Hydrogen component fugacity in binary mixtures with carbon monoxide: Temperature dependence

The fugacity coefficients of hydrogen in binary mixtures with carbon monoxide were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not carbon monoxide, can penetrate. Measurement of the gas pressures inside and outside of the membrane allows a direct measurement of the hydrogen component fugacity at a given temperature and binary mixture mole fraction. In this paper, results are reported at 130, 160, and 190°C. In each case, the total pressure of the mixture was maintained at a nominal value of 3.39 MPa. The general qualitative features of the data are discussed, and comparisons are made with predictions obtained from the Redlich-Kwong, Peng-Robinson-Soave, and extended corresponding-state models.     

Removal of Ambiguous Wind Directions for a Ku-Band Wind Scatterometer Using Three Different Azimuth Angles

The Seasat-A satellite scatterometer (SASS) sensor demonstrated very successfully that Ku-band scatterometers can make accurate synoptic measurements of surface wind speed over the ocean. Because SASS provided normalized radar cross section (NRCS) measurements from only two azimuths, however, the harmonic relationship of NRCS with azimuth results in up to four ambiguous wind directions. The primary improvement to be incorporated in a next-generation scatterometer design such as Navy Remote Ocean Sensing System (NROSS) is the addition of a third azimuth look at each sampled cell. With this and other instrument improvements, preliminary studies indicate that wind-direction ambiguities (aliases) could successfully be removed in at least 80 percent of the cases. Furthermore, these studies show that in over 90 percent of the wind solutions, the two most probable solutions correctly identify the wind streamlines. Methods were studied which could examine typical streamline patterns derived from scatterometers using continuity or pattern-recognition techniques to determine which of the possible two wind directions was correct. In addition, unambiguous solutions were sought for cases where streamlines were not correctly defined. This paper describes several approaches for such alias-removal algorithms. These algorithms were developed with the aid of simulated three-beam scatterometer ambiguous wind-solution data (based on NOSS conditions) over a known windfield. The resulting algorithms were evaluated using a different set of simulated orbital data, but withholding the true winds.     

Direct measurement of the acoustic decay times of hypersonic waves generated by SBS

The acoustic decay time of hypersound generated by stimulated Brillouin scattering (SBS) has been measured in several heavy gases (Xe, SF6, CCIF3, C2F6) over a range of pressures. A straightforward optical probing technique is used whereby the decay time can be measured directly with high precision. A theoretical formulation of the decay mechanisms in a polyatomic gas is presented, and it is shown both theoretically and experimentally that vibrational relaxation can become the major decay process at high gas density. The Brillouin gain coefficient and acoustic frequency are also experimentally determined or calculated for the gases investigated. Two Brillouin-active gases (CCIF3and C2F6) with high Brillouin gains, which have not been studied previously, have been characterized. A study of the gas C2F6near its critical point showed a large variation of the acoustic velocity which reaches a minimum value in the vicinity of its critical density.     

Prostate tissue composition and response to finasteride in men with symptomatic benign prostatic hyperplasia

PURPOSE: We sought to quantify prostate tissue changes induced by finasteride and to identify a predictor of finasteride response in men with symptomatic benign prostatic hyperplasia (BPH) via a randomized, placebo controlled, double-blind clinical trial. MATERIALS AND METHODS: Men with symptomatic BPH (52 to 78 years old) were randomly assigned to 6 months of treatment with finasteride (26) or placebo (15). Outcome measures were clinical (urinary symptom score and flow rate), chemical (serum prostate specific antigen and dihydrotestosterone levels), volumetric (transrectal ultrasound, and magnetic resonance imaging for whole and zonal prostate volumes) and histological (morphometry of prostate sextant biopsies, separated into inner and outer gland segments, to measure the percent epithelium, stroma and glandular lumen). RESULTS: In the finasteride group we found a suggestion of decreasing symptom scores and increasing flow rates (not significant) with significant decreases (p < 0.01) in prostate specific antigen (48%), dihydrotestosterone (74%) and prostate volume (21%). Finasteride treatment induced a 55% decrease in inner gland epithelium (p < 0.01) with little effect on stroma or lumina. We also found a linear correlation between pretreatment inner gland epithelial content and prostate volume decrease induced by the drug (tau = 0.58, p = 0.01). CONCLUSIONS: Finasteride treatment results in a major suppression of prostate epithelium, which is most pronounced in the inner gland. Moreover, a finasteride induced prostate volume decrease was predictable by quantification of epithelial tissues of the inner gland. These data lend additional support to the emerging concept of transition zone primacy in symptomatic BPH.     

