3,460 research outputs found

    de Broglie-Proca and Bopp-Podolsky massive photon gases in cosmology

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    We investigate the influence of massive photons on the evolution of the expanding universe. Two particular models for generalized electrodynamics are considered, namely de Broglie-Proca and Bopp-Podolsky electrodynamics. We obtain the equation of state (EOS) P=P(ε)P=P(\varepsilon) for each case using dispersion relations derived from both theories. The EOS are inputted into the Friedmann equations of a homogeneous and isotropic space-time to determine the cosmic scale factor a(t)a(t). It is shown that the photon non-null mass does not significantly alter the result at1/2a\propto t^{1/2} valid for a massless photon gas; this is true either in de Broglie-Proca's case (where the photon mass mm is extremely small) or in Bopp-Podolsky theory (for which mm is extremely large).Comment: 8 pages, 2 figures; v2 matches the published versio

    Phase Transition in Asymmetrical Superfluids I: Equal Fermi Surfaces

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    In this paper, we study phase transitions in asymmetrical fermion superfluids. In this scenario, the candidates to form pair are particles with mismatched masses and chemical potentials. We derive an expression for the critical temperature in terms of the gap and masses (or chemical potentials) when the constraint of equal Fermi surfaces maμa=mbμbm_a\mu_a = m_b\mu_b is imposed.Comment: RevTex, 11 pages, 2 figures, typos corrected and an appendix added, accepted for publication in Phys. Rev.

    A to Z of the Muon anomalous magnetic moment in the MSSM with Pati-Salam at the GUT scale

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    We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an A4 × Z5 family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass m0 and three right-handed soft masses m1, m2, m3, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon (g − 2)μ. Since about two decades, (g − 2)μ suffers a puzzling about 3σ excessoftheexperimentallymeasuredvalueoverthetheoreticalprediction,whichour model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potentially explain di-lepton excesses observed by CMS and ATLAS

    Trends in the extinction of carnivores in Madagascar

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    Tendencias de la extinción de carnívoros en Madagascar La extinción de los depredadores apicales, como los mamíferos carnívoros, puede conllevar cambios drásticos en la estructura de la red alimentaria y la dinámica de los ecosistemas. Dado que todos los mamíferos carnívoros terrestres autóctonos de Madagascar son endémicos, su extinción implica una pérdida notable de biodiversidad en este país. En el presente artículo examinamos las publicaciones sobre mamíferos carnívoros de Madagascar con el propósito de determinar cuáles son las especies que tienen mayor probabilidad de extinguirse en un futuro próximo, en vista de los factores que amenazan su supervivencia. Puntuamos cada factor en función de los efectos que ejerce en las especies. Según nuestros resultados, la especie que tiene más probabilidad de extinguirse es la mangosta rayada grande, Galidictis grandidieri, lo cual no es sorprendente porque esta especie se considera uno de los carnívoros más escasos del mundo, que habita solo en un ecosistema forestal pequeño y amenazado. Asimismo, nuestros resultados ponen de manifiesto la necesidad de disponer de datos sólidos sobre cada especie, a fin de ayudar y respaldar a las autoridades a poner en práctica medidas de conservación.The extinction of top predators, such as mammalian carnivores can lead to dramatic changes in foodweb structure and ecosystem dynamics. Since all native Malagasy terrestrial mammalian carnivores are endemic, their extinction implies a significant loss of biodiversity in Madagascar. Here we review the literature on Madagascar’s mammalian carnivores, aiming to determine which species are most likely to become extinct in the near future in view of the factors threatening their survival. We scored each factor according to its impact on the species. According to our results, the giant–striped mongoose, Galidictis grandidieri, is the most likely species to next become extinct. This is no surprise because this species is considered one of the rarest carnivores in the world, inhabiting only a small, threatened forest ecosystem. Our results emphasize the need for robust data about each species to help and support decision–makers implement conservation measures.Tendencias de la extinción de carnívoros en Madagascar La extinción de los depredadores apicales, como los mamíferos carnívoros, puede conllevar cambios drásticos en la estructura de la red alimentaria y la dinámica de los ecosistemas. Dado que todos los mamíferos carnívoros terrestres autóctonos de Madagascar son endémicos, su extinción implica una pérdida notable de biodiversidad en este país. En el presente artículo examinamos las publicaciones sobre mamíferos carnívoros de Madagascar con el propósito de determinar cuáles son las especies que tienen mayor probabilidad de extinguirse en un futuro próximo, en vista de los factores que amenazan su supervivencia. Puntuamos cada factor en función de los efectos que ejerce en las especies. Según nuestros resultados, la especie que tiene más probabilidad de extinguirse es la mangosta rayada grande, Galidictis grandidieri, lo cual no es sorprendente porque esta especie se considera uno de los carnívoros más escasos del mundo, que habita solo en un ecosistema forestal pequeño y amenazado. Asimismo, nuestros resultados ponen de manifiesto la necesidad de disponer de datos sólidos sobre cada especie, a fin de ayudar y respaldar a las autoridades a poner en práctica medidas de conservación

