Synthetic aperture interferometry: in-process measurement of aspheric optics

A scanning probe consisting of a source and receive fiber pair is used to measure the phase difference between wave fronts scattered from the front and rear surfaces of an aspheric optic. This system can be thought of as a classical interferometer with an aperture synthesized from the data collected along the path of the probe. If the form of either surface is known, the other can be deduced. In contrast with classical interferometers, the method does not need test or null plates and has the potential to be integrated into the manufacturing process.     

On the many faces of Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) is a maternally inherited disorder, associated with mutations in the mitochondrial DNA, which is notorious for its aspecific presentations. Two pedigrees are described with cases that are atypical for LHON with respect to sex, age of onset, interval between the eyes becoming affected, course of the disease, concomitant disorders, additional test results, final visual acuity, and/or results of mtDNA analysis. Moreover, the pedigrees themselves did not suggest maternal inheritance. We analysed the diagnostic and clinical genetic difficulties related to the atypical aspects of these pedigrees. We conclude that mtDNA analysis is justified in every case of optic nerve atrophy with no clear cause. Identification of one of the three LHON specifically associated mtDNA mutations is essential to confirm the diagnosis.     

The shear strength of copper and brass soldered with Sn-40% Pb containing 0 to 10% Sb and/or 0 to 15% Zn

The single lap shear strength of copper and brass soldered with Sn-40% Pb containing 0 to 10% Sb and/or 0 to 15% Zn has been determined and the microstructure examined using metallographic techniques. For any solder composition, brass joints were stronger than copper joints. The strength of copper joints decreased monotonically with the increase of antimony in Sn-Pb solder, and the strength of brass joints increased to a peak with about 3% Sb in the solder and thereafter decreased on further additions of antimony. With less than a few per cent antimony in the solder, 1 % Zn in the solder decreased the strength of both copper and brass joints; with more than 1 % Zn in the solder the strengths of both copper and brass joints were increased substantially. Fracture occurs mainly in the Cu₆Sn₅. The microstructure and the presence of zinc in the intermetallic compounds were determined, and the results are discussed.     

Butylated hydroxytoluene exposure is necessary to induce lung tumors in BALB mice treated with 3-methylcholanthrene

Chronic butylated hydroxytoluene (BHT) treatment after a single administration of a carcinogen increases lung tumor multiplicity in some inbred strains of mice. We report that BALB/cOla and BALB/cByJ mice given a low dose (10 microg/g of body weight) of 3-methylcholanthrene (MCA) develop no lung tumors unless this is followed by chronic BHT exposure. Slightly higher MCA doses (15 and 25 microg/g) induce low lung tumor multiplicities (0.6 and 1.9 tumors/mouse, respectively) that are increased 12-26-fold by chronic BHT administration. This low-dose MCA/BHT model in BALB mice will facilitate the identification of genes regulating susceptibility to lung tumor promotion and pulmonary chemopreventative agents that act at a postinitiation site.     

A multifactorial analysis of melanoma: prognostic histopathological features comparing Clark's and Breslow's staging methods

A multifactorial analysis was used to identify the dominant prognostic variables affecting survival from a computerized data base of 339 melanoma patients treated at this institution during the past 17 years. Five of the 13 parameters examined simultaneously were found to independently influence five year survival rates: 1) pathological stage (I vs II, p = 0.0014), 2) lesion ulceration (present vs absent, p = 0.006), 3) surgical treatment (wide excision vs wide excision plus lymphadenectomy, p = 0.024), 4) melanoma thickness (p = 0.032), and 5) location (upper extremity vs lower extremity vs trunk vs head and neck, p = 0.038). Additional factors considered that had either indirect or no influence on survival rates were clinical stage of disease, age, sex, level of invasion, pigmentation, lymphocyte infiltration, growth pattern, and regression. Most of these latter variables derived their prognostic value from correlation with melanoma thickness, except sex which correlated with location (extremity lesions were more frequent on females, trunk lesions on males). This statistical analysis enabled us to derive a mathematical equation for predicting an individual patient's probability of five year survival. Three categories of risk were delineated by measuring tumor thickness (Breslow microstaging) in Stage I patients: 1) thin melanomas (<0.76 mm) were associated with localized disease and a 100% cure rate: 2) intermediate thickness melanomas (0.76-4.00 mm) had an increasing risk (up to 80%) of harboring regional and/or distant metastases and 3) thick melanomas (>/=4.00 mm) had a 80% risk of occult distant metastases at the time of initial presentation. The level of invasion (Clark's microstaging) correlated with survival, but was less predictive than measuring tumor thickness. Within each of Clark's Level II, III and IV groups, there were gradations of thickness with statistically different survival rates. Both microstaging methods (Breslow and Clark) were less predictive factors in patients with lymph node or distant metastases. Clinical trials evaluating alternative surgical treatments or adjunctive therapy modalities for melanoma patients should incorporate these parameters into their assessment, especially in Stage I (localized) disease where tumor thickness and the anatomical site of the primary melanoma are dominant prognostic factors.     

