2,719 research outputs found

    Blob sizes and velocities in the Alcator C-Mod scrape-off layer

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    A new blob-tracking algorithm for the GPI diagnostic installed in the outboard-midplane of Alcator C-Mod is developed. I t tracks large-amplitude fluctuations propagating through the scrape-off layer and calculates blob sizes and velocities. We compare the results of this method to a blob velocity scaling from a simple blob-model for sheath-connected blobs. We further present initial results from a fully three-dimensional blob model that features plasma resistivity as a free parameter

    Atmospheric lepton fluxes at ultrahigh energies

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    In order to estimate the possibility to observe exotic physics in a neutrino telescope, it is essential to first understand the flux of atmospheric neutrinos, muons and dimuons. We study the production of these leptons by high-energy cosmic rays. We identify three main sources of muons of energy E > 10^6 GeV: the weak decay of charm and bottom mesons and the electromagnetic decay of unflavored mesons. Contrary to the standard assumption, we find that eta mesons, not the prompt decay of charm hadrons, are the dominant source of atmospheric muons at these energies. We show that, as a consequence, the ratio between the neutrino and muon fluxes is significantly reduced. For dimuons, which may be a background for long-lived staus produced near a neutrino telescope, we find that pairs of E ~ 10^7 GeV forming an angle above 10^-6 rad are produced through D (80%) or B (10%) meson decay and through Drell-Yan proceses (10%). The frequency of all these processes has been evaluated using the jet code PYTHIA.Comment: 10 pages, 4 figures; published versio

    Identification of a quorum sensing-dependent communication pathway mediating bacteria-gut-brain cross talk

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    Despite recently established contributions of the intestinal microbiome to human health and disease, our understanding of bacteria-host communication pathways with regard to the gut-brain axis remains limited. Here we provide evidence that intestinal neurons are able to “sense” bacteria independently of the host immune system. Using supernatants from cultures of the opportunistic pathogen Staphylococcus aureus (S. aureus) we demonstrate the release of mediators with neuromodulatory properties at high population density. These mediators induced a biphasic response in extrinsic sensory afferent nerves, increased membrane permeability in cultured sensory neurons, and altered intestinal motility and secretion. Genetic manipulation of S. aureus revealed two key quorum sensing-regulated classes of pore forming toxins that mediate excitation and inhibition of extrinsic sensory nerves, respectively. As such, bacterial mediators have the potential to directly modulate gut-brain communication to influence intestinal symptoms and reflex function in vivo, contributing to homeostatic, behavioral, and sensory consequences of infection

    The assessment of Shin's method for the prediction of creatinine kinase-MB elevation after percutaneous coronary intervention: an intravascular ultrasound study

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    Cardiac enzyme release is common after percutaneous coronary intervention (PCI). At present there is no established relationship between the quantity of necrotic core and dense calcium, as assessed by Shin's method using intravascular ultrasound virtual histology (VH-IVUS), and post-PCI creatinine kinase-MB (CK-MB) elevation. A total of 112 consecutive patients with unstable angina and a normal pre-PCI CK-MB level were imaged using VH-IVUS. Patients were divided into 2 groups according to the presence (CK-MB group, n = 22) or absence (non CK-MB group, n = 90) of a post-PCI CK-MB elevation >1.0 the upper limit of normal (3.6 ng/ml). Using Shin's method contours were drawn around the IVUS catheter (instead of the lumen), and the vessel. Mean area and volume of necrotic core and dense calcium were significantly greater in CK-MB group than in non CK-MB group (1.7 ± 0.9 mm2vs. 0.9 ± 0.6 mm2, P < 0.001; 17.2 ± 8.8 mm3vs. 8.8 ± 5.8 mm3, P < 0.001, and 0.9 ± 0.6 mm2vs. 0.4 ± 0.4 mm2, P = 0.001; 9.1 ± 5.8 mm3vs. 3.9 ± 3.7 mm3, P < 0.001, respectively). Percent necrotic core and dense calcium areas calculated by external elastic membrane (EEM) area were significantly greater in CK-MB group than in non CK-MB group (11.9 ± 5.1 vs. 6.6 ± 4.0%, P < 0.001 and 6.5 ± 4.0 vs. 3.0 ± 2.9%, P 

    Alterations in Wnt- and/or STAT3 signaling pathways and the immune microenvironment during metastatic progression

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    Metastatic breast cancer is an extremely complex disease with limited treatment options due to the lack of information about the major characteristics of metastatic disease. There is an urgent need, therefore, to understand the changes in cellular complexity and dynamics that occur during metastatic progression. In the current study, we analyzed the cellular and molecular differences between primary tumors and paired lung metastases using a syngeneic p53-null mammary tumor model of basal-like breast cancer. Distinct subpopulations driven by the Wnt- and/or STAT3 signaling pathways were detected in vivo using a lentiviral Wnt- and STAT3 signaling reporter system. A significant increase in the overlapping populations driven by both the Wnt- and STAT3 signaling pathways was observed in the lung metastases as compared to the primary tumors. Furthermore, the overlapping populations showed a higher metastatic potential relative to the other populations and pharmacological inhibition of both signaling pathways was shown to markedly reduce the metastatic lesions in established lung metastases. An analysis of the unique molecular features of the lung metastases revealed a significant association with immune response signatures. Specifically, Foxp3 gene expression was markedly increased and elevated levels of Foxp3 + Treg cells were detected in close proximity to lung metastases. Collectively, these studies illustrate the importance of analyzing intratumoral heterogeneity, changes in population dynamics, and the immune microenvironment during metastatic progression

    Correlation energies of inhomogeneous many-electron systems

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    We generalize the uniform-gas correlation energy formalism of Singwi, Tosi, Land and Sjolander to the case of an arbitrary inhomogeneous many-particle system. For jellium slabs of finite thickness with a self-consistent LDA groundstate Kohn-Sham potential as input, our numerical results for the correlation energy agree well with diffusion Monte Carlo results. For a helium atom we also obtain a good correlation energy.Comment: 4 pages,1 figur

    On the Size of the Dark Side of the Solar Neutrino Parameter Space

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    We present an analysis of the MSW neutrino oscillation solutions of the solar neutrino problem in the framework of two-neutrino mixing in the enlarged parameter space (Δm2,tan2θ)(\Delta m^2, \tan^2\theta) with θ(0,π2)\theta \in (0,\frac{\pi}{2}). Recently, it was pointed out that the allowed region of parameters from a fit to the measured total rates can extend to values θπ4\theta \geq \frac{\pi}{4} (the so called ``dark side'') when higher confidence levels are allowed. The purpose of this letter is to reanalize the problem including all the solar neutrino data available, to discuss the dependence on the statistical criteria in the determination of the CL of the ``dark side'' and to extract the corresponding limits on the largest mixing allowed by the data. Our results show that when the Super-Kamiokande data on the zenith angle distribution of events and the spectrum information is included, the regions extend more into the dark side.Comment: 5 pages,latex file using RevTex. Two-layer aproximation for the Earth density replaced by numerical integration with PREM. Latest parametrization of the sun matter density (BP2000) is included. Misprints corrected. Conclusions unchanged. 5 postscript figures (bitmapped for compression). A full version of the paper can be found at http://ific.uv.es/~penya/papers/ To appear in Phys. Rev.
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