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2006

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Articles 3751 - 3780 of 5872

Full-Text Articles in Physical Sciences and Mathematics

Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu Jan 2006

Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu

Duane D. Johnson

We report ab initio density functional theory calculations of generalized planar fault energies of fcc Cu–xAl (x=0, 5.0, and 8.3at.%) alloys. We investigate the effects of substitutional solute Al on the unstable intrinsic γus and twin γutstacking faultenergies (SFEs). Our results reveal an increased tendency of Cu–Al to deform preferentially by twinning with increasing Al content, consistent with experiment. We attribute this mechanical behavior to appreciable lowering of the twinning barrier γut, along with the stable intrinsic and twin SFEs.

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A Molecular Salt Of Tricyanomethanide Anion And A N,N9- Dianisylphenazinium Dication: Cooperative Affects Of Methoxy…Methoxy And Cmn…N+ Intermolecular Contacts, Scott E. Mckay, Kraig A. Wheeler, Silas C. Blackstock Jan 2006

A Molecular Salt Of Tricyanomethanide Anion And A N,N9- Dianisylphenazinium Dication: Cooperative Affects Of Methoxy…Methoxy And Cmn…N+ Intermolecular Contacts, Scott E. Mckay, Kraig A. Wheeler, Silas C. Blackstock

Kraig A. Wheeler

A molecular salt of tricyanomethanide anion and a N,N9- dianisylphenazinium dication forms extended supramolecular assemblies that consist of unusual methoxy…methoxy and CMN…N+ intermolecular contacts.

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Electron Transport In Laterally Confined Phosphorus Δ-Layers In Silicon, S. J. Robinson, J. S. Kline, H. J. Wheelwright, J. R. Tucker, C. L. Yang, R. R. Du, B. E. Volland, I. W. Rangelow, T. -C. Shen Jan 2006

Electron Transport In Laterally Confined Phosphorus Δ-Layers In Silicon, S. J. Robinson, J. S. Kline, H. J. Wheelwright, J. R. Tucker, C. L. Yang, R. R. Du, B. E. Volland, I. W. Rangelow, T. -C. Shen

T. -C. Shen

Two-dimensional electron systems fabricated from a single layer of P-donors have been lithographically confined to nanometer scale in lateral directions. The electronic transport of such quasi-one-dimensional systems with and without a perpendicular magnetic field was characterized at cryogenic temperatures. Experimental data fit well with two-dimensional weak localization and interaction theory when the phase coherence length is shorter than the smaller dimension of the confinement. Below a transition temperature the wire conductance saturates.

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Supercam, As 64-Pixel Heterodyne Imaging Array For The 870 Micron Atmospheric Window, Christopher Groppi, Christopher Walker, Craig Kulesa, Patrick Putz, Dathon Golish, Paul Gensheimer, Abigail Hedden, Shane Bussmann, Sander Weinreb, Thomas Kuiper, Jacob Kooi, Glenn Jones, Joseph Bardin, Hamdi Mani, Arthur Lichtenberger, Gopal Narayanan Jan 2006

Supercam, As 64-Pixel Heterodyne Imaging Array For The 870 Micron Atmospheric Window, Christopher Groppi, Christopher Walker, Craig Kulesa, Patrick Putz, Dathon Golish, Paul Gensheimer, Abigail Hedden, Shane Bussmann, Sander Weinreb, Thomas Kuiper, Jacob Kooi, Glenn Jones, Joseph Bardin, Hamdi Mani, Arthur Lichtenberger, Gopal Narayanan

Gopal Narayanan

We report on the development of SuperCam , a 64 pixel, superheterodyne camera designed for operation in the astrophysically important 870 μm atmospheric window. SuperCam will be used to answer fundamental questions about the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation. The advent of such a system will provide an order of magnitude increase in mapping speed over what is now available and revolutionize how observational astronomy is performed in this important wavelength regime. Unlike the situation with bolometric detectors, heterodyne receiver systems are coherent, retaining information about both …

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Kinematics Of Protostellar Objects In The Ρ Ophiuchus A Region, Gopal Narayanan, Daniel W. Logan Jan 2006

