214 research outputs found

    Geology and Geomorphology of Jenolan Caves and the Surrounding Region

    Get PDF
    Detailed mapping by university students and staff since the 1980s has significantly elucidated previously poorly known stratigraphic and structural relationships in the Jenolan Caves region. Apart from andesite of ?Ordovician age, rocks west of the caves probably correlate with the lower Silurian Campbells Group. That succession is faulted against the Silurian (mid Wenlockian) Jenolan Caves Limestone, in which caves developed during several episodes from the late Palaeozoic. Immediately east of Jenolan Caves, siliciclastic sedimentary and volcaniclastic rocks with interbedded silicic lavas constitute the newly defined Inspiration Point Formation, correlated with the upper Silurian to Lower Devonian Mount Fairy Group. Several prominent marker units are recognised, including limestone previously correlated with the main Jenolan limestone belt. Extensive strike-slip and thrust faulting disrupts the sequence, but in general the entire Silurian succession youngs to the east, so that beds apparently steeply-dipping westerly are actually overturned. Further east, Upper Devonian Lambie Group siliciclastics unconformably overlie the Inspiration Point Formation and both are overlain unconformably by lower Permian conglomeratic facies. Carboniferous intrusions include the Hellgate Granite with associated felsite dykes. The regional geomorphology probably evolved from late Carboniferous–early Permian time, with ‘steps’ in the deep valleys indicating episodic periods of valley formation, possibly including Permian glaciation

    Comprehensive Geriatric Assessment on an Acute Medical Unit: a Qualitative Study of Older People’s and Informal Carer’s Perspectives of the Care and Treatment Received

    Get PDF
    Objective: This qualitative study was imbedded in a randomized controlled trial evaluating the addition of geriatricians to usual care to enable the comprehensive geriatric assessment process with older patients on acute medical units. The qualitative study explored the perspectives of intervention participants on their care and treatment.Design: A constructivist study incorporating semi-structured interviews that were conducted in patients’ homes within six weeks of discharge from the acute medical unit. These interviews were recorded, transcribed, and analysed using thematic analysis.Setting: An acute medical unit in the United Kingdom.Participants: Older patients (n = 18) and their informal carers (n = 6) discharged directly home from an acute medical unit, who had been in the intervention group of the randomized controlled trial.Results: Three core themes were constructed: (1) perceived lack of treatment on the acute medical unit; (2) nebulous grasp of the role of the geriatrician; and (3) on-going health and activities of daily living needs postdischarge. These needs impacted upon the informal carers, who either took over, or helped the patients to complete their activities of daily living. Despite the help received with activities of daily living, a lot of the patients voiced a desire to complete these activities themselves.Conclusions:The participants perceived they were just monitored and observed on the acute medical unit, rather than receiving active treatment, and spoke of on-going unresolved health and activity of daily living needs following discharge, despite receiving the additional intervention of a geriatrician

    Stringent Constraints on Cosmological Neutrino-Antineutrino Asymmetries from Synchronized Flavor Transformation

    Full text link
    We assess a mechanism which can transform neutrino-antineutrino asymmetries between flavors in the early universe, and confirm that such transformation is unavoidable in the near bi-maximal framework emerging for the neutrino mixing matrix. We show that the process is a standard Mikheyev-Smirnov-Wolfenstein flavor transformation dictated by a synchronization of momentum states. We also show that flavor ``equilibration'' is a special feature of maximal mixing, and carefully examine new constraints placed on neutrino asymmetries. In particular, the big bang nucleosynthesis limit on electron neutrino degeneracy xi_e < 0.04 does not apply directly to all flavors, yet confirmation of the large-mixing-angle solution to the solar neutrino problem will eliminate the possibility of degenerate big bang nucleosynthesis.Comment: 11 pages, 6 figures; minor changes to match PRD versio

    Orbit structure and (reversing) symmetries of toral endomorphisms on rational lattices

    Get PDF
    We study various aspects of the dynamics induced by integer matrices on the invariant rational lattices of the torus in dimension 2 and greater. Firstly, we investigate the orbit structure when the toral endomorphism is not invertible on the lattice, characterising the pretails of eventually periodic orbits. Next we study the nature of the symmetries and reversing symmetries of toral automorphisms on a given lattice, which has particular relevance to (quantum) cat maps.Comment: 29 pages, 3 figure

    Direct Measurements of Unimolecular and Bimolecular Reaction Kinetics of the Criegee Intermediate (CH 3 ) 2 COO

