25,503 research outputs found
Comparison of techniques to reconstruct VHE gamma-ray showers from multiple stereoscopic Cherenkov images
For air showers observed simultaneously by more than two imaging atmospheric
Cherenkov telescopes, the shower geometry is overconstrained by the images and
image information should be combined taking into account the quality of the
images. Different algorithms are discussed and tested experimentally using data
obtained from observations of Mkn 501 with the HEGRA IACT system. Most of these
algorithms provide an estimate of the accuracy of the reconstruction of shower
geometry on an event-by-event basis, allowing, e.g., to select higher-quality
subsamples for precision measurements.Comment: 14 Pages, 6 figures, Late
Giant nonlinear response of superconducting single crystal niobium in a sweeping magnetic field
Giant enhancement of the nonlinear response of a single crystal of Nb placed
in a sweeping magnetic field has been experimentally observed. The rectified
signal from Nb ( K) has been measured by means of an inductive method
as a function of temperature, dc field, dc field sweep rate, and the amplitude
of ac field. The Nb sample was excited by an amplitude modulated ac field.
Under a stationary regime, the rectified signal appears only for magnetic
fields () in the range . However, when the dc field
was swept slowly, the rectified signal appears at . This experiment
shows that the amplitude of the rectified signal is two orders of magnitude
larger than the amplitude of the signal seen under stationary field conditions.
Moreover, the amplitude of the rectified signal is a power function of the
sweep rate, with the power exponent close to 1.Comment: 3 pages, 3 figures, presented to EUCAS 200
Unintegrated gluon distribution and soft pp collisions at LHC
We found the parameterization of the unintegrated gluon distribution from the
best description of the LHC data on the inclusive spectra of hadrons produced
in collisions at the mid-rapidity region and small transverse momenta. It
is different from the one obtained within perturbative QCD only at low
intrinsic transverse momenta . The application of this distribution to
analysis of the DIS allows us to get the results which do not contradict
the H1 and ZEUS data on the structure functions at low . So, the connection
between the soft processes at LHC and low- physics at HERA is found.Comment: 8 pages, 4 figures. Contributed to 3rd Workshop on Multi-Parton
Interactions at the LHC (MPI11), Hamburg, 21-25 November 201
Highest weight modules over quantum queer Lie superalgebra U_q(q(n))
In this paper, we investigate the structure of highest weight modules over
the quantum queer superalgebra . The key ingredients are the
triangular decomposition of and the classification of finite
dimensional irreducible modules over quantum Clifford superalgebras. The main
results we prove are the classical limit theorem and the complete reducibility
theorem for -modules in the category .Comment: Definition 1.5 and Definition 6.1 are changed, and a remark is added
in the new versio
Reconceptualising Personas Across Cultures: Archetypes, Stereotypes & Collective Personas in Pastoral Namibia
The paucity of projects where persona is the research foci and a lack of consensus on this artefact keep many reticent about its purpose and value. Besides crafting personas is expected to differ across cultures, which contrasts the advancements in Western theory with studies and progress in other sites. We postulate User-Created Personas reveal specific characteristics of situated contexts by allowing laypeople to design persona artefacts in their own terms. Hence analysing four persona sessions with an ethnic group in pastoral Namibia –ovaHerero– brought up a set of fundamental questions around the persona artefact regarding stereotypes, archetypes, and collective persona representations: (1) to what extent user depictions are stereotypical or archetypal? If stereotypes prime (2) to what degree are current personas a useful method to represent end-users in technology design? And, (3) how can we ultimately read accounts not conforming to mainstream individual persona descriptions but to collectives
Nonequilibrium 1/f Noise in Low-doped Manganite Single Crystals
1/f noise in current biased La0.82Ca0.18MnO3 crystals has been investigated.
The temperature dependence of the noise follows the resistivity changes with
temperature suggesting that resistivity fluctuations constitute a fixed
fraction of the total resistivity, independently of the dissipation mechanism
and magnetic state of the system. The noise scales as a square of the current
as expected for equilibrium resistivity fluctuations. However, at 77 K at bias
exceeding some threshold, the noise intensity starts to decrease with
increasing bias. The appearance of nonequilibrium noise is interpreted in terms
of bias dependent multi-step indirect tunneling.Comment: 4pages, 3figures,APL accepte
Bias Dependent 1/f Conductivity Fluctuations in Low-Doped LaCaMnO Manganite Single Crystals
Low frequency noise in current biased LaCaMnO single
crystals has been investigated in a wide temperature range from 79 K to 290 K.
Despite pronounced changes in magnetic properties and dissipation mechanisms of
the sample with changing temperature, the noise spectra were found to be always
of the 1/f type and their intensity (except the lowest temperature studied)
scaled as a square of the bias. At liquid nitrogen temperatures and under bias
exceeding some threshold value, the behavior of the noise deviates from the
quasi-equilibrium modulation noise and starts to depend in a non monotonic way
on bias. It has been verified that the observed noise obeys Dutta and Horn
model of 1/f noise in solids. The appearance of nonequilibrium 1/f noise and
its dependence on bias have been associated with changes in the distribution of
activation energies in the underlying energy landscape. These changes have been
correlated with bias induced changes in the intrinsic tunneling mechanism
dominating dissipation in LaCaMnO at low temperatures.Comment: Accepted for publication in the Journal of Applied Physic
Staggered Currents in the Vortex Core
We study the electronic structure of the vortex core in the cuprates using
the U(1) slave-boson mean-field wavefunctions and their Gutzwiller projection.
We conclude that there exists local orbital antiferromagnetic order in the core
near optimal doping. We compare the results with that of BCS theory and analyze
the spatial dependence of the local tunneling density of states.Comment: 4 pages, 3 figure
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