Kinematics Of Protostellar Objects In The Ρ Ophiuchus A Region, Gopal Narayanan, Daniel W. Logan

Gopal Narayanan

We present the detection of infall, rotation, and outflow kinematic signatures toward both a protostellar source, VLA 1623, and what was initially thought to be a pre-protostellar core, SM 1N, in the ρ Ophiuchus A region. The kinematic signatures of early star formation were detected in the dense molecular gas surrounding the embedded sources using high signal-to-noise ratio millimeter and submillimeter data. Centroid velocity maps made with HCO+ J = 4 → 3 and J = 1 → 0 line emission exhibit the blue bulge signature of infall, which is predicted to be seen when infall motion dominates over rotational …

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X-Ray Selected Agn Hosts Are Similar To Inactive Galaxies Out To Z=3: Results From Candels/Cdf-S, D. J. Rosario, M. Mozena, S. Wuyts, K. Nandra, A. Koekemoer, E. Mcgrath, N. Hathi, A. Dekel, J. Donley, J. S. Dunlop, S. M. Faber, H. Ferguson, Mauro Giavalisco, N. Grogin, Y. Guo, J. Newman, D. D. Kocevski, D. C. Koo, R. Somerville Jan 2006

X-Ray Selected Agn Hosts Are Similar To Inactive Galaxies Out To Z=3: Results From Candels/Cdf-S, D. J. Rosario, M. Mozena, S. Wuyts, K. Nandra, A. Koekemoer, E. Mcgrath, N. Hathi, A. Dekel, J. Donley, J. S. Dunlop, S. M. Faber, H. Ferguson, Mauro Giavalisco, N. Grogin, Y. Guo, J. Newman, D. D. Kocevski, D. C. Koo, R. Somerville

Mauro Giavalisco

We use multi-band high-resolution photometry in the 4 MSec Chandra Deep Field-South (CDF-S), in particular imaging from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS), to explore the nuclear and extended colors, color gradients and stellar populations of X-ray selected AGN host galaxies out to z=3. Based on a study of their central light, we develop X-ray based criteria to exclude objects with strong AGN contamination. We use stellar masses from the FIREWORKS database to understand and account for stellar mass selection effects, and carefully study, for the first time, the resolved host galaxy properties of AGNs at z~2 in …

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Entrainment Mechanisms For Outlfows In The L1551 Star-Forming Region, Irena Stijimirovic, Gopal Narayanan, Ronald L. Snell Jan 2006

Entrainment Mechanisms For Outlfows In The L1551 Star-Forming Region, Irena Stijimirovic, Gopal Narayanan, Ronald L. Snell

Gopal Narayanan

We present high sensitivity 12CO and 13CO J = 1 → 0 maps covering the full extent of the parsec-scale L1551 molecular outflow, including the redshifted east-west (EW) flow. We also present 12CO J = 3 → 2 data obtained over a good fraction of the L1551 outflow. We compare the molecular data to wide-field, narrowband optical emission in Hα. While there are multiple outflows in the L1551 cloud, the main outflow is oriented at 50° position angle and appears to be driven by an embedded source(s) in the central IRS 5 region. The J = 3 → 2 data …

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Integrating Stakeholder Values With Multiple Attributes To Quantify Watershed Performance, Timothy O. Randhir, Deborah M. Shriver Jan 2006

Integrating Stakeholder Values With Multiple Attributes To Quantify Watershed Performance, Timothy O. Randhir, Deborah M. Shriver

Timothy O. Randhir

Integrating stakeholder values into the process of quantifying impairment of ecosystem functions is an important aspect of watershed assessment and planning. This study develops a classification and prioritization model to assess potential impairment in watersheds. A systematic evaluation of a broad set of abiotic, biotic, and human indicators of watershed structure and function was used to identify the level of degradation at a subbasin scale. Agencies and communities can use the method to effectively target and allocate resources to areas of greatest restoration need. The watershed performance measure (WPM) developed in this study is composed of three major components: (1) …

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Threats To Water Supplies In The Tropical Andes, Raymond S. Bradley, Mathias Vuille, Henry F. Diaz, Walter Vergara Jan 2006

Threats To Water Supplies In The Tropical Andes, Raymond S. Bradley, Mathias Vuille, Henry F. Diaz, Walter Vergara

Raymond S Bradley

Climate models predict that greenhouse warming will cause temperatures to rise faster at higher than at lower altitudes. In the tropical Andes, glaciers may soon disappear, with potentially grave consequences for water supplies.