    Get PDF
    The Criegee intermediate acetone oxide, (CH3)2COO, is formed by laser photolysis of 2,2-diiodopropane in the presence of O2 and characterized by synchrotron photoionization mass spectrometry and by cavity ring-down ultraviolet absorption spectroscopy. The rate coefficient of the reaction of the Criegee intermediate with SO2 was measured using photoionization mass spectrometry and pseudo-first-order methods to be (7.3 ± 0.5) × 10–11 cm3 s–1 at 298 K and 4 Torr and (1.5 ± 0.5) × 10–10 cm3 s–1 at 298 K and 10 Torr (He buffer). These values are similar to directly measured rate coefficients of anti-CH3CHOO with SO2, and in good agreement with recent UV absorption measurements. The measurement of this reaction at 293 K and slightly higher pressures (between 10 and 100 Torr) in N2 from cavity ring-down decay of the ultraviolet absorption of (CH3)2COO yielded even larger rate coefficients, in the range (1.84 ± 0.12) × 10–10 to (2.29 ± 0.08) × 10–10 cm3 s–1. Photoionization mass spectrometry measurements with deuterated acetone oxide at 4 Torr show an inverse deuterium kinetic isotope effect, kH/kD = (0.53 ± 0.06), for reactions with SO2, which may be consistent with recent suggestions that the formation of an association complex affects the rate coefficient. The reaction of (CD3)2COO with NO2 has a rate coefficient at 298 K and 4 Torr of (2.1 ± 0.5) × 10–12 cm3 s–1 (measured with photoionization mass spectrometry), again similar to rate for the reaction of anti-CH3CHOO with NO2. Cavity ring-down measurements of the acetone oxide removal without added reagents display a combination of first- and second-order decay kinetics, which can be deconvolved to derive values for both the self-reaction of (CH3)2COO and its unimolecular thermal decay. The inferred unimolecular decay rate coefficient at 293 K, (305 ± 70) s–1, is similar to determinations from ozonolysis. The present measurements confirm the large rate coefficient for reaction of (CH3)2COO with SO2 and the small rate coefficient for its reaction with water. Product measurements of the reactions of (CH3)2COO with NO2 and with SO2 suggest that these reactions may facilitate isomerization to 2-hydroperoxypropene, possibly by subsequent reactions of association products

    The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs

    Full text link
    The Coma cluster was the target of a HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in 2007, the partially completed survey still covers ~50% of the core high-density region in Coma. Observations were performed for 25 fields that extend over a wide range of cluster-centric radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the south-west region of the cluster. In this paper we present reprocessed images and SExtractor source catalogs for our survey fields, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SExtractor Kron magnitudes based only on the measured source flux and half-light radius. We have performed photometry for ~73,000 unique objects; one-half of our detections are brighter than the 10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight majority of objects (60%) are unresolved or only marginally resolved by ACS. We estimate that Coma members are 5-10% of all source detections, which consist of a large population of unresolved objects (primarily GCs but also UCDs) and a wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The red sequence of Coma member galaxies has a constant slope and dispersion across 9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma Treasury program was made available to the public in 2008 August. The images and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd

    Theory of Pseudomodes in Quantum Optical Processes

    Get PDF
    This paper deals with non-Markovian behaviour in atomic systems coupled to a structured reservoir of quantum EM field modes, with particular relevance to atoms interacting with the field in high Q cavities or photonic band gap materials. In cases such as the former, we show that the pseudo mode theory for single quantum reservoir excitations can be obtained by applying the Fano diagonalisation method to a system in which the atomic transitions are coupled to a discrete set of (cavity) quasimodes, which in turn are coupled to a continuum set of (external) quasimodes with slowly varying coupling constants and continuum mode density. Each pseudomode can be identified with a discrete quasimode, which gives structure to the actual reservoir of true modes via the expressions for the equivalent atom-true mode coupling constants. The quasimode theory enables cases of multiple excitation of the reservoir to now be treated via Markovian master equations for the atom-discrete quasimode system. Applications of the theory to one, two and many discrete quasimodes are made. For a simple photonic band gap model, where the reservoir structure is associated with the true mode density rather than the coupling constants, the single quantum excitation case appears to be equivalent to a case with two discrete quasimodes

    The Seventh Data Release of the Sloan Digital Sky Survey

    Get PDF
    This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11663 deg^2 of imaging data, with most of the roughly 2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry over 250 deg^2 along the Celestial Equator in the Southern Galactic Cap. A coaddition of these data goes roughly two magnitudes fainter than the main survey. The spectroscopy is now complete over a contiguous area of 7500 deg^2 in the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog (UCAC-2), reducing the rms statistical errors at the bright end to 45 milli-arcseconds per coordinate. A systematic error in bright galaxy photometr is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat-fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. (Abridged)Comment: 20 pages, 10 embedded figures. Accepted to ApJS after minor correction
    • …
    corecore