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11.
The complementarity of two renewable energy sources, namely hydro and wind, is investigated. We consider the diversification effect of wind power to reduce the risk of water inflow shortages, an important energy security concern for hydropower-based economic zones (e.g. Québec and Norway). Our risk measure is based on the probability of a production deficit, in a manner akin to the value-at-risk, simulation analysis of financial portfolios. We examine whether the risk level of a mixed hydro-and-wind portfolio of generating assets improves on the risk of an all-hydro portfolio, by relaxing the dependence on water inflows and attenuating the impact of droughts. Copulas are used to model the dependence between the two sources of energy. The data considered, over the period 1958–2003, are for the province of Québec, which possesses large hydro and wind resources. 相似文献
12.
Abstract. Past research indicates that expectations play a crucial role in the final satisfaction of users of information systems (IS). This includes expectations regarding the skill levels exhibited by the providers of the IS services and products. Typically, the expectations are examined as gaps from perceived performance or as gaps from realistic expectations. The interaction of these gaps has not been thoroughly explored in past research, although recent theories anticipate both gaps are crucial in meeting the desires of the users. A matched pair sample of IS users and IS providers is used to collect data on expected skill levels and perceived delivery of the skills demanded. Gaps, both between these two stakeholder groups regarding expectations and within the user group regarding perceived delivery, are found to impact user satisfaction in a two-way analysis. The results indicate that expectations should be managed to higher levels and commonly understood across the user and provider groups. 相似文献
13.
Russell Jennifer J.; Moskowitz D. S.; Zuroff David C.; Sookman Debbie; Paris Joel 《Canadian Metallurgical Quarterly》2007,116(3):578
This study examined both mean levels and intraindividual variability in the mood and interpersonal behavior of individuals with borderline personality disorder (BPD) and nonclinical control participants over a 20-day event-contingent recording period. Individuals in the BPD group experienced more unpleasantly valenced affect and were less dominant, more submissive, more quarrelsome, and more extreme in overall levels of behavior than control participants. In addition to these mean-level differences, individuals with BPD also reported more intraindividual variability in overall affect valence and in pleasantly valenced affect; displayed greater variability in dominant, quarrelsome, and agreeable behaviors; and exhibited an increased tendency to "spin" among interpersonal behaviors relative to nonclinical control participants. The findings document behavioral and affective manifestations of BPD in the context of naturally occurring interpersonal situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
Virginia Hamilton Youling Yuan Debbie A Rigney Betsy M Chesnutt Aaron D Puckett Joo L Ong Yunzhi Yang Warren O Haggard Steven H Elder Joel D Bumgardner 《Polymer International》2007,56(5):641-647
Chitosan has been widely researched for bone tissue and implant applications. While initial results are promising, there are inconsistent reports regarding the biological responses. This may be due to inadequate evaluation of chitosan material properties. This study evaluated normal human osteoblast precursor cell attachment and proliferation on a series of well‐characterized chitosan films. The chitosan films exhibited a range of properties: 76–96% degree of de‐acetylation (DDA), 2400–8200 kDa viscosity‐average molecular weight, 62–90° contact angle, 0.24–2.46% residual ash, 5.3–287 µg cm?2 residual protein and 23–40% crystallinity. There was no trend or correlation between DDA, crystallinity, contact angle, molecular weight, residual ash or protein content and the attachment or growth of bone cells on chitosan films. All films supported higher levels of bone cell proliferation than tissue culture plastic, which supports the general hypothesis that chitosans are osteocompatible. The 78 and 92% DDA chitosan films supported the most cell proliferation, approximately 16 times that of tissue culture plastic controls, but no chitosan physiochemical property correlated with the increased cell growth. The lack of correlation is hindered since more than one physiochemical property changed for each chitosan material. Data do indicate that there may be much variability in chitosan materials, and this variability may make understanding and comparing biological performance of chitosan materials difficult. These results highlight the need for systematic characterizations of chitosan materials for predictable biomedical applications. Copyright © 2006 Society of Chemical Industry 相似文献
15.
This study used molecular methods to measure concentrations of four enteric viruses (adenovirus, enterovirus, norovirus GI, and norovirus GII) and fecal source tracking markers (human, ruminant, and pig Bacteroidales) in land-based runoff from 22 tropical streams on O'ahu, Hawai'i. Each stream was sampled twice in the morning and afternoon during dry weather. Viruses and human Bacteroidales were widespread in the streams. Watershed septic tank densities were positively associated with higher occurrence of human Bacteroidales and norovirus. There were no associations between occurrence of viruses and fecal indicator concentrations. Virus concentrations and previously reported culturable Salmonella and Campylobacter were used as inputs to a quantitative microbial risk assessment (QMRA) model to estimate the risk of acquiring gastrointestinal (GI) illness from swimming in tropical marine waters adjacent to discharging streams. Monte Carlo methods were used to incorporate uncertainties in the dilution of stream discharge with seawater, swimmer ingestion volumes, pathogen concentrations, and dose-response parameters into the model. Median GI illness risk to swimmers from exposure to coastal waters adjacent to the 22 streams ranged from 0 to 21/1000. GI illness risks from viral exposures were generally orders of magnitude greater than bacterial exposures. Swimming adjacent to streams positive for norovirus or adenovirus resulted in the highest risks. The median risk adjacent to each stream was positively, significantly correlated to the concentration of Clostridium perfringens in the stream. Although a number of important assumptions were made to complete the QMRA, results suggest land-based runoff in the tropics as a potential source of GI illness risk, with pathogens coming from both human and nonhuman nonpoint sources including septic tanks. 相似文献
16.
