1,445 research outputs found
The Gemini NICI Planet-Finding Campaign: The Offset Ring of HR 4796 A
We present J, H, CH_4 short (1.578 micron), CH_4 long (1.652 micron) and
K_s-band images of the dust ring around the 10 Myr old star HR 4796 A obtained
using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1
meter Telescope. Our images clearly show for the first time the position of the
star relative to its circumstellar ring thanks to NICI's translucent focal
plane occulting mask. We employ a Bayesian Markov Chain Monte Carlo method to
constrain the offset vector between the two. The resulting probability
distribution shows that the ring center is offset from the star by 16.7+/-1.3
milliarcseconds along a position angle of 26+/-3 degrees, along the PA of the
ring, 26.47+/-0.04 degrees. We find that the size of this offset is not large
enough to explain the brightness asymmetry of the ring. The ring is measured to
have mostly red reflectivity across the JHK_s filters, which seems to indicate
micron-sized grains. Just like Neptune's 3:2 and 2:1 mean-motion resonances
delineate the inner and outer edges of the classical Kuiper Belt, we find that
the radial extent of the HR 4796 A and Fomalhaut rings could correspond to the
3:2 and 2:1 mean-motion resonances of hypothetical planets at 54.7 AU and 97.7
AU in the two systems, respectively. A planet orbiting HR 4796 A at 54.7 AU
would have to be less massive than 1.6 Mjup so as not to widen the ring too
much by stirring.Comment: Accepted to A&A for publication on April 23, 2014 (15 pages, 9
figures, 4 tables
Genomic analysis of advanced breast cancer tumors from talazoparib-treated gBRCA1/2mut carriers in the ABRAZO study
Breast cancer; Pharmacogenomics; Tumour biomarkersCáncer de mama; Farmacogenómica; Biomarcadores tumoralesCà ncer de mama; Farmacogenòmica; Biomarcadors tumoralsThese analyses explore the impact of homologous recombination repair gene mutations, including BRCA1/2 mutations and homologous recombination deficiency (HRD), on the efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor talazoparib in the open-label, two-cohort, Phase 2 ABRAZO trial in germline BRCA1/2-mutation carriers. In the evaluable intent-to-treat population (N = 60), 58 (97%) patients harbor ≥1 BRCA1/2 mutation(s) in tumor sequencing, with 95% (53/56) concordance between germline and tumor mutations, and 85% (40/47) of evaluable patients have BRCA locus loss of heterozygosity indicating HRD. The most prevalent non-BRCA tumor mutations are TP53 in patients with BRCA1 mutations and PIK3CA in patients with BRCA2 mutations. BRCA1- or BRCA2-mutated tumors show comparable clinical benefit within cohorts. While low patient numbers preclude correlations between HRD and efficacy, germline BRCA1/2 mutation detection from tumor-only sequencing shows high sensitivity and non-BRCA genetic/genomic events do not appear to influence talazoparib sensitivity in the ABRAZO trial.In Manchester, this trial was undertaken in/supported by the NIHR Manchester Clinical Research Facility at The Christie Hospital NHS Foundation Trust. The ABRAZO study was sponsored by Medivation, which was acquired by Pfizer in September 2016 (grant number not applicable). The authors wish to thank Masaki Mihaila and the Pfizer clinical programming team for the ABRAZO correlative analyses. Medical writing support was provided by Dominic James, PhD, and Hannah Logan, PhD, of CMC AFFINITY, a division of IPG Health Medical Communications, and was funded by Pfizer
NICI: combining coronagraphy, ADI, and SDI
The Near-Infrared Coronagraphic Imager (NICI) is a high-contrast AO imager at
the Gemini South telescope. The camera includes a coronagraphic mask and dual
channel imaging for Spectral Differential Imaging (SDI). The instrument can
also be used in a fixed Cassegrain Rotator mode for Angular Differential
Imaging (ADI). While coronagraphy, SDI, and ADI have been applied before in
direct imaging searches for exoplanets. NICI represents the first time that
these 3 techniques can be combined. We present preliminary NICI commissioning
data using these techniques and show that combining SDI and ADI results in
significant gains.Comment: Proc. SPIE, Vol. 7014, 70141Z (2008
The Gemini NICI Planet-Finding Campaign
Our team is carrying out a multi-year observing program to directly image and
characterize young extrasolar planets using the Near-Infrared Coronagraphic
Imager (NICI) on the Gemini-South 8.1-meter telescope. NICI is the first
instrument on a large telescope designed from the outset for high-contrast
imaging, comprising a high-performance curvature adaptive optics system with a
simultaneous dual-channel coronagraphic imager. Combined with state-of-the-art
observing methods and data processing, NICI typically achieves ~2 magnitudes
better contrast compared to previous ground-based or space-based programs, at
separations inside of ~2 arcsec. In preparation for the Campaign, we carried
out efforts to identify previously unrecognized young stars, to rigorously
construct our observing strategy, and to optimize the combination of angular
and spectral differential imaging. The Planet-Finding Campaign is in its second
year, with first-epoch imaging of 174 stars already obtained out of a total
sample of 300 stars. We describe the Campaign's goals, design, implementation,
performance, and preliminary results. The NICI Campaign represents the largest
and most sensitive imaging survey to date for massive (~1 Mjup) planets around
other stars. Upon completion, the Campaign will establish the best measurements
to date on the properties of young gas-giant planets at ~5-10 AU separations.
