156 results on '"C. M. Hoffman"'
Search Results
2. Informing CONOPS and medical countermeasure deployment strategies after an improvised nuclear device detonation: the importance of delayed treatment efficacy data
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N Yeddanapudi, J M Appler, M A Clay, Mary J. Homer, David P. Durham, and C M Hoffman
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Detonation ,Concept of operations ,Time-to-Treatment ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aeronautics ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Nuclear Weapons ,Radiological and Ultrasound Technology ,business.industry ,fungi ,food and beverages ,Acute Radiation Syndrome ,Delayed treatment ,Radiation Exposure ,Improvised Nuclear Device ,Medical Countermeasures ,Software deployment ,030220 oncology & carcinogenesis ,Cytokines ,business ,Countermeasure (computer) - Abstract
Purpose: In the wake of a nuclear detonation, individuals with acute radiation syndrome will be a significant source of morbidity and mortality. Mathematical modeling can compare response strategie...
- Published
- 2018
3. Modeling the costs and benefits associated with the evolution of endothermy using a robotic python
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Dale F. DeNardo, Ty C. M. Hoffman, and J. Alex Brashears
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030110 physiology ,0301 basic medicine ,Avian clutch size ,Physiology ,Energy investment ,Aquatic Science ,Biology ,Models, Biological ,Energy requirement ,03 medical and health sciences ,Animals ,Homeothermy ,Clutch ,Process engineering ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Cost–benefit analysis ,business.industry ,Ecology ,Reproduction ,Thermogenesis ,Robotics ,Biological evolution ,Clutch Size ,Biological Evolution ,Boidae ,Insect Science ,Ectotherm ,Animal Science and Zoology ,business - Abstract
Endothermy provides considerable benefits to an organism but requires large energy investment. To understand potential driving forces that would lead to the evolution of endothermy, it is important to understand the energy costs and potential benefits of intermediate steps between ectothermy and homeothermic endothermy as well as the influences of environmental conditions on energetic costs. However, efforts to examine intermediate conditions are greatly limited by the predominant natural dichotomy between ectothermy and endothermy. Facultative endothermy by brooding pythons provides a fortunate study system where endothermy is beneficial but not essential. As one cannot control the extent of energy investment in heat production by a female python, we created an artificial snake with controllable heating capability. This enabled us to determine the energetic costs of maintaining a clutch at a preferred temperature, and to determine the relative thermal benefit of limited energy-producing capability (i.e. 50% of the required energy to maintain the preferred developmental temperature). We manipulated the pseudoserpent's clutch size (5, 10, 15 eggs), diel ambient temperature cycle (2, 4, 6°C) and insulation (with and without) at each of these power levels: unlimited power, half required power and no power. We found no significant effect of clutch size on either power requirements or developmental temperature. Energy requirements increased with the amplitude of the diel cycle and decreased with the addition of insulation, while the quality of the thermal environment decreased with the amplitude of the diel cycle. Interestingly, the quality of the thermal environment also decreased with the addition of insulation. We discuss these results within the context of the reproductive model of the evolution of endothermy.
- Published
- 2017
4. Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes
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Humberto Ibarguen Salazar, H. Martinez, J. Braun, Miguel Mostafa, B. Patricelli, Arnulfo Zepeda, Ibrahim Torres, J. McEnery, Varlen Grabski, H. León Vargas, R. Arceo, A. Marinelli, N. Bautista-Elivar, W.H. Lee, E. Moreno, V. Vasileiou, D.A. Williams, J.C. Arteaga-Velázquez, R. Noriega-Papaqui, C. M. Hui, A. A. Abdo, K. Sparks Woodle, F. Salesa, J. P. Harding, Michael DuVernois, Hao Zhou, P. Karn, R. A. Caballero-Lopez, Peter Nemethy, A. Sandoval, D. Berley, James M. Ryan, E. De la Fuente, Michael Schneider, T. Weisgarber, Fernando Garfias, Dirk Lennarz, Tyce DeYoung, E. Mendoza Torres, P.A. Toale, O. Martinez, S. Westerhoff, Petra Hüntemeyer, R. Diaz Hernandez, J. Martínez-Castro, Joshua A. Wood, Rodrigo Pelayo, B. T. Allen, E. Belmont, E. Ruiz-Velasco, A. Galindo, Z. Hampel-Arias, T. N. Ukwatta, A. J. Smith, Alberto Carramiñana, M. Bonilla Rosales, Alejandro Lara, Michael Newbold, J.H. MacGibbon, L. Nellen, Juan Carlos Diaz-Velez, R. Luna-GarcIa, C. M. Hoffman, D. W. Fiorino, C. Rivière, T. Aune, A. Imran, P.W. Younk, Segev BenZvi, J.A.J. Matthews, L. Villaseñor, J. A. Goodman, Ruben Alfaro, Daniel Rosa-Gonzalez, M. Gussert, C. De León, G. Sinnis, J. Becerra González, Daniel R. Stump, E.C. Linares, S.S. Marinelli, Jennifer Pretz, Anushka Udara Abeysekara, T. Morgan, Pedro Miranda-Romagnoli, A. Iriarte, P. M. Saz Parkinson, Jorge Cotzomi, M. Longo, Umberto Cotti, G.J. Kunde, T. Oceguera-Becerra, K. Tollefson, Maria Magdalena González, R. J. Lauer, E. Hays, D. Zaborov, Karen S. Caballero-Mora, H. A. Ayala Solares, J. D. Álvarez, G. B. Yodh, J. T. Linnemann, L. Diaz-Cruz, Allen Mincer, B. M. Baughman, A. S. Barber, G. E. Christopher, R. W. Ellsworth, S. Silich, B.E. Kolterman, M. Castillo, Nissim Illich Fraija, Brenda Dingus, I. Taboada, I.G. Wisher, R. W. Springer, E. G. Pérez-Pérez, C. Alvarez, and David Kieda
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Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,Astronomy ,FOS: Physical sciences ,Primordial black hole ,Astronomy and Astrophysics ,Gamma-ray astronomy ,Astrophysics ,Black hole ,Observatory ,Milagro ,Gamma-ray burst ,Astrophysics - High Energy Astrophysical Phenomena ,Cherenkov radiation - Abstract
Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ~5.0 x 10^14 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events., Comment: Accepted to Astroparticle Physics Journal (25 Pages, 3 figures and 7 tables). Corresponding author: T. N. Ukwatta
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- 2015
- Full Text
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5. MILAGRO OBSERVATIONS OF MULTI-TeV EMISSION FROM GALACTIC SOURCES IN THE FERMI BRIGHT SOURCE LIST
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E. Hays, G. Sinnis, Petra Huentemeyer, T. Aune, Brenda Dingus, C. M. Hoffman, A. A. Abdo, P. M. Saz Parkinson, J. T. Linnemann, James M. Ryan, G. P. Walker, V. Vasileiou, J. A. Goodman, B. T. Allen, T. Morgan, C. Chen, D. Berley, Tyce DeYoung, G. B. Yodh, Maria Magdalena González, Peter Nemethy, David A. Williams, A. L. Shoup, J. Pretz, Allen Mincer, A. J. S. Smith, Julie McEnery, G. E. Christopher, R. W. Ellsworth, and B. E. Kolterman
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Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,Pulsar wind nebula ,law.invention ,Telescope ,Pulsar ,law ,0103 physical sciences ,010303 astronomy & astrophysics ,media_common ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,010308 nuclear & particles physics ,Gamma ray ,Astronomy and Astrophysics ,Fermi energy ,Astrophysics - Astrophysics of Galaxies ,13. Climate action ,Space and Planetary Science ,Sky ,Astrophysics of Galaxies (astro-ph.GA) ,Milagro ,Astrophysics - High Energy Astrophysical Phenomena ,Fermi Gamma-ray Space Telescope - Abstract
We present the result of a search of the Milagro sky map for spatial correlations with sources from a subset of the recent Fermi Bright Source List (BSL). The BSL consists of the 205 most significant sources detected above 100 MeV by the Fermi Large Area Telescope. We select sources based on their categorization in the BSL, taking all confirmed or possible Galactic sources in the field of view of Milagro. Of the 34 Fermi sources selected, 14 are observed by Milagro at a significance of 3 standard deviations or more. We conduct this search with a new analysis which employs newly-optimized gamma-hadron separation and utilizes the full 8-year Milagro dataset. Milagro is sensitive to gamma rays with energy from 1 to 100 TeV with a peak sensitivity from 10-50 TeV depending on the source spectrum and declination. These results extend the observation of these sources far above the Fermi energy band. With the new analysis and additional data, multi-TeV emission is definitively observed associated with the Fermi pulsar, J2229.0+6114, in the Boomerang Pulsar Wind Nebula (PWN). Furthermore, an extended region of multi-TeV emission is associated with the Fermi pulsar, J0634.0+1745, the Geminga pulsar., Comment: Accepted for publication in Astrophysical Journal Letters June 30, 2009
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- 2009
6. THE LARGE-SCALE COSMIC-RAY ANISOTROPY AS OBSERVED WITH MILAGRO
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C. P. Lansdell, James M. Ryan, B. E. Kolterman, D. Noyes, T. Aune, Brenda Dingus, David Berley, Peter Nemethy, J. T. Linnemann, C. M. Hoffman, G. W. Sullivan, B. T. Allen, R. W. Ellsworth, J. A. Goodman, R. Fleysher, P. H. Hüntemeyer, A. L. Shoup, A. J. Smith, M. M. Gonzalez, L. Fleysher, Allen Mincer, Sabrina Casanova, David A. Williams, A. A. Abdo, V. Vasileiou, B. Hopper, Julie McEnery, P. M. Saz Parkinson, G. P. Walker, Chang-Hsiao Chen, G. B. Yodh, J. Pretz, and G. Sinnis
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Physics ,010308 nuclear & particles physics ,Cherenkov detector ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,01 natural sciences ,Declination ,law.invention ,Space and Planetary Science ,Observatory ,law ,Sidereal time ,0103 physical sciences ,Milagro ,Anisotropy ,Right ascension ,010303 astronomy & astrophysics - Abstract
Results are presented of a harmonic analysis of the large scale cosmic-ray anisotropy as observed by the Milagro observatory. We show a two-dimensional display of the sidereal anisotropy pro jections in right ascension generated by the fitting of three harmonics to 18 separate declination bands. The Milagro observatory is a water Cherenkov detector located in the Jemez mountains near Los Alamos, New Mexico. With a high duty cycle and large field-of-view, Milagro is an excellent instrument for measuring this anisotropy with high sensitivity at TeV energies. The analysis is conducted using a seven year data sample consisting of more than 95 billion events, the largest such data set in existence. We observe an anisotropy with a magnitude around 0.1% for cosmic rays with a median energy of 6 TeV. The dominant feature is a deficit region of depth (2.49 +/- 0.02 stat. +/- 0.09 sys.)x10^(-3) in the direction of the Galactic North Pole centered at 189 degrees right ascension. We observe a steady increase in the magnitude of the signal over seven years., Comment: 36 pages, 16 figures, submitted to ApJ
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- 2009
7. Search for correlations between HiRes stereo events and active galactic nuclei
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R. C. Gray, B. T. Stokes, C. Song, B. C. Knapp, J. R. Thomas, John N. Matthews, J. H. Boyer, Segev BenZvi, L. M. Scott, A. O’Neill, R. Riehle, C. Cannon, O. A. Brusova, Pierre Sokolsky, Dale Tupa, G. Archbold, P. Hüntemeyer, Konstantin Belov, W. Deng, Douglas Bergman, N. Sasaki, C. B. Finley, M. M. Maestas, M. A. Kirn, S. A. Blake, Gordon Thomson, M. D. Roberts, R. W. Springer, E. J. Mannel, C. C. H. Jui, Steve Schnetzer, E. C. Loh, G. Sinnis, Gareth Hughes, S. B. Thomas, C. M. Hoffman, Michael H. Holzscheiter, Tareq Abu-Zayyad, B. F. Jones, M. Seman, Y. Fedorova, J. D. Smith, Kevin Reil, N. Manago, J. F. Amman, J. Findlay, D. Rodriguez, Z. Cao, Lawrence Wiencke, Dmitri Ivanov, R. Snow, John Belz, S. A. Moore, L. Perera, Xiang Zhang, L. J. Marek, K. Kim, M. Allen, William Hanlon, Rasha Abbasi, C. A. Painter, K. Martens, A. Zech, G. W. Burt, and S. R. Stratton
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Physics ,Active galactic nucleus ,010308 nuclear & particles physics ,Astrophysics (astro-ph) ,Northern Hemisphere ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,Positive correlation ,01 natural sciences ,Auger ,Data set ,Correlation ,0103 physical sciences ,010303 astronomy & astrophysics ,Southern Hemisphere - Abstract
We have searched for correlations between the pointing directions of ultrahigh energy cosmic rays observed by the High Resolution Fly's Eye experiment and Active Galactic Nuclei (AGN) visible from its northern hemisphere location. No correlations, other than random correlations, have been found. We report our results using search parameters prescribed by the Pierre Auger collaboration. Using these parameters, the Auger collaboration concludes that a positive correlation exists for sources visible to their southern hemisphere location. We also describe results using two methods for determining the chance probability of correlations: one in which a hypothesis is formed from scanning one half of the data and tested on the second half, and another which involves a scan over the entire data set. The most significant correlation found occurred with a chance probability of 24%., 13 pages, 1 table, 5 figures
- Published
- 2008
8. Postural Shifts During Egg-Brooding and Their Impact on Egg Water Balance in Children’s Pythons (Antaresia childreni)
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Ty C. M. Hoffman, Dale F. DeNardo, and Zachary R. Stahlschmidt
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Developmental stage ,biology ,Ecology ,Offspring ,Respiratory gas exchange ,Zoology ,biology.organism_classification ,Discontinuous gas exchange ,Water balance ,Antaresia childreni ,embryonic structures ,behavior and behavior mechanisms ,Animal Science and Zoology ,Clutch ,Paternal care ,reproductive and urinary physiology ,Ecology, Evolution, Behavior and Systematics - Abstract
Parental care typically consists of distinct behavioral components that are balanced to address the multiple needs of offspring. Female pythons exhibit post-oviposition parental care in which they coil around their parchment-shelled eggs throughout incubation (40‐80 d). Subtle postural shifts during egg-brooding facilitate embryonic gas exchange but may entail hydric costs to the clutch. This study used a simple behavioral model to (1) further quantify the costs and benefits of specific parental behaviors to developing offspring and (2) determine the influence that developmental stage and relative clutch mass have on parental behavior. Although previous research has demonstrated that egg-brooding as a whole reduces clutch water loss, we hypothesized that eggbrooding female pythons specifically adopt a tightly coiled posture to conserve embryonic water, but must make postural adjustments to enhance gas exchange between the clutch and nest environments at the cost of increased clutch water loss. We measured rates of water loss in brooding Children’s pythons (Antaresia childreni) and their respective clutches (i.e., brooding units) and monitored changes in brooding posture. We conducted serial trials to elucidate the effect of developmental stage on postural adjustments and water loss. Results demonstrated that the proportion of time females spent in a tightly coiled posture was inversely related to mean water loss from the brooding unit. Analyses indicated that slight adjustments in posture led to bursts in brooding unit water loss. Indeed, brooding unit water loss during postural adjustments was significantly higher than during tight coiling. These findings imply that python egg-brooding provides an adjustable diffusive barrier that leads to discontinuous gas exchange, which minimizes clutch water loss. Because females with larger relative clutch masses spent more time tightly coiled, egg-brooding female pythons may use a ‘water first’ strategy in which they intentionally conserve clutch water at the cost of reduced embryonic respiratory gas exchange.
