529 research outputs found

    Geomorphic Constraints on Listric Thrust Faulting: Implications for Active Deformation in the Mackenzie Basin, South Island, New Zealand

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    Deformed fluvial terraces preserved over active thrust-related folds record the kinematics of folding as fault slip accumulates on the underlying thrust. In the Mackenzie Basin of southern New Zealand, the kinematics revealed by folded fluvial terraces along the active Ostler and Irishman Creek fault zones are inconsistent with traditional models for thrust-related folding in which spatially uniform rock uplift typically occurs over planar fault ramps. Instead, warped and tilted terraces in the Mackenzie are characterized by broad, continuous backlimbs and abrupt forelimbs and suggest folding through progressive limb rotation. By relating this pattern of surface deformation to the underlying thrust with a newly developed, simple geometric and kinematic model, we interpret both faults as listric thrusts rooted at depth into gently dipping planar fault ramps. Constraints on the model from detailed topographic surveying of deformed terraces, ground-penetrating radar over active fault scarps, and luminescence dating of terrace surfaces suggest slip rates for the Ostler and Irishman Creek faults of ~1.1– 1.7 mm/yr and~0.5–0.7 mm/yr, respectively. The predicted depth of listric faulting for the Ostler fault (0.70 +0.1-0.2 km) and the Irishman Creek fault (1.3+0.1-0.5 km) generally agrees with geophysical estimates of basin depth in the Mackenzie and suggests control of preexisting basin architecture on the geometry of active thrusting. Despite the potential effects of changes in fault curvature and hanging wall internal deformation, the methodology presented here provides a simple tool for approximating the kinematics of surface deformation associated with slip along listric, or curviplanar, thrust faults

    Charm as a domain wall fermion in quenched lattice QCD

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    We report a study describing the charm quark by a domain-wall fermion (DWF) in lattice quantum chromodynamics (QCD). Our study uses a quenched gauge ensemble with the DBW2 rectangle-improved gauge action at a lattice cutoff of a13a^{-1} \sim 3 GeV. We calculate masses of heavy-light (charmed) and heavy-heavy (charmonium) mesons with spin-parity JP=0J^P = 0^\mp and 11^\mp, leptonic decay constants of the charmed pseudoscalar mesons (DD and DsD_s), and the D0D^0-D0ˉ\bar{D^0} mixing parameter. The charm quark mass is found to be mcMSˉ(mc)=1.24(1)(18)m^{\bar{\rm MS}}_{c}(m_{c})=1.24(1)(18) GeV. The mass splittings in charmed-meson parity partners Δq,J=0\Delta_{q,J=0} and Δq,J=1\Delta_{q, J=1} are degenerate within statistical errors, in accord with experiment, and they satisfy a relation Δq=ud,J>Δq=s,J\Delta_{q=ud, J} > \Delta_{q=s, J}, also consistent with experiment. A C-odd axial vector charmonium state, hc),lies22(11)MeVabovetheh_c), lies 22(11) MeV above the \chi_{c1}meson,or meson, or m_{h_{c}} = 3533(11)_{\rm stat.}MeVusingtheexperimental MeV using the experimental \chi_{c1}) mass. However, in this regard, we emphasize significant discrepancies in the calculation of hyperfine splittings on the lattice. The leptonic decay constants of DD and DsD_s mesons are found to be fD=232(7)stat.(0+6)chiral(11)syst.f_D=232(7)_{\rm stat.}(^{+6}_{-0})_{\rm chiral}(11)_{\rm syst.} MeV and fDs/fD=1.05(2)stat.(2+0)chiral(2)syst.f_{D_s}/f_{D} = 1.05(2)_{\rm stat.}(^{+0}_{-2})_{\rm chiral}(2)_{\rm syst.}, where the first error is statistical, the second a systematic due to chiral extrapolation and the third error combination of other known systematics. The D0D^0-D0ˉ\bar{D^0} mixing bag parameter, which enters the ΔC=2\Delta C = 2 transition amplitude, is found to be BD(2GeV)=0.845(24)stat.(6+24)chiral(105)syst.B_D(2{GeV})=0.845(24)_{\rm stat.}(^{+24}_{-6})_{\rm chiral}(105)_{\rm syst.}.Comment: 49 pages, 15 figure

