398 research outputs found

    Transition from discrete to continuous time of arrival distribution for a quantum particle

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    We show that the Kijowski distribution for time of arrivals in the entire real line is the limiting distribution of the time of arrival distribution in a confining box as its length increases to infinity. The dynamics of the confined time of arrival eigenfunctions is also numerically investigated and demonstrated that the eigenfunctions evolve to have point supports at the arrival point at their respective eigenvalues in the limit of arbitrarilly large confining lengths, giving insight into the ideal physical content of the Kijowsky distribution.Comment: Accepted for publication in Phys. Rev.

    Análisis de las diversas metodologías para el estudio del sistema de atraque en terminales portuarias

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    This paper is concerned with the study of the berth system in port terminals. The main objective is to present the management methodologies, which include empirical methods, analytical methods and simulation methods The comparison shows that these three methods are not independent, but they are complementary. Each method has advantages and limitations and these depend on the type of study performed

    Effect of starch substitution with crude glycerol on growing rabbit and lactating doe performance

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    The aim of this work was to study the effect of dietary inclusion of 2.5 or 5.0% of glycerol in substitution for starch on performance of lactating does and fattening rabbits. Over four consecutive reproductive cycles, a total of 81 New Zealand ´ Californian rabbit does and 813 young rabbits weaned at 25 (fattening trial 1) or 35 (fattening trial 2) days of age were allocated at random to the experimental treatments. Inclusion of glycerol in the diet up to 5% did not influence total feed consumption of does and suckling rabbits, body weight and bioelectrical impedance of does at parturition or at day 21 of lactation and litter weight at weaning, or reproductive efficiency. Substitution of starch with glycerol did not affect feed intake, weight gain or mortality during fattening. The results of the current study indicate that crude glycerol from the biofuel industry can be used at levels up to 5% in rabbit diets without any detrimental or beneficial effect on performanc

    Angiotensin II receptor blockade alleviates calcineurin inhibitor nephrotoxicity by restoring cyclooxygenase 2 expression in kidney cortex

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    Aim: The use of calcineurin inhibitors such as cyclosporine A (CsA) for immunosuppression after solid organ transplantation is commonly limited by renal side effects. CsA-induced deterioration of glomerular filtration rate and sodium retention may be related to juxtaglomerular dysregulation as a result of suppressed cyclooxygenase 2 (COX-2) and stimulated renin biosynthesis. We tested whether CsA-induced COX-2 suppression is caused by hyperactive renin-angiotensin system (RAS) and whether RAS inhibition may alleviate the related side effects. Methods: Rats received CsA, the RAS inhibitor candesartan, or the COX-2 inhibitor celecoxib acutely (3 days) or chronically (3 weeks). Molecular pathways mediating effects of CsA and RAS on COX-2 were studied in cultured macula densa cells. Results: Pharmacological or siRNA-mediated calcineurin inhibition in cultured cells enhanced COX-2 expression via p38 mitogen-activated protein kinase and NF-kB signalling, whereas angiotensin II abolished these effects. Acute and chronic CsA administration to rats led to RAS activation along with reduced cortical COX-2 expression, creatinine clearance and fractional sodium excretion. Evaluation of major distal salt transporters, NKCC2 and NCC, showed increased levels of their activating phosphorylation upon CsA. Concomitant candesartan treatment blunted these effects acutely and completely normalized the COX-2 expression and renal functional parameters at long term. Celecoxib prevented the candesartan-induced improvements of creatinine clearance and sodium excretion. Conclusion: Suppression of juxtaglomerular COX-2 upon CsA results from RAS activation, which overrides the cell-autonomous, COX-2-stimulatory effects of calcineurin inhibition. Angiotensin II antagonism alleviates CsA nephrotoxicity via the COX-2-dependent normalization of creatinine clearance and sodium excretion

    Captive Housing during Water Vole (Arvicola terrestris) Reintroduction: Does Short-Term Social Stress Impact on Animal Welfare?

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    Background: Animals captive bred for reintroduction are often housed under conditions which are not representative of their preferred social structure for at least part of the reintroduction process. Specifically, this is most likely to occur during the final stages of the release programme, whilst being housed during transportation to the release site. The degree of social stress experienced by individuals during this time may negatively impact upon their immunocompetence. Methodology/Principal Findings: We examined two measure of stress - body weight and Leukocyte Coping Capacity (LCC) - to investigate the effects of group size upon captive-bred water voles destined for release within a reintroduction program. Water voles were housed in laboratory cages containing between one and eight individuals. LCC scores were negatively correlated with group size, suggesting that individuals in larger groups experienced a larger degree of immunosuppression than did individuals housed in smaller groups or individually. During the course of the study mean body weights increased, in contrast to expectations from a previous study. This was attributed to the individuals sampled being sub-adults and thus growing in length and weight during the course of the investigation. Conclusions/Significance: The reintroduction process will inevitably cause some stress to the release cohort. However, for water voles we conclude that the stress experienced may be reduced by decreasing group size within captive colony and/or transportation housing practises. The findings are of significance to other species' reintroductions, in highlighting the need to consider life-history strategies when choosing housing systems for animals being maintained in captivity prior to release to the wild. A reduction in stress experienced at the pre-release stage may improve immunocompetence and thus animal welfare and initial survival post-release

