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We present the Young Exoplanet Transit Initiative (YETI), in which we use several 0.2 to 2.6-m telescopes around the world to monitor continuously young (≤100 Myr), nearby (≤1 kpc) stellar clusters mainly to detect young transiting planets (and to study other variability phenomena on time-scales from minutes to years). The telescope network enables us to observe the targets continuously for several days in order not to miss any transit. The runs are typically one to two weeks long, about three runs per year per cluster in two or three subsequent years for about ten clusters. There are thousands of stars detectable in each field with several hundred known cluster members, e.g. in the first cluster observed, Tr-37, a typical cluster for the YETI survey, there are at least 469 known young stars detected in YETI data down to R = 16.5 mag with sufficient precision of 50 millimag rms (5 mmag rms down to R = 14.5 mag) to detect transits, so that we can expect at least about one young transiting object in this cluster. If we observe ∼10 similar clusters, we can expect to detect ∼10 young transiting planets with radius determinations. The precision given above is for a typical telescope of the YETI network, namely the 60/90-cm Jena telescope (similar brightness limit, namely within ±1 mag, for the others) so that planetary transits can be detected. For targets with a periodic transit-like light curve, we obtain spectroscopy to ensure that the star is young and that the transiting object can be sub-stellar; then, we obtain Adaptive Optics infrared images and spectra, to exclude other bright eclipsing stars in the (larger) optical PSF; we carry out other observations as needed to rule out other false positive scenarios; finally, we also perform spectroscopy to determine the mass of the transiting companion. For planets with mass and radius determinations, we can calculate the mean density and probe the internal structure. We aim to constrain planet formation models and their time-scales by discovering planets younger than ∼100 Myr and determining not only their orbital parameters, but also measuring their true masses and radii, which is possible so far only by the transit method. Here, we present an overview and first results.
This article discusses the use of the General Health Questionnaire (GHQ‐12) in the Australian Defence Force (ADF), but comment pertaining to stress measurement and considerations for management are equally applicable to the paramilitary and other high‐risk professions. It is concluded that (a) prior to the widespread administration of a questionnaire designed to determine stress levels amongst ADF personnel, the defence research community should attempt to define stress in a conceptual, strategic, and operational fashion; (b) only after an optimal conceptual definition of stress has been operationalised can the defence research community attempt to accurately determine whether (and how) current stress levels are affecting the performance of personnel and begin to impart effective stress‐management techniques to those in need; and (c) no one measure can replace the GHQ, which in itself has been inappropriately applied to the ADF population in an attempt to measure the extent to which personnel experience the debilitating effects of physiological and psychological distress.
Experimental data of the first observed radiation induced transient changes to the bandwidth responses of an acousto optic (AO) Bragg device is reported. A brief description is presented of a procedure for measuring radiation induced transient changes to the first order diffracted beam and the zero order transmitted beam to determine the diffraction efficiencies of PbMoO4, Te02, and GaP AO deflectors and modulators. A brief analysis of the effects of radiation induced color centers and heating effects in a PbMoO4 AU Bragg device is presented. It was determined that a significant portion of the changes to the PbMoO4 swept frequency responses were due to radiation induced heating, and that radiation induced color center effects played a secondary role. Changes to the PbMoO4 diffraction efficiency were induced by CO2 laser heating of the PbMoO4 crystal. The laser induced changes correlated highly with electron induced changes indicating alteration of the acoustic diffraction grating which resulted in changes to the bandwidth and bandshape responses. The presence of thermally induced spatial index gradients across the aousto optic interaction region are believed responsible for these changes. INTRODUCTIONAcousto optic (AU) deflectors are critical components in high speed optical information processing and scanning applications. These technologies may find application in space based communication, sensing and optical processing systems. When operated in the spatial light modulator or scanning modes, parameters determined from the acousto optic interaction such as resolution, speed and bandwidth response are of paramount importance in system performance. In particular, the design of high performance AO deflectors requires stringent requirements of the diffraction efficiency, time aperture and bandwidth. Until just recently, very little was known about the effects of ionizing radiation affecting AU performance. The results of recent studies1'2'3 of radiation induced changes to AU device diffraction efficiencies and spatial intensities has revealed that these performance characteristics undergo transient degradation. This paper examines the consequences of exposing a Lead Molybdate (PbMoU4) AO Bragg cell operating in the longitudinal mode to ionizing electron radiation, and reports for the first time, changes to an AU deflector bandwidth and diffraction efficiency under dynamic conditions. The techniques first devised during this experiment were later applied to Tellurium Dioxide (TeU2) and Gallium 16 ISPIE Vol. 2482 O-8194-1835-8195/$6.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/27/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx
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