245 research outputs found

    Simulated Diabetes Testing Experiment Using Artificially Manipulated Livestock Blood

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    Due to the prevalence of diabetes and lack of simple endocrine experiments, a laboratory protocol was developed in order to increase student knowledge of the disease and the diabetic testing process. In this paper, we present the protocol for manipulating the glucose concentration of commercially available bovine blood. The bovine blood was manipulated using Ringer's solution to which glucose was added, and six samples were prepared (pre-prandial and postprandial, normal; pre-prandial and postprandial, pre-diabetic; pre-prandial and postprandial, diabetic). This laboratory exercise provides a physical, hands-on student activity that highlights pancreatic endocrinology and the results of pancreatic malfunction. The laboratory exercise is relatively inexpensive and can be performed in under an hour. Students in Human Anatomy and Physiology II performed the experiment using glucose meters. When tested, the blood samples’ glucose readings were consistently within the desired ranges. The post-laboratory questions were designed to assess student knowledge of diabetes upon completion of the experiment. The students also completed a pre-laboratory and post-laboratory survey, and these results were also recorded and tabulated. Upon completion, the majority of students (164 of 209) reported an increase in knowledge concerning diabetes. An overwhelming majority (190 of 209) of the students enjoyed the laboratory exercise. Bovine blood was used in the experiment to ensure realism, and 194 of the students believed that this experiment was realistic given the constraints (i.e., using simulated blood). Due to student results and survey answers, it was deduced that this laboratory exercise was successful

    Global fits to neutrino oscillation data

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    I summarize the determination of neutrino oscillation parameters within the three-flavor framework from world neutrino oscillation data with date of May 2006, including the first results from the MINOS long-baseline experiment. It is illustrated how the determination of the leading "solar" and "atmospheric" parameters, as well as the bound on θ13\theta_{13} emerge from an interplay of various complementary data sets. Furthermore, I discuss possible implications of sub-leading three-flavor effects in present atmospheric neutrino data induced by Δm212\Delta m^2_{21} and θ13\theta_{13} for the bound on θ13\theta_{13} and non-maximal values of θ23\theta_{23}, emphasizing, however, that these effects are not statistically significant at present. Finally, in view of the upcoming MiniBooNE results I briefly comment on the problem to reconcile the LSND signal.Comment: 5 pages, 5 figures, talk presented at the SNOW2006 workshop, Stockholm, 2-6 May 200

    Optimal Image Reconstruction in Radio Interferometry

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    We introduce a method for analyzing radio interferometry data which produces maps which are optimal in the Bayesian sense of maximum posterior probability density, given certain prior assumptions. It is similar to maximum entropy techniques, but with an exact accounting of the multiplicity instead of the usual approximation involving Stirling's formula. It also incorporates an Occam factor, automatically limiting the effective amount of detail in the map to that justified by the data. We use Gibbs sampling to determine, to any desired degree of accuracy, the multi-dimensional posterior density distribution. From this we can construct a mean posterior map and other measures of the posterior density, including confidence limits on any well-defined function of the posterior map.Comment: 41 pages, 11 figures. High resolution figures 8 and 9 available at http://www.astro.uiuc.edu/~bwandelt/SuttonWandelt200

    LOTIS Upper Limits and the Prompt OT from GRB 990123

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    GRB 990123 established the existence of prompt optical emission from gamma-ray bursts (GRBs). The Livermore Optical Transient Imaging System (LOTIS) has been conducting a fully automated search for this kind of simultaneous low energy emission from GRBs since October 1996. Although LOTIS has obtained simultaneous, or near simultaneous, coverage of the error boxes obtained with BATSE, IPN, XTE, and BeppoSAX for several GRBs, image analysis resulted in only upper limits. The unique gamma-ray properties of GRB 990123, such as very large fluence (top 0.4%) and hard spectrum, complicate comparisons with more typical bursts. We scale and compare gamma-ray properties, and in some cases afterglow properties, from the best LOTIS events to those of GRB 990123 in an attempt to determine whether the prompt optical emission of this event is representative of all GRBs. Furthermore, using LOTIS upper limits in conjunction with the relativistic blast wave model, we weakly constrain the GRB and afterglow parameters such as density of the circumburster medium and bulk Lorentz factor of the ejecta.Comment: 5 pages, 2 figures, To appear in Proceedings of the 5th Huntsville Gamma-Ray Burst Symposiu

    Multi-Frequency Synthesis of VLBI Images Using a Generalized Maximum Entropy Method

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    A new multi-frequency synthesis algorithm for reconstructing images from multi-frequency VLBI data is proposed. The algorithm is based on a generalized maximum-entropy method, and makes it possible to derive an effective spectral correction for images over a broad frequency bandwidth, while simultaneously reconstructing the spectral-index distribution over the source. The results of numerical simulations demonstrating the capabilities of the algorithm are presented.Comment: 17 pages, 8 figure

    Future Precision Neutrino Oscillation Experiments and Theoretical Implications

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    Future neutrino oscillation experiments will lead to precision measurements of neutrino mass splittings and mixings. The flavour structure of the lepton sector will therefore at some point become better known than that of the quark sector. This article discusses the potential of future oscillation experiments on the basis of detailed simulations with an emphasis on experiments which can be done in about ten years. In addition, some theoretical implications for neutrino mass models will be briefly discussed.Comment: Talk given at Nobel Symposium 2004: Neutrino Physics, Haga Slott, Enkoping, Sweden, 19-24 Aug 200

    LOTIS Search for Early Time Optical Afterglows: GRB 971227

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    We report on the very early time search for an optical afterglow from GRB 971227 with the Livermore Optical Transient Imaging System (LOTIS). LOTIS began imaging the `Original' BATSE error box of GRB 971227 approximately 14 s after the onset of gamma-ray emission. Continuous monitoring of the position throughout the evening yielded a total of 499 images (10 s integration). Analysis of these images revealed no steady optical afterglow brighter than R=12.3 +- 0.2 in any single image. Coaddition of different combinations of the LOTIS images also failed to uncover transient optical emission. In particular, assuming a constant early time flux, no optical afterglow brighter than R=14.2 +- 0.2 was present within the first 1200 s and no optical afterglow brighter than R=15.0 +- 0.2 was present in the first 6.0 h. Follow up observations by other groups revealed a likely X-ray afterglow and a possible optical afterglow. Although subsequent deeper observations could not confirm a fading source, we show that these transients are not inconsistent with our present knowledge of the characteristics of GRB afterglows. We also demonstrate that with the upgraded thermoelectrically cooled CCDs, LOTIS is capable of either detecting very early time optical afterglow or placing stringent constraints on the relationship between the gamma-ray emission and the longer wavelength afterglow in relativistic blast wave models.Comment: 17 pages, 3 eps figures, revisions based on reviewers comment
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