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Articles 7291 - 7320 of 8870

Full-Text Articles in Astrophysics and Astronomy

The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith Jan 2004

The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith

Masters

In every part of the world the rate of map revision is alarmingly low when compared to the rate of change of many human influenced surface features. There is therefore a requirement to regularly gather up-to-date information about surface features and to incorporate changes in maps both quickly and effectively before it becomes history. When an aerial photograph is taken, it contains errors one category of which is caused by the aircraft taking the photograph being tilted. This aerial photograph by itself is of little commercial value. Accurate maps cannot be created from it, its use in GIS (Geographical Information …

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The Host Of Grb 030323 At Z=3.372: A Very High Column Density Dla System With A Low Metallicity, P. M. Vreeswijk, S. L. Ellison, C. Ledoux, R. A. M. J. Wijers, J. P. U. Fymbo, P. Møller, A. Henden, J. Hjorth, G. Masi Jan 2004

The Host Of Grb 030323 At Z=3.372: A Very High Column Density Dla System With A Low Metallicity, P. M. Vreeswijk, S. L. Ellison, C. Ledoux, R. A. M. J. Wijers, J. P. U. Fymbo, P. Møller, A. Henden, J. Hjorth, G. Masi

Publications

We present photometry and spectroscopy of the afterglow of GRB 030323. VLT spectra of the afterglow show damped Lyα(DLA) absorption and low- and high-ionization lines at a redshift z =3.3718 ±0.0005. The inferred neutral hy-drogen column density, log N(H i) =21.90±0.07, is larger than any (GRB- or QSO-) DLA H  column density inferred directly from Lyαin absorption. From the afterglow photometry, we derive a conservative upper limit to the host-galaxy extinction: AV <0.5 mag. The iron abundance is [Fe/H] =−1.47 ±0.11, while the metallicity of the gas as measured from sulphur is [S/H] =−1.26 ±0.20. We derive an upper limit on the H2 molecular fraction of 2N(H2)/(2N(H2) +N(H i)) <∼10−6.In the Lyαtrough, a Lyαemission line is detected, which corresponds to a star-formation rate (not corrected for dust extinction) of roughly 1 Myr−1. All these results are consistent with the host galaxy of GRB 030323 consisting of a low metallicity gas with a low dust content. We detect fine-structure lines of silicon, Si*, which have never been clearly detected in QSO-DLAs; this suggests that these lines are produced in the vicinity of the GRB explosion site. Under the assumption that these fine-structure levels are populated by particle collisions, we estimate the H  volume density to be nH i =102−104 cm−3.HST/ACS imaging 4 months after the burst shows an extended AB(F606W) =28.0 ±0.3 mag object at a distance of 0.14 (1 kpc) from the early afterglow location, which presumably is the host galaxy of GRB 030323.

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Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson Jan 2004

Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson

All Physics Faculty Publications

Time-delay interferometry (TDI) is the data processing technique needed for generating interferometric combinations of data measured by the multiple Doppler readouts available onboard the three Laser Interferometer Space Antenna (LISA) spacecraft. Within the space of all possible interferometric combinations TDI can generate, we have derived a specific combination that has zero response to the gravitational wave signal, and called it the zero-signal solution (ZSS). This is a two-parameter family of linear combinations of the generators of the TDI space, and its response to a gravitational wave becomes null when these two parameters coincide with the values of the angles of …

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Single-Sided Czt Strip Detectors, John R. Macri, L A. Hamel, Manuel Julien, R S. Miller, B Donmez, Mark L. Mcconnell, James M. Ryan, Mark Widholm Jan 2004

Single-Sided Czt Strip Detectors, John R. Macri, L A. Hamel, Manuel Julien, R S. Miller, B Donmez, Mark L. Mcconnell, James M. Ryan, Mark Widholm

Space Science Center

We report progress in the study of thick CZT strip detectors for 3-D imaging and spectroscopy and discuss two approaches to device design. Unlike double-sided strip detectors, these devices feature both row and column contacts implemented on the anode surface. This electron-only approach circumvents problems associated with poor hole transport in CZT that normally limit the thickness and energy range of double-sided strip detectors. The work includes laboratory and simulation studies aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma radiation measurements while minimizing the number and complexity of the electronic readout channels. These devices can …

