2,550 research outputs found

    Should we mine the deep seafloor?

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    As land-based mineral resources become increasingly difficult and expensive to acquire, the potential for mining resources from the deep seafloor has become widely discussed and debated. Exploration leases are being granted, and technologies are under development. However, the quantity and quality of the resources are uncertain, and many worry about risks to vulnerable deep-sea ecosystems. Deep-sea mining has become part of the discussion of the United Nations Sustainable Development Goals. In this article we provide a summary of benefits, costs, and uncertainties that surround this potentially attractive but contentious topic

    Re-examination of the possible tidal stream in front of the LMC

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    It has recently been suggested that the stars in a vertical extension of the red clump feature seen in LMC color-magnitude diagrams could belong to a tidal stream of material located in front of that galaxy. If this claim is correct, this foreground concentration of stars could contribute significantly to the rate of gravitational microlensing events observed in the LMC microlensing experiments. Here we present radial velocity measurements of stars in this so-called ``vertical red clump'' (VRC) population. The observed stellar sample, it transpires, has typical LMC kinematics. It is shown that it is improbable that an intervening tidal stream should have the same distribution of radial velocities as the LMC, which is consistent with an earlier study that showed that the VRC feature is more likely a young stellar population in the main body of that galaxy. However, the kinematic data do not discriminate against the possibility that the VRC is an LMC halo population.Comment: 10 pages, 3 figures, 1 table. Accepted for publication in ApJ

    MOA-2011-BLG-293Lb: First Microlensing Planet possibly in the Habitable Zone

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    We used Keck adaptive optics observations to identify the first planet discovered by microlensing to lie in or near the habitable zone, i.e., at projected separation r⊄=1.1±0.1 r_\perp=1.1\pm 0.1\,AU from its ML=0.86±0.06 M⊙M_{L}=0.86\pm 0.06\,M_\odot host, being the highest microlensing mass definitely identified. The planet has a mass mp=4.8±0.3 MJupm_p = 4.8\pm 0.3\,M_{\rm Jup}, and could in principle have habitable moons. This is also the first planet to be identified as being in the Galactic bulge with good confidence: DL=7.72±0.44D_L=7.72\pm 0.44 kpc. The planet/host masses and distance were previously not known, but only estimated using Bayesian priors based on a Galactic model (Yee et al. 2012). These estimates had suggested that the planet might be a super-Jupiter orbiting an M dwarf, a very rare class of planets. We obtained high-resolution JHKJHK images using Keck adaptive optics to detect the lens and so test this hypothesis. We clearly detect light from a G dwarf at the position of the event, and exclude all interpretations other than that this is the lens with high confidence (95%), using a new astrometric technique. The calibrated magnitude of the planet host star is HL=19.16±0.13H_{L}=19.16\pm 0.13. We infer the following probabilities for the three possible orbital configurations of the gas giant planet: 53% to be in the habitable zone, 35% to be near the habitable zone, and 12% to be beyond the snow line, depending on the atmospherical conditions and the uncertainties on the semimajor axis.Comment: Accepted by ApJ, 21 pages, 4 figure

    Impact of Level of Effort on the Effects of Compliance with the 3-Hour Rule

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    Objective To determine if patients’ level of effort (LOE) in therapy sessions during traumatic brain injury (TBI) rehabilitation modifies the effect of compliance with the 3-Hour Rule of the Centers for Medicare & Medicaid Services. Design Propensity score methodology applied to the TBI-Practice-Based Evidence (TBI-PBE) database, consisting of multi-site, prospective, longitudinal observational data. Setting Acute inpatient rehabilitation facilities (IRF). Participants Patients (n=1820) who received their first IRF admission for TBI in the US and were enrolled for 3 and 9 month follow-up. Main Outcome Measures Participation Assessment with Recombined Tools-Objective-17, FIMTM Motor and Cognitive scores, Satisfaction with Life Scale, and Patient Health Questionnaire-9. Results When the full cohort was examined, no strong main effect of compliance with the 3-Hour Rule was identified and LOE did not modify the effect of compliance with the 3-Hour Rule. In contrast, LOE had a strong positive main effect on all outcomes, except depression. When the sample was stratified by level of disability, LOE modified the effect of compliance, particularly on the outcomes of participants with less severe disability. For these patients, providing 3 hours of therapy for 50%+ of therapy days in the context of low effort resulted in poorer performance on select outcome measures at discharge and up to 9 months post discharge compared to patients with <50% of 3-hr therapy days. Conclusions LOE is an active ingredient in inpatient TBI rehabilitation, while compliance with the 3-Hour Rule was not found to have a substantive impact on the outcomes. The results support matching time in therapy during acute TBI rehabilitation to patients’ LOE in order to optimize long-term benefits on outcomes

    FMR studies of exchange-coupled multiferroic polycrystalline Pt/BiFeO3_3/Ni81_{81}Fe19_{19}/Pt heterostructures

