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Research Collection School Of Computing and Information Systems

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Articles 8341 - 8370 of 8452

Full-Text Articles in Physical Sciences and Mathematics

The Forward-Backward Asymmetry For Charm Quarks At The Z Pole, D. Buskulic, Manoj Thulasidas Jun 1995

The Forward-Backward Asymmetry For Charm Quarks At The Z Pole, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

From 1.4 million hadronic Z decays collected by the ALEPH detector at LEP, an enriched sample of Z → cc̄ events is extracted by requiring the presence of a high momentum D∗±. The charm quark forward-backward charge asymmetry at the Z pole is measured to be AFB0.c = (8.0 ± 2.4) % corresponding to an effective electroweak mixing angle of sin2θWeff = 0.2302 ± 0.0054.

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The Effect Of A Database Feedback System On User Performance, H. Chan, K. Wei, Keng Siau May 1995

The Effect Of A Database Feedback System On User Performance, H. Chan, K. Wei, Keng Siau

Research Collection School Of Computing and Information Systems

There are two main approaches to improving the effectiveness of database interfaces. One is to raise the level of abstraction for the content of the user-database interaction. The relational model belonging to the logical level has replaced the hierarchical and network models that belong to the lower physical level. It is likely that the relational model will eventually be replaced by models belonging to the even higher conceptual level, such as entity relationship models and object-oriented models. The second approach is to enhance the actual interaction process. This can be done by providing better feedback to the user. Feedback can …

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Myriad: Design And Implementation Of A Federated Database Prototype, Ee Peng Lim, San-Yih Hwang, Jaideep Srivastava, Dave Clements, M. Ganesh May 1995

Myriad: Design And Implementation Of A Federated Database Prototype, Ee Peng Lim, San-Yih Hwang, Jaideep Srivastava, Dave Clements, M. Ganesh

Research Collection School Of Computing and Information Systems

A key problem in providing enterprise-wide information is the integration of databases that have been independently developed. An important requirement is to accommodate heterogeneity and maintain the autonomy of component databases. Myriad is a federated database prototype developed at the University of Minnesota, to provide a testbed for investigating alternatives in architecture and algorithms for database integration, query processing and optimization, and concurrency control and recovery. The system incorporates our group's research results in these areas. This paper describes our experiences in the design and implementation of Myriad, and in the project management. Special emphasis is given to discussing design …

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Exceptions And Exception Handling In Computerized Information Processes, Diane M. Strong, Steven M. Miller Apr 1995

Exceptions And Exception Handling In Computerized Information Processes, Diane M. Strong, Steven M. Miller

Research Collection School Of Computing and Information Systems

Exceptions, situations that cannot be correctly processed by computer systems, occur frequently in computer-based information processes. Five perspectives on exceptions provide insights into why exceptions occur and how they might be eliminated or more efficiently handled. We investigate these perspectives using an in-depth study of an operating information process that has frequent exceptions. Our results support the use of a total quality management (TQM) approach of eliminating exceptions for some exceptions, in particular, those caused by computer systems that are poor matches to organizational processes. However, some exceptions are explained better by a political system perspective of conflicting goals between …

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Search For Supersymmetric Particles With R-Parity Violation In Z Decays, D. Buskulic, Manoj Thulasidas Apr 1995

Search For Supersymmetric Particles With R-Parity Violation In Z Decays, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Searches for supersymmetric particles produced in e+e− interactions at the Z peak have been performed under the assumptions that R-parity is not conserved, that the dominant R-parity violating coupling involves only leptonic fields, and that the lifetime of the lightest supersymmetric particle can be neglected. In a data sample collected by the ALEPH detector at LEP up to 1993, and corresponding to almost two million hadronic Z decays, no signal was observed. As a result, supersymmetric particle masses and couplings are at least as well constrained as under the usual assumption of R-parity conservation.

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An Upper Limit For The Τ Neutrino Mass From Τ → 5Π(Π0)Ντ Decays, D. Buskulic, M. Thulasidas Apr 1995

An Upper Limit For The Τ Neutrino Mass From Τ → 5Π(Π0)Ντ Decays, D. Buskulic, M. Thulasidas

Research Collection School Of Computing and Information Systems

From a sample of 152,000 τ decays collected by the ALEPH detector at LEP an upper limit of 24 MeV at 95% CL on the τ neutrino mass has been determined. The limit is obtained using a two dimensional likelihood fit of the visible energy and the invariant mass distribution of 25 τ → 5π(π0)ντ events.

