945 research outputs found

    PEN as self-vetoing structural Material

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    Polyethylene Naphtalate (PEN) is a mechanically very favorable polymer. Earlier it was found that thin foils made from PEN can have very high radio-purity compared to other commercially available foils. In fact, PEN is already in use for low background signal transmission applications (cables). Recently it has been realized that PEN also has favorable scintillating properties. In combination, this makes PEN a very promising candidate as a self-vetoing structural material in low background experiments. Components instrumented with light detectors could be built from PEN. This includes detector holders, detector containments, signal transmission links, etc. The current R\&D towards qualification of PEN as a self-vetoing low background structural material is be presented.Comment: 4 pages, 7 figures, contribution to Proceedings of the sixth workshop on Low Radioactivity Techniques 2017, 23-27 May 2017 Seoul, to be published at AIP, editor: D. Leonar

    Contrasting Pressure Effects in Sr2VFeAsO3 and Sr2ScFePO3

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    We report the resistivity measurements under pressure of two Fe-based superconductors with a thick perovskite oxide layer, Sr2VFeAsO3 and Sr2ScFePO3. The superconducting transition temperature Tc of Sr2VFeAsO3 markedly increases with increasing pressure. Its onset value, which was Tc{onset}=36.4 K at ambient pressure, increases to Tc{onset}=46.0 K at ~4 GPa, ensuring the potential of the "21113" system as a high-Tc material. However, the superconductivity of Sr2ScFePO3 is strongly suppressed under pressure. The Tc{onset} of ~16 K decreases to ~5 K at ~4 GPa, and the zero-resistance state is almost lost. We discuss the factor that induces this contrasting pressure effect.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jpn. No.12 (2009

    Superconductivity Near a Quantum Critical Point in Ba(Fe,Co)2As2

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    We will examine the possible link between spin fluctuations and the superconducting mechanism in the iron-based high temperature superconductor Ba(Fe,Co)2As2 based on NMR and high pressure transport measurements.Comment: Invited paper to m2s-IX (2009

    Comments on the distribution of \u3ci\u3eBotrychium lunarioides\u3c/i\u3e (Ophioglossaceae) in Texas

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    Botrychium lunarioides (Michx.) Sw. (Ophioglossaceae) is now known to be widespread and abundant throughout the eastern portion of Texas. In 1996, Do, et al. reported ten additional county records in the central portion of the Post Oak Savannah of Texas, thereby extending the known distribution of the species up to 273 km to the west. Additional field studies during 1996 have yielded nineteen new county records for the species in Texas. These new reports are primarily from the Post Oak Savannah, Pineywoods, and Blackland Prairies of northeast Texas and from the southern portion of the Post Oak Savannah. The most notable occurrence of the species is at Lake Bastrop State Recreation Area, Bastrop County, about 45 km ESE of Austin, which extends both the western and southern known limits of the species

    Does Taekwondo improve children's self-regulation? If so, how? A randomized field experiment

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    Emerging evidence suggests interventions can improve childhood self-regulation. One intervention approach that has shown promise is Taekwondo martial arts instruction, though little is known about its acceptability among stakeholders or its mechanisms of effect. We extend evidence on Taekwondo interventions in three ways: (a) testing the efficacy of a standard introductory course of Taekwondo, (b) assessing the acceptability of Taekwondo instruction among school children, and (c) investigating two self-regulatory mechanisms by which Taekwondo may operate (executive functions and motivation). This article reports findings from a randomized control trial implementing a standard 11-week beginners’ course of Taekwondo. Participants were from a mixed-sex, nonselective U.K. primary school (N = 240, age range 7 to 11 years). Measures of self-regulation included teacher-rated effortful control, impulsivity, prosocial behavior, and conduct problems; computer-based assessments of executive functions; and child self-reported expectancies and values to use self-regulation. Postintervention, children in the Taekwondo condition were rated by teachers as having fewer symptoms of conduct problems and better effortful control (specifically attentional control), and they also had better executive attention assessed by a flanker task. Effects were not found for teacher-rated inhibitory control, activation control, impulsivity, and prosocial behavior or for assessments of response inhibition, verbal working memory, and switching. Taekwondo was rated very positively by children. Finally, there was evidence that children who completed Taekwondo classes reported higher expectancies and values to use self-regulation and that expectancies and values mediated intervention effects on self-regulation. We conclude that short standard Taekwondo courses are well received by pupils, improve attentional self-regulation, and reduce symptoms of conduct problems

    Spatially Resolving Substructures within the Massive Envelope around an Intermediate-mass Protostar: MMS 6/OMC-3

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    With the Submillimeter Array, the brightest (sub)millimeter continuum source in the OMC-2/3 region, MMS 6, has been observed in the 850 um continuum emission with approximately 10 times better angular resolution than previous studies (~0.3"; ~120 AU at Orion). The deconvolved size, the mass, and the column density of MMS 6-main are estimated to be 0.32"x0.29" (132 AUx120 AU), 0.29 Mo, and 2.1x10^{25} cm^{-2}, respectively. The estimated extremely high mean number density, 1.5x10^{10} cm^{-3}, suggests that MMS 6-main is likely optically thick at 850 um. We compare our observational data with three theoretical core models: prestellar core, protostellar core + disk-like structure, and first adiabatic core. These comparisons clearly show that the observational data cannot be modeled as a simple prestellar core with a gas temperature of 20 K. A self-luminous source is necessary to explain the observed flux density in the (sub)millimeter wavelengths. Our recent detection of a very compact and energetic outflow in the CO (3-2) and HCN (4-3) lines, supports the presence of a protostar. We suggest that MMS 6 is one of the first cases of an intermediate mass protostellar core at an extremely young stage. In addition to the MMS 6-main peak, we have also spatially resolved a number of spiky structures and sub-clumps, distributed over the central 1000 AU. The masses of these sub-clumps are estimated to be 0.066-0.073 Mo, which are on the order of brown dwarf masses. Higher angular resolution and higher sensitivity observations with ALMA and EVLA will reveal the origin and nature of these structures such as whether they are originated from fragmentations, spiral arms, or inhomogeneity within the disk-like structures/envelope.Comment: Accepted to Ap

    Pressure-induced superconductivity in Iron pnictide compound SrFe2As2

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    Electrical resistivity under high pressure have been measured on nominally pure SrFe2As2 up to 14 GPa. The resistivity drop appeared with increasing pressure, and we clearly observed zero resistivity. The maximum of superconducting transition temperature (Tc) is 38 K. The value is corresponding to the one of optimally doping AFe2As2 (A=Sr, Ba) system with K+ ions at the A2+ site.Comment: 10 pages, 2 figure
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