26 research outputs found
The topography of the field and flux inside and above the surfaces of ferromagnetic plates during their contact and contactless magnetization
First observations of separated atmospheric nu_mu and bar{nu-mu} events in the MINOS detector
The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nu” and [overline nu ]” charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving Rup/downdata/Rup/downMC=0.62-0.14+0.19(stat.)±0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nu” and [overline nu ]” interactions are separated. The ratio of [overline nu ]” to nu” events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R[overline nu ][sub mu]/nu[sub mu]data/R[overline nu ][sub mu]/nu[sub mu]MC=0.96-0.27+0.38(stat.)±0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nu” and [overline nu ]”
Electrophysiological and Structural Remodeling in Heart Failure Modulate Arrhythmogenesis. 1D Simulation Study
Background: Heart failure is a final common pathway or descriptor for various cardiac pathologies. It is associated with
sudden cardiac death, which is frequently caused by ventricular arrhythmias. Electrophysiological remodeling, intercellular
uncoupling, fibrosis and autonomic imbalance have been identified as major arrhythmogenic factors in heart failure
etiology and progression.
Objective: In this study we investigate in silico the role of electrophysiological and structural heart failure remodeling on the
modulation of key elements of the arrhythmogenic substrate, i.e., electrophysiological gradients and abnormal impulse
propagation.
Methods: Two different mathematical models of the human ventricular action potential were used to formulate models of
the failing ventricular myocyte. This provided the basis for simulations of the electrical activity within a transmural
ventricular strand. Our main goal was to elucidate the roles of electrophysiological and structural remodeling in setting the
stage for malignant life-threatening arrhythmias.
Results: Simulation results illustrate how the presence of M cells and heterogeneous electrophysiological remodeling in the
human failing ventricle modulate the dispersion of action potential duration and repolarization time. Specifically, selective
heterogeneous remodeling of expression levels for the Na+
/Ca2+ exchanger and SERCA pump decrease these
heterogeneities. In contrast, fibroblast proliferation and cellular uncoupling both strongly increase repolarization
heterogeneities. Conduction velocity and the safety factor for conduction are also reduced by the progressive structural
remodeling during heart failure.
Conclusion: An extensive literature now establishes that in human ventricle, as heart failure progresses, gradients for
repolarization are changed significantly by protein specific electrophysiological remodeling (either homogeneous or
heterogeneous). Our simulations illustrate and provide new insights into this. Furthermore, enhanced fibrosis in failing
hearts, as well as reduced intercellular coupling, combine to increase electrophysiological gradients and reduce electrical
propagation. In combination these changes set the stage for arrhythmias.This work was partially supported by (i) the "VI Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica" from the Ministerio de Economia y Competitividad of Spain (grant number TIN2012-37546-C03-01) and the European Commission (European Regional Development Funds - ERDF - FEDER), (ii) the Direccion General de Politica Cientifica de la Generalitat Valenciana (grant number GV/2013/119), and (iii) Programa Prometeo (PROMETEO/2012/030) de la Conselleria d'Educacio Formacio I Ocupacio, Generalitat Valenciana. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.GĂłmez GarcĂa, JF.; Cardona, K.; Romero PĂ©rez, L.; Ferrero De Loma-Osorio, JM.; TrĂ©nor Gomis, BA. (2014). Electrophysiological and Structural Remodeling in Heart Failure Modulate Arrhythmogenesis. 1D Simulation Study. PLoS ONE. 9(9). https://doi.org/10.1371/journal.pone.0106602S9
Observation of Muon Neutrino Disappearance with the MINOS Detectors in the NuMI Neutrino Beam
This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current ΜΌ interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27Ă1020 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336±14 events. The data are consistent with ΜΌ disappearance via oscillations with |Îm322|=2.74-0.26+0.44Ă10-3ââeV2 and sinâĄ2(2Ξ23)>0.87 (68% C.L.)