581 research outputs found

    Integrated medical and behavioral laboratory measurement system engineering analysis and laboratory specification

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    Site selection, program planning, cost and design studies for support of the IMBLMS program were investigated. Accomplishments are reported for the following areas: analysis of responses to site selection criteria, space-oriented biotechnology, life sciences payload definition, and program information transfer

    Treatment of avoidant/restrictive food intake disorder: a systematic review

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    Objective: This study aimed to conduct a systematic review on the effects of available treatments for avoidant/restrictive food intake disorder (ARFID). Methods: Literature searches, study selection, method development, and quality appraisal were performed independently by one author, and data were synthesized using a narrative approach. Studies published in English and in peer-reviewed journals that evaluated the outcomes of ARFID treatments in at least three participants were taken into consideration, while non-original studies, editorials and letters to the editor were excluded. Results: The review had three main findings. First, in all of the studies by the end of the treatment there was a significant weight gain in the ARFID participants. Second, weight recovery was maintained at follow-up in a good percentage of participants with an associated improvement of eating behavior and a reduction in anxiety, depression, and fear for the adverse consequences of eating. Third, there was weak or missing evidence regarding the treatment of ARFID in adults and the difference in outcome in the three different ARFID profiles. Eighteen studies were selected and eleven were included. Conclusion: The treatments for ARFID, although promising, have focused only on young participants and addressed the normalization of eating with behavioral procedures, but not the underlying psychopathology. Moreover, the lack of randomized controlled trials with adequate statistical power does not allow to draw conclusions on the difference in the effectiveness of the interventions tested

    Preliminary observations on the mandibles of palaemonoid shrimp (Crustacea: Decapoda: Caridea: Palaemonoidea)

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    The mandibles of caridean shrimps have been widely studied in the taxonomy and functional biology of the group. Within the Palaemonoidea the mandibles reach a high level of structural diversity reflecting the diverse lifestyles within the superfamily. However, the majority of studies have been restricted to light microscopy, with the ultrastructure at finer levels poorly known. This study investigates the mandible of nine species belonging to six of the recognised families of the Palaemonoidea using SEM and analyses the results in a phylogenetic and dietary framework. The results of the study indicate that little phylogenetic information is conveyed by the structure of the mandible, but that its form is influenced by primary food sources of each species. With the exception of Anchistioides antiguensis, all species examined possessed cuticular structures at the distal end of the pars molaris (molar process). Five types of cuticular structures are recognised herein, each with a unique form, but variable in number, placement and arrangement. Each type is presumed to have a different function which is likewise related to diet

    The spin temperature of high-redshift damped Lyman-α\alpha systems

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    We report results from a programme aimed at investigating the temperature of neutral gas in high-redshift damped Lyman-α\alpha absorbers (DLAs). This involved (1) HI 21cm absorption studies of a large DLA sample, (2) VLBI studies to measure the low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy to determine DLA metallicities and velocity widths. Including literature data, our sample consists of 37 DLAs with estimates of the spin temperature TsT_s and the covering factor. We find a strong 4σ4\sigma) difference between the TsT_s distributions in high-z (z>2.4) and low-z (z<2.4) DLA samples. The high-z sample contains more systems with high TsT_s values, 1000\gtrsim 1000 K. The TsT_s distributions in DLAs and the Galaxy are also clearly (~6σ6\sigma) different, with more high-TsT_s sightlines in DLAs than in the Milky Way. The high TsT_s values in the high-z DLAs of our sample arise due to low fractions of the cold neutral medium. For 29 DLAs with metallicity [Z/H] estimates, we confirm the presence of an anti-correlation between TsT_s and [Z/H], at 3.5σ3.5\sigma significance via a non-parametric Kendall-tau test. This result was obtained with the assumption that the DLA covering factor is equal to the core fraction. Monte Carlo simulations show that the significance of the result is only marginally decreased if the covering factor and the core fraction are uncorrelated, or if there is a random error in the inferred covering factor. We also find evidence for redshift evolution in DLA TsT_s values even for the z>1 sub-sample. Since z>1 DLAs have angular diameter distances comparable to or larger than those of the background quasars, they have similar efficiency in covering the quasars. Low covering factors in high-z DLAs thus cannot account for the observed redshift evolution in spin temperatures. (Abstract abridged.)Comment: 37 pages, 22 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