Through development of a team of Departmental Safety Advisors trained as generalists and supported by subject area experts, the campus community receives efficient, accurate, and personalized help in implementing the safety programs required of the university. The on-call program helps to solve problems and answer questions in a timely manner. The e-mail distribution of on-call information keeps the staff at EH&S informed about what is happening on campus and gives us the opportunity to be proactive problem solvers.Ongoing training of the DSAs, twice-monthly operations meetings, and e-mail keep the lines of communication open between the director and staff and among the staff. The staff feels as though it knows what is going on in the larger scheme of things and that its concerns are respected.The program is continuously improved by evaluating workload, benchmarking with other, similar universities, and feedback from clients. 相似文献
17.
Ruffolo Jessica Somerville; Javorsky Debbie J.; Tremont Geoffrey; Westervelt Holly James; Stern Robert A. 《Canadian Metallurgical Quarterly》2001,13(3):299
The Rey-Osterrieth Complex Figure (ROCF) is commonly used to assess visuospatial skills, visuoconstruction, visual memory, and executive functioning. Two different methods are traditionally used to record the order in which the figure is drawn: the flowchart method and the pen-switching method. Although it has been suggested that pen switching may interfere with performance, to date no research has been conducted to assess whether ROCF performance significantly differs due to administration method. As part of routine neuropsychological evaluation, 100 inpatients and outpatients were randomly assigned to either method. Using the Boston Qualitative Scoring System and the traditional 36-point scoring method, the authors unexpectedly found that the pen-switching group generally performed better than the flowchart group, and productions drawn with pen switching were also significantly faster to score. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
Mullen Brian; Futrell David; Stairs Debbie; Tice Dianne M.; Baumeister Roy F.; Dawson Kathryn E.; Riordan Catherine A.; Radloff Christine E.; Goethals George R.; Kennedy John G.; Rosenfeld Paul 《Canadian Metallurgical Quarterly》1986,51(2):291
Two studies examined the association between newscasters' facial expressions and the voting behavior of viewers. In Exp I, with 45 undergraduates, the facial expressions exhibited by network newscasters while referring to the 1984 presidential candidates prior to the election were investigated. Results indicate that 1 of the 3 newscasters exhibited significantly more positive facial expressions when referring to Reagan than when referring to Mondale. In Exp II, a telephone survey of approximately 200 individuals was conducted to determine whether voting behavior was associated with the nightly news program watched. It was found that voters who regularly watched the newscaster who exhibited the biased facial expressions were significantly more likely to vote for the candidate that the newscaster had smiled upon. Three explanations for the results are discussed: (1) Viewing the newscasters' biased facial expressions caused the viewers' voting preferences; (2) the viewers' voting preferences determined their viewing of biased newscasters' facial expressions; or (3) some other variable accounted for the findings. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Debbie Epstein 《Pedagogy, Culture & Society》1993,1(3):317-334
This paper is organised around three possible meanings that can be given to the question 'Too small to notice?' in relation to racism and anti-racism in the early years of schooling (up to the age of eight). Firstly, are young children too small to have notice taken of their serious concerns and questions? Secondly, are young children too small to notice and/or engage with racism and difference? And thirdly, is racism too small a problem in predominantly white early years contexts? Using anti-racist education as a case study, the paper argues that dominant constructions of childhood and discourses of developmental psychology make it difficult to undertake education for social justice in the early years of schooling. 相似文献
20.
Lefcourt Herbert M.; Miller Rickey S.; Ware Edward E.; Sherk Debbie 《Canadian Metallurgical Quarterly》1981,41(2):357
In the search for moderators of negative life events, locus of control (LOC) has been thought to be one of the more potentially important personality variables. Recent research has substantiated this hypothesis to a limited degree. The present 3 experiments with 216 undergraduates presents stronger indications for the utility of variables. LOC measures (Rotter's Internal–External LOC Scale) interacted with recalled negative life events in predicting mood states that were assessed weekly over a period of several weeks. Multiple regression analyses indicated that negative life events that had occurred during the high school years had a lingering effect on the current mood states of the more external Ss. On the other hand, more recent negative life events resulted in mood disturbances for all Ss regardless of LOC scores, although externals were equally distraught in the absence of negative events. Multiple correlations between negative life events, LOC, and mood scores attained sizable magnitudes. Positive life events, on the other hand, had relatively slight effects on subsequent mood disturbance. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献