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71.
Objective: Low socioeconomic status (SES) environments may impede the development of a bank of resources, labeled reserve capacity, and may also be stressful, thereby depleting available reserves. In consequence, lower SES persons may experience more negative emotions, leading to adverse health consequences. The authors tested the reserve capacity model in relation to the metabolic syndrome. Design: There were 401 initially healthy women who followed longitudinally for 12 years. Self-reported characteristics, stressors, and cardiovascular risk factors were measured repeatedly. Structural equation modeling was used to evaluate hypothesized relationships. Main Outcome Measure: Metabolic syndrome factor. Results: Confirmatory factor analysis verified reserve capacity as the aggregate of optimism, self-esteem, and social support, and negative emotion as the aggregate of depressive symptoms, anger, and tension. Structural equation modeling showed two pathways to the metabolic syndrome factor, (χ2(59) = 111.729, p ldf = 1.894; CFI = .956; RMSEA = .047): direct from low SES to the metabolic syndrome factor (B = -0.19, t = -3.24, p = .001); and indirect, from low SES to low reserve capacity to high negative emotions to the metabolic syndrome factor (B = -0.024, t = -2.05, p = .04). Conclusion: Low SES may increase risk for metabolic syndrome, in part, through reserve capacity and negative emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
72.
We have modified Merrifield’s resin to provide polymers containing secondary amine groups. Lithiation of the solids gives strongly basic yet poorly nucleophilic resins useful for rearrangement of epoxides to their corresponding allylic alcohols. The resins are easy to handle, non-volatile, non-toxic, and are easily recovered and reused, providing environmental and economic benefits that might have commercial viability.  相似文献   
73.
BACKGROUND: The optimal timing for surgery in patients with mitral regurgitation is disputed. Because of the frequency of left ventricular dysfunction, which is difficult to predict, early surgery has been recommended, but its potential benefits have not been demonstrated. METHODS AND RESULTS: The outcomes of 221 patients (mean age, 65 +/- 13 years; 71% males) with flail leaflets diagnosed with two-dimensional echocardiography between 1980 and 1989 who were eligible for operation were analyzed. Group I comprised 63 patients who had early mitral valve surgery (within 1 month after diagnosis). Group II comprised 158 patients initially treated conservatively (80 of whom were operated on later). Group I patients were younger (P=.009), had more symptoms (P<.0001), and were more frequently in atrial fibrillation (P=.023) than group II patients. There was no difference in ejection fraction between the groups. The early surgery strategy was followed by an improved overall survival rate (P=.028) and a lower incidence of cardiovascular deaths (P=.025), congestive heart failure (P=.046), and new chronic atrial fibrillation (P=.032), as confirmed by multivariate analysis (adjusted risk ratios of 0.31, 0.18, 0.38, and 0.05, respectively; all P<.02). CONCLUSIONS: In patients with mitral regurgitation due to flail leaflets, the strategy of early surgery versus conservative management is associated with an improved long-term survival rate, decreased cardiac mortality, and decreased morbidity after diagnosis. This outcome advantage suggests that early surgery is a reasonable treatment option to be considered in low-risk candidates with repairable valves and severe mitral regurgitation.  相似文献   
74.
75.
The influence of visual workload history on visual performance   总被引:3,自引:0,他引:3  
M L Matthews 《Human factors》1986,28(6):623-632
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76.
77.
Fractions of Elbistan and Seyitomer (Turkish) lignites, extracted with supercritical toluene at 340 °C and 8 MPa, have been separated by solvent extraction and silica-gel chromatography. Analyses by n.m.r. and i.r. spectroscopies and other methods have been combined in structural-analysis schemes to yield information about the average molecule in aromatic extracts. Carbon aromaticities, fa, derived from 22.63 MHz 1H-decoupled pulse Fourier-transform (PFT) 13C-n.m.r. are more widely spread for Elbistan (0.34–0.56) than for Seyitomer (0.40–0.43), and are lower than for supercritical-gas (SCG) products from bituminous coals. 13C-n.m.r. also reveals the presence of aromatic ether-O in polar fractions. Narrow aromatic signals in 100 MHz 1H-n.m.r. spectra suggest the presence of single-aromatic-ring average structures. In the hexane-soluble aromatics, 27% (Elbistan) and 29% (Seyitomer) of the available sites are substituted by alkyI groups, some of which are at least eight carbon atoms long; the hexane-soluble polar and asphaltene/asphaltol fractions contain fewer such groups.  相似文献   
78.
It is not easy to find candidate sites within a given proteinwhere the geometry of the polypeptide chain matches that ofmetal-binding sites in known protein structures. By choosinga location in T4 lysozyme that is inherently flexible, it waspossible to engineer a two-histidine site that binds differentdivalent cations. Crystallographic analysis shows that the geometryof binding of zinc is distorted tetrahedral while that of cobaltand nickel is octahedral. Insofar as spectroscopic data canbe measured, they indicate that similar modes of coordinationare retained in solution. The two substitutions, Thr21  相似文献   
79.
The paper gives a short overview on tungsten (W) coatings deposited by various methods on carbon materials (carbon fibre composite – CFC and fine grain graphite – FGG). Vacuum Plasma Spray (VPS), Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) techniques are analyzed in respect with the characteristics and performances of the W coatings.A particular attention is paid to the Combined Magnetron Sputtering and Ion Implantation (CMSII) technique, which was developed during the last 4 years from laboratory to industrial scale and it is successfully applied for W coating (10–15 μm and 20–25 μm) of more than 2500 tiles for the ITER-like Wall project at JET and ASDEX Upgrade. This technique involves simultaneously magnetron sputtering and high energy (tens of keV) ion implantation. Due to the ion bombardment a stress relief occurs within the coating enabling its growth without delamination to a relatively large thickness. In addition, in order to adjust the thermal expansion mismatch between CFC and W, a Mo interlayer of 2–3 μm is currently used. Experimentally, W/Mo coatings with a thickness up to 50 μm were produced and successfully tested in the GLADIS ion beam facility up to 23 MW/m2.  相似文献   
80.
Thorium oxide and uranium oxide pellet fuel development activities leading to a process fohd fabrication of high density, homogeneous fuel pellets are described. Conventional dry ball-milling was used to comminute commercially available powders. After separate milling, these ThO2-UO2mixtures were co-milled, pressed, and sintered to 95 % of theoretical density with a homogeneous distribution of the components. An intimate mix of highly active powders promotes solid solution formation and yields high density pellets.  相似文献   
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