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High Precision Measurement Of The Thermal Exponent For The Three-Dimensional Xy Universality Class, Evgeni Burovski, Jonathan Machta, Nikolay Prokof'ev, Boris Svitunov Jan 2006

High Precision Measurement Of The Thermal Exponent For The Three-Dimensional Xy Universality Class, Evgeni Burovski, Jonathan Machta, Nikolay Prokof'ev, Boris Svitunov

Jonathan Machta

Simulation results are reported for the critical point of the two-component ϕ4 field theory. The correlation-length exponent is measured to high precision with the result ν=0.6717(3). This value is in agreement with recent simulation results [Campostrini et al., Phys. Rev. B 63, 214503 (2001)] and marginally agrees with the most recent space-based measurements of the superfluid transition in He4 [Lipa et al., Phys. Rev. B 68, 174518 (2003)].

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Elliptic Phases: A Study Of The Nonlinear Elasticity Of Twist-Grain Boundaries, Christian Santangelo, Randall D. Kamien Jan 2006

Elliptic Phases: A Study Of The Nonlinear Elasticity Of Twist-Grain Boundaries, Christian Santangelo, Randall D. Kamien

Christian Santangelo

We develop an explicit and tractable representation of a twist-grain-boundary phase of a smectic-A liquid crystal. This allows us to calculate the interaction energy between grain boundaries and the relative contributions from the bending and compression deformations. We discuss the special stability of the π/2 grain boundaries and discuss the relation of this structure to the Schwarz D surface.

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Crossover States Of Vortex Matter In Trapped Bose Condensates, S. Kragset, Egor Babaev, A. Sudbo Jan 2006

Crossover States Of Vortex Matter In Trapped Bose Condensates, S. Kragset, Egor Babaev, A. Sudbo

Egor Babaev

We perform Monte Carlo studies of vortices in three dimensions in a cylindrical confinement, with uniform and nonuniform density. The former is relevant to rotating 4He, the latter is relevant to a rotating trapped Bose condensate. In the former case we find dominant angular thermal vortex fluctuations close to the cylinder wall. For the latter case, a novel effect is that at low temperatures the vortex solid close to the center of the trap crosses directly over to a tension-less vortex tangle near the edge of the trap. At higher temperatures an intermediate tension-full vortex liquid located between the vortex …

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Complexity, Parallel Computation And Statistical Physics, Jonathan Machta Jan 2006

Complexity, Parallel Computation And Statistical Physics, Jonathan Machta

Jonathan Machta

The intuition that a long history is required for the emergence of complexity in natural systems is formalized using the notion of depth. The depth of a system is defined in terms of the number of parallel computational steps needed to simulate it. Depth provides an objective, irreducible measure of history that is applicable to systems of the kind studied in statistical physics. It is argued that physical complexity cannot occur in the absence of substantial depth and that depth is a useful proxy for physical complexity. The ideas are illustrated for a variety of systems in statistical physics

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On 3+1 Dimensional Scalar Field Cosmologies, Panos Kevrekidis Jan 2006

On 3+1 Dimensional Scalar Field Cosmologies, Panos Kevrekidis

Panos Kevrekidis

In this communication, we analyze the case of 3+1 dimensional scalar field cosmologies in the presence, as well as in the absence of spatial curvature, in isotropic, as well as in anisotropic settings. Our results extend those of Hawkins and Lidsey [Phys. Rev. D {\bf 66}, 023523 (2002)], by including the non-flat case. The Ermakov-Pinney methodology is developed in a general form, allowing through the converse results presented herein to use it as a tool for constructing new solutions to the original equations. As an example of this type a special blowup solution recently obtained in Christodoulakis {\it et al.} …