    Prospects for the Bc Studies at LHCb

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    We discuss the motivations and perspectives for the studies of the mesons of the (bc) family at LHCb. The description of production and decays at LHC energies is given in details. The event yields, detection efficiencies, and background conditions for several Bc decay modes at LHCb are estimated.Comment: 20 pages, 5 eps-figure

    Exclusive Semileptonic Decays of Bc Meson

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    We present a detailed analysis of exclusive semileptonic decays of Bc meson involving pseudoscalar and vector mesons in the BSW framework, by investigating the effects of the flavor dependence on the average transverse quark momentum inside a meson. Branching ratios of exclusive semileptonic decays of Bc meson are predicted.Comment: 15 pages, 2 figure

    A multiscale hybrid model for pro-angiogenic calcium signals in a vascular endothelial cell

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    Cytosolic calcium machinery is one of the principal signaling mechanisms by which endothelial cells (ECs) respond to external stimuli during several biological processes, including vascular progression in both physiological and pathological conditions. Low concentrations of angiogenic factors (such as VEGF) activate in fact complex pathways involving, among others, second messengers arachidonic acid (AA) and nitric oxide (NO), which in turn control the activity of plasma membrane calcium channels. The subsequent increase in the intracellular level of the ion regulates fundamental biophysical properties of ECs (such as elasticity, intrinsic motility, and chemical strength), enhancing their migratory capacity. Previously, a number of continuous models have represented cytosolic calcium dynamics, while EC migration in angiogenesis has been separately approached with discrete, lattice-based techniques. These two components are here integrated and interfaced to provide a multiscale and hybrid Cellular Potts Model (CPM), where the phenomenology of a motile EC is realistically mediated by its calcium-dependent subcellular events. The model, based on a realistic 3-D cell morphology with a nuclear and a cytosolic region, is set with known biochemical and electrophysiological data. In particular, the resulting simulations are able to reproduce and describe the polarization process, typical of stimulated vascular cells, in various experimental conditions.Moreover, by analyzing the mutual interactions between multilevel biochemical and biomechanical aspects, our study investigates ways to inhibit cell migration: such strategies have in fact the potential to result in pharmacological interventions useful to disrupt malignant vascular progressio

    Demostración de resultado económico: percepción del comando da aeronáutica de Brasil

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    No ano de 2010, uma alteração no quadro normativo brasileiro introduziu a Demonstração do Resultado Econômico (DRE) para o setor público, que busca comparar custos internos de produção com valores de mercado, segundo o conceito de custo de oportunidade. Este estudo procura analisar as possíveis respostas estratégicas dos gestores , buscando perceber se a cultura contábil existente no País permite a aceitação do novo instrumento. Por meio das percepções dos agentes públicos do Comando da Aeronáutica (Comaer), no Brasil, conclui-se que a resposta estratégica dos entrevistados tende para a atitude de aceitação da nova rotina, demonstrando traços de menor conservadorismo e maior interesse pela evidenciação de resultados.In 2010, a change in the Brazilian accounting regulatory framework introduced the Demonstração do Resultado Econômico (DRE) [Economic Income Statement] for the public sector, which seeks to compare the internal costs of production to market values, according to the concept of opportunity cost. This study aims to analyse the possible strategic responses of managers and tries to understand if the existing accounting culture in Brazil facilitates the introduction of the new statement. By means of perceptions of officials of the Aeronautical Command (Comaer), in Brazil, it is possible to conclude that the strategic response of respondents is closer to acceptance of the new routine, showing traces of less conservatism and greater interest for displaying results.En el año 2010, una modificación del cuadro normativo brasileño introdujo la Demostración del Resultado Económico (DRE) para el sector público, que busca comparar los costos internos de producción con los valores del mercado, según el concepto de costo de oportunidad. Este estudio tiene como objetivo analizar las posibles respuestas estratégicas de los gestores, con el fin de percibir si la cultura contable existente en el país permite la aceptación del nuevo instrumento. Por medio de las percepciones de los agentes públicos del Comando da Aeronáutica (Comaer), en Brasil, se concluyó que la respuesta estratégica de los entrevistados tiende a aceptar la nueva rutina, mostrando rasgos de menos conservadurismo y más interés por la manifestación de resultados.Fundação para a Ciência e a Tecnologia (FCT

