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Showing papers by "Indian Institute of Technology Bombay published in 2004"


Journal ArticleDOI
TL;DR: Influence of different parameters such as molecular structure, temperature, salt concentration, and salt concentration that are very important in surfactant adsorption are reviewed here.

901 citations


Book ChapterDOI
26 May 2004
TL;DR: A new technique for combining text features and features indicating relationships between classes, which can be used with any discriminative algorithm is presented, which beat accuracy of existing methods with statistically significant improvements.
Abstract: In this paper we present methods of enhancing existing discriminative classifiers for multi-labeled predictions. Discriminative methods like support vector machines perform very well for uni-labeled text classification tasks. Multi-labeled classification is a harder task subject to relatively less attention. In the multi-labeled setting, classes are often related to each other or part of a is-a hierarchy. We present a new technique for combining text features and features indicating relationships between classes, which can be used with any discriminative algorithm. We also present two enhancements to the margin of SVMs for building better models in the presence of overlapping classes. We present results of experiments on real world text benchmark datasets. Our new methods beat accuracy of existing methods with statistically significant improvements.

746 citations


Proceedings Article
01 Dec 2004
TL;DR: Intuitively, a semi-CRF on an input sequence x outputs a "segmentation" of x, in which labels are assigned to segments rather than to individual elements of xi, and transitions within a segment can be non-Markovian.
Abstract: We describe semi-Markov conditional random fields (semi-CRFs), a conditionally trained version of semi-Markov chains. Intuitively, a semi-CRF on an input sequence x outputs a "segmentation" of x, in which labels are assigned to segments (i.e., subsequences) of x rather than to individual elements xi of x. Importantly, features for semi-CRFs can measure properties of segments, and transitions within a segment can be non-Markovian. In spite of this additional power, exact learning and inference algorithms for semi-CRFs are polynomial-time—often only a small constant factor slower than conventional CRFs. In experiments on five named entity recognition problems, semi-CRFs generally outperform conventional CRFs.

714 citations


Journal ArticleDOI
TL;DR: Electrocoagulation has been evaluated as a treatment technology for arsenite and arsenate removal from water and revealed that EC has better removal efficiency for As(III), whereas As(V) removal by both processes was nearly same.

576 citations


Proceedings ArticleDOI
13 Jun 2004
TL;DR: This paper presents an efficient, scalable and general algorithm for performing set joins on predicates involving various similarity measures like intersect size, Jaccard-coefficient, cosine similarity, and edit-distance that generalize to several weighted and unweighted measures of partial word overlap between sets.
Abstract: In this paper we present an efficient, scalable and general algorithm for performing set joins on predicates involving various similarity measures like intersect size, Jaccard-coefficient, cosine similarity, and edit-distance. This expands the existing suite of algorithms for set joins on simpler predicates such as, set containment, equality and non-zero overlap. We start with a basic inverted index based probing method and add a sequence of optimizations that result in one to two orders of magnitude improvement in running time. The algorithm folds in a data partitioning strategy that can work efficiently with an index compressed to fit in any available amount of main memory. The optimizations used in our algorithm generalize to several weighted and unweighted measures of partial word overlap between sets.

376 citations


Proceedings ArticleDOI
13 Jun 2004
TL;DR: In this paper, a fine-grained access control model based on authorization views is presented, where user queries can be phrased in terms of the database relations, and are valid if they can be answered using only the information contained in these authorization views.
Abstract: Current day database applications, with large numbers of users, require fine-grained access control mechanisms, at the level of individual tuples, not just entire relations/views, to control which parts of the data can be accessed by each user. Fine-grained access control is often enforced in the application code, which has numerous drawbacks; these can be avoided by specifying/enforcing access control at the database level. We present a novel fine-grained access control model based on authorization views that allows "authorization-transparent" querying; that is, user queries can be phrased in terms of the database relations, and are valid if they can be answered using only the information contained in these authorization views. We extend earlier work on authorization-transparent querying by introducing a new notion of validity, conditional validity. We give a powerful set of inference rules to check for query validity. We demonstrate the practicality of our techniques by describing how an existing query optimizer can be extended to perform access control checks by incorporating these inference rules.

