Universidad Politécnica de Cartagena
Recent publications
The fundamental objective of acoustic barriers is to preserve the inhabitants of nearby areas from the high noise generated by road traffic. It is possible to significantly improve the performance of conventional acoustic barriers by attaching small acoustic diffusers on their upper part (caps) that do not imply an appreciable height increase of the barrier, thereby adhering to any height regulation or restriction. This work deepens and yields findings in the study of the acoustic performance of barriers with diffusers of different shapes, number and arrangement through the calculation of their insertion losses (IL). In this research, a design of four Y-shaped diffusing elements arranged according to the well-known fractal pattern called Cantor set is presented and validated through two types of traffic noise sources (‘Car’ and ‘Ambulance’), one listener and a wide frequency band up to 10 kHz. The results demonstrate that the proposed diffuser provides a significant increase in acoustic losses compared to the results obtained in previous works without raising the height of the barrier. To the best of the authors’ knowledge, there are no diffuser structures like the one presented here that have been installed or even proposed/analysed.
In this study, we comment about a wrong proof, at least incomplete, of the closed Newton Cotes error formulas for integration in a closed interval [ a , b ] . \left[a,b]. These error formulas appear as an intuitive generalization of the simple proof for the error formula of the trapezoidal rule, and their proofs present one controversial step, which converts the proofs in mischievous, or at least, this step needs a clear clarification that it is not easy to derive. The correct proof of such formulas comes from a technique based on the Peano kernel.
A bstract Haloscopes, microwave resonant cavities utilized in detecting dark matter axions within powerful static magnetic fields, are pivotal in modern astrophysical research. This paper delves into the realm of cylindrical geometries, investigating techniques to augment volume and enhance compatibility with dipole or solenoid magnets. The study explores volume constraints in two categories of haloscope designs: those reliant on single cavities and those employing multicavities. In both categories, strategies to increase the expanse of elongated structures are elucidated. For multicavities, the optimization of space within magnets is explored through 1D configurations. Three subcavity stacking approaches are investigated, while the foray into 2D and 3D geometries lays the groundwork for future topological developments. The results underscore the efficacy of these methods, revealing substantial room for progress in cylindrical haloscope design. Notably, an elongated single cavity design attains a three-order magnitude increase in volume compared to a WC-109 standard waveguide-based single cavity. Diverse prototypes featuring single cavities, 1D, 2D, and 3D multicavities highlight the feasibility of leveraging these geometries to magnify the volume of tangible haloscope implementations.
We construct a family of compact free boundary minimal annuli immersed in the unit ball B3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb {B}^3$$\end{document} of R3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb {R}^3$$\end{document}, the first such examples other than the critical catenoid. This solves a problem formulated by Nitsche in 1985. These annuli are symmetric with respect to two orthogonal planes and a finite group of rotations around an axis, and are foliated by spherical curvature lines. We show that the only free boundary minimal annulus embedded in B3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb {B}^3$$\end{document} foliated by spherical curvature lines is the critical catenoid; in particular, the minimal annuli that we construct are not embedded. On the other hand, we also construct families of non-rotational compact embedded capillary minimal annuli in B3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb {B}^3$$\end{document}. Their existence solves in the negative a problem proposed by Wente in 1995.
This paper focuses on Grover’s quantum search algorithm, which is of paramount importance as a masterpiece of Quantum Computing software. Given the inherent probabilistic nature of quantum computers, quantum programs based on Grover’s algorithm need to be run a number of times in order to generate a histogram of candidate values for solutions, which are then checked to identify the valid ones. In this paper, the distribution of the required number of shots to find all or a fraction of all the solutions to the Grover’s search problem is studied. Firstly, considering the similarity of the probability problem with the well-known coupon collector’s problem, two formulae are obtained from asymptotic results on the distribution of the required number of shots, as the number of problem solutions grows. These expressions allow to compute the number of shots required to ensure that, with probability p, all or a fraction of all the solutions are found. Secondly, the probability mass function of the required number of shots is derived, which serves as a benchmark to assess the validity of the asymptotic approximations derived previously. A comparison between the two approaches is presented and, as a result, a rule of thumb to decide under which circumstances employ one or the other is proposed.
Environmental challenges have led to a shift toward more sustainable consumption and production patterns. Understanding the factors that influence consumers' choices toward green products is crucial for achieving sustainable development. This study investigates the adoption process of a low‐involvement eco‐innovation, examining the influence of the level of green consumerism, the perception of its technological and symbolic dimensions, social pressure, and social conspicuousness. A sample of 268 observations was examined using the PLS‐SEM methodology. The results highlightthe indirect effect of the level of green consumption on low‐involvement eco‐innovation adoption through the perception of its technological and symbolic dimensions, as well as social pressure and social conspicuousness. These findings have important practical implications for the design of marketing strategies aimed at promoting low‐involvement eco‐innovations. By emphasizing the social benefits and the influence of others on adopting green behaviors, marketers can effectively target consumers and facilitate the transition toward more sustainable consumption patterns.
