User benefits and funding strategies

A three-step, systematic method is described for selecting relevant and highly beneficial payloads for the Interim Upper Stage (IUS) that will be used with the space shuttle until the space tug becomes available. Viable cost-sharing strategies which would maximize the number of IUS payloads and the benefits obtainable under a limited NASA budget were also determined

A Comprehensive Spectroscopic Analysis of DB White Dwarfs

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 Mo for our sample, with a dispersion of only 0.09 Mo. White dwarfs also showing hydrogen lines, the DBA stars, comprise 44% of our sample, and their mass distribution appears similar to that of DB stars. As in our previous investigation, we find no evidence for the existence of low-mass (M < 0.5 Mo) DB white dwarfs. We derive a luminosity function based on a subset of DB white dwarfs identified in the Palomar-Green survey. We show that 20% of all white dwarfs in the temperature range of interest are DB stars, although the fraction drops to half this value above Teff ~ 20,000 K. We also show that the persistence of DB stars with no hydrogen features at low temperatures is difficult to reconcile with a scenario involving accretion from the interstellar medium, often invoked to account for the observed hydrogen abundances in DBA stars. We present evidence for the existence of two different evolutionary channels that produce DB white dwarfs: the standard model where DA stars are transformed into DB stars through the convective dilution of a thin hydrogen layer, and a second channel where DB stars retain a helium-atmosphere throughout their evolution. We finally demonstrate that the instability strip of pulsating V777 Her white dwarfs contains no nonvariables, if the hydrogen content of these stars is properly accounted for.Comment: 74 pages including 30 figures, accepted for publication in the Astrophysical Journa

User community development for the space transportation system/Skylab

The New User Function plan for identifying beneficial uses of space is described. Critical issues such as funding, manpower, and protection of user proprietary rights are discussed along with common barriers which impede the development of a user community. Studies for developing methodologies of identifying new users and uses of the space transportation system are included

A Gravitational Redshift Determination of the Mean Mass of White Dwarfs. DBA and DB Stars

We measure apparent velocities (v_app) of absorption lines for 36 white dwarfs (WDs) with helium-dominated atmospheres -- 16 DBAs and 20 DBs -- using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). We find a difference of 6.9+/-6.9 km/s in the average apparent velocity of the H-alpha lines versus that of the HeI 5876AA for our DBAs. This is a measure of the blueshift of this He line due to pressure effects. By using this as a correction, we extend the gravitational redshift method employed by Falcon et al. (2010) to use the apparent velocity of the HeI 5876AA line and conduct the first gravitational redshift investigation of a group of WDs without visible hydrogen lines. We use biweight estimators to find an average apparent velocity, _BI, (and hence average gravitational redshift, _BI) for our WDs; from that we derive an average mass, _BI. For the DBAs, we find _BI = 40.8+/-4.7 km/s and derive _BI = 0.71 +0.04 -0.05 Msun. Though different from of DAs (32.57 km/s) at the 91% confidence level and suggestive of a larger DBA mean mass than that for normal DAs derived using the same method (0.647 +0.013 -0.014 Msun; Falcon et al. 2010), we do not claim this as a stringent detection. Rather, we emphasize that the difference between _BI of the DBAs and of normal DAs is no larger than 9.2 km/s, at the 95% confidence level; this corresponds to roughly 0.10 Msun. For the DBs, we find ^He_BI = 42.9+/-8.49 km/s after applying the blueshift correction and determine _BI = 0.74 +0.08 -0.09 Msun. The difference between ^He_BI of the DBs and of DAs is less than or equal to 11.5 km/s (~0.12 Msun), at the 95% confidence level. The gravitational redshift method indicates much larger mean masses than the spectroscopic determinations of the same sample by Voss et al. (2007)...Comment: Accepted to the Astrophysical Journal, 10 pages double-column, 3 figures, 5 table

Multiwavelength Observations of the Hot DB Star PG 0112+104

We present a comprehensive multiwavelength analysis of the hot DB white dwarf PG 0112+104. Our analysis relies on newly-acquired FUSE observations, on medium-resolution FOS and GHRS data, on archival high-resolution GHRS observations, on optical spectrophotometry both in the blue and around Halpha, as well as on time-resolved photometry. From the optical data, we derive a self-consistent effective temperature of 31,300+-500 K, a surface gravity of log g = 7.8 +- 0.1 (M=0.52 Msun), and a hydrogen abundance of log N(H)/N(He) < -4.0. The FUSE spectra reveal the presence of CII and CIII lines that complement the previous detection of CII transitions with the GHRS. The improved carbon abundance in this hot object is log N(C)/N(He) = -6.15 +- 0.23. No photospheric features associated with other heavy elements are detected. We reconsider the role of PG 0112+104 in the definition of the blue edge of the V777 Her instability strip in light of our high-speed photometry, and contrast our results with those of previous observations carried out at the McDonald Observatory.Comment: 10 pages in emulateapj, 9 figures, accepted for publication in Ap

