Nonholonomic constraints in classical field theories

A multisymplectic setting for classical field theories subjected to non-holonomic constraints is presented. The infinite dimensional setting in the space of Cauchy data is also given.Comment: 14 pages; 1 figur

Aplicación FullStack Mi Finquita

El producto final realizado “Mi Finquita” surge de la realización de un proyecto fullstack destinado, por un lado, a proveer de información útil en el sector agrícola en cuanto a la monitorización y mantenimiento de explotaciones agrícolas y, por otro lado, a la visualización ágil y dinámica de información de estaciones meteorológicas, ya sean propias de la explotación, de su entorno, o de una región determinada. El objetivo del proyecto es el de la visualización de datos tomados por estaciones meteorológicas. Además, se han incluido otras formas de visualización de datos como puede ser la obtenida a través de la utilización de satélites, Graniot o Sentinel, siendo estos importantes en cuanto a agricultura de precisión se refiere. Con todo esto se pretende establecer un entorno de prueba al cual el usuario podrá acceder y seleccionar, de las diferentes capas de información disponibles, las que quiera visualizar. Por otro lado, cabe destacar también como finalidad el establecimiento de un rendimiento adecuado de carga de la web, así como de una estética uniforme y que garantice su usabilidad y accesibilidad adaptada. Para este trabajo se ha utilizado el lenguaje de programación C#, para el desarrollo backend, y Angular para el desarrollo del frontend.The final product “Mi Finquita” arises from the realization of a fullstack project that is destined to provide useful information in the agricultural sector in terms of monitoring and maintenance of agricultural operations and, on the other hand, to visualize agile and dynamic information from meteorological stations, whether they are specific to the plantation, its surroundings, or a specific region. The objective of the project is to visualize data of the stations but there are also other ways of data visualization implemented such as the use of satellites, Graniot or Sentinel. These satellites are very important in terms of the precision agriculture. With all this, it is intended to establish a test environment in which the user can enter and select from the different layers of information the ones he wants to see. On the other hand, it is also worth mentioning as a purpose the establishment of an adequate loading performance of the web, as well as an uniform aesthetic that guarantees its usability and adapted accessibility. For this work, the programming language C# has been used for the backend development and the framework Angular for the development of the frontend

Population resistance and recovery after an extreme heat event are explained by thermal effects on life-history traits

Extreme heat events lower the fitness of organisms by inducing physiological stress and increasing metabolic costs. Yet, little is known about the role of life-history traits in elucidating population responses to extreme heat events. Here, we used a trait-based approach to understand population resistance and recovery using four closely related species of soil-dwelling Collembola. We measured thermal reaction norms of life-history traits (survival and reproductive traits) and used this information to identify ecological mechanisms linked to population responses after an extreme heat event (i.e. one week at 26–30°C, representing + 10°C above ambient conditions). Furthermore, we investigated potential shifts in the body size distribution of recovering populations to better understand if extreme heat events can restructure body size spectra within populations. While resistance remained unaltered across species in our study, the recovery response of the most heat-sensitive species (Protaphorura pseudovanderdrifti, predominantly a boreal species) was strongly affected by the extreme heat event (−54% population change compared to ambient conditions). Given that the fecundity (linked to recovery) of P. pseudovanderdrifti was more sensitive to heat than their survival (linked to resistance), we detected a decoupling between population resistance and recovery to an extreme heat event in this species. In addition, the detrimental effects of heat on fecundity were largely responsible for a drop in the proportion of small-sized (juvenile) individuals in the recovering populations of P. pseudovanderdrifti. Thermally insensitive resistance and recovery in the other three species (P. armata, P. fimata, P. tricampata; predominantly temperate species) can be explained by their high survival and fecundity at warmer temperatures. We highlight that life-history trait responses to warming can help explain population resistance and recovery after extreme heat events

Studies on the electromagnetic structure of the nucleon by free and quasi-free Compton scattering at MAMI (Mainz)

Using hydrogen and deuterium targets, Compton scattering by the proton and neutron have been studied at the tagged photon beam of the MAMI (Mainz) accelerator using different experimental setups. The theoretical tools for the analysis of the experimental data have been investigated, as there are the nonsubtracted dispersion theory and the theory of quasi-free reactions on the proton and neutron bound in the deuteron. Experimental Compton scattering data are understood in the first and second resonance region with good precision. Precise electromagnetic polarizabilities and spin polarizabilities for the proton and neutron have been determined

Survival in an extreme habitat: the roles of behaviour and energy limitation

Extreme habitats challenge animals with highly adverse conditions, like extreme temperatures or toxic substances. In this paper, we report of a fish (Poecilia mexicana) inhabiting a limestone cave in Mexico. Several springs inside the cave are rich in toxic H2S. We demonstrate that a behavioural adaptation, aquatic surface respiration (ASR), allows for the survival of P. mexicana in this extreme, sulphidic habitat. Without the possibility to perform ASR, the survival rate of P. mexicana was low even at comparatively low H2S concentrations. Furthermore, we show that food limitation affects the survival of P. mexicana pointing to energetically costly physiological adaptations to detoxify H2

Life on the edge: hydrogen sulfide and the fish communities of a Mexican cave and surrounding waters