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Future Prospects For High Energy Polarimetry Of Gamma‐Ray Bursts, Mark L. Mcconnell Jan 2004

Future Prospects For High Energy Polarimetry Of Gamma‐Ray Bursts, Mark L. Mcconnell

Space Science Center

The recent detection of linear polarization from GRB120206 has piqued the interest of the community in this relatively unexplored avenue of research. Here, we review the current status and prospects for GRB polarimetry at hard X‐ray and soft γ‐ray energies. After reviewing the most recent results, we present a brief survey of current and planned experiments that are capable of making GRB polarization measurements in the energy range between 30 keV and 30 MeV.

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Grain Size Distributions And Photoelectric Heating In Ionized Media, P. A. M. Vanhoof, J. C. Weingartner, P. G. Martin, K. Volk, Gary J. Ferland Jan 2004

Grain Size Distributions And Photoelectric Heating In Ionized Media, P. A. M. Vanhoof, J. C. Weingartner, P. G. Martin, K. Volk, Gary J. Ferland

Physics and Astronomy Faculty Publications

Ever since the pioneering study of Spitzer, it has been widely recognized that grains play an important role in the heating and cooling of photoionized environments. This includes the diffuse interstellar medium and H II regions, planetary nebulae and photodissociation regions. A detailed code is necessary to model grains in a photoionized medium since the interactions of grains with their environment include a host of microphysical processes. In this paper we will use the spectral synthesis code CLOUDY for this purpose. A comprehensive upgrade of the grain model has been recently incorporated into CLOUDY. One of these upgrades is the …

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Senior Thesis Work, Corey Jansen Jan 2004

Senior Thesis Work, Corey Jansen

Presidential Scholars Theses (1990 – 2006)

In closing, it is important to remember, as stated earlier, that no one can prove exactly what it was that the authors of Genesis were trying to get across to us. It is valid to note, however, that the stories they were trying to get across were intended for and more properly understood by the people at that time and place. While they form the basis of many of our beliefs in Christianity, they weren't written with the realization that thousands of years later there would be great scientific discoveries that would teach us more about the world and about …

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Novel N-Body Orbits For Constrained Potentials Including The Unusual Figure Eight Three Body Orbit, Jan M. Dudzik Jan 2004

Novel N-Body Orbits For Constrained Potentials Including The Unusual Figure Eight Three Body Orbit, Jan M. Dudzik

Masters Theses

Recently new n-body planar orbits have been discovered which are known as choreographies. These orbits correspond to small n, generally n<20, and exhibit unexpected patterns with respect to given initial conditions. Here we shall examine numerical solutions to the three-body problem and the restricted three-body problem for three body potentials that are the sum of three two-body potentials. Then for an everywhere attractive three body potential with non-collinear and collision-less orbits with a strictly monotone decreasing potential function there exist bound states that are not chaotic that are choreographies. For the right initial conditions these orbits can be mapped numerically and visualized. We will display a number of these cases corresponding to the three body problem, restricted three body problem, the chaotic restricted three body problem and the new figure eight bound state choreography for the Kazalov potential orbits to exhibit some of their special features and to take note of a number of open questions dealing with simple orbital problems.

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Observations Of The Pulsating White Dwarf G 185-32, Bárbara Garcia Castanheira, Matt A. Wood Jan 2004

Observations Of The Pulsating White Dwarf G 185-32, Bárbara Garcia Castanheira, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

We observed the pulsating hydrogen atmosphere white dwarf G 185-32 with the Whole Earth Telescope in 1992. We report on a weighted Fourier transform of the data detecting 18 periodicities in its light curve. Using the Hubble Space Telescope Faint Object Spectrograph time resolved spectroscopy, and the wavelength dependence of the relative amplitudes, we identify the spherical harmonic degree (ℓ) for 14 pulsation signals. We also compare the determinations of effective temperature and surface gravity using the excited modes and atmospheric methods, obtaining Teff = 11960 ± 80 K, log g = 8.02 ± 0.04 and M = 0.617 ± …

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Table Of Contents Jan 2004

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

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President's Message, David J. Stroup Jan 2004

President's Message, David J. Stroup

Journal of the South Carolina Academy of Science

No abstract provided.

