The Foggy Disks Surrounding Herbig Ae Stars: a Theoretical Study of the H2O Line Spectra

Water is a key species in many astrophysical environments, but it is particularly important in proto-planetary disks. So far,observations of water in these objects have been scarce, but the situation should soon change thanks to the Herschel satellite. We report here a theoretical study of the water line spectrum of a proto-planetary disk surrounding Ae stars. We show that several lines will be observable with the HIFI instrument onboard the Herschel Space Observatory. We predict that some maser lines could also be observable with ground telescopes and we discuss how the predictions depend not only on the adopted physical and chemical model but also on the set of collisional coefficients used and on the H2 ortho to para ratio through its effect on collisional excitation. This makes the water lines observations a powerful, but dangerous -if misused- diagnostic tool.Comment: Accepted for publication in ApJ Letter

Exotic Ground States: A Study in the Structural Effects on Frustration and Dimensionality

Structural disorder and dimensionality play central roles in the characterization of structure and properties of crystalline materials. Although structural disorder is commonly considered an undesirable quality, structural disorder may be desirable when searching for new materials with exotic properties. Disorder can be used as a tunable parameter when considering atomic sizes, coordination preferences, and electronegativity differences can be varied by substituting elements into a given structure. Dimensionality can be viewed as another adjustable parameter when searching for new materials presenting unique challenges when characterizing new materials. One way to tune dimensionality is by chemical doping to affect coupling between layers/chains. The growth of phases with inherent structural disorder often involves tuning at the edge of structural stability which necessitates careful adjustment of synthetic parameters and presents unique characterization challenges. Understanding the effects of disorder and dimensionality could lead to better understanding of complex behavior. Many materials with exotic magnetic ground states exhibit magnetic frustration in one form or another. Magnetic frustration is a term which loosely describes the suppression of long-range magnetic ordering to temperatures much lower than the Weiss temperature in phases with magnetic correlations. Three parameters linked to magnetic frustration include: geometry of the magnetic sublattice, site disorder, and the effective dimensionality of the magnetic sublattice. Often these three parameters are inseparable in real systems, and investigating the fundamental differences between these geometrical frustration, structural disorder, and dimensionality would be of significant interest. This dissertation presents the growth, structure, and properties of single crystals of 3-d structurally disordered intermetallic phases Ln2Ag1-xGa10-y (Ln = La, Ce) and â-LnNiGa4 (Ln = Tb-Er), 2-d frustrated spin glasses MAl2S4 (M = Mn, Fe, Co, Ni), and quasi-1-d quantum, antiferromagnet K4Cu(MoO4)3 to highlight the effects of structural disorder and dimensionality on magnetic ground states

On the stratified dust distribution of the GG Tau circumbinary ring

Our objective is to study the vertical dust distribution in the circumbinary ring of the binary system GG Tau and to search for evidence of stratification, one of the first steps expected to occur during planet formation. We present a simultaneous analysis of four scattered light images spanning a range of wavelength from 800 nm to 3800 nm and compare them with (i) a parametric prescription for the vertical dust stratification, and (ii) with the results of SPH bi-fluid hydrodynamic calculations. The parametric prescription and hydrodynamical calculations of stratification both reproduce the observed brightness profiles well. These models also provide a correct match for the observed star/ring integrated flux ratio. Another solution with a well-mixed, but ``exotic'', dust size distribution also matches the brightness profile ratios but fails to match the star/ring flux ratio. These results give support to the presence of vertical stratification of the dust in the ring of GG Tau and further predict the presence of a radial stratification also.Comment: 9 pages, 11 figures. Accepted for publication in A&

MR-Guided Interventions for Prostate Cancer

Cataloged from PDF version of article.MR imaging is currently the most effective diagnostic imaging tool for visualizing the anatomy and pathology of the prostate gland. Currently, the practicality and cost effectiveness of transrectal ultrasound dominates image guidance for needle-based prostate interventions. Challenges to the integration of diagnostic and interventional MR imaging have included the lack of real-time feedback, the complexity of the imaging technique, and limited access to the perineum within the geometric constraints of the MR imaging scanner. Two basic strategies have been explored and clinically demonstrated in the literature: (1) coregistration of previously acquired diagnostic MR imaging to interventional TRUS or open scanner MR images, and (2) stereotactic needle interventions within conventional diagnostic scanners using careful patient positioning or the aid of simple manipulators. Currently, researchers are developing techniques that render MR imaging the method of choice for the direct guidance of many procedures. This article focuses on needle-based interventions for prostate cancer, including biopsy, brachytherapy, and thermal therapy. With rapid progress in biologic imaging of the prostate gland, the authors believe that MR imaging guidance will play an increasing role in the diagnosis and treatment of prostate cancer. © 2005 Elsevier Inc. All rights reserved

