A VLBA Search for a Stimulated Recombination Line from the Accretion Region in NGC1275

The radio source 3C84, in NGC1275, has a two sided structure on parsec scales. The northern feature, presumed to be associated with a jet moving away from the Earth, shows strong evidence for free-free absorption. The ionized gas responsible for that absorption would be a source of detectable stimulated recombination line emission for a wide range of physical conditions. The VLBA has been used to search for the H65$\alpha$ hydrogen recombination line. The line is only expected to be seen against the northern feature which contains a small fraction of the total radio flux density. This spatial discrimination significantly aids the search for a weak line. No line was seen, with upper limits of roughly 15% of the continuum over a velocity range of 1486 km/s with resolutions up to 6.6 km/s. In the absence of a strong radiation field, this would imply that the free-free absorbing gas has a wide velocity width, is moving rapidly relative to the systemic velocity, or is concentrated in a thin, high density structure. All of these possibilities are reasonably likely close to an AGN. However, in the intense radiation environment of the AGN, even considering only the radiation we actually observe passing through the free-free absorbing gas, the non-detection is probably assured by a combination of saturation and radiation damping.Comment: 14 pages with 4 postscript figures. Accepted for publication in the April 2003 Astronomical Journa

Advanced launch system trajectory optimization using suboptimal control

The maximum-final mass trajectory of a proposed configuration of the Advanced Launch System is presented. A model for the two-stage rocket is given; the optimal control problem is formulated as a parameter optimization problem; and the optimal trajectory is computed using a nonlinear programming code called VF02AD. Numerical results are presented for the controls (angle of attack and velocity roll angle) and the states. After the initial rotation, the angle of attack goes to a positive value to keep the trajectory as high as possible, returns to near zero to pass through the transonic regime and satisfy the dynamic pressure constraint, returns to a positive value to keep the trajectory high and to take advantage of minimum drag at positive angle of attack due to aerodynamic shading of the booster, and then rolls off to negative values to satisfy the constraints. Because the engines cannot be throttled, the maximum dynamic pressure occurs at a single point; there is no maximum dynamic pressure subarc. To test approximations for obtaining analytical solutions for guidance, two additional optimal trajectories are computed: one using untrimmed aerodynamics and one using no atmospheric effects except for the dynamic pressure constraint. It is concluded that untrimmed aerodynamics has a negligible effect on the optimal trajectory and that approximate optimal controls should be able to be obtained by treating atmospheric effects as perturbations

Spectroscopy of the optical Einstein ring 0047-2808

We present optical and near-infrared spectroscopic observations of the optical Einstein ring 0047-2808. We detect both [OIII] lines 4959, 5007 near 2.3 micron, confirming the redshift of the lensed source as z=3.595. The Ly-a line is redshifted relative to the [OIII] line by 140+-20 km/s. Similar velocity shifts have been seen in nearby starburst galaxies. The [OIII] line is very narrow, 130 km/s FWHM. If the ring is the image of the centre of a galaxy the one-dimensional stellar velocity dispersion sigma=55 km/s is considerably smaller than the value predicted by Baugh et al. (1998) for the somewhat brighter Lyman-break galaxies. The Ly-a line is significantly broader than the [OIII] line, probably due to resonant scattering. The stellar central velocity dispersion of the early-type deflector galaxy at z=0.485 is 250+-30 km/s. This value is in good agreement both with the value predicted from the radius of the Einstein ring (and a singular isothermal sphere model for the deflector), and the value estimated from the D_n-sigma relation.Comment: 7 pages, 3 figures, accepted for publication in MNRA

UR-285 OPERATION ENDURING FREEDOM: Improving Mission Effectiveness by Identifying Trends in Successful Terrorism

This research examines how the characteristics of terrorist attacks predict the chance of an attack succeeding, where an attack is defined as successful if the intended attack type is carried out. Data was analyzed across three geographical missions within Operation Enduring Freedom: Trans-Sahara, Horn of Africa, and the Philippines. Using predicted probabilities of success obtained from logistic regression models, the medians were plotted to compare the characteristics of terrorist attacks across missions. By determining the specific features of attacks that produce the highest probabilities of success, the effectiveness of Operation Enduring Freedom can be improved by focusing counter-terrorism training and operations on the features that predict successful attacks

Metaphors of travel in the language of hymns: 1650–1800

This dissertation concentrates on the role of the conceptual metaphor LIFE IS A JOURNEY in English hymns of the 17th and 18th centuries, addressing the following research questions: 1) To what extent and in which contexts have elements of the lexical category of travel, applied metaphorically, been used in English spiritual language and literature in the period 1650–1800? 2) How has metaphorical extension affected the semantic development of this category? This dissertation discusses the use of travel metaphors as structural schemata for complete hymns, and analyzes the use of individual elements of travel-related terminology across a historical textual corpus. The analyses in this dissertation are undertaken in light of recent trends in semantics, and with the aim of contributing to the development of Cognitive Metaphor Theory as a tool for historical linguistic analysis and literary criticism

Every Day Counts: Proposals to Reform IDEA\u27s Due Process Structure

It is a core principle of special education legislation that the parents of children with disabilities can challenge the child\u27s educational programming through an administrative due process hearing. Yet for years the special education due process structure has been criticized as inefficient, anticollaborative, and prohibitively expensive. Those criticisms have given rise to widely varying proposals to reform special education due process, proposals that range from adding certain alternative dispute resolution mechanisms to a wholesale replacement of the due process structure. This article provides a comprehensive analysis of special education dispute resolution. The article first examines the lively debate among scholars and special interest groups about perceived deficiencies of IDEA due process and various proposals to remedy those deficiencies. The article then sets forth the results of a nationwide survey in which over three hundred and fifty special education attorneys voiced their opinions about the current structure and some proposals for reform. Finally, the article recommends certain structural changes to IDEA due process that are designed to improve the efficiency and reduce the cost of special education dispute resolution

Changes in Testing and Paying for Milk Components as Proposed under the Final Rule of Federal Order Reform: Implications for Dairy Producers

Agricultural and Food Policy, Livestock Production/Industries,