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Articles 1 - 24 of 24
Full-Text Articles in Physical Sciences and Mathematics
Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis
Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis
Publications
In this article we study two problems that arise when using timing and amplitude estimates from a network of interferometers (IFOs) to evaluate the direction of an incident gravitational wave burst (GWB). First, we discuss an angular bias in the least squares timing-based approach that becomes increasingly relevant for moderate to low signal-to-noise ratios. We show how estimates of the arrival time uncertainties in each detector can be used to correct this bias. We also introduce a stand alone parameter estimation algorithm that can improve the arrival time estimation and provide root-sum-squared strain amplitude (h(rss)) values for each site. In …
A Three-Dimensional Pattern-Space Representation For Volumetric Arrays, William C. Barott, Paul G. Steffes
A Three-Dimensional Pattern-Space Representation For Volumetric Arrays, William C. Barott, Paul G. Steffes
Publications
A three-dimensional pattern-space representation is presented for volumetric arrays. In this representation, the radiation pattern of an array is formed by the evaluation of the three-dimensional pattern-space on a spherical surface. The scan angle of the array determines the position of this surface within the pattern-space. This pattern-space representation is used in conjunction with a genetic algorithm to minimize the sidelobe levels exhibited by a thinned volumetric array during scanning.
Geocoronal Hydrogen Observations Spanning Three Solar Minima, S. M. Nossal, E. J. Mierkiewicz, F. L. Roesler, L. M. Haffner, R. J. Reynolds, R. C. Woodward
Geocoronal Hydrogen Observations Spanning Three Solar Minima, S. M. Nossal, E. J. Mierkiewicz, F. L. Roesler, L. M. Haffner, R. J. Reynolds, R. C. Woodward
Publications
The 11-year solar cycle is a dominant source of natural variability in the upper atmosphere, and its effect on atomic hydrogen distributions and emissions must be understood to investigate possible signs of longer-term climatic trends in this region. We present midlatitude geocoronal hydrogen Balmer α observations from solar cycle 23 (1997–2006) and three solar minimum periods, 1985, 1997, and 2006. The 1997 through 2006 observations were taken with the Wisconsin H-αMapper Fabry-Perot (WHAM), a ground-based CCD-annular summing instrument that began observations at the Kitt Peak Observatory in Arizona in 1997. The 1985 observations were made with a similarly …
What A User Wants: Redesigning A Library's Web Site Based On A Card-Sort Analysis, Laura Pope Robbins, Lisa Esposito, Christ Kretz, Michael Aloi
What A User Wants: Redesigning A Library's Web Site Based On A Card-Sort Analysis, Laura Pope Robbins, Lisa Esposito, Christ Kretz, Michael Aloi
Publications
Web site usability concerns anyone with a web site to maintain. Libraries, however, are often the biggest offenders in terms of usability. In our efforts to provide users with everything they need to do research, we often overwhelm them with sites that are confusing in structure, difficult to navigate, and weighed down with jargon. Dowling College Library recently completed a redesign of its web site based upon the concept of usability. For smaller libraries in particular, this can be a challenge. The web site is often maintained by one or two people and finding the time and resources to conduct …
Electron Density And Electron Neutral Collision Frequency In The Ionosphere Using Plasma Impedance Probe Measurement, E. Spencer, S. Patra, T. Andriyas, C. Swenson, J. Ward, Aroh Barjatya
Electron Density And Electron Neutral Collision Frequency In The Ionosphere Using Plasma Impedance Probe Measurement, E. Spencer, S. Patra, T. Andriyas, C. Swenson, J. Ward, Aroh Barjatya
Publications
Swept Impedance Probe measurements in a sporadic E layer observed during the Sudden Atomic Layer (SAL) sounding rocket mission are analyzed to obtain absolute electron densities and electron neutral collision frequencies accurately. Three sets of upleg and downleg impedance data are selected for the analysis. Initial estimates of the plasma parameters are obtained through a least mean square fit of the measured impedance data against the analytical impedance formula ZB(f ) of Balmain (1969). These initial parameters are used as a starting point to drive a finite difference computational model of an antenna immersed in a plasma called PF-FDTD. The …
