Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Distances and redshifts (3)
- Elliptical and lenticular (3)
- Galaxies (3)
- Mobile computing (3)
- Mobile-agent (3)
-
- Astrophysics (2)
- Cd (2)
- Clusters (2)
- Physics (2)
- CD (1)
- Computational physics (1)
- Condensed matter (1)
- Cosmology (1)
- Fundamental parameters (1)
- Galaxies: evolution (1)
- Galaxiy evolution (1)
- Galaxy distances and redshifts (1)
- Galaxy formation (1)
- High energy physics (1)
- Inflationary universe (1)
- Keywords: Binaries: close||Stars: abundances||Ultraviolet: stars||White dwarfs||ANU Digital Collections Repository||Journal article (1)
- Large-scale structure of universe (1)
- Lattice (1)
- Lusters (1)
- Magnetospheric physics (energetic particles (1)
- Nonlinear sciences (1)
- Pattern formation and solitons (1)
- Phenomenology (1)
- Proper interval graph (1)
- Quantum field theory (1)
- Publication
- Publication Type
Articles 1 - 30 of 38
Full-Text Articles in Entire DC Network
Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling
Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling
Dartmouth Scholarship
Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the reality of large-scale streaming motion; results of this study have been reported in M\"uller $et$ $al.$ (1998). The new APM South Equatorial Strip Catalog (−17.5 < δ < +2.5) was used to select the sample of field galaxies in three directions: (1) 15h10 – 16h10; (2) 20h30 – 21h50; (3) 00h10 – 01h30. The spectra obtained have a median S/N per ̊A of 23, an in- strumental resolution (FWHM) of ∼ 4 ̊A, and the spectro- graph resolution (dispersion) is ∼ 100 km s−1. The Fourier cross-correlation method was used to derive the radial ve- locities and velocity dispersions. The velocity dispersions have been corrected for the size of the aperture and for the galaxy effective radius. Comparisons of the derived radial velocities with data from the literature show that our values are accurate to 40 km s−1. A comparison with results from Jørgensen et al. (1995) shows that the derived central velocity dispersion have an rms scatter of 0.036 in log σ. There is no offset relative to the velocity dispersions of Davies et al. (1987).
Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul
Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul
Dartmouth Scholarship
As a study of peculiar velocities of nonlinear structure, we analyze the model of a relativistic thin-shell void in the expanding universe. (1) Adopting McVittie (MV) spacetime as a background universe, we investigate the dynamics of an uncompensated void with negative MV mass. Although the motion itself is quite different from that of a compensated void, as shown by Haines & Harris (1993), the present peculiar velocities are not affected by MV mass. (2) We discuss how precisely the formula in the linear perturbation theory applies to nonlinear relativistic voids, using the results in (1) as well as the previous …
An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz
An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz
Computer Science Technical Reports
In our quest to give users uniform access to resources unimpeded by administrative boundaries, we discovered that we needed transitive sharing among users, with the possibility of restricted access along each sharing link. To achieve that goal, we extend Lampson et al.'s calculus for access control to support restricted delegations. We discuss the advantages of our extension, including the simplification of constructs like ACLs and statement expiration. We also apply our extension to model the Simple Public Key Infrastructure and make suggestions about its future development. Our extended calculus exposes some surprising consequences in such systems that use restricted delegation.
