5,692 research outputs found
Pregnancy Complicated by Ovarian and Fibroid Tumors. Remarks Upon Indications for Treatment.
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One-Electron Ionization of Multielectron Systems in Strong Nonresonant Laser Fields
We present a novel approach to calculating strong field ionization dynamics
of multielectron molecular targets. Adopting a multielectron wavefunction
ansatz based on field-free ab initio neutral and ionic multielectron states, a
set of coupled time-dependent single-particle Schroedinger equations describing
the neutral amplitude and continuum electron are constructed. These equations,
amenable to direct numerical solution or further analytical treatment, allow
one to study multielectron effects during strong field ionization, recollision,
and high harmonic generation. We apply the method to strong field ionization of
CO_2, and suggest the importance of intermediate core excitation to explain
previous failure of analytical models to reproduce experimental ionization
yields for this molecule.Comment: 25 pages, 6 figure
Mechanisms of two-color laser-induced field-free molecular orientation
Two mechanisms of two-color (\omega + 2\omega) laser-induced field-free
molecular orientation, based on the hyperpolarizability and ionization
depletion, are explored and compared. The CO molecule is used as a
computational example. While the hyperpolarizability mechanism generates small
amounts of orientation at intensities below the ionization threshold,
ionization depletion quickly becomes the dominant mechanism as soon as ionizing
intensities are reached. Only the ionization mechanism leads to substantial
orientation (e.g. on the order of || > 0.1). For intensities typical
of laser-induced molecular alignment and orientation experiments, the two
mechanism lead to robust, characteristic timings of the field-free orientation
wave-packet revivals relative to the the alignment revivals and the revival
time. The revival timings can be used to detect the active orientation
mechanism experimentally
Beginning of the End of Cost Competitiveness in CEE Countries - Analysis of Dependence between Labor Costs and Internationalization of the Region
In order to exemplify the above econometric model I carried out empirical analysis of the companies listed on the Warsaw Stock Exchange, identifying the companies for which efficiency-seeking is the main internationalization motive. The analysis of internationalization of 26 companies during the years 1990-2010 clearly shows that a significant part of investments is located outside the territory of Poland, in the countries with lower labor costs. This fact confirms that CEE countries will gradually become less and less attractive in terms of costs not only for MNEs from developed countries but also for the companies originating from transition economies.Głównym celem artykułu jest weryfikacja, czy niski poziom kosztów pracy w Europie Środkowej i Wschodniej będący do tej pory jednym z czynników wpływających na konkurencyjność tego regionu pozostanie nim w dłuższej perspektywie czasowej. W pracy na podstawie próby wszystkich państw UE zbadano zależność pomiędzy poziomem internacjonalizacji (stan odpływu BIZ per capita) a kosztami pracy w sektorze przedsiębiorstw i GNP per capita. Analiza regresji potwierdziła istnienie zależności pomiędzy wyżej wymienionymi czynnikami. Oznacza to, że stopniowy wzrost kosztów pracy w państwach Europy Środkowej i Wschodniej prowadził będzie do stopniowego odpływu BIZ z tego regionu do państw bardziej konkurencyjnych kosztowo. W celu egzemplifikacji powyższych zależności w pracy dodatkowo przedstawiono analizę inwestycji zagranicznych polskich spółek notowanych na GPW, z których to 26 dokonało inwwestycji zagranicznych o wyraźnych motywach związanych z obniżeniem kosztów produkcji. Fakt ten potwierdza powolny spadek konkurencyjności kosztowej polskiej gospodarki, tym samym zmusza do poszukiwania nowych rozwiązań instytucjonalnych mogących utrzymać konkurencyjność polskiej gospodarki w długim okresie
The heats of formation of the haloacetylenes XCCY [X, Y = H, F, Cl]: basis set limit ab initio results and thermochemical analysis
The heats of formation of haloacetylenes are evaluated using the recent W1
and W2 ab initio computational thermochemistry methods. These calculations
involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh
quality, extrapolations to the one-particle basis set limit, and contributions
of inner-shell correlation, scalar relativistic effects, and (where relevant)
first-order spin-orbit coupling. The heats of formation determined using W2
theory are: \hof(HCCH) = 54.48 kcal/mol, \hof(HCCF) = 25.15 kcal/mol,
\hof(FCCF) = 1.38 kcal/mol, \hof(HCCCl) = 54.83 kcal/mol, \hof(ClCCCl) = 56.21
kcal/mol, and \hof(FCCCl) = 28.47 kcal/mol. Enthalpies of hydrogenation and
destabilization energies relative to acetylene were obtained at the W1 level of
theory. So doing we find the following destabilization order for acetylenes:
FCCF ClCCF HCCF ClCCCl HCCCl HCCH. By a combination of W1
theory and isodesmic reactions, we show that the generally accepted heat of
formation of 1,2-dichloroethane should be revised to -31.80.6 kcal/mol, in
excellent agreement with a very recent critically evaluated review. The
performance of compound thermochemistry schemes such as G2, G3, G3X and CBS-QB3
theories has been analyzed.Comment: Mol. Phys., in press (E. R. Davidson issue
A variational approach for the Quantum Inverse Scattering Method
We introduce a variational approach for the Quantum Inverse Scattering Method
to exactly solve a class of Hamiltonians via Bethe ansatz methods. We undertake
this in a manner which does not rely on any prior knowledge of integrability
through the existence of a set of conserved operators. The procedure is
conducted in the framework of Hamiltonians describing the crossover between the
low-temperature phenomena of superconductivity, in the
Bardeen-Cooper-Schrieffer (BCS) theory, and Bose-Einstein condensation (BEC).
