bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of tree structures for efficient querying
Authors: Casey R. G.
Published: July 2002

A standard information retrieval operation is to determine which records in a data collection satisfy a given query expressed in terms of data values. The process of locating the desired responses can be represented by a tree search model. This paper poses an optimization problem in the design of such trees to serve a well-specified application. The problem is academic in the sense that ordinarily the optimal tree cannot be implemented by means of practical techniques. On the other hand, it is potentially useful for the comparison it affords between observed performance and that of an intuitively attractive ideal search procedure.

As a practical application of such a model this paper considers the design of a novel tree search scheme based on a bit vector representation of data and shows that essentially the same algorithm can be used to design either an ideal search tree or a bit-vector tree. An experimental study of a small formatted file illustrates the concepts.
On the meaning of names in programming systems
Authors: Fraser A. G.
Published: July 2002

It is assumed that there is a similarity of function between the data names of a programming language and the file names of an operating system. The two functions are discussed in terms of the same basic concepts in order to identify the extent to which they overlap. It is suggested that there is some similarity between the idea of a file directory and a storable object of type context. Manipulations with contexts are then discussed at length.

It is noted that there is a simple extension of Church's λ notation that deals nicely with these ideas of context manipulation. Whereas a function can be regarded as the abstraction based upon the first two terms of the expression λ(namelist)(expression)(valuelist), it is found that a context can be viewed as an abstraction based upon the first two terms in the equivalent expression μ(namelist)(valuelist)(expression).
The MAD definition facility
Authors: Arden Bruce W. , Galler Bernard A. , Graham Robert M.
Published: July 2002

One of the first definition facilities for higher level languages is described. Users of the language can define new operators and/or data types into the MAD language, so that their use appears as if they were predefined. Information is given on how one writes definitions, as well as on much of the motivation behind the form in which definitions are written. Some conclusions are drawn about future definitional facilities.
The IITRAN programming language
Authors: Dewar Robert B. K. , Hochsprung Ronald R. , Worley William S.
Published: July 2002

The IITRAN language, developed to be used by students, and its important features are described. IITRAN is a procedure-oriented language with a one-level block structure and a variety of data types. Several novel and powerful features are included. A discussion of design principles to be followed in a student language is given.
APAREL—A parse-request language
Authors: Balzer R. M. , Farber D. J.
Published: July 2002

APAREL is described: this language is an extension to an algorithmic language (PL/I) that provides the pattern-matching capabilities normally found only in special purpose languages such as SNOBOL4 and TMG. This capability is provided through parse-requests stated in a BNF-like format. These parse-requests form their own programming language with special sequencing rules. Upon successfully completing a parse-request, an associated piece of PL/I code is executed. This code has available for use, as normal PL/I strings, the various pieces (at all levels) of the parse. It also has available, as normal PL/I variables, the information concerning which of the various alternatives were successful. Convenient facilities for multiple input-output streams, the initiation of sequences of parse-requests as a subroutine, and parse-time semantic checks are also included.

APAREL has proven convenient in building a powerful SYNTAX and FUNCTION macro system, an algebraic language preprocessor debugging system, an on-line command parser, a translator for Dataless Programming, and as a general string manipulator.
A futures market in computer time
Authors: Sutherland I. E.
Published: July 2002

An auction method is described for allocating computer time that allows the price of computer time to fluctuate with the demand and the relative priority of users to be controlled so that more important projects get better access. This auction is free of the periodic fluctuation in computer use often associated with monthly schemes.
CLP-the Cornell list processor
Authors: Conway R. W. , Delfausse J. J. , Maxwell W. L. , Walker W. E.
Published: July 2002

Presented in this paper are the highlights of CLP, a teaching language which has been employed at Cornell University and was constructed to serve as a means of introducing simulation and other list-processing concepts. The various advantages of CLP are discussed and examples are given.
Randomized binary searching with tree structures
Authors: Clampett Harry A.
Published: July 2002

A more efficient method of using tree structures is proposed, which utilizes both plus and minus branches in the search path. Very significant gains result when the search key includes alphabetic characters.
Approximate solution of initial-boundary wave equation problems by boundary-value techniques
Authors: Greenspan Donald
Published: July 2002

A new boundary-value technique is proposed for the treatment of initial-boundary-value problems for linear and mildly non-linear wave equations. Several illustrative examples are offered to demonstrate the ease with which the method can be applied.
A language for describing the functions of synchronous systems
Authors: Parnas David L.
Published: July 2002

Before the design of a system is started, the exact function desired of it should be specified. It is suggested that a computer-oriented language be used for this purpose. The inadequacies of the standard programming languages for the description of systems are discussed, and a dialect of ALGOL which is suitable for describing synchronous systems is introduced. These descriptions can be used for simulation and automatic design of the system described, in addition to communicating system specifications.
Proposal for an UNCOL
Authors: Conway Melvin E.
Published: July 2002