The Pulsation Properties Of Procyon A, Brian Chaboyer, P. Demarque, D. B. Guenther
The Pulsation Properties Of Procyon A, Brian Chaboyer, P. Demarque, D. B. Guenther
Dartmouth Scholarship
A grid of stellar evolution models for Procyon A has been calculated. These models include the best physics available to us (including the latest opacities and equation of state) and are based on the revised astrometric mass of Girard et al. Models were calculated with helium diffusion and with the combined effects of helium and heavy-element diffusion. Oscillation frequencies for l = 0, 1, 2, and 3 p-modes and the characteristic period spacing for the g-modes were calculated for these models. We find that g-modes are sensitive to model parameters that effect the structure of the core, …
Resonant Enhancement Of Relativistic Electron Fluxes During Geomagnetically Active Periods, I Roth, M Temerin, M K. Hudson
Resonant Enhancement Of Relativistic Electron Fluxes During Geomagnetically Active Periods, I Roth, M Temerin, M K. Hudson
Dartmouth Scholarship
The strong increase in the ̄ux of relativistic electrons during the recovery phase of magnetic storms and during other active periods is investigated with the help of Hamiltonian formalism and simulations of test electrons which interact with whistler waves. The intensity of the whistler waves is enhanced signi®cantly due to injection of 10±100 keV electrons during the substorm. Electrons which drift in the gradient and curvature of the magnetic ®eld generate the rising tones of VLF whistler chorus. The seed population of relativ- istic electrons which bounce along the inhomogeneous magnetic ®eld, interacts resonantly with the whistler waves. Whistler wave …
Sar By Ms For Functional Genomics (Structure-Activity Relation By Mass Spectrometry), Bruce Randall Donald, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein
Sar By Ms For Functional Genomics (Structure-Activity Relation By Mass Spectrometry), Bruce Randall Donald, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein
Computer Science Technical Reports
Large-scale functional genomics will require fast, high-throughput experimental techniques, coupled with sophisticated computer algorithms for data analysis and experiment planning. In this paper, we introduce a combined experimental-computational protocol called Structure-Activity Relation by Mass Spectrometry (SAR by MS), which can be used to elucidate the function of protein-DNA or protein-protein complexes. We present algorithms for SAR by MS and analyze their complexity. Carefully-designed Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI TOF) and Electrospray Ionization (ESI) assays require only femtomolar samples, take only microseconds per spectrum to record, enjoy a resolution of up to one dalton in $10^6$, and (in the case of …
A Game-Theoretic Formulation Of Multi-Agent Resource Allocation, Jonathan Bredin, Rajiv T. Maheswaran, Cagri Imer, Tamer Basar, David Kotz, Daniela Rus
A Game-Theoretic Formulation Of Multi-Agent Resource Allocation, Jonathan Bredin, Rajiv T. Maheswaran, Cagri Imer, Tamer Basar, David Kotz, Daniela Rus
Computer Science Technical Reports
This paper considers resource allocation in a network with mobile agents competing for computational priority. We formulate this problem as a multi-agent game with the players being agents purchasing service from a common server. We show that there exists a computable Nash equilibrium when agents have perfect information into the future. We simulate a network of hosts and agents using our strategy to show that our resource-allocation mechanism effectively prioritizes agents according to their endowments.
Stellar Masses, Kinematics, And White Dwarf Composition For Three Close Da+Dme Binaries, Stephane Vennes, John R. Thorstensen, Elisha F. Polomski
Stellar Masses, Kinematics, And White Dwarf Composition For Three Close Da+Dme Binaries, Stephane Vennes, John R. Thorstensen, Elisha F. Polomski
Dartmouth Scholarship
We determine the mass functions and mass ratios for three close white dwarf plus red dwarf binaries (EUVE J0720-317, 1016-053, and 2013+400). Hubble Space Telescope Goddard High-Resolution Spectrograph spectra of the He II λ1640 and C IV λ1550 spectral lines trace the white dwarf orbital motion, and Hamilton Spectrograph echelle spectra (Lick Observatory) and lower dispersion spectra trace the red dwarf orbital motion. The data sets allow us to measure orbital periods and velocities, as well as the white dwarf gravitational redshifts. The red dwarf and white dwarf mass estimates obtained from a combination of independent mass measurements for the …