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- 2008
9. Search for point-like sources of cosmic rays with energies above 1018.5eV in the HiRes-I monocular data set
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B.M. Connolly, William Hanlon, Rasha Abbasi, L. Perera, S. A. Blake, M. D. Roberts, W. Deng, C. M. Hoffman, G. Sinnis, Y. Fedorova, Dale Tupa, C. B. Finley, John N. Matthews, Gareth Hughes, J. D. Smith, Tareq Abu-Zayyad, B. F. Jones, R. Riehle, R. W. Springer, Kevin Reil, R. C. Gray, C. A. Painter, B. T. Stokes, J. R. Thomas, L. M. Scott, K. Martens, M. A. Kirn, E. C. Loh, Pierre Sokolsky, A. Zech, M. M. Maestas, N. Manago, Z. Cao, S. A. Moore, G. Archbold, J. A.J. Matthews, Douglas Bergman, Segev BenZvi, Lawrence Wiencke, C. C. H. Jui, Konstantin Belov, J. Findlay, Xiang Zhang, John Belz, Steve Schnetzer, M. Sasaki, S. B. Thomas, C. Song, L. J. Marek, P. Hüntemeyer, A. O’Neill, D. Rodriguez, James F. Amann, S. Westerhoff, K. Kim, Gordon Thomson, and Michael H. Holzscheiter
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Physics ,Monocular ,Point source ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Northern Hemisphere ,Astronomy ,Flux ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Physics::Geophysics ,Sky ,0103 physical sciences ,Ultra-high-energy cosmic ray ,010306 general physics ,Anisotropy ,010303 astronomy & astrophysics ,media_common - Abstract
We report the results of a search for point-like deviations from isotropy in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere. In the monocular data set collected by the High-Resolution Fly's Eye, consisting of 1,525 events with energy exceeding 10^18.5 eV, we find no evidence for point-like excesses. We place 90% c.l. upper limits less than or equal to 0.8 cosmic rays/km^2yr on the flux from such sources as a function of position in the sky., Comment: 24 pages, 16 figures
- Published
- 2007
10. Studies of systematic uncertainties in the estimation of the monocular aperture of the HiRes experiment
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B. F. Jones, A. O’Neill, K. Martens, John Belz, G. W. Burt, O. A. Brusova, A. Zech, Pierre Sokolsky, P. Hüntemeyer, L. M. Scott, C. B. Finley, L. J. Marek, Dale Tupa, William Hanlon, Rasha Abbasi, C. C. H. Jui, John N. Matthews, E. C. Loh, John Matthews, S. B. Thomas, B. T. Stokes, J. R. Thomas, R. W. Springer, Konstantin Belov, B. C. Connolly, G. Archbold, Lawrence Wiencke, N. Manago, W. Deng, Douglas Bergman, C. Song, S. Y. Ben Zvi, Steve Schnetzer, L. Perera, J. D. Smith, S. A. Blake, M. Sasaki, Xiang Zhang, M. D. Roberts, Kevin Reil, Gareth Hughes, J. F. Amman, M. M. Maestas, R. Riehle, Tareq Abu-Zayyad, Z. Cao, C. A. Painter, C. M. Hoffman, D. Rodriguez, G. Sinnis, S. A. Moore, S. Westerhoff, Y. Fedorova, K. Kim, M. A. Kirn, R. C. Gray, Gordon Thomson, and Michael H. Holzscheiter
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Physics ,Monocular ,business.industry ,Aperture ,Astrophysics (astro-ph) ,Monte Carlo method ,Detector ,FOS: Physical sciences ,Astronomy and Astrophysics ,Cosmic ray ,Interaction model ,Astrophysics ,01 natural sciences ,Power law ,3. Good health ,Computational physics ,Air shower ,Optics ,0103 physical sciences ,010306 general physics ,business ,010303 astronomy & astrophysics - Abstract
We have studied several sources of systematic uncertainty in calculating the aperture of the High Resolution Fly's Eye experiment (HiRes) in monocular mode, primarily as they affect the HiRes-II site. The energy dependent aperture is determined with detailed Monte Carlo simulations of the air showers and the detector response. We have studied the effects of changes to the input energy spectrum and composition used in the simulation. A realistic shape of the input spectrum is used in our analysis in order to avoid biases in the aperture estimate due to the limited detector resolution. We have examined the effect of exchanging our input spectrum with a simple E^{-3} power law in the "ankle" region. Uncertainties in the input composition are shown to be significant for energies below about 10^{18} eV for data from the HiRes-II detector. Another source of uncertainties is the choice of the hadronic interaction model in the air shower generator. We compare the aperture estimate for two different models: QGSJet01 and SIBYLL 2.1. We also describe the implications of employing an atmospheric database with hourly measurements of the aerosol component, instead of using an average as has been used in our previously published measurements of the monocular spectra., Comment: 27 pages, 15 figures, revision
- Published
- 2007
11. Cloacal evaporation: an important and previously undescribed mechanism for avian thermoregulation
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Ty C. M. Hoffman, Glenn E. Walsberg, and Dale F. DeNardo
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Physiology ,Evaporation ,Zoology ,Coturnix ,Aquatic Science ,Biology ,Cloaca ,Species Specificity ,Skin Physiological Phenomena ,biology.animal ,Animals ,Columbidae ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Mouth ,Ecology ,Arizona ,Temperature ,Thermoregulation ,biology.organism_classification ,Water Loss, Insensible ,Quail ,Insect Science ,Coturnix coturnix ,Animal Science and Zoology ,Body Temperature Regulation - Abstract
SUMMARY We present the first experimental evidence that a bird is capable of evaporating enough water from the cloaca to be important for thermoregulation. We measured rates of evaporation occurring from the mouth, the skin, and the cloaca of Inca doves Columbina inca Lesson and Eurasian quail Coturnix coturnix Linnaeus. Inca doves showed no significant increase in cutaneous evaporation in response to curtailment of buccopharyngeal evaporation. Cloacal evaporation in doves was negligible at ambient temperatures of 30°, 35° and 40°C. However, at 42°C, the apportionment of total evaporation in doves was 53.4% cutaneous, 25.4%buccopharyngeal and 21.2% cloacal, with cloacal evaporation shedding, on average, 150 mW of heat. In contrast, the evaporative apportionment in quail at 32°C (the highest ambient temperature tolerated by this species) was 58.2% cutaneous, 35.4% buccopharyngeal and 6.4% cloacal. These results suggest that, for some birds, cloacal evaporation can be controlled and could serve as an important emergency tactic for thermoregulation at high ambient temperatures.
- Published
- 2007
12. A likelihood method for measuring the ultrahigh energy cosmic ray composition
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B.M. Connolly, D. Rodriguez, A. O’Neill, R. Snow, Douglas Bergman, John N. Matthews, S. Westerhoff, Gordon Thomson, K. Kim, Lawrence Wiencke, M. A. Kirn, John Matthews, W. Deng, M. Sasaki, N. Manago, J. Findlay, John Belz, Michael H. Holzscheiter, B. T. Stokes, S. A. Blake, M. Seman, M. D. Roberts, J. R. Thomas, L. J. Marek, Z. Cao, R. W. Springer, J. H. Boyer, K. Martens, Gareth Hughes, Dale Tupa, A. Zech, C. M. Hoffman, Tareq Abu-Zayyad, G. Sinnis, C. C. H. Jui, J. F. Amman, Y. Fedorova, S. B. Thomas, P. Hüntemeyer, C. B. Finley, G. Archbold, Pierre Sokolsky, E. J. Mannel, R. Riehle, E. C. Loh, M. M. Maestas, Konstantin Belov, B. C. Knapp, G. W. Burt, L. Perera, Steve Schnetzer, William Hanlon, Rasha Abbasi, Segev BenZvi, Kevin Reil, J. D. Smith, and C. A. Painter
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Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Detector ,Hadron ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Cosmic ray ,Function (mathematics) ,Astrophysics ,Spectral line ,Computational physics ,Distribution (mathematics) ,Energy (signal processing) - Abstract
Air fluorescence detectors traditionally determine the dominant chemical composit ion of the ultrahigh energy cosmic ray flux by comparing the averaged slant depth of the shower maximum, $X_{max}$, as a function of energy to the slant depths expect ed for various hypothesized primaries. In this paper, we present a method to make a direct measurement of the expected mean number of protons and iron by comparing the shap es of the expected $X_{max}$ distributions to the distribution for data. The advantages of this method includes the use of information of the full distribution and its ability to calculate a flux for various cosmic ray compositi ons. The same method can be expanded to marginalize uncertainties due to choice of spectra, hadronic models and atmospheric parameters. We demonstrate the technique with independent simulated data samples from a parent sample of protons and iron. We accurately predict the number of protons and iron in the parent sample and show that the uncertainties are meaningful., 11 figures, 22 pages, accepted by Astroparticle Physics
- Published
- 2006
13. Using Direct Calorimetry to Test the Accuracy of Indirect Calorimetry in an Ectotherm
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Glenn E. Walsberg and Ty C. M. Hoffman
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Hot Temperature ,Time Factors ,Physiology ,Chemistry ,Respiratory gas exchange ,Thermodynamics ,Direct calorimetry ,Calorimetry ,Sensitivity and Specificity ,Biochemistry ,Endothermic process ,Boidae ,Energy expenditure ,Ectotherm ,Metabolic heat production ,Animals ,Animal Science and Zoology ,Body Temperature Regulation - Abstract
We previously demonstrated that the relationship between respiratory gas exchange and metabolic heat production is unexpectedly variable and that conventional approaches to estimating energy expenditure by indirect calorimetry can incorporate large errors. Prior studies, however, comparing direct and indirect calorimetry of animals focused only on endothermic organisms. Given that endothermy and ectothermy represent a fundamental dichotomy of animal energetics, in this analysis we explore how these contrasting physiologies correlate with the relationship between heat production and respiratory gas exchange. Simultaneous indirect and direct calorimetry in an ectotherm, the ball python (Python regius Shaw), revealed that the relationships between gas exchange and heat production were within 1% of those expected when analyses using indirect calorimetry were based on the assumption that the fasting animal catabolized only protein. This accuracy of indirect calorimetry contrasts sharply with our previous conclusions for three species of birds and mammals.