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Ergodic Properties Of Markov Processes, L Rey-Bellet Jan 2006

Ergodic Properties Of Markov Processes, L Rey-Bellet

Luc Rey-Bellet

In these notes we discuss Markov processes, in particular stochastic differential equations (SDE) and develop some tools to analyze their long-time behavior. There are several ways to analyze such properties, and our point of view will be to use systematically Liapunov functions which allow a nice characterization of the ergodic properties. In this we follow, at least in spirit, the excellent book of Meyn and Tweedie [7]. In general a Liapunov function W is a positive function which grows at infinity and satisfies an inequality involving the generator of the Markov process L: roughly speaking we have the implications (α …

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Open Classical Systems, L Rey-Bellet Jan 2006

Open Classical Systems, L Rey-Bellet

Luc Rey-Bellet

Open systems are usually understood as a small Hamiltonian system (i.e. with a finite number of degrees of freedom) in contact with one or several large reservoirs. There are several ways to model reservoirs and we will take the point of view that the reservoirs are also Hamiltonian systems themselves. It is a convenient physical and mathematical idealization to separate scales and assume that the reservoirs have infinitely many degrees of freedom. We will also assume that, to start with, the reservoirs are in equilibrium, i.e., the initial states of the reservoirs are distributed according to Gibbs distribution with given …

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Parity-Violating Electron Scattering From ^4 He And The Strange Electric Form Factor Of The The Nucleon, K. A. Aniol, D. S. Armstrong, T. Averett, H. Benaoum, P. Y. Bertin, E. Burtin, J. Cahoon, G. D. Cates, C. C. Chang, Y. C. Chao, J. P. Chen, Seonho Choi, E. Chudakov, B. Craver, F. Cusanno, P. Decowsky, D. Deepa, C. Ferdi, R. J. Feuerbach, M. J. Finn, S. Frullani, K. Fuoti, F. Garibaldi, R. Gilman, A. Glamazdin, V. Gorbenko, J. M. Grames, J. Hansknecht, D. W. Higinbotham, R. Holmes, T. Holmstrom, T. B. Humensky, H. Ibrahim, C. W. De Jager, X. Jiang, L. J. Kaufman, A. Kelleher, A. Kolarkar, S. Kowalski, Krishna Kumar, D. Lambert, P. Laviolette, J. Lerose, D. Lhuillier, N. Liyanage, D. J. Margaziotis, M. Mazouz, K. Mccormick, D. G. Meekins, Z. E. Meziani, R. Michaels, B. Moffit, P. Monaghan, C. Munoz-Camacho, S. Nanda, V. Nelyubin, D. Neyret, K. D. Paschke, M. Poelker, R. Pomatsalyuk, Y. Qiang, B. Reitz, J. Roche, A. Saha, J. Singh, R. Snyder, P. A. Souder, R. Subedi, R. Suleiman, V. Sulkosky, W. A. Tobias, G. M. Urciuoli, A. Vacheret, E. Voutier, K. Wang, R. Wilson, B. Wojtsekhowski, X. Zheng Jan 2006

Parity-Violating Electron Scattering From ^4 He And The Strange Electric Form Factor Of The The Nucleon, K. A. Aniol, D. S. Armstrong, T. Averett, H. Benaoum, P. Y. Bertin, E. Burtin, J. Cahoon, G. D. Cates, C. C. Chang, Y. C. Chao, J. P. Chen, Seonho Choi, E. Chudakov, B. Craver, F. Cusanno, P. Decowsky, D. Deepa, C. Ferdi, R. J. Feuerbach, M. J. Finn, S. Frullani, K. Fuoti, F. Garibaldi, R. Gilman, A. Glamazdin, V. Gorbenko, J. M. Grames, J. Hansknecht, D. W. Higinbotham, R. Holmes, T. Holmstrom, T. B. Humensky, H. Ibrahim, C. W. De Jager, X. Jiang, L. J. Kaufman, A. Kelleher, A. Kolarkar, S. Kowalski, Krishna Kumar, D. Lambert, P. Laviolette, J. Lerose, D. Lhuillier, N. Liyanage, D. J. Margaziotis, M. Mazouz, K. Mccormick, D. G. Meekins, Z. E. Meziani, R. Michaels, B. Moffit, P. Monaghan, C. Munoz-Camacho, S. Nanda, V. Nelyubin, D. Neyret, K. D. Paschke, M. Poelker, R. Pomatsalyuk, Y. Qiang, B. Reitz, J. Roche, A. Saha, J. Singh, R. Snyder, P. A. Souder, R. Subedi, R. Suleiman, V. Sulkosky, W. A. Tobias, G. M. Urciuoli, A. Vacheret, E. Voutier, K. Wang, R. Wilson, B. Wojtsekhowski, X. Zheng

