bluuebunny/crossref_metadata_2025 huggingface dataset:
Parallelism and recovery in database systems
Authors: Bayer R. , Heller H. , Reiser A.
Published: July 2002

In this paper a new method to increase parallelism in database systems is described. Use is made of the fact that for recovery reasons, we often have two values for one object in the database—the new one and the old one. Introduced and discussed in detail is a certain scheme by which readers and writers may work simultaneously on the same object. It is proved that transactions executed according to this scheme have the correct effect; i.e., consistency is preserved. Several variations of the basic scheme which are suitable depending on the degree of parallelism required, are described.
New results on quantifier elimination over real closed fields and applications to constraint databases
Authors: Basu Saugata
Published: July 2002

In this paper, we give a new algorithm for quantifier elimination in the first order theory of real closed fields that improves the complexity of the best known algorithm for this problem till now. Unlike previously known algorithms [Basu et al. 1996; Renegar 1992; Heintz et al. 1990], the combinatorial part of the complexity (the part depending on the number of polynomials in the input) of this new algorithm is independent of the number of free variables. Moreover, under the assumption that each polynomial in the input depends only on a constant number of the free variables, the algebraic part of the complexity(the part depending on the degrees of the input polynomials) can also be made independent of the number of free variables. This new feature of our algorithm allow us to obtain a new algorithm for a variant of the quantifier elimination problem. We give an almost optimal algorithm for this new problem, which we call theuniform quantifier elimination problem.

Using tthe uniform quantifier elimination algorithm, we give an algorithm for solving a problem arising in the field of constraint databases with real polynomial constraints. We give an algorithm for converting a query with natural domain semantics to an equivalent one with active domain semantics. A nonconstructive version of this result was proved in Benedikt et al. [1998]. Very recently, a constructive proof was also given independently in Benedikt and Libkin [1997]. However, complexity issues were not considered and no algorithm with a reasonable complexity bound was known for this latter problem till now.

We also point out interesting logical consequences of this algorithmic result, concerning the expressive power of a constraint query language over the reals. This leads to simpler and constructive proofs for these inexpressibility results than the ones known before.

Moreover, our improved algorithm for performing quantifier elimination immediately leads to improved algorithms for several problems for which quantifier elimination is a basic step, for example, the problem of computing the closure of a given semi-algebraic set.
The Synthesis of Recursive Digital Filters
Authors: Holtz Howard , Leondes C. T.
Published: July 2002

The circumstances and methods of the synthesis of linear digital recursive filters which are both stable and physically realizable are described. It is shown that any amplitude requency transfer function expressible as an even trigonometric rational polynomial can be synthesized by a real stable linear digital recursive filter. The degree of the corresponding difference equation is twice the degree of the denominator of the rational trigonometric polynomial.

A class of even rational trigonometric functions which exhibit pointwise convergence to the deal rectangular low or high-pass amplitude frequency transfer function is chosen. A member of this class is shown to approximate more closely the ideal rectangular filter than does the corresponding classical continuous Butterworth filter. This class of filters is then mechanized. The phase and unit-impulse response functions are calculated for the corresponding difference equations of degrees 2 and 4.
Loopless Algorithms for Generating Permutations, Combinations, and Other Combinatorial Configurations
Authors: Ehrlich Gideon
Published: July 2002

The purpose of this work is to find a method for building loopless algorithms for listing combinatorial items, like partitions, permutations, combinations. Gray code, etc. Algorithms for the above sequence are detailed in full.
Program Improvement by Source-to-Source Transformation
Authors: Loveman David B.
Published: July 2002

The use of source-to-source program transformations has proved valuable in improving program performance. The concept of program manipulation is elucidated by describing its role in both conventional optimization and high level modification of conditional, looping, and procedure structures. An example program fragment written in an Algol-like language is greatly improved by transformations enabled by a user-provided assertion about a data array. A compilation model based on the use of source-to-source program transformations is used to provide a framework for discussing issues of code generation, compilation of high level languages such as APL, and eliminating overhead commonly associated with modular structured programming. Application of the compilation model to several different languages is discussed.
Concurrency control performance modeling: alternatives and implications
Authors: Agrawal Rakesh , Carey Michael J. , Livny Miron
Published: July 2002

A number of recent studies have examined the performance of concurrency control algorithms for database management systems. The results reported to date, rather than being definitive, have tended to be contradictory. In this paper, rather than presenting “yet another algorithm performance study,” we critically investigate the assumptions made in the models used in past studies and their implications. We employ a fairly complete model of a database environment for studying the relative performance of three different approaches to the concurrency control problem under a variety of modeling assumptions. The three approaches studied represent different extremes in how transaction conflicts are dealt with, and the assumptions addressed pertain to the nature of the database system's resources, how transaction restarts are modeled, and the amount of information available to the concurrency control algorithm about transactions' reference strings. We show that differences in the underlying assumptions explain the seemingly contradictory performance results. We also address the question of how realistic the various assumptions are for actual database systems.
Smart packets
Authors: Schwartz Beverly , Jackson Alden W. , Strayer W. Timothy , Zhou Wenyi , Rockwell R. Dennis , Partridge Craig
Published: July 2002