Constraining The Surface Inhomogeneity And Settling Times Of Metals On Accreting White Dwarfs, Michael H. Montgomery, S.E. Thompson, Ted Von Hippel
Constraining The Surface Inhomogeneity And Settling Times Of Metals On Accreting White Dwarfs, Michael H. Montgomery, S.E. Thompson, Ted Von Hippel
Publications
Due to the short settling times of metals in DA white dwarf atmospheres, any white dwarfs with photospheric metals must be actively accreting. It is therefore natural to expect that the metals may not be deposited uniformly on the surface of the star. We present calculations showing how the temperature variations associated with white dwarf pulsations lead to an observable diagnostic of the surface metal distribution, and we show what constraints current data sets are able to provide. We also investigate the effect that time-variable accretion has on the metal abundances of different species, and we show how this can …
Gis Modeling And Mitigation Of Coral Reef Damage, Richard Snow, Mary Snow
Gis Modeling And Mitigation Of Coral Reef Damage, Richard Snow, Mary Snow
Publications
The objective of this study is to demonstrate that an efficient instrument for conducting surveys and inventories of coral reefs to assess those ecosystems at higher risk and develop mitigation strategies is through the use of a Geographic Information System (GIS). Efficient monitoring requires the assessment of various coastal data baselines and the evaluation of subsequent alterations in spatial patterns. While monitoring involves real-time components, among the most powerful tools of a GIS are its modeling capabilities, which allow simulation of various climate change scenarios. Relevant aspects include changes in coastal land use, wetlands, and shoreline configuration. Using Caribbean coral …
Excitation Of Ducted Gravity Waves In The Lower Thermosphere By Tropospheric Sources, Jonathan B. Snively, Victor P. Pasko
Excitation Of Ducted Gravity Waves In The Lower Thermosphere By Tropospheric Sources, Jonathan B. Snively, Victor P. Pasko
Publications
Short-period, small-scale gravity waves are frequently observed in nighttime airglow imaging experiments. These waves are often found to be ducted and may be confined to a thin region of altitude in the mesosphere or lower thermosphere. An apparent paradox of high-altitude ducted waves is the nature of the source; it is necessary that a ducted wave be excited in situ or have been able to tunnel into the duct from another atmospheric region. In this paper, analytical and numerical solutions are presented for simple thermally ducted gravity waves that are Doppler-shifted by constant background winds. Using a continuous analytical model, …
Book Review: Guide To Observing Deep-Sky Objects: A Complete Global Resource For Astronomers, T. D. Oswalt
Book Review: Guide To Observing Deep-Sky Objects: A Complete Global Resource For Astronomers, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of Guide to Observing Deep-Sky Objects : a Complete Global Resource for Astronomers by Jeff A. Farinacci. Springer, 2007 189p, 9780387728506 $29.95
The First Mid-Infrared Spectra Of Cool White Dwarfs, Mukremin Kilic, Ted Von Hippel, Et Al.
The First Mid-Infrared Spectra Of Cool White Dwarfs, Mukremin Kilic, Ted Von Hippel, Et Al.
Publications
We present the first mid-infrared spectra of two cool white dwarfs obtained with the Spitzer Space Telescope. We also present 3.5–8 μ m photometry for 19 cool white dwarfs with 5000 K ≤Teff ≤ 9000 K. We perform a detailed model atmosphere analysis of these white dwarfs by fitting their UBVRIJHK and Spitzer photometry with state-of-the-art model atmospheres, and demonstrate that the optical and infrared spectral energy distributions of cool white dwarfs are well reproduced by our grid of models. Our mid-infrared photometry and 7.5-14.5 μm spectrum of WD 0018–267 are consistent with a Teff = 5720 …
An Application Of High Fidelity Ftds For Ab Initio Pilot Training: The Way Ahead, Nickolas D. Macchiarella, Tim Brady, Brandon S. Lyon
An Application Of High Fidelity Ftds For Ab Initio Pilot Training: The Way Ahead, Nickolas D. Macchiarella, Tim Brady, Brandon S. Lyon
