11,412 research outputs found
One-point fluctuation analysis of IceCube neutrino events outlines a significant unassociated isotropic component and constrains the Galactic contribution
The origins of the extraterrestrial neutrinos observed in IceCube have yet to
be determined. In this study we perform a one-point fluctuation analysis of the
six-year high-energy starting event (HESE) shower data, with fixed
non-Poissonian contributions from atmospheric, Galactic and some extragalactic
components, as well as an isotropic (and weakly non-Poissonian) template. In
addition to the star-forming galaxies and blazars, our analysis suggests the
presence of an additional isotropic component, not associated with any known
class of sources, with best-fit intensity of . For the first time, we
also consider high-energy extrapolations of several phenomenological models for
the diffuse Galactic emission (tuned to both local cosmic-ray data and diffuse
gamma-ray emission in the GeV-TeV domain). We demonstrate the potential of our
framework in discriminating between different scenarios, with possible
implications on the physics of cosmic ray transport in the TeV-PeV range.Comment: 10 pages, 3 figures, accepted for publication in PR
World Checklist of Opiliones species (Arachnida). Part 2: Laniatores – Samooidea, Zalmoxoidea and Grassatores incertae sedis
Including more than 6500 species, Opiliones is the third most diverse order of Arachnida, after the megadiverse Acari and Araneae. This database is part 2 of 12 of a project containing an intended worldwide checklist of species and subspecies of Opiliones, and it includes the members of the suborder Laniatores, infraorder Grassatores of the superfamilies Samooidea and Zalmoxoidea plus the genera currently not allocated to any family (i.e. Grassatores incertae sedis). In this Part 2, a total of 556 species and subspecies are listed.Fil: Kury, Adriano Brilhante. Universidade Federal Do Rio de Janeiro. Museu Nacional; BrasilFil: Souza, Daniele R.. Universidade Federal Do Rio de Janeiro. Museu Nacional; BrasilFil: Pérez González, Abel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin
Manipulating the voltage drop in graphene nanojunctions using a gate potential
Graphene is an attractive electrode material to contact nanostructures down
to the molecular scale since it can be gated electrostatically. Gating can be
used to control the doping and the energy level alignment in the nanojunction,
thereby influencing its conductance. Here we investigate the impact of
electrostatic gating in nanojunctions between graphene electrodes operating at
finite bias. Using first principles quantum transport simulations, we show that
the voltage drop across \emph{symmetric} junctions changes dramatically and
controllably in gated systems compared to non-gated junctions. In particular,
for \emph{p}-type(\emph{n}-type) carriers the voltage drop is located close to
the electrode with positive(negative) polarity, i.e. the potential of the
junction is pinned to the negative(positive) electrode. We trace this behaviour
back to the vanishing density of states of graphene in the proximity of the
Dirac point. Due to the electrostatic gating, each electrode exposes different
density of states in the bias window between the two different electrode Fermi
energies, thereby leading to a non-symmetry in the voltage drop across the
device. This selective pinning is found to be independent of device length when
carriers are induced either by the gate or dopant atoms, indicating a general
effect for electronic circuitry based on graphene electrodes. We envision this
could be used to control the spatial distribution of Joule heating in graphene
nanostructures, and possibly the chemical reaction rate around high potential
gradients.Comment: 6 pages, 7 figure
Correlation of Local Order with Particle Mobility in Supercooled Liquids is Highly System Dependent
We investigate the connection between local structure and dynamical
heterogeneity in supercooled liquids. Through the study of four different
models we show that the correlation between a particle's mobility and the
degree of local order in nearby regions is highly system dependent. Our results
suggest that the correlation between local structure and dynamics is weak or
absent in systems that conform well to the mean-field picture of glassy
dynamics and strong in those that deviate from this paradigm. Finally, we
investigate the role of order-agnostic point-to-set correlations and reveal
that they provide similar information content to local structure measures, at
least in the system where local order is most pronounced.Comment: 6 pages, 3 figures and 6 page sup. with 5 figures and 1 tabl
Prediction of axial-flow instabilities in a turbojet engine by use of a multistage compressor simulation on the digital computer
A method of estimating the undistorted stall line for an axial-flow compressor by using the digital computer is presented. The method involves linearization of nonlinear dynamic equations about an operating point on a speed line, and then application of the first method of Lyapunov to determine the stability of the nonlinear system from the stability of the linear system. The method is applied to a simulation of the J85 compressor, which utilizes stage stacking and lumped volume techniques for the interstage regions to simulate steady-state and dynamic compressor performance. The stability boundary predicted by the digital simulation compares quite well with the stall line predicted by a dynamic simulation of the J85 compressor programmed on the analog computer. Since previous studies have shown that the analog-predicted stall line agrees well with the stall line of the compressor, the digital method presented is also a good means of estimating the stall line
Quantum scalar field in D-dimensional static black hole space-times
An Euclidean approach for investigating quantum aspects of a scalar field
living on a class of D-dimensional static black hole space-times, including the
extremal ones, is reviewed. The method makes use of a near horizon
approximation of the metric and -function formalism for evaluating the
partition function and the expectation value of the field fluctuations
. After a review of the non-extreme black hole case, the extreme
one is considered in some details. In this case, there is no conical
singularity, but the finite imaginary time compactification introduces a cusp
singularity. It is found that the -function regularized partition
function can be defined, and the quantum fluctuations are finite on the
horizon, as soon as the cusp singularity is absent, and the corresponding
temperature is T=0.Comment: 9 pages, LaTe
The Poker Face of Inelastic Dark Matter: Prospects at Upcoming Direct Detection Experiments
The XENON100 and CRESST experiments will directly test the inelastic dark
matter explanation for DAMA's 8.9? sigma anomaly. This article discusses how
predictions for direct detection experiments depend on uncertainties in
quenching factor measurements, the dark matter interaction with the Standard
Model and the halo velocity distribution. When these uncertainties are
accounted for, an order of magnitude variation is found in the number of
expected events at CRESST and XENON100.Comment: 5 pages, 3 figure
Terminal-shock and restart control of a Mach 2.5, mixed compression inlet coupled to a turbofan engine
Results of an experimental program conducted on a mixed-compression inlet coupled to a turbofan engine are presented. Open-loop frequency response data are presented that show the response of shock position (as measured by an average inlet static pressure) to sinusoidal airflow disturbances produced at the compressor face station. Also presented are results showing the effect of different passive terminations (a choke plate or a long duct) on the characteristics of the inlet. Transfer functions obtained by using experimental data are presented and compared to the experimental data. Closed-loop frequency response of shock position (with a proportional-plus-integral controller) is presented. In addition, transient data are presented that show the unstart-restart characteristics of the inlet
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