Analysis of burn-in time using the general law of reliability

Empirical lifetime distributions sometimes have a bathtub-shaped failure rate. This paper deals with some models having a bathtub-shaped failure rate. The root-mean-square criterion is proposed for selection of the best model. Besides two criteria of optimum burn-in time are proposed. The comparison of some models with the general law of reliability is given to determine a burn-in time in a number of examples.     

Toward the reduction of population obesity: Macrolevel environmental approaches to the problems of food, eating, and obesity.

The authors reviewed the evidential basis of three environmental approaches to reducing population obesity: What are the effects of (a) taxing or subsidizing foods, (b) manipulating the ease of food access, and (c) restricting access to certain foods? A narrative review evaluated evidence using National Heart, Lung, and Blood Institute criteria. There was strong evidence that subsidization influences food purchases, but not necessarily food consumption or body weight. Ease of food access may influence food purchases, and possibly food intake and body weight. Data on restriction were lacking. More studies are needed to justify that altering these macro-environmental variables will necessarily reduce population obesity. A proposed conceptual model posits that the steps through environmental interventions may exert intended and unintended influences on body weight and obesity prevalence. Contemplated policy changes should weigh scientific evidence with social judgments and values concerning changes to the environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Autoradiographic assessment of blood flow heterogeneity in the hamster heart

OBJECTIVE: Provide regional flow measurement in the hearts of small mammals using a new, higher-resolution technique based on the deposition of a molecular marker. METHODS: We determined the instantaneous extraction and retention of the "molecular microsphere" radiolabeled desmethylimipramine in retrogradely perfused hamster hearts. In a separate series of experiments, autoradiography was used to measure regional myocardial deposition densities in hamster hearts of about 0.5 g with spatial area resolution of 16 x 16 microns. RESULTS: Radiolabeled desmethylimipramine is almost 100% extracted during a single transcapillary passage and is retained in the tissue for many minutes. Autoradiographic images demonstrated a spatial flow heterogeneity with standard deviations of 31 +/- 4% of the mean flow (N = 5) in 16 x 16 x 20-micronm3 voxels. This is equivalent to the projections made using fractal relationships from cruder observations obtained with microspheres in the hearts of baboons, sheep, and rabbits. CONCLUSIONS: Autoradiography using a molecular deposition marker provides quantitative information on myocardial flow heterogeneities with resolution at the size of cardiac myocytes. Because the regions resolved are smaller than the volume of regions supplied by single arterioles, the results must slightly exaggerate the true heterogeneity of regional flows.     

Division of the genitofemoral nerve and late orchiectomy: effects on the contralateral testis in ipsilateral testicular torsion

Unilateral torsion of the spermatic cord has been demonstrated to damage the contralateral testis; however, the pathogenesis has not yet been examined in detail. The purpose of this study was to evaluate the influence of unilateral torsion on the contralateral testis in rats by performing ipsilateral division of the genitofemoral nerve (GFN) and/or late orchiectomy. Male 25-day-old, prepubertal Wistar albino rats were divided into five groups: (1) sham operation; (2) unilateral testicular torsion; (3) simultaneous unilateral testicular torsion and ipsilateral GFN division; (4) unilateral testicular torsion and orchiectomy on the 4th day after torsion; and (5) simultaneous unilateral testicular torsion and GFN ipsilateral division, and orchiectomy on the 4th day after torsion. Torsions performed were 720 degrees, all on the right testes. On day 55 after torsion, which represents the early postpubertal period of the rat, the contralateral testes were removed. Tubular biopsy score (TBS) was calculated, and seminiferous tubular diameters (STD) were measured. Student's t-test was used for statistical analysis. There was no contralateral testicular damage in the control group, but in all of the study groups destructive changes were found in the left gonad after torsion of the right testicle. The mean TBS of the study groups was higher than that of the control group. STD values were lower in the study groups, but the differences were not statistically significant between groups. In prepubertal rats, unilateral torsion causes histologically measurable changes in the contralateral testis. Ipsilateral division of the GFN and late orchiectomy did not cause any significant alterations in terms of contralateral damage. Further investigations are needed to determine the role of the GFN in testicular torsion.     

