Time filter

Source Type

Dempsey J.T.,Joint Astronomy Center | Bell G.S.,Joint Astronomy Center | Chrysostomou A.,University of Hertfordshire | Coulson I.M.,Joint Astronomy Center | And 8 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The James Clerk Maxwell Telescope (JCMT) is the largest single-dish submillimetre telescope in the world, and throughout its lifetime the volume and impact of its science output have steadily increased. A key factor for this continuing productivity is an ever-evolving approach to optimising operations, data acquisition, and science product pipelines and archives. The JCMT was one of the first common-user telescopes to adopt flexible scheduling in 2003, and its impact over a decade of observing will be presented. The introduction of an advanced data-reduction pipeline played an integral role, both for fast real-time reduction during observing, and for science-grade reduction in support of individual projects, legacy surveys, and the JCMT Science Archive. More recently, these foundations have facilitated the commencement of remote observing in addition to traditional on-site operations to further increase on-sky science time. The contribution of highly-trained and engaged operators, support and technical staff to efficient operations will be described. The long-term returns of this evolution are presented here, noting they were achieved in face of external pressures for leaner operating budgets and reduced staffing levels. In an era when visiting observers are being phased out of many observatories, we argue that maintaining a critical level of observer participation is vital to improving and maintaining scientific productivity and facility longevity. © 2014 SPIE. Source

Baeten D.,Catholic University of Leuven | Mathot V.B.F.,Catholic University of Leuven | Pijpers T.F.J.,Catholic University of Leuven | Verkinderen O.,Catholic University of Leuven | And 3 more authors.
Macromolecular Rapid Communications | Year: 2015

An experimental setup, making use of a Flash DSC 1 prototype, is presented in which materials can be studied simultaneously by fast scanning calorimetry (FSC) and synchrotron wide angle X-ray diffraction (WAXD). Accumulation of multiple, identical measurements results in high quality, millisecond WAXD patterns. Patterns at every degree during the crystallization and melting of high density polyethylene at FSC typical scanning rates from 20 up to 200 °C s-1 are discussed in terms of the temperature and scanning rate dependent material crystallinities and crystal densities. Interestingly, the combined approach reveals FSC thermal lag issues, for which can be corrected. For polyamide 11, isothermal solidification at high supercooling yields a mesomorphic phase in less than a second, whereas at very low supercooling crystals are obtained. At intermediate supercooling, mixtures of mesomorphic and crystalline material are generated at a ratio proportional to the supercooling. This ratio is constant over the isothermal solidification time. Simultaneously fast scanning chip calorimetry and wide-angle X-ray scattering experiments are performed. The crystallization and melting of high-density polyethylene at fast scanning calorimetry typical scanning rates from 20 up to 200 °C s-1 are discussed, as well as the isothermal crystallization of PA11 at high supercooling. The high-density polyethylene experiments reveal instrumental issues, whereas the PA11 study brings new insights on its polymorphic behavior. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Stawski T.M.,MESA Institute for Nanotechnology | Veldhuis S.A.,MESA Institute for Nanotechnology | Castricum H.L.,University of Amsterdam | Keim E.G.,MESA Institute for Nanotechnology | And 4 more authors.
Langmuir | Year: 2011

The structural evolution of sol-gel derived lead zirconate titanate (PZT) precursor films during and after physical drying was investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), selected area electron diffraction (SAED), and time-resolved X-ray diffraction (XRD). Films were deposited from initial 0.3 mol/dm 3 precursor sols with varying hydrolysis ratios. Zr-rich grains of 1-10 nm size, embedded in a Pb-, Zr-, and Ti-containing amorphous matrix were found in as-dried films. The Zr-rich regions were crystalline at hydrolysis ratios [H 2O]/[PZT] < 27.6, and amorphous at ratios > 100. X-ray diffraction analysis of PZT and zirconia sols revealed that the crystalline nanoparticles in both sols are identical and are probably composed of nanosized zirconium oxoacetate-like clusters. This study demonstrates that time-resolved X-ray diffraction combined with electron energy loss spectroscopy mapping is a powerful tool to monitor the nanoscale structural evolution of sol-gel derived thin films. © 2011 American Chemical Society. Source

