Digital Commons Network^™

A Precautionary Tale: Separating The Infant From The Fetus, Lawrence Torcello

Articles

This article confronts growing conservative opposition to abortion based on the slippery slope claim that abortion is morally equivalent to infanticide. By examining the relationship between moral skepticism and precautionary ethics the article promotes completely the permissive position on abortion from conception to birth while consistently rejecting the possibility that such a position entails permissive implications for infanticide. The article introduces and traces the implicit relationship between moral skepticism, the precautionary principle and political liberalism.

Regular Second Order Perturbations Of Binary Black Holes: The Extreme Mass Ratio Regime, Carlos O. Lousto, Hiroyuki Nakano

Articles

In order to derive the precise gravitational waveforms for extreme mass ratio inspirals (EMRI), we develop a formulation for the second order metric perturbations produced by a point particle moving in the Schwarzschild spacetime. The second order waveforms satisfy a wave equation with an effective source build up from products of the first order perturbations and its derivatives. We have explicitly regularized this source at the horizon and at spatial infinity. We show that the effective source does not contain squares of the Dirac’s delta and that perturbations are regular at the particle location. We introduce an asymptotically flat gauge …

Optimal Resource Management In The Presence Of A Deleterious Alien Species: A Stochastic Model For An Orchard, Amitrajeet A. Batabyal, Peter Nijkamp

Articles

Various plants and resources such as orchards are vulnerable to the detrimental effects of successful invasions by alien animal or plant species. To outline an appropriate policy response, we first use renewal theory to construct a stochastic model of optimal orchard management in the presence of a deleterious alien species. Next, we derive the orchard manager’s long run expected cost (LREC) of orchard management per unit time. Finally, we show that when confronted with a successful biological invasion, the optimal number of trees that need to be removed and replanted in order to keep the orchard under study sustainable in …

High Accuracy Imaging Polarimetry With Nicmos, Daniel Batcheldor, G. Schneider, D.C. Hines, G. D. Schmidt, David J. Axon, Andew Robinson, W. Sparks, C. Tadhunter

Articles

The ability of NICMOS to perform high accuracy polarimetry is currently hampered by an uncalibrated residual instrumental polarization at a level of 1.2−1.5%. To better quantify and characterize this residual we obtained observations of three polarimetric standard stars at three separate space-craft roll angles. Combined with archival data, these observations were used to characterize the residual instrumental polarization to enable NICMOS to reach its full polarimetric potential. Using these data, we calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric …

Plasma-Controlled Metal Catalyst Saturation And The Initial Stage Of Carbon Nanostructure Array Growth, Igor Levchenko, Ken Ostrikov, Davide Mariotti, Anthony Bruce Murphy

Articles

The kinetics of the nucleation and growth of carbon nanotube and nanocone arrays on Ni catalyst nanoparticles on a silicon surface exposed to a low-temperature plasma are investigated numerically, using a complex model that includes surface diffusion and ion motion equations. It is found that the degree of ionization of the carbon flux strongly affects the kinetics of nanotube and nanocone nucleation on partially saturated catalyst patterns. The use of highly ionized carbon flux allows formation of a nanotube array with a very narrow height distribution of half-width 7 nm. Similar results are obtained for carbon nanocone arrays, with an …

Reducing Atmospheric Carbon Dioxide: Oceans Provide A Huge Opportunity For Sequestration, Jules Chiavaroli

Articles

The scientific community is fairly unified in their assessment of climatological change. It is happening primarily as the result of excess carbon dioxide (CO2) in the atmosphere produced by unrelenting world industrialization. If it continues unabated it will cause major physical changes to the earth that will dramatically alter how mankind lives. And, the world has until the middle of this century to cap CO2 levels short of where they will cause this irreversible change. For many experts involved in this issue, actively reducing existing CO2 levels is a necessary component for a total solution to the problem. This paper …

Three-Body Equations Of Motion In Successive Post-Newtonian Approximations, Carlos O. Lousto, Hiroyuki Nakano