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Study Of The Subjet Structure Of Quark And Gluon Jets, D. Buskulic, D., M. Thulasidas Mar 1995

Study Of The Subjet Structure Of Quark And Gluon Jets, D. Buskulic, D., M. Thulasidas

Research Collection School Of Computing and Information Systems

Measurements of the subjet structure of quark and gluon jets in hadronic Z decays are presented. The analysis is based on one million hadronic events recorded by the Aleph detector. Roughly symmetric three-jet events are selected with a coarse jet-resolution cut-off, y1. Gluon jets are identified with a purity of 94.6% in those events where evidence of long-lived heavy-flavour hadrons in the other two jets is found. The jets are then analyzed using a smaller cut-off y0 (< y1) so that subjets are resolved. The properties of the jets (subjet multiplicities (Nq), (Ng) and rates Rng(q) for n = 1, 2, 3, 4) are determined and are found to be in good agreement with the expectations of perturbative QCD as long as the subjet resolution parameter y0 is sufficiently large to keep non-perturbative effects small. In particular, the ratio , which to leading order in QCD is given by the ratio of colour factors , is measured to be 1.96 ± 0.15 for y0 = 2 · 10−3, but falls to 1.29 ± 0.03 for y0 = 1.6 · 10−5.

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Michel Parameters And Τ Neutrino Helicity From Decay Correlations In Z → Τ+Τ-, D. Buskulic, Manoj Thulasidas Mar 1995

Michel Parameters And Τ Neutrino Helicity From Decay Correlations In Z → Τ+Τ-, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

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A Study Of D*+ Π- Production In Semileptonic B Decay, D. Buskulic, M. Thulasidas Feb 1995

A Study Of D*+ Π- Production In Semileptonic B Decay, D. Buskulic, M. Thulasidas

Research Collection School Of Computing and Information Systems

In a sample of 1.5 million hadronic decays of the Z collected by the ALEPH detector, a search is carried out for the decays B→ D10(2420)l−νX and B→ D2∗0(2460)l−νX. The product branching ratio for D10 production is measured to be Br(b →B) × Br(B→ D10l−νX) × Br(D10→ D∗+π−) = (2.04 ± 0.58stat± 0.34syst) × 10−3, and a 95% confidence level limit of Br(b →B) × Br(B→ D2∗0l−νX) × Br(D2∗0→ D∗+π−) ≤ 0.81 × 10−3 is obtained for D2∗0 production.A topological search sensitive to the processes above, but also to wide resonances that decay to D∗+π− and to non-resonant D∗+π− production …

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A Type I Hybrid Arq System With Adaptive Code Rates, Robert H. Deng, Michael L. Lin Feb 1995

A Type I Hybrid Arq System With Adaptive Code Rates, Robert H. Deng, Michael L. Lin

Research Collection School Of Computing and Information Systems

Type I hybrid ARQ systems use an error-control code of fixed rate for error-correction in each transmitted packet. In such systems, the code rate must be carefully chosen to match the channel bit error rate (BER) in order to maximize system throughput. Whenever there is a mismatch between code rate and channel BER, the throughput suffers. In this paper, we proposed a type I hybrid ARQ system which automatically adjusts its code rates to match channel BERs. The proposed system is very simple to implement and yet performs significantly better than type I hybrid ARQ systems of fixed code rate

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Production Of Excited Beauty States In Z Decays, D. Buskulic, Manoj Thulasidas Jan 1995

Production Of Excited Beauty States In Z Decays, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

A data sample of about 3.0 million hadronic Z decays collected by the ALEPH experiment at LEP in the years 1991 through 1994, is used to make an inclusive selection of B hadron events.

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Rule Extraction: From Neural Architecture To Symbolic Representation, Gail A. Carpenter, Ah-Hwee Tan Jan 1995

Rule Extraction: From Neural Architecture To Symbolic Representation, Gail A. Carpenter, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

This paper shows how knowledge, in the form of fuzzy rules, can be derived from a supervised learning neural network called fuzzy ARTMAP. Rule extraction proceeds in two stages: pruning, which simplifies the network structure by removing excessive recognition categories and weights; and quantization of continuous learned weights, which allows the final system state to be translated into a usable set of descriptive rules. Three benchmark studies illustrate the rule extraction methods: (1) Pima Indian diabetes diagnosis, (2) mushroom classification and (3) DNA promoter recognition. Fuzzy ARTMAP and ART-EMAP are compared with the ADAP algorithm, the k nearest neighbor system, …

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Transplanting Manufacturing Power: Observations From Five Years At Fujitsu, Steven M. Miller Jan 1995

Transplanting Manufacturing Power: Observations From Five Years At Fujitsu, Steven M. Miller

Research Collection School Of Computing and Information Systems

Within a factory, what are the underpinnings of manufacturing power? During my thirty-month residency at Fujitsu's factory in Oyama, Japan, I constantly reflected on this question. The standard view of a factory structure provided by an organization chart was inadequate for summarizing my observations.

