Basalt reinforced concrete to create a sustainable concrete post suitable for use in agricultural and livestock environments is one which has some merit. Basalt is an eco-friendly material originating from volcanic (igneous) rock. Basalt rebar is non-toxic and non-corrosive and will not wick moisture or conduct electricity. Concrete is an extremely brittle material that resists stresses while under compression, when reinforced with basalt (in the form of rebar), concrete is able to better withstand these tensile and shear stresses. Poles currently used in the Agri sector are either made of wood, pressure treated wood or steel reinforced concrete. Wood is subject to decay, and in the case of pressure treated wood exposure to chemical preservatives and leeching in to surrounding soil may cause contamination. If livestock eat the wood, they can be adversely affected. Available teel reinforced concrete posts have been observed to have experienced a significant amount of deformation that results in major cracks forming thereby exposing the steel reinforcement. These steel reinforced concrete posts are vulnerable to corrosion due other environmental factors such as rain, and freeze thaw cycles. Hence, using non-corrosive, green rebar (basalt) provides a superior alternative to the steel rebar currently being used. In this study, twelve (12) concrete posts with dimensions of:8 cm × 8 cm,10 cm × 10 cm and 14 cm × 14 cm; along with two (2) rebar configurations (one (1) rebar in the center of the post and four (4) rebars placed symmetrically at each corner) were tested to determine the optimal design, cost and desired strength for the proposed concrete pole.
This paper presents the results obtained from an experimental study conducted on grouted masonry prisms. The study determined the interfacial interaction between the grout and concrete blocks, as well as the development of cracks leading to final failure when grouted prisms are loaded in compression. A total of two 4-course high grouted concrete masonry prisms were constructed. These prisms were constructed using the running bond pattern. One of the prisms was cut along its length (390 mm) and one was cut along its width (190 mm), hence, four cut prism specimens were tested. Experimental data was obtained using the innovative digital image correlation (DIC) technique and an accurate data acquisition system. In addition, linear variable displacement transducers (LDVTs) were also used for the validation of the DIC data. The DIC technique was used to effectively observe and track the crack growth and pattern of the concrete masonry prisms, as well as to observe the interaction between grout and concrete blocks. The results obtained from this study showed that DIC is a technique that can be used to determine these behaviours which have not been observable in the past.
This study sets out to extend the use of blink rate and pupil size to the assessment of cognitive load of completing common automotive manufacturing tasks. Nonoptimal cognitive load is detrimental to safety. Existing occupational ergonomics approaches come short of measuring dynamic changes in cognitive load during complex assembling tasks. Cognitive demand was manipulated by having participants complete two versions of the n-back task (easy, hard). Two durations of the physical task were also considered (short, long). Pupil size and blink rate increased under greater cognitive task demand. High cognitive load also resulted in longer task completion times, and higher ratings of mental and temporal demand, and effort. This exploratory study offers relevant insights on the use of ocular metrics for cognitive load assessment in occupational ergonomics. While the existing eye-tracking technology may yet limit their adoption in the field, they offer advantages over the more popular expert-based and self-reported techniques in measuring changes in cognitive load during dynamic tasks.
Vertical Axis Wind Turbines (VAWT) are currently viewed as promising renewable energy sources. However, they are still insufficiently investigated and implemented. H-Blade VAWT specifically are considered very advantageous, but they suffer from induced drag generated from the vortical flow at the tips of the airfoil. This paper suggests winglets as a design solution capable of managing the vortical flow. Winglets have found much use in the aviation industry as they can simultaneously reduce the induced drag and increase the lift. These features can also be harnessed in wind turbines, enabling enhanced power production and improved rotor starting ability. A H-Blade VAWT, with winglets attached to the tips, is proposed to investigate its aerodynamic performance. For this purpose, a Double Multiple Stream Tube (DMST) model has been carried out at first using the QBlade software to examine the performance of the turbine within various design variations. It has allowed us to obtain an optimized turbine structure with attached winglets. This design has then been investigated using Ansys Fluent 17.2 where an unsteady turbulent fluid flow based on the RANS equations and shear stress transport formulations SST k-ω is adopted. The results showed the advantage of adding winglets to the blades in terms of flow regulation, vortices control and power enhancement.KeywordsH-blade VAWTWingletQBladeDMSTCFDTurbulence
Immunotherapy and vaccines have revolutionized disease treatment and prevention. Vaccines against infectious diseases have been in use for several decades. In contrast, only few cancer vaccines have been approved for human use. These include preventative vaccines against infectious agents associated with cancers, and therapeutic vaccines used as immunotherapy agents to treat cancers. Challenges in developing cancer vaccines include heterogeneity within and between cancer types, screening and identification of appropriate tumour-specific antigens, and the choice of vaccine delivery platforms. Recent advances in all of these areas and the lessons learnt from COVID-19 vaccines have significantly boosted interest in cancer vaccines. Further advances in these areas are expected to facilitate development of effective novel cancer vaccines. In this review, we aim to discuss the past, the present, and the future of cancer vaccines.