    Use of a new ocular insert versus conventional mydriasis in cataract surgery

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    Background. To compare the efficacy and safety of a new ocular insert versus conventional mydriasis in cataract surgery. Methods. We selected 70 patients undergoing cataract surgery. Thirty five patients (Group 1) received instillation of mydriatic drops (tropicamide 1%, phenylephrine 10%, and cyclopentolate 1%) prior to surgery, and 35 patients (Group 2) had a Mydriasert insert (Théa Pharma) (0.28¿mg of tropicamide and 5.4¿mg of phenylephrine hydrochloride) placed in the inferior fornix. Pupil size before and after surgery, blood pressure, and heart rate were measured. Results. Before surgery, pupil diameter was ¿mm in Group 1 and in Group 2 ( ). Twenty four hours after surgery, pupil diameter was ¿mm in Group 1 and in Group 2 ( ). There were no statistically significant differences in blood pressure or heart rate between groups. Conclusions. The effect of the Mydriasert insert was similar to conventional mydriatic agents. Pupil size was restored to normal faster when using the Mydriasert insert compared with conventional mydriatic agents for pupil dilation

    Switcher-random-walks: a cognitive-inspired mechanism for network exploration

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    Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life specific experiences. The organization of concepts within semantic memory can be understood as a semantic network, where the concepts (nodes) are associated (linked) to others depending on perceptions, similarities, etc. Lexical access is the complementary part of this system and allows the retrieval of such organized knowledge. While conceptual information is stored under certain underlying organization (and thus gives rise to a specific topology), it is crucial to have an accurate access to any of the information units, e.g. the concepts, for efficiently retrieving semantic information for real-time needings. An example of an information retrieval process occurs in verbal fluency tasks, and it is known to involve two different mechanisms: -clustering-, or generating words within a subcategory, and, when a subcategory is exhausted, -switching- to a new subcategory. We extended this approach to random-walking on a network (clustering) in combination to jumping (switching) to any node with certain probability and derived its analytical expression based on Markov chains. Results show that this dual mechanism contributes to optimize the exploration of different network models in terms of the mean first passage time. Additionally, this cognitive inspired dual mechanism opens a new framework to better understand and evaluate exploration, propagation and transport phenomena in other complex systems where switching-like phenomena are feasible.Comment: 9 pages, 3 figures. Accepted in "International Journal of Bifurcations and Chaos": Special issue on "Modelling and Computation on Complex Networks

    Price-denomination effect: Choosing to pay with denominations that are the same as the product prices

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    Building on past research on judgment anchoring, we investigate the effect of price information on consumers’ choice of denomination when making a purchase. Across seven experiments, including two in the field (N = 4,020), we find that people tend to purchase with denominations that are the same as the product prices. They use larger denominations for higher priced products that are priced at the value of the denomination held, and smaller denominations for lower priced products that are priced at the value of the smaller denomination held. The effect is not explained by storage or purchase convenience. We propose the “price-denomination effect” is driven by consumers anchoring on product price and then choosing the denomination that matches the anchor. The effect replicates across participants from different continents (United States, Europe, and Africa) and samples (online panelists, and actual consumers), as well as prices in different currencies (United States $, €, and Nigerian Naira). We further demonstrate that people’s preference for denominations also affects the choice of the form of payment used: cash versus card. Consumers are more likely to use cash (vs. card) when product price is exactly the same as a denomination held. We conclude with a discussion of theoretical and practical implications

    New functionalities for the Tonatiuh ray-tracing software

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    ABSTRACT: Tonatiuh is an open source, freeware, Monte Carlo ray tracer suitable for CST applications, and is currently under further development to to increase and improve its functionalities. Work has recently been performed to implement the following functionalities: a flux distribution calculation utility; materials with incidence angle dependent optical properties; and the ability to import 3D geometries from CAD files. This paper provides a detailed account of these new functionalities, and the tests performed to establish their correct implementation in the new software version, Tonatiuh v 2.2.3info:eu-repo/semantics/publishedVersio
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