A Single Circumbinary Disk in the HD 98800 Quadruple System

We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'' (38 AU), each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optically fainter binary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 150 K, indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary. We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity. Given the data, the most-likely values of disk properties in the ranges considered are R_in = 5.0 +/- 2.5 AU, DeltaR = 13+/-8 AU, lambda_0 = 2(+4/-1.5) microns, gamma = 0+/-2.5, and sigma_total = 16+/-3 AU^2, where R_in is the inner radius, DeltaR is the radial extent of the disk, lambda_0 is the effective grain size, gamma is the radial power-law exponent of the optical depth, tau, and sigma_total is the total cross-section of the grains. The range of implied disk masses is 0.001--0.1 times that of the moon. These results show that, for a wide range of possible disk properties, a circumbinary disk is far more likely than a narrow ring.Comment: 11 page Latex manuscript with 3 postscript figures. Accepted for publication in Astrophysical Journal Letters. Postscript version of complete paper also available at http://www.hep.upenn.edu/PORG/web/papers/koerner00a.p

Committee Reports

Contains reports from the following committees of the Washington State Bar Association: Administrative Law, Civil Rights, Code Commission, Cooperation with American Bar Association, Federal Legislation, Improvement of Probate Statutes, Law Examiners, Legal Education, Legal Ethics, Legal Institutes, Legislative, Obituary, Selection of Judges, and Unauthorized Practice of Law. Also includes the auditor\u27s report

A double-lined spectroscopic orbit for the young star HD 34700

We report high-resolution spectroscopic observations of the young star HD 34700, which confirm it to be a double-lined spectroscopic binary. We derive an accurate orbital solution with a period of 23.4877 +/- 0.0013 days and an eccentricity of e = 0.2501 +/- 0.0068. The stars are found to be of similar mass (M2/M1 = 0.987 +/- 0.014) and luminosity. We derive also the effective temperatures (5900 K and 5800 K) and projected rotational velocities (28 km/s and 22 km/s) of the components. These values of v sin i are much higher than expected for main-sequence stars of similar spectral type (G0), and are not due to tidal synchronization. We discuss also the indicators of youth available for the object. Although there is considerable evidence that the system is young --strong infrared excess, X-ray emission, Li I 6708 absorption (0.17 Angstroms equivalent width), H alpha emission (0.6 Angstroms), rapid rotation-- the precise age cannot yet be established because the distance is unknown.Comment: 17 pages, including 2 figures and 2 tables. Accepted for publication in AJ, to appear in February 200

The Circumstellar Disk of HD 141569 Imaged with NICMOS

Coronagraphic imaging with the Near Infrared Camera and Multi Object Spectrometer on the Hubble Space Telescope reveals a large, ~400 AU (4'') radius, circumstellar disk around the Herbig Ae/Be star HD 141569. A reflected light image at 1.1 micron shows the disk oriented at a position angle of 356 +/- 5 deg and inclined to our line of sight by 51 +/- 3 deg; the intrinsic scattering function of the dust in the disk makes the side inclined toward us, the eastern side, brighter. The disk flux density peaks 185 AU (1.''85) from the star and falls off to both larger and smaller radii. A region of depleted material, or a gap, in the disk is centered 250 AU from the star. The dynamical effect of one or more planets may be necessary to explain this morphology.Comment: 4 pages, LaTeX with emulateapj.sty and epsfig.sty, 4 postscript figures, Accepted to ApJ Letter

Technical evaluation of the mEducator 3.0 linked data-based environment for sharing medical educational resources

mEducator 3.0 is a content sharing approach for medical education, based on Linked Data principles. Through standardization, it enables sharing and discovery of medical information. Overall the mEducator project seeks to address the following two different approaches, mEducator 2.0, based on web 2.0 and ad-hoc Application Programmers Interfaces (APIs), and mEducator 3.0, which builds upon a collection of Semantic Web Services that federate existing sources of medical and Technology Enhanced Learning (TEL) data. The semantic mEducator 3.0 approach It has a number of different instantiations, allowing flexibility and choice. At present these comprise of a standalone social web-based instantiation (MetaMorphosis+) and instantiations integrated with Drupal, Moodle and OpenLabyrinth systems. This paper presents the evaluation results of the mEducator 3.0 Linked Data based environment for sharing medical educational resources and focuses on metadata enrichment, conformance to the requirements and technical performance (of the MetaMorphosis+ and Drupal instantiations)

Limiting Carleman weights and anisotropic inverse problems

In this article we consider the anisotropic Calderon problem and related inverse problems. The approach is based on limiting Carleman weights, introduced in Kenig-Sjoestrand-Uhlmann (Ann. of Math. 2007) in the Euclidean case. We characterize those Riemannian manifolds which admit limiting Carleman weights, and give a complex geometrical optics construction for a class of such manifolds. This is used to prove uniqueness results for anisotropic inverse problems, via the attenuated geodesic X-ray transform. Earlier results in dimension $n \geq 3$ were restricted to real-analytic metrics.Comment: 58 page