371 citations


Posted Content
TL;DR: In this paper, a review of literature at the firm level and study of competitiveness-related frameworks and models is presented, where key criteria and sources of competitiveness are synthesized and depicted graphically as connotations of competitiveness.
Abstract: Turbulent start of the new century has brought new challenges for firms, industries and countries. Success in such times is demanding new perspectives on competitiveness: the ability to compete. Detailed structuring of competitiveness related problems of software firms in India identified weaknesses in understanding about the concept and its implementation as root causes. Review of competitiveness-related literature, by classifying it at three levels, clearly indicated the importance of the firm level. The focus of this paper is on review of literature at the firm level and study of competitiveness-related frameworks and models. The studies are further classified on the Asset – Processes – Performance (APP) framework. Key criteria and sources of competitiveness at the firm level are synthesized and depicted graphically as connotations of competitiveness. Select frameworks and models of competitiveness were reviewed and categorized. A sample matrix that can help select frameworks and models is demonstrated. Utility of the APP framework as a tool for integration competitiveness and strategy is explored. Finally, learning from the review and their implications are listed.

366 citations


Journal ArticleDOI
TL;DR: In this article, the ballistic impact behavior of two-dimensional woven fabric composites has been investigated and different damage and energy absorbing mechanisms during ballistic impact have been identified, including deformation of primary yarns, delamination, matrix cracking, shear plugging and friction during penetration.

296 citations


Proceedings ArticleDOI
22 Aug 2004
TL;DR: A semi-Markov extraction process is formalized, which is based on sequentially classifying segments of several adjacent words, rather than single words, and provides a more natural formulation of the NER problem than sequential word classification.
Abstract: We consider the problem of improving named entity recognition (NER) systems by using external dictionaries---more specifically, the problem of extending state-of-the-art NER systems by incorporating information about the similarity of extracted entities to entities in an external dictionary. This is difficult because most high-performance named entity recognition systems operate by sequentially classifying words as to whether or not they participate in an entity name; however, the most useful similarity measures score entire candidate names. To correct this mismatch we formalize a semi-Markov extraction process, which is based on sequentially classifying segments of several adjacent words, rather than single words. In addition to allowing a natural way of coupling high-performance NER methods and high-performance similarity functions, this formalism also allows the direct use of other useful entity-level features, and provides a more natural formulation of the NER problem than sequential word classification. Experiments in multiple domains show that the new model can substantially improve extraction performance over previous methods for using external dictionaries in NER.

258 citations


Journal ArticleDOI
TL;DR: In this article, the authors report on the effects of vacuum pyrolysis of deashed sugarcane bagasse, on the performance of pyrolyses of the products.
Abstract: This paper reports the studies made on the vacuum pyrolysis of deashed sugarcane bagasse, on the pyrolysis products. The present work is with an objective to understand the change in the quantity and quality of the oil fraction obtained from pyrolysis, upon pretreatment for deashing of original biomass. Ash, in the entrained char is believed to be catalyzing the polymerization reaction in the oils and thereby increases the viscosity. Three different pre-treatment processes used for deashing are water leaching, mild acid treatment with HCl and mild acid treatment with HF.1 The study indicates the remarkable influence of pretreatment process for deashing, by enhancing the total energy distribution in oil fraction of the pyrolysis products. This is attributed to selective removal of ash elements along with removal of extractives and hemicellulose in different proportions. However, it was found that the pre-treatments do not improve the stability of oil. The water leachate, as expected, showed potential of making ethanol via fermentation.

