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Dartmouth College

2009

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Articles 31 - 60 of 67

Full-Text Articles in Physical Sciences and Mathematics

Hydrodynamic Relaxation Of An Electron Plasma To A Near-Maximum Entropy State, D. J. Rodgers, S. Servidio, W. H. Matthaeus, D. C. Montgomery, T. B. Mitchell, T. Aziz Jun 2009

Hydrodynamic Relaxation Of An Electron Plasma To A Near-Maximum Entropy State, D. J. Rodgers, S. Servidio, W. H. Matthaeus, D. C. Montgomery, T. B. Mitchell, T. Aziz

Dartmouth Scholarship

Dynamical relaxation of a pure electron plasma in a Malmberg-Penning trap is studied, comparing experiments, numerical simulations and statistical theories of weakly dissipative two-dimensional (2D) turbulence. Simulations confirm that the dynamics are approximated well by a 2D hydrodynamic model. Statistical analysis favors a theoretical picture of relaxation to a near-maximum entropy state with constrained energy, circulation, and angular momentum. This provides evidence that 2D electron fluid relaxation in a turbulent regime is governed by principles of maximum entropy.

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Data For Cybersecurity Research: Process And ‘Wish List’, Jean Camp, Lorrie Cranor, Nick Feamster, Joan Feigenbaum, Stephanie Forrest, David Kotz, Wenke Lee, Patrick Lincoln, Vern Paxson, Mike Reiter, Ron Rivest, William Sanders, Stefan Savage, Sean Smith, Eugene Spafford, Sal Stolfo Jun 2009

Data For Cybersecurity Research: Process And ‘Wish List’, Jean Camp, Lorrie Cranor, Nick Feamster, Joan Feigenbaum, Stephanie Forrest, David Kotz, Wenke Lee, Patrick Lincoln, Vern Paxson, Mike Reiter, Ron Rivest, William Sanders, Stefan Savage, Sean Smith, Eugene Spafford, Sal Stolfo

Other Faculty Materials

This document identifies data needs of the security research community. This document is in response to a request for a “data wish list”. Because specific data needs will evolve in conjunction with evolving threats and research problems, we augment the wish list with commentary about some of the broader issues for data usage.

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Automated Tracking Of Dividing Nuclei In Microscopy Videos Of Living Cells, Evan L. Tice Jun 2009

Automated Tracking Of Dividing Nuclei In Microscopy Videos Of Living Cells, Evan L. Tice

Dartmouth College Undergraduate Theses

Many cell biologists perform analysis of multinucleated cell data in order to better under- stand the mechanisms that regulate cell division. Sbalzarini, et al., have developed methods for automatically tracking nuclei in cell data in order to aid in this time-consuming analysis. In this paper, we present an implementation of the Sbalzarini tracking algorithm, introduce a new algorithm we developed which is able to identify mitosis events, and present other software tools we have developed to aid in the automated detection of nucleus data.

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The Effects Of Introspection On Computer Security Policies, Stephanie A. Trudeau Jun 2009

The Effects Of Introspection On Computer Security Policies, Stephanie A. Trudeau

Dartmouth College Undergraduate Theses

What does it mean to be an expert? And what makes an expert more capable than a non-expert when it comes to evaluating and articulating their impressions about something as commonly practiced as food tasting? How do we explain those behaviors that humans perform very well, but don't quite know why? Studies have shown that there exists a class of activities that we as humans execute well intuitively, but that we perform much worse upon introspection. Evidence supports the claim that the act of introspection actually causes us to do more poorly at these tasks. My goal is to apply …

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Developing An Improved, Web-Based Classroom Response System With Web Services, Oleg B. Seletsky Jun 2009

Developing An Improved, Web-Based Classroom Response System With Web Services, Oleg B. Seletsky

Dartmouth College Undergraduate Theses

Classroom Response Systems (CRS) are an in-class technology used to poll students and instantly display an aggregate representation of their responses. CRS have been around since the 1970s and have become increasingly more popular in higher education lecture halls. Even though technology, specifically computers and communications, has improved significantly since the 1970s, CRS have remained surprisingly unchanged. The purpose of this project was to develop an innovative web-based CRS using web services. The web-based aspect utilizes Dartmouth's wireless campus while the web services back-end makes the product more extensible. Lastly, we added a set of out-of-class learning tools for students …

