511 research outputs found

    Proceedings of the 2003 Winter Simulation Conference

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    In this paper we have applied an interval representation of time to represent and reason about activities, events, actions and situations relevant to the construction domain. The first part of the paper formally defines the situational simulation environment and develops a set of temporal axioms which can be used to 1) Express precedence constraints between time intervals and 2) Capture the causal relationships between actions and events. The second part of the paper looks at an agent reasoning mechanism used to perceive and predict actions and foresee future consequences of present actions within the simulation environment. Agent reasoning is based on awareness derived from a knowledge base of facts which captures the causal nature of events in the construction management domain

    Discovery of the Optical Transient of the Gamma Ray Burst 990308

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    The optical transient of the faint Gamma Ray Burst 990308 was detected by the QUEST camera on the Venezuelan 1-m Schmidt telescope starting 3.28 hours after the burst. Our photometry gives V=18.32±0.07V = 18.32 \pm 0.07, R=18.14±0.06R = 18.14 \pm 0.06, B=18.65±0.23B = 18.65 \pm 0.23, and R=18.22±0.05R = 18.22 \pm 0.05 for times ranging from 3.28 to 3.47 hours after the burst. The colors correspond to a spectral slope of close to fνν1/3f_{\nu} \propto \nu^{1/3}. Within the standard synchrotron fireball model, this requires that the external medium be less dense than 104cm310^{4} cm^{-3}, the electrons contain >20> 20% of the shock energy, and the magnetic field energy must be less than 24% of the energy in the electrons for normal interstellar or circumstellar densities. We also report upper limits of V>12.0V > 12.0 at 132 s (with LOTIS), V>13.4V > 13.4 from 132-1029s (with LOTIS), V>15.3V > 15.3 at 28.2 min (with Super-LOTIS), and a 8.5 GHz flux of <114μJy< 114 \mu Jy at 110 days (with the Very Large Array). WIYN 3.5-m and Keck 10-m telescopes reveal this location to be empty of any host galaxy to R>25.7R > 25.7 and K>23.3K > 23.3. The lack of a host galaxy likely implies that it is either substantially subluminous or more distant than a red shift of 1.2\sim 1.2.Comment: ApJ Lett submitted, 5 pages, 2 figures, no space for 12 coauthor

    TNOs are Cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel PACS observations

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    We present Herschel PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling. We analyze our results for correlations, draw conclusions on the Plutino size distribution, and compare to earlier results. Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods. In order to improve the quality of our results, we combine our PACS data with existing Spitzer MIPS data where possible, and refine existing absolute magnitudes for the targets. The physical characterization of our sample is done using a thermal model. Uncertainties of the physical parameters are derived using customized Monte Carlo methods. The correlation analysis is performed using a bootstrap Spearman rank analysis. We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28. The average albedo of the sample is 0.08 \pm 0.03, which is comparable to the mean albedo of Centaurs, Jupiter Family comets and other Trans-Neptunian Objects. We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the bulk density of 1999 TC36 and find a density of 0.64 (+0.15/-0.11) g cm-3. On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo. Furthermore, we find biases based on geometrical aspects and color in our sample. There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample.Comment: 18 pages, 8 figures, 8 tables, accepted for publication in A&

    The management of ADHD in children and adolescents: bringing evidence to the clinic: perspective from the European ADHD Guidelines Group (EAGG)

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    ADHD is the most common neurodevelopmental disorder presenting to child and adolescent mental health, paediatric, and primary care services. Timely and effective interventions to address core ADHD symptoms and co-occurring problems are a high priority for healthcare and society more widely. While much research has reported on the benefits and adverse effects of different interventions for ADHD, these individual research reports and the reviews, meta-analyses and guidelines summarizing their findings are sometimes inconsistent and difficult to interpret. We have summarized the current evidence and identified several methodological issues and gaps in the current evidence that we believe are important for clinicians to consider when evaluating the evidence and making treatment decisions. These include understanding potential impact of bias such as inadequate blinding and selection bias on study outcomes; the relative lack of high-quality data comparing different treatments and assessing long-term effectiveness, adverse effects and safety for both pharmacological and non-pharmacological treatments; and the problems associated with observational studies, including those based on large national registries and comparing treatments with each other. We highlight key similarities across current international clinical guidelines and discuss the reasons for divergence where these occur. We discuss the integration of these different perspective into a framework for person/family-centered evidence-based practice approach to care that aims to achieve optimal outcomes that prioritize individual strengths and impairments, as well as the personal treatment targets of children and their families. Finally, we consider how access to care for this common and impairing disorder can be improved in different healthcare systems
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