This article introduces Smart Packets and describes the smart Packets architecture, the packet formats, the language and its design goals, and security considerations. Smart Packets is an Active Networks project focusing on applying active networks technology to network management and monitoring. Messages in active networks are programs that are executed at nodes on the path to one or more target hosts. Smart Packets programs are written in a tightly encoded, safe language specifically designed to support network management and avoid dangerous constructs and accesses. Smart Packets improves the management of large complex networks by (1) moving management decision points closer to the node being managed, (2) targeting specific aspects of the node for information rather than exhaustive collection via polling, and (3) abstracting the management concepts to language constructs, allowing nimble network control.
Applications of the polynomial s-power basis in geometry processing
Authors: Sánchez-Reyes Javier
Published: July 2002

We propose a unified methodology to tackle geometry processing operations admitting explicit algebraic expressions. This new approach is based on representing and manipulating polynomials algebraically in a recently basis, the symmetric analogue of the power form (s-power basis for brevity), so called because it is associated with a “Hermite two-point expansion” instead of a Taylor expansion. Given the expression of a polynomial in this basis over the unit interval
u
ε[0, 1], degree reduction is trivally obtained by truncation, which yields the He many terms as desired of the corresponding Hermite interpolant and build “s-power series,” akin to Taylor series. Applications include computing integral approximations of rational polynomials, or approximations of offset curves.
Caching in the Sprite network file system
Authors: Nelson Michael N. , Welch Brent B. , Ousterhout John K.
Published: July 2002

The Sprite network operating system uses large main-memory disk block caches to achieve high performance in its file system. It provides non-write-through file caching on both client and server machines. A simple cache consistency mechanism permits files to be shared by multiple clients without danger of stale data. In order to allow the file cache to occupy as much memory as possible, the file system of each machine negotiates with the virtual memory system over physical memory usage and changes the size of the file cache dynamically. Benchmark programs indicate that client caches allow diskless Sprite workstations to perform within O-12 percent of workstations with disks. In addition, client caching reduces server loading by 50 percent and network traffic by 90 percent.
On the modeling of parallel access to shared data
Authors: Chesnais A. , Gelenbe E. , Mitrani I.
Published: July 2002

A model is constructed of a database that can be accessed and modified concurrently by a number of users, and an approximate solution is presented. The resource allocation policies considered involve dynamic acquisition of entities and locking; deadlock is avoided by limiting the number of consecutive attempts to acquire a particular entity. The accuracy of the approximation is evaluated by simulations. Several generalizations aimed at improving the practicality of the model are described.
The computer science research network CSNET
Authors: Comer Douglas
Published: July 2002

In 1981, the National Science Foundation started a five-year project totaling nearly $5 million to construct a computer science research network, CSNET, connecting all groups engaged in computer science research. For an NSF division with an annual budget of $25 million, the award represents an unusual commitment to a single project; only a handful of such large awards have been made. What is CSNET? Why is it receiving such attention? How will it benefit the community? When will it be completed? Who are the architects and implementors?
Performance results of the simplex algorithm for a set of real-world linear programming models
Authors: McCall Edward H.
Published: July 2002

This paper provides performance results using the SPERRY UNIVAC 1100 Series linear programming product FMPS to solve a set of 16 real-world linear programming problems. As such, this paper provides a data point for the actual performance of a commercial simplex algorithm on real-world linear programming problems and shows that the simplex algorithm is a linear time algorithm in actual performance. Correlations and performance relationships not previously available are also provided.
Authentication of signatures using public key encryption
Authors: Booth Kellogg S.
Published: July 2002

One of Needham and Schroeder's proposed signature authentication protocols is shown to fail when there is a possibility of compromised keys: this invalidates one of the applications of their technique. A more elaborate mechanism is proposed which does not require a network clock, but does require a third party to the transaction. The latter approach is shown to be reliable in a fairly strong sense.
Global optimization by suppression of partial redundancies
Authors: Morel E. , Renvoise C.
Published: July 2002

The elimination of redundant computations and the moving of invariant computations out of loops are often done separately, with invariants moved outward loop by loop. We propose to do both at once and to move each expression directly to the entrance of the outermost loop in which it is invariant. This is done by solving a more general problem, i.e. the elimination of computations performed twice on a given execution path. Such computations are termed partially redundant. Moreover, the algorithm does not require any graphical information or restrictions on the shape of the program graph. Testing this algorithm has shown that its execution cost is nearly linear with the size of the program, and that it leads to a smaller optimizer that requires less execution time.
An optimal real-time algorithm for planar convex hulls
Authors: Preparata F. P.
Published: July 2002

