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Dartmouth College

2005

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Articles 31 - 60 of 73

Full-Text Articles in Physical Sciences and Mathematics

Mining Frequent And Periodic Association Patterns, Guanling Chen, Heng Huang, Minkyong Kim Jul 2005

Mining Frequent And Periodic Association Patterns, Guanling Chen, Heng Huang, Minkyong Kim

Computer Science Technical Reports

Profiling the clients' movement behaviors is useful for mobility modeling, anomaly detection, and location prediction. In this paper, we study clients' frequent and periodic movement patterns in a campus wireless network. We use offline data-mining algorithms to discover patterns from clients' association history, and analyze the reported patterns using statistical methods. Many of our results reflect the common characteristics of a typical academic campus, though we also observed some unusual association patterns. There are two challenges: one is to remove noise from data for efficient pattern discovery, and the other is to interpret discovered patterns. We address the first challenge …

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More Efficient Secure Function Evaluation Using Tiny Trusted Third Parties, Alexander Iliev, Sean Smith Jul 2005

More Efficient Secure Function Evaluation Using Tiny Trusted Third Parties, Alexander Iliev, Sean Smith

Computer Science Technical Reports

Secure Function Evaluation (SFE) problems. We assume that a really trustworthy TTP device will have very limited protected memory and computation environment---a \emph{tiny TTP}. This precludes trivial solutions like "just run the function in the TTP". Traditional scrambled circuit evaluation approaches to SFE have a very high overhead in using indirectly-addressed arrays---every array access's cost is linear in the array size. The main gain in our approach is that array access can be provided with much smaller overhead---$O(\sqrt{N}\log N)$. This expands the horizon of problems which can be efficiently solved using SFE. Additionally, our technique provides a simple way to …

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Cosmic Shear Of The Microwave Background: The Curl Diagnostic, Asantha Cooray, Marc Kamionkowski, Robert R. Caldwell Jun 2005

Cosmic Shear Of The Microwave Background: The Curl Diagnostic, Asantha Cooray, Marc Kamionkowski, Robert R. Caldwell

Dartmouth Scholarship

Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is to deflect the primary temperature and polarization signal to slightly different locations on the sky. Deflections due to density fluctuations, gradient-type for the gradient of the projected gravitational potential, give a direct measure of the mass distribution. Curl-type deflections can be induced by, for example, a primordial background of gravitational waves from inflation or by second-order effects related to lensing by density perturbations. Whereas gradient-type deflections are expected to dominate, we show that curl-type deflections can …

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Dynamo Regimes With A Nonhelical Forcing, Pablo D. Mininni, Yannick Ponty, David C. Montgomery, Jean-Francois Pinton Jun 2005

Dynamo Regimes With A Nonhelical Forcing, Pablo D. Mininni, Yannick Ponty, David C. Montgomery, Jean-Francois Pinton

Dartmouth Scholarship

A three-dimensional numerical computation of magnetohydrodynamic dynamo behavior is described. The dynamo is mechanically forced with a driving term of the Taylor-Green type. The magnetic field development is followed from negligibly small levels to saturated values that occur at magnetic energies comparable to the kinetic energies. Although there is locally a nonzero helicity density, there is no overall integrated helicity in the system. Persistent oscillations are observed in the saturated state for not-too-large mechanical Reynolds numbers, oscillations in which the kinetic and magnetic energies vary out of phase but with no reversal of the magnetic field. The flow pattern exhibits …

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Late‐Time X‐Ray, Uv, And Optical Monitoring Of Supernova 1979c, Stefan Immler, Robert A. Fesen, Schuyler D. Van Dyk, Kurt W. Weiler, Robert Petre, Walter H.G Lewin, David Pooley, Wolfgang Pietsch, Bernd Aschenbach, Molly C. Hammell, Gwen C. Rudie Jun 2005

Late‐Time X‐Ray, Uv, And Optical Monitoring Of Supernova 1979c, Stefan Immler, Robert A. Fesen, Schuyler D. Van Dyk, Kurt W. Weiler, Robert Petre, Walter H.G Lewin, David Pooley, Wolfgang Pietsch, Bernd Aschenbach, Molly C. Hammell, Gwen C. Rudie

