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Sniffers: Fluid-Dynamic Sampling for Olfactory Trace Detection in Nature and Homeland Security—
Abstract
Vertebrates aim their noses at regions of interest and sniff in order to acquire olfactory trace signals that carry information on food, reproduction, kinship, danger, etc. Inverte- brates likewise position antennae in the surrounding fluid to acquire such signals. Some of the fluid dynamics of these natural sensing processes has been examined piecemeal, but the overall topic of sniffing is not well investigated or understood. It is, however, important for several human purposes, especially sampling schemes for sensors to detect chemical and biological traces in the environment. After establishing some background, a general appraisal is given of nature's accomplishments in the fluid dynamics of sniffing. Opportunities are found for innovation through biomimicry. Since few artificial ("elec- tronic") noses can currently sniff in the natural sense, ways are considered to help them sniff effectively. Security issues such as explosive trace detection, landmine detection, chemical and biological sniffing, and people sampling are examined. Other sniffing ap- plications including medical diagnosis and leak detection are also considered. Several research opportunities are identified in order to advance this topic of biofluid dynamics. Though written from a fluid dynamics perspective, this review is intended for a broad audience. fDOI: 10.1115/1.1891146g
... If air temperature is sufficiently colder than skin temperatures, scent is transported to the top of the head and shoulders and into the air above by the human thermal plume (1,4). For a walking person in calm air, all scent on the body in the thermal plume would be incorporated into a turbulent wake behind the person (8,9). The wake would quickly carry some of the scent to the ground directly behind the person while the rest would remain airborne. ...
... Continued production of VOCs by particles provides a process which can increase the density of scent along the trail. It has been shown that, during sniffing, strong exhalation jets from the dog's nose can remove particles from surfaces and that some of these airborne particles are inhaled (9,14). It is also likely that dogs use these jets to remove VOCs from surfaces and inhale them (9). ...
... It has been shown that, during sniffing, strong exhalation jets from the dog's nose can remove particles from surfaces and that some of these airborne particles are inhaled (9,14). It is also likely that dogs use these jets to remove VOCs from surfaces and inhale them (9). This examination of the behavior of particles and VOCs on trails may help to partially explain the ease and difficulties that TDs have when trailing under some conditions noted below. ...
... Diverse examples of respiratory-type flows occur throughout the natural world. Both aquatic and terrestrial animals use respiratory-type flows to sample the environment for metabolic intake or to intercept sensory information [1,2]. Other respiratory-type flow examples are analogous to the processes of respiration and olfaction, in which the lung capacity dictates the tidal volume exchanged through the mouth or nostrils. ...
... Previous studies have argued that flow dynamics associated with olfaction are partly responsible for the ability of many animals to detect chemical signals at astonishingly low concentrations which rival even the most sensitive analytic equipment [1]. Among these studies, some have considered not only the complicated flow patterns occurring internal to the nares, but also the external flow patterns. ...
... For example, the aerodynamic reach of the inhale allows for stereo sensing in both canine [43] and rat [10] nasal morphology. In canines, a directed jet during the exhale allows them to entrain fluid samples from further afield and liberate odors from surfaces for enhanced detection [1,[43][44][45]. Interestingly, canine sniff rates tend to vary little between 4-7 Hz whereas tidal volume scales with body size [46]. ...
Respiratory-type flows facilitate the exchange of fluid through an orifice in many natural and engineered environments. The external flow dynamics for an idealized respiratory-type flow, consisting of periodic inhalation and exhalation of a fixed tidal volume of fluid through a circular orifice at the end of a tube, are investigated. In both numerical and experimental investigations, inertial effects produce asymmetric inhalant and exhalant flow structures, resulting in a dynamic exchange of fluid volume across the orifice. A Lagrangian approach is used to quantify the reinhalation ratio r I , defined as the amount of exhaled fluid that is subsequently reinhaled. Results show that these flow structure asymmetries and hence r I are strongly sensitive to Reynolds number, and, to a lesser extent, Womersley number or Strouhal number. At low Reynolds number, where viscous effects dominate, we observe flow kinematics similar to an ideal source or sink and the exchange ratio asymptotes to an upper limit. As the inertial effects become more dominant with increasing Reynolds number, we instead observe jetlike flow structures and a rapid decrease in r I. In the context of biological sensory and metabolic processes, these results suggest organisms can optimize the exchange of fluid with surrounding environment by modulating the asymmetries in the flow structures arising during olfactory and respiratory activity.
... vestibule and nostril act as a flow diverter, ejecting an expired air jet that is directed ventral-laterally (downward and to the side). When sniffing a surface, the warm expired air jets mechanically disturb and volatilize latent odorant, thereby liberating vapor that may then be inspired 22,36 . Additionally, the direction of the expired air jet from each nostril serves two primary functions when sniffing a surface: 1) it prevents the blow-off of odorant sample directly in front of the nostril (enabling it to be subsequently inspired), and 2) it entrains, or draws, air in front of the nose toward the nostril, effectively extending the aerodynamic reach of the nose over simple inspiration alone. ...
... The external aerodynamics of scent acquisition have also been investigated in the same species -dogs 36,37 , rodents 56 , and humans 55 . Based on flow visualization studies of canine sniffing 37 , Settles 22 first suggested the use of jet-assisted odorant sampling for artificial chemical sensing (e.g., using a method for augmenting aerodynamic reach that was first patented by Aaberg 57 ). However, to our knowledge, no study to date has successfully incorporated bio-inspired active sniffing in a man-made device and quantified the influence on chemical detection performance. ...
... This is an operational benefit that allows the detector (in this case the dog) to sense the presence of an odor from greater distances and further augmented with anterior directionality, thereby increasing the effective areal coverage rate of the detection system. Second, the warm expired air jets disturb an odor source and volatilize latent odorant that may then be inspired 22,36 . Taken together, the external flow patterns that develop during sniffing are likely one of the reasons that dogs have been observed to "scan" a ground plane in the anterior-posterior direction when sniffing a scent source 37 . ...
Unlike current chemical trace detection technology, dogs actively sniff to acquire an odor sample. Flow visualization experiments with an anatomically-similar 3D printed dog’s nose revealed the external aerodynamics during canine sniffing, where ventral-laterally expired air jets entrain odorant-laden air toward the nose, thereby extending the “aerodynamic reach” for inspiration of otherwise inaccessible odors. Chemical sampling and detection experiments quantified two modes of operation with the artificial nose-active sniffing and continuous inspiration-and demonstrated an increase in odorant detection by a factor of up to 18 for active sniffing. A 16-fold improvement in detection was demonstrated with a commercially-available explosives detector by applying this bio-inspired design principle and making the device “sniff” like a dog. These lessons learned from the dog may benefit the next-generation of vapor samplers for explosives, narcotics, pathogens, or even cancer, and could inform future bio-inspired designs for optimized sampling of odor plumes.
... The suction system under investigation here has some similarity to mammalian sniffing. By sniffing the air or water into nostrils, the sampling volume entering the nostrils is increased [17]. Moreover, the increased flow velocity over or inside the olfactory organ reduces the thickness of the boundary layer, and therefore, molecular diffusion to the surface of the olfactory organ through the boundary layer is promoted [17]. ...
... By sniffing the air or water into nostrils, the sampling volume entering the nostrils is increased [17]. Moreover, the increased flow velocity over or inside the olfactory organ reduces the thickness of the boundary layer, and therefore, molecular diffusion to the surface of the olfactory organ through the boundary layer is promoted [17]. However, even if the odor is sucked into the nostrils and the thickness of the boundary layer is reduced, no signal can be obtained if the flow path of the sucked odor passes far outside the boundary layer of the olfactory epithelium. ...
... The sensor response curves obtained with the slits illustrate the importance of ensuring the contact of the sucked water sample with the sensor surface (or at least the contact with the outer perimeter of the boundary layer around the sensor electrode). The slits might be analogous to the complicated but sophisticated structure in the mammalian nasal cavity that guides the sucked air along specific paths for sensitive odor detection [17]. Figure 7 were compared to see the effects of the number of the slits and their widths on the chemical detection at the sensors. ...
This paper investigates the effect of active water sampling to enhance chemical reception for small underwater robots. The search for a chemical source in a stagnant water environment is not an easy task because the chemical solution released from the source stays in the close vicinity of the source. No signal is obtained even if a robot with chemical sensors is placed a few centimeters from the chemical source. In the system under study, four electrochemical sensors are aligned in front of a suction pipe that draws water samples from the surroundings. Owing to the smooth laminar flow converging to the suction port, the streak of the chemical solution drawn to the sensors is shaped into a thin filamentous form. To prevent the chemical solution from passing between the sensors without touching their surfaces, slits are placed in front of the sensors to guide the incoming chemical solution from different directions to the corresponding sensors. A chemical source can be located by moving the system in the direction of the sensor showing the largest response. It is also shown that the chemical reception at the sensors can be significantly enhanced when the system is wobbled to introduce disturbances.
... The use of a detection dog and location of one or more of the target odors will typically go as follows: (1) the dog is deployed with a search command. (2) Casting stage: the dog will start sampling the air currents trying to locate an odor plume. As air current carries the target odor, dogs locate the edges of the odor plume and try to find the source. ...
... Current literature defines three search phases in dogs (i.e., Thesen et al. 58 : initial, deciding, and tracking phases), where each phase differs from the other based on speed, sniff frequency, and time spent sniffing. The addition and use of distinct casting and localizing stages in this study bridges the gap in terminology from tracking and trailing to the wider olfactory literature 2,11,12,[18][19][20][21][22]26,58 . Therefore, the terms used in the current study better classify and describe the search stages dogs iterate through as they navigate the odor plumes they search. ...
Trained detection dogs have a unique ability to find the sources of target odors in complex fluid environments. How dogs derive information about the source of an odor from an odor plume comprised of odorants with different physical properties, such as diffusivity, is currently unknown. Two volatile chemicals associated with explosive detection, ammonia (NH3, derived from ammonium nitrate-based explosives) and 2-ethyl-1-hexanol (2E1H, associated with composition C4 plastic explosives) were used to ascertain the effects of the physical properties of odorants on the search behavior and motion of trained dogs. NH3 has a diffusivity 3.6 times that of 2E1H. Fourteen civilian detection dogs were recruited to train on each target odorant using controlled odor mimic permeation systems as training aids over 6 weeks and then tested in a controlled-environment search trial where behavior, motion, and search success were analyzed. Our results indicate the target-odorant influences search motion and time spent in the stages of searching, with dogs spending more time in larger areas while localizing NH3. This aligns with the greater diffusivity of NH3 driving diffusion-dominated odor transport when dogs are close to the odor source in contrast to the advection-driven transport of 2E1H at the same distances.
