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1.
The neuronal nicotinic synapse in tissue slices of the adrenal medulla was studied with whole-cell patch-clamp. Excitatory postsynaptic currents (EPSCs) were evoked by local field stimulation or occurred spontaneously especially when external [K+] was increased. EPSCs were carried by channels sharing biophysical and pharmacological properties of neuronal-type nicotinic receptors (nAChRs). A single-channel conductance (gamma) of 43-45 pS was found from nonstationary variance analysis of EPSCs. Spontaneous EPSCs were tetrodotoxin-insensitive and Ca(2+)-dependent and occurred in burst-like clusters. Quantal analysis of spontaneous EPSCs gave a quantal size of 20 pA and amplitude histograms were well described by binomial models with low values of quantal content, consistent with a small number of spontaneously active release sites. However, rare large amplitude EPSCs suggest that the total number of sites is higher and that extrajunctional receptors are involved. Our estimates of quantal content and size at the chromaffin cell neuronal nicotinic synapse may be useful in characterizing central neuronal-type nicotinic receptor-mediated cholinergic synaptic transmission. 相似文献
2.
The dynamic and equilibrium swelling behavior of polystyrene microparticles crosslinked with divinyl benzene was investigated in methyl ethyl ketone and cyclohexane. The dynamic studies gave new information about the mechanism of penetrant transport in this polymer. The equilibrium studies were used to determine important parameters of the crosslinked structure of these systems, including the average molecular weight between crosslinks, M?c 相似文献
3.
Two approaches for dealing with “endogenous selection” problems when estimating causal effects are considered. They are principal stratification and selection models. The main goal is to highlight similarities and differences between the two approaches, by investigating the different nature of their parametric hypotheses. The principal stratification approach focuses on information contained in specific subgroups of units. The aim is to produce valid inference conditional on such subgroups, without an a priori extension of the results to the whole population. Selection models, on the contrary, aim at estimating parameters that should be valid for the whole population, as if the data come from random sampling. A simulation study is conducted to show their different performances, with data generating processes coming from either approach. It is also argued that principal stratification is able to suggest alternative identification strategies not always easily translatable into assumptions of a selection model. 相似文献
4.
Interviewed 120 sunbathing and nonsunbathing beachgoers about their health practices, knowledge about skin cancer, moods, and social rewards obtained through sunbathing. Ss also completed personality questionnaires. Data were considered using a theoretical perspective combining aspects of health belief, social influence, social learning, and risk-taking models. Results indicate that sunbathing was related to having a positive attitude toward risk taking, having little knowledge about skin cancer, reporting a relaxed mood, having friends who sunbathe, and engaging in activities related to maintaining a positive physical appearance. Sunscreen use was related to sex, having knowledge about skin cancer, knowing people who have had cancer, and reporting high levels of anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Pope Kenneth S.; Tabachnick Barbara G.; Keith-Spiegel Patricia 《Canadian Metallurgical Quarterly》1987,42(11):993
There is an absence of comprehensive, systematically gathered data concerning psychologists' beliefs about and compliance with ethical principles. Furthermore, we know little about which resources are valued as effective in guiding appropriate behavior. Survey data were collected from 456 APA Division 29 members regarding the degree to which they engaged in each of 83 behaviors and the degree to which they considered each behavior to be ethical. These data were categorized and examined in terms of five principles derived from the Hippocratic oath (avoiding harm, competence, avoiding exploitation, respect, and confidentiality) as well as two additional principles (informed consent; social equity and justice). Twelve of the behaviors were very difficult for participants to evaluate on the basis of ethics. Seven of the 83 behaviors were practiced by over 90% of the participants; 16 by fewer than 10%. Colleagues, the APA Ethical Principles, and internship training were rated as the most helpful resources in guiding behavior; state and federal laws, published research, and local ethics committees were rated least helpful. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
The diffusion coefficient of the cationic dye Anilana Red BL in the anionically modified polyester fiber Dilana has been calculated regarding a general diffusion-immobilization model. In the model the mobile species are distinguished from the immobilized ones. In computations of Sand's equation and experimentally determined sorption isotherm of the dye in the fiber, the rate-of-dyeing curve and the concentration profiles of the dye in the same fiber were employed. The diffusion coefficient of the mobile species of Anilana Red BL in the fiber is two orders of magnitude higher than the average diffusion coefficient obtained from Hill's equation and the apparent diffusion coefficient calculated by the Boltzmann–Matano method. 相似文献
7.
Testing the Ortega hypothesis: Facts and artifacts 总被引:2,自引:0,他引:2
We examine the assumptions and data base used by researchers who have tested the Ortega hypothesis. We find that the assumptions are not supported by the data and that the data are faulty. We conclude that the results are artifactual. We recommend that any policy implemented on the basis of this research be suspended. 相似文献
8.
Thompson Robert J.; Gil Karen M.; Keith Barbara R.; Gustafson Kathryn E.; George Linda K.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1994,62(4):856
Rates of poor psychological adjustment of children with sickle cell disease remained relatively constant over initial and follow-up assessment points. 50 children (aged 7–12 yrs) and their mothers completed the initial protocol. 30 children completed the follow-up plus 5 additional children and their mothers. These Ss were aged 7–24 yrs at follow-up. With initial levels of adjustment controlled, children's strategies for coping with pain accounted for a significant increment in child-reported symptoms and mother-reported internalizing behavior problems at follow-up beyond the contribution of illness and demographic parameters and follow-up interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Observed visuographic and paranoid symptomatology in 26 dentists (mean age, 49.9 yrs) with elevated mercury levels. Neuropsychological functions were assessed with measures such as the Wechsler Adult Intelligence Scale (WAIS), the Bender-Gestalt Test, and the SCL-90 (Revised). Although the observed changes were mild, their presence suggests subtoxic hazards associated with dental practice and underscore a continual need for maintaining mercury hygiene. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Barbara K. Reck Robert B. Gordon 《JOM Journal of the Minerals, Metals and Materials Society》2008,60(7):55-59
Nickel and chromium are essential ingredients in alloys increasingly important for energy-efficient, environmentally friendly
modern technology. Quantitative assessment of the flows of these metals through the world economy from resource extraction
to final disposal informs resource policy, energy planning, environmental science, and waste management. This article summarizes
the worldwide technological cycles of nickel and chromium in 2000. Stainless steel is the major use of these metals, but they
serve numerous other special needs, as in superalloys for high-temperature service, as plating materials, and in coinage.
Because they are used primarily in alloys, novel recycling issues arise as their use becomes more widespread.
“... the great New York and St. Louis double track, nickel plated railroad...”
— Norwalk, Ohio, Chronicle 10 March 1881 announces arrival of surveyors for the future Nickel Plate Railway
“Later [1911] I formed an alloy of Iron and Chromium, which showed remarkable resistance to rust and tarnish ... [It was]
rediscovered by an Englishman named Brearley, in 1914.”
—Elwood Haynes to Stephen F. Roberts, 17 January 1925 相似文献