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Research Collection School Of Computing and Information Systems

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A Typology For Understanding The Role Of Information As A Source Of Value Creation In The Emerging Information Economy, J. Mcintosh, Keng Siau Aug 1998

A Typology For Understanding The Role Of Information As A Source Of Value Creation In The Emerging Information Economy, J. Mcintosh, Keng Siau

Research Collection School Of Computing and Information Systems

Today’s economy is increasingly driven by the integration of information in many aspects of business. Greater information intensity in industries such as hospital supply and express package delivery is causing a fundamental transformation in the way firms conduct business, the menu of competitive choices that they are faced with, and the need to continuously keep ahead of competitors. Information driven businesses appear to adopt several competitive or operating innovations. These include: mass customization or the creation of customized products which offer virtually individualized products to customers in mass markets (Pine, 1993); disintermediation or the creation of direct links between producers …


Search For Sleptons In E+E- Collisions At Centre-Of-Mass Energies Up To 184 Gev Aleph Collaboration, R. Barate, Manoj Thulasidas Aug 1998

Search For Sleptons In E+E- Collisions At Centre-Of-Mass Energies Up To 184 Gev Aleph Collaboration, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The data collected by the ALEPH experiment at LEP at centre–of–mass energies around 183 GeV are analysed to search for sleptons, the partners of leptons in supersymmetric theories. The previously published search for acoplanar leptons and missing energy has been updated. New searches have been developed to cover a wider range of slepton signals. These include single electrons, acoplanar leptons accompanied by two photons plus missing energy as well as particles with lifetime. No evidence for the production of any such particles is found. Slepton mass limits are reported within gravity mediated and gauge mediated SUSY breaking scenarios.


Scalar Quark Searches In E+E- Collisions At √S = 181 - 184 Gev, Barate, R.; Et Al., M. Thulasidas Aug 1998

Scalar Quark Searches In E+E- Collisions At √S = 181 - 184 Gev, Barate, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

Searches for scalar top, scalar bottom and degenerate scalar quarks have been performed with data collected with the ALEPH detector at LEP. The data sample consists of 57 pb−1 taken at s = 181–184 GeV. No evidence for scalar top, scalar bottom or degenerate scalar quarks was found in the channels t̃→cχ, t̃→bℓν̃, b̃→bχ, and q̃→qχ. From the channel t̃→cχ a limit of 74 GeV/c2has been set on the scalar top quark mass, independent of the mixing angle. This limit assumes a mass difference between the t̃ and the χ in the range 10–40 GeV/c2. From the channel t̃→bℓν̃ the …


Join Processing In Web Databases, Sourav S. Bhowmick, Wee-Keong Ng, Ee Peng Lim Aug 1998

Join Processing In Web Databases, Sourav S. Bhowmick, Wee-Keong Ng, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Recently, there has been increasing interests in data models and query languages for unstructured data in the World Wide Web. When web data is harnessed in a web warehouse, new and useful information can be derived through appropriate information manipulation. In our web warehousing project, we introduce a new operator called the web join. Like its relational counterpart, web join combines information from two web tables to yield a new web table. This paper discusses various issues in web join such as join semantics, joinability, and join evaluation.


The Forward-Backward Asymmetry For Charm Quarks At The Z, R. Barate, Manoj Thulasidas Aug 1998

The Forward-Backward Asymmetry For Charm Quarks At The Z, R. Barate, 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.


Information Systems And Economics, Robert J. Kauffman, Frederick J. Riggins Aug 1998

Information Systems And Economics, Robert J. Kauffman, Frederick J. Riggins

Research Collection School Of Computing and Information Systems

Do big dollar expenditures on information systems pay off? Friction-free: is that what we really want markets to be? Is it time for consumers to say goodbye to fixed pricing? The Internet creates an environment in which the cost of buyer-seller interactions is cheaper than ever, and consumers can participate in the price-setting process—revealing their willingness to pay—making it the most efficient one-on-one selling environment anywhere, approaching the efficiency of the financial markets. In fact, such transformation is evident throughout the information economy. We see it in the approximately 1,000% annual network growth rates expected by some Internet service providers’ …


Database Selection Techniques For Routing Bibliographic Queries, Ee Peng Lim, Wee-Keong Ng, Jian Xu, Yinyan Cao Jun 1998

Database Selection Techniques For Routing Bibliographic Queries, Ee Peng Lim, Wee-Keong Ng, Jian Xu, Yinyan Cao

Research Collection School Of Computing and Information Systems

No abstract provided.


