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Search Results: 1 - 10 of 215341 matches for " Scott L. Nutter "
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Cosmic-Ray Positrons: Are There Primary Sources?
Stephane Coutu,Steven W. Barwick,James J. Beatty,Amit Bhattacharyya,Chuck R. Bower,Christopher J. Chaput,Georgia A. de Nolfo,Michael A. DuVernois,Allan Labrador,Shawn P. McKee,Dietrich Muller,James A. Musser,Scott L. Nutter,Eric Schneider,Simon P. Swordy,Gregory Tarle,Andrew D. Tomasch,Eric Torbet
Physics , 1999, DOI: 10.1016/S0927-6505(99)00011-0
Abstract: Cosmic rays at the Earth include a secondary component originating in collisions of primary particles with the diffuse interstellar gas. The secondary cosmic rays are relatively rare but carry important information on the Galactic propagation of the primary particles. The secondary component includes a small fraction of antimatter particles, positrons and antiprotons. In addition, positrons and antiprotons may also come from unusual sources and possibly provide insight into new physics. For instance, the annihilation of heavy supersymmetric dark matter particles within the Galactic halo could lead to positrons or antiprotons with distinctive energy signatures. With the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument, we have measured the abundances of positrons and electrons at energies between 1 and 50 GeV. The data suggest that indeed a small additional antimatter component may be present that cannot be explained by a purely secondary production mechanism. Here we describe the signature of the effect and discuss its possible origin.
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry-BLASTPol: Performance and results from the 2012 Antarctic flight
N. Galitzki,P. A. R. Ade,F. E. Angilé,S. J. Benton,M. J. Devlin,B. Dober,L. M. Fissel,Y. Fukui,N. N. Gandilo,J. Klein,A. L. Korotkov,T. G. Matthews,L. Moncelsi,C. B. Netterfield,G. Novak,D. Nutter,E. Pascale,F. Poidevin,G. Savini,D. Scott,J. A. Shariff,J. D. Soler,C. E. Tucker,G. S. Tucker,D. Ward-Thompson
Physics , 2014, DOI: 10.1117/12.2054759
Abstract: The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping experiment, designed to study the role played by magnetic fields in the star formation process. BLASTPol observes polarized light using a total power instrument, photolithographic polarizing grids, and an achromatic half-wave plate to modulate the polarization signal. During its second flight from Antarctica in December 2012, BLASTPol made degree scale maps of linearly polarized dust emission from molecular clouds in three wavebands, centered at 250, 350, and 500 microns. The instrumental performance was an improvement over the 2010 BLASTPol flight, with decreased systematics resulting in a higher number of confirmed polarization vectors. The resultant dataset allows BLASTPol to trace magnetic fields in star-forming regions at scales ranging from cores to entire molecular cloud complexes.
Thermal design and performance of the balloon-borne large aperture submillimeter telescope for polarimetry BLASTPol
J. D. Soler,P. A. R. Ade,F. E. Angilè,S. J. Benton,M. J. Devlin,B. Dober,L. M. Fissel,Y. Fukui,N. Galitzki,N. N. Gandilo,J. Klein,A. L. Korotkov,T. G. Matthews,L. Moncelsi,A. Mroczkowski,C. B. Netterfield,G. Novak,D. Nutter,E. Pascale,F. Poidevin,G. Savini,D. Scott,J. A. Shariff,N. E. Thomas,M. D. Truch,C. E. Tucker,G. S. Tucker,D. Ward-Thompson
Physics , 2014, DOI: 10.1117/12.2055431
Abstract: We present the thermal model of the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). This instrument was successfully flown in two circumpolar flights from McMurdo, Antarctica in 2010 and 2012. During these two flights, BLASTPol obtained unprecedented information about the magnetic field in molecular clouds through the measurement of the polarized thermal emission of interstellar dust grains. The thermal design of the experiment addresses the stability and control of the payload necessary for this kind of measurement. We describe the thermal modeling of the payload including the sun-shielding strategy. We present the in-flight thermal performance of the instrument and compare the predictions of the model with the temperatures registered during the flight. We describe the difficulties of modeling the thermal behavior of the balloon-borne platform and establish landmarks that can be used in the design of future balloon-borne instruments.