... Such commonalities include the sinusoidal swings back and forth during trail and plume following 5,13 and casting-like behavior upon losing the scent 13,19 . However, surface-bound odorants are also distinct from airborne odorants in that disturbing the bound medium can increase the concentration of the odorant available to detect [22][23][24] , which may drive sniffing 13 and antennal sampling strategies 5 when exploring odor trails. ...
... Compared to odor plume tracking there were notable differences in strategy that were also observed while following surface-bound odor trails. For animals that smell using respiration, they are able to disturb the surface by sniffing, increasing the amount of scent available for tracking [22][23][24] . Similarly, animals with antennae are able to probe the ground in front of them 50 , mechanically disturbing the surface while sampling the trail. ...
One of the important subsets of odor sources used in olfactory navigation is surface-bound sources, which can broadly take the form of point sources or trails. Odor trails, in particular, have been observed to be highly relevant components of olfactory-based navigation for species as broadly distributed as dogs and ants. Here, we present an automated treadmill setup capable of dynamically printing odor trails of arbitrary lengths and configurations, and with closed-loop control of speed based on the animal's movement. We used this setup to characterize trail-following behavior in locusts (Schistocerca americana). The free-moving behavior of the locusts is more naturalistic and is richer in plumbable data than many traditional assays. We reveal broad classes of behavioral walking motifs and their dynamic transitions as locusts pursue or avoid an odor trail. Furthermore, we show how these motifs vary across individuals, with the identity of the odorant and with respect to the sex of the organism. Our dataset and analyses provide a first demonstration that this model organism is capable of robust odor trail following, and provides a comprehensive analysis of the dynamic motifs that underlie this behavioral capability.
... To receive olfactory information for sensory processing, odorants must enter the inlet nostril, pass through the incurrent channel and across the olfactory rosette where it then binds with an olfactory receptor neuron on the lamellae that sends a signal to the brain via the olfactory bulb . Therefore, the shape, size, and position of a fish's nostrils determine how odor is captured and transported (Cox et al. 2008;Settles, 2005). Fishes will orient into an odor plume by comparing the bilateral odor concentration differences of their paired nostrils, turning towards the higher concentration, or the nostril that is stimulated first (Atema, 1971; Bardach, Todd, and Crickmer, 1967; Gardiner and Atema, 2010; Johnson and Teeter, 1985; Mathewson and Hodgson, 1972;Tester, 1963). ...
... This layer acts a barrier to odor transport. While the mechanisms for which odor is harnessed into the batoid nose has not been explored, it is hypothesized that batoid olfaction relies upon one or a combination of the following mechanisms: RAM ventilation, the buccopharyngeal pump, pressure differences, or some other form of unknown mechanical agitation (movement of jaw bones) (Settles, 2005;Cox, 2008). have their nostrils positioned more anteriorly on their head, which may make odor capture easier. ...
Batoid fishes (rays, skates, sawfishes and guitarfishes) are macrosmatic, meaning they rely on their sense of smell as one of the primary senses for survival and reproduction. Olfaction is important for long-distance tracking and navigation, predator and prey recognition, and conspecific signaling. However, the mechanisms by which batoids harness odorants is unknown. Without a direct pump-like system, it is hypothesized that batoids irrigate their nostrils via one or a combination of the following: the motion pump, buccopharyngeal pump, pressure (ex. pitot-like mechanism), or a shearing force (ex. viscous entrainment). These mechanisms rely on the size, shape, and position of the nostrils with respect to the head and to each other. Batoids are united as a group by their dorsoventrally compressed body plans, with nostrils on the ventral side of their body. This position presents several challenges for odor capture and likely limits the effectivity of the motion pump. Batoid fishes display an expansive nasal morphology, with inlet nostrils ranging from thin, vertical slits to wide, horizontal ovals to protruding, tube-like funnels, and more. In this paper, a morphometric model is developed to quantify the vast diversity in batoid nose shapes, sizes, and positions on the head in an ecological and functional framework. Specifically, swimming mode, lifestyle, habitat, and diet are examined for correlations with observed nasal morphotypes. Morphometric measurements were taken on all 4 orders present in Batoidea to broadly encompass batoid nasal diversity (Rhinopristiformes 4/5 families; Rajiformes 2/4 families; Torpediniformes 4/4 families; Myliobatiformes 8/11 families). All batoid external nasal diversity was found to be categorized into 5 major morphological groups and were termed: flush nare [circle, comma, intermediate], open nare, and protruding nare. Several morphometric traits remained significant when accounting for shared ancestry, including the position and angle of the nostril on the head, the width of the inlet hole, and the spacing of the nostrils from each other. These measurements were found to be closely correlated and statistically significant with the swimming mode of the animal. This study provides the first crucial step in understanding batoid olfaction, by understanding the diversity of the morphology of the system. Because odor capture is a strictly hydrodynamic process, it may be that factors relating more directly to the fluid dynamics (i.e., swimming mode, velocity, Reynolds number) may be more important in shaping the evolution of the diversity of batoid noses than other ecological factors like habitat and diet.
... Dogs have been used for centuries for tracking and hunting due to their excellent sense of smell and the ease with which they can be trained (Settles, 2005). Dogs have an olfactory epithelium (within which the olfactory receptor neurons are located) that sits behind the respiratory region of the nose, so that the bulk of the inhaled air does not pass through it. ...
... The human olfactory epithelium contains considerably fewer olfactory receptor neurons and is located within the main nasal cavity, which is optimised for breathing. Dogs are said to sniff with a frequency of between 4 Hz and 7 Hz (Craven et al., 2010) but do sometimes take longer sniffs at 0.5 Hz (Settles, 2005). This means that they will not be able to differentiate plume structures with frequencies higher than this. ...
Air movement in indoor spaces can be complex due to large regions with no dominant flow direction and low mean velocities. Therefore, vapour released from an explosive indoors would be expected to result in a high degree of temporal and spatial variability in concentration. To improve canine detection capability, specifically training equipment, training methods and concepts of use, the science of vapour signatures in enclosed spaces needs to be improved.
Large-eddy simulation has been used to study the vapour field in a benchmark test room. The work provides insight into vapour behaviour within indoor spaces and results have been interpreted in relation to vapour detection using dogs. For the test room, it was shown that vapour concentrations reduce rapidly within a short distance from the source. However, the concentration fluctuations, which occur at frequencies that a dog should be able to detect, can be significantly greater than the mean concentration.
Due to the low volatility of many explosives, the vapour they produce will readily partition onto surfaces altering the concentrations in the room. A multi-layer vapour sorption model based on computational fluid dynamics (CFD) was validated. The CFD sorption model and a well-mixed sorption model were applied to the benchmark test room. It was shown, for a moderately high volatility explosive, that absorption had little effect on the well-mixed concentration but could have a significant effect on concentrations in the vicinity of the absorbing surface.
When it is not possible/practical to build a CFD model, eddy diffusion models can be used to rapidly predict the spatially resolved concentration field indoors. However, there is uncertainty over the parameter that governs mixing, the eddy diffusion coefficient, De. Work has been carried out to develop a method to predict De for mechanically ventilated, isothermal rooms. It was found that De is a function of the air flow rate, room volume and number of air supply vents only. This will enable eddy diffusion modelling to be used with more confidence in the future to plan canine training experiments or to interpret detection results. <br/
... In fishes at least, odorant transport has received little attention. The knowledge gained from studying odorant transport in fishes may also be applied to the design of artificial chemical sensors (Rouhi, 1997;Settles, 2005). ...
... The knowledge from conclusions 3) and 4) may be used to devise a rigid, ultrasensitive microfluidic chemical sensor (Settles, 2005). ...
The olfactory epithelium of the sea catfish, Ariopsis felis, is found on a pinnate array of lamellae (the olfactory rosette) housed within a nasal chamber. The nasal anatomy of A. felis suggests an ability to capture external water currents. We prepared models from X-ray micro-computed tomography scans of two preserved specimens of A. felis. We then used dye visualisation and computational fluid dynamics to show that an external current induced a flow of water through a) the nasal chamber and b) the sensory channels of the olfactory rosette. The factors responsible for inducing flow through the nasal chamber are common to fishes from two other orders. The dye visualisation experiments, together with observations of sea catfishes in vivo, indicate that flow through the nasal chamber is regulated by a mobile nasal flap. The position of the nasal flap – elevated (significant flow) or depressed (reduced flow) – is controlled by the sea catfish's movements. Flow in the sensory channels of the olfactory rosette can pass through either a single channel or, via multiple pathways, up to four consecutive channels. Flow through consecutive sensory channels (olfactory resampling) is more extensive at lower Reynolds numbers (200 and 300, equivalent to swimming speeds of 0.5–1.0 total lengths s⁻¹), coinciding with the mean swimming speed of the sea catfishes observed in vivo (0.6 total lengths s⁻¹). Olfactory resampling may also occur, via a vortex, within single sensory channels. In conclusion, olfactory flow in the sea catfish is regulated and thoroughly sampled by novel mechanisms.
... Animals perceive odors when the odor molecules actually reach the surfaces of the olfactory receptor cells. In order to achieve sensitive odor detection, many animals make efforts to collect odor molecules effectively onto the olfactory receptor cells [9]. It is expected that mimicking such odor collection behavior will lead to great improvements in chemical detection and chemical localization abilities of the robots [9]. ...
... In order to achieve sensitive odor detection, many animals make efforts to collect odor molecules effectively onto the olfactory receptor cells [9]. It is expected that mimicking such odor collection behavior will lead to great improvements in chemical detection and chemical localization abilities of the robots [9]. In rivers and tides, odor molecules are transported by water flow and form odor plumes. ...
This paper describes a wheeled underwater robot developed for locating chemical sources autonomously under stagnant flow conditions. In still water, the released chemical stays in the immediate vicinity of the source location. The search for chemical sources under such conditions is extremely laborious since the presence of a chemical source cannot be detected from a distant place. The chemical sensors on the robot show no response unless a chemical substance released from the source arrives at the sensors. Crayfish in search of food are known to actively generate water currents by waving their small appendages with a fan-like shape. It is considered that the generated water currents help their olfactory search. The smell of food is carried to their olfactory organs from the surroundings by the generated flow, and then is perceived. The robot presented in this paper employs arms mimicking the maxillipeds of a crayfish to generate water currents and to draw chemicals to its sensors. By waving the arms vertically, a three-dimensional flow field is generated and water samples are drawn from a wide angular range. The direction of a chemical source can be determined by comparing the responses of four laterally aligned electrochemical sensors. Experimental results show that the flow field generated by the maxilliped arms is more effective in collecting chemical samples onto the sensors than that generated by a pump. The robot equipped with the maxilliped arms can detect the presence of a chemical source even if the source is placed off the trajectory of the robot.