A Measurement Of The Inclusive B → Sγ Branching Ratio, R. Barate, Manoj Thulasidas Jun 1998

A Measurement Of The Inclusive B → Sγ Branching Ratio, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The avour changing neutral current decay b ! s has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged b b events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to be (3:11 0:80stat 0:72syst) 104 ; consistent with the Standard Model expectation via penguin processes


The New Aleph Silicon Vertex Detector, D. Creanza, Manoj Thulasidas May 1998

The New Aleph Silicon Vertex Detector, D. Creanza, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The ALEPH collaboration, in view of the importance of effective vertex detection for the Higgs boson search at LEP 2, decided to upgrade the previous vertex detector. Main changes were an increased length (+/- 20 cm), a higher granularity for r phi view (50 mu m), a new preamplifier (MX7 rad hard chip), a polymide (upilex) fan-out on z side to carry the signals from the strips to the front-end electronics outside the fiducial region reducing consequently the passive material in the central region by a factor of two. The detector, the running experience and its performance will be described. …


Resonant Structure And Flavour Tagging In The Bπ± System Using Fully Reconstructed B Decays, Barate, R.; Et Al., M. Thulasidas Apr 1998

Resonant Structure And Flavour Tagging In The Bπ± System Using Fully Reconstructed B Decays, Barate, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Measurement Of The W Mass By Direct Reconstruction In E+E- Collisions At 172 Gev, Barate, R.; Et Al., M. Thulasidas Mar 1998

Measurement Of The W Mass By Direct Reconstruction In E+E- Collisions At 172 Gev, Barate, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Measurement Of Triple Gauge-Boson Couplings At 172 Gev, Barate, R.; Et Al, M. Thulasidas Mar 1998

Measurement Of Triple Gauge-Boson Couplings At 172 Gev, Barate, R.; Et Al, M. Thulasidas

Research Collection School Of Computing and Information Systems

The triple gauge-boson couplings, αWΦ, αW and αBΦ, have been measured using 34 semileptonically and 54 hadronically decaying W+W− candidate events. The events were selected in the data recorded during 1996 with the ALEPH detector at 172 GeV, corresponding to an integrated luminosity of 10.65 pb−1. The triple gauge-boson couplings have been measured using optimal observables constructed from kinematic information of W+W− events. The results are in agreement with the Standard Model expectation.


Four-Jet Final State Production In E+E- Collisions At Centre-Of-Mass Energies Ranging From 130 To 184 Gev, R. Barate, Manoj Thulasidas Feb 1998

Four-Jet Final State Production In E+E- Collisions At Centre-Of-Mass Energies Ranging From 130 To 184 Gev, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The four jet topology is analysed in the ALEPH data taken between November 1995 and October 1997, at centre-of-mass energies ranging from 130 to 184 GeV. While an unexpected accumulation of events with a dijet mass sum around 105 GeV/c 2 had been observed during the first run in 1995 at 130/136 GeV, corresponding to an integrated luminosity of 5.7 pb1 , no significant dierences between data and standard model prediction is seen, either in the high energy runs (81.1 pb1 taken at centre-of-mass energies from 161 to 184 GeV) or in the 7.1 pb1 recorded during a new short …


A Visual Object-Relationship Query Language For User-Database Interaction, Keng Siau Feb 1998

A Visual Object-Relationship Query Language For User-Database Interaction, Keng Siau

Research Collection School Of Computing and Information Systems

User–database interaction has a direct and immediate effect on the effectiveness and efficiency of database end users. Traditional query languages like SQL and QBE require end users to understand the underlying data structure in the database. This is a burden on end users, especially novice end users who have little technical knowledge or understanding of database. To alleviate the need for end users to know the logical database organization, this paper proposes the use of an object–relationship (OR) model and a formal high-level visual query language as the interface. Using this interface, end users communicate only domain knowledge with the …