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Failure To Replicate A Genetic Association May Provide Important Clues About Genetic Architecture, Casey S. Greene, Nadia M. Penrod, Scott M. Williams, Jason H. Moore Jun 2009

Failure To Replicate A Genetic Association May Provide Important Clues About Genetic Architecture, Casey S. Greene, Nadia M. Penrod, Scott M. Williams, Jason H. Moore

Dartmouth Scholarship

Replication has become the gold standard for assessing statistical results from genome-wide association studies. Unfortunately this replication requirement may cause real genetic effects to be missed. A real result can fail to replicate for numerous reasons including inadequate sample size or variability in phenotype definitions across independent samples. In genome-wide association studies the allele frequencies of polymorphisms may differ due to sampling error or population differences. We hypothesize that some statistically significant independent genetic effects may fail to replicate in an independent dataset when allele frequencies differ and the functional polymorphism interacts with one or more other functional polymorphisms. To …

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An Information Complexity Approach To The Inner Product Problem, William B. Henderson-Frost Jun 2009

An Information Complexity Approach To The Inner Product Problem, William B. Henderson-Frost

Dartmouth College Undergraduate Theses

We prove a lower bound of the randomized communication complexity of the inner product function on the uniform distribution.

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Hawk: 3d Gestured-Based Interactive Bird Flight Simulation, Thomas Yale Eastman Jun 2009

Hawk: 3d Gestured-Based Interactive Bird Flight Simulation, Thomas Yale Eastman

Dartmouth College Undergraduate Theses

Control interfaces provide the most tangible connection between human users and computer software. This link is especially important in interactive real-time applications, like games and simulations, because users desire efficient controls that allow them to maximize their interactivity and immersion with the software. Traditionally, interfaces have been largely limited to keyboards and mice. Recently, however, technological advances have made motion-sensitive devices not only available to mainstream consumers but have also lifted restrictions limiting devices to two-dimensional motion. This work presents a 3-dimensional motion-sensitive interface alongside a natural application. Players can control a soaring red-tailed hawk and perform various intuitive flight …

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Surface Reconstruction Through Time, Leeann T. Brash Jun 2009

Surface Reconstruction Through Time, Leeann T. Brash

Dartmouth College Master’s Theses

Surface reconstruction is an area of computational geometry that has been progressing rapidly over the last decade. Current algorithms and their implementations can reconstruct surfaces from a variety of input and the accuracy and precision improve with each new development. These all make use of various heuristics to achieve a reconstruction. Much of this work consists of reconstructing a still object from point samples taken from the object's surface. We examine reconstructing an n-dimensional object and its motion by treating time as an (n + 1)st axis. Our input consists of (n-1)-dimensional scans taken over time and at di?erent positions …

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A Computational Framework For Certificate Policy Operations, Gabriel A. Weaver, Scott Rea, Sean W. Smith Jun 2009

A Computational Framework For Certificate Policy Operations, Gabriel A. Weaver, Scott Rea, Sean W. Smith

Computer Science Technical Reports

The trustworthiness of any Public Key Infrastructure (PKI) rests upon the expectations for trust, and the degree to which those ex- pectations are met. Policies, whether implicit as in PGP and SDSI/SPKI or explicitly required as in X.509, document expectations for trust in a PKI. The widespread use of X.509 in the context of global e-Science infrastructures, financial institutions, and the U.S. Federal government demands efficient, transparent, and reproducible policy decisions. Since current manual processes fall short of these goals, we designed, built, and tested computational tools to process the citation schemes of X.509 certificate policies defined in RFC 2527 …

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Applying Domain Knowledge From Structured Citation Formats To Text And Data Mining: Examples Using The Cite Architecture, D Neel Smith, Gabriel A. Weaver Jun 2009

Applying Domain Knowledge From Structured Citation Formats To Text And Data Mining: Examples Using The Cite Architecture, D Neel Smith, Gabriel A. Weaver

Computer Science Technical Reports

Domain knowledge expressed in structured citation formats can be exploited in data mining. We propose four structural properties of canonically cited texts, then look at to two classic problems in the study of the scholia, or ancient scholarly commentary, found in the manuscripts of the Iliad. We cluster citations of scholia to analyze their distribution in different manuscripts; this leads to a revised view of how the manuscripts' scribes drew on their source material. Correlated frequencies of named entities suggest that one group of manuscripts had access to material more closely based on the work of the greatest Hellenistic editor …

