Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being ...used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations.
The article reviews the current knowledge on the effects that pollution by antibiotics and antibiotic resistance genes may have for the microbiosphere.
Antibiotic resistance is a threat to human and animal health worldwide, and key measures are required to reduce the risks posed by antibiotic resistance genes that occur in the environment. These ...measures include the identification of critical points of control, the development of reliable surveillance and risk assessment procedures, and the implementation of technological solutions that can prevent environmental contamination with antibiotic resistant bacteria and genes. In this Opinion article, we discuss the main knowledge gaps, the future research needs and the policy and management options that should be prioritized to tackle antibiotic resistance in the environment.
In today's society, the trend of ethical consumerism is undeniable. Yet, even though consumers are ethically concerned, they rarely transform their intentions into a green purchasing behaviour—and ...this phenomenon is also evident in the sustainable fashion industry. This study aims to understand the prevailing attitude‐behaviour gap and explores the barriers that constrain consumers in purchasing green apparel. A total of 13 in‐depth interviews were conducted and analysed to the principles of grounded theory. The analysis reveals that the following barriers impede consumption of sustainable fashion: price, availability, knowledge, transparency, image, inertia and consumption habits. The impact of each dimension on consumers' purchase decisions might be of interest to apparel manufacturers and retailers who should implement strategies to encourage eco‐conscious apparel acquisition and focus on diminishing these barriers. Accordingly, three major recommendations are made: (a) to concentrate on specific product attributes; (b) to adopt an efficient digital communication strategy; and (c) to make a greater effort on making green apparel attainable. This study contributes to the overall understanding of consumer behaviour in the ethical fashion industry and examines in‐depth the purchasing criteria for sustainable fashion for consumers.
International shipping has finally set a target to reduce its CO2 emission by at least 50% by 2050. Despite this positive progress, this target is still not sufficient to reach Paris Agreement goals ...since CO2 emissions from international shipping could reach 17% of global emissions by 2050 if no measures are taken. A key factor that hampers the achievement of Paris goals is the knowledge gap in terms of what level of decarbonization it is possible to achieve using all the available technologies. This paper examines the technical possibility of achieving the 1.5° goal of the Paris Agreement and the required supporting policy measures. We project the transport demand for 6 ship types (dry bulk, container, oil tanker, gas, wet product and chemical, and general cargo) based on the Organization for Economic Co-operation and Development’s (OECD’s) global trade projection of 25 commodities. Subsequently, we test the impact of mitigation measures on CO2 emissions until 2035 using an international freight transport and emission model. We present four possible decarbonization pathways which combine all the technologies available today. We found that an 82–95% reduction in CO2 emissions could be possible by 2035. Finally, we examine the barriers and the relevant policy measures to advance the decarbonization of international maritime transport.
Recent advancements on the fabrication of organic micro- and nanostructures have permitted the strong collective light–matter coupling regime to be reached with molecular materials. Pioneering works ...in this direction have shown the effects of this regime in the excited state reactivity of molecular systems and at the same time have opened up the question of whether it is possible to introduce any modifications in the electronic ground energy landscape which could affect chemical thermodynamics and/or kinetics. In this work, we use a model system of many molecules coupled to a surface-plasmon field to gain insight on the key parameters which govern the modifications of the ground-state potential energy surface. Our findings confirm that the energetic changes per molecule are determined by effects that are essentially on the order of single-molecule light–matter couplings, in contrast with those of the electronically excited states, for which energetic corrections are of a collective nature. Hence the prospects of ultrastrong coupling to change ground-state chemical reactions for the parameters studied in this model are limited. Still, we reveal some intriguing quantum-coherent effects associated with pathways of concerted reactions, where two or more molecules undergo reactions simultaneously and which can be of relevance in low-barrier reactions. Finally, we also explore modifications to nonadiabatic dynamics and conclude that, for our particular model, the presence of a large number of dark states yields negligible effects. Our study reveals new possibilities as well as limitations for the emerging field of polariton chemistry.
Broadband Radar Cross-Section Reduction Using AMC Technology Iriarte Galarregui, Juan Carlos; Tellechea Pereda, Amagoia; Martinez de Falcon, Jose Luis ...
IEEE transactions on antennas and propagation,
12/2013, Letnik:
61, Številka:
12
Journal Article
Recenzirano
Odprti dostop
This paper presents the design, fabrication, and characterization of a planar broadband chessboard structure to reduce the radar cross-section (RCS) of an object. The chessboard -like configuration ...is formed by combining two artificial magnetic conductor (AMC) cells. The bandwidth limitations intrinsic to AMC structures are overcome in this work by properly selecting the phase slope versus frequency of both AMC structures. A 180 ° phase difference has been obtained over more than 40% frequency bandwidth with a RCS reduction larger than 10 dB. The influence of the incidence angle in the working bandwidth has been performed. A good agreement between simulations and measurements is achieved.