Publications
"Decreases in simulation costs and increases in aircraft training costs led to the need for further investigation into the application of simulation-based training. Researchers conducted an eighteen-month study using ab initio student pilots as participants. This study applied a Federal Aviation Administration (FAA) approved, Part 142, flight-training curriculum that included 60% flight training device (FTD) use. Researchers identified five causal factors that warranted further investigation. The causal factors identified were visual fidelity, procedural similarity, dynamic flight environment, difficulty of task, and visual scanning and response. These causal factors have the potential to affect transfer of training (ToT) from simulated flight …
Gis Forest Inventory And Evaluation In The Wake Of Climate Change, Mary Snow, Richard K. Snow
Gis Forest Inventory And Evaluation In The Wake Of Climate Change, Mary Snow, Richard K. Snow
Publications
"Because climate and vegetation are so strongly associated, it is assumed that the forecast rapid changes in climate will affect plant distributions and alter the makeup of forest communities. For example, climate change could cause regional wind patterns to shift, which would be accompanied by an increase in wind speed intensity. Such shifts could impact existing rain shadow effects in some regions causing more precipitation on the windward side of mountain ranges while creating even drier conditions on the leeward sides. Fire patterns are likely to be altered as well, which could affect a variety of plant species, even those …
A New Look At The Local White Dwarf Population, J. B. Holberg, E. M. Sion, Terry D. Oswalt, G. P. Mccook, S. Foran, John P. Subasavage
A New Look At The Local White Dwarf Population, J. B. Holberg, E. M. Sion, Terry D. Oswalt, G. P. Mccook, S. Foran, John P. Subasavage
Publications
We have conducted a detailed new survey of the local population of white dwarfs lying within 20 pc of the Sun. A new revised catalog of local white dwarfs containing 122 entries (126 individual degenerate stars) is presented. This list contains 27 white dwarfs not included in a previous list from 2002, as well as new and recently published trigonometric parallaxes. In several cases new members of the local white dwarf population have come to light through accurate photometric distance estimates. In addition, a suspected new double degenerate system (WD 0423+120) has been identified. The 20 pc sample is currently …
Book Review: The Road To Galaxy Formation 2nd Ed, T. D. Oswalt
Book Review: The Road To Galaxy Formation 2nd Ed, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of The road to galaxy formation 2nd ed by William C. Keel. Springer/Praxis, 2007 262p, 9783540725343 $99.00.
Over-Ocean Validation Of The Global Convective Diagnostic, David W. Martin, Richard A. Kohrs, Frederick R. Mosher, Carlo Maria Medaglia, Claudia Adamo
Over-Ocean Validation Of The Global Convective Diagnostic, David W. Martin, Richard A. Kohrs, Frederick R. Mosher, Carlo Maria Medaglia, Claudia Adamo
Publications
The global convective diagnostic (GCD) is a bispectral (infrared and water vapor), day–night scheme for operationally mapping deep convection by means of geostationary satellite images. This article describes a test of GCD performance over tropical and subtropical waters near North America. The test consists of six cases, each involving a convective cloud complex. A seventh case treats convection over land. For each case, a map of deep convection was constructed from image pairs from Geostationary Operational Environmental Satellite-12 (GOES-12). Case by case and for all maritime cases together, the GCD map was compared with a convective parameter derived …
On Existence And Uniqueness Results For The Bbm Equation With Arbitrary Forcing Terms, Timothy A. Smith
On Existence And Uniqueness Results For The Bbm Equation With Arbitrary Forcing Terms, Timothy A. Smith
Publications
The problem of classical solutions for the regularized long-wave equation is considered where various additional forcing terms are introduced which are often required for physical modifications in the wave theory. Sufficient conditions of solvability and existence are established and then these conditions are related to the structure of the forcing terms under consideration.
