bluuebunny/crossref_metadata_2025 huggingface dataset:
A framework for testing safety and effective computability of extended datalog
Authors: Krishnamurthy Ravi , Ramakrishnan Raghu , Shmueli Oded
Published: November 2005

This paper presents a methodology for testing a general logic program containing function symbols and built-in predicates for
safety
and
effective computability
. Safety is the property that the set of answers for a given query is finite. A related issues is whether the evaluation strategy can effectively compute all answers and terminate. We consider these problems under the assumption that queries are evaluated using a bottom-up fixpoint computation. We also approximate the use of function symbols by considering Datalog programs with infinite base relations over which
finiteness constraints
and
monotonicity constraints
are considered. One of the main results of this paper is a recursive algorithm,
check_clique
, to test the safety and effective computability of predicates in arbitrarily complex cliques. This algorithm takes certain procedures as parameters, and its applicability can be strengthened by making these procedures more sophisticated. We specify the properties required of these procedures precisely, and present a formal proof of correctness for algorithm
check_clique
. This work provides a framework for testing safety and effective computability of recursive programs, and is based on a clique by clique analysis. The results reported here form the basis of the safety testing for the LDL language, being implemented at MCC.
Twin grid files: space optimizing access schemes
Authors: Hutflesz Andreas , Six Hans-Werner , Widmayer Peter
Published: November 2005

Storage access schemes for points, supporting spatial searching, usually suffer from an undesirably low storage space utilization. We show how a given set of points can be distributed among two grid files in such a way that storage space utilization is optimal. The optimal twin grid file can be built practically as fast as a standard grid file, i.e., the storage space optimality is obtained at almost no extra cost. We compare the performances of the standard grid file, the optimal static twin grid file, and an efficient dynamic twin grid file, where insertions and deletions trigger the redistribution of points among the two grid files. Twin grid files utilize storage space at roughly 90%, as compared with the 69% of the standard grid file. Typical range queries - the most important spatial search operations - can be answered in twin grid files at least as fast as in the standard grid file.
Hashing practice: analysis of hashing and universal hashing
Authors: Ramakrishna M. V.
Published: November 2005

Much of the literature on hashing deals with overflow handling (collision resolution) techniques and its analysis. What does all the analytical results mean in practice and how can they be achieved with practical files? This paper considers the problem of achieving analytical performance of hashing techniques in practice with reference to successful search lengths, unsuccessful search lengths and the expected worst case performance (expected length of the longest probe sequence). There has been no previous attempt to explicitly link the analytical results to performance of real life files. Also, the previously reported experimental results deal mostly with successful search lengths. We show why the well known division method performs “well” under a specific model of selecting the test file. We formulate and justify an hypothesis that by choosing functions from a particular class of hashing functions, the analytical performance can be obtained in practice on real life files. Experimental results presented strongly support our hypothesis. Several interesting problems arising are mentioned in conclusion.
Resolving the tension between integrity and security using a theorem prover
Authors: Mazumdar Subhasish , Stemple David , Sheard Tim
Published: November 2005

Some information in databases and knowledge bases often needs to be protected from disclosure to certain users. Traditional solutions involving multi-level mechanisms are threatened by the user's ability to infer higher level information from the semantics of the application. We concentrate on the revelation of secrets through a user running transactions in the presence of database integrity constraints. We develop a method of specifying secrets formally that not only exposes a useful structure and equivalence among secrets but also allows a theorem prover to detect certain security lapses during transaction compilation time.
A transaction logic for database specification
Authors: Qian Xiaolei , Waldinger Richard
Published: November 2005

We introduce a logical formalism for the specification of the dynamic behavior of databases. The evolution of databases is characterized by both the dynamic integrity constraints which describe the properties of state transitions and the transactions whose executions lead to state transitions. Our formalism is based on a variant of first-order situational logic in which the states of computations are explicit objects. Integrity constraints and transactions are uniformly specifiable as expressions in our language. We also point out the application of the formalism to the verification and synthesis of transactions.
A generalized model for a relational temporal database
Authors: Gadia Shashi K. , Yeung Chuen-Sing
Published: November 2005

We propose a generalized relational model for a temporal database which allows time stamping with respect to a Boolean algebra of multidimensional time stamps. The interplay between the various temporal dimensions is symmetric. As an application, a two dimensional model which allows objects with real world and transaction oriented time stamps is discussed. The two dimensional model can be used to query the past states of the database. It can also be used to give a precise classification of the errors and updates in a database, and is a promising approach for querying these errors and updates.
A DBMS for large design automation databases
Authors: Haynie M.
Published: November 2005

Large capacity Design Automation (CAD/CAM) database management systems require special capabilities over and above what commercial DBMSs or small workstation-based CAD/CAM systems provide. This paper describes one such system, Tacoma, used at Amdahl Corporation for the storage and retrieval of LSI and VLSI mainframe computer designs Tacoma is based on the relational model with additional object-oriented database features.
Performance analysis and fundamental performance tradeoffs for CLV optical disks
Authors: Christodoulakis Stavros , Ford Daniel Alexander
Published: November 2005

CLV type optical disks is a very large and important class of optical disk technology, of which CD-ROM disks form a subclass.

