2,118 research outputs found

    Dye laser remote sensing of marine plankton

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    Dye laser, emitting four wavelengths sequentially in time, has been incorporated into helicopter-borne lidar flight package, for performing studies of laser-induced fluorescence of chlorophyll A in algae. Data obtained by multicolor lidar technique can provide water-resource management with rapid-access wide-area coverage of the impact of various environmental factors for any body of water

    Groups of Galaxies in the Two Micron All-Sky Redshift Survey

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    We present the results of applying a percolation algorithm to the initial release of the Two Micron All-Sky Survey Extended Source Catalog, using subsequently measured redshifts for almost all of the galaxies with K < 11.25 mag. This group catalog is based on the first near-IR all-sky flux-limited survey that is complete to |b| = 5 deg. We explore the dependence of the clustering on the length and velocity scales involved. The paper describes a group catalog, complete to a limiting redshift of 10,000 km/s, created by maximizing the number of groups containing 3 or more members. A second catalog is also presented, created by requiring a minimum density contrast of 80 to identify groups. We identify known nearby clusters in the catalogs and contrast the groups identified in the two catalogs. We examine and compare the properties of the determined groups and verify that the results are consistent with the UZC-SSRS2 and northern CfA redshift survey group catalogs. The all-sky nature of the catalog will allow the development of a flow-field model based on the density field inferred from the estimated cluster masses.Comment: Accepted for publication in ApJ (29 pages including 13 figures). A version with high-resolution figures is available at http://www.cfa.harvard.edu/~acrook/preprints

    Optically controlled spin-glasses in multi-qubit cavity systems

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    Recent advances in nanostructure fabrication and optical control, suggest that it will soon be possible to prepare collections of interacting two-level systems (i.e. qubits) within an optical cavity. Here we show theoretically that such systems could exhibit novel phase transition phenomena involving spin-glass phases. By contrast with traditional realizations using magnetic solids, these phase transition phenomena are associated with both matter and radiation subsystems. Moreover the various phase transitions should be tunable simply by varying the matter-radiation coupling strength.Comment: 4 pages, 3 figure

    Towards a Full Census of the Obscure(d) Vela Supercluster using MeerKAT

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    Recent spectroscopic observations of a few thousand partially obscured galaxies in the Vela constellation revealed a massive overdensity on supercluster scales straddling the Galactic Equator (l \sim 272.5deg) at cz18000cz \sim 18000km/s. It remained unrecognised because it is located just beyond the boundaries and volumes of systematic whole-sky redshift and peculiar velocity surveys - and is obscured by the Milky Way. The structure lies close to the apex where residual bulkflows suggest considerable mass excess. The uncovered Vela Supercluster (VSCL) conforms of a confluence of merging walls, but its core remains uncharted. At the thickest foreground dust column densities (|b| < 6 deg) galaxies are not visible and optical spectroscopy is not effective. This precludes a reliable estimate of the mass of VSCL, hence its effect on the cosmic flow field and the peculiar velocity of the Local Group. Only systematic HI-surveys can bridge that gap. We have run simulations and will present early-science observing scenarios with MeerKAT 32 (M32) to complete the census of this dynamically and cosmologically relevant supercluster. M32 has been put forward because this pilot project will also serve as precursor project for HI MeerKAT Large Survey Projects, like Fornax and Laduma. Our calculations have shown that a survey area of the fully obscured part of the supercluster, where the two walls cross and the potential core of the supercluster resides, can be achieved on reasonable time-scales (200 hrs) with M32.Comment: 10 pages, 3 figures, accepted for publication, Proceedings of Science, workshop on "MeerKAT Science: On the Pathway to the SKA", held in Stellenbosch 25-27 May 201

    A more promising architecture? Commissioners’ perspectives on the reconfiguration of personality disorder services under the Offender Personality Disorder (OPD) pathway