    Rapid Suppression of Activated Rac1 by Cadherins and Nectins during De Novo Cell-Cell Adhesion

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    Cell-cell adhesion in simple epithelia involves the engagement of E-cadherin and nectins, and the reorganization of the actin cytoskeleton and membrane dynamics by Rho GTPases, particularly Rac1. However, it remains unclear whether E-cadherin and nectins up-regulate, maintain or suppress Rac1 activity during cell-cell adhesion. Roles for Rho GTPases are complicated by cell spreading and integrin-based adhesions to the extracellular matrix that occur concurrently with cell-cell adhesion, and which also require Rho GTPases. Here, we designed a simple approach to examine Rac1 activity upon cell-cell adhesion by MDCK epithelial cells, without cell spreading or integrin-based adhesion. Upon initiation of cell-cell contact in 3-D cell aggregates, we observed an initial peak of Rac1 activity that rapidly decreased by ∼66% within 5 minutes, and further decreased to a low baseline level after 30 minutes. Inhibition of E-cadherin engagement with DECMA-1 Fab fragments or competitive binding of soluble E-cadherin, or nectin2alpha extracellular domain completely inhibited Rac1 activity. These results indicate that cadherins and nectins cooperate to induce and then rapidly suppress Rac1 activity during initial cell-cell adhesion, which may be important in inhibiting the migratory cell phenotype and allowing the establishment of initially weak cell-cell adhesions

    Synthetic spatially graded Rac activation drives directed cell polarization and locomotion

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    Migrating cells possess intracellular gradients of Rho GTPases, but it is unknown whether these shallow gradients themselves can induce motility. Here we describe a new method to present cells with induced linear gradients of active, endogenous Rac without receptor activation. Gradients as low as 15% were sufficient to not only trigger cell migration up the synthetic gradient, but also to induce both cell polarization and repolarization. Response kinetics were inversely proportional to Rac gradient values, in agreement with a new mathematical model, suggesting a role for natural input gradient amplification upstream of Rac. Increases in Rac levels beyond a well-defined threshold dramatically augmented polarization and decreased sensitivity to the gradient value. The threshold was governed by initial cell polarity and PI3K activity, supporting a role for both in defining responsiveness to natural or synthetic Rac activation. Our methodology suggests a general way to investigate processes regulated by intracellular signaling gradients

    Unc5B Interacts with FLRT3 and Rnd1 to Modulate Cell Adhesion in Xenopus Embryos

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    The FLRT family of transmembrane proteins has been implicated in the regulation of FGF signalling, neurite outgrowth, homotypic cell sorting and cadherin-mediated adhesion. In an expression screen we identified the Netrin receptors Unc5B and Unc5D as high-affinity FLRT3 interactors. Upon overexpression, Unc5B phenocopies FLRT3 and both proteins synergize in inducing cell deadhesion in Xenopus embryos. Morpholino knock-downs of Unc5B and FLRT3 synergistically affect Xenopus development and induce morphogenetic defects. The small GTPase Rnd1, which transmits FLRT3 deadhesion activity, physically and functionally interacts with Unc5B, and mediates its effect on cell adhesion. The results suggest that FLRT3, Unc5B and Rnd1 proteins interact to modulate cell adhesion in early Xenopus development
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