In this paper we present a model of retrieval from CLV optical disks. We then provide exact and approximate results analyzing the retrieval performance from them. Our analysis takes into account disks with and without a mirror in the read mechanism, small objects completely placed within block boundaries, placement that allows block boundary crossing, as well as very large objects (such as documents) placed within files.

In the second part of the paper we describe some fundamental implications of physical data base design for data bases stored on CLV optical disks. We show that very significant performance gains may be realized by appropriate design.
Managing knowledge about information system evolution
Authors: Jarke Matthias , Rose Thomas
Published: November 2005

This paper describes the design and initial prototype implementation of a knowledge base management system (KBMS) for controlling database software development and maintenance. The KBMS employs a version of the conceptual modelling language CML to represent knowledge about the tool-aided development process of an information system from requirements analysis to conceptual design to implementation, together with the relationship of these system components to the real-world environment in which the information system is intended to function. A decision-centered documentation methodology facilitates communication across time and among multiple developers (and possibly users), thus enabling improved maintenance support.
Compiling separable recursions
Authors: Naughton Jeffrey F.
Published: November 2005

In this paper we consider evaluating queries on relations defined by a combination of recursive rules. We first define separable recursions. We then give a specialized algorithm for evaluating selections on separable recursions. Like the Generalized Magic Sets and Generalized Counting algorithms, thus algorithm uses selection constants to avoid examining irrelevant portions of the database, however, on some simple recursions this algorithm is
Ο
(
n
), whereas Generalized Magic Sets is Ω(
n
2
) and Generalized Counting is Ω(2

n

)
Classification of recursive formulas in deductive databases
Authors: Youn Cheong , Henschen Lawrence J. , Han Jiawei
Published: November 2005

In this paper, we present results on the classification of linear recursive formulas in deductive databases and apply those results to the compilation and optimization of recursive queries. We also introduce compiled formulas and query evaluation plans for a representative query for each of these classes.

To explain general recursive formulas, we use a graph model that shows the connectivity between variables. The connecticity between variables is the most critical part in processing recursive formulas. We demonstrate that based on such a graph model all the linear recursive formulas can be classified into several classes and each class shares some common characteristics in compilation and query processing. The compiled formulas and the corresponding query evaluation plans can be derived based on the study of the compilation of each class.
Distributed processing of logic programs
Authors: Wolfson Ouri , Silberschatz Avi
Published: November 2005

This paper is concerned with the issue of parallel evaluation of logic programs. To address this issue we define a new concept of
predicate decomposability
. If a predicate is decomposable, it means that the load of evaluating it can be divided among a number of processors, without a need for communication among them. This in turn results in a very significant speed-up of the evaluation process.

We completely characterize three classes of single rule programs (sirups) with respect to decomposability nonrecursive, linear, and simple chain programs. All three classes were studied previously in various contexts. We establish that nonrecursive programs are decomposable, whereas for the other two classes we determine which ones are, and which ones are not decomposable. We also establish two sufficient conditions for sirup decomposability.
A performance analysis of the gamma database machine
Authors: DeWitt D. J. , Ghanderaizadeh S. , Schneider D.
Published: November 2005

This paper presents the results of an initial performance evaluation of the Gamma database machine. In our experiments we measured the effect of relation size and indices on response time for selection, join, and aggregation queries, and single-tuple updates. A Teradata DBC/1012 database machine of similar size is used as a basis for interpreting the results obtained. We also analyze the performance of Gemma relative to the number of processors employed and study the impact of varying the memory size and disk page size on the execution time of a variety of selection and join queries. We analyze and interpret the results of these experiments based on our understanding of the system hardware and software, and conclude with an assessment of the strengths and weaknesses of Gamma.
Commitment in a partitioned distributed database
Authors: Ramarao K. V. S.
Published: November 2005

Network partition is among the hardest failure types in a distributed system even if all processors and links are offail-stoptype. We address the transaction commitment problem in a partitioned distributed database. It is assumed that partitions are detectable. The approach taken is conservative - that is, the same transaction cannot be committed by one site and aborted by another.

