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1999

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Articles 2401 - 2430 of 2555

Full-Text Articles in Physical Sciences and Mathematics

Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, N. Dimakis, M-Ali Al-Akhras, Grant Bunker Jan 1999

Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, N. Dimakis, M-Ali Al-Akhras, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

This paper describes recent results using our approach to calculating self-consistently single (SS) and multiple-scattering (MS) Debye- Waller factors (DWF) on active sites of metalloproteins. The calculation of MS DWF, together with the Feff7 program allows us to simulate ab-initio EXAFS spectra for a given temperature systems with no adjustable parameters. In our latest report (Dimakis N., and Bunker G., 1998) we calculate, using density functional and semiempirical approaches, the SS and MS DWF for small molecules and compared them to Raman, infrared and EXAFS spectra. In this report calculation of DWFs is done for tetrahedral Zn imidazole, a complex …

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Polymer Depletion Effects Near Mesoscopic Particles, Andreas Hanke, E. Eisenriegler, S. Dietrich Jan 1999

Polymer Depletion Effects Near Mesoscopic Particles, Andreas Hanke, E. Eisenriegler, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

The behavior of mesoscopic particles dissolved in a dilute solution of long, flexible, and nonadsorbing polymer chains is studied by field-theoretic methods. For spherical and cylindrical particles the solvation free energy for immersing a single particle in the solution is calculated explicitly. Important features are qualitatively different for self-avoiding polymer chains as compared with ideal chains. The results corroborate the validity of the Helfrich-type curvature expansion for general particle shapes and allow for quantitative experimental tests. For the effective interactions between a small sphere and a wall, between a thin rod and a wall, and between two small spheres, quantitative …

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Smarandache Type Functions Obtained By Duality, Florentin Smarandache, C Dumitrescu, N Varlan, St Zamfir, E Radescu, N Radescu Jan 1999

Smarandache Type Functions Obtained By Duality, Florentin Smarandache, C Dumitrescu, N Varlan, St Zamfir, E Radescu, N Radescu

Branch Mathematics and Statistics Faculty and Staff Publications

we extend the Smarandache function from the set N* of positive integers to the set Q of rationals

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Compositions Of Darboux And Connectivity Functions, Krzysztof Ciesielski Jan 1999

Compositions Of Darboux And Connectivity Functions, Krzysztof Ciesielski

Faculty & Staff Scholarship

We describe here an example of a Darboux function k from the unit interval I = [0, 1] onto itself such that k is not the composition of any finite collection of connectivity functions from I into I. This answers a question of Ceder [2].

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Uniformly Antisymmetric Function With Bounded Range, Krzysztof Ciesielski Jan 1999

Uniformly Antisymmetric Function With Bounded Range, Krzysztof Ciesielski

Faculty & Staff Scholarship

The goal of this note is to construct a uniformly antisymmetric function f : R → R with a bounded countable range. This answers Problem 1(b) of Ciesielski and Larson [6]. (See also the list of problems in Thomson [9] and Problem 2(b) from Ciesielski’s survey [5].) A problem of existence of uniformly antisymmetric function f : R → R with finite range remains open.

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Measurement Of The Hadronic Photon Structure Function At Lep 1 For 〈Q2〉 Values Between 9.9 And 284 Gev2, Barate, R.; Et Al., M. Thulasidas Jan 1999

Measurement Of The Hadronic Photon Structure Function At Lep 1 For 〈Q2〉 Values Between 9.9 And 284 Gev2, Barate, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

Inclusive γ∗γ interactions to hadronic final states where one scattered electron or positron is detected in the electromagnetic calorimeters have been studied in the LEP 1 data taken by ALEPH from 1991 to 1995. The event sample has been used to measure the hadronic structure function of the photon F2γ in three bins with 〈Q2〉 of 9.9, 20.7 and 284 GeV2.

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Decision Analytic Approach To Severe Head Injury Management., Harmanec D., Tze-Yun Leong, Sundaresh S., Poh K., Yeo T., Ng I., Lew T. Jan 1999

Decision Analytic Approach To Severe Head Injury Management., Harmanec D., Tze-Yun Leong, Sundaresh S., Poh K., Yeo T., Ng I., Lew T.

