Tracking ocean wave spectrum from SAR images

An end to end algorithm for recovery of ocean wave spectral peaks from Synthetic Aperture Radar (SAR) images is described. Current approaches allow precisions of 1 percent in wave number, and 0.6 deg in direction

Searching for keV Sterile Neutrino Dark Matter with X-ray Microcalorimeter Sounding Rockets

High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field-of-view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l = 165, b = -5 with an effective exposure of 106 seconds, obtaining a limit on the sterile neutrino mixing angle of sin^2(2 theta) < 7.2e-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of sin^2(2 theta) ~ 2.1e-11 at 95\% CL for a 7 keV neutrino is achievable with future 300-second observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.Comment: 13 pages, 13 figures, submitted to Ap

The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group

We have observed and spatially resolved a set of seven A-type stars in the nearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combiners on the CHARA Array. At least four of these stars have large rotational velocities ($v \sin i$ $\gtrsim$ 170 $\mathrm{km~s^{-1}}$) and are expected to be oblate. These interferometric measurements, the stars' observed photometric energy distributions, and $v \sin i$ values are used to computationally construct model oblate stars from which stellar properties (inclination, rotational velocity, and the radius and effective temperature as a function of latitude, etc.) are determined. The results are compared with MESA stellar evolution models (Paxton et al. 2011, 2013) to determine masses and ages. The value of this new technique is that it enables the estimation of the fundamental properties of rapidly rotating stars without the need to fully image the star. It can thus be applied to stars with sizes comparable to the interferometric resolution limit as opposed to those that are several times larger than the limit. Under the assumption of coevality, the spread in ages can be used as a test of both the prescription presented here and the MESA evolutionary code for rapidly rotating stars. With our validated technique, we combine these age estimates and determine the age of the moving group to be 414 $\pm$ 23 Myr, which is consistent with, but much more precise than previous estimates.Comment: Accepted by Ap

Peer education for secondary stroke prevention in inner-city minorities: Design and methods of the Prevent Recurrence of All Inner-city Strokes through Education randomized controlled trial

Background The highest risk for stroke is among survivors of strokes or transient ischemic attacks (TIA). However, use of proven-effective cardiovascular medications to control stroke risk is suboptimal, particularly among the Black and Latino populations disproportionately impacted by stroke. Methods A partnership of Harlem and Bronx community representatives, stroke survivors, researchers, clinicians, outreach workers and patient educators used community-based participatory research to conceive and develop the Prevent Recurrence of All Inner-city Strokes through Education (PRAISE) trial. Using data from focus groups with stroke survivors, they tailored a peer-led, community-based chronic disease self-management program to address stroke risk factors. PRAISE will test, in a randomized controlled trial, whether this stroke education intervention improves blood pressure control and a composite outcome of blood pressure control, lipid control, and use of antithrombotic medications. Results Of the 582 survivors of stroke and TIA enrolled thus far, 81% are Black or Latino and 56% have an annual income less than $15,000. Many (33%) do not have blood pressures in the target range, and most (66%) do not have control of all three major stroke risk factors. Conclusions Rates of stroke recurrence risk factors remain suboptimal in the high risk, urban, predominantly minority communities studied. With a community-partnered approach, PRAISE has recruited a large number of stroke and TIA survivors to date, and may prove successful in engaging those at highest risk for stroke and reducing disparities in stroke outcomes in inner-city communities

Empowerment and the Transition to Housing for Homeless Mentally Ill People: An Anthropological Perspective

Often lacking in scholarly and policy-oriented discussions of homelessness are contextualized understandings of the problems faced, and the values held, by homeless mentally ill people. This article, using an anthropological perspective, examines issues that arise for homeless mentally ill individuals in making the transition from shelter living to permanent residences. The transition occurs as part of a housing initiative driven by the philosophy of consumer empowerment. Project participants are placed in independent apartments or evolving consumer households (ECH) — shared, staffed residences designed to transform themselves into consumer-directed living situations over time. The effects of an empowerment paradigm on the organization of space, the nature of social relations, and the management of economic resources in the ECHs are discussed to show that consumers and staff sometimes have contrasting views of what empowerment entails. It is suggested that anthropological research can help to illuminate the issues at stake in determining policy for homeless people with major mental illness

Effect of Peer Education on Stroke Prevention: The Prevent Recurrence of All Inner-City Strokes Through Education Randomized Controlled Trial

Background and Purpose—Efforts to reduce disparities in recurrent stroke among Black and Latino stroke survivors have met with limited success. We aimed to determine the effect of peer education on secondary stroke prevention among predominantly minority stroke survivors. Methods—Between 2009 and 2012, we enrolled 600 stroke or transient ischemic attack survivors from diverse, low-income communities in New York City into a 2-arm randomized clinical trial that compared a 6 week (1 session/week), peer-led, community-based, stroke prevention self-management group workshop (N=301) to a wait-list control group (N=299). The primary outcome was the proportion with a composite of controlled blood pressure (<140/90 mm Hg), low-density lipoprotein cholesterol <100 mg/dL, and use of antithrombotic medications at 6 months. Secondary outcomes included control of the individual stroke risk factors. All analyses were by intent-to-treat. Results—There was no difference in the proportion of intervention and control group participants achieving the composite outcome (34% versus 34%; P=0.98). The proportion with controlled blood pressure at 6 months was greater in the intervention group than in the control group (76% versus 67%; P=0.02). This corresponded to a greater change in systolic blood pressure in the intervention versus control group (−3.63 SD, 19.81 mm Hg versus +0.34 SD, 23.76 mm Hg; P=0.04). There were no group differences in the control of cholesterol or use of antithrombotics. Conclusions—A low-cost peer education self-management workshop modestly improved blood pressure, but not low-density lipoprotein cholesterol or antithrombotic use, among stroke and transient ischemic attack survivors from vulnerable, predominantly minority urban communities

