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Articles 1 - 24 of 24
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A Tight Upper Bound On The Benefits Of Replication And Consistency Control Protocols, Donald B. Johnson, Larry Raab
A Tight Upper Bound On The Benefits Of Replication And Consistency Control Protocols, Donald B. Johnson, Larry Raab
Computer Science Technical Reports
We present an upper bound on the performance provided by a protocol guaranteeing mutually exclusive access to a replicated resource in a network subject to component failure and subsequent partitioning. The bound is presented in terms of the performance of a single resource in the same network. The bound is tight and is the first such bound known to us. Since mutual exclusion is one of the requirements for maintaining the consistency of a database object, this bound provides an upper limit on the availability provided by any database consistency control protocol, including those employing dynamic data relocation and replication. …
The Duke Internet Programming Contest, Owen Astrachan, Vivek Khera, David Kotz
The Duke Internet Programming Contest, Owen Astrachan, Vivek Khera, David Kotz
Dartmouth Scholarship
On the evening of October 23, 1990, electronic mail messages started to pour into the computers at the Duke University Computer Science Department. Teams of programmers from all over the world were registering to compete in the first global (as far as the authors are aware) programming contest to be held on the Internet. During the three hour competition, modeled after the annual ACM scholastic programming contest, 60 teams from 37 institutions in 5 countries attempted to solve a set of six programming problems using C or Pascal. Their solutions were sent by electronic mail to Duke, where their programs …
Monocytes And Polymorphonuclear Neutrophils Of Patients With Streptococcal Pharyngitis Express Increased Numbers Of Type I Igg Fc Receptors., Paul M. Guyre, A Scott Campbell, Wayne D. Kniffin, Michael W. Fanger
Monocytes And Polymorphonuclear Neutrophils Of Patients With Streptococcal Pharyngitis Express Increased Numbers Of Type I Igg Fc Receptors., Paul M. Guyre, A Scott Campbell, Wayne D. Kniffin, Michael W. Fanger
Dartmouth Scholarship
Studies using cultured cells have shown that gamma interferon (IFN-gamma) induces the expression of Fc gamma RI (the type I Fc receptor for IgG) on human polymorphonuclear neutrophils (PMN) and greatly increases the number of these receptors on human monocytes. Administration of rIFN-gamma in vivo also causes enhanced Fc gamma RI expression on these cell populations. Because streptococcal antigens are potent inducers of IFN-gamma in vitro, we postulated that IFN-gamma would be produced endogenously in vivo in patients with streptococcal infections. Such production of IFN-gamma in vivo, even at low levels, might be expected to induce the expression of Fc …
Nucleotide Sequence Of The Epsilon-Subunit Of The Mouse Muscle Nicotinic Acetylcholine Receptor, P D. Gardner
Nucleotide Sequence Of The Epsilon-Subunit Of The Mouse Muscle Nicotinic Acetylcholine Receptor, P D. Gardner
Dartmouth Scholarship
The two predominant types of nicotinic acetylcholine receptors expressed in mammalian muscle differ with respect to a variety of electrophysiological and biochemical properties. A developmental, innervation-dependent switch in the subunit structure of the receptor, in which a y subunit is replaced by an E subunit, is thought to account, in large part, for these differences(1). Because of the interest in the regulatory mechanisms underlying this switch, much attention has focused on these two subunits. Here I report the nucleotide and deduced amino acid sequences of a clone coding for the mouse muscle E subunit isolated from a cDNA library constructed …
The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole
The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole
Dartmouth Scholarship
The simian virus 40 T-antigen carboxy-terminal mutants, dlA2459 and dlA2475, are cell line and temperature dependent for growth and plaque formation in monkey kidney cells. Although these mutants did form plaques on BSC-1 cells at 37 degrees C, they were about fivefold less efficient for plaque formation than wild-type simian virus 40. These mutants did not grow in CV-1 cells and did not synthesize agnoprotein in those cells. CV-1 cells which constitutively express the agnoprotein were permissive for mutant plaque formation. However, late mRNAs, virion proteins, and progeny virion yields did not accumulate to wild-type levels during mutant infection of …
