841 research outputs found

    Atomic oxygen between 80 and 120 km: Evidence for a rapid spatial variation in vertical transport near the ionosphere

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    Analysis of OGO-6 OI green line photometer results was carried out for 8 cases when the alignment of the spacecraft was such that local emission rates could be determined below the altitude of maximum emission and down to about 80 km. Results show a variation on a scale of 6 deg to 8 deg in latitude between regions where the emission rate increases rapidly between 90 and 95 km and regions where it increases slowly from 80 km to 95 km. Latitude-altitude maps of iso-emissivity contours and iso-density contours for oxygen concentration are presented. The latter are computed under 3 assumptions concerning excitation mechanisms. Comparisons of the spatial variations of oxygen density with the results of a time dependent theory suggest the regions of strong downward transport alternate on a scale of about 1000 km with regions of weak transport near 90 km. In the first case conversion of O to O3 at night appears to be overwhelmed by downward transport of O

    The two-loop five-particle amplitude in N=8\mathcal{N}=8 supergravity

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    We compute for the first time the two-loop five-particle amplitude in N=8\mathcal{N}=8 supergravity. Starting from the known integrand, we perform an integration-by-parts reduction and express the answer in terms of uniform weight master integrals. The latter are known to evaluate to non-planar pentagon functions, described by a 31-letter symbol alphabet. We express the final result for the amplitude in terms of uniform weight four symbols, multiplied by a small set of rational factors. The amplitude satisfies the expected factorization properties when one external graviton becomes soft, and when two external gravitons become collinear. We verify that the soft divergences of the amplitude exponentiate, and extract the finite remainder function. The latter depends on fewer rational factors, and is independent of one of the symbol letters. By analyzing identities involving rational factors and symbols we find a remarkably compact representation in terms of a single seed function, summed over all permutations of external particles. Finally, we work out the multi-Regge limit, and present explicitly the leading logarithmic terms in the limit. The full symbol of the IR-subtracted hard function is provided as an ancillary file.Comment: 22 pages, 1 figure, 8 ancillary file

    All master integrals for three-jet production at NNLO

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    We evaluate analytically all previously unknown nonplanar master integrals for massless five-particle scattering at two loops, using the differential equations method. A canonical form of the differential equations is obtained by identifying integrals with constant leading singularities, in DD space-time dimensions. These integrals evaluate to Q\mathbb{Q}-linear combinations of multiple polylogarithms of uniform weight at each order in the expansion in the dimensional regularization parameter, and are in agreement with previous conjectures for nonplanar pentagon functions. Our results provide the complete set of two-loop Feynman integrals for any massless 232\to 3 scattering process, thereby opening up a new level of precision collider phenomenology.Comment: 6 pages, 1 figure, 5 ancillary files; v2: references added; full boundary values in s12 physical region included; v3: values of the master integrals in the ancillary files update

    Influence of restraining devices on patterns of pediatric facial trauma in motor vehicle collisions.

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    In the Commonwealth of Pennsylvania, it is required that all children under the age of 4 years be restrained by an infant seat or car seat appropriate for their age and weight. Furthermore, all individuals riding in the front seat must be restrained by a seatbelt. This study examined the relationship between patterns of facial injuries and the use of restraining devices in the pediatric population. A retrospective analysis was performed on motor vehicle collision data submitted to the Pennsylvania Trauma Outcome Study database from 1990 through 1995. Criteria for submission included trauma patients who were admitted to the Intensive Care Unit, those who died during hospitalization, those who were hospitalized for more than 72 hours, or those who were transferred in or out of the receiving hospital. A subset of 412 pediatric patients, 15 years of age or younger, was analyzed for patterns of facial injury and the presence or absence of restraining devices. Restraining devices were categorized as a car seat or a seatbelt. Statistical analysis was performed using chi-square and Fisher\u27s exact tests. Of the 412 pediatric patients, only 17 children were restrained with a car seat and 121 were wearing a seatbelt. A total of 30 children sustained facial fractures, and 50 children suffered facial lacerations. There was a statistically significant increase in the incidence of facial fractures with increasing age of the child (p \u3c 0.001). Of children with facial fractures, 70 percent of those 5 to 12 years old and 90 percent of those 13 to 15 years old were unrestrained (p = 0.166). In conclusion, despite legislation mandating the use of restraints, a large proportion of children involved in motor vehicle collisions were unrestrained. Furthermore, there seems to be a direct relationship between the age of a child and the incidence of facial fractures sustained in motor vehicle collisions

    Designing for comfort in shared and automated vehicles (SAV): a conceptual framework