Analysis of anti-Trypanosoma cruzi antibody isotype specificities by western blot in sera from patients with different forms of Chagas' disease

Infection of humans with Trypanosoma cruzi leads to either a lifelong asymptomatic infection or to symptomatic presentations such as cardiomyopathy, mega-syndromes, or both. The reasons for the different clinical manifestations are not understood. We have previously studied a group of chronically infected individuals with different clinical forms of Chagas' disease and found that the levels of some anti-T. cruzi antibody isotypes, analyzed by enzyme-linked immunosorbent assay, differed among patients with different clinical presentations. We have expanded these studies to examine the antigen specificity of these patients' IgG1, 2, 3, IgM, and IgA by western blot. We observed that binding of particular antigens by some antibody isotypes were more prevalent in some clinical groups as compared to others. For example, IgG3 from 13 of 19 (68%) individuals with digestive manifestations bound a 68-kDa antigen, but only 3 of 31 (9%) individuals with cardiac involvement detected this same moiety. We also found that, regardless of the clinical group, the profiles of antigens recognized by each antibody isotype differs dramatically from the profiles recognized by each other isotype. Together with our previous observations demonstrating that the levels of anti-parasite antibody isotypes correlates with the clinical form, these data suggest that overall anti-T. cruzi antibody reactivities may indeed be skewed toward different antigens in individuals with different clinical presentations.     

Neuroimaging in psychiatry

The promise of neuroimaging as an aid to diagnosis is discussed, and findings from the most accessible imaging techniques are reviewed. In addition, some of the earliest findings from functional MR imaging and other technologies are presented with several illustrations. Strategies for interpretation, critique of imaging techniques, and review of major findings for brain injury, mood, anxiety, schizophrenia, and attention deficit disorders are offered. Examples of normal and pathologic images illustrate actual cases and examples of the newer imaging technologies.     

Flexor reflex afferents reset the step cycle during fictive locomotion in the cat

It has been reported that antiarrhythmic drugs possessing the property of potassium channel blockade were most effective in preventing halothane-epinephrine induced arrhythmias. Recent attention has focused on ATP-sensitive potassium (K(ATP)) channels because of their contribution to the cardiovascular actions of volatile anesthetics. The present study was designed to evaluate whether K(ATP) channels or transient outward potassium channels (Ito) were involved in the mechanism of halothane-epinephrine arrhythmias in rat. Rats were anesthetized with halothane (1.5%), and the lungs were mechanically ventilated. The arrhythmogenic thresholds of epinephrine during halothane anesthesia were determined in 74 rats receiving saline or one of tested agents. The arrhythmogenic dose of epinephrine (ADE) was significantly increased by a K(ATP) channel opener, JTV506 (P < 0.01), and had a tendency to be increased by other K(ATP) channel openers, cromakalim, nicorandil, KRN2391 and Y 26763, but were not affected by a K(ATP) channel blocker, glibenclamide. The Ito blocker, 4-aminopyridine, also significantly increased the ADE. Epinephrine produced second-degree or complete atrioventricular block in 4 out of 7 rats receiving glibenclamide. These results suggest that Ito but not K(ATP) channels might be involved in the mechanism in producing halothane-epinephrine arrhythmias.     

Severe anoxia with and without concomitant brain atrophy and neuropsychological impairments

Significant anoxia may cause a variety of neuropathologic changes as well as cognitive deficits. We have recently seen 3 patients who have suffered severe anoxic episodes all with initial Glasgow Coma Scores (GCS) of 3 with sustained coma for 10-14 d. All 3 patients had extended hospitalizations and rehabilitation therapy. A neuropsychological test battery was administered and volumetric analyses of MRI scans were carried out in each case at least 6 mo postinjury. Two of the patients display distinct residual cognitive and neuropathologic changes while 1 patient made a remarkable recovery without evidence of significant morphological abnormality. These three cases demonstrate, that even with similar admission GCS, the outcome is variable and the degree of neuropsychological impairment appears to match the degree of morphologic abnormalities demonstrated by quantitative MR image analysis. An important finding of this study is that even though subjects with an anoxic insult exhibit severe cognitive and memory impairments along with concomitant morphologic changes, their attention/concentration abilities appear to be preserved. MR morphometry provides an excellent means by which neural structural changes can be quantified and compared to neuropsychological and behavioral outcomes.