Non-Adiabatic Spin Transfer Torque in Real Materials

The motion of simple domain walls and of more complex magnetic textures in the presence of a transport current is described by the Landau-Lifshitz-Slonczewski (LLS) equations. Predictions of the LLS equations depend sensitively on the ratio between the dimensionless material parameter $\beta$ which characterizes non-adiabatic spin-transfer torques and the Gilbert damping parameter $\alpha$. This ratio has been variously estimated to be close to 0, close to 1, and large compared to 1. By identifying $\beta$ as the influence of a transport current on $\alpha$, we derive a concise, explicit and relatively simple expression which relates $\beta$ to the band structure and Bloch state lifetimes of a magnetic metal. Using this expression we demonstrate that intrinsic spin-orbit interactions lead to intra-band contributions to $\beta$ which are often dominant and can be (i) estimated with some confidence and (ii) interpreted using the "breathing Fermi surface" model.Comment: 18 pages, 9 figures; submitted to Phys. Rev.

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

Sex and Symbol in Andalusian Comic Poetry

This paper presents a series of comic coplas written for public performance during carnival in agrotown in Seville Province, Andalusia. The songs date from the 1940s to the 1990s. Their production is a male prerogative: composed by male «maestros», they are sung by male troubadours. This is a specifically Andalusian genre of social burlesque that takes woman as its subject: wives, lovers, mothers-in-law. The lyrics use erotic imagery, genital tropes, and obscene allegories to covey the prevailing masculine ideology concerning sexuality, male-female politics, and domestic relations. The paper concludes with a brief interpretation of the style and symbolism of the Andalusian carnivalesque, borrowing from the critic Bakhtin's concept of «grotesque realism».Este artículo presenta unas coplas de chirigota compuestas por desempeño público durante el carnaval en una villa agraria de la provincia de Sevilla. Las coplas están compuestas entre los años 40 y 90. Representando un género folklórico burlesco social específicamente andaluz, las coplas son una prerrogativa solamente masculina, escritas por los «maestros de murga» e interpretadas por cantores masculinos («murguistas»). Basadas en imágenes eróticas, metáforas genitales y alegorías obscenas, las letras comunican una ideología masculina sobre la sexualidad, las relaciones entre el hombre y la mujer y la domesticidad. Concluye el artículo con una breve interpretación de las letras de chirigota, basándose el análisis en el concepto de «realismo grotesco» propuesto por el crítico ruso Bakhtin

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

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

A Survey of Clustering Analysis and Clustering Analysis in Graphs

Clustering analysis is an important topic in data mining, where data points that are similar to each other are grouped together. Graph clustering deals with clustering analysis of data points that correspond to vertices on a graph. We first survey some most well known algorithms for clustering analysis. Then for graph clustering we note that one of the fundamental factors is the distance measure between vertices. We further examine various known venues for defining such measures and propose some others

Effects of Cognitive Set on the Physiological, Subjective, and Behavioral Responses to Fearful Stimuli

This research investigated the effects of cognitive set on the physiological, subjective, and motoric responses of fearful and non-fearful subjects exposed to specific fear stimuli. High, moderate, and low mutilation fear subjects were given instructions designed to persuade them that they were or were not afraid of mutilation stimuli. The extent to which instructions differentially affected subjects in the three fear groups and produced differential effects on responses in the three modalities was examined. The degree to which the physiological, self-report, and behavioral channels responded concordantly was also investigated. A series of hypotheses were derived which generally indicated that high-fear instructions would produce significantly greater physiological, self-report, and behavioral indices of anxiety than low-fear instructions. It was also predicted that these effects would be great- est for subjects in the moderate-fear group, and that the subjective and motoric response systems would exhibit greater differential change due to instructions than the physiological channel. In addition, high mutilation fear subjects were predicted to show greater concordance between response systems than the moderate- or low-fear groups. Subjects were 48 female undergraduate students enrolled at Virginia Commonwealth University who were selected from a pool of 168 females who answered the Mutilation Questionnaire (Klorman, Weerts, Hastings, Melamed, & Lang, 1974). Sixteen subjects were assigned to each of the three fear groups on the basis of their total MQ scores, with 8 subjects in each of the six combined fear-instructional conditions. Following the administration of either high- or low-fear instructions, each subject was exposed to 5 neutral and 5 fearful slides. Each slide was presented for a 10-second duration with a 120—second interval between slides. Dependent measures consisted of skin conductance responses (SCR), heart rate responses (HRR), and subjective distress ratings (SUDS) for each slide, total scores on a posttest administration of the MQ, and a behavioral avoidance Test (BAT) in seconds of latency to respond. Results indicated that instruction had the predicted effects on the SCR‘s produced by all three fear groups to neutral stimuli, and on the level of heart rate exhibited by high mutilation fear subjects to both fearful and neutral slides. With the exception of the SUDS ratings of the moderate-fear group, the predicted instructional effects were obtained on both self-report measures for all three groups. The BAT measure failed to produce any significant instructional effects. The results did not support the hypotheses predicting greater instructional effects for moderately fearful subjects and no significant differences were obtained in the degree of concordance between dependent measures for the three fear groups. Results are discussed with regard to the effects of cognitive set on the various components of the anxiety response and the relationship between arousal level and effectiveness of the instructional manipulation. Issues of clinical relevance, such as the treatment of phobias, were also discussed with regard to the results of the present study. Methodological problems in the present study and suggestions for future research are also discussed