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    To date, automotive design and research is heavily biased towards the driver. However, with the rapid advance of vehicle automation, the driving task will increasingly being taken over by a machine. Automation by itself, however, will not be able to tackle the transport challenges we are facing and the need for shared mobility is now widely recognized. Future mobility solutions are therefore expected to consist of Shared and Automated Vehicles (SAV). This means that the passenger experience will take center stage in the design of future road vehicles. Whereas at first sight this may not appear to be different to the experience in other modes of transport, automation and shared mobility introduce different psychological, physical and physiological challenges. These are related to the fact that the occupant is no longer in control, has to put his or her life in the hands of a computer, while at the same time expects such future vehicles to render travel time more efficient or pleasurable and engage in so-called non-driving related tasks. Taking inspiration from work conducted in the field of aircraft passenger comfort experience, we discuss major comfort factors in the context of SAV and highlight both similarities and differences between transport modes. We present a human centered design framework to assist both the research agenda and the development of safe, usable, comfortable, and desirable future mobility solutions

    Parent and child dietary changes in a 6-month mobile-delivered weight loss intervention with tailored messaging for parents

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    Objective To examine changes in parent and child dietary intake, associations between program adherence and parent dietary changes, and the association between parent and child dietary changes in a mobile-delivered weight loss intervention for parents with personalized messaging. Methods Adults with overweight or obesity and who had a child aged 2–12 in the home were recruited for a randomized controlled trial comparing two types of dietary monitoring: calorie monitoring (Standard, n = 37) or “red” food monitoring (Simplified, n = 35). Parents received an intervention delivered via a smartphone application with lessons, text messages, and weekly personalized feedback, and self-monitoring of diet, activity, and weight. To measure associations between parent and child dietary changes, two 24-h recalls for parents and children at baseline and 6 months measured average daily calories, percent of calories from fat, vegetables, fruit, protein, dairy, whole grains, refined grains, added sugars, percent of calories from added sugars, and total Healthy Eating Index-2015 score. Results Higher parent engagement was associated with lower parent percent of calories from fat, and greater days meeting the dietary goal was associated with lower parent daily calories and refined grains. Adjusting for child age, number of children in the home, parent baseline BMI, and treatment group, there were significant positive associations between parent and child daily calories, whole grains, and refined grains. Parent-child dietary associations were not moderated by treatment group. Conclusions These results suggest that parent dietary changes in an adult weight loss program may indirectly influence child diet

    Correlation between Tick Density and Pathogen Endemicity, New Hampshire

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    To assess the endemicity of tick-borne pathogens in New Hampshire, we surveyed adult tick vectors. Pathogens were more prevalent in areas of high tick density, suggesting a correlation between tick establishment and pathogen endemicity. Infection rates in ticks correlated with disease frequency in humans

    Invasion of Two Tick-borne Diseases Across New England: Harnessing Human Surveillance Data to Capture Underlying Ecological Invasion Processes

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    Modelling the spatial spread of vector-borne zoonotic pathogens maintained in enzootic transmission cycles remains a major challenge. The best available spatio-temporal data on pathogen spread often take the form of human disease surveillance data. By applying a classic ecological approach-occupancy modelling-to an epidemiological question of disease spread, we used surveillance data to examine the latent ecological invasion of tick-borne pathogens. Over the last half-century, previously undescribed tick-borne pathogens including the agents of Lyme disease and human babesiosis have rapidly spread across the northeast United States. Despite their epidemiological importance, the mechanisms of tick-borne pathogen invasion and drivers underlying the distinct invasion trajectories of the co-vectored pathogens remain unresolved. Our approach allowed us to estimate the unobserved ecological processes underlying pathogen spread while accounting for imperfect detection of human cases. Our model predicts that tick-borne diseases spread in a diffusion-like manner with occasional long-distance dispersal and that babesiosis spread exhibits strong dependence on Lyme disease

    The Extrachromosomal EAST Protein of Drosophila Can Associate with Polytene Chromosomes and Regulate Gene Expression

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    The EAST protein of Drosophila is a component of an expandable extrachromosomal domain of the nucleus. To better understand its function, we studied the dynamics and localization of GFP-tagged EAST. In live larval salivary glands, EAST-GFP is highly mobile and localizes to the extrachromosomal nucleoplasm. When these cells are permeabilized, EAST-GFP rapidly associated with polytene chromosomes. The affinity to chromatin increases and mobility decreases with decreasing salt concentration. Deleting the C-terminal residues 1535 to 2301 of EAST strongly reduces the affinity to polytene chromosomes. The bulk of EAST-GFP co-localizes with heterochromatin and is absent from transcriptionally active chromosomal regions. The predominantly chromosomal localization of EAST-GFP can be detected in non-detergent treated salivary glands of pupae as they undergo apoptosis, however not in earlier stages of development. Consistent with this chromosomal pattern of localization, genetic evidence indicates a role for EAST in the repression of gene expression, since a lethal east mutation is allelic to the viable mutation suppressor of white-spotted. We propose that EAST acts as an ion sensor that modulates gene expression in response to changing intracellular ion concentrations
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