Dartmouth Scholarship

We present results from observations of supernova (SN) 1979C with the Newton X-Ray Multi-Mirror (XMM-Newton) mission in X-rays and in UV, archival X-ray, and Hubble Space Telescope (HST) data, and follow-up ground-based optical imaging. The XMM-Newton MOS spectrum shows the best-fit two-temperature thermal plasma emission characteristics of both the forward (kThigh = 4.1 keV) and reverse shock (kTlow = 0.79 keV) with no intrinsic absorption. The long-term X-ray light curve, constructed from all X-ray data available, reveals that SN 1979C is still radiating at a flux level similar to that detected by …

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Managing Access Control In Virtual Private Networks, Twum Djin Jun 2005

Managing Access Control In Virtual Private Networks, Twum Djin

Dartmouth College Undergraduate Theses

Virtual Private Network technology allows remote network users to benefit from resources on a private network as if their host machines actually resided on the network. However, each resource on a network may also have its own access control policies, which may be completely unrelated to network access. Thus users� access to a network (even by VPN technology) does not guarantee their access to the sought resources. With the introduction of more complicated access privileges, such as delegated access, it is conceivable for a scenario to arise where a user can access a network remotely (because of direct permissions from …

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Monomial Nonnegativity And The Bruhat Order, Brian Drake, Sean Gerrish, Mark Skandera Jun 2005

Monomial Nonnegativity And The Bruhat Order, Brian Drake, Sean Gerrish, Mark Skandera

Dartmouth Scholarship

We show that five nonnegativity properties of polynomials coincide when restricted to polynomials of the form x1, pi(1) ... xn,pi(n) - x1, sigma(1) ... xn, sigma(n), where $\pi and sigma are permutations in Sn. In particular, we show that each of these properties may be used to characterize the Bruhat order on Sn.

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Survey Of Energetic O + Ions Near The Dayside Mid-Latitude Magnetopause With Cluster, M. Bouhram, B. Klecker, G. Paschmann, S. Haaland, H. Hasegawa, A. Blagau, H. Reme, J.A. Sauvaud, L. M. Kistler, A. Balogh Jun 2005

Survey Of Energetic O + Ions Near The Dayside Mid-Latitude Magnetopause With Cluster, M. Bouhram, B. Klecker, G. Paschmann, S. Haaland, H. Hasegawa, A. Blagau, H. Reme, J.A. Sauvaud, L. M. Kistler, A. Balogh

Dartmouth Scholarship

Since December 2000, the Cluster satellites have been conducting detailed measurements of the magnetospheric boundaries and have confirmed the unambiguous presence of ions of terrestrial origin (e.g. O+ in regions adjacent to the dayside, mid-latitude magnetopause. In the present paper, we focus on the statistical properties of the O+ ion component at energies ranging from 30eV up to 40keV, using three years of ion data at solar maximum from the Cluster Ion Spectrometry (CIS) experiment aboard two Cluster spacecraft. The O+ density decreases on average by a factor of 6, from 0.041 to 7x10-3cm-3 …

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Lower Bounds On The Communication Complexity Of Shifting, Marco D. Adelfio Jun 2005

Lower Bounds On The Communication Complexity Of Shifting, Marco D. Adelfio

Dartmouth College Undergraduate Theses

We study the communication complexity of the SHIFT (equivalently, SUM-INDEX) function in a 3-party simultaneous message model. Alice and Bob share an n-bit string x and Alice holds an index i and Bob an index j. They must send messages to a referee who knows only n, i and j, enabling him to determine x[(i+j) mod n]. Surprisingly, it is possible to achieve nontrivial savings even with such a strong restriction: Bob can now make do with only ceil(n/2) bits. Here we show that this bound is completely tight, for all n. This is an exact lower bound, with no …

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On-Line Metasearch, Pooling, And System Evaluation, Robert A. Savell Jun 2005

