150 research outputs found
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Sampling of Borehole WL-3A through -12 in Support of the Vadose Zone Transport Field Study
This report presents the results of the fiscal year 2001 core sampling effort conducted to support the Vadose Zone Transport Field Study
The Kepler Pixel Response Function
Kepler seeks to detect sequences of transits of Earth-size exoplanets
orbiting Solar-like stars. Such transit signals are on the order of 100 ppm.
The high photometric precision demanded by Kepler requires detailed knowledge
of how the Kepler pixels respond to starlight during a nominal observation.
This information is provided by the Kepler pixel response function (PRF),
defined as the composite of Kepler's optical point spread function, integrated
spacecraft pointing jitter during a nominal cadence and other systematic
effects. To provide sub-pixel resolution, the PRF is represented as a
piecewise-continuous polynomial on a sub-pixel mesh. This continuous
representation allows the prediction of a star's flux value on any pixel given
the star's pixel position. The advantages and difficulties of this polynomial
representation are discussed, including characterization of spatial variation
in the PRF and the smoothing of discontinuities between sub-pixel polynomial
patches. On-orbit super-resolution measurements of the PRF across the Kepler
field of view are described. Two uses of the PRF are presented: the selection
of pixels for each star that maximizes the photometric signal to noise ratio
for that star, and PRF-fitted centroids which provide robust and accurate
stellar positions on the CCD, primarily used for attitude and plate scale
tracking. Good knowledge of the PRF has been a critical component for the
successful collection of high-precision photometry by Kepler.Comment: 10 pages, 5 figures, accepted by ApJ Letters. Version accepted for
publication
Soil Resources Influence Vegetation and Response to Fire and Fire-Surrogate Treatments in Sagebrush-Steppe Ecosystems
Current paradigm suggests that spatial and temporal competition for resources limit an exotic invader, cheatgrass (Bromus tectorum L.), which once established, alters fire regimes and can result in annual grass dominance in sagebrush steppe. Prescribed fire and fire surrogate treatments (mowing, tebuthiuron, and imazapic) are used to reduce woody fuels and increase resistance to exotic annuals, but may alter resource availability and inadvertently favor invasive species. We used four study sites within the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) to evaluate 1) how vegetation and soil resources were affected by treatment, and 2) how soil resources influenced native herbaceous perennial and exotic annual grass cover before and following treatment. Treatments increased resin exchangeable NH4+, NO3-, H2PO4-, and K+, with the largest increases caused by prescribed fire and prolonged by application of imazapic. Burning with imazapic application also increased the number of wet growing degree days. Tebuthiuron and imazapic reduced exotic annual grass cover, but imazapic also reduced herbaceous perennial cover when used with prescribed fire. Native perennial herbaceous species cover was higher where mean annual precipitation and soil water resources were relatively high. Exotic annual grass cover was higher where resin exchangeable H2PO4- was high and gaps between perennial plants were large. Prescribed fire, mowing, and tebuthiuron were successful at increasing perennial herbaceous cover, but the results were often ephemeral and inconsistent among sites. Locations with sandy soil, low mean annual precipitation, or low soil water holding capacity were more likely to experience increased exotic annual grass cover after treatment, and treatments that result in slow release of resources are needed on these sites. This is one of few studies that correlate abiotic variables to native and exotic species cover across a broad geographic setting, and that demonstrates how soil resources potentially influence the outcome of management treatments
Woodland Expansion\u27s Influence on Belowground Carbon and Nitrogen in the Great Basin U.S.
