349 research outputs found
Coronary interventions in Europe 1992
The general practice of coronary interventions is influenced by various aspects, traditional, cultural, socioeconomic and personal. The aim of this survey was to collect the data on coronary interventions in all member countries of the European Society of Cardiology. The data from 12 of the 35 national members were missing or grossly incomplete and were therefore excluded from the analysis. Coronary angiography The total number of coronary angiograms was reported as 683 888, an incidence of 1009 ± 1021 per million inhabitants (range 9 (Romania) to 3076 (Germany)). Germany (246115 cases), France (144 754), the United Kingdom (76 296), Italy (45 517) and Spain (43 495) registered 81% of all the coronary angiograms performed. Percutaneous transluminal coronary angioplasty (PTCA) The total number of reported PTCAs was 147 729, which on average accounted for 19 ± 11% (range 2 (Lithuania) to 53% (Netherlands)) of the coronary angiograms. Most of the PTCAs (82%) were confined to a single vessel. The highest incidence of multivessel PTCA was reported from Slovakia (28%). PTCA took place immediately after the diagnostic study in only 18% of cases. Adjusted per capita, Germany ranked first with 703 PTCAs per million inhabitants, followed by Iceland (619), France (614), Belgium (568) and Austria (485). A major in-hospital complication was reported in 2.5% of the patients undergoing PTCA: 0.4% hospital deaths, 1.0% emergency CABGs and 1.1% myocardial infarctions. New devices Stents were implanted in 3211 patients (2.7% of all PTCA patients), equally distributed between emergency situations (53%) and elective procedures. Other interventional devices were applied in 4133 cases (2.8% of all PTCA cases): directional atherectomy, rotablator, transluminal extraction catheter, laser and Rotacs accounted for 1452, 1232, 55, 558 and 222, respectively. Coronary ultrasound (1350 cases) and coronary angioscopy (373 cases) were rarely performed. Coronary artery bypass grafting (CABG) A total of 63 477 patients underwent CABG in the reporting centres resulting in a PTCA/CABG ratio of 2.3. A significant under-reporting of surgery in the participating centres must be assumed. Conclusions Although partial reporting might bias conclusions, several findings of this survey are noteworthy: (1) PTCA was a well accepted treatment for coronary artery disease, (2) PTCA was applied more frequently than CABG, (3) there was an extremely wide range of coronary angiography and PTCA performed per million inhabitants, (4) the most common additional procedure was stent implantation, but other new devices were only rarely applie
Molecular dynamics in shape space and femtosecond vibrational spectroscopy of metal clusters
We introduce a method of molecular dynamics in shape space aimed at metal
clusters. The ionic degrees of freedom are described via a dynamically
deformable jellium with inertia parameters derived from an incompressible,
irrotational flow. The shell correction method is used to calculate the
electronic potential energy surface underlying the dynamics. Our finite
temperature simulations of Ag_14 and its ions, following the negative to
neutral to positive scheme, demonstrate the potential of pump and probe
ultrashort laser pulses as a spectroscopy of cluster shape vibrations.Comment: Latex/Revtex, 4 pages with 3 Postscript figure
Dynamics of concurrent and sequential Central European and Scandinavian heatwaves
In both 2003 and 2018 a heatwave in Scandinavia in July was followed by a heatwave in Central Europe in August. Whereas the transition occurred abruptly in 2003, it was gradual in 2018 with a 12-day period of concurrent heatwaves in both regions. This study contrasts these two events in the context of a heatwave climatology to elucidate the dynamics of both concurrent and sequential heatwaves. Central European and, in particular, concurrent heatwaves are climatologically associated with weak pressure gradient (WPG) events over Central Europe, which indicate the absence of synoptic activity over this region. One synoptic pattern associated with such events is Scandinavian blocking. This pattern is at the same time conducive to heatwaves in Scandinavia, thereby providing a mechanism by which Scandinavian and Central European heatwaves can co-occur. Further, the association of WPG events with Scandinavian blocking constitutes a mechanism that allows heatwaves to grow beyond the perimeter of the synoptic system from which they emanated. A trajectory analysis of the source regions of the low-level air incorporated in the heatwaves indicates rapidly changing air mass sources throughout the heatwaves in both regions, but no recycling of heat from one heatwave to the other. This finding is line with a composite analysis indicating that transitions between Scandinavian and Central European heatwaves are merely a random coincidence of heatwave onset and decay
