4,471 research outputs found
The case for a Torres Strait Islanderâdriven, longâterm research agenda for environment, health and wellbeing
[Extract] Researchers and communities are seeking strategies to manage complex challenges regarding positive health for Torres Strait Islanders â a âwicked problemâ for which there is no straightforward solution.1 Proposed models for Torres Strait Islanderâdriven research and policy analysis are not new.2 Yet a coordinated model for achieving synergy of multidisciplinary teams and stakeholders for environment, health and wellbeing has remained elusive. Partnerships between researchers and communities are typically limited by project scope and funding duration. Research capacityâbuilding efforts have focused on individual researchers. This has successfully produced a new generation of Torres Strait Islander researchers across disciplines, including Meriba buayângalpan wakaythoemamy (also known as the Torres Strait Islander Researchersâ Community of Practice or CoP). However, support for local community organisations to drive their own longâterm research agenda is found wanting. Given Torres Strait Islandersâ previous and current calls for autonomy, the community itself is best positioned to determine key priorities and to understand the context for decision making.3-5 How can Torres Strait Islander communities leverage research that properly informs decisionâmaking and action towards positive health and wellbeing
Upgrade of the protection system for superconducting circuits in the LHC
Prior to the re-start of the Large Hadron Collider LHC in 2009 the protection system for superconducting magnets and bus-bars QPS will be substantially upgraded. The foreseen modifications will enhance the capability of the system in detecting problems related to the electrical interconnections between superconducting magnets as well as the detection of so-called aperture symmetric quenches in the LHC main magnets
RELICS: The Reionization Lensing Cluster Survey and the Brightest High-z Galaxies
Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the z ~ 6-8 candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of â200 arcminÂČ. These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z ~ 6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z ~ 6 candidates are as bright as AB mag ~23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope
Competing Ultrafast Energy Relaxation Pathways in Photoexcited Graphene
For most optoelectronic applications of graphene a thorough understanding of
the processes that govern energy relaxation of photoexcited carriers is
essential. The ultrafast energy relaxation in graphene occurs through two
competing pathways: carrier-carrier scattering -- creating an elevated carrier
temperature -- and optical phonon emission. At present, it is not clear what
determines the dominating relaxation pathway. Here we reach a unifying picture
of the ultrafast energy relaxation by investigating the terahertz
photoconductivity, while varying the Fermi energy, photon energy, and fluence
over a wide range. We find that sufficiently low fluence ( 4
J/cm) in conjunction with sufficiently high Fermi energy (
0.1 eV) gives rise to energy relaxation that is dominated by carrier-carrier
scattering, which leads to efficient carrier heating. Upon increasing the
fluence or decreasing the Fermi energy, the carrier heating efficiency
decreases, presumably due to energy relaxation that becomes increasingly
dominated by phonon emission. Carrier heating through carrier-carrier
scattering accounts for the negative photoconductivity for doped graphene
observed at terahertz frequencies. We present a simple model that reproduces
the data for a wide range of Fermi levels and excitation energies, and allows
us to qualitatively assess how the branching ratio between the two distinct
relaxation pathways depends on excitation fluence and Fermi energy.Comment: Nano Letters 201
Photocurrent measurements of supercollision cooling in graphene
The cooling of hot electrons in graphene is the critical process underlying
the operation of exciting new graphene-based optoelectronic and plasmonic
devices, but the nature of this cooling is controversial. We extract the hot
electron cooling rate near the Fermi level by using graphene as novel
photothermal thermometer that measures the electron temperature () as it
cools dynamically. We find the photocurrent generated from graphene
junctions is well described by the energy dissipation rate , where the heat capacity is and is the
base lattice temperature. These results are in disagreement with predictions of
electron-phonon emission in a disorder-free graphene system, but in excellent
quantitative agreement with recent predictions of a disorder-enhanced
supercollision (SC) cooling mechanism. We find that the SC model provides a
complete and unified picture of energy loss near the Fermi level over the wide
range of electronic (15 to 3000 K) and lattice (10 to 295 K) temperatures
investigated.Comment: 7pages, 5 figure
Drimolen cranium DNH 155 documents microevolution in an early hominin species
Paranthropus robustus is a small-brained extinct hominin from South Africa characterized by derived, robust craniodental
morphology. The most complete known skull of this species is DNH 7 from Drimolen Main Quarry, which differs from
P. robustus specimens recovered elsewhere in ways attributed to sexual dimorphism. Here, we describe a new fossil specimen
from Drimolen Main Quarry, dated from approximately 2.04â1.95 million years ago, that challenges this view. DNH 155 is a
well-preserved adult male cranium that shares with DNH 7 a suite of primitive and derived features unlike those seen in adult
P. robustus specimens from other chronologically younger deposits. This refutes existing hypotheses linking sexual dimorphism,
ontogeny and social behaviour within this taxon, and clarifies hypotheses concerning hominin phylogeny. We document
small-scale morphological changes in P. robustus associated with ecological change within a short time frame and restricted
geography. This represents the most highly resolved evidence yet of microevolutionary change within an early hominin species
An improved measurement of muon antineutrino disappearance in MINOS
We report an improved measurement of muon anti-neutrino disappearance over a
distance of 735km using the MINOS detectors and the Fermilab Main Injector
neutrino beam in a muon anti-neutrino enhanced configuration. From a total
exposure of 2.95e20 protons on target, of which 42% have not been previously
analyzed, we make the most precise measurement of the anti-neutrino
"atmospheric" delta-m squared = 2.62 +0.31/-0.28 (stat.) +/- 0.09 (syst.) and
constrain the anti-neutrino atmospheric mixing angle >0.75 (90%CL). These
values are in agreement with those measured for muon neutrinos, removing the
tension reported previously.Comment: 5 pages, 4 figures. In submission to Phys.Rev.Let
RELICS: High-Resolution Constraints on the Inner Mass Distribution of the z=0.83 Merging Cluster RXJ0152.7-1357 from strong lensing
Strong gravitational lensing (SL) is a powerful means to map the distribution
of dark matter. In this work, we perform a SL analysis of the prominent X-ray
cluster RXJ0152.7-1357 (z=0.83, also known as CL 0152.7-1357) in \textit{Hubble
Space Telescope} images, taken in the framework of the Reionization Lensing
Cluster Survey (RELICS). On top of a previously known galaxy multiply
imaged by RXJ0152.7-1357, for which we identify an additional multiple image,
guided by a light-traces-mass approach we identify seven new sets of multiply
imaged background sources lensed by this cluster, spanning the redshift range
[1.79-3.93]. A total of 25 multiple images are seen over a small area of ~0.4
, allowing us to put relatively high-resolution constraints on the
inner matter distribution. Although modestly massive, the high degree of
substructure together with its very elongated shape make RXJ0152.7-1357 a very
efficient lens for its size. This cluster also comprises the third-largest
sample of z~6-7 candidates in the RELICS survey. Finally, we present a
comparison of our resulting mass distribution and magnification estimates with
those from a Lenstool model. These models are made publicly available through
the MAST archive.Comment: 15 Pages, 7 Figures, 4 Tables Accepted for publication in Ap
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Search for the disappearance of muon antineutrinos in the NuMI neutrino beam
We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of 136.4 ± 11.7(stat)^(+10.2)_(-8.9)(syst) events under the assumption âÎm^2â = 2.32 X 10^(-3) eV^2, sin^2(2Ξ) = 1.0
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