... Macrosmatic animals, such as dogs, have several features giving them a well-developed sense of smell. Their larger noses, greater surface area along their olfactory epithelium, and more active olfactory genes contribute to their enhanced olfactory abilities (Craven et al., 2009;Kokocioska-Kusiak et al., 2021;Settles, 2005). Within the nasal cavity, air flow taken in through sniffing is divided between separate olfactory and respiratory pathways. ...
Dogs are utilized in forensic science for their extensive scent detection capabilities. They are often considered the “gold standard” in field detection for targets such as illicit drugs and explosives. Despite their prevalence in the field, relatively little is known about how dogs interact with and transport volatile organic compounds through their olfactory system. In this study, two groups of dogs were utilized – Sport detection dogs (n=19) that participate in the National Association of Canine Scent Work and have achieved advanced standing through training and successful search competitions and law enforcement explosive detection dogs (n=8) which were included for comparison. Both groups were presented with two target odorants having differing molecular properties, 2-ethyl-1-hexanol and ammonia, two non-target odorants, 1-bromooctane and methyl benzoate, and a negative control. Canines were tested prior to experience with the target odorants, when all odorants were novel, after some brief training with the target odorants, and after longer training time with the target odorants. The non-target odorants were never used in training. Sniffing was measured using flow sensors embedded in a wall immediately in front of the odorants held in a closed cylinder. Sensor data was used to calculate sniff flow rate, frequency (sniffs per seconds) and volume. Results indicated no difference in sniffing dynamics between target odorants; however, sniffing frequency increased significantly with increased experience with the target odorants (Wilcoxon rank sum exact test, W= 148, p=6×10-5). Sniff volume and flow rate showed a positive correlation to body mass for all sport detection dogs (slope = 2.71, F(1,17)= 9.48, p= 0.007, R2= 0.32), though the R2 was low, indicating other factors at play. Law enforcement detection dogs were shown to take in significantly higher mean total sniff volumes (Wilcoxon rank sum exact test: W= 7, p=10-4) and volume flow rates (Wilcoxon rank sum exact test: W= 5, p=6×10-5) compared to the sport detection dogs, but the sniff frequency remained similar for both groups.
... Studie Settlese a McGanna [88,89] dále dokládají způsob, kterým se "raft" dostává do okolí. ...
Předkládaná dizertační práce je zaměřena na studium molekulárního profilu lidského kožního pachu pomocí metod plynové chromatografie ve spojení s hmotnostní detekcí (GC-MS a GC×GC-MS). V rámci této práce je představeno několik dílčích experimentů, zabývajících se optimální přípravou pachových vzorků pro chemickou analýzu (nalezení vhodných sorpčních materiálů, vhodných rozpouštědel pro následnou extrakci pachových sloučenin, způsobu koncentrování vzorků, či testování pachů z různých částí těla). Několik experimentů se pak věnuje možnostem provedení skupinové identifikace (konkrétně diskriminaci pohlaví) ze vzorků lidského pachu, a to za použití různých způsobů provedení analýzy. Poslední popisovaný a nejrozsáhlejší experiment (504 vzorků lidského pachu od 40 dobrovolníků, v nichž bylo sledováno 67 látek) se pak zabývá nejen skupinovou identifikací, ale i identifikací individuální. Za pomoci matematické metody podpůrných vektorů byly vytvořeny modely s přesností určení pohlaví kolem 90 %, klasifikační modely pro určení jednotlivce pak dosahovaly přesnosti kolem 70 %.
Dosažené výsledky ukazují, že detailní analýza molekulárního profilu pachu jedince umožňuje jak skupinovou, tak individuální identifikaci člověka, nicméně pro budoucí použitelnost ve forenzní praxi je třeba provést další experimenty, s cílem vybudovat rozsáhlou mezinárodní databázi pachových vzorků odebraných, připravených a zanalyzovaných unifikovaným způsobem tak, aby byly pachové vzorky porovnatelné a umožňovaly vytvoření přesných (více jak 95%) klasifikačních modelů.
... Skin flakes form the greatest source of particulate matter within people's personal breathing zones and can gain high charge. Around 6000e50,000 skin flakes of between 5 and 50 mm in size can enter the nasal passages per liter of air inhaled [90]. Approximately between 5 and 10% of all skin scales shed from the human body can harbor bacteria [91]. ...
There are a growing number of studies investigating how grounding (earthing) the body may benefit biological performance and aid the treatment of non-communicable diseases. Research also indicates how biological grounding initiatives can sometimes be compromised, or inappropriate, and the need to take additional factors into account as potential contributory factors, or confounders, to expected results. It is proposed that expanding electromagnetic hygiene measures beyond biological grounding alone may help reduce spread of communicable diseases, incidence of respiratory conditions, neurodegenerative disease and all-cause mortality. Identifying potential synergies that exist could enable multilevel interventions to further increase the efficacy of measures. It is hoped that this review will help act as a catalyst to inspire and inform multi-disciplinary research within these topic areas, best practices and policies to help drive medical innovation, reduce health burdens, improve bioelectromagnetic-based therapies, and influence the general design of the built environment and next-generation technologies.
... Examples include chemokinetic navigation of motile cells, foraging of animals, [6] and odorsniffing robots. [7,8] For micrometer-sized agents, the signal-tonoise ratio of sensing chemical gradients is low at subnanomolar concentrations, preventing effective directed che-motaxis, nonwithstanding the fact that the chemical signal itself is above detection threshold, and thus indicates the proximity of a target releasing signaling molecules. ...
We theoretically address minimal search strategies of self-propelled particles towards hidden targets in three-dimensional space. The particles can sense if targets are close, e.g., by detecting released signaling molecules, but they cannot deduce directional cues. We investigate composite search strategies, where particles switch between extensive outer search and intensive inner search; inner search is started when proximity of a target is detected and ends when a certain inner search time has elapsed. In the simplest strategy, active particles move ballistically during outer search, and transiently reduce their directional persistence during inner search. In a second, adaptive strategy, particles exploit a dynamic scattering effect by reducing directional persistence only outside a well-defined target zone. These two search strategies require only minimal information processing capabilities, yet increase target encounter rates substantially. The optimal inner search time scales as power-law with exponent -2/3 with target density, reflecting a trade-off between exploration and exploitation.
... However, the difference lies in the fact that dogs have a superior olfactory capability which is reportedly 10,000-100,000 times better than that of humans (Sankaran, Khot, & Panigrahi, 2012;Walker et al., 2003;Walker et al., 2006). Additionally, their short voluminous sniffing and unique nasal airflow pattern allows for greater amounts of odorants to enter dogs' nostrils and generate an enhanced response by triggering the large olfactory bulbs in their brain (Craven, Paterson, & Settles, 2010;Settles, 2005). These odorants comprise of volatile chemical compounds emitted by the odor source. ...
Cadaver‐detection dogs (CDDs) are an essential tool for the search and detection of human remains. In order to enhance their search capability, CDDs are regularly trained on natural and synthetic training aids. The odor profile of these training aids comprises a range of volatile organic compounds (VOCs) which is intended to resemble those produced by a decomposing body. It is currently unknown if detector dogs respond to the same stimuli and whether it is a specific VOC or a suite of decomposition‐related VOCs as their target odor. This review summarizes the VOCs that have been detected in various CDD training aids such as blood, human remains, decomposition fluid, soil, buried remains, textile, and synthetic formulations. Additionally, it discusses the reported capability of CDDs to respond to each of these training aids. The purpose of this review is to understand the variability of VOCs in CDD training aids and the response of CDDs to this wide range of compounds. Additionally, this review attempts to determine if there is a specific training aid to which CDDs respond preferentially. Such a review will assist to establish better practices for CDD training since no standardized practices exist globally.
This article is categorized under:
• Crime Scene Investigation > Special Situations and Investigations
• Forensic Anthropology > Taphonomic Changes and the Environment
• Forensic Medicine > Death Scene Investigation
Abstract
Compounds detected by modern instruments indicating the potential volatile organic compounds detected by cadaver‐detection dogs from decomposition related material used as training aids.
... Bu sistem koku yayan maddelerin solunmasının ardından oluşan sinirsel dürtülerin yorumlaması şeklinde gerçekleşen biyolojik bir işlemdir. Burnunun oryantasyonu nedeniyle bir köpeğin koklama sıklığı 5Hz civarındadır, bu da dakikada yaklaşık 300 nefese karşılık gelmektedir (41). Köpeğin burnundan soluduğu bu hava hacmi yaklaşık 60 mL/sn'dir (42). ...
Uyuşturucu, patlayıcı maddeler veya insan vücudu tarafından serbest bırakılan uçucu organik birleşiklerin kokusunun belirlenebilmesi kaçakçılığın, terörün, canlı veya ölü bireyin varlığını gösterebileceği gibi bir kişiyi belirli bir yer veya nesneyle ilişkilendirebileceği için ceza soruşturmalarında artan bir öneme sahiptir. Her ne kadar koku tespitinde kullanılan araç ve gereçler son yıllarda önemli ölçüde iyileşmiş, biyolojik detektörler olan köpekler ile rekabet edebilecek seviyeye yaklaşmış olsalar da, köpeklerin hız, çok yönlülük, kokuyu takip etme becerisi ve ayırt edici özelliklerinden dolayı hala koku kaynağının tespitinde ilk tercih olarak kullanıldıkları kabul edilmektedir. Uçucu organik birleşiklerin tespitinde kaydedilen ilerlemelerin yanı sıra, cihazlar ve köpekler için standardize uygulamaların geliştirilmesi, kokunun kanıt olarak güvenilirliğini sürekli olarak artırmaktadır. İyi uygulama kılavuzlarının geliştirilmesi, ilgilenilen uçucu organik birleşiklerin tespit edilmesindeki duyarlılık, seçicilik ve güvenilirliğinin artması ile bugün için sadece takip ve yakalamada kullanılan yöntemin ceza yargılamasında kabul edilebilir bir adli kanıt olarak kullanımını olanaklı kılacaktır. Bu çalışmada koku algılamasında rolü olan anatomik yapılar, histolojik ve fizyolojik mekanizma ile halen bu süreçte kullanılan temel aktörler olan köpeklerin anatomik, fizyolojik, genetik farklılıkları, eğitimleri ve eğiticileri ile olan ilişkileri, sınırlamaları, bu alanda kullanılan analitik cihazların temel prensip ve kapasiteleri ile kaydedilen ilerlemeler araştırılmış ve okuyucuya derli toplu bir şekilde sunulması amaçlanmıştır.
... Studies have shown that the reach of a suction inlet can be increased by discharging auxiliary jets to the sides from the inlet port [17]. Settles proposed to use such a device as a sniffer for chemical sensors [5]. In [18], an auxiliary jet flow is used to generate swirling flow. ...