Vegetation changes associated with climate shifts and anthropogenic disturbance can have major impacts on biogeochemical cycling and soils. Much of the Great Basin, U.S. is currently dominated by sagebrush (Artemisia tridentate (Rydb.) Boivin) ecosystems. Sagebrush ecosystems are increasingly influenced by pinyon (Pinus monophylla Torr. & Frém and Pinus edulis Engelm.) and juniper (Juniperus osteosperma Torr. and Juniperus occidentalis Hook.) expansion. Some scientists and policy makers believe that increasing woodland cover in the intermountain western U.S. offers the possibility of increased organic carbon (OC) storage on the landscape; however, little is currently known about the distribution of OC on these landscapes, or the role that nitrogen (N) plays in OC retention. We quantified the relationship between tree cover, belowground OC, and total below ground N in expansion woodlands at 13 sites in Utah, Oregon, Idaho, California, and Nevada, USA. One hundred and twenty nine soil cores were taken using a mechanically driven diamond tipped core drill to a depth of 90 cm. Soil, coarse fragments, and coarse roots were analyzed for OC and total N. Woodland expansion influenced the vertical distribution of root OC by increasing 15–30 cm root OC by 2.6 Mg ha−1 and root N by 0.04 Mg ha−1. Root OC and N increased through the entire profile by 3.8 and 0.06 Mg ha−1 respectively. Woodland expansion influenced the vertical distribution of soil OC by increasing surface soil (0–15 cm) OC by 2.2 Mg ha−1. Woodland expansion also caused a 1.3 Mg ha−1 decrease in coarse fragment associated OC from 75–90 cm. Our data suggests that woodland expansion into sagebrush ecosystems has limited potential to store additional belowground OC, and must be weighed against the risk of increased wildfire and exotic grass invasion
Impaired self awareness after traumatic brain injury: inter-rater reliability and factor structure of the dysexecutive questionnairre (DEX) in patients, significant others and clinicians
Aims: This study sought to address two questions: (1) what is the inter-rater reliability
of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant
others, and clinicians; and (2) does the factor structure of the DEX vary for these three
groups?
Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from
two brain injury services in the UK and two services in Ireland. We gathered data from
two groups of raters—”significant others” (DEX-SO) such as partners and close family
members and “clinicians” (DEX-C), who were psychologists or rehabilitation physicians
working closely with the patient and who were able to provide an opinion about the
patient’s level of everyday executive functioning. Intra-class correlation coefficients and
their 95% confidence intervals were calculated between each of the three groups (self,
significant other, clinician). Principal axis factor (PAF) analyses were also conducted for
each of the three groups.
Results: The factor analysis revealed a consistent one-factor model for each of the
three groups of raters. However, the inter-rater reliability analyses showed a low level of
agreement between the self-ratings and the ratings of the two groups of independent
raters. We also found low agreement between the significant others and the clinicians.
Conclusion: Although there was a consistent finding of a single factor solution for each
of the three groups, the low level of agreement between significant others and clinicians
raises a question about the reliability of the DEX.</p
Impaired self awareness after traumatic brain injury: inter-rater reliability and factor structure of the dysexecutive questionnairre (DEX) in patients, significant others and clinicians
Aims: This study sought to address two questions: (1) what is the inter-rater reliability
of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant
others, and clinicians; and (2) does the factor structure of the DEX vary for these three
groups?
Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from
two brain injury services in the UK and two services in Ireland. We gathered data from
two groups of raters—”significant others” (DEX-SO) such as partners and close family
members and “clinicians” (DEX-C), who were psychologists or rehabilitation physicians
working closely with the patient and who were able to provide an opinion about the
patient’s level of everyday executive functioning. Intra-class correlation coefficients and
their 95% confidence intervals were calculated between each of the three groups (self,
significant other, clinician). Principal axis factor (PAF) analyses were also conducted for
each of the three groups.
Results: The factor analysis revealed a consistent one-factor model for each of the
three groups of raters. However, the inter-rater reliability analyses showed a low level of
agreement between the self-ratings and the ratings of the two groups of independent
raters. We also found low agreement between the significant others and the clinicians.
Conclusion: Although there was a consistent finding of a single factor solution for each
of the three groups, the low level of agreement between significant others and clinicians
raises a question about the reliability of the DEX.</p
Developing a strategy for the national coordinated soil moisture monitoring network
Soil moisture is a critical land surface variable, affecting a wide variety of climatological, agricultural, and hydrological processes. Determining the current soil moisture status is possible via a variety of methods, including in situ monitoring, remote sensing, and numerical modeling. Although all of these approaches are rapidly evolving, there is no cohesive strategy or framework to integrate these diverse information sources to develop and disseminate coordinated national soil moisture products that will improve our ability to understand climate variability. The National Coordinated Soil Moisture Monitoring Network initiative has developed a national strategy for network coordination with NOAA’s National Integrated Drought Information System. The strategy is currently in review within NOAA, and work is underway to implement the initial milestones of the strategy. This update reviews the goals and steps being taken to establish this national-scale coordination for soil moisture monitoring in the United States
Overview of the Kepler Science Processing Pipeline
The Kepler Mission Science Operations Center (SOC) performs several critical
functions including managing the ~156,000 target stars, associated target
tables, science data compression tables and parameters, as well as processing
the raw photometric data downlinked from the spacecraft each month. The raw
data are first calibrated at the pixel level to correct for bias, smear induced
by a shutterless readout, and other detector and electronic effects. A
background sky flux is estimated from ~4500 pixels on each of the 84 CCD
readout channels, and simple aperture photometry is performed on an optimal
aperture for each star. Ancillary engineering data and diagnostic information
extracted from the science data are used to remove systematic errors in the
flux time series that are correlated with these data prior to searching for
signatures of transiting planets with a wavelet-based, adaptive matched filter.
