Space shuttle avionics system

The Space Shuttle avionics system, which was conceived in the early 1970's and became operational in the 1980's represents a significant advancement of avionics system technology in the areas of systems and redundacy management, digital data base technology, flight software, flight control integration, digital fly-by-wire technology, crew display interface, and operational concepts. The origins and the evolution of the system are traced; the requirements, the constraints, and other factors which led to the final configuration are outlined; and the functional operation of the system is described. An overall system block diagram is included

Space Station Freedom research capabilities

NASA's plan for enhancing space-based research capabilities begins with extended-duration Space Shuttle missions that will double the research capability currently provided by Spacelab and culminate in Space Station Freedom. The 14-day USML 1 mission flown on the Space Shuttle in June 1992 was a space station precursor mission, dedicated to microgravity and life science research. Freedom will be a permanent space-based research facility, providing a working environment nearly free of buoyancy-driven convection, sedimentation, and hydrostatic pressure and featuring access to the ultra-high vacuum of space (for external payloads). In its crew-tended phase, Space Station Freedom will provide 40 times Spacelab's capability, and in its permanently occupied phase, Freedom will provide 110 times Spacelab's capability. (The Russian space station, Mir, offers 26 times Spacelab's capabilities.) According to NASA's current schedule, the first launch of a space station element will take place in November 1995, with permanently occupied capability planned for September 1999. This year, NASA will conduct space station critical design reviews (CDR's). Work package design reviews will take place from February to April 1993, followed by a systems CDR

Design and Properties of Novel Substituted Borosilicate Bioactive Glasses and Their Glass-Ceramic Derivatives

Three novel borosilicate bioactive glasses (BBGs) of general formula of 0.05Na2O·0.35x·0.20B2O3·0.40SiO2 (molar ratio, where x = MgO or CaO or SrO) were prepared and used to investigate the effect of crystallization on their properties including cytotoxicity. The three postmelt compositions were determined using X-ray fluorescence spectroscopy, and crystallization events were studied using differential thermal analysis and X-ray diffraction. This information was used to determine heat treatments to prepare glass-ceramics by controlled crystallization. X-ray diffraction analysis and Fourier transform infrared spectroscopy showed that, after higher heat treatment temperatures (800–900 °C), borosilicate bioactive glass-ceramics (BBGCs) contained mainly borate and silicate crystalline phases. Specifically, BBG-Mg, BBG-Ca, and BBG-Sr glass-ceramics detected the presence of magnesium silicate-Mg2(SiO3)2 and magnesium borate-Mg2B2O5; wollastonite-2M-CaSiO3 and calcium borate-Ca(BO2)2; and strontium silicate-SrSiO3 and strontium borate-Sr2B2O5, respectively. In vitro cytotoxicity tests were performed using the mouse fibroblast cell line (L929). Glass and glass ceramic at concentrations lower than 50 mg/mL did not exhibit any level of cytotoxicity when compared with the control. However, quantitative evaluation indicated that greater cell growth occurred in the presence of materials with crystalline phases. Control of BBGs crystallization may therefore be used to influence the biocompatibility of these glass-ceramic systems

Stent redilation in canine models of congenital heart disease: Pulmonary artery stenosis and coarctation of the aorta

In a canine puppy model, pulmonary artery stenosis was created by banding the left pulmonary artery to 30–40% of its original diameter. Animals underwent right heart catheterization and angiography 1–2 mo later, and Palmaz P308 stents were implanted. Stent redilation was performed 3–5 mo later. One mo postredilation, the animals were restudied and sacrificed. Coarctations of the aorta were created by transverse aortic incision and longitudinal repair. P308 stent implantation was performed 2–3 mo later. Stent redilation was performed after 6–10 mo, and the animals were restudied and sacrificed 1–2 mo later. Stent implantation was performed in 6 puppies with pulmonary artery stenosis, as 2 animals developed postoperative pulmonary arterial hypoplasia, precluding stenting. The stenosis diameter increased from 4.8 ± 0.5 mm to 7.4 ± 0.6 mm (mean ± SE) following stenting ( P = 0.005), and increased further to 9.2 ± 0.7 mm following redilation ( P < 0.001). There were no significant vessel tears or ruptures. Coarctation stenting was performed in 8 animals. The coarctation was dilated from 5.8 ± 0.9 mm to 9.8 ± 0.6 mm ( P < 0.001), and to 13.5 ± 0.5 mm at redilation ( P = 0.002). Redilation could not be performed in 1 animal. Aortic rupture and death occurred in 2 of 7 animals at redilation. Stent implantation and redilation in experimental pulmonary artery stenosis appears safe and effective. Though stent implantation for coarctation of the aorta appears safe, there was a 28% aortic rupture rate at stent redilation in this model. © 1996 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38176/1/24_ftp.pd

KEPLER's First Rocky Planet: Kepler-10b

NASA's Kepler Mission uses transit photometry to determine the frequency of earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: 1) a 152 +/- 4 ppm dimming lasting 1.811 +/- 0.024 hours with ephemeris T[BJD]=2454964.57375+N*0.837495 days and 2) a 376 +/- 9 ppm dimming lasting 6.86 +/- 0.07 hours with ephemeris T[BJD]=2454971.6761+N*45.29485 days. Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1-minute cadence for >4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9 +/- 4.5 Gyr) but otherwise Sun-like Main Sequence star with Teff=5627 +/- 44 K, Mstar=0.895 +/- 0.060 Msun, and Rstar=1.056 +/- 0.021 Rsun. Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: Mpl=4.56 +/- 1.29 Mearth, Rpl=1.416 +/- 0.036 Rearth, and density=8.8 +/- 2.9 gcc. Kepler-10b is the smallest transiting exoplanet discovered to date.Comment: Accepted, Astrophysical Journal, November 25, 2010; Eexpected publication date: February 20, 201

Bostonia: 1997-1998, no. 1-4

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Bostonia: 1997-1998, no. 1-4

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Defining Peruvians as a Problem: Ethnic Projects and Resistance at a Japanese Elementary School

I argue that some Japanese elementary school practices, such as having foreign parents sign a loyalty oath and repeatedly questioning the parents about their migration plans, constitute an ethnic project that defines these parents as disloyal aliens who are unwilling to adapt to Japanese cultural norms. In response, the foreign parents limit their willingness to assimilate. Based on ethnographic fieldwork at a public elementary school in central Japan that has more than 50 foreign children, the majority of whom are Peruvians of Japanese descent, I explore the context of reception in the school, including teacher-parent relations, teachers’ expectations, their complaints, and their questions about the parents’ commitment to living in the host country. I ask what is the nature of the relationship between Japanese teachers and foreign parents? How are school practices influencing the context of reception, and how is that context impacting foreign parents’ sense of belonging in Japan? I conclude by discussing potential impacts, including the reproduction of existing inequalities in this immigrant population

TEACHING AND LEARNING ACROSS AN ETHNIC DIVIDE: PERUVIAN PARENTS AND A JAPANESE SCHOOL

This article presents a case study of relations between Japanese teachers and Peruvian parents at a public elementary school in central Japan. Using interviews and participant observation, this critical account reveals how some teachers, frustrated by the challenges of teaching an increasingly foreign student body, blame problems at the school on Peruvian parents’ limited language skills and cultural differences. Amid these complaints, various structural factors hinder the efforts of Peruvian parents and children, including poor language support and ineffective remedial language instruction. This account also examines the ways parents’ class position and immigrant status influence their acquisition of the social and cultural capital necessary for the parents to more effectively participate in their children’s education in Japan