A new and very general formal model of protocols operating in a partitioned system is introduced and protocols more efficient than the existing ones are constructed.
Implementing large production systems in a DBMS environment: concepts and algorithms
Authors: Sellis T. , Lin C. C. , Raschid L.
Published: November 2005

It has been widely recognized that many future database applications, including engineering processes, manufacturing and communications, will require some kind of rule based reasoning. In this paper we study methods for storing and manipulating large rule bases using relational database management systems. First, we provide a matching algorithm which can be used to efficiently identify applicable rules. The second contribution of this paper, is our proposal for concurrent execution strategies which surpass, in terms of performance, the sequential OPS5 execution algorithm. The proposed method is fully parallelizable, which makes its use even more attractive, as it can be used in parallel computing environments.
A secure hierarchical model for sensor network
Authors: Tubaishat Malik , Yin Jian , Panja Biswajit , Madria Sanjay
Published: November 2005

In a distributed sensor network, large number of sensors deployed which communicate among themselves to self-organize a wireless ad hoc network. We propose an energy-efficient level-based hierarchical system. We compromise between the energy consumption and shortest path route by utilizing number of neighbors (NBR) of a sensor and its level in the hierarchical clustering. In addition, we design a Secure Routing Protocol for Sensor Networks (
SRPSN
) to safeguard the data packet passing on the sensor networks under different types of attacks. We build the secure route from the source node to sink node. The sink node is guaranteed to receive correct information using our
SRPSN
. We also propose a group key management scheme, which contains group communication policies, group membership requirements and an algorithm for generating a distributed group key for secure communication.
Robust key establishment in sensor networks
Authors: Wang Yongge
Published: November 2005

Secure communication guaranteeing reliability, authenticity, and privacy in sensor networks with active adversaries is a challenging research problem since asymmetric key cryptosystems are not suitable for sensor nodes with limited computation and communication capabilities. In most proposed secure communication protocols, sensor nodes need to contact the base station to get a session key first if two sensor nodes want to establish a secure communication channel (e.g., SPINS). In several environments, this may be impractical. In this paper, we study key agreement protocols for which two sensor nodes (who do not necessarily have a shared key from the key predistribution phase) could establish a secure communication channel against active adversaries (e.g., denial of service attacks) without the involvement of the base station.
Team communications among autonomous sensor swarms
Authors: Gerla Mario , Yi Yunjung
Published: November 2005

In this paper, we consider team (swarm) of unmanned vehicles (UVs) equipped with various sensors (videos, chemicals, etc). Those swarms need efficient communication to feed sensed data, communicate data to other swarms, to navigate and, more generally, to carry out complex mission autonomously. We focus on a particular aspect of mission oriented communications, namely,
team multicast
. In team multicast, the multicast group does not consist of individual members, rather, of teams. In our case, the teams may consist of special UVs that have been established to launch a search and rescue mission. Simulation results illustrate the performance benefits of the team multicast solution as compared with more traditional multicast approaches.
Replica allocation for correlated data items in ad hoc sensor networks
Authors: Hara Takahiro , Murakami Norishige , Nishio Shojiro
Published: November 2005

To improve data accessibility in ad hoc networks, in our previous work we proposed three methods of replicating data items by considering the data access frequencies from mobile nodes to each data item and the network topology. In this paper, we extend our previously proposed methods to consider the correlation among data items. Under these extended methods, the data priority of each data item is de-fined based on the correlation among data items, and data items are replicated at mobile nodes with the data priority. We employ simulations to show that the extended methods are more efficient than the original ones.
An initial study of overheads of eddies
Authors: Deshpande Amol
Published: November 2005

An eddy [2] is a highly adaptive query processing operator that continuously reoptimizes a query in response to changing runtime conditions. It does this by treating query processing as
routing
of tuples through
operators
and making per-tuple routing decisions. The benefits of such adaptivity can be significant, especially in highly dynamic environments such as data streams, sensor query processing, web querying, etc. Various parties have asserted that the cost of making per-tuple routing decisions is prohibitive. We have implemented eddies in the PostgreSQL open source database system [1] in the context of the TelegraphCQ project. In this paper, we present an "apples-to-apples" comparison of PostgreSQL query processing overhead with and without eddies. Our results show that with some minor tuning, the overhead of the eddy mechanism is negligible.
Toward an ontology-enhanced information filtering agent
Authors: Sim Kwang Mong
Published: November 2005

Whereas search engines assist users in locating initial information sources, often an overwhelmingly large number of
ULRs
is returned, and the task of browsing websites rests heavily on users. The contribution of this work is developing an
information filtering agent (IFA)
that assists users in identifying out-of-context web pages and rating the relevance of web pages. An
IFA
determines the relevance of web pages by adopting three heuristics: (i) detecting
evidence phrases (EP)
constructed from WORDNET's ontology, (ii) counting the
frequencies
of
EP
and (iii) considering the
nearness
among keywords. Favorable experimental results show that the
IFA's
ratings of web pages are generally close to human ratings in many instances. The strength and weaknesses of the
IFA
are also discussed.
Science of design for information systems
Authors: ACM SIGMOD Record staff
Published: November 2005