Research Collection School Of Computing and Information Systems

Severe head injury management in the intensive care unit is extremely challenging due to the complex domain, the uncertain intervention efficacies, and the time-critical setting. We adopt a decision analytic approach to automate the management process. We document our experience in building a simplified influence diagram that involves about 3000 numerical parameters. We identify the inherent problems in structuring a model with unclear domain relationships, numerous interacting variables, and real-time multiple inputs. We analyze the effectiveness and limitations of the decision analytic approach and present a set of desiderata for effective knowledge acquisition in this setting. We also propose a …

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Artificial Societies: A Computational Approach To Studying Combat, Rachel J. Moore Jan 1999

Artificial Societies: A Computational Approach To Studying Combat, Rachel J. Moore

Dissertations, Theses, and Masters Projects

No abstract provided.

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Fabrications And Characterizations Of Boron Containing Polyimides For Radiation Shielding, Christopher Scott Pugh Jan 1999

Fabrications And Characterizations Of Boron Containing Polyimides For Radiation Shielding, Christopher Scott Pugh

Dissertations, Theses, and Masters Projects

No abstract provided.

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The Photochemistry Of Thiobenzoyl Derivatives Of Methyl Benzylidene-Alpha-D-Glucopyranoside, Adam Louis Schreiber Jan 1999

The Photochemistry Of Thiobenzoyl Derivatives Of Methyl Benzylidene-Alpha-D-Glucopyranoside, Adam Louis Schreiber

Dissertations, Theses, and Masters Projects

No abstract provided.

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Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Imidazole Based Ligands By X-Ray Crystallography And Nmr Spectroscopy, Geoffrey Murphy Jan 1999

Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Imidazole Based Ligands By X-Ray Crystallography And Nmr Spectroscopy, Geoffrey Murphy

Dissertations, Theses, and Masters Projects

No abstract provided.

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Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna Jan 1999

Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna

Dissertations, Theses, and Masters Projects

To investigate the relationship between biological and physical mixing in forming strata, the lower mainstem of Chesapeake Bay has been contrasted with the York River Subestuary. By using radioisotope profiles from sediment cores, comparisons are made in terms of depth and rate of sediment mixing, deposition and accretion. Within the lower Chesapeake Bay two sites were selected as biologically dominated, both are located within the bay stem plains and are characterized by muddy sand and an abundance of large, deep-dwelling organisms. X-radiographs indicate complete biological reworking of sediments. 210Pb profiles reveal low sediment accretion rates within the mainstem sites ( …

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Nitrate Reduction At The Groundwater - Salt Marsh Interface, Craig -1967 Tobias Jan 1999

Nitrate Reduction At The Groundwater - Salt Marsh Interface, Craig -1967 Tobias

Dissertations, Theses, and Masters Projects

The influence of groundwater discharge on the hydrology and biogeochemical cycling of nitrogen in a fringing intertidal wetland was studied by characterizing groundwater discharge, determining N-cycling rates in cores, and examining nitrate reduction in situ using 15N enrichment and natural gradient tracer techniques. Groundwater discharge was estimated by three independent methods: Darcy's Law, a water/salt mass balance, and a subsurface tracer test. Seasonal patterns of discharge predicted by Darcy's Law and the mass balance were similar. Discharge maxima and minima occurred in April and September, respectively. The water/salt mass balance provided the more reasonable estimate of groundwater flux at high …

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Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald Jan 1999

Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald

Dissertations, Theses, and Masters Projects

No abstract provided.

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Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church Jan 1999

Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church

Dissertations, Theses, and Masters Projects

No abstract provided.

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Environmental Stress In Hard Coral: Evaluating Lipid As An Indicator Of Sublethal Stress On Short Time Scales, David Harold Niebuhr Jan 1999

Environmental Stress In Hard Coral: Evaluating Lipid As An Indicator Of Sublethal Stress On Short Time Scales, David Harold Niebuhr