    ENERGÍA CINÉTICA PRODUCIDA EN FOTOELECTRONES DE CU INDUCIDO POR FOTONES DE ALTA ENERGÍA DE LA LUZ

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    El efecto fotoeléctrico en el cobre ha sido estudiado desde distintos ámbitos alterando cualquiera de sus propiedades. Para este estudio en particular el cobre se considera en su estado natural y contemplando la función de trabajo del metal se propusieron 5 escenarios de estudio en los que se varía la frecuencia de onda de la luz para analizar y cuantificar la energía cinética en los fotoelectrones emitidos. Analíticamente se obtuvieron los valores para cada caso de estudio y numéricamente se generaron gráficas en las que se observa el comportamiento de la energía cinética frente a la frecuencia y longitud de onda inducidas. El espectro electromagnético UV es el último en el que se puede presentar el efecto fotoeléctrico en el Cu, el valor obtenido es de 4.562 〖 X10 〗 ^(-17) J y representa la menor energía cinética generada en los fotoelectrones mientras que 6.625 〖 X10 〗 ^(-10) J es el valor máximo en radiación gamma (γ).

    Is Mislocalization during saccades related to the position of the saccade target within the image or to the gaze position at the end of the saccade?

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    A stimulus that is flashed around the time of a saccade tends to be mislocalized in the direction of the saccade target. Our question is whether the mislocalization is related to the position of the saccade target within the image or to the gaze position at the end of the saccade. We separated the two with a visual illusion that influences the perceived distance to the target of the saccade and thus saccade endpoint without affecting the perceived position of the saccade target within the image. We asked participants to make horizontal saccades from the left to the right end of the shaft of a Müller-Lyer figure. Around the time of the saccade, we flashed a bar at one of five possible positions and asked participants to indicate its location by touching the screen. As expected, participants made shorter saccades along the fins-in (<->) configuration than along the fins-out (>-<) configuration of the figure. The illusion also influenced the mislocalization pattern during saccades, with flashes presented with the fins-out configuration being perceived beyond flashes presented with the fins-in configuration. The difference between the patterns of mislocalization for bars flashed during the saccade for the two configurations corresponded quantitatively with a prediction based on compression towards the saccade endpoint considering the magnitude of the effect of the illusion on saccade amplitude. We conclude that mislocalization is related to the eye position at the end of the saccade, rather than to the position of the saccade target within the image

    Interactive seminars or small group tutorials in preclinical medical education: results of a randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Learning in small group tutorials is appreciated by students and effective in the acquisition of clinical problem-solving skills but poses financial and resource challenges. Interactive seminars, which accommodate large groups, might be an alternative. This study examines the educational effectiveness of small group tutorials and interactive seminars and students' preferences for and satisfaction with these formats.</p> <p>Methods</p> <p>Students in year three of the Leiden undergraduate medical curriculum, who agreed to participate in a randomized controlled trial (RCT, n = 107), were randomly allocated to small group tutorials (n = 53) or interactive seminars (n = 54). Students who did not agree were free to choose either format (n = 105). Educational effectiveness was measured by comparing the participants' results on the end-of-block test. Data on students' reasons and satisfaction were collected by means of questionnaires. Data was analyzed using student unpaired t test or chi-square test where appropriate.</p> <p>Results</p> <p>There were no significant differences between the two educational formats in students' test grades. Retention of knowledge through active participation was the most frequently cited reason for preferring small group tutorials, while a dislike of compulsory course components was mentioned more frequently by students preferring interactive seminars. Small group tutorials led to greater satisfaction.</p> <p>Conclusions</p> <p>We found that small group tutorials leads to greater satisfaction but not to better learning results. Interactive learning in large groups might be might be an effective alternative to small group tutorials in some cases and be offered as an option.</p

    Carbon Nanotubes by a CVD Method. Part I: Synthesis and Characterization of the (Mg, Fe)O Catalysts

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    The controlled synthesis of carbon nanotubes by chemical vapor deposition requires tailored and wellcharacterized catalyst materials. We attempted to synthesize Mg1-xFexO oxide solid solutions by the combustion route, with the aim of performing a detailed investigation of the influence of the synthesis conditions (nitrate/urea ratio and the iron content) on the valency and distribution of the iron ions and phases. Notably, characterization of the catalyst materials is performed using 57Fe Mo¨ssbauer spectroscopy, X-ray diffraction, and electron microscopy. Several iron species are detected including Fe2+ ions substituting for Mg2+ in the MgO lattice, Fe3+ ions dispersed in the octahedral sites of MgO, different clusters of Fe3+ ions, and MgFe2O4-like nanoparticles. The dispersion of these species and the microstructure of the oxides are discussed. Powders markedly different from one another that may serve as model systems for further study are identified. The formation of carbon nanotubes upon reduction in a H2/CH4 gas atmosphere of the selected powders is reported in a companion paper

    Non-Invasive Estimation of Local Field Potentials for Neuroprosthesis Control

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    Recent experiments have shown the possibility to use the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions; i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using different number of electrodes
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