This study examines the motivational crowding effects of a traditional monetary incentive – fines – and a relatively new nonmonetary incentive – a public revelation mechanism – on the conservation of common pool resources. Previous literature largely examines the crowding effects of instruments that include both moral suasion and monetary incentives. This paper examines the crowding effects of these incentives beyond moral suasion. We achieve these purposes by implementing a lab experiment in China. We find that, contrary to much of the previous literature, monetary incentives in the form of high penalties crowd in intrinsic motivation. This effect is primarily observed in individuals with the lowest initial extraction levels. Finally, we find that the public revelation mechanism crowds out intrinsic motivation; this crowd-out effect falls primarily on a specific sub-population, conditional cooperators. The debriefings suggest one possible reason for the crowd-out effects: While the public revelation mechanism pressures subjects to not over-harvest, it also reveals others’ extractions, which happens to be higher than expected. This crowds out the conservation effort of conditional cooperators. This informational function of the public revelation mechanism is generally overlooked in previous literature.
Salmonids are ecologically and economically important fishes in Lake Ontario but declines in Alewife (Alosa pseudoharengus), recently the primary prey item, may cause shifts in salmonid diets. Improving our understanding of salmonid trophic niches and diets and whether these have changed over time will provide insight into salmonid foraging patterns, ecology, and management. Using three stable isotopes (δ¹³C, δ¹⁵N and δ³⁴S) and Bayesian models, we estimated core trophic niches, niche overlaps among species, and diets for six salmonid species from Lake Ontario sampled during 2018. We used fin and muscle tissue with different temporal assimilation periods to assess seasonal variability in diet, and investigated salmonid trophic niches and diets among three major spatial units (East, Central, West). Overall, core trophic niches overlapped across all species, except Lake Trout (Salvelinus namaycush). Consistent with previous lake-wide analyses of Lake Ontario salmonid diets, Alewife were the preferred prey fish, although Lake Trout and Atlantic Salmon (Salmo salar) had more varied diets, particularly based on white muscle. Fin-based isotope mixing models predicted greater consumption of shallow (< 30 m depth) Round Goby (Neogobius melanostomus) for Lake Trout, Brown Trout (Salmo trutta), and Rainbow Trout (Oncorhynchus mykiss) than other salmonids, indicating seasonal variation in diets. Lake Trout and Brown Trout also varied across spatial units with greater Round Goby consumption in western Lake Ontario. Spatially distinct diets suggest that Brown Trout and Lake Trout populations should be monitored regionally. Understanding prey consumption trends are important to effectively manage fish populations, especially considering on-going ecological changes in the Great Lakes.
A facile and high yield centrifugal spinning technique known as Forcespinning® (FS) was used to develop unique microstructures consisting of PLA microbeads along alginate fibers. Morphological variation and structural features appeared in the field-emission scanning electron micrographs for the PLA-alginate composites and dried PLA-alginate films from precursor emulsions at constant PLA and varied alginate contents. Shrunk and deflated microbeads were observed for composites whilst spherical beads were evident for the PLA control. Furthermore, PLA was found surrounding the alginate when the alginate was present at 0.24 wt% or lower, while alginate (mushroom-like structures), were seen protruding through the PLA layer at ≥0.34 wt% alginate. Rheological characterization of the composite emulsions revealed that the filler (alginate) provided shear thinning properties including pseudoplasticity, desirable for printing and other related applications in contrast to the Newtonian flow shown by the PLA control. Along with infra-red spectroscopy, the nanocomposites were further characterized using thermal gravimetry and differential scanning calorimetry featuring reversible events influenced by heat capacity and irreversible kinetic/thermodynamic counterparts. The work provides a comprehensive investigation of biocompatible networks of PLA-alginate microbeads embedded in nano-sized fibers and the prospective application of these microbeads as a drug delivery system.