Articles

There are periodic solutions to the equal-mass three-body (and N-body) problem in Newtonian gravity. The figure-eight solution is one of them. In this paper, we discuss its solution in the first and second post-Newtonian approximations to General Relativity. To do so we derive the canonical equations of motion in the ADM gauge from the three-body Hamiltonian. We then integrate those equations numerically, showing that quantities such as the energy, linear and angular momenta are conserved down to numerical error. We also study the scaling of the initial parameters with the physical size of the triple system. In this way we …

Extra-Large Remnant Recoil Velocities And Spins From Near-Extremal-Bowen-York-Spin Black-Hole Binaries, Sergio Dain, Carlos O. Lousto, Yosef Zlochower

Articles

We evolve equal-mass, equal-spin black-hole binaries with specific spins of a/mH 0.925, the highest spins simulated thus far and nearly the largest possible for Bowen-York black holes, in a set of configurations with the spins counter-aligned and pointing in the orbital plane, which maximizes the recoil velocities of the merger remnant, as well as a configuration where the two spins point in the same direction as the orbital angular momentum, which maximizes the orbital hang-up effect and remnant spin. The coordinate radii of the individual apparent horizons in these cases are very small and the simulations require very high central …

A Measurement Of The Rate Of Type Ia Supernovae At Redshift Z ≈ 0.1 From The First Season Of The Sdss-Ii Supernova Survey, Benjamin Dilday, Richard Kessler, Joshua Frieman, Michael W. Richmond, Et Al.

Articles

We present a measurement of the rate of type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift z ≤ 0.12. Assuming a flat cosmology with m = 0.3 = 1 − , we find a volumetric SN Ia rate of [2.93+0.17 −0.04(systematic)+0.90 −0.71(statistical)]×10−5 SNe Mpc−3 h3 70 year−1, at a volumeweighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the …

Stationary Rotating Strings As Relativistic Particle Mechanics, Kouji Ogawa, Hideki Ishihara, Hiroshi Kozaki, Hiroyuki Nakano, Shinya Saito

Articles

Stationary rotating strings can be viewed as geodesic motions in appropriate metrics on a two dimensional space. We obtain all solutions describing stationary rotating strings in flat space time strings have infinite length with various wiggly shapes. Averaged value of the string energy, the angular momentum and the linear momentum along the string are discussed.

Hubble Space Telescope Near-Infrared Snapshot Survey Of 3cr Radio Source Counterparts. Ii. An Atlas And Inventory Of The Host Galaxies, Mergers, And Companions, David J.E. Floyed, David J. Axon, Stefi A. Baum, Christopher P. O'Dea, Et Al.

Articles

We present the second part of an H-band (1.6 μm) “atlas” of z < 0.3 3CR radio galaxies, using the Hubble Space Telescope Near Infrared Camera and Multi- Object Spectrometer (HST NICMOS2). We present new imaging for 21 recently acquired sources, and host galaxy modeling for the full sample of 101 (including 11 archival) – an 87% completion rate. Two different modeling techniques are applied, following those adopted by the galaxy morphology and the quasar host galaxy communities. Results are compared, and found to be in excellent agreement, although the former breaks down in the case of strongly nucleated sources.

A Parallel Gravitational N-Body Kernel, Simon Portegies Zwart, Stephen Mcmillan, Derek Groen, Alessia Gualandris, Michael Sipior, Willem Vermin

Articles

We describe source code level parallelization for the kira direct gravitational Nbody integrator, the workhorse of the starlab production environment for simulating dense stellar systems. The parallelization strategy, called “j-parallelization”, involves the partition of the computational domain by distributing all particles in the system among the available processors. Partial forces on the particles to be advanced are calculated in parallel by their parent processors, and are then summed in a final global operation. Once total forces are obtained, the computing elements proceed to the computation of their particle trajectories. We report the results of timing measurements on four different parallel …

A New Method To Integrate (2+1)-Wave Equations With Dirac’S Delta Functions As Sources, Carlos O. Lousto, Hiroyuki Nakano

Articles

Unlike in the Schwarzschild black hole background, gravitational perturbations in a Kerr black hole background can not be decomposed into simple tensor harmonics in the time domain. Here, we make mode decompositions only in the azimuthal direction. As a first step, we discuss the resulting (2+1)-dimensional Klein-Gordon differential equation for scalar perturbations with a two dimensional Dirac’s -function as a source representing a point particle orbiting a much larger black hole. To make this equation amenable for numerical integrations we explicitly remove analytically the singular behavior of the source and compute a global, well behaved, effective source for the corresponding …