Large‐Scale Power Spectrum And Cosmological Parameters From Sfi Peculiar Velocities, Wolfram Freudling, Idit Zehavi, Luiz N. Da Costa, Avishai Dekel, Amiram Eldar, Riccardo Giovanelli, Martha P. Haynes, John J. Salzer, Gary Wegner, Saleem Zaroubi
Large‐Scale Power Spectrum And Cosmological Parameters From Sfi Peculiar Velocities, Wolfram Freudling, Idit Zehavi, Luiz N. Da Costa, Avishai Dekel, Amiram Eldar, Riccardo Giovanelli, Martha P. Haynes, John J. Salzer, Gary Wegner, Saleem Zaroubi
Dartmouth Scholarship
We estimate the power spectrum of mass density fluctuations from peculiar velocities of galaxies by applying an improved maximum likelihood technique to the new all-sky SFI catalog. Parametric models are used for the power spectrum and the errors, and the free parameters are determined by assuming Gaussian velocity fields and errors and maximizing the probability of the data given the model. It has been applied to generalized cold dark matter (CDM) models with and without COBE normalization. The method has been carefully tested using artificial SFI catalogs. The most likely distance errors are found to be similar to the original …
Long-Lived Localized Field Configurations In Small Lattices: Application To Oscillons, M. Gleiser, A. Sornborger
Long-Lived Localized Field Configurations In Small Lattices: Application To Oscillons, M. Gleiser, A. Sornborger
Dartmouth Scholarship
Long-lived localized field configurations such as breathers, oscillons, or more complex objects naturally arise in the context of a wide range of nonlinear models in different numbers of spatial dimensions. We present a numerical method, which we call the adiabatic damping method, designed to study such configurations in small lattices. Using three-dimensional oscillons in φ4 models as an example, we show that the method accurately (to one part in 105 or better) reproduces results obtained with static or dynamically expanding lattices, dramatically cutting down in integration time. We further present results for two-dimensional oscillons, whose lifetimes would be prohibitively …
Mobile Agents And The Future Of The Internet, David Kotz, Robert S. Gray
Mobile Agents And The Future Of The Internet, David Kotz, Robert S. Gray
Dartmouth Scholarship
Use of the Internet has exploded in recent years with the appearance of the World-Wide Web. In this paper, we show how current technological trends may lead to a system based substantially on mobile code, and in many cases, mobile agents. We discuss several technical and non-technical hurdles along the path to that eventuality. It seems likely that, within a few years, nearly all major Internet sites will be capable of hosting and willing to host some form of mobile code or mobile agents.
A First Principles Warm Inflation Model That Solves The Cosmological Horizon And Flatness Problems, Arjun Berera, Marcelo Gleiser, Rudnei O. Ramos
A First Principles Warm Inflation Model That Solves The Cosmological Horizon And Flatness Problems, Arjun Berera, Marcelo Gleiser, Rudnei O. Ramos
Dartmouth Scholarship
A quantum field theory warm inflation model is presented that solves the horizon and flatness problems. The model obtains, from the elementary dynamics of particle physics, cosmological scale factor trajectories that begin in a radiation dominated regime, enter an inflationary regime, and then smoothly exit back into a radiation dominated regime, with non-negligible radiation throughout the evolution.
An Ultraviolet Fe Ii Image Of Sn 1885 In M31, Andrew Js Hamilton, Robert A. Fesen
An Ultraviolet Fe Ii Image Of Sn 1885 In M31, Andrew Js Hamilton, Robert A. Fesen
Dartmouth Scholarship
Ultraviolet imaging of the remnant of Supernova 1885 in M31 with the Hubble Space Telescope using the F255W filter on the WFPC2 reveals a dark spot of Fe II absorption at the remnant’s known position′′ ′′in the bulge of M31. The diameter of the absorbing spot is 0. 55 ± 0. 15, slightly smaller than, but′′ ′′consistent with, the 0. 70 ± 0. 05 diameter measured in the higher quality WFPC2 Ca II absorption image previously reported by us. The measured ratio of flux inside to outside SNR 1885 in the Fe IIimage is 0.24 ± 0.17, consistent with the …
Existence Theorems For Scheduling To Meet Two Objectives, April M. Rasala
Existence Theorems For Scheduling To Meet Two Objectives, April M. Rasala
Dartmouth College Undergraduate Theses
