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61.
Fast-2, a membrane mutant of Paramecium aurelia, is due to a single-gene mutation and has behavioral abnormalities. Intracellular recordings through changes of external solutions were made. The mutant membrane hyperpolarized when it encountered solutions with low K+ concentration. This hyperpolarization and other associated activities were best observed in Ca- or Na-solutions devoid of K+. Membrane potential was plotted against the concentration of K+ (0.5 to 16 mM) in solutions of fixed Na+ or Ca++ concentration. The slopes of the curves for the mutant membrane were steeper than those for the wild type at the lower concentrations of K+. Inclusion of 2 mM tetraethylammonium chloride (TEA-Cl) counteracted the mutational effects. Spontaneous action potentials in Ba-solution and the electrically evoked action potentials in various solutions are normal in this mutant. We conclude that the resting permeability to K+ relative to the permeabilities to Na+ and Ca++ has been increased by the mutation.  相似文献   
62.
63.
The collection efficiency (CE) of the aerosol mass spectrometer (AMS) for chamber-generated secondary organic aerosol (SOA) at elevated mass concentrations (range: 19–207 μg m?3; average: 64 μg m?3) and under dry conditions was investigated by comparing AMS measurements to scanning mobility particle sizer (SMPS), Sunset semi-continuous carbon monitor (Sunset), and gravimetric filter measurements. While SMPS and Sunset measurements are consistent with gravimetric filter measurements throughout a series of reactions with varying parent hydrocarbon/oxidant combinations, AMS CE values were highly variable ranging from unity to <15%. The majority of mass discrepancy reflected by low CE values does not appear to be due to particle losses either in the aerodynamic lens system or in the vacuum chamber as the contributions of these mechanisms to CE are low and negligible, respectively. As a result, the largest contribution to CE in the case of chamber-generated SOA appears to be due to particle bounce at the vaporizer surface before volatilization, which is consistent with earlier studies that have investigated the CE of ambient and select laboratory-generated particles. CE values obtained throughout the series of reactions conducted here are also well correlated with the f 44/f 57 ratio, thereby indicating both that the composition of the organic fraction has an important impact on the CE of chamber-generated SOA and that this effect may be linked to the extent to which the organic fraction is oxidized.

Copyright 2013 American Association for Aerosol Research  相似文献   
64.
The aim of this study was to examine the nature of the relationship between attentional dysfunction and social competence deficits in patients with schizophrenia. Attentional functioning, social perception, and social competence were assessed in 56 inpatients. Measures of vigilance and span of apprehension were administered to assess attentional functioning. Social perception was assessed with an audiovisual measure of affect recognition. Social competence was rated from a role-play task. Span of apprehension and auditory vigilance emerged as specific predictors of social competence. Affect recognition was tested as a mediator and a moderator of the relationship between attentional dysfunction and social competence. Affect recognition was found to moderate the relationship between span of apprehension and social competence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
65.
Intensive insulin therapy (IIT) and tight glycaemic control (TGC), particularly in intensive care unit (ICU), are the subjects of increasing and controversial debate in recent years. Model-based TGC has shown potential in delivering safe and tight glycaemic management, all the while limiting hypoglycaemia. A comprehensive, more physiologically relevant Intensive Control Insulin-Nutrition-Glucose (ICING) model is presented and validated using data from critically ill patients. Two existing glucose-insulin models are reviewed and formed the basis for the ICING model. Model limitations are discussed with respect to relevant physiology, pharmacodynamics and TGC practicality. Model identifiability issues are carefully considered for clinical settings. This article also contains significant reference to relevant physiology and clinical literature, as well as some references to the modeling efforts in this field. Identification of critical constant population parameters was performed in two stages, thus addressing model identifiability issues. Model predictive performance is the primary factor for optimizing population parameter values. The use of population values are necessary due to the limited clinical data available at the bedside in the clinical control scenario. Insulin sensitivity, S(I), the only dynamic, time-varying parameter, is identified hourly for each individual. All population parameters are justified physiologically and with respect to values reported in the clinical literature. A parameter sensitivity study confirms the validity of limiting time-varying parameters to S(I) only, as well as the choices for the population parameters. The ICING model achieves median fitting error of <1% over data from 173 patients (N=42,941 h in total) who received insulin while in the ICU and stayed for ≥ 72 h. Most importantly, the median per-patient 1-h ahead prediction error is a very low 2.80% [IQR 1.18, 6.41%]. It is significant that the 75th percentile prediction error is within the lower bound of typical glucometer measurement errors of 7-12%. These results confirm that the ICING model is suitable for developing model-based insulin therapies, and capable of delivering real-time model-based TGC with a very tight prediction error range. Finally, the detailed examination and discussion of issues surrounding model-based TGC and existing glucose-insulin models render this article a mini-review of the state of model-based TGC in critical care.  相似文献   
66.