Brain connectivity and socioeconomic status at birth and externalizing symptoms at age 2 years

Low childhood socioeconomic status (SES) predisposes individuals to altered trajectories of brain development and increased rates of mental illness. Brain connectivity at birth is associated with psychiatric outcomes. We sought to investigate whether SES at birth is associated with neonatal brain connectivity and if these differences account for socioeconomic disparities in infant symptoms at age 2 years that are predictive of psychopathology. Resting state functional MRI was performed on 75 full-term and 37 term-equivalent preterm newborns (n = 112). SES was characterized by insurance type, the Area Deprivation Index, and a composite score. Seed-based voxelwise linear regression related SES to whole-brain functional connectivity of five brain regions representing functional networks implicated in psychiatric illnesses and affected by socioeconomic disadvantage: striatum, medial prefrontal cortex (mPFC), ventrolateral prefrontal cortex (vlPFC), and dorsal anterior cingulate cortex. Lower SES was associated with differences in striatum and vlPFC connectivity. Striatum connectivity with frontopolar and medial PFC mediated the relationship between SES and behavioral inhibition at age 2 measured by the Infant-Toddler Social Emotional Assessment (n = 46). Striatum-frontopolar connectivity mediated the relationship between SES and externalizing symptoms. These results, convergent across three SES metrics, suggest that neurodevelopmental trajectories linking SES and mental illness may begin as early as birth

Sigma viruses from three species of Drosophila form a major new clade in the rhabdovirus phylogeny

The sigma virus (DMelSV), which is a natural pathogen of Drosophila melanogaster, is the only Drosophila-specific rhabdovirus that has been described. We have discovered two new rhabdoviruses, D. obscura and D. affinis, which we have named DObsSV and DAffSV, respectively. We sequenced the complete genomes of DObsSV and DMelSV, and the L gene from DAffSV. Combining these data with sequences from a wide range of other rhabdoviruses, we found that the three sigma viruses form a distinct clade which is a sister group to the Dimarhabdovirus supergroup, and the high levels of divergence between these viruses suggest that they deserve to be recognized as a new genus. Furthermore, our analysis produced the most robustly supported phylogeny of the Rhabdoviridae to date, allowing us to reconstruct the major transitions that have occurred during the evolution of the family. Our data suggest that the bias towards research into plants and vertebrates means that much of the diversity of rhabdoviruses has been missed, and rhabdoviruses may be common pathogens of insects

The Frequency of Mid-Infrared Excess Sources in Galactic Surveys

We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8 micron mid-infrared extraphotospheric excesses in the MidCourse Space Experiment (MSX) and Spitzer Space Telescope Galactic Legacy MidPlane Survey Extraordinaire (GLIMPSE) surveys. Of these, 183 are either OB stars earlier than B8 in which the excess plausibly arises from a thermal bremsstrahlung component or evolved stars in which the excess may be explained by an atmospheric dust component. The remaining 47 stars have spectral classifications B8 or later and appear to be main sequence or late pre-main-sequence objects harboring circumstellar disks. Six of the 47 stars exhibit multiple signatures characteristic of pre-main-sequence circumstellar disks, including emission lines, near-infrared K-band excesses, and X-ray emission. Approximately one-third of the remaining 41 sources have emission lines suggesting relative youth. Of the 25 GLIMPSE stars with SST data at >24 microns, 20 also show an excess at 24 microns. Three additional objects have 24 micron upper limits consistent with possible excesses, and two objects have photospheric measurements at 24 microns. Six MSX sources had a measurement at wavelengths >8 microns. We modeled the excesses in 26 stars having two or more measurements in excess of the expected photospheres as single-component blackbodies. We determine probable disk temperatures and fractional infrared luminosities in the range 191 < T < 787 and 3.9x10^-4 < L_IR/L_* < 2.7x10^-1. We estimate a lower limit on the fraction of Tycho-2 Spectral Catalog main-sequence stars having mid-IR, but not near-IR, excesses to be 1.0+-0.3%.Comment: Accepted to Ap

Efficient implementation of selective recoupling in heteronuclear spin systems using Hadamard matrices

We present an efficient scheme which couples any designated pair of spins in heteronuclear spin systems. The scheme is based on the existence of Hadamard matrices. For a system of $n$ spins with pairwise coupling, the scheme concatenates $cn$ intervals of system evolution and uses at most $c n^2$ pulses where $c \approx 1$. Our results demonstrate that, in many systems, selective recoupling is possible with linear overhead, contrary to common speculation that exponential effort is always required.Comment: 7 pages, 4 figures, mypsfig2, revtex, submitted April 27, 199