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Deamon: Energy-Efficient Sensor Monitoring, Minho Shin, Patrick Tsang, David Kotz, Cory Cornelius Jun 2009

Deamon: Energy-Efficient Sensor Monitoring, Minho Shin, Patrick Tsang, David Kotz, Cory Cornelius

Dartmouth Scholarship

In people-centric opportunistic sensing, people offer their mobile nodes (such as smart phones) as platforms for collecting sensor data. A sensing application distributes sensing `tasks,' which specify what sensor data to collect and under what conditions to report the data back to the application. To perform a task, mobile nodes may use on-board sensors, a body-area network of personal sensors, or sensors from neighboring nodes that volunteer to contribute their sensing resources. In all three cases, continuous sensor monitoring can drain a node's battery. \par We propose DEAMON (Distributed Energy-Aware MONitoring), an energy-efficient distributed algorithm for long-term sensor monitoring. Our …

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Perturbative Analysis Of The Method Of Particular Solutions For Improved Inclusion Of High-Lying Dirichlet Eigenvalues, A. H. Barnett May 2009

Perturbative Analysis Of The Method Of Particular Solutions For Improved Inclusion Of High-Lying Dirichlet Eigenvalues, A. H. Barnett

Dartmouth Scholarship

The Dirichlet eigenvalue or “drum” problem in a domain $\Omega\subset\mathbb{R}^2$ becomes numerically challenging at high eigenvalue (frequency) E. In this regime the method of particular solutions (MPS) gives spectral accuracy for many domain shapes. It requires a number of degrees of freedom scaling as $\sqrt{E}$, the number of wavelengths on the boundary, in contrast to direct discretization for which this scaling is E. Our main result is an inclusion bound on eigenvalues that is a factor $O(\sqrt{E})$ tighter than the classical bound of Moler–Payne and that is optimal in that it reflects the true slopes of curves appearing …

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Proper Motions And Brightness Variations Of Nonthermal X-Ray Filaments In The Cassiopeia A Supernova Remnant, Daniel J. Patnaude, Robert A. Fesen May 2009

Proper Motions And Brightness Variations Of Nonthermal X-Ray Filaments In The Cassiopeia A Supernova Remnant, Daniel J. Patnaude, Robert A. Fesen

Dartmouth Scholarship

We present Chandra ACIS X-ray observations of the Galactic supernova remnant Cassiopeia A taken in 2007 December. Combining these data with previous archival Chandra observations taken in 2000, 2002, and 2004, we estimate the remnant's forward shock velocity at various points around the outermost shell to range between 4200 and 5200 ± 500 km s–1. Using these results together with previous analyses of Cas A's X-ray emission, we present a model for the evolution of Cas A and find that it's expansion is well fit by a ρej ∝ r –(7–9) ejecta profile running into a circumstellar …

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Sdss Unveils A Population Of Intrinsically Faint Cataclysmic Variables At The Minimum Orbital Period, B. T. Gänsicke, M. Dillon, J. Southworth, J. R. Thorstensen May 2009

Sdss Unveils A Population Of Intrinsically Faint Cataclysmic Variables At The Minimum Orbital Period, B. T. Gänsicke, M. Dillon, J. Southworth, J. R. Thorstensen

Dartmouth Scholarship

We discuss the properties of 137 cataclysmic variables (CVs) which are included in the Sloan Digital Sky Survey (SDSS) spectroscopic data base, and for which accurate orbital periods have been measured. 92 of these systems are new discoveries from SDSS and were followed-up in more detail over the past few years. 45 systems were previously identified as CVs because of the detection of optical outbursts and/or X-ray emission, and subsequently re-identified from the SDSS spectroscopy. The period distribution of the SDSS CVs differs dramatically from that of all the previously known CVs, in particular it contains a significant accumulation of …

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Anthropogenic Osmium In Rain And Snow Reveals Global-Scale Atmospheric Contamination, Cynthia Chen, Peter N. Sedwick, Mukul Sharma May 2009

Anthropogenic Osmium In Rain And Snow Reveals Global-Scale Atmospheric Contamination, Cynthia Chen, Peter N. Sedwick, Mukul Sharma