231 citations


Proceedings ArticleDOI
13 Jun 2004
TL;DR: This paper provides an elegant definition of relaxation on structure and defines primitive operators to span the space of relaxations for ranking schemes and proposes natural ranking schemes that adhere to these principles.
Abstract: Querying XML data is a well-explored topic with powerful database-style query languages such as XPath and XQuery set to become W3C standards. An equally compelling paradigm for querying XML documents is full-text search on textual content. In this paper, we study fundamental challenges that arise when we try to integrate these two querying paradigms.While keyword search is based on approximate matching, XPath has exact match semantics. We address this mismatch by considering queries on structure as a "template", and looking for answers that best match this template and the full-text search. To achieve this, we provide an elegant definition of relaxation on structure and define primitive operators to span the space of relaxations. Query answering is now based on ranking potential answers on structural and full-text search conditions. We set out certain desirable principles for ranking schemes and propose natural ranking schemes that adhere to these principles. We develop efficient algorithms for answering top-K queries and discuss results from a comprehensive set of experiments that demonstrate the utility and scalability of the proposed framework and algorithms.

Journal ArticleDOI
TL;DR: The benefits of cross-layer feedback on the mobile device and a representative survey are discussed and the proposed protocol stack would be useful to improve the efficiency of these protocol stacks.

Journal ArticleDOI
TL;DR: Besides robotics, applications such as medical patient monitoring, programmed stock trading, and military command and control systems like submarine contact tracking require timely actions as well as the ability to access and store complex data that reflects the state of the application's environment.
Abstract: Typically, a real–time system consists of a a controlling system and a controlled system. In an automated factory, the controlled system is the factory floor with its robots, assembling stations, and the assembled parts, while the controlling system is the computer and human interfaces that manage and coordinate the activities on the factory floor. Thus, the controlled system can be viewed as the environment with which the computer interacts. The controlling system interacts with its environment based on the data available about the environment, say from various sensors, e.g. temperature and pressure sensors. It is imperative that the state of the environment, as perceived by the controlling system, be consistent with the actual state of the environment. Otherwise, the effects of the controlling systems’ activities may be disastrous. Hence, timely monitoring of the environment as well as timely processing of the sensed information is necessary. The sensed data is processed further to derive new data. For example, the temperature and pressure information pertaining to a reaction may be used to derive the rate at which the reaction appears to be progressing. This derivation typically would depend on past temperature and pressure trends and so some of the needed information may have to be fetched from archival storage. Based on the derived data, where the derivation may involve multiple steps, actuator commands are set. For instance, in our example, the derived reaction rate is used to determine the amount of chemicals or coolant to be added to the reaction. In general, the history of (interactions with) the environment are also logged in archival storage. In addition to the timing constraints that arise from the need to continuously track the environment, timing correctness requirements in a real–time (database) system also arise because of the need to make data available to the controlling system for its decision-making activities. If the computer controlling a robot does not command it to stop or turn on time, the robot might collide with another object on the factory floor. Needless to say, such a mishap can result in a major catastrophe. Besides robotics, applications such as medical patient monitoring, programmed stock trading, and military command and control systems like submarine contact tracking require timely actions as well as the ability to access and store complex data that reflects the state of the application’s environment. That is, data in these applications must be valid, or fresh, when it is accessed in order for the application to perform correctly. In a patient monitoring system, data such as heart rate, temperature, and blood pressure must be collected periodically. Transactions that monitor the danger level of a patient’s status must be performed within a specified time, and the data must be accessed within an interval that defines the validity of the data. If not, the computations made by the transactions do not reflect the current state of the patient’s health. A traditional database provides some of the functionality required by these applications, such as coordination of concurrent actions and consistent access to shared data. But they do not provide for enforcement of the

Journal ArticleDOI
TL;DR: In this paper, the authors presented a critical review of daily flow simulation models based on the Soil Conservation Service curve number (SCS-CN), which specialized into seven cases.
Abstract: Presenting a critical review of daily flow simulation models based on the Soil Conservation Service curve number (SCS-CN), this paper introduces a more versatile model based on the modified SCS-CN method, which specializes into seven cases. The proposed model was applied to the Hemavati watershed (area = 600 km2) in India and was found to yield satisfactory results in both calibration and validation. The model conserved monthly and annual runoff volumes satisfactorily. A sensitivity analysis of the model parameters was performed, including the effect of variation in storm duration. Finally, to investigate the model components, all seven variants of the modified version were tested for their suitability. Copyright © 2004 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this article, the influence of isolator characteristics on the seismic response of multi-story base-isolated structure is investigated by using two different mathematical models depicted by bi-linear hysteretic and equivalent linear elastic-viscous behaviors.

