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Social anxiety disorder (SAD) is characterized by fear of social and performance situations. The consequence of scrutiny by others for the neural processing of performance feedback in SAD is unknown.
We used event-related functional magnetic resonance imaging to investigate brain activation to positive, negative, and uninformative performance feedback in patients diagnosed with SAD and age-, gender-, and education-matched healthy control subjects who performed a time estimation task during a social observation condition and a non-social control condition: while either being monitored or unmonitored by a body camera, subjects received performance feedback after performing a time estimation that they could not fully evaluate without external feedback.
We found that brain activation in ventral striatum (VS) and midcingulate cortex was modulated by an interaction of social context and feedback type. SAD patients showed a lack of social-context-dependent variation of feedback processing, while control participants showed an enhancement of brain responses specifically to positive feedback in VS during observation.
The present findings emphasize the importance of social-context processing in SAD by showing that scrutiny prevents appropriate reward-processing-related signatures in response to positive performances in SAD.
This paper briefly describes the principle of operation and science goals of the AMANDA high energy neutrino telescope located at the South Pole, Antarctica. Results from an earlier phase of the telescope, called AMANDA-BIO, demonstrate both reliable operation and the broad astrophysical reach of this device, which includes searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, Gamma-Ray Bursts and diffuse sources. The predicted sensitivity and angular resolution of the telescope were confirmed by studies of atmospheric muon and neutrino backgrounds. We also report on the status of the analysis from AMANDA-II, a larger version with far greater capabilities. At this stage of analysis, details of the ice properties and other systematic uncertainties of the AMANDA-II telescope are under study, but we have made progress toward critical science objectives. In particular, we present the first preliminary flux limits from AMANDA-II on the search for continuous emission from astrophysical point sources, and report on the search for correlated neutrino emission from Gamma Ray Bursts detected by BATSE before decommissioning in May 2000. During the next two years, we expect to exploit the full potential of AMANDA-II with the installation of a new data acquisition system that records full waveforms from the in-ice optical sensors.
We have analyzed a sample of 1150 type ab, and 550 type c RR Lyrae stars found in 24 of 94 bulge fields of the MACHO database. These fields cover a range in Galactocentric distances from 0.3 to 1.6 kpc. In combination with the data on the outer bulge fields of Alard (1997) and Wesselink (1987), here we present the surface density distribution of bulge RR Lyrae between 0.3 and 3 kpc.
The MACHO microlensing experiment's time-sampled photometry database contains blue and red lightcurves for nearly 9 million stars in the central bar region of the Large Magellanic Cloud (LMC). We have identified known LMC Planetary Nebulae (PN) in the database and find one, Jacoby 5, to be variable. We additionally present data on the “parent populations” of LMC PN, and discuss the star formation history of the LMC bar.
We positionally match sources observed by the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey. Practically all 2MASS sources are matched to an SDSS source within 2 arcsec; ~11% of them are optically resolved galaxies and the rest are dominated by stars. About 1/3 of FIRST sources are matched to an SDSS source within 2 arcsec; ~80% of these are galaxies and the rest are dominated by quasars. Based on these results, we project that by the completion of these surveys the matched samples will include about 107 stars and 106 galaxies observed by both SDSS and 2MASS, and about 250,000 galaxies and 50,000 quasars observed by both SDSS and FIRST. Here we present a preliminary analysis of the optical, infrared and radio properties for the extragalactic sources from the matched samples. In particular, we find that the fraction of quasars with stellar colors missed by the SDSS spectroscopic survey is probably not larger than ~10%, and that the optical colors of radio-loud quasars are ~0.05 mag. redder (with 4σ significance) than the colors of radio-quiet quasars.
A review of the properties of Type II Cepheids and RV Tauri stars in the Magellanic Clouds is presented. In the behaviour of their light and colour curves, the RV Tauri stars appear to be a direct extension of the Type II Cepheids to longer periods. A single P – L – C relationship describes both the Type II Cepheids and RV Tauri stars in the LMC. The derived high intrinsic magnitudes for the RV Tauri variables supports the proposition that these objects are luminous stars evolving off the AGB. Preliminary analysis of the long time-series MACHO photometry indicates one star (MACHO*05:37:45.0–69:54:16) has an obvious ‘period-quadrupled’ periodicity, which is supporting evidence for a period-doubling bifurcation transition to chaotic pulsations.
We present the first results of the analysis of 22 Blazhko stars. We find: 1) Blazhko RRab stars that are nearly pure amplitude modulators; 2) Blazhko RRab stars that have both amplitude and phase modulation; 3) A Blazhko RRab star that has an abrupt period change; 4) Proof of the Blazhko effect in RRc stars. Our data show the character of the amplitude and phase modulations of the light curves over the Blazhko cycles far better than has been previously possible.
We present the preliminary results of a frequency analysis of 1457 fundamental mode RR Lyrae (RR0) stars in the Large Magellanic Cloud (LMC) from MACHO Project photometry. We find the same classes of pulsational behavior as were found in our earlier survey of first overtone RR Lyrae (RR1) stars. Variables whose prewhitened power spectra contain one or two peaks close to the main frequency component in the original power spectra are commonly known as Blazhko-type variables. The present analysis shows the overall frequency of Blazhko-type stars in the total RR0 population analysed to date to be ≈ 10%. This is lower than the often cited Galactic field/globular rate of 20-30% (Szeidl, 1988).