Here, we report on computational fluid dynamics (CFD) simulations conducted to develop a chemical sample collection device inspired by crayfish. The sensitivity of chemical sensors can be improved when used with a sniffing device. By collecting fluid samples from the surroundings, all solute species are also collected for the sensor. Crayfish generate jet-like water currents for this purpose. Compared to simply sucking water, food smells dissolved in the surrounding water can be more efficiently collected using the inflow induced by the jet discharge because of the smaller decay of the inflow velocity with the distance. Moreover, the angular range of water sample collection can be adjusted by changing the directions of the jet discharge. In our previous work, a chemical sample collection device that mimics the jet discharge of crayfish has been proposed. Here, we report CFD simulations of the flow fields generated by the device. By carefully configuring the simulation setups, we have obtained simulation results in which the angular ranges of the chemical sample collection in real experiments is well reproduced. Although there are still some discrepancies between the simulation and experimental results, such simulations will facilitate the process of designing such devices.
... The exterior flow approaching an inlet orifice is of interest in a variety of contexts: pipettes, [11][12][13] aerosol and water samplers, 14,15 synthetic jets, 16 and organismal predation, feeding, and/or respiration processes. [17][18][19][20][21][22][23][24][25] While these studies explore many aspects of the exterior flow, most feature simplifications or complexities that complicate a mechanistic understanding of viscous inhalant flow hydrodynamics. Numerical modeling 1 recently quantified the effects of Re and extraction height h * on the time-evolving exterior flow and showed marked differences in exterior flow kinematics and dynamics across the Re-h * parameter space. ...
High dynamic velocity range (DVR) flows are challenging to measure with traditional double-pulse particle image velocimetry (PIV) since no single correlation time scale optimally resolves particle displacements over the entire DVR of interest. Inhalant flows are ubiquitous in engineering and biology and feature a high DVR as they draw viscous fluid through an orifice from a surrounding reservoir since large interior tube velocities rapidly attenuate with exterior distance from the inhalant orifice. We conducted a high-DVR PIV study of viscous inhalant flow hydrodynamics by developing and applying a multi-time-lag type processing scheme to construct DVR-enhanced flowfields. The algorithm adapts existing multi-time-lag type schemes into one that is well suited for slowly evolving flows with a persistent spatiotemporal structure. Correlation analyses between image pairs across two optimized time scales produce a pair of correlation maps well suited for resolution of targeted high and low measurement velocities. An evaluation map based on the best statistical relative strength of the local correlation peak amplitude and peak ratio is then used to spatially reconstruct a single DVR-enhanced velocity field with a DVR on the order of 1000:1. Numerical simulations show close agreement with measured flows everywhere following DVR enhancement, and the high-DVR PIV results reveal marked differences in the exterior flow kinematics and dynamics due to varying viscous and boundary interaction effects. The inlet velocity profiles at the tube orifice are highly sensitive to the Reynolds number within this range (1–100) and show notable departures from classically assumed uniform pipe entry profiles, impacting flow development lengths downstream.
... [1][2][3][4][5][6][7] Another sampling technique is aerodynamic sampling, a noncontact approach to collecting material from surfaces that relies on fluid dynamics to liberate and transport particulates. [8][9][10] While the canine is a highly sophisticated example of sampling detection from nature, 11,12 manmade examples include physical screening of both people 13,14 and belongings. 15 Wipe sampling is typically performed by a human operator and is thus prone to a high level of variability in collection efficiency. ...
This work describes a high-speed imaging system that enables the microscopic visualization of the removal and collection of micrometer-sized particles from surfaces during wipe sampling and aerodynamic sampling events. The system features a high-speed digital camera, microlens, custom sample mount and sampling sled, and an illumination source. This imaging system enables direct visualization of wipe-particle and particle-particle interactions during sampling and provides insights relevant to the dynamics of particle removal and collection. Examples of common and adhesive-modified wipe materials sampling polymer microspheres and an explosive-laden fingerprint are given, along with visualization of particle removal via air jet impingement.
... R ESEARCH in robot olfaction has received wide attention to address many challenges, some of which include detection of hazardous gases in mines, tunnels and industrial setup, search and rescue of victims, forest fire detection and firefighting [1]- [3], etc. Recently, extra-terrestrial odor source localization via autonomous agents has been carried out on Mars [4], [5]. ...
This paper presents an investigation of the task of localizing an unknown source of an odor by heterogeneous multiagent systems. A hierarchical cooperative control strategy has been proposed as a potential candidate to solve the problem. The agents are driven into consensus as soon as the information about the location of source is acquired. The controller has been designed in a hierarchical manner of group decision making, agent path planning, and robust control. In group decision making, the particle swarm optimization algorithm has been used along with the information of the movement of odor molecules to predict the odor source location. Next, a trajectory has been mapped using this predicted location of source, and the information is passed to the control layer. A variable structure control has been used in the control layer due to its inherent robustness and disturbance rejection capabilities. Cases of movement of agents toward the source under consensus and parallel formation have been discussed. The efficacy of the proposed scheme has been confirmed by simulations.
... R ESEARCH in robot olfaction has received wide attention to address many challenges, some of which include detection of hazardous gases in mines, tunnels and industrial setup, search and rescue of victims, forest fire detection and firefighting, [1]- [3], etc. Recently, extra-terrestrial odour source localisation via autonomous agents has been carried out on Mars [4], [5]. ...
This paper presents an investigation of the task of localising unknown source of an odour by heterogeneous multiagent systems. A hierarchical cooperative control strategy has been proposed as a potential candidate to solve the problem. The agents are driven into consensus as soon as the information about the location of source is acquired. The controller has been designed in a hierarchical manner of group decision making, agent path planning, and robust control. In group decision making, Particle Swarm Algorithm has been used along with the information of the movement of odour molecules to predict the odour source location. Next, a trajectory has been mapped using this predicted location of source, and the information is passed to the control layer. A variable structure control has been used in the control layer due to its inherent robustness and disturbance rejection capabilities. Cases of movement of agents towards the source under consensus, and parallel formation have been discussed. The efficacy of the proposed scheme has been confirmed by simulations.
... In principle, a trailing canine can only find and follow a trail from the starting point if a searched person was there and has moved away from this location in a manner which allows an exchange of the released human scent trace with the environment [5][6][7][8][9]. This is in accordance with the Locard's exchange principle, which states that a perpetrator cannot leave a crime scene without leaving numerous traces [10]. ...
Specially trained dogs have long been used by law enforcement agencies to help in criminal investigations and in searching for missing persons. Still, it is unclear which components of human scent released into the environment contribute to successful searches of individuals. In this study, saliva and axillary sweat samples were taken from a total of 190 people. Additionally, DNA was extracted from whole blood of seven different people and used as an odour sample as well. Overall 675 tests (trails) were performed during a period of 18 months. The ability to track individuals with the odour samples mentioned above was examined with seven dogs, four of which were specially-trained dogs (mantrailer) from the Saxony Police. Results indicated that specially-trained police dogs can track a person with an average success rate of 82% and correctly identify the absence of an odour track with an average success rate of 97% under various conditions. Private rescue dogs were less successful with an average success rate of 65% and 75% respectively. These data suggest that the potential error rate of a well-trained handler team is low and can be a useful tool for law enforcement personnel. Saliva, as a reference odour source, was found to be particularly suitable for the search. The results of the study suggest that the components contained in axillary sweat, saliva and DNA extracted from whole blood are sufficient, serving as a key stimulus for individualized searches.
... The most anterior portion of the canine nose (the naris), however, is mobile and deforms during sniffing. During inspiration the naris is relaxed and undilated, but during the expiratory phase of sniffing the nostril flares to facilitate the vectoring of a ventrolaterally directed air jet from the nose (Settles et al. 2003;Settles 2005). Simulating nostril flaring during expiration is possible using CFD with dynamic mesh motion in an arbitrary Lagrangian-Eulerian (ALE) reference frame (e.g., see Cieri et al. 2014, who used similar techniques). ...
Nasal airflow plays a critical role in olfaction by transporting odorant from the environment to the olfactory epithelium, where chemical detection occurs. Most studies of olfaction neglect the unsteadiness of sniffing and assume that nasal airflow and odorant transport are "quasi-steady," wherein reality most mammals "sniff." Here, we perform computational fluid dynamics simulations of airflow and odorant deposition in an anatomically accurate model of the coyote (Canis latrans) nasal cavity during quiet breathing, a notional quasi-steady sniff, and unsteady sniffing to: quantify the influence of unsteady sniffing, assess the validity of the quasi-steady assumption, and investigate the functional advantages of sniffing compared to breathing. Our results reveal that flow unsteadiness during sniffing does not appreciably influence qualitative (gross airflow and odorant deposition patterns) or quantitative (time-averaged olfactory flow rate and odorant uptake) measures of olfactory function. A quasi-steady approximation is, therefore, justified for simulating time-averaged olfactory function in the canine nose. Simulations of sniffing versus quiet breathing demonstrate that sniffing delivers about 2.5 times more air to the olfactory recess and results in 2.5-3 times more uptake of highly- and moderately-soluble odorants in the sensory region per unit time, suggesting one reason why dogs actively sniff. Simulations also reveal significantly different deposition patterns in the olfactory region during inspiration for different odorants, and that during expiration there is little retronasal odorant deposition in the sensory region. These results significantly improve our understanding of canine olfaction, and have several practical implications regarding computer simulation of olfactory function.
... Chemoreception plays a vital role in finding food sources in many invertebrate (e.g., Atema, 1995;Keller and Weissburg, 2004;Settles, 2005;Koehl, 2006;Waldrop et al., 2015;Waldrop and Koehl, 2016) and vertebrate (e.g., Schoenfeld and Cleland, 2006) species. Chemoreception requires that odor molecules from the surrounding fluid get into contact with the receptors in the epidermis, and is therefore enhanced by an increase in flow speed, i.e. a reduction of the boundary layer above the epidermis. ...
The corona ciliata of Chaetognatha (arrow worms) is a circular or elliptical groove lined by a rim from which multiple lines of cilia emanate, located dorsally on the head and/or trunk. Mechanoreception, chemosensation, excretion, respiration, and support of reproduction have been suggested to be its main functions. Here we provide the first experimental evidence that the cilia produce significant water flow, and the first visualisation and quantification of this flow. In Spadella cephaloptera, water is accelerated toward the corona ciliata from dorsal and anterior of the body in a funnel-shaped pattern, and expelled laterally and caudally from the corona, with part of the water being recirculated. Maximal flow speeds were approximately 140 μm s⁻¹ in adult specimens. Volumetric flow rate was Q = 0.0026 μl s⁻¹. The funnel-shaped directional flow can possibly enable directional chemosensation. The flow measurements demonstrate that the corona ciliata is well suited as a multifunctional organ.