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First Measurement Of The Quark-To-Photon Fragmentation Function, D. Buskulic, Manoj Thulasidas Jan 1995

First Measurement Of The Quark-To-Photon Fragmentation Function, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Earlier measurements at LEP of isolated hard photons in hadronic Z decays, attributed to radiation from primary quark pairs, have been extended in the ALEPH experiment to include hard photon production inside hadron jets. Events are selected where all particles combine democratically to form hadron jets, one of which contains a photon with a fractional energy z 0:7. After statistical subtraction of non-prompt photons, the quark-to-photon fragmentation function, D(z), is extracted directly from the measured 2-jet rate. By taking into account the perturbative contributions to D(z) obtained from an O(S ) QCD calculation, the unknown non-perturbative component of D(z) is …

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Improved Tau Polarisation Measurement, D. Buskulic, M. Thulasidas Jan 1995

Improved Tau Polarisation Measurement, D. Buskulic, M. Thulasidas

Research Collection School Of Computing and Information Systems

Using 22 pb−1 of data collected at LEP in 1992 on the peak of the Z resonance, the ALEPH collaboration has measured the polarisation of the tau leptons decaying intoevv¯,μvv¯evv¯,μvv¯,πν, ρν and a1 ν from their individual decay product distributions. The measurement of the tau polarisation as a function of the production polar angle yields the two parametersN τ andN e, where, in terms of the axial and vector couplingsg Al andg Vl,N l=2g Vl gAl/(g 2Vl+g2Al). This analysis follows to a large extent the methods devised for the 1990 and 1991 data but with improvements which bring a better …

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Object Interactions As First Class Objects: From Design To Implementation, Mahesh Dodani, Benjamin Kok Siew Gan, Lizette Velazquez Jan 1995

Object Interactions As First Class Objects: From Design To Implementation, Mahesh Dodani, Benjamin Kok Siew Gan, Lizette Velazquez

Research Collection School Of Computing and Information Systems

Collaborations between objects make up the dynamic behavior of OO software. These collaborations among objects require careful design and implementation. Treating the interactions as responsibilities that are integrated in the participating objects, results in tight coupling between objects. Tight coupling increases complexity and reduces reusability. Object interactions need to be first class objects from design to implementation. Our research provides a unified approach to model and implement these interactions as first class objects. During analysis and design, they are modeled using DynaSpecs. During implementation, they are coded with a new language construct called Compositions. DynaSpecs and Compositions provide a consistent …

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Multiple Query Optimization With Depth-First Branch-And-Bound And Dynamic Query Ordering, Ee Peng Lim, Ahmet Cosar, Jaideep Srivastava Jan 1995

Multiple Query Optimization With Depth-First Branch-And-Bound And Dynamic Query Ordering, Ee Peng Lim, Ahmet Cosar, 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., usually a single query gets transformed into a set of closely related database queries. Also, great benefits can be obtained by executing a group of related queries all together in a single unified multi-plan instead of executing each query separately. In order to achieve this Multiple Query Optimization (MQO) identifies common task(s) (e.g. common subexpressions, joins, etc.) among a set of query plans and creates a single unified plan (multi-plan) which can be executed to obtain the required outputs for all queries at once. …

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Inclusive Production Of Neutral Vector Mesons In Hadronic Z Decays, D. Buskulic, Manoj Thulasidas Jan 1995

Inclusive Production Of Neutral Vector Mesons In Hadronic Z Decays, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Data on the inclusive production of the neutral vector mesonsρ 0(770),ω(782), K*0(892), andφ(1020) in hadronic Z decays recorded with the ALEPH detector at LEP are presented and compared to Monte Carlo model predictions. Bose-Einstein effects are found to be important in extracting a reliable value for theρ 0 production rate. An averageρ 0 multiplicity of 1.45±0.21 per event is obtained. Theω is detected via its three pion decay modeω→π + π − π 0 and has a total rate of 1.07±0.14 per event. The multiplicity of the K*0 is 0.83±0.09, whilst that of theφ is 0.122±0.009, both measured using their …