An algorithm is described for the construction in real-time of the convex hull of a set of
n
points in the plane. Using an appropriate data structure, the algorithm constructs the convex hull by successive updates, each taking time
O
(log
n
), thereby achieving a total processing time
O
(
n
log
n
).
Secure personal computing in an insecure network
Authors: Denning Dorothy E.
Published: July 2002

A method for implementing secure personal computing in a network with one or more central facilities is proposed. The method employs a public-key encryption device and hardware keys. Each user is responsible for his own security and need not rely on the security of the central facility or the communication links. A user can safely store confidential files in the central facility or transmit confidential data to other users on the network.
Complexity of computations
Authors: Rabin Michael O.
Published: July 2002

The framework for research in the theory of complexity of computations is described, emphasizing the interrelation between seemingly diverse problems and methods. Illustrative examples of practical and theoretical significance are given. Directions for new research are discussed.
Verifying properties of parallel programs
Authors: Owicki Susan , Gries David
Published: July 2002

An axiomatic method for proving a number of properties of parallel programs is presented. Hoare has given a set of axioms for partial correctness, but they are not strong enough in most cases. This paper defines a more powerful deductive system which is in some sense complete for partial correctness. A crucial axiom provides for the use of auxiliary variables, which are added to a parallel program as an aid to proving it correct. The information in a partial correctness proof can be used to prove such properties as mutual exclusion, freedom from deadlock, and program termination. Techniques for verifying these properties are presented and illustrated by application to the dining philosophers problem.
The denotational semantics of programming languages
Authors: Tennent R. D.
Published: July 2002

This paper is a tutorial introduction to the theory of programming language semantics developed by D. Scott and C. Strachey. The application of the theory to formal language specification is demonstrated and other applications are surveyed. The first language considered, LOOP, is very elementary and its definition merely introduces the notation and methodology of the approach. Then the semantic concepts of environments, stores, and continuations are introduced to model classes of programming language features and the underlying mathematical theory of computation due to Scott is motivated and outlined. Finally, the paper presents a formal definition of the language GEDANKEN.
On a solution to the cigarette smoker's problem (without conditional statements)
Authors: Parnas D. L.
Published: July 2002

This report discusses a problem first introduced by Patil, who has claimed that the cigarette smoker's problem cannot be solved using the
P
and
V
operations introduced by Dijkstra unless conditional statements are used. An examination of Patil's proof shows that he has established this claim only under strong restrictions on the use of
P
and
V
. These restrictions eliminate programming techniques used by Dijkstra and others since the first introduction of the semaphore concept. This paper contains a solution to the problem. It also discusses the need for the generalized operators suggested by Patil.
An operating system based on the concept of a supervisory computer
Authors: Gaines R. Stockton
Published: July 2002

An operating system which is organized as a small supervisor and a set of independent processes are described. The supervisor handles I/O with external devices—the file and directory system—schedules active processes and manages memory, handles errors, and provides a small set of primitive functions which it will execute for a process. A process is able to specify a request for a complicated action on the part of the supervisor (usually a wait on the occurrence of a compound event in the system) by combining these primitives into a “supervisory computer program.” The part of the supervisor which executes these programs may be viewed as a software implemented “supervisory computer.” The paper develops these concepts in detail, outlines the remainder of the supervisor, and discusses some of the advantages of this approach.
Requirements for advanced programming systems for list processing
Authors: Bobrow Daniel G.
Published: July 2002

List processing systems should be designed to facilitate production of large programs to manipulate large complex symbolic data stores. This paper presents an overview of a number of system features which the author feels are important to improve the productivity of programmers working in such domains. A systems view is taken, rather than focusing just on language features, since algorithms must be not only coded in a language form, but debugged, modified, made efficient, and run on data. Because of this general framework, the requirements specified are applicable to the design of advanced programming systems for a wide range of applications.

Three aspects of programming systems are highlighted: good interactive facilities, programmable control structures, and sophisticated data communication mechanisms. Interactive features are described to facilitate program composition, entry, testing, debugging, editing, optimization, and packaging. Implementation of a generalized environment structure model specified would allow programming of various control regimes including multiprocesses, coroutines and backtracking. Alternative methods of procedure invocation required include invocation by pattern and by monitoring condition. The need for extended data forms, storage management, and extensibility are stressed, as is the duality of data retrieval and function evaluation. Syntax directed input and output of data would facilitate use of complex data stores.
Experiments with the M & N tree-searching program
Authors: Slagle James R. , Dixon John K.
Published: July 2002

