14,828 research outputs found
Statistics of temperature fluctuations in an electron system out of equilibrium
We study the statistics of the fluctuating electron temperature in a metallic
island coupled to reservoirs via resistive contacts and driven out of
equilibrium by either a temperature or voltage difference between the
reservoirs. The fluctuations of temperature are well-defined provided that the
energy relaxation rate inside the island exceeds the rate of energy exchange
with the reservoirs. We quantify these fluctuations in the regime beyond the
Gaussian approximation and elucidate their dependence on the nature of the
electronic contacts.Comment: 4 pages, 3 figure
Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
We present a detailed temperature dependent Raman light scattering study of
optical phonons in Ba{1-x}K{x}Fe{2}As{2} (x ~ 0.28, superconducting Tc ~ 29 K),
Sr{1-x}K{x}Fe{2}As{2} (x ~ 0.15, Tc ~ 29 K) and non-superconducting
BaFe{2}As{2} single crystals. In all samples we observe a strong continuous
narrowing of the Raman-active Fe and As vibrations upon cooling below the
spin-density-wave transition Ts. We attribute this effect to the opening of the
spin-density-wave gap. The electron-phonon linewidths inferred from these data
greatly exceed the predictions of ab-initio density functional calculations
without spin polarization, which may imply that local magnetic moments survive
well above Ts. A first-order structural transition accompanying the
spin-density-wave transition induces discontinuous jumps in the phonon
frequencies. These anomalies are increasingly suppressed for higher potassium
concentrations. We also observe subtle phonon anomalies at the superconducting
transition temperature Tc, with a behavior qualitatively similar to that in the
cuprate superconductors.Comment: 5 pages, 6 figures, accepted versio
The Offline Software Framework of the Pierre Auger Observatory
The Pierre Auger Observatory is designed to unveil the nature and the origins
of the highest energy cosmic rays. The large and geographically dispersed
collaboration of physicists and the wide-ranging collection of simulation and
reconstruction tasks pose some special challenges for the offline analysis
software. We have designed and implemented a general purpose framework which
allows collaborators to contribute algorithms and sequencing instructions to
build up the variety of applications they require. The framework includes
machinery to manage these user codes, to organize the abundance of
user-contributed configuration files, to facilitate multi-format file handling,
and to provide access to event and time-dependent detector information which
can reside in various data sources. A number of utilities are also provided,
including a novel geometry package which allows manipulation of abstract
geometrical objects independent of coordinate system choice. The framework is
implemented in C++, and takes advantage of object oriented design and common
open source tools, while keeping the user side simple enough for C++ novices to
learn in a reasonable time. The distribution system incorporates unit and
acceptance testing in order to support rapid development of both the core
framework and contributed user code.Comment: 4 pages, 2 figures, presented at IEEE NSS/MIC, 23-29 October 2005,
Puerto Ric
Open Space – a collaborative process for facilitating Tourism IT partnerships
The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: “how do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?” The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships
Spectroscopy of electron-induced fluorescence in organic liquid scintillators
Emission spectra of several organic liquid-scintillator mixtures which are
relevant for the proposed LENA detector have been measured by exciting the
medium with electrons of ~10keV. The results are compared with spectra
resulting from ultraviolet light excitation. Good agreement between spectra
measured by both methods has been found.Comment: 6 pages, 7 figure
Fluorescence decay-time constants in organic liquid scintillators
The fluorescence decay-time constants have been measured for several
scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear
alkylbenzene (LAB) solvents. The resulting values are of relevance for the
physics performance of the proposed large-volume liquid scintillator detector
LENA (Low Energy Neutrino Astronomy). In particular, the impact of the measured
values to the search for proton decay via p -> K+ antineutrino is evaluated in
this work.Comment: 7 pages, 5 figure
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