Survey Of Internet And At-Risk Behaviors, Samuel C. Mcquade Iii, Neel Sampat

Articles

In May 2007 though January 2008 fourteen Monroe County school districts in New York State participated in a major research study undertaken by the Rochester Institute of Technology (RIT). A major portion of the study was an online survey. It was designed to:

• Measure the nature and extent of online victimization and offending experiences of K-12th grade students
• Determine types and levels of supervision and role modeling employed by parents pertaining to the use of computers and portable electronic devices by their children; and
• Obtain information from teachers about their perceptions of school-related cyber abuse and crime, along with the …

Shared-Sensing And Control Using Reversible Transducers, Tuhin Das, Ranjan Mukherjee

Articles

As an alternative to self-sensing, we propose the concept of shared-sensing for reversible transducers. In shared-sensing, reversible transducers are continuously switched between actuator and sensor modes. This results in a hybrid system, and, in this paper, we investigate stability properties of the equilibrium for linear systems and a class of nonlinear systems with a single shared-sensing transducer. Our theoretical results are validated through simulations and experiments with a dc servo motor.

Implementation Of Standard Testbeds For Numerical Relativity, M. C. Babiuc, S. Husa, D. Alic, I. Hinder, C. Lechner, E. Schnetter, B. Szilágyi, Yosef Zlochower, N. Dorband, D. Pollney

Articles

We discuss results that have been obtained from the implementation of the initial round of testbeds for numerical relativity which was proposed in the first paper of the Apples with Apples Alliance. We present benchmark results for various codes which provide templates for analyzing the testbeds and to draw conclusions about various features of the codes. This allows us to sharpen the initial test specifications, design a new test and add theoretical insight.

The Hubble Space Telescope Advanced Camera For Surveys Coma Cluster Survey. I. Survey Objectives And Design, David Carter, Paul Goudfrooij, Bahram Mobasher, Dan Batcheldor, David Merritt, Et Al.

Articles

We describe the HST ACS Coma cluster Treasury survey, a deep twopassband imaging survey of one of the nearest rich clusters of galaxies, the Coma cluster (Abell 1656). The survey was designed to cover an area of 740 arcmin2 in regions of different density of both galaxies and intergalactic medium within the cluster. The ACS failure of January 27th 2007 leaves the survey 28% complete, with 21 ACS pointings (230 arcmin2) complete, and partial data for a further 4 pointings (44 arcmin2). Predicted survey depth for 10 detections for optimal photometry of point sources is g′ = 27.6 in the …

Close Encounters Of Three Black Holes, Manuela Campanelli, Carlos O. Lousto, Yosef Zlochower

Articles

We present the first fully relativistic longterm numerical evolutions of three equal-mass black holes in a system consisting of a third black hole in a close orbit about a black-hole binary. We find that these close-three-black-hole systems have very different merger dynamics from black-hole binaries. In particular, we see complex trajectories, a redistribution of energy that can impart substantial kicks to one of the holes, distinctive waveforms, and suppression of the emitted gravitational radiation. We evolve two such configurations and find very different behaviors. In one configuration the binary is quickly disrupted and the individual holes follow complicated trajectories and …

The Effect Of Radiation Pressure On Virial Black Hole Mass Estimates And The Case Of Narrow-Line Seyfert 1 Galaxies, Alessandro Marconi, David J. Axon, Roberto Maiolino, Tohru Nagao, Guia Pastorini, Paola Pietrini, Andew Robinson, Guidetta Torricelli

Articles

We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based on the application of the virial theorem to broad emission lines in AGN spectra. BH masses based only on the virial product V2R and neglecting the effect of radiation pressure can be severely underestimated especially in objects close to the Eddington limit. We provide an empirical calibration of the correction for radiation pressure and we show that it is consistent with a simple physical model in which BLR clouds are optically thick to ionizing radiation and have average column densities of NH ∼ …

Nonequilibrium And Effect Of Gas Mixtures In An Atmospheric Microplasma, Davide Mariotti

Articles

The gas and effective electron temperatures have been estimated for atmospheric microplasma by means of optical emission spectroscopy. The results have shown that the microplasma exhibits nonequilibrium and, as its size is reduced, the two temperatures depart from each other, enhancing the nonequilibrium characteristic. The effect of methane and oxygen concentrations has also been studied, showing that gas mixtures have an important effect on the microplasma state.