This discussion contains a proposal for a universal computer-oriented language (UNCOL) to be used as a common path between the problem-oriented language (POL) and the machine language (ML) in compatible automatic programming systems. (See Ref. 1.)
Architecture-level power estimation and design experiments
Authors: Chen Rita Yu , Irwin Mary Jane , Bajwa Raminder S.
Published: July 2002

Architecture-level power estimation has received more attention recently because of its efficiency. This article presents a technique used to do power analysis of processors at the architecture level. It provides cycle-by-cycle power consumption data of the architecture on the basis of the instruction/data flow stream. To characterize the power dissipation of control units, a novel hierarchical method has been developed. Using this technique, a power estimator is implemented for a commercial processor. The accuracy of the estimator is validated by comparing the power values it produces against measurements made by a gate-level power simulator for the same benchmark set. Our estimation approach is shown to provide very efficient and accurate power analysis at the architecture level. The energy models built for first-pass estimation (such as ALU, MAC unit, register files) are reusable for future architecture design modification. In this article, we demonstrate the application of the technique. Furthermore, this technique can evaluate various kinds of software to achieve hardware/software codesign for low power.
A model of computation for VLSI with related complexity results
Authors: Chazelle Bernard , Monier Louis
Published: July 2002

A new model of computation for VLSI, based on the assumption that time for propagating information is at least linear in the distance, is proposed. While accommodating for basic laws of physics, the model is designed to be general and technology independent. Thus, from a complexity viewpoint, it is especially suited for deriving lower bounds and trade-offs. New results for a number of problems, including fan-in, transitive functions, matrix multiplication, and sorting are presented. As regards upper bounds, it must be noted that, because of communication costs, the model clearly favors regular and pipelined architectures (e.g., systolic arrays).
Error bounds for performance prediction in queuing networks
Authors: Tay Y. C. , Suri Rajan
Published: July 2002

Analytic models based on closed queuing networks (CQNS) are widely used for performance prediction in practical systems. In using such models, there is always a prediction error, that is, a difference between the predicted performance and the actual outcome. This prediction error is due both to modeling errors and estimation errors, the latter being the difference between the estimated values of the CQN parameters and the actual outcomes. This paper considers the second class of errors; in particular, it studies the effect of small estimation errors and provides bounds on prediction errors based on bounds on estimation errors. Estimation errors may be divided into two types: (1) the difference between the estimated value and the average value of the outcome, and (2) the deviation of the actual value from its average. The analysis first studies the sum of both types of errors, then the second type alone. The results are illustrated with three examples.
Access methods for text
Authors: Faloutsos Chris
Published: July 2002

This paper compares text retrieval methods intended for office systems. The operational requirements of the office environment are discussed, and retrieval methods from database systems and from information retrieval systems are examined. We classify these methods and examine the most interesting representatives of each class. Attempts to speed up retrieval with special purpose hardware are also presented, and issues such as approximate string matching and compression are discussed. A qualitative comparison of the examined methods is presented. The signature file method is discussed in more detail.
Office-by-example: an integrated office system and database manager
Authors: Whang Kyu-Young , Ammann Art , Bolmarcich Anthony , Hanrahan Maria , Hochgesang Guy , Huang Kuan-Tsae , Khorasani Al , Krishnamurthy Ravi , Sockut Gary , Sweeney Paula , Waddle Vance , Zloof Moshé
Published: July 2002

Office-by-Example (OBE) is an integrated office information system that has been under development at IBM Research. OBE, an extension of Query-by-Example, supports various office features such as database tables, word processing, electronic mail, graphics, images, and so forth. These seemingly heterogeneous features are integrated through a language feature called
example elements
. Applications involving example elements are processed by the database manager, an integrated part of the OBE system. In this paper we describe the facilities and architecture of the OBE system and discuss the techniques for integrating heterogeneous objects.
Managing prototype knowledge/expert system projects
Authors: Cupello James M. , Mishelevich David J.
Published: July 2002

Computer science technology in the 1990s will involve knowledge/expert systems. Fundamental issues of technology transfer, training, problem selection, staffing, corporate politics, and more, are explored.
Orthogonal Latin squares: an application of experiment design to compiler testing
Authors: Mandl Robert
Published: July 2002

Orthogonal Latin squares—a new method for testing compilers—yields the informational equivalent of exhaustive testing at a fraction of the cost. The method has been used successfully in designing some of the tests in the Ada Compiler Validation Capability (ACVC) test suite.
Systems programming with JSP: example—a VDU controller
Authors: Sanden Bo
Published: July 2002

