SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
We present a phenomenological treatment of free-electron laser storage ring saturation dynamics. The model includes longitudinal instabilities, Touschek intrabeam scattering, and nonzero off-energy-function contributions. The model predictions are compared with Super ACO experimental results and the agreement is shown to be satisfactory.
We find that a 2D periodic potential, with different modulation amplitudes in the x and y directions, and a perpendicular magnetic field may lead to a transition to electron transport along the direction of stronger modulation and to localization in the direction of weaker modulation. In the experimentally accessible regime we relate this new quantum transport phenomenon to avoided band crossings due to classical chaos.
Electron-hole mixing-induced fine structure in alkaline earth hexaborides leads to lower energy (temperature) scales, and thus a stronger tendency toward an excitonic instability than in their doped counterparts (viz. Ca1-xLaxB6, x approximately 0.005), which are high-Curie-temperature, small-moment ferromagnets. Comparison of Fermi surfaces and spectral distributions with de Haas-van Alphen, optical, transport, and tunneling data indicates that SrB6 remains a fermionic semimetal down to (at least) 5 K, rather than forming an excitonic condensate. For the doped system the Curie temperature is higher than the degeneracy temperature.
63Cu nuclear magnetic resonance spin-echo decay rate (T-12) measurements are reported for the normal and superconducting states of a single crystal of Pr(1.85)Ce(0.15)CuO(4-y) in a magnetic field B(0)=9 T over the temperature range 2<T<200 K. The spin-echo decay rate is temperature dependent for T<55 K and has a substantial dependence on the radio frequency (rf) pulse parameters below T approximately 25 K. This dependence indicates that T-12 is strongly effected by a local magnetic field distribution that can be modified by the rf pulses, including ones that are not at the nuclear Larmor frequency. The low-temperature results are consistent with the formation of a static inhomogeneous electronic structure that couples to the rf fields of the pulses.
We report correlated-electron calculations of optically excited states in ten semiconducting single-walled carbon nanotubes with a wide range of diameters. Optical excitation occurs to excitons whose binding energies decrease with increasing nanotube diameter, and are smaller than the binding energy of an isolated strand of poly-(paraphenylene vinylene). The ratio of the energy of the second optical exciton polarized along the nanotube axis to that of the lowest exciton is smaller than the value predicted within single-particle theory. The experimentally observed weak photoluminescence is an intrinsic feature of semiconducting nanotubes.
We solve the disordered Holstein model in three dimensions considering the phonon variables to be classical. After mapping out the phases of the "clean" strong coupling problem, we focus on the effect of disorder at strong electron-phonon (EP) coupling. The presence of even weak disorder (i) enormously enhances the resistivity (rho) at T=0, simultaneously suppressing the density of states at the Fermi level, (ii) suppresses the temperature dependent increase of rho, and (iii) leads to a regime with drho/dT<0. We locate the origin of these anomalies in the disorder induced tendency towards polaron formation, and the associated suppression in effective carrier density and mobility. These results, explicitly at "metallic" density, are of direct relevance to disordered EP materials such as covalent semiconductors, the manganites, and to anomalous transport in the A-15 compounds.
The ground state electronic properties of the strongly correlated transition metal Ni are usually not accessible from the excitation spectra measured in photoelectron spectroscopy. We show that the bottom of the Ni d band along [111] can be probed through the energy dependence of the phase of quantum-well states in Ag/Ni(111). Our model description of the quantum-well energies measured by angle-resolved photoemission determines the bottom of the empty set 1 d band of Ni as 2.6 eV, in full agreement with standard local density theory and at variance with the values of 1.7-1.8 eV from direct angle-resolved photoemission experiments of Ni.
The crystallography of recrystallization has been investigated in channel-die deformed pure aluminium bicrystals with {100}<011>/{110}<001> orientations. The microstructural and microtextural changes during the early stages of recrystallization were followed by systematic local orientation measurements using scanning and transmission electron microscopes. In particular, orientation mapping combined with in situ sample heating was used to investigate the formation and growth of new grains at very early stages of recrystallization. Grain boundary migration and 'consumption' of the as-deformed areas was always favoured along directions parallel to the traces of the {111} slip planes that had been most active during deformation.
