Knowledge-based manufacturability assessment: an object-oriented approach

To help the achievement of integrated product and process development, there is a need for tools that can assist designers in creating manufacturable parts with less design routines and tryouts. This paper presents a systematic approach to developing automated manufacturability assessment tools by identifying the functional and informational requirements and proposing an assessment model. The work presented in this paper includes: (1) identification of characteristics and tasks of design for the die-casting process; (2) determination of functional and informational requirements for automatic manufacturability assessment; (3) formalization and modularization of assessment knowledge; and (4) modeling of product definition data to support the assessment. Object-oriented techniques are employed to model the assessment knowledge and manage the complicated and diverse types of product definition data by taking advantage of data abstraction, modularity, inherent concurrence, and the concept of encapsulation and extendibility.     

An autosomal genomic scan for loci linked to prediabetic phenotypes in Pima Indians

Type 2 diabetes mellitus is a common chronic disease that is thought to have a substantial genetic basis. Identification of the genes responsible has been hampered by the complex nature of the syndrome. Abnormalities in insulin secretion and insulin action predict the development of type 2 diabetes and are, themselves, highly heritable traits. Since fewer genes may contribute to these precursors of type 2 diabetes than to the overall syndrome, such genes may be easier to identify. We, therefore, undertook an autosomal genomic scan to identify loci linked to prediabetic traits in Pima Indians, a population with a high prevalence of type 2 diabetes. 363 nondiabetic Pima Indians were genotyped at 516 polymorphic microsatellite markers on all 22 autosomes. Linkage analyses were performed using three methods (single-marker, nonparametric multipoint [MAPMAKER/SIBS], and variance components multipoint). These analyses provided evidence for linkage at several chromosomal regions, including 3q21-24 linked to fasting plasma insulin concentration and in vivo insulin action, 4p15-q12 linked to fasting plasma insulin concentration, 9q21 linked to 2-h insulin concentration during oral glucose tolerance testing, and 22q12-13 linked to fasting plasma glucose concentration. These results suggest loci that may harbor genes contributing to type 2 diabetes in Pima Indians. None of the linkages exceeded a LOD score of 3.6 (a 5% probability of occurring in a genome-wide scan). These findings must, therefore, be considered tentative until extended in this population or replicated in others.     

Mechanisms underlying changes of tetanic [Ca2+]i and force in skeletal muscle

Force development in skeletal muscle is driven by an increase in myoplasmic free [Ca2+]i ([Ca2+]i) due to Ca2+ release from the sarcoplasmic reticulum (SR). The magnitude of [Ca2+]i elevation during stimulation depends on: (a) the rate of Ca2+ release from the SR; (b) the rate of Ca2+ uptake by the SR; and (c) the myoplasmic Ca2+ buffering. We have used fluorescent Ca2+ indicators to measure [Ca2+]i in intact, single fibres from mouse and Xenopus muscles under conditions where one or more of the above factors are changed. The following interventions resulted in increased tetanic [Ca2+]i: beta-adrenergic stimulation, which potentiates the SR Ca2+ release; application of 2.5-di(tert-butyl)-1,4-benzohydroquinone, which inhibits SR Ca2+ pumps; application of caffeine, which facilitates SR Ca2+ release and inhibits SR Ca2+ uptake; early fatigue, where the rate of SR Ca2+ uptake is reduced; acidosis, which reduces both the myoplasmic Ca2+ buffering and the rate of SR Ca2+ uptake. Reduced tetanic [Ca2+]i was observed in late fatigue, due to reduced SR Ca2+ release, and in alkalosis, due to increased myoplasmic Ca2+ buffering. Force is monotonically related to [Ca2+]i but depends also on the myofibrillar Ca2+ sensitivity and the maximum force cross-bridges can produce. This is clearly illustrated by changes of intracellular pH where, despite a lower tetanic [Ca2+]i, tetanic force is higher in alkalosis than acidosis due to increases of myofibrillar Ca2+ sensitivity and maximum cross-bridge force.     