The generation of an embedded microprogram controlling a video display unit demonstrates how Jackson Structured Programming can be used effectively for both systems programming and microprocessor applications.
Implementation concepts for an extensible data model and data language
Authors: Batory D. S. , Leung T. Y. , Wise T. E.
Published: July 2002

Future database systems must feature extensible data models and data languages in order to accommodate the novel data types and special-purpose operations that are required by nontraditional database applications. In this paper, we outline a functional data model and data language that are targeted for the semantic interface of GENESIS, an extensible DBMS. The model and language are generalizations of FQL [11] and DAPLEX [40], and have an implementation that fits ideally with the modularity required by extensible database technologies. We explore different implementations of functional operators and present experimental evidence that they have efficient implementations. We also explain the advantages of a functional front-end to ¬1NF databases, and show how our language and implementation are being used to process queries on both 1NF and ¬1NF relations.
Toward the domestication of microelectronics
Authors: Birnbaum Joel S.
Published: July 2002

The great challenge for computer science in this decade is to make computers usable by everyone. Computers, long viewed as a dehumanizing force, will become the most powerful means of personal creative expression and communication ever known.
Dynamic hashing schemes
Authors: Enbody R. J. , Du H. C.
Published: July 2002

A new type of dynamic file access called
dynamic hashing
has recently emerged. It promises the flexibility of handling dynamic files while preserving the fast access times expected from hashing. Such a fast, dynamic file access scheme is needed to support modern database systems. This paper surveys dynamic file access scheme is needed to support modern database systems. This paper surveys dynamic hashing schemes and examines their critical design issues.
Counting is easy
Authors: Seiferas Joel I. , Vitányi Paul M. B.
Published: July 2002

For any fixed
k
, a remarkably simple single-tape Turing machine can simulate
k
independent counters in real time.
Acceptable internet use policy
Authors: Siau Keng , Nah Fiona Fui-Hoon , Teng Limei
Published: July 2002

Surveying use policies of three organizations--- educational institutions, ISPs, and non-ISPs.
Multiway spatial joins
Authors: Mamoulis Nikos , Papadias Dimitris
Published: July 2002

Due to the evolution of Geographical Information Systems, large collections of spatial data having various thematic contents are currently available. As a result, the interest of users is not limited to simple spatial selections and joins, but complex query types that implicate numerous spatial inputs become more common. Although several algorithms have been proposed for computing the result of pairwise spatial joins, limited work exists on processing and optimization of
multiway spatial joins
. In this article, we review pairwise spatial join algorithms and show how they can be combined for multiple inputs. In addition, we explore the application of
synchronous traversal
(ST), a methodology that processes synchronously all inputs without producing intermediate results. Then, we integrate the two approaches in an engine that includes ST and pairwise algorithms, using dynamic programming to determine the optimal execution plan. The results show that, in most cases, multiway spatial joins are best processed by combining ST with pairwise methods. Finally, we study the optimization of very large queries by employing randomized search algorithms.
Making ontologies work for resolving redundancies across documents
Authors: Everett John O. , Bobrow Daniel G. , Stolle Reinhard , Crouch Richard , de Paiva Valeria , Condoravdi Cleo , van den Berg Martin , Polanyi Livia
Published: July 2002

Producing normalized representations from different ways of expressing the same idea.
On filter effects in web caching hierarchies
Authors: Williamson Carey
Published: July 2002

This article studies the "filter effects" that occur in Web proxy caching hierarchies due to the presence of multiple levels of caches. That is, the presence of one level of cache changes the structural characteristics of the workload presented to the next level of cache, since only the requests that miss in one cache are forwarded to the next cache.Trace-driven simulations, with empirical and synthetic traces, are used to demonstrate the presence and magnitude of the filter effects in a multilevel Web proxy caching hierarchy. Experiments focus on the effects of cache size, cache replacement policy, Zipf slope, and the depth of the Web proxy caching hierarchy.Finally, the article considers novel cache management techniques that can better exploit the changing workload characteristics across a multilevel Web proxy caching hierarchy. Trace-driven simulations are used to evaluate the performance of these approaches. The simulation results demonstrate that size-based partitioning and heterogeneous cache replacement policies each offer improvements in overall caching performance. The sensitivity of the results to the degree of workload overlap among child-level proxy caches is also studied.
Abstraction-based intrusion detection in distributed environments
Authors: Ning Peng , Jajodia Sushil , Wang Xiaoyang Sean
Published: July 2002

