9,857 research outputs found
Analysis of X-ray spectra emitted from laser-produced plasmas of uranium
In this paper, we used the multiconfiguration Dirac-Fock method to generate
theoretical X-ray spectra for Co-, Ni-, Cu-, Zn-, Ga-, Ge-, As-, Se-, Br-, Kr-,
and Rb-like uranium ions. Using the distribution of these ions in a
laser-produced plasma, for different plasma temperatures, we generate
theoretical spectra, which are compared to experimental data
A Study of Two-Temperature Non-Equilibrium Ising Models: Critical Behavior and Universality
We study a class of 2D non-equilibrium Ising models based on competing
dynamics induced by contact with heat-baths at two different temperatures. We
make a comparative study of the non-equilibrium versions of Metropolis, heat
bath/Glauber and Swendsen-Wang dynamics and focus on their critical behavior in
order to understand their universality classes. We present strong evidence that
some of these dynamics have the same critical exponents and belong to the same
universality class as the equilibrium 2D Ising model. We show that the bond
version of the Swendsen-Wang update algorithm can be mapped into an equilibrium
model at an effective temperature.Comment: 12 pages of LaTeX plus 18 pages of postscript figures in a uuencoded
file (608k
Relativistic correlation correction to the binding energies of the ground configuration of Beryllium-like, Neon-like, Magnesium-like and Argon-like ions
Total electronic correlation correction to the binding energies of the
isoelectronic series of Beryllium, Neon, Magnesium and Argon, are calculated in
the framework of relativistic multiconfiguration Dirac-Fock method. Convergence
of the correlation energies is studied as the active set of orbitals is
increased. The Breit interaction is treated fully self-consistently. The final
results can be used in the accurately determination of atomic masses from
highly charged ions data obtained in Penning-trap experiments.Comment: version soumise 3/08/200
Quantum Fields with Noncommutative Target Spaces
Quantum field theories (QFT's) on noncommutative spacetimes are currently
under intensive study. Usually such theories have world sheet noncommutativity.
In the present work, instead, we study QFT's with commutative world sheet and
noncommutative target space. Such noncommutativity can be interpreted in terms
of twisted statistics and is related to earlier work of Oeckl [1], and others
[2,3,4,5,6,7,8]. The twisted spectra of their free Hamiltonians has been found
earlier by Carmona et al [9,10]. We review their derivation and then compute
the partition function of one such typical theory. It leads to a deformed black
body spectrum, which is analysed in detail. The difference between the usual
and the deformed black body spectrum appears in the region of high frequencies.
Therefore we expect that the deformed black body radiation may potentially be
used to compute a GZK cut-off which will depend on the noncommutative parameter
.Comment: 20 pages, 5 figures; Abstract changed. Changes and corrections in the
text. References adde
Fundamental cosmology from ANDES precision spectroscopy
Fundamental cosmology observations, such as the detection of the redshift
drift and tests of the universality of physical laws, are key science and
design drivers of the ArmazoNes high Dispersion Echelle Spectrograph (ANDES),
an Extremely Large Telescope instrument. While separate forecasts for each of
them have been reported, we have developed Fisher Matrix based forecast tools
combining both of these observables. We demonstrate the synergies between the
two ANDES datasets, quantifying the improvements in cosmology and fundamental
physics parameter constraints for two separate theoretical paradigms. We
publicly release this forecast code, which is one of the tools for the
optimisation of the ANDES observing strategy.Comment: 8 pages, 3 figures, 2 tables, MNRAS (in press
Smoking cessation and the incidence of pre-diabetes and type 2 diabetes: a cohort study.
AIMS: Smoking cessation has been suggested to increase the short-term risk of type 2 diabetes mellitus (T2DM). This study aimed at assessing the association between smoking cessation and incidence of T2DM and impaired fasting glucose (IFG).
METHODS: Data from participants in the CoLaus study, Switzerland, aged 35-75 at baseline and followed for 5.5years were used. Participants were classified as smokers, recent (≤5years), long-term (>5years) quitters, and non-smokers at baseline. Outcomes were IFG (fasting serum glucose (FSG) 5.6-6.99mmol/l) and T2DM (FSG ≥7.0mmol/l and/or treatment) at follow up.
