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71.
The liver S9 head space vial equilibration technique is an in vitro alternative that holds promises for a satisfactory in vivo extrapolation of liver metabolism of volatile organic chemicals. The aim of this study was to investigate the suitability of this methodology for the extrapolation of in vitro metabolic data from rodent to man by allometry with the two highly metabolized organic solvents toluene and n-hexane as model substances. The calculated hepatic clearance of toluene in man from rodent liver S9 in this study was equal to the reported total body clearance of toluene in man, suggesting insignificant extrahepatic clearance of toluene in humans. The calculated hepatic clearance of n-hexane was less than the reported values of total body clearance of n-hexane in man, indicating an about 80% extrahepatic clearance of n-hexane in humans. Both results are in line with our present knowledge of the metabolism of the two organic solvents in man. Allometric scaling from rodent liver S9 head space incubations to in vivo metabolism of toluene and n-hexane in man thus seems promising and could be a method of choice for scaling of organic solvent metabolism in general. 相似文献
72.
The authors present two optimization models for decision support tools for selecting available programs in the market. Information on reliability and cost of the available programs are considered as basic criteria for the selection. These models apply to software packages that consist of several programs where each, upon execution, performs a different function as required by the user. The objective is to maximize the average reliability of the software package, considering the tradeoff between reliability and cost of the programs. In model one, redundancy of the programs is not considered; thus, the authors select one program for each function. In model two, redundancy is considered: thus, the authors identify the optimal set of programs for each function. They begin with a discussion of the underlying concepts that rationalize the composition of the models 相似文献
73.
Boone Kyle Brauer; Lesser Ira M.; Miller Bruce L.; Wohl Marcy; Berman Nancy; Lee Alison; Palmer Barton; Back Carla 《Canadian Metallurgical Quarterly》1995,9(3):390
Neuropsychological evaluation of 73 older healthy, unmedicated outpatients with major depression and 110 controls suggested that relatively distinct cognitive profiles may correspond to the presence vs. severity of depression. Specifically, the presence of depression was associated with subtle weaknesses in visual memory and nonverbal intelligence, with sparing of verbal skills (verbal intelligence, language, and verbal memory), constructional ability, attention, information processing speed, and executive functions. In contrast, increasing severity of depression was associated with mild weaknesses, primarily in information-processing speed and executive skills, but was essentially unrelated to memory (verbal or visual), intelligence, language skills, constructional ability, or basic attention. Findings are discussed in terms of a possible state vs. trait model of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
ER Nekrasova DM Berman RR Rustandi HE Hamm AG Gilman VY Arshavsky 《Canadian Metallurgical Quarterly》1997,36(25):7638-7643
RGS proteins (regulators of G protein signaling) constitute a newly appreciated group of negative regulators of G protein signaling. Several members of this group stimulate the guanosine triphosphatase (GTPase) activity of various G protein alpha-subunits, including the photoreceptor G protein, transducin. In photoreceptor cells transducin GTPase is known to be substantially accelerated by the coordinated action of the gamma-subunit of its effector enzyme, cGMP phosphodiesterase (PDE gamma), and another yet unidentified membrane-associated protein factor. Here we test the possibility that this factor belongs to the RGS family of GTPase stimulators. We report a detailed kinetic analysis of transducin GTPase activation by two members of the RGS family, RGS4 and G alpha interacting protein (GAIP). RGS4, being at least 5-fold more potent than GAIP, stimulates the rate of transducin GTPase by 2 orders of magnitude. Neither RGS4 nor GAIP requires PDE gamma for activating transducin. Rather, PDE gamma causes a partial reversal of transducin GTPase activation by RGS proteins. The effect of PDE gamma is based on a decreased apparent affinity of RGS for the alpha-subunit of transducin. Our observations indicate that GTPase activity of transducin can be activated by at least two distinct mechanisms, one based on the action of RGS proteins alone and another involving the cooperative action of the effector enzyme and another protein. 相似文献
75.
L. S. Berman 《Semiconductors》1997,31(1):63-66
Existing diagnostic techniques used to evaluate the temporal instability of the parameters of a semiconductor-insulator interface
with deep-level centers are analyzed. A method is proposed for evaluating temporal instability according to the long-term
isothermal transient behavior of the capacitance of a metal-insulator-semiconductor structure. The energy spectrum of the
effective density of surface states is determined for n-type InP-SiO2-Al structures prepared by chemical vapor deposition. The variation of the capacitance during long-term isothermal relaxation
provides a criterion of temporal instability of a semiconductor-insulator interface.
Fiz. Tekh. Poluprovodn. 31, 78–82 (January 1997) 相似文献
76.
The incidence of difficulty in tracheal intubation in the presence of goiter was investigated. Data were collected in a series of 4742 consecutive adult patients undergoing general anesthesia. The prevalence of goiter was 6.8%. Fifteen anesthesiologists performed the preoperative airway assessment using standardized guidelines. Seven individual risk factors were correlated with the potential for difficult tracheal intubation. Whenever evidence of goiter or airway pathology was observed, the evaluation was completed by indirect laryngoscopy and radiologic examination to establish the presence of any anatomical deviation. Difficult intubation was defined as inadequate exposure of the glottis by direct laryngoscopy. There was no difference in probability of difficulty in tracheal intubation between patients who presented for thyroidectomy and patients with goiter estimated as a random finding. Statistical analysis revealed an increased risk of difficult intubation amongst goiter patients compared with patients with no evidence of any risk factor (6.8% vs 0.9%, P < 10(-8), relative risk = 7.4). We conclude that goiter, when accompanied by airway deformity, constitutes an aggravating factor for difficult intubation. 相似文献
77.
Michael R. Berman 《应用聚合物科学杂志》1992,45(1):111-117
Darkening of ethylene–tetrafluorethylene (ETFE) films caused by exposure to xenon chloride excimer laser radiation at 308 nm was studied. Darkening was determined to result from a rapid, local heating of the film. The laser-induced heating caused elimination of hydrogen fluoride from the film, leaving a noncrystalline graphitic backbone. A threshold laser fluence for darkening of (205 ± 25) mJ/cm2 was observed. At laser fluences above this threshold the rate of darkening of the ETFE films increased linearly with laser fluence. The rate of darkening was found to decrease as the extent of crosslinking in the polymer sample increased. Observations suggest that low concentrations of monomers in the film might affect the darkening rate. 相似文献
78.
79.
80.
Lee J.B. Woodyatt A.S. Berman M. 《Geoscience and Remote Sensing, IEEE Transactions on》1990,28(3):295-304
High-spectral-resolution remote-sensing data are first transformed so that the noise covariance matrix becomes the identity matrix. Then the principal components transform is applied. This transform is equivalent to the maximum noise fraction transform and is optimal in the sense that it maximizes the signal-to-noise ratio (SNR) in each successive transform component, just as the principal component transform maximizes the data variance in successive components. Application of this transform requires knowledge or an estimate of the noise covariance matrix of the data. The effectiveness of this transform for noise removal is demonstrated in both the spatial and spectral domains. Results that demonstrate the enhancement of geological mapping and detection of alteration mineralogy in data from the Pilbara region of Western Australia, including mapping of the occurrence of pyrophyllite over an extended area, are presented 相似文献