533 research outputs found
Integrated stress response of Escherichia coli to methylglyoxal : transcriptional readthrough from the nemRA operon enhances protection through increased expression of glyoxalase I
© 2013 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.Peer reviewedPublisher PD
Cyber Threats and NATO 2030: Horizon Scanning and Analysis
The book includes 13 chapters that look ahead to how NATO can best address the cyber threats, as well as opportunities and challenges from emerging and disruptive technologies in the cyber domain over the next decade.
The present volume addresses these conceptual and practical requirements and contributes constructively to the NATO 2030 discussions. The book is arranged in five short parts...All the chapters in this book have undergone double-blind peer review by at least two external experts.https://scholarworks.wm.edu/asbook/1038/thumbnail.jp
X-Ray and Infrared Enhancement of Anomalous X-ray Pulsar 1E 2259+58
The long term (~1.5 years) X-ray enhancement and the accompanying infrared
enhancement light curves of the anomalous X-ray pulsar 1E 2259+58 following the
major bursting epoch can be accounted for by the relaxation of a fall back disk
that has been pushed back by a gamma-ray flare. The required burst energy
estimated from the results of our model fits is low enough for such a burst to
have remained below the detection limits. We find that an irradiated disk model
with a low irradiation efficiency is in good agreement with both X-ray and
infrared data. Non-irradiated disk models also give a good fit to the X-ray
light curve, but are not consistent with the infrared data for the first week
of the enhancement.Comment: 17 pages, 3 figures, accepted for publication in Ap
Metric fluctuations and decoherence
Recently a model of metric fluctuations has been proposed which yields an
effective Schr\"odinger equation for a quantum particle with a modified
inertial mass, leading to a violation of the weak equivalence principle. The
renormalization of the inertial mass tensor results from a local space average
over the fluctuations of the metric over a fixed background metric. Here, we
demonstrate that the metric fluctuations of this model lead to a further
physical effect, namely to an effective decoherence of the quantum particle. We
derive a quantum master equation for the particle's density matrix, discuss in
detail its dissipation and decoherence properties, and estimate the
corresponding decoherence time scales. By contrast to other models discussed in
the literature, in the present approach the metric fluctuations give rise to a
decay of the coherences in the energy representation, i. e., to a localization
in energy space.Comment: 7 page
Space--time fluctuations and the spreading of wavepackets
Using a density matrix description in space we study the evolution of
wavepackets in a fluctuating space-time background. We assume that space-time
fluctuations manifest as classical fluctuations of the metric. From the
non-relativistic limit of a non-minimally coupled Klein-Gordon equation we
derive a Schr\"odinger equation with an additive gaussian random potential.
This is transformed into an effective master equation for the density matrix.
The solutions of this master equation allow to study the dynamics of
wavepackets in a fluctuating space-time, depending on the fluctuation scenario.
We show how different scenarios alter the diffusion properties of wavepackets.Comment: 11 page
Long-term X-ray changes in the emission from the anomalous X-ray pulsar 4U 0142+61
We present results obtained from X-ray observations of the anomalous X-ray
pulsar (AXP) 4U 0142+61 taken between 2000-2007 using XMM-Newton, Chandra and
Swift. In observations taken before 2006, the pulse profile is observed to
become more sinusoidal and the pulsed fraction increased with time. These
results confirm those derived using the Rossi X-ray Timing Explorer and expand
the observed evolution to energies below 2 keV. The XMM-Newton total flux in
the 0.5-10 keV band is observed to be nearly constant in observations taken
before 2006, while an increase of ~10% is seen afterwards and coincides with
the burst activity detected from the source in 2006-2007. After these bursts,
the evolution towards more sinusoidal pulse profiles ceased while the pulsed
fraction showed a further increase. No evidence for large-scale, long-term
changes in the emission as a result of the bursts is seen. The data also
suggest a correlation between the flux and hardness of the spectrum, with
brighter observations on average having a harder spectrum. As pointed out by
other authors, we find that the standard blackbody plus power-law model does
not provide the best spectral fit to the emission from 4U 0142+61. We also
report on observations taken with the Gemini telescope after two bursts. These
observations show source magnitudes consistent with previous measurements. Our
results demonstrate the wide range of X-ray variability characteristics seen in
AXPs and we discuss them in light of current emission models for these sources.Comment: 10 pages, 9 figures, in emulateapj style. Submitted to Ap
Non-LTE modeling of supernova-fallback disks
We present a first detailed spectrum synthesis calculation of a
supernova-fallback disk composed of iron. We assume a geometrically thin disk
with a radial structure described by the classical alpha-disk model. The disk
is represented by concentric rings radiating as plane-parallel slabs. The
vertical structure and emission spectrum of each ring is computed in a fully
self-consistent manner by solving the structure equations simultaneously with
the radiation transfer equations under non-LTE conditions. We describe the
properties of a specific disk model and discuss various effects on the emergent
UV/optical spectrum.
