bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploiting the Natural Diversity in Adenovirus Tropism for Therapy and Prevention of Disease
Authors: Havenga M. J. E. , Lemckert A. A. C. , Ophorst O. J. A. E. , van Meijer M. , Germeraad W. T. V. , Grimbergen J. , van den Doel M. A. , Vogels R. , van Deutekom J. , Janson A. A. M. , de Bruijn J. D. , Uytdehaag F. , Quax P. H. A. , Logtenberg T. , Mehtali M. , Bout A. 
Published: July 2002

ABSTRACT
Since targeting of recombinant adenovirus vectors to defined cell types in vivo is a major challenge in gene therapy and vaccinology, we explored the natural diversity in human adenovirus tissue tropism. Hereto, we constructed a library of Ad5 vectors carrying fibers from other human serotypes. From this library, we identified vectors that efficiently infect human cells that are important for diverse gene therapy approaches and for induction of immunity. For several medical applications (prenatal diagnosis, artificial bone, vaccination, and cardiovascular disease), we demonstrate the applicability of these novel vectors. In addition, screening cell types derived from different species revealed that cellular receptors for human subgroup B adenoviruses are not conserved between rodents and primates. These results provide a rationale for utilizing elements of human adenovirus serotypes to generate chimeric vectors that improve our knowledge concerning adenovirus biology and widen the therapeutic window for vaccination and many different gene transfer applications.
Nef-Mediated Downregulation of CD4 Enhances Human Immunodeficiency Virus Type 1 Replication in Primary T Lymphocytes
Authors: Lundquist Christopher A. , Tobiume Minoru , Zhou Jing , Unutmaz Derya , Aiken Christopher 
Published: July 2002

ABSTRACT

The accessory protein Nef plays a crucial role in primate lentivirus pathogenesis. Nef enhances human immunodeficiency virus type 1 (HIV-1) infectivity in culture and stimulates viral replication in primary T cells. In this study, we investigated the relationship between HIV-1 replication efficiency in CD4
+
T cells purified from human blood and two various known activities of Nef, CD4 downregulation and single-cycle infectivity enhancement. Using a battery of reporter viruses containing point mutations in
nef
, we observed a strong genetic correlation between CD4 downregulation by Nef during acute HIV-1 infection of activated T cells and HIV-1 replication efficiency in T cells. In contrast, HIV-1 replication ability was not significantly correlated with the ability of Nef to enhance single-cycle virion infectivity, as determined by using viruses produced in cells lacking CD4. These results demonstrate that CD4 downregulation by Nef plays a crucial role in HIV-1 replication in activated T cells and underscore the potential for the development of therapies targeting this conserved activity of Nef.
Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence
Authors: Citarda F , Tomaselli G , Capocaccia R , Barcherini S , Crespi M , Group The Italian Multicentre Study 
Published: July 2002

BACKGROUNDColorectal cancer is one of the leading causes of death from cancer in Western countries. Removal of adenomas is based on the assumption that it could lead to a reduction in the incidence of colorectal cancer, as demonstrated by the National Polyp Study in the USA. A critical issue is whether the benefit observed in clinical trials can also be observed in standard clinical practice. To address the issue, a multicentre Italian collaborative study was organised.METHODSThe study cohort comprised 1693 subjects of both sexes, aged 40–69 years, enrolled between 1980 and 1987 following a total colon examination (TCE) (that is, total colonoscopy or colonoscopy and double contrast barium enema), with removal of at least one adenoma larger than 5 mm in diameter. Exclusion criteria were genetic syndromes, previous adenomas or colorectal cancer, previous colonic resection, inflammatory bowel disease, or sessile adenomas more than 3 cm in diameter. Follow up ended in December 1996 by TCE or telephone interview, and review of the medical records, clinical files, or death certificates. Incidence ratios for colorectal cancer were compared with expected age and sex specific incidences in the Italian general population.RESULTSFollow up data were obtained for 97.3% of cases for a total of 14 211 person/years. Mean follow up was 10.5 years. Six colorectal cancer cases (four in males, two in females) at various stages were ascertained (one at 29 months, two at five years, one at seven years, one at eight years, and one at 10 years from the index examination). The number of cancers expected in the reference population was 17.7 for an incidence ratio of 0.34 (confidence interval 0.23–0.63; p<0.01).CONCLUSIONSColonoscopic polypectomy substantially reduced the incidence of colorectal cancer in the cohort compared with that expected in the general population. These results are of particular relevance considering that those with adenomas are at increased risk of colorectal cancer and that this retrospective study was performed on data obtained in standard clinical practice. This observation strengthens the concept of effective population screening in view of the fact that adenomatous polyps are the most frequent neoplastic outcome of screening and their removal is associated with a decrease in the incidence of colorectal cancer.
The serodiagnosis of infection withSalmonella typhi
Authors: Chart H , Cheesbrough J S , Waghorn D J 
Published: July 2002

