17,709 research outputs found

    Testing An Identification Algorithm for Extragalactic OB Associations Using a Galactic Sample

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    We have used a Galactic sample of OB stars and associations to test the performance of an automatic grouping algorithm designed to identify extragalactic OB associations. The algorithm identifies the known Galactic OB associations correctly when the search radius (78 pc) is defined by the observed stellar surface density. Galactic OB associations identified with a 78 pc search radius have diameters that are ∼\sim3 times larger than OB associations identified with a 22 pc search radius in M33. Applying the smaller search radius to the Galactic data matches both the sizes and the number of member stars between the two galaxies quite well. Thus, we argue that this and similar algorithms should be used with a constant physical search radius, rather than one which varies with the stellar surface density. Such an approach would allow the identification of differences in the giant molecular cloud populations and star formation efficiency under most circumstances.Comment: accepted to AJ; 16 pages, aas latex, 9 postscript figures; available at http://www.physics.mcmaster.ca/Wilson_Preprints/index.htm

    A Short Wavelength GigaHertz Clocked Fiber-Optic Quantum Key Distribution System

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    A quantum key distribution system has been developed, using standard telecommunications optical fiber, which is capable of operating at clock rates of greater than 1 GHz. The quantum key distribution system implements a polarization encoded version of the B92 protocol. The system employs vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, and silicon single photon avalanche diodes as the single photon detectors. A distributed feedback laser of emission wavelength 1.3 micro-metres, and a linear gain germanium avalanche photodiode was used to optically synchronize individual photons over the standard telecommunications fiber. The quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-per-second for a 4.2 km transmission range. For a 10 km fiber range a quantum bit error rate of 2.1%, and estimated net bit rate of greater than 7,000 bits-per-second was achieved.Comment: Pre-press versio

    The October 27-28, 1986, FIRE cirrus case study: Cloud microstructure

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    Using aircraft in-situ measurements, the microphysics of cirrus clouds observed on 28 Oct. 1986 during FIRE were examined. Results are presented as one component of a coordinated study of the cirrus on the day. The study contributes to the understanding of cold clouds by: (1) providing microphysical data to supplement satellite and aircraft data for investigating cirrus cloud radiative effects; (2) providing more complete information on ice particle evolution and cloud forcing mechanisms than has been available through the use of instrumentation with higher resolution and more accurate calibration; (3) expanding the knowledge of the particle characteristics in cold liquid water clouds, through improved instrumentation and by making use of sensors on other platforms, such as lidar; and (4) by estimating the ice nucleus concentrations active at low temperatures in the upper troposphere from the concentrations of ice particles in colloidally stable liquid water clouds

    Buy High Sell Low: Redefining Bean Counting in the Coffee Industry for a Sustainable Future

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    Charles Manz returns to the JVBL providing ‒ together with several fellow researchers/writers ‒ a case study of a socially responsible business within the coffee industry. Familiar CSR concepts are examined such as Fair Trade and sustainability which foster parity in dealing with buyers while maintaining product quality and reasonable income. The practices of Dean’s Beans, a progressive coffee organization, are examined as a notable demonstration of how a business can fiscally succeed while maintaining a commitment to the triple-bottom-line considerations of people, planet, and profits

    3.3 Gigahertz Clocked Quantum Key Distribution System

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    A fibre-based quantum key distribution system operating up to a clock frequency of 3.3GHz is presented. The system demonstrates significantly increased key exchange rate potential and operates at a wavelength of 850nm.Comment: Presented at ECOC 05, Glasgow, UK, (September 2005

    Characterizing 15 Years of Saharan-like, Dry, Well-Mixed Air Layers in North Africa

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    The Saharan Air Layer (SAL) is a dry, well-mixed layer (WML) of warm and sometimes dusty air of nearly constant water vapor mixing ratio generated by the intense surface heating and strong, dry convection in the Sahara Desert, which has notable downstream impacts on the surface energy balance, organized convective system development, seasonal precipitation, and air quality. Characterizing both WMLs and SALs from the existing rawinsonde network has proven challenging because of its sparseness and inconsistent data reporting. Spurred on by this challenge, we previously created a detection methodology and supporting software to automate the identification and characterization of WMLs from multiple data sources including rawinsondes, remote sensing platforms, and model products. We applied our algorithm to each dataset at both its native and at a common (most coarse data product) vertical resolution to detect WMLs and their characteristics (temperature, mixing ratio, AOD, etc.) at each of the 53 rawinsonde launch sites in north Africa

    Reducing parental anxiety using a family based intervention for youth mental health : a randomized controlled trial

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    This paper presents findings on parent anxiety and attachment relationship style from the Deakin Family Options (DFO) pilot study, a randomized controlled pilot study comparing a family-based treatment (BEST Plus), versus a youth only treatment (CBT) versus a group who received both of these treatments (COMBINED). Eligible participants were families with a young person (aged 12 - 25 years) with a high prevalence mental health problem. Youth from participating families scored in the clinical or subclinical range for depression, anxiety and/or substance misuse symptoms on standardized measures during the initial assessment. The collected sample was drawn from regional and urban centers in Victoria, Australia and allocated to treatment condition using a simple randomization procedure (parallel design). It was hypothesized that families receiving the BEST Plus would experience greater reductions in youth and parent mental health symptoms, and improved parent-child relationships, compared with those in the CBT condition. This paper describes and discusses changes in parent anxiety and parent attachment, according to whether the parent participated in a treatment (BEST Plus) or did not (NONBEST Plus). Participants were blind to the study hypotheses. In total 71 parent participants returned pre data and were allocated to a treatment group. In this paper, data from parent participants who completed pre and post measures (n = 48) and pre, post, and 6-month follow-up measures (n = 28) on anxiety and attachment were analyzed by group (BEST Plus versus NONBEST Plus). The results of this study suggest that parent anxiety decreased significantly more following parent involvement in a group treatment, than for parents that did not receive treatment. Unexpectedly, avoidant attachment increased in the no treatment group, but remained relatively stable following the BEST Plus group. There were no significant findings in relation to compulsive traits and anxious attachment. These findings are discussed in light of the study limitations.<br /
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