Abstraction is an important issue in intrusion detection, since it not only hides the difference between heterogeneous systems, but also allows generic intrusion-detection models. However, abstraction is an error-prone process and is not well supported in current intrusion-detection systems (IDSs). This article presents a hierarchical model to support attack specification and event abstraction in distributed intrusion detection. The model involves three concepts:
system view
,
signature
, and
view definition
. A system view provides an abstract interface of a particular type of information; defined on the instances of system views, a signature specifies certain distributed attacks or events to be monitored; a view definition is then used to derive information from the matches of a signature and presents it through a system view. With the three elements, the model provides a hierarchical framework for maintaining signatures, system views, as well as event abstraction. As a benefit, the model allows generic signatures that can accommodate unknown variants of known attacks. Moreover, abstraction represented by a system view can be updated without changing either its specification or the signatures specified on its basis. This article then presents a decentralized method for autonomous but cooperative component systems to detect distributed attacks specified by signatures. Specifically, a signature is decomposed into finer units, called
detection tasks
, each of which represents the activity to be monitored on a component system. The component systems (involved in a signature) then perform the detection tasks cooperatively according to the "dependency" relationships among these tasks. An experimental system called
CARDS
has been implemented to test the feasibility of the proposed approach.
Applications of Byzantine agreement in database systems
Authors: Garcia Molina Hector , Pittelli Frank , Davidson Susan
Published: July 2002

In this paper we study when and how B Byzantine agreement protocol can he used in general-purpose database management systems. We present an overview of the failure model used for Byzantine agreement, and of the protocol itself. We then present correctness criteria for database processing in this failure environment and discuss strategies for satisfying them. In doing this, we present new failure models for input/output nodes and study ways to distribute input transactions to processing nodes under these models. Finally, we investigate applications of Byzantine agreement protocols in the more common failure environment where processors are assumed to halt after a failure.
Summary of the second annual UCLA survey of business school computer usage
Authors: Frand Jason L. , McLean Ephraim R.
Published: July 2002

The compilation and analysis of data collected from 125 business schools reveal important trends and identify problems that arise when computers are integrated into education.
Parsing distfix operators
Authors: Peyton Jones Simon L.
Published: July 2002

The advantages of user-defined distfix operators—a syntactic convenience that enhances the readability of programs—can be obtained as an extension of almost any programming language without requiring dynamic changes to the parser.
Positive alternatives: a report on an ACM panel on hacking
Authors: Lee John A. , Segal Gerald , Steier Rosalie
Published: July 2002

A broad cross section of computer security experts, hackers, educators, journalists, and corporate executives examine hacking issues, problems, and possible solutions.
A modular system of algorithms for unconstrained minimization
Authors: Schnabel Robert B. , Koonatz John E. , Weiss Barry E.
Published: July 2002

We describe a new package, UNCMIN, for finding a local minimizer of a real valued function of more than one variable. The novel feature of UNCMIN is that it is a modular system of algorithms, containing three different step selection strategies (line search, dogleg, and optimal step) that may be combined with either analytic or finite difference gradient evaluation and with either analytic, finite difference, or BFGS Hessian approximation. We present the results of a comparison of the three step selection strategies on the problems in More, Garbow, and Hillstrom in two separate cases: using finite difference gradients and Hessians, and using finite difference gradients with BFGS Hessian approximations. We also describe a second package, REVMIN, that uses optimization algorithms identical to UNCMIN but obtains values of user-supplied functions by reverse communication.
Unification: a multidisciplinary survey
Authors: Knight Kevin
Published: July 2002

The unification problem and several variants are presented. Various algorithms and data structures are discussed. Research on unification arising in several areas of computer science is surveyed; these areas include theorem proving, logic programming, and natural language processing. Sections of the paper include examples that highlight particular uses of unification and the special problems encountered. Other topics covered are resolution, higher order logic, the occur check, infinite terms, feature structures, equational theories, inheritance, parallel algorithms, generalization, lattices, and other applications of unification. The paper is intended for readers with a general computer science background—no specific knowledge of any of the above topics is assumed.
A practical sieve algorithm finding prime numbers
Authors: Luo Xuedong
Published: July 2002

Based on the sieve of Eratosthenes, a faster and more compact algorithm is presented for finding all primes between 2 and N.
The SEI education program: the challenge of teaching future software engineers
Authors: Gibbs N. E.
Published: July 2002

As the technical foundations of software production emerge, software engineers run the risk of obsolescence—now.
Conversation-based mail
Authors: Comer Douglas E. , Peterson Larry L.
Published: July 2002

A new message communication paradigm based on
conversations
that provides an alternative to
memo
- and
conference
-based mail is described. A conversation-based message system groups messages into conversations, and orders messages within a conversation according to the
context
in which they were written. The message context relation leads to an efficient implementation of conversations in a distributed environment and supports a natural ordering of messages when viewed by the user. Experience with a prototype demonstrates the workability of conversation-based mail and suggests that conversations provide a powerful tool for message communication.
Consistency of transactions and random batch
Authors: Bayer Rudolf
Published: July 2002

A synchronization technique and scheduling strategy is described, which allows us to run a batch process simultaneously with on-line transactions. The batch process and the transactions are serialized in such a way that consistency level 3 is achieved.
A logarithmic time sort for linear size networks
Authors: Reif John H. , Valiant Leslie G.
Published: July 2002