Using UK data supplied by universities, this paper confirms that women academics earn less than men, even after controlling for a range of covariates. Despite narrowing after 2004/05, the observed (unconditional) pay gap was still −0.089 in 2019/20, while the conditional pay gap was relatively unchanged remaining at around −0.050 in 2019/20. The results are consistent with the literature on why pay gaps might occur, with the key disparity occurring when women face a higher cost of investment and statistical discrimination, linked to bias, to achieve promotion. That is, the results presented here suggest that earnings gaps are significantly reduced when grade-balanced gender sub-groups are compared, suggesting conditional wage differences are more likely due to bias rather than any inherent differences in (research) productivity.
The high Salmonella and Listeria monocytogenes risk in poultry products reinforces the urgent need for new technologies with high antimicrobial effects. In that sense, a combined technology consisting of encapsulated extra virgin olive oil (EVOO) during chicken nugget breading combined with infrared processing was hereby studied at three levels (experiments). The high in vitro EVOO antimicrobial activity (up to 74%), which was 1.2-fold higher against L. monocytogenes than Salmonella , was enhanced after encapsulation (α-cyclodextrin) by 1.5–2.0 and 1.2–1.6-fold, respectively (experiment 1). Oil-free processing (infrared and convection ovens) combined with encapsulated EVOO (2.5 and 1.6% EVOO doses) even enhanced the high in vitro antimicrobial activity of encapsulated EVOO (experiment 2). In the in vivo study (experiment 3), infrared (180 °C, 6.4 min) + convection air (120 °C, 10 min) processing combined with encapsulated EVOO (1.6 and 2.5%) within chicken nugget breading of the chicken nuggets achieved in vivo antimicrobial reductions of 60 and 80% against Salmonella and L. monocytogenes , respectively. In conclusion, this new technology including encapsulated EVOO (1.6–2.5%) within the breading of chicken nuggets and innovative oil-free processing may ensure the food safety of these poultry products very susceptible to the incidence of Salmonella and L. monocytogenes .
Second order accurate Cartesian grid methods have been well developed for interface problems in the literature. However, it is challenging to develop third or higher order accurate methods for problems with curved interfaces and internal boundaries. In this paper, alternative approaches are developed for some interface and internal layer problems based on non-matching grids, in which two mesh sizes are used to obtain comparable high order accuracy near and away from an interface or an internal layer. For one-dimensional, or two-dimensional problems with straight interfaces or boundary layers that are parallel to one of the axes, the discussion is relatively easy. One of the challenges is how to construct a fourth order compact finite difference scheme at border grid points that connect two meshes. The idea is to employ a second order discretization near the interface in the fine mesh and a fourth order discretization away from the interface in the coarse and border grid points. For two-dimensional problems with a curved interface or an internal layer, a level set representation is utilized for which we can build a fine mesh within a tube |φ(x)|≤δh\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$|\varphi ({\varvec{x}}) | \le \delta h$$\end{document} of the interface. A new super-third seven-point discretization that can guarantee the discrete maximum principle has been developed at hanging nodes. The coefficient matrices of the finite difference equations developed in this paper are M-matrices, which leads to the convergence of the finite difference schemes. Non-trivial numerical examples have confirmed the desired accuracy and convergence of the proposed method.
The aim of this study was to evaluate the most abundant native plants that could be used as a bio-monitor of metal(loid) concentration in dry riverbeds affected by mining activities. Three plants species and their respective rhizospheric soils were sampled from the El Beal (Piptatherum miliaceum, 15 samples), La Carrasquilla (Foeniculum vulgare, 10 samples), and Ponce (Dittrichia viscosa, 12 samples) dry riverbeds from the mining district of Cartegena-La Unión (SE Spain). There is scanty bibliography of the capacity of these species to be used as bio-monitors in the dry riverbeds. Plants categorized as a bio-monitor were established according to the bioaccumulation factor (BF), mobility ratio (MR), and linear correlations between metal(loid) concentrations in plants tissues (root or stem)-rhizospheric soils. The rhizospheric soils were highly contaminated for As, Cd, Pb, and Zn (Cf ≥ 6), and moderately contaminated for Mn (1 ≤ Cf < 3). Piptatherum miliaceum presented on Cd similar mean concentrations on rhizospheric soil and root, BF = 1.07, with a strong correlation soil–root (r = 0.61, p = 0.02). Therefore, of the three species with the capacity to grow in the area, Piptatherum miliaceum showed characteristics to be considered as a bio-monitor for Cd, with a BF > 1, and a positive–significant correlation between the rhizospheric soil and roots.