Dissertations, Theses, and Masters Projects

Lipid quality was evaluated in Montastrea spp. under sediment- and heat-stressed conditions to evaluate lipid ratio as an indicator of sub-lethal stress on short time scales. The ratio of storage lipid (wax ester + triacylglyceride) to structural lipid (sterol esters + phospholipid) decreased significantly (0.25 to 0.14, p < 0.01) after experimental sedimentation. FAME analysis of colonies exposed to experimental sedimentation showed a reduction of the algal, 18:3(n-6) and 18:4(n-3), polyunsaturated fatty acid (PUFA) in the polar lipid fraction. This loss of PUFA suggests a loss of algal membrane in sediment-stressed colonies. Lipid quality was similarly measured in M. faveolata over a 10-day period. Mean (n = 20) ratio of storage to structural lipid in M. faveolata dropped from 2.43 to a level of 0.98 immediately following a natural sedimentation event before recovering to levels of 1.4 and 2.9 on post-storm days 2 and 4, respectively. Colonies of M. annularis subject to heat-stress (35??C) exhibited no significant change in storage lipid ratio, while levels of Free Fatty Acids increased significantly from 0.012 (n = 22) to 0.156 mg lipid/g dry tissue (n = 22)(p < 0.05). FAME analysis of tissue lipids extracted from the heat-stressed colonies showed changes in the polar fraction, with significant decreases in the 18:3(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6) and 20:5(n-3) (p < 0.05) PUFA and subsequent significant increases in the saturated fatty acids, 16:0 and 18:0 (p < 0.05). These changes in lipid quantity and quality indicate possible oxidation and preferential digestion of zooxanthellar membranes. Stress experiments were repeated in M. annularis using VacutainerRTM blood collection tubes to collect micro-tissue samples without destroying skeleton of the sample colonies. A significant decrease in storage: structural lipid ratio after sedimentation was also detected using the micro-tissue technique. This study indicates that the relative abundance of lipid subclass components can indicate sub-lethal environmental stress, on short time scales, in M. annularis and M. faveolata. Furthermore, micro-tissue collection techniques permit repeated monitoring coral colonies to assess the manifestation of stress from first detection of impact at the cellular level to changes in community to changes in community structure detectable over longer time scales.

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Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr. Jan 1999

Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr.

Dissertations, Theses, and Masters Projects

Situated in the Bengal Basin, the Ganges-Brahmaputra river delta comprises one of the largest fluviodeltaic systems in the world, comprising ∼ 100,000 km2 of floodplain and delta plain and a 40,000 km2 subaqueous delta on the shelf. Sediment load of the Ganges-Brahmaputra river is 109 t/yr, and seasonal flooding may inundate >70% of the delta during large events. Active tectonic processes have resulted in both uplift and subsidence in this structurally complex region. These general characteristics suggest that the Ganges-Brahmaputra delta represents a heretofore undescribed delta end-member, forming along a high-yield, high-energy, tectonically active margin. to investigate this view, stratigraphic, …

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Totally Nonnegative Matrices, Shaun M. Fallat Jan 1999

Totally Nonnegative Matrices, Shaun M. Fallat

Dissertations, Theses, and Masters Projects

An m-by-n matrix A is called totally nonnegative (resp. totally positive) if the determinant of every square submatrix (i.e., minor) of A is nonnegative (resp. positive). The class of totally nonnegative matrices has been studied considerably, and this class arises in a variety of applications such as differential equations, statistics, mathematical biology, approximation theory, integral equations and combinatorics. The main purpose of this thesis is to investigate several aspects of totally nonnegative matrices such as spectral problems, determinantal inequalities, factorizations and entry-wise products. It is well-known that the eigenvalues of a totally nonnegative matrix are nonnegative. However, there are many …

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Experimental And Computational Techniques In Carbon-13 Nmr, Samuel John Varner Jan 1999

Experimental And Computational Techniques In Carbon-13 Nmr, Samuel John Varner

Dissertations, Theses, and Masters Projects

An efficient method for calculating NMR lineshapes from anisotropic second rank tensor interactions is presented. The algorithm produces lineshapes from asymmetric tensors by summing those from symmetric tensors. This approach significantly reduces the calculation time, greatly facilitating iterative nonlinear least squares fitting of experimental spectra. This algorithm has been modified to produce partially relaxed lineshapes and spectra of partially ordered samples.;Calculations for rapidly spinning samples show that spin-lattice relaxation time ( T1Z ) anisotropy varies with the angle between the spinning axis and the external field. When the rate of molecular motion is in the extreme narrowing limit, measurement of …

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Harp: A Distributed Query System For Legacy Public Libraries And Structured Databases, Ee Peng Lim, Ying Lu Jan 1999

Harp: A Distributed Query System For Legacy Public Libraries And Structured Databases, Ee Peng Lim, Ying Lu

Research Collection School Of Computing and Information Systems

The main purpose of a digital library is to facilitate users easy access to enormous amount of globally networked information. Typically, this information includes preexisting public library catalog data, digitized document collections, and other databases. In this article, we describe the distributed query system of a digital library prototype system known as HARP. In the HARP project, we have designed and implemented a distributed query processor and its query front-end to support integrated queries to preexisting public library catalogs and structured databases. This article describes our experiences in the design of an extended Sequel (SQL) query language known as HarpSQL. …