Search For Supersymmetry With A Dominant R-Parity Violating Llē Coupling In E+E- Collisions At Centre-Of-Mass Energies Of 130 Gev To 172 Gev, R. Barate, M. Thulasidas Jan 1998

Search For Supersymmetry With A Dominant R-Parity Violating Llē Coupling In E+E- Collisions At Centre-Of-Mass Energies Of 130 Gev To 172 Gev, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LLE¯LLE¯ coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130–172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This is translated into lower limits on the mass of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, charginos with masses less than 73 GeV/c2c2 and neutralinos with masses less than 23 GeV/c2c2 are excluded at 95% confidence level for any generation structure of the LLE¯LLE¯ coupling, and for neutralino, slepton …


Measurement Of The Axial-Vector Τ Spectral Functions And Determination Of Αs (M2Τ) From Hadronic Τ Decays, R. Barate, M. Thulasidas Jan 1998

Measurement Of The Axial-Vector Τ Spectral Functions And Determination Of Αs (M2Τ) From Hadronic Τ Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

An analysis based on 124 000 selected ττ pairs recorded by the ALEPH detector at LEP provides the vector (V)(V) and axial-vector (A)(A) spectral functions of hadronic ττ decays together with their total widths. This allows the evaluation of finite energy chiral sum rules that are weighted integrals over the (V−A)(V−A) spectral functions. In addition, a precise measurement of αsαs along with a determination of nonperturbative contributions at the ττ mass scale is performed. The experimentally and theoretically most robust determination of αs(M2τ)αs(Mτ2) is obtained from the (V+A)(V+A) fit that yields αs(M2τ)=0.334±0.022αs(Mτ2)=0.334±0.022 giving αs(M2Z)=0.1202±0.0027αs(MZ2)=0.1202±0.0027 after the extrapolation to the mass …


Search For Evidence Of Compositeness At Lep I, R. Barate, M. Thulasidas Jan 1998

Search For Evidence Of Compositeness At Lep I, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

Extensive searches for evidence of compositeness of quarks and leptons have been made in the complete set of ALEPH data from LEP running at the Z peak. These include searches for radiative and weak decays of excited fermions, produced either in pairs or singly, and a scalar partner of the Z. Coupling and branching ratio limits deduced from these searches are presented.


Measurement Of The Fraction Of Hadronic Z Decays Into Charm Quark Pairs, R. Barate, M. Thulasidas Jan 1998

Measurement Of The Fraction Of Hadronic Z Decays Into Charm Quark Pairs, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

The full statistics of hadronic Z decays collected with the ALEPH detector are analysed to measure, by three methods, the ratio, RcRc, of the partial decay width of the Z into cc¯cc¯ quarks to the total hadronic width. One method uses the inclusive pp and p⊥p⊥ spectra of electrons. The other two use a double-tagging technique to measure RcRc independently of the charm-tagging efficiency. In one, the tagging procedure uses the reconstruction of high momentum charmed mesons (D∗+D∗+, D+D+ and \({\rm D^0}$) to detect the charm quarks. In the other, a charm quark is tagged from the D∗D∗'s reconstructed in …


Searches For Charginos And Neutralinos In E+E- Collisions At √S = 161 And 172 Gev, R. Barate, M. Thulasidas Jan 1998

Searches For Charginos And Neutralinos In E+E- Collisions At √S = 161 And 172 Gev, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

The data recorded by the ALEPH detector at centre-of-mass energies of 161, 170, and 172 GeV are analysed for signals of chargino and neutralino production. No evidence of a signal is found, although candidate events consistent with the expectations from Standard Model processes are observed. Limits at 95% C.L. on the production cross sections are derived and bounds on the parameters of the Minimal Supersymmetric Standard Model are set. The lower limit on the mass of the lightest ch is 85.5 GeV/c2GeV/c2 for gaugino-like charginos (μ=−500GeV/c2μ=−500GeV/c2), and 85.0 GeV/c2GeV/c2 for Higgsino-like charginos (M2=500GeV/c2M2=500GeV/c2), for heavy sneutrinos (Mν~≥200GeV/c2Mν~≥200GeV/c2) and tanβ=2–√tan⁡β=2. The …


