765 research outputs found

    The Solar Proton Burning Process Revisited In Chiral Perturbation Theory

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    The proton burning process p + p -> d + e(+) + \nu(e), important for the stellar evolution of main-sequence stars of mass equal to or less than that of the Sun, is computed in effective field theory using chiral perturbation expansion to the next-to-next-to leading chiral order. This represents a model-independent calculation consistent with low-energy effective theory of QCD comparable in accuracy to the radiative np capture at thermal energy previously calculated by first using very accurate two-nucleon wavefunctions backed up by an effective field theory technique with a finite cut-off. The result obtained thereby is found to support within theoretical uncertainties the previous calculation of the same process by Bahcall and his co-workers.Comment: 30 pages, 2 eps files, aaspp4.sty needed, slightly modified, to be published in Ap.

    The GRaPPa Lab: Supporting Team Decision Making in Complex Environments

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    poster abstractThe GRaPPa (Group Psychology and Performance) Lab operates within the School of Informatics at Indiana University Purdue University Indianapolis (IUPUI), in cooperation with the User Simulation and Experience Research Lab. The focus of our research is on interdependent teams in technologically complex work environments characterized by uncertainty, stress, high risk, changing moods, and varying levels of expertise. The GRaPPa Lab employs a mixed-methodological approach. Field studies provide rich and nuanced knowledge about individuals and teams at work in complex environments. Likewise, controlled laboratory experiments have provided the foundation for countless contributions to our understanding of the human characteristics that impact the development and use of systems, devices, and environments. Yet such experiments are limited in what they can tell us about work situated in real-world settings, just as field studies are limited in their support for precision and replicability. The GRaPPa Lab leverages the strengths of both through the use of simulated task environments and scaled worlds in the search for holistic assessments of group behavior and task performance. This poster will showcase aspects of an ongoing research program, Bridging the Situation Space to Decision Space Gap. This project is examining the modeling and visualization of decision space information to supplement situation space information in the contexts of disease contagion and emergency management. To enhance the decision support of emergency responders, we are examining the ability of decision space visualization tools to enhance option awareness and support more robust decision making. This work is focused on detailing the impact of the decision space information provided to users, relating the correctness of decisions to the levels of complexity represented in the events, and the affordances for understanding alternative actions. This ongoing project is focused on prototyping multiple visualization methods and testing them in human-in-the-loop experiments based on the domain of emergency crisis management. In addition, the computer models underlying the decision space are being expanded to support increasingly complex situations. This research provides further insight into the value of decision space information and option awareness for users working in complex environments

    Single-Exposure, Single-Mask, Edge-Illumination X-ray Phase-Contrast Imaging Using a 7.8-ÎŒm Pixel Pitch Direct Conversion X-ray Detector

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    Double-mask edge-illumination is a well-reported technique for phase-contrast x-ray imaging. Although phase retrieval using this technique is comparably easier than propagation-based phase-contrast x-ray imaging, edge-illumination can be inefficient in terms of dose efficiency and imaging time when it comes to computed tomography scanning. The illumination curve, which describes the beamlets' intensity profile impinging upon the detector, is a key parameter that contributes to retrieving phase and absorption information. To obtain the illumination curve, multiple exposures are typically required which decreases x-ray dose efficiency and, more importantly, increases imaging time. Moreover, sample motion can negatively impact the image and information retrieval process. In this research, we employ a single mask in conjunction with a 7.8-ÎŒm pixel pitch amorphous selenium-CMOS hybrid direct conversion x-ray detector to obtain the beamlets' intensity profile with only a single exposure. We demonstrate how using an ultra-high spatial resolution x-ray detector with a single-mask edge-illumination technique can potentially increase both dose efficiency and imaging time by at least a factor of 1.5X. Moreover, the resulting system using our approach is more compact with a source-to-detector distance of less than 30 cm. Single-exposure imaging can also help mitigate the impact of motion artifacts in the final image

    MARVAND: Mobile Application for Relief Volunteering Activity after Natural Disaster

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    poster abstractModern technologies play significant roles in the natural disaster domain. Current services focus mostly on providing information, recruiting volunteers, and donating money and goods, butless on supporting the activities of on-site volunteers. Our preliminary interviews showed that there are not enough experts on hand to help support on-site volunteers, and it is difficult to keep track of whether help requests have been met. To fill this gap, we proposed a MARVAND, utilizing LBS, with three main features: ‘Instant Crowd Knowledge’ providing access to remote experts using crowdsourcing; ‘Volunteer Radar’ providing awareness of other volunteers nearby; and ‘Reunite Missing Family Members’ helping reunite families who have been separated as a result of the disaster. The results of the evaluations with twelve participants who had experience in disaster relief volunteering activities demonstrated that the MARVAND could support activities of onsite volunteers after the natural disaster, and serve as an additional communication channel between volunteers and experts