Finally, Campaign discoveries will be well-suited to long-term orbital
monitoring and detailed spectrophotometric followup with next-generation
planet-finding instruments.Comment: Proceedings of the SPIE, vol 7736 (Advances in Adaptive Optics, San
Diego, CA, June 2010 meeting), in pres
The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets Around Debris Disk Stars
We have completed a high-contrast direct imaging survey for giant planets
around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign.
We achieved median H-band contrasts of 12.4 mag at 0.5" and 14.1 mag at 1"
separation. Follow-up observations of the 66 candidates with projected
separation < 500 AU show that all of them are background objects. To establish
statistical constraints on the underlying giant planet population based on our
imaging data, we have developed a new Bayesian formalism that incorporates (1)
non-detections, (2) single-epoch candidates, (3) astrometric and (4)
photometric information, and (5) the possibility of multiple planets per star
to constrain the planet population. Our formalism allows us to include in our
analysis the previously known Beta Pictoris and the HR 8799 planets. Our
results show at 95% confidence that 5MJup
planet beyond 80 AU, and 3MJup planet outside
of 40 AU, based on hot-start evolutionary models. We model the population of
directly-imaged planets as d^2N/dMda ~ m^alpha a^beta, where m is planet mass
and a is orbital semi-major axis (with a maximum value of amax). We find that
beta 1.7. Likewise, we find that beta < -0.8 and/or amax
< 200 AU. If we ignore the Beta Pic and HR 8799 planets (should they belong to
a rare and distinct group), we find that
3MJup planet beyond 10 AU, and beta < -0.8 and/or alpha < -1.5. Our Bayesian
constraints are not strong enough to reveal any dependence of the planet
frequency on stellar host mass. Studies of transition disks have suggested that
about 20% of stars are undergoing planet formation; our non-detections at large
separations show that planets with orbital separation > 40 AU and planet masses
> 3 MJup do not carve the central holes in these disks.Comment: Accepted to ApJ on June 24, 2013. 67 pages, 17 figures, 12 table
Randomized double-blind trial of pregabalin versus placebo in conjunction with palliative radiotherapy for cancer-induced bone pain
Purpose
Cancer-induced bone pain (CIBP) affects one third of patients with cancer. Radiotherapy remains the gold-standard treatment; however, laboratory and clinical work suggest that pregabalin may be useful in treating CIBP. The aim of this study was to examine pregabalin in patients with CIBP receiving radiotherapy.
Patients and Methods
A multicenter, double-blind randomized trial of pregabalin versus placebo was conducted. Eligible patients were age ≥ 18 years, had radiologically proven bone metastases, were scheduled to receive radiotherapy, and had pain scores ≥ 4 of 10 (on 0-to-10 numeric rating scale). Before radiotherapy, baseline assessments were completed, followed by random assignment. Doses of pregabalin and placebo were increased over 4 weeks. The primary end point was treatment response, defined as a reduction of ≥ 2 points in worst pain by week 4, accompanied by a stable or reduced opioid dose, compared with baseline. Secondary end points assessed average pain, interference of pain with activity, breakthrough pain, mood, quality of life, and adverse events.
Results
A total of 233 patients were randomly assigned: 117 to placebo and 116 to pregabalin. The most common cancers were prostate (n = 88; 38%), breast (n = 77; 33%), and lung (n = 42; 18%). In the pregabalin arm, 45 patients (38.8%) achieved the primary end point, compared with 47 (40.2%) in the placebo arm (adjusted odds ratio, 1.07; 95% CI, 0.63 to 1.81; P = .816). There were no statistically significant differences in average pain, pain interference, or quality of life between arms. There were differences in mood (P = .031) and breakthrough pain duration (P = .037) between arms. Outcomes were compared at 4 weeks.
Conclusion
Our findings do not support the role of pregabalin in patients with CIBP receiving radiotherapy. The role of pregabalin in CIBP with a clinical neuropathic pain component is unknown
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