1,878 research outputs found
Relativistic dynamical polarizability of hydrogen-like atoms
Using the operator representation of the Dirac Coulomb Green function the
analytical method in perturbation theory is employed in obtaining solutions of
the Dirac equation for a hydrogen-like atom in a time-dependent electric field.
The relativistic dynamical polarizability of hydrogen-like atoms is calculated
and analysed.Comment: 15 pages, 3 figures (not included, but hard copies are available upon
request
Quantum tops as examples of commuting differential operators
We study the quantum analogs of tops on Lie algebras and
represented by differential operators.Comment: 24 p
Relativistic effects in proton-induced deuteron break-up at intermediate energies with forward emission of a fast proton pair
Recent data on the reaction pD -> (pp) n with a fast forward pp pair with
very small excitation energy is analyzed within a covariant approach based on
the Bethe-Salpeter formalism. It is demonstrated that the minimum
non-relativistic amplitude is completely masked by relativistic effects, such
as Lorentz boost and the negative-energy P components in the 1S_0
Bethe-Salpeter amplitude of the pp pair
PLATELETÂ FUNCTIONÂ TESTÂ FORÂ THEÂ ASSESSMENTÂ OFÂ THROMBOSISÂ ANDÂ BLEEDINGÂ RISKÂ INÂ CHDÂ PATIENTSÂ TAKINGÂ ANTIPLATELETÂ MEDICATIONS
The review concerns on the testing of platelet function in Chd patients receiving antiplatelet medications. the results are shown of the main large-scale studies demonstrating the relationship of the residual platelet activity level with the development of ishemic and hemorrhagic complications. the analysis is done of the causes of insufficient suppressing of platelet function as the response to clopidogrel. the guidelines of major international expert organizations are discussed on problem of sensitivity to aggregants testing and possible modification of antiplatelet treatment
Mechanisms of arsenic clustering in silicon
A model of arsenic clustering in silicon is proposed and analyzed. The main
feature of the proposed model is the assumption that negatively charged arsenic
complexes play a dominant role in the clustering process. To confirm this
assumption, electron density and concentration of impurity atoms incorporated
into the clusters are calculated as functions of the total arsenic
concentration. A number of the negatively charged clusters incorporating a
point defect and one or more arsenic atoms are investigated. It is shown that
for the doubly negatively charged clusters or for clusters incorporating more
than one arsenic atom the electron density reaches a maximum value and then
monotonically and slowly decreases as total arsenic concentration increases. In
the case of doubly negatively charged cluster incorporating two arsenic atoms,
the calculated electron density agrees well with the experimental data.
Agreement with the experiment confirms the conclusion that two arsenic atoms
participate in the cluster formation. Among all present models, the proposed
model of clustering by formation of doubly negatively charged cluster
incorporating two arsenic atoms gives the best fit to the experimental data and
can be used in simulation of high concentration arsenic diffusion.Comment: 13 pages, 4 figures. Revised and shortened version of the paper has
been published in Phys. Rev. B, Vol.74 (3), art. no. 035205 (2006
CCD thermoreflectance thermography system : methodology and experimental validation
This work introduces a thermoreflectance-based system designed to measure the surface temperature field of activated microelectronic devices at submicron spatial resolution with either a laser or a CCD camera. The article describes the system, outlines the measurement methodology, and presents validation results. The thermo-reflectance thermography (TRTG) system is capable of acquiring device surface temperature fields at up to 512\u81 512 points with 0.2 ÆĂm resolution. The setup and measurement methodology are presented, along with details of the calibration process required to convert changes in measured surface reflectivity to absolute temperatures. To demonstrate the system\u81fs capabilities, standard gold micro-resistors are activated and their surface temperature fields are measured. The results of the CCD camera and our existing laser-based measurement approaches are compared and found to be in very good agreement. Finally, the system is validated by comparing the temperatures obtained with the TRTG method with those obtained from electrical resistance measurements
A Coupled Thermoreflectance Thermography Experimental System and Ultra-Fast Adaptive Computational Engine for the Complete Thermal Characterization of Three-Dimensional Electronic Devices : Validation
This work builds on the previous introduction [1] of a coupled experimental-computational system devised to fully characterize the thermal behavior of complex 3D submicron electronic devices. The new system replaces the laser-based surface temperature scanning approach with a CCD camera-based approach. As before, the thermo-reflectance thermography system is used to non-invasively measure with submicron resolution the 2D surface temperature field of an activated device. The measured temperature field is then used as input for an ultra-fast inverse computational solution to fully characterize the thermal behavior of the complex three-dimensional device. For the purposes of this investigation, basic micro-heater devices were built, activated, and measured. In order to quantitatively validate the coupled experimental-computational system, the system was used to extract geometric features of a known device, thus assessing the system's ability to combine measured experimental results and computations to fully characterize complex 3D electronic devices
Quantal Two-Centre Coulomb Problem treated by means of the Phase-Integral Method I. General Theory
The present paper concerns the derivation of phase-integral quantization
conditions for the two-centre Coulomb problem under the assumption that the two
Coulomb centres are fixed. With this restriction we treat the general
two-centre Coulomb problem according to the phase-integral method, in which one
uses an {\it a priori} unspecified {\it base function}. We consider base
functions containing three unspecified parameters and .
When the absolute value of the magnetic quantum number is not too small, it
is most appropriate to choose . When, on the other hand,
is sufficiently small, it is most appropriate to choose .
Arbitrary-order phase-integral quantization conditions are obtained for these
choices of . The parameters and are determined from the
requirement that the results of the first and the third order of the
phase-integral approximation coincide, which makes the first-order
approximation as good as possible.
In order to make the paper to some extent self-contained, a short review of
the phase-integral method is given in the Appendix.Comment: 23 pages, RevTeX, 4 EPS figures, submitted to J. Math. Phy
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