Dartmouth Scholarship

Osmium is one of the rarer elements in seawater, with typical concentration of approximately 10 x 10(-15) g g(-1) (5.3 x 10(-14) mol kg(-1)). The osmium isotope composition ((187)Os/(188)Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (approximately 1.3) and mantle/cosmic dust (approximately 0.13). Here, we show that the (187)Os/(188)Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (approximately 0.2) that are processed to extract platinum and other metals to be used primarily …

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Autoscopy: Detecting Pattern-Searching Rootkits Via Control Flow Tracing, Ashwin Ramaswamy May 2009

Autoscopy: Detecting Pattern-Searching Rootkits Via Control Flow Tracing, Ashwin Ramaswamy

Dartmouth College Master’s Theses

Traditional approaches to rootkit detection assume the execution of code at a privilege level below that of the operating system kernel, with the use of virtual machine technologies to enable the detection system itself to be immune from the virus or rootkit code. In this thesis, we approach the problem of rootkit detection from the standpoint of tracing and instrumentation techniques, which work from within the kernel and also modify the kernel's run-time state to detect aberrant control flows. We wish to investigate the role of emerging tracing frameworks (Kprobes, DTrace etc.) in enforcing operating system security without the reliance …

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Dynamic Universal Accumulators For Ddh Groups And Their Application To Attribute-Based Anonymous Credential Systems, Man Ho Au, Patrick P. Tsang, Willy Susilo, Yi Mu Apr 2009

Dynamic Universal Accumulators For Ddh Groups And Their Application To Attribute-Based Anonymous Credential Systems, Man Ho Au, Patrick P. Tsang, Willy Susilo, Yi Mu

Computer Science Technical Reports

We present the first dynamic universal accumulator that allows (1) the accumulation of elements in a DDH-hard group G and (2) one who knows x such that y=g^x has --- or has not --- been accumulated, where g generates G, to efficiently prove her knowledge of such x in zero knowledge, and hence without revealing, e.g., x or y. We introduce the Attribute-Based Anonymous Credential System (ABACS), which allows the verifier to authenticate anonymous users according to any access control policy expressible as a formula of possibly negated boolean user attributes. We construct the system from our accumulator.

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Distance To The Sagittarius Dwarf Galaxy Using Macho Project Rr Lyrae Stars, Andrea Kunder, Brian Chaboyer Apr 2009

Distance To The Sagittarius Dwarf Galaxy Using Macho Project Rr Lyrae Stars, Andrea Kunder, Brian Chaboyer

Dartmouth Scholarship

We derive the distance to the northern extension of the Sagittarius (Sgr) dwarf spheroidal galaxy from 203 Sgr RR0 Lyrae stars found in the MACHO database. Their distances are determined differentially with respect to 288 Galactic bulge RR0 Lyrae stars also found in the MACHO data. We find a distance modulus difference of 2.41 mag at l = 5◦ and b =− 8◦ and that the extension of the Sgr galaxy toward the galactic plane is inclined toward us. Assuming R GC = 8 kpc, this implies the distance to these stars is (m − M) 0 = …

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High Time Resolution Pfisr And Optical Observations Of Naturally Enhanced Ion Acoustic Lines, R G. Michell, K A. Lynch, C J. Heinselman, H C. Stenbaek-Nielsen Apr 2009

High Time Resolution Pfisr And Optical Observations Of Naturally Enhanced Ion Acoustic Lines, R G. Michell, K A. Lynch, C J. Heinselman, H C. Stenbaek-Nielsen

Dartmouth Scholarship

Observations of naturally enhanced ion acoustic lines (NEIALs) taken with the Poker Flat Incoherent Scatter Radar (PFISR) using a mode with very high time resolution are presented. The auroral event took place over Poker Flat, Alaska on 8 February 2007 at 09:35 UT (∼22:00 MLT), and the radar data are complemented by common-volume high- resolution auroral imaging. The NEIALs occurred during only one of the standard 15-s integration periods. The raw data of this time show very intermittent NEIALs which oc- cur only during a few very short time intervals (≤1 s) within the 15-s period. The time sampling of …

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The Acs Survey Of Galactic Globular Clusters. Vii. Relative Ages, Antonio Marín-Franch, Antonio Aparicio, Giampaolo Piotto, Alfred Rosenberg, Brian Chaboyer Apr 2009

