An Independent Calibration of Stellar Ages: HST Observations of White Dwarfs at V=25

The white dwarf luminosity function of a stellar cluster will have a sharp truncation at a luminosity which is determined by the time since formation of the first white dwarfs in that cluster. Calculation of the dependence of this limiting luminosity on age requires relatively well-understood physics and is independent of stellar evolutionary models. Thus, measurement of the termination of the white dwarf luminosity function provides an independent method to determine the age of a cluster, and thereby to calibrate stellar evolutionary ages. We have obtained HST WFPC2 data in two open clusters, identified the white dwarf sequence, and proved the feasibility of this approach, by detecting white dwarfs to V=25. Much deeper data are feasible. From our present limited data, we show that degenerate cooling ages are not consistent with some published isochrone ages for clusters with ages of order 1Gyr.Comment: 5 pages plus 3 figures ps format, paper in press in MNRAS: previous attempt lost the tex

Connections of the Mesencephalic Locomotor Region (MLR) in the Cat

The cat entopeduncular nucleus (EN), which is the main output of the basal ganglia, is known to project to the mesencephalic tegmentum. We have been able to elicit antidromic responses in single EN neurons from the region of the mesencephalic locomotor region (MLR), then transect (precollicular-postmamillary) the brainstem and elicit rhythmic movements of the limbs by stimulation of the same site in the same animal. Injections of the fluorescent dye 2,4 diamidino phenylindole 2 HCL (DAPI) into this area induces retrograde labeling of cell bodies in EN and motor cortex. Injections of a tritiated amino acid (leucine) into the motor cortex induce terminal labeling in the area of the MLR. These studies describe convergent projections from EN and motor cortex to the MLR. These connections may be involved in the sequencing and ordering of voluntary movements in which locomotion is necessary

On N=8 attractors

We derive and solve the black hole attractor conditions of N=8 supergravity by finding the critical points of the corresponding black hole potential. This is achieved by a simple generalization of the symplectic structure of the special geometry to all extended supergravities with $N>2$. There are two solutions for regular black holes, one for 1/8 BPS ones and one for the non-BPS. We discuss the solutions of the moduli at the horizon for BPS attractors using N=2 language. An interpretation of some of these results in N=2 STU black hole context helps to clarify the general features of the black hole attractors.Comment: 15 page

Technology transfer - A selected bibliography

Selected bibliography on technology transfe

Use of an External Inhibition Procedure in the Treatment of Spider Phobic Subjects

This research represented an extension of previous work on the therapeutic application of the external inhibition phenomenon, and sought to examine the effects of such a procedure on the verbal- cognitive, motoric, and physiological components of the anxiety response. To accomplish this, subjects were selected and treatment effects evaluated on the basis of changes elicited in each of the three response modalities by a specific fear stimulus, The relative effectiveness of the external inhibition treatment in modifying the multiple components of the anxiety response was examined by a comparison with procedures controlling for expectancy effects and repeated exposure to the phobic stimulus. A series of hypotheses were derived which predicted that the external inhibition treatment would produce significant reductions in the self-report, behavioral, and physiological channels being assessed. It was also predicted that these reductions in anxiety for subjects receiving the external inhibition treatment would be significantly greater than those evidenced by subjects receiving procedures designed to control for expectancy effects and repeated stimulus exposures. Subjects were 24 female undergraduate students enrolled at Virginia Commonwealth University who were selected from a pool of 316 females who answered the Spider Questionnaire (Klorman, Weerts, Hastings, Melamed, & Lang, 1974). Three separate selection criteria were utilized to help insure that only those subjects who were highly fearful of spiders were selected for participation in the study: (1) a total score on the SPQ that was within the upper 25% of the distribution of scores on the SPQ, (2) a distance score of at least 24 inches on a passive behavioral avoidance test (BAT), and (3) an increase in heart rate of at least 10% during the initial exposure to the spider. Eight subjects meeting these criteria were randomly assigned to one of three experimental groups: An External Inhibition group, a Graduated Exposure Group, or a Test-Retest Control group. Following an initial pretreatment assessment, subjects in the External Inhibition group were exposed to the spider in a BAT format, and were presented with an external stimulus (white noise administered in 2-second pulses for 30-seconds at 95dbA) each time they began to feel anxious and stopped the advance of the spider. Graduated Exposure subjects received the same procedure without the external stimulus and were instead instructed to ”relax” themselves whenever they began to feel anxious. Subjects in the Test-Retest group received no intervening procedure and simply sat quietly without the spider present for a comparable period of time. Dependent measures consisted of pre- and posttreatment BAT scores, subjective distress ratings (SUDS) elicited by the spider, heart rate responding, skin conductance activity, and SPQ scores. The results failed to provide any evidence of the relative efficacy of external inhibition in modifying phobic behavior. In all cases, the external inhibition treatment was found to be either ineffective or no more effective than the two control procedures in modifying the multiple components of the anxiety response. These findings are discussed in terms of various situational, procedural, and subject factors that may have contributed to the rapid habituation of anxiety among all three experimental groups, and thereby precluded the valid evaluation of potential treatment effects. The implications of these results for the external inhibition phenomenon and for analogue fear research are discussed