100 research outputs found
Conducting Research on the International Space Station Using the EXPRESS Rack Facilities
EXPRESS Racks provide capability for payload access to ISS resources. The successful on-orbit operations and versatility of the EXPRESS Rack has facilitated the operations of many scientific areas, with the promise of continued payload support for years to come. EXPRESS Racks are currently deployed in the US Lab, Columbus and JEM. Process improvements and enhancements continue to improve the accommodations and make the integration and operations process more efficient. Payload Integration Managers serve as the primary interface between the ISS Program and EXPRESS Payload Developers. EXPRESS Project coordinates across multiple functional areas and organizations to ensure integrated EXPRESS Rack and subrack products and hardware are complete, accurate, on time, safe, and certified for flight. NASA is planning to expand the EXPRESS payload capacity by developing new Basic Express Racks expected to be on ISS in 2018
Conducting Research on the International Space Station Using the EXPRESS Rack Facilities
Eight "Expedite the Processing of Experiments to Space Station" (EXPRESS) Rack facilities are located within the International Space Station (ISS) laboratories to provide standard resources and interfaces for the simultaneous and independent operation of multiple experiments within each rack. Each EXPRESS Rack provides eight Middeck Locker Equivalent locations and two drawer locations for powered experiment equipment, also referred to as sub-rack payloads. Payload developers may provide their own structure to occupy the equivalent volume of one, two, or four lockers as a single unit. Resources provided for each location include power (28 Vdc, 0-500 W), command and data handling (Ethernet, RS-422, 5 Vdc discrete, +/- 5 Vdc analog), video (NTSC/RS 170A), and air cooling (0-200 W). Each rack also provides water cooling (500 W) for two locations, one vacuum exhaust interface, and one gaseous nitrogen interface. Standard interfacing cables and hoses are provided on-orbit. One laptop computer is provided with each rack to control the rack and to accommodate payload application software. Four of the racks are equipped with the Active Rack Isolation System to reduce vibration between the ISS and the rack. EXPRESS Racks are operated by the Payload Operations Integration Center at Marshall Space Flight Center and the sub-rack experiments are operated remotely by the investigating organization. Payload Integration Managers serve as a focal to assist organizations developing payloads for an EXPRESS Rack. NASA provides EXPRESS Rack simulator software for payload developers to checkout payload command and data handling at the development site before integrating the payload with the EXPRESS Functional Checkout Unit for an end-to-end test before flight. EXPRESS Racks began supporting investigations onboard ISS on April 24, 2001 and will continue through the life of the ISS
Urinary eicosanoid metabolites in HIV-infected women with central obesity switching to raltegravir: an analysis from the women, integrase, and fat accumulation trial.
Chronic inflammation is a hallmark of HIV infection. Eicosanoids reflect inflammation, oxidant stress, and vascular health and vary by sex and metabolic parameters. Raltegravir (RAL) is an HIV-1 integrase inhibitor that may have limited metabolic effects. We assessed urinary F2-isoprostanes (F2-IsoPs), prostaglandin E2 (PGE-M), prostacyclin (PGI-M), and thromboxane B2 (TxB2) in HIV-infected women switching to RAL-containing antiretroviral therapy (ART). Thirty-seven women (RAL = 17; PI/NNRTI = 20) with a median age of 43 years and BMI 32 kg/m(2) completed week 24. TxB2 increased in the RAL versus PI/NNRTI arm (+0.09 versus -0.02; P = 0.06). Baseline PGI-M was lower in the RAL arm (P = 0.005); no other between-arm cross-sectional differences were observed. In the PI/NNRTI arm, 24-week visceral adipose tissue change correlated with PGI-M (rho = 0.45; P = 0.04) and TxB2 (rho = 0.44; P = 0.005) changes, with a trend seen for PGE-M (rho = 0.41; P = 0.07). In an adjusted model, age ā„ 50 years (N = 8) was associated with increased PGE-M (P = 0.04). In this randomized trial, a switch to RAL did not significantly affect urinary eicosanoids over 24 weeks. In women continuing PI/NNRTI, increased visceral adipose tissue correlated with increased PGI-M and PGE-M. Older age (ā„ 50) was associated with increased PGE-M. Relationships between aging, adiposity, ART, and eicosanoids during HIV-infection require further study
The role of the most luminous, obscured AGN in galaxy assembly at z~2
We present HST WFC3 F160W imaging and infrared spectral energy distributions
for twelve extremely luminous, obscured AGN at , selected via "Hot,
Dust Obscured" mid-infrared colors. Their infrared luminosities span
L, making them among the most luminous objects in
the Universe at . In all cases the infrared emission is consistent with
arising at least in most part from AGN activity. The AGN fractional
luminosities are higher than those in either sub-millimeter galaxies, or AGN
selected via other mid-infrared criteria. Adopting the , M and
morphological parameters, together with traditional classification boundaries,
infers that three quarters of the sample as mergers. Our sample do not,
however, show any correlation between the considered morphological parameters
and either infrared luminosity or AGN fractional luminosity. Moreover, their
asymmetries and effective radii are distributed identically to those of massive
galaxies at . We conclude that our sample is not preferentially
associated with mergers, though a significant merger fraction is still
plausible. Instead, we propose that our sample are examples of the massive
galaxy population at that harbor a briefly luminous, "flickering" AGN,
and in which the and M values have been perturbed, due to either the
AGN, and/or the earliest formation stages of a bulge in an inside-out manner.