Hyperfast Pulsars As The Remnants Of Massive Stars Ejected From Young Star Clusters, Vasilii Gvaramadze, Alessia Gualandris, Simon P. Zwart

Articles

Recent proper motion and parallax measurements for the pulsar PSR B1508+55 indicate a transverse velocity of 1 100 kms−1, which exceeds earlier measurements for any neutron star. The spin-down characteristics of PSR B1508+55 are typical for a non-recycled pulsar, which implies that the velocity of the pulsar cannot have originated from the second supernova disruption of a massive binary system. The high velocity of PSR B1508+55 can be accounted for by assuming that it received a kick at birth or that the neutron star was accelerated after its formation in the supernova explosion. We propose an explanation for the origin …

Wfpc2 Lrf Imaging Of Emission Line Nebulae In 3cr Radio Galaxies, G. C. Privon, Christopher P. O'Dea, Stefi A. Baum, David J. Axom, P. Kharb, C. L. Buchanan, W. Sparks, M. Chiaberge

Articles

We present HST/WFPC2 Linear Ramp Filter images of high surface brightness emission lines (either [OII], [OIII], or H +[NII]) in 80 3CR radio sources. We overlay the emission line images on high resolution VLA radio images (eight of which are new reductions of archival data) in order to examine the spatial relationship between the optical and radio emission. We confirm that the radio and optical emission line structures are consistent with weak alignment at low redshift (z < 0.6) except in the Compact Steep Spectrum (CSS) radio galaxies where both the radio source and the emission line nebulae are on galactic scales and strong alignment is seen at all redshifts. There are weak trends for the aligned emission line nebulae to be more luminous, and for the emission line nebula size to increase with redshift and/or radio power. The combination of these results suggests that there is a limited but real capacity for the radio source to influence the properties of the emission line nebulae at these low redshifts (z < 0.6). Our results are consistent with previous suggestions that both mechanical and radiant energy are responsible for generating alignment between the radio source and emission line gas.

The Subaru/Xmm-Newton Deep Survey (Sxds) - V. Optically Faint Variable Object Survey, Tomoki Morokuma, Mamoru Doi, Naoki Yasuda, Michael Richmond, Et Al.

Articles

We present our survey for optically faint variable objects using multi-epoch (8−10 epochs over 2−4 years) i′-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg2 in the Subaru/XMMNewton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10m class telescopes or HST. The detection limit for variable components is i′ vari 25.5 mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGN), based on the optical morphologies, magnitudes, …

Design Of A Multiple Component Geometric Breast Phantom, Karl G. Baum, Kevin Mcnamara, María Helguera

Articles

The quality and realism of simulated images is currently limited by the quality of the digital phantoms used for the simulations. The transition from simple raster based phantoms to more detailed geometric (mesh) based phantoms has the potential to increase the usefulness of the simulated data. A preliminary breast phantom which contains 12 distinct tissue classes along with the tissue properties necessary for the simulation of dynamic positron emission tomography scans was created (activity and attenuation). The phantom contains multiple components which can be separately manipulated, utilizing geometric transformations, to represent populations or a single individual being imaged in multiple …

The Origin Of The Infrared Emission In Radio Galaxies. I. New Mid- To Far-Infrared And Radio Observations Of The 2 Jy Sample, D. Dicken, Clive Tadhunter, Raffaella Morganti, C. Buchanan, T. Oosterloo, David J. Axon

