Numerical simulation of the influence of the orifice aperture on the flow around a teeth-shaped obstacle

The sound generated during the production of the sibilant [s] results from the impact of a turbulent jet on the incisors. Several geometric characteristics of the oral tract can affect the properties of the flow-induced noise so that the characterization of the influence of different geometric parameters on the acoustic sources properties allows determining control factors of the noise production. In this study, a simplified vocal tract/teeth geometric model is used to numerically investigate the flow around a teeth-shaped obstacle placed in a channel and to analyze the influence of the aperture at the teeth on the spectral properties of the fluctuating pressure force exerted on the surface of the obstacle, which is at the origin of the dipole sound source. The results obtained for Re = 4000 suggest that the aperture of the constriction formed by the teeth modifies the characteristics of the turbulent jet downstream of the teeth. Thus, the variations of the flow due to the modification of the constriction aperture lead to variations of the spectral properties of the sound source even if the levels predicted are lower than during the production of real sibilant fricative

Background Radioactivity in the Decorah Fault Region

A known fault site at Decorah, Iowa, was surveyed for indicative variations in surface radioactivity. A portable ionization chamber revealed significant increases in gamma ray intensity at several locations. At one point the radiation level was 70% greater than the background intensity. Measurements repeated one year later verified this pattern. Radiation contours were plotted over an extensive area in the city of Decorah. This map, with other items of supporting evidence, indicated a possible fault strike of approximately N 55° W

Speech Communication

Contains reports on two research projects.National Institutes of Health (Grant 2 ROl1 NS04332)National Institutes of Health (Training Grant 5 T32 NS07040)C.J. LeBel FellowshipsNational Science Foundation (Grant BNS77-26871

Outer-Sphere Contributions to the Electronic Structure of Type Zero Copper Proteins

Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 copper proteins. In recent work, we have found that copper ET sites in proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding

HIV Testing of At Risk Patients in a Large Integrated Health Care System

OBJECTIVE: Early identification of HIV infection is critical for patients to receive life-prolonging treatment and risk-reduction counseling. Understanding HIV screening practices and barriers to HIV testing is an important prelude to designing successful HIV screening programs. Our objective was to evaluate current practice patterns for identification of HIV. METHODS: We used a retrospective cohort analysis of 13,991 at-risk patients seen at 4 large Department of Veterans Affairs (VA) health-care systems. We also reviewed 1,100 medical records of tested patients. We assessed HIV testing rates among at-risk patients, the rationale for HIV testing, and predictors of HIV testing and of HIV infection. RESULTS: Of the 13,991 patients at risk for HIV, only 36% had been HIV-tested. The prevalence of HIV ranged from 1% to 20% among tested patients at the 4 sites. Approximately 90% of patients who were tested had a documented reason for testing. CONCLUSION: One-half to two-thirds of patients at risk for HIV had not been tested within our selected VA sites. Among tested patients, the rationale for HIV testing was well documented. Further testing of at-risk patients could clearly benefit patients who have unidentified HIV infection by providing earlier access to life-prolonging therapy

Regulation of mitochondrial morphogenesis by annexin a6.

Mitochondrial homeostasis is critical in meeting cellular energy demands, shaping calcium signals and determining susceptibility to apoptosis. Here we report a role for anxA6 in the regulation of mitochondrial morphogenesis, and show that in cells lacking anxA6 mitochondria are fragmented, respiration is impaired and mitochondrial membrane potential is reduced. In fibroblasts from AnxA6(-/-) mice, mitochondrial Ca(2+) uptake is reduced and cytosolic Ca(2+) transients are elevated. These observations led us to investigate possible interactions between anxA6 and proteins with roles in mitochondrial fusion and fission. We found that anxA6 associates with Drp1 and that mitochondrial fragmentation in AnxA6(-/-) fibroblasts was prevented by the Drp1 inhibitor mdivi-1. In normal cells elevation of intracellular Ca(2+) disrupted the interaction between anxA6 and Drp1, displacing anxA6 to the plasma membrane and promoting mitochondrial fission. Our results suggest that anxA6 inhibits Drp1 activity, and that Ca(2+)-binding to anxA6 relieves this inhibition to permit Drp1-mediated mitochondrial fission