1,474 research outputs found
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Speciation on the Rocks: Integrated Systematics of the Heteronotia spelea Species Complex (Gekkota; Reptilia) from Western and Central Australia
The isolated uplands of the Australian arid zone are known to provide mesic refuges in an otherwise xeric landscape, and divergent lineages of largely arid zone taxa have persisted in these regions following the onset of Miocene aridification. Geckos of the genus Heteronotia are one such group, and have been the subject of many genetic studies, including H. spelea, a strongly banded form that occurs in the uplands of the Pilbara and Central Ranges regions of the Australian arid zone. Here we assess the systematics of these geckos based on detailed examination of morphological and genetic variation. The H. spelea species complex is a monophyletic lineage to the exclusion of the H. binoei and H. planiceps species complexes. Within the H. spelea complex, our previous studies based on mtDNA and nine nDNA loci found populations from the Central Ranges to be genetically divergent from Pilbara populations. Here we supplement our published molecular data with additional data gathered from central Australian samples. In the spirit of integrative species delimitation, we combine multi-locus, coalescent-based lineage delimitation with extensive morphological analyses to test species boundaries, and we describe the central populations as a new species, H. fasciolatus sp. nov. In addition, within the Pilbara there is strong genetic evidence for three lineages corresponding to northeastern (type), southern, and a large-bodied melanic population isolated in the northwest. Due to its genetic distinctiveness and extreme morphological divergence from all other Heteronotia, we describe the melanic form as a new species, H. atra sp. nov. The northeastern and southern Pilbara populations are morphologically indistinguishable with the exception of a morpho-type in the southeast that has a banding pattern resembling H. planiceps from the northern monsoonal tropics. Pending more extensive analyses, we therefore treat Pilbara H. spelea as a single species with phylogenetic structure and morphological heterogeneity
Validation of northern latitude Tropospheric Emission Spectrometer stare ozone profiles with ARC-IONS sondes during ARCTAS: sensitivity, bias and error analysis
We compare Tropospheric Emission Spectrometer (TES) versions 3 and 4, V003 and V004, respectively, nadir-stare ozone profiles with ozonesonde profiles from the Arctic Intensive Ozonesonde Network Study (ARCIONS, http://croc.gsfc.nasa.gov/arcions/ during the Arctic Research on the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field mission. The ozonesonde data are from launches timed to match Aura's overpass, where 11 coincidences spanned 44° N to 71° N from April to July 2008. Using the TES "stare" observation mode, 32 observations are taken over each coincidental ozonesonde launch. By effectively sampling the same air mass 32 times, comparisons are made between the empirically-calculated random errors to the expected random errors from measurement noise, temperature and interfering species, such as water. This study represents the first validation of high latitude (>70°) TES ozone. We find that the calculated errors are consistent with the actual errors with a similar vertical distribution that varies between 5% and 20% for V003 and V004 TES data. In general, TES ozone profiles are positively biased (by less than 15%) from the surface to the upper-troposphere (~1000 to 100 hPa) and negatively biased (by less than 20%) from the upper-troposphere to the lower-stratosphere (100 to 30 hPa) when compared to the ozonesonde data. Lastly, for V003 and V004 TES data between 44° N and 71° N there is variability in the mean biases (from −14 to +15%), mean theoretical errors (from 6 to 13%), and mean random errors (from 9 to 19%)
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Multi-Scale Investigations of Liquid Flow in a Fractured Basalt Vadose Zone
Ecological divergence and evolutionary transition of resprouting types in Banksia attenuata
Resprouting is a key functional trait that allows plants to survive diverse disturbances. The fitness benefits associated with resprouting include a rapid return to adult growth, early flowering, and setting seed. The resprouting responses observed following fire are varied, as are the ecological outcomes. Understanding the ecological divergence and evolutionary pathways of different resprouting types and how the environment and genetics interact to drive such morphological evolution represents an important, but under-studied, topic. In the present study, microsatellite markers and microevolutionary approaches were used to better understand: (1) whether genetic differentiation is related to morphological divergence among resprouting types and if so, whether there are any specific genetic variations associated with morphological divergence and (2) the evolutionary pathway of the transitions between two resprouting types in Banksia attenuata (epicormic resprouting from aerial stems or branch; resprouting from a underground lignotuber). The results revealed an association between population genetic differentiation and the morphological divergence of postfire resprouting types in B. attenuata. A microsatellite allele has been shown to be associated with epicormic populations. Approximate Bayesian Computation analysis revealed a likely evolutionary transition from epicormic to lignotuberous resprouting in B. attenuata. It is concluded that the postfire resprouting type in B. attenuata is likely determined by the fire's characteristics. The differentiated expression of postfire resprouting types in different environments is likely a consequence of local genetic adaptation. The capacity to shift the postfire resprouting type to adapt to diverse fire regimes is most likely the key factor explaining why B. attenuata is the most widespread member of the Banksia genus
An Intercomparison of Tropospheric Ozone Retrievals Derived from Two Aura Instruments and Measurements in Western North America in 2006
Two recently developed methods for quantifying tropospheric ozone abundances based on Aura data, the Trajectoryenhanced Tropospheric Ozone Residual (TTOR) and an assimilation of Aura data into Goddard Earth Observing System Version 4 (ASM), are compared to ozone measurements from ozonesonde data collected in April-May 2006 during the INTEX Ozonesonde Network Study 2006 (IONS06) campaign. Both techniques use Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) observations. Statistics on column ozone amounts for both products are presented. In general, the assimilation compares better to sonde integrated ozone to 200 hPa (28.6% difference for TTOR versus 2.7% difference for ASM), and both products are biased low. To better characterize the performance of ASM, ozone profiles based on the assimilation are compared to those from ozonesondes. We noted slight negative biases in the lower troposphere, and slight positive biases in the upper troposphere/lower stratosphere (UT/ LS), where we observed the greatest variability. Case studies were used to further understand ASM performance. We examine one case from 17 April 2006 at Bratt's Lake, Saskatchewan, where geopotential height gradients appear to be related to an underestimation in the ASM in the UT/LS region. A second case, from 21 April 2006 at Trinidad Head, California, is a situation where the overprediction of ozone in the UT/LS region does not appear to be due to current dynamic conditions but seems to be related to uncertainty in the flow pattern and large differences in MLS observations upstream
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‘Dead people don’t claim’: A psychopolitical autopsy of UK austerity suicides
One of the symptoms of post financial crisis austerity in the UK has been an increase in the numbers of suicides, especially by people who have experienced welfare reform. This article develops and utilises an analytic framework of psychopolitical autopsy to explore media coverage of ‘austerity suicide’ and to take seriously the psychic life of austerity (internalisation, shame, anxiety), embedding it in a context of social dis-ease.
