972 resultados para Phase change


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The grain-boundary conductivity (sigma (gb),) of 8-mol%-ytterbiastabilized zirconia increased markedly with heat treatment between 1000 degrees and 1300 degreesC with a slow heating rate (0.1 degreesC/min) before sintering. The extent of the sigma (gb) improvement was the same or larger than that via Al2O3 addition. The heat treatment did not affect the grain-interior conduction when sintered at 1600 degreesC, while Al2O3-derived scavenging significantly did, given the larger increment of total conductivity in the heat-treated sample. The formation of a silicon-containing phase in a discrete form was suggested as a possible route of scavenging the resistive phase from the correlation between average grain size and sigma (gb).

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We investigate the size and power properties of the AH test of evolutionary change. This involves examining whether the size results are sensitive to both the number of individual frequencies estimated and the spectral shape adopted under the null hypothesis. The power tests examine whether the test has good power to detect shifts in both spectral position (variance) and spectral shape (autocovariance structure).

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Purpose: To assess the toxicity and the efficacy of preoperative radiotherapy with continuous infusion 5-fluorouracil (5-FU) for locally advanced adenocarcinoma of the rectum. Methods and Materials: Eligible patients had newly diagnosed localized adenocarcinoma of the rectum within 12 cm of the anal verge, Stage T3-4, and were suitable for curative resection. Eighty-two patients were treated with radiotherapy-50.4 Gy in 28 fractions in 5.6 weeks, given concurrently with continuous infusion 5-FU, using either 96-h/week infusion at 300 mg/m(2)/day or 7-days/week infusion at 225 mg/m(2)/day. Results: The median age was 59 years (range, 27-87), and 67% of patients were male. Pretreatment stages of the rectal cancer were T3, 89% and resectable T4, 11%, with endorectal ultrasound confirmation in 67% of patients. Grade 3 acute toxicity occurred in 5 of 82 patients (6%; 95% confidence interval [CI], 2-14%). Types of surgical resection were anterior resection, 61%; abdominoperineal resection, 35%; and other procedures, 4%. There was no operative mortality. Anastomotic leakage after low anterior resection occurred in 3 of 50 patients (6%; 95% CI, 1-17%). The pathologic complete response rate was 16% (95% CI, 9-26%). Pathologic Stages T2 or less occurred in 51%. Conclusion: Preoperative radiotherapy with continuous infusion 5-FU for locally advanced rectal cancer is a safe regimen, with a significant downstaging effect. It does not seem to lead to a significant increase in serious surgical complications. (C) 2001 Elsevier Science Inc.

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Excessive consumption of alcohol is a serious public health problem. While intensive treatments are suitable for those who are physically dependent on alcohol, they are not cost-effective options for the vast majority of problem drinkers who are not dependent. There is good evidence that brief interventions are effective in reducing overall alcohol consumption, alcohol-related problems, and health-care utilisation among nondependent problem drinkers. Psychologists are in an ideal position to opportunistically detect people who drink excessively and to offer them brief advice to reduce their drinking. In this paper we outline the process involved in providing brief opportunistic screening and intervention for problem drinkers. We also discuss methods that psychologists can employ if a client is not ready to reduce drinking, or is ambivalent about change. Depending on the client's level of motivation to change, psychologists can engage in either an education-clarification approach, a commitment-enhancement approach, or a skills-training approach. Routine engagement in opportunistic intervention is an important public-health approach to reducing alcohol-related harm in the community.

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The adoption of the incorporated form of ownership in preference to partnership is linked to the shift to a more modem organizational archetype in professional firms. Yet existing empirical research offers insufficient insight into the organizational processes of this transformation in different professional arenas. Where ownership and control become separated, there is a clearer theoretical explanation of the implications for the way the firm is run. Where ownership and control remain inside, the firm, however, the consequences are not so clear and have not been well explored. Using survey and interview materials derived from a study of architecture practices, we examine the processes by which differences based on ownership emerge. Then, by drawing on Weberian theories, where they are concerned with professionalization as a project with material and social rewards, we specify more clearly the context for change in professional firms' archetypes. This, we conclude, provides a stronger basis for understanding the change trajectories of firms within professions and comparative organizational analysis between professions.

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This review compiles evidence for an alternative to the classical adenoma-carcinoma sequence in the evolution of colorectal cancer. It is suggested that between 30 and 50% of colorectal cancers are not initiated by mutation of the tumor suppressor gene APC, but through the epigenetic silencing of genes implicated in the control of differentiation, cell cycle control and DNA repair proficiency. The precursor polyps are often characterized by a serrated architecture, and include hyperplastic polyps, admixed polyps and serrated adenomas. The alternative pathway is heterogeneous and may culminate in cancers showing low or high level DNA microsatellite instability (MSI-L and MSI-H, respectively), and in cancers that are microsatellite stable (MSS). Cancers showing DNA MSI may be characterized by an accelerated evolution. Cancers in hereditary non-polyposis colorectal cancer show features of both classical (adenoma and APC mutation) and alternative pathways (rapid evolution, MSI-H and lack of chromosomal instability). (C) 2001 Blackwell Science Asia Pty Ltd.