Mechanism Of Escape Of Endogenous Murine Leukemia Virus Emv-14 From Recognition By Anti-Akr/Gross Virus Cytolytic T Lymphocytes., Hillary D. White, Michael D. Robbins, William R. Green
Mechanism Of Escape Of Endogenous Murine Leukemia Virus Emv-14 From Recognition By Anti-Akr/Gross Virus Cytolytic T Lymphocytes., Hillary D. White, Michael D. Robbins, William R. Green
Dartmouth Scholarship
It was previously shown that spleen cells from endogenous ecotropic murine leukemia virus emv-14+ AKXL-5 mice fail to stimulate an anti-AKR/Gross virus cytolytic T-lymphocyte (CTL) response in a mixed lymphocyte culture with primed C57BL/6 responder spleen cells, whereas spleen cells from AKXL strains carrying the very similar emv-11 provirus do stimulate a response (Green and Graziano, Immunogenetics 23:106-110, 1986). We wished to determine whether the lack of response with AKXL-5 spleen cells was at the level of recognition between effector cell and target cell and whether the relevant mutation was within the emv-14 provirus. It is shown here that EMV-negative …
Citrate As A Siderophore In Bradyrhizobium Japonicum., Mary Lou Guerinot, Erik J. Meidl, Ora Plessner
Citrate As A Siderophore In Bradyrhizobium Japonicum., Mary Lou Guerinot, Erik J. Meidl, Ora Plessner
Dartmouth Scholarship
Under iron-limiting conditions, many bacteria secrete ferric iron-specific ligands, generically termed siderophores, to aid in the sequestering and transport of iron. One strain of the nitrogen-fixing soybean symbiont Bradyrhizobium japonicum, 61A152, was shown to produce a siderophore when 20 B. japonicum strains were screened with all six chemical assays commonly used to detect such production. Production by strain 61A152 was detected via the chrome azurol S assay, a general test for siderophores which is independent of siderophore structure. The iron-chelating compound was neither a catechol nor a hydroxamate and was ninhydrin negative. It was determined to be citric acid via …
Fibril In Senile Systemic Amyloidosis Is Derived From Normal Transthyretin., Per Westermark, Knut Sletten, Bjorn Johansson, Gibbons G. Cornwell
Fibril In Senile Systemic Amyloidosis Is Derived From Normal Transthyretin., Per Westermark, Knut Sletten, Bjorn Johansson, Gibbons G. Cornwell
Dartmouth Scholarship
The amyloid fibril in senile systemic amyloidosis (SSA), like that of familial amyloidotic polyneuropathy, is derived from transthyretin (TTR). SSA, however, is a common disease, affecting to some degree 25% of the population greater than 80 years old. In familial amyloidotic polyneuropathy, the amyloidogenesis has been considered to depend on point mutations leading to TTR variants. We show that the TTR molecule in SSA, on the other hand, has a normal primary structure. Factors other than the primary structure of TTR must therefore be important in the pathogenesis of TTR-derived amyloid.
A Rapid And Simple Method For Preparation Of Rna From Saccharomyces Cerevisiae, Mark E. Schmitt, Timothy A. Brown, Bernard L. Trumpower
A Rapid And Simple Method For Preparation Of Rna From Saccharomyces Cerevisiae, Mark E. Schmitt, Timothy A. Brown, Bernard L. Trumpower
Dartmouth Scholarship
Most methods for isolation of RNA from yeast require tedious vortexing with glass beads, and give low yields when scaled down to 10 ml cultures (1). In addition, it is frequently desirable to prepare RNA from several different yeast strains grown under a variety of growth conditions, and preparations using glass beads are impractical when dealing with multiple samples.
A Bound Of Data Availability When Networks Partition, Michael Goldweber, Donald B. Johnson
A Bound Of Data Availability When Networks Partition, Michael Goldweber, Donald B. Johnson
Computer Science Technical Reports
Many consistency or replication control schemes that increase data availability in distributed systems exist, and the search for improvements continues, though there have been no good nontrivial upper bound demonstrating how much improvement is possible. We present a new upper bound for data availability under replication for general networks. In addition we also describe a new technique that yields near optimal levels of data availability with respect to this bound.