A randomized algorithm that sorts on an
N
node network with constant valence in
O
(log
N
) time is given. More particularly, the algorithm sorts
N
items on an
N
-node cube-connected cycles graph, and, for some constant
k
, for all large enough
α
, it terminates within
kα
log
N
time with probability at least 1 -
N

-
α

.
Weyl group orbits
Authors: Snow Dennis M.
Published: July 2002

A new technique is presented for calculating the orbits of the finite Weyl group of a semisimple Lie group
G
in the weight lattice of
G
. Such calculations are important in the representation theory of
G
, and have previously been difficult to carry out for large Weyl groups such as
E
8
. This new technique allows large orbits to be computed using only a small fraction of the computer memory required when using standard techniques. In the case of
E
8
, the memory requirements can be reduced by a factor of 30,000.
Rasterization of nonparametric curves
Authors: Hobby John D.
Published: July 2002

We examine a class of algorithms for rasterizing algebraic curves based on an implicit form that can be evaluated cheaply in integer arithmetic using finite differences. These algorithms run fast and produce “optimal” digital output, where previously known algorithms have had serious limitations. We extend previous work on conic sections to the cubic and higher order curves, and we solve an important undersampling problem.
Analysis of database performance with dynamic locking
Authors: Ryu In Kyung , Thomasian Alexander
Published: July 2002

A detailed model of a transaction processing system with dynamic locking is developed and analyzed. Transaction classes are distinguished on the basis of the number of data items accessed and the access mode (read-only/update). The performance of the system is affected by transaction blocking and restarts, due to lock conflicts that do not or do cause deadlocks, respectively. The probability of these events is determined by the characteristics of transactions and the database access pattern. Hardware resource contention due to concurrent transaction processing is taken into account by specifying the throughput characteristic of the computer system for processing transactions when there is no data contention. A solution method based on decomposition is developed to analyze the system, and also used as the basis of an iterative scheme with reduced computational cost. The analysis to estimate the probability of lock conflicts and deadlocks is based on the mean number of locks held by transactions. These probabilities are used to derive the state transition probabilities for the Markov chain specifying the transitions among the system states. The decomposition solution method and the associated iterative scheme are shown to be more accurate than previously defined methods for dynamic locking through validation against simulation results. Several important conclusions regarding the behavior of dynamic locking systems are derived from parametric studies.
Cache considerations for multiprocessor programmers
Authors: Hill Mark D. , Larus James R.
Published: July 2002

Although caches in most computers are invisible to programmers, they significantly affect program performance. This is particularly true for cache-coherent, shared-memory multiprocessors. This article presents recent research into the performance of parallel programs and its implications for programmers who may know little about caches.
Sharing scientific data
Authors: Sterling Theodor D. , Weinkam James J.
Published: July 2002

The willingness of one scientist to share data with another scientist continues to be influenced by a number of enconomic, social, psychological and political factors.
A Formal Method for the Abstract Specification of Software
Authors: McLean John
Published: July 2002

An intuitive presentation of the trace method for the abstract
specification of software contains sample specifications, syntactic
and semantic definitions of consistency and totalness, methods for
proving specifications consistent and total, and a comparison of
the method with the algebraic approach to specification. This
intuitive presentation is underpinned by a formal syntax,
semantics, and derivation system for the method. Completeness and
soundness theorems establish the correctness of the derivation
system with respect to the semantics, the coextensiveness of the
syntactic definitions of consistency and totalness with their
semantic counterparts, and the correctness of the proof methods
presented. Areas for future research are discussed.
Direct transitive closure algorithms: design and performance evaluation
Authors: Agrawal Rakesh , Dar Shaul , Jagadish H. V.
Published: July 2002

We present new algorithms for computing transitive closure of large database relations. Unlike iterative algorithms, such as the seminaive and logarithmic algorithms, the termination of our algorithms does not depend on the length of paths in the underlying graph (hence the name
direct
algorithms). Besides reachability computations, the proposed algorithms can also be used for solving path problems. We discuss issues related to the efficient implementation of these algorithms, and present experimental results that show the direct algorithms perform uniformly better than the iterative algorithms. A side benefit of this work is that we have proposed a new methodology for evaluating the performance of recursive queries.
SEAVE: a mechanism for verifying user presuppositions in query systems
Authors: Motro Amihai
Published: July 2002