On-Line Metasearch, Pooling, And System Evaluation, Robert A. Savell

Dartmouth College Ph.D Dissertations

This thesis presents a unified method for simultaneous solution of three problems in Information Retrieval--- metasearch (the fusion of ranked lists returned by retrieval systems to elicit improved performance), efficient system evaluation (the accurate evaluation of retrieval systems with small numbers of relevance judgements), and pooling or ``active sample selection" (the selection of documents for manual judgement in order to develop sample pools of high precision or pools suitable for assessing system quality). The thesis establishes a unified theoretical framework for addressing these three problems and naturally generalizes their solution to the on-line context by incorporating feedback in the form …

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Modeling Users' Mobility Among Wifi Access Points, Minkyong Kim, David Kotz Jun 2005

Modeling Users' Mobility Among Wifi Access Points, Minkyong Kim, David Kotz

Dartmouth Scholarship

Modeling movements of users is important for simulating wireless networks, but current models often do not reflect real movements. Using real mobility traces, we can build a mobility model that reflects reality. In building a mobility model, it is important to note that while the number of handheld wireless devices is constantly increasing, laptops are still the majority in most cases. As a laptop is often disconnected from the network while a user is moving, it is not feasible to extract the exact path of the user from network messages. Thus, instead of modeling individual user's movements, we model movements …

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Analysis Of A Wi-Fi Hotspot Network, David P. Blinn, Tristan Henderson, David Kotz Jun 2005

Analysis Of A Wi-Fi Hotspot Network, David P. Blinn, Tristan Henderson, David Kotz

Dartmouth Scholarship

Wireless hotspot networks have become increasingly popular in recent years as a means of providing Internet access in public areas such as restaurants and airports. In this paper we present the first study of such a hotspot network. We examine five weeks of SNMP traces from the Verizon Wi-Fi HotSpot network in Manhattan. We find that far more cards associated to the network than logged into it. Most clients used the network infrequently and visited few APs. AP utilization was uneven and the network displayed some unusual patterns in traffic load. Some characteristics were similar to those previously observed in …

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A Toy Rock Climbing Robot, Matthew P. Bell May 2005

A Toy Rock Climbing Robot, Matthew P. Bell

Dartmouth College Undergraduate Theses

The goal of this thesis was to build a simple toy rock climbing robot, and to explore problems related to grasping, path planning, and robot control. The robot is capable of climbing a wall of pegs either under manual control through a host system and an infrared interface, or on the basis of a set of pre-recorded keyframes. In addition, the robot can climb certain peg configurations using a cyclic gait. The robot climbs in an open-loop mode without sensor feedback. All communications are sent through the IR connection, and the tether to the robot consists only of two power …

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Lattice Thermal Conductance In Nanowires At Low Temperatures: Breakdown And Recovery Of Quantization, Y. Tanaka, F. Yoshida, S. Tamura May 2005

Lattice Thermal Conductance In Nanowires At Low Temperatures: Breakdown And Recovery Of Quantization, Y. Tanaka, F. Yoshida, S. Tamura

Dartmouth Scholarship

The quantization of lattice thermal conductance g normalized by g0=π2k2BT/3h (the universal quantum of thermal conductance) was recently predicted theoretically to take an integer value over a finite range of temperature and then observed experimentally in nanowires with catenoidal contacts. The prediction of this quantization by Rego and Kirczenow [Phys. Rev. Lett. 81, 232 (1998)] relies on a study of only dilatational (longitudinal) vibrational mode in the wires. We study the thermal conductance in catenoidal wires by explicitly calculating the transmission rates of the six distinct vibrational modes (four acoustic and two low-lying optical modes) and applying the Landauer …

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Integrated Recombinant Protein Expression And Purification Platform Based On Ralstonia Eutropha, Gavin C. Barnard, Jesse D. Mccool, David W. Wood, Tillman U. Gerngross May 2005

Integrated Recombinant Protein Expression And Purification Platform Based On Ralstonia Eutropha, Gavin C. Barnard, Jesse D. Mccool, David W. Wood, Tillman U. Gerngross

Dartmouth Scholarship

Protein purification of recombinant proteins constitutes a significant cost of biomanufacturing and various efforts have been directed at developing more efficient purification methods. We describe a protein purification scheme wherein Ralstonia eutropha is used to produce its own “affinity matrix,” thereby eliminating the need for external chromatographic purification steps. This approach is based on the specific interaction of phasin proteins with granules of the intracellular polymer poly

