Fastener Design Course [Workbook]

Richard T. Barrett, Senior Aerospace Engineer of NASA Lewis Research Center presents a comprehensive course on fastener design. A recognized expert in the field of fastener technology Mr. Barrett combines lecture, charts, illustrations with real-world experiences. Topics covered include: materials, plantings and coatings, locking methods threads, joint stiffness, rivets, inserts, nut plates, thread lubricants, design criteria, etc. These presentation slides accompany the DVD

Ethnic differences in proximal and distal tubular sodium reabsorption are heritable in black and white populations.

BACKGROUND: Segmental handling of sodium along the proximal and distal nephron might be heritable and different between black and white participants. METHODS: We randomly recruited 95 nuclear families of black South African ancestry and 103 nuclear families of white Belgian ancestry. We measured the (FENa) and estimated the fractional renal sodium reabsorption in the proximal (RNaprox) and distal (RNadist) tubules from the clearances of endogenous lithium and creatinine. In multivariable analyses, we studied the relation of RNaprox and RNadist with FENa and estimated the heritability (h) of RNaprox and RNadist. RESULTS: Independent of urinary sodium excretion, South Africans (n = 240) had higher RNaprox (unadjusted median, 93.9% vs. 81.0%; P < 0.001) than Belgians (n = 737), but lower RNadist (91.2% vs. 95.1%; P < 0.001). The slope of RNaprox on FENa was steeper in Belgians than in South Africans (-5.40 +/- 0.58 vs. -0.78 +/- 0.58 units; P < 0.001), whereas the opposite was true for the slope of RNadist on FENa (-3.84 +/- 0.19 vs. -13.71 +/- 1.30 units; P < 0.001). h of RNaprox and RNadist was high and significant (P < 0.001) in both countries. h was higher in South Africans than in Belgians for RNaprox (0.82 vs. 0.56; P < 0.001), but was similar for RNadist (0.68 vs. 0.50; P = 0.17). Of the filtered sodium load, black participants reabsorb more than white participants in the proximal nephron and less postproximally. CONCLUSION: Segmental sodium reabsorption along the nephron is highly heritable, but the capacity for regulation in the proximal and postproximal tubules differs between whites and blacks

Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled DC electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on DC electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains.Comment: 17 pages (including references), 7 figure

Prevalence of left ventricular diastolic dysfunction in a general population

BACKGROUND: Because the process of myocardial remodelling starts before the onset of symptoms, recent heart failure (HF) guidelines place special emphasis on the detection of subclinical left ventricular (LV) systolic and diastolic dysfunction and the timely identification of risk factors for HF. Our goal was to describe the prevalence and determinants (risk factors) of LV diastolic dysfunction in a general population and to compare the amino terminal probrain natriuretic peptide level across groups with and without diastolic dysfunction. METHODS AND RESULTS: In a randomly recruited population sample (n=539; 50.5% women; mean age, 52.5 years), we measured early and late diastolic peak velocities of mitral inflow (E and A), pulmonary vein flow by pulsed-wave Doppler, and the mitral annular velocities (Ea and Aa) at 4 sites by tissue Doppler imaging. A healthy subsample of 239 subjects (mean age, 43.7 years) provided age-specific cutoff limits for normal E/A and E/Ea ratios and the differences in duration between the mitral A and the reverse pulmonary vein flows during atrial systole (DeltaAd-ARd). The number of subjects in diastolic dysfunction groups 1 (impaired relaxation), 2 (elevated LV end-diastolic filling pressure), and 3 (elevated E/Ea and abnormally low E/A) were 53 (9.8%), 76 (14.1%), and 18 (3.4%), respectively. We used Delta(Ad<ARd+10) to confirm possible elevation of LV filling pressures in group 2. Compared with subjects with normal diastolic function (n=392, 72.7%), group 1 (209 versus 251 pmol/L; P=0.015) and group 2 (209 versus 275 pmol/L; P=0.0003) but not group 3 (209 versus 224 pmol/L; P=0.65) had a significantly higher adjusted NT-probrain natriuretic peptide. Higher age, body mass index, heart rate, systolic blood pressure, serum insulin, and creatinine were significantly associated with a higher risk of LV diastolic dysfunction. CONCLUSIONS: The overall prevalence of LV diastolic dysfunction in a random sample of a general population, as estimated from echocardiographic measurements, was as high as 27.3%