The M & N procedure is an improvement to the mini-max backing-up procedure widely used in computer programs for game-playing and other purposes. It is based on the principle that it is desirable to have many options when making decisions in the face of uncertainty. The mini-max procedure assigns to a MAX (MIN) node the value of the highest (lowest) valued successor to that node. The M & N procedure assigns to a MAX (MIN) node some function of the M (N) highest (lowest) valued successors. An M & N procedure was written in LISP to play the game of kalah, and it was demonstrated that the M & N procedure is significantly superior to the mini-max procedure. The statistical significance of important conclusions is given. Since information on statistical significance has often been lacking in papers on computer experiments in the artificial intelligence field, these experiments can perhaps serve as a model for future work.
Coding the Lehmer pseudo-random number generator
Authors: Payne W. H. , Rabung J. R. , Bogyo T. P.
Published: July 2002

An algorithm and coding technique is presented for quick evaluation of the Lehmer pseudo-random number generator modulo 2 ** 31 - 1, a prime Mersenne number which produces 2 ** 31 - 2 numbers, on a
p
-bit (greater than 31) computer. The computation method is extendible to limited problems in modular arithmetic. Prime factorization for 2 ** 61 - 2 and a primitive root for 2 ** 61 - 1, the next largest prime Mersenne number, are given for possible construction of a pseudo-random number generator of increased cycle length.
Structure of a LISP system using two-level storage
Authors: Bobrow Daniel G. , Murphy Daniel L.
Published: July 2002

In an ideal list-processing system there would be enough core memory to contain all the data and programs. Described in this paper are a number of techniques that have been used to build a LISP system utilizing a drum for its principal storage medium, with a surprisingly low time penalty for use of this slow storage device. The techniques include careful segmentation of system programs, allocation of virtual memory to allow address arithmetic for type determination, and a special algorithm for building reasonably linearized lists. A scheme for binding variables is described which is good in this environment and allows for complete compatibility between compiled and interpreted programs with no special declarations.
EULER
Authors: Wirth Niklaus , Weber Helmut
Published: July 2002

In this section the algorithmic language EULER is described first informally and then formally by its syntax and semantics. An attempt has been made to generalize and extend some of the concepts of ALGOL, thus creating a language which is simpler and yet more flexible than ALGOL 60. A second objective in developing this language was to show that a useful programming language which can be processed with reasonable efficiency can be defined in rigorous formality.
Optimal test access architectures for system-on-a-chip
Authors: Chakrabarty Krishnendu
Published: July 2002

Test access is a major problem for core-based system-on-a-chip (SOC) designs. Since embedded cores in an SOC are not directly accessible via chip inputs and outputs, special access mechanisms are required to test them at the system level. An efficient test access architecture should also reduce test cost by minimizing test application time. We address several issues related to the design of optimal test access architectures that minimize testing time., including the assignment of cores to test buses, distribution of test data width between multiple test buses, and analysis of test data width required to satisfy an upper bound on the testing time. Even though the decision versions of all these problems are shown to be NP-complete, they can be solved exactly for practical instances using integer linear programming (ILP). As a case study, the ILP models for two hypothetical but nontrivial systems are solved using a public-domain ILP software package.
GALILEO: a strongly-typed, interactive conceptual language
Authors: Albano Antonio , Cardelli Luca , Orsini Renzo
Published: July 2002

Galileo, a programming language for database applications, is presented. Galileo is a strongly-typed, interactive programming language designed specifically to support semantic data model features (classification, aggregation, and specialization), as well as the abstraction mechanisms of modern programming languages (types, abstract types, and modularization). The main contributions of Galileo are (a) a flexible type system to model database structure and semantic integrity constraints; (b) the inclusion of type hierarchies to support the specialization abstraction mechanisms of semantic data models; (c) a modularization mechanism to structure data and operations into interrelated units (d) the integration of abstraction mechanisms into an expression-based language that allows interactive use of the database without resorting to a new stand-alone query language.

Galileo will be used in the immediate future as a tool for database design and, in the long term, as a high-level interface for DBMSs.
How to assign votes in a distributed system
Authors: Garcia-Molina Hector , Barbara Daniel
Published: July 2002

In a distributed system, one strategy for achieving mutual exclusion of groups of nodes without communication is to assign to each node a number of votes. Only a group with a majority of votes can execute the critical operations, and mutual exclusion is achieved because at any given time there is at most one such group. A second strategy, which
appears
to be similar to votes, is to define a priori a set of groups that intersect each other. Any group of nodes that finds itself in this set can perform the restricted operations. In this paper, both of these strategies are studied in detail and it is shown that they are
not
equivalent in general (although they are in some cases). In doing so, a number of other interesting properties are proved. These properties will be of use to a system designer who is selecting a vote assignment or a set of groups for a specific application.
Distributed programming in Argus
Authors: Liskov Barbara
Published: July 2002