- Published
- 2006
14. A measurement of time-averaged aerosol optical depth using air-showers observed in stereo by HiRes
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A. O’Neill, M. Seman, B.M. Connolly, Kevin Reil, Konstantin Belov, John N. Matthews, C. Cannon, P. Hüntemeyer, E. J. Mannel, R. W. Springer, G. Archbold, C. B. Finley, S. Westerhoff, M. D. Roberts, B. T. Stokes, C. M. Hoffman, G. Sinnis, John Matthews, Dale Tupa, J. H. Boyer, Y. Fedorova, E. C. Loh, K. Martens, A. Zech, Steve Schnetzer, Gordon Thomson, C. Song, B. C. Knapp, C. C. H. Jui, Michael H. Holzscheiter, James F. Amann, Gareth Hughes, Tareq Abu-Zayyad, Pierre Sokolsky, Segev BenZvi, S. B. Thomas, Lawrence Wiencke, Z. Cao, M. A. Kirn, John Belz, J. D. Smith, Douglas Bergman, William Hanlon, Rasha Abbasi, N. Manago, and R. W. Atkins
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Physics ,business.industry ,Attenuation ,Detector ,Astronomy and Astrophysics ,Cosmic ray ,Atmospheric model ,Astrophysics ,Aerosol ,Atmosphere ,Optics ,business ,Energy (signal processing) ,Optical depth ,Remote sensing - Abstract
Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span., Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journal
- Published
- 2006
15. Search for Cross‐Correlations of Ultrahigh‐Energy Cosmic Rays with BL Lacertae Objects
- Author
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S. A. Blake, J. D. Smith, Kevin Reil, D. Rodriguez, M. D. Roberts, R. Snow, C. M. Hoffman, G. Sinnis, Y. Fedorova, S. Westerhoff, K. Kim, E. J. Mannel, John N. Matthews, B.M. Connolly, Konstantin Belov, G. Archbold, N. Manago, W. Deng, Lawrence Wiencke, P. Hüntemeyer, Segev BenZvi, Dale Tupa, C. B. Finley, M. Seman, J. A.J. Matthews, R. W. Springer, K. Martens, Gareth Hughes, A. Zech, Tareq Abu-Zayyad, M. Sasaki, Steve Schnetzer, M. M. Maestas, G. W. Burt, B. C. Knapp, Gordon Thomson, James F. Amann, J. Findlay, Douglas Bergman, John Belz, Pierre Sokolsky, L. J. Marek, C. C. H. Jui, R. Riehle, Michael H. Holzscheiter, S. B. Thomas, William Hanlon, Rasha Abbasi, A. O’Neill, B. T. Stokes, J. R. Thomas, Z. Cao, J. H. Boyer, M. A. Kirn, C. A. Painter, E. C. Loh, and L. Perera
- Subjects
Physics ,Active galactic nucleus ,genetic structures ,010308 nuclear & particles physics ,High resolution ,Astronomy ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,01 natural sciences ,Galaxy ,Correlation ,Space and Planetary Science ,0103 physical sciences ,Ultrahigh energy ,010303 astronomy & astrophysics ,health care economics and organizations - Abstract
Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultra--high-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lacs and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lacs from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data., Comment: 5 pages, 1 figure, submitted to ApJ
- Published
- 2006
16. Observation of the ankle and evidence for a high-energy break in the cosmic ray spectrum
- Author
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S. Y. Ben Zvi, Gordon Thomson, J. A.J. Matthews, J. Findlay, John Belz, Steve Schnetzer, B. C. Connolly, L. J. Marek, Michael H. Holzscheiter, C. Song, J. R. Thomas, John N. Matthews, P. Hüntemeyer, M. A. Kirn, C. B. Finley, Lawrence Wiencke, K. M. Simpson, Kevin Reil, William Hanlon, Rasha Abbasi, R. Riehle, B. T. Stokes, W. Deng, N. Manago, Bruce R. Dawson, M. Sasaki, M. D. Roberts, C. M. Hoffman, G. Sinnis, Jose A. Bellido, G. Archbold, Douglas Bergman, C. A. Painter, Z. Cao, A. O’Neill, Konstantin Belov, R. W. Atkins, E.G. Loh, Dale Tupa, R. W. Springer, C. C. H. Jui, G. W. Burt, S. B. Thomas, J. D. Smith, J. F. Amman, R. Snow, L. Perera, S. Westerhoff, K. Kim, Pierre Sokolsky, K. Martens, A. Zech, Gareth Hughes, Tareq Abu-Zayyad, Y. Fedorova, Roger W Clay, and M. M. Maestas
- Subjects
Physics ,Nuclear and High Energy Physics ,Photomultiplier ,Physics::Instrumentation and Detectors ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Spectrum (functional analysis) ,Detector ,High resolution ,Cosmic ray ,Astrophysics ,01 natural sciences ,medicine.anatomical_structure ,Computer Science::Systems and Control ,0103 physical sciences ,Calibration ,medicine ,Ankle ,010303 astronomy & astrophysics ,Energy (signal processing) - Abstract
We have measured the cosmic ray spectrum at energies above $10^{17}$ eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near $3\times 10^{18}$ eV, and strong evidence for a suppression near $6\times 10^{19}$ eV., Comment: 14 pages, 9 figures. To appear in Physics Letters B. Accepted version
- Published
- 2005
17. Search for Point Sources of Ultra–High‐Energy Cosmic Rays above 4.0 x 1019eV Using a Maximum Likelihood Ratio Test
- Author
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R. U. Abbasi, T. Abu‐Zayyad, J. F. Amann, G. Archbold, R. Atkins, J. A. Bellido, K. Belov, J. W. Belz, S. Y. Ben‐Zvi, D. R. Bergman, J. H. Boyer, G. W. Burt, Z. Cao, R. W. Clay, B. M. Connolly, B. R. Dawson, W. Deng, G. R. Farrar, Y. Fedorova, J. Findlay, C. B. Finley, W. F. Hanlon, C. M. Hoffman, M. H. Holzscheiter, G. A. Hughes, P. Huntemeyer, C. C. H. Jui, K. Kim, M. A. Kirn, B. C. Knapp, E. C. Loh, M. M. Maestas, N. Manago, E. J. Mannel, L. J. Marek, K. Martens, J. A. J. Matthews, J. N. Matthews, A. O’Neill, C. A. Painter, L. Perera, K. Reil, R. Riehle, M. D. Roberts, M. Sasaki, S. R. Schnetzer, M. Seman, K. M. Simpson, G. Sinnis, J. D. Smith, R. Snow, P. Sokolsky, C. Song, R. W. Springer, B. T. Stokes, J. R. Thomas, S. B. Thomas, G. B. Thomson, D. Tupa, S. Westerhoff, L. R. Wiencke, and A. Zech
- Subjects
Physics ,010308 nuclear & particles physics ,Point source ,Astrophysics::High Energy Astrophysical Phenomena ,Ratio test ,Astronomy and Astrophysics ,Probability density function ,Cosmic ray ,Astrophysics ,01 natural sciences ,Bin ,Space and Planetary Science ,0103 physical sciences ,Ultra-high-energy cosmic ray ,Cluster analysis ,010303 astronomy & astrophysics ,Event (probability theory) - Abstract
We present the results of a search for cosmic ray point sources at energies above 40 EeV in the combined data sets recorded by the AGASA and HiRes stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found.
- Published
- 2005
18. A search for arrival direction clustering in the HiRes-I monocular data above 1019.5 eV
- Author
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B.M. Connolly, A. O’Neill, L. Perera, Z. Cao, N. Manago, R. W. Springer, Gordon Thomson, G. Archbold, J. Findlay, John N. Matthews, John Belz, P. Hüntemeyer, G. W. Burt, Michael H. Holzscheiter, R. Snow, K. Martens, J. R. Thomas, Douglas Bergman, B. T. Stokes, A. Zech, S. Westerhoff, W. Deng, K. Kim, Bruce R. Dawson, Dale Tupa, M. D. Roberts, C. B. Finley, C. M. Hoffman, R. W. Atkins, M. A. Kirn, G. Sinnis, Y. Fedorova, Jose A. Bellido, Gareth Hughes, Tareq Abu-Zayyad, L. J. Marek, Pierre Sokolsky, Lawrence Wiencke, M. Sasaki, E. C. Loh, C. C. H. Jui, S. B. Thomas, James F. Amann, Segev BenZvi, R. Riehle, J. D. Smith, C. A. Painter, William Hanlon, Rasha Abbasi, J. A.J. Matthews, C. Song, Kevin Reil, K. M. Simpson, Konstantin Belov, M. M. Maestas, Steve Schnetzer, and Roger W Clay
- Subjects
Physics ,Monocular ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Autocorrelation ,Detector ,Astronomy and Astrophysics ,Cosmic ray ,Akeno Giant Air Shower Array ,Astrophysics ,01 natural sciences ,Data set ,0103 physical sciences ,Angular resolution ,Cluster analysis ,010303 astronomy & astrophysics - Abstract
In the past few years, small scale anisotropy has become a primary focus in the search for source of Ultra-High Energy Cosmic Rays (UHECRs). The Akeno Giant Air Shower Array (AGASA) has reported the presence of clusters of event arrival directions in their highest energy data set. The High Resolution Fly's Eye (HiRes) has accumulated an exposure in one of its monocular eyes at energies above 10^(19.5) eV comparable to that of AGASA. However, monocular events observed with an air fluorescence detector are characterized by highly asymmetric angular resolution. A method is developed for measuring autocorrelation with asymmetric angular resolution. It is concluded that HiRes-I observations are consistent with no autocorrelation and that the sensitivity to clustering of the HiRes-I detector is comparable to that of the reported AGASA data set. Furthermore, we state with a 90% confidence level that no more than 13% of the observed HiRes-I events above 10^(19.5) eV could be sharing common arrival directions. However, because a measure of autocorrelation makes no assumption of the underlying astrophysical mechanism that results in clustering phenomena, we cannot claim that the HiRes monocular analysis and the AGASA analysis are inconsistent beyond a specified confidence level., Comment: 16 pages, 23 figures
- Published
- 2004
19. Study of Small-Scale Anisotropy of Ultra-High-Energy Cosmic Rays Observed in Stereo by the High Resolution Fly's Eye Detector
- Author
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Douglas Bergman, J. A.J. Matthews, J. D. Smith, R. Snow, M. A. Kirn, C. Song, Kevin Reil, B. C. Knapp, R. W. Springer, Jose A. Bellido, W. Deng, S. Westerhoff, Gordon Thomson, L. J. Marek, G. Archbold, K. Kim, M. M. Maestas, M. Seman, R. Riehle, C. A. Painter, Michael H. Holzscheiter, Dale Tupa, C. C. H. Jui, Lawrence Wiencke, John N. Matthews, Pierre Sokolsky, R. W. Atkins, James F. Amann, S. B. Thomas, M. Sasaki, Segev BenZvi, M. D. Roberts, Z. Cao, Roger W Clay, E. J. Mannel, C. M. Hoffman, G. Sinnis, E. C. Loh, William Hanlon, Y. Fedorova, Rasha Abbasi, Konstantin Belov, A. O’Neill, K. M. Simpson, C. B. Finley, Steve Schnetzer, L. Perera, N. Manago, J. Findlay, John Belz, B. T. Stokes, J. H. Boyer, Bruce R. Dawson, J. R. Thomas, Gareth Hughes, Tareq Abu-Zayyad, G. W. Burt, B.M. Connolly, P. Hüntemeyer, K. Martens, and A. Zech
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Detector ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,01 natural sciences ,Cosmology ,Particle acceleration ,Correlation function (statistical mechanics) ,Space and Planetary Science ,0103 physical sciences ,Angular resolution ,Ultra-high-energy cosmic ray ,Anisotropy ,010303 astronomy & astrophysics - Abstract
The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 06 and is sensitive to cosmic rays with energies above 1018 eV. The HiRes cosmic-ray detector is thus an excellent instrument for the study of the arrival directions of ultra-high-energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales ( 1019 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 1019 eV. No small-scale anisotropy is found, and the strongest clustering found in the HiRes stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.