Every information system incorporates a database component, and a frequent activity of users of information systems is to present it with queries. These queries reflect the presuppositions of their authors about the system and the information it contains. With most query processors, queries that are based on erroneous presuppositions often result in null answers. These fake nulls are misleading, since they do not point out the user's erroneous presuppositions (and can even be interpreted as their affirmation). This article describes the SEAVE mechanism for extracting presuppositions from queries and verifying their correctness. The verification is done against three repositories of information: the actual data, their integrity constraints, and their completeness assertions. Consequently, queries that reflect erroneous presuppositions are answered with informative messages instead of null answers, and user-system communication is thus improved (an aspect that is particularly important in systems that often are accessed by naive users). First, the principles of SEAVE are described abstractly. Then, specific algorithms for implementing it with relational databases are presented, including a new method for storing knowledge and an efficient algorithm for processing queries against the knowledge.
Unidraw: a framework for building domain-specific graphical editors
Authors: Vlissides John M. , Linton Mark A.
Published: July 2002

Unidraw is a framework for creating graphical editors in domains such as technical and artistic drawing, music composition, and circuit design. The Unidraw architecture simplifies the construction of these editors by proving programming abstractions that are common across domains. Unidraw defines four basic abstractions:
components
define operations on components, and
external representations
define the mapping between components and the file format generated by the editor. Unidraw also supports multiple views, graphical connectivity, and dataflow between components. This paper describes the Unidraw design, implementation issues, and three experimental domain specific editors we have developed with Unidraw: a drawing editor, a user interface builder, and a schematic capture system. Our results indicate a substantial reduction in implementation time and effort compared with existing tools.
The effects of processor architecture on instruction memory traffic
Authors: Mitchell Chad L. , Flynn Michael J.
Published: July 2002

The relative amount of instruction traffic for two architectures is about the same in the presence of a large cache as with no cache. Furthermore, the presence of an intermediate-sized cache probably substantially favors the denser architecture. Encoding techniques have a much greater impact on instruction traffic than do the differences between instruction set families such as stack and register set. However, register set architectures have somewhat lower instruction traffic than directly comparable stack architectures of some local variables are allocated in registers. This study has clearly indicated that cache factors should be taken into consideration when making architectural tradeoffs. The differences in memory traffic between two architectures may be greatly amplified in the presence of a cache.
State and Society at Teotihuacan, Mexico
Authors: Cowgill George L.
Published: July 2002

Between 100 BCE and 200 CE, the city of Teotihuacan grew rapidly, most of the Basin of Mexico population was relocated in the city, immense civic-religious structures were built, and symbolic and material evidence shows the early importance of war. Rulers were probably able and powerful. Subsequently the city did not grow, and government may have become more collective, with significant constraints on rulers' powers. A state religion centered on war and fertility deities presumably served elite interests, but civic consciousness may also have been encouraged. A female goddess was important but probably not as pervasive as has been suggested. Political control probably did not extend beyond central Mexico, except perhaps for some outposts, and the scale and significance of commerce are unclear. Teotihuacan's prestige, however, spread widely in Mesoamerica, manifested especially in symbols of sacred war, used for their own ends by local elites.
CURRENT ISSUES IN LINGUISTIC TAXONOMY
Authors: Michalove Peter A. , Georg Stefan , Ramer Alexis Manaster
Published: July 2002

▪ Abstract  The genealogical classification of languages has been the subject of investigation for more than two centuries, and progress continues to be made in deepening our understanding of language change, both in theoretical terms and in the study of specific language families. In recent years, as in the past, many new proposals of linguistic relationships have been constructed, some promising to various degrees and others clearly untenable. The debate about specific recent proposals is part of the healthy process needed to evaluate proposed relationships, discard those that prove incorrect, and refine those of merit. Rather than evaluating the relative linguistic “distance” between potentially related languages, with temporal distance leading to some point where we cannot distinguish real relationships from chance similarities, we propose a scale of easy to difficult relationships in which temporal distance is only one factor that makes some relationships more recognizable than others.
The Political Economy of Archaeology in the United States
Authors: Patterson Thomas C.
Published: July 2002

▪ Abstract  The professionalization of archaeology in the late nineteenth century was linked to the growth of antiquities markets and the development of museums as institutions of education and social reproduction. Professional archaeologists moved into the universities in large numbers after World War II and then increasingly into the private sector after the mid-1970s. In the United States, archaeologists currently confront a highly segmented labor market with significant wage and benefits differentials, and increasing numbers face marginal employment. At the same time, descendant communities and government regulations are transforming the ways by which archaeologists have traditionally conducted their investigations.
The State of Culture Theory in the Anthropology of Southeast Asia
Authors: Steedly Mary Margaret
Published: July 2002

▪ Abstract  Southeast Asia is probably the part of the world most closely associated by anthropologists with an interpretive concept of culture. Yet do such ideas as culture areas or local cultures retain their analytical salience when our attention turns to processes of domination, displacement, and diaspora? This article considers the state of culture theory in the anthropology of Southeast Asia today, focusing on the themes of gender, marginality, violence, and the state. Culture is increasingly viewed as an attribute of the state—an object of state policy, an ideological zone for the exercise of state power, or literally a creation of the state—whereas the state itself is comprehended in ways analogous to totalizing models of culture.
GENETIC ANALYSIS OF OVULE DEVELOPMENT
Authors: Gasser C. S. , Broadhvest J. , Hauser B. A.
Published: July 2002

