Path-integral molecular dynamics simulation of 3 C − Si C Ramírez, Rafael; Herrero, Carlos P.; Hernández, Eduardo R. ...
Physical review. B, Condensed matter and materials physics,
1/2008, Letnik:
77, Številka:
4
Journal Article
The purpose of our study was to compare the efficacy and safety of alteplase in acute myocardial infarction (AMI), when administered in a double bolus regimen or an accelerated regimen during ...admission to an intensive care or coronary care unit (ICU/CCU).
A retrospective cohort study including all the AMI patients treated with alteplase recorded in the ARIAM register (Analysis of Delay in AMI), a multi-center register in which 77 Spanish hospitals participate. The study period was from January 1995 to January 2000.
4,615 AMI patients were studied. The accelerated regimen (Group I) was administered to 57.51% (2,654 patients) and the remaining 42.49% (1,961 patients) received the double bolus regimen (Group II). There were no differences in mortality or in the incidence of hemorrhagic stroke between the groups. The mortality was 7.15% in Group I versus 6.43% in Group II (not significant). The incidence of hemorrhagic stroke was 1.09% in Group I versus 1.22% in Group II (not significant). Fewer coronary angiographies were required in Group I (6.28% vs. 8.99%; p<0.001) and fewer rescue angioplasties (10.67% vs. 21.88%, p=0.03). Group I also showed a smaller requirement for stent insertion (2.45% vs. 4.77%; p<0.0001) and for assistance using intra-aortic balloon contrapulsation (0.47% vs. 1.36%; p=0.02).
The two regimens appear to be similar in efficacy and safety. Nevertheless, from these results it may be hypothesized that further revascularization techniques are required after double bolus administration.
Heterojunction diodes fabricated by plasma enhanced chemical vapour deposition of
n-type amorphous silicon carbide on p-type crystalline silicon are analysed by measuring their current-voltage ...characteristics. Two carrier transport mechanisms are believed to be at the origin of the forward current. At low bias voltage, the current is due to recombination in the amorphous side of the space charge region, while at higher voltages, the current becomes space charge limited. At reverse bias, the current can be explained by tunnelling models. The space charge limited currents in these heterojunctions have been used to determine the density of states in the
n-type a-Si
1 −
x
C
x
:H gap. The results show the increase in localized states when approaching the conduction band edge.
Molecular dynamics simulations of 3C-SiC have been performed as a function of pressure and temperature. These simulations treat both electrons and atomic nuclei by quantum mechanical methods. While ...the electronic structure of the solid is described by an efficient tight-binding Hamiltonian, the nuclei dynamics is treated by the path integral formulation of statistical mechanics. To assess the relevance of nuclear quantum effects, the results of quantum simulations are compared to others where either the Si nuclei, the C nuclei or both atomic nuclei are treated as classical particles. We find that the experimental thermal expansion of 3C-SiC is realistically reproduced by our simulations. The calculated bulk modulus of 3C-SiC and its pressure derivative at room temperature show also good agreement with the available experimental data. The effect of the electron-phonon interaction on the direct electronic gap of 3C-SiC has been calculated as a function of temperature and related to results obtained for bulk diamond and Si. Comparison to available experimental data shows satisfactory agreement, although we observe that the employed tight-binding model tends to overestimate the magnitude of the electron-phonon interaction. The effect of treating the atomic nuclei as classical particles on the direct gap of 3C-SiC has been assessed. We find that non-linear quantum effects related to the atomic masses are particularly relevant at temperatures below 250 K.
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