... Deposition of methamphetamine on surfaces can occur via direct contact from skin, for example walking and handling door or window elements. 45 Like tobacco smokers, the human thermal plume 295,296 of methamphetamine smokers and the air turbulence associated with their movement 297 is also likely to be a minor source of methamphetamine contamination. ...
The effectiveness of commonly used surface testing and decontamination methods was investigated for 20 suspected former clandestine methamphetamine laboratories in New Zealand. Methamphetamine surface contamination was collected via wipe sampling and measured quantitatively with GC-MS using an isotopically labelled methamphetamine internal standard. Methamphetamine surface wipe concentrations (n = 137) ranged from below detection limits (0.005 μg/100 cm2) up to 6100 μg/100 cm2. The median concentration was 2 μg/100 cm2 and 95 % of concentrations lay between detection limits and 500 μg/100 cm2. Results showed that some testing methods in use in New Zealand in 2008 - 2010 were unreliable, and that some decontamination methods used at that time were ineffective. All but three of the sites tested had surface concentrations exceeding the New Zealand Ministry of Health surface clean-up guideline of 0.5 μg/100 cm2. Only glass and very smooth impervious surfaces were effectively cleaned. Building materials that were analysed for methamphetamine (n = 15) had concentrations ranging from below detection limits up to 5,200 μg/g methamphetamine. Pseudoephedrine was the second most common contaminant found. The ratio between pseudoephedrine and methamphetamine was strongly correlated with the suspected site of manufacture. There were 39 compounds found to be associated with methamphetamine manufacture, of these 11 were associated only with drug synthesis, and 14 were associated with methamphetamine precursor activities. Six compounds were found that could originate from either methamphetamine smoking or methamphetamine manufacture, and five compounds were found that could originate as analytical artifacts or from methamphetamine manufacture. The compound 1,2-dimethyl-3- phenylaziridine was detected at several sites, and may be a more useful manufacture indicator compound than methamphetamine. A novel method for sampling and quantitation of airborne methamphetamine at μg/m3 concentrations was developed using dynamic SPME GC-MS and isotopically labelled methamphetamine. Air was sampled for airborne methamphetamine and other semivolatile organic compounds at 11 suspected former clandestine methamphetamine laboratories using SPME GC-MS, and methamphetamine was detected in the air at three former clandestine methamphetamine laboratories. There was a positive correlation between the detection of airborne methamphetamine and high methamphetamine surface concentrations.
... inhalation of air through an inlet orifice (e.g., a nostril). Although some researchers have focused on the interior flow in the internal airways [5] and others have focused on aspects of the exterior flow [10], fundamental hydrodynamics of the coupled inhalant flow system have not been characterized, though they are certainly acknowledged [11]. While both interior flow regions have been investigated extensively in the literature, viscous exterior flow approaching an inlet orifice is relatively unstudied. ...
Inhalant flows draw fluid into an orifice from a reservoir and are ubiquitous in engineering and biology. Surprisingly, there is a lack of quantitative information on viscous inhalant flows. We consider here laminar flows (Reynolds number Re≤100) developing after impulsive inhalation begins. We implement finite element simulations of flows with varying Re and extraction height h (orifice height above a bottom bed). Numerical results are experimentally validated using particle image velocimetry measurements in a physical model for a representative flow case in the middle of the Re-h parameter space. We use two metrics to characterize the flow in space and time: regions of influence (ROIs), which describe the spatial extent of the flow field, and inhalation volumes, which describe the initial distribution of inhaled fluid. The transient response for all Re features an inviscid sinklike component at early times followed by a viscous diffusive component. At lower Re, diffusion entrains an increasing volume of fluid over time, enlarging the ROI indefinitely. In some geometries, these flows spatially bifurcate, with some fluid being inhaled through the orifice and some bypassing into recirculation. At higher Re, inward advection dominates outward viscous diffusion and the flow remains trapped in a sinklike state. Both ROIs and inhalation volumes are strongly dependent on Re and extraction height, suggesting that organisms or engineers could tune these parameters to achieve specific inhalation criteria.
... Development of an efficient and cost-effective method for detection of nitroaromatic explosives is highly desirable, since there are considerable environmental and security needs, especially with the surge of international terrorism and an enhanced use of explosives in terrorist attacks [1][2][3]. There are a number of handled sniffers (sensors working as an artificial dog's nose) using advantage of materials which are capable of searching explosives through smell of these compounds [4]. The most famous artificial nose for nitroaromatics has been launched successfully into the market, as "FIDO" by Nomadics Inc [5]. ...
In this paper, the new sensors based on the C(4) or/and C(5) mono(heteroaryl) and di(heteroaryl) substituted pyrimidines are described. The effect of different substituents in pyrimidine ring on the detection limits and selectivity for prepared sensors are explained. The results of detection towards various nitro-explosives and volatile interferents at room temperature with use of the portable detector "Nitroscan" are shown.
... With the advances in robotics and chemicals sensor research in the last decade, odor sniffing robots have become an active research area. Notably the localization of odor sources would allow for very interesting robotic applications, such as search and rescue operations, safety and control operations on airports or industrial plants, and humanitarian demining [19] [4] [15] [7]. Many of these applications are time-critical, i. e. odor sources should be found as fast as possible. ...
We introduce a novel bio-inspired odor source localization algorithm (surge-cast) for environments with a main wind flow and compare it to two well- known algorithms. With all three algorithms, systematic experiments with real robots are carried out in a wind tunnel under laminar flow conditions. The algo- rithms are compared in terms of distance overhead when tracking the plume up to the source, but a variety of other experimentally measured results are provided as well. We conclude that the surge-cast algorithm yields significantly better performance than the casting algorithm, and slightly better performance than the surge-spiral algorithm.
... Most garments are permeable for this current of particles. [19] The conclusion is that humans permanently release many skin cells into their surroundings. These cells are decomposed by microorganisms. ...
Mantrailing is a new kind of searching, performed by canines. It is based on the assumption that dogs perceive an unique odour image from every single person. This assumption has developed out of varied practical experiences. More specifically, mantrailing is the search for, and track of, the individual odour of humans by specially trained canines. The purpose is to locate and indicate the sought person. The concept “trailing” has to be distinguished by the concept “tracking”. In the strict sense of the term tracking the dog should follow footstep to footstep. The trailing dog is oriented to the rafts of scent which may have fallen to ground along the person’s route. The distribution of this rafts is influenced by environmental conditions, such as wind, so that these also can be in a certain distance of the footprint. This allows the trailing canine to move from the actual step to an outer region of rafts and back again.[1] The canine that is trained to search and trail the unique odour image of human is called “mantrailer“.
... Current detection methods are cumbersome, require pre-treatment of samples, are susceptible to interfere from other compounds, and are usually suffering from a low sensitivity [9e12]. On the other hand, there is a number of hand-held sniffers (sensors working as an artificial dog's nose) using the advantage of materials, which are capable of searching explosives through the «smell» of these compounds [13]. The most famous artificial nose for nitroaromatics has been launched successfully into the market, as «FIDO» by Nomadics Inc [14]. ...
A series of D–π–A–π–D type dyes based on pyrimidines, bearing thiophene linkers, have been studied as sensing fluorophores. Fluorescence studies have demonstrated that the emission of all derivatives is sensitive to the presence of 2,4,6-trinitrotoluene (TNT) and other nitroaromatic compounds (NACs), in their acetonitrile solutions. The detection limits of fluorophores to NACs proved to be in the range from 10⁻⁴ to 10⁻⁶ mol/L. The time-resolved fluorescence measurements and theoretical investigation into the quenching mechanism in the presence of fluorophore has been performed. The two types of sensor prototypes for handheld sniffer «Nitroscan» (Plant «Promautomatika», Ekaterinburg, Russia) on the basis of non-woven dry wipe and spunlace non-woven fabric with various quantities of the most sensitive fluorophore have been fabricated. The reusable, reversible and sensitive response of the designed prototypes to NACs enables one to qualify these compounds as promising fluorescent sensory materials for detection of NACs.
... Efficient Chemical Plume Tracing (CPT) is important in search and rescue, security and safety operations by tracing and locating the source [1,2]. Research is ongoing with numerous methods being proposed for CPT. ...
Biomimetic Chemical Plume Tracing (CPT) problem is complex because it couples nonlinearity of biological systems with uncertainty of time-varying plume diffusion. A vision-based simulator is proposed to decouple these difficulties to facilitate multiple runs under controlled environment. This enables identification of efficient biological CPT algorithm. The simulator is used to simulate Embodiment Sensing (ES), i.e. sensing using physical attributes of animals. Wings and antennae of silk moth are used for ES, and evaluated for CPT using vision-based simulator. Results suggest (1) vision-based plume field mimics actual plume diffusion in terms intermittency, and (2) similar performance as that for surge-cast algorithm. The contribution is two-fold, (1) vision-based plume diffusion simulator decouples uncertainty of plume diffusion from nonlinearity of biological system to facilitate biomimetic CPT study, and (2) feasibility of using physical attributes of silk moth to achieve good CPT performance.
... The sniffing volume flow rate was chosen to be 1.91 L/min (a factor of 2.81 higher) based on the allometric relationship provided by Ranslow et al. (2014). The sniffing frequency was chosen to be 8 Hz from the allometric estimation that the sniffing frequency of the rat, dog, and human is 10, 5, and 2 Hz, respectively (Settles, 2005). To study the respiration rate effect, a spectrum of inhalation flow rates (i.e., 0.68 L/ min 30.5, 1.0, 2.0, 3.0, 4.0) was considered in computational simulations. ...
The rabbit is commonly used as a laboratory animal for inhalation toxicology tests and detail knowledge of the rabbit airway morphometry is needed for outcome analysis or theoretical modeling. The objective of this study is to quantify the morphometric dimension of the nasal airway of a New Zealand white rabbit and to relate the morphology and functions through analytical and computational methods. Images of high-resolution MRI scans of the rabbit were processed to measure the axial distribution of the cross-sectional areas, perimeter, and complexity level. The lateral recess, which has functions other than respiration or olfaction, was isolated from the nasal airway and its dimension was quantified separately. A low Reynolds number turbulence model was implemented to simulate the airflow, heat transfer, vapor transport, and wall shear stress. Results of this study provide detailed morphological information of the rabbit that can be used in the studies of olfaction, inhalation toxicology, drug delivery, and physiology-based pharmacokinetics modeling. For the first time, we reported a spiral nasal vestibule that splits into three paths leading to the dorsal meatus, maxilloturbinate, and ventral meatus, respectively. Both non-dimensional functional analysis and CFD simulations suggested that the airflow in the rabbit nose is laminar and the unsteady effect is only significantly during sniffing. Due to the large surface-to-volume ratio, the maxilloturbinate is highly effective in warming and moistening the inhaled air to body conditions. The unique anatomical structure and respiratory airflow pattern may have important implications for designing new odorant detectors or electronic noses. This article is protected by copyright. All rights reserved.
