2,499 research outputs found

    Exploring the movement dynamics of deception

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    Both the science and the everyday practice of detecting a lie rest on the same assumption: hidden cognitive states that the liar would like to remain hidden nevertheless influence observable behavior. This assumption has good evidence. The insights of professional interrogators, anecdotal evidence, and body language textbooks have all built up a sizeable catalog of non-verbal cues that have been claimed to distinguish deceptive and truthful behavior. Typically, these cues are discrete, individual behaviors—a hand touching a mouth, the rise of a brow—that distinguish lies from truths solely in terms of their frequency or duration. Research to date has failed to establish any of these non-verbal cues as a reliable marker of deception. Here we argue that perhaps this is because simple tallies of behavior can miss out on the rich but subtle organization of behavior as it unfolds over time. Research in cognitive science from a dynamical systems perspective has shown that behavior is structured across multiple timescales, with more or less regularity and structure. Using tools that are sensitive to these dynamics, we analyzed body motion data from an experiment that put participants in a realistic situation of choosing, or not, to lie to an experimenter. Our analyses indicate that when being deceptive, continuous fluctuations of movement in the upper face, and somewhat in the arms, are characterized by dynamical properties of less stability, but greater complexity. For the upper face, these distinctions are present despite no apparent differences in the overall amount of movement between deception and truth. We suggest that these unique dynamical signatures of motion are indicative of both the cognitive demands inherent to deception and the need to respond adaptively in a social context

    Health effect assessment of vinyl chloride in the environment

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    Prva četiri slučaja angiosarkoma jetre u radnika zaposlenih u tvornici vinilklorida opisana su 1974. godine. Taj je izvještaj privukao pažnju svjetske javnosti i potakao brojna retrospektivna epidemiološka istraživanja među radnicima zaposlenim u industriji vinilklorida, kao i čitav niz klasičnih farmakokinetskih i toksikoloških studija na eksperimentalnim životinjama. Namjera ovog prikaza je da sažme raspoložive znanstvene podatke o izloženosti, farmakokinetici i toksikologiji vinilklorida. Posebna je pažnja posvećena procjeni opasnosti po zdravlje stanovništva od zagađenja okoline vinilkloridom.The first four cases of liver angiosarcoma in workers employed in a vinyl chloride plant were reported in 1974. This initial report attracted worldwide attention. It spurred a flurry of retrospective epidemiologic investigations of workers in the vinyl chloride industry, and led to a classical pharrnacokinetic and toxicologic studies in animals. The purpose of this paper is to summarize the large volume of published literature on the exposure, pharmacokinetics and toxicology of vinyl chloride. Inhalation of vinyl chloride is the principal route of exposure to people working in or living near vinyl chloride industries, as this compound is a gas at normal atmospheric temperatures and pressures. The average exposure of a person chosen at random living within a 5-mile radius from vinyl chloride and polyvinyl chloride plants was calculated to be 17 ppb. It is considered that the exposure levels and associated risk to man from vinyl chloride contaminated water supplies or food is small in comparison to exposure by inhalation. Vinyl chloride is rapidly absorbed through the lungs. Its fate and absorption after oral administration are consistent with observations derived from inhalation studies. It ds extensively metabolized and the metabolic pathway appears to be saturable by exposures to concentrations exceeding 220 ppm. The excretion of vinyl chloride or its metabolites is rapid. The predominant route of excretion for non-metabolized vinyl chloride is through the lungs (at higher levels of exposure), and for its metabolites in the urine, Tumors at multiple and diverse sites have been observed in all species of experimental animals tested for carcinogenicity by inhalation and ingestion of vinyl chloride. Liver angiosarcoma have been observed in two species of experimental animals after inhalation exposure to vinyl chloride, at the lowest dose tested, 50 ppm, and after exposure by ingestion, at 16 mg/kg. In this paper special attention is given to the human health risk assessment associated with vinyl chloride contaminated environment

    Adaptive Lévy processes and area-restricted search in human foraging

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    A considerable amount of research has claimed that animals’ foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods–comparing alternative distributions using maximum likelihood methods–showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments–where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources–as both patched and dispersed conditions led to similar Lévy-like movement distributions

    The Structure of Phonological Networks Across Multiple Languages

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    The network characteristics based on the phonological similarities in the lexicons of several languages were examined. These languages differed widely in their history and linguistic structure, but commonalities in the network characteristics were observed. These networks were also found to be different from other networks studied in the literature. The properties of these networks suggest explanations for various aspects of linguistic processing and hint at deeper organization within human language.Comment: 5 pages, 3 figures, 2 tables, submitted to Phys. Rev.

    The impact of incorporating surgical simulation into trichiasis surgery training on operative aspects of initial live-training surgeries

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    BACKGROUND: While surgical simulation is regularly used in surgical training in high-income country settings, it is uncommon in low- and middle-income countries, particularly for surgical training that primarily occurs in rural areas. We designed and evaluated a novel surgical simulator for improving trachomatous trichiasis (TT) surgery training, given that trichiasis is mostly found among the poorest individuals in rural areas. METHODOLOGY/PRINCIPAL FINDINGS: TT surgery programs were invited to incorporate surgical simulation with a new, high fidelity, low-cost simulator into their training. Trainees completed standard TT-surgery training following World Health Organization guidelines. A subset of trainees received three hours of supplemental training with the simulator between classroom and live-surgery training. We recorded the time required to complete each surgery and the number of times the trainer intervened to correct surgical steps. Participants completed questionnaires regarding their perceptions. We also assessed trainer and trainee perceptions of surgical simulation training as part of trichiasis surgery training. 22 surgeons completed standard training and 26 completed standard training plus simulation. We observed 1,394 live-training surgeries. Average time to first live-training surgery completion was nearly 20% shorter the simulation versus the standard group (28.3 vs 34.4 minutes; p = 0.02). Trainers intervened significantly fewer times during initial live-training surgeries in the simulation group (2.7 vs. 4.8; p = 0.005). All trainers indicated the simulator significantly improved training by allowing trainees to practice safely and to identify problem areas before performing live-training surgeries. Trainees reported that simulation practice improved their confidence and skills prior to performing live-training surgeries. CONCLUSIONS: A single high-fidelity surgical simulation session can significantly improve critical aspects of initial TT surgeries
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