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Preventing Theft Of Quality Of Service On Open Platforms, Kwang-Hyun Baek, Sean W. Smith May 2005

Preventing Theft Of Quality Of Service On Open Platforms, Kwang-Hyun Baek, Sean W. Smith

Computer Science Technical Reports

As multiple types of traffic converge onto one network (frequently wireless), enterprises face a tradeoff between effectiveness and security. Some types of traffic, such as voice-over-IP (VoIP), require certain quality of service (QoS) guarantees to be effective. The end client platform is in the best position to know which packets deserve this special handling. In many environments (such as universities), end users relish having control over their own machines. However, if end users administer their own machines, nothing stops dishonest ones from marking undeserving traffic for high QoS. How can an enterprise ensure that only appropriate traffic receives high QoS, …

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Aggregated Path Authentication For Efficient Bgp Security, Meiyuan Zhao, Sean W. Smith, David M. Nicol May 2005

Aggregated Path Authentication For Efficient Bgp Security, Meiyuan Zhao, Sean W. Smith, David M. Nicol

Computer Science Technical Reports

The border gateway protocol (BGP) controls inter-domain routing in the Internet. BGP is vulnerable to many attacks, since routers rely on hearsay information from neighbors. Secure BGP (S-BGP) uses DSA to provide route authentication and mitigate many of these risks. However, many performance and deployment issues prevent S-BGP's real-world deployment. Previous work has explored improving S-BGP processing latencies, but space problems, such as increased message size and memory cost, remain the major obstacles. In this paper, we combine two efficient cryptographic techniques---signature amortization and aggregate signatures---to design new aggregated path authentication schemes. We propose six constructions for aggregated path authentication …

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An O(N^{5/2} Log N) Algorithm For The Rectilinear Minimum Link-Distance Problem In Three Dimensions (Extended Abstract), Robert Scot Drysdale, Clifford Stein, David P. Wagner May 2005

An O(N^{5/2} Log N) Algorithm For The Rectilinear Minimum Link-Distance Problem In Three Dimensions (Extended Abstract), Robert Scot Drysdale, Clifford Stein, David P. Wagner

Computer Science Technical Reports

In this paper we consider the Rectilinear Minimum Link-Distance Problem in Three Dimensions. The problem is well studied in two dimensions, but is relatively unexplored in higher dimensions. We solve the problem in O(B n log n) time, where n is the number of corners among all obstacles, and B is the size of a BSP decomposition of the space containing the obstacles. It has been shown that in the worst case B = Theta(n^{3/2}), giving us an overall worst case time of O(n^{5/2} log n). Previously known algorithms have had worst-case running times of Omega(n^3).

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Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz May 2005

Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz

Computer Science Technical Reports

There is increasing interest in location-aware systems and applications. It is important for any designer of such systems and applications to understand the nature of user and device mobility. Furthermore, an understanding of the effect of user mobility on access points (APs) is also important for designing, deploying, and managing wireless networks. Although various studies of wireless networks have provided insights into different network environments and user groups, it is often hard to apply these findings to other situations, or to derive useful abstract models. In this paper, we present a general methodology for extracting mobility information from wireless network …

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Probing Multiple Sight Lines Through The Sn 1006 Remnant By Ultraviolet Absorption Spectroscopy, P. Frank Winkler, Knox S. Long, Andrew S. Hamilton, Robert A. Fesen May 2005

Probing Multiple Sight Lines Through The Sn 1006 Remnant By Ultraviolet Absorption Spectroscopy, P. Frank Winkler, Knox S. Long, Andrew S. Hamilton, Robert A. Fesen

Dartmouth Scholarship

Absorption-line spectroscopy is an effective probe for cold ejecta within a supernova remnant (SNR), provided that suitable background UV sources can be identified. For the SN 1006 remnant we have identified four such sources, in addition to the much-studied Schweitzer-Middleditch (SM) star. We have used STIS on the Hubble Space Telescope to obtain UV spectra of all four sources, to study "core samples" of the SN 1006 interior. The line of sight closest to the center of the SNR shell, passing only 20 away, is to a V = 19.5 QSO at z = 1.026. Its spectrum shows broad Fe …

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Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz May 2005

Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz

Dartmouth Scholarship

There is increasing interest in location-aware systems and applications. It is important for any designer of such systems and applications to understand the nature of user and device mobility. Furthermore, an understanding of the effect of user mobility on access points (APs) is also important for designing, deploying, and managing wireless networks. Although various studies of wireless networks have provided insights into different network environments and user groups, it is often hard to apply these findings to other situations, or to derive useful abstract models. \par In this paper, we present a general methodology for extracting mobility information from wireless …

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Numerical Study Of Dynamo Action At Low Magnetic Prandtl Numbers, Y. Ponty, P. D. Mininni, D. C. Montgomery, J. Pinton, H. Politano, A. Pouquet Apr 2005

Numerical Study Of Dynamo Action At Low Magnetic Prandtl Numbers, Y. Ponty, P. D. Mininni, D. C. Montgomery, J. Pinton, H. Politano, A. Pouquet

Dartmouth Scholarship

We present a three-pronged numerical approach to the dynamo problem at low magnetic Prandtl numbers PM. The difficulty of resolving a large range of scales is circumvented by combining direct numerical simulations, a Lagrangian-averaged model and large-eddy simulations. The flow is generated by the Taylor-Green forcing; it combines a well defined structure at large scales and turbulent fluctuations at small scales. Our main findings are (i) dynamos are observed from PM=1 down to PM=10−2, (ii) the critical magnetic Reynolds number increases sharply with P−1M as turbulence sets in and then it saturates, and (iii) in the linear growth phase, unstable …

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The Oxford-Dartmouth Thirty Degree Survey - Ii. Clustering Of Bright Lyman Break Galaxies: Strong Luminosity-Dependent Bias At Z = 4, Paul D. Allen, Leonidas A. Moustakas, Gavin Dalton, Emily Macdonald, Chris Blake, Lee Clewley, Catherine Heymans, Gary Wegner Apr 2005

The Oxford-Dartmouth Thirty Degree Survey - Ii. Clustering Of Bright Lyman Break Galaxies: Strong Luminosity-Dependent Bias At Z = 4, Paul D. Allen, Leonidas A. Moustakas, Gavin Dalton, Emily Macdonald, Chris Blake, Lee Clewley, Catherine Heymans, Gary Wegner

Dartmouth Scholarship

We present measurements of the clustering properties of bright (L > L*) z~4 Lyman break galaxies (LBGs) selected from the Oxford-Dartmouth Thirty Degree Survey (ODT). We describe techniques used to select and evaluate our candidates and calculate the angular correlation function, which we find best fitted by a power law, ω(θ) =Awθ−β with Aw= 15.4 (with θ in arcsec), using a constrained slope of β= 0.8. Using a redshift distribution consistent with photometric models, we deproject this correlation function and find a comoving Mpc in a Ωm= 0.3 flat λ cosmology for iAB≤ 24.5. This corresponds to a linear bias value …

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Numerical Solutions Of The Three-Dimensional Magnetohydrodynamic Α Model, Pablo D. Mininni, David C. Montgomery, Annick Pouquet Apr 2005

Numerical Solutions Of The Three-Dimensional Magnetohydrodynamic Α Model, Pablo D. Mininni, David C. Montgomery, Annick Pouquet

Dartmouth Scholarship

We present direct numerical simulations and α-model simulations of four familiar three-dimensional magnetohydrodynamic (MHD) turbulence effects: selective decay, dynamic alignment, inverse cascade of magnetic helicity, and the helical dynamo effect. The MHD α model is shown to capture the long-wavelength spectra in all these problems, allowing for a significant reduction of computer time and memory at the same kinetic and magnetic Reynolds numbers. In the helical dynamo, not only does the α model correctly reproduce the growth rate of magnetic energy during the kinematic regime, it also captures the nonlinear saturation level and the late generation of a large scale …

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Resonant Nucleation, Marcelo Gleiser, Rafael C. Howell Apr 2005

Resonant Nucleation, Marcelo Gleiser, Rafael C. Howell

Dartmouth Scholarship

We investigate the role played by fast quenching on the decay of metastable (or false vacuum) states. Instead of the exponentially slow decay rate per unit volume, ΓHN∼exp[−Eb/kBT] (Eb is the free energy of the critical bubble), predicted by homogeneous nucleation theory, we show that under fast enough quenching the decay rate is a power law ΓRN∼[Eb/kBT]−B, where B is weakly sensitive to the temperature. For a range of parameters, large-amplitude oscillations about the metastable state trigger the resonant emergence of coherent subcritical configurations. Decay mechanisms for different Eb are proposed and illustrated in a (2+1)-dimensional scalar field model.