Three-tangle for mixtures of generalized GHZ and generalized W states
We give a complete solution for the three-tangle of mixed three-qubit states
composed of a generalized GHZ state, a|000>+b|111>, and a generalized W state,
c|001>+d|010>+f|100>. Using the methods introduced by Lohmayer et al. we
provide explicit expressions for the mixed-state three-tangle and the
corresponding optimal decompositions for this more general case. Moreover, as a
special case we obtain a general solution for a family of states consisting of
a generalized GHZ state and an orthogonal product state
Charge-Induced Fragmentation of Sodium Clusters
The fission of highly charged sodium clusters with fissilities X>1 is studied
by {\em ab initio} molecular dynamics. Na_{24}^{4+} is found to undergo
predominantly sequential Na_{3}^{+} emission on a time scale of 1 ps, while
Na_{24}^{Q+} (5 \leq Q \leq 8) undergoes multifragmentation on a time scale
\geq 0.1 ps, with Na^{+} increasingly the dominant fragment as Q increases. All
singly-charged fragments Na_{n}^{+} up to size n=6 are observed. The observed
fragment spectrum is, within statistical error, independent of the temperature
T of the parent cluster for T \leq 1500 K. These findings are consistent with
and explain recent trends observed experimentally.Comment: To appear in Physical Review Letter
Electronic entropy, shell structure, and size-evolutionary patterns of metal clusters
We show that electronic-entropy effects in the size-evolutionary patterns of
relatively small (as small as 20 atoms), simple-metal clusters become prominent
already at moderate temperatures. Detailed agreement between our
finite-temperature-shell-correction-method calculations and experimental
results is obtained for certain temperatures. This agreement includes a
size-dependent smearing out of fine-structure features, accompanied by a
measurable reduction of the heights of the steps marking major-shell and
subshell closings, thus allowing for a quantitative analysis of cluster
temperatures.Comment: Latex/Revtex, 4 pages with 3 Postscript figure
Thermal expansion in small metal clusters and its impact on the electric polarizability
The thermal expansion coefficients of clusters with and , and
are obtained from {\it ab initio} Born-Oppenheimer LDA molecular dynamics.
Thermal expansion of small metal clusters is considerably larger than that in
the bulk and size-dependent. We demonstrate that the average static electric
dipole polarizability of Na clusters depends linearly on the mean interatomic
distance and only to a minor extent on the detailed ionic configuration when
the overall shape of the electron density is enforced by electronic shell
effects. The polarizability is thus a sensitive indicator for thermal
expansion. We show that taking this effect into account brings theoretical and
experimental polarizabilities into quantitative agreement.Comment: 4 pages, 2 figures, one table. Accepted for publication in Physical
Review Letters. References 10 and 23 update
Surface reconstruction induced geometries of Si clusters
We discuss a generalization of the surface reconstruction arguments for the
structure of intermediate size Si clusters, which leads to model geometries for
the sizes 33, 39 (two isomers), 45 (two isomers), 49 (two isomers), 57 and 61
(two isomers). The common feature in all these models is a structure that
closely resembles the most stable reconstruction of Si surfaces, surrounding a
core of bulk-like tetrahedrally bonded atoms. We investigate the energetics and
the electronic structure of these models through first-principles density
functional theory calculations. These models may be useful in understanding
experimental results on the reactivity of Si clusters and their shape as
inferred from mobility measurements.Comment: 9 figures (available from the author upon request) Submitted to Phys.
Rev.
Ionic structure and photoabsorption in medium sized sodium clusters
We present ground-state configurations and photoabsorption spectra of Na-7+,
Na-27+ and Na-41+. Both the ionic structure and the photoabsorption spectra of
medium-size sodium clusters beyond Na-20 have been calculated self-consistently
with a nonspherical treatment of the valence electrons in density functional
theory. We use a local pseudopotential that has been adjusted to experimental
bulk properties and the atomic 3s level of sodium. Our studies have shown that
both the ionic structure of the ground state and the positions of the plasmon
resonances depend sensitively on the pseudopotential used in the calculation,
which stresses the importance of its consistent use in both steps.Comment: 4 pages, 3 figures. Accepted for publication in PRB, tentatively July
15th, 1998 some typos corrected, brought to nicer forma
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