1,910 research outputs found

    Aerial-Ground collaborative sensing: Third-Person view for teleoperation

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    Rapid deployment and operation are key requirements in time critical application, such as Search and Rescue (SaR). Efficiently teleoperated ground robots can support first-responders in such situations. However, first-person view teleoperation is sub-optimal in difficult terrains, while a third-person perspective can drastically increase teleoperation performance. Here, we propose a Micro Aerial Vehicle (MAV)-based system that can autonomously provide third-person perspective to ground robots. While our approach is based on local visual servoing, it further leverages the global localization of several ground robots to seamlessly transfer between these ground robots in GPS-denied environments. Therewith one MAV can support multiple ground robots on a demand basis. Furthermore, our system enables different visual detection regimes, and enhanced operability, and return-home functionality. We evaluate our system in real-world SaR scenarios.Comment: Accepted for publication in 2018 IEEE International Symposium on Safety, Security and Rescue Robotics (SSRR

    Asymptotic behavior of support points for planar curves

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    In this paper we prove a universal inequality describing the asymptotic behavior of support points for planar continuous curves. As corollaries we get an analogous result for tangent points of differentiable planar curves and some (partially known) assertions on the asymptotic of the mean value points for various classical analytic theorems. Some open questions are formulated.Comment: 17 pages, some typos corrected, some references adde

    Trapping and acceleration of upflowing ionospheric electrons in the magnetosphere by electrostatic electron cyclotron harmonic (ECH) waves

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    During geomagnetically active conditions upflowing field-aligned electrons which form part of the Birkland current system have been observed at energies of up to 100 eV. If the first adiabatic invariant is conserved these electrons would reach the conjugate ionosphere without trapping in the magnetosphere. Here we show, by using quasi-linear diffusion theory, that electrostatic electron cyclotron harmonic (ECH) waves can diffuse these low energy electrons in pitch angle via Doppler shifted cyclotronresonance and trap them in the magnetosphere. We show that energy diffusion is comparable to pitch angle diffusion up to energies of a few keV. We suggest that ECH waves trap ionospheric electrons in the magnetosphere and accelerate them to produce butterfly pitch-angle distributions at energies of up to a few keV. We suggest that ECH waves play a role in magnetosphere-ionosphere coupling and help provide the source electron population for the radiation belts

    The Social Determinants of Health:Time to Re-Think?

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    Twelve years have now passed since the influential WHO Report on the Social Determinants of Health (SDoH) in 2008. A group of senior international public health scholars and decision-makers met in Italy in mid-2019 to review the legacy of the SDoH conceptual framework and its adequacy for the many challenges facing our field as we enter the 2020s. Four major categories of challenges were identified: emerging "exogenous" challenges to global health equity, challenges related to weak policy and practice implementation, more fundamental challenges related to SDoH theory and research, and broader issues around modern research in general. Each of these categories is discussed, and potential solutions offered. We conclude that although the SDoH framework is still a worthy core platform for public health research, policy, and practice, the time is ripe for significant evolution

    The social determinants of health: Time to re-think?

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    Twelve years have now passed since the influential WHO Report on the Social Determinants of Health (SDoH) in 2008. A group of senior international public health scholars and decision-makers met in Italy in mid-2019 to review the legacy of the SDoH conceptual framework and its adequacy for the many challenges facing our field as we enter the 2020s. Four major categories of challenges were identified: emerging “exogenous” challenges to global health equity, challenges related to weak policy and practice implementation, more fundamental challenges related to SDoH theory and research, and broader issues around modern research in general. Each of these categories is discussed, and potential solutions offered. We conclude that although the SDoH framework is still a worthy core platform for public health research, policy, and practice, the time is ripe for significant evolution

    A kinetic and theoretical study of the borate catalysed reactions of hydrogen peroxide: the role of dioxaborirane as the catalytic intermediate for a wide range of substrates