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From the mid-1970s through the 1980s and into the 1990s, wage inequality and skill differentials in earnings and employment increased sharply in OECD countries. After 1973 and especially in the 1980s, the US experienced a dismal real wage performance for the less skilled. Among the factors singled out by economists as possible major contributors to this development are economic globalisation processes and skill-biased technological change. Although these are most commonly considered as independent influences, after critically outlining views about these factors, this article argues that strong interdependence exists between them. The article then examines potential policy responses to this growing inequality.

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Management are keen to maximize the life span of an information system because of the high cost, organizational disruption, and risk of failure associated with the re-development or replacement of an information system. This research investigates the effects that various factors have on an information system's life span by understanding how the factors affect an information system's stability. The research builds on a previously developed two-stage model of information system change whereby an information system is either in a stable state of evolution in which the information system's functionality is evolving, or in a state of revolution, in which the information system is being replaced because it is not providing the functionality expected by its users. A case study surveyed a number of systems within one organization. The aim was to test whether a relationship existed between the base value of the volatility index (a measure of the stability of an information system) and certain system characteristics. Data relating to some 3000 user change requests covering 40 systems over a 10-year period were obtained. The following factors were hypothesized to have significant associations with the base value of the volatility index: language level (generation of language of construction), system size, system age, and the timing of changes applied to a system. Significant associations were found in the hypothesized directions except that the timing of user changes was not associated with any change in the value of the volatility index. Copyright (C) 2002 John Wiley Sons, Ltd.

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The efficacy of psychological treatments emphasising a self-management approach to chronic pain has been demonstrated by substantial empirical research. Nevertheless, high drop-out and relapse rates and low or unsuccessful engagement in self-management pain rehabilitation programs have prompted the suggestion that people vary in their readiness to adopt a self-management approach to their pain. The Pain Stages of Change Questionnaire (PSOCQ) was developed to assess a patient's readiness to adopt a self-management approach to their chronic pain. Preliminary evidence has supported the PSOCQ's psychometric properties. The current study was designed to further examine the psychometric properties of the PSOCQ, including its reliability, factorial structure and predictive validity. A total of 107 patients with an average age of 36.2 years (SD = 10.63) attending a multi-disciplinary pain management program completed the PSOCQ, the Pain Self-Efficacy Questionnaire (PSEQ) and the West Haven-Yale Multidimensional Pain Inventory (WHYMPI) pre-admission and at discharge from the program. Initial data analysis found inadequate internal consistencies of the precontemplation and action scales of the PSOCQ and a high correlation (r = 0.66, P < 0.01) between the action and maintenance scales. Principal component analysis supported a two-factor structure: 'Contemplation' and 'Engagement'. Subsequent analyses revealed that the PSEQ was a better predictor of treatment outcome than the PSOCQ scales. Discussion centres upon the utility of the PSOCQ in a clinical pain setting in light of the above findings, and a need for further research. (C) 2002 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.

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Recent research in Australia and overseas has suggested that we are witnessing a convergence of men's and women's time on domestic labour activities. But there is disagreement about whether this is due to women reducing their time on housework or men increasing their time on housework. This article addresses these issues using national survey data collected in Australia in 1986, 1993 and 1997. The results show some changes in the proportional responsibilities of men and women in the home with men reporting a greater share of traditional indoor activities. But overall both men and women are spending less time on housework. In particular, women's time on housework has declined by six hours per week since 1986. Hence, while the gender gap between men's and women's involvement in the home is getting smaller, it is not the result of men increasing their share of the load, but is due to the large decline in women's time spent on domestic labour. There is also evidence of change in the relationship. between paid and unpaid work for women. Women's hours of,paid labour had a greater impact on their involvement in domestic labour in 1997 compared to a decade earlier. The article concludes that women's increased labour force involvement in combination with changing patterns and styles, of consumption is leading to some changes in the gender-division:of household labour, but not in the direction anticipated by earlier commentators on the domestic division of labour.

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As a function of temperature, the layered compound K2Na[Ag(CN)213 displays dramatic variations in luminescence thermochromism with major trend changes occurring around 80 K. In order to understand these interesting optical properties, high-resolution neutron diffraction investigations were performed on a polycrystalline sample of this material in the temperature range from 1.5 to 300 K, and previous synchrotron X-ray data of Larochelle et al. (Solid State Commun. 114, 155 (2000)) were reinterpreted. The corresponding significant structural changes were found to be continuous with an anomalous increase of the monoclinic c-lattice parameter with decreasing temperature, associated with slight reorientations of two inequivalent, approximately linear N-C-Ag-C-N units. In the whole temperature range, the crystal structure is monoclinic with the space group C2/m. Based on the structural results, the major luminescence thermochromism changes around 80 K are attributed to the dominance of a back energy transfer process from low- to high-energy excitons at high temperatures. (E) 2002 Elsevier Science (USA).