... Desert isopods lack aesthetascs, do not flick their antennules and the areas of the brain responsible for processing olfactory information have been functionally lost [36]. Like coenobitid crabs, insects are adept at tracking odour plumes in air [57]. Insects have lost their first antennae and secondarily developed chemosensory sensilla on their second antennae, thus the olfactory capture structures of coenobitid crabs and insects are not homologous [35,36]. ...
Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from air is not understood. The terrestrial hermit crab, Coenobita rugosus, uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid flow relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that flow. Air does not flow into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from air flowing around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
... The biomechanics of the movement of air past the back of the mouth involves more specifically a subset of engineering problems that fall under the category of dynamic fluid mechanics. This approach has revealed complex flow patterns of air through the nasal cavity during orthonasal [25][26][27] smell. The challenge now is to do the same for the flow patterns of air through the oro-and nasopharynx during retronasal smell. ...
Flavour science is concerned with the sensory appreciation of food. However, flavor is not in the food; it is created by the brain, through multiple sensory, motor, and central behavioral systems. We call this new multidisciplinary field “neurogastronomy.” It is proving useful in integrating research findings in the brain with the biomechanics of generating food volatiles and their transport through retronasal smell. Recent findings in laboratory animals and in humans give new insights into the adaptations that have occurred during evolution that give humans an enhanced flavor perception. This process will be illustrated by an analysis of how the brain creates the taste of wine. The successive stages of the biomechanics of movement of the ingested wine and transport of the released volatiles will be correlated with activation of the multiple brain mechanisms, apparently engaging more of the brain than any other human behavior. These stages include the initial cephalic phase, visual analysis, ingestion, formation of the wine perceptual image, formation of the wine perceptual object, swallowing, and post-ingestive effects. This combined biomechanic and brain mechanism approach suggests a new discipline of “neuroenology (neuro-oenology),” adding to the contributions that science can make to the enhanced quality and appreciation of wine.
Direct analysis in real time-mass spectrometry (DART-MS) was used to explore the behavior of vapor released from triacetone triperoxide (TATP) versus an absorption-based canine training aid sometimes called a polydimethylsiloxane (PDMS) polymer odor capture and release (POCR) system. The results compare dissipation from the source to the instrument (in minutes), steady state signal intensity (i.e. approximate relative amounts), and dissipation of the odor after removing the source (also in minutes). Several parameters were tested: reproducibility between POCRs, TATP versus TATP with a lid (containing 13 precision-drilled holes), distance from the detector, heights of the source, concealment, purposeful air disturbances, blanks, and containment systems.
In general, the PDMS-based training aid behaved similarly to the TATP with a 13-hole lid, which is the aid most often used by the FBI’s National Canine Improvised Explosives Detection Program. Results shows that the PDMS-based training aids are reproducible and reliable at steady state as a vapor release system. As expected, signal was decreased given increased distance from the DART interface for all sample types, when using the odor-restricting lid with the 1 g TATP sample, when all samples were placed at height, and when using a cotton bag as a method of concealment. Despite having no direct correlation, these results support anecdotal canine evidence since canine handlers tend to report that their dogs have more difficulty finding training aids within those same parameters. Further, adding purposeful air disturbances had a larger effect on signal intensity for 1 g TATP than on the PDMS-based training aid. Finally, adding a masking odor at the DART interface decreased detection of TATP regardless of the vapor source, but did not fully diminish it. This too agrees with canine handler reports and previous research, where dogs may have a more difficult time locating odors in the presence of high background.
This is the first report of its kind to use real-time detection to characterize vapor release and dissipation from a biosensor training aid in comparison to the corresponding true material it intends to replace. By using the three phases of odor release (saturation, steady state, and depletion), the study investigates the effects of several ambient parameters on TATP volatile detection from true material and the PDMS-based training aid.
This paper describes the design of a miniature air suction system to house a chemical sensor. It has been designed to improve the aerodynamic chemical sensing efficiency and to have a low weight since it is meant to be mounted on a micro air vehicle. The design is done around a readily available miniature axial flow fan by computational methods. A converging-diverging shape for the air suction system with the sensor disc having a central hole and mounted at the throat is proposed as good design concept. The systematic approach has led to a light weight system with high aerodynamic efficiency even under extreme flow conditions that may be caused by MAV manoeuvre or cross winds.
Fluid dynamics plays an important part in olfaction. Using the complementary techniques of dye visualisation and computational fluid dynamics (CFD), we investigated the hydrodynamics of the nasal region of the sturgeon Huso dauricus. H. dauricus offers several experimental advantages, including a well-developed, well-supported, radial array (rosette) of visible-by-eye olfactory sensory channels. We represented these features in an anatomically accurate rigid model derived from an X-ray scan of the head of a preserved museum specimen. We validated the results from the CFD simulation by comparing them with data from the dye visualisation experiments. We found that flow through both the nasal chamber and, crucially, the sensory channels could be induced by an external flow (caused by swimming in vivo) at a physiologically relevant Reynolds number. Flow through the nasal chamber arises from the anatomical arrangement of the incurrent and excurrent nostrils, and is assisted by the broad, cartilage-supported, inner wall of the incurrent nostril. Flow through the sensory channels arises when relatively high speed flow passing through the incurrent nostril encounters the circular central support of the olfactory rosette, decelerates, and is dispersed amongst the sensory channels. Vortices within the olfactory flow may assist odorant transport to the sensory surfaces. We conclude that swimming alone is sufficient to drive olfactory flow in H. dauricus, and consider the implications of our results for the three other extant genera of sturgeons (Acipenser, Pseudoscaphirhynchus and Scaphirhynchus), and for other fishes with olfactory rosettes.
With advancements in mobile robot olfaction, networked Multiagent Systems (MAS) are used in odour source localisation. These MAS are often equipped with small microprocessors that have limited computing capabilities, and they usually operate in bandwidth and energy constrained environment. The exigent need for faster localising algorithm under communication and computational resource constraints invite many design challenges. In this study, we have designed a two level hierarchical cooperative control strategy for heterogeneous nonlinear MAS for odour source localisation. Agents are forced towards consensus expeditiously once the information on whereabouts of the source is attained. Synthesis of the controller happens in a hierarchical manner-- obtaining group decision, followed by a resource-efficient robust control. Odour concentration and wind information have been used in group decision making layer to predict a probable location of source as tracking reference. This reference is then fed to the control layer synthesised using event-triggered Sliding Mode Control (SMC). The advantage of using event-triggered control scheduling in conjunction with SMC is rooted in retaining the robustness of SMC while lowering resource utilisation burden. Numerical simulations confirm the efficiency of the scheme put forth.
This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions.
The topic of search dogs could be a component of a more all-encompassing category of search techniques. It is highlighted here, however, because of the routine historic use of dogs in searches for both live and deceased victims. The compiler has found the use of qualified cadaver dog teams the most efficient and cost effective means of searching large areas. By the same token, he has been frustrated by the inconsistency of some dogs and the inappropriate conduct by their handlers. Search and rescue teams will typically volunteer their efforts. A canine search is inherently a low impact technique involving minimal disruption of potential buried scenes. It is also a technique which can be implemented discretely and repeatedly as environmental conditions (ie. temperature, moisture, or vegetation), change across a search area. A drawback to the use of dogs involves confirmation of their abilities. Obviously, the best confirmation includes a history of multiple finds in the past. In the absence of such history and referrals, the nature and extent of the team’s training should be considered. The resources listed below should offer insight into proper training techniques and the use of canine search teams. The use of trained canines is only one of several search tools. The competent investigator incorporates as many tools as feasible yet does not base his investigation on one technique or resource.
An important aspect of incorporating a qualified search dog team into a law enforcement investigation is preparation through cross-training. While a member of the FBI's St. Louis Evidence Response Team, the compiler introduced outside cadaver dogs and handlers into Evidence Response Team training as a way to familiarize both teams with the capabilities and protocols of the other. Periodic testing of dogs and their handlers is a must. Search dog handlers reluctant to be tested using accepted training standards should be avoided. Likewise, investigators should not be shy in requesting documentation of finds and failed searches by search teams under consideration. Legitimate teams record those call-outs they have had and the results of same. If they do not, or only document finds without recording later discoveries missed by their dogs, then they should be avoided. As a crime scene investigator, the compiler considers legitimate those handlers who acknowledge failed searches, among their successes, in which victims' remains were missed by their dogs. Those handlers have then analyzed such experiences to determine why their dogs did not alert and to refine their training.
Consideration of search dogs should also include the conduct of their handlers. Their backgrounds, behavior, and ethics will be scrutinized in court if not by the law enforcement who use them. In 2005, internationally recognized dog handler Sandy Anderson was convicted after and investigation discovered her planting of human remains fragments at search sites. (Shepardson, 2004 and Walker, 2004 below). Unfortunately, Anderson's canine counterpart, "Eagle", had successfully located victims. This handler's unethical behavior was not necessary to enhance or validate the capabilities of her dog.
As with virtually every other category in this bibliography, technological developments attempt to improve the state of the art. Vass, et al's. (2004 through 2012) work, Furton, et al. (2015), and others in scent detection, seek to develop devices which may never replace man's best friend, but to join him as another tool in the search arsenal. With mass disasters such as the aftermath of September 11, 2001 and Hurricane Katrina in 2005, research into scent measurements is increasingly appearing in mass media and forensic science literature. Citations encountered by the compiler are included in this section. The reader is also directed to that section of this bibliography which deals with topics of Decomposition under Taphonomy. (603 citations)
The olfactory system recognizes a vast range of molecules that represent vital information about an animal's environment. How does the nose organize this complex mixture of olfactory information? This article discusses evidence from rodents showing that there are several spatially segregated subpopulations of sensory neurons within the mammalian nose. Each of these olfactory subsystems may serve distinct functions by using different signal transduction pathways and projecting to different brain areas. Together, they may carry both distinct and overlapping information into the brain and provide a complete representation about the chemical world.
Many vertebrates possess at least two distinct olfactory systems—a main olfactory system and an accessory olfactory system—both of which are capable of detecting and transducing molecular cues of a social nature, such as pheromones. This article summarizes the basic physiology and functions of the accessory olfactory system, which includes the vomeronasal organ and the accessory olfactory bulb.
