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41.
During dynamic exercise in warm environments, requisite increases in skin and active muscle blood flows are supported by increasing cardiac output (Qc) and redistributing flow away from splanchnic and renal circulations. To examine the effect of age on these responses, six young (Y; 26 +/- 2 yr) and six older (O; 64 +/- 2 yr) men performed upright cycle exercise at 35 and 60% of peak O2 consumption (VO2peak) in 22 and 36 degrees C environments. To further isolate age, the two age groups were closely matched for VO2peak, weight, surface area, and body composition. Measurements included heart rate, Qc (CO2 rebreathing), skin blood flow (from increases in forearm blood flow (venous occlusion plethysmography), splanchnic blood flow (indocyanine green dilution), renal blood flow (p-amino-hippurate clearance), and plasma norepinephrine concentration. There were no significant age differences in Qc; however, in both environments the O group maintained Qc at a higher stroke volume and lower heart rate. At 60% VO2peak, forearm blood flow was significantly lower in the O subjects in each environment. Splanchnic blood flow fell (by 12-14% in both groups) at the lower intensity, then decreased to a greater extent at 60% VO2peak in Y than in O subjects (e.g., -45 +/- 2 vs. -33 +/- 3% for the hot environment, P < 0.01). Renal blood flow was lower at rest in the O group, remained relatively constant at 35% VO2peak, then decreased by 20-25% in both groups at 60% VO2peak. At 60% VO2peak, 27 and 37% more total blood flow was redistributed away from these two circulations in the Y than in the O group at 22 and 36 degrees, respectively. It was concluded that the greater increase in skin blood flow in Y subjects is partially supported by a greater redistribution of blood flow away from splanchnic and renal vascular beds.  相似文献   
42.
A decline of cytosol protein kinase C activity was observed in rat myocardial cells at 4 and 8 h after endotoxin administration, and membrane-associated protein kinase C activity rose at the same time. The activity of membrane protein kinase C in aortic smooth muscle cells at 0.5 and 4 h after endotoxin injection was higher than that in control, while cytosol protein kinase C activity was lower. The results indicate that protein kinase C was activated in myocardial cells and aortic smooth muscle cells during various phases of endotoxemia.  相似文献   
43.
Capillary phenomena was studied and discussed by the scholars about 200 years ago, but the progress was slow due to the limited equipment and manufacture precision of the microchannel. In recent years, because of the rapid development of MEMS and micromachining, many applications of the capillary flow is widely developing in some modern processes, such as underfilling of flip chip, flow in microfluidic chip or biochip, and a variety of other fields.  相似文献   
44.
Effect of Cu concentration on the reactions between Sn-Ag-Cu solders and Ni   总被引:2,自引:0,他引:2  
The reaction between the Sn-Ag-Cu solders and Ni at 250°C for 10 min and 25 h was studied. Nine different Sn-Ag-Cu solders, with the Ag concentration fixed at 3.9 wt.% and Cu concentrations varied between 0.0–3.0 wt.%, were used. When the reaction time was 10 min, the reactions strongly depended on the Cu concentration. At low-Cu concentrations (≦0.2 wt.%), only a continuous (Ni1−xCux)3Sn4 layer formed at the interface. When the Cu concentration increased to 0.4 wt.%, a continuous (Ni1−xCux)3Sn4 layer and a small amount of discontinuous (Cu1−yNiy)6Sn5 particles formed at the interface. When the Cu concentration increased to 0.5 wt.%, the amount of (Cu1−yNiy)6Sn5 increased and (Cu1−yNi6)6Sn5 became a continuous layer. Beneath this (Cu1−yNiy)6Sn5 layer was a very thin but continuous layer of (Ni1−xCux)3Sn4. At higher Cu concentrations (0.6–3.0 wt.%), (Ni1−xCux)3Sn4 disappeared, and only (Cu1−yNiy)6Sn5 was present. The reactions at 25 h also depended strongly on the Cu concentration, proving that the strong concentration dependence was not a transient phenomenon limited to a short reaction time. The findings of this study were rationalized using the Cu-Ni-Sn isotherm. This study shows that precise control over the Cu concentration in solders is needed to produce consistent results.  相似文献   
45.
This study relates to the development of coatings for optical discs in high-density digital versatile disc systems (HD-DVD or blue lay disk) that use a high numerical aperture of 0.85 at 405 nm wavelength and have a protective top layer over a primer layer for protection against damage and dust. Ultraviolet-curable raw materials of two acrylic monofunctional monomers ( isobornylacrylate, IBA and tetrahydrofurfurylacrylate, THFA) and two kinds of urethaneacrylate oligomers (OUMD and OUME) have been easily mixed with photoinitiators. Curing rate of these materials was characterized by FT-IR. In case of top coats, VTES (vinyltriethoxysilane) and acrylic acid were added to enhance the abrasion resistance. These two kinds of UV-curable resinous materials having no solvent were synthesized and investigated as means for making a blue ray disk having good optical and mechanical properties. In addition, dynamic characteristics including reflectivity, fluctuation of RF signal and noise level were also investigated.  相似文献   
46.
Orbital-free density functional theory (OF-DFT) can be made to scale linearly with sample size, allowing thousands of atoms to be treated explicitly with quantum mechanics. State-of-the-art kinetic energy density functionals and ion–electron pseudopotentials are used to obtain accurate structural property predictions for nanoparticles, nanowires, extended surfaces, and nanoindentation of simple metals.  相似文献   
47.
48.
Bibliometric analysis of tsunami research   总被引:3,自引:0,他引:3  
The use of the bibilometric analytical technique for examining tsunami research does not exist in the literature. The objective of the study was to perform a bibliometric analysis of all tsunami-related publications in the Science Citation Index (SCI). Analyzed parameters included document type, language of publication, publication output, authorship, publication patterns, distribution of subject category, distribution of author keywords, country of publication, most-frequently cited article, and document distribution after the Indonesia tsunami. The US and Japan produced 53% of the total output where the seven major industrial countries accounted for the majority of the total production. English was the dominant language, comprising 95% of articles. A simulation model was applied to describe the relationship between the number of authors and the number of articles, the number of journals and the number of articles, and the percentage of total articles and the number of times a certain keyword was used. Moreover the tsunami publication patterns in the first 8 months after the Indonesia tsunami occurred on 26 December 2004 indicated a high percentage of non-article publications and more documents being published in journals with higher impact factors.  相似文献   
49.
In this paper, we propose an efficient design method for area optimization in a digital filter. The conventional methods to reduce the number of adders in a filter have the problem of a long critical path delay caused by the deep logic depth of the filter due to adder sharing. Furthermore, there is such a disadvantage that they use the transposed direct form (TDF) filter which needs more registers than those of the direct form (DF) filter. In this paper, we present a hybrid structure of a TDF and DF based on the flattened coefficients method so that it can reduce the number of flip‐flops and full‐adders without additional critical path delay. We also propose a resource sharing method and sharing‐pattern searching algorithm to reduce the number of adders without deepening the logic depth. Simulation results show that the proposed structure can save the number of adders and registers by 22 and 26%, respectively, compared to the best one used in the past.  相似文献   
50.
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