Polycyclic aromatic hydrocarbons (PAHs) are compounds widespread in the environment, many of them showing carcinogenic effects. These compounds can reach the food chain by different ways and, ...therefore, the analysis of PAHs in food is a matter of concern. This article reviews the extraction methodologies together with the separation and detection techniques which are currently applied in the determination of PAHs in food and beverages. Specific extraction conditions, performance characteristics, chromatographic and detection parameters are discussed. A review of the occurrence of these compounds in the matrixes under study is also provided.
Many insurgent groups operate across international borders, but transnational insurgent activities are seldom observable and little is known about their consequences. In this paper I show that ...activity by Colombian insurgent group FARC increased disproportionately in Colombian municipalities next to the border with Venezuela after Hugo Chávez became president of the latter. I argue that FARC's reliance on short-range weaponry and non-mechanized transportation limited the area in which the group could expand its operations as a result of access to a cross-border safe haven. In consequence, the finding above constitutes evidence of increased FARC presence in Venezuela during the Chávez administration. Exploiting the plausibly exogenous change of government in Venezuela, I find that Colombian municipalities more exposed to a cross-border guerrilla sanctuary experience large increases in the intensity of violence, as well as reductions in local tax revenue and educational enrolment.
As data resources grow, providing recommendations that best meet the demands has become a vital requirement in business and life to overcome the information overload problem. However, building a ...system suggesting relevant recommendations has always been a point of debate. One of the most cost-efficient techniques in terms of producing relevant recommendations at a low complexity is product quantization (PQ). PQ approaches have continued developing in recent years. This system's crucial challenge is improving PQ performance in terms of recall measures without compromising its complexity. This makes the algorithm suitable for problems that require a greater number of potentially relevant items without disregarding others, at high speed and low cost to keep up with traffic. This is the case of online shops where the recommendations for the purpose are important, although customers can be susceptible to scoping other products. A recent approach has been exploiting the notion of norm subvectors encoded in product quantizers. This research proposes a fuzzy approach to perform norm-based PQ. Type-2 fuzzy sets (T2FSs) define the codebook allowing subvectors (T2FSs) to be associated with more than one element of the codebook, and next, its norm calculus is resolved by means of integration. Our method finesses the recall measure up, making the algorithm suitable for problems that require querying at most possible potential relevant items without disregarding others. The proposed approach is tested with three public recommender benchmark datasets and compared against seven PQ approaches for maximum inner-product search. The proposed method outperforms all PQ approaches, such as norm-explicit PQ, PQ, and residual quantization up to +6%, +5%, and +8% by achieving a recall of 94%, 69%, and 59% in Netflix, Audio, and Cifar60k datasets, respectively. Moreover, computing time and complexity nearly equal those of the most computationally efficient existing PQ method in the state of the art.
Microbiota studies of Aedes aegypti and other mosquitoes generally focus on the bacterial communities found in adult female midguts. However, other compartments of the digestive tract maintain ...communities of bacteria which remain almost entirely unstudied. For example, the Dipteran crop is a food storage organ, but few studies have looked at the microbiome of crops in mosquitoes, and only a single previous study has investigated the crop in Ae. aegypti. In this study, we used both culture-dependent and culture-independent methods to compare the bacterial communities in midguts and crops of laboratory reared Ae. aegypti. Both methods revealed a trend towards higher abundance, but also higher variability, of bacteria in the midgut than the crop. When present, bacteria from the genus Elizabethkingia (family Weeksellaceae) dominated midgut bacterial communities. In crops, we found a higher diversity of bacteria, and these communities were generally dominated by acetic acid bacteria (family Acetobacteriaceae) from the genera Tanticharoenia and Asaia. These three taxa drove significant community structure differences between the tissues. We used FAPROTAX to predict the metabolic functions of these communities and found that crop bacterial communities were significantly more likely to contain bacteria capable of methanol oxidation and methylotrophy. Both the presence of acetic acid bacteria (which commonly catabolize sugar to produce acetic acid) and the functional profile that includes methanol oxidation (which is correlated with bacteria found with natural sources like nectar) may relate to the presence of sugar, which is stored in the mosquito crop. A better understanding of what bacteria are present in the digestive tract of mosquitoes and how these communities assemble will inform how the microbiota impacts mosquito physiology and the full spectrum of functions provided by the microbiota. It may also facilitate better methods of engineering the mosquito microbiome for vector control or prevention of disease transmission.
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