Krishna Kumar

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q2 = 0.091 GeV2 . From these data, for the first time, the strange electric form factor of the nucleon G(E)s can be isolated. The measured asymmetry of A(PV) = (6.72 +/- 0.84(stat) +/- 0.21(syst) x 10(-6) yields a value of G(E)s = -0.038 +/- 0.042(stat) +/- 0.010(syst), consistent with zero.

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Numerical Study Of The Random Field Ising Model At Zero And Positive Temperature, Yong Wu, Jonathan Machta Jan 2006

Numerical Study Of The Random Field Ising Model At Zero And Positive Temperature, Yong Wu, Jonathan Machta

Jonathan Machta

In this paper the three-dimensional random-field Ising model is studied at both zero temperature and positive temperature. Critical exponents are extracted at zero temperature by finite size scaling analysis of large discontinuities in the bond energy. The heat capacity exponent α is found to be near zero. The ground states are determined for a range of external field and disorder strength near the zero temperature critical point and the scaling of ground state tilings of the field-disorder plane is discussed. At positive temperature the specific heat and the susceptibility are obtained using the Wang-Landau algorithm. It is found that sharp …

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Computing Counterion Densities At Intermediate Coupling, Christian Santangelo Jan 2006

Computing Counterion Densities At Intermediate Coupling, Christian Santangelo

Christian Santangelo

By decomposing the Coulomb interaction into a long-distance component appropriate for mean-field theory, and a non-mean-field short distance component, we compute the counterion density near a charged surface for all values of the counterion coupling parameter. A modified strong-coupling expansion that is manifestly finite at all coupling strengths is used to treat the short-distance component. We find a nonperturbative correction related to the lateral counterion correlations that modifies the density at intermediate coupling.

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Solar Modulation Of Little Ice Age Climate In The Tropical Andes, P. J. Polissar, M. B. Abbott, A. P. Wolfe, M. Bezada, V. Rull, Raymond S. Bradley Jan 2006

Solar Modulation Of Little Ice Age Climate In The Tropical Andes, P. J. Polissar, M. B. Abbott, A. P. Wolfe, M. Bezada, V. Rull, Raymond S. Bradley

Raymond S Bradley

The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines of −3.2 ± 1.4°C and precipitation increases of ≈20% are required to produce the observed glacial responses. These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing.

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Modeling Bacteria Fate And Transport In Watersheds To Support Tmdls, Brian L. Benham, Claire Baffaut, Rebecca W. Zeckoski, Kyle R. Mankin, Yakov A. Pachepsky, Ali M. Sadeghi, Kevin M. Brannan, Michelle L. Soupir, Matthew J. Habersack Jan 2006

Modeling Bacteria Fate And Transport In Watersheds To Support Tmdls, Brian L. Benham, Claire Baffaut, Rebecca W. Zeckoski, Kyle R. Mankin, Yakov A. Pachepsky, Ali M. Sadeghi, Kevin M. Brannan, Michelle L. Soupir, Matthew J. Habersack

