154 research outputs found

    Minimum Bias and Underlying Event Measurements with ATLAS

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    A summary of some of the recent minimum bias and underlying event measurements by the ATLAS collaboration is given. The results of several analyses using low-luminosity proton-proton collision data from the LHC taken at center-of-mass energies of sqrt(s) = 0.9, 2.36 and 7 TeV are presented. Data are compared to predictions by several different Monte Carlo event generators. The measurements expose limitations of the phenomenological models in properly describing the measured observables in all regions of phase space.Comment: 9 pages, 5 figures, 1 table; Proceedings for the 3rd Workshop on Multiple-Partonic Interactions at the LHC, Hamburg, Germany, November 201

    Exploring the hidden interior of the Earth with directional neutrino measurements

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    Roughly 40% of the Earth's total heat flow is powered by radioactive decays in the crust and mantle. Geo-neutrinos produced by these decays provide important clues about the origin, formation and thermal evolution of our planet, as well as the composition of its interior. Previous measurements of geo-neutrinos have all relied on the detection of inverse beta decay reactions, which are insensitive to the contribution from potassium and do not provide model-independent information about the spatial distribution of geo-neutrino sources within the Earth. Here we present a method for measuring previously unresolved components of Earth's radiogenic heating using neutrino-electron elastic scattering and low-background, direction-sensitive tracking detectors. We calculate the exposures needed to probe various contributions to the total geo-neutrino flux, specifically those associated to potassium, the mantle and the core. The measurements proposed here chart a course for pioneering exploration of the veiled inner workings of the Earth.Comment: 18 pages, 11 figures, 8 table

    Photon-assisted confinement-induced resonances for ultracold atoms

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    We solve the two-particle s-wave scattering for an ultracold atom gas confined in a quasi-one-dimensional trapping potential which is periodically modulated. The interaction between the atoms is included in terms of Fermi's pseudopotential. For a modulated isotropic transverse harmonic confinement, the atomic center of mass and relative degrees of freedom decouple and an exact solution is possible. We use the Floquet approach to show that additional photon-assisted resonant scattering channels open up due to the harmonic modulation. Applying the Bethe-Peierls boundary condition, we obtain the general scattering solution of the time-dependent Schr\"odinger equation which is universal at low energies. The binding energies and the effective one-dimensional scattering length can be controlled by the external driving

    Implementaci贸n de aisladores s铆smicos en un edificio de viviendas en Lima, Per煤

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    En la actualidad, los sistemas de protecci贸n s铆smica representan una opci贸n viable para la prevenci贸n de desastres naturales como lo es un evento tel煤rico. Nuestro pa铆s se encuentra en la zona del cintur贸n de fuego del pac铆fico, por lo tanto no se debe hacer caso omiso al peligro que un sismo supone. En atenci贸n a ello, se presenta el siguiente estudio que intentar谩 explicar, a grandes rasgos, una tecnolog铆a de protecci贸n s铆smica: la implementaci贸n de aisladores en un edificio de viviendas. Es recurrente que el p煤blico en general, e inclusive ingenieros civiles, tengan interrogantes sobre el comportamiento, tipos, eficiencia y conveniencia de los distintos tipos de aisladores s铆smicos. Por tal motivo, este estudio fue estructurado para describir la tecnolog铆a desde los principios b谩sicos y la filosof铆a del dise帽o, hasta los mecanismos de protecci贸n y propiedades din谩micas de cada uno de los dispositivos. La informaci贸n t茅cnica mostrada corresponde a est谩ndares internacionales, normativa local y pr谩cticas comunes de la ingenier铆a estructural y construcci贸n. Complementario a la informaci贸n te贸rica, se plantea una comparaci贸n entre la propuesta ya construida y su similar con aisladores en una edificaci贸n de viviendas de varios niveles. Se ha seleccionado para el ejercicio un edificio multifamiliar t铆pico del distrito de San Isidro, en la ciudad de Lima: dos s贸tanos y siete niveles de viviendas, incluyendo la azotea. La directriz general que se sigui贸, para realizar la propuesta con aisladores, fue la de restructurar la edificaci贸n con la idea de ahorrar en materiales de construcci贸n y compensar, as铆, el sobrecosto por el concepto de aisladores. Al mismo tiempo, se mantuvo la arquitectura original y la funcionalidad de las viviendas. Finalmente, se resumen los resultados de los an谩lisis de estructuras, de acuerdo a norma, y se presentan los costos de construcci贸n asociados, junto con los beneficios del aislamiento s铆smico, para comparar la conveniencia de su implementaci贸n en el ejercicio mostrado.Tesi