RESULTS: 3,166 participants (63% women) had normal baseline FSG, of whom 26.7% were smokers, 6.5% recent quitters, and 23.5% long-term quitters. During follow-up 1,311 participants (41.4%) developed IFG (33.6% women, 54.7% men) and 47 (1.5%) developed T2DM (1.1% women, 2.1% men). Former smokers did not have statistically significant increased odds of IFG compared with smokers after adjustment for age, education, physical activity, hypercholesterolemia, hypertension and alcohol intake, with OR of 1.29 [95% confidence interval 0.94-1.76] for recent quitters and 1.03 [0.84-1.27] for long-term quitters. Former smokers did not have significant increased odds of T2DM compared with smokers with multivariable-adjusted OR of 1.53 [0.58-4.00] for recent quitters and 0.64 [0.27-1.48] for long-term quitters. Adjustment for body-mass index and waist circumference attenuated the association between recent quitting and IFG (OR 1.07 [0.78-1.48]) and T2DM (OR 1.28 [0.48-3.40].
CONCLUSION: In this middle-aged population, smoking cessation was not associated with an increased risk of IFG or T2DM
AN APPROACH TO OPTIMISE THE SELECTION OF LNG CARRIERS’ PROPULSION SYSTEM
Marine transport of natural gas, mostly in its liquid phase, is of growing importance in the global energy markets. The fleet of liquefied natural gas carriers is thereby increasing and being upgraded to enhance its performance. Since there is no well-defined procedure about how to perform the selection of the propulsion system considering the peculiarities of this kind of vessel, this work intend to fill this gap. In other words, the present article aims to propose an approach so that one can perform the optimised selection of liquefied natural gas carriers’ propulsion system mainly concerning financial aspects. Firstly, some fundamentals about liquefied natural gas and its transport are presented followed by reasons why the traditional steam turbine propulsion plant was abandoned and dual- fuel diesel engines have been applied instead. Then, a list of criteria is discussed and studies that inspired this work are summarised. A case study of a ship with cargo capacity of 174,000 m3 operating between Lake Charles and Tokyo Bay via Panama Canal is selected. Owing to this route and environmental rules, the ship has to travel at three different levels of service speed unlike ordinary ones, which usually keep a steady speed throughout voyage. Maximising the net present value of the project is the objective function that is intended to be achieved by optimising eleven variables regarding synthesis, design and operation of the propulsion system. Finally, it is suggested that this work may assist marine engineers and ship-owners to design and outline the operation of liquefied natural gas carriers
CRISP (crayfish and rice integrated system of production): 2. Modelling crayfish (Procambarus clarkii) population dynamics
An ecological sub-model of crayfish (Procambarus clarkii) population dynamics is presented for integration into the CRISP (crayfish and rice integrated system of production) series of models. The present structure is directed towards simulation of crayfish population responses under different human interventions, namely different capture rates. The crayfish population was subdivided into seven age classes of 80 days, each one constituting a state variable. The increase in weight for each 80-day period was considered dependent on the temperature, the oxygen level and the water level. Mortality was assumed to be dependent on the dry weight of the crayfish and regulated by the total crayfish biomass. Food, water and oxygen content of the water were considered to be non limiting. Total crayfish biomass and total wet weight of crayfish captures were very sensitive to both the temperature for maximum growth and the mortality rates. Our most optimistic simulation, with a 50% decrease in the mortality rates, resulted in a fourfold increase in captures, from 230 to 917 kg ha-1 per year. Without capture, a value of 121 kg ha-1 was simulated for the average crayfish biomass, which is close to the 124 kg ha-1 obtained with crayfish capture. Our simulated average crayfish biomass was approximately 120 kg ha-1 in a natural situation, which lies inside the reported ranges from areas at approximately the same latitude.http://www.sciencedirect.com/science/article/B6VBS-3XM2SN8-2/1/c3c8d93a43ea0ffd5fc0055b9347934
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