The Workshop on Science of Design for Information Systems (SDIS2003) was held in Seattle, September 16 and 17, 2003. It was funded through a grant from the National Science Foundation
2
, with the goal of assessing the state-of-the-art in information systems design and suggesting promising directions for future research and development in this critical area.This short report is intended to provide an overview of the workshop report for the SIGMOD audience. In summary, we believe that there is a need to develop a new set of methodologies for information system design that cover advanced aspects of such systems. In particular, we are interested in techniques that offer guidance in the design of information systems that integrate data from multiple sources, handle dynamic aspects of the system (e.g., rapidly changing data, tracking provenance, version management), include aspects influenced by data location (e.g., cached objects and queries, peer-to-peer data sharing), model process-oriented issues (e.g., workflows, web-services), and account for the security and privacy of the data. AB@The interested reader can find a full version of this report at the workshop website, www.cs.wisc.edu/sdis03.
Editing requirements for data base applications and their implementation on the INDY backend kernel
Authors: Otis Allen J. , Copeland George P.
Published: November 2005

An extrapolation of user and hardware cost trends indicate that future systems should provide more complete functionality, simplicity of use, and reliability by increasing the amount of hardware present in the system. For data base systems, this can be done by providing very high level data languages and by implementing them directly in hardware. These goals are realized with a simple hardware arrangement called INDY, which uses inexpensive memory technologies (such as charge coupled devices, magnetic bubbles, or discs). This paper first discusses the data definition and editing requirements of data languages. Then the implementation of these requirements on the INDY backend kernel is described. Finally, a comparison is made of the various memory technologies for suitability to INDY.
Semantic paging on intelligent discs
Authors: Lipovski G. Jack
Published: November 2005

In order to apply Artificial Intelligence techniques like inferencing to large (10
9
-10
12
bit) data bases, an intelligent secondary memory is proposed that is capable of extracting a subgraph from a graph stored in it for further processing in a conventional or special purpose computer. The "pointer transfer" technique developed for CASSM is used to efficiently mark and output a subgraph stored in one file, and a simple technique is proposed to link parts of the subgraph stored on different files. Besides proposing a useful secondary memory system for applying Artificial Intelligence techniques to large data bases, this paper attacks one of the most difficult problems in distributed data base systems, which is the generation of "homomorphic query fragments" that automatically carry the query from one file to other files needed to resolve the query.
A specialized computer architecture for text retrieval
Authors: Roberts David C.
Published: November 2005

This paper describes a specialized computer architecture for text retrieval that provides a wide range of query capabilities, without the use of indexes of the material retrieved. A distributed approach is employed, with direct search processors. Each search processor is closely associated with one or more disk drives that store the data to be searched and each consists of a comparator for matching query terms, logic elements to combine query terms, a disk controller and a control minicomputer.The key element of the architecture is the comparator, which can store over 64,000 characters of query terms and compare all of these terms simultaneously with data arriving from a disk continuously at more than one million bytes per second. Exact match, partical match, numeric comparison and context limitation are among the capabilities provided. The comparator is implemented as three similar universal finite-state automata, with special features to facilitate text retrieval and reduce hardware costs.A breadboard version of the system with one searcher is operational and has undergone detailed evaluation. A prototype system with two searchers is being implemented and will be placed into regularly scheduled use.
A hierarchical controller for concurrent accessing of distributed databases
Authors: Gouda Mohamed G.
Published: November 2005

An access controller for a distributed database is a (central or distributed) structure which routes access requests to the different components of the database. Such a controller is also supposed to resolve the conflicts between concurrent requests, if any, such that deadlock situations never arise.In this paper, some architectures for distributed access controllers of distributed databases are investigated. In particular, three controllers with hierarchical architectures are considered. The controllers are evaluated based on three criteria: (i) freedom of deadlocks, (ii) robustness, and (iii) parallelism. The third criterion implies that the added redundancy to increase the controller robustness against failure conditions should also contribute to the amount of achieved parallelism during the no-failure periods. We then define a controller architecture which satisfies all the three criteria.
Madman machine
Authors: Hutchison J. S. , Roman W. G.
Published: November 2005

A back-end data base machine is discussed in which the back-end is closely coupled to the host system as an intelligent I/O device. The design of the hardware and software is such that the data base disks can be on either the host or back-end computers. The design is motivated by memory size considerations on mini-computer systems and also by cost considerations of large disks. The implementations of such a system on PDP-11s is discussed.
Bubbles for relational database
Authors: Chang Hsu
Published: November 2005