Argus—a programming language and system developed to support the implementation and execution of distributed programs—provides mechanisms that help programmers cope with the special problems that arise in distributed programs, such as network partitions and crashes of remote nodes.
Conditions for tangent plane continuity over recursively generated B-spline surfaces
Authors: Ball A. A. , Storry D. J. T.
Published: July 2002

The continuity properties of recursively generated B-spline surfaces over an arbitrary topology have been related to the eigenproperties of the local subdivision transformation. In this paper a discrete Fourier transform technique is employed to derive these eigenproperties for a general choice of subdivision weightings. Conditions on these weightings are identified for tangent plane continuity at the extraordinary points and a geometric interpretation is given.
The coloring and maximum independent set problems on planar perfect graphs
Authors: Hsu Wen-Lian
Published: July 2002

Efficient decomposition algorithms for the weighted maximum independent set, minimum coloring, and minimum clique cover problems on planar perfect graphs are presented. These planar graphs can also be characterized by the absence of induced odd cycles of length greater than 3 (odd holes). The algorithm in this paper is based on decomposing these graphs into essentially two special classes of inseparable component graphs whose optimization problems are easy to solve, finding the solutions for these components and combining them to form a solution for the original graph. These two classes are (i) planar comparability graphs and (ii) planar line graphs of those planar bipartite graphs whose maximum degrees are no greater than three. The same techniques can be applied to other classes of perfect graphs, provided that efficient algorithms are available for their inseparable component graphs.
Embedded menus: selecting items in context
Authors: Koved Larry , Shneiderman Ben
Published: July 2002

In many situations, embedded menus represent an attractive alternative to the more traditional explicit menus, particularly in touchtext, spelling checkers, language-based program editors, and graphics-based systems.
The British Nationality Act as a logic program
Authors: Sergot M. J. , Sadri F. , Kowalski R. A. , Kriwaczek F. , Hammond P. , Cory H. T.
Published: July 2002

The formalization of legislation and the development of computer systems to assist with legal problem solving provide a rich domain for developing and testing artificial-intelligence technology.
A common schema for dynamic programming and branch and bound algorithms
Authors: Helman Paul
Published: July 2002

A new model for dynamic programming and branch and bound algorithms is presented. The model views these algorithms as utilizing computationally feasible dominance relations to infer the orderings of application objects, thereby implicitly enumerating a finite solution space. The formalism is broad enough to apply the computational strategies of dynamic programming and branch and bound to problems with nonassociative objects, and can model both oblivious and nonoblivious algorithms, as well as parallel algorithms. The model is used to classify computations based, in part, on the types of computationally feasible dominances that they employ. It is demonstrated that the model is computationally precise enough to support the derivation of lower bounds on the number of operations required to solve various types of problems.
Developing knowledge-based systems: reorganizing the system development life cycle
Authors: Weitzel John R. , Kerschberg Larry
Published: July 2002

Through methodological evolution, the development of the Knowledge-Based Development Life Cycle is supported. In this methodology, processes replace phases and stages and during system development, dynamic activation of processes allows the system to evolve.
Data compression with finite windows
Authors: Fiala E. R. , Greene D. H.
Published: July 2002

Several methods are presented for adaptive, invertible data compression in the style of Lempel's and Ziv's first textual substitution proposal. For the first two methods, the article describes modifications of McCreight's suffix tree data structure that support cyclic maintenance of a window on the most recent source characters. A percolating update is used to keep node positions within the window, and the updating process is shown to have constant amortized cost. Other methods explore the tradeoffs between compression time, expansion time, data structure size, and amount of compression achieved. The article includes a graph-theoretic analysis of the compression penalty incurred by our codeword selection policy in comparison with an optimal policy, and it includes empirical studies of the performance of various adaptive compressors from the literature.
A compact row storage scheme for Cholesky factors using elimination trees
Authors: Liu Joseph W.
Published: July 2002

For a given sparse symmetric positive definite matrix, a compact row-oriented storage scheme for its Cholesky factor is introduced. The scheme is based on the structure of an elimination tree defined for the given matrix. This new storage scheme has the distinct advantage of having the amount of overhead storage required for indexing always bounded by the number of nonzeros in the original matrix. The structural representation may be viewed as storing the minimal structure of the given matrix that will preserve the symbolic Cholesky factor. Experimental results on practical problems indicate that the amount of savings in overhead storage can be substantial when compared with Sherman's compressed column storage scheme.
The influence of relaxed supernode partitions on the multifrontal method
Authors: Ashcraft Cleve , Grimes Roger
Published: July 2002