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Scas Officers And Council Members 2004 - 2005 Jan 2004

Scas Officers And Council Members 2004 - 2005

Journal of the South Carolina Academy of Science

No abstract provided.

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Bioinformatics: An Undergraduate Research/Teaching Tool., Abhishek Agrawal, Valgene L. Dunham Jan 2004

Bioinformatics: An Undergraduate Research/Teaching Tool., Abhishek Agrawal, Valgene L. Dunham

Journal of the South Carolina Academy of Science

No abstract provided.

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Theoretical Considerations For Geosynchronous, Earth-Based Gravity Wave Interferometer, William Griffin Jan 2004

Theoretical Considerations For Geosynchronous, Earth-Based Gravity Wave Interferometer, William Griffin

Honors Program Theses

We investigated theoretical considerations in the design of an Earth-based laser interferometer for detecting gravitational waves. Our design envisages a ground-based tracking station in communication with two geosynchronous satellites. We assumed linearized gravitational waves in a Schwarzschild spacetime geometry outside the Earth. Our initial calculations show that such a design is sufficiently sensitive to successfully detect gravitational waves near Earth.

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Riemann Tensor Of The Ambient Universe, The Dilaton, And Newton’S Constant, Rossen Ivanov, Emil Prodanov Jan 2004

Riemann Tensor Of The Ambient Universe, The Dilaton, And Newton’S Constant, Rossen Ivanov, Emil Prodanov

Articles

We investigate a four-dimensional world, embedded into a five-dimensional spacetime, and find the five-dimensional Riemann tensor via generalisation of the Gauss (--Codacci) equations. We then derive the generalised equations of the four-dimensional world and also show that the square of the dilaton field is equal to the Newton's constant. We find plausable constant and non-constant solutions for the dilaton. Comment: 5 pages, revtex

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The Faith Factor: New Testament Cosmology In Its Historical Context, Keith A. Burton Jan 2004

The Faith Factor: New Testament Cosmology In Its Historical Context, Keith A. Burton

Journal of the Adventist Theological Society

No abstract provided.

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Uranium Oxide As A Highly Reflective Coating From 100-400 Ev, Richard L. Sandberg, David D. Allred, Luke J. Bissell, Jed E. Johnson, R. Steven Turley Jan 2004

Uranium Oxide As A Highly Reflective Coating From 100-400 Ev, Richard L. Sandberg, David D. Allred, Luke J. Bissell, Jed E. Johnson, R. Steven Turley

Faculty Publications

We present the measured reflectances (Beamline 6.3.2, ALS and LBNL) of naturally oxidized uranium and naturally oxidized nickel thin films from 100-460 eV (2.7 to 11.6 nm) at 5 and 15 degrees grazing incidence. These show that uranium as UO2, can fulfill its promise as the highest known single surface reflector for this portion of the soft x-ray region, being nearly twice as reflective as nickel in the 124-250 eV (5-10 nm) region. This is due to its large index of refraction coupled with low absorption. Nickel is commonly used in soft x-ray applications in astronomy and synchrotrons. (Its reflectance …

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Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck Jan 2004

Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck

Faculty Publications

We calculate the systematic average speed of the adiabatic piston and a thermal Brownian motor, introduced by C. Van den Broeck, R. Kawai and P. Meurs [Phys. Rev. Lett. 93, 090601 (2004)], by an expansion of the Boltzmann equation and compare with the exact numerical solution.