Clinical use of on-line portal imaging for daily patient treatment verification

PURPOSE: To determine the ease of use by clinical staff and reliability of an electronic portal imaging system and evaluate the potential to utilize on-line imaging to assess accuracy of daily patient treatment positioning in radiation therapy. METHODS AND MATERIALS: A computer controlled fluorescent screen-mirror imaging system was used to acquire on-line portal images. A physician panel assessed on-line image quality relative to standard portal film. Clinical use of the imager was implemented through a protocol where images were obtained during the first six monitor units of external beam. The images were visually compared to a reference portal and patient setup was adjusted for errors exceeding 5 mm. Subsequent off-line analysis was utilized to give insight into the magnitude of clinical setup error in the visually accepted images. RESULTS: Physician evaluation of on-line image quality with an initial 211 images found that 70% were comparable or superior to standard film portal images. Eighty percent of treatment fields fit completely within the on-line imaging area. Eight percent of on-line images were rejected due to poor image quality. Twelve percent of the daily treatment setups imaged required adjustment overall, but specific field types predictably required more frequent adjustment (pelvic and mantle fields). Off-line analysis of accepted images demonstrates that 18% of the final images had setup errors exceeding 5 mm. CONCLUSION: On-line imaging facilitated daily portal alignment and verification. Ease of use, almost instantaneous viewing and consistent ability to identify and locate anatomical landmarks imply the potential for on-line imaging to replace film based approaches. Retrospective analysis of daily images reveals that visual assessment of setup is not sufficient for eliminating localization errors. Further improvement is required with respect to detecting localization error and fully encompassing larger field sizes.     

Experimental results of integral effects tests with 1/10th scale zion subcompartment structures in the Surtsey test facility

Three integral effects tests (IET-1, IET-3, and IET-6) were conducted to investigate the effects of high-pressure melt ejection on direct containment heating. A 1:10 linear scale model of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey test facility at Sandia National Laboratories. The RPV was modeled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a hemispherical bottom head containing a graphite limitor plate with a 4 cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by tube ejection in a severe nuclear power plant accident. The reactor cavity model contained 3.48 kg water with a depth of 0.9 cm that corresponded to condensate levels in the Zion plant. 43 kg iron oxide/aluminum/ chromium thermite was used to simulate molten core debris. The molten thermite in the three tests was driven into the scaled reactor cavity by slightly superheated steam at 7.1, 6.1, and 6.3 MPa for IET-1, IET-3, and IET-6 respectively. The IET-1 atmosphere was pre-inerted with nitrogen, while the IET-3 atmosphere was nitrogen with approximately 9.0 mol% O₂. The IET-6 atmosphere was nitrogen with 9.79 mol% O₂ and 2.59 mol% pre-existing hydrogen. In IET-1, approximately 233 g mol hydrogen were produced but almost none burned because oxygen was not available. In IET-3, approximately 227 g mol hydrogen were produced and 190 g mol burned. In IET-6, approximately 319 g mol hydrogen were produced and 345 g mol burned. The peak pressure increases in the IET-1, IET-3 and IET-6 experiments were 0.098, 0.246, and 0.279 MPa respectively. In IET-3 and IET-6 hydrogen burned as it was pushed out of the subcompartments into the upper region of the Surtsey vessel. In IET-6, although a substantial amount of pre-existing hydrogen burned, it apparently did not burn on a time scale that made a significant contribution to the peak pressure increase in the vessel.     

Mohs' surgery of periocular basal cell carcinoma using formalin-fixed sections and delayed closure

Mohs' surgery of periocular basal cell carcinoma (BCC) ensures a high cure rate with maximal preservation of normal tissue. The formalin-fixed paraffin-embedded tissue technique allows Mohs' surgery to be performed using routine pathology facilities and permits the efficient use of operating room personnel and theatre time. The inevitable delay between excision and closure may potentially result in a poor functional and cosmetic outcome, particularly around the eye. We prospectively studied all patients with periocular BCC treated with this technique at our unit between 1985 and 1996. One hundred and twenty-three periocular BCCs in 120 patients were treated. Microscopic clearance was achieved in all cases. Closure was performed on average 5 days after the initial excisional stage. Closing procedures included direct closure, flaps and grafts. Significant complications affecting outcome were noted in only two patients. Eighty-eight per cent of patients assessed had a functional and cosmetic result regarded as excellent, good or adequate. Mohs' surgery of periocular BCC using formalin-fixed paraffin-embedded tissue and delayed closure results in a satisfactory functional and cosmetic outcome and offers a viable alternative to the frozen section fresh tissue technique.     

Effectiveness of physicians-in-training counseling for smoking cessation in African Americans

This study examined the effectiveness of smoking cessation counseling by physicians-in-training (residents) with African-American patients. One hundred fifty-eight family and internal medicine residents at a large urban public general hospital participated in the study; two thirds of the residents underwent a 2-hour smoking cessation training program. Ninety-two of the trained physicians counseled from 1 to 18 patients. The majority of physicians were male, with 8% being current smokers. Over a 26-month period, 1086 patients were randomly assigned to intervention and control (usual care) groups. Mean patient age was 44 years, mean years smoking was 25, and mean number of cigarettes smoked per day was 14. There were no differences in biochemically validated smoking cessation rates between the intervention and control groups at 3 or 12 months postenrollment (2% versus 1.8% and 2.2% versus 2.8%, respectively). Losses to follow-up were high at both 3 and 12 months (38% and 40% respectively). Implications for future trials in minority populations are discussed. A brief physician-based smoking cessation message does not appear to be an effective strategy for use with African-American smokers in a large urban public general hospital.