The Hamiltonians considered describe systems with interacting Cooper pairs and
a bosonic degree of freedom. We obtain general exact solvability requirements
which include seven subcases which have previously appeared in the literature.Comment: 18 pages, no eps figure
CT Perfusion for Detection of Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis
BACKGROUND AND PURPOSE: Delayed cerebral ischemia is a significant cause of morbidity and mortality after aneurysmal SAH, leading to poor outcomes. The purpose of this study was to evaluate the usefulness of CTP in determining delayed cerebral ischemia in patients with aneurysmal SAH. MATERIALS AND METHODS: We conducted a systematic review evaluating studies that assessed CTP in patients with aneurysmal SAH for determining delayed cerebral ischemia. Studies using any of the following definitions of delayed cerebral ischemia were included in the systematic review: 1) new onset of clinical deterioration, 2) cerebral infarction identified on follow-up CT or MR imaging, and 3) functional disability. A random-effects meta-analysis was performed assessing the strength of association between a positive CTP result and delayed cerebral ischemia. RESULTS: The systematic review identified 218 studies that met our screening criteria, of which 6 cohort studies met the inclusion criteria. These studies encompassed a total of 345 patients, with 155 (45%) of 345 patients classified as having delayed cerebral ischemia and 190 (55%) of 345 patients as not having delayed cerebral ischemia. Admission disease severity was comparable across all groups. Four cohort studies reported CTP test characteristics amenable to the meta-analysis. The weighted averages and ranges of the pooled sensitivity and specificity of CTP in the determination of delayed cerebral ischemia were 0.84 (0.7-0.95) and 0.77 (0.66-0.82), respectively. The pooled odds ratio of 23.14 (95% CI, 5.87-91.19) indicates that patients with aneurysmal SAH with positive CTP test results were approximately 23 times more likely to experience delayed cerebral ischemia compared with patients with negative CTP test results. CONCLUSIONS: Perfusion deficits on CTP are a significant finding in determining delayed cerebral ischemia in aneurysmal SAH. This may be helpful in identifying patients with delayed cerebral ischemia before development of infarction and neurologic deficits
University of Maine Cooperative Extension Service Cumberland County Annual Report, December 1, 1962-November 30, 1963
Controlling the accuracy of the density matrix renormalization group method: The Dynamical Block State Selection approach
We have applied the momentum space version of the Density Matrix
Renormalization Group method (-DMRG) in quantum chemistry in order to study
the accuracy of the algorithm in the new context. We have shown numerically
that it is possible to determine the desired accuracy of the method in advance
of the calculations by dynamically controlling the truncation error and the
number of block states using a novel protocol which we dubbed Dynamical Block
State Selection (DBSS). The relationship between the real error and truncation
error has been studied as a function of the number of orbitals and the fraction
of filled orbitals. We have calculated the ground state of the molecules
CH, HO, and F as well as the first excited state of CH. Our
largest calculations were carried out with 57 orbitals, the largest number of
block states was 1500--2000, and the largest dimensions of the Hilbert space of
the superblock configuration was 800.000--1.200.000.Comment: 12 page
Electron attachment to valence-excited CO
The possibility of electron attachment to the valence state of CO
is examined using an {\it ab initio} bound-state multireference configuration
interaction approach. The resulting resonance has symmetry;
the higher vibrational levels of this resonance state coincide with, or are
nearly coincident with, levels of the parent state. Collisional
relaxation to the lowest vibrational levels in hot plasma situations might
yield the possibility of a long-lived CO state.Comment: Revtex file + postscript file for one figur
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