In this paper we present an algorithm for partitioning the nodes of a graph into supernodes, which improves the performance of the multifrontal method for the factorization of large, sparse matrices on vector computers. This new algorithm first partitions the graph into fundamental supernodes. Next, using a specified relaxation parameter, the supernodes are coalesced in a careful manner to create a coarser supernode partition. Using this coarser partition in the factorization generally introduces logically zero entries into the factor. This is accompanied by a decrease in the amount of sparse vector computations and data movement and an increase in the number of dense vector operations. The amount of storage required for the factor is generally increased by a small amount. On a collection of moderately sized 3-D structures, matrices speedups of 3 to 20 percent on the Cray X-MP are observed over the fundamental supernode partition which allows no logically zero entries in the factor. Using this relaxed supernode partition, the multifrontal method now factorizes the extremely sparse electric power matrices faster than the general sparse algorithm. In addition, there is potential for considerably reducing the communication requirements for an implementation of the multifrontal method on a local memory multiprocessor.
Advanced compiler optimizations for supercomputers
Authors: Padua David A. , Wolfe Michael J.
Published: July 2002

Compilers for vector or multiprocessor computers must have certain optimization features to successfully generate parallel code.
The Format Model
Authors: Hull Richard , Yap Chee K.
Published: July 2002

A mathematical theory for the study of data representation in
databases is introduced and developed. The theory focuses on three
data constructs (collection, composition and classification).
"Formats" with semantically rich yet tractable structure are built
recursively using these constructs. Using formats, we obtain
several nontrivial results concerning notions of relative
information capacity and restructuring of data sets. As such, the
format model provides a new approach for the formal study of the
construction of "user views" and other data manipulations in
databases.
TONOPLAST TRANSPORTERS: Organization and Function
Authors: Maeshima Masayoshi
Published: July 2002

▪ Abstract  Regulation of the contents and volume of vacuoles in plant cells depends on the coordinated activities of transporters and channels located in the tonoplast (vacuolar membrane). The three major components of the tonoplast are two proton pumps, the vacuolar H+-ATPase (V-ATPase) and H+-pyrophosphatase (V-PPase), and aquaporins. The tertiary structure of the V-ATPase complex and properties of its subunits have been characterized by biochemical and genetic techniques. These studies and a comparison with the F-type ATPase have enabled estimation of the dynamics of V-ATPase activity during catalysis. V-PPase, a simple proton pump, has been identified and cloned from various plant species and other organisms, such as algae and phototrophic bacteria, and functional motifs of the enzyme have been determined. Aquaporin, serving as the water channel, is the most abundant protein in the tonoplast in most plants. A common molecular architecture of aquaporins in mammals and plants has been determined by two-dimensional crystallographic analysis. Furthermore, recent molecular biological studies have revealed several other types of tonoplast transporters, such as the Ca2+-ATPase, Ca2+/H+ antiporter and Na+/H+ antiporter. Many other transporters and channels in the tonoplast remain to be identified; their activities have already been detected. This review presents an overview of the field and discusses recent findings on the tonoplast protein components that have been identified and their physiological consequences.
The First 50 Years at Palomar: 1949–1999 The Early Years of Stellar Evolution, Cosmology, and High-Energy Astrophysics
Authors: Sandage Allan
Published: July 2002

PROLOGUE

▪ Abstract 

In 1999 we celebrate the 50th anniversary of the initial bringing into operation of the Palomar 200-inch Hale telescope. When this telescope was dedicated, it opened up a much larger and clearer window on the universe than any telescope that had gone before.

Because the Hale telescope has played such an important role in twentieth century astrophysics, we decided to invite one or two of the astronomers most familiar with what has been achieved at Palomar to give a scientific commentary on the work that has been done there in the first fifty years.

The first article of this kind which follows is by Allan Sandage, who has been an active member of the staff of what was originally the Mount Wilson and Palomar Observatories, and later the Carnegie Observatories for the whole of these fifty years.

The article is devoted to the topics which covered the original goals for the Palomar telescope, namely observational cosmology and the study of galaxies, together with discoveries that were not anticipated, but were first made at Palomar and which played a leading role in the development of high energy astrophysics.

The Palomar work first showed how optical astronomy would be the key to our understanding of observations made in other parts of the electromagnetic spectrum, particularly at radio wavelengths and at X-ray energies.

     —Geoffrey Burbidge, Editor

An account is given of the history of two observational programs set for the Palomar 200-inch telescope, one by Walter Baade and the other by Edwin Hubble near the start of the scheduled operation of the telescope 50 years ago. The review is partly an assessment of whether, and how well, these programs have been carried to completion, and partly an account of the response of Palomar to new discoveries and developments not foreseen in 1950. Stellar evolution, the discovery of variations in the metallicity of stars of different populations, the chemical evolution of the Galaxy, the Cepheid P-L relation, the redshift-distance relation of the expanding universe, and the extragalactic distance scale are discussed as they relate to the predictions for progress on the programs set out by Baade and Hubble. Not foreseen was the invention and development of radio astronomy and high energy astrophysics, leading to the discovery of radio galaxies, quasars, and the gradual realization of violent events, both in stars and in galaxies. The review is highly restricted to these subjects, covering only three areas among the totality of the work in observational astrophysics studied during the first 50 years at Palomar.
BIOCHEMISTRY AND GENETICS OF VON WILLEBRAND FACTOR
Authors: Sadler J. Evan
Published: July 2002