The rising demands for energy use and the increase in environmental and economic concerns necessitate a reduction in energy consumption of thermal systems. A phase change material (PCM) is a viable solution to enhance thermal system performance through its latent heat thermal energy storage capability. This study experimentally investigates an innovative PCM-air-liquid meso heat exchanger to extend the thermal comfort in a vehicle during short periods of engine shutdown. Extended surfaces (fins) are placed inside the PCM medium and integrated throughout the whole heat exchanger to enable and improve the transfer of thermal energy between the PCM and the air. It is found from the experiments that the PCM extends the airside cooling time by more than 4 min when the main coolant is shutdown. A comparison of heat transfer when using PCM to no PCM case revealed a 120 kJ released from the PCM during the discharging process. Furthermore, doubling the air mass flow rate resulted in a 29 % decrease in the cumulative energy transferred to the air. The presented system offers an innovative solution for the start-stop function implemented in many hybrid and electric vehicles. In addition, a transient response of the crossflow heat exchanger is studied due to airside mass velocity variations. A generalized empirical correlation to predict the airside Nusselt number as a function of air mass velocity ratio is derived.
The reasonable investment of suppliers and retailers in precooling and carbon emission reduction technology is important to maintain the freshness of products and improve the overall profit of the supply chain. This paper establishes a game model to examine the impact of the relationship between fresh food suppliers and retailers on the level of R&D investment in precooling technology and carbon emission reduction technology and thence on the overall revenue of the supply chain. This model considers the three cases of whether the two subjects cooperate or not and whether the retailer shares the cost of suppliers’ investment in precooling technology. It is found that the overall supply chain revenue and the level of R&D investment in both technologies are higher in the case of cooperation between the two subjects than in the case of non-cooperation. In a decentralized case when the two subjects do not cooperate, the overall supply chain revenue, and the level of R&D investment in the two technologies, depend on the relationship between the retail price and the wholesale price.
Nest predation is a primary cause of reproductive failure in birds; thus, predators apply strong selective pressure on nesting behaviour, especially risk assessment behaviours during predator encounters at nests. Prey's risk assessments are not static; rather, dynamic risk assessment theory predicts that prey assess risk in real-time and update it according to changes in cues posed by the predator(s). We used drone videography to film nest-flushing behaviours of common eiders, Somateria mollissima, in response to foraging polar bears, Ursus maritimus, on East Bay Island (Nunavut, Canada). We assessed how cue use influenced flushing behaviour and nest fate in a path analysis using 200 observations of 193 eiders in 2017. Our most supported model found that more direct angles of visual gaze and travel angle by polar bears resulted in conspicuous nest flushes by eiders (β = −0.236 ± 0.059), whereas the presence of herring gulls, Larus argentatus, resulted in more discrete flushes of hens walking from their nests (β = −0.181 ± 0.059). Shorter flush initiation distances between eiders and approaching bears resulted in greater nest predation by polar bears (β = −0.203 ± 0.076). We found no support that an eider's visibility from the nest influenced any component of flushing behaviour. We suggest that during encounters with bears, eiders are capable of assessing risk and making appropriate behavioural decisions to reduce the chances of nest loss. However, as the colony experienced heavy predation by bears in 2017, behavioural responses alone appear to be insufficient to mitigate polar bear predation at the population level.
Mosquito borne diseases (MBD) are a major global health concern. To aid MBD management efforts, the distribution of mosquito species is frequently investigated through species distribution models (SDMs). However, the quality these SDMs for management use has not been examined. We evaluated 127 publications of mosquito SDMs published between 1998 and 2020 and assessed each against a set of recently-developed, best-practice standards pertaining to quality of the response variable, predictor variables, model building, and model evaluation aspects. Mosquito SDMs were predominantly trained with presence-background response variables (77% of studies), bioclimatic predictor variables (39-63%), maximum entropy algorithm (54%), and evaluated by area under the receiver operating curve (36%) or confusion matrix metrics (34%). Aedes were the best-studied genus (70 studies). Pan-African (20%) and global (16%) distribution studies dominated. All published studies had one or more unacceptable standards within considered aspects, but no aspect observed unacceptable standards in all publications. The highest proportion of unacceptable standards were observed within predictor variables (60%), followed by model building (53%), model evaluation (34%), and response variable (17%). Response variable and model building demonstrated 8% and 0.2% increases in quality over time, but predictor variables and model evaluation exhibited 6% and 2% decreases in quality, respectively. Quality of mosquito SDMs has not changed since introduction of best practice standards. Quality of mosquito SDMs can be improved by ensuring known species temperature and precipitation thresholds are represented within the response variable. Resolution of predictor variables must be justified from ecological knowledge or statistically approximated. SDMs of mosquitoes require improved evaluation against independent data or creation of geographically-structured data. We encourage future mosquito SDM applications to utilize the most recent SDM standards and recommendations to improve applicability.
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