3,285 research outputs found

    An inventory and condition survey of rangelands in the Ashburton River catchment, Western Australia

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    The inventory and condition survey of rangelands in the Ashburton River catchment, undertaken by the Department of Agriculture and Food, Western Australia (DAFWA) between 1976 and 1978, describes and maps the natural resources of the region’s pastoral leasehold land. This survey report provides a baseline record of the existence and condition of the natural area’s resources, to assist with the planning and implementation of land management practices. The report identified and described the condition of soils, landforms, vegetation, habitat, ecosystems, and declared plants and animals. It also assessed the impact of pastoralism and made land management recommendations. The area surveyed covers approximately 93 600km² and includes the catchment of the Ashburton River and part of the catchment of the Yannarie River. About 65% (61 130km²) of the area is occupied by 30 pastoral leases. The remaining 35% (32 470km²) consists of reserves of various kinds, and vacant crown land which is unsuitable for pastoral purposes. The worst areas of degredation and erosion are on the most valuable pasture lands. These areas are readily accessible, close to permanent water supplies and support attractive pastures. Therefore, they received preferential overuse in the early days of settlement, and sensitive parts are now seriously degraded

    Systematics of Moduli Stabilization, Inflationary Dynamics and Power Spectrum

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    We study the scalar sector of type IIB superstring theory compactified on Calabi-Yau orientifolds as a place to find a mechanism of inflation in the early universe. In the large volume limit, one can stabilize the moduli in stages using perturbative method. We relate the systematics of moduli stabilization with methods to reduce the number of possible inflatons, which in turn lead to a simpler inflation analysis. Calculating the order-of-magnitude of terms in the equation of motion, we show that the methods are in fact valid. We then give the examples where these methods are used in the literature. We also show that there are effects of non-inflaton scalar fields on the scalar power spectrum. For one of the two methods, these effects can be observed with the current precision in experiments, while for the other method, the effects might never be observable.Comment: 20 pages, JHEP style; v.2 and v.3: typos fixed, discussion and references adde

    A Search for a Sub-Earth Sized Companion to GJ 436 and a Novel Method to Calibrate Warm Spitzer IRAC Observations

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    We discovered evidence for a possible additional 0.75 R_Earth transiting planet in the NASA EPOXI observations of the known M dwarf exoplanetary system GJ 436. Based on an ephemeris determined from the EPOXI data, we predicted a transit event in an extant Spitzer Space Telescope 8 micron data set of this star. Our subsequent analysis of those Spitzer data confirmed the signal of the predicted depth and at the predicted time, but we found that the transit depth was dependent on the aperture used to perform the photometry. Based on these suggestive findings, we gathered new Warm Spitzer Observations of GJ 436 at 4.5 microns spanning a time of transit predicted from the EPOXI and Spitzer 8 micron candidate events. The 4.5 micron data permit us to rule out a transit at high confidence, and we conclude that the earlier candidate transit signals resulted from correlated noise in the EPOXI and Spitzer 8 micron observations. In the course of this investigation, we developed a novel method for correcting the intrapixel sensitivity variations of the 3.6 and 4.5 micron channels of the Infrared Array Camera (IRAC) instrument. We demonstrate the sensitivity of Warm Spitzer observations of M dwarfs to confirm sub-Earth sized planets. Our analysis will inform similar work that will be undertaken to use Warm Spitzer observations to confirm rocky planets discovered by the Kepler mission.Comment: 22 pages, 8 figures, accepted for publication in PAS

    Increase in Caesarean Deliveries after the Australian Private Health Insurance Incentive Policy Reforms

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    AbstractBackground: The Australian Private Health Insurance Incentive (PHII) policy reforms implemented in 1997–2000 increased PHI membership in Australia by 50%. Given the higher rate of obstetric interventions in privately insured patients, the reforms may have led to an increase in surgical deliveries and deliveries with longer hospital stays. We aimed to investigate the effect of the PHII policy introduction on birth characteristics in Western Australia (WA).Methods and Findings: All 230,276 birth admissions from January 1995 to March 2004 were identified from administrative birth and hospital data-systems held by the WA Department of Health. Average quarterly birth rates after the PHII introduction were estimated and compared with expected rates had the reforms not occurred. Rate and percentage differences (including 95% confidence intervals) were estimated separately for public and private patients, by mode of delivery, and by length of stay in hospital following birth. The PHII policy introduction was associated with a 20% (221.4 to219.3) decrease in public birth rates, a 51% (45.1 to 56.4) increase in private birth rates, a 5% (25.3 to 25.1) and 8% (28.9 to 27.9) decrease in unassisted and assisted vaginal deliveries respectively, a 5% (25.3 to 25.1) increase in caesarean sections with labour and 10% (8.0 to 11.7) increase in caesarean sections without labour. Similarly, birth rates where the infant stayed 0–3 days in hospital following birth decreased by 20% (221.5 to 218.5), but rates of births with .3 days inhospital increased by 15% (12.2 to 17.1).Conclusions: Following the PHII policy implementation in Australia, births in privately insured patients, caesarean deliveries and births with longer infant hospital stays increased. The reforms may not have been beneficial for quality obstetric care in Australia or the burden of Australian hospitals