Journal ArticleDOI
TL;DR: This paper surveys important approaches to active 3-D object recognition and reviews existing approaches towards another important application of an active sensor namely, that of scene analysis and interpretation.

Journal ArticleDOI
TL;DR: In this article, a semi-analytical method has been presented to evaluate the natural frequencies as well as displacement and stress eigenvectors for simply supported, cross-ply laminated and sandwich plates by using higher order mixed theory.

Journal ArticleDOI
TL;DR: In this paper, the impacts of increased pollutant concentration may affect the behavior of the Earth-atmosphere system, and large-scale changes in atmospheric composition are associated with changes in the Earth's radiative balance and climatic change.

Journal ArticleDOI
TL;DR: In this article, the apparent molar volumes of amino acids and peptides in aqueous SDS and CTAB solutions were calculated for a homologous series of amino acid classes.

Journal ArticleDOI
TL;DR: In this article, Sharma and Mahajani reviewed the very recent applications of reactive distillation and provided information on the ongoing research in the existing applications and newly discovered applications such as manufacture of phenol, linear alkyl benzene, carbonates, chlorosilane derivatives and chiral chemicals.
Abstract: Last few years have seen a dramatic rise in the number of applications of reactive distillation (RD). This useful technology is now being applied for any scale of operationfrom manufacture of fine chemicals to that of bulk chemicals. This article reviews the very recent applications and serves as a supplement for the exhaustive review on this subject by Sharma and Mahajani (2003). It not only furnishes the information on the ongoing research in the existing applications but also elaborates the newly discovered applications such as manufacture of phenol, linear alkyl benzene, carbonates, chlorosilane derivatives and chiral chemicals. Multiple reactions in RD, failure of RD in some cases and new RD configurations to increase the overall yields are some of the additional aspects being covered.

Journal ArticleDOI
TL;DR: Two parallel genetic algorithm (PGA) models for TRND problem for urban bus operation are proposed and it is observed that the global PVM model performed better than the other model.
Abstract: A transit route network design (TRND) problem for urban bus operation involves the determination of a set of transit routes and the associated frequencies that achieve the desired objective. This can be formulated as an optimization problem of minimizing the total system cost, which is the sum of the operating cost and the generalized travel cost. A review of previous approaches to solve this problem reveals the deficiency of conventional optimization techniques and the suitability of genetic algorithm (GA) based models to handle such combinatorial optimization problems. Since GAs are computationally intensive optimization techniques, their application to large and complex problems is limited. The computational performance of a GA model can be improved by exploiting its inherent parallel nature. Accordingly, two parallel genetic algorithm (PGA) models are proposed in this study. The first is a global parallel virtual machine (PVM) parallel GA model where the fitness evaluation is done concurrently in a parallel processing environment using PVM libraries. The second is a global message passing interface (MPI) parallel GA model where an MPI environment substitutes for the PVM libraries. An existing GA model for TRND for a large city is used as a case study. These models are tested for computation time, speedup, and efficiency. From the study, it is observed that the global PVM model performed better than the other model.

Journal ArticleDOI
TL;DR: The greater than expected actions of benomyl on mammalian microtubules and mitosis together with its relatively low toxicity suggest that it might be useful as an adjuvant in cancer chemotherapy.
Abstract: The antifungal agent benomyl [methyl-1-(butylcarbamoyl)-2-benzimidazolecarbamate] is used throughout the world against a wide range of agricultural fungal diseases. In this paper, we investigated the interaction of benomyl with mammalian brain tubulin and microtubules. Using the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulfonic acid, benomyl was found to bind to brain tubulin with a dissociation constant of 11.9 +/- 1.2 microM. Further, benomyl bound to at a novel site, distinct from the well-characterized colchicine and vinblastine binding sites. Benomyl altered the far-UV circular dichroism spectrum of tubulin and reduced the accessibility of its cysteine residues to modification by 5,5'-dithiobis-2-nitrobenzoic acid, indicating that benomyl binding to tubulin induces a conformational change in the tubulin. Benomyl inhibited the polymerization of brain tubulin into microtubules, with 50% inhibition occurring at a concentration of 70-75 microM. Furthermore, it strongly suppressed the dynamic instability behavior of individual brain microtubules in vitro as determined by video microscopy. It reduced the growing and shortening rates of the microtubules but did not alter the catastrophe or rescue frequencies. The unexpected potency of benomyl against mammalian microtubule polymerization and dynamics prompted us to investigate the effects of benomyl on HeLa cell proliferation and mitosis. Benomyl inhibited proliferation of the cells with an IC(50) of 5 microM, and it blocked mitotic spindle function by perturbing microtubule and chromosome organization. The greater than expected actions of benomyl on mammalian microtubules and mitosis together with its relatively low toxicity suggest that it might be useful as an adjuvant in cancer chemotherapy.