Where is the warm H2 ? A search for H2 emission from disks around Herbig Ae/Be stars

Mid-IR emission lines of H2 are useful probes to determine the mass of warm gas present in the surface layers of disks. Numerous observations of Herbig Ae/Be stars (HAeBes) have been performed, but only 2 detections of mid-IR H2 toward HD97048 and AB Aur have been reported. We aim at tracing the warm gas in the disks of 5 HAeBes with gas-rich environments and physical characteristics close to those of AB Aur and HD97048, to discuss whether the detections toward these 2 objects are suggestive of peculiar conditions for the gas. We search for the H2 S(1) emission line at 17.035 \mu\m with VISIR, and complemented by CH molecule observations with UVES. We gather the H2 measurements from the literature to put the new results in context and search for a correlation with some disk properties. None of the 5 VISIR targets shows evidence for H2 emission. From the 3sigma upper limits on the integrated line fluxes we constrain the amount of optically thin warm gas to be less than 1.4 M_Jup in the disk surface layers. There are now 20 HAeBes observed with VISIR and TEXES instruments to search for warm H2, but only two detections (HD97048 and AB Aur) were made so far. We find that the two stars with detected warm H2 show at the same time high 30/13 \mu\m flux ratios and large PAH line fluxes at 8.6 and 11.3 \mu\m compared to the bulk of observed HAeBes and have emission CO lines detected at 4.7 \mu\m. We detect the CH 4300.3A absorption line toward both HD97048 and AB Aur with UVES. The CH to H2 abundance ratios that this would imply if it were to arise from the same component as well as the radial velocity of the CH lines both suggest that CH arises from a surrounding envelope, while the detected H2 would reside in the disk. The two detections of the S(1) line in the disks of HD97048 and AB Aur suggest either peculiar physical conditions or a particular stage of evolution.Comment: accepted for publication in A&A : 10 pages, 6 figure

An Evaluation of Tennessee Soybean Growers’ Views on a New Generation Cooperative to Produce Biodiesel

Substituting petroleum diesel with biodiesel could decrease air emissions, reduce reliance on foreign oil, and help expand markets for U.S. farmers. Soybean producers can potentially capture this value-added by forward integrating the processing of soybeans into biodiesel via a New Generation Cooperative (NGC). Using probit analysis, this study examines factors influencing soybean producers’ willingness to participate in an NGC to produce biodiesel. Tobit analysis is used to examine the factors influencing the number of shares the soybean producer would be willing to purchase. Survey results indicate that over 70% of the soybean producers in the study group are interested in investing in an NGC to produce biodiesel. Among those producers willing to participate, the average number of shares they would purchase was just under 3,460.biodiesel, New Generation Cooperative, probit analysis, soybean producers, tobit analysis, Marketing, Research Methods/ Statistical Methods,

Proximity effect between two superconductors spatially resolved by scanning tunneling spectroscopy

We present a combined experimental and theoretical study of the proximity effect in an atomic-scale controlled junction between two different superconductors. Elaborated on a Si(111) surface, the junction comprises a Pb nanocrystal with an energy gap of 1.2 meV, connected to a crystalline atomic monolayer of lead with a gap of 0.23 meV. Using in situ scanning tunneling spectroscopy we probe the local density of states of this hybrid system both in space and in energy, at temperatures below and above the critical temperature of the superconducting monolayer. Direct and inverse proximity effects are revealed with high resolution. Our observations are precisely explained with the help of a self-consistent solution of the Usadel equations. In particular, our results demonstrate that in the vicinity of the Pb islands, the Pb monolayer locally develops a finite proximity-induced superconducting order parameter, well above its own bulk critical temperature. This leads to a giant proximity effect where the superconducting correlations penetrate inside the monolayer a distance much larger than in a non-superconducting metal.Comment: 13 pages, 14 figures, accepted for publication in Physical Review

CONSUMER PREFERENCES FOR ELECTRICITY FROM BIOENERGY AND OTHER RENEWABLES

This study ascertains residential electricity consumers' support and willingness to pay for electricity from renewable sources. Then, willingness to pay for specified renewable energy sources (solar, wind, landfill wastes, bioenergy from fast growing crops, and bioenergy from forest products wastes). Effects of demographics and environmental behaviors are estimated.Institutional and Behavioral Economics,

Video modules for online learning: Creating content for the new normal.

15-minute Webinar PresentationIn order to supplement the Evidence based medicine (EBM) curriculum that Ruth Lilly Medical Library teaches to 1st and 2nd year medical undergraduates, two librarians created four short videos on EBM topics. Join us for this interactive session focused on teaching the skills and techniques used in video creation such as: modified story-boarding for script creation and presentation software design, calculation of video length as well as methods used to practice and record the videos. We will provide lessons learned and also have ample time for questions from the audience.ACRL Health Sciences Interest Grou