Optimum earth re-entry corridors

Steepest ascent optimization procedure for reentry trajectory of manned aerospace vehicle

Chosen Ones: A Qualitative Inquiry into the Collegiate Team Captain Experience

The team captain is a highly recognizable position held in collegiate athletics. Loughead et al. (2006) suggests the team captain represents the formal peer leader in athletics. Although this may be the case, only one study was found which qualitatively investigated this position in male ice hockey (Dupois et al. 2006). Moran and Weiss (2005) highlighted differences in male versus female peer leadership in sport. A gap in the current sport psychology literature exists in the critical evaluation of both male and female, and team and individual peer sport leadership, from the first-person perspective. The purpose of this study was to critically examine the experience of the collegiate team captain as well as the perceived roles of the individual. Two open-ended questions were presented to individuals representing four area\u27s of collegiate competition: male team sport captains, male individual sport captains, female team sport captains, and female individual sport captains. Participant interviews revealed an overall thematic structure of: A Good and Fun Experience, Responsibilities, and Relationships. Several subthemes from each of these categories emerged in the data, as well as additional subthemes when separating the co-participants into their appropriate gender groups

Active galactic nucleus feedback in clusters of galaxies

Observations made during the last ten years with the Chandra X-ray Observatory have shed much light on the cooling gas in the centers of clusters of galaxies and the role of active galactic nucleus (AGN) heating. Cooling of the hot intracluster medium in cluster centers can feed the supermassive black holes found in the nuclei of the dominant cluster galaxies leading to AGN outbursts which can reheat the gas, suppressing cooling and large amounts of star formation. AGN heating can come in the form of shocks, buoyantly rising bubbles that have been inflated by radio lobes, and the dissipation of sound waves.Comment: Refereed review article published in Chandra's First Decade of Discovery Special Feature edition of the Proceedings of the National Academy of Science

The EFIGI catalogue of 4458 nearby galaxies with morphology II. Statistical properties along the Hubble sequence

The EFIGI catalogue of 4458 galaxies provides a reference database of the morphological properties of nearby galaxies, with 16 shape attributes describing their various dynamical components, their texture and environment, and with a dense sampling of all Hubble types. This catalogue allows us to derive a quantitative description of the Hubble Sequence in terms of the specific morphological features of the various types. The variations of the EFIGI morphological attributes with type confirm that the visual Hubble sequence is a decreasing sequence of bulge-to-total ratio and an increasing sequence of disk contribution to the total flux. There is nevertheless a large dispersion of approximately 5 types for a given bulge-to-total ratio, due to the fact that the Hubble sequence is primarily based on the strength and pitch angle of the spiral arms, independently from the bulge-to-total ratio. The grand spiral design is also related to a steep decrease in visible dust from types Sb to Sbc-Sc. In contrast, the scattered and giant HII regions show different strength variation patterns; hence, they do not appear to directly participate in the establishment of the Hubble sequence. The distortions from a symmetric profile also incidentally increase along the sequence. Bars and inner rings are frequent and occur in 41% and 25% of disk galaxies resp. Outer rings are twice less frequent than inner rings, and outer pseudo-rings occur in 11% of barred galaxies. Finally, we find a smooth decrease in mean surface brightness and intrinsic size along the Hubble sequence. The largest galaxies are cD, Ellipticals and Sab-Sbc spirals, whereas Sd and later spirals are nearly twice smaller. S0 are intermediate in size, and Im, cE and dE are confirmed as small objects. Dwarf spiral galaxies of type Sa to Scd are rare in the EFIGI catalogue, we only find 2 such objects.Comment: Accepted for publication in Astronomy and Astrophysics, 22 pages, 10 tables, 19 colour figures. Data available at http://www.efigi.or