The Acs Survey Of Galactic Globular Clusters. Vii. Relative Ages, Antonio Marín-Franch, Antonio Aparicio, Giampaolo Piotto, Alfred Rosenberg, Brian Chaboyer

Dartmouth Scholarship

The ACS Survey of Galactic globular clusters is a Hubble Space Telescope Treasury program designed to provide a new large, deep, and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main-sequence (MS) turnoffs, using MS fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2%-7%. We demonstrate that the calculated relative ages are independent of the choice of theoretical model. We find that the Galactic globular cluster sample can …

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Stellar Population Models And Individual Element Abundances. Ii. Stellar Spectra And Integrated Light Models, Hyun-Chul Lee, Guy Worthey, Aaron Dotter, Brian Chaboyer Apr 2009

Stellar Population Models And Individual Element Abundances. Ii. Stellar Spectra And Integrated Light Models, Hyun-Chul Lee, Guy Worthey, Aaron Dotter, Brian Chaboyer

Dartmouth Scholarship

The first paper in this series explored the effects of altering the chemical mixture of the stellar population on an element-by-element basis on stellar evolutionary tracks and isochrones to the end of the red giant branch. This paper extends the discussion by incorporating the fully consistent synthetic stellar spectra with those isochrone models in predicting integrated colors, Lick indices, and synthetic spectra. Older populations display element ratio effects in their spectra at higher amplitude than younger populations. In addition, spectral effects in the photospheres of stars tend to dominate over effects from isochrone temperatures and lifetimes, but, further, the isochrone-based …

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Intermodulation And Parametric Amplification In A Superconducting Stripline Resonator Integrated With A Dc-Squid, B. Abdo, O. Suchoi, E. Segev, O. Shtempluck, M. Blencowe, E. Buks Mar 2009

Intermodulation And Parametric Amplification In A Superconducting Stripline Resonator Integrated With A Dc-Squid, B. Abdo, O. Suchoi, E. Segev, O. Shtempluck, M. Blencowe, E. Buks

Dartmouth Scholarship

We utilize a superconducting stripline resonator containing a dc-SQUID as a strong intermodulation amplifier exhibiting a signal gain of 24dB and a phase modulation of 30dB. Studying the system response in the time domain near the intermodulation amplification threshold reveals a unique noise-induced spikes behavior. We account for this response qualitatively via solving numerically the equations of motion for the integrated system. Furthermore, employing this device as a parametric amplifier yields an abrupt rise of 38dB in the generated side-band signal.

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Authenticated Streamwise On-Line Encryption, Patrick P. Tsang, Rouslan V. Solomakhin, Sean W. Smith Mar 2009

Authenticated Streamwise On-Line Encryption, Patrick P. Tsang, Rouslan V. Solomakhin, Sean W. Smith

Computer Science Technical Reports

In Blockwise On-line Encryption, encryption and decryption return an output block as soon as the next input block is received. In this paper, we introduce Authenticated Streamwise On-line Encryption (ASOE), which operates on plaintexts and ciphertexts as streams of arbitrary length (as opposed to fixed-sized blocks), and thus significantly reduces message expansion and end-to-end latency. Also, ASOE provides data authenticity as an option. ASOE can therefore be used to efficiently secure resource-constrained communications with real-time requirements such as those in the electric power grid and wireless sensor networks. We investigate and formalize ASOE's strongest achievable notion of security, and present …

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New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich Mar 2009

New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich

Dartmouth Scholarship

We present astrometric parallaxes for 18 suspected nearby stars selected from the LSPM-north proper motion catalog. 16 objects are confirmed to be main-sequence M dwarfs within 16 pc of the Sun, including three stars (LSPM J0011+5908, LSPM J0330+5413, and LSPM J0510+2714) which lie just within the 10 pc horizon. Two other targets (LSPM J1817+1328, LSPM J2325+1403) are confirmed to be nearby white dwarfs at distances of 14 and 22 pc, respectively. One of our targets, the common proper motion pair LSPM J0405+7116E + LSPM J0405+7116W, is revealed to be a triple system, with the western component resolved into a pair …

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Smoking Enhances Risk For New External Genital Warts In Men, Dorothy J. Wiley, David Elashoff, Emmanuel V. Masongsong, Diane M. Harper Mar 2009