▪ Abstract  Ovules are the direct precursors of seeds and thus play central roles in sexual plant reproduction and human nutrition. Extensive classical studies have elucidated the evolutionary trends and developmental processes responsible for the current wide variety of ovule morphologies. Recently, ovules have been perceived as an attractive system for the study of genetic regulation of plant development. More than a dozen regulatory genes have now been identified through isolation of ovule mutants. Characterization of these mutants shows that some aspects of ovule development follow independent pathways, while other processes are interdependent. Some of these mutants have ovules resembling those of putative ancestors of angiosperms and may help in understanding plant evolution. Clones of several of the regulatory genes have been used to determine expression patterns and putative biochemical functions of the gene products. Newly constructed models of genetic regulation of ovule development provide a framework for interpretation of future discoveries.
PLANT THIOREDOXIN SYSTEMS REVISITED
Authors: Schürmann P. , Jacquot J.-P.
Published: July 2002

▪ Abstract  Thioredoxins, the ubiquitous small proteins with a redox active disulfide bridge, are important regulatory elements in plant metabolism. Initially recognized as regulatory proteins in the reversible light activation of key photosynthetic enzymes, they have subsequently been found in the cytoplasm and in mitochondria. The various plant thioredoxins are different in structure and function. Depending on their intracellular location they are reduced enzymatically by an NADP-dependent or by a ferredoxin (light)-dependent reductase and transmit the regulatory signal to selected target enzymes through disulfide/dithiol interchange reactions. In this review we summarize recent developments that have provided new insights into the structures of several components and into the mechanism of action of the thioredoxin systems in plants.
BIOSYNTHESIS OF ASCORBIC ACID IN PLANTS: A Renaissance
Authors: Smirnoff Nicholas , Conklin Patricia L , Loewus Frank A
Published: July 2002

▪ Abstract  The structure of the familiar antioxidant L-ascorbic acid (vitamin C) was described in 1933 yet remarkably, its biosynthesis in plants remained elusive until only recently. It became clear from radioisotopic labeling studies in the 1950s that plant ascorbic acid biosynthesis does not proceed in toto via a route similar to that in mammals. The description in 1996 of an Arabidopsis thaliana mutant deficient in ascorbic acid prompted renewed research effort in this area, and subsequently in 1998 a new pathway was discovered that is backed by strong biochemical and molecular genetic evidence. This pathway proceeds through the intermediates GDP-D-mannose, L-galactose, and L-galactono-1,4-lactone. Much research has focused on the properties of the terminal enzyme responsible for conversion of the aldonolactone to ascorbate, and on related enzymes in both mammals and fungi. Two of the plant biosynthetic genes have been studied at the molecular level and additional ascorbate-deficient A. thaliana mutants may hold the key to other proteins involved in plant ascorbate metabolism. An analysis of the biosynthesis of ascorbate and its analogues in algae and fungi as well as the study of alternative proposed pathways should broaden our understanding of ascorbate metabolism in plants. With a biosynthetic pathway in hand, research on areas such as the control of ascorbate biosynthesis and the physiological roles of ascorbate should progress rapidly.
LUMINOUS SUPERSOFT X-RAY SOURCES
Authors: Kahabka P. , van den Heuvel E. P. J.
Published: July 2002

Luminous supersoft X-ray sources were discovered with the Einstein observatory and have been established as an important new class of X-ray binaries on the basis of observations with the Roentgen Satellite (ROSAT). They have extremely soft spectra (equivalent blackbody temperatures of ∼15–80 eV) and are highly luminous (bolometric luminosities of 1036–1038erg s−1). Correcting for the heavy extinction of soft X rays by interstellar neutral hydrogen, their numbers in the disks of ordinary spiral galaxies like our own and M31 are estimated to be of the order of 103. Their observed characteristics are consistent with those of white dwarfs, which are steadily or cyclically burning hydrogen-rich matter accreted onto the surface at a rate of order 10−7[Formula: see text] year−1. The required high accretion rates can be supplied by mass transfer on a thermal time scale (106–107years) from close companion stars that are more massive than the white dwarf accretor, typically 1.3–2.5 [Formula: see text]. Steady burning can also occur in a post-nova stage, but for shorter time scales, and it has been observed in a few classical novae and symbiotic novae. A few supersoft sources have been found to be recurrent transients. They are possibly connected with very massive white dwarfs accreting at high rates. Luminous supersoft sources may make a considerable contribution to the Type Ia supernova rate in spiral and irregular galaxies.
PROBING PLANETARY ATMOSPHERES WITH STELLAR OCCULTATIONS
Authors: Elliot J. L. , Olkin C. B.
Published: July 2002