The mechanical disk storage is limited by long initial delay, few inputs/outputs, and serial access, thus necessitating large complex programs in existing database systems in order to map the user's view into the physical storage and to provide different access paths in response to different queries. Bubble devices are capable of set-oriented processing and associative addressing architecture. This paper presents concepts on data structure, storage structure, and access methods for bubble implementation of relational database.
An automated technique for designing optimal performance IMS data bases
Authors: Roach Vincent
Published: November 2005

There exists great potential for IMS performance improvement through selection among design alternatives. One such area is data base design, which covers a number of sensitive variables. The only feasible way to evaluate the effects of varying combinations of values for these variables, is via simulation. Many of the drawbacks of simulation have been alleviated by the creation of a comprehensive, validated model of IMS, which feeds mostly on pre-existing data. This model allows the evaluation of many alternatives, including data base design. A case study has shown the great potential which may be realized through use of this tool.
Bringing data base technology to the programmer
Authors: Honig William L.
Published: November 2005

This paper reports work toward melding some ideas from data base management with currently popular views of structured programming. The basic idea is to allow all data structures used inside programs (instead of just those in an external data base) to be described at multiple conceptual levels by a separate definition. This approach brings to programmers the benefits of data independence and also allows structured programming to have its hitherto unrealized full effect on data.
A graduate course in database management
Authors: Purdy J. Gerry
Published: November 2005

Database management is a new and fast growing discipline within computer science. Curriculum 68 did not include database management in its recommended courses. With the advent of large direct access secondary storage devices to hold large volumes of information referred to as a database and with the need to manage that storage efficiently and conveniently, there has developed the computer science discipline of database management. This paper describes a course in database management, including a course catalog overview, course outline, and bibliography. This paper could serve as a guideline for future ACM Curriculum Committee on Computer Science recommendation in database management.
Customized segment synthesis
Authors: Odell James J.
Published: November 2005

Segment design is a process which must be exercised by every data-base designer. This paper presents an easily authomated method of designing segments taking into account system-usage factors. The segments resulting from this algorithm are a subset of all possible synthesis solutions; but they are those results which may be of more importance to the D.B. designer.
Business
Authors: Miller Peter B. , Tetelbaum Sergey , Webb Kincade N.
Published: November 2005

BUSINESS is a new application development language intended to answer the needs of a rapidly growing user community - the end-user. The underlying computational model is the paper office. BUSINESS instructions manipulate objects within this model in ways analogous to human office workers. The syntax of BUSINESS closely approximates a subset of English. Standard programming functions are embodied in the language in ways that seem natural to first time computer users. For example, to open a file for exclusive read/write access one 'Pulls' a 'Folder' (containing 'Forms' and 'Documents') from a 'Drawer' in a 'File Cabinet'. In the computational model, the Folder is seen to actually move from the Drawer to a 'Desk' belonging to an 'Aide'(the "worker" inside the computer).To support the construction of reliable software within this model, BUSINESS contains a rich repertoire of structured control constructs: execute (procedures), do (routines), go through (a set of objects), test and select one (from a set of 'if - then' instructions). Base data types include: whole numbers, decimal numbers, money, dates, times and characters. The set of operators and tests within BUSINESS support a complete range of data manipulations and logical decisions. Data structures include Fillins (collections of Fields) and Tables (having Entries at Row/Column intersections). Permanent data is organized by Form (collections of Fillins and Tables).
Implementation of a time expert in a data base system
Authors: Overmyer Ricky , Stonebraker Michael
Published: November 2005

This paper reports on the design and implementation of a time expert for a relational data base system. It demonstrates that a sophisticated expert can be written easily and cause minimal performance degradation. As a result, extending a data base system to support user defined data types is an easy operation.
A formal definition of the relational model
Authors: Date C. J.
Published: November 2005

The relational model of data, originally introduced by Codd in [1], has three components: (1) a set of objects (relations, domains, etc.); (2) a set of operators (union, project, etc.); (3) a set of general integrity rules. The purpose of this paper is to provide a formal definition of each of these three components.
A precise definition of basic relational notions and of the relational algebra
Authors: Pirotte Alain
Published: November 2005

This paper presents a precise definition of basic relational notions as well as a precise and general definition of the relational algebra. The paper also illustrates a method for developing semi-formal definitions of data models. A nearly formal definition of relations with unordered attributes is given, and algebraic operations are described as operating on and producing relations thus defined. The definition of algebric operations contains, as a special case, the "classical" definition of the algebra (see e.g. [CODD72]). But, in addition, several operations are generalized. The closure of the algebra is characterized precisely, with the help of an operation for renaming relation attributes.
Deadlock detection is cheap
Authors: Agrawal Rakesh , Carey Michael J. , DeWitt David J.
Published: November 2005