The formal exchange of functional groups in internal positions of two different molecules is of interest in synthetic chemistry, as a simple retrosynthetic strategy. Here we show the formal exchange reaction between internal α–methylene ketones and vinyl ethers, retaining the original C–O bonds. This process offers a new route for the synthesis of vinyl ethers in one step from ketones, including 1,3-diketones, under mild reaction conditions. Besides, the reaction is catalyzed by reusable cheap solids and can be carried out in flow for 20 days without signs of catalyst depletion. Combined experimental and computational mechanistic studies unveil the key role of carbonyl–enol equilibria.
The global coconut water market is projected to grow in the upcoming years, attributed to its numerous health benefits. However, due to its susceptibility to microbial contamination and the limitations of non-thermal decontamination methods, thermal treatments remain the primary approach to ensure the shelf-life stability and the microbiological safety of the product. In this study, the thermal inactivation of Listeria innocua, a Listeria monocytogenes surrogate, was evaluated in coconut water and in tryptone soy broth (TSB) under both isothermal (50–60 °C) and dynamic conditions (from 30 to 60 °C, with temperature increases of 0.5, 1 and 5 °C/min). Mathematical models were used to analyse the inactivation data. The Geeraerd model effectively described the thermal inactivation of L. innocua in both TSB and coconut water under isothermal conditions, with close agreement between experimental data and model fits. Parameter estimates and analysis revealed that acidified TSB is a suitable surrogate medium for studying the thermal inactivation of L. innocua in coconut water, despite minor differences observed in the shoulder length of inactivation curves, likely attributed to the media composition. The models fitted to the data obtained at isothermal conditions fail to predict L. innocua responses under dynamic conditions. This is attributed to the stress acclimation phenomenon that takes place under dynamic conditions, where bacterial cells adapt to initial sub-lethal treatment stages, leading to increased thermal resistance. Fitting the Bigelow model directly to dynamic data with fixed z-values reveals a three-fold increase in D-values with lower heating rates, supporting the role of stress acclimation. The findings of this study aid in designing pasteurization treatments targeting L. innocua in coconut water and enable the establishment of safe, mild heat treatments for refrigerated, high-quality coconut water.
We investigate the use of a single leaky-wave antenna for amplitude-monopulse direction finding, when compared to the more conventional use of two tilted antennas. Thanks to the inherent bidirectional feeding and scanning behavior of leaky-wave antennas, it is demonstrated a more compact and planar design while offering similar functionality in the far field. The frequency beam squinting effect suffered by the leaky-wave antenna, and its capability to create frequency-scanned monopulse patterns, are also analyzed. Moreover, its more reduced size mitigates the near-field effects, thus reporting a superior localization performance in the proximity of the antenna. This is experimentally demonstrated with prototypes designed in the 2.4 GHz ISM band, which are subsequently applied for direction finding of mobile devices connected to a WiFi network.
Intensive and widespread use of pesticides raises serious environmental and human health concerns. The presence and levels of 209 pesticide residues (active substances and transformation products) in 625 environmental samples (201 soil, 193 crop, 20 outdoor air, 115 indoor dust, 58 surface water, and 38 sediment samples) have been studied. The samples were collected during the 2021 growing season, across 10 study sites, covering the main European crops, and conventional and organic farming systems. We profiled the pesticide residues found in the different matrices using existing hazard classifications towards non-target organisms and humans. Combining monitoring data and hazard information, we developed an indicator for the prioritization of pesticides, which can support policy decisions and sustainable pesticide use transitions. Eighty-six percent of the samples had at least one residue above the respective limit of detection. One hundred residues were found in soil, 112 in water, 99 in sediments, 78 in crops, 76 in outdoor air, and 197 in indoor dust. The number, levels, and profile of residues varied between farming systems. Our results show that non-approved compounds still represent a significant part of environmental cocktails and should be accounted for in monitoring programs and risk * Corresponding author at 2 assessments. The hazard profiles analysis confirms the dominance of compounds of low-moderate hazard and underscores the high hazard of some approved compounds and recurring "no data available" situations. Overall, our results support the idea that risk should be assessed in a mixture context, taking environmentally relevant mixtures into consideration. We have uncovered uncertainties and data gaps that should be addressed, as well as the policy implications at the EU approval status level. Our newly introduced indicator can help identify research priority areas, and act as a reference for targeted scenarios set forth in the Farm to Fork pesticide reduction goals.