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Web-Based Interlibrary Loan System, Ee Peng Lim, Schubert Foo, Cheng Hai Tan, Kwang-Yong Tan Jan 1999

Web-Based Interlibrary Loan System, Ee Peng Lim, Schubert Foo, Cheng Hai Tan, Kwang-Yong Tan

Research Collection School Of Computing and Information Systems

Interlibrary loan (ILL) system is one of the important library services provided by most public libraries. Through ILL, public libraries share their collections of reading material and library users are able to access library resources beyond their affiliated libraries. However, the present manual ILL process is inconvenient, inefficient and error-prone. In this project, we developed a system that automated many tedious procedures in the existing ILL system. The new ILL system is realized by a number of Java applets customized for librarians and library users. The new ILL system allows library users to submit ILL requests at any time using …

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The Steep Spectrum Quasar Pg1404+ 226 With Asca, Hst And Rosat, Marie-Helene Ulrich, Andrea Comastri, Stefanie Komossa, Phil Crane Jan 1999

The Steep Spectrum Quasar Pg1404+ 226 With Asca, Hst And Rosat, Marie-Helene Ulrich, Andrea Comastri, Stefanie Komossa, Phil Crane

Dartmouth Scholarship

We present and discuss our observations of the Narrow Line quasar PG1404+226 (zem = 0.098) with ASCA and HST, and a re-analysis of our earlier observa- tions with ROSAT. The soft X-ray spectrum is very steep and displays an absorption feature (edge or line at ∼ 1.1 keV). We have applied a variety of models to the ASCA and ROSAT spectra without finding a completely satis- factory fit, and the identification of the edge remains un- certain. A satisfactory fit of the ASCA spectrum assuming that the edge is produced by highly ionized iron (using the code absori in XSPEC) …

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Late-Time Optical And Ultraviolet Spectra Of Sn 1979c And Sn 1980k, Robert A. Fesen, Christopher L. Gerardy, Alexei V. Filippenko, Thomas Matheson, Roger A. Chevalier, Robert P. Kirshner, Brian P. Schmidt, Peter Challis, Claes Fransson, Bruno Leibundgut, Schuyler D. Van Dyk Jan 1999

Late-Time Optical And Ultraviolet Spectra Of Sn 1979c And Sn 1980k, Robert A. Fesen, Christopher L. Gerardy, Alexei V. Filippenko, Thomas Matheson, Roger A. Chevalier, Robert P. Kirshner, Brian P. Schmidt, Peter Challis, Claes Fransson, Bruno Leibundgut, Schuyler D. Van Dyk

Dartmouth Scholarship

A low-dispersion Keck I spectrum of SN 1980K taken in 1995 August (t = 14.8 yr after explosion) and a spectrum taken in 1997 November (t = 17.0 yr) at the MDM Observatory show broad 5500 km s-1 emission lines of Hα, [O I] 6300, 6364 Å, and [O II] 7319, 7330 Å. Weaker but similarly broad lines detected include [Fe II] 7155 Å, [S II] 4068, 4072 Å, and a blend of [Fe II] lines at 5050–5400 Å. The presence of strong [S II] 4068, 4072 Å emission but a lack of [S II] 6716, 6731 …

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Physical Control Of Biological Processes In The Central Equatorial Pacific: A Data Assimilative Modeling Study, Marjorie Anne Macwhorter Friedrichs Jan 1999

Physical Control Of Biological Processes In The Central Equatorial Pacific: A Data Assimilative Modeling Study, Marjorie Anne Macwhorter Friedrichs

OES Theses and Dissertations

A five-component data assimilative ecosystem model is developed in order to investigate the effects of physical processes encompassing a wide range of space and time scales, on the lower trophic levels of the highly dynamic central equatorial Pacific (140°W). Many of the biological processes included in the ecosystem model respond to environmental fluctuations with time scales between one and ten days, which are not typically resolved by basin to global scale circulation models. Therefore, the ecosystem model is forced using daily observations from the TAO mooring array. Model simulations successfully reproduce data collected both during and after the 1991–92 El …

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A Coupled Bio-Optical And Mixed Layer Model For The Equatorial Pacific, James Vincent Koziana Jan 1999

A Coupled Bio-Optical And Mixed Layer Model For The Equatorial Pacific, James Vincent Koziana