The incidence rate of Blazhko-type variability in the LMC appears to be about three times higher in RR0 stars than in RR1 stars. This puts important constraints on possible models of the Blazhko effect.
We present the first massive frequency analysis of the 1200 first overtone RR Lyrae stars in the Large Magellanic Cloud observed in the first 4.3 yr of the MACHO project. Besides the many new double-mode variables, we also discovered stars with closely spaced frequencies. These variables are most probably nonradial pulsators.
EMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The primary goal of EMU is to make a deep (rms ∼ 10 μJy/beam) radio continuum survey of the entire Southern sky at 1.3 GHz, extending as far North as +30° declination, with a resolution of 10 arcsec. EMU is expected to detect and catalogue about 70 million galaxies, including typical star-forming galaxies up to z ∼ 1, powerful starbursts to even greater redshifts, and active galactic nuclei to the edge of the visible Universe. It will undoubtedly discover new classes of object. This paper defines the science goals and parameters of the survey, and describes the development of techniques necessary to maximise the science return from EMU.
Time-resolved imagery is presented showing the changes that occur in the focal volume of dilute liquid/particle suspensions following the arrival of single, Q-switched, frequency-doubled, Nd:YAG laser pulses. Limiting data and corresponding imagery at 21, 84, 244, 790, and 2900 nanoseconds following the laser pulse are presented for a carbon particle suspension consisting of used (carbonized) 1OW-15 motor oil and for a suspension of the inorganic metallic cluster molecule Mo2Ag4S8 [PPh3]4. The images in conjunction with the accompanying limiting data show that the reduction in transmission, observed as the input pulse energy is increased, results from scattering from bubbles augmented by plasma absorption. Keywords: laser induced breakdown, plasma, suspension, bubble, nonlinear materials, shadowgraph, imagery
Pulsed-laser shadowgraphs and images of scattered light are combined with limiting and scattering data to build a model of the response of silicon napthalocyanine (SiNc) at concentrations on the order of 10−3 M in toluene to 12–16 ns 532 nm laser pulses over an energy range from 10 nJ to 2 mJ. The inherent spherical aberration induced by the sample has a profound effect on the response. The scattering is extremely intense above pulse energies of 100 μJ. The data indicates the response at pulse energies below 300 mJ is due to reverse saturable absorption. Full absorbance is not observed until the agglomerates vaporize. At fluences approaching 1 J/cm2 a plasma begins to form and the liquid near the window starts to boil. Intense scatter from the boiling liquid combined with plasma absorption produces hard clamping.
We present a new mask design and implantation scheme, which uses one single ion implantation step of 2 MeV He ions at a dose of 7–1014 to 3–1015 He/cm2 to form channel waveguides in single crystalline KNbO3. The special processing of the photoresist mask enables the formation of channel waveguides with a trapezoidal-shaped cross section, providing for the first time simultaneous confinement of both TE and TM modes in a permanent KNbO3 channel waveguide. 2.6 mW second-harmonic blue light at 441 nm was generated in a 5.8 mm long guide for a fundamental power of approx. 200 mW.
Functional and structural disturbances of the brain produced by sudden impact to the skull represent a fundamental problem in neurosurgical treatment of head trauma. A proper experimental approach to brain trauma requires the development of an adequate animal model useful in defining both the biomechanical and physiological variables relevant to mechanical injury to the human central nervous system (CNS). The development of appropriate animal models has proved essential to progress in other clinically related research and is a prerequisite for the development of rational modes of diagnosis and treatment of head injury.
Total energy electronic structure calculations are performed for the elements and selected binary ordered compounds of the ternary system Nb-Ru-Zr. These calculations provide binding energies, atomic volumes, bulk moduli, Debye temperatures, and Grüneiesen constants for the selected structures and compounds. Volume dependent pair and many-body chemical interactions are also obtained from the total energy results which, in turn, are used to study partially ordered alloys at finite temperatures. The stability of all the binary intermetallic compounds experimentally observed at low temperatures is correctly predicted by the first-principles calculations. The solid state portion of the Nb-Ru binary phase diagram is calculated using the chemical interactions obtained from the total energy calculations, a Debye-Grüneisen model for the vibrational free energy and the cluster variation method (CVM) for the configurational entropy with a local volume relaxation scheme. The calculations reproduce the experimentally observed ordering temperature of the NbRu3 intermetallic to within 2%.
Examples of the mass spectrometry of sputtered or evaporating neutral species obtained by SALI are presented for NBS Glass 610 (primarily a silicate), and an anodic oxide of HgCdTe. For the NBS glass, a SIMS spectra was recorded for comparison with SALI using the same apparatus. The raw SALI spectra of the glass is in semiquantitative accord with the known composition, in contrast to SIMS. Relative secondary ion yields can be determined for unknown complex materials by comparing SALI and SIMS spectra. Depth profiling measurements on the anodic oxides of Hg1−xCdxTe show a significant though depleted concentration of Hg in the oxide in contrast to numerous other analyses; this result is corroborated by RBS studies. Hg and also Te evaporation is monitored in real-time by SALI with large dynamic range capabilities.