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Measuring Wireless Network Usage With The Experience Sampling Method, Tristan Henderson, Denise Anthony, David Kotz Apr 2005

Measuring Wireless Network Usage With The Experience Sampling Method, Tristan Henderson, Denise Anthony, David Kotz

Dartmouth Scholarship

Measuring wireless local area networks has proven useful for characterizing, modeling and provisioning these networks. These measurements are typically taken passively from a vantage point on the network itself. Client devices, or users, are never actively queried. These measurements can indicate \em what is happening on the network, but it can be difficult to infer \em why a particular behavior is occurring. In this paper we use the Experience Sampling Method (ESM) to study wireless network users. We monitored 29 users remotely for one week, and signaled them to fill out a questionnaire whenever interesting wireless behavior was observed. We …

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Optimal Reconstruction Of Magnetopause Structures From Cluster Data, H Hasegawa, B U. Ö Sonnerup, B Klecker, G Paschmann Mar 2005

Optimal Reconstruction Of Magnetopause Structures From Cluster Data, H Hasegawa, B U. Ö Sonnerup, B Klecker, G Paschmann

Dartmouth Scholarship

The Grad-Shafranov (GS) reconstruction tech- nique, a single-spacecraft based data analysis method for recovering approximately two-dimensional (2-D) magneto- hydrostatic plasma/field structures in space, is improved to become a multi-spacecraft technique that produces a single field map by ingesting data from all four Cluster spacecraft into the calculation. The plasma pressure, required for the technique, is measured in high time resolution by only two of the spacecraft, C1 and C3, but, with the help of spacecraft po- tential measurements available from all four spacecraft, the pressure can be estimated at the other spacecraft as well via a relationship, established from C1 …

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Regularized Orbit Models Unveiling The Stellar Structure And Dark Matter Halo Of The Coma Elliptical Ngc 4807, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner Mar 2005

Regularized Orbit Models Unveiling The Stellar Structure And Dark Matter Halo Of The Coma Elliptical Ngc 4807, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner

Dartmouth Scholarship

This is the second in a series of papers dedicated to unveiling the mass structure and orbital content of a sample of flattened early-type galaxies in the Coma cluster. The ability of our orbit libraries to reconstruct internal stellar motions and the mass composition of a typical elliptical in the sample is investigated by means of Monte Carlo simulations of isotropic rotator models. The simulations allow a determination of the optimal amount of regularization needed in the orbit superpositions. It is shown that under realistic observational conditions and with the appropriate regularization, internal velocity moments can be reconstructed to an …

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Department Of Computer Science Activity 1998-2004, David Kotz Mar 2005

Department Of Computer Science Activity 1998-2004, David Kotz

Computer Science Technical Reports

This report summarizes much of the research and teaching activity of the Department of Computer Science at Dartmouth College between late 1998 and late 2004. The material for this report was collected as part of the final report for NSF Institutional Infrastructure award EIA-9802068, which funded equipment and technical staff during that six-year period. This equipment and staff supported essentially all of the department's research activity during that period.

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Secure Context-Sensitive Authorization, Kazuhiro Minami, David Kotz Mar 2005

Secure Context-Sensitive Authorization, Kazuhiro Minami, David Kotz

Dartmouth Scholarship

There is a recent trend toward rule-based authorization systems to achieve flexible security policies. Also, new sensing technologies in pervasive computing make it possible to define context-sensitive rules, such as “allow database access only to staff who are currently located in the main office.” However, these rules, or the facts that are needed to verify authority, often involve sensitive context information. This paper presents a secure context-sensitive authorization system that protects confidential information in facts or rules. Furthermore, our system allows multiple hosts in a distributed environment to perform the evaluation of an authorization query in a collaborative way; we …

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