The Identification And Verification Of Hazardous Convective Cells Over Oceans Using Visible And Infrared Satellite Observations, Michael F. Donovan, Earle R. Williams, Cathy Kessinger, Gary Blackburn, Paul H. Herzegh, Richard L. Bankert, Steve Miller, Frederick R. Mosher
The Identification And Verification Of Hazardous Convective Cells Over Oceans Using Visible And Infrared Satellite Observations, Michael F. Donovan, Earle R. Williams, Cathy Kessinger, Gary Blackburn, Paul H. Herzegh, Richard L. Bankert, Steve Miller, Frederick R. Mosher
Publications
Three algorithms based on geostationary visible and infrared (IR) observations are used to identify convective cells that do (or may) present a hazard to aviation over the oceans. The performance of these algorithms in detecting potentially hazardous cells is determined through verification with Tropical Rainfall Measuring Mission (TRMM) satellite observations of lightning and radar reflectivity, which provide internal information about the convective cells. The probability of detection of hazardous cells using the satellite algorithms can exceed 90% when lightning is used as a criterion for hazard, but the false-alarm ratio with all three algorithms is consistently large (40%), thereby exaggerating …
Models Of Phototransduction In Rod Photoreceptors, Harihar Khanal, Vasilios Alexiades
Models Of Phototransduction In Rod Photoreceptors, Harihar Khanal, Vasilios Alexiades
Publications
Phototransduction is the process by which photons of light generate an electrical response in retinal rod and cone photoreceptors, thereby initiating vision. We compare the electrical response in salamander rods from increasingly more (spacialy) detailed models of phototransduction: 0-dimensional (bulk), 1-dimensional (longitudinal), 2-dimensional (axisymmetric), and 3-dimensional (with incisures). We discuss issues of finding physical parameters for simulation and validation of models, and also present some computational experiments for rods with geometry of mouse and human photoreceptors.
Book Review: Mac Os X, Ipod, And Iphone Forensic Analysis Dvd Toolkit, Gary C. Kessler
Book Review: Mac Os X, Ipod, And Iphone Forensic Analysis Dvd Toolkit, Gary C. Kessler
Publications
This document is Dr. Kessler's review of MAC OS X, iPod, and iPhone Forensic Analysis DVD Toolkit, edited by Jesse Varsalone. Syngress, 2009. ISBN: 978-1-59749-297-3.
Book Review: The Dotcrime Manifesto: How To Stop Internet Crime, Gary C. Kessler
Book Review: The Dotcrime Manifesto: How To Stop Internet Crime, Gary C. Kessler
Publications
This document is Dr. Kessler's review of The dotCrime Manifesto: How to Stop Internet Crime, by Phillip Hallam-Baker. Addison-Wesley, 2008. ISBN: 0-321-50358-9
White Dwarf Luminosity And Mass Functions From Sloan Digital Sky Survey Spectra, Steven Degennaro, Ted Von Hippel, D. E. Winget, S. O. Kepler, Atsuko Nitta, Detlev Koester, Leandro Althaus
White Dwarf Luminosity And Mass Functions From Sloan Digital Sky Survey Spectra, Steven Degennaro, Ted Von Hippel, D. E. Winget, S. O. Kepler, Atsuko Nitta, Detlev Koester, Leandro Althaus
Publications
We present the first phase in our ongoing work to use Sloan Digital Sky Survey (SDSS) data to create separate white dwarf (WD) luminosity functions (LFs) for two or more different mass ranges. In this paper, we determine the completeness of the SDSS spectroscopic WD sample by comparing a proper-motion selected sample of WDs from SDSS imaging data with a large catalog of spectroscopically determined WDs. We derive a selection probability as a function of a single color (g − i) and apparent magnitude (g) that covers the range −1.0 < g − i < 0.2 and 15 < g < 19.5. We address the observed upturn in log g for WDs with Teff 12,000 K and offer arguments that the problem is limited to the line profiles and is not present in the continuum. We offer an empirical method of removing the upturn, recovering a reasonable mass function for WDs with Teff < 12,000 K. Finally we present a WD LF with nearly an order of magnitude (3358) more spectroscopically confirmed WDs than any previous work.
Book Review: The Telescope: Its History, Technology, And Future, T. D. Oswalt
Book Review: The Telescope: Its History, Technology, And Future, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of The Telescope : Its History, Technology, and Future by Geoff Andersen. Princeton, 2007 248p, 0691129797 $29.95, 9780691129792 $29.95.
Book Review: Your Cosmic Context: An Introduction To Modern Cosmology, T. D. Oswalt
Book Review: Your Cosmic Context: An Introduction To Modern Cosmology, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of Your Cosmic Context : an Introduction to Modern Cosmology by Todd Duncan and Craig Tyler Pearson Addison-Wesley, 2008 466p, 0132400103 $80.00, 9780132400107 $80.00.
Book Review: Challenges To Digital Forensic Evidence, Gary C. Kessler
Book Review: Challenges To Digital Forensic Evidence, Gary C. Kessler
Publications
This document is Dr. Kessler's review of Challenges to Digital Forensic Evidence, by Fred Cohen. Fred Cohen & Associates, 2008. ISBN 1-878109-41-3