22,059 research outputs found
A database of number fields
We describe an online database of number fields which accompanies this paper
The database centers on complete lists of number fields with prescribed
invariants. Our description here focuses on summarizing tables and connections
to theoretical issues of current interest.Comment: 25 pages, 1 figur
Gas flows in elliptical galaxies
In preparation for the next generation of x ray telescopes, researchers have begun a program investigating the evolving x ray properties of elliptical galaxies. Their galaxy models consist of a modified King profile for the luminous portion of the galaxy and can include an isothermal dark halo comprising 90 percent of the total mass. The stellar population is assumed to form at a rate which decreases exponentially on a dynamical time scale with a Salpeter initial mass function. Stellar mass loss occurs instantaneously as stars evolve off the main sequence. All stars more massive than 8 solar mass produce type II supernovae, while less massive stars loss mass through a planetary nebulae. The evolving rate of type I supernovae is normalized to a fraction, gamma sub sn I, of Tammann's (1974) value. All of this information is then incorporated into a one-dimensional hydrodynamics code to determine the evolving dynamical state of the interstellar medium
Transforming a 4th year Modern Optics Course Using a Deliberate Practice Framework
We present a study of active learning pedagogies in an upper division physics
course. This work was guided by the principle of deliberate practice for the
development of expertise, and this principle was used in the design of the
materials and the orchestration of the classroom activities of the students. We
present our process for efficiently converting a traditional lecture course
based on instructor notes into activities for such a course with active
learning methods. Ninety percent of the same material was covered and scores on
common exam problems showed a 15 % improvement with an effect size greater than
1 after the transformation. We observe that the improvement and the associated
effect size is sustained after handing off the materials to a second
instructor. Because the improvement on exam questions was independent of
specific problem topics and because the material tested was so mathematically
advanced and broad (including linear algebra, Fourier Transforms, partial
differential equations, vector calculus), we expect the transformation process
could be applied to most upper division physics courses having a similar
mathematical base.Comment: 31 page
The Stability of the orbits of Earth-mass planets in and near the habitable zones of known exoplanetary systems
We have shown that Earth-mass planets could survive in variously restricted regions of the habitable zones (HZs) of most of a sample of nine of the 93 main-sequence exoplanetary systems confirmed by May 2003. In a preliminary extrapolation of our results to the other systems, we estimate that roughly a third of the 93 systems might be able to have Earth-mass planets in stable, confined orbits somewhere in their HZs. Clearly, these systems should be high on the target list for exploration for terrestrial planets. We have reached this conclusion by launching putative Earth-mass planets in various orbits and following their fate with a mixed-variable symplectic integrator
Adjustable mount for electro-optic transducers in an evacuated cryogenic system
The invention is an adjustable mount for positioning an electro-optic transducer in an evacuated cryogenic environment. Electro-optic transducers are used in this manner as high sensitivity detectors of gas emission lines of spectroscopic analysis. The mount is made up of an adjusting mechanism and a transducer mount. The adjusting mechanism provided five degrees of freedom, linear adjustments and angular adjustments. The mount allows the use of an internal lens to focus energy on the transducer element thereby improving the efficiency of the detection device. Further, the transducer mount, although attached to the adjusting mechanism, is isolated thermally such that a cryogenic environment can be maintained at the transducer while the adjusting mechanism remains at room temperature. Radiation shields also are incorporated to further reduce heat flow to the transducer location
How do Multinationals Build Social Capital? Diageo's Corporate Citizenship Programme.
This paper attempts to enhance understanding of the process by which multinationals build social capital by examining the Corporate Citizenship (CC) activities and associated social capital outcomes of the UK-based branded alcoholic drinks company, Diageo. The firm possesses a structured portfolio of CC initiatives and projects and has a long-standing tradition of community engagement. This paper examines Diageo’s CC strategy in depth and considers the ways that their engagements impact upon social capital development in different arenas. The forces driving social capital outcomes are considered and implications for companies and governments are offered.social capital, corporate citizenship, Diageo, community programmes.
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