22,125 research outputs found
A Penetration Depth Study on Li2Pd3B and Li2Pt3B
In this paper we present a penetration depth study on the newly discovered
superconductors LiPdB and LiPtB. Surprisingly, the
low-temperature penetration depth demonstrates distinct behavior in
these two isostructural compounds. In LiPdB, follows an
exponential decay and can be nicely fitted by a two-gap BCS superconducting
model with a small gap K and a large gap K.
However, linear temperature dependence of is observed in LiPtB
below 0.3, giving evidence of line nodes in the energy gap.Comment: 2 pages, submitted to LT2
Non-damping oscillations at flaring loops
Context. QPPs are usually detected as spatial displacements of coronal loops
in imaging observations or as periodic shifts of line properties in
spectroscopic observations. They are often applied for remote diagnostics of
magnetic fields and plasma properties on the Sun. Aims. We combine imaging and
spectroscopic measurements of available space missions, and investigate the
properties of non-damping oscillations at flaring loops. Methods. We used the
IRIS to measure the spectrum over a narrow slit. The double-component Gaussian
fitting method was used to extract the line profile of Fe XXI 1354.08 A at "O
I" window. The quasi-periodicity of loop oscillations were identified in the
Fourier and wavelet spectra. Results. A periodicity at about 40 s is detected
in the line properties of Fe XXI, HXR emissions in GOES 1-8 A derivative, and
Fermi 26-50 keV. The Doppler velocity and line width oscillate in phase, while
a phase shift of about Pi/2 is detected between the Doppler velocity and peak
intensity. The amplitudes of Doppler velocity and line width oscillation are
about 2.2 km/s and 1.9 km/s, respectively, while peak intensity oscillate with
amplitude at about 3.6% of the background emission. Meanwhile, a quasi-period
of about 155 s is identified in the Doppler velocity and peak intensity of Fe
XXI, and AIA 131 A intensity. Conclusions. The oscillations at about 40 s are
not damped significantly during the observation, it might be linked to the
global kink modes of flaring loops. The periodicity at about 155 s is most
likely a signature of recurring downflows after chromospheric evaporation along
flaring loops. The magnetic field strengths of the flaring loops are estimated
to be about 120-170 G using the MHD seismology diagnostics, which are
consistent with the magnetic field modeling results using the flux rope
insertion method.Comment: 9 pages, 9 figures, 1 table, accepted by A&
On cost-effective communication network designing
How to efficiently design a communication network is a paramount task for
network designing and engineering. It is, however, not a single objective
optimization process as perceived by most previous researches, i.e., to
maximize its transmission capacity, but a multi-objective optimization process,
with lowering its cost to be another important objective. These two objectives
are often contradictive in that optimizing one objective may deteriorate the
other. After a deep investigation of the impact that network topology, node
capability scheme and routing algorithm as well as their interplays have on the
two objectives, this letter presents a systematic approach to achieve a
cost-effective design by carefully choosing the three designing aspects. Only
when routing algorithm and node capability scheme are elegantly chosen can
BA-like scale-free networks have the potential of achieving good tradeoff
between the two objectives. Random networks, on the other hand, have the
built-in character for a cost-effective design, especially when other aspects
cannot be determined beforehand.Comment: 6 pages, 4 figure
Implementing topological quantum manipulation with superconducting circuits
A two-component fermion model with conventional two-body interactions was
recently shown to have anyonic excitations. We here propose a scheme to
physically implement this model by transforming each chain of two two-component
fermions to the two capacitively coupled chains of superconducting devices. In
particular, we elaborate how to achieve the wanted operations to create and
manipulate the topological quantum states, providing an experimentally feasible
scenario to access the topological memory and to build the anyonic
interferometry.Comment: 4 pages with 3 figures; V2: published version with minor updation
Pure multiplicative stochastic resonance of anti-tumor model with seasonal modulability
The effects of pure multiplicative noise on stochastic resonance in an
anti-tumor system modulated by a seasonal external field are investigated by
using theoretical analyses of the generalized potential and numerical
simulations. For optimally selected values of the multiplicative noise
intensity quasi-symmetry of two potential minima and stochastic resonance are
observed. Theoretical results and numerical simulations are in good
quantitative agreement.Comment: 5 pages, 5 figure
Full calculation of clumpiness boost factors for antimatter cosmic rays in the light of Lambda-CDM N-body simulation results
Anti-proton and positron Galactic cosmic ray spectra are among the key
targets for indirect detection of dark matter. The boost factors, corresponding
to an enhancement of the signal and linked to the clumpiness properties of the
dark matter distribution, have been taken as high as thousands in the past. The
dramatic impact of these boost factors for indirect detection of antiparticles,
for instance with the PAMELA satellite or the coming AMS-02 experiment, asks
for their detailed calculation. We take into account the results of high
resolution N-body dark matter simulations to calculate the most likely energy
dependent boost factors linked to the cosmic ray propagation properties, for
anti-protons and positrons. Starting from the mass and space distributions of
sub-halos, the anti-proton and positron propagators are used to calculate the
mean value and the variance of the boost factor for the primary fluxes. We take
advantage of the statistical method introduced in Lavalle et al. (2007) and
cross-check the results with Monte Carlo computations. By spanning some extreme
configurations of sub-halo and propagation properties, we find that the average
contribution of the clumps is negligible compared to that of the smooth dark
matter component. Sub-halos do not lead to enhancement of the signals, unless
they are taken with some extreme (unexpected) properties. This result is
independent of the nature of the self-annihilating dark matter candidate
considered, and provides precise estimates of the theoretical and the
statistical uncertainties of the antimatter flux from dark matter
substructures. Spectral distortions can still be expected in antimatter flux
measurements, but scenarios invoking large and even mild clumpiness boost
factors are strongly disfavoured by our analysis.Comment: Final version, matching the published one. 32 pages, 12 figure
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