    Antioxidant activity and total phenolic content of different extracts of delipidified olive oil pomace

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    Introduction: The use of by-products as a source of bioactive compounds with economic added value is one of the objectives of the circular economy. Olive oil industry is a source of olive pomace, as a by-product. The olive pomace used in the present study was the exhausted (delipidified) olive pomace, which is the by-product generated after drying and subsequent hexane extraction of residual oil from the olive pomace. This exhausted olive oil pomace may contain remaining bioactive compounds, such as phenolic compounds, which can be of interest not only for the food industry, but also for the pharmaceutical and cosmetic industries. Objectives: Various types of green methodologies, such as solvent extraction (water and hydroalcoholic), ultrasound-assisted extraction, ultra-turrax-assisted extraction and enzyme-assisted extraction (cellulase; viscoenzyme) were used to obtain extracts rich in bioactive compounds from the exhausted olive oil pomace. The bioactivity of these extracts was evaluated through the antioxidant activity. Conclusions: Among all methodologies used the extractions with enzymes produced the best yields of extraction and the conventional extraction with water at 50 °C produced the best results for the total phenolic content and antioxidant activity: ABTS, DPPH and ORAC.info:eu-repo/semantics/publishedVersio

    Recent highlights in sustainable bio-based edible films and coatings for fruit and vegetable applications

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    The present review paper focuses on recent developments in edible films and coatings made of base compounds from biological sources, namely plants, animals, algae, and microorganisms. These sources include by-products, residues, and wastes from agro-food industries and sea products that contribute to sustainability concerns. Chitosan, derived from animal biological sources, such as crustacean exoskeletons, has been the most studied base compound over the past three years. Polysaccharides typically constitute no more than 3–5% of the film/coating base solution, with some exceptions, like Arabic gum. Proteins and lipids may be present in higher concentrations, such as zein and beeswax. This review also discusses the enrichment of these bio-based films and coatings with various functional and/or bioactive compounds to confer or enhance their functionalities, such as antimicrobial, antioxidant, and anti-enzymatic properties, as well as physical properties. Whenever possible, a comparative analysis among different formulations was performed. The results of the applications of these edible films and coatings to fruit and vegetable products are also described, including shelf life extension, inhibition of microbial growth, and prevention of oxidation. This review also explores novel types of packaging, such as active and intelligent packaging. The potential health benefits of edible films and coatings, as well as the biodegradability of films, are also discussed. Finally, this review addresses recent innovations in the edible films and coatings industry, including the use of nanotechnologies, aerogels, and probiotics, and provides future perspectives and the challenges that the sector is facing.info:eu-repo/semantics/publishedVersio

    Development of the correction procedure for High Volume Instrument elongation measurement.

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    Cotton spinning mills need high-quality fibers to maintain their manufacturing efficiency. Machinery throughput is increasing and it could translate into more processes with higher breaking stress. Consequently, more fibers are susceptible to breaking or damage. To face this problem, breeders must develop new varieties whose fibers can better withstand this mechanical stress. The main tool utilized in cotton breeding programs is the High Volume Instrument (HVI), which reports in a short time measurements such as micronaire, length, color, and strength. This instrument can also determine fiber elongation, but there is no current correction method for it. Both elongation and strength factor into the work-to-break of fibers, which plays a direct role in fiber breakage and spinning performance. The objective of this work was to develop cotton elongation standards, devise a correction procedure for HVI lines, evaluate measurement stability, and validate these results with a set of independent samples. Two commercial bales, one with low and one with high HVI elongation, were identified as potential elongation standards. The potential standards were produced and evaluated. After validation, they were used to correct HVI lines against Stelometer (STrength-ELOngation-METER) measurements. An independent set of samples was tested on corrected HVIs to confirm the effectiveness of the elongation corrected measurements. The HVI data were at least as good as the Stelometer data, with increased data acquisition speed and precision. This research can help cotton breeders to improve fiber elongation and strength at the same time, resulting in better fibers for yarn spinning
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