Journal ArticleDOI
TL;DR: In this article, the impact of seismic isolation on the peak response of isolated bridges was investigated by solving the governing equations of motion in the incremental form using an iterative step-by-step method.
Abstract: The response of bridges seismically isolated by lead-rubber bearings (L-RB) to bidirectional earthquake excitation (i.e., 2 horizontal components) is presented. The force-deformation behavior of L-RB is considered as bilinear, and the interaction between the restoring forces in 2 orthogonal horizontal directions is duly considered in the response analysis. The specific purpose of the study is to assess the effects of seismic isolation on the peak response of the bridges, and to investigate the effects of the bidirectional interaction of restoring forces of isolation bearings. The seismic response of the lumped mass model of continuous span isolated bridges is obtained by solving the governing equations of motion in the incremental form using an iterative step-by-step method. To study the effectiveness of L-RB, the seismic response of isolated bridges is compared with the response of corresponding nonisolated bridges (i.e., bridges without isolation devices). A comparison of the response of the isolated bridges obtained by considering and ignoring the bidirectional interaction of bearing forces is made under important parametric variation. The important parameters included are the flexibility of bridge piers and the stiffness and yield strength of the L-RB. Results show the bidirectional interaction of the restoring forces of the L-RB has considerable effects on the seismic response of isolated bridges. If these interaction effects are ignored, then the peak bearing displacements are underestimated which can be crucial from a design point of view.

Journal ArticleDOI
Joseph Adams1, Madan M. Aggarwal2, Zubayer Ahammed3, J. Amonett4  +367 moreInstitutions (43)
TL;DR: Results on high transverse momentum charged particle emission with respect to the reaction plane are presented and stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane.
Abstract: Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching.

Journal ArticleDOI
TL;DR: The interaction of 3,5-diisopropylsalicylic acid (DIPSA) with benzene proceeds with elimination of water to produce stannoxane [nBu2Sn(3,5iPr2C6H2(O)(COO))]6 (1), while an analogous...

Proceedings ArticleDOI
30 Mar 2004
TL;DR: This work proposes a novel approach, next-of-kin (NoK) pattern matching, to speed up the node-selection step, and to reduce the join size significantly in the second step, to efficiently perform NoK pattern matching.
Abstract: Path expressions are ubiquitous in XML processing languages. Existing approaches evaluate a path expression by selecting nodes that satisfies the tag-name and value constraints and then joining them according to the structural constraints. We propose a novel approach, next-of-kin (NoK) pattern matching, to speed up the node-selection step, and to reduce the join size significantly in the second step. To efficiently perform NoK pattern matching, we also propose a succinct XML physical storage scheme that is adaptive to updates and streaming XML as well. Our performance results demonstrate that the proposed storage scheme and path evaluation algorithm is highly efficient and outperforms the other tested systems in most cases.

Journal ArticleDOI
TL;DR: ES1 cultures isolated from Arabian Sea sediments obtained from the vicinity of an oil field could utilize diesel as the sole source of carbon and energy and has good potential for decontamination of oil-contaminated marine and subsurface environments.

Journal ArticleDOI
TL;DR: In this paper, a simple C 0 isoparametric finite element formulation based on a shear deformable model of higher-order theory using a higher order facet shell element is presented for the free vibration analysis of isotropic, orthotropic and layered anisotropic composite and sandwich laminates.