Furthermore, we find that the mass assembly of the central black holes in our
sample leads the mass assembly of any bulge component. Finally, we speculate
that our sample represent a small fraction of the immediate antecedents of
compact star-forming galaxies at .Comment: ApJ, accepted. Updated to reflect the accepted versio
Three-Terminal Si-Based Negative Differential Resistance Circuit Element with Adjustable Peak-to-Valley Current Ratios Using a Monolithic Vertical Integration
Si-based resonant bipolar transistors are demonstrated by the monolithic vertical integration of Si-based resonant interband tunnel diodes atop the emitter of Si/SiGe heterojunction bipolar transistors ~HBTs! on a silicon substrate. In the common emitter configuration, IC versus VCE shows negative differential resistance characteristics. The resulting characteristics are adjustable peak-to-valley current ratios, including infinite and negative values, and tailorable peak current densities by the control of the HBT base current under room temperature operation. With the integrated RITD-HBT combination, latching properties which are the key operating principle for high-speed mixed-signal, memory, and logic circuitry, are experimentally demonstrated
Mid-infrared Selection of Active Galactic Nuclei with the Wide-Field Infrared Survey Explorer. I. Characterizing WISE-selected Active Galactic Nuclei in COSMOS
The Wide-field Infrared Survey Explorer (WISE) is an extremely capable and efficient black hole finder. We present a simple mid-infrared color criterion, W1 ā W2 ā„ 0.8 (i.e., [3.4]ā[4.6] ā„0.8, Vega), which identifies 61.9 Ā± 5.4 active galactic nucleus (AGN) candidates per deg^2 to a depth of W2 ~ 15.0. This implies a much larger census of luminous AGNs than found by typical wide-area surveys, attributable to the fact that mid-infrared selection identifies both unobscured (type 1) and obscured (type 2) AGNs. Optical and soft X-ray surveys alone are highly biased toward only unobscured AGNs, while this simple WISE selection likely identifies even heavily obscured, Compton-thick AGNs. Using deep, public data in the COSMOS field, we explore the properties of WISE-selected AGN candidates. At the mid-infrared depth considered, 160 Ī¼Jy at 4.6 Ī¼m, this simple criterion identifies 78% of Spitzer mid-infrared AGN candidates according to the criteria of Stern et al. and the reliability is 95%. We explore the demographics, multiwavelength properties and redshift distribution of WISE-selected AGN candidates in the COSMOS field
Chavis Heights Public Housing Community, Southeast Raleigh, Wake County, North Carolina : action-oriented community diagnosis : findings and next steps of action
During the 2002-2003 academic year, six students from the Department of Health Behavior and Health Education within the University of North Carolina at Chapel Hill School of Public Health, under the guidance of a preceptor from Wake County Human Services and faculty of the program, conducted an Action Oriented Community Diagnosis (AOCD) of the Chavis Heights public housing community in Southeast Raleigh, Wake County, North Carolina. The purpose of this document is to summarize the AOCD process, present findings, and suggest future action steps to improve life within the community. The paper begins with an introduction to the AOCD process, a basic history of the Chavis Heights public housing community, and some demographic information about Chavis Heights residents. This is followed by a description of the qualitative methodology used by the student team to conduct the community diagnosis. Findings from the data collection process are reported on six prominent domains identified during the AOCD process; those domains include crime, sense of community, services, youth, health, and schools/education. Under each domain, emergent themes are discussed, including a presentation of insidersā and outsidersā perspectives, secondary data analysis, and participant observations. Conclusions are then drawn about how well the four sources of information about the Chavis Heights community match up. A description of the community meeting, the culminating event of the diagnosis, and potential action steps discussed at this event are also discussed. This is followed by conclusions and recommendations made by the student team at the end of the diagnosis. While residents of Chavis Heights face many challenges, the AOCD shows that community members and service providers working in the area agree on which issues should receive priority attention. It is clear that the Chavis Heights residents have a number of strengths, including a strong devotion to the many children who live within the community. The coordination of outside resources and community input would certainly enhance the lives of many community members. It is the student teamās hope that with improved communication between service providers and community members, this document can serve as a useful resource for those working to make Chavis Heights a better place in the years to come.Master of Public Healt
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