Strategic planning for bioanalytical automation: managing growth successfully

Bioanalytical automation expanded at Glaxo Inc. from 1987 to 1991 by cycling through periods of justification, planning, implementation, obstacle-jumping and success, which justified continued cycling. In 1990 it became evident that the technology and its growth needed to be planned and the resources had to be managed. A Strategic Plan was researched and prepared. The plan describes the mission, values, goals and structure of the Bioanalytical Automation Group and the most important requirements for achieving those planned goals, including: (1) Long-term management commitment; (2) Trained, dedicated personnel; (3) Quality facilities; (4) Teamwork; and (5) Investment in automationcompatible equipment. The strategic plan has been in effect for over a year; current status, history, and the future are discussed in this article.     

A model for the enantiomeric enrichment of polypeptides on the primitive earth

A mixture of D- and L-leucine N-Carboxyanhydride (NCA) having an enantiomeric composition of 65.6% L- and 34.4% D-isomer (i.e. 31.2% enantiomeric excess (e.e)) was polymerized to the extent of 52% with sodium methoxide initiator to yield a polyleucine product the enantiomeric composition of which was 72.7% L- and 27.3% D-leucine (45.4% e.e.). This polymer was in turn partially hydrolyzed by acid, whereupon the unhydrolyzed polyleucine residue was found to have an enantiomeric composition of 77.5% L- and 22.5% D-leucine (55.0% e.e.). Thus the e.e. increase in the partial polymerization step (14.2%) and the partial hydrolysis step (9.6%) combined to total 23.8% for the overall polymerization-hydrolysis sequence. On the basis of these model experiments it is proposed that repetitive partial polymerization hydrolysis reactions, driven by environmental dry-wet cycles, might have been operative on the primitive Earth to engender the abiotic evolution of optically enriched polypeptides.     

Serum HIV-1 RNA levels and time to development of AIDS in the Multicenter Hemophilia Cohort Study

Normal women produce small amounts of active androgens. When androgen levels are elevated, such as for example in the polycystic ovary syndrome, this is followed by the development of male physical characteristics and muscle mass, structure and function as well as android adipose tissue distribution and function. Psychological features and stress reactions also seem similar to those of men. Such women have an increased risk of developing hypertension, non-insulin-dependent diabetes mellitus and cardiovascular disease. Recent data have shown that these physical, and psychological characteristics, as well as risk of ill health, are also found in the population of women selected at random. Women in the lowest quintiles of levels of sex-hormone-binding globulin--an indicator inversely related to active androgens--are at risk of developing hypertension, non-insulin-dependent diabetes mellitus and cardiovascular mortality. The mechanism probably includes muscular insulin resistance, following a relative androgen excess. It is thus apparent that androgens, even within the highest levels of the nonselected population of women, are powerful predictors of serious disease development. The population at risk might be as large as about 20% of middle-aged women. This is an area of female disease risk which requires more attention in screening and intervention procedures.     

巨磁电阻读出磁头

用巨磁电阻（GMR）材料构成的磁电子学新器件,已开始在计算机存储领域成功地获得了应用,本文介绍了用于计算机硬件磁盘驱动器的巨磁电阻磁头,描术字它的工作原理、性能特点及研究现状和发展趋势。