12,596 research outputs found

    Measurements of the CKM angle beta in charmless loop-dominated B meson decays at BaBar

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    We report on preliminary measurements of time-dependent CP-violation asymmetries in charmless neutral B meson decays to K+K-K0 (including resonant decays phiK0 and f0K0), eta'K0, pi0K0s, K0sK0sK0s, K0sK0s, rho0K0s, omegaK0s. The results are obtained from a data sample of up to 347 million BBbar pairs produced by e+e- annihilation at the Y(4S) resonance collected with the BaBar detector at the PEP-2 asymmetric-energy B-meson Factory at SLAC.Comment: 6 pages, contributed to the Proceedings of ICHEP200

    A silicon model of auditory localization

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    The barn owl accurately localizes sounds in the azimuthal plane, using interaural time difference as a cue. The time-coding pathway in the owl's brainstem encodes a neural map of azimuth, by processing interaural timing information. We have built a silicon model of the time-coding pathway of the owl. The integrated circuit models the structure as well as the function of the pathway; most subcircuits in the chip have an anatomical correlate. The chip computes all outputs in real time, using analog, continuous-time processing

    Measurements of CKM angles beta/phi_1 and alpha/phi_2 at the BABAR and Belle experiments

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    We report measurements of the CKM angles beta/phi_1 and alpha/phi_2 done by the BABAR and Belle experiments. Both experiments have collected large data samples, corresponding to a total of more than 1 billion of BBbar pairs, at the e^+e^- asymmetric-energy colliders PEP-II (SLAC) and KEK-B (KEK), respectively.Comment: 6 pages, 1 postscript figure, contributed to the Proceedings of Heavy Quarks and Leptons, Melbourne, 200

    A Fast Splitting Method for efficient Split Bregman Iterations

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    In this paper we propose a new fast splitting algorithm to solve the Weighted Split Bregman minimization problem in the backward step of an accelerated Forward-Backward algorithm. Beside proving the convergence of the method, numerical tests, carried out on different imaging applications, prove the accuracy and computational efficiency of the proposed algorithm

    A transcriptional regulatory mechanism finely tunes the firing of type VI secretion system in response to bacterial enemies

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    The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells. For Serratia marcescens, it has been proposed that its T6SS is stochastically expressed, with no distinction between harmless or aggressive competitors. In contrast, we demonstrate that the Rcs regulatory system is responsible for finely tuning Serratia T6SS expression levels, behaving as a transcriptional rheostat. When confronted with harmless bacteria, basal T6SS expression levels suffice for Serratia to eliminate the competitor. A moderate T6SS upregulation is triggered when, according to the aggressor-prey ratio, an unbalanced interplay between homologous and heterologous effectors and immunity proteins takes place. Higher T6SS expression levels are achieved when Serratia is challenged by a contender like Acinetobacter, which indiscriminately fires heterologous effectors able to exert lethal cellular harm, threatening the survival of the Serratia population. We also demonstrate that Serratia’s RcsB-dependent T6SS regulatory mechanism responds not to general stress signals but to the action of specific effectors from competitors, displaying an exquisite strategy to weigh risks and keep the balance between energy expenditure and fitness costs. IMPORTANCE Serratia marcescens is among the health-threatening pathogens categorized by the WHO as research priorities to develop alternative antimicrobial strategies, and it was also recently identified as one major component of the gut microbiome in familial Crohn disease dysbiosis. Type VI secretion systems (T6SSs) stand among the array of survival strategies that Serratia displays. They are contractile multiprotein complexes able to deliver toxic effectors directed to kill bacterial species sharing the same niche and, thus, competing for vital resources. Here, we show that Serratia is able to detect and measure the extent of damage generated through T6SS-delivered toxins from neighboring bacteria and responds by transcriptionally adjusting the expression level of its own T6SS machinery to counterattack the rival. This strategy allows Serratia to finely tune the production of costly T6SS devices to maximize the chances of successfully fighting against enemies and minimize energy investment. The knowledge of this novel mechanism provides insight to better understand bacterial interactions and design alternative treatments for polymicrobial infections.Fil: Lazzaro, Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Feldman, Mario F.. Washington University in St. Louis; Estados UnidosFil: Garcia Vescovi, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

    A probabilistic approach to quantifying hydrologic thresholds regulating migration of adult Atlantic salmon into spawning streams

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    Acknowledgment Data to support this study are provided by the Marine Scotland Science Freshwater Laboratory (MSS-FL) and are available for free download on line [Glover and Malcolm, 2015a, 2015b].Peer reviewedPublisher PD

    Feeding convergence in South American and African zooplanktivorous cichlids Geophagus brasiliensis and Tilapia rendalli

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    Acara, #Geophagus brasiliensis, and red-breasted bream, #Tilapia rendalli, are important planktivorous cichlids in Southern Brazilian lakes and reservoirs. In laboratory experiments, I quantified behavior and selectivity of different sizes of these two fish feeding on lake zooplankton. Feeding behavior depended on fish size. Fish 70 mm were pump-filter feeders. Replicate 1 h feeding trials revealed that, as the relative proportions of prey changed during an experiment, acara (30-42 mm, standard lenght) and tilapia (29-42 mm) shifted from visual feeding on large evasive copepods to filter feeding on small cladocerans and rotifers. Electivity and feeding rate increased with prey lenght, but were distinct for similar-sized cladocerans and copepods. Visual/filter-feeding fish had lowest electivities for small and poorly evasive rotifers and cyclopoid nauplii. (D'après résumé d'auteur

    Marker assisted breeding and mass selection of wheat composite cross populations

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    Utilising diverse populations instead of single line varieties is expected to lead to a number of advantages in cereal production. These include reduced epidemics of plant diseases, improved weed competition and better exploitation of soil nutrients, resulting in improved yield stability. However, a number of challenges must be met before diverse wheat populations can be introduced into commercial wheat production: one of these is the development of breeding technologies based on mass selection which enable breeders and farmers to improve specific traits in populations and maintain diversity at the same time
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