Background/Aims—The serodiagnosis of infection withSalmonella typhi,using the Widal agglutination assay, relies on patients' antibodies to the O=9,12 lipopolysaccharide (LPS) antigens, H=d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection withS typhi.In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens.Methods—The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation ofS typhi,ViI Bhatnagar variant strain (S typhi, ViI).Sera used in the study comprised 73 from patients who were culture positive forS typhi,10 from patients who were culture positive for other species ofSalmonellanot expressing a Vi antigen (namely,S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly,orS mbandaka), and eight from healthy blood donors.Results—Agglutination titres of ≥ 1/40 were detected toS typhiViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies toS. typhiViI in all eight control sera and seven sera from patients infected withS bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley.Conclusions—Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections withS typhishould be based on the detection of antibodies to both the O=9,12 LPS antigen and the H=d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.
Epidemiological study to investigate potential interaction between physical and psychosocial factors at work that may increase the risk of symptoms of musculoskeletal disorder of the neck and upper limb
Authors: Devereux J J , Vlachonikolis I G , Buckle P W 
Published: July 2002

Objectives: To investigate potential interactions between physical and psychosocial risk factors in the workplace that may be associated with symptoms of musculoskeletal disorder of the neck and upper limb.Methods: 891 of 1514 manual handlers, delivery drivers, technicians, customer services computer operators, and general office staff reported on physical and psychosocial working conditions and symptoms of neck and upper limb disorders using a self administered questionnaire (59% return rate). Of the 869 valid questionnaire respondents, 564 workers were classified in to one of four exposure groups: high physical and high psychosocial, high physical and low psychosocial, low physical and high psychosocial, and low physical and low psychosocial. Low physical and low psychosocial was used as an internal reference group. The exposure criteria were derived from the existing epidemiological literature and models for physical and psychosocial work factors. The frequency and amplitude of lifting and the duration spent sitting while experiencing vibration were used as physical exposure criteria. Ordinal values of mental demands, job control, and social support with managers and coworkers were used as psychosocial exposure criteria.Results: In the multivariate analyses, the highest and significant increase in risk was found in the high physical and high psychosocial exposure group for symptoms of hand or wrist and upper limb disorders after adjusting for years at the job, age, and sex. A potential interaction effect was found for the symptoms of the hand or wrist and upper limb disorders but not for the neck symptoms.Conclusion: This study showed that workers highly exposed to both physical and psychosocial workplace risk factors were more likely to report symptoms of musculoskeletal disorders than workers highly exposed to one or the other. The results suggest an interaction between physical and psychosocial risk factors in the workplace that increased the risk of reporting symptoms in the upper limbs. Psychosocial risk factors at work were more important when exposure to physical risk factors at work were high than when physical exposure was low. Ergonomic intervention strategies that aim to minimise the risks of work related musculoskeletal disorders of the upper limb should not only focus on physical work factors but also psychosocial work factors.
A TWO-DIMENSIONAL REPRESENTATION OF FOUR-DIMENSIONAL GRAVITATIONAL WAVES
Authors: SCHMIDT HANS-JÜRGEN 
Published: July 2002

The Einstein equation in D dimensions, if restricted to the class of spacetimes possessing n = D - 2 commuting hypersurface-orthogonal Killing vectors, can be equivalently written as metric-dilaton gravity in two dimensions with n scalar fields. For n = 2, this result reduces to the known reduction of certain four-dimensional metrics which include gravitational waves. Here, we give such a representation which leads to a new proof of the Birkhoff theorem for plane-symmetric spacetimes, and which leads to an explanation, in which sense two (spin zero-) scalar fields in two dimensions may incorporate the (spin two-) gravitational waves in four dimensions. (This result should not be mixed up with well–known analogous statements where, however, the four-dimensional spacetime is supposed to be spherically symmetric, and then, of course, the equivalent two-dimensional picture cannot mimic any gravitational waves.) Finally, remarks on hidden symmetries in two dimensions are made.
SURFACE SENSITIVITY OF VERY LOW ENERGY ELECTRONS
Authors: BARTOŠ I. , SCHATTKE W. 
Published: July 2002

