543 research outputs found

    Influence of Genetics on Disease Susceptibility and Progression

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    For many chronic diseases, the influence of genetics is complex and phenotypes do not conform to simpl

    Unusual Features of Varying Speed of Light Cosmologies

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    We contrast features of simple varying speed of light (VSL) cosmologies with inflationary universe models. We present new features of VSL cosmologies and show that they face problems explaining the cosmological isotropy problem. We also find that if c falls fast enough to solve the flatness and horizon problems then the quantum wavelengths of massive particle states and the radii of primordial black holes can grow to exceed the scale of the particle horizon. This may provide VSL cosmologies with a self-reproduction property. The constraint of entropy increase is also discussed. The new problems described in the this letter provide a set of bench tests for more sophisticated VSL theories to pass.Comment: expanded version, 12 page

    Field and laboratory validation of remote rover operations Science Team findings: The CanMars Mars Sample Return analogue mission

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    The CanMars Mars Sample Return Analogue Deployment (MSRAD) was a closely simulated, end-to-end Mars Sample Return (MSR) mission scenario, with instrumentation, goals, and constraints modeled on the upcoming NASA Mars 2020 rover mission; this paper reports on the post-mission validation of the exercise. The exercise utilized the CSA Mars Exploration Science Rover (MESR) rover, deployed to Utah, USA, at a Mars-analogue field site. The principal features of the field site located near Green River, Utah are Late Jurassic inverted, fluvial paleochannels, analogous to features on Mars in sites being considered for the ESA ExoMars rover mission and present within the chosen landing site for the Mars 2020 rover mission. The in-simulation (“in-sim”) mission operations team worked remotely from The University of Western Ontario, Canada. A suite of MESR-integrated and hand-held spectrometers was selected to mimic those of the Mars 2020 payload, and a Utah-based, on-site team was tasked with field operations to carry out the data collection and sampling as commanded by the in-sim team. As a validation of the in-sim mission science findings, the field team performed an independent geological assessment. This paper documents the field team's on-site geological assessment and subsequent laboratory and analytical results, then offers a comparison of mission (in-sim) and post-mission (laboratory) science results. The laboratory-based findings were largely consistent with the in-sim rover-derived data and geological interpretations, though some notable exceptions highlight the inherent difficulties in remote science. In some cases, available data was insufficient for lithologic identification given the absence of other important contextual information (e.g., textural information). This study suggests that the in-sim instruments were largely adequate for the Science Team to characterize samples; however, rover-based field work is necessarily hampered by mobility and time constraints with an obvious effect on efficiency but also precision, and to some extent, accuracy of the findings. The data show a dearth of preserved total organic carbon (TOC) – used as a proxy for ancient biosignature preservation potential – in the fluvial-lacustrine system of this field site, suggesting serious consideration with respect to the capabilities and opportunities for addressing the Mars exploration goals. We therefore suggest a thorough characterization of terrestrial sites analogous to those of Mars rover landing sites, and in-depth field studies like CanMars as important, pre-mission strategic exercises

    Fingertip force control during bimanual object lifting in hemiplegic cerebral palsy

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    In the present study we examined unimanual and bimanual fingertip force control during grasping in children with hemiplegic cerebral palsy (CP). Participants lifted, transported and released an object with one hand or both hands together in order to examine the effect on fingertip force control for each hand separately and to determine whether any benefit exists for the affected hand when it performed the task concurrently with the less-affected hand. Seven children with hemiplegic CP performed the task while their movement and fingertip force control were measured. In the bimanual conditions, the weight of the instrumented objects was equal or unequal. The durations of the all temporal phases for the less-affected hand were prolonged during bimanual control compared to unimanual control. We observed close synchrony of both hands when the task was performed with both hands, despite large differences in duration between both hands when they performed separately. There was a marginal benefit for two of the five force related variables for the affected hand (grip force at onset of load force, and peak grip force) when it transported the object simultaneously with the less-affected hand. Collectively, these results corroborate earlier findings of reaching studies that showed slowing down of the less-affected hand when it moved together with the affected hand. A new finding that extends these studies is that bimanual tasks may have the potential to facilitate force control of the affected hand. The implications of these findings for recent rehabilitative therapies in children with CP that make use of bimanual training are discussed
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