N-Ethylmaleimide-Sensitive Protein(S) Involved In Cortical Exocytosis In The Sea-Urchin Egg - Localization To Both Cortical Vesicles And Plasma-Membrane, Robert C. Jackson, Paul A. Modern
N-Ethylmaleimide-Sensitive Protein(S) Involved In Cortical Exocytosis In The Sea-Urchin Egg - Localization To Both Cortical Vesicles And Plasma-Membrane, Robert C. Jackson, Paul A. Modern
Dartmouth Scholarship
The exocytotic release of secretory products from fragments of sea urchin egg cortex has been shown to be inhibited by covalent modification of membrane sulfhydryl groups with N-ethylmaleimide (NEM). Exocytotically competent preparations of reconstituted cortex, formed by recombination of purified cortical vesicles (CVs) with fragments of egg plasma membrane (PM) were also inhibited by treatment with NEM. The cellular localization of sulfhydryl-containing constituent(s) responsible for inhibition was investigated by treating CVs and/or PM with NEM prior to reconstitution. Both native cortex and cortex reconstituted with NEM-treated components were challenged with calcium-containing buffers. Exocytosis was monitored by phase-contrast microscopy, and quantitated …
Murine Gamma Interferon Fails To Inhibit Toxoplasma Gondii Growth In Murine Fibroblasts., Joseph D. Schwartzman, Steven L. Gonias, E R. Pfefferkorn
Murine Gamma Interferon Fails To Inhibit Toxoplasma Gondii Growth In Murine Fibroblasts., Joseph D. Schwartzman, Steven L. Gonias, E R. Pfefferkorn
Dartmouth Scholarship
Although treatment of human macrophages or fibroblasts with human gamma interferon results in the inhibition of intracellular Toxoplasma gondii, murine gamma interferon stimulated only murine macrophages, not murine fibroblasts, to inhibit T. gondii. This species difference may be important in understanding the control of acute and chronic toxoplasmosis.
Building Voronoi Diagrams For Convex Polygons In Linear Expected Time, L Paul Chew
Building Voronoi Diagrams For Convex Polygons In Linear Expected Time, L Paul Chew
Computer Science Technical Reports
Let P be a list of points in the plane such that the points of P taken in order form the vertices of a convex polygon. We introduce a simple, linear expected-time algorithm for finding the Voronoi diagram of the points in P. Unlike previous results on expected-time algorithms for Voronoi diagrams, this method does not require any assumptions about the distribution of points. With minor modifications, this method can be used to design fast algorithms for certain problems involving unrestricted sets of points. For example, fast expected-time algorithms can be designed to delete a point from a Voronoi diagram, …
Term Reduction Using Directed Congruence Closure, L Paul Chew
Term Reduction Using Directed Congruence Closure, L Paul Chew
Computer Science Technical Reports
Many problems in computer science can be described in terms of reduction rules that tell how to transform terms. Problems that can be handled in this way include interpreting programs, implementing abstract data types, and proving certain kinds of theorems. A terms is said to have a normal form if it can be transformed, using the reduction rules, into a term to which no further reduction rules apply. In this paper, we extend the Congruence Closure Algorithm, an algorithm for finding the consequences of a finite set of equations, to develop Directed Congruence Closure, a technique for finding the normal …
Planar Graphs And Sparse Graphs From Efficient Motion Planning In The Plane, L Paul Chew
Planar Graphs And Sparse Graphs From Efficient Motion Planning In The Plane, L Paul Chew
Computer Science Technical Reports
Given a source, a destination, and a number of obstacles in the plane, the Motion Planning Program is to determine the best path to move an object (a robot) from the source to the destination without colliding with any of the obstacles. For us, motion is restricted to the plane, the robot is represented by a point, and the obstacles are represented by a set of polygons with a total of n vertices among all the polygonal obstacles.
Applying The Take-Grant Protection Model, Matt Bishop
Applying The Take-Grant Protection Model, Matt Bishop
Computer Science Technical Reports
The Take-Grant Protection Model has in the past been used to model multilevel security hierarchies and simple protection systems. The models are extended to include theft of rights and sharing of information, and additional security policies are examined. The analysis suggests that in some cases the basic rules of the Take-Grant Protection Model should be augmented to represent the policy properly; when appropriate, such modifications are made and their effects with respect to the policy and its Take-Grant representations are discussed.
