Measuring Galactic Extinction: A Test

We test the recently published all-sky reddening map of Schlegel, Finkbeiner & Davis (1998 [SFD]) using the extinction study of a region in the Taurus dark cloud complex by Arce & Goodman (1999 [AG]). In their study, AG use four different techniques to measure the amount and structure of the extinction toward Taurus, and all four techniques agree very well. Thus we believe that the AG results are a truthful representation of the extinction in the region and can be used to test the reliability of the SFD reddening map. The results of our test show that the SFD all-sky reddening map, which is based on data from COBE/DIRBE and IRAS/ISSA, overestimates the reddening by a factor of 1.3 to 1.5 in regions of smooth extinction with A_V > 0.5 mag. In some regions of steep extinction gradients the SFD map underestimates the reddening value, probably due to its low spatial resolution. We expect that the astronomical community will be using the SFD reddening map extensively. We offer this Letter as a cautionary note about using the SFD map in regions of high extinction (A_V > 0.5 mag), as it might not be giving accurate reddening values there.Comment: 14 pages (which include 2 pages of figures

Estimating Tariff Equivalents of Nontariff Barriers

International Relations/Trade,

Structural and optical properties of compensated microcrystalline silicon films

Boron-doped microcrystalline silicon films were deposited in a plasma enhanced chemical vapor deposition (PECVD) system using silane (SiH4) diluted in hydrogen, and diborane (B2H6) as a dopant gas. The effects of the Boron concentration on the optical and structural properties were investigated by the constant-photocurrent method (CPM) and atomic force microscopy (AFM) measurements. The variations in the optical constants (refractive index, absorption coefficient and optical gap) as a function of wavelength were carried out from the optical transmission and CPM spectra. By increasing the doping level, a systematic increase in the absorption coefficient spectra in the low-energy region between 0.7 - 1.2 eV was observed. It was found that the increase of Boron concentration in the samples results in changes of the grain size. Correlations between optical properties and the density of states (DOS) were also studied.Fil: Dussan, A.. Universidad Nacional de Colombia; ColombiaFil: Koropecki, Roberto Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Arce, Roberto Delio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Schmidt, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

A Bubbling Nearby Molecular Cloud: COMPLETE Shells in Perseus

We present a study on the shells (and bubbles) in the Perseus molecular cloud using the COMPLETE survey large-scale 12CO(1-0) and 13CO(1-0) maps. The twelve shells reported here are spread throughout most of the Perseus cloud and have circular or arc-like morphologies with a range in radius of about 0.1 to 3 pc. Most of them have not been detected before most likely as maps of the region lacked the coverage and resolution needed to distinguish them. The majority of the shells are coincident with infrared nebulosity of similar shape and have a candidate powering source near the center. We suggest they are formed by the interaction of spherical or very wide-angle winds powered by young stars inside or near the Perseus molecular cloud -a cloud that is commonly considered to be mostly forming low-mass stars. Two of the twelve shells are powered by high-mass stars close to the cloud, while the others appear to be powered by low or intermediate mass stars in the cloud. We argue that winds with a mass loss rate of about 10^-8 to 10^-6 M_sun/yr are required to produce the observed shells. Our estimates indicate that the energy input rate from these stellar winds is similar to the turbulence dissipation rate. We conclude that in Perseus the total energy input from both collimated protostellar outflows and powerful spherical winds from young stars is sufficient to maintain the turbulence in the molecular cloud. Large scale molecular line and IR continuum maps of a sample of clouds will help determine the frequency of this phenomenon in other star forming regions.Comment: 48 pages in total: 16 pages of text and references; 2 pages of tables; 30 figures (one page per figure). Accepted for publication in the Astrophysical Journa

Characterization and Synthesis of Pentafluorophenyl-terminated Hyperbranched Benzyl Ether Polymer

This poster was presented at the American Chemical Society in Denver, Colorado.https://scholarworks.uttyler.edu/student_posters/1005/thumbnail.jp

Smart and networking underwater robots in cooperation meshes : the swarms ECSEL : H2020 project

The work presented on this paper is aimed to explain the role that unmanned underwater vehicles (AUVs/ROVs) plays in the ECSEL-H2020 SWARMS project. The main goal of the project is to reduce the operational cost and increase the safety of tasks assigned to divers in these operations. This will be achieved enabling the AUVs/ROVs to work in a cooperative mesh. The challenge is to design and develop an integrated platform (a set of Software/Hardware components), incorporated into the current generation of underwater vehicles in order to improve autonomy, cooperation, robustness, cost-effectiveness, and reliability of the offshore operations. The first demonstration of the project will be performed at PLOCAN (Oceanic Platform of the Canary Islands) where these technologies will be validated on its first stage.Peer Reviewe

The COMPLETE Survey of Outflows in Perseus

We present a study on the impact of molecular outflows in the Perseus molecular cloud complex using the COMPLETE survey large-scale 12CO(1-0) and 13CO(1-0) maps. We used three-dimensional isosurface models generated in RA-DEC-Velocity space to visualize the maps. This rendering of the molecular line data allowed for a rapid and efficient way to search for molecular outflows over a large (~ 16 sq. deg.) area. Our outflow-searching technique detected previously known molecular outflows as well as new candidate outflows. Most of these new outflow-related high-velocity features lie in regions that have been poorly studied before. These new outflow candidates more than double the amount of outflow mass, momentum, and kinetic energy in the Perseus cloud complex. Our results indicate that outflows have significant impact on the environment immediately surrounding localized regions of active star formation, but lack the energy needed to feed the observed turbulence in the entire Perseus complex. This implies that other energy sources, in addition to protostellar outflows, are responsible for turbulence on a global cloud scale in Perseus. We studied the impact of outflows in six regions with active star formation within Perseus of sizes in the range of 1 to 4 pc. We find that outflows have enough power to maintain the turbulence in these regions and enough momentum to disperse and unbind some mass from them. We found no correlation between outflow strength and star formation efficiency for the six different regions we studied, contrary to results of recent numerical simulations. The low fraction of gas that potentially could be ejected due to outflows suggests that additional mechanisms other than cloud dispersal by outflows are needed to explain low star formation efficiencies in clusters.Comment: Published in The Astrophysical Journa