Study Of B0s Oscillations And Lifetime Using Fully Reconstructed D̄S Decays, R. Barate, M. Thulasidas Jan 1998

Study Of B0s Oscillations And Lifetime Using Fully Reconstructed D̄S Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for B0sBs0 oscillations is performed using approximately 4 million Z→qq¯Z→qq¯ events collected by the ALEPH experiment during 1991–1995. B0sBs0 candidates are partially reconstructed by combining tracks with fully reconstructed D−sDs− candidates. The B0sBs0 production flavour is estimated from the sign of the opposite hemisphere charge, a fragmentation kaon in the same hemisphere, or a lepton in the opposite hemisphere. From a total sample of 1620 candidates, with a B0sBs0 purity estimated to be 22%, all values of ΔmsΔms below 3.9 ps−1−1 and between 6.5 and 8.8 ps−1−1 are excluded at 95% CL. From the same sample, the B0sBs0 …


Evaluating Information Modeling Methods – A Review, Keng Siau, M. Rossi Jan 1998

Evaluating Information Modeling Methods – A Review, Keng Siau, M. Rossi

Research Collection School Of Computing and Information Systems

Hundreds of modeling methods are in existence today, yet practitioners and researchers are zealously “producing” new modeling methods. The “blooming” of modeling methods is not the problem; the lack of standardized techniques for evaluating them is. To further complicate the matter, most of the modeling methods are introduced based on common sense and intuition. Theoretical foundations and empirical evidence are severely lacking. With the current state of affairs, evaluation of modeling methods has become necessary. Comparing modeling methods provides us with the necessary knowledge and understanding on the strengths and weaknesses of each method. This knowledge can also guide us …


An Interlibrary Loan System On The World Wide Web, Schubert Shou Boon Foo, Ee Peng Lim Jan 1998

An Interlibrary Loan System On The World Wide Web, Schubert Shou Boon Foo, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Inter-Library Loan (ILL) service is one of the services provided by libraries that offers users a way to access library resources beyond their affiliated libraries. Additionally, it allows participating libraries to share and maximize their resources. This work examines the ILL process used by libraries in Singapore and proposes that the existing paper-based manual system be replaced by a Web-based ILL system. Such a Web-based system has been successfully designed and implemented at the Nanyang Technological University. The paper presents an overview of the system requirements and architecture, implementation details and demonstrates the feasibility and advantages of the new system.


An Integrated Web-Based Ill System For Singapore Libraries, Schubert Foo, Ee Peng Lim Jan 1998

An Integrated Web-Based Ill System For Singapore Libraries, Schubert Foo, Ee Peng Lim

Research Collection School Of Computing and Information Systems

The paper proposes an integrated Web-based inter-library loan (ILL) system to replace and enhance the existing manual-based ILL system used by Singapore libraries. It describes the system requirements that must be supported in order to make it a viable and acceptable solution to all participating libraries. Subsequently, it presents the client-server Web-based system architecture, database design and Java development platform that are used to implement the system. The new system exhibits a host of advantages over the manual system including the minimising of human resource by eliminating form-filling and other forms of paper work completely, improving the access and speed …


Evaluation Of Information Modeling Methods: A Review, Keng Siau, Matti Rossi Jan 1998

Evaluation Of Information Modeling Methods: A Review, Keng Siau, Matti Rossi

Research Collection School Of Computing and Information Systems

Hundreds of modeling methods are in existence today. Yet practitioners and researchers are zealously "producing" new modeling methods. The "blooming" of modeling methods is not the problem; the lack of standardize techniques for evaluating them is. To further complicate the matter, most of the modeling methods are introduced based on common sense and intuition. Theoretical foundations and empirical evidence are severely lacking. With the current state of affairs, evaluation of modeling methods has become necessary. Comparing modeling methods provides us with the necessary knowledge and understanding on the strengths and weaknesses of each method. This knowledge can also guide us …