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    Purpose – This paper explores the views of NHS England (NHSE) and Her Majesty’s Prison and Probation Service (HMPPS) commissioners about the Offender Personality Disorder (OPD) pathway. Design/methodology/approach – Thematic analysis of four semi-structured interviews with NHSE and HMPPS commissioners. Findings – Commissioners offered a cautious but confident assessment of the potential effectiveness of the OPD pathway, drawing particular attention to its potential to enhance the confidence and competency of staff, offer better value for money and provide enhanced progression routes for offenders with personality disorders. Additionally, commissioners identified a number of potential risks for the pathway including wider system flux, funding availability, multi-agency working, offender engagement and the need to evidence effectiveness. Research limitations/implications – Our analysis is based on a small number of interviews. However, there are only a limited number of commissioners involved with the OPD pathway. Practical implications – While the stronger focus on progression in the OPD pathway is a welcome departure from a narrow focus on high security DSPD services, the foundations of the OPD pathway ultimately lie with the DSPD programme and similar challenges are likely to follow. The system within which the pathway operates is subject to a great deal of flux and this inevitably poses significant challenges for pathway services, staff and offenders, as well as for those of us charged with its evaluation. Originality/value – There has been limited empirical work with commissioners in the mental health field. Our paper offers a unique insight into the perspectives of those responsible for commissioning the OPD pathway

    Triply responsive soft matter nanoparticles based on poly[oligo(ethylene glycol) methyl ether methacrylate-block-3-phenylpropyl methacrylate] copolymers

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    The stimulus-responsive properties of soft matter nanoparticles based on poly[oligo(ethylene glycol) methyl ether methacrylate-block-3-phenylpropyl methacrylate] (p(OEGMA-block-PPMA)) copolymers in methanol and ethanol are described. Methanolic synthesis, with 4-cyanopentanoic acid dithiobenzoate as the RAFT mediating agent, facilitates simple access to nanoparticles exhibiting the full range of common morphologies (spheres, worms and vesicles) simply by varying the copolymer composition (fixed average degree of polymerization (X¯n) of the pOEGMA macro-CTA for variable X¯n of the pPPMA block). Interestingly, we demonstrate that p(OEGMAx-block-PPMAy) nanoparticles are able to elicit three types of response to externally applied stimuli. These materials possess two distinct, but complementary, reversible thermal responses-one that results in an order-order transition, i.e. a morphological change, while the second is a reversible order-disorder transition based on upper critical solution temperature (UCST)-type behaviour associated with the pOEGMA coronal chains in the nanoparticles. Finally, we report the first example where specific p(OEGMA-block-PPMA) nanoparticles are shown to be sensitive to addition of an organobase-a response that is accompanied by an order-order, worm-to-sphere, morphology transition

    Detection of Powerful Mid-IR H_2 Emission in the Bridge between the Taffy Galaxies

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    We report the detection of strong, resolved emission from warm H_2 in the Taffy galaxies and bridge. Relative to the continuum and faint polyclic aromatic hydrocarbon (PAH) emission, the H_2 emission is the strongest in the connecting bridge, approaching L(H_2)/L(PAH 8 μm) = 0.1 between the two galaxies, where the purely rotational lines of H_2 dominate the mid-infrared spectrum in a way very reminiscent of the group-wide shock in the interacting group Stephan's Quintet (SQ). The surface brightness in the 0-0 S(0) and S(1) H_2 lines in the bridge is more than twice that observed at the center of the SQ shock. We observe a warm H2 mass of 4.2 × 10^8 M_☉ in the bridge, but taking into account the unobserved bridge area, the total warm mass is likely to be twice this value. We use excitation diagrams to characterize the warm molecular gas, finding an average surface mass of ~5 × 10^6 M_☉ kpc^(–2) and typical excitation temperatures of 150-175 K. H_2 emission is also seen in the galaxy disks, although there the emission is more consistent with normal star-forming galaxies. We investigate several possible heating mechanisms for the bridge gas but favor the conversion of kinetic energy from the head-on collision via turbulence and shocks as the main heating source. Since the cooling time for the warm H_2 is short (~5000 yr), shocks must be permeating the molecular gas in the bridge region in order to continue heating the H_2
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