The 90th Anniversary of the Fluids Engineering Division (FED) of ASME will be celebrated on July 10–14, 2016 in Washington, DC. The venue is ASME's Summer Heat Transfer Conference (SHTC), Fluids Engineering Division Summer Meeting (FEDSM), and International Conference on Nanochannels and Microchannels (ICNMM). The occasion is an opportune time to celebrate and reflect on the origin of FED and its predecessor—the Hydraulic Division (HYD), which existed from 1926–1963. Therefore, the FED Executive Committee decided that it would be appropriate to publish concurrently a history of the HYD/FED. Accordingly, they commissioned Paul Cooper, C. Samuel Martin, and Timothy O'Hern to prepare this paper, which would document the division's past. A brief work in this direction had appeared in the 2010 FED Newsletter (Morgan, W. B., 2010, Brief History of ASME's Hydraulic/Fluids Engineering Division, Fluids Engineering Division Newsletter, New York, pp. 6–7), and the research by Martin for the present paper had been under way for several years prior to that (Cooper, P., 2010, “History of the FED,” FED Executive Committee at the ASME-CSME Fluids Engineering Summer Conference (FEDSM-2010), Montréal, QC, Canada, Aug., p. 14).
Over the past two decades, various research efforts have been made to employ chemical sensing capabilities on mobile robot platforms. This chapter presents the tasks that mobile robots are expected to accomplish with the help of chemical sensing capabilities with the technical challenges involved in those tasks. Then, it presents hardware setups that people can use and various algorithms that have been proposed to accomplish the tasks. The chapter deals with the detection of airborne gas-phase chemical substances by mobile robots. It also mentions underwater chemical sensing. Research on mobile robot olfaction seems to be getting into a next phase in which the research efforts are more directed toward real applications. It may be too ambitious to develop a versatile gas source localization robot that can be used in any environment. One of the promising applications for gas sensing mobile robots is to find methane leaks in landfill sites.
Scent detection in an aquatic environment is dependent on the movement of water. We set out to determine the mechanisms for moving water through the olfactory organ of guitarfishes (Rhinobatidae, Chondrichthyes) with open nasal cavities. We found at least two. In the first mechanism, which we identified by observing dye movement in the nasal region of a life-sized physical model of the head of Rhinobatos lentiginosus mounted in a flume, olfactory flow is generated by the guitarfish's motion relative to water, e.g. when it swims. We suggest that the pressure difference responsible for motion-driven olfactory flow is caused by the guitarfish's nasal flaps, which create a region of high pressure at the incurrent nostril, and a region of low pressure in and behind the nasal cavity. Vortical structures in the nasal region associated with motion-driven flow may encourage passage of water through the nasal cavity and its sensory channels, and may also reduce the cost of swimming. The arrangement of vortical structures is reminiscent of aircraft wing vortices. In the second mechanism, which we identified by observing dye movement in the nasal regions of living specimens of Glaucostegus typus, the guitarfish's respiratory pump draws flow through the olfactory organ in a rhythmic (0.5–2 Hz), but continuous, fashion. Consequently, the respiratory pump will maintain olfactory flow whether the guitarfish is swimming or at rest. Based on our results, we propose a model for olfactory flow in guitarfishes with open nasal cavities, and suggest other neoselachians which this model might apply to.
Artificial (electronic) noses are devices engineered to identify volatile odorous compounds. They usually consist of two components that derive from biological olfactory principles: (1) cross-reactive sensing arrays that generate patterned responses upon odor exposure and (2) analytical algorithms that categorize these patterned response signatures. As in the olfactory pathway, artificial noses encode odor information in a distributed fashion across the system. These devices occupy a unusual niche in relationship to neuroscience in that they were developed to mimic basic olfactory principles at a time when the phenomenology of olfactory encoding was recognized, but the underlying mechanisms were still not well documented.
This paper proposes the particle swarm optimization based on Shannon’s entropy to deal with the problem of odor source localization. First, a measurement model by which the robots can always observe a position is briefly described. When the detection events occur, the position of the odor source lies in the vicinity of the observed position with a higher probability. When the non-detection events occur, the position of the odor source does not lie in the vicinity of the observed position with a higher probability. Second, on the basis of the measurement model, the posteriori probability distribution on the position of the odor source is established where the detection events and non-detection events are taken into account. Third, each robot can understand the search environment by using Shannon’s entropy which can be calculated in terms of the posteriori probability distribution on the position of the odor source. Moreover, each robot should move toward the direction of the entropy reduction. By means of this principle, the particle swarm optimization algorithm is introduced to plan the movement of the robot group. Finally, the effectiveness of the proposed approach is investigated for the problem of odor source localization.
This review paper discusses the field of particle resuspension from surfaces, with special attention paid to the developments of the last decade. We present both general models of particle resuspension which appear in the literature, and studies on specific aspects of the problem. Among the topics discussed in the paper, one can find such diverse subjects as effect of particle and substrate material properties, modeling of particle adhesion, hydrodynamic mechanisms of particle removal, particle detachment from smooth and rough surfaces, and particle motion after its detachment. Also presented are particle resuspension from multilayer deposits and resuspension phenomena in liquid environments. Modern methods of particle removal and other related topics of interest are discussed.
Crayfish are known to generate water jets by waving their special appendages with a fan-like shape. The generated jets entrain surrounding water, and thus inflow converging toward their olfactory organs is induced. Therefore, the jets are considered to help crayfish collect water samples to search for the smell of a prey. Although crayfish are also known to be able to change the direction of the jet discharge, its implication in olfactory search has not been well understood. To investigate this issue, we have developed a chemical sampling device equipped with a jet discharger and electrochemical sensors. Results of computational fluid dynamics analyses and chemical detection experiments are presented to show that the angular range of water-sample collection can be adjusted by changing the jet discharge directions. The results suggest that the olfactory search efficiency can be improved by narrowing down the angular sample collection range as the search progress.
This article reports experiments carried out to determine the effectiveness of an air shower used to enter a cleanroom suite. It was concluded that air showers have little value in reducing particle dispersion from cleanroom personnel
From Animals to Animats 4 brings together the latest research at the frontier of an exciting new approach to understanding intelligence.
The Animals to Animats Conference brings together researchers from ethology, psychology, ecology, artificial intelligence, artificial life, robotics, engineering, and related fields to further understanding of the behaviors and underlying mechanisms that allow natural and synthetic agents (animats) to adapt and survive in uncertain environments. The work presented focuses on well-defined models—robotic, computer-simulation, and mathematical—that help to characterize and compare various organizational principles or architectures underlying adaptive behavior in both natural animals and animats.
Bradford Books imprint
An overview of neurotechnology, the engineering of robots based on animals and animal behavior.
The goal of neurotechnology is to confer the performance advantages of animal systems on robotic machines. Biomimetic robots differ from traditional robots in that they are agile, relatively cheap, and able to deal with real-world environments. The engineering of these robots requires a thorough understanding of the biological systems on which they are based, at both the biomechanical and physiological levels.This book provides an in-depth overview of the field. The areas covered include myomorphic actuators, which mimic muscle action; neuromorphic sensors, which, like animal sensors, represent sensory modalities such as light, pressure, and motion in a labeled-line code; biomimetic controllers, based on the relatively simple control systems of invertebrate animals; and the autonomous behaviors that are based on an animal's selection of behaviors from a species-specific behavioral "library." The ultimate goal is to develop a truly autonomous robot, one able to navigate and interact with its environment solely on the basis of sensory feedback without prompting from a human operator.
Bradford Books imprint
The insect olfactory system has become a very important model of sensory function, morphology and development. Intense research in several insect orders has yielded a large amount of data. This book provides a comprehensive overview, with special emphasis placed on pheromone-specific and host-related detection and processing of odour information. A valuable information source not only for researchers and students in the field of insect olfaction but also for those working on sensory systems, in entomology, neurophysiology, and pest control.
The mechanics of submerged turbulent jets has received a good deal of research attention. This work has resulted in an understanding of the process by which jets grow by entrainment of surrounding fluid. While of direct scientific interest, this work has practical implications that are of interest to engineers concerned with the design of systems that utilize jet concepts. A fluid motion is called a jet if its primary source of kinetic energy and momentum flux is a pressure drop through an orifice. A fluid motion whose main source of kinetic energy and momentum flux is body forces is called a plume. The flows, whose motion is in transition from a jet to a plume, are called a forced plume or a buoyant jet. Almost all jets whose fluid density differs from the ambient fluid density become plumes. This chapter discusses the mechanics of jets and plumes whose interactions with their environment are self-generated. It discusses how such jets and plumes are influenced by changes in the environment such as density stratification of the surrounding fluid, uniform motion of the ambient fluid, or turbulence within the ambient fluid.
1 The olfactory system of vertebrates.- 1.1 Anatomy.- 1.2 Odorant characteristics.- 1.3 Function of the external nares and related structures.- 1.4 Evolutionary trends.- 1.5 Summary.- 2 Sources and chemistry of vertebrate scent.- 2.1 The sites of odour production.- 2.2 Chemical composition of odorants.- 2.3 Threshold levels of perception.- 3 Detection of food.- 3.1 Responses of young to food odours.- 3.2 The detection of plant food by odorous cues.- 3.3 The detection of animal food by odorous cues.- 3.4 Scavengers.- 3.5 Quasi-parasites.- 3.6 Summary.- 4 Reproductive processes.- 4.1 Sex attraction and recognition the advertisement of sexual status.- 4.2 Detection and induction of oestrus, ovulation and lordosis.- 4.3 Courtship, mating and related behaviours.- 4.4 Pregnancy.- 4.5 Parental behaviour imprinting.- 4.6 Growth physical and psychosexual development.- 4.7 Summary and conclusions.- 5 Odour discrimination and species isolation.- 5.1 Individual odour.- 5.2 Family, population and racial odours.- 5.3 Species odours and sexual isolation.- 5.4 Summary and conclusions.- 6 Dispersion and social integration.- 6.1 Intraspecific aggression.- 6.2 The social hierarchy.- 6.3 Territoriality.- 6.4 Correlation between aggression-motivated behaviour and scent deposition.- 6.5 Summary and conclusions.- 7 Alarm and defence.- 7.1 Detection of the predator.- 7.2 Transmission of alarm or warning signals.- 7.3 Active defence.- 7.4 Protection from intraspecific attack.- 7.5 Summary.- 8 Olfactory navigation and orientation.- 8.1 Olfactory navigation.- 8.2 Homing orientation.- 8.3 Summary.- 9 Applications of researches into olfactory biology.- 9.1 Pest repellents and attractants.- 9.2 Animal husbandry.- 9.3 Miscellaneous applications.- References.- Taxonomie index.
This work presents the results of experiments conducted to characterize the detachment of microparti-cles from surfaces exposed to turbulent air during accelerated free-stream ow. Smooth glass plates used as substrates are scanned with an atomic force microscope to determine their roughness-height distributions. Microparticles of diierent sizes, materials and shapes (mostly microspheres) are deposited as sparse monolay-ers onto the substrates under controlled clean and dry conditions. The microparticles attach to the substrate in a condition of static equilibrium due to adhesion and reside completely within the viscous sublayer as the ow is accelerated. Microvideographic observations of individual microparticle detachment show that detachment occurs primarily as rolling motion along the surface and not as lift-oo. Detachment is not necessarily followed by entrainment in the ow. Results are presented as detachment fractions as function of time. The experimental results reveal that detachment is governed by a balance of the moments of aerodynamic drag and rough-surface pull-oo forces. This is substantiated using a recently developed attachment theory that takes into account surface roughness to determine the pull-oo force of microparticles. The sensitivity of the free-stream threshold velocity for detachment to ÿve factors contained in the experiments and the model is analyzed. Results indicate that the surface energy of adhesion and the microsphere radius have the most innuence on the threshold velocity for detachment. ?