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Generation Of The Transient Electrical And Spontaneous Magnetic Fields By Solid State Combustion, Karen S. Martirosyan, J. R. Claycomb, J. H. Miller Jr., D. Luss Jan 2004

Generation Of The Transient Electrical And Spontaneous Magnetic Fields By Solid State Combustion, Karen S. Martirosyan, J. R. Claycomb, J. H. Miller Jr., D. Luss

Physics & Astronomy Faculty Publications

Experiments revealed that transient electric field intensities up to 2.5 V/cm were generated during the initial period of combustion synthesis of the ferromagnetic products before the maximum temperature was reached. This occurred when the iron particles were partially oxidized and the reaction product was mainly magnetite sFe3O4d. The electromagnetic field caused spontaneous magnetization of the product in the postcombustion zone. Magnetic field values up to 4 µT formed after the sample temperature fell below the Curie temperature and the initial reactants were completely converted to the ferromagnetic phase PbFe12O19. Increasing the volume of the samples increases the absolute residual magnetic …

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New Methods For Exafs Analysis In Structural Genomics, Grant Bunker, Nicholas Dimakis, Gocha Kelashvili Jan 2004

New Methods For Exafs Analysis In Structural Genomics, Grant Bunker, Nicholas Dimakis, Gocha Kelashvili

Physics & Astronomy Faculty Publications

Data analysis is one of the remaining bottlenecks in high-throughput EXAFS for structural genomics. Here some recent developments in methodology are described that offer the potential for rapid and automated XAS analysis of metalloproteins.

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Xafs Debye-Waller Factors For Zn Metalloproteins, Nicholas Dimakis, Grant Bunker Jan 2004

Xafs Debye-Waller Factors For Zn Metalloproteins, Nicholas Dimakis, Grant Bunker

Physics & Astronomy Faculty Publications

An accurate and practical method for the calculation and use of thermal x-ray absorption fine structure (XAFS) Debye-Waller factors (DWFs) in active sites of metalloproteins is presented. These factors are calculated on model clusters within the local density functional approximation with nonlocal corrections. The DWFs are mapped out and parametrized as a function of the first shell distance and an angle (where applicable), for all significant single and multiple scattering paths, as well as the sample temperature. This approach is applied to the biologically essential but spectroscopically silent Zn+2 active sites composed of histidines, cysteines, and carboxylate ligands in homogeneous …

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Setting Upper Limits On The Strength Of Periodic Gravitational Waves From Psr J1939+2134 Using The First Science Data From The Geo 600 And Ligo Detectors, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres Jan 2004

Setting Upper Limits On The Strength Of Periodic Gravitational Waves From Psr J1939+2134 Using The First Science Data From The Geo 600 And Ligo Detectors, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres

Physics & Astronomy Faculty Publications

Data collected by the GEO 600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar J1939+2134 at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: a frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar’s gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar’s equatorial ellipticity.

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Probing Molecular Free Energy Landscapes By Periodic Loading, Oliver Braun, Andreas Hanke, Udo Seifert Jan 2004

Probing Molecular Free Energy Landscapes By Periodic Loading, Oliver Braun, Andreas Hanke, Udo Seifert

Physics & Astronomy Faculty Publications

Single molecule pulling experiments provide information about interactions in biomolecules that cannot be obtained by any other method. However, the reconstruction of the molecule’s free energy profile from the experimental data is still a challenge, in particular, for the unstable barrier regions. We propose a new method for obtaining the full profile by introducing a periodic ramp and using Jarzynski’s relation for obtaining equilibrium quantities from nonequilibrium data. Our simulated experiments show that this method delivers significant more accurate data than previous methods, under the constraint of equal experimental effort.

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First Upper Limits From Ligo On Gravitational Wave Bursts, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres Jan 2004

First Upper Limits From Ligo On Gravitational Wave Bursts, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres

Physics & Astronomy Faculty Publications

We report on a search for gravitational wave bursts using data from the first science run of the Laser Interferometer Gravitational Wave Observatory (LIGO) detectors. Our search focuses on bursts with durations ranging from 4 to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at a 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine Gaussians) as a function of their root-sum-square strain hrss; typical sensitivities …

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Analysis Of First Ligo Science Data For Stochastic Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano Jan 2004

Analysis Of First Ligo Science Data For Stochastic Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present the analysis of between 50 and 100 h of coincident interferometric strain data used to search for and establish an upper limit on a stochastic background of gravitational radiation. These data come from the first LIGO science run, during which all three LIGO interferometers were operated over a 2-week period spanning August and September of 2002. The method of cross correlating the outputs of two interferometers is used for analysis. We describe in detail practical signal processing issues that arise when working with real data, and we establish an observational upper limit on a f−3 power spectrum of …

