753 research outputs found

    Magnetic linear dichroism in x-ray emission spectroscopy: Yb in Yb3 Fe5 O12

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    A magnetic linear dichroism MLD effect of up to 5% has been observed in the 2p 1/2 4d x-ray emission spectrum of Yb in Yb 3 Fe 5 O 12 . The spectral shape is well reproduced with an atomic multiplet calculation of the 4d to 2p decay. It is shown that the details of the spectral shapes are determined by the 4d4 f exchange interaction. While the integrated intensity of the MLD effect is zero, the magnitude of the effect is a direct measure of the 4 f magnetic moment of Yb. The technique is applicable to all rare-earth and transition-metal systems (probing the 3d magnetic moment). With respect to x-ray-absorption magnetic circular dichroism it possesses the advantage that (i) hard x rays are involved and (ii) no circular polarization is needed. Therefore all complications related to electron detection, soft x-ray experiments, and circular polarization disappear. Potential applications include the study of ~buried! magnetic systems in situ, at high pressures, varying (high) magnetic fields, and varying temperatures

    R2D2 - a symmetric measurement of reactor neutrinos free of systematical errors

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    We discuss a symmetric setup for a reactor neutrino oscillation experiment consisting of two reactors separated by about 1 km, and two symmetrically placed detectors, one close to each reactor. We show that such a configuration allows a determination of sin22θ13\sin^22\theta_{13} which is essentially free of systematical errors, if it is possible to separate the contributions of the two reactors in each detector sufficiently. This can be achieved either by considering data when in an alternating way only one reactor is running or by directional sensitivity obtained from the neutron displacement in the detector.Comment: 11 pages, 3 figures, clarifications added, some numbers in relation with the neutron displacement corrected, version to appear in JHE

    Pulmonary function is associated with distal aortic calcium, not proximal aortic distensibility. MESA lung study

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    Forced expiratory volume in one second strongly predicts mortality from cardiovascular disease. FEV1 has been associated with aortic stiffness a strong independent predictor of cardiovascular mortality. However, the anatomical site and possible mechanisms linking aortic stiffness and lung function are unknown. We therefore examined if FEV1 and CT percent emphysema were associated with calcification of the abdominal aorta or reduced distensibility of the proximal thoracic aorta.The Multi-Ethnic Study of Atherosclerosis (MESA) measured aortic calcification on cardiac and abdominal CT scans and proximal aortic distensibility using magnetic resonance among participants aged 45–84 years without clinical cardiovascular disease. Spirometry was measured following ATS/ERS guidelines and percent emphysema was measured in the lung fields of cardiac CT scans. Multivariate analyses adjusted for age, sex, race/ethnicity and cardiovascular risk factors. Of 1,917 participants with aortic distensibility measures, 13% were current and 38% were former smokers. Eighteen percent had airflow limitation without asthma. FEV1 was associated with the extent of distal aortic calcification (0.76; 95%CI 0.60–0.97, p = 0.02) but not proximal aortic calcification or proximal aortic distensibility (−0.04 mmHg−1; 95%CI −0.16–0.09 mmHg−1, p = 0.60). Percent emphysema was associated with neither measure. FEV1 was associated with severity of distal aortic calcification where it was present independently of smoking and other cardiovascular risk factors but not with distensibility or calcification of the proximal aorta

    Network development in biological gels: role in lymphatic vessel development

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    In this paper, we present a model that explains the prepatterning of lymphatic vessel morphology in collagen gels. This model is derived using the theory of two phase rubber material due to Flory and coworkers and it consists of two coupled fourth order partial differential equations describing the evolution of the collagen volume fraction, and the evolution of the proton concentration in a collagen implant; as described in experiments of Boardman and Swartz (Circ. Res. 92, 801–808, 2003). Using linear stability analysis, we find that above a critical level of proton concentration, spatial patterns form due to small perturbations in the initially uniform steady state. Using a long wavelength reduction, we can reduce the two coupled partial differential equations to one fourth order equation that is very similar to the Cahn–Hilliard equation; however, it has more complex nonlinearities and degeneracies. We present the results of numerical simulations and discuss the biological implications of our model

    Myotube growth is associated with cancer-like metabolic reprogramming and is limited by phosphoglycerate dehydrogenase

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    Funding Information: Brendan M. Gabriel was supported by fellowships from the Novo Nordisk Foundation ( NNF19OC0055072 ) & the Wenner-Gren Foundation , an Albert Renold Travel Fellowship from the European Foundation for the Study of Diabetes , and an Eric Reid Fund for Methodology from the Biochemical Society . Abdalla D. Mohamed was funded initially by Sarcoma UK (grant number SUK09.2015 ), then supported by funding from Postdoctoral Fellowship Program ( Helmholtz Zentrum München, Germany ), and currently by Cancer Research UK . Publisher Copyright: © 2023 The AuthorsPeer reviewedPublisher PD

    Rotational master equation for cold laser-driven molecules

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    The equations of motion for the molecular rotation are derived for vibrationally cold dimers that are polarized by off-resonant laser light. It is shown that, by eliminating electronic and vibrational degrees of freedom, a quantum master equation for the reduced rotational density operator can be obtained. The coherent rotational dynamics is caused by stimulated Raman transitions, whereas spontaneous Raman transitions lead to decoherence in the motion of the quantized angular momentum. As an example the molecular dynamics for the optical Kerr effect is chosen, revealing decoherence and heating of the molecular rotation.Comment: 11 pages, 5 figures, to appear in Phys. Rev.

    Dietary Folate and APC Mutations in Sporadic Colorectal Cancer.

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    Folate deficiency has been associated with colorectal cancer risk and may be involved in colorectal carcinogenesis through increased chromosome instability, gene mutations, and aberrant DNA methylation. Within the Netherlands Cohort Study on diet and cancer, we investigated the associations between dietary folate intake and colorectal cancer risk with (APC+) and without (APC-) truncating APC mutations, accounting for hMLH1 expression and K-ras mutations. In total, 528 cases and 4200 subcohort members were available for data analyses of the study cohort (n = 120,852) from a follow-up period between 2.3 and 7.3 y after baseline. Adjusted gender-specific incidence rate ratios (RR) over tertiles of folate intake were calculated in case-cohort analyses for colon and rectal cancer. Although relatively high folate intake was not associated with overall colorectal cancer risk, it reduced the risk of APC- colon tumors in men (RR 0.58, 95% CI 0.32-1.05, P trend = 0.06 for the highest vs. lowest tertile of folate intake). In contrast, it was positively associated with APC+ colon tumors in men (highest vs. lowest tertile: RR 2.77, 95% CI 1.29-5.95, Ptrend = 0.008) and was even stronger when the lack of hMLH1 expression and K-ras mutations were excluded (RR 3.99, 95% CI 1.43-11.14, Ptrend = 0.007). Such positive associations were not observed among women; nor was folate intake associated with rectal cancer when APC mutation status was taken into account. Relatively high folate consumption reduced the risk of APC- colon tumors, but folate intake was positively associated with APC+ colon tumors among men. These opposite results may indicate that folate enhances colorectal carcinogenesis through a distinct APC mutated pathway. © 2006 American Society for Nutrition

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters
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