483 research outputs found
Analytical two-center integrals over Slater geminal functions
We present analytical formulas for the calculation of the two-center
two-electron integrals in the basis of Slater geminals and products of Slater
orbitals. Our derivation starts with establishing a inhomogeneous fourth-order
ordinary differential equation that is obeyed by the master integral, the
simplest integral with inverse powers of all interparticle distances. To solve
this equation it was necessary to introduce a new family of special functions
which are defined through their series expansions around regular singular
points of the differential equation. To increase the power of the interparticle
distances under the sign of the integral we developed a family of open-ended
recursion relations. A handful of special cases of the integrals is also
analysed with some remarks on simplifications that occur. Additionally, we
present some numerical examples of the master integral that validate the
usefulness and correctness of the key equations derived in this paper. In
particular, we compare our results with the calculations based on the series
expansion of the exp(-\gamma r12) term in the master integral.Comment: 28 pages, 0 figures, 7 table
Approximation for Batching via Priorities
We consider here the one-machine serial batching problem under weighted average completion. This problem is known to be -hard and no good approximation algorithms are known. Batching has wide application in manufacturing, decision management, and scheduling in information technology.
We give an approximation algorithm with approximation ratio of ; the algorithm is a priority algorithm, which batches jobs in decreasing order of priority. We also give a lower bound of on the approximation ratio of any priority algorithm and conjecture that there is a priority algorithm which matches this bound. Adaptive algorithm experiments are used to support the conjecture. An easier problem is the list version of the problem where the order of the jobs is given. We give a new linear time algorithm for the list batching problem
The influence of continuous casting and extrusion processes on the properties and structure of CuNi2Si alloy and the morphology of the Ni-Si phase precipitates
CuNiSi alloys are widely used in various mechanical and electrical applications. These group of materials, due to the phenomena of precipitation hardening, are able to obtain high mechanical properties with also relatively high electrical properties. In the article authors compare two different types of products, made from the CW111C alloy i.e. rods which were continuously cast on the horizontal laboratory casting set-up (low degree of structure refinement) and rods commercially extruded with high degree of structure refinement. The presented results of experimental work characterize the tested materials in terms of their chemical composition, mechanical and electrical properties depending on the manufacturing process, as well as reveal their structures and the effect of heat treatment on the morphology of the Ni-Si precipitates
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The Effect of Tricaine on Use of the Fluorescein Test for Detecting Skin and Corneal Ulcers in Fish
Fluorescein has been used for rapid and sensitive detection of fish skin and corneal ulceration. Effective use of the fluorescein test requires knowledge of conditions that might cause misleading interpretations or otherwise interfere with test reliability. Examination of fish health and the clinical workup often require tricaine as one of the most commonly used anesthetics. However, tricaine may interfere with correct interpretation of the fluorescein test and might also cause significant fish injury. The effects of tricaine exposure sequence on the fidelity of the fluorescein test was studied in Pacific halibut Hippoglossus stenolepis, walleye pollock Theragra chalcogramma, and northern rock soles Lepidopsetta polyxystra by examining the fluorescence of experimentally induced epidermal wounding. Tricaine can quench fluorescence that is emitted by fluorescein retained in skin ulcers, causing a false-negative reaction. Thus, for the fluorescein test to work properly, it is important to avoid the exposure of fluorescein-treated and rinsed ulcers to tricaine. The effects of exposure to buffered versus unbuffered tricaine on epidermal and corneal integrity were studied in Nile tilapia Oreochromis niloticus and channel catfish Ictalurus punctatus subjected to the fluorescein test and histological examination. Fluorescein could detect not only ulcers but also areas with only a partial loss of epithelium (i.e., erosion). The use of unbuffered tricaine to anesthetize these fish caused serious epidermal and corneal damage. If fish are euthanized with unbuffered tricaine for clinical workup, this severe epidermal or corneal damage could be misinterpreted as an antemortem lesion, leading to misdiagnosis. Even in water with alkalinity exceeding 50 mg/L as CaCO3, it would seem prudent to always buffer tricaine with sodium bicarbonate to prevent a pH change that might lead to iatrogenic effects from unbuffered tricaine. Thus, current general recommendations suggesting that tricaine does not need to be buffered in waters with alkalinity greater than 50 mg/L might need to be modified.Keywords: fluorescein, ulceration, alkalinityKeywords: fluorescein, ulceration, alkalinit
Omalizumab may decrease IgE synthesis by targeting membrane IgE+ human B cells
Omalizumab, is a humanized anti-IgE monoclonal antibody used to treat allergic asthma. Decreased serum IgE levels, lower eosinophil and B cell counts have been noted as a result of treatment. In vitro studies and animal models support the hypothesis that omalizumab inhibits IgE synthesis by B cells and causes elimination of IgE-expressing cells either by induction of apoptosis or induction of anergy or tolerance. METHODS: We examined the influence of omalizumab on human tonsillar B cell survival and on the genes involved in IgE synthesis. Tonsillar B cells were stimulated with IL-4 plus anti-CD40 antibody to induce class switch recombination to IgE production in the presence or absence of omalizumab. Cell viability was assessed and RNA extracted to examine specific genes involved in IgE synthesis. CONCLUSIONS: We found that omalizumab reduced viable cell numbers but this was not through induction of apoptosis. IL-4R and germline Cϵ mRNA levels were decreased as well as the number of membrane IgE+ cells in B cells treated with omalizumab. These data suggest that omalizumab may decrease IgE synthesis by human B cells by specifically targeting membrane IgE-bearing B cells and inducing a state of anergy
Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations
A benchmark ab initio and density functional (DFT) study has been carried out
on the electron affinities of the first- and second-row atoms. The ab initio
study involves basis sets of and quality, extrapolations to
the 1-particle basis set limit, and a combination of the CCSD(T), CCSDT, and
full CI electron correlation methods. Scalar relativistic and spin-orbit
coupling effects were taken into account. On average, the best ab initio
results agree to better than 0.001 eV with the most recent experimental
results. Correcting for imperfections in the CCSD(T) method improves the mean
absolute error by an order of magnitude, while for accurate results on the
second-row atoms inclusion of relativistic corrections is essential. The latter
are significantly overestimated at the SCF level; for accurate spin-orbit
splitting constants of second-row atoms inclusion of (2s,2p) correlation is
essential. In the DFT calculations it is found that results for the 1st-row
atoms are very sensitive to the exchange functional, while those for second-row
atoms are rather more sensitive to the correlation functional. While the LYP
correlation functional works best for first-row atoms, its PW91 counterpart
appears to be preferable for second-row atoms. Among ``pure DFT'' (nonhybrid)
functionals, G96PW91 (Gill 1996 exchange combined with Perdew-Wang 1991
correlation) puts in the best overall performance. The best results overall are
obtained with the 1-parameter hybrid modified Perdew-Wang (mPW1) exchange
functionals of Adamo and Barone [J. Chem. Phys. {\bf 108}, 664 (1998)], with
mPW1LYP yielding the best results for first-row, and mPW1PW91 for second-row
atoms. Indications exist that a hybrid of the type mPW1LYP +
mPW1PW91 yields better results than either of the constituent functionals.Comment: Phys. Rev. A, in press (revised version, review of issues concerning
DFT and electron affinities added
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