1,350 research outputs found
Direct Observational Test Rules Out Small MgII Absorbers
Recent observations suggest the incidence of strong intervening MgII
absorption systems along the line-of-sight to gamma ray burst (GRB) afterglows
is significantly higher than expected from analogous quasar sightlines. One
possible explanation is a geometric effect, arising because MgII absorbers only
partially cover the quasar continuum regions, in which case MgII absorbers must
be considerably smaller than previous estimates. We investigate the production
of abnormal absorption profiles by partial coverage and conclude that the lack
of any known anomalous profiles in observed systems, whilst constraining,
cannot on its own rule out patchy MgII absorbers.
In a separate test, we look for differences in the distribution function of
MgII equivalent widths over quasar continuum regions and CIII] emission lines.
We show that these anomalies should be observable in any scenario where MgII
absorbers are very small, but they are not present in the data. We conclude
that models invoking small MgII cloudlets to explain the excess of absorbers
seen towards GRBs are ruled out.Comment: Accepted for publication in MNRAS Letters. 5 pages, 2 figure
Dungeness crab research program
In 1974, the California State Legislature, recognizing the
problem of low yields from the Dungeness crab resource of
central California, directed the Department of Fish and Game
to conduct an investigation into the causes of the decline.
The Operations Research Branch of the Department has conducted
preliminary studies and field operations necessary to formulate the Dungeness Crab Research Program. The objectives,
research design, and work plans are presented for a 4-year
program from July 1, 1975 through August 31, 1979. (38pp.
Theoretical Studies of Crystallisation in Hard Sphere Systems
The primary focus of this work is to develop an understanding of crystallisation in hard sphere systems. The thesis is presented in two parts. The first section is an investigation of the liquid/crystal interface at equilibrium using molecular dynamical simulations. The objective is to understand how the interface might bridge between the disordered and ordered states in liquid/crystal environments. Topological measures of structure are used to investigate whether any precursor structures are present in the liquid phase, close to the interface, that would allow transition from disorder to order. This differs from other work where simpler measures of structure, classifying phases into either liquid or crystal, are used. The results indicate that the liquid/crystal interface of a hard sphere system is very narrow and no readily observable structures were found that extended past the width of the equilibrium interface. The second section of the thesis is a theoretical study of growth kinetics in hard sphere systems using density functional theory. The kinetics in a fixed volume are examined with a single conserved order parameter. The work is extended incorporating both conserved particle and non-conserved structure dynamics. The kinetics of growth are examined and it is shown that the small initial crystals are quickly isolated from the higher pressure of the surrounding system through the development of a depletion zone
Terrorism and College Students: A Generation\u27s Response to September 11, 2001
The terrorist attacks on the United States of September 11, 2001 marked a significant cultural turning point for Americans. The tragic destruction of the World Trade Towers , the damage to the Pentagon and the loss of thousands of civilian lives brought an end to the optimism and feelings of security and invulnerability that marked the decade of the 1990s. Students who were enrolled in college at the time of the attacks were affected as well. This qualitative study examines the emotions and attitudes of 50 students enrolled a mid-sized, private research institution on September 11, 2001. The study explores both the short term and long term responses to the attacks. Very little research has been conducted on college student reactions to September 11, 2001. This study indicated a departure from some of the predictions of Terror Management Theory ( Pyszczynski, Solomon, & Greenberg, 2003) that suggested high levels of patriotism and bigotry in the wake of 9/11, neither of which were widely expressed by the students interviewed. However, this study reinforces the predictions from several theories on generational change (notably those from Strauss and Howe, 1991) that the values and attitudes of the Millennial generation (students born from 1980 ¿ 2000) will be different from the generation before them. Students enrolled in college during the September 11, 2001 terrorist attacks will be much more outwardly focused and civic-minded than generations that preceded them
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