Deadlock detection is usually considered to be expensive, and timeouts or deadlock prevention techniques are usually resorted to as a result, which many times causes unnecessary transaction restarts. In this paper, we show that under certain reasonable assumptions, deadlocks can be detected very cheaply.
An informal approach to formal specifications
Authors: Furtado A. L.
Published: November 2005

An attempt is made to help bridging the gap between theoretical research and the real practice of data base specification. Some fundamental problems that must be addressed are described and a number of formalisms that propose to attack them are overviewed. The case pro and against the use of formal specifications is presented.
Research issues in database specification
Authors: Brodie Michael L.
Published: November 2005

This paper summarizes discussions of a panel on "Type Specifications and Databases" at VLDB in Mexico City. Panel members are listed at the end of the paper.Significant advances have been achieved in software engineering and programming language research in the development of specification techniques. There are important consequences for design, redesign, precision, and analysis of software. The importance of this work to database applications, and indeed data models and data languages, is now becoming apparent. However, specific database issues (e.g., constraints, complex data relationships, shared data, data independence) alter the specification problem as encountered in programming languages. The summary emphasizes the importance of (precise) specification in the database context and relates recent results in both programming languages and databases. It also lists outstanding theoretical problems and the relationship of advances in specification research to the development of semantic data models and high level languages for databases.
Implementation of data abstraction in the relational database system INGRES
Authors: Ong James , Fogg Dennis , Stonebraker Michael
Published: November 2005

This paper discusses the design and implementation of an
abstract data type (ADT) facility
which was added to the INGRES database manager. Our implementation of ADTs allows a user to register ADTs and ADT operators with the run-time database manager, declare column values of relations to be instances of ADTs, and formulate queries containing references to ADTs and ADT operators. The user view, implementation, performance, and possible extensions to this new facility are described.
A straightforward formalization of the relational model
Authors: Niemi Timo , Järvelin Kalervo
Published: November 2005

There has been a lot of recent interest in the formalization of the relational data model (RDM). Many approaches may be characterized as ones oriented mainly towards declaring the components of the RDM and their interrelationships. Other approaches provide a tool for manipulating the components of RDM so that research topics on the model can be specified exactly. The latter approaches are based on formal specification methods such as denotational semantics or abstract data types. Some in the data base community experience them quite complex and cumbersome.The goal of the approach of this paper is of the latter kind. However, special attention is being paid to avoid the complexity of the formal specification methods because our notations and definitions are based on set theory. We attempt to provide an exact, convenient and general tool for specifications and proofs concerning various topics like relational query languages, query optimization, relational data base restructuring, data base design, etc.
Distributing a database for parallel processing is NP-hard
Authors: Du H. C.
Published: November 2005

In a database the response time to a query can be reduced if certain concurrent operations are provided. In order to maximize the degree of concurrency, data has to be carefully allocated. The complexities of the following two problems are studied in this paper: one is to allocate a database onto a multiple-disk system which maximizes the disk access concurrency; the other one is to allocate a database over a network which minimize the number of nodes being used and a complete parallel searching is possible for a set of queries. Both are shown to be NP-hard (computational intractable) problems.
A method for concurrency control in distributed DBMSs
Authors: Halici Ugur , Dogac Asuman
Published: November 2005

In this paper, a method for concurrency control in distributed DBMSs, called Permission Test Method is proposed. The PT method satisfies the basic requirements for concurrency control, that is, it executes the transactions in a serializable order, deadlocks do not appear and indefinite postponment is prevented by the method. In PT method, transactions, which are permitted to run, are not aborted unless a related site failure occurs. Furthermore, the complexity analysis indicates that the algorithm will work in a reasonable amount of time. The PT method provides more concurrency than the Basic Timestamp Ordering and Two-Phase Locking techniques.
Supporting maybe algebra in the Associative Search Language Machine (ASLM)
Authors: Miller L. L. , Hurson A. R.
Published: November 2005

Changes in the user population continues the trend to more simplicity for the user and increased sophistication of the computer systems. In addition, advances in data storage technology have enforced the growth and creation of incomplete data files. A growing number of users require information from the database which cannot be obtained through the operators found in traditional query languages. Such needs have increased the expectation that a system should be able to assist the user in gathering and interpreting the appropriate data. The recent discussion of null values and maybe algebra is an attempt in this direction. However, the current literature has not addressed the practical issues of such theoretical concepts. This presentation examines the inclusion of the maybe algebra operators in a database machine. In addition, modifications designed to increase the time and space efficiency of the maybe algebra operators as well as the quality of the results are discussed.
Compartmental distribution of amino acids during hemodialysis-induced hypoaminoacidemia
Authors: Børsheim Elisabet , Kobayashi Hisamine , Traber Daniel L. , Wolfe Robert R.
Published: November 2005

