Spin coating over topography

A model for predicting film thickness profiles around topographical features during spin coating is presented. This model is applicable to features of arbitrary geometry in the two lateral dimensions. This generally permits study of the planarization of real device structures, including both isolated and neighboring features, with any orientation with respect to the wafer center. Predictions from this model agree qualitatively with measured thin-film profiles from interferograms taken during spinning. Phenomena such as pile-up and wakes result from interactions between surface tension and other driving forces in the flow     

Children's beliefs about drinking

This paper reports the results of a study in which age (grade level), racial/ethnic, and gender differences in beliefs and perceived norms about drinking were examined in a multi-ethnic urban sample of 4th through 7th grade children. Results showed that older children held beliefs and perceived norms that were more favorable toward drinking than younger children. The major difference between older and younger children lay in their differential estimates of the likelihood of certain consequences occurring and not in their evaluation of these consequences of drinking. Further, older children not only displayed less motivation to comply with their parents and greater motivation to comply with their peers, but they also perceived their parents, as well as their peers, as less disapproving of drinking than did younger children. There were few gender or race/ethnicity differences at these ages in children's beliefs and perceived norms about drinking.     

Hysteresis effects with ZrO2 oxygen sensors exposed to non-equilibrium oxygen-hydrocarbon mixtures

Hysteresis effects are reported for ZrO₂ oxygen sensors exposed to non-equilibrium oxygen/hydrocarbon gas mixtures. With oxygen/toluene at 800° C, voltage-composition curves differ following composition changes (a) from excess oxygen to excess toluene and (b) from excess toluene to excess oxygen. A catalysis model is developed to account for this behaviour: the Thiele modulus of the catalyst/electrode is presumed to differ under (a) net oxidizing and (b) net reducing conditions. Large scale voltage fluctuations, sometimes exceeding 400 mV, were observed in experiments with oxygen/isobutane mixtures at 600° C. This behaviour is analysed in terms of a kinetic model involving stochastic variations of relative mass transfer coefficients of oxygen and isobutane.     

橡胶添加剂苯并呋咱-1-氧化物

普遍称为Ｂｅｎｚｏｆｕｒｏｘａｎ（ＢＦＯ）的苯并呋咱－１－氧化物已证明能降低填充炭黑的硫化胶的滞后损失３０％以上。ＢＦＯ大概能促进弹性体和炭黑之间的键合，导致硫化胶“佩恩效应”降低。ＢＦＯ在母炼胶混炼期间于不同温度下加入。为了最大限度地降低滞后损失，需要高温混炼，而且采用高比表面积的炭黑会更有效。镍盐会改善ＢＦＯ和弹性体／炭黑间的反应。     

Gingival recession and exposure of barrier membrane: effect on guided tissue regeneration of Class II furcation defects

The purpose of the present study was to evaluate the effect of barrier membrane exposure on the success of guided tissue regeneration in Class II furcation defects. Twenty-six subjects with mandibular Class II furcation defects received initial periodontal therapy followed by guided tissue regeneration surgery. The membrane was placed and the flaps were repositioned so that the membrane was totally submerged. Membranes were removed 4 to 6 weeks later, at which time the extent of their exposure was recorded. An overall improvement in all clinical parameters was observed for all subjects 1 year after surgery. Half of the patients had experienced no membrane exposure, while the other 13 subjects had experienced mild to pronounced exposure; both groups showed similar improvement in all clinical and surgical parameters. In light of the comparable results obtained in exposed sites, and the anatomic difficulties sometimes encountered in covering a membrane completely, in some of these cases the membrane may be left only partially submerged. This approach will allow for tighter occlusal "seal" of the tooth-membrane interface and preservation of the keratinized gingiva.     

Setting optimal production lot sizes and planned lead times in a job shop

In this research, we model a job shop that produces a set of discrete parts in a make-to-stock setting. The intent of the research is to develop a planning model to determine the optimal tactical policies that minimise the relevant manufacturing costs subject to workload variability and capacity limits. We consider two tactical decisions, namely the production lot size for each part and the planned lead time for each work station. We model the relevant manufacturing costs, entailing production overtime costs and inventory-related costs, as functions of these tactical decisions. We formulate a non-linear optimisation model and implement it in the Excel spreadsheet. We test the model with actual factory data from our research sponsor. The results are consistent with our intuition and demonstrate the potential value from jointly optimising over these tactical policies.     