Articles

As part of a large study to investigate the nature of the longer wavelength continuum emission of radio-loud AGN, we present new mid to far-infrared (MFIR) and high frequency radio observations for a complete sample of 2Jy powerful, southern radio galaxies at intermediate redshifts (0.05 < z < 0.7). Utilizing the sensitivity of the Spitzer Space Telescope, we have made deep MIPS observations at the wavelengths of 24, 70 and 160μm, detecting 100% of our sample at 24μm and 90% at 70μm. This high detection rate at MFIR wavelengths is unparallelled in samples of intermediate redshift radio galaxies. Complementing these results, we also present new high frequency observations (15 to 24Ghz) from the Australia Telescope Compact Array (ATCA) and the Very Large Array (VLA), which are used to investigate the potential contamination of the MFIR continuum by non-thermal synchrotron emission. With the latter observations we detect the compact cores in 59% of our complete sample, and deduce that non-thermal contamination of the MFIR continuum is significant in a maximum of 30% of our total sample. MFIR fluxes, radio fluxes and spectral energy distributions for the complete sample are presented here, while in a second paper we will analyse these data and discuss the implications for our understanding of the heating mechanism for the warm/cool dust, star formation in the host galaxies, and the unified schemes for powerful radio sources.

Further Insight Into Gravitational Recoil, Carlos O. Lousto, Yosef Zlochower

Articles

We test the accuracy of our recently proposed empirical formula to model the recoil velocity imparted to the merger remnant of spinning, unequal-mass black-hole binaries. We study three families of black-hole binary configurations, all with mass ratio q=3/8 (to maximize the unequal-mass contribution to the kick) and spins aligned (or counter aligned) with the orbital angular momentum, two with spin configurations chosen to minimize the spin-induced tangential and radial accelerations of the trajectories respectively, and a third family where the trajectories are significantly altered by spin-orbit coupling. We find good agreement between the measured and predicted recoil velocities for the …

On The Onset Of Runaway Stellar Collisions In Dense Star Clusters - I. Dynamics Of The First Collision, Evghenii Gaburov, Alessia Gualandris, Simon P. Zwart

Articles

We study the circumstances under which first collisions occur in young and dense star clusters. The initial conditions for our direct N-body simulations are chosen such that the clusters experience core collapse within a few million years, before the most massive stars have left the main-sequence. It turns out that the first collision is typically driven by the most massive stars in the cluster. Upon arrival in the cluster core, by dynamical friction, massive stars tend to form binaries. The enhanced cross section of the binary compared to a single star causes other stars to engage the binary. A collision …

Plane Decompositions As Tools For Approximation, Melanie J. Agnew, Christopher M. Homan

Articles

Tree decompositions were developed by Robertson and Seymour [21]. Since then algorithms have been developed to solve intractable problems efficiently for graphs of bounded tree width. In this paper we extend tree decompositions to allow cycles to exist in the decomposition graph; we call these new decompositions plane decompositions because we require that the decomposition graph be planar. First, we give some background material about tree decompositions and an overview of algorithms both for decompositions and for approximations of planar graphs. Then, we give our plane decomposition definition and an algorithm that uses this decomposition to approximate the size of …

Foundations Of Multiple Black Hole Evolutions, Carlos O. Lousto, Yosef Zlochower

Articles

We present techniques for long-term, stable, and accurate evolutions of multiple-black-hole spacetimes using the ‘moving puncture’ approach with fourth- and eighth-order finite difference stencils. We use these techniques to explore configurations of three black holes in a hierarchical system consisting of a third black hole approaching a quasi-circular black-hole binary, and find that, depending on the size of the binary, the resulting encounter may lead to a prompt merger of all three black holes, production of a highly elliptical binary (with the third black hole remaining unbound), or disruption of the binary (leading to three free black holes). We also …

An Fio Calculus For Marine Seismic Imaging: Folds And Cross Caps, Raluca Felea, Allan Greenleaf

Articles

We consider a linearized inverse problem, arising in offshore seismic exploration, for an isotropic wave equation with sound speed assumed to be a small, singular perturbation of a smooth background. Under an assumption of at most fold caustics for the background, we identify the geometry of the canonical relation underlying the linearization, F, which is a Fourier integral operator, and establish a composition calculus sufficient to describe the normal operator F^*F. The resulting artifacts are 1/2 derivative smoother than in the case of a single-source seismic experiment. Refer to PDF file for exact formula.)