Coronary angioplasty, a privileged method of myocardial revascularization of the elderly

Coronary angioplasty is a myocardial revascularisation technique of choice in the elderly, avoiding the need for general anesthesia as well as the complications of thoracotomy and extracorporeal circulation. Used in a continuous series of 62 patients, it provided a 79% primary success rate in this situation, where reaching the coronary artery and penetrating the stenosis may be difficult. Femoral complications (hematoma, false aneurysm) are commoner in this age group, but appear to be beneficially influenced by the replacement of heparin by ticlopidine peri-operatively. With 24 months follow-up, the proportion of patients free of any major cardiac event and NYHA classes I and II is 66%, actuarial survival rate without infarction is 76%. These results would tend to restrict the indications for bypass after the age of 75 to cases of stenosis of the left main coronary artery, failure of angioplasty or multi-vessel atheroma with a "culprit lesion" inaccessible to dilatation.     

Ordering in InGaAs/InAlAs layers

The structure of InCaAs/InAlAs layers lattice matched to an InP substrate, grown on either (100) or on (110) with a 4° tilt toward [111] at 500 and 300°C has been investigated by transmission electron microscopy. High perfection resulted for the layers grown on [001] oriented substrates whereas growth on the near [110] substrates resulted in compositional nonuniformities, macrosteps formation, and ordering of the group III elements. This difference in structural perfection between the two sets of samples was also reflected in differences in electrical properties.     

„Prächtiges Menschenmaterial“ – Anthropometrische Konstitutionsforschung auf der Suche nach dem statistischen Normalkörper (1914–1922)

NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin - Im Zentrum der vorliegenden Arbeit steht das anthropometrische Forschungsprogramm der Konstitutionslehre während...     

Solid source MBE growth of InAsP/InP quantum wells

Strained InAsP multiquantum wells (MWQs) were grown on InP(100) substrates by solid source molecular beam epitaxy and were characterized to relate structural and optical quality to growth conditions. The multiquantum wells were grown using either dimer or tetramer arsenic (As₂ or As₄) over the substrate temperature range of 420–535°C. θ-2θ x-ray diffraction measurements showed only slight differences between arsenic compositions in the quantum wells grown with As₂ or As₄. 300K and 8K photoluminescence full width at half max (FWHM) decreased at higher growth temperatures regardless of the arsenic species used. The 8K photoluminescence FWHM and the surface roughness measured by atomic force microscopy are found to be less sensitive to substrate growth temperature for the multiquantum wells growth with As₂ as opposed to As₄.     

Design of high-efficiency current-mode class-D amplifiers for wireless handsets

Design considerations are discussed for current-mode class-D (CMCD) microwave power amplifiers. Factors affecting amplifier efficiency are described analytically and via simulation. Amplifiers are reported that incorporate parallel LC resonators alongside the switching transistors. To reduce parasitic resistance, bond-wires were utilized to implement a high Q inductor in the LC resonator. An experimental CMCD amplifier based on GaAs HBTs is reported, with collector efficiency of 78.5% at an output power of 29.5 dBm (0.89 W) at 700 MHz.     

A selective human beta3 adrenergic receptor agonist increases metabolic rate in rhesus monkeys

Activation of beta3 adrenergic receptors on the surface of adipocytes leads to increases in intracellular cAMP and stimulation of lipolysis. In brown adipose tissue, this serves to up-regulate and activate the mitochondrial uncoupling protein 1, which mediates a proton conductance pathway that uncouples oxidative phosphorylation, leading to a net increase in energy expenditure. While chronic treatment with beta3 agonists in nonprimate species leads to uncoupling protein 1 up-regulation and weight loss, the relevance of this mechanism to energy metabolism in primates, which have much lower levels of brown adipose tissue, has been questioned. With the discovery of L-755,507, a potent and selective partial agonist for both human and rhesus beta3 receptors, we now demonstrate that acute exposure of rhesus monkeys to a beta3 agonist elicits lipolysis and metabolic rate elevation, and that chronic exposure increases uncoupling protein 1 expression in rhesus brown adipose tissue. These data suggest a role for beta3 agonists in the treatment of human obesity.     

Matrix behavior in copper-tungsten composites at small strains

Composites with up to 15 pct tungsten wires in a copper crystal matrix prepared by infiltration showed matrix microyield and flow stresses increasing with fiber fraction. Dislocation etch-pit observations showed that the walls of a cell structure in the matrix formed during fabrication were the operative dislocation obstacles and that this initial structure rather than fiber-matrix interaction during straining was responsible for the matrix strengthening.     

Sauna-takers disease. Hypersensitivity pneumonitis due to contaminated water in a home sauna

Daily saunas taken by a young man were followed by fever, chills, malaise, dyspnea, cough, and myalgia from six to eight hours later. Symptoms, which were related to pouring water from a sauna bucket over the heating element, progressed to chronic dyspnea and fatigue. Serial serum samples showed precipitin reactions to bucket water and extracts of bucket mold. IgG antibody activity, demonstrated by radioimmunoassay, suggested that Pullularia was a major antigen.