40 research outputs found
Ground-based, Near-infrared Exospectroscopy. II. Tentative Detection of Emission From the Extremely Hot Jupiter WASP-12b
We report the tentative detection of the near-infrared emission of the Hot
Jupiter WASP-12b with the low-resolution prism on IRTF/SpeX. We find a K-H
contrast color of 0.137% +/- 0.054%, corresponding to a blackbody of
temperature 2400 (+1500/-500) K and consistent with previous, photometric
observations. We also revisit WASP-12b's energy budget on the basis of
secondary eclipse observations: the dayside luminosity is a relatively poorly
constrained (2.0-4.3) x 10^30 erg/s, but this still allows us to predict a
day/night effective temperature contrast of 200-1,000 K (assuming A_B=0). Thus
we conclude that WASP-12b probably does not have both a low albedo and low
recirculation efficiency. Our results show the promise and pitfalls of using
single-slit spectrographs for characterization of extrasolar planet
atmospheres, and we suggest future observing techniques and instruments which
could lead to further progress. Limiting systematic effects include the use of
a too-narrow slit on one night -- which observers could avoid in the future --
and chromatic slit losses (resulting from the variable size of the seeing disk)
and variations in telluric transparency -- which observers cannot control.
Single-slit observations of the type we present remain the best option for
obtaining lambda > 1.7 micron spectra of transiting exoplanets in the brightest
systems. Further and more precise spectroscopy is needed to better understand
the atmospheric chemistry, structure, and energetics of this, and other,
intensely irradiated planet.Comment: ApJ accepted. 16 pages, 15 figure
Precise Infrared Radial Velocities from Keck/NIRSPEC and the Search for Young Planets
We present a high-precision infrared radial velocity study of late-type stars
using spectra obtained with NIRSPEC at the W. M. Keck Observatory. Radial
velocity precisions of 50 m/s are achieved for old field mid-M dwarfs using
telluric features for precise wavelength calibration. Using this technique, 20
young stars in the {\beta} Pic (age ~12 Myr) and TW Hya (age ~8 Myr)
Associations were monitored over several years to search for low mass
companions; we also included the chromospherically active field star GJ 873 (EV
Lac) in this survey. Based on comparisons with previous optical observations of
these young active stars, radial velocity measurements at infrared wavelengths
mitigate the radial velocity noise caused by star spots by a factor of ~3.
Nevertheless, star spot noise is still the dominant source of measurement error
for young stars at 2.3 {\mu}m, and limits the precision to ~77 m/s for the
slowest rotating stars (v sin i < 6 km/s), increasing to ~168 m/s for rapidly
rotating stars (v sin i > 12 km/s). The observations reveal both GJ 3305 and
TWA 23 to be single-lined spectroscopic binaries; in the case of GJ 3305, the
motion is likely caused by its 0.09" companion, identified after this survey
began. The large amplitude, short-timescale variations of TWA 13A are
indicative of a hot Jupiter-like companion, but the available data are
insufficient to confirm this. We label it as a candidate radial velocity
variable. For the remainder of the sample, these observations exclude the
presence of any 'hot' (P < 3 days) companions more massive than 8 MJup, and any
'warm' (P < 30 days) companions more massive than 17 MJup, on average. Assuming
an edge-on orbit for the edge-on disk system AU Mic, these observations exclude
the presence of any hot Jupiters more massive than 1.8 MJup or warm Jupiters
more massive than 3.9 MJup.Comment: Accepted for publication in The Astrophysical Journal. 18 pages, 7
figure
TESS asteroseismology of the known red-giant host stars HD 212771 and HD 203949
International audienc
PALB2, CHEK2 and ATM rare variants and cancer risk: data from COGS
Background: The rarity of mutations in PALB2, CHEK2 and ATM make it difficult to estimate precisely associated cancer risks. Population-based family studies have provided evidence that at least some of these mutations are associated with breast cancer risk as high as those associated with rare BRCA2 mutations. We aimed to estimate the relative risks associated with specific rare variants in PALB2, CHEK2 and ATM via a multicentre case-control study.Methods: We genotyped 10 rare mutations using the custom iCOGS array: PALB2 c.1592delT, c.2816T>G and c.3113G>A, CHEK2c.349A>G, c.538C>T, c.715G>A, c.1036C>T, c.1312G>T, and c.1343T>G and ATM c.7271T>G. We assessed associations with breast cancer risk (42 671 cases and 42 164 controls), as well as prostate (22 301 cases and 22 320 controls) and ovarian (14 542 cases and 23 491 controls) cancer risk, for each variant.Results: For European women, strong evidence of association with breast cancer risk was observed for PALB2 c.1592delT OR 3.44 (95% CI 1.39 to 8.52, p=7.1×10−5), PALB2 c.3113G>A OR 4.21 (95% CI 1.84 to 9.60, p=6.9×10−8) and ATM c.7271T>G OR 11.0 (95% CI 1.42 to 85.7, p=0.0012). We also found evidence of association with breast cancer risk for three variants in CHEK2, c.349A>G OR 2.26 (95% CI 1.29 to 3.95), c.1036C>T OR 5.06 (95% CI 1.09 to 23.5) and c.538C>T OR 1.33 (95% CI 1.05 to 1.67) (p≤0.017). Evidence for prostate cancer risk was observed for CHEK2 c.1343T>G OR 3.03 (95% CI 1.53 to 6.03, p=0.0006) for African men and CHEK2 c.1312G>T OR 2.21 (95% CI 1.06 to 4.63, p=0.030) for European men. No evidence of association with ovarian cancer was found for any of these variants.Conclusions: This report adds to accumulating evidence that at least some variants in these genes are associated with an increased risk of breast cancer that is clinically important.</p
Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer.
