43 research outputs found
Vortex Fiber Nulling for Exoplanet Observations: Implementation and First Light
Vortex fiber nulling (VFN) is a single-aperture interferometric technique for
detecting and characterizing exoplanets separated from their host star by less
than a diffracted beam width. VFN uses a vortex mask and single mode fiber to
selectively reject starlight while coupling off-axis planet light with a simple
optical design that can be readily implemented on existing direct imaging
instruments that can feed light to an optical fiber. With its axially symmetric
coupling region peaking within the inner working angle of conventional
coronagraphs, VFN is more efficient at detecting new companions at small
separations than conventional direct imaging, thereby increasing the yield of
on-going exoplanet search campaigns. We deployed a VFN mode operating in K band
(m) on the Keck Planet Imager and Characterizer (KPIC)
instrument at the Keck II Telescope. In this paper we present the instrument
design of this first on-sky demonstration of VFN and the results from on-sky
commissioning, including planet and star throughput measurements and predicted
flux-ratio detection limits for close-in companions. The instrument performance
is shown to be sufficient for detecting a companion times fainter than a
magnitude host star in 1 hour at a separation of 50 mas
(1.1). This makes the instrument capable of efficiently detecting
substellar companions around young stars. We also discuss several routes for
improvement that will reduce the required integration time for a detection by a
factor 3.Comment: 26 pages, 5 figures; Accepted to JATI
Stimulant Reduction Intervention using Dosed Exercise (STRIDE) - CTN 0037: Study protocol for a randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study.</p> <p>Methods/Design</p> <p>STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI) or Health Education Intervention Augmentation (HEI). Both groups will receive TAU (i.e., usual care). The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual) sessions, although other participants may be exercising at the same time. Following the 12-week acute phase, participants will begin a 6-month continuation phase during which time they will attend one weekly supervised DEI or HEI session.</p> <p>Clinical Trials Registry</p> <p>ClinicalTrials.gov, <a href="http://www.clinicaltrials.gov/ct2/show/NCT01141608">NCT01141608</a></p> <p><url>http://clinicaltrials.gov/ct2/show/NCT01141608?term=Stimulant+Reduction+Intervention+using+Dosed+Exercise&rank=1</url></p
Polygamy reconsidered : African plural marriage and the Christian Churches
New Yorkx, 266 p.; 21 c
Polygamy Reconsidered : African Plural Marriage and the Christian Churches
Maryknollx, 266 p.: 22 c