We will look at the existence of schedules which are simultaneously near-optimal for two criteria. First, we will present some techniques for proving existence theorems, in a very general setting, for bicriterion scheduling problems. We will then use these techniques to prove existence theorems for a large class of problems. We will consider the relationship between objective functions based on completion time, flow time, lateness and the number of on-time jobs. We will also present negative results first for the problem of simultaneously minimizing the maximum flow time and average weighted flow time and second for minimizing the maximum flow …
A Two Dimensional Crystalline Atomic Unit Modular Self-Reconfigurable Robot, Marsette Arthur Vona Iii
A Two Dimensional Crystalline Atomic Unit Modular Self-Reconfigurable Robot, Marsette Arthur Vona Iii
Dartmouth College Undergraduate Theses
Self-reconfigurable robots are designed so that they can change their external shape without human intervention. One general way to achieve such functionality is to build a robot composed of multiple, identical unit modules. If the modules are designed so that they can be assembled into rigid structures, and so that individual units within such structures can be relocated within and about the structure, then self-reconfiguration is possible. We propose the Crystalline Atomic unit modular self-reconfigurable robot, where each unit is called an Atom. In two dimensions, an Atom is square. Connectors at the faces of each Atom support structure formation …
An Application Of Word Sense Disambiguation To Information Retrieval, Jason M. Whaley
An Application Of Word Sense Disambiguation To Information Retrieval, Jason M. Whaley
Dartmouth College Undergraduate Theses
The problems of word sense disambiguation and document indexing for information retrieval have been extensively studied. It has been observed that indexing using disambiguated meanings, rather than word stems, should improve information retrieval results. We present a new corpus-based algorithm for performing word sense disambiguation. The algorithm does not need to train on many senses of each word; it uses instead the probability that certain concepts will occur together. That algorithm is then used to index several corpa of documents. Our indexing algorithm does not generally outperform the traditional stem-based tf.idf model.
Computers, Art And Smart Rooms: A Smart Picture Frame That Senses The Weather And Genetically Evolves Images, Marisa E. Kolodny
Computers, Art And Smart Rooms: A Smart Picture Frame That Senses The Weather And Genetically Evolves Images, Marisa E. Kolodny
Dartmouth College Undergraduate Theses
By using sensors to sense the environment and genetic programming to evolve images, this thesis explores two methods for developing smart pictures that can be integrated with a living space. The system presented senses the weather and indoor conditions, displays current weather and forecast information retrieved from the web, and displays genetically evolved images. Sensing the weather not only provides the user with information they might find useful, but also allows the computer to gain a better understanding of the user which in turn allows the computer to respond more accurately. Genetic programming allows the computer to better respond to …
The Implementation Of Dassf Otcl Apis, Hongxia Quan
The Implementation Of Dassf Otcl Apis, Hongxia Quan
Dartmouth College Undergraduate Theses
As an extension of Tcl, Otcl provides basic functionality for object-oriented programming in scripting language Tcl. We implemented the Otcl APIs for DaSSF (a parallel simulator software written in C++ at Dartmouth College) using Tclcl software package written in University of California at Berkeley. This document discussed the issues involved in the implementation, especially the communications between C++ objects and Otcl objects required by DaSSF and the naming problems.
Improved Computer Detection And Mapping Of Cerebral Oxygenation, David H. Kung
Improved Computer Detection And Mapping Of Cerebral Oxygenation, David H. Kung
Dartmouth College Undergraduate Theses
Near-infrared (NIR) optical image reconstruction that incorporates blood oxygen level dependant (BOLD) magnetic resonance imaging has the potential to improve both quantifiable measurement of oxygenation and the spatial resolution involved in such mapping. My thesis continues some preliminary work in this area through development of an analytic diffusion parameter estimation algorithm for use with a NIR imaging array and development of a finite element mesh utility to read a priori BOLD images and tag them with property elements for NIR image resolution improvement.