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Adaptive Resonance Associative Map, Ah-Hwee Tan Jan 1995

Adaptive Resonance Associative Map, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

This article introduces a neural architecture termed Adaptive Resonance Associative Map (ARAM) that extends unsupervised Adaptive Resonance Theory (ART) systems for rapid, yet stable, heteroassociative learning. ARAM can be visualized as two overlapping ART networks sharing a single category field. Although ARAM is simpler in architecture than another class of supervised ART models known as ARTMAP, it produces classification performance equivalent to that of ARTMAP. As ARAM network structure and operations are symmetrical, associative recall can be performed in both directions. With maximal vigilance settings, ARAM encodes pattern pairs explicitly as cognitive chunks and thus guarantees perfect storage and recall …

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Knowledge-Based Safety Training System (Kbsts): A Prototype Implementation, Venky Shankararaman, B. S. Lee Dec 1994

Knowledge-Based Safety Training System (Kbsts): A Prototype Implementation, Venky Shankararaman, B. S. Lee

Research Collection School Of Computing and Information Systems

A computer-based safety training system for process operators must be able to make effective presentation of textual material, test the trainee's understanding through quizzes and facilitate plant simulation. The general framework of such a system is presented in an earlier paper (Computers in Industry, Vol. 17, 1991, pp. 349–358). In this paper, we discuss the development and implementation of a prototype Knowledge-Based Safety Training System based on the framework. The design philosophy, system architecture and the plant modelling methodology are described.

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A Load Distribution Through Competition For Workstation Clusters, Kam Hong Shum, Muslim Bozyigit Nov 1994

A Load Distribution Through Competition For Workstation Clusters, Kam Hong Shum, Muslim Bozyigit

Research Collection School Of Computing and Information Systems

The aim of this work is to develop a competition driven solution approach for load distribution in distributed computing system (DCS) environments. The subject DCS is composed of a set of workstation clusters. The study deals with concurrent applications, but assumes the existence of the independent tasks executing on individual workstations as well. Akin to conventional load balancing algorithms, the approach considers two phases; the partitioning phase and the mapping phase. Each phase is based on the application and the DCS data which is translated into market data, mainly price. The price is governed by the demand and supply of …

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An Empirical Study On End Users' Update Performance For Different Abstraction Levels, Hock Chuan Chan, Kwok Kee Wei, Keng Siau Sep 1994

An Empirical Study On End Users' Update Performance For Different Abstraction Levels, Hock Chuan Chan, Kwok Kee Wei, Keng Siau

Research Collection School Of Computing and Information Systems

Recent laboratory experiments have shown a strong tendency that database users can perform better at the conceptual level than at the logical level. The experiments measured users’ performance for the tasks of database design and database retrieval. Besides database design and retrieval, the third major database task is update. User performance for updates has not been measured. With the widespread availability of databases, updates will be done frequently by end-users. This task is gaining in importance as a measure of the usability of a database system. An experiment was conducted to measure the effect of different abstraction levels on user …

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Performance Of Combined Diversity Reception And Convolutional Coding For Qdpsk Land Mobile Radio, Huafei Zhou, Robert H. Deng, T. T. Tjhung Aug 1994

Performance Of Combined Diversity Reception And Convolutional Coding For Qdpsk Land Mobile Radio, Huafei Zhou, Robert H. Deng, T. T. Tjhung

Research Collection School Of Computing and Information Systems

Diversity reception and error correction coding are powerful techniques to combat multipath fading encountered in mobile radio communications. In order to improve the transmission performance of the ?/4-shift QDPSK signal in mobile radio channels, the authors propose a new scheme of combined coding and diversity reception, i.e., combination of diversity reception employing code combining (CC) and convolutional coding employing error-and erasure correction Viterbi decoding. They also consider another combination scheme, i.e., combination of diversity reception employing postdetection maximal ratio combining (MRC) and convolutional coding employing hard decision Viterbi decoding. They theoretically analyze the performance of the schemes taking into account …

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Optimum Symbol-By-Symbol Detection Of Uncoded Digital Data Over The Gaussian Channel With Unknown Carrier Phase, Pooi Yuen Kam, Seng Siew Ng, Tock Soon Ng Aug 1994

Optimum Symbol-By-Symbol Detection Of Uncoded Digital Data Over The Gaussian Channel With Unknown Carrier Phase, Pooi Yuen Kam, Seng Siew Ng, Tock Soon Ng