- Published
- 2004
20. TeV Gamma‐Ray Survey of the Northern Hemisphere Sky Using the Milagro Observatory
- Author
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A. Shoup, Midge Wilson, R. W. Ellsworth, J. T. Linnemann, C. M. Hoffman, R. Fleysher, L. A. Kelley, L. Fleysher, J. A. Goodman, Galen Gisler, X. W. Xu, G. W. Sullivan, Frank W. Samuelson, James M. Ryan, Allen Mincer, G. Sinnis, J. E. McEnery, D. Noyes, Wystan Benbow, Peter Nemethy, S. Westerhoff, David A. Williams, J. Bussons, Miguel F. Morales, Richard Miller, D. E. Dorfan, D. G. Coyne, R. Atkins, G. B. Yodh, A. J. Smith, D. Berley, T. DeYoung, Brenda Dingus, Todd Haines, E. Blaufuss, C. P. Lansdell, M. M. Gonzalez, and E. Hays
- Subjects
Physics ,Active galactic nucleus ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,Astronomy ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Crab Nebula ,Air shower ,Extragalactic background light ,Space and Planetary Science ,Observatory ,Milagro ,Astrophysics::Galaxy Astrophysics - Abstract
Milagro is a water Cerenkov extensive air shower array that continuously monitors the entire overhead sky in the TeV energy band. The results from an analysis of ~3 yr of data (2000 December-2003 November) are presented. The data have been searched for steady point sources of TeV gamma rays between declinations of 11 and 80°. Two sources are detected, the Crab Nebula and the active galaxy Mrk 421. For the remainder of the northern hemisphere, we set 95% confidence level (CL) upper limits between 275 and 600 mcrab (4.8 × 10-12 to 10.5 × 10-12 cm-2 s-1) above 1 TeV for source declinations between 5° and 70°. Since the sensitivity of Milagro depends on the spectrum of the source at the top of the atmosphere, the dependence of the limits on the spectrum of a candidate source is presented. Because high-energy gamma rays from extragalactic sources are absorbed by interactions with the extragalactic background light, the dependence of the flux limits on the redshift of a candidate source are given. The upper limits presented here are over an order of magnitude more stringent than previously published limits from TeV gamma-ray all-sky surveys.
- Published
- 2004
21. Cloacal evaporative cooling: a previously undescribed means of increasing evaporative water loss at higher temperatures in a desert ectotherm, the Gila monster Heloderma suspectum
- Author
-
Tricia E. Zubal, Ty C. M. Hoffman, and Dale F. DeNardo
- Subjects
Heloderma ,Physiology ,Aquatic Science ,Animal science ,Cloaca ,biology.animal ,Animals ,Gila monster ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Analysis of Variance ,biology ,Ecology ,Lizard ,Body Weight ,Arizona ,Temperature ,Lizards ,Thermoregulation ,biology.organism_classification ,Adaptation, Physiological ,Water Loss, Insensible ,Insect Science ,Ectotherm ,Animal Science and Zoology ,Desert Climate ,Body Temperature Regulation ,Evaporative cooler - Abstract
The Gila monster Heloderma suspectum is an active forager in an environment that, at times, can be extremely hot and arid. Thus, Gila monsters face extreme thermostatic and hydrostatic demands. For a desert ectotherm routinely risking dehydration, evaporative water loss (EWL) is typically viewed as detrimental. Yet evaporation simultaneously dehydrates and cools an animal. We explored EWL in Gila monsters by measuring cutaneous, ventilatory and cloacal EWL at five ambient temperatures between 20.5 degrees C and 40 degrees C. Our results show that Gila monsters have high EWL rates relative to body mass. Cutaneous EWL underwent a consistent, temperature-dependent increase over the entire range of test temperatures (Q(10)=1.61, with EWL ranging from 0.378 to 0.954 mg g(-1) h(-1)). Ventilatory EWL did not show a significant temperature-dependent response, but ranged from 0.304 to 0.663 mg g(-1) h(-1). Cloacal EWL was extremely low and relatively constant between 20.5 degrees C and 35 degrees C, but rose dramatically above 35 degrees C (Q(10)8.3 x 10(7), from 0.0008 at 35 degrees C to 7.30 mg g(-1) h(-1) at 40 degrees C). This steep rise in cloacal EWL coincided with an increasing suppression of body temperature relative to ambient temperature. Dehydration to 80% of initial body mass led to a delay in the onset and an attenuation of the dramatic increase in cloacal EWL. These results emphasize the potential value of EWL for thermoregulation in ectotherms and demonstrate for the first time the role of the cloaca in this process.
- Published
- 2004
22. Observation of GeV Solar Energetic Particles from the 1997 November 6 Event Using Milagrito
- Author
-
Todd Haines, Galen Gisler, R. W. Ellsworth, R. Fleysher, J. E. McEnery, M. L. Chen, Wystan Benbow, James M. Ryan, L. A. Kelley, T. Yang, Miguel F. Morales, G. W. Sullivan, S. Westerhoff, R. Atkins, M. O. Wascko, A. J. Smith, Peter Nemethy, Abraham D. Falcone, D. G. Coyne, D. Berley, L. Fleysher, Kelin Wang, B. C. Shen, Tumay O. Tumer, A. Shoup, Richard Miller, C. M. Hoffman, I. Leonor, G. Sinnis, D. E. Dorfan, J. F. McCullough, Brenda Dingus, J. A. Goodman, Allen Mincer, S. Hugenberger, David A. Williams, and G. B. Yodh
- Subjects
Physics ,Photomultiplier ,Photosphere ,Neutron monitor ,Solar energetic particles ,Solar flare ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Interplanetary medium ,Astronomy and Astrophysics ,Astrophysics ,Space and Planetary Science ,Observatory ,Physics::Space Physics ,Milagro ,Astrophysics::Solar and Stellar Astrophysics - Abstract
Milagrito was an extensive air-shower observatory that served as a prototype for the larger Milagro instrument. Milagrito operated from 1997 February to 1998 May. Although it was designed as a very high energy (few hundred GeV threshold) water-Cerenkov gamma-ray observatory, it could also be used to study solar energetic particles (SEPs). By recording scaler data, which correspond to photomultiplier tube singles rates, it was sensitive to muons and small showers from hadronic primary particles with rigidities above ~4 GV. Milagrito simultaneously recorded air-shower trigger data of primary particles with energies greater than ~100 GeV that provide the data to help reconstruct event directions. The Milagrito scalers registered a ground-level enhancement associated with the 1997 November 6 SEP event and X9 solar flare. At its peak, the enhancement was 22 times the background rms fluctuations. Based on comparisons to neutron monitor and satellite data, we find evidence that the rigidity power-law spectrum for the differential flux of energetic protons steepened above ~4 GV and that the acceleration site was high in the corona (at ~3 R☉ above the photosphere), assuming that a CME-driven shock was responsible for the ground-level enhancement.
- Published
- 2003
23. Milagro observations of potential TeV emitters
- Author
-
A. J. Smith, B. T. Allen, Julie McEnery, A. S. Barber, J. Pretz, E. Hays, Michael Schneider, J. Braun, B. E. Kolterman, A. A. Abdo, Anushka Udara Abeysekara, Peter Nemethy, V. Vasileiou, A. Shoup, Maria Magdalena González, James M. Ryan, Petra Hüntemeyer, J. A. Goodman, David A. Williams, G. E. Christopher, R. W. Ellsworth, G. B. Yodh, Allen Mincer, Brenda Dingus, A. Imran, J. T. Linnemann, P. M. Saz Parkinson, C. M. Hoffman, G. Sinnis, T. Morgan, C. Chen, D. Berley, Tyce DeYoung, G. P. Walker, and T. Aune
- Subjects
Active galactic nucleus ,Point source ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Atomic ,Particle and Plasma Physics ,Pulsar ,Nuclear ,Astrophysics::Galaxy Astrophysics ,Pulsars ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Astroparticle physics ,Physics ,astro-ph.HE ,Active galactic nuclei ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Molecular ,Astronomy and Astrophysics ,Gamma-ray astronomy ,Galaxies ,Nuclear & Particles Physics ,Galaxy ,Milagro ,Astrophysics - High Energy Astrophysical Phenomena ,Gamma-rays ,Astronomical and Space Sciences ,Fermi Gamma-ray Space Telescope - Abstract
This paper reports the results from three targeted searches of Milagro TeV sky maps: two extragalactic point source lists and one pulsar source list. The first extragalactic candidate list consists of 709 candidates selected from the Fermi-LAT 2FGL catalog. The second extragalactic candidate list contains 31 candidates selected from the TeVCat source catalog that have been detected by imaging atmospheric Cherenkov telescopes (IACTs). In both extragalactic candidate lists Mkn 421 was the only source detected by Milagro. This paper presents the Milagro TeV flux for Mkn 421 and flux limits for the brighter Fermi-LAT extragalactic sources and for all TeVCat candidates. The pulsar list extends a previously published Milagro targeted search for Galactic sources. With the 32 new gamma-ray pulsars identified in 2FGL, the number of pulsars that are studied by both Fermi-LAT and Milagro is increased to 52. In this sample, we find that the probability of Milagro detecting a TeV emission coincident with a pulsar increases with the GeV flux observed by the Fermi-LAT in the energy range from 0.1 GeV to 100 GeV., Comment: 18 pages, 6 Figures and 4 tables
- Published
- 2014
24. Evaluating crown fire rate of spread from physics based simulations to field data
- Author
-
C. M. Hoffman, R. R. Linn, W. Mell, C. H. Sieg, F. Pimont, J. Ziegler, Colorado State University [Fort Collins] (CSU), Los Alamos National Laboratory (LANL), Pacific Wildland Fire Sciences Laboratory, United States Department of Agriculture, Rocky Mountain Research Station, Unité de Recherches Forestières Méditerranéennes (URFM), and Institut National de la Recherche Agronomique (INRA)
- Subjects
model evaluation ,13. Climate action ,fire behaviour ,physics-based model ,15. Life on land ,[SDE.ES]Environmental Sciences/Environmental and Society - Abstract
Wildland fire behavior models are commonly used to augment expert opinions, experiments and field observations by both the research and management communities. However, modelling wildfires is challenging in part due to complex set of coupled processes that drive the properties of a spreading wildfire. Further these processes occur over a vast span of spatial and temporal scales that further complicate the development and validation of models. Due to these complications there has been a variety of model types developed for a variety of specific applications. Regardless of the type and purpose of a model, well quantified fire behavior data from wildland fires and field and laboratory experimental fires are necessary for a variety of reasons including the calibration of empirically based models, the evaluation of physically based or theoretical models, and to provide model developers with potential areas to improve model performance by identifying inadequacies in the code. Here we utilize a compiled data set of crown fire rate of spread from Alexander and Cruz (2006) to evaluate published crown fire rate of spread predictions from two physics-based fire behavior models HIGRAD/FIRETEC developed at Los Alamos National Laboratory and the Wildland Urban Interface Fire Dynamics Simulator (WFDS) developed by the National Institute of Standards and Technology and the USDA Forest Service. Our preliminary results suggest that physics based models reasonably predict the crown fire rate of spread given the current data set. In addition we discuss the sensitivity of physics based models to a variety of parameters which likely influence crown fire rate of spread.