OES Theses and Dissertations

A one dimensional coupled bio-optical and mixed layer model is developed and applied to problems involving the role of phytoplankton-induced turbidity (PIT) on the vertical structure and heating of the upper ocean in the Equatorial Pacific Ocean. The bio-optical and mixed layer model for optically pure sea water was forced with climatological environmental conditions to provide a reference simulation for 140°W in the eastern Equatorial Pacific Ocean. This reference simulation was used for comparison to other simulations which considered the effects of variations in wind stress and solar input for a homogeneous chlorophyll a profile and variations in the magnitude …

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Reviewing Software As A Means Of Enhancing Instruction, Marcus D. Childress, Guang-Lea Lee, Gregory P. Sherman Jan 1999

Reviewing Software As A Means Of Enhancing Instruction, Marcus D. Childress, Guang-Lea Lee, Gregory P. Sherman

Teaching & Learning Faculty Publications

A software review procedure developed by the authors is described. The procedure centers around a form that extends the functionality of traditional software evaluation forms by enhancing the use of the computer software in the early childhood classroom. The form encourages teachers to discover ways a piece of software can be integrated across disciplines and used as an anchor for instruction. Users of the review form are also encouraged to examine ways the software motivates the user to remain engaged in its use. The majority of the review form emphasizes the important role of the teacher in identifying outcomes or …

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Apex: Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker Jan 1999

Apex: Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

We have developed version 1.0 of a freely available (including source code) suite of basic X-Ray Absorption Fine Structure (XAFS) data analysis programs for data reduction and single scattering analysis. This package is based on the University of Washington (UW/NRL) Fortran 77 programs that are available on the International XAFS Society (IXS) database, complemented by a graphical TCL/TK scripting language based user interface which runs virtually unchanged between platforms, using the native look and feel of the corresponding platform. The package has been tested on MacOS 8.1, Linux, IRIX, Windows95 and NT. Particular emphasis is placed on simplicity, reliability, and …

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Critical Adsorption On Curved Objects, Andreas Hanke, S. Dietrich Jan 1999

Critical Adsorption On Curved Objects, Andreas Hanke, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

A systematic field-theoretical description of critical adsorption on curved objects such as spherical or rodlike colloidal particles immersed in a fluid near criticality is presented. The temperature dependence of the corresponding order parameter profiles and of the excess adsorption are calculated explicitly. Critical adsorption on elongated rods is substantially more pronounced than on spherical particles. It turns out that, within the context of critical phenomena in confined geometries, critical adsorption on a microscopically thin ‘‘needle’’ represents a distinct universality class of its own. Under favorable conditions the results are relevant for the flocculation of colloidal particles.

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A Study Of Single W Production In E+E- Collisions At √S = 161-183 Gev, R. Barate, Manoj Thulasidas Jan 1999

A Study Of Single W Production In E+E- Collisions At √S = 161-183 Gev, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Single W production is studied in the data recorded with the ALEPH detector at LEP at centre-of-mass energies between 161 and 183 GeV. The cross section is measured to be σw = 0.41 ± 0.17(stat.) ± 0.04(syst.) pb at 183 GeV, consistent with the Standard Model expectation. Limits on non-standard WWγ couplings are deduced as -1.6 γ γ = 0) and -1.6 γ γ = 1) at 95% C.L. A search for effectively invisible decays of the W boson in W pair production is performed, leading to an upper limit on the branching ratio of 1.3% (Γinv = 27 MeV) …

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Determination Of |Vub| From The Measurement Of The Inclusive Charmless Semileptonic Branching Ratio Of B Hadrons, R. Barate, M. Thulasidas Jan 1999

Determination Of |Vub| From The Measurement Of The Inclusive Charmless Semileptonic Branching Ratio Of B Hadrons, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

From a study of the kinematic properties of the final state produced in the semileptonic decays b→Xℓνℓb→Xℓνℓ, the inclusive charmless semileptonic branching ratio of b hadrons is measured. With a sample of 3.6 million hadronic Z decays recorded between 1992 and 1995 with the ALEPH detector at LEP, the value Br(b→Xuℓνℓ)Br(b→Xuℓνℓ) is determined to be (1.73±0.55stat±0.55syst)×10−3(1.73±0.55stat±0.55syst)×10−3, where XuXu represents any charmless hadronic state and b is a mixture of b hadrons weighted by their production rates. This measurement yields the result|Vub|2=(18.68±5.94stat±5.94syst±1.45HQE)×10−6,|Vub|2=(18.68±5.94stat±5.94syst±1.45HQE)×10−6,where the last error comes from the conversion of the branching ratio to the CKM matrix element squared.

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