    A Description of Multiscale Modeling for the Head-Disk Interface Focusing on Bottom-Level Lubricant and Carbon Overcoat Models

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    The challenges in designing future head disk interface (HDI) demand efficient theoretical modeling tools with flexibility in investigating various combinations of perfluoropolyether (PFPE) and carbon overcoat (COC) materials. For broad range of time and length scales, we developed multiscale/multiphysical modeling approach, which can bring paradigm-shifting improvements in advanced HDI design. In this paper, we introduce our multiscale modeling methodology with an effective strategic framework for the HDI system. Our multiscale methodology in this paper adopts a bottom to top approach beginning with the high-resolution modeling, which describes the intramolecular/intermolecular PFPE-COC degrees of freedom governing the functional oligomeric molecular conformations on the carbon surfaces. By introducing methodology for integrating atomistic/molecular/mesoscale levels via coarse-graining procedures, we investigated static and dynamic properties of PFPE-COC combinations with various molecular architectures. By bridging the atomistic and molecular scales, we are able to systematically incorporate first-principle physics into molecular models, thereby demonstrating a pathway for designing materials based on molecular architecture. We also discussed future materials (e.g., graphene for COC, star-like PFPEs) and systems (e.g., heat-assisted magnetic recording (HAMR)) with higher scale modeling methodology, which enables the incorporation of molecular/mesoscale information into the continuum scale models

    Radiative Neutron-Proton Capture in Effective Chiral Lagrangians

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    We calculate the cross-section for the thermal n+p→d+Îłn+p\rightarrow d+\gamma process in chiral perturbation theory to next-to-next-to-leading order using heavy-fermion formalism. The exchange current correction is found to be (4.5±0.3) %(4.5\pm 0.3)~\% in amplitude and the chiral perturbation at one-loop order gives the cross section \sigma_{th}^{np}=(334\pm 2)\ {\mbox mb} which is in agreement with the experimental value (334.2\pm 0.5)\ {\mbox mb}. Together with the axial charge transitions, this provides a strong support for the power of chiral Lagrangians for nuclear physics.Comment: 9 pages, revtex, uses epsfig.sty, 2 uuencoded figure

    Effect of the National Resident Assessment Instrument on Selected Health Conditions and Problems

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111253/1/j.1532-5415.1997.tb02972.x.pd

    The Rotation Average in Lightcone Time-Ordered Perturbation Theory

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    We present a rotation average of the two-body scattering amplitude in the lightcone time(τ\tau)-ordered perturbation theory. Using a rotation average procedure, we show that the contribution of individual time-ordered diagram can be quantified in a Lorentz invariant way. The number of time-ordered diagrams can also be reduced by half if the masses of two bodies are same. In the numerical example of ϕ3\phi^{3} theory, we find that the higher Fock-state contribution is quite small in the lightcone quantization.Comment: 25 pages, REVTeX, epsf.sty, 69 eps file

    Whole Genome Analysis of the Red-Crowned Crane Provides Insight into Avian Longevity

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    The red-crowned crane (Grus japonensis) is an endangered, large-bodied crane native to East Asia. It is a traditional symbol of longevity and its long lifespan has been confirmed both in captivity and in the wild. Lifespan in birds is known to be positively correlated with body size and negatively correlated with metabolic rate, though the genetic mechanisms for the red-crowned crane's long lifespan have not previously been investigated. Using whole genome sequencing and comparative evolutionary analyses against the grey-crowned crane and other avian genomes, including the long-lived common ostrich, we identified red-crowned crane candidate genes with known associations with longevity. Among these are positively selected genes in metabolism and immunity pathways (NDUFA5, NDUFA8, NUDT12, SOD3, CTH, RPA1, PHAX, HNMT, HS2ST1, PPCDC, PSTK CD8B, GP9, IL-9R, and PTPRC). Our analyses provide genetic evidence for low metabolic rate and longevity, accompanied by possible convergent adaptation signatures among distantly related large and long-lived birds. Finally, we identified low genetic diversity in the red-crowned crane, consistent with its listing as an endangered species, and this genome should provide a useful genetic resource for future conservation studies of this rare and iconic species
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