- Published
- 2014
25. The Study of TeV Variability and the Duty Cycle of Mrk 421 from 3 Yr of Observations with the Milagro Observatory
- Author
-
B. Patricelli, R. S. Delay, A. J. S. Smith, A. Imran, P. M. Saz Parkinson, James M. Ryan, Gus Sinnis, Petra Hüntemeyer, E. Hays, Nissim Illich Fraija, C. M. Hoffman, G. E. Christopher, Anushka Udara Abeysekara, R. W. Ellsworth, B. T. Allen, G. B. Yodh, B. E. Kolterman, C. Chen, A. Marinelli, J. T. Linnemann, V. Vasileiou, Brenda Dingus, D. Berley, A. L. Shoup, J. Pretz, Allen Mincer, Tyce DeYoung, G. P. Walker, M. M. Gonzalez, J. A. Goodman, Peter Nemethy, T. Morgan, T. Aune, Julie McEnery, A. S. Barber, A. A. Abdo, Michael Schneider, J. Braun, David R. Williams, Laboratoire Univers et Particules de Montpellier (LUPM), and Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
individual [BL Lacertae objects] ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astronomy & Astrophysics ,Atomic ,Physical Chemistry ,01 natural sciences ,BL Lacertae objects: individual (Markarian 421) ,law.invention ,blazar ,X-ray ,Particle and Plasma Physics ,Observatory ,law ,0103 physical sciences ,synchrotron ,Nuclear ,Blazar ,010303 astronomy & astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,astro-ph.HE ,Physics ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,Molecular ,Astronomy and Astrophysics ,gamma rays: general ,flux ,observatory ,gamma ray: VHE ,Space and Planetary Science ,Duty cycle ,correlation ,Milagro ,astro-ph.CO ,Physics::Accelerator Physics ,High Energy Physics::Experiment ,VERITAS ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,general [gamma rays] ,statistical ,Astronomical and Space Sciences ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Physical Chemistry (incl. Structural) ,Flare - Abstract
TeV flaring activity with time scales as short as tens of minutes and an orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421). The TeV emission from Mrk 421 is believed to be produced by leptonic synchrotron self-Compton (SSC) emission. In this scenario, correlations between the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly explained and the activity (measured as duty cycle) of the source at TeV energies is expected to be equal or less than that observed in X-rays if only SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish limits on its variability at different time scales, we continuously observed Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a statistical significance of 7.1 standard deviations between 2005 September 21 and 2008 March 15. The observed spectrum is consistent with previous observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies above 1 TeV for different hypothesis of the baseline flux and for different flare selections and we compare our results with the X-ray duty cycle estimated by Resconi et al. 2009. The robustness of the results is discussed., Comment: 27 pages, 6 figures, ApJ accepted
- Published
- 2014
26. A Survey of the Northern Sky for TeV Point Sources
- Author
-
K. Wang, R. Atkins, W. Benbow, D. Berley, M.‐L. Chen, D. G. Coyne, B. L. Dingus, D. E. Dorfan, R. W. Ellsworth, A. Falcone, L. Fleysher, R. Fleysher, G. Gisler, J. A. Goodman, T. J. Haines, C. M. Hoffman, S. Hugenberger, L. A. Kelley, I. Leonor, M. McConnell, J. F. McCullough, J. E. McEnery, R. S. Miller, A. I. Mincer, M. F. Morales, P. Nemethy, J. M. Ryan, F. W. Samuelson, B. Shen, A. Shoup, G. Sinnis, A. J. Smith, G. W. Sullivan, O. T. Tumer, M. O. Wascko, S. Westerhoff, D. A. Williams, T. Yang, and G. B. Yodh
- Subjects
Physics ,Point source ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,Photon flux ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,Declination ,Space and Planetary Science ,Sky ,Point (geometry) ,Astrophysics::Galaxy Astrophysics ,media_common - Abstract
A search for steady TeV point sources anywhere in the northern sky has been made with data from the Milagrito air-shower-particle detector. Over 3 x 10**9 events collected from 1997 February to 1998 May have been used in this study. No statistically significant excess above the background from the isotropic flux of cosmic rays was found for any direction of the sky with declination between -5 degrees and 71.7 degrees. Upper limits are derived for the photon flux above 1 TeV from any steady point source in the northern sky., 2 Figures
- Published
- 2001
27. Evidence for T[CLC]e[/CLC]V Emission from GRB 970417[CLC]a[/CLC]
- Author
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A. J. Smith, Miguel F. Morales, A. Shoup, Kelin Wang, D. G. Coyne, C. M. Hoffman, R. W. Ellsworth, Mark L. McConnell, J. F. McCullough, S. Westerhoff, M. O. Wascko, Tumay O. Tumer, B. Shen, R. W. Atkins, James M. Ryan, T. Yang, Wystan Benbow, R. Fleysher, Peter Nemethy, D. Berley, L. A. Kelley, Allen Mincer, Todd Haines, Richard Miller, L. Fleysher, M. L. Chen, I. Leonor, G. W. Sullivan, Brenda Dingus, D. E. Dorfan, Galen Gisler, J. A. Goodman, A. Falcone, J. E. McEnery, S. Hugenberger, David A. Williams, D. Evans, C. Sinnis, and G. B. Yodh
- Subjects
Physics ,High energy ,Large field of view ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Gamma ray ,Astronomy ,Astronomy and Astrophysics ,Field of view ,Astrophysics ,Space and Planetary Science ,Coincident ,Sky ,Gamma-ray burst ,media_common - Abstract
Milagrito, a detector sensitive to very high energy gamma rays, monitored the northern sky from 1997 February through 1998 May. With a large field of view and a high duty cycle, this instrument was well suited to perform a search for TeV gamma-ray bursts (GRBs). We report on a search made for TeV counterparts to GRBs observed by BATSE. BATSE detected 54 GRBs within the field of view of Milagrito during this period. An excess of events coincident in time and space with one of these bursts, GRB 970417a, was observed by Milagrito. The excess has a chance probability of 2.8 × 10-5 of being a fluctuation of the background. The probability for observing an excess at least this large from any of the 54 bursts is 1.5 × 10-3. No significant correlations were detected from the other bursts.
- Published
- 2000
28. Inhibiting ventilatory evaporation produces an adaptive increase in cutaneous evaporation in mourning doves Zenaida macroura
- Author
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Ty C. M. Hoffman and Glenn E. Walsberg
- Subjects
Meteorology ,biology ,Physiology ,Chemistry ,Evaporation ,Heat losses ,Skin temperature ,Aquatic Science ,biology.organism_classification ,Zenaida macroura ,Animal science ,Insect Science ,Skin surface ,Animal Science and Zoology ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Water vapor - Abstract
We tested the hypothesis that birds can rapidly change the conductance of water vapor at the skin surface in response to a changing need for evaporative heat loss. Mourning doves (Zenaida macroura) were placed in a two-compartment chamber separating the head from the rest of the body. The rate of cutaneous evaporation was measured in response to dry ventilatory inflow at three ambient temperatures and in response to vapor-saturated ventilatory inflow at two ambient temperatures. At 35 °C, cutaneous evaporation increased by 72 % when evaporative water loss from the mouth was prevented, but no increase was observed at 45 °C. For both dry and vapor-saturated treatments, cutaneous evaporation increased significantly with increased ambient temperature. Changes in skin temperature made only a minor contribution to any observed increase in cutaneous evaporation. This indicates that Z. macroura can effect rapid adjustment of evaporative conductance at the skin in response to acute change in thermoregulatory demand.
- Published
- 1999
29. T[CLC]e[/CLC]V Observations of Markarian 501 with the Milagrito Water Cerenkov Detector
- Author
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R. Atkins, W. Benbow, D. Berley, M. L. Chen, D. G. Coyne, R. S. Delay, B. L. Dingus, D. E. Dorfan, R. W. Ellsworth, C. Espinoza, D. Evans, A. Falcone, L. Fleysher, R. Fleysher, G. Gisler, J. A. Goodman, T. J. Haines, C. M. Hoffman, S. Hugenberger, L. A. Kelley, I. Leonor, M. McConnell, J. F. McCullough, J. E. McEnery, R. S. Miller, A. I. Mincer, M. F. Morales, M. M. Murray, P. Nemethy, J. M. Ryan, M. Schneider, B. Shen, A. Shoup, C. Sinnis, A. J. Smith, G. W. Sullivan, T. N. Thompson, T. Tumer, K. Wang, M. O. Wascko, S. Westerhoff, D. A. Williams, T. Yang, G. B. Yodh, and null (The Milagro Collaboration)
- Subjects
Physics ,Space and Planetary Science ,law ,Sky ,Cherenkov detector ,media_common.quotation_subject ,Milagro ,Detector ,Astronomy and Astrophysics ,Astrophysics ,Flare ,law.invention ,media_common - Abstract
The Milagrito water Cherenkov detector near Los Alamos, New Mexico, operated as a sky monitor at energies of a few TeV between February 1997 and May 1998 including the period of the strong, long-lasting 1997 flare of Markarian 501. Milagrito served as a test run for the full Milagro detector. An event excess with a significance of 3.7 sigma from Markarian 501 was observed, in agreement with expectations.
- Published
- 1999
30. High energy gamma ray astroparticle physics with milagro
- Author
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T. N. Thompson, Michael Schneider, G. W. Sullivan, S. Delay, Kelin Wang, R. Fleyesher, Richard Miller, M. L. Chen, Peter Nemethy, Todd Haines, M. Cavalli-Sforza, I. Leonor, G. B. Yodh, D. G. Coyne, Benjamin C. Shen, C. M. Hoffman, B. C. Shen, D. Berley, S. Westerhoff, John R. Macri, C. Espinosa, M. Murray, S. Hugenberger, James M. Ryan, T. Yang, David A. Williams, C. Sinnis, D. E. Dorfan, Tumay O. Tumer, J. F. McCullough, Galen Gisler, Allen Mincer, L. Fleyesher, R. W. Ellsworth, L. A. Kelley, A. J. Smith, Mark L. McConnell, M. O. Wascko, A. Shoup, Brenda Dingus, and J. A. Goodman
- Subjects
Astroparticle physics ,Physics ,Nuclear and High Energy Physics ,High energy ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Detector ,Astrophysics::Instrumentation and Methods for Astrophysics ,Gamma ray ,Astrophysics ,Atomic and Molecular Physics, and Optics ,Air shower ,Sky ,Physics::Space Physics ,Milagro ,High Energy Physics::Experiment ,Angular resolution ,media_common - Abstract
Milagro will be the first water-Cerenkov detector specifically built to study extensive air showers. It is being built in an existing man-made pond located near Los Alamos, NM. Milagro will be the only air shower detector to have an energy threshold as low as a few hundred GeV and an angular resolution as good as 0.3°. Milagro will observe the entire overhead sky at all times. We describe here the Milagro detector, it capabilities and its physics goals.
- Published
- 1999
31. Do Metabolic Responses to Solar Radiation Scale Directly with Intensity of Irradiance?
- Author
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Randall L. Tracy, Ty C. M. Hoffman, and Glenn E. Walsberg
- Subjects
Phodopus ,Physiology ,Irradiance ,Wind ,Aquatic Science ,Radiation ,Atmospheric sciences ,chemistry.chemical_compound ,Oxygen Consumption ,Optics ,Cricetinae ,Thermal ,Animals ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Sunlight ,business.industry ,Temperature ,Carbon Dioxide ,Respiratory quotient ,Metabolism ,chemistry ,Insect Science ,Solar gain ,Carbon dioxide ,Animal Science and Zoology ,business ,Intensity (heat transfer) ,Body Temperature Regulation - Abstract
Endotherms exposed to air temperatures below thermal neutrality reduce their metabolic heat production when exposed to sunlight. The physiological effects of this additional source of heat gain from the environment usually are assumed to be proportional to the intensity of irradiance if other factors are held constant. We test this assumption by measuring changes in metabolic heat production produced by exposing a small mammal, the Siberian hamster (Phodopus sungorus) to four intensities of simulated solar radiation (0 W m−2, 317 W m−2, 634 W m−2 and 950 W m−2). In the absence of solar radiation, metabolic heat production is inversely correlated with air temperature over the measured range of 3–27 °C. The respiratory quotient varies significantly with ambient temperature, indicating that the catabolic substrate and the thermal equivalent of oxygen consumed or carbon dioxide produced also vary with temperature. The depression of metabolic heat production resulting from exposure to simulated solar radiation is not simply a multiple of the intensity of irradiance. Rather, metabolic responses to higher levels of irradiance are blunted by 14–29 % compared with those expected on the basis of the response to less intense irradiance. Because changes in irradiance levels do not have simple linear effects upon the animal’s metabolic heat production, even in a simplified situation, significant errors may accumulate in biophysical analyses in which an animal’s responses to a restricted set of radiative conditions are measured and the results are extrapolated to a wider range observed in nature.
