636 research outputs found
Low speed testing of the inlets designed for a tamden-fan V/STOL nacelle
An approximately 0.25 scale model of a tandem fan nacelle, designed for a subsonic V/STOL aircraft, was tested in a Lewis wind tunnel. Model variables included long and short aft inlet cowls and the addition of exterior strakes to the short inlet cowl. Inlet pressure recoveries and distortion were measured at pitch angles to 40 deg and at combinations of pitch and yaw to 30 deg. Airspeeds covered a range to 135 knots (69 m/sec). The short aft inlet with added strakes had the best aerodynamic performance and is considered suitable for the intended V/STOL application
Effects of Divalent Metal Cations and Resistance Mechanisms of the Cyanobacterium Synechococcus SP. Strain PCC 7942
Cyanobacteria exhibit an extraordinary resistance to many environmental factors including nutrient limitation, changes in hydrogen ion concentration, temperature, and light extremes. A better understanding of the biological effects and response mechanisms of cyanobacteria to heavy metal exposure could be used to develop these bacteria for use in bioremediation. Synechococcus sp. strain PCC 7942 expresses messenger RNA for the stress protein GroEL and for the metal-binding protein metallothionein in response to a wide range of divalent metal ion concentrations. Although groEL is expressed at low levels regardless of environmental conditions, a high rate of transcription is initiated within 15 minutes following exposure to divalent metal cations at concentrations ranging from 10 ĀµM to 100 ĀµM for copper and zinc, and concentrations as low as 1 ĀµM for cadmium. Transcript levels return to normal within one hour following exposure to each metal. Induction of the metallothionein operon also occurs within 15 minutes of these exposures. We speculate that these resistance mechanisms are working together to protect the cell from damage
Misanthropic Person Memory when the Need to Self-Enhance is Absent
This research examined the role that the removal of the need or ability to self-enhance can play in the misanthropic processing of attributed behavioral information (i.e., remembering best negative, internally attributed behaviors and positive externally attributed behaviors). Experiment 1demonstrated that removing a personās need to self-enhance by increasing his or her self-esteem eliminated misanthropic memory, whereas misanthropy was preserved for control participants and perceivers who had experienced a decrease in self-esteem. Furthermore, controlling for participantsā self-evaluations eliminated the memory pattern differences between the two experimental conditions. Experiment 2 demonstrated that canceling the ability to self-enhance by having perceivers form an impression of themselves eliminated the misanthropy effect. However, the misanthropy effect was replicated when perceivers learned about an unknown other. The results were discussed with regard to the situations and factors that can increase or reduce the need to self-enhance and their implications for social information processing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68679/2/10.1177_0146167299025002011.pd
āI h 8 uā: Findings from a five-year study of text and e-mail bullying
Copyright @ 2010 British Educational Research Association. The final version of this article is available at the link below.This study charts reports of nasty or threatening text and e-mail messages received by students in academic years 7 and 8 (11-13 years of age) attending 13 secondary schools in the North of England between 2002-2006. Annual surveys were undertaken on behalf of the local education authority (LEA) to monitor bullying. Results indicated that, over five years, the number of pupils receiving one or more nasty or threatening text messages or e-mails increased significantly, particularly among girls. However, receipt of frequent nasty or threatening text and e-mail messages remained relatively stable. For boys, being a victim of direct-physical bullying was associated with receiving nasty or threatening text and e-mail messages; for girls it was being unpopular among peers. Boys received more hate-related messages and girls were primarily the victims of name-calling, Findings are discussed with respect to theoretical and policy developments, and recommendations for future research are offered
Differential Influence of the Great Recession on Political Participation among Race and Ethnic Groups
Our study seeks to understand the role of perceived economic stress of the Great Recession on political participation among blacks, whites and Latinos. Methods. We use the 2012 Collaborative Multi-Racial Political Study and negative binomial regression to examine the impact of financial hardship on black, Hispanic, and white political participation. Results. We find that political participation among whites is unaffected by the Great Recession and is largely motivated by political interest. Blacks are mobilized by financial hardship even after controlling for political enthusiasm and linked fate. Hispanics have the lowest level of political participation. Conclusion. Overall, we conclude that the Great Recession did affect political behavior but differently across race and ethnic groups; specifically, Hispanics were least likely to politically engage if they experienced negative consequences of the Great Recession