Von Willebrand factor (VWF) is a blood glycoprotein that is required for normal hemostasis, and deficiency of VWF, or von Willebrand disease (VWD), is the most common inherited bleeding disorder. VWF mediates the adhesion of platelets to sites of vascular damage by binding to specific platelet membrane glycoproteins and to constituents of exposed connective tissue. These activities appear to be regulated by allosteric mechanisms and possibly by hydrodynamic shear forces. VWF also is a carrier protein for blood clotting factor VIII, and this interaction is required for normal factor VIII survival in the circulation. VWF is assembled from identical ≈250 kDa subunits into disulfide-linked multimers that may be >20,000 kDa. Mutations in VWD can disrupt this complex biosynthetic process at several steps to impair the assembly, intracellular targeting, or secretion of VWF multimers. Other VWD mutations impair the survival of VWF in plasma or the function of specific ligand binding sites. This growing body of information about VWF synthesis, structure, and function has allowed the reclassification of VWD based upon distinct pathophysiologic mechanisms that appear to correlate with clincial symptoms and the response to therapy.
THE THREE-DIMENSIONAL STRUCTURE OF THE RIBOSOME AND ITS COMPONENTS
Authors: Moore Peter B.
Published: July 2002

▪ Abstract  Exciting progress has been made in the last decade by those who use physical methods to study the structure of the ribosome and its components. The structures of 10 ribosomal proteins and three isolated ribosomal protein domains are known, and the conformations of a significant number of rRNA sequences have been determined. Electron microscopists have made major advances in the analysis of images of ribosomes, and microscopically derived ribosome models at resolutions approaching 10Å are likely quite soon. Furthermore, ribosome crystallographers are on the verge of phasing the diffraction patterns they have had for several years, and near-atomic resolution models for entire ribosomal subunits could emerge from this source at any time. The literature relevant to these developments is reviewed below.
Geodynamo Simulations—How Realistic Are They?
Authors: Glatzmaier Gary A.
Published: July 2002

▪ Abstract  The past seven years have seen significant advances in computational simulations of convection and magnetic field generation in the Earth's core. Although dynamically self-consistent models of the geodynamo have simulated magnetic fields that appear in some ways quite similar to the geomagnetic field, none are able to run in an Earth-like parameter regime because of the considerable spatial resolution that is required. Here we discuss some of the subtle compromises that have been made in current models and propose a grand challenge for the future, requiring significant improvements in numerical methods and spatial resolution.
Lipid Transport Biochemistry and Its Role in Energy Production
Authors: Ryan Robert O. , van der Horst Dick J.
Published: July 2002

▪ Abstract  Recent advances on the biochemistry of flight-related lipid mobilization, transport, and metabolism are reviewed. The synthesis and release of adipokinetic hormones and their function in activation of fat body triacylglycerol lipase to produce diacylglycerol is discussed. The dynamics of reversible lipoprotein conversions and the structural properties and role of the exchangeable apolipoprotein, apolipophorin III, in this process is presented. The nature and structure of hemolymph lipid transfer particle and the potential role of a recently discovered lipoprotein receptor of the low-density lipoprotein receptor family, in lipophorin metabolism and lipid transport is reviewed.
Biology and Management of the Smokybrown Cockroach
Authors: Appel Arthur G. , Smith Lane M.
Published: July 2002

▪ Abstract  The smokybrown cockroach, Periplaneta fuliginosa (Serville), has become an increasingly important peridomestic pest throughout much of the southeastern United States, Japan, and southeast Asia. We provide a brief description of the species and clarify its worldwide distribution. Aspects of smokybrown cockroach behavior, biology, ecology, and physiology are discussed in the context of this species' successful exploitation of the urban environment. We describe smokybrown cockroach management based upon a model that relates house and landscape characteristics to cockroach population size. Finally, we illustrate the effectiveness of a model-based IPM system that increases control while reducing use of insecticides.
Bacterial Symbionts of the Triatominae and Their Potential Use in Control of Chagas Disease Transmission
Authors: Beard C. Ben , Cordon-Rosales Celia , Durvasula Ravi V.
Published: July 2002

