175 research outputs found

    The life history and ecology of the Pink-tailed Worm-lizard Aprasia parapulchella Kluge a review

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    This review synthesises research on the Pink-tailed Worm-lizard Aprasia parapukhella - a threatened species with life-history traits and habitat and dietary preferences that make it particularly vulnerable to decline. Further information on the ecology of A. parapukhella is required in order to develop effective approaches to conservation and management, particularly given the conservation status of the species. Aprasia parapukhella is a dietary specialist living in the burrows of small ants, the eggs and larvae of which it preys upon. It is late maturing (adult size probably attained in the third or fourth year of life), has a small clutch, is thought to be longlived and has specific habitat preferences. It has a strong association with landscapes that are characterised by outcroppings of lightly-embedded surface rocks.The lizard is associated with a particular suite of ant species and ground cover tending towards open native vegetation (grasses and shrubs) at most sites, but with regional differences. Although the highest densities have been recorded in areas without tree cover, the species has also been found in open-forest and woodland.The relative density of populations and the snout-vent length and weight of specimens reveal regional differences, suggesting that further analysis of the genetic status of the population across its range is warranted. There is still much to learn about the ecology of the species, in particular with respect to movement, breeding, dispersal and the relationship between lizards and ants. Further survey for new populations remains a key priority

    How well do ecosystem-based planning units represent different componenets of biodiversity?

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    There are many proposals for managing biodiversity by using surrogates, such as umbrella, indicator, focal, and flagship species. We use the term biodiversity management unit for any ecosystem-based classificatory scheme for managing biodiversity. The sufficiency of biodiversity management unit classification schemes depends upon (1) whether different biotic elements (e.g., trees, birds, reptiles) distinguish between biodiversity management units within a classification (i.e., coherence within classes}; and (2) whether different biotic elements agree upon similarities and dissimilarities among biodiversity management unit classes (i.e., conformance among classes). Recent evaluations suggest that biodiversity surrogates based on few or single taxa are not useful. Ecological vegetation classes are an ecosystem-based classification scheme used as one component for biodiversity management in Victoria, Australia. Here we evaluated the potential for ecological vegetation classes to be used as biodiversity management units in the box-ironbark ecosystem of central Victoria, Australia. Eighty sites distributed among 14 ecological vegetation classes were surveyed in the same ways for tree species, birds, mammals, reptiles, terrestrial invertebrates, and nocturnal flying insects. Habitat structure and geographic separations also were measured, which, with the biotic elements, are collectively referred to as variables. Less than half of the biotic element-ecological vegetation class pairings were coherent. Generalized Mantel tests were used to examine conformance among variables with respect to ecological vegetation classes. While most tests were not significant, birds, mammals, tree species, and habitat structure together showed significant agreement on the rating of similarities among ecological vegetation classes. In this system, use of ecological vegetation classes as biodiversity management units may account reasonably well for birds, mammals, and trees; but reptiles and invertebrates would not be accommodated. We conclude that surrogates will usually have to be augmented or developed as hierarchies to provide general representativeness

    Discovery of the Transiting Planet Kepler-5B

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    We present 44 days of high duty cycle, ultra precise photometry of the 13th magnitude star Kepler-5 (KIC 8191672, T(eff) = 6300 K, log g = 4.1), which exhibits periodic transits with a depth of 0.7%. Detailed modeling of the transit is consistent with a planetary companion with an orbital period of 3.548460 +/- 0.000032 days and a radius of 1.431(-0.052)(+0.041) R(J). Follow-up radial velocity measurements with the Keck HIRES spectrograph on nine separate nights demonstrate that the planet is more than twice as massive as Jupiter with a mass of 2.114(-0.059)(+0.056) M(J) and a mean density of 0.894 +/- 0.079 g cm(-3).NASA's Science Mission DirectorateAstronom

    Is the gravitational action additive?

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    The gravitational action is not always additive in the usual sense. We provide a general prescription for the change in action that results when different portions of the boundary of a spacetime are topologically identified. We discuss possible implications for the superposition law of quantum gravity. We present a definition of `generalized additivity' which does hold for arbitrary spacetime composition.Comment: 20 pages LaTeX file, report numbers UMD-PP 94-100 and Alberta Thy 10-9

    Kepler Observations of Transiting Hot Compact Objects

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    Kepler photometry has revealed two unusual transiting companions orbiting an early A-star and a late B-star. In both cases the occultation of the companion is deeper than the transit. The occultation and transit with follow-up optical spectroscopy reveal a 9400 K early A-star, KOI-74 (KIC 6889235), with a companion in a 5.2 day orbit with a radius of 0.08 Rsun and a 10000 K late B-star KOI-81 (KIC 8823868) that has a companion in a 24 day orbit with a radius of 0.2 Rsun. We infer a temperature of 12250 K for KOI-74b and 13500 K for KOI-81b. We present 43 days of high duty cycle, 30 minute cadence photometry, with models demonstrating the intriguing properties of these object, and speculate on their nature.Comment: 12 pages, 3 figures, submitted to ApJL (updated to correct KOI74 lightcurve

    The Spitzer c2d Survey of Weak-Line T Tauri Stars. III. The Transition from Primordial Disks to Debris Disks

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    We present 3.6 to 70 {\mu}m Spitzer photometry of 154 weak-line T Tauri stars (WTTS) in the Chamaeleon, Lupus, Ophiuchus and Taurus star formation regions, all of which are within 200 pc of the Sun. For a comparative study, we also include 33 classical T Tauri stars (CTTS) which are located in the same star forming regions. Spitzer sensitivities allow us to robustly detect the photosphere in the IRAC bands (3.6 to 8 {\mu}m) and the 24 {\mu}m MIPS band. In the 70 {\mu}m MIPS band, we are able to detect dust emission brighter than roughly 40 times the photosphere. These observations represent the most sensitive WTTS survey in the mid to far infrared to date, and reveal the frequency of outer disks (r = 3-50 AU) around WTTS. The 70 {\mu}m photometry for half the c2d WTTS sample (the on-cloud objects), which were not included in the earlier papers in this series, Padgett et al. (2006) and Cieza et al. (2007), are presented here for the first time. We find a disk frequency of 19% for on-cloud WTTS, but just 5% for off- cloud WTTS, similar to the value reported in the earlier works. WTTS exhibit spectral energy distributions (SEDs) that are quite diverse, spanning the range from optically thick to optically thin disks. Most disks become more tenuous than Ldisk/L* = 2 x 10^-3 in 2 Myr, and more tenuous than Ldisk/L* = 5 x 10^-4 in 4 Myr.Comment: 40 pages, 13 figures, 4 tables. Accepted for publication in ApJ on September 20, 201

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
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