Internet Use among Ugandan Adolescents: Implications for HIV Intervention
BACKGROUND: The Internet is fast gaining recognition as a powerful, low-cost method to deliver health intervention and prevention programs to large numbers of young people across diverse geographic regions. The feasibility and accessibility of Internet-based health interventions in resource-limited settings, where cost-effective interventions are most needed, is unknown. To determine the utility of developing technology-based interventions in resource-limited settings, availability and patterns of usage of the Internet first need to be assessed. METHODS AND FINDINGS: The Uganda Media and You Survey was a cross-sectional survey of Internet use among adolescents (ages 12ā18 years) in Mbarara, Uganda, a municipality mainly serving a rural population in sub-Saharan Africa. Participants were randomly selected among eligible students attending one of five participating secondary day and boarding schools in Mbarara, Uganda. Of a total of 538 students selected, 93% (500) participated. Of the total respondents, 45% (223) reported ever having used the Internet, 78% (175) of whom reported going online in the previous week. As maternal education increased, so too did the odds of adolescent Internet use. Almost two in five respondents (38% [189]) reported already having used a computer or the Internet to search for health information. Over one-third (35% [173]) had used the computer or Internet to find information about HIV/AIDS, and 20% (102) had looked for sexual health information. Among Internet users, searching for HIV/AIDS information on a computer or online was significantly related to using the Internet weekly, emailing, visiting chat rooms, and playing online games. In contrast, going online at school was inversely related to looking for HIV/AIDS information via technology. If Internet access were free, 66% (330) reported that they would search for information about HIV/AIDS prevention online. CONCLUSIONS: Both the desire to use, and the actual use of, the Internet to seek sexual health and HIV/AIDS information is high among secondary school students in Mbarara. The Internet may be a promising strategy to deliver low-cost HIV/AIDS risk reduction interventions in resource-limited settings with expanding Internet access
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Adolescent Abstinence and Unprotected Sex in CyberSenga, an Internet-Based HIV Prevention Program: Randomized Clinical Trial of Efficacy
Context Cost-effective, scalable programs are urgently needed in countries deeply affected by HIV. Methods: This parallel-group RCT was conducted in four secondary schools in Mbarara, Uganda. Participants were 12 years and older, reported past-year computer or Internet use, and provided informed caregiver permission and youth assent. The intervention, CyberSenga, was a five-hour online healthy sexuality program. Half of the intervention group was further randomized to receive a booster at four-months post-intervention. The control arm received ātreatment as usualā (i.e., school-delivered sexuality programming). The main outcome measures were: 1) condom use and 2) abstinence in the past three months at six-months' post-intervention. Secondary outcomes were: 1) condom use and 2) abstinence at three-month's post-intervention; and 6-month outcomes by booster exposure. Analyses were intention to treat. Results: All 416 eligible youth were invited to participate, 88% (n = 366) of whom enrolled. Participants were randomized to the intervention (n = 183) or control (n = 183) arm; 91 intervention participants were further randomized to the booster. No statistically significant results were noted among the main outcomes. Among the secondary outcomes: At three-month follow-up, trends suggested that intervention participants (81%) were more likely to be abstinent than control participants (74%; p = 0.08), and this was particularly true among youth who were abstinent at baseline (88% vs. 77%; p = 0.02). At six-month follow-up, those in the booster group (80%) reported higher rates of abstinence than youth in the intervention, no booster (57%) and control (55%) groups (p = 0.15); they also reported lower rates of unprotected sex (5%) compared to youth in the intervention, no booster (24%) and control (21%) groups (p = 0.21) among youth sexually active at baseline. Conclusions: The CyberSenga program may affect HIV preventive behavior among abstinent youth in the short term and, with the booster, may also promote HIV preventive behavior among sexually active youth in the longer term. Trial Registration NCT00906178
Advanced Hybrid Spacesuit Concept Featuring Integrated Open Loop and Closed Loop Ventilation Systems