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    An experimental study of the in-plane azimuthal behaviour and frequency dependence of the ferromagnetic resonance field and the resonance linewidth as a function of BiFeO3_3 thickness is carried out in a polycrystalline exchange-biased BiFeO3_3/Ni81_{81}Fe19_{19} system. The magnetization decrease of the Pt/BiFeO3_3/Ni81_{81}Fe19_{19}/Pt heterostructures with BiFeO3_3 thickness deduced from static measurements has been confirmed by dynamic investigations. Ferromagnetic resonance measurements have shown lower gyromagnetic ratio in a perpendicular geometry compared with that of a parallel geometry. The monotonous decrease of gyromagnetic ratio in a perpendicular geometry as a function of the BiFeO3_3 film thickness seems to be related to the spin-orbit interactions due to the neighbouring Pt film at its interface with Ni81_{81}Fe19_{19} film. The in-plane azimuthal shape of the total linewidth of the uniform mode shows isotropic behaviour that increases with BiFeO3_3 thickness. The study of the frequency dependence of the resonance linewidth in a broad band of 3 to 35 GHz has allowed the determination of intrinsic and extrinsic contributions to the relaxation as function of BiFeO3_3 thickness in perpendicular geometries. In our system the magnetic relaxation is dominated by the spin-pumping mechanism due to the presence of Pt. The insertion of BiFeO3_3 between Pt and Ni81_{81}Fe19_{19} attenuates the spin-pumping damping at one interface.Comment: paper accepted for publication in the Journal of Physics D: Applied Physic

    Signals for a Transition from Surface to Bulk Emission in Thermal Multifragmentation

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    Excitation-energy-gated two-fragment correlation functions have been studied between 2 to 9A MeV of excitation energy for equilibrium-like sources formed in π−\pi^- and p + 197^{197}Au reactions at beam momenta of 8,9.2 and 10.2 GeV/c. Comparison of the data to an N-body Coulomb-trajectory code shows a decrease of one order of magnitude in the fragment emission time in the excitation energy interval 2-5A MeV, followed by a nearly constant breakup time at higher excitation energy. The observed decrease in emission time is shown to be strongly correlated with the increase of the fragment emission probability, and the onset of thermally-induced radial expansion. This result is interpreted as evidence consistent with a transition from surface-dominated to bulk emission expected for spinodal decomposition.Comment: 11 pages including 3 postscript figures (1 color

    Thermally-induced expansion in the 8 GeV/c π−\pi^- + 197^{197}Au reaction

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    Fragment kinetic energy spectra for reactions induced by 8.0 GeV/c π−\rm{\pi^-} beams incident on a 197\rm{^{197}}Au target have been analyzed in order to deduce the possible existence and influence of thermal expansion. The average fragment kinetic energies are observed to increase systematically with fragment charge but are nearly independent of excitation energy. Comparison of the data with statistical multifragmentation models indicates the onset of extra collective thermal expansion near an excitation energy of E*/A ≈\rm{\approx} 5 MeV. However, this effect is weak relative to the radial expansion observed in heavy-ion-induced reactions, consistent with the interpretation that the latter expansion may be driven primarily by dynamical effects such as compression/decompression.Comment: 12 pages including 4 postscript figure

    Effect of interleukin-6 receptor blockade on surrogates of vascular risk in rheumatoid arthritis: MEASURE, a randomised, placebo-controlled study

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    Objectives The interleukin-6 receptor (IL-6R) blocker tocilizumab (TCZ) reduces inflammatory disease activity in rheumatoid arthritis (RA) but elevates lipid concentrations in some patients. We aimed to characterise the impact of IL-6R inhibition on established and novel risk factors in active RA. Methods Randomised, multicentre, two-part, phase III trial (24-week double-blind, 80-week open-label), MEASURE, evaluated lipid and lipoprotein levels, high-density lipoprotein (HDL) particle composition, markers of coagulation, thrombosis and vascular function by pulse wave velocity (PWV) in 132 patients with RA who received TCZ or placebo. Results Median total-cholesterol, low-density lipoprotein-cholesterol (LDL-C) and triglyceride levels increased in TCZ versus placebo recipients by week 12 (12.6% vs 1.7%, 28.1% vs 2.2%, 10.6% vs −1.9%, respectively; all p&#60;0.01). There were no significant differences in mean small LDL, mean oxidised LDL or total HDL-C concentrations. However, HDL-associated serum amyloid A content decreased in TCZ recipients. TCZ also induced reductions (&#60;30%) in secretory phospholipase A2-IIA, lipoprotein(a), fibrinogen and D-dimers and elevation of paraoxonase (all p&#60;0.0001 vs placebo). The ApoB/ApoA1 ratio remained stable over time in both groups. PWV decreases were greater with placebo than TCZ at 12 weeks (adjusted mean difference 0.79 m/s (95% CI 0.22 to 1.35; p=0.0067)). Conclusions These data provide the first detailed evidence for the modulation of lipoprotein particles and other surrogates of vascular risk with IL-6R inhibition. When compared with placebo, TCZ induced elevations in LDL-C but altered HDL particles towards an anti-inflammatory composition and favourably modified most, but not all, measured vascular risk surrogates. The net effect of such changes for cardiovascular risk requires determination.</p
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