Two Algorithms For Performing Multidimensional, Multiprocessor, Out-Of-Core Ffts, Lauren M. Baptist
Two Algorithms For Performing Multidimensional, Multiprocessor, Out-Of-Core Ffts, Lauren M. Baptist
Dartmouth College Undergraduate Theses
We show two algorithms for computing multidimensional Fast Fourier Transforms (FFTs) on a multiprocessor system with distributed memory when problem sizes are so large that the data do not fit in the memory of the entire system. Instead, data reside on a parallel disk system and are brought into memory in sections. We use the Parallel Disk Model for implementation and analysis. The first method is a straightforward out-of-core variant of a well-known method for in-core, multidimensional FFTs. It performs 1-dimensional FFT computations on each dimension in turn. This method is easy to generalize to any number of dimensions, and …
Fast Out-Of-Core Sorting On Parallel Disk Systems, Matthew D. Pearson
Fast Out-Of-Core Sorting On Parallel Disk Systems, Matthew D. Pearson
Dartmouth College Undergraduate Theses
This paper discusses our implementation of Rajasekaran's (l,m)-mergesort algorithm (LMM) for sorting on parallel disks. LMM is asymptotically optimal for large problems and has the additional advantage of a low constant in its I/O complexity. Our implementation is written in C using the ViC* I/O API for parallel disk systems. We compare the performance of LMM to that of the C library function qsort on a DEC Alpha server. qsort makes a good benchmark because it is fast and performs comparatively well under demand paging. Since qsort fails when the swap disk fills up, we can only compare these algorithms …
Investigating Measures For Pairwise Document Similarity, Jeffrey D. Isaacs
Investigating Measures For Pairwise Document Similarity, Jeffrey D. Isaacs
Dartmouth College Undergraduate Theses
The need for a more effective similarity measure is growing as a result of the astonishing amount of information being placed online. Most existing similarity measures are defined by empirically derived formulas and cannot easily be extended to new applications. We present a pairwise document similarity measure based on Information Theory, and present corpus dependent and independent applications of this measure. When ranked with existing similarity measures over TREC FBIS data, our corpus dependent information theoretic similarity measure ranked first.
Parallel Dassf Discrete-Event Simulation Without Shared Memory, James D. Chalfant
Parallel Dassf Discrete-Event Simulation Without Shared Memory, James D. Chalfant
Dartmouth College Undergraduate Theses
The Dartmouth implementation of the Scalable Simulation Framework (DaSSF) is a discrete-event simulator used primarily in the simulation of networks. It achieves high performance through parallel processing. DaSSF 1.22 requires shared memory between all processors in order to operate. This limits the number of processors available and the hardware platforms that can exploit parallelism. We are interested in extending parallel DaSSF operation to architectures without shared memory. We explore the requirements of this by implementing parallel DaSSF using MPI as the sole form of interaction between processors. The approaches used to achieve this can be abstracted and applied to the …
An Environment For The Facilitation Of Robotic Programming, Artem Lifschitz
An Environment For The Facilitation Of Robotic Programming, Artem Lifschitz
Computer Science Technical Reports
I have developed, tested, and evaluated a robot programming environment organized as a library of flexible data structures to facilitate the creation of robotics programs. Abstractions are the basis of all of the achievements of Computer Science, and if it were possible to create a truly flexible, generic abstraction for the programming of robots -- the science of robotics could advance at a faster pace. For this reason, I have attempted to implement the abstraction of low-level commands, and the assembling of them into hierarchies of higher-level actions. My libraries provide mechanisms for the manipulation and queuing of actions, as …
Mobile-Agent Planning In A Market-Oriented Environment, Jonathan Bredin, David Kotz, Daniela Rus
Mobile-Agent Planning In A Market-Oriented Environment, Jonathan Bredin, David Kotz, Daniela Rus
Computer Science Technical Reports