Michelle L. Soupir

Fecal contamination of surface waters is a critical water-quality issue, leading to human illnesses and deaths. Total Maximum Daily Loads (TMDLs), which set pollutant limits, are being developed to address fecal bacteria impairments. Watershed models are widely used to support TMDLs, although their use for simulating in-stream fecal bacteria concentrations is somewhat rudimentary. This article provides an overview of fecal microorganism fate and transport within watersheds, describes current watershed models used to simulate microbial transport, and presents case studies demonstrating model use. Bacterial modeling capabilities and limitations for setting TMDL limits are described for two widely used watershed models (HSPF …

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Renewable Energy Alternatives—A Growing Opportunity For Engineering And Technology Education, Kurt A. Rosentrater Jan 2006

Renewable Energy Alternatives—A Growing Opportunity For Engineering And Technology Education, Kurt A. Rosentrater

Kurt A. Rosentrater

A hallmark of the United States’ economic growth is an ever-increasing demand for energy, which has traditionally been met primarily by combusting the hydrocarbons found in fossil fuels. As national security and environmental concerns grow, renewable energy resources are gaining increased attention. Unfortunately, there is currently a dearth of renewable energy coverage in engineering and technology curricula. The objectives of this paper are to examine historical energy data for both traditional as well as alternative energy sources, and to motivate educators to address this gap. Even with the progressive developments of non-traditional energy sources over the years, the U.S. still …

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Expanding The Role Of Systems Modeling: Considering Byproduct Generation From Biofuel Production, Kurt A. Rosentrater Jan 2006

Expanding The Role Of Systems Modeling: Considering Byproduct Generation From Biofuel Production, Kurt A. Rosentrater

Kurt A. Rosentrater

The bioethanol industry has been experiencing rapid growth over the past several years, and is expected to continue to increase production for the foreseeable future. A vital component to the success of this industry is the sales and marketing of processing residues, which are primarily sold as dried distillers grains with solubles (DDGS). Systems modeling, a technique that has been used to predict future demand for bioethanol, can also be used to determine potential byproduct generation rates. This paper discusses the development of one such model, and presents predicted generation of DDGS as well as carbon dioxide emissions from this …

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Head Tilt-Translation Combinations Distinguished At The Level Of Neurons, Jan E. Holly, Sarah E. Pierce, Gin Mccollum Jan 2006

Head Tilt-Translation Combinations Distinguished At The Level Of Neurons, Jan E. Holly, Sarah E. Pierce, Gin Mccollum

Gin McCollum

Angular and linear accelerations of the head occur throughout everyday life, whether from external forces such as in a vehicle or from volitional head movements. The relative timing of the angular and linear components of motion differs depending on the movement. The inner ear detects the angular and linear components with its semicircular canals and otolith organs, respectively, and secondary neurons in the vestibular nuclei receive input from these vestibular organs. Many secondary neurons receive both angular and linear input. Linear information alone does not distinguish between translational linear acceleration and angular tilt, with its gravity-induced change in the linear …

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Charge Storage Model For Hysteretic Negative-Differential Resistance In Metal-Molecule-Metal Junctions, Rebecca Hoye, R. A. Kiehl, J. D. Le, P. Candra, T. R. Hoye Jan 2006

Charge Storage Model For Hysteretic Negative-Differential Resistance In Metal-Molecule-Metal Junctions, Rebecca Hoye, R. A. Kiehl, J. D. Le, P. Candra, T. R. Hoye

Rebecca Hoye, Retired

No abstract provided.

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Modeling The Potential Impact Of Rectal Microbicides To Reduce Hiv Transmission In Bathhouses, Romulus Breban, Ian Mcgowan, Chad M. Topaz, Elissa Schwartz, Peter Anton, Sally Blower Jan 2006

Modeling The Potential Impact Of Rectal Microbicides To Reduce Hiv Transmission In Bathhouses, Romulus Breban, Ian Mcgowan, Chad M. Topaz, Elissa Schwartz, Peter Anton, Sally Blower