    Longitudinal change in everyday function and behavioral symptoms in frontotemporal dementia

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    Background: The relationship between behavioral changes and functional decline in frontotemporal dementia (FTD) is not well understood. Methods: Thirty-nine patients (21 behavioral variant FTD [bvFTD], 18 semantic variant primary progressive aphasia [svPPA]) were followed up longitudinally (2鈥4 years follow-up). Functional (Disability Assessment for Dementia) and behavioral (Cambridge Behavioural Inventory Revised) assessments were included for between-group (pairwise comparisons, mixed model analysis) and within-group analyses (bivariate correlations). Results: Functionally, patients with bvFTD were more impaired than patients with svPPA at baseline and continued to be at follow-up, despite similar disease duration. By contrast, behavioral impairments differed between patient groups at baseline and at follow-up. At baseline, patients with bvFTD exhibited higher levels of apathy and changes in eating than patients with svPPA; disinhibited and stereotypical behaviors were similar. Over the years, patients with bvFTD showed reduction in disinhibition and stereotypical behavior while apathy and eating changes increased. By contrast, all measured behaviors increased in patients with svPPA over time. Finally, only apathy made longitudinal contributions to functional disability in patients with svPPA, whereas apathy and stereotypical behavior were associated with increased disability in patients with bvFTD. Conclusions: Despite shared overlapping baseline behavioral symptoms, patients with bvFTD are more functionally impaired than patients with svPPA. Apathy has a strong role in disability for both bvFTD and svPPA, but stereotypical behaviors only contributed to functional deficits in patients with bvFTD. Our findings suggest that rigid/compulsive behaviors may in fact support activity engagement in patients with svPPA. Taken together, our results indicate that interventions to reduce disability in the FTD spectrum require an alternative rationale in comparison to Alzheimer disease dementia, and should carefully weigh the interaction of behavioral symptoms and functional status

    Size and conformation limits to secretion of disulfide-bonded loops in autotransporter proteins

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    Autotransporters are a superfamily of virulence factors typified by a channel-forming C terminus that facilitates translocation of the functional N-terminal passenger domain across the outer membrane of Gram-negative bacteria. This final step in the secretion of autotransporters requires a translocation-competent conformation for the passenger domain that differs markedly from the structure of the fully folded secreted protein. The nature of the translocation-competent conformation remains controversial, in particular whether the passenger domain can adopt secondary structural motifs, such as disulfide- bonded segments, while maintaining a secretion-competent state. Here, we used the endogenous and closely spaced cysteine residues of the plasmid-encoded toxin (Pet) from enteroaggregative Escherichia coli to investigate the effect of disulfide bond-induced folding on translocation of an auto-transporter passenger domain. We reveal that rigid structural elements within disulfide-bonded segments are resistant to autotransporter-mediated secretion. We define the size limit of disulfide-bonded segments tolerated by the autotransporter system demonstrating that, when present, cysteine pairs are intrinsically closely spaced to prevent congestion of the translocator pore by large disulfide-bonded regions. These latter data strongly support the hairpin mode of autotransporter biogenesis

    AFTER THE PARADIGM OF CONTEMPORARY PHYSICS IN ARCHITECTURE: SPATIAL POSSIBILITIES AND VARIATIONS

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    Living in the age of scientific, technological and digital revolution changes our attitude towards information. It is inevitable to start approaching information not only as a product of fashionable digital media behavior, but also as a particular accumulation of facts and activities, transferable bits of matter, which influence our environment. Architecture not only exerts spatial influence on our environment, but also it structures its processes. Acting as such, architecture is involved into direct representation of informational flows via organizing spatial systems. Therefore, in the digital era, design gets more related to transforming different informational modes into spatial structures. Transformations of information provide rich possibilities for conceptualizing space; such transformations could be achieved by different methodologies. This paper uses the concept of space in contemporary physics, namely the self-organizational behavior of the spacetime framework, in order to explore various ways of coding information in design. Analyzing String theory and its follower M 鈥 theory, the research derives a method for spatial organization of cause-and-effect activities resulting in a unified approach towards design methodology. This paper explores the concept of movement in the space-time framework, namely the movement in various dimensions and in non-Euclidean geometry, in order to develop a system for achieving a particular design control over informational activities. Using the topology of spacetime in String heory and M-theory, a topology produced as an outcome from that particular movement behavior, the research proposes a way to handle an informational status in the environment spatially. Such a design approach, becoming more and more necessary in the age of the digital, opens room not only for mere spatial variations, but also for a direction towards new design morphology; a morphology in which architecture obtains new spatial value, reaching beyond the label of visionary desig
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