- Published
- 1997
32. Demonstration of Communication using Neutrinos
- Author
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Daniel D. Stancil, K. Hurtado, R. Gran, N. Tagg, J. Devan, N. Ochoa, M. Kordosky, A. Pla-Dalmau, J. Grange, Sergey A. Kulagin, Steve Dytman, J. Chvojka, G. A. Fiorentini, C. J. Solano Salinas, G. Zavala, Howard Scott Budd, I. Vergalosova, C. Araujo Del Castillo, Michael Benjamin Andrews, R. Bradford, B. Eberly, L. Loiacono, William Brooks, R. J. Stefanski, T. Griffin, J. Mousseau, J. G. Morfín, T. Le, M. Lanari, M. Day, J. Voirin, J. Kilmer, J. L. Bazo Alba, B. G. Tice, D. J. Boehnlein, Cristian Pena, J. Wolcott, J. A. Niemiec-Gielata, R. G. Stevens, M. E. Christy, T. P. Wytock, L. Aliaga, D. A.M. Caicedo, P. Rubinov, A. Judd, A. Chamorro, Brian L. Hughes, K. Kephart, C. M. Castromonte, D. Zhang, Fedor Prokoshin, L. Y. Zhu, Jennifer Hobbs, J. Osta, D. Ruggiero, A. Mislivec, T. Kafka, V. Kuznetsov, O. S. Sands, Juan C. Felix, Brandon J. Walker, B. Osmanov, James Downey, P. D. Conrow, Kevin Scott McFarland, D. P. Capista, E. Schulte, B. P. Ziemer, M. Reyhan, A. M. Gago, V. Takhistov, V. Paolone, H. Schellman, Ha Youn Lee, H. da Motta, Ronald Ransome, Gabriel Perdue, J. L. Palomino, J. Park, J. S. Paradis, A. Higuera, E. Charlton, J. R. Fein, S. Manly, A. M. McGowan, E. Hahn, C. M. Marshall, L. Fields, E. Maher, P. Adamson, Joshua D. Griffin, W. A. Mann, Alison Peterman, J. Walding, C. E. Perez Lara, G. Maggi, D. W. Schmitz, J.P. Velásquez, J. K. Nelson, Anatoly Butkevich, C. Simon, L. Bagby, T. Walton, M. Alania, H. R. Gallagher, D. A. Harris, I. Z. Danko, Arie Bodek, R. N. Tilden, H. Ray, C. M. Hoffman, and B. Pollock
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,010308 nuclear & particles physics ,business.industry ,Detector ,Electrical engineering ,FOS: Physical sciences ,General Physics and Astronomy ,Astronomy and Astrophysics ,Data rate ,01 natural sciences ,Communication with submarines ,NuMI ,High Energy Physics - Experiment ,High Energy Physics - Experiment (hep-ex) ,0103 physical sciences ,Bit error rate ,Interstellar communication ,Physics::Accelerator Physics ,High Energy Physics::Experiment ,Fermilab ,Neutrino ,010306 general physics ,business - Abstract
Beams of neutrinos have been proposed as a vehicle for communications under unusual circumstances, such as direct point-to-point global communication, communication with submarines, secure communications and interstellar communication. We report on the performance of a low-rate communications link established using the NuMI beam line and the MINERvA detector at Fermilab. The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth., 10 pages, 7 figures, updated with final figures used in Modern Physics Letters A publication
- Published
- 2012
33. Spectrum and Morphology of the Two Brightest Milagro Sources in the Cygnus Region: MGRO J2019+37 and MGRO J2031+41
- Author
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A. A. Abdo, U. Abeysekara, B. T. Allen, T. Aune, D. Berley, E. Bonamente, G. E. Christopher, T. DeYoung, B. L. Dingus, R. W. Ellsworth, J. G. Galbraith-Frew, M. M. Gonzalez, J. A. Goodman, C. M. Hoffman, P. H. Hüntemeyer, C. M. Hui, B. E. Kolterman, J. T. Linnemann, J. E. McEnery, A. I. Mincer, T. Morgan, P. Nemethy, J. Pretz, J. M. Ryan, P. M. Saz Parkinson, A. Shoup, G. Sinnis, A. J. Smith, V. Vasileiou, G. P. Walker, D. A. Williams, and G. B. Yodh
- Subjects
Nuclear and High Energy Physics ,Photon ,acceleration of particles ,astroparticle physics ,gamma rays: general ,open clusters and associations: individual (Cyg OB1, Cyg OB2) ,pulsars: general ,Space and Planetary Science ,Astronomy and Astrophysics ,Astrophysics::High Energy Astrophysical Phenomena ,Flux ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,7. Clean energy ,Power law ,0103 physical sciences ,Cutoff ,010303 astronomy & astrophysics ,Cyg OB2) ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Spectral index ,010308 nuclear & particles physics ,open clusters and associations: individual (Cyg OB1 ,Astrophysics - Astrophysics of Galaxies ,Air shower ,Astrophysics of Galaxies (astro-ph.GA) ,Milagro ,Astrophysics - High Energy Astrophysical Phenomena ,Energy (signal processing) - Abstract
The Cygnus region is a very bright and complex portion of the TeV sky, host to unidentified sources and a diffuse excess with respect to conventional cosmic-ray propagation models. Two of the brightest TeV sources, MGRO J2019+37 and MGRO J2031+41, are analyzed using Milagro data with a new technique, and their emission is tested under two different spectral assumptions: a power law and a power law with an exponential cutoff. The new analysis technique is based on an energy estimator that uses the fraction of photomultiplier tubes in the observatory that detect the extensive air shower. The photon spectrum is measured in the range 1 to 200 TeV using the last 3 years of Milagro data (2005-2008), with the detector in its final configuration. MGRO J2019+37 is detected with a significance of 12.3 standard deviations ($\sigma$), and is better fit by a power law with an exponential cutoff than by a simple power law, with a probability $>98$% (F-test). The best-fitting parameters for the power law with exponential cutoff model are a normalization at 10 TeV of $7^{+5}_{-2}\times10^{-10}$ $\mathrm{s^{-1}\: m^{-2}\: TeV^{-1}}$, a spectral index of $2.0^{+0.5}_{-1.0}$ and a cutoff energy of $29^{+50}_{-16}$ TeV. MGRO J2031+41 is detected with a significance of 7.3$\sigma$, with no evidence of a cutoff. The best-fitting parameters for a power law are a normalization of $2.4^{+0.6}_{-0.5}\times10^{-10}$ $\mathrm{s^{-1}\: m^{-2}\: TeV^{-1}}$ and a spectral index of $3.08^{+0.19}_{-0.17}$. The overall flux is subject to an $\sim$30% systematic uncertainty. The systematic uncertainty on the power law indices is $\sim$0.1. A comparison with previous results from TeV J2032+4130, MGRO J2031+41 and MGRO J2019+37 is also presented., Comment: 11 pages, 10 figures
- Published
- 2012
34. Analysis of the breeding progress of sugar beet
- Author
-
J. Loel, C. M. Hoffman, C. Kenter, and B. Maerlaender
- Subjects
Horticulture ,chemistry.chemical_compound ,chemistry ,Agronomy ,Chlorophyll ,Crop yield ,Crop quality ,Assimilation (biology) ,Cultivar ,Plant breeding ,Biology ,Photosynthesis - Published
- 2011
35. New limit on the rate-density of evaporating black holes
- Author
-
D. D. Weeks, David A. Williams, G. M. Dion, C. Y. Chang, Mike Stark, M. L. Chen, C. Dion, A. L. Shoup, R. L. Burman, J. P. Wu, G. E. Allen, W. Zhang, J. A. Goodman, S. R. Klein, P. Chumney, C. M. Hoffman, T. J. Haines, S. D. Biller, D. E. Dorfan, M. Cavalli-Sforza, G. B. Yodh, D. M. Schmidt, D. G. Coyne, R. Schnee, C. Sinnis, D. E. Nagle, D. Berley, Luke Zoltan Kelley, T. Yang, M. Harmon, D. E. Alexandreas, and R. W. Ellsworth
- Subjects
Black hole ,Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,Orders of magnitude (length) ,General Physics and Astronomy ,Astrophysics ,Emission spectrum ,Gamma-ray burst ,Energy source ,Upper and lower bounds ,Spectral line - Abstract
Data taken with the CYGNUS detector between 1989 September and 1993 January have been used to search for 1 s bursts of ultrahigh-energy gamma rays from point sources at arbitrary locations in the northern sky. We find no evidence for such bursts. We set a theory-dependent upper limit on the rate-density of evaporating black holes of 8.5\ifmmode\times\else\texttimes\fi{}${10}^{5}$ ${\mathrm{pc}}^{\mathrm{\ensuremath{-}}3}$ ${\mathrm{yr}}^{\mathrm{\ensuremath{-}}1}$ at the 99% C.L. When the same emission spectrum is used to recalculate previous upper limits based on direct searches, this limit is the most restrictive by nearly 2 orders of magnitude.
- Published
- 1993
36. Point source search techniques in ultra high energy gamma ray astronomy
- Author
-
D. Berley, C. Sinnis, G. B. Yodh, G. M. Dion, J. A. Goodman, D. E. Alexandreas, T. J. Haines, S. D. Biller, X. Q. Lu, E. Horch, W. Zhang, and C. M. Hoffman
- Subjects
Physics ,Nuclear and High Energy Physics ,Photon ,Point source ,Astrophysics::High Energy Astrophysical Phenomena ,Ultra-high-energy gamma ray ,Gamma ray ,Astronomy ,Cosmic ray ,Astrophysics ,Electromagnetic radiation ,Particle detector ,Instrumentation ,Background radiation - Abstract
Searches for point astrophysical sources of ultra high energy (UHE) gamma rays are plagued by large numbers of background events from isotropic cosmic rays. Some of the methods that have been used to estimate the expected number of background events coming from the direction of a possible source are found to contain biases. Search techniques that avoid this problem are described. There is also a discussion of how to optimize the sensitivity of a search to emission from a point source.
- Published
- 1993
37. Publisher’s Note: Indications of Proton-Dominated Cosmic-Ray Composition above 1.6 EeV [Phys. Rev. Lett.104, 161101 (2010)]
- Author
-
John Belz, Dmitri Ivanov, M. M. Maestas, L. J. Marek, D. R. Bergman, W. Deng, G. W. Burt, A. O’Neill, Rasha Abbasi, Gareth Hughes, J. P. Lundquist, Naruo Sasaki, K. Martens, Tareq Abu-Zayyad, M. A. Kirn, Steve Schnetzer, Dale Tupa, Samuel Blake, L. Perera, J. Liu, M. Allen, A. Zech, William Hanlon, John N. Matthews, S. R. Stratton, L. M. Scott, N. Manago, Ben Stokes, Gordon Thomson, B. F. Jones, J. A.J. Matthews, G. Archbold, J. F. Amman, Konstantin Belov, J. D. Smith, E. C. Loh, C. Song, Xiang Zhang, M. D. Roberts, C. A. Painter, Z. Cao, Kevin Reil, J. R. Thomas, S. A. Moore, Michael H. Holzscheiter, Ross Anderson, Pierre Sokolsky, M. Al-Seady, R. W. Springer, C. M. Hoffman, G. Sinnis, R. Riehle, Y. Fedorova, C. C. H. Jui, D. C. Rodriguez, S. B. Thomas, K. Kim, C. Cannon, O. A. Brusova, P. Hüntemeyer, C. B. Finley, and R. C. Gray
- Subjects
Physics ,Nuclear physics ,Proton ,General Physics and Astronomy ,Cosmic ray ,Astrophysics - Published
- 2010
38. Analysis of large-scale anisotropy of ultra-high energy cosmic rays in HiRes data
- Author
-
B. F. Jones, James F. Amann, Dale Tupa, P. Tinyakov, Kevin Reil, Konstantin Belov, R. Riehle, C. Cannon, J. Findlay, John Belz, William Hanlon, K. Kim, O. A. Brusova, P. Hüntemeyer, Hylke B. J. Koers, R. W. Springer, K. Martens, Lawrence Wiencke, M. Sasaki, M. M. Maestas, Steve Schnetzer, Gordon Thomson, Michael H. Holzscheiter, Dmitri Ivanov, L. J. Marek, G. W. Burt, Rasha Abbasi, J. D. Smith, Gareth Hughes, Tareq Abu-Zayyad, C. B. Finley, A. Zech, Douglas Bergman, Ben Stokes, L. M. Scott, R. C. Gray, N. Manago, Pierre Sokolsky, Xiang Zhang, D. C. Rodriguez, C. Song, Gus Sinnis, L. Perera, M. Allen, G. Archbold, S. R. Stratton, A. O’Neill, J. R. Thomas, M. D. Roberts, C. M. Hoffman, Y. Fedorova, W. Deng, John N. Matthews, C. A. Painter, Z. Cao, S. A. Moore, C. C. H. Jui, S. B. Thomas, M. A. Kirn, John Matthews, Samuel Blake, and E. C. Loh
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Isotropy ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,01 natural sciences ,Universe ,Space and Planetary Science ,TRACER ,0103 physical sciences ,ddc:520 ,Ultra-high-energy cosmic ray ,Astrophysics - High Energy Astrophysical Phenomena ,010306 general physics ,Anisotropy ,010303 astronomy & astrophysics ,media_common ,Free parameter - Abstract
Stereo data collected by the HiRes experiment over a six year period are examined for large-scale anisotropy related to the inhomogeneous distribution of matter in the nearby Universe. We consider the generic case of small cosmic-ray deflections and a large number of sources tracing the matter distribution. In this matter tracer model the expected cosmic ray flux depends essentially on a single free parameter, the typical deflection angle theta. We find that the HiRes data with threshold energies of 40 EeV and 57 EeV are incompatible with the matter tracer model at a 95% confidence level unless theta is larger than 10 degrees and are compatible with an isotropic flux. The data set above 10 EeV is compatible with both the matter tracer model and an isotropic flux., 9 pages, 5 Postscript figures
- Published
- 2010
39. The CYGNUS extensive air-shower experiment
- Author
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C. Sinnis, R. Cady, W. Zhang, P.R. Vishwanath, T. N. Thompson, M. Potter, V. D. Sandberg, C.A. Wilkinson, Todd Haines, G. B. Yodh, D. E. Alexandreas, S. D. Biller, R. L. Burman, C. Y. Chang, R. W. Ellsworth, D. E. Nagle, J. A. Goodman, Brenda Dingus, X. Q. Lu, R. L. Talaga, K. B. Butterfield, J. Lloyd-Evans, R. S. Delay, R. C. Allen, G. M. Dion, S. Stanislaus, C. M. Hoffman, S. Gupta, M. J. Stark, D. A. Krakauer, and D. Berley
- Subjects
Physics ,Nuclear and High Energy Physics ,Data processing ,Plastic scintillation detector ,business.industry ,Astrophysics ,Data acquisition ,Air shower ,Data analysis ,Proton spectra ,Cosmic muons ,Aerospace engineering ,business ,Instrumentation - Abstract
The CYGNUS extensive air-shower experiment is described. The design criteria, construction and operation details, and performance characteristics are presented. A discussion of the data analysis techniques is given. Finally, several enhancements and improvements in the apparatus are described.