A document discusses the design and prototype of an advanced spacesuit concept that integrates the capability to function seamlessly with multiple ventilation system approaches. Traditionally, spacesuits are designed to operate both dependently and independently of a host vehicle environment control and life support system (ECLSS). Spacesuits that operate independent of vehicle-provided ECLSS services must do so with equipment selfcontained within or on the spacesuit. Suits that are dependent on vehicle-provided consumables must remain physically connected to and integrated with the vehicle to operate properly. This innovation is the design and prototype of a hybrid spacesuit approach that configures the spacesuit to seamlessly interface and integrate with either type of vehicular systems, while still maintaining the ability to function completely independent of the vehicle. An existing Advanced Crew Escape Suit (ACES) was utilized as the platform from which to develop the innovation. The ACES was retrofitted with selected components and one-off items to achieve the objective. The ventilation system concept was developed and prototyped/retrofitted to an existing ACES. Components were selected to provide suit connectors, hoses/umbilicals, internal breathing system ducting/ conduits, etc. The concept utilizes a lowpressure- drop, high-flow ventilation system that serves as a conduit from the vehicle supply into the suit, up through a neck seal, into the breathing helmet cavity, back down through the neck seal, out of the suit, and returned to the vehicle. The concept also utilizes a modified demand-based breathing system configured to function seamlessly with the low-pressure-drop closed-loop ventilation system
Star Formation and Young Population of the HII Complex Sh2-294
The Sh2-294 HII region ionized by a single B0V star features several infrared
excess sources, a photodissociation region, and also a group of reddened stars
at its border. The star formation scenario in the region seems to be quite
complex. In this paper, we present follow-up results of Sh2-294 HII region at
3.6, 4.5, 5.8, and 8.0 microns observed with the Spitzer Space Telescope
Infrared Array Camera (IRAC), coupled with H2 (2.12 microns) observation, to
characterize the young population of the region and to understand its star
formation history. We identified 36 young stellar object (YSO, Class I, Class
II and Class I/II) candidates using IRAC color-color diagrams. It is found that
Class I sources are preferentially located at the outskirts of the HII region
and associated with enhanced H2 emission; none of them are located near the
central cluster. Combining the optical to mid-infrared (MIR) photometry of the
YSO candidates and using the spectral energy distribution fitting models, we
constrained stellar parameters and the evolutionary status of 33 YSO
candidates. Most of them are interpreted by the model as low-mass (< 4 solar
masses) YSOs; however, we also detected a massive YSO (~9 solar masses) of
Class I nature, embedded in a cloud of visual extinction of ~24 mag. Present
analysis suggests that the Class I sources are indeed younger population of the
region relative to Class II sources (age ~ 4.5 x 10^6 yr). We suggest that the
majority of the Class I sources, including the massive YSOs, are
second-generation stars of the region whose formation is possibly induced by
the expansion of the HII region powered by a ~ 4 x 10^6 yr B0 main-sequence
star.Comment: 12 pages, 7 figures, 2 tables. Accepted for publication in The
Astrophysical Journa
Digging into NGC 6334I(N): Multiwavelength Imaging of a Massive Protostellar Cluster
We present a high-resolution, multi-wavelength study of the massive
protostellar cluster NGC 6334I(N) that combines new spectral line data from the
Submillimeter Array (SMA) and VLA with a reanalysis of archival VLA continuum
data, 2MASS and Spitzer images. As shown previously, the brightest 1.3 mm
source SMA1 contains substructure at subarcsecond resolution, and we report the
first detection of SMA1b at 3.6 cm along with a new spatial component at 7 mm
(SMA1d). We find SMA1 (aggregate of sources a, b, c, and d) and SMA4 to be
comprised of free-free and dust components, while SMA6 shows only dust
emission. Our 1.5" resolution 1.3 mm molecular line images reveal substantial
hot-core line emission toward SMA1 and to a lesser degree SMA2. We find CH3OH
rotation temperatures of 165\pm 9 K and 145\pm 12 K for SMA1 and SMA2,
respectively. We estimate a diameter of 1400 AU for the SMA1 hot core emission,
encompassing both SMA1b and SMA1d, and speculate that these sources comprise a
>800 AU separation binary that may explain the previously-suggested precession
of the outflow emanating from the SMA1 region. The LSR velocities of SMA1,
SMA2, and SMA4 all differ by 1-2 km/s. Outflow activity from SMA1, SMA2, SMA4,
and SMA6 is observed in several molecules including SiO(5--4) and IRAC 4.5
micron emission; 24 micron emission from SMA4 is also detected. Eleven water
maser groups are detected, eight of which coincide with SMA1, SMA2, SMA4, and
SMA6. We also detect a total of 83 Class I CH3OH 44GHz maser spots which likely
result from the combined activity of many outflows. Our observations paint the
portrait of multiple young hot cores in a protocluster prior to the stage where
its members become visible in the near-infrared.Comment: Accepted to ApJ, 24 pages, a full high resolution version is
available at http://www.cv.nrao.edu/~cbrogan/ms.long.pd
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