We find that strong iron-line blanketing causes broad absorption features
over the whole spectral range. Limb darkening changes the spectral distribution
up to a factor of four depending on the inclination angle. Consequently, such
differences also occur between a blackbody spectrum and our model. The overall
spectral shape is independent of the exact chemical composition as long as iron
is the dominant species. A pure iron composition cannot be distinguished from
silicon-burning ash. Non-LTE effects are small and restricted to few spectral
features.Comment: ApSS, accepted, Proceedings of Isolated Neutron Stars: from the
Interior to the Surface, April 24-28, 2006, London, U
Users, Economics, Technology: Unavoidable Interdynamics
This paper briefly presents some conclusions of a brainstorming session on the way technology is evolving in ICT. Technology advances have overcome society ability to answer, both in economic and in human aspects. The current design paradigms, of agnostic technology development, need to be reconsidered, and the user needs to be repositioned at the center of future developments
Earnings announcement return extrapolation
We propose that extrapolative beliefs about earnings announcement (EA) returns may contribute to our understanding of EA return patterns. We construct a theoretically-motivated measure of extrapolative investors’ expectations based on a stock’s recent history of EA returns. We then show that this measure explains cross-sectional variation in stock returns and investor behavior around EAs. Stocks expected to have high EA returns according to our measure experience predictable increases in prices before EAs and predictable decreases afterwards. These patterns are economically significant: investors that buy (sell) a portfolio that is long firms with high recent EA returns and short firms with low recent EA returns in the pre-EA (post-EA) period earn daily five-factor abnormal returns of 16.1 bps (18.3 bps). Using individual investor trades data and a measure of institutional trading, we find that individual and institutional investors are more likely to purchase stocks with high recent EA returns, consistent with at least a subset of investors forming extrapolative beliefs about EA returns
Assessing the influence of oil and grease and salt content on fish canning wastewater biodegradation through respirometric tests
Fish canning industry wastewaters have high organic matter, oil and grease and salt (NaCl) content, which make difficult a proper treatment before discharge. In this work, their treatment was evaluated via activated sludge aerobic biological process through respirometric tests. Inhibition was found to be significant for NaCl concentr ations higher than 17.5 g/L. On the other hand, the oil and grease content affects the wastewater biodegradability in the same way that the organic matter content expressed as chemical oxygen demand: the lower oil and grease and organic matter concentrations, the lower the percentage of wastewater biodegradability. As a final conclusion, the aerobic biological treatment process by activated sludge proved to be appropriate to treat fish canning industrial wastewaters, leading to high organic matter degradation rates (average value of 4900 mg O2 /g COD .d). Additionally, the experimental results achieved with the respirometric tests may be useful for the design of activated sludge plants to treat this type of wastewaters.This work was co-financed by FCT/MEC and FEDER under Programe
PT2020 (Project UID/EQU/50020/2013), by QREN, ON2 and
FEDER (Project NORTE-07-0162-FEDER-000050) and by ValorPeixe
e Valorizaç~ao de Subprodutos e Aguas Residuais da Indústria de
Conservas de Peixe, project in co-promotion I&DT QREN, nº 13634,
financed by FEDER through POFC e Programa Operacional Factores
de Competitividade for which the authors are thankful. The authors
also wish to thank the cannery in study for wastewater samples.
Raquel O. Cristóvão thanks FCT for the Post-doc Scholarship (SFRH/
BPD/81564/2011).info:eu-repo/semantics/publishedVersio
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