Vector characterization of photodetectors, photoreceivers, andoptical pulse sources by time-domain pulse response measurements

Deconvolution of measurement system effects from pulse response measurements is demonstrated to yield reproducible, accurate characterization of the impulse response (and vector frequency response) of a photodetector or photoreceiver, as well as the intensity waveform of an optical pulse. Calibration is based on a <3-ps FWHM (full width at half maximum) optical pulse and a 50-GHz 3-dB bandwidth electrical sampling system. Vector characterization of a photodetector/photoreceiver to >40 GHz and an optical pulse source to >30 GHz are demonstrated. Calibration and effects of noise are discussed     

ACAT inhibitors derived from hetero-Diels-Alder cycloadducts of thioaldehydes

Acyl-CoA:cholesterol acyltransferase (ACAT) is the enzyme largely responsible for intracellular cholesterol esterification. A systemic inhibitor of ACAT is believed to be able to slow or even reverse the atherosclerotic process. Towards that goal, a series of cyclic sulfides, derived from the hetero-Diels-Alder reaction of thioaldehydes with 1,3-dienes, and bearing carboxamide substituents, were prepared and evaluated for in vitro (in several tissues and species) and ex vivo ACAT inhibition. Minor changes in subsequent structure were found to have a significant effect in optimization of the biological activity of this series of compounds.     

Middle cerebral artery main stem thrombosis in two siblings with familial thrombotic thrombocytopenic purpura

Idiopathic thrombotic thrombocytopenic purpura (TTP) is frequently complicated by microinfarcts in cerebral cortex and subcortical white matter. We describe two sisters who suffered massive hemispheric infarction due to thrombosis of the middle cerebral artery main stem during exacerbations of TTP. Acute TTP may be associated with intraluminal thrombosis of large-diameter arteries in addition to arterioles and capillaries.     

How office space affects programming productivity

The relationship between office size and noise level is one of the most significant, yet least investigated, factors affecting software productivity. According to Tom DeMarco and Tim Lister (1992), US programmers with more than 80 square feet of private, noise-free office space consistently outperform programmers who occupy two- or three-person cubicles. The result was the Santa Teresa Programming Laboratory in San Jose, California, which opened in 1978. The author discusses some requirements of an optimal programming office environment. He considers the effectiveness of home working     

Fertilization in vitro. A review over the medical indications and suggestion to unified guidelines for public fertility clinics in Denmark

Medical indications for in vitro fertilization and embryo transfer (IVF-ET) internationally and in Denmark are reviewed. Reports from large international centres document that tubal infertility, unexplained infertility, endometriosis and male infertility are equally good indications for IVF. Traditionally, tubal infertility has been the only medical indication qualifying for IVF treatment within the National Health Service in Denmark. Thus, in this country, couples with unexplained and male infertility and with endometriosis have to pay up to 25,000 D.Kr. per IVF-ET treatment in private fertility clinics. Since there is no scientific basis for this discrimination, it is urged that the present rules are changed, so that couples with unexplained and male infertility and endometriosis are also allowed IVF treatment free of charge in the public fertility clinics.     

Real-time X-ray diffraction study at different scan rates of phase transitions for dipalmitoylphosphatidylcholine in KSCN

A questionnaire survey was carried out to examine the attitudes and practices of Australian and New Zealand intensivists with regard to brain death and organ donation. A return rate of 82.5% was achieved. Fifty-eight per cent had written evidence of their own wishes to donate organs and 94% would agree to donation from a dependent. At least one intensivist is involved in certifying brain death on 95% of occasions. Intensivists are involved in the request for organ donation over 90% of the time although one-third do not believe that it is their role to request organ donation. Although two-thirds believe that the family should always be approached for organ donation, another 52 out of 254 indicated that it was their (the intensivist's) role to decide if families should be asked for organ donation. Possible reasons for not requesting are language or other communication problems, perceptions of cultural differences and degrees of family distress. Twenty per cent of respondents do not provide haemodynamic support before brain death confirmation. Australian and New Zealand intensivists overwhelmingly support the concept of brain death, current methods of confirmation of brain death, organ donation and transplantation. Possible reasons behind loss of potential donors include decisions not to resuscitate both before and after brain death is confirmed. Perceptions of family grief and cultural differences clearly inhibit requests for organ donation. A very few units have an effective policy on approaching families about organ donation. Intensivists have almost exclusive control over requests for organ donation and thus bear a full professional responsibility for this element of hospital practice.     

Hematopoietic stem cell transplantation for infantile osteopetrosis

Infantile osteopetrosis is a lethal disorder resulting from a severe defect in the ability of osteoclasts to resorb bone. The only therapy shown to be capable of providing lasting benefit is allogeneic hematopoietic stem cell transplantation (HCT). We report the outcome of 10 patients with infantile malignant osteopetrosis treated with HCT from an HLA A, B, DRB1 matched (n=6) or A or B locus mismatched (n=4) family member or unrelated donor at the University of Minnesota between 1978 and 1997. Eight of 10 patients achieved primary engraftment; secondary graft failure was seen in two patients. Five of 10 patients survive; three with full or partial donor chimerism and two with autologous hematological recovery. Transient or partial donor chimerism can be sufficient to correct the hematological manifestations of osteopetrosis. We recommend early referral for consideration of HCT with a related or unrelated donor as neurosensory manifestations of osteopetrosis are generally not reversible. Donor engraftment may be easier to achieve early in the course of the disease.     

Multiple solution conformations of the integrin-binding cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-). Analysis of the (phi, psi) space available to cyclic pentapeptides

The aqueous solution structure of the cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-) has been determined by two-dimensional 1H-NMR spectroscopy, combined with a conformational search and distance-geometry calculations. As many as five conformers in slow exchange were observed, and the rate of interconversion between components was measured from the build-up rates of exchange peaks. NMR data allowed the structures of the two predominant conformers to be determined. The major component (66%) contained a cis-proline as part of a type-VIa2 beta-turn encompassing residues Asp-Val-cis-Pro-Ser. The second component (16%) contained only trans-amide bonds, and a type-VIII beta-turn formed by residues Val-Pro-Ser-D-Leu. These structures are discussed in relation to the (phi, psi), space available to the cyclic pentapeptide, determined by a conformational search, and in relation to previously published cyclic-pentapeptide structures. The molecule exhibits activity in a scintillation-proximity assay for the inhibition of the interaction between the integrin very-late antigen-4 (VLA-4; alpha 4 beta 1) and vascular-cell-adhesion molecule-1 (VCAM-1). The structure/activity relationship of the LDV sequence is discussed and related to the recently published X-ray structure of VCAM-1. The relevance of the work to the design of anti-inflammatory drugs is discussed.