Drawing on three distinct yet interrelated areas of literature (the politics of affect and psychosocial dynamics of welfare, post and anti-colonial psychopolitics, and critical suicidology), the article aims to better understand how austerity ‘kills’. Key findings include understanding austerity suicides as embedded within an affective economy of the anxiety caused by punitive welfare retrenchment, the stigmatisation of being a recipient of benefits, and the internalisation of market logic that assigns value through ‘productivity’ and conceptualises welfare entitlement as economic ‘burden’. The significance of this approach lies in its ability to widen analytic framing of suicide from an individual and psychocentric focus, to illuminate culpability of government reforms while still retaining the complexity of suicide, and thus to provide relevant policy insights about welfare reform
The Subaru Coronagraphic Extreme Adaptive Optics system: enabling high-contrast imaging on solar-system scales
The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a
multipurpose high-contrast imaging platform designed for the discovery and
detailed characterization of exoplanetary systems and serves as a testbed for
high-contrast imaging technologies for ELTs. It is a multi-band instrument
which makes use of light from 600 to 2500nm allowing for coronagraphic direct
exoplanet imaging of the inner 3 lambda/D from the stellar host. Wavefront
sensing and control are key to the operation of SCExAO. A partial correction of
low-order modes is provided by Subaru's facility adaptive optics system with
the final correction, including high-order modes, implemented downstream by a
combination of a visible pyramid wavefront sensor and a 2000-element deformable
mirror. The well corrected NIR (y-K bands) wavefronts can then be injected into
any of the available coronagraphs, including but not limited to the phase
induced amplitude apodization and the vector vortex coronagraphs, both of which
offer an inner working angle as low as 1 lambda/D. Non-common path, low-order
aberrations are sensed with a coronagraphic low-order wavefront sensor in the
infrared (IR). Low noise, high frame rate, NIR detectors allow for active
speckle nulling and coherent differential imaging, while the HAWAII 2RG
detector in the HiCIAO imager and/or the CHARIS integral field spectrograph
(from mid 2016) can take deeper exposures and/or perform angular, spectral and
polarimetric differential imaging. Science in the visible is provided by two
interferometric modules: VAMPIRES and FIRST, which enable sub-diffraction
limited imaging in the visible region with polarimetric and spectroscopic
capabilities respectively. We describe the instrument in detail and present
preliminary results both on-sky and in the laboratory.Comment: Accepted for publication, 20 pages, 10 figure
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Evidence Of Rapid Localized Groundwater Transport In Volcanic Tuffs Beneath Yucca Mountain, Nevada
At Yucca Mountain, Nevada-the proposed location for a national high-level nuclear waste repository-radionuclides, if released from breached waste storage canisters, could make their way down through the unsaturated zone (where the repository would be located) into the underlying groundwater and eventually back to the biosphere (i.e., where they could adversely affect human health). The compliance boundary, 18 km south of the proposed repository, is defined as the location where a human being using groundwater would be maximally exposed to radionuclides outside of an exclusion zone set around the repository. It is thus important to predict how these radionuclides would be transported by the groundwater flow, and to predict both the concentration of and the rate at which any leaked radionuclides would arrive at the compliance boundary. We recently conducted a study of groundwater flux in the saturated zone through the Crater Flat Group, in a wellbore 15 km south of the proposed repository. The Crater Flat Group, a sequence of ash-flow tuff formations, is laterally extensive beneath the footprint of the proposed repository. Because of its intense fracturing and high permeabilities, the Bullfrog tuff is the primary unit within the Cratei Flat Group through which radionuclides would be transported, as indicated by groundwater models. In a new wellbore, NC-EWDP-24PB, we conducted flowing electrical conductivity logging (FEC), an open-wellbore logging technique, to identify flowing fractures prior to wellbore completion. While the FEC logs have identified transmissive zones, quantitative interpretation of the FEC results was difficult because differences in hydraulic heads in different flowing intervals created significant intraborehole fluid flow. The well was subsequently backfilled and completed with a distributed thermal perturbation sensor (DTPS), which introduces a thermal pulse to the wellbore and uses the thermal transient to estimate groundwater flux. Corroborating FEC observations, the DTPS has identified two flowing intervals within the Bullfrog tuff that are each approximately 20 m thick and exhibit an average specific discharge of 50 m/yr. Assuming a fracture porosity of 1%, groundwater velocities are estimated to be on the order of 5 to 10 km/yr. While these results are for one borehole, heterogeneity in the flow system may play a significant role in determining regional groundwater flow. Additional data, including geochemical and isotopic, will be needed to provide a more complete picture of the origin of the groundwater in these fast flow paths, and aid in the determination of the lateral extent of the identified flowing intervals
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