Chad M. Topaz

We evaluate the potential impact of rectal microbicides for reducing HIV transmission in bathhouses. A new mathematical model describing HIV transmission dynamics among men who have sex with men (MSM) in bathhouses is constructed and analyzed. The model incorporates key features affecting transmission, including sexual role behavior (insertive and receptive anal intercourse acts), biological transmissibility of HIV, frequency and efficacy of condom usage, and, most pertinently, frequency and efficacy of rectal microbicide usage. To evaluate the potential impact of rectal microbicide usage, we quantify the effect of rectal microbicides (ranging in efficacy from 10% to 90%) on reducing the number …

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A Nonlocal Continuum Model For Biological Aggregations, Chad M. Topaz, Andrea L. Bertozzi, Mark E. Lewis Jan 2006

A Nonlocal Continuum Model For Biological Aggregations, Chad M. Topaz, Andrea L. Bertozzi, Mark E. Lewis

Chad M. Topaz

We construct a continuum model for biological aggregations in which individuals experience long-range social attraction and short range dispersal. For the case of one spatial dimension, we study the steady states analytically and numerically. There exist strongly nonlinear states with compact support and steep edges that correspond to localized biological aggregations, or clumps. These steady state clumps are approached through a dynamic coarsening process. In the limit of large population size, the clumps approach a constant density swarm with abrupt edges. We use energy arguments to understand the nonlinear selection of clump solutions, and to predict the internal density in …

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Apex Co (3-2) Observations Of Ngc 6822, S. De Rijcke, P. Buyle, John M. Cannon, F. Walter, A. Lundgren, D. Michelsen, H. Dejonghe Jan 2006

Apex Co (3-2) Observations Of Ngc 6822, S. De Rijcke, P. Buyle, John M. Cannon, F. Walter, A. Lundgren, D. Michelsen, H. Dejonghe

John Cannon

No abstract provided.

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Extended Mid-Infrared Aromatic Feature Emission In M 82, C. W. Engelbracht, P. Kundurthy, K. D. Gordon, G. H. Rieke, R. C. Kennicutt, J.D. T. Smith, M. W. Regan, D. Makovoz, M. Sosey, B. T. Draine, G. Helou, L. Armus, D. Calzetti, M. Meyer, G. J. Bendo, F. Walter, D. Hollenbach, John M. Cannon, E. J. Murphy, D. A. Dale, B. A. Buckalew, K. Sheth Jan 2006

Extended Mid-Infrared Aromatic Feature Emission In M 82, C. W. Engelbracht, P. Kundurthy, K. D. Gordon, G. H. Rieke, R. C. Kennicutt, J.D. T. Smith, M. W. Regan, D. Makovoz, M. Sosey, B. T. Draine, G. Helou, L. Armus, D. Calzetti, M. Meyer, G. J. Bendo, F. Walter, D. Hollenbach, John M. Cannon, E. J. Murphy, D. A. Dale, B. A. Buckalew, K. Sheth

John Cannon

No abstract provided.

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Warm Dust And Spatially Variable Pah Emission In The Dwarf Starburst Galaxy Ncg 1705, John M. Cannon, J.D. T. Smith, F. Walter, G. J. Bendo, D. Calzetti, D. A. Dale, B. T. Draine, C. W. Engelbracht, K. D. Gordon, G. Helou, R. C. Kennicutt, C. Leitherer, L. Armus, B. A. Buckalew, D. J. Hollenbach, T. H. Jarrett, A. Li, M. J. Meyer, E. J. Murphy, M. W. Regan, G. H. Rieke, M. J. Rieke, H. Roussel, K. Sheth, M. D. Thornley Jan 2006

Warm Dust And Spatially Variable Pah Emission In The Dwarf Starburst Galaxy Ncg 1705, John M. Cannon, J.D. T. Smith, F. Walter, G. J. Bendo, D. Calzetti, D. A. Dale, B. T. Draine, C. W. Engelbracht, K. D. Gordon, G. Helou, R. C. Kennicutt, C. Leitherer, L. Armus, B. A. Buckalew, D. J. Hollenbach, T. H. Jarrett, A. Li, M. J. Meyer, E. J. Murphy, M. W. Regan, G. H. Rieke, M. J. Rieke, H. Roussel, K. Sheth, M. D. Thornley

John Cannon

No abstract provided.

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