Investigations of the chemical ecology of host-seeking behaviour of the anthropophilic, malarial mosquito Anopheles gambiae s.s. were conducted using observations on biting behaviour, a behavioural bioassay to test the activity of candidate odours, and analytical chemistry of attractive odour mixtures. Anopheles gambiae s.s. landed and bit preferentially on the human foot and it was shown that this behaviour was odour modulated. In the bioassay, the mosquitoes were found to be highly attracted to emanations of Limburger cheese, the odours of which are reminiscent of those from human feet. The active compounds in the cheese were found to be fatty acids and the mosquitoes were attracted to a synthetic mixture of such acids. The ecology of this behaviour is discussed with respect to the odours produced by human skin.
The olfactory systems of animals as diverse as insects and primates are well-known for having extraordinary sensitivity while, at the same time, exhibiting broad discriminative abilities. These properties, often mutually exclusive in other chemical recognition systems, appear to arise from the parallel, distributed nature of the processes that underlie how odors are encoded at each level in the olfactory pathway in the brain. In this paper we describe how we have tried to characterize the physiological aspects of these processes in biological experiments, capture these processes in a computational model, and then to use these observations to design and build a biologically inspired artificial device. The Tufts Medical School Nose has achieved a degree of sensitivity and discriminability that, for certain compounds under defined conditions, approaches that of its biological parent.
Many organisms move up or down stimulus gradients to a more favorable environment. Investigation over more than a century has revealed that a variety of mechanisms are used by different organisms. There are tradeoffs among these strategies between the number of sensors, the movements required of the searcher, and physical constraints on its orientation. Recently, theoretical analysis and computer simulation have been used to explore these tradeoffs quantitatively. This information may be useful in the design of autonomous vehicles that might also follow stimulus gradients.
A finite element fluid dynamics software model, FIDAP 6.0, was used to model the air flow in two different personnel screening booth configurations; one a walk-in/walk-out booth and the other a walk-through booth. The various parameters modeled were streamline contours, speed contours, effects of puffers, and RDX concentration. For optimum results it is necessay to produce high velocity air flows and, in the case of the walk through booth, it is imperative to locate a high speed puffer on the side of the booth opposite the sampling ducts.
A theoretical model which predicts the expected concentration of explosive vapor which might be available for detection in various scenarios was reported at a previous conference (Mannheim 1989). The results of this model have now been refined and the model extended to apply to other situations. A comparison has been made of the predictions of this model with experimental results obtained in a controlled experiment in a room-sized environment. The experimental results are found to be in good agreement with the theoretical predictions.
Computational fluid dynamics (CFD) models of the nasal passages of a rat, monkey, and human are being used (1) to determine important factors affecting nasal uptake, (2) to make interspecies dosimetric comparisons, (3) to provide detailed anatomical information for the rat, monkey, and human nasal passages, and (4) to provide estimates of regional air-phase mass transport coefficients (a measure of the resistance to gas transport from inhaled air to airway walls) in the nasal passages of all three species. For many inhaled materials, lesion location in the nose follows patterns that are both site and species specific. For reactive, water-soluble (Category 1) gases, regional uptake can be a major factor in determining lesion location. Since direct measurement of airflow and uptake is experimentally difficult, CFD models are used here to predict uptake patterns quantitatively in three-dimensional reconstructions of the F344 rat, rhesus monkey, and human nasal passages. In formaldehyde uptake simulations, absorption processes were assumed to be as rapid as possible, and regional flux (transport rate) of inhaled formaldehyde to airway walls was calculated for rats, primates, and humans. For uptake of gases like vinyl acetate and acrylic acid vapors, physiologically based pharmacokinetic uptake models incorporating anatomical and physical information from the CFD models were developed to estimate nasal tissue dose in animals and humans. The use of biologically based models in risk assessment makes sources of uncertainty explicit and, in doing so, allows quantification of uncertainty through sensitivity analyses. Limited resources can then be focused on reduction of important sources of uncertainty to make risk estimates more accurate.
Comparison of personal and area concentration measurements made in different workplaces show the variation due to sampler position and work methods. Measurements made using a manikin show that breathing zone concentrations may not be the same as with a human operative. Tests which use a manikin may not therefore provide an adequate simulation.
Airborne culturable bacteria were monitored at five locations (three in an office/laboratory building and two in a private residence) in a series of experiments designed to compare the efficiency of four air samplers: the Andersen two-stage, Burkard portable, RCS Plus, and SAS Super 90 samplers. A total of 280 samples was collected. The four samplers were operated simultaneously, each sampling 100 L of air with collection on trypticase soy agar. The data were corrected by applying positive hole conversion factors for the Burkard portable, Andersen two-stage, and SAS Super 90 air samplers, and were expressed as log(10) values prior to statistical analysis by analysis of variance. The Burkard portable air sampler retrieved the highest number of airborne culturable bacteria at four of the five sampling sites, followed by the SAS Super 90 and the Andersen two-stage impactor. The number of bacteria retrieved by the RCS Plus was significantly less than those retrieved by the other samplers. Among the predominant bacterial genera retrieved by all samplers were Staphylococcus, Bacillus, Corynebacterium, Micrococcus, and Streptococcus.
Using gas chromatography, a vapor sensor called the zNose can provide an almost unlimited number of virtual chemical sensors as well as recognizable olfactory images of specific vapor mixtures. Currently, the equipment is being used for quality control of many different foods and beverages. The ability to process hundreds of samples per day with part-per-billion accuracy is an important and cost-effective advantage of this new technology.
In this presentation, we briefly describe some of the research projects in
GALCIT in which flow visualization played a central role.
CONTENTS: PURPOSES OF VENTILATION; PHYSICAL PROPERTIES OF MOIST AIR; AIR WASHERS; AERODYNAMIC PRINCIPLES OF AIR INTERCHANGE; JET THEORY; AIR OUTLETS; SUCTION DATA; AIR CIRCULATION IN PREMISES UNDER ISOTHERMAL CONDITIONS; SURPLUS HEAT; HUMIDITY; GASES AND VAPOURS; DUST; REMOVAL OF DUST FROM AIR; AIR CHANGE; AIR DOUCHES; AIR CURTAINS; LOCAL EXHAUST SYSTEMS; INDEX
Raw material, fuel, and product costs plus the penalties for misuse emphasize the importance of nonleaking process systems. This study surveys a wide variety of methods that can be applied to fluid leak detection in petroleum and other industries. These techniques include pressurization; such simple methods as bubble observation; chemical analysis; combustible gas, thermal conductivity, and halogen detection; acoustic emission; and other instrumented approaches. Infrared methods that were developed for heat observation can be applied to leak detection, so both application areas are covered. Suggestions ar3 made for additional information and potential vendors for certain kinds of equipment.
Turbulent jets are fluid flows produced by a pressure drop through an orifice. Their mechanics, although studied for over fifty years, has recently received research attention that has resulted in a much improved understanding of the process by which they entrain surrounding fluid. Turbulent plumes are fluid motions whose primary source of kinetic energy and momentum flux is body forces derived from density inhomogeneities. Plumes have not been studied in the same detail as jets but nevertheless there have been some recent gains in the understanding of their mechanics. In this article we will review this progress, especially in relation to how jets and plumes interact with environmental factors, such as density stratification or uniform motion of the ambient fluid. As will become evident, many problems remain and, in some circumstances, we simply cannot describe precisely what does occur. In such cases we will try to provide current references and suggest approaches for future research.
The need to capture localized contaminant emissions, the major causes of respiratory ailments in industrial workforces, has been highlighted. The Reinforced Exhaust System (REEXS) is a system used for the purpose of capturing the contaminant, and is highly efficient due to its extended suction capacity. The system immediately replaces the exhaust with a direct supply of fresh air to the worker's occupancy zone. However, the use of the system is accompanied by the risk of the jet blowing contaminants back into the room if the contaminant source moves outside of the capture zone.
The use of surface sampling and on-site analysis is a recent innovation in “sniffer” technology designed to counter the bomb threat in civil aviation. Augmenting the previous vapour sampling approach, new detector technology is emerging which allows the rapid detection of nanogram quantities of plastic explosive residue which may be present on the exterior of passenger luggage or air cargo as a result of secreted explosives. In assessing the efficacy of a new detector system, the problem arises of providing a realistic and reliable source of plastic explosive residue with which to challenge the detector. This paper describes several laboratory and field-simulation approaches, and presents results obtained with the most quantitative of these techniques, a “calibrated” thumbprint source.
The continuing threat of worldwide terrorism has prompted the need for new and innovative explosives detection systems. As part of an ongoing research effort, the FBI Laboratory has been evaluating new technology and the innovative adaptation of existing technology for use in counterterrorism and counternarcotics investigations. We have been examining the application of ion mobility spectrometry (IMS), for its role in explosives detection. The explosives residue is collected on a membrane filter by a special attachment on a household vacuum. Subsequent thermal desorption and analysis requires 5 seconds. Experimental results have determined the limits of detection for most common explosives to be approximately 200 pg. The persistence of explosives on hands and transfer to other surfaces has been examined. Post-blast residue of NG was detected on fragments of improvised explosive devices constructed with double-based smokeless powder. Post-blast residue from C-4, SEMTEX, and other explosives have also been detected on items of forensic and evidentiary value.
Detection of explosives has become a high priority for counterterrorism and land mine clearance operations. In most cases, current technology relies on detection of the metal casing of a mine or explosive device. Because dogs can directly detect explosive residues in air, it is theorized that an "artificial nose" could be constructed to provide fast, reliable detection of explosives. One major obstacle to this approach is the low vapor pressure of explosive materials, such as RDX, at ambient temperature. It is possible, however, to momentarily increase the explosive vapor pressure in the headspace over a target by the use of laser thermal desorption. In this sampling technique, a laser pulse of appropriate wavelength is focused onto a target spot and a detector momentarily samples the vapor over the target. Thus, highly sensitive vapor detectors could be used to detect explosive residues on surfaces of interest.
We have performed experiments that indicate TNT contamination is present on surfaces exposed to TNT vapor, and that TNT contamination is transferred rapidly between proximate surfaces. Contaminated surfaces continue to be nearly constant sources of TNT vapor for some time after removal of the primary source.
airborne particles;assessment of exposure