▪ Abstract  Earth-based stellar occultations probe the temperature, pressure, and number-density profiles of planetary atmospheres in the microbar range with a vertical resolution of a few kilometers. Depending on the occultation data available for a given body and other information, the technique also allows determination of local density variations, extinction by aerosols and molecules, rotation period and zonal winds, atmospheric composition, and the temporal and spatial variability of an atmosphere. A brief quantitative description of the interaction of starlight with a planetary atmosphere is presented, and observational techniques are discussed. Observational results through 1995 are presented for Venus, Mars, Jupiter, Saturn, Titan, Neptune, Triton, Pluto, and Charon.
SATELLITE ALTIMETRY, THE MARINE GEOID, AND THE OCEANIC GENERAL CIRCULATION
Authors: Wunsch Carl , Stammer Detlef
Published: July 2002

▪ Abstract  For technical reasons, the general circulation of the ocean has historically been treated as a steady, laminar flow field. The recent availability of extremely high-accuracy and high-precision satellite altimetry has provided a graphic demonstration that the ocean is actually a rapidly time-evolving turbulent flow field. To render the observations quantitatively useful for oceanographic purposes has required order of magnitude improvements in a number of fields, including orbit dynamics, gravity field estimation, and atmospheric variability. With five years of very high-quality data now available, the nature of oceanic variability on all space and time scales is emerging, including new findings about such diverse and important phenomena as mixing coefficients, the frequency/wavenumber spectrum, and turbulent cascades. Because the surface elevation is both a cause and consequence of motions deep within the water column, oceanographers soon will be able to provide general circulation numerical models tested against and then combined with the altimeter data. These will be complete three-dimensional time-evolving estimates of the ocean circulation, permitting greatly improved estimates of oceanic heat, carbon, and other property fluxes.
Modern Imaging Using Seismic Reflection Data
Authors: Fehler Michael C. , Huang Lianjie
Published: July 2002

▪ Abstract  Imaging using seismic reflection data has undergone tremendous advances over the past few years. The advances have been fostered in part by the availability of faster computers that have made more reliable algorithms for migration imaging feasible. The conventional approach to migration imaging, ray-based Kirchhoff migration, has been improved by the use of multiple-valued traveltime tables, ray amplitudes, and ray phases that can be calculated from various ray-tracing implementations. Wave-equation imaging, based on implementations of solutions of the wave equation, one-way wave equation, and approximations to the Lippmann-Schwinger equation, has become tractable. Wave-equation methods take account of wave phenomena such as focusing, defocusing, and diffraction that are important in many geological environments where imaging is used for petroleum exploration. There have also been applications of various types of migration imaging in basic studies of Earth structure. Such studies have been made to investigate deep Earth structure and large-scale lithospheric structure using waveforms from teleseisms as sources.
Evolutionary Genetics and Genetic Variation of Haplodiploids and X-Linked Genes
Authors: Hedrick Philip W. , Parker Joel D.
Published: July 2002

The evolutionary genetics of haplodiploids and X-linked genes share many features and are different from diploid (autosomal) genes in many respects. For example, the conditions for a stable polymorphism, the amount of genetic load, and the effective population size are all expected to be quite different between haplodiploids or X-linked genes and diploids. From experimental data, the genetic load for X-linked genes is much less than autosomal genes and appears less for haplodiploids than for diploids. The observed amount of molecular variation for haplodiploids is much less than that for diploids, even more so than predicted from the differences in effective population size. Extensive recently published data suggest that the differences in variation for X-linked and autosomal genes for Drosophila, mice, and humans are consistent with the differences predicted theoretically based on the relative effective population sizes.
VERTEBRATE HERBIVORES IN MARINE AND TERRESTRIAL ENVIRONMENTS: A Nutritional Ecology Perspective
Authors: Choat J. H. , Clements K. D.
Published: July 2002

▪ Abstract  The study of digestive physiology provides a framework for analyzing food resources, feeding patterns, and evolutionary trends in vertebrate herbivores. Most of the research in this field, nutritional ecology, has been focused on terrestrial herbivores, especially mammals. By integrating physiological, demographic, and evolutionary approaches, the study of terrestrial herbivores has generated several important hypotheses, notably on factors determining body mass. Marine vertebrate herbivores are abundant and locally diverse, but with the exception of reptiles and mammals, we lack information on digestive physiology and processing of plant foods, the key element in terrestrial studies. This review provides a foundation for a nutritional ecology of marine vertebrate herbivores, especially teleost fish, by summarizing the available information on their digestive physiology and identifying research priorities in the field.