Correlates of Post-traumatic Stress Disorder in Stroke Survivors

Background Post-traumatic stress disorder (PTSD) can occur after life-threatening events, including illness, but correlates of PTSD after stroke or transient ischemic attack (TIA) have not been well described. Methods We measured the prevalence of stroke-induced PTSD with the PTSD Checklist Specific for stroke (PCL-S) in adults who had a stroke or TIA within 5 years. A PCL-S score of 50 or more indicated likely PTSD. We tested for potential predictors of stroke-associated PTSD, including demographics, stroke history, disability, medical comorbidities, depression, and emotional support and then examined the association between poststroke PTSD and measures of physical and mental health. Results Of 535 participants, 95 (18%) had a PCL-S score of 50 or more; the mean score was 35.4 ± 13.7 (range 17-80 of 85). In logistic regression analysis, low income (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.01-3.61), recurrent stroke or TIA (OR 1.86, 1.10-3.16), more disability (OR 1.79, 1.43-2.23), and increased comorbidities (OR 1.90, 1.05-3.45) were independently associated with PTSD. Older age (OR .93, .90-.95), marriage or partnership (OR .52, .28-.98), and having emotional support (OR .25, .11-.54) were protective against developing PTSD. Participants with likely PTSD had worse physical and mental health. Conclusions In this racially and ethnically diverse cohort of stroke and TIA survivors, stroke-induced PTSD was associated with younger age, recurrent strokes, greater disability, and comorbidities. PTSD was associated with a substantially increased physical, mental, and quality of life burden in this already vulnerable population. Having social support was protective, suggesting a potential target for intervention

Interferometric radii of bright Kepler stars with the CHARA Array: {\theta} Cygni and 16 Cygni A and B

We present the results of long-baseline optical interferometry observations using the Precision Astronomical Visual Observations (PAVO) beam combiner at the Center for High Angular Resolution Astronomy (CHARA) Array to measure the angular sizes of three bright Kepler stars: {\theta} Cygni, and both components of the binary system 16 Cygni. Supporting infrared observations were made with the Michigan Infrared Combiner (MIRC) and Classic beam combiner, also at the CHARA Array. We find limb-darkened angular diameters of 0.753+/-0.009 mas for {\theta} Cyg, 0.539+/-0.007 mas for 16 Cyg A and 0.490+/-0.006 mas for 16 Cyg B. The Kepler Mission has observed these stars with outstanding photometric precision, revealing the presence of solar-like oscillations. Due to the brightness of these stars the oscillations have exceptional signal-to-noise, allowing for detailed study through asteroseismology, and are well constrained by other observations. We have combined our interferometric diameters with Hipparcos parallaxes, spectrophotometric bolometric fluxes and the asteroseismic large frequency separation to measure linear radii ({\theta} Cyg: 1.48+/-0.02 Rsun, 16 Cyg A: 1.22+/-0.02 Rsun, 16 Cyg B: 1.12+/-0.02 Rsun), effective temperatures ({\theta} Cyg: 6749+/-44 K, 16 Cyg A: 5839+/-42 K, 16 Cyg B: 5809+/-39 K), and masses ({\theta} Cyg: 1.37+/-0.04 Msun, 16 Cyg A: 1.07+/-0.05 Msun, 16 Cyg B: 1.05+/-0.04 Msun) for each star with very little model dependence. The measurements presented here will provide strong constraints for future stellar modelling efforts.Comment: 9 pages, 4 figures, and 5 tables, accepted for publication in Monthly Notices of the Royal Astronomical Societ

The CHARA Array Angular Diameter of HR 8799 Favors Planetary Masses for Its Imaged Companions

HR 8799 is an hF0 mA5 gamma Doradus, lambda Bootis, Vega-type star best known for hosting four directly imaged candidate planetary companions. Using the CHARA Array interferometer, we measure HR 8799's limb-darkened angular diameter to be 0.342 +/- 0.008 mas; this is the smallest interferometrically measured stellar diameter to date, with an error of only 2%. By combining our measurement with the star's parallax and photometry from the literature, we greatly improve upon previous estimates of its fundamental parameters, including stellar radius (1.44 +/- 0.06 R_Sun), effective temperature (7193 +/- 87 K, consistent with F0), luminosity (5.05 +/- 0.29 L_Sun), and the extent of the habitable zone (1.62 AU to 3.32 AU). These improved stellar properties permit much more precise comparisons with stellar evolutionary models, from which a mass and age can be determined, once the metallicity of the star is known. Considering the observational properties of other lambda Bootis stars and the indirect evidence for youth of HR 8799, we argue that the internal abundance, and what we refer to as the effective abundance, is most likely near-solar. Finally, using the Yonsei-Yale evolutionary models with uniformly scaled solar-like abundances, we estimate HR 8799's mass and age considering two possibilities: 1.516 +0.038/-0.024 M_Sun and 33 +7/-13 Myr if the star is contracting toward the zero age main-sequence or 1.513 +0.023/-0.024 M_Sun and 90 +381/-50 Myr if it is expanding from it. This improved estimate of HR 8799's age with realistic uncertainties provides the best constraints to date on the masses of its orbiting companions, and strongly suggests they are indeed planets. They nevertheless all appear to orbit well outside the habitable zone of this young star.Comment: Accepted for publication in ApJ; 37 pages, 6 tables, 13 figure