Experimental and theoretical evaluation of the CW suppression of TEside modes in conventional 1.55 μm InP-InGaAsP distributed feedbacklasers

A study is made of the factors that influence the suppression of the second TE Bragg mode in conventional 1.55 μm capped-mesa-buried-heterostructure distributed-feedback (CMBH-DFB) lasers. It is shown that the TE side-mode suppression becomes increasingly worse as the coupling of the optical mode to the grating ( kL) becomes larger, as expected from theoretical predictions. This degradation is not correlated to changes in the measured threshold gain margin, as obtained from spectral resonances. To explain the results, the authors introduce a new parameter-the threshold bias margin-which is a measure of the threshold difference between the lasing mode and the most prominent side mode     

Thymus-derived striated muscle clones. An ultrastructural analysis of cell differentiation

Myogenic clones can be induced in thymus reticulum cultures from adult mice. We investigated the differentiation and maturation of myogenic cells by combined ultrathin section and freeze etching analyses. New insights into the development of cell membranes and cytoplasmic organelles will be discussed in the light of previous investigations of embryonic muscle cell cultures.     

Growth and characterization of high yield, reliable, high-power,high-speed, InP/InGaAsP capped mesa buried heterostructure distributedfeedback (CMBH-DFB) lasers

The capped-mesa buried-heterostructure distributed-feedback (CMBH-DFB) laser structure requires three epitaxial growths and is designed to allow good control of the width of the active layer using straightforward chemical etching techniques. The base structure, which contains the active layer, was fabricated using a variety of epitaxial techniques: liquid-phase epitaxy, hydride vapor-phase epitaxy (VPE) and metalorganic vapor-phase epitaxy (MOVPE). The final cap growth was done using hydride VPE. High yields of low-threshold high-power DFB lasers were produced from a number of wafers at emission wavelengths of 1.3 and 1.55 μm     

Pituitary adrenocorticotrophic (ACTH) cells during reproductive cycle in a Vespertilionid bat, Scotophilus heathi

Present study described the pituitary adrenocorticotropic (ACTH)-cells during different phases of reproductive cycle of Indian Vespertilionid bat, S. heathi. ACTH-cells were identified by histochemical, immunocytochemical and electron microscopic techniques. These cells shows round to polygonal in shape and be easily distinguished by histochemical staining. The body weight attains peak during recrudescence phase due to accumulation of fat. The mean areal fraction occupied by ACTH-cells were higher in recrudescence and winter dormancy as compared with other reproductive phases. The size and granulation pattern of these cells showed variation in relation with the seasonal fat cycle. The possible significance of ACTH-cells during periods of recrudescence and winter dormancy, which is also coincided with period of delayed ovulation in this species, were discussed.     

Effects of arm support on shoulder and arm muscle activity during sedentary work

The aim of this study was to evaluate different arm supports by comparing the activity of shoulder and arm muscles during various work tasks, with and without the lower arm supported. Twelve female subjects, aged between 23 and 37 years, were asked to perform three types of tasks: typing, simulated assembly work (in two different positions), and pipetting. The supports used were: fixed arm support (FIX), horizontal movable arm support (HOR), and spring-loaded arm support (SLA). During the experiments, the electromyograms (EMG) of four muscles were simultaneously recorded: m. deltoideus anterior and lateralis, m. trapezius pars descendens and m. extensor carpi radialis brevis. Normalization was made against maximum isometric contraction. The mean values of the normalized EMG levels showed a reduced EMG level of the shoulder muscles when using arm supports in all the tasks, and for all muscles but the wrist extensor, compared to the EMG levels without arm supports. The horizontal movable support was more effective in reducing the EMG levels of the shoulder muscles than other arm supports, in tasks at table height. Thus, it is possible to reduce muscle activity of the shoulder region by using arm supports. Further research is needed to make biomechanical calculations to compare the EMG level of these muscles using suspension and the effects of inclination of work task.     

Receptors for oxidized low density lipoprotein

An increasing body of evidence indicates that oxidized low density lipoprotein (LDL) is involved in the pathogenesis of atherosclerosis. One of the first biologic actions of oxidized LDL to be identified in vitro was its ability to interact with the 'acetyl LDL receptor' discovered by Goldstein and Brown. Over the past decade, considerable progress has been made in identifying and characterizing cell-surface receptors for oxidized LDL. Most of these receptors are thought to be multifunctional because they interact with several structurally different ligands, and accordingly have been termed 'scavenger receptors'. The objective of this article is to review the most important publications dealing with structure, ligand specificity, regulation, and function of scavenger receptors.