What is the best method of surgical training?: A report of America's leading senior surgeons

OBJECTIVES: To characterize the career choices and developments made by leading senior surgeons in this country and to examine hypothetically whether application of a short tracking program would have hindered their career decisions. DESIGN: A survey pertaining to each surgeon's career, decisions, and opinions concerning surgical training. SETTING AND PARTICIPANTS: Senior surgeons of regional and national surgical societies. MAIN OUTCOME MEASURE: Survey responses. RESULTS: A total of 352 surveys (41.4%) were received. Respondents answered that the most common reasons for choosing a specialty were role models or mentors (56%), research (51%), and available patient population (23%). The 2 most common stages in a career at which the respondents became interested in a specialty, or an area of expertise, were at the junior residency level (when the specialty was chosen) and at the assistant professor level (when a more specific topic within the specialty was chosen). The most common stage at which the group believed they acquired their expertise was also at the assistant professor level. Seventy-one percent of respondents believed broad training was superior to a short tracking system, although none had participated in shortened surgical training. CONCLUSIONS: Most leading senior surgeons in this country still believe that broad surgical training is superior and should be maintained. Because career specialties in this surveyed group were generally chosen in early residency, a hypothetical application of the short tracking system would have still allowed for these important decisions to be made. Also, it seems likely that specialty and career development would not have been hindered because "expertization" mostly occurred after training was completed. Regardless of training method, a role model or mentor seems most important in career choices and developments.     

Human immunodeficiency virus infection, Part II

The acceptance of highly active antiretroviral therapy (HAART) among patients and health care providers has had a dramatic impact on the epidemiology and clinical characteristics of many opportunistic infections associated with human immunodeficiency virus (HIV). Previously intractable opportunistic infections and syndromes are now far less common. In addition, effective antibiotic prophylactic therapies have had a profound impact on the risk of patients developing particular infections and on the incidence of these infections overall. Most notable among these are Pneumocystis carinii, disseminated Mycobacterium avium complex, tuberculosis, and toxoplasmosis. Nevertheless, infections continue to cause significant morbidity and mortality among patients who are infected with HIV. The role of HAART in many clinical situations is unquestioned. Compelling data from clinical trials support the use of these therapies during pregnancy to prevent perinatal transmission of HIV. HAART is also recommended for health care workers who have had a "significant" exposure to the blood of an HIV-infected patient. Both of these situations are discussed in detail in this article. In addition, although more controversial, increasing evidence supports the use of HAART during the acute HIV seroconversion syndrome. An "immune reconstitution syndrome" has been newly described for patients in the early phases of treatment with HAART who develop tuberculosis, M avium complex, and cytomegalovirus disease. Accumulating data support the use of hydroxyurea, an agent with a long history in the field of myeloproliferative disorders, for the treatment of HIV. Newer agents, particularly abacavir and adefovir dipivoxil, are available through expanded access protocols, and their roles are being defined and clarified.     

Home use of a functional electrical stimulation system for standing and mobility in adolescents with spinal cord injury

OBJECTIVE: Functional electrical stimulation (FES) is a technology that may allow some patients with spinal cord injury (SCI) to integrate standing and upright mobility with wheelchair mobility. The purpose of this study was to document the patterns of home and community use of a FES system for standing and mobility. DESIGN: A telephone questionnaire was administered every 1 to 4 weeks for a minimum of 1 year. An interview was given at the end of the study to probe the motivators and barriers to home use. SETTING: Training for use of the FES system was performed in an inpatient pediatric rehabilitation setting. Data collection began after the subjects were discharged to home. PARTICIPANTS: Five adolescents with complete, thoracic-level SCI. INTERVENTION: Subjects participated in a program of FES exercise followed by training in basic mobility skills such as standing transfers, maneuvering, level ambulation, one-handed and reaching activities, and stair ascent/descent. MAIN OUTCOME MEASURE: The frequency with which the FES system was used at home and the activities for which it was utilized were documented. Motivators and barriers to FES home use were examined. RESULTS: Subjects donned the FES system on the average once every 3 to 4 days. Between 51% and 84% of the times donned, the system was used for exercise. The remaining times it was used for standing activities, most commonly reaching, one-handed tasks, and standing for exercise. "Motivators" included being able to do things that would otherwise be difficult, perceiving a healthful benefit or a sense of well-being from standing and exercise, and feeling an obligation to stand as a participant in a research study. "Barriers" to FES use included not finding time to use the system, having difficulty seeing opportunities to stand, and being reluctant to wear the FES system all day.