Studies Of Quantum Chromodynamics With The Aleph Detector, R. Barate, M. Thulasidas Jan 1998

Studies Of Quantum Chromodynamics With The Aleph Detector, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


An Upper Limit On The Τ Neutrino Mass From Three- And Five-Prong Tau Decays, R. Barate, M. Thulasidas Jan 1998

An Upper Limit On The Τ Neutrino Mass From Three- And Five-Prong Tau Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A bound on the tau neutrino mass is established using the data collected from 1991 to 1995 at s√≃mZ with the ALEPH detector. Two separate limits are derived by fitting the distribution of visible energy vs invariant mass in τ−→2π−π+ντ and τ−→3π−2π+(π0)ντ decays. The two results are combined to obtain a 95% confidence level upper limit of 18.2 MeV/c2 on the mass of the tau neutrino.


Observation Of Doubly-Charmed B Decays At Lep, R. Barate, M. Thulasidas Jan 1998

Observation Of Doubly-Charmed B Decays At Lep, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for doubly-charmed B decays with both charmed mesons reconstructed is performed, using about 3.8 million hadronic Z decays recorded with the ALEPH detector at LEP. A clear signal is observed in the channels B→DsD¯(X)B→DsD¯(X) and B→DD¯(X)B→DD¯(X) (where D can be either a D00, a D++ or a D∗+∗+), providing the first direct evidence for doubly-charmed B decays involving no DsDs production. Evidence for associated K0SKS0 and K±K± production in the decays B→DD¯(X)B→DD¯(X) is also presented and some candidates for completely reconstructed decays B→DsD¯(nπ)B→DsD¯(nπ), B→DD¯K0SB→DD¯KS0 and B→DD¯K±B→DD¯K± are observed. Furthermore, candidates for the two-body Cabibbo suppressed decays B0→D∗−D∗+B0→D∗−D∗+ and …


The Effect Of Data Model, System And Task Characteristics On User Query Performance – An Empirical Study, Hock Chan, Keng Siau, Kwok-Kee Wei Dec 1997

The Effect Of Data Model, System And Task Characteristics On User Query Performance – An Empirical Study, Hock Chan, Keng Siau, Kwok-Kee Wei

Research Collection School Of Computing and Information Systems

With the proliferation of end-user computing and empowerment of end users in the organizations, the user-database interface is increasingly being recognized as an important research area. A user-database interface consists of two key components: the data model and the query language. Database management system designers can manipulate these two components to produce an effective database interface to maximize user task performance. However, in order to do this, the designers first need to know the effect of the two components on end users and the interaction effect of the two components. Despite the acknowledgment of user-database interface as a cornerstone in …


Inclusive Production Of Neutral Pions In Hadronic Z Decays, R. Barate, M. Thulasidas Dec 1997

Inclusive Production Of Neutral Pions In Hadronic Z Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A measurement of the inclusive production of π0 mesons in hadronic Z decays is presented and compared to Monte Carlo model predictions. The analysis is based on approximately 2 million hadronic events recorded with the ALEPH detector at LEP at a centre-of-mass energy of ⊡s = 91.2 GeV. Neutral pions are reconstructed using photons measured in the electromagnetic calorimeter and photons from conversion pairs. The inclusive π0 momentum spectrum is measured in the range 0.025 x p = p/p beam 0 per hadronic Z is found to be 4.80 ± 0.07(stat) ± 0.31(sys). The differential inclusive π0 cross section is …


Updated Measurement Of The Τ Lepton Lifetime, R. Barate, Manoj Thulasidas Nov 1997

Updated Measurement Of The Τ Lepton Lifetime, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

A new measurement of the mean lifetime of the τ lepton is presented. Three different analysis methods are applied to a sample of 90000 τ pairs, collected in 1993 and 1994 with the ALEPH detector at LEP. The average of this measurement and those previously published by ALEPH is ττ = 290.1±1.5±1.1fs.