1,070 research outputs found

    Energy upper bound for structurally-stable N-passive states

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    Passive states are special configurations of a quantum system which exhibit no energy decrement at the end of an arbitrary cyclic driving of the model Hamiltonian. When applied to an increasing number of copies of the initial density matrix, the requirement of passivity induces a hierarchical ordering which, in the asymptotic limit of infinitely many elements, pinpoints ground states and thermal Gibbs states. In particular, for large values of N the energy content of a N-passive state which is also structurally stable (i.e. capable to maintain its passivity status under small perturbations of the model Hamiltonian), is expected to be close to the corresponding value of the thermal Gibbs state which has the same entropy. In the present paper we provide a quantitative assessment of this fact, by producing an upper bound for the energy of an arbitrary N-passive, structurally stable state which only depends on the spectral properties of the Hamiltonian of the system. We also show the condition under which our inequality can be saturated. A generalization of the bound is finally presented that, for sufficiently large N, applies to states which are N-passive, but not necessarily structurally stable

    Appropriate end points for the characterization of behavioral changes in developmental toxicology.

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    The present paper is devoted to second- and higher-tier test methods for the characterization of behavioral changes produced in rodents by exposure to noxious agents during development. The paper analyzes a series of end points that are informative about specific processes and underlying regulatory mechanisms but require greater technical sophistication and larger investments than first-tier end points. This applies to ultrasonic emissions in successive postnatal periods; to mother-pup interactions, including appropriate cross-fostering controls; to social (including sexual) interaction tests from the infantile to the young adult stage; and to a variety of conditioning and learning tests using both positive and negative reinforcement

    Estimating flooded area and mean water level using active and passive microwaves: the example of Paraná River Delta floodplain

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    This paper describes a procedure to estimate both the fraction of flooded area and the mean water level in vegetated river floodplains by using a synergy of active and passive microwave signatures. In particular, C band Envisat ASAR in Wide Swath mode and AMSR-E at X, Ku and Ka band, are used. The method, which is an extension of previously developed algorithms based on passive data, exploits also model simulations of vegetation emissivity. The procedure is applied to a long flood event which occurred in the Paraná River Delta from December 2009 to April 2010. Obtained results are consistent with in situ measurements of river water level

    Exploring low-degree nodes first accelerates network exploration

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    We consider information diffusion on Web-like networks and how random walks can simulate it. A well-studied problem in this domain is Partial Cover Time, i.e., the calculation of the expected number of steps a random walker needs to visit a given fraction of the nodes of the network. We notice that some of the fastest solutions in fact require that nodes have perfect knowledge of the degree distribution of their neighbors, which in many practical cases is not obtainable, e.g., for privacy reasons. We thus introduce a version of the Cover problem that considers such limitations: Partial Cover Time with Budget. The budget is a limit on the number of neighbors that can be inspected for their degree; we have adapted optimal random walks strategies from the literature to operate under such budget. Our solution is called Min-degree (MD) and, essentially, it biases random walkers towards visiting peripheral areas of the network first. Extensive benchmarking on six real datasets proves that the---perhaps counter-intuitive strategy---MD strategy is in fact highly competitive wrt. state-of-the-art algorithms for cover

    Working in (Slow) Progress: Socio-Environmental and Economic Dynamics in the Forestry Sector and the Contribution to Sustainable Development in Europe