    Constraints in the Context of Induced-gravity Inflation

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    Constraints on the required flatness of the scalar potential V(ϕ)V(\phi) for a cousin-model to extended inflation are studied. It is shown that, unlike earlier results, Induced-gravity Inflation can lead to successful inflation with a very simple lagrangian and λ∼10−6\lambda \sim 10^{-6}, rather than 10−1510^{-15} as previously reported. A second order phase transition further enables this model to escape the \lq big bubble' problem of extended inflation, while retaining the latter's motivations based on the low-energy effective lagrangians of supergravity, superstring, and Kaluza-Klein theories.Comment: 19 pp; 3 figures (not included -- available from author). Plain LaTeX. In press in Physical Review

    Solar District Cup Competition

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    The Solar District Cup is a two-semester design competition sponsored by the U.S. Dept. of Energy in which teams from across the nation compete to design the most efficient and cost effective solar plus storage system for a unique district case. The Embry Riddle team was tasked with designing such a system for New Mexico State University in Las Cruses, NM

    On the Decoherence of Primordial Fluctuations During Inflation

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    We study the process whereby quantum cosmological perturbations become classical within inflationary cosmology. By setting up a master-equation formulation we show how quantum coherence for super-Hubble modes can be destroyed by their coupling to the environment provided by sub-Hubble modes. We identify what features the sub-Hubble environment must have in order to decohere the longer wavelengths, and identify how the onset of decoherence (and how long it takes) depends on the properties of the sub-Hubble physics which forms the environment. Our results show that the decoherence process is largely insensitive to the details of the coupling between the sub- and super-Hubble scales. They also show how locality implies, quite generally, that the decohered density matrix at late times is diagonal in the field representation (as is implicitly assumed by extant calculations of inflationary density perturbations). Our calculations also imply that decoherence can arise even for couplings which are as weak as gravitational in strength.Comment: 31 pages, 1 figur

    Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC

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    We report the detection of transit timing variations (TTVs) well in excess of one hour in the Kepler multi-planet candidate system KOI 806. This system exhibits transits consistent with three separate planets -- a Super-Earth, a Jupiter, and a Saturn -- lying very nearly in a 1:2:5 resonance, respectively. We used the Kepler public data archive and observations with the Gran Telescopio de Canarias to compile the necessary photometry. For the largest candidate planet (KOI 806.02) in this system, we detected a large transit timing variation of -103.5±\pm6.9 minutes against previously published ephemeris. We did not obtain a strong detection of a transit color signature consistent with a planet-sized object; however, we did not detect a color difference in transit depth, either. The large TTV is consistent with theoretical predictions that exoplanets in resonance can produce large transit timing variations, particularly if the orbits are eccentric. The presence of large TTVs among the bodies in this systems indicates that KOI806 is very likely to be a planetary system. This is supported by the lack of a strong color dependence in the transit depth, which would suggest a blended eclipsing binary.Comment: 9 pages, 4 figures, accepted into A&A Letter

    The architecture of the hierarchical triple star KOI 928 from eclipse timing variations seen in Kepler photometry

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    We present a hierarchical triple star system (KIC 9140402) where a low mass eclipsing binary orbits a more massive third star. The orbital period of the binary (4.98829 Days) is determined by the eclipse times seen in photometry from NASA's Kepler spacecraft. The periodically changing tidal field, due to the eccentric orbit of the binary about the tertiary, causes a change in the orbital period of the binary. The resulting eclipse timing variations provide insight into the dynamics and architecture of this system and allow the inference of the total mass of the binary (0.424±0.017M⊙0.424 \pm 0.017 \text{M}_\odot) and the orbital parameters of the binary about the central star.Comment: Submitted to MNRAS Letters. Additional tables with eclipse times are included here. The Kepler data that was used for the analysis of this system (Q1 through Q6) will be available on MAST after June 27, 201
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