We use 2009-2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4 degree 5 degree and up to 50 km ...50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a-1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2-42.7 Tg a-1, as compared to 24.9-27.0 Tg a-1 in the EDGAR and EPA bottom-up inventories, and 30.0-44.5 Tg a-1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern-central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29-44 % of US anthropogenic methane emissions to livestock, 22-31 % to oil/gas, 20 % to landfills/wastewater, and 11-15 % to coal. Wetlands contribute an additional 9.0-10.1 Tg a-1.
Clinical Pharmacology Unit, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
Submitted 3 June 2005
; accepted in final form 30 August 2005
The arterial pulse-wave transit ...time can be measured between the ECG R-wave and the finger pulse ( r PTT), and has been shown previously to have a linear correlation with blood pressure (BP). We hypothesized that the relationship between r PTT, preejection period (PEP; the R-wave/mechanical cardiac delay), and BP would vary with different vasoactive drugs. Twelve healthy men (mean age 22 yr) were studied. Beat-to-beat measurements were made of r PTT (using ECG and photoplethysmograph finger probe), intra-arterial radial pressure, PEP (using cardiac bioimpedance), and transit time minus PEP ( p PTT). Four drugs (glyceryl trinitrate, angiotensin II, norepinephrine, salbutamol) were administered intravenously over 15 min, with stepped dosage increase every 5 min and a 25-min saline washout between agents. All subjects in all conditions had a negative linear correlation ( R 2 = 0.39) between r PTT and systolic BP (SBP), generally constant between different drugs, apart from four subjects who had a positive r PTT/SBP correlation with salbutamol. The 95% limits of agreement between measured and r PTT-predicted SBP were ±17.0 mmHg. Beat-to-beat variability of r PTT showed better coherence with SBP variability than it did with heart rate variability ( P < 0.001). PEP accounted for a substantial and variable proportion of r PTT (1235%). Diastolic (DBP) and mean arterial BP (MAP) correlated poorly with r PTT ( R 2 = 0.02 and 0.08, respectively) but better with p PTT ( r PTT corrected for PEP, R 2 = 0.41 and 0.45, respectively). The 95% limits of agreement between measured and p PTT-predicted DBP were ± 17.3 mmHg. In conclusion, the negative correlation between r PTT and SBP is generally constant, even with marked hemodynamic perturbations. However, the relationship is not reliable enough for r PTT to be used as a surrogate marker of SBP, although it may be useful in assessing BP variability. DBP and MAP cannot be predicted from r PTT without correction for PEP. The significant contribution of PEP to r PTT means that r PTT should not be used as a marker of purely vascular function.
preejection period; pulse-wave transit time
Address for reprint requests and other correspondence: R. Payne, Clinical Pharmacology Unit, Univ. of Edinburgh, Western General Hospital, Crewe Rd., Edinburgh, EH4 2XU, UK (e-mail: r.payne{at}ed.ac.uk )
ABSTRACT
We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Galactic Plane and the large magellanic cloud (LMC). It was first detected at 888 MHz with the ...Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ∼196 arcsec. This source has phenomenological similarities to odd radio circles (ORCs). Significant differences to the known ORCs – a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size – suggest that J0624–6948 may be a different type of object. We argue that the most plausible explanation for J0624–6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment. We also examine if a massive star or a white dwarf binary ejected from either galaxy could be the supernova progenitor. Finally, we consider several other hypotheses for the nature of the object, including the jets of an active galactic nucleus (30Dor) or the remnant of a nearby stellar super-flare.
The Arabian Shield preserves a protracted magmatic record of amalgamated juvenile terranes that host a diverse range of early Neoproterozoic to Cambrian granitoids intruding volcanosedimentary basin ...assemblages that have corollaries in other parts of the East African Orogen. New zircon U–Pb geochronology of 19 granitoids intruding eight Arabian Shield terranes, define four discrete magmatic events: island arc (∼845 Ma), syncollisional (∼710 Ma), post-tectonic (∼620 Ma) and anorogenic (∼525 Ma). Zircon Lu–Hf isotopic analyses indicate that all studied granitoids are juvenile with typical εHf values of >+5 to +10 and Stenian-Tonian (∼1100–900 Ma) model ages, regardless of their precise intrusive ages or spatial relationship. Subtle changes in isotopic signatures between ∼850 and 600 Ma, suggest the result from changes in granite source materials brought about by; basaltic underplating, limited crustal interaction with Palaeoproterozoic basement and a change to lithospheric delamination/subduction roll-back processes driving juvenile ANS crustal growth.
