A comparison of motor submodels in the optimal control model

Properties of several structural variations in the neuromotor interface portion of the optimal control model (OCM) are investigated. For example, it is known that commanding control-rate introduces an open-loop pole at S=O and will generate low frequency phase and magnitude characteristics similar to experimental data. However, this gives rise to unusually high sensitivities with respect to motor and sensor noise-ratios, thereby reducing the models' predictive capabilities. Relationships for different motor submodels are discussed to show sources of these sensitivities. The models investigated include both pseudo motor-noise and actual (system driving) motor-noise characterizations. The effects of explicit proprioceptive feedback in the OCM is also examined. To show graphically the effects of each submodel on system outputs, sensitivity studies are included, and compared to data obtained from other tests

A population synthesis study of the luminosity function of hot white dwarfs

We present a coherent and detailed Monte Carlo simulation of the population of hot white dwarfs. We assess the statistical significance of the hot end of the white dwarf luminosity function and the role played by the bolometric corrections of hydrogen-rich white dwarfs at high effective temperatures. We use the most up-to-date stellar evolutionary models and implement a full description of the observational selection biases to obtain realistic simulations of the observed white dwarf population. Our theoretical results are compared with the luminosity function of hot white dwarfs obtained from the Sloan Digital Sky Survey (SDSS), for both DA and non-DA white dwarfs. We find that the theoretical results are in excellent agreement with the observational data for the population of white dwarfs with hydrogen deficient atmospheres (non-DA white dwarfs). For the population of white dwarfs with hydrogen-rich atmospheres (white dwarfs of the DA class), our simulations show some discrepancies with the observations for the brightest luminosity bins. These discrepancies can be attributed to the way in which the masses of the white dwarfs contributing to this luminosity bin have been computed, as most of them have masses smaller than the theoretical lower limit for carbon-oxygen white dwarfs. We conclude that the way in which the observational luminosity function of hot white dwarfs is obtained is very sensitive to the particular implementation of the method used to derive the masses of the sample. We also provide a revised luminosity function for hot white dwarfs with hydrogen-rich atmospheres.Comment: 6 pages, 5 figures, accepted for publication in A&

Voz Alta: The Sound of a Collective Memory

Voz Alta is a participatory, voice-activated public light installation designed by Rafael Lozano-Hemmer as a memorial for the Tlatelolco massacre, which occurred on October 2, 1968 in the Plaza de las Tres Culturas in Tlatelolco, Mexico. In the Plaza, Lozano-Hemmer has synchronized a megaphone with a 10 kW Xenon robotic searchlight. As each participant speaks into the megaphone, the searchlight shines to the uppermost floor of the towering Centro Cultural Tlatelolco (CCT) building where three additional searchlights instantaneously strobe, dim, and brighten, illuminating the nocturnal landscape in horizontally fixed, tangential beams. Although the aesthetic, social, historical, and political aspects of Voz Alta have been discussed extensively in existing scholarship, the role of sound as a mechanism for power, control, and disruption has been sparsely addressed. This paper examines the metaphorical and literal manifestations of sound in Voz Alta and build upon Diana Sorenson’s discussion of the literary and verbal insurgencies that emerged after the massacre, as well as Michael Soldatenko’s analysis of the “oppositional imaginary,” which was catalyzed by the public in the informational vacuum imposed by the ruling Partido Revolucionario Institucional (PRI) regime. By incorporating the memory of a charged national event into spaces already imbued with meaning, Voz Alta operates on multiple levels, deliberately exceeding the parameters of artistic practice and becoming a platform for social activism. The paper’s aim is to achieve consensus on what Voz Alta achieves for its participants; its correlation and activation of memory associated with the massacre; and its potential to supplement the incomplete history that haunts the contemporary Mexican state.https://scholarscompass.vcu.edu/gradposters/1006/thumbnail.jp

New Pulsating DB White Dwarf Stars from the Sloan Digital Sky Survey

We are searching for new He atmosphere white dwarf pulsators (DBVs) based on the newly found white dwarf stars from the spectra obtained by the Sloan Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better known cousins, the H atmosphere white dwarf pulsators (DAVs or ZZ Ceti stars). Since the evolution of white dwarf stars is characterized by cooling, asteroseismological studies of DBVs give us opportunities to study white dwarf structure at a different evolutionary stage than the DAVs. The hottest DBVs are thought to have neutrino luminosities exceeding their photon luminosities (Winget et al. 2004), a quantity measurable through asteroseismology. Therefore, they can also be used to study neutrino physics in the stellar interior. So far we have discovered nine new DBVs, doubling the number of previously known DBVs. Here we report the new pulsators' lightcurves and power spectra.Comment: 15 pages, 2 figures, 3 tables, ApJ accepte

Method of Using CCR3 Binding Agents to Detect Choroidal Neovascularization

The results presented herein demonstrate the specific expression of CCR3 in CNV endothelial cells in humans with AMD, and despite the expression of its ligands, eotaxin-1, -2, and -3, neither eosinophils nor mast cells are present in human CNV. The genetic or pharmacological targeting of CCR3 or eotaxins as disclosed herein inhibited injury-induced CNV in mice. CNV suppression by CCR3 blockade was due to direct inhibition of endothelial cell proliferation, and was uncoupled from inflammation as it occurred in mice lacking eosinophils or mast cells and was independent of macrophage and neutrophil recruitment. CCR3 blockade was more effective at reducing CNV than vascular endothelial growth factor-A (VEGF-A) neutralization, which is currently in clinical use, and, unlike VEGF-A blockade, not toxic to the mouse retina. In vivo imaging with CCR3-targeting quantum dots located spontaneous CNV invisible to standard fluorescein angiography in mice before retinal invasion. CCR3 targeting is useful in reducing vision loss due to AMD through early detection and therapeutic angioinhibition

The unusual pulsation spectrum of the cool ZZ Ceti star HS 0507+0434B

We present the analysis of one week of single-site high-speed CCD photometric observations of the cool ZZ Ceti star HS 0507+0434B. Ten independent frequencies are detected in the star's light variations: one singlet and three nearly-equally spaced triplets. We argue that these triplets are due to rotationally split modes of spherical degree l=1. This is the first detection of consistent multiplet structure in the amplitude spectrum of a cool ZZ Ceti star and it allows us to determine the star's rotation period: 1.70 +/- 0.11 d. We report exactly equal frequency, not period, spacings between the detected mode groups. In addition, certain pairs of modes from the four principal groups have frequency ratios which are very close to 3:4 or 4:5; while these ratios are nearly exact (within one part in 10^4), they still lie outside the computed error bars. We speculate that these relationships between different frequencies could be caused by resonances. One of the three triplets may not be constant in amplitude and/or frequency. We compare our frequency solution for the combination frequencies (of which we detected 38) to Wu's (1998, 2001) model thereof. We obtain consistent results when trying to infer the star's convective thermal time and the inclination angle of its rotational axis. Theoretical combination-frequency amplitude spectra also resemble those of the observations well, and direct theoretical predictions of the observed second-order light-curve distortions were also reasonably successful assuming the three triplets are due to l=1 modes. Attempts to reproduce the observed combination frequencies adopting all possible l=2 identifications for the triplets did not provide similarly consistent results, supporting their identification with l=1.Comment: Accepted for publication in MNRAS; 12 pages, 8 figure

Display/control requirements for VTOL aircraft

Quantative metrics were determined for system control performance, workload for control, monitoring performance, and workload for monitoring. Pilot tasks were allocated for navigation and guidance of automated commercial V/STOL aircraft in all weather conditions using an optimal control model of the human operator to determine display elements and design