Research Collection School Of Computing and Information Systems

A theory of optimum receiver design for symbol-by-symbol detection of an uncoded digital data sequence received over the Gaussian channel with unknown carrier phase is presented. Linear suppressed-carrier modulation is assumed. The work here aims at laying a conceptual foundation for optimum symbol-by-symbol detection, and rectifies existing approaches to the problem. The optimum receiver structure is obtained explicitly for an arbitrary carrier phase model, but its computational requirements are too heavy in general for any practical implementation. In one important special case, namely, the case in which the carrier phase can be treated as a constant over some K+1 symbol …

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Automated Manpower Rostering: Techniques And Experience, C. M. Khoong, Hoong Chuin Lau, L. W. Chew Jul 1994

Automated Manpower Rostering: Techniques And Experience, C. M. Khoong, Hoong Chuin Lau, L. W. Chew

Research Collection School Of Computing and Information Systems

We present ROMAN, a comprehensive, generic manpower rostering toolkit that successfully handles a wide spectrum of work policies found in service organizations. We review the use of various techniques and methodologies in the toolkit that contribute to its robustness and efficiency, and relate experience gained in addressing manpower rostering problems in industry.

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Production And Decay Of D1 (2420)0 And D2* (2460)0, Avery, P.; Et Al., M. Thulasidas Jun 1994

Production And Decay Of D1 (2420)0 And D2* (2460)0, Avery, P.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

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Managing Memory For Real-Time Queries, Hwee Hwa Pang, Michael J. Carey, Miron Livny May 1994

Managing Memory For Real-Time Queries, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

The demanding performance objectives that real-time database systems (RTDBS) face necessitate the use of priority resource scheduling. This paper introduces a Priority Memory Management (PMM) algorithm that is designed to schedule queries in RTDBS. PMM attempts to minimize the number of missed deadlines by adapting both its multiprogramming level and its memory allocation strategy to the characteristics of the offered workload. A series of simulation experiments confirms that PMM's admission control and memory allocation mechanisms are very effective for real-time query scheduling.

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The Myriad Federated Database Prototype, San-Yih Hwang, Ee Peng Lim, H. R. Yang, S. Musukula, K. Mediratta, M. Ganesh, D. Clements, J. Stenoien, Jaideep Srivastava May 1994

The Myriad Federated Database Prototype, San-Yih Hwang, Ee Peng Lim, H. R. Yang, S. Musukula, K. Mediratta, M. Ganesh, D. Clements, J. Stenoien, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

Myriad is a federated database system (FDBS) prototype being developed at the University of Minnesota. The main objective behind this prototyping effort is to provide "enterprise-wide" information by integrating independently developed databases while preserving the local autonomy of the component DBMSs and applications. In Myriad, multiple federations can be formed. A federation consists of an integrated database whose schema is represented as a set of integrated relations derived from the export relations provided by the component DBMSS. SQL, mainly due to its simplicity and popularity among database users and vendors, has been adopted to express global queries as well as …

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Automating Output Size And Reuse Metrics In A Repository-Based Computer-Aided Software Engineering (Case) Environment, R. D. Banker, Robert J. Kauffman, C. Wright, D. Zweig Mar 1994

Automating Output Size And Reuse Metrics In A Repository-Based Computer-Aided Software Engineering (Case) Environment, R. D. Banker, Robert J. Kauffman, C. Wright, D. Zweig

Research Collection School Of Computing and Information Systems

Measurement of software development productivity is needed in order to control software costs, but it is discouragingly labor-intensive and expensive. Computer-aided software engineering (CASE) technologies-especially repository-based, integrated CASE-have the potential to support the automation of this measurement. We discuss the conceptual basis for the development of automated analyzers for function point and software reuse measurement for object-based CASE. Both analyzers take advantage of the existence of a representation of the application system that is stored within an object repository, and that contains the necessary information about the application system. We also discuss metrics for software reuse measurement, including reuse leverage, …

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A Measurement Of B(D+S → Φl+Ν) B(D+S → Φπ+), Cleo Collaboration, F. Butler, Manoj Thulasidas Mar 1994

A Measurement Of B(D+S → Φl+Ν) B(D+S → Φπ+), Cleo Collaboration, F. Butler, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at CESR, we have measured the ratio of branching fractions B(D → φlν) B(D → φπ) = 0.54 ± 0.05 ± 0.04. We use this measurement to obtain a model dependent estimate of B(D → φπ). © 1994.

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