To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC
Recommended from our members
Tools for Improved Management of Buffelgrass in the Sonoran Desert
Buffelgrass (Cenchrus ciliaris L.) is an invasive, perennial, C₄ bunchgrass. Buffelgrass has a rapid invasion rate, a tendency to displace native vegetation, and presents a fire risk to native plant communities, adjacent developed areas and their associated infrastructure. Mechanical control is impractical and unable to keep pace with regional spread. Chemical control has offered the most promise for successful and cost-effective management on a regional scale. The predominant herbicide used to control buffelgrass is glyphosate, which requires active vegetative growth when applied for optimum uptake and translocation to meristematic tissue. The timing and duration of active growth is difficult to predict. In this dissertation I addressed three related topics to improve effectiveness of buffelgrass management in the Sonoran Desert. First, I used digital time-lapse photography and weather data to predict the timing and length of future active growth based on day of year and antecedent weather at three sites in the Sonoran Desert near Tucson, AZ that were representative of habitats currently infested by buffelgrass in the region. I was able to correctly predict greenness above or below a threshold of herbicide susceptibility at 81 to 95% for a basin floor site and at 61-88% for slope sites. Second, I evaluated the effects of different rates of two herbicides (imazapic and clethodim), alone or in combination with different rates of glyphosate, for pre- (imazapic only) and postemergence control of buffelgrass. I found a minimum glyphosate application rate of 2.52 kg ae ha⁻¹ glyphosate consistently killed mature buffelgrass plants; clethodim at had no effect on mature buffelgrass; and imazapyr was successful in killing mature plants when applied during the dormant season at 0.56 kg ae ha⁻¹ and provided preemergence control. Imazapic severely damaged but did not kill mature buffelgrass plants at the maximum label rate of 0.21 kg ae ha⁻¹. Finally, we evaluated results from a helicopter broadcast herbicide application trial conducted in the Tucson Mountains. We demonstrated that most species and life forms were less affected than buffelgrass to glyphosate deposition rates achieved in the study, but asserted that procedural changes were necessary to achieve effective buffelgrass control.Release 1-Aug-201
Fire and Invasive Species Management in Hot Deserts: Resources, Strategies, Tactics, and Response
The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 2020Legacy DOIs that must be preserved: 10.2458/azu_rangelands_v31i3_bea
Integration of grazing and herbicide application improves management of barb goatgrass and medusahead in pasture and rangelands
The invasive annual grasses barb goatgrass (Aegilops triuncialis L.) and medusahead (Elymus caput-medusae L.) are widespread in western states and present management challenges on grasslands. To develop an integrated management strategy for these species, we treated sites in five pastures in Mendocino County, comparing combinations of intensive sheep grazing, glyphosate herbicide (low and high), and application timings (tillering, boot and heading stage). We found that grazing alone reduced barb goatgrass spikelet densities by 68% and the number of seeds per spikelet by 35%. Both rates of glyphosate application without grazing had similar effects on seed production. High and low glyphosate application at tillering resulted in almost complete control of both target species. Boot- and heading-stage applications reduced barb goatgrass density by 39% and 32%, respectively. Application at the boot stage also resulted in an 82% reduction in number of seeds per barb goatgrass spikelet. Our results suggest that intensive grazing may be a useful management strategy to reduce barb goatgrass and medusahead spikelet densities and barb goatgrass seed numbers, especially when integrated with a boot- or heading-stage glyphosate application