A Proactive Password Checker, Matt Bishop
A Proactive Password Checker, Matt Bishop
Computer Science Technical Reports
Password selection has long been a difficult issue; traditionally, passwords are either assigned by the computer or chosen by the user. When the computer does the assignments, the passwords are often hard to remember; when the User makes the selection, the passwords are often easy to guess. This paper describes a technique, and a mechanism, to allow users to select passwords which to them are easy to remember but to others would be very difficult to guess. The technique is site, user, and group configurable, and allows rapid changing of constraints impossed upon the passwords. Although experience with this technique …
Administrator's Guide To The Digital Signature Facility "Rover", Matt Bishop
Administrator's Guide To The Digital Signature Facility "Rover", Matt Bishop
Computer Science Technical Reports
This document describes the installation and maintenance of the rover utility, which provides a digital signature capability for internet messages.
Effects Of Replication On Data Availability, Donald B. Johnson, Larry Raab
Effects Of Replication On Data Availability, Donald B. Johnson, Larry Raab
Computer Science Technical Reports
In this paper we examine the effects of replication on the availability of data in a large network. This analysis differs from previous analyses in that it compares the performance of a dynamic consistency control protocol not only to that of other consistency control protocols, but also to the performance of non-replication and to an upper bound on data availability. This analysis also differes in that we gather extensive simulations on large networks subject to partitions at realistically high component reliabilities. We examine the dynamic consistency protocol presented by Jajodia and Mutchler [9, 12] and by Long and Paris[18] along …
Finding Optimal Quorum Assigments For Distributed Databases, Donald B. Johnson, Larry Raab
Finding Optimal Quorum Assigments For Distributed Databases, Donald B. Johnson, Larry Raab
Computer Science Technical Reports
Replication has been studied as a method of increasing the availability of a data item in a distributed database subject to component failures and consequent partitioning. The potential for partitioning requires that a protocol be employed which guarantees that any access to a data item is aware of the most recent update to that data item. By minimizing the number of access requests denied due to this constraint, we maximize availability. In the event that all access requests are reads, placing one copy of the data item at each site clearly leads to maximum availability. The other extreme, all access …
A Notch-Strengthening Effect In Fresh-Water Ice, Wilfrid A. Nixon, Erland M. Schulson
A Notch-Strengthening Effect In Fresh-Water Ice, Wilfrid A. Nixon, Erland M. Schulson
Dartmouth Scholarship
Tensile tests have been performed onnotched and unnotched cylindrical samples of randomlyoriented polycrystalline ice of controlled grain-size (between2.2 and 7.3mm) at a loading rate of lOOPaS-l and at a temperature of -10 0c. In the notched samples, the notch-root diameter was 80% of the base diameter. Anotch-strengthening effect was observed in the large-grained ice, with fracture stresses being up to 50% higher than that for unnotched samples of the same grain-size. This notch-strengthening effect diminished as grain-size decreased, disappearing at a grain-size of "'3 mm. The notch-strengthening effect is explained in terms of the triaxial stress constraint at the notch …
International Travel And Hiv-Infection, C F. Von Reyn, J M. Mann, J Chin
International Travel And Hiv-Infection, C F. Von Reyn, J M. Mann, J Chin
Dartmouth Scholarship
Although human immunodeficiency virus (HIV) infection is a worldwide problem, its prevalence and pattern vary from country to country. Accordingly, the risk to international travellers of acquiring HIV infection also varies widely in different parts of the world, and depends principally on their behaviour. The risk of sexual acquisition of HIV infection can be virtually eliminated by avoiding penetrative sexual intercourse with intravenous drug users and persons who have had multiple sexual partners (such as prostitutes) or reduced by the use of condoms. The risk of parenteral exposure to HIV can be reduced by avoiding parenteral drug use and behaviour …
Induction Of Antigen-Specific Human Cytotoxic T Cells By Toxoplasma Gondii, I A. Khan, K A. Smith, L H. Kasper
Induction Of Antigen-Specific Human Cytotoxic T Cells By Toxoplasma Gondii, I A. Khan, K A. Smith, L H. Kasper
Dartmouth Scholarship
No abstract provided.
Live Free Or Die, Ernest Hebert
Live Free Or Die, Ernest Hebert
Dartmouth Scholarship
"You stay in your hometown, you end up more of a stranger than if you'd started new someplace else." The struggle between the indigenous rural working class and the upper crust intensifies in this final novel of Hebert's Darby series as Freddy Elman, son of the town trash collector, and Lilith Salmon, daughter of a prestigious family, embark on their ill-fated love affair. Seeing Darby through new eyes, Freddy comes to realize that "the kind of people who hunkered down among these tree-infested, rock-strewn hills" is "dying out, replaced by people with money, education, culture, people 'wise in the ways …