5,518 research outputs found

    Elastic scattering of intermediate-energy electrons from C_(60) molecules

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    Experimental and calculated differential cross sections for elastic scattering of electrons by C_(60) molecules at collision energies of 100 to 500 eV are reported. The elastic differential cross sections were measured in a standard crossed-beam apparatus, while the calculations were performed employing the Schwinger multichannel technique at the static-exchange level. Diffraction effects, some due to the overall spherical-cage structure and some to scattering by individual C atoms, are observed in both the measured and calculated cross sections

    Synthesis and methane cracking activity of a silicon nitride supported vanadium nitride nanoparticle composite

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    The co-ammonolysis of V(NMe2)4 and Si(NHMe)4 with ammonia in THF and in the presence of ammonium triflate ([NH4][CF3SO3]) leads to the formation of monolithic gels. Pyrolysing these gels produces mesoporous composite materials containing nanocrystalline VN and amorphous silicon imidonitride. Elemental mapping indicated a thorough distribution of VN with no evidence of large cluster segregation. Whilst not active for ammonia synthesis, the silicon nitride based materials were found to possess activity for the COx-free production of H2 from methane, which makes them candidates for applications in which the presence of low levels of CO in H2 feedstreams is detrimental

    The importance of social relations in shaping energy demand

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    Current efforts to change patterns of energy demand tend to target people as discrete and isolated individuals. In so doing, they ignore the fact that energy use occurs in places such as homes, workplaces and communities in which complex webs of social relations already exist. Here, we argue that more attention should be paid to how people’s social relations influence energy demand. We review recent qualitative research to show how social relations shape how much energy people use, when and where they use it, as well as how they respond to interventions. We propose a typology that identifies three types of social relation as especially significant: those with family and friends, with agencies and communities, and those associated with social identities. We show how a focus on social relations can generate new forms of policy and intervention in efforts to build more just and sustainable energy futures

    Hot methane line lists for exoplanet and brown dwarf atmospheres

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    We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300 - 1400 degC at twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns) region of the infrared. This range encompasses the dyad, pentad and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH4 spectra, we have estimated empirical lower state energies (Elow in cm-1) and our values have been incorporated into the line lists along with line positions (cm-1) and calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal referenc

    Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes

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    We report the results of a spectroscopic study of the Bootes (Boo) dwarf spheroidal (dSph) galaxy carried out with the WIYN telescope and the Hydra multifiber spectrograph. Radial velocities have been measured for 58 Boo candidate stars selected to have magnitudes and colors consistent with its red and asymptotic giant branches. Within the 13' half-light radius, seven members of Boo yield a systemic velocity of V_r=95.6+-3.4 km/s and a velocity dispersion of 6.6+-2.3 km/s. This implies a mass on the order of 1 x 10^7 M_sun, similar to the inferred masses of other Galactic dSphs. Adopting a total Boo luminosity of L=1.8 x 10^4 L_sun to 8.6 x 10^4 L_sun implies M/L ~ 610 to 130, making Boo, the most distorted known Milky Way dwarf galaxy, potentially also the darkest. From the spectra of Boo member stars we estimate its metallicity to be [Fe/H] ~ -2.5, which would make it the most metal poor dSph known to date.Comment: Accepted for publication in ApJ Letter

    Systemic threats to the growth mindset: classroom experiences of agency among children designated as 'lower-attaining'

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    In this paper, the authors consider how Carol Dweck’s concept of growth mindset has been misconceptualised. They explore the proposition that agency is an important aspect of growth mindset and that the effects of hard work by children is reduced when agency is limited. They draw on qualitative data from 84 interviews with 23 participant children who had been designated at the end of their Year 3 as ‘lower-attainers’ in mathematics, English or both. They explore their experiences of this designation across the first two years of the five-year project. Their findings suggested that participants displayed ample capacity for action, curiosity, engagement and creative learning. However, classroom rules sometimes mitigated against children benefiting from these capacities. Children narrated adopting the performance orientation suggested by Dweck, which could lead to a reduced sense of competence, which itself led to less agentic classroom behaviours
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