Comparison of Prestellar Core Elongations and Large-Scale Molecular Cloud Structures in the Lupus I Region
F. Poidevin,P. A. R. Ade,F. E. Angile,S. J. Benton,E. L. Chapin,M. J. Devlin,L. M. Fissel,Y. Fukui,N. N. Gandilo,J. O. Gundersen,P. C. Hargrave,J. Klein,A. L. Korotkov,T. G. Matthews,L. Moncelsi,T. K. Mroczkowski,C. B. Netterfield,G. Novak,D. Nutter,L. Olmi,E. Pascale,G. Savini,D. Scott,J. A. Shariff,J. D. Soler,K. Tachihara,N. E. Thomas,M. D. P. Truch,C. E. Tucker,G. S. Tucker,D. Ward-Thompson
Physics , 2014, DOI: 10.1088/0004-637X/791/1/43
Abstract: Turbulence and magnetic fields are expected to be important for regulating molecular cloud formation and evolution. However, their effects on subparsec to 100 parsec scales, leading to the formation of starless cores, is not well understood. We investigate the prestellar core structure morphologies obtained from analysis of the Herschel-SPIRE 350 $\mu$m maps of the Lupus I cloud. This distribution is first compared on a statistical basis to the large scale shape of the main filament. We find the distribution of the elongation position angle of the cores to be consistent with a random distribution, which means no specific orientation of the morphology of the cores is observed with respect to a large-scale filament shape model for Lupus I, or relative to a large-scale bent filament model. This distribution is also compared to the mean orientation of the large-scale magnetic fields probed at 350 $\mu$m with the Balloon-borne Large Aperture Telescope for Polarimetry (BLASTPol) during its 2010 campaign. Here again we do not find any correlation between the core morphology distribution and the average orientation of the magnetic fields on parsec scales. Our main conclusion is that the local filament dynamics - including secondary filaments that often run orthogonally to the primary filament - and possibly small-scale variations in the local magnetic field direction, could be the dominant factors for explaining the final orientation of each core.
Lupus I Observations from the 2010 Flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry
Tristan G. Matthews,Peter A. R. Ade,Francesco E. Angilè,Steven J. Benton,Edward L. Chapin,Nicholas L. Chapman,Mark J. Devlin,Laura M. Fissel,Yasuo Fukui,Natalie N. Gandilo,Joshua O. Gundersen,Peter C. Hargrave,Jeffrey Klein,Andrei L. Korotkov,Lorenzo Moncelsi,Tony K. Mroczkowski,Calvin B. Netterfield,Giles Novak,David Nutter,Luca Olmi,Enzo Pascale,Frédérick Poidevin,Giorgio Savini,Douglas Scott,Jamil A. Shariff,Juan Diego Soler,Kengo Tachihara,Nicholas E. Thomas,Matthew D. P. Truch,Carole E. Tucker,Gregory S. Tucker,Derek Ward-Thompson
Physics , 2013, DOI: 10.1088/0004-637X/784/2/116
Abstract: The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 {\mu}m. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry (The optical data were published in 1998 by J. Rizzo and collaborators.). The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.
Rapid Increase in Log Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests in Northern Arizona  [PDF]
Joseph L. Ganey, Scott C. Vojta
Open Journal of Forestry (OJF) , 2012, DOI: 10.4236/ojf.2012.22008
Abstract: Down logs provide important ecosystem services in forests and affect surface fuel loads and fire behavior. Amounts and kinds of logs are influenced by factors such as forest type, disturbance regime, forest management, and climate. To quantify potential short-term changes in log populations during a recent global- climate-change type drought, we sampled logs in mixed-conifer and ponderosa pine (Pinus ponderosa) forests in northern Arizona in 2004 and 2009 (n = 53 and 60 1-ha plots in mixed-conifer and ponderosa pine forests, respectively). Over this short time interval, density of logs, log volume, area covered by logs, and total length of logs increased significantly in both forest types. Increases in all log parameters were greater in mixed-conifer than in ponderosa pine forest, and spatial variability was pronounced in both forest types. These results document rapid increases in log populations in mixed-conifer forest, with smaller changes observed in ponderosa pine forest. These increases were driven by climate-mediated tree mortality which created a pulse in log input, rather than by active forest management. The observed increases will affect wildlife habitat, surface fuel loads, and other ecosystem processes. These changes are likely to continue if climate change results in increased warmth and aridity as predicted, and may require shifts in management emphasis.