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Analysis Of Ligo Data For Gravitational Waves From Binary Neutron Stars, B. P. Abbott, R. Abbott, Wm. R. Johnston, Joseph D. Romano, V. Schmidt Jan 2004

Analysis Of Ligo Data For Gravitational Waves From Binary Neutron Stars, B. P. Abbott, R. Abbott, Wm. R. Johnston, Joseph D. Romano, V. Schmidt

Physics & Astronomy Faculty Publications

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of R

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Coalescence Remnant Of Spinning Binary Black Holes, J Baker, M. Campanelli, C. O. Lousto, R. Takahashi Jan 2004

Coalescence Remnant Of Spinning Binary Black Holes, J Baker, M. Campanelli, C. O. Lousto, R. Takahashi

Physics & Astronomy Faculty Publications

We compute the gravitational radiation generated in the evolution of a family of close binary black hole configurations, using a combination of numerical and perturbative approximation methods. We evolve the binaries with spins s aligned or counteraligned with the orbital angular momentum from near the innermost stable circular orbit down to the final single rotating black hole. For the moderately spinning holes studied here the remnant Kerr black holes formed at the end of an inspiral process have rotation parameters a/M≈0.72+0.32(s/mH), suggesting it is difficult (though not excluded) to end up with near maximally rotating holes from such scenarios.

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Measurement Of Beam-Spin Asymmetries For Π⁺ Electroproduction Above The Baryon Resonance Region, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration Jan 2004

Measurement Of Beam-Spin Asymmetries For Π⁺ Electroproduction Above The Baryon Resonance Region, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration

Physics Faculty Publications

We report the first evidence for a nonzero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic kinematic region. Data for the reaction e→pe'π+X have been obtained using a polarized electron beam of 4.3 GeV with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility. The amplitude of the sin ᵠ modulation increases with the momentum of the pion relative to the virtual photon, z. In the range z = 0.5-0.8 the average amplitude is 0.038 ± 0.005 ± 0.003 for a missing mass Mx > 1.1 GeV and 0.037 …

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Search For High-Energy Gamma Rays From An X-Ray-Selected Blazar Sample, P. T. Reynolds, Et. Al. Dec 2003

Search For High-Energy Gamma Rays From An X-Ray-Selected Blazar Sample, P. T. Reynolds, Et. Al.

Physical Sciences Publications

Our understanding of blazars has been greatly increased in recent years by extensive multiwavelength observations, particularly in the radio, X-ray, and gamma-ray regions. Over the past decade the Whipple 10 m telescope has contributed to this with the detection of five BL Lacertae objects at very high gamma-ray energies. The combination of multiwavelength data has shown that blazars follow a well-defined sequence in terms of their broadband spectral properties. Together with providing constraints on emission models, this information has yielded a means by which potential sources of TeV emission may be identified and predictions made as to their possible gamma-ray …

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Ion Cyclotron Waves In The High Altitude Cusp: Cluster Observations At Varying Spacecraft Separations, K. Nykyri, P. J. Cargill, E. A. Lucek, T. S. Horbury, A. Balogh, B. Lavraud, I. Dandouras, H. Reme Dec 2003

Ion Cyclotron Waves In The High Altitude Cusp: Cluster Observations At Varying Spacecraft Separations, K. Nykyri, P. J. Cargill, E. A. Lucek, T. S. Horbury, A. Balogh, B. Lavraud, I. Dandouras, H. Reme

Publications

We have analysed high-resolution Cluster magnetic field data during three high-altitude cusp crossings in 2001 and 2002. The Cluster separations for these crossings varied between 100 and 600 km and therefore provided an unique opportunity to study wave properties at different length scales. In the cusp Cluster sees frequent intervals of magnetic field fluctuations with clear peaks in power close to the local ion cyclotron frequency, and both left- and right-handed polarisations. At large separations the power seen at different spacecraft can differ by orders of magnitude. For smaller separations, the power seen at the four spacecraft agrees better but …

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