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Performance Changes (performance + change)
Selected AbstractsAbrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Minjung Shin Abstract The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology,including the size and population of P3HT crystallites,abruptly changes at 140,°C between 5 and 30,min and is then stable up to 120,min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5,min annealing at 140,°C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high. [source] Working and Episodic Memory in HIV Infection, Alcoholism, and Their Comorbidity: Baseline and 1-Year Follow-Up ExaminationsALCOHOLISM, Issue 10 2009Rosemary Fama Background:, Selective memory deficits occur in individuals with human immunodeficiency virus (HIV) infection and those with chronic alcoholism, but the potential compounded effect of these conditions is seldom considered, despite the high prevalence of alcohol use disorders in HIV infection. Methods:, Here, we examined component processes of working and episodic memory in HIV infection and chronic alcoholism (ALC) in 4 subject groups (HIV, ALC, HIV + ALC, and normal controls) at baseline and 1-year follow-up. Accuracy scores, response times, and rate of information processing were assessed with subtests of the computerized neuropsychological test battery, the MicroCog. Results:, Although individuals with either HIV infection or alcoholism generally performed at normal levels, individuals comorbid with HIV infection and alcoholism were impaired relative to controls and to the single diagnosis groups on selective memory processes. Immediate episodic memory was impaired, whereas working memory remained intact. Ability to retain information over time was not impaired in the clinical groups. Little performance change between groups was detected over 1 year. Results could not be explained by amount of alcohol consumed over a lifetime, CD4 cell count, AIDS diagnosis, or HAART medication. Conclusions:, This study provides behavioral support for adverse synergism of HIV infection and chronic alcoholism on brain function and is consistent with neuroimaging reports of compromised hippocampal and associated memory structures related to episodic memory processes in these 2 conditions. [source] Challenges in multisource feedback: intended and unintended outcomesMEDICAL EDUCATION, Issue 6 2007Joan Sargeant Context, Multisource feedback (MSF) is a type of formative assessment intended to guide learning and performance change. However, in earlier research, some doctors questioned its validity and did not use it for improvement, raising questions about its consequential validity (i.e. its ability to produce intended outcomes related to learning and change). The purpose of this qualitative study was to increase understanding of the consequential validity of MSF by exploring how doctors used their feedback and the conditions influencing this use. Methods, We used interviews with open-ended questions. We purposefully recruited volunteer participants from 2 groups of family doctors who participated in a pilot assessment of MSF: those who received high (n = 25) and those who received average/lower (n = 44) scores. Results, Respondents included 12 in the higher- and 16 in the average/lower-scoring groups. Fifteen interpreted their feedback as positive (i.e. confirming current practice) and did not make changes. Thirteen interpreted feedback as negative in 1 or more domains (i.e. not confirming their practice and indicating need for change). Seven reported making changes. The most common changes were in patient and team communication; the least common were in clinical competence. Positive influences upon change included receiving specific feedback consistent with other sources of feedback from credible reviewers who were able to observe the subjects. These reviewers were most frequently patients. Discussion, Findings suggest circumstances that may contribute to low consequential validity of MSF for doctors. Implications for practice include enhancing procedural credibility by ensuring reviewers' ability to observe respective behaviours, enhancing feedback usefulness by increasing its specificity, and considering the use of more objective measures of clinical competence. [source] A review of evaluation outcomes of web-based continuing medical educationMEDICAL EDUCATION, Issue 6 2005Vernon R Curran Introduction, The Internet and worldwide web have expanded opportunities for the provision of a flexible, convenient and interactive form of continuing medical education (CME). Larger numbers of doctors are accessing and using the Internet to locate and seek medical information. It has been suggested that a significant proportion of this usage is directly related to questions that arise from patient care. A variety of Internet technologies are being used to provide both asynchronous and synchronous forms of web-based CME. Various models for designing and facilitating web-based CME learning have also been reported. The purpose of this study was to examine the nature and characteristics of the web-based CME evaluative outcomes reported in the peer-reviewed literature. Methods, A search of Medline was undertaken and the level of evaluative outcomes reported was categorised using Kirkpatrick's model for levels of summative evaluation. Results, The results of this analysis revealed that the majority of evaluative research on web-based CME is based on participant satisfaction data. There was limited research demonstrating performance change in clinical practices and there were no studies reported in the literature that demonstrated that web-based CME was effective in influencing patient or health outcomes. Discussion, The findings suggest an important need to examine in greater detail the nature and characteristics of those web-based learning technologies, environments and systems which are most effective in enhancing practice change and ultimately impacting patient and health outcomes. This is particularly important as the Internet grows in popularity as a medium for knowledge transfer. [source] Monitoring bacterial and archaeal community shifts in a mesophilic anaerobic batch reactor treating a high-strength organic wastewaterFEMS MICROBIOLOGY ECOLOGY, Issue 3 2008Changsoo Lee Abstract Shifts in bacterial and archaeal communities, associated with changes in chemical profiles, were investigated in an anaerobic batch reactor treating dairy-processing wastewater prepared with whey permeate powder. The dynamics of bacterial and archaeal populations were monitored by quantitative real-time PCR and showed good agreement with the process data. A rapid increase in bacterial populations and a high rate of substrate fermentation were observed during the initial period. Growth and regrowth of archaeal populations occurred with biphasic production of methane, corresponding to the diauxic consumption of acetate