29,814 research outputs found

    Improved electro-optical tracking system

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    Electro-optical tracking system employs a laser beam illuminating source, an electronic laser beam deflector, and an image dissector photomultiplier. An electronic scanning transmitter and receiver follows rapid movements or accelerations of the target

    From GM Law to A Powerful Mean Field Scheme

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    A new and powerful mean field scheme is presented. It maps to a one-dimensional finite closed chain in an external field. The chain size accounts for lattice topologies. Moreover lattice connectivity is rescaled according to the GM law recently obtained in percolation theory. The associated self-consistent mean-field equation of state yields critical temperatures which are within a few percent of exact estimates. Results are obtained for a large variety of lattices and dimensions. The Ising lower critical dimension for the onset of phase transitions is dl=1+2qd_l=1+\frac{2}{q}. For the Ising hypercube it becomes the Golden number dl=1+52d_l=\frac{1+\sqrt 5}{2}. The scheme recovers the exact result of no long range order for non-zero temperature Ising triangular antiferromagnets.Comment: 3M Conference Proceedings, San Jose, California (November, 1999

    Robust Hypothesis Tests for Detecting Statistical Evidence of 2D and 3D Interactions in Single-Molecule Measurements

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    A variety of experimental techniques have improved the 2D and 3D spatial resolution that can be extracted from \emph{in vivo} single-molecule measurements. This enables researchers to quantitatively infer the magnitude and directionality of forces experienced by biomolecules in their native cellular environments. Situations where such forces are biologically relevant range from mitosis to directed transport of protein cargo along cytoskeletal structures. Models commonly applied to quantify single-molecule dynamics assume that effective forces and velocity in the x,yx,y (or x,y,zx,y,z) directions are statistically independent, but this assumption is physically unrealistic in many situations. We present a hypothesis testing approach capable of determining if there is evidence of statistical dependence between positional coordinates in experimentally measured trajectories; if the hypothesis of independence between spatial coordinates is rejected, then a new model accounting for 2D (3D) interactions should be considered to more faithfully represent the underlying experimental kinetics. The technique is robust in the sense that 2D (3D) interactions can be detected via statistical hypothesis testing even if there is substantial inconsistency between the physical particle's actual noise sources and the simplified model's assumed noise structure. For example, 2D (3D) interactions can be reliably detected even if the researcher assumes normal diffusion, but the experimental data experiences "anomalous diffusion" and/or is subjected to a measurement noise characterized by a distribution differing from that assumed by the fitted model. The approach is demonstrated on control simulations and on experimental data (IFT88 directed transport in the primary cilium).Comment: 7 pages, 6 figure

    Resolving the Uncertainty of Preterm Symptoms: Women’s Experiences With the Onset of Preterm Labor

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    Objective: To describe expectant women\u27s experiences with the onset of preterm labor. Design: Qualitative, using grounded theory methods. Setting: Southwestern tertiary women\u27s hospital. Participants: Thirty pregnant women who were less than 35 weeks gestation, had experienced preterm labor within the past 7 days, and had no previous experience with preterm labor. Data Source: Taped and transcribed interviews. Results: Themes that emerged from the interview data included the following: recognition and naming of sensations, a consistent pattern of attribution of symptoms, the threat or risk inferred by the attributed cause of the symptom pattern, the associated certainty or uncertainty about these attributions, the process of interpreting and verifying symptom meaning, and the decision to self-manage the symptoms or engage health care assistance. The core process of women experiencing the onset of preterm labor symptoms was identified as resolving the uncertainty of preterm labor symptoms: recognizing and responding to the possibilities. Conclusions: Preterm labor often is not within expectant women\u27s consciousness. They may attribute the symptoms to nonthreatening causes, which results in delays in seeking care for preterm labor. Education about symptom patterns at the onset of preterm labor will increase the probability that women and their health care providers will recognize and interpret the early, subtle symptoms that herald the onset of preterm labor. Uncertainty in illness theory and attribution theory offer frameworks for understanding women\u27s experiences with the onset of preterm labor

    The extensive nature of group quality

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    We consider groups of interacting nodes engaged in an activity as many-body, complex systems and analyse their cooperative behaviour from a mean-field point of view. We show that inter-nodal interactions rather than accumulated individual node strengths dominate the quality of group activity, and give rise to phenomena akin to phase transitions, where the extensive relationship between group quality and quantity reduces. The theory is tested using empirical data on quantity and quality of scientific research groups, for which critical masses are determined.Comment: 6 pages, 6 figures containing 13 plots. Very minor changes to coincide with published versio

    Reaction of the chick to one atmosphere of oxygen

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    Experiment to determine chicken reaction to 100 percent oxygen at atmospheric pressur

    Embryo development and chick growth in a helium - oxygen atmosphere

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    Embryo development and chick growth in helium- oxygen atmospher
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