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    Forest ecosystems are increasingly subject to disturbances, such as extreme (climate) events, fires and pathological outbreaks, which exert significant (and still poorly quantified) economic impacts, despite their intrinsic resilience. How forest management addresses these challenges will have profound effects on human health, environmental diversity, (ecological and economic) productivity and the ability of forest ecosystems to recovery from exogenous shocks. Assuming forests as ensuring ecosystem services that are vital to society and human well-being, in addition to providing wood material, a better knowledge of forest ecosystems appears a key requirement to delineate a developmental strategy that guarantees environmental protection objectives and achievement of climate and energy targets. In the context of Sustainable Development Goals of the United Nations 2030 Agenda, the information available on forest management practices in Europe still seems not completely suitable to provide a comprehensive overview of ecosystem conditions, their economic value, and their biodiversity. Based on a literature review, the present contribution focuses on recent dynamics of the forestry sector in Europe, delineating the inherent complexity in the environmental-economic nexus. Additionally, the extensive use of a key natural resource such as wood exerts social implications for local districts adapting to ecological change-from climate warming to landscape transformations. In line with earlier studies, our paper confirms the role of the technical-economic dimension of forestry in sustainable development paths of districts and regions, affecting together (i) short-term economic dynamics, (ii) the growth prospects of the sector, (iii) the organization of the supply chain, (iv) the interconnections between companies, and (v) investment strategies at large. One of the major issues is the low reliability of official statistics to provide a coherent picture of the actual status of forest resources. At the same time, forestry practices are pivotal in maintaining habitats and species while increasing the timber production that remains (too) sustainable. This is the policy direction constantly given by the European Commission to stimulate over time public bodies and private (in whose hands is about 60% of European forests) to start virtuous paths in the circular economy with considerable repercussions in terms of additional jobs, recycled materials, mt of CO2 equivalent avoided, and increase in community added value. In this context, forestry should assure a more 'holistic' contribution to sustainable development paths at various spatial scales. This means concentrating on both economic and environmental targets based on the identification of significant (ecological-economic) dimensions that may delineate future lines of investigation and policy intervention, while increasing between member countries and regional authorities

    Males with low serum levels of vitamin D have lower pregnancy rates when ovulation induction and timed intercourse are used as a treatment for infertile couples: results from a pilot study

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    Background: Vitamin D (Vit D) is important for the regulation of reproductive physiology. In humans, maternal Vit D deficiency has been implicated in several reproductive- and pregnancy-related disorders. Very few data are available regarding the Vit D status in male partners of couples attempting pregnancy. This observational study (IRB Prot. N. 078/13) aimed to evaluate whether low Vit D serum levels in males might decrease the rate of successful conception in couples attempting pregnancy. Methods: Male and female partners of infertile couples (n = 102) were classified into 2 GROUPS according to normal (≥30 ng/ml) or low (below 30 ng/ml) serum Vit D levels in male partners. Semen analysis was performed in each male participant based on the WHO reference criteria. The female partners of both groups were subjected to 3 consecutive cycles of gonadotropin-induced mono-ovulation. The main outcome measures included the clinical pregnancy rate, delivery per patient and per cycle, and miscarriage rate between the 2 groups evaluated at the end of the three-month period of the study. Results: In male partners of both groups, standard semen analysis did not highlight substantial differences in sperm concentration, sperm progressive motility, or typical form. The pregnancy rates per patient and per cycle and delivery rates per patient and per cycle were all significantly higher (p< 0.05) in couples with normal Vit D levels. Conclusions: These results suggest the existence of a relationship between male Vit D serum levels and semen ability to begin a pregnancy during cycles of timed vaginal intercourse. © 2015 Tartagni et al

    In Vitro Evaluation of the Antibacterial Activity of the Peptide Fractions Extracted from the Hemolymph of Hermetia illucens (Diptera: Stratiomyidae)

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    Antimicrobial peptides (AMPs) are a chemically and structurally heterogeneous family of molecules produced by a large variety of living organisms, whose expression is predominant in the sites most exposed to microbial invasion. One of the richest natural sources of AMPs is insects which, over the course of their very long evolutionary history, have adapted to numerous and different habitats by developing a powerful innate immune system that has allowed them to survive but also to assert themselves in the new environment. Recently, due to the increase in antibiotic-resistant bacterial strains, interest in AMPs has risen. In this work, we detected AMPs in the hemolymph of Hermetia illucens (Diptera, Stratiomyidae) larvae, following infection with Escherichia coli (Gram negative) or Micrococcus flavus (Gram positive) and from uninfected larvae. Peptide component, isolated via organic solvent precipitation, was analyzed by microbiological techniques. Subsequent mass spectrometry analysis allowed us to specifically identify peptides expressed in basal condition and peptides differentially expressed after bacterial challenge. We identified 33 AMPs in all the analyzed samples, of which 13 are specifically stimulated by Gram negative and/or Gram positive bacterial challenge. AMPs mostly expressed after bacterial challenge could be responsible for a more specific activity
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