- Published
- 1992
40. Measurement of the Flux of Ultra High Energy Cosmic Rays by the Stereo Technique
- Author
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B. F. Jones, M. A. Kirn, C. Cannon, O. A. Brusova, Gordon Thomson, P. Hüntemeyer, James F. Amann, W. Deng, B. K. Zhang, C. B. Finley, Michael H. Holzscheiter, R. Riehle, S. A. Blake, Steve Schnetzer, K. Martens, A. Zech, G. Sinnis, John Matthews, R. C. Gray, C. M. Hoffman, Y. Fedorova, J. D. Smith, R. W. Springer, D. Rodriguez, R. Snow, S. R. Stratton, Gareth Hughes, John N. Matthews, Tareq Abu-Zayyad, Dmitri Ivanov, K. Kim, G. Archbold, Z. Cao, Kevin Reil, S. A. Moore, Dale Tupa, L. M. Scott, E. C. Loh, L. Perera, Konstantin Belov, C. C. H. Jui, M. M. Maestas, S. B. Thomas, B. T. Stokes, J. R. Thomas, M. Al-Seady, Y. Zhang, Pierre Sokolsky, A. O’Neill, G. W. Burt, Lawrence Wiencke, M. Sasaki, J. Findlay, John Belz, M. D. Roberts, L. J. Marek, Douglas Bergman, C. A. Painter, William Hanlon, Rasha Abbasi, N. Manago, Xiang Zhang, and M. Allen
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Flux ,High resolution ,Stereoscopy ,Cosmic ray ,01 natural sciences ,law.invention ,Optics ,law ,0103 physical sciences ,Ultra-high-energy cosmic ray ,Ultrahigh energy ,010303 astronomy & astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Monocular ,010308 nuclear & particles physics ,business.industry ,Detector ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,business ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The High Resolution Fly's Eye experiment has measured the flux of ultrahigh energy cosmic rays using the stereoscopic air fluorescence technique. The HiRes experiment consists of two detectors that observe cosmic ray showers via the fluorescence light they emit. HiRes data can be analyzed in monocular mode, where each detector is treated separately, or in stereoscopic mode where they are considered together. Using the monocular mode the HiRes collaboration measured the cosmic ray spectrum and made the first observation of the Greisen-Zatsepin-Kuzmin cutoff. In this paper we present the cosmic ray spectrum measured by the stereoscopic technique. Good agreement is found with the monocular spectrum in all details., 20 pages, 10 figures
- Published
- 2009
41. Indications of Proton-Dominated Cosmic Ray Composition above 1.6 EeV
- Author
-
R U, Abbasi, T, Abu-Zayyad, M, Al-Seady, M, Allen, J F, Amman, R J, Anderson, G, Archbold, K, Belov, J W, Belz, D R, Bergman, S A, Blake, O A, Brusova, G W, Burt, C, Cannon, Z, Cao, W, Deng, Y, Fedorova, C B, Finley, R C, Gray, W F, Hanlon, C M, Hoffman, M H, Holzscheiter, D, Ivanov, G, Hughes, P, Hüntemeyer, B F, Jones, C C H, Jui, K, Kim, M A, Kirn, E C, Loh, J, Liu, J P, Lundquist, M M, Maestas, N, Manago, L J, Marek, K, Martens, J A J, Matthews, J N, Matthews, S A, Moore, A, O'Neill, C A, Painter, L, Perera, K, Reil, R, Riehle, M, Roberts, D, Rodriguez, N, Sasaki, S R, Schnetzer, L M, Scott, G, Sinnis, J D, Smith, P, Sokolsky, C, Song, R W, Springer, B T, Stokes, S, Stratton, S B, Thomas, J R, Thomas, G B, Thomson, D, Tupa, A, Zech, and X, Zhang
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Proton ,Astrophysics::High Energy Astrophysical Phenomena ,Hadron ,Astrophysics::Instrumentation and Methods for Astrophysics ,General Physics and Astronomy ,FOS: Physical sciences ,Cosmic ray ,Astrophysics ,Composition (combinatorics) ,Energy spectrum ,ddc:550 ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report studies of ultra-high energy cosmic ray composition via analysis of depth of airshower maximum (Xmax), for airshower events collected by the High Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d/d(log(E)) of 47.9 +- 6.0 (stat.) +- 3.2 (syst.)g/cm^2/decade for energies between 1.6 EeV and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum "ankle' at 4 EeV., Comment: 11 pages, 4 figures, accepted for publication in Physical Review Letters
- Published
- 2009
- Full Text
- View/download PDF
42. Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
- Author
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James M. Ryan, Peter Nemethy, R. Fleysher, C. M. Hoffman, E. Blaufuss, J. Pretz, P. M. Saz Parkinson, A. Shoup, G. P. Walker, L. Fleysher, R. W. Ellsworth, C. P. Lansdell, G. B. Yodh, B. E. Kolterman, A. A. Abdo, Benjamin William Allen, G. Sinnis, Maria Magdalena González, Julie McEnery, C. Chen, David A. Williams, D. Berley, P. H. Hüntemeyer, D. Noyes, Allen Mincer, A. J. Smith, J. T. Linnemann, Sabrina Casanova, T. Aune, J. A. Goodman, V. Vasileiou, Brenda Dingus, and G. W. Sullivan
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Hadron ,FOS: Physical sciences ,General Physics and Astronomy ,Sigma ,Flux ,Cosmic ray ,Astrophysics ,01 natural sciences ,Observatory ,0103 physical sciences ,Scale structure ,Milagro ,Ultra-high-energy cosmic ray ,010303 astronomy & astrophysics - Abstract
An analysis of 7 years of Milagro data performed on a 10-degree angular scale has found two localized regions of excess of unknown origin with greater than 12 sigma significance. Both regions are inconsistent with gamma-ray emission with high confidence. One of the regions has a different energy spectrum than the isotropic cosmic-ray flux at a level of 4.6 sigma, and it is consistent with hard spectrum protons with an exponential cutoff, with the most significant excess at ~10 TeV. Potential causes of these excesses are explored, but no compelling explanations are found., Submitted to PhysRevLett
- Published
- 2008
43. A Measurement of the Spatial Distribution of Diffuse TeV Gamma Ray Emission from the Galactic Plane with Milagro
- Author
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G. Sinnis, C. Chen, D. Berley, Peter Nemethy, R. Fleysher, V. Vasileiou, C. M. Hoffman, Julie McEnery, L. Fleysher, T. Aune, Igor V. Moskalenko, James M. Ryan, G. W. Sullivan, A. A. Abdo, P. M. Saz Parkinson, G. P. Walker, R. W. Ellsworth, Andrew W. Strong, C. P. Lansdell, A. J. S. Smith, B. E. Kolterman, Benjamin William Allen, P. H. H\\'untemeyer, E. Blaufuss, J. T. Linnemann, D. Noyes, Brenda Dingus, T. A. Porter, Sabrina Casanova, A. L. Shoup, J. A. Goodman, J. Pretz, Allen Mincer, G. B. Yodh, Maria Magdalena González, and David A. Williams
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Gamma ray ,FOS: Physical sciences ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Galactic plane ,7. Clean energy ,01 natural sciences ,Galaxy ,Interstellar medium ,Pion ,13. Climate action ,Space and Planetary Science ,Observatory ,0103 physical sciences ,Milagro ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
Diffuse $\gamma$-ray emission produced by the interaction of cosmic-ray particles with matter and radiation in the Galaxy can be used to probe the distribution of cosmic rays and their sources in different regions of the Galaxy. With its large field of view and long observation time, the Milagro Gamma Ray Observatory is an ideal instrument for surveying large regions of the Northern Hemisphere sky and for detecting diffuse $\gamma$-ray emission at very high energies. Here, the spatial distribution and the flux of the diffuse $\gamma$-ray emission in the TeV energy range with a median energy of 15 TeV for Galactic longitudes between 30$^\circ$ and 110$^\circ$ and between 136$^\circ$ and 216$^\circ$ and for Galactic latitudes between -10$^\circ$ and 10$^\circ$ are determined. The measured fluxes are consistent with predictions of the GALPROP model everywhere except for the Cygnus region ($l\in[65^\circ,85^\circ]$). For the Cygnus region, the flux is twice the predicted value. This excess can be explained by the presence of active cosmic ray sources accelerating hadrons which interact with the local dense interstellar medium and produce gamma rays through pion decay., Comment: 15 pages, 3 figures, accepted by ApJ
- Published
- 2008
44. An upper limit on the electron-neutrino flux from the HiRes detector
- Author
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S. Y. Ben Zvi, M. Allen, B. F. Jones, J. Findlay, John Belz, R. C. Gray, Konstantin Belov, N. Manago, R. Riehle, J. D. Smith, Dmitri Ivanov, L. Perera, Ben Stokes, R. W. Springer, L. J. Marek, E. C. Loh, Douglas Bergman, L. M. Scott, G. Archbold, C. A. Painter, Xiang Zhang, P. Huentemeyer, J. R. Thomas, M. D. Roberts, J. H. Boyer, E. J. Mannel, C. Cannon, S. R. Stratton, Kevin Reil, O. A. Brusova, Z. Cao, C. M. Hoffman, A. O’Neill, Samuel Blake, G. W. Burt, C. B. Finley, S. A. Moore, K. Martens, Gareth Hughes, Pierre Sokolsky, Y. Fedorova, D. C. Rodriguez, John Matthews, Tareq Abu-Zayyad, Steve Schnetzer, William Hanlon, Rasha Abbasi, G. Sinnis, M. A. Kirn, C. Song, A. Zech, B. C. Knapp, M. M. Maestas, M. Seman, W. Deng, Lawrence Wiencke, James F. Amann, M. Sasaki, C. C. H. Jui, S. B. Thomas, John N. Matthews, Dale Tupa, R. Snow, K. Kim, A. Biesiadecka, Gordon Thomson, and Michael H. Holzscheiter
- Subjects
Physics ,010308 nuclear & particles physics ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,Monte Carlo method ,Detector ,Astrophysics (astro-ph) ,Bremsstrahlung ,Flux ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,7. Clean energy ,Charged particle ,Nuclear physics ,Pair production ,13. Climate action ,Space and Planetary Science ,0103 physical sciences ,High Energy Physics::Experiment ,Neutrino ,010306 general physics ,Electron neutrino - Abstract
Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy electron-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron-neutrino-induced cascades and present an upper limit on the flux of electron-neutrinos., Comment: 13 pages, 3 figures. submitted to Astrophysical Journal
- Published
- 2008
- Full Text
- View/download PDF
45. Measurement of proton induced radiation damage to CMOS transistors and p-i-n diodes
- Author
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C. Milner, Nicolo Cartiglia, A. Kaluzniacki, Paolo Giubellino, D. Pitzl, P. Tenenbaum, W. W. Kinnison, C. M. Hoffman, W.A. Rowe, J. Bacigalupi, David B. Holtkamp, Walter F. Sommer, J. DeWitt, E. Spencer, Hans Ziock, H. F.W. Sadrozinski, Phillip D. Ferguson, S M Sartori, and Hermann Kolanoski
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Physics ,Nuclear and High Energy Physics ,Physics::Instrumentation and Detectors ,business.industry ,Biasing ,Semiconductor device ,Threshold voltage ,Computer Science::Hardware Architecture ,Computer Science::Emerging Technologies ,Nuclear Energy and Engineering ,CMOS ,Physics::Accelerator Physics ,Optoelectronics ,Field-effect transistor ,Electrical and Electronic Engineering ,business ,Radiation hardening ,Electronic circuit ,Diode - Abstract
As part of a program to develop a silicon tracking device for the Superconducting Super Collider (SSC), radiation-hard CMOS transistors and p-i-n diodes have been exposed to the 800-MeV LAMPF (Los Alamos Meson Physics Facility) proton beam. The fluences accumulated in one week corresponded to the expected radiation levels of about ten SSC years. The leakage current constants for p-i-n diodes and threshold voltage shifts for CMOS transistors are determined under different biasing conditions. The results are presented and examined in detail. >