Arthroscopic Capsular Release for Frozen Shoulder—Time to Thaw the Delay?  [PDF]
Christopher Munro, Scott L. Barker, Kapil Kumar
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.49A004
Abstract:

Introduction: Frozen shoulder is a common condition that affects the working population. Current management regimes are variable nationwide and the evidence base on which to base these decisions is poor. The longevity and severity of symptoms often result in great economic burden, both to health services and in terms of absence from work. Early surgical intervention with arthroscopic capsular release may result in improved symptoms and earlier return to both work and leisure activities. Aims: The aim of our prospective cohort study was to investigate whether early intervention with arthroscopic capsular release resulted in improvement of symptoms and whether this would in turn provide overall economic benefit to society. Methods: Patients diagnosed with frozen shoulder at an elective orthopaedic specialist shoulder clinic were recruited prospectively. Data were gathered by way of questionnaire to ascertain the demographic information of the patient as well as their previous treatment in the primary care setting and absence from work. Initial Oxford Shoulder Score (OSS) was also calculated: Arthroscopic capsular release was then performed and further data gathered at four-week post-operative follow-up. Economic impact of delay to treatment and cost of intervention were calculated using government data from the national tariff which cost different forms of treatment. Statistical analysis was then performed on the results. Results: Twenty five patients were recruited. Mean results were: Age of patients: 53.5 years, duration of symptoms prior to intervention: 35.2 weeks, days absent from

Mechanisms of Action of Noninvasive Monopolar Radiofrequency: Technology Review  [PDF]
Terry L. Whipple, Scott P. Steinmann
Open Journal of Orthopedics (OJO) , 2013, DOI: 10.4236/ojo.2013.31006
Abstract:

Tendinosis is now understood as the result of a failed tendon healing process regardless of where it occurs in the body. Current noninvasive therapeutic alternatives are anti-inflammatory in nature and outcomes are unpredictable at best. The benefit of invasive alternatives resides in the induction of the healing response as demonstrated in pre-clinical and clinical studies in cardiology and orthopaedics. A new technology that employs noninvasivemonopolar capacitive-coupled radiofrequency (mcRF), has demonstrated the ability to raise temperatures in tendons and ligaments upwards of 50°C, the temperature threshold for collagen modulation and recruitment of macrophages, fibroblasts and Heat Shock Protein factors—without damaging the overlying structures—resulting in activation of the Wound Healing Response (WHR).

An Isothermal Study of the Electrochemical Performance of Intermediate Temperature Solid Oxide Fuel Cells  [PDF]
O. O. Ighodaro, K. Scott, L. Xing
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.52006
Abstract: A two-dimensional along the channel micro-scale isothermal model of a SOFC is developed and validated against experimental data and other simulated results from literature. The steady state behaviour of the cell was determined by numerical solution of the combined transport, continuity and kinetic equations. An important characteristic of the model is the consideration of the triple phase boundary as a distinct layer. The model is capable of predicting the cell performance including polarisation behaviour and power output. The model is used to study the effect of the support structure, geometric parameters and the effect of operating conditions on cell performance. Several parametric studies include the effect of operating conditions and geometric parameters on cell performance with a view to optimising the cell. The simulation results showed that the anode supported SOFC displayed the best performance with the activation and ohmic overpotentials being responsible for most of the voltage losses in the cell.
IL-21 modulates cytokine levels in murine collagen-induced arthritis and contributes to disease pathology
DA Young, M Hegen, H Ma, L Napierata, J Lamothe, M Senices, L Lowe, M Collins, C Nickerson-Nutter
Arthritis Research & Therapy , 2007, DOI: 10.1186/ar2227
Abstract: Previously we have shown that blockade of the IL-21 pathway with soluble IL-21R-Fc resulted in a reduction of clinical signs of arthritis in rodent models. To understand potential mechanisms of IL-21 regulation in arthritis, we analyzed serum immunoglobulin levels, and cytokine expression in the paws, serum, and collagen-restimulated splenocytes, in response to IL-21 pathway blockade.Arthritis was induced in DBA/1 male mice with bovine type II collagen. Animals were treated with either soluble mIL-21R-Fc, which neutralizes murine IL-21 bioactivity, with TNFRII-Fc or with control IgG. Spleens from each group of treated mice were cultured in vitro with collagen and assayed for cytokine secretion. Cytokines and anticollagen-specific IgG levels were also measured in the serum by ELISA. Cytokine mRNA levels in the paws were evaluated by quantitative PCR analysis.Treatment of mice with IL-21R-Fc or TNFRII-Fc reduced clinical and histological signs of collagen-induced arthritis. IL-6 mRNA in paws and serum IL-6 levels were decreased after IL-21R-Fc treatment. IFNγ mRNA was increased in paws of IL-21R-Fc-treated mice. Collagen-specific spleen cell responses from IL-21R-Fc-treated mice exhibited increased IFNγ and IL-2, and reduced IL-6 and IL-17 levels. Serum levels of total IgG1 were also reduced in response to IL-21R-Fc treatment.These data demonstrate a role for IL-21 in the modulation of collagen-specific T-cell responses and the pathology of arthritis, supporting a rationale for blockade of the IL-21 pathway in rheumatoid arthritis.
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