Stars with signatures exceeding 7.1 sigma are subjected to a suite of
statistical tests including an examination of each star's centroid motion to
reject false positives caused by background eclipsing binaries. Physical
parameters for each planetary candidate are fitted to the transit signature,
and signatures of additional transiting planets are sought in the residual
light curve. The pipeline is operational, finding planetary signatures and
providing robust eliminations of false positives.Comment: 8 pages, 3 figure
Recommended from our members
Soil Resources Influence Vegetation and Response to Fire and Fire-Surrogate Treatments in Sagebrush-Steppe Ecosystems
Current paradigm suggests that spatial and temporal competition for resources limit an exotic invader, cheatgrass (Bromus
tectorum L.), which once established, alters fire regimes and can result in annual grass dominance in sagebrush steppe.
Prescribed fire and fire surrogate treatments (mowing, tebuthiuron, and imazapic) are used to reduce woody fuels and increase
resistance to exotic annuals, but may alter resource availability and inadvertently favor invasive species.We used four study sites
within the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) to evaluate 1) how vegetation and soil resources were
affected by treatment, and 2) how soil resources influenced native herbaceous perennial and exotic annual grass cover before
and following treatment. Treatments increased resin exchangeable NH₄⁺, NO₃⁻, H₂PO₄⁻, and K⁺, with the largest increases
caused by prescribed fire and prolonged by application of imazapic. Burning with imazapic application also increased the
number of wet growing degree days. Tebuthiuron and imazapic reduced exotic annual grass cover, but imazapic also reduced
herbaceous perennial cover when used with prescribed fire. Native perennial herbaceous species cover was higher where mean
annual precipitation and soil water resources were relatively high. Exotic annual grass cover was higher where resin
exchangeable H₂PO₄⁻ was high and gaps between perennial plants were large. Prescribed fire, mowing, and tebuthiuron were
successful at increasing perennial herbaceous cover, but the results were often ephemeral and inconsistent among sites.
Locations with sandy soil, low mean annual precipitation, or low soil water holding capacity were more likely to experience
increased exotic annual grass cover after treatment, and treatments that result in slow release of resources are needed on these
sites. This is one of few studies that correlate abiotic variables to native and exotic species cover across a broad geographic
setting, and that demonstrates how soil resources potentially influence the outcome of management treatments.Keywords: prescribed fire, soil water, soil nutrients, herbicide, exotic annual grass, mowin
Planetary Candidates Observed by Kepler V: Planet Sample from Q1-Q12 (36 Months)
The Kepler mission discovered 2842 exoplanet candidates with 2 years of data.
We provide updates to the Kepler planet candidate sample based upon 3 years
(Q1-Q12) of data. Through a series of tests to exclude false-positives,
primarily caused by eclipsing binary stars and instrumental systematics, 855
additional planetary candidates have been discovered, bringing the total number
known to 3697. We provide revised transit parameters and accompanying posterior
distributions based on a Markov Chain Monte Carlo algorithm for the cumulative
catalogue of Kepler Objects of Interest. There are now 130 candidates in the
cumulative catalogue that receive less than twice the flux the Earth receives
and more than 1100 have a radius less than 1.5 Rearth. There are now a dozen
candidates meeting both criteria, roughly doubling the number of candidate
Earth analogs. A majority of planetary candidates have a high probability of
being bonafide planets, however, there are populations of likely
false-positives. We discuss and suggest additional cuts that can be easily
applied to the catalogue to produce a set of planetary candidates with good
fidelity. The full catalogue is publicly available at the NASA Exoplanet
Archive.Comment: Accepted for publication, ApJ
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