Advanced space communications architecture study. Volume 1: Executive summary

The technical feasibility and economic viability of satellite system architectures that are suitable for Customer Premise Service (CPS) communications is investigated. System evaluation is performed at 30/20 GHz (Ka-band); however, the system architectures examined are equally applicable to 14/11 GHz (Ku-band). Emphasis is placed on system that permit low cost user terminals. Frequency Division Multiple Access (FDMA) is used on the uplink, with typically 10,000 simultaneous accesses per satellite, each of 64 kbps. Bulk demodulators onboard the satellite, in combination with a baseband multiplexer, convert the many narrowband uplink signals into a small number of wideband data streams for downlink transmission. Single hop network interconnectivity is accomplished through use of downlink scanning beams. Each satellite is estimated to weigh 5600 lb and consume 6850W of power; the corresponding payload totals are 1000 lb and 5000W. Nonrecurring satellite cost is estimated at $110 million, with the first unit cost at$113 million. In large quantities, the user terminal cost estimate is $25,000

Advanced space communications architecture study. Volume 2: Technical report

The technical feasibility and economic viability of satellite system architectures that are suitable for customer premise service (CPS) communications are investigated. System evaluation is performed at 30/20 GHz (Ka-band); however, the system architectures examined are equally applicable to 14/11 GHz (Ku-band). Emphasis is placed on systems that permit low-cost user terminals. Frequency division multiple access (FDMA) is used on the uplink, with typically 10,000 simultaneous accesses per satellite, each of 64 kbps. Bulk demodulators onboard the satellite, in combination with a baseband multiplexer, convert the many narrowband uplink signals into a small number of wideband data streams for downlink transmission. Single-hop network interconnectivity is accomplished via downlink scanning beams. Each satellite is estimated to weigh 5600 lb and consume 6850W of power; the corresponding payload totals are 1000 lb and 5000 W. Nonrecurring satellite cost is estimated at $110 million, with the first-unit cost at$113 million. In large quantities, the user terminal cost estimate is $25,000. For an assumed traffic profile, the required system revenue has been computed as a function of the internal rate of return (IRR) on invested capital. The equivalent user charge per-minute of 64-kbps channel service has also been determined

Underrepresented Minorities in Medical School Admissions: A Qualitative Study.

Phenomenon: This study explored Black/African American and Hispanic/Latino medical students\u27 perceptions of the medical school admissions process. Previous research has explored other elements of the medical education continuum. However, little is known regarding minorities\u27 perceptions of navigating the medical school admissions process. To address this gap in the literature, this exploratory study suggests a conceptual model describing why minorities apply to medical school and the influences affecting their admissions experience. APPROACH: This qualitative study utilized a grounded theory approach. Between December 2012 and January 2014, the principal researcher conducted one-on-one telephone and in-person small-group interviews, as well as web-based telephone feedback sessions, with Black/African American and Hispanic/Latino medical students. FINDINGS: Thirty-three students participated, including 23 Black/African American and 10 Hispanic/Latino medical students. Participants represented 25 U.S. allopathic medical schools. Emergent themes are categorized under 2 headings: (a) motivations for a career in medicine and (b) barriers and supports. Motivations for a career in medicine include perceived fit, prior experience or knowledge, encouragement and role models, desire to help others, interest in science, and perceived benefits. Barriers and supports included information, guidance and social support, financial and academic factors, and persistence. Insights: Building on theories of student college choice and academic capital formation, the researcher\u27s analysis and interpretations result in the proposal of a conceptual model describing minority applicants\u27 experience in medical school admissions. The study also suggests research and practice implications related to premedical advising, mentoring, financial assistance, information, outreach, and data collection