We propose a method for increasing incentives for sites to host arbitrary mobile agents in which mobile agents purchase their computing needs from host sites. We present a scalable market-based CPU allocation policy and an on-line algorithm that plans a mobile agent's expenditure over a multihop ordered itinerary. The algorithm chooses a set of sites at which to execute and computational priorities at each site to minimize execution time while preserving a prespecified budget constraint. We present simulation results of our algorithm to show that our allocation policy and planning algorithm scale well as more agents are added to the …
The Peculiar Motions Of Early-Type Galaxies In Two Distant Rregions — Ii. The Spectroscopic Data, Gary Wegner, Matthew Colless, R. P. Saglia, Robert K. Mcmahan
The Peculiar Motions Of Early-Type Galaxies In Two Distant Rregions — Ii. The Spectroscopic Data, Gary Wegner, Matthew Colless, R. P. Saglia, Robert K. Mcmahan
Dartmouth Scholarship
We present the spectroscopic data for the galaxies studied in the EFAR project, which is designed to measure the properties and peculiar motions of early-type galaxies in two distant regions. We have obtained 1319 spectra of 714 early-type galaxies over 33 observing runs on 10 different telescopes. We describe the observations and data reductions used to measure redshifts, velocity dispersions and the Mgb and Mg2 Lick linestrength indices. Detailed simulations and intercomparison of the large number of repeat observations lead to reliable error estimates for all quantities. The measurements from different observing runs are calibrated to a common …
Using Haptic Vector Fields For Animation Motion Control, Bruce Randall Donald, Frederick Henle
Using Haptic Vector Fields For Animation Motion Control, Bruce Randall Donald, Frederick Henle
Computer Science Technical Reports
We are exploring techniques for animation authoring and editing using a haptic force-feedback device. In our system, a family of animations is encoded by a bundle of trajectories. This bundle in turn defines a time-varying, higher-order vector field on a configuration space for the animation. A haptic input device provides a low-dimensional parameterization of the resulting dynamical system, and the haptic force feedback permits browsing and editing of the space of animations, by allowing the user to experience the vector field as physical forces.
The I-Band Tully-Fisher Relation For Sc Galaxies: 21 Centimeter H I Line Data, Martha P. Haynes, Riccardo Giovanelli, Pierre Chamaraux, Luiz N. Da Costa, Wolfram Freudling, John J. Salzer, Gary Wegner
The I-Band Tully-Fisher Relation For Sc Galaxies: 21 Centimeter H I Line Data, Martha P. Haynes, Riccardo Giovanelli, Pierre Chamaraux, Luiz N. Da Costa, Wolfram Freudling, John J. Salzer, Gary Wegner
Dartmouth Scholarship
A compilation of 21 cm line spectral parameters specifically designed for application of the Tully-Fisher (TF) distance method is presented for 1201 spiral galaxies, primarily field Sc galaxies, for which optical I-band photometric imaging is also available. New H I line spectra have been obtained for 881 galaxies. For an additional 320 galaxies, spectra available in a digital archive have been reexamined to allow application of a single algorithm for the derivation of the TF velocity width parameter. A velocity width algorithm is used that provides a robust measurement of rotational velocity and permits an estimate of the error …
Economic Markets As A Means Of Open Mobile-Agent Systems, Jonathan Bredin, David Kotz, Daniela Rus
Economic Markets As A Means Of Open Mobile-Agent Systems, Jonathan Bredin, David Kotz, Daniela Rus
Dartmouth Scholarship
Mobile-agent systems have gained popularity in use because they ease the application design process by giving software engineers greater flexibility. Although the value of any network is dependent on both the number of users and the number of sites participating in the network, there is little motivation for systems to donate resources to arbitrary agents. We propose to remedy the problem by imposing an economic market on mobile-agent systems where agents purchase resources from host sites and sell services to users and other agents. Host sites accumulate revenues, which are distributed to users to be used to launch more agents. …
Mobile Code: The Future Of The Internet, David Kotz, Robert S. Gray
Mobile Code: The Future Of The Internet, David Kotz, Robert S. Gray
Dartmouth Scholarship
Use of the Internet has exploded in recent years with the appearance of the World-Wide Web. In this paper, we show how current technological trends necessarily lead to a system based substantially on mobile code, and in many cases, mobile agents. We discuss several technical and non-technical hurdles along the path to that eventuality. Finally, we predict that, within five years, nearly all major Internet sites will be capable of hosting and willing to host some form of mobile agents.