and propionate. Bacterial community structure was examined by denaturing gel gradient electrophoresis (DGGE) targeting 16S rRNA genes. An Aeromonas -like organism was suggested to be mainly responsible for the rapid fermentation of carbohydrate during the initial period. Several band sequences closely related to the Clostridium species, capable of carbohydrate fermentation, lactate or ethanol fermentation, and/or homoacetogenesis, were also detected. Statistical analyses of the DGGE profiles showed that the bacterial community structure, as well as the process performance, varied with the incubation time. Our results demonstrated that the bacterial community shifted, reflecting the performance changes and, particularly, that a significant community shift corresponded to a considerable process event. This suggested that the diagnosis of an anaerobic digestion process could be possible by monitoring bacterial community shifts. [source] Detecting and classifying delay Data Exceptions on communication networks using rule based algorithmsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2005Tammam Benmusa Abstract Network performance monitoring is essential for managing a network efficiently and for ensuring reliable operation of the network. Monitored network performance changes reflect events in the network, such as faults, significant changes in usage patterns or planned alterations. Network managers are interested in how and when the performance of a network changes; however it is inefficient to analyse all the data resulting from the monitoring operation manually. In this paper a rule based algorithm to automate detection of the changes in one of the network performance parameters, namely delay, is presented and described in detail. The nature of the delay pattern in a commercial communication network was the key issue in developing this algorithm. The approach was tested with monitored delay data generated from three different networks and showed good results. Also, the algorithm was tested with sets of delay data which have been already input to a previously developed detector based on a different approach, and the results between the two detectors are compared. In addition to a noticeable improvement in detection performance, the new approach provides more generality and independency of the source of the delay data, making the approach generally applicable to other networks. Copyright © 2004 John Wiley & Sons, Ltd. [source] Performance prediction of a refrigerating machine using R-407C: the effect of the circulating composition on system performanceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2002P. Haberschill Abstract This article presents a steady-state model of a vapour compression refrigerating machine using a ternary refrigerant mixture R-407C. When using a zeotropic mixture in a refrigerant cycle, the circulating composition does not agree with the composition of the original charged mixture. It is mainly due to the temperature glide and the vapour,liquid slip ratio. As a result of the composition shift and its magnitude, the system performance changes depending on the system design, especially the presence of liquid receiving vessels. In this paper, a method that predicts the circulating composition has been associated to a refrigerating machine model. The results obtained with this model show an enrichment in the most volatile components of about 1% for the circulating composition, which is sufficient to decrease the system performance by about 3%. Factors affecting the overall performance have been investigated. The results show a very strong performance dependence on the refrigerant charge. The COP can decrease by 25% when the refrigerant charge is insufficient. An initial charged composition variation of 2% involves variations of the cooling capacity of about 5%. Furthermore, our model was employed to compare the performance for both R-22 and R-407C. The cooling capacity for R-22 is slightly greater in comparison to R-407C and the COP is almost constant. Copyright © 2002 John Wiley & Sons, Ltd. [source] Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response studyJOURNAL OF SLEEP RESEARCH, Issue 1 2003Gregory Belenky SUMMARY Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n = 18), 5 (n= 16), 7 (n = 16), or 9 h (n = 16) daily time in bed (TIB) for 7 days (restriction/augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed (mean and fastest 10% of responses) on the psychomotor vigilance task (PVT) declined, and PVT lapses (reaction times greater than 500 ms) increased steadily across the 7 days of sleep restriction. In the 7- and 5-h groups speed initially declined, then appeared to stabilize at a reduced level; lapses were increased only in the 5-h group. In the 9-h group, speed and lapses remained at baseline levels. During recovery, PVT speed in the 7- and 5-h groups (and lapses in the 5-h group) remained at the stable, but reduced levels seen during the last days of the experimental phase, with no evidence of recovery. Speed and lapses in the 3-h group recovered rapidly following the first night of recovery sleep; however, recovery was incomplete with speed and lapses stabilizing at a level comparable with the 7- and 5-h groups. Performance in the 9-h group remained at baseline levels during the recovery phase. These results suggest that the brain adapts to chronic sleep restriction. In mild to moderate sleep restriction this adaptation is sufficient to stabilize performance, although at a reduced level. These adaptive changes are hypothesized to restrict brain operational capacity and to persist for several days after normal sleep duration is restored, delaying recovery. [source] Redesigning alkylated diphenylamine antioxidants for modern lubricantsLUBRICATION SCIENCE, Issue 1 2007Vincent J. Gatto This paper describes a new alkylation technology that is very effective at synthesizing structurally different alkylated diphenylamine chemistries relative to those currently available to lubricant formulators. Examples are provided showing how this technology can be used in a practical way to produce a variety of chemically modified nonylated diphenylamine types. One example is also provided illustrating the preparation of a higher molecular weight dodecylated diphenylamine. Engine oil performance data utilizing pressurized differential scanning calorimetry (PDSC), the thermo-oxidation engine oil simulation test, and a bulk oil oxidation test demonstrate that subtle changes in alkylated diphenylamine chemical composition can result in significant oxidation and deposit control performance enhancements or losses. Examples of similar performance responses in industrial oils are demonstrated utilizing PDSC and the rotating pressure vessel oxidation test. These performance changes are directly related to specific structural changes in the modified products. Copyright © 2006 John Wiley & Sons, Ltd. [source] | |||||||||||||