Most eucaryotic organisms classified as living in an extreme habitat are invertebrates. Here we report of a fish living in a Mexican cave (Cueva del Azufre) that is rich in highly toxic H2S. We compared the water chemistry and fish communities of the cave and several nearby surface streams. Our study revealed high concentrations of H2S in the cave and its outflow (El Azufre). The concentrations of H2S reach more than 300μM inside the cave, which are acutely toxic for most fishes. In both sulfidic habitats, the diversity of fishes was heavily reduced, and Poecilia mexicana was the dominant species indicating that the presence of H2S has an all-or-none effect, permitting only few species to survive in sulfidic habitats. Compared to habitats without H2S, P. mexicana from the cave and the outflow have a significantly lower body condition. Although there are microhabitats with varying concentrations of H2S within the cave, we could not find a higher fish density in areas with lower concentrations of H2S. We discuss that P. mexicana is one of the few extremophile vertebrates. Our study supports the idea that extreme habitats lead to an impoverished species diversit

Properties of freeze-dried gelatin/clay aerogel composites crosslinked with tannic acid

Polymer-based aerogels are tough, low-density, and thermally insulating materials currently receiving increasing attention. In this work, robust all-natural aerogel composites have been obtained by incorporating nanoscale montmorillonite and tannic acid into a gelatin matrix via freeze-drying. The prepared aerogels exhibited low densities, good compressive properties, and low thermal conductivities. The significant improvement in the thermomechanical properties results from the strong bonding between gelatin and tannic acid. Under fire, the systems exhibited excellent flame retardancy with reduced thermal degradation rate and cone calorimeter burning parameters. A straightforward surface treatment with polydimethylsiloxane gave the aerogels exceptional and durable superhydrophobicity. These multifunctional composite aerogels are considered promising eco-friendly alternatives to synthetic polymer-based foams.Peer ReviewedPostprint (published version

Ice-template crosslinked PVA aerogels modified with tannic acid and sodium alginate

With the commitment to reducing environmental impact, bio-based and biodegradable aerogels may be one approach when looking for greener solutions with similar attributes to current foam-like materials. This study aimed to enhance the mechanical, thermal, and flame-retardant behavior of poly(vinyl alcohol) (PVA) aerogels by adding sodium alginate (SA) and tannic acid (TA). Aerogels were obtained by freeze-drying and post-ion crosslinking through calcium chloride (CaCl2) and boric acid (H3BO3) solutions. The incorporation of TA and SA enhanced the PVA aerogel’s mechanical properties, as shown by their high compressive specific moduli, reaching up to a six-fold increase after crosslinking and drying. The PVA/TA/SA aerogels presented a thermal conductivity of 0.043 to 0.046 W/m·K, while crosslinked ones showed higher values (0.049 to 0.060 W/m·K). Under TGA pyrolytic conditions, char layer formation reduced the thermal degradation rate of samples. After crosslinking, a seven-fold decrease in the thermal degradation rate was observed, confirming the high thermal stability of the formed foams. Regarding flammability, aerogels were tested through cone calorimetry. PVA/TA/SA aerogels showed a significant drop in the main parameters, such as the heat release rate (HRR) and the fire growth (FIGRA). The ion crosslinking resulted in a further reduction, confirming the improvement in the fire resistance of the modified compositionsPeer ReviewedPostprint (published version

Compton Scattering by the Nucleon

The status of Compton scattering by the nucleon at energies of the first and second resonance is summarized. In addition to a general test of dispersion theories and a precise determination of polarizabilities, the validities of four fundamental sum rules are explored. {\it Recommended} averages of experimental values for the electromagnetic polarizabilities and spin-polarizabilities of the nucleon are determined: $\alpha_p=12.0\pm 0.6$, $\beta_p=1.9\mp 0.6$, $\alpha_n= 12.5 \pm 1.7$, $\beta_n= 2.7 \mp 1.8$ (unit $10^{-4}$fm$^3$), $\gamma^{(p)}_\pi= -38.7 \pm 1.8$, $\gamma^{(n)}_\pi = 58.6 \pm 4.0$ (unit $10^{-4}$fm$^4$).Comment: version appearing in the conference proceeding

Locally adapted fish populations maintain small-scale genetic differentiation despite perturbation by a catastrophic flood event

Background: Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence, lead to speciation. Perturbations by catastrophic events, however, can distort such parapatric ecological speciation processes. Here, we asked whether an exceptionally strong flood led to homogenization of gene pools among locally adapted populations of the Atlantic molly (Poecilia mexicana, Poeciliidae) in the Cueva del Azufre system in southern Mexico, where two strong environmental selection factors (darkness within caves and/or presence of toxic H2S in sulfidic springs) drive the diversification of P. mexicana. Nine nuclear microsatellites as well as heritable female life history traits (both as a proxy for quantitative genetics and for trait divergence) were used as markers to compare genetic differentiation, genetic diversity, and especially population mixing (immigration and emigration) before and after the flood. Results: Habitat type (i.e., non-sulfidic surface, sulfidic surface, or sulfidic cave), but not geographic distance was the major predictor of genetic differentiation. Before and after the flood, each habitat type harbored a genetically distinct population. Only a weak signal of individual dislocation among ecologically divergent habitat types was uncovered (with the exception of slightly increased dislocation from the Cueva del Azufre into the sulfidic creek, El Azufre). By contrast, several lines of evidence are indicative of increased flood-induced dislocation within the same habitat type, e.g., between different cave chambers of the Cueva del Azufre. Conclusions: The virtual absence of individual dislocation among ecologically different habitat types indicates strong natural selection against migrants. Thus, our current study exemplifies that ecological speciation in this and other systems, in which extreme environmental factors drive speciation, may be little affected by temporary perturbations, as adaptations to physico-chemical stressors may directly affect the survival probability in divergent habitat types