The asteroseismological potential of the pulsating DB white dwarf stars CBS 114 and PG 1456+103

We have acquired 65 h of single-site time-resolved CCD photometry of the pulsating DB white dwarf star CBS 114 and 62 h of two-site high-speed CCD photometry of another DBV, PG 1456+103. The pulsation spectrum of PG 1456+103 is complicated and variable on time scales of about one week and could only partly be deciphered with our measurements. The modes of CBS 114 are more stable in time and we were able to arrive at a frequency solution somewhat affected by aliasing, but still satisfactory, involving seven independent modes and two combination frequencies. These frequencies also explain the discovery data of the star, taken 13 years earlier. We find a mean period spacing of 37.1 +/- 0.7 s significant at the 98% level between the independent modes of CBS 114 and argue that they are due to nonradial g-mode pulsations of spherical degree l=1. We performed a global search for asteroseismological models of CBS 114 using a genetic algorithm, and we examined the susceptibility of the results to the uncertainties of the observational frequency determinations and mode identifications (we could not provide m values). The families of possible solutions are identified correctly even without knowledge of m. Our optimal model suggests Teff = 21,000 K and M_* = 0.730 M_sun as well as log(M_He/M_*) = -6.66, X_O = 0.61. This measurement of the central oxygen mass fraction implies a rate for the ^12C(alpha,gamma)^16O nuclear reaction near S_300=180 keV b, consistent with laboratory measurements.Comment: 10 pages, 10 embedded figures, 3 embedded tables. Accepted for publication in MNRA

The Relationship Between Task Cohesion and Competitive State Anxiety

The general purpose of the present study was to determine if perceptions of team cohesion are related to the interpretation athletes attach to their precompetition anxiety. Specifically examined was the association between athlete perceptions of task cohesiveness (Individual Attractions to the Group–Task, ATG-T, and Group Integration–Task, GI-T) and the degree to which perceptions of the intensity of precompetition anxiety symptoms (cognitive and somatic) were viewed as facilitative versus debilitative. Participants were athletes (N = 392) from the sports of soccer, rugby, and field hockey. Each athlete completed the Group Environment Questionnaire (Carron, Widmeyer, & Brawley, 1985) after a practice session. A directionally modified version of the Competitive State Anxiety Inventory-2 (Martens, Burton, Vealey, Bump, & Smith, 1990) was completed just prior to a competition. Results showed that athletes who perceived their cognitive anxiety as facilitative had higher perceptions of both ATG-T and GI-T, χ2 (2, N = 260) = 8.96, p \u3c .05, than athletes who perceived their cognitive anxiety as debilitative. Also, athletes who perceived their somatic anxiety as facilitative had higher perceptions of GI-T, χ2 (2, N = 249) = 5.85, p \u3c .05

Development of methodologies and procedures for identifying STS users and uses

A study was conducted to identify new uses and users of the new Space Transporation System (STS) within the domestic government sector. The study develops a series of analytical techniques and well-defined functions structured as an integrated planning process to assure efficient and meaningful use of the STS. The purpose of the study is to provide NASA with the following functions: (1) to realize efficient and economic use of the STS and other NASA capabilities, (2) to identify new users and uses of the STS, (3) to contribute to organized planning activities for both current and future programs, and (4) to air in analyzing uses of NASA's overall capabilities

Bottom-up and top-down processes affecting marine survival of salmon in the Salish Sea

Bottom-up processes mechanistically link with top-down control of populations, and these interactions are mediated by environmental variability and human-induced changes in land and water use. Size-selective mortality can be a significant force regulating recruitment of salmon and may be imposed at different life stages and habitats for different species, stocks, or life history types. The first months of marine growth are commonly regarded as a critical period for growth and survival of salmon. For ESA-listed Puget Sound Chinook salmon, emergent bottom-up patterns include: 1) a critical growth period occurs when body mass increases 2-4 fold during the first month of feeding in epi-pelagic habitats within Puget Sound; 2) that growth is limited primarily by food supply, but can be exacerbated by warm temperatures in shoreline habitiats; 3) higher growth and survival correspond with higher contributions of key prey like larval crab. Piscivorous fishes exhibit size-selective predation on juvenile salmon in Puget Sound, and resident forms of Chinook salmon are capable of imposing significant mortality on subyearling Chinook in Puget Sound