The cycle of granite intrusion reflects accretionary cycles initiated during Mozambique Ocean closure and during Gondwana amalgamation and final assembly. Post-tectonic magmatism is divided into a ∼636–600 Ma phase and post 600 Ma event that reflects first subduction and then within-plate related processes. The identification of magmatism at ∼525 Ma is now the youngest granitoid identified so far in the Saudi Arabian Shield and may change the identified age of the regional, basal Palaeozoic unconformity. This late magmatism may be generated by the Najd Fault reactivation correlating with the Malagasy/Kunnga Orogeny that marked the final stages of Gondwana assembly.
•449 Arabian zircons define 845, 710, 620, and 525 Ma discrete magmatic events.•Dated granitoids reflect accretionary cycles following Rodinian break-up.•525 Ma plutons follow the Cambrian unconformity and mark final Gondwana assembly.•270 Hf isotopic analyses suggest juvenile (εHf >+5) basaltic underplated crust.•Juvenile model ages of 1100–900 Ma suggest connection with Mozambique Ocean closure.
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Bulk and surface sensitive x-ray spectroscopic techniques are applied in tandem to show that the valence band edge for In2O3 is found significantly closer to the bottom of the conduction band than ...expected on the basis of the widely quoted bulk band gap of 3.75 eV. First-principles theory shows that the upper valence bands of In2O3 exhibit a small dispersion and the conduction band minimum is positioned at Gamma. However, direct optical transitions give a minimal dipole intensity until 0.8 eV below the valence band maximum. The results set an upper limit on the fundamental band gap of 2.9 eV.
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The hydromagnetic structure of a neutron star accreting symmetrically at both magnetic poles is calculated as a function of accreted mass, Ma, and polar cap radius, starting from a centred magnetic ...dipole and evolving through a quasi-static sequence of two-dimensional, Grad–Shafranov equilibria. The calculation is the first to track fully the growth of high-order magnetic multipoles, due to equatorward hydromagnetic spreading, while simultaneously preserving flux-freezing and a self-consistent mass–flux distribution. Equilibria are constructed numerically by an iterative scheme and analytically by Green functions. Two key results are obtained, with implications for recycled pulsars. (i) The mass required to reduce significantly the magnetic dipole moment, 10−5 M⊙, greatly exceeds previous estimates (∼10−10 M⊙), which ignored the confining stress exerted by the compressed equatorial magnetic field. (ii) Magnetic bubbles, disconnected from the stellar surface, form in the later stages of accretion (Ma≳ 10−4 M⊙).
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Magnetically confined mountains on accreting neutron stars are promising sources of continuous-wave gravitational radiation and are currently the targets of directed searches with long-baseline ...detectors like the Laser Interferometer Gravitational Wave Observatory (LIGO). In this paper, previous ideal-magnetohydrodynamic models of isothermal mountains are generalized to a range of physically motivated, adiabatic equations of state. It is found that the mass ellipticity ε drops substantially, from ε≈ 3 × 10−4 (isothermal) to ε≈ 9 × 10−7 (non-relativistic degenerate neutrons), 6 × 10−8 (relativistic degenerate electrons) and 1 × 10−8 (non-relativistic degenerate electrons) (assuming a magnetic field of 1012.5 G at birth). The characteristic mass M
c at which the magnetic dipole moment halves from its initial value is also modified, from M
c/M⊙≈ 5 × 10−4 (isothermal) to M
c/M⊙≈ 2 × 10−6, 1 × 10−7, and 3 × 10−8 for the above three equations of state, respectively. Similar results are obtained for a realistic, piecewise-polytropic nuclear equation of state. The adiabatic models are consistent with current LIGO upper limits, unlike the isothermal models. Updated estimates of gravitational-wave detectability are made. Monte Carlo simulations of the spin distribution of accreting millisecond pulsars including gravitational-wave stalling agree better with observations for certain adiabatic equations of state, implying that X-ray spin measurements can probe the equation of state when coupled with magnetic mountain models.
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