Smoking Enhances Risk For New External Genital Warts In Men, Dorothy J. Wiley, David Elashoff, Emmanuel V. Masongsong, Diane M. Harper

Dartmouth Scholarship

Repeat episodes of HPV-related external genital warts reflect recurring or new infections. No study before has been sufficiently powered to delineate how tobacco use, prior history of EGWs and HIV infection affect the risk for new EGWs. Behavioral, laboratory and examination data for 2,835 Multicenter AIDS Cohort Study participants examined at 21,519 semi-annual visits were evaluated. Fourteen percent (391/2835) of men reported or were diagnosed with EGWs at 3% (675/21,519) of study visits. Multivariate analyses showed smoking, prior episodes of EGWs, HIV infection and CD4+ T-lymphocyte count among the infected, each differentially influenced the risk for new EGWs.

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Approximability Of The Unsplittable Flow Problem On Trees, Chrisil Arackaparambil, Amit Chakrabarti, Chien-Chung Huang Mar 2009

Approximability Of The Unsplittable Flow Problem On Trees, Chrisil Arackaparambil, Amit Chakrabarti, Chien-Chung Huang

Computer Science Technical Reports

We consider the approximability of the Unsplittable Flow Problem (UFP) on tree graphs, and give a deterministic quasi-polynomial time approximation scheme for the problem when the number of leaves in the tree graph is at most poly-logarithmic in $n$ (the number of demands), and when all edge capacities and resource requirements are suitably bounded. Our algorithm generalizes a recent technique that obtained the first such approximation scheme for line graphs. Our results show that the problem is not APX-hard for such graphs unless NP \subseteq DTIME(2^{polylog(n)}). Further, a reduction from the Demand Matching Problem shows that UFP is APX-hard when …

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Auroral Evidence For Multiple Reconnection In The Magnetospheric Tail Plasma Sheet, R. A. Treumann, C. H. Jaroschek, R. Pottelette Feb 2009

Auroral Evidence For Multiple Reconnection In The Magnetospheric Tail Plasma Sheet, R. A. Treumann, C. H. Jaroschek, R. Pottelette

Dartmouth Scholarship

We present auroral evidence for multiple and, most probably, small-scale reconnection in the near-Earth magnetospheric plasma sheet current layer during auroral activity. Hall currents as the source of upward and downward field-aligned currents require the generation of the corresponding electron fluxes. The auroral spatial ordering in a multiple sequence of these fluxes requires the assumption of the existence of several —and possibly— even many tailward reconnection sites.

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Field Line Distribution Of Density At L=4.8 Inferred From Observations By Cluster, R E. Denton, P Décréau, M J. Engebretson, F Darrouzet Feb 2009

Field Line Distribution Of Density At L=4.8 Inferred From Observations By Cluster, R E. Denton, P Décréau, M J. Engebretson, F Darrouzet

Dartmouth Scholarship

For two events observed by the CLUSTER space- craft, the field line distribution of mass density ρ was inferred from Alfve ́n wave harmonic frequencies and compared to the electron density ne from plasma wave data and the oxy- gen density nO+ from the ion composition experiment. In one case, the average ion mass M≡ρ/ne was about 5amu (28 October 2002), while in the other it was about 3 amu (10 September 2002). Both events occurred when the CLUSTER 1 (C1) spacecraft was in the plasmatrough. Nevertheless, the electron density ne was significantly lower for the first event (ne =8 …

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The Evolution Of Late-Time Optical Emission From Sn 1979c, Dan Milisavljevic, Robert A. Fesen, Robert P. Kirshner, Peter Challis Feb 2009

The Evolution Of Late-Time Optical Emission From Sn 1979c, Dan Milisavljevic, Robert A. Fesen, Robert P. Kirshner, Peter Challis

Dartmouth Scholarship

Optical spectra of the bright Type II-L supernova SN 1979C obtained in April 2008 with the 6.5 m Multiple Mirror Telescope are compared with archival late-time spectra to follow the evolution of its optical emission over the age range of 11-29 years. We estimate an Hα flux decrease of around 35% from 1993 to 2008 but noticeable increases in the strength of blueshifted emission of forbidden oxygen lines. While the maximum expansion of the broad ~6700 km s–1 Hα emission appears largely unchanged from 1993, we find a significant narrowing of the double-peaked emission profiles in the [O I] …

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