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    Our recent work has provided new insights into the equilibria and species that exist in aqueous solution at different pHs for the boric acid – hydrogen peroxide system, and the role of these species in oxidation reactions. Most recently, (M. C. Durrant, D. M. Davies and M. E. Deary, Org. Biomol. Chem., 2011, 9,7249–7254), we have produced strong theoretical and experimental evidence for the existence of a previously unreported monocyclic three membered peroxide species, dioxaborirane, that is the likely catalytic species in borate mediated electrophilic reactions of hydrogen peroxide in alkaline solution. In the present paper, we extend our study of the borate–peroxide system to look at a wide range of substrates that include substituted dimethyl anilines, methyl-p-tolyl sulfoxide, halides, hydrogen sulfide anion, thiosulfate ,thiocyanate, and hydrazine. The unusual selectivity–reactivity pattern of borate catalysed reactions compared with hydrogen peroxide and inorganic or organic peracids previously observed for theorganic sulfides (D. M. Davies, M. E. Deary, K. Quill and R. A. Smith, Chem.–Eur. J., 2005, 11, 3552–3558) is also seen with substituted dimethyl aniline nucleophiles. This provides evidence that the pattern is not due to any latent electrophilic tendency of the organic sulfides and further supports dioxaborirane being the likely reactive intermediate, thus broadening the applicability of this catalytic system. Moreover, density functional theory calculations on our proposed mechanism involving dioxaborirane are consistent with the experimental results for these substrates. Results obtained at high concentrations of both borate and hydrogen peroxide require the inclusion the diperoxodiborate dianion in the kinetic analysis .A scheme detailing our current understanding of the borate–peroxide system is presented

    Dynamical completions of generalized O'Raifeartaigh models

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    We present gauge theory completions of Wess-Zumino models admitting supersymmetry breaking vacua with spontaneously broken R-symmetry. Our models are simple deformations of generalized ITIY models, a supersymmetric theory with gauge group Sp(N), N+1 flavors plus singlets, with a modified tree level superpotential which explicitly breaks (part of) the global symmetry. Depending on the nature of the deformation, we obtain effective O'Raifeartaigh-like models whose pseudomoduli space is locally stable in a neighborhood of the origin of field space, or in a region not including it. Hence, once embedded in direct gauge mediation scenarios, our models can give low energy spectra with either suppressed or unsuppressed gaugino mass.Comment: 21 pages, 1 figure; v3: reference adde

    A Bio-Polymer Transistor: Electrical Amplification by Microtubules

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    Microtubules (MTs) are important cytoskeletal structures, engaged in a number of specific cellular activities, including vesicular traffic, cell cyto-architecture and motility, cell division, and information processing within neuronal processes. MTs have also been implicated in higher neuronal functions, including memory, and the emergence of "consciousness". How MTs handle and process electrical information, however, is heretofore unknown. Here we show new electrodynamic properties of MTs. Isolated, taxol-stabilized microtubules behave as bio-molecular transistors capable of amplifying electrical information. Electrical amplification by MTs can lead to the enhancement of dynamic information, and processivity in neurons can be conceptualized as an "ionic-based" transistor, which may impact among other known functions, neuronal computational capabilities.Comment: This is the final submitted version. The published version should be downloaded from Biophysical Journa

    The NIEHS Environmental Health Sciences Data Resource Portal: Placing Advanced Technologies in Service to Vulnerable Communities

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    BACKGROUND: Two devastating hurricanes ripped across the Gulf Coast of the United States during 2005. The effects of Hurricane Katrina were especially severe: The human and environmental health impacts on New Orleans, Louisiana, and other Gulf Coast communities will be felt for decades to come. The Federal Emergency Management Agency (FEMA) estimates that Katrina’s destruction disrupted the lives of roughly 650,000 Americans. Over 1,300 people died. The projected economic costs for recovery and reconstruction are likely to exceed $125 billion. OBJECTIVES: The NIEHS (National Institute of Environmental Health Sciences) Portal aims to provide decision makers with the data, information, and the tools they need to a) monitor human and environmental health impacts of disasters; b) assess and reduce human exposures to contaminants; and c) develop science-based remediation, rebuilding, and repopulation strategies. METHODS: The NIEHS Portal combines advances in geographic information systems (GIS), data mining/integration, and visualization technologies through new forms of grid-based (distributed, web-accessible) cyberinfrastructure. RESULTS: The scale and complexity of the problems presented by Hurricane Katrina made it evident that no stakeholder alone could tackle them and that there is a need for greater collaboration. The NIEHS Portal provides a collaboration-enabling, information-laden base necessary to respond to environmental health concerns in the Gulf Coast region while advancing integrative multidisciplinary research. CONCLUSIONS: The NIEHS Portal is poised to serve as a national resource to track environmental hazards following natural and man-made disasters, focus medical and environmental response and recovery resources in areas of greatest need, and function as a test bed for technologies that will help advance environmental health sciences research into the modern scientific and computing era
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