Journal ArticleDOI
TL;DR: In nurses occupational stress appears to vary according to individual and job characteristics, and work-family conflict, and the effects, moderating influences, coping mechanisms and risk factors associated with shift work are considered.
Abstract: This paper explores nurses’ occupational stressors and coping mechanisms. In nurses occupational stress appears to vary according to individual and job characteristics, and work-family conflict. Co...

Journal ArticleDOI
J. Adams1, C. Adler2, Madan M. Aggarwal2, Zubayer Ahammed3, C. Allgower4, J. Amonett5, B. D. Anderson4, Michael W. Anderson, D. Arkhipkin4, G. S. Averichev4, Y. Bai, J. Balewski6, O. Barannikova7, Lee Stuart Barnby1, J. Baudot, S. Bekele8, V. V. Belaga4, R. Bellwied9, J. Berger10, H. Bichsel11, A. Billmeier9, L. C. Bland12, C. O. Blyth1, B. E. Bonner13, A. Boucham, A. V. Brandin14, A. Bravar12, R. V. Cadman15, H. Caines, M. Calderon De La Barca Sanchez12, A. Cardenas, J. Carroll16, J. Castillo16, M. Castro16, D. Cebra17, P. Chaloupka18, S. Chattopadhyay19, Yu Chen20, S.P. Chernenko3, M. Cherney21, A. Chikanian22, B. Choi23, W. Christie12, J. P. Coffin, Thomas Michael Cormier9, M.M. Corral, J. G. Cramer11, Hank Crawford24, W.S. Deng24, A. A. Derevschikov, L. Didenko12, T. Dietel25, J. E. Draper17, V. B. Dunin4, J. C. Dunlop12, V. Eckardt26, L. G. Efimov4, V. Emelianov14, J. Engelage24, G. Eppley13, B. Erazmus, P. Fachini12, V. Faine3, Julien Faivre, R. Fatemi6, K. Filimonov16, E. Finch22, Y. Fisyak12, D. Flierl13, K. J. Foley12, J. Fu23, C. A. Gagliardi27, N.D. Gagunashvili, J. Gans22, L. Gaudichet, M. Germain16, F. Geurts13, V. Ghazikhanian20, O. A. Grachov9, V. Grigoriev12, M. Guedon12, S. M. Guertin20, E. Gushin23, T. J. Hallman12, D. Hardtke22, J. W. Harris3, M. Heinz, T.W. Henry13, S. Heppelmann20, T. Herston3, Boris Hippolyte20, A. Hirsch9, E. Hjort, Gerald W Hoffmann28, M. Horsley20, H. Z. Huang9, Thomas Humanic29, G. Igo17, A. Ishihara12, Yu. Ivanshin, Peter Martin Jacobs, William Jacobs, Malgorzata Anna Janik, Ian Johnson, P. G. Jones, E. G. Judd, Masashi Kaneta, Morton Kaplan, D. Keane, J. Kiryluk, Adam Ryszard Kisiel, J. L. Klay, S. R. Klein, A. Klyachko, Thorsten Sven Kollegger, A. S. Konstantinov, S.M. Kopytine, L. Kotchenda, Alexander Kovalenko, Michael Kramer, P. Kravtsov, K. Krueger, Christian Claude Kuhn, A. I. Kulikov, Gerd Joachim Kunde, C. L. Kunz, R. K. Kutuev, A. A. Kuznetsov, M. A.C. Lamont, J. M. Landgraf, S. Lange, C. P. Lansdell, B. Lasiuk, F. Laue, J. Lauret, A. Lebedev, R. Lednicky, V. M. Leontiev, M. J. LeVine, Q. Li, S. J. Lindenbaum, Lisa, F. Liu, L. Liu, Z. Liu 
TL;DR: In this paper, the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair was presented.
Abstract: We present the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. The pair transverse momentum, p{sub T}, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The e{sup +} and e{sup -} p{sub T} spectra are similar, with no evidence for interference effects due to higher-order diagrams.