Guidelines regarding patient-provider electronic mail are presented. The intent is to provide guidance concerning computer-based communications between clinicians and patients within a contractual relationship in which the health-care provider has taken on an explicit measure of responsibility for the client's care. The guidelines address two interrelated aspects: effective interaction between the clinician and patient, and observance of medicolegal prudence. Recommendations for site-specific policy formulation are included.
As part of the Outcome Project of the Accreditation Council for Graduate Medical Education, training programs are required to evaluate trainees across six general competencies. Assessment of the patient-care competency by direct observation can be supplemented with a quantification of overall experience through the use of case logs. However, manual entry of information into such registries frequently is incomplete. The authors report on the development of an automated electronic case log as a novel tool for evaluating the experience of individual trainees or an entire training program. Specific examples of use of the case log are provided. The authors use a pediatric emergency medicine fellowship as a paradigm to demonstrate the potential utility across all emergency medicine training programs. In addition, the authors discuss how additional information technologies might be incorporated to further these evaluative efforts in the future.
This article considers the government plans for the development of electronic health and patient records as set out in the NHS Plan and the progress and problems which have been encountered in their realization.
We report the development and initial implementation of what we believe to be a new rapid- spatial-scan millimeter-wave interferometer for plasma density measurements. The fast scan is effected by electronic frequency sweeping of a wideband (180-280 GHz) backward-wave oscillator whose output is focused onto a fixed blazed diffraction grating. The system, which augments the rotating-grating scanned multiview H-1 heliac interferometer, can sweep the plasma cross section in a period of less than 1 ms with a beam diameter in the plasma of 20 mm and phase noise of the order of 0.01 rad.
Most molecular and supramolecular organic photochemical reactions involve paramagnetic reactive intermediates (such as molecular triplet states, triplet radical pairs, and free radicals). In a number of cases these species are created with "anomalous" spin populations which are far from thermal equilibrium. Such paramagnetic species are said to be "spin polarized" and may be observed directly by time-resolved electron paramagnetic resonance (TREPR). The TREPR technique can be applied to exploit spin polarization, which, in addition to providing an enormous signal to noise enhancement, also reveals the mechanisms involved in photochemical reactions. TREPR spectroscopy provides a means of tracking the reaction of radicals with molecules and the nonreactive interactions of radicals with other radicals in real time. The latter interactions provide a systematic investigation of supramolecular interactions of geminate radicals in micelles.
The hepatotoxic effect of the analitically pure toluol and a toluol neing used in the Chemical Factory "Tiszai" was investigated. Single toxic and various subtoxic doses of toluol were administered intraperitoneally and subeutaneously to male rats of CFY. The liver of the animals was investigated by the aid of electron microscope. It was established that large doses of toluol lead to the decrease of glycogen content and increase of the number of mitochondria in the hepatic cells. Numerous dividing mitochondria were also observed, with a great deal of matrix graules. Electronhistochemical demonstration of the activity of succinic-dehydrogenase does not reveal any difference between the liver of experimental and control animals. As an effect of small doses of toluol degenerative changes-enlargement of the cysternae of the endoplasmatic reticulum, separation of ribosomes, increase of the number of autophag-vacuola-could be seen. The degenerative changes occurred only in a part of the hepatic cells which appeared to be distributed randomly in the liver lobules. Authors assume that lesions revealed are of reversible type.
Electronic-conformational interactions (ECI) are the main causes of enzymatic catalysis and other biological processes, occuring at the molecular and super-molecular levels. For the studies of several problems, related to ECI the qualitative methods of quantum chemistry can be used, in particular the method of intermolecular orbitals. The possibilities of this method are shown in some simple cases.
The biggest problem in organisation of the effective and rational health care of good quality in Bosnia quality and Herzegovina is a functional and updated Health Information System. In this system, important role play Health Statistic System in which documentation and evidence are very important segment. Developed countries proceeded from the manual and semiautomatic method of medical data processing and system management to the new methods of entering, storage, transfer, searching and protection of data using electronic equipment. Recently, the competition between manufacturers of the Smart Card and Laser Card is reality. Also scientific and professional debate exists about the standard card for storage of medical information in Health Care System. First option is supported by West European countries that developing Smart Card called Eurocard and second by USA and Far East countries. Because the Health Care System and other segments of Society of Bosnia and Herzegovina innovate intensively similar systems, the authors of this article intend to open discussion, and to show advantages and failures of each technological medium.
Explore the source record for details and available documents.
Explore the source record for details and available documents.