2,826 research outputs found

    Behavioral ontogeny in larvae and early juveniles of the giant trevally (Caranx ignobilis) (Pisces: Carangidae)

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    Behavior of young (8−18 mm SL) giant trevally (Caranx ignobilis), a large coral-reef−associated predator, was observed in the laboratory and the ocean. Size was a better predictor of swimming speed and endurance than was age. Critical speed increased with size from 12 to 40 cm/s at 2.7 cm/s for each mm increase in size. Mean scaled critical speed was 19 body lengths/s and was not size related. Swimming speed in the ocean was 4 to 20 cm/s (about half of critical speed) and varied among areas, but within each area, it increased at 2 cm/s for each mm increase in size. Swimming endurance in the laboratory increased from 5 to 40 km at 5 km for each mm increase in size. Vertical distribution changed ontogenetically: larvae swam shallower, but more variably, and then deeper with growth. Two-thirds of individuals swam directionally with no ontogenetic increase in orientation precision. Larvae swam offshore off open coasts, but not in a bay. In situ observations of C. ignobilis feeding, interacting with pelagic animals, and reacting to reefs are reported. Manus

    Effects of Hydrogen on the Phases and Transition Temperatures of NiTi

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    Austenitic (B2) NiTi samples were cathodically charged with various amounts of hydrogen. Trends are tracked based on temperature, time and voltage throughout the process to establish consistent and predictive hydrogen charging procedures. The effect of hydrogen on the austenitic structure and the formation of hydrides are studied with x-ray diffraction (XRD). An increase in the austenite lattice parameter with increased hydrogen content is observed up to a hydrogen solubility limit of approximately 85 wppm. At greater hydrogen concentrations, additional XRD peaks appear, suggesting possible hydride formation. Differential scanning calorimetry (DSC) results show a decrease in both the austenitic and martensitic transition temperatures with increased atomic hydrogen content and increased hydride phase. Scanning electron microscopy (SEM) is used to reveal the hydride phase. The effect of atomic hydrogen on NiTi and the structure of the hydride phase are compared with previous hydrogen studies

    ALMA Resolves 30 Doradus: Sub-parsec Molecular Cloud Structure Near the Closest Super-Star Cluster

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    We present ALMA observations of 30 Doradus -- the highest resolution view of molecular gas in an extragalactic star formation region to date (~0.4pc x 0.6pc). The 30Dor-10 cloud north of R136 was mapped in 12CO 2-1, 13CO 2-1, C18O 2-1, 1.3mm continuum, the H30alpha recombination line, and two H2CO 3-2 transitions. Most 12CO emission is associated with small filaments and clumps (<1pc, ~1000 Msun at the current resolution). Some clumps are associated with protostars, including "pillars of creation" photoablated by intense radiation from R136. Emission from molecular clouds is often analyzed by decomposition into approximately beam-sized clumps. Such clumps in 30 Doradus follow similar trends in size, linewidth, and surface density to Milky Way clumps. The 30 Doradus clumps have somewhat larger linewidths for a given size than predicted by Larson's scaling relation, consistent with pressure confinement. They extend to higher surface density at a given size and linewidth compared to clouds studied at 10pc resolution. These trends are also true of clumps in Galactic infrared-dark clouds; higher resolution observations of both environments are required. Consistency of clump masses calculated from dust continuum, CO, and the virial theorem reveals that the CO abundance in 30 Doradus clumps is not significantly different from the LMC mean, but the dust abundance may be reduced by ~2. There are no strong trends in clump properties with distance from R136; dense clumps are not strongly affected by the external radiation field, but there is a modest trend towards lower dense clump filling fraction deeper in the cloud.Comment: accepted to Ap

    The uses and gratifications of using Facebook music listening applications

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    Despite rapid adoption of social media as a means of music listening, little is known about users’ motivations. This study applies the uses and gratifications approach to users’ motivations for using music listening applications on Facebook. Participants completed an online survey, and 153 out of 576 respondents indicated that they used a Facebook music listening application. A principal axis factor analysis identified three different motivations for this usage, namely entertainment, communication, and habitual diversion gratifications. The entertainment and communication gratifications replicate those found in prior uses and gratifications research concerning other social networking features, illustrating the strong similarity between uses of music and social media. However, the habitual diversion gratification may serve to distinguish listening applications from other features. Identifying and explaining these factors is relevant to social media users, musicians and application designers, as they explain what motivates a means of music listening that is gaining prominence

    Ligand-clustered “patchy” nanoparticles for modulated cellular uptake and in vivo tumor targeting

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    Author Manuscript: 2012 August 05.A matter of presentation: The manner in which polyvalent ligands are presented to a cell—homogeneously or in spatially defined groupings on a nanoparticle surface—may play an important role in cellular uptake. This aspect is investigated for the first time using a linear dendritic polymer construct to pattern the surfaces of nanoparticles with variable-sized ligand clusters in different spatial arrangements.National Institutes of Health (U.S.) (NIH NIBIB Grant 5R01EB008082-02)MIT-Harvard Center of Cancer Nanotechnology ExcellenceNational Science Foundation (U.S.
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