6,601 research outputs found

    Study of electrolytic dissociation of CO2-H2O USING a solid oxide electrolyte

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    Electrolytic dissociation of carbon dioxide-water using solid oxide electrolyt

    Development of a CO2-H2O solid oxide electrolysis system Annual report, 1 Apr. - 31 Dec. 1970

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    Performance tests of CO2-H2O solid oxide electrolyte electrolysis system for generation of oxygen for life support system

    Optics in the Schwarzschild space-time

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    Realistic modelling of radiation transfer in and from variable accretion disks around black holes requires the solution of the problem: find the constants of motion and equation of motion of a light-like geodesic connecting two arbitrary points in space. Here we give the complete solution of this problem in the Schwarzschild space-time.Comment: 14 pages, 10 figures, type C orbits added, analytic solutions for time of flight of photons for all 3 types of orbits adde

    Three Trustees of School of Living Express Their Views on Old Mill

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    The Power of General Relativity

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    We study the cosmological and weak-field properties of theories of gravity derived by extending general relativity by means of a Lagrangian proportional to R1+δR^{1+\delta}. This scale-free extension reduces to general relativity when δ0\delta \to 0. In order to constrain generalisations of general relativity of this power class we analyse the behaviour of the perfect-fluid Friedmann universes and isolate the physically relevant models of zero curvature. A stable matter-dominated period of evolution requires δ>0\delta >0 or δ<1/4\delta <-1/4. The stable attractors of the evolution are found. By considering the synthesis of light elements (helium-4, deuterium and lithium-7) we obtain the bound 0.017<δ<0.0012.-0.017<\delta <0.0012. We evaluate the effect on the power spectrum of clustering via the shift in the epoch of matter-radiation equality. The horizon size at matter--radiation equality will be shifted by 1\sim 1% for a value of δ0.0005.\delta \sim 0.0005. We study the stable extensions of the Schwarzschild solution in these theories and calculate the timelike and null geodesics. No significant bounds arise from null geodesic effects but the perihelion precession observations lead to the strong bound δ=2.7±4.5×1019\delta =2.7\pm 4.5\times 10^{-19} assuming that Mercury follows a timelike geodesic. The combination of these observational constraints leads to the overall bound 0δ<7.2×10190\leq \delta <7.2\times 10^{-19} on theories of this type.Comment: 26 pages and 5 figures. Published versio

    Long term outcomes of simple clinical risk stratification in management of differentiated thyroid cancer

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    WL Craig was supported by a Cameron Research Fellowship, NHS Grampian. The University of Aberdeen Health Services Research Unit is supported by a core grant from the Chief Scientist Office of the Scottish Government Health and Social Care Directorate. There are no declared conflicts of interest.Peer reviewedPostprin

    Ultracool Spectroscopic Outliers in Gaia DR3

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    © The Author(s) 2023. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).Gaia DR3 provided a first release of RP spectra and astrophysical parameters for ultracool dwarfs. We used these Gaia RP spectra and astrophysical parameters to select the most outlying ultracool dwarfs. These objects have spectral types of M7 or later and might be young brown dwarfs or low metallicity objects. This work aimed to find ultracool dwarfs which have Gaia RP spectra significantly different to the typical population. However, the intrinsic faintness of these ultracool dwarfs in Gaia means that their spectra were typically rather low signal-to-noise in Gaia DR3. This study is intended as a proof-of-concept for future iterations of the Gaia data releases. Based on well studied subdwarfs and young objects, we created a spectral type-specific color ratio, defined using Gaia RP spectra; this ratio is then used to determine which objects are outliers. We then used the objects kinematics and photometry external to Gaia to cut down the list of outliers into a list of 'prime candidates'. We produce a list of 58 Gaia RP spectra outliers, seven of which we deem as prime candidates. Of these, six are likely subdwarfs and one is a known young stellar object. Four of six subdwarf candidates were known as subdwarfs already. The two other subdwarf candidates: 2MASS J03405673+2633447 (sdM8.5) and 2MASS J01204397+6623543 (sdM9), are new classifications.Peer reviewe

    The heats of formation of the haloacetylenes XCCY [X, Y = H, F, Cl]: basis set limit ab initio results and thermochemical analysis

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    The heats of formation of haloacetylenes are evaluated using the recent W1 and W2 ab initio computational thermochemistry methods. These calculations involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh quality, extrapolations to the one-particle basis set limit, and contributions of inner-shell correlation, scalar relativistic effects, and (where relevant) first-order spin-orbit coupling. The heats of formation determined using W2 theory are: \hof(HCCH) = 54.48 kcal/mol, \hof(HCCF) = 25.15 kcal/mol, \hof(FCCF) = 1.38 kcal/mol, \hof(HCCCl) = 54.83 kcal/mol, \hof(ClCCCl) = 56.21 kcal/mol, and \hof(FCCCl) = 28.47 kcal/mol. Enthalpies of hydrogenation and destabilization energies relative to acetylene were obtained at the W1 level of theory. So doing we find the following destabilization order for acetylenes: FCCF >> ClCCF >> HCCF >> ClCCCl >> HCCCl >> HCCH. By a combination of W1 theory and isodesmic reactions, we show that the generally accepted heat of formation of 1,2-dichloroethane should be revised to -31.8±\pm0.6 kcal/mol, in excellent agreement with a very recent critically evaluated review. The performance of compound thermochemistry schemes such as G2, G3, G3X and CBS-QB3 theories has been analyzed.Comment: Mol. Phys., in press (E. R. Davidson issue
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