Diffraction of millimeter waves by projecting a shadow pattern onto a semiconductor

The transmission of millimeter waves through a semiconductor changes according to the amount of light falling on it. In the experiments reported here, a pattern of light and shadow is projected onto a sheet of semiconductor and the regions of greater and lesser transmission serve as a diffracting object for a millimeter-wave beam. The light source is a quartz tungsten halogen lamp. A lock-in amplifier is employed to overcome difficulties due to the differences in transmitted power being small.     

Intrauterine transfusions influence fetal leukocyte counts and subsets

Histamine is an important mediator in allergic reactions, gastric acid secretions, and neurotransmission in the central nervous system. Basophils and mast cells are the main sources of histamine, which is formed from L-histidine by histidine decarboxylase (HDC). However, the regulatory mechanism of HDC in these cells remains unclear. We examined the regulation of HDC activity and gene expression using a unique human mast cell line, HMC-1, after stimulation with phorbol 12-myristate 13-acetate (PMA) or ionomycin. HDC activity was increased from 52.1+/-0.4 (mean+/-standard deviation) to 154+/-6.9, or 105.6+/-6.2 pmol/min/mg protein (n = 3), 4 hours after stimulation with PMA (10 ng/mL) or ionomycin (10[-6] M). Although actinomycin D had no effect on this increase, cycloheximide completely inhibited the increase caused by these stimuli. The population of HMC-1 cells containing HDC protein was increased after stimulation with either PMA or ionomycin as evaluated by immunocytochemical analysis with anti-HDC antibody as a marker. HMC-1 constitutively expressed HDC mRNA, and its level was not increased with these stimuli. These results suggest that the increase of HDC activity in HMC-1 induced by PMA or ionomycin is regulated at the translational level.     

Correlation between clinical course and quantitative analysis of the ischemia related artery in patients with unstable angina pectoris, refractory to medical treatment. Results of two randomized trials. The European Cooperative Study Group

Patients with unstable angina, refractory to intensive medical therapy, are at high risk for developing thrombotic complications, such as recurrent ischemia, myocardial infarction and coronary occlusion during coronary angioplasty. As both platelet aggregation and/or thrombus formation play an important role in this ongoing ischemic process, a monoclonal platelet GPIIb/IIIa receptor antibody (c7E3) or thrombolytic therapy (alteplase) might be able to modify the clinical course and underlying coronary lesion morphology. To evaluate whether alteplase or c7E3 could influence the incidence of complications, we randomized 36 and 60 patients, respectively to alteplase or placebo, or c7E3 or placebo. All patients exhibited dynamic ECG changes and recurrent pain attacks, despite maximal tolerated medical therapy. Patients were randomized in both studies after initial angiography had demonstrated a culprit lesion amenable for angioplasty. After study drug infusion quantitative angiography was repeated and angioplasty performed. Recurrent ischemia during study drug infusion occurred in 5, 6, 9 and 16 patients from the alteplase, placebo, c7E3 and placebo group, respectively. Major events defined as death, myocardial infarction or urgent intervention occurred in 7, 3, 1 and 7 patients, respectively. Two patients died: one in the alteplase group and one in the placebo group from the c7E3 study. The first patient due to retroperitoneal hemorrhage, the second as a result of recurrent infarction. Qualitative angiography showed resolution of clots in the c7E3 group only, while the same group of patients showed in 20% an improvement in TIMI flow grade, without deterioration in any patient from this group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multinuclear NMR spectroscopy studies on NH4Cl-induced metabolic alterations and detoxification processes in primary astrocytes and glioma cells

Glutamine synthesis, the major pathway of ammonia detoxification, and the intracellular concentration of organic osmolytes in primary astrocytes and F98 glioma cells were investigated with multinuclear magnetic resonance spectroscopy. Acute exposure to ammonia (3 h incubation with NH4Cl) raised the concentration of glutamine and other amino acids, such as glutamate and aspartate, and decreased myo-inositol, hypotaurine, and taurine concentrations. The loss of these osmolytes was partially reversed by co-treatment with the glutamine synthetase inhibitor, methionine sulphoximine. Glutamate, the precursor of glutamine, is provided by stimulated anaplerotic flux via pyruvate carboxylase and glutamate dehydrogenase activity. Thus, the glutamine increase and myo-inositol decrease observed by in vivo magnetic resonance spectroscopy on patients with hepatic encephalopathy may be due to the disturbed osmoregulation in astrocytes caused by accumulation of glutamine and the subsequent loss of organic osmolytes.     