The intracellular concentrations of essential amino acids (EAA) in muscle are maintained relatively constant under a variety of conditions. However, the effect of a decrease in blood amino acid concentrations on intracellular concentrations is not clear. Similarly, the relation between intracellular and interstitial concentrations has not been determined in this circumstance. Thus the aim of this study was to determine the effect of hypoaminoacidemia on intracellular, interstitial, and plasma concentrations of EAA and the mechanisms responsible for the respective changes. Twelve normal pigs were investigated before and during 120 min of hemodialysis by use of stable-isotope tracer methodology, microdialysis technique, and muscle biopsies. During hemodialysis, there was a decrease in the interstitial fluid concentrations of phenylalanine, leucine, alanine, and lysine that corresponded to their decrease in plasma concentration. Nonetheless, the intracellular concentrations of these amino acids were maintained at the basal levels throughout the entire period due principally to a reduction in the rate of incorporation of amino acids into protein that was approximately equivalent to the decrease in uptake from the plasma. In conclusion, intracellular concentrations of amino acids are regulated to maintain relatively constant values, even when plasma and interstitial concentrations fall as a consequence of hemodialysis.
The mass, but not the frequency, of insulin secretory bursts in isolated human islets is entrained by oscillatory glucose exposure
Authors: Ritzel R. A. , Veldhuis J. D. , Butler P. C.
Published: November 2005

Insulin is secreted in discrete insulin secretory bursts. Regulation of insulin release is accomplished almost exclusively by modulation of insulin pulse mass, whereas the insulin pulse interval remains stable at ∼4 min. It has been reported that in vivo insulin pulses can be entrained to a pulse interval of ∼10 min by infused glucose oscillations. If oscillations in glucose concentration play an important role in the regulation of pulsatile insulin secretion, abnormal or absent glucose oscillations, which have been described in type 2 diabetes, might contribute to the defective insulin secretion. Using perifused human islets exposed to oscillatory vs. constant glucose, we questioned 1) whether the interval of insulin pulses released by human islets is entrained to infused glucose oscillations and 2) whether the exposure of islets to oscillating vs. constant glucose confers an increased signal for insulin secretion. We report that oscillatory glucose exposure does not entrain insulin pulse frequency, but it amplifies the mass of insulin secretory bursts that coincide with glucose oscillations ( P < 0.001). Dose-response analyses showed that the mode of glucose drive does not influence total insulin secretion ( P = not significant). The apparent entrainment of pulsatile insulin to infused glucose oscillations in nondiabetic humans in vivo might reflect the amplification of underlying insulin secretory bursts that are detected as entrained pulses at the peripheral sampling site, but without changes in the underlying pacemaker activity.
PPARδ activator GW-501516 has no acute effect on glucose transport in skeletal muscle
Authors: Terada Shin , Wicke Scott , Holloszy John O. , Han Dong-Ho
Published: November 2005

It has been reported that treatment of cultured human skeletal muscle myotubes with the peroxisome proliferator-activated receptor-δ (PPARδ) activator GW-501516 directly stimulates glucose transport and enhances insulin action. Cultured myotubes are minimally responsive to insulin stimulation of glucose transport and are not a good model for studying skeletal muscle glucose transport. The purpose of this study was to evaluate the effect of GW-501516 on glucose transport to determine whether the findings on cultured myotubes have relevance to skeletal muscle. Rat epitrochlearis and soleus muscles were treated for 6 h with 10, 100, or 500 nM GW-501516, followed by measurement of 2-deoxyglucose uptake. GW-501516 had no effect on glucose uptake. There was no effect on insulin sensitivity or responsiveness. Also, in contrast to findings on myotubes, treatment of muscles with GW-501516 did not result in increased phosphorylation or increased expression of AMP-activated protein kinase (AMPK) or p38 mitogen-activated protein kinase (MAPK). Treatment of epitrochlearis muscles with GW-501516 for 24 h induced a threefold increase in uncoupling protein-3 mRNA, providing evidence that the GW-501516 compound that we used gets into and is active in skeletal muscle. In conclusion, our results show that, in contrast to myotubes in culture, skeletal muscle does not respond to GW-501516 with 1) an increase in AMPK or p38 MAPK phosphorylation or expression or 2) direct stimulation of glucose transport or enhanced insulin action.
Alternative splicing generates a smaller assortment of CaV2.1 transcripts in cerebellar Purkinje cells than in the cerebellum
Authors: Kanumilli Srinivasan , Tringham Elizabeth W. , Elizabeth Payne C. , Dupere Jonathan R. B. , Venkateswarlu Kanamarlapudi , Usowicz Maria M.
Published: November 2005