Antimicrobial cationic peptides (AMPs) are excellent candidates for use as therapeutic antimicrobial agents. Among them, short peptides possessing sequences of 9–11 amino acids have some advantages over long-sequence peptides. However, one of the main limitations of short peptides is that their mechanism of action at the molecular level is not well-known. In this article, we report a model based on multiscale molecular dynamics simulations of short peptides interacting with vesicles containing palmitoyl-oleoyl-phosphatidylglycerol (POPG)/palmitoyl-oleoyl-phosphatidylethanolamine (POPE). Simulations using this approach have allowed us to understand the different behaviors of peptides with antimicrobial activity with respect to those that do not produce this effect. We found remarkable agreement with a series of experimental results directly supporting our model. Moreover, these results allow us to understand the mechanism of action at the molecular level of these short peptides. Our simulations suggest that mechanical inhomogeneities appear in the membrane, promoting membrane rupture when a threshold concentration of peptides adsorbed on the membrane is achieved. These results explain the high structural demand for these peptides to maintain a delicate balance between the affinity for the bilayer surface, a low peptide–peptide repulsion (in order to reach the threshold concentration), and an acceptable tendency to penetrate into the bilayer. This mechanism is different from those proposed for peptides with long amino acid sequences. Such information is very useful from the medicinal chemistry point of view for the design of new small antimicrobial peptides.
A theorem by Almgren establishes that any minimal 2-sphere immersed in \(\mathbb {S}^3\) is a totally geodesic equator. In this paper we give a purely geometric extension of Almgren’s result, by showing that any immersed, real analytic 2-sphere in \(\mathbb {S}^3\) that is saddle, i.e., of non-positive extrinsic curvature, must be an equator of \(\mathbb {S}^3\). We remark that, contrary to Almgren’s theorem, no geometric PDE is imposed on the surface. The result is not true for \(C^{\infty }\) spheres.
We present a protocol to produce a class of non-thermal Fock state mixtures in trapped ions. This class of states features a clear metrological advantage with respect to the ground state, thus overcoming the standard quantum limit without the need for full sideband cooling and Fock-state preparation on a narrow electronic transition. The protocol consists in the cyclic repetition of red-sideband, measurement and preparation laser pulses. By means of the Kraus map representation of the protocol, it is possible to relate the length of the red sideband pulses to the specific class of states that can be generated. With the help of numerical simulations, we analyze the parametric regime where these states can be reliably reproduced.
Extremely low-frequency magnetic fields (ELF-MF), those between 1 and 300 Hz, have been associated with childhood leukemia since the late 1970s [2, 7]. The accumulated evidence provided by several epidemiological studies led the World Health Organization (WHO) in 2002 to consider these types of fields as possibly carcinogenic (category 2B). However, there is still discussion in the scientific community about whether power lines should continue to be classified in that category (e.g., [1]), as observational studies have produced fewer clear results in recent decades (e.g., [6]). This increasing concern about the plausibility of this association has implications for regulations on reference levels of public exposure. Those levels have not been modified for decades and remain two or three orders of magnitude above what epidemiology suggests as a risk threshold (≥200–400 nT, see Ref. [8]). One of the most significant recent contributions to the field is the research by [2]; who conducted separate meta-analyses of studies investigating exposure to magnetic fields and childhood leukemia, utilizing various exposure variables. When the magnetic field was a variable derived from distance-to-line measurements or calculated based on distance, the meta-analyses did not demonstrate a significant relationship between exposure to magnetic fields and childhood leukemia (OR=1.07, p=0.74; OR=1.24, p=0.56, respectively). However, the meta-analysis conducted exclusively with studies that conducted direct measurements of the magnetic field did show a significant association (OR=1.23, p=0.02). This suggests that confounding factors might be present in studies that do not incorporate in situ measurements (e.g., [5]), such as other magnetic field sources that lead to actual exposure differing significantly from estimates based solely on distance to high voltage overhead lines. Underground power lines can constitute a relevant source of magnetic fields, given their proximity to the ground compared to overhead wires. They carry intensities that, in some instances, can be of the same order of magnitude as those of high-voltage overhead lines. The objective of this research is to empirically analyze whether the presence of underground wires results in a significant contribution to the exposure to magnetic fields originating from overhead lines. This analysis aims to offer a plausible explanation for the disparate results observed in the meta-analyses conducted by [2].
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Jose A. Martinez
  • Business Economics
Rafael Asorey Cacheda
  • Department of Information and Communication Technologies
Marta Doval
  • Chemical and Environmental Engineering
Bernardo Martin-Gorriz
  • Agricultural Engineering
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