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Full-Text Articles in Databases and Information Systems

Measurement Of The Branching Fraction For D+K-++, Balest, R.; Et Al., M. Thulasidas Jan 1994

Measurement Of The Branching Fraction For D+K-++, Balest, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the ratio of branching fractions, B(D+K-++)/(D0K-+)=2.350.160.16. Our recent measurement of scrB(D0K-+) then gives scrB(D+K-++)=(9.30.60.8)%.


Study Of The Five-Charged-Pion Decay Of The Τ Lepton, D. Gibaut, Manoj Thulasidas Jan 1994

Study Of The Five-Charged-Pion Decay Of The Τ Lepton, D. Gibaut, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The branching fractions for the five-charged-particle decays of the τ lepton have been measured in e+e− annihilations using the CLEO II detector at the Cornell Electron Storage Ring. Assuming all charged particles to be pions, the results are B(3π−2π+≥0 neutrals ντ)=(0.097±0.005±0.011)%, B(3π−2π+ντ)=(0.077±0.005 ±0.009)%, B(3π−2π+π0ντ)=(0.019±0.004±0.004)%, and B(3π−2π+2π0ντ)B(3π−2π−π0ντ) is measured for the first time by exclusive π0 reconstruction. The results are compared with the predictions from the partially conserved-axial-current and conserved-vector-current hypotheses assuming isospin invariance.


Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas Jan 1994

Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Resolving Attribute Incompatibility In Database Integration: An Evidential Reasoning Approach, Ee-Peng Lim, Shashi Shekhar Jan 1994

Resolving Attribute Incompatibility In Database Integration: An Evidential Reasoning Approach, Ee-Peng Lim, Shashi Shekhar

Research Collection School Of Computing and Information Systems

Resolving domain incompatibility among independently developed databases often involves uncertain information. DeMichiel (1989) showed that uncertain information can be generated by the mapping of conflicting attributes to a common domain, based on some domain knowledge. The authors show that uncertain information can also arise when the database integration process requires information not directly represented in the component databases, but can be obtained through some summary of data. They therefore propose an extended relational model based on Dempster-Shafer theory of evidence (1976) to incorporate such uncertain knowledge about the source databases. They also develop a full set of extended relational operations …


Managing Risks In Information Technology Projects, Boon Siong Neo, Kwong Sin Leong Jan 1994

Managing Risks In Information Technology Projects, Boon Siong Neo, Kwong Sin Leong

Research Collection School Of Accountancy

The development and implementation of IT (Information Technology) projects are plagued with problems of cost and time overruns. technical inadequacy, inability to meet user requirements. lack of utilization. and failure to achieve anticipated benefits. These problems occur to some projects and not to others because I) IT projects have different profiles of risk. and 2) IT project risks have been managed more or less effectively. This paper synthesizes the literature into four classes of risks. and applies it to evaluate TradeNet. an EDLbased trading system implemented in Singapore in I989. Through a case study of TradeNet. we derived a typology …


Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas Jan 1994

Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Measurement Of The Cross Section For Γγ→Pp̄, Artuso, M.; Et Al., M. Thulasidas Jan 1994

Measurement Of The Cross Section For Γγ→Pp̄, Artuso, M.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Observation Of Inclusive B Decays To The Charmed Baryons C++ And C0, Procario, M.; Te Al., M. Thulasidas Jan 1994

Observation Of Inclusive B Decays To The Charmed Baryons C++ And C0, Procario, M.; Te Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas Jan 1994

Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

We have measured the vector-pseudoscalar mass splitting M(D*+s)-M(D+s)=144.22±0.47±0.37 MeV significantly more precisely than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference M(D*0)-M(D0) using the radiative decay D*0→D0γ, obtaining [M(D*+s)-M(D+s)]-[M(D*0)-M(D0)] =2.09±0.47±0.37 MeV. This is then combined with our previous high-precision measurement of M(D*0)-M(D0), which used the decay D*0→D0π0. We also measure the mass difference M(D+s)-M(D+)=99.5±0.6±0.3 MeV, using the φπ+ decay modes of the D+s and D+ mesons.


User-Database Interface: The Effect Of Abstraction Levels On Query Performance, Hock Chuan Chan, Kwok Kee Wei, Keng Siau Dec 1993

User-Database Interface: The Effect Of Abstraction Levels On Query Performance, Hock Chuan Chan, Kwok Kee Wei, Keng Siau

Research Collection School Of Computing and Information Systems

A common classification of data models is based on their abstraction levels: physical, logical and conceptual. The user-database interaction can be similarly classified. For the conceptual-level interaction, the user and the database exchange information on the user's world, e.g., information of entities, relationships, and attributes. For the logical-level interaction, the user and the database communicate based on concepts in the database system, e.g., relations and join operations. We expect users to be familiar with concepts in their world but not the concepts in the database system. This is especially so for infrequent or naive database users. The conceptual level should …


Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava Dec 1993

Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

We propose a new (and restricted) model for global transactions which allows asynchronous commitment of subtransactions. Our model requires each global transaction to have a fixed structure with update to the data in at most one database. Based on this transaction model, we present two concurrency control algorithms, namely Asynchronous Site Graph and Asynchronous VirtGlobalSG, which employ asynchronous commitment and achieve global serializability. Compared to other proposed algorithms, our algorithms employ asynchronous commitment so as to increase transaction performance. Furthermore, our algorithms do not put restrictions on transaction data access or local histories.


Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava Nov 1993

Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

No abstract provided.


Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava Nov 1993

Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

In certain database applications such as deductive databases, batch query processing, and recursive query processing etc., a single query can be transformed into a set ofclosely related database queries. Great benefits can be obtained by executing a group of related queries all together in a single unijied multi-plan instead of executing each query separately. In order to achieve this, Multiple Query Optimization (MQO) identifies common task(s) (e.g. common subezpressions, joins, etc.) among a set of query plans and creates a single unified plan (multiplan) which can be executed to obtain the required outputs forall queries at once. In this paper, …


Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava Sep 1993

Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

Entity identification is the problem of matching object instances from different databases which correspond to the same real-world entity. In this paper, we present a 2-step entity identification process in which attributes for matching tuples may be missing in certain tuples, and thus need to be derived prior to the matching. To match tuples, we require identity rules which specify the conditions to be satisfied by a pair of tuples, from different databases, before they can be considered as modeling the same real-world entity. We also introduce ILFD's (instance-level functional dependencies) as a form of inference rules which derive the …


Memory-Adaptive External Sorting, Hwee Hwa Pang, Michael J. Carey, Miron Livny Aug 1993

Memory-Adaptive External Sorting, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

In real-time and goal-oriented database systems, the amount of memory assigned to queries that sort or join large relations may fluctuate due to contention from other higher priority transactions. This study focuses on techniques that enable external sorts both to reduce their buffer usage when they lose memory, and to effectively utilize any additional buffers that are given to them. We also show how these techniques can be extended to work with sort-merge joins. A series of experiments confirms that our proposed techniques are useful for sorting and joining large relations in the face of memory fluctuations.


Partially Preemptible Hash Joins, Hwee Hwa Pang, Michael J. Carey, Miron Livny May 1993

Partially Preemptible Hash Joins, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

With the advent of real-time and goal-oriented database systems, priority scheduling is likely to be an important feature in future database management systems. A consequence of priority scheduling is that a transaction may lose its buffers to higher-priority transactions, and may be given additional memory when transactions leave the system. Due to their heavy reliance on main memory, hash joins are especially vulnerable to fluctuations in memory availability. Previous studies have proposed modifications to the hash join algorithm to cope with these fluctuations, but the proposed algorithms have not been extensively evaluated or compared with each other. This paper contains …


Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson Apr 1993

Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson

Research Collection School Of Computing and Information Systems

The objective of entity identification is to determine the correspondence between object instances from more than one database. Entity identification at the instance level, assuming that schema level heterogeneity has been resolved a priori, is examined. Soundness and completeness are defined as the desired properties of any entity identification technique. To achieve soundness, a set of identity and distinctness rules are established for entities in the integrated world. The use of extended key, which is the union of keys, and possibly other attributes, from the relations to be matched, and its corresponding identify rule are proposed to determine the equivalence …


Federated Autonomous Databases: Project Overview, Satya Prabhakar, Jiandong Huang, James Richardson, Jaideep Srivastava, Ee Peng Lim, Sham Navathe, Ashok Savarase, Mark Foresti Apr 1993

Federated Autonomous Databases: Project Overview, Satya Prabhakar, Jiandong Huang, James Richardson, Jaideep Srivastava, Ee Peng Lim, Sham Navathe, Ashok Savarase, Mark Foresti

Research Collection School Of Computing and Information Systems

The paper presents an overview of an ongoing research program, Federated Autonomous Databases, sponsored by Rome Laboratory (US Air Force) and conducted by Honeywell in collaboration with the University of Minnesota and Georgia Institute of Technology. This program is exploratory in nature and is aimed at understanding and solving, within the scope of the program definition, the problem of providing integrated access to distributed, heterogeneous and autonomous databases.


Observation Of B0 Decay To Two Charmless Mesons, M. Battle, Manoj Thulasidas Jan 1993

Observation Of B0 Decay To Two Charmless Mesons, M. Battle, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

We report results from a search for the decays B0→π+π-, B0→K+π-, and B0→K+K-. We find 90% confidence level upper limits on the branching fractions, Bππ


Measurement Of Charmless Semileptonic Decays Of B Mesons, Bartelt; J.; Et Al., M. Thulasidas Jan 1993

Measurement Of Charmless Semileptonic Decays Of B Mesons, Bartelt; J.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Tau Decays With One Charged Particle Plus Multiple Π0'S, M. Procario, Manoj Thulasidas Jan 1993

Tau Decays With One Charged Particle Plus Multiple Π0'S, M. Procario, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

With the CLEO-II detector at the Cornell Electron Storage Ring, we have measured branching fractions for tau lepton decay into one-prong final states with multiple π0’s B0hnπ, normalized to the branching fraction for tau decay into one charged particle and a single π0. We find B0h2π/B0hπ=0.345±0.006±0.016, B0h3π/B0hπ=0.041 ±0.003±0.005, and B0h4π/B0hπ=0.006±0.002±0.002.


Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas Jan 1993

Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Evidence For Penguin-Diagram Decays: First Observation Of B→K*(892)Γ, R. Ammar, M. Thulasidas Jan 1993

Evidence For Penguin-Diagram Decays: First Observation Of B→K*(892)Γ, R. Ammar, M. Thulasidas

Research Collection School Of Computing and Information Systems

We have observed the decays B0→K*(892)0γ and B−→K*(892)−γ, which are evidence for the quark-level process b→sγ. The average branching fraction is (4.5±1.5±0.9)×10−5. This value is consistent with standard model predictions from electromagnetic penguin diagrams.


Search For Τ-→Γμ-: A Test Of Lepton Number Conservation, A. Bean, M. Thulasidas Jan 1993

Search For Τ-→Γμ-: A Test Of Lepton Number Conservation, A. Bean, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for the lepton mumber violating decay of the τ lepton to the γμ final state has been performed with the CLEO II detector at the Cornell e+e− storage ring CESR. In a data sample that corresponds to an integrated luminosity of 1.55 fb−1, we observe no candidates in the signal region. We thus determine an upper limit of B(τ−→γμ−)


Study Of D0 Decays Into K̄0 And K̄*0, M. Procario, M. Thulasidas Jan 1993

Study Of D0 Decays Into K̄0 And K̄*0, M. Procario, M. Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at CESR we have studied D0 decays into final states with a ¯K0 or ¯K*0, and have measured branching ratios for the decay modes D0→(¯K0¯K*0)π0, η, η′. These results are compared with predictions of various charm decay models, and contributions of final-state interactions are discussed.


A Rule-Based System For Query Feedback, Hock C. Chan, Kwok-Kee Wei, Keng Siau Jan 1993

A Rule-Based System For Query Feedback, Hock C. Chan, Kwok-Kee Wei, Keng Siau

Research Collection School Of Computing and Information Systems

The authors propose a rule-based system which provides feedback in order to give the user a better understanding of the user's queries. This technique improves query accuracy and confidence. A rule-based expert system that pinpoints syntax errors is described. It suggests possible semantics errors and provides possible solutions, as well as the English translation for the queries. The system can be used for computer-aided training and in actual operations. The system was experimentally tested with a group of students.


A Case Tool For Conceptual Database Design, Keng Siau, Kok Phuang Tan, Hock Chuan Chan Dec 1992

A Case Tool For Conceptual Database Design, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

The paper describes a Computer Aided Software Engineering (CASE) tool to support conceptual database modelling. One popular approach for conceptual database modelling is use of the Entity-Relationship (ER) model. The paper proposes the use of an Enhanced Entity-Relationship (EER) model for conceptual database modelling. This Enhanced Entity-Relationship model extends the Entity-Relationship model by incorporating the generalization/specialization, aggregation and categorization abstractions. The CASE tool, which is based on the Enhanced Entity-Relationship model, is known as the Enhanced Entity-Relationship Diagrammer (EERD). In addition, the CASE tool supports direct visual query and update based on the EERM.


A Participants' Dss For A Management Game With A Dss Generator, G. K. Yeo, Fiona Fui-Hoon Nah Sep 1992

A Participants' Dss For A Management Game With A Dss Generator, G. K. Yeo, Fiona Fui-Hoon Nah

Research Collection School Of Computing and Information Systems

A decision support system for a management game has been built with emphasis on total model integration, easy database access, and efficient model building by participants themselves. A decision-support-system generator has been used to provide a wide range of modeling capabilities. This article describes its design principles and major features.


Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas Jan 1992

Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=Γ(τ→eν¯eντ)Γ1 where Γ1 is the τ decay rate to final states with one charged particle. We find R=0.2231±0.0044±0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the τ lepton to electrons, Be=0.192±0.004±0.006.


Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas Jan 1992

Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using the decay modes, D*+→D+π0 and D*0→D0π0, we have measured the D*+−D+ and D*0−D0 mass differences to be 140±0.08±0.06 and 142.12±0.05±0.05 MeV, respectively. Combining these measurements with the Particle Data Group average for the D*+−D0 mass difference, we obtain isospin mass splittings for D*+−Dusp*0 and D+−D0 of 3.32±0.08±0.05 and 4.80±0.10 ±0.06 MeV. We discuss the implications of these measurements for models of isospin mass differences and model-dependent estimates of fD.