P/Q-type calcium channels control many calcium-driven functions in the brain. The CACNA1A gene encoding the pore-forming CaV2.1 (α1A) subunit of P/Q-type channels undergoes alternative splicing at multiple loci. This results in channel variants with different phenotypes. However, the combinatorial patterns of alternative splice events at two or more loci, and hence the diversity of CaV2.1 transcripts, are incompletely defined for specific brain regions and types of brain neurons. Using RT-PCR and splice variant-specific primers, we have identified multiple CaV2.1 transcript variants defined by different pairs of splice events in the cerebellum of adult rat. We have uncovered new splice variations between exons 28 and 34 (some of which predict a premature stop codon) and a new variation in exon 47 (which predicts a novel extended COOH-terminus). Single cell RT-PCR reveals that each individual cerebellar Purkinje neuron also expresses multiple alternative CaV2.1 transcripts, but the assortment is smaller than in the cerebellum. Two of these variants encode different extended COOH-termini which are not the same as those previously reported in Purkinje cells of the mouse. Our patch-clamp recordings show that calcium channel currents in the soma and dendrites of Purkinje cells are largely inhibited by a concentration of ω-agatoxin IVA selective for P-type over Q-type channels, suggesting that the different transcripts may form phenotypic variants of P-type calcium channels in Purkinje cells. These results expand the known diversity of CaV2.1 transcripts in cerebellar Purkinje cells, and propose the selective expression of distinct assortments of CaV2.1 transcripts in different brain neurons and species.
Involvement of the Ubiquitin-Mediated Proteolytic System in the Signaling Pathway Induced by Ceramide in Primary Astrocyte Cultures
Authors: Calatayud C.A. , Pasquini L.A. , Pasquini J.M. , Soto E.F.
Published: November 2005

The selective degradation of abnormal or short half-life proteins in eukaryotic cells proceeds through the ubiquitin-mediated proteolytic system (UbPS). The signals that tag the proteins for their ubiquitination are well known. In the present study, our aim was to investigate the relationship between the action of ceramide and the changes in the expression of certain mRNAs of the Ub pathway and in the activation of the UbPS in cultured astrocytes (ASTs). Changes in the expression of components that are known to be substrates of the UbPS and that participate in the regulation of the cell death process were also studied. Addition of different concentrations of C2 ceramide to cultured ASTs produced an increase in the expression of the Ub gene and in the gene that encodes E1, one of the enzymes involved in the ubiquitination process, without any changes on cell viability. Immunocytochemical studies showed an increase in the expression of Bcl-2 with no changes in cytochrome c. Also, there was an increase in the nuclear reactivity of NFĸB, suggesting a translocation of this factor towards the nucleus. Western blots showed a decrease in IĸB and its phosphorylated form as well as an increase in Bcl-2 with no changes in cytochrome c. All of these compounds appear to be acting as possible modulators of AST responses to C2 ceramide. Our results suggest that in AST primary cultures, C2 ceramide, at the concentrations used in this study, does not produce apoptosis. However, it induces an activation of the UbPS, probably as a consequence of an activation of phosphatases and kinases, or through the generation of reactive oxygen species, which act as triggering signals of the UbPS. The fundamental role of NFĸB and Bcl-2 as antiapoptotic factors is discussed.
Association of E-Cadherin Gene 3’-UTR C/T Polymorphism with Primary Open Angle Glaucoma
Authors: Lin Hui-Ju , Tsai Fuu-Jen , Hung Porting , Chen Wen-Chi , Chen Huey-Yi , Fan Seng-Sheen , Tsai Shih-Wei
Published: November 2005

Purpose: E-cadherin (E-CDH) is one of the most important cell surface glycoproteins involved in cell morphogenesis. In primary open angle glaucoma (POAG), the extracellular matrixes of trabecular meshwork and lamina cribrosa in the optic nerve head are out of balance. We suspected that E-CDH by way of metalloproteinases is closely related to POAG. We therefore investigated the relationship between CDH-1 gene 3′ untranslated region (3′-UTR) polymorphism and POAG patients in order to support this hypothesis. Patients and Methods: We enrolled 60 POAG patients and 103 healthy volunteers from the Department of Ophthalmology at the China Medical University Hospital, Taichung, Taiwain, ROC. None of the control subjects had a history of eye disease and all underwent the same examination as the POAG patients. PCR-based analysis of the restriction fragment length polymorphism was used to test the CDH-1 gene 3′-UTR polymorphism. All statistical analyses were performed by the χ2 test. Result: There was a significant difference in the distribution of the CDH-1 gene 3′-UTR C/T polymorphism between POAG patients and the normal controls (p <0.000). The odds ratio of the ‘C’ allele was al so significantly different between both groups (odds ratio = 5.510, 95% confidence interval = 3.171–9.574). Conclusion: CDH-1 is closely related to metalloproteinase and plays an important but not well-understood role in the onset and progression of POAG. The exact role of CDH-1 in POAG could be resolved by the posttranslated products of the gene and the protein-protein interaction of the gene products in the future.