Length of stay for specialized pediatric urologic care

BACKGROUND: Pediatric urologic specialists have been excluded from many recent managed care contracts because they are believed to be more expensive and of no better quality than general urologists in managing common urologic problems in children. We believed this to be inaccurate. OBJECTIVES: To compare the length of stay at the University of California, San Francisco Medical Center for 2 common pediatric urologic operative procedures with data from other northern California hospitals and to document our results and patient satisfaction. DESIGN: Retrospective analysis of HCIA statewide database (HCIA Inc, Orange, Conn). SETTING: Northern California, 1995. SUBJECTS: Children younger than 12 years undergoing surgery for repair of an obstruction of the ureteropelvic junction or vesicoureteral reflux. MAIN OUTCOME MEASURE: Length of stay. RESULTS: The length of stay in our hospital was similar to that observed in other hospitals in which other full-time pediatric urologic specialists practiced and was significantly less than that observed in other northern California hospitals, even when adjusted for risk. In fact, a savings of 279 hospital days would have been realized if all patients had the same length of stay as that achieved at University of California, San Francisco Medical Center. In the 38 patients operated on at our center, there was uniform surgical success. Of the parents, 92% (11/ 12) were satisfied with their child's care and 92% (11/ 12) believed they received enough information to know what to expect and how to care for their child at home. There were no data available evaluating quality from other northern California hospitals for comparison. CONCLUSIONS: Our finding that actual and risk-adjusted length of stay were shorter when patients were treated by full-time pediatric urologists, while excellent quality was maintained, suggests that these specialists achieve their results with more efficiency and lower resource utilization than do general urologists. The implication of these results is that exclusive contracting that prevents patients from receiving care from full-time specialists results in overuse of valuable resources and possibly reduced quality. If our results are generalizable, they have important implications for health care reform in the United States.     

Design and synthesis of a series of potent and orally bioavailable noncovalent thrombin inhibitors that utilize nonbasic groups in the P1 position

As part of an ongoing effort to prepare therapeutically useful orally active thrombin inhibitors, we have synthesized a series of compounds that utilize nonbasic groups in the P1 position. The work is based on our previously reported lead structure, compound 1, which was discovered via a resin-based approach to varying P1. By minimizing the size and lipophilicity of the P3 group and by incorporating hydrogen-bonding groups on the N-terminus or on the 2-position of the P1 aromatic ring, we have prepared a number of derivatives in this series that exhibit subnanomolar enzyme potency combined with good in vivo antithrombotic and bioavailability profiles. The oxyacetic amide compound 14b exhibited the best overall profile of in vitro and in vivo activity, and crystallographic studies indicate a unique mode of binding in the thrombin active site.     

Operative complications of hernia repair in childhood

In a training center, 1,131 inguinal hernias were repaired in 1,000 consecutive patients in 6 years. The documents of these patients were reviewed retrospectively for surgical complications. A total of 38 complications were encountered in 35 patients, including wound infection (1.9%), recurrence (0.9%), tethered testis (0.3%), bladder injury (0.3%), was deferens injury (0.2%), iatrogenic orchiectomy (0.1%), and postoperative death. Most of them occurred in the early years of the clinic, and nearly one-half were technical in nature. Careful training, stressing the importance of gentle handling of the tissues, and meticulous dissection with emphasis on learning groin anatomy should reduce the incidence of such complications.     

Methodology for creating “rejuvenating” devices

In this paper we discuss the properties and characteristics of rejuvenating elements. By applying a developed method for expanding a distribution density function into generalized orthogonal Laguerre polynomes, the failure rate function of semiconductor devices has been investigated. It is shown that with this methodology one can create rejuvenating devices.