Thermally excited silicon oxide beam and bridge resonators in CMOStechnology

The design, fabrication, and characterization of thermally excited silicon oxide beam and bridge resonators by a modern industrial CMOS process combined with one additional maskless etching step is reported. The resonant frequencies, vibration amplitudes, and mode shapes of the devices are measured using a laser heterodyne interferometer. The acoustic transmitting and receiving sensitivities of the resonant structures in air are investigated in order to test their possible application as ultrasound transducers for proximity sensing. The experimental results are compared with finite element simulations using ANSYS     

Minimization of switching activities of partial products for designing low-power multipliers

This work presents low-power 2's complement multipliers by minimizing the switching activities of partial products using the radix-4 Booth algorithm. Before computation for two input data, the one with a smaller effective dynamic range is processed to generate Booth codes, thereby increasing the probability that the partial products become zero. By employing the dynamic-range determination unit to control input data paths, the multiplier with a column-based adder tree of compressors or counters is designed. To further reduce power consumption, the two multipliers based on row-based and hybrid-based adder trees are realized with operations on effective dynamic ranges of input data. Functional blocks of these two multipliers can preserve their previous input states for noneffective dynamic data ranges and thus, reduce the number of their switching operations. To illustrate the proposed multipliers exhibiting low-power dissipation, the theoretical analyzes of switching activities of partial products are derived. The proposed 16 /spl times/ 16-bit multiplier with the column-based adder tree conserves more than 31.2%, 19.1%, and 33.0% of power consumed by the conventional multiplier, in applications of the ADPCM audio, G.723.1 speech, and wavelet-based image coders, respectively. Furthermore, the proposed multipliers with row-based, hybrid-based adder trees reduce power consumption by over 35.3%, 25.3% and 39.6%, and 33.4%, 24.9% and 36.9%, respectively. When considering product factors of hardware areas, critical delays and power consumption, the proposed multipliers can outperform the conventional multipliers. Consequently, the multipliers proposed herein can be broadly used in various media processing to yield low-power consumption at limited hardware cost or little slowing of speed.     

Mechanical consequences of core drilling and bone-grafting on osteonecrosis of the femoral head

We employed an anatomically realistic three-dimensional finite-element model to explore several biomechanical variables involved in coring or bone-grafting of a segmentally necrotic femoral head. The mechanical efficacy of several variants of these procedures was indexed in terms of their alteration of the stress:strength ratio in at-risk necrotic cancellous bone. For coring alone, the associated structural compromise was generally modest, provided that the tract did not extend near the subchondral plate. Cortical bone-grafting was potentially of great structural benefit for femoral heads in which the graft penetrated deeply into the superocentral or lateral aspect of the lesion, ideally with abutment against the subchondral plate. By contrast, central or lateral grafts that stopped well short of the subchondral plate were contraindicated biomechanically because they caused marked elevations in stress on the necrotic cancellous bone. Calculated levels of stress were relatively insensitive to variations in the diameter of the graft.     

波长为515nm的氩离子激光器的频率稳定

用声光晶体对氩离子激光作频率调制,获得了碘分子的差拍饱和吸收信号。将得到的斜率极陡的—阶微商形式的饱和吸收信号作为鉴频曲线把氩离子频率激光稳定到~(127)I_2分子的p(13)43—0的a_3超精细分量上。通过与一稳定到相同精细分量的稳频氩离子激光拍频,给出激光频率稳定性优于±6.5×10~(-12),重复性优于±3.4×10~(-11)。     

Products formed in an aged concrete

At a dam in Australia the concrete shows a widespread reaction that has caused surface cracking, and possibly a tightening up of gates that control the flow of water through diversion tunnels. The reaction has produced reaction rims to the aggregate, a crystallization of zeolite A-like material within the aggregate and in pores in the concrete, in addition to the precipitation of amorphous alkali-silicate hardened gel in other concrete pores. The hardened gel is sometimes associated with trona and is metastable. It tends to transform into zeolite A-like material or analcite. The reaction products are low in alumina and high in silica. Possible reaction mechanisms are discussed.