52,664 research outputs found

    Are there gender differences in perceived sexual self-efficacy among African-American adolescents?

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    Background: African American adolescents accounted for more than half of all HIV/AIDS cases in 2009. Behavioral Strategies are needed to help lessen the incidence of HIV/AIDS among this population. Purpose: The aim of his study was to examine sexual self-efficacy practices and beliefs among African American adolescents. We also examined gender differences between African American adolescents to better understand their perceptions of sexual self-efficacy, condom use intention, and other safer sex practices and beliefs. Methods: A cross-sectional study was conducted with 214 African American adolescents using survey instruments to examine their beliefs, perception and intentions on the use of condoms, sexual self-efficacy and safe sex practices. Participants were recruited though a mass media campaign and local youth serving organizations within Sedgwick County, KS. Results: Our findings indicate significant differences exist between genders in perception of sexual self-efficacy among African American adolescents. Females were found to have higher perceived sexual self-efficacy compared to males. Having high negotiation skills and a sexual partner who approved of condom use were significant predictors for high perceived sexual self-efficacy. Conclusions: African American adolescent females were more likely to have higher perceived sexual self-efficacy then African American male adolescents. Because of the dynamics that exist in male and female relationships and the mediating role sexual self-efficacy might play in engaging in safe sex practices, it is important to design gender specific interventions in order to curb the spread of HIV/AIDS and other STDS/STIā€™s

    USSR Space Life Sciences Digest

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    Research in exobiology, life sciences technology, space biology, and space medicine and physiology, primarily using data gathered on the Salyut 6 orbital space station, is reported. Methods for predicting, diagnosing, and preventing the effects of weightlessness are discussed. Psychological factors are discussed. The effects of space flight on plants and animals are reported. Bioinstrumentation advances are noted

    Intensity-Correlation Spectroscopy

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    A survey is given of techniques for spectroscopic analysis using intensity fluctuations. Particular attention is given to counting times, the role of macroscopic sources and detectors, and the electronic constraints placed on the observations

    Microwave resonance of the reentrant insulating quantum Hall phases in the 1st excited Landau Level

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    We present measurements of the real diagonal microwave conductivity of the reentrant insulating quantum Hall phases in the first excited Landau level at temperatures below 50 mK. A resonance is detected around filling factor Ī½=2.58\nu=2.58 and weaker frequency dependence is seen at Ī½=2.42\nu=2.42 and 2.28. These measurements are consistent with the formation of a bubble phase crystal centered around these Ī½\nu at very low temperatures

    Oscillator strengths and line widths of dipole-allowed transitions in Ā¹ā“Nā‚‚ between 89.7 and 93.5ā€‚nm

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    Line oscillator strengths in the 20 electric dipole-allowed bands of Ā¹ā“Nā‚‚ in the 89.7ā€“93.5nm (111480ā€“106950cmā»Ā¹) region are reported from photoabsorptionmeasurements at an instrumental resolution of āˆ¼6mƅ (0.7cmā»Ā¹) full width at half maximum. The absorptionspectrum comprises transitions to vibrational levels of the 3pĻƒįµ¤cā€²ā‚„Ā¹Ī£įµ¤āŗ, 3pĻ€įµ¤cĀ³Ī įµ¤, and 3sĻƒgoā‚ƒĀ¹Ī įµ¤Rydberg states and of the bā€²Ā¹Ī£įµ¤āŗ and bĀ¹Ī įµ¤ valence states. The J dependences of band f values derived from the experimental line f values are reported as polynomials in Jā€²(Jā€²+1) and are extrapolated to Jā€²=0 in order to facilitate comparisons with results of coupled Schrƶdinger-equation calculations. Most bands in this study are characterized by a strong J dependence of the band f values and display anomalous P-, Q-, and R-branch intensity patterns. Predissociation line widths, which are reported for 11 bands, also exhibit strong J dependences. The f value and line width patterns can inform current efforts to develop comprehensive spectroscopic models that incorporate rotational effects and predissociation mechanisms, and they are critical for the construction of realistic atmospheric radiative-transfer models.This work was supported in part by NASA Grant No. NNG05GA03G to Wellesley College and Australian Research Council Discovery Program Grant No. DP0558962

    CMB lensing and primordial squeezed non-Gaussianity

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    Squeezed primordial non-Gaussianity can strongly constrain early-universe physics, but it can only be observed on the CMB after it has been gravitationally lensed. We give a new simple non-perturbative prescription for accurately calculating the effect of lensing on any squeezed primordial bispectrum shape, and test it with simulations. We give the generalization to polarization bispectra, and discuss the effect of lensing on the trispectrum. We explain why neglecting the lensing smoothing effect does not significantly bias estimators of local primordial non-Gaussianity, even though the change in shape can be >~10%. We also show how tau_NL trispectrum estimators can be well approximated by much simpler CMB temperature modulation estimators, and hence that there is potentially a ~10-30% bias due to very large-scale lensing modes, depending on the range of modulation scales included. Including dipole sky modulations can halve the tau_NL error bar if kinematic effects can be subtracted using known properties of the CMB temperature dipole. Lensing effects on the g_NL trispectrum are small compared to the error bar. In appendices we give the general result for lensing of any primordial bispectrum, and show how any full-sky squeezed bispectrum can be decomposed into orthogonal modes of distinct angular dependence.Comment: 22 pages, 6 figures; minor edits to match published versio

    Voice control of the space shuttle video system

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    A pilot voice control system developed at the Jet Propulsion Laboratory (JPL) to test and evaluate the feasibility of controlling the shuttle TV cameras and monitors by voice commands utilizes a commercially available discrete word speech recognizer which can be trained to the individual utterances of each operator. Successful ground tests were conducted using a simulated full-scale space shuttle manipulator. The test configuration involved the berthing, maneuvering and deploying a simulated science payload in the shuttle bay. The handling task typically required 15 to 20 minutes and 60 to 80 commands to 4 TV cameras and 2 TV monitors. The best test runs show 96 to 100 percent voice recognition accuracy

    Quasar Microlensing at High Magnification and the Role of Dark Matter: Enhanced Fluctuations and Suppressed Saddlepoints

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    Contrary to naive expectation, diluting the stellar component of the lensing galaxy in a highly magnified system with smoothly distributed ``dark'' matter increases rather than decreases the microlensing fluctuations caused by the remaining stars. For a bright pair of images straddling a critical curve, the saddlepoint (of the arrival time surface) is much more strongly affected than the associated minimum. With a mass ratio of smooth matter to microlensing matter of 4:1, a saddlepoint with a macro-magnification of mu = 9.5 will spend half of its time more than a magnitude fainter than predicted. The anomalous flux ratio observed for the close pair of images in MG0414+0534 is a factor of five more likely than computed by Witt, Mao and Schechter if the smooth matter fraction is as high as 93%. The magnification probability histograms for macro-images exhibit distinctly different structure that varies with the smooth matter content, providing a handle on the smooth matter fraction. Enhanced fluctuations can manifest themselves either in the temporal variations of a lightcurve or as flux ratio anomalies in a single epoch snapshot of a multiply imaged system. While the millilensing simulations of Metcalf and Madau also give larger anomalies for saddlepoints than for minima, the effect appears to be less dramatic for extended subhalos than for point masses. Morever, microlensing is distinguishable from millilensing because it will produce noticeable changes in the magnification on a time scale of a decade or less.Comment: As accepted for publication in ApJ. 17 pages. Substantial revisions include a discussion of constant M/L models and the calculation of a "photometric" dark matter fraction for MG0414+053
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