▪ Abstract  Chagas disease is caused by the parasitic protozoan Trypanosoma cruzi and transmitted by insects in the family Reduviidae, subfamily Triatominae, commonly known as kissing bugs. Because these insects feed throughout their entire developmental cycle on vertebrate blood, they harbor populations of symbiotic bacteria in their intestinal track that produce nutrients that are lacking in the insects' limited diet. It is possible to cultivate these bacteria, genetically modify them, and place them back into their insect host, thus generating a paratransgenic insect. This procedure has allowed the expression of antitrypanosomal gene products in the insect gut, thereby resulting in insects that are incapable of transmitting Chagas disease. A method has been developed that would allow introduction and spread of genetically modified symbionts into natural populations of kissing bugs, thus leading potentially to a transgenic intervention tool for use as a part of an integrated vector control approach.
NUCLEAR MAGNETIC RESONANCE AS A TOOL TO STUDY FLOW
Authors: Fukushima Eiichi
Published: July 2002

▪ Abstract  Nuclear magnetic resonance (NMR) measurements of flowing materials are reviewed with emphasis on applications to multiphase flows. After a brief presentation of NMR physics, experimental considerations related to flow measurements are discussed. Both imaging and non-imaging NMR as well as topics such as Earth's field NMR and rapid imaging are covered. Specific topics that follow are tagging and time-of-flight, phase measurement of velocity, diffusion, turbulence, and calibration and validations. Finally, recent applications are reviewed in the areas of sedimentation, suspension flows in Couette and pipe geometries, rheometers and viscometers, liquid-liquid multiphase flows, porous media flow, granular flows, and turbulence.
MATING TYPE IN FILAMENTOUS FUNGI
Authors: Kronstad J. W. , Staben C.
Published: July 2002

▪ Abstract  Mating type genes regulate sexual compatibility and sexual reproduction in fungi. This review focuses on recent molecular analyses of well-characterized mating systems from representative ascomycete (Neurospora crassa, Podospora anserina) and basidiomycete (Ustilago maydis, Coprinus cinereus, Schizophyllum commune) fungi. These mating systems include many conserved components, such as gene regulatory polypeptides and pheromone/receptor signal transduction cascades, as well as conserved processes, like self-nonself recognition and controlled nuclear migration. The components' structures and their genetic arrangements in the mating system vary greatly in different fungi. Although similar components and processes are also found in ascomycete yeasts (Saccharomyces cerevisiae and Schizosaccharomyces pombe), the filamentous systems exhibit properties not encountered in yeast. Mating type genes act within, and control the development of, spatially differentiated fruiting bodies. The complex mating systems of basidiomycetes, unlike ascomycete systems, involve novel one-to-many specificity in both pheromone-receptor and homeodomain protein interactions.
THE DIVERSE AND DYNAMIC STRUCTURE OF BACTERIAL GENOMES
Authors: Casjens Sherwood
Published: July 2002

▪ Abstract  Bacterial genome sizes, which range from 500 to 10,000 kbp, are within the current scope of operation of large-scale nucleotide sequence determination facilities. To date, 8 complete bacterial genomes have been sequenced, and at least 40 more will be completed in the near future. Such projects give wonderfully detailed information concerning the structure of the organism's genes and the overall organization of the sequenced genomes. It will be very important to put this incredible wealth of detail into a larger biological picture: How does this information apply to the genomes of related genera, related species, or even other individuals from the same species? Recent advances in pulsed-field gel electrophoretic technology have facilitated the construction of complete and accurate physical maps of bacterial chromosomes, and the many maps constructed in the past decade have revealed unexpected and substantial differences in genome size and organization even among closely related bacteria. This review focuses on this recently appreciated plasticity in structure of bacterial genomes, and diversity in genome size, replicon geometry, and chromosome number are discussed at inter- and intraspecies levels.
Lentivirus Replication and Regulation
Authors: Tang Hengli , Kuhen Kelli L , Wong-Staal Flossie
Published: July 2002

▪ Abstract  Lentiviruses are associated with chronic diseases of the hematological and neurological systems in animals and man. In particular, human immunodeficiency virus type 1 (HIV-1) is the etiological agent of the global AIDS epidemic. The genomes of lentiviruses are complex, encoding a number of regulatory and accessory proteins not found in other retroviruses. This complexity is reflected in their replication cycle, which reveals intricate regulatory pathways and unique mechanisms for viral persistence. In this review, we highlight some of these unique features for HIV-1, with particular focus on the transcriptional and posttranscriptional control of gene expression. Although our understanding of the biology of HIV-1 is far from complete, the knowledge gained thus far has already led to novel strategies for both virus intervention and exploiting the lentiviruses for therapeutic applications.
New Perspectives on Nuclear Transport
Authors: Komeili Arash , O'Shea Erin K.
Published: July 2002

▪ Abstract  A central aspect of cellular function is the proper regulation of nucleocytoplasmic transport. In recent years, significant progress has been made in identifying and characterizing the essential components of the transport machinery. Despite these advances, some facets of this process are still unclear. Furthermore, recent work has uncovered novel molecules and mechanisms of nuclear transport. This review focuses on the unresolved and novel aspects of nuclear transport and explores issues in tRNA, snRNA, and mRNA export that highlight the diversity of nuclear transport mechanisms.