- Published
- 1990
46. Milagro Constraints on Very High Energy Emission from Short Duration Gamma-Ray Bursts
- Author
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James M. Ryan, R. W. Ellsworth, C. P. Lansdell, E. Hays, A. J. Smith, E. Blaufuss, D. Berley, G. Sinnis, V. Vasileiou, A. A. Abdo, C. M. Hoffman, G. W. Sullivan, X. W. Xu, D. A. Williams, P. M. Saz Parkinson, G. P. Walker, G. B. Yodh, B. T. Allen, Frank W. Samuelson, J. E. McEnery, Brenda Dingus, J. T. Linnemann, J. A. Goodman, D. Noyes, B. E. Kolterman, Peter Nemethy, Sabrina Casanova, M. M. Gonzalez, A. L. Shoup, and Allen Mincer
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Gamma ray ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Galaxy ,Redshift ,Extragalactic background light ,Space and Planetary Science ,0103 physical sciences ,Milagro ,Gamma-ray burst ,Absorption (electromagnetic radiation) ,010303 astronomy & astrophysics ,Short duration - Abstract
Recent rapid localizations of short, hard gamma-ray bursts (GRBs) by the Swift and HETE satellites have led to the observation of the first afterglows and the measurement of the first redshifts from this type of burst. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Seventeen short duration (< 5 s) GRBs detected by satellites occurred within the field of view of the Milagro gamma-ray observatory between 2000 January and 2006 December. We have searched the Milagro data for >100 GeV counterparts to these GRBs and find no significant emission correlated with these bursts. Due to the absorption of high-energy gamma rays by the extragalactic background light (EBL), detections are only expected for redshifts less than ~0.5. While most long duration GRBs occur at redshifts higher than 0.5, the opposite is thought to be true of short GRBs. Lack of a detected VHE signal thus allows setting meaningful fluence limits. One GRB in the sample (050509b) has a likely association with a galaxy at a redshift of 0.225, while another (051103) has been tentatively linked to the nearby galaxy M81. Fluence limits are corrected for EBL absorption, either using the known measured redshift, or computing the corresponding absorption for a redshift of 0.1 and 0.5, as well as for the case of z=0., Accepted for publication in the Astrophysical Journal
- Published
- 2007
47. Alternative Methods to Finding Patterns in HiRes Stereo Data
- Author
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R. W. Springer, L. M. Scott, Kevin Reil, Segev BenZvi, Dale Tupa, J. D. Smith, G. Archbold, Konstantin Belov, Pierre Sokolsky, M. A. Kirn, L. Perera, G. W. Burt, C. A. Painter, A. Zech, N. Manago, Gareth Hughes, Douglas Bergman, Tareq Abu-Zayyad, B. F. Jones, M. Seman, D. Rodriguez, Steve Schnetzer, J. A.J. Matthews, S. Westerhoff, Xiang Zhang, K. Kim, J. Findlay, John Belz, C. Song, B. C. Knapp, L. J. Marek, M. Sasaki, B.M. Connolly, L.R. Weincke, E. J. Mannel, R. Riehle, C. B. Finley, R. C. Gray, P. Hüntemeyer, William Hanlon, A. O’Neill, M. M. Maestas, Rasha Abbasi, Gordon Thomson, K. Martins, Z. Cao, Michael H. Holzscheiter, S. A. Moore, C. C. H. Jui, S. B. Thomas, B. T. Stokes, J. R. Thomas, E. C. Loh, J. H. Boyer, W. Deng, J. F. Amman, John N. Matthews, S. A. Blake, M. D. Roberts, C. M. Hoffman, G. Sinnis, and Y. Fedorova
- Subjects
Physics ,media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,01 natural sciences ,Galaxy ,Hough transform ,law.invention ,Great circle ,Arc (geometry) ,law ,Sky ,0103 physical sciences ,010306 general physics ,Anisotropy ,010303 astronomy & astrophysics ,Energy (signal processing) ,media_common - Abstract
In this paper ultra-high energy cosmic rays UHECRs data observed by the HiRes fluorescence detector in stereo mode is analyzed to search for events in the sky with an arrival direction lying on a great circle. Such structure is known as the arc structure. The arc structure is expected when the charged cosmic rays pass through the galactic magnetic field. The arcs searched for could represent a broad or a small scale anisotropy depending on the proposed source model for the UHECRs. The arcs in this paper are looked for using Hough transform were Hough transform is a technique used to looking for patterns in images. No statistically significant arcs were found in this study.
- Published
- 2007
48. First Observation of the Greisen-Zatsepin-Kuzmin Suppression
- Author
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R. W. Springer, Steve Schnetzer, B. T. Stokes, J. R. Thomas, N. Manago, John N. Matthews, Gordon Thomson, Kevin Reil, Douglas Bergman, Konstantin Belov, Michael H. Holzscheiter, Xiang Zhang, Naruo Sasaki, A. O’Neill, W. Deng, L. M. Scott, S. A. Blake, John Matthews, M. D. Roberts, Z. Cao, B. C. Connolly, C. M. Hoffman, S. A. Moore, Y. Fedorova, J. F. Amman, John Belz, M. Allen, L. J. Marek, C. A. Painter, E. C. Loh, Gareth Hughes, G. Archbold, Tareq Abu-Zayyad, G. W. Burt, William Hanlon, Rasha Abbasi, C. C. H. Jui, R. Riehle, S. B. Thomas, Lawrence Wiencke, A. Zech, C. Song, Dale Tupa, M. A. Kirn, G. Sinnis, S. Y. Ben Zvi, J. D. Smith, R. C. Gray, D. Rodriguez, L. Perera, S. Westerhoff, K. Kim, B. F. Jones, C. Cannon, O. A. Brusova, P. Hüntemeyer, C. B. Finley, K. Martens, M. M. Maestas, and Pierre Sokolsky
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,General Physics and Astronomy ,High resolution ,FOS: Physical sciences ,Cosmic ray ,Astrophysics ,01 natural sciences ,0103 physical sciences ,Energy spectrum ,Cutoff ,Ultrahigh energy ,010303 astronomy & astrophysics ,Energy (signal processing) - Abstract
The High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement of the flux of ultrahigh energy (UHE) cosmic rays shows a sharp suppression at an energy of $6 \times 10^{19}$ eV, consistent with the expected cutoff energy. We observe the ``ankle'' of the cosmic-ray energy spectrum as well, at an energy of $4 \times 10^{18}$ eV. We describe the experiment, data collection, analysis, and estimate the systematic uncertainties. The results are presented and the calculation of the statistical significance of our observation is described., Comment: 4 pages, 3 figures, accepted by and to appear in PRL
- Published
- 2007
- Full Text
- View/download PDF
49. TeV Gamma-Ray Sources from a Survey of the Galactic Plane with Milagro
- Author
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A. A. Abdo, J. T. Linnemann, D. Noyes, B. Hopper, G. W. Sullivan, Peter Nemethy, A. J. Smith, David A. Williams, James M. Ryan, G. Sinnis, Sabrina Casanova, X. W. Xu, B. E. Kolterman, J. A. Goodman, R. W. Ellsworth, C. P. Lansdell, R. Fleysher, P. M. Saz Parkinson, P. H. Hüntemeyer, G. B. Yodh, G. P. Walker, Benjamin William Allen, A. L. Shoup, E. Hays, D. G. Coyne, Allen Mincer, L. Fleysher, Brenda Dingus, M. M. Gonzalez, V. Vasileiou, C. Chen, J. E. McEnery, D. Berley, and C. M. Hoffman
- Subjects
Physics ,biology ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Gamma ray ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Galactic plane ,biology.organism_classification ,01 natural sciences ,Galaxy ,Crab Nebula ,Space and Planetary Science ,Observatory ,0103 physical sciences ,Milagro ,Egret ,Longitude ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
A survey of Galactic gamma-ray sources at a median energy of ~20 TeV has been performed using the Milagro Gamma Ray Observatory. Eight candidate sources of TeV emission are detected with pre-trials significance $>4.5\sigma$ in the region of Galactic longitude $l\in[30^\circ,220^\circ]$ and latitude $b\in[-10^\circ,10^\circ]$. Four of these sources, including the Crab nebula and the recently published MGRO J2019+37, are observed with significances $>4\sigma$ after accounting for the trials involved in searching the 3800 square degree region. All four of these sources are also coincident with EGRET sources. Two of the lower significance sources are coincident with EGRET sources and one of these sources is Geminga. The other two candidates are in the Cygnus region of the Galaxy. Several of the sources appear to be spatially extended. The fluxes of the sources at 20 TeV range from ~25% of the Crab flux to nearly as bright as the Crab., Comment: Submitted to ApJ
- Published
- 2007
- Full Text
- View/download PDF
50. Maternal brooding in the children's python (Antaresia childreni) promotes egg water balance
- Author
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Olivier Lourdais, Ty C. M. Hoffman, and Dale F. DeNardo
- Subjects
Avian clutch size ,Physiology ,Offspring ,Zoology ,Biochemistry ,Endocrinology ,Antaresia childreni ,Animals ,Relative humidity ,Clutch ,Maternal Behavior ,reproductive and urinary physiology ,Ecology, Evolution, Behavior and Systematics ,Ovum ,Tissue Survival ,Facultative ,biology ,Ecology ,food and beverages ,Humidity ,Water ,biology.organism_classification ,Clutch Size ,Water Loss, Insensible ,Boidae ,embryonic structures ,behavior and behavior mechanisms ,Animal Science and Zoology ,Female ,Paternal care - Abstract
Parental care provides considerable benefits to offspring and is widespread among animals, yet it is relatively uncommon among squamate reptiles (e.g., lizards and snakes). However, all pythonine snakes show extended maternal egg brooding with some species being facultatively endothermic. While facultative endothermy provides thermal benefits, the presence of brooding in non-endothermic species suggests other potential benefits of brooding. In this study we experimentally tested the functional significance of maternal brooding relative to water balance in the children's python, Antaresia childreni, a small species that does not exhibit facultative endothermy. Clutch evaporative water loss (EWL) was positively correlated with clutch mass and was much lower than expected values based on individual eggs. The conglomerate clutch behaved as a single unit with a decreasing surface area to volume ratio as clutch size increased. Maternal brooding had a dramatic impact on evaporation from eggs, reducing and possibly eliminating clutch EWL. In a separate experiment, we found that viability of unattended eggs is highly affected by humidity level, even in the narrow range from 75 to 100% relative humidity at 30.5 degrees C (20-33 mg m(-3 )absolute humidity). However, the presence of the brooding female ameliorated this sensitivity, as viability of brooded clutches at 75% relative humidity was higher than that of non-brooded eggs at either the same absolute humidity or at near-saturated conditions. Overall, these results demonstrate that brooding behavior strongly promotes egg water balance (and thus egg viability) in children's pythons.
- Published
- 2006
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