Smoothing noisy spectroscopic data with many-knot spline method

In this paper, we present the development of a many-knot spline method derived to remove the statistical noise in the spectroscopic data. This method is an expansion of the B-spline method. Compared to the B-spline method, the many-knot spline method is significantly faster.Comment: 3pages, 2 figure

Control and Monitoring of the Online Computer Farm for Offline Processing in LHCb

ISBN 978-3-95450-139-7 - http://accelconf.web.cern.ch/AccelConf/ICALEPCS2013/papers/tuppc063.pdfInternational audienceLHCb, one of the 4 experiments at the LHC accelerator at CERN, uses approximately 1500 PCs (averaging 12 cores each) for processing the High Level Trigger (HLT) during physics data taking. During periods when data acquisition is not required most of these PCs are idle. In these periods it is possible to profit from the unused processing capacity to run offline jobs, such as Monte Carlo simulation. The LHCb offline computing environment is based on LHCbDIRAC (Distributed Infrastructure with Remote Agent Control). In LHCbDIRAC, job agents are started on Worker Nodes, pull waiting tasks from the central WMS (Workload Management System) and process them on the available resources. A Control System was developed which is able to launch, control and monitor the job agents for the offline data processing on the HLT Farm. This control system is based on the existing Online System Control infrastructure, the PVSS SCADA and the FSM toolkit. It has been extensively used launching and monitoring 22.000+ agents simultaneously and more than 850.000 jobs have already been processed in the HLT Farm. This paper describes the deployment and experience with the Control System in the LHCb experiment

Fredholm Modules on P.C.F. Self-Similar Fractals and their Conformal Geometry

The aim of the present work is to show how, using the differential calculus associated to Dirichlet forms, it is possible to construct Fredholm modules on post critically finite fractals by regular harmonic structures. The modules are d-summable, the summability exponent d coinciding with the spectral dimension of the generalized laplacian operator associated with the regular harmonic structures. The characteristic tools of the noncommutative infinitesimal calculus allow to define a d-energy functional which is shown to be a self-similar conformal invariant.Comment: 16 page

Fragment Isospin as a Probe of Heavy-Ion Collisions

Isotope ratios of fragments produced at mid-rapidity in peripheral and central collisions of 114Cd ions with 92Mo and 98Mo target nuclei at E/A = 50 MeV are compared. Neutron-rich isotopes are preferentially produced in central collisions as compared to peripheral collisions. The influence of the size (A), density, N/Z, E*/A, and Eflow/A of the emitting source on the measured isotope ratios was explored by comparison with a statistical model (SMM). The mid-rapidity region associated with peripheral collisions does not appear to be neutron-enriched relative to central collisions.Comment: 12 pages including figure

Spin-filtering and charge- and spin-switching effects in a quantum wire with periodically attached stubs

Spin-dependent electron transport in a periodically stubbed quantum wire in the presence of Rashba spin-orbit interaction (SOI) is studied via the nonequilibrium Green's function method combined with the Landauer-Buttiker formalism. The coexistence of spin filtering, charge and spin switching are found in the considered system. The mechanism of these transport properties is revealed by analyzing the total charge density and spin-polarized density distributions in the stubbed quantum wire. Furthermore, periodic spin-density islands with high polarization are also found inside the stubs, owing to the interaction between the charge density islands and the Rashba SOI-induced effective magnetic field. The proposed nanostructure may be utilized to devise an all-electrical multifunctional spintronic device.Comment: 4 pages, 4 figure

Hall-conductivity sign change and fluctuations in amorphous Nbx_{x}Ge1−x_{1-x} films

The sign change in the Hall conductivity has been studied in thin amorphous Nb$_{1-x}$Ge$_x (x\approx$0.3) films. By changing the film thickness it is shown that the field at which the sign reversal occurs shifts to lower values (from above to below the mean-field transition field $H_{c2}$) with increasing film thickness. This effect can be understood in terms of a competition between a positive normal and a negative fluctuation contribution to the Hall conductivity.Comment: 5 pages, 4 figures, to appear in Phys. Rev.

Theoretical study of the two-proton halo candidate 17^{17}Ne including contributions from resonant continuum and pairing correlations

With the relativistic Coulomb wave function boundary condition, the energies, widths and wave functions of the single proton resonant orbitals for $^{17}$Ne are studied by the analytical continuation of the coupling constant (ACCC) approach within the framework of the relativistic mean field (RMF) theory. Pairing correlations and contributions from the single-particle resonant orbitals in the continuum are taken into consideration by the resonant Bardeen-Cooper-Schrieffer (BCS) approach, in which constant pairing strength is used. It can be seen that the fully self-consistent calculations with NL3 and NLSH effective interactions mostly agree with the latest experimental measurements, such as binding energies, matter radii, charge radii and densities. The energy of $\pi$2s$_{1/2}$ orbital is slightly higher than that of $\pi1d_{5/2}$ orbital, and the occupation probability of the $(\pi$2s$_{1/2})^2$ orbital is about 20%, which are in accordance with the shell model calculation and three-body model estimation

Which blazars are neutrino loud?

Protons accelerated in the cores of active galactic nuclei can effectively produce neutrinos only if the soft radiation background in the core is sufficiently high. We find restrictions on the spectral properties and luminosity of blazars under which they can be strong neutrino sources. We analyze the possibility that neutrino flux is highly beamed along the rotation axis of the central black hole. The enhancement of neutrino flux compared to GeV gamma-ray flux from a given source makes the detection of neutrino point sources more probable. At the same time the smaller open angle reduces the number of possible neutrino-loud blazars compared to the number of gamma-ray loud ones. We present the table of 15 blazars which are the most likely candidates for the detection by future neutrino telescopes.Comment: 9 pages, 5 figures, version to be published in PR

Past, present, and future geo-biosphere interactions on the Tibetan Plateau and implications for permafrost

This manuscript resulted from a Workshop in 2019 at the Senckenberg Research Institute and Natural History Museum Frankfurt, Germany, supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA20100300). J. Liu also thanks the support of the Henan Provincial Key Laboratory of Hydrosphere and Watershed Water Security. T. Ehlers thanks the California Institute of Technology Moore Distinguished Scholar Program for support in completing this manuscript during a sabbatical. J. Liu and T. Bolch thank the support from the Strategic Priority Research Program of the Chinese Academy of Sciences (grants no. XDA20060402, XDA20100300). We thank the German Science Foundation (DFG) for support of the TiP (Tibetan Plateau: Formation-Climate-Ecoystems) priority research program (SPP-1372) for initiating the collaborations that led to this manuscript.Interactions between the atmosphere, biosphere, cryosphere, hydrosphere, and geosphere are most active in the critical zone, a region extending from the tops of trees to the top of unweathered bedrock. Changes in one or more of these spheres can result in a cascade of changes throughout the system in ways that are often poorly understood. Here we investigate how past and present climate change have impacted permafrost, hydrology, and ecosystems on the Tibetan Plateau. We do this by compiling existing climate, hydrologic, cryosphere, biosphere, and geologic studies documenting change over decadal to glacial-interglacial timescales and longer. Our emphasis is on showing present-day trends in environmental change and how plateau ecosystems have largely flourished under warmer and wetter periods in the geologic past. We identify two future pathways that could lead to either a favorable greening or unfavorable degradation and desiccation of plateau ecosystems. Both paths are plausible given the available evidence. We contend that the key to which pathway future generations experience lies in what, if any, human intervention measures are implemented. We conclude with suggested management strategies that can be implemented to facilitate a future greening of the Tibetan Plateau.Publisher PDFPeer reviewe