Hosaka N.,Tokyo Metroplitan University | Hosaka N.,Research Institute of Japan Association for Advancement of Phyto Regulators | Kachi N.,Tokyo Metroplitan University | Kudoh H.,Kyoto University | And 2 more authors.
Plant Ecology | Year: 2016

In hardwood forests, clonal understory trees often develop patches of ramets that are interconnected via root systems. The patches are often partially disturbed by litter falling from the forest canopy, and patterns of damage can vary in size and the number of directly affected ramets. To test the effects of different types of disturbance on recovery and development of patches, we conducted a field experiment using the clonal understory tree, Asimina triloba in a hardwood forest of the northeastern USA. Either single large ramets or many small ramets were cut at their base, which removed about half of the aboveground biomass from each patch. Both types of disturbance did not change new ramet production, and the recovery response of A. triloba was primarily achieved by sprouting of damaged ramets. Three years after the manipulation, total aboveground biomass of disturbed patches recovered to pre-treatment levels without cost in terms of reduced growth or survival of undamaged ramets. These results suggest that A. triloba has the ability to persist under different types of disturbance and regrowth of damaged ramets is probably supported by the translocation of resources stored in root systems. On the other hand, damaged ramets grew less for the first year after the disturbance. New ramets also grew less in disturbed patches than in controls, especially where large ramets were damaged. In A. triloba, damage to large ramets may compromise sexual reproduction, which is limited to large ramets, and have negative impacts on new patch establishment via sexual reproduction. © 2016 Springer Science+Business Media Dordrecht Source

Xilouris E.M.,National institute for astrophysics | Tabatabaei F.S.,Max Planck Institute for Astronomy | Boquien M.,French National Center for Scientific Research | Kramer C.,Instituto Radioastronomia Milimetrica IRAM | And 26 more authors.
Astronomy and Astrophysics | Year: 2012

In the framework of the open-time key program "Herschel M 33 extended survey (HerM33es)", we study the far-infrared emission from the nearby spiral galaxy M 33 in order to investigate the physical properties of the dust such as its temperature and luminosity density across the galaxy. Taking advantage of the unique wavelength coverage (100, 160, 250, 350, and 500 μm) of the Herschel Space Observatory and complementing our dataset with Spitzer-IRAC 5.8 and 8 μm and Spitzer-MIPS 24 and 70 μm data, we construct temperature and luminosity density maps by fitting two modified blackbodies of a fixed emissivity index of 1.5. We find that the "cool" dust grains are heated to temperatures of between 11 K and 28 K, with the lowest temperatures being found in the outskirts of the galaxy and the highest ones both at the center and in the bright HII regions. The infrared/submillimeter total luminosity (5-1000 μm) is estimated to be 1.9 × 10 9 +4.0×108 -4.4×10 8 L ·. Fifty-nine percent of the total infrared/submillimeter luminosity of the galaxy is produced by the "cool" dust grains (∼15 K), while the remaining 41% is produced by "warm" dust grains (~55 K). The ratio of the cool-to-warm dust luminosity is close to unity (within the computed uncertainties), throughout the galaxy, with the luminosity of the cool dust being slightly higher at the center than the outer parts of the galaxy. Decomposing the emission of the dust into two components (one emitted by the diffuse disk of the galaxy and one emitted by the spiral arms), we find that the fraction of the emission from the disk in the mid-infrared (24 μm) is 21%, while it gradually rises up to 57% in the submillimeter (500 μm). We find that the bulk of the luminosity comes from the spiral arm network that produces 70% of the total luminosity of the galaxy with the rest coming from the diffuse dust disk. The "cool" dust inside the disk is heated to temperatures in a narrow range between 18 K and 15 K (going from the center to the outer parts of the galaxy). © 2012 ESO. Source

Discover hidden collaborations