The Bookmark method for setting cut-scores was used to re-set the cut-score for the Canadian Forces Firefighter Physical Fitness Maintenance Evaluation (FF PFME). The time required to complete 10 tasks that together simulate a first-response firefighting emergency was accepted as a measure of work capacity. A panel of 25 Canadian Forces firefighter supervisors set cut-scores in three rounds. Each round involved independent evaluation of nine video work samples, where the times systematically increased from 400 seconds to 560 seconds. Results for Round 1 were discussed before moving to Round 2 and results for Round 2 were discussed before moving to Round 3. Accounting for the variability among panel members at the end of Round 3, a cut-score of 481 seconds (mean Round 3 plus 2 SEM) was recommended. Firefighters who complete the FF PFME in 481 seconds or less have the physical capacity to complete first-response firefighting work.  相似文献   
67.
The speech of some schizophrenia patients becomes markedly more disordered when negative affect is aroused. The authors tested associations between affective reactivity of speech and responsiveness and inhibition on an acoustic startle task in a sample of 27 outpatients. Patients whose language was reactive to negative affect showed significantly higher initial startle amplitudes than those whose language was not reactive. However, they also showed greater habituation to repeated startle stimuli over trials, even after differences in initial amplitudes were controlled statistically. These findings suggest that affective reactivity of speech is associated with higher initial startle responsiveness but also with greater habituation and, conversely, that patients who are relatively nonreactive to excitatory affective and sensory stimuli are also less reactive to inhibitory input. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
68.
Expression of the single mouse TSH beta gene gives rise to multiple mRNAs, and we have previously shown that in vitro, one of these mRNAs gives rise to a novel TSH beta-presubunit due to initiation of translation at an in-frame start site unique to this mRNA which is up-stream of the normal start site. The novel presubunit contains a 17-amino acid NH2-terminal extension sequence compared to the normal presubunit. Although this extension sequence does not have the characteristics of a normal signal sequence, the novel TSH beta-presubunit was processed in vitro by microsomal membranes. In this study we have examined the translation product of this mRNA in intact cells and whether in vivo it gives rise to a processed secreted TSH beta-subunit that has an NH2-terminal sequence different from that of the established TSH beta-subunit. Firstly, mRNAs encoding alpha-presubunit and either the normal or novel TSH beta-presubunit were microinjected into Xenopus oocytes, and it was found that immunoprecipitable TSH dimer was secreted into the medium regardless of the mRNA used for TSH beta-subunit synthesis. However, less TSH was obtained when the TSH beta-subunit was derived from the extended TSH beta-presubunit. Secondly, when COS cells were transiently transfected with plasmids expressing alpha-presubunit and either the normal or novel TSH beta-presubunit, secreted TSH was obtained when the TSH beta-subunit was derived from either presubunit. TSH dimer was also obtained when the TSH beta-presubunit was derived from a mRNA encoding the extended presubunit in which the down-stream AUG had been eliminated by site-specific mutagenesis. This demonstrated that the up-stream translation start site was used in the intact cell and that secreted TSH beta-subunit was derived from the extended presubunit and not from normal presubunit resulting from translational readthrough to the down-stream AUG. When secreted TSH beta-subunits derived from the normal and extended TSH beta-presubunits were digested with endoproteinase LysC, the NH2-terminal fragments were similar in size, suggesting that the NH2-terminal extension had little if any effect on the site of cleavage by signal peptidase. Our data, therefore, demonstrate that the longer TSH beta-presubunit is synthesized in vivo and strongly suggest that it is processed in the intact cell to give a mature secreted TSH beta-subunit indistinguishable from that derived from the normal TSH beta-presubunit.  相似文献   
69.

The formation of secondary organic aerosol (SOA) from reactions of O 3 with g -pinene, an exocyclic monoterpene prominent in the ambient atmosphere, was studied in an environmental chamber using a thermal desorption particle beam mass spectrometer for chemical analysis and a scanning mobility particle sizer for aerosol yield measurements. Potential reaction pathways for SOA formation were investigated in a series of experiments conducted using various scavengers for stabilized Criegee intermediates (SCI) and OH radicals, both of which are formed in the reaction. The major particulate products were compounds less volatile than pinic acid, a low-volatility dicarboxylic acid that was identified but was a minor component of the aerosol. The aerosol mass spectrum and yield were relatively insensitive to the identity of the SCI scavenger, indicating that association reactions of scavengers with SCI were not important in SOA formation. The mass spectrum of the aerosol also did not depend on the identity of the OH radical scavenger. SOA yields, on the other hand, were significantly larger when cyclohexane was used as an OH radical scavenger, compared to those measured for reactions conducted using alcohols or aldehydes. This dependence indicates that radical pathways play a major role in SOA formation in this reaction. Furthermore, the results show that reaction of OH radicals with scavengers used in laboratory studies can perturb the radical chemistry in such a way as to significantly impact SOA yields. We propose that this effect is due to increases in the ratio [hydroperoxy radicals]/[organic peroxy radicals] when alcohols or aldehydes are used as OH radical scavengers. This apparently enhances the rate of reaction of hydroperoxy radicals with key radical intermediates in SOA formation, effectively short-circuiting the reaction system into pathways leading to more volatile products.  相似文献   
70.
Data relating to variations in hem lengths (presented in Part I) are further assessed in the context of a range of economic indicators. The results indicate, firstly, that the pace of fashion change has not been notably affected by changes in a variety of economic indicators and, secondly, that, contrary to popular mythology, hem lengths do not appear to have risen and fallen in unison with changes in the economy.  相似文献   
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