The surface sensitivity of electron diffraction and of electron spectroscopies is determined by the imaginary component of the electron self-energy. In crystals, the energy and direction dependence of the electron attenuation and of the escape depth should be taken into account at very low energies. Strong anisotropy of the electron attenuation has been obtained around 20 eV from peak shapes in VLEED intensity profiles from (111) transition metal surfaces. Extension of the local density approximation in the density functional formalism provides quantitative description of the electron self-energy. The one-step model of angular resolved photoemission incorporating the self-energy predicts a strong energy and angle dependence of the escape depth of low energy photoelectrons emitted from GaAs(110).
Telos: representing knowledge about information systems
Authors: Mylopoulos John , Borgida Alex , Jarke Matthias , Koubarakis Manolis 
Published: July 2002

We describe Telos, a language intended to support the development of information systems. The design principles for the language are based on the premise that information system development is knowledge intensive and that the primary responsibility of any language intended for the task is to be able to formally represent the relevent knowledge. Accordingly, the proposed language is founded on concepts from knowledge representations. Indeed, the language is appropriate for representing knowledge about a variety of worlds related to a particular information system, such as the subject world (application domain), the usage world (user models, environments), the system world (software requirements, design), and the development world (teams, metodologies).
We introduce the features of the language through examples, focusing on those provided for desribing metaconcepts that can then be used to describe knowledge relevant to a particular information system. Telos' fetures include an object-centered framework which supports aggregation, generalization, and classification; a novel treatment of attributes; an explicit representation of time; and facilities for specifying integrity constraints and deductive rules. We review actual applications of the language through further examples, and we sketch a formalization of the language.
On stability and performance of parallel processing systems
Authors: Bambos Nicholas , Walrand Jean 
Published: July 2002

The general problem of parallel (concurrent) processing is investigated from a queuing theoretic point of view.As a basic simple model, consider infinitely many processors that can work simultaneously, and a stream of arriving jobs, each carrying a processing time requirement. Upon arrival, a job is allocated to a processor and starts being executed, unless it is blocked by another one already in the system. Indeed, any job can be randomly blocked by any preceding one, in the sense that it cannot start being processed before the one that blocks it leaves. After execution, the job leaves the system. The arrival times, the processing times and the blocking structures of the jobs form a stationary and ergodic sequence.The random precedence constraints capture the essential operational characteristic of parallel processing and allow a unified treatment of concurrent processing systems from such diverse areas as parallel computation, database concurrency control, queuing networks, flexible manufacturing systems. The above basic model includes the G/G/1 and G/G/∞ queuing systems as special extreme cases.Although there is an infinite number of processors, the precedence constraints induce a queuing phenomenon, which, depending on the loading conditions, can lead to stability or instability of the system.In this paper, the condition for stability of the system is first precisely specified. The asymptotic behavior, at large times, of the quantities associated with the performance of the system is then studied, and the degree of parallelism, expressed as the asymptotic average number of processors that work concurrently, is computed. Finally, various design and simulation aspects concerning parallel processing systems are considered, and the case of finite number of processors is discussed.The results proved for the basic model are then extended to cover more complex and realistic parallel processing systems, where each job has a random internal structure of subtasks to be executed according to some internal precedence constriants.
Massively parallel and distributed simulation of a class of discrete event systems
Authors: Vakili Pirooz 
Published: July 2002

In this paper we propose a new approach to parallel and distributed simulation of discrete event systems. Most parallel and distributed discrete event simulation algorithms are concerned with the simulation of one “large” discrete event system. In this case the computational intensity is due to the size and complexity of the simulated system. In contrast, we are interested in simulating a “large” number of “medium sized” systems. These are variants of a “nominal system” with different system parameter values or operation policies. The computational intensity in our case is due to the “large” number of simulated variants. Many simulation projects such as factor screening, performance modeling, and optimization require system performance evaluations at many parameter values; and others, we believe, could significantly benefit from them.
There is considerable work in the literature on stochastic coupling of trajectories of parametric families of stochastic processes. Our approach can be viewed as the simulation of the coupled trajectories. We use a single clock mechanism that drives all trajectories simultaneously, hence the approach is called Single Clock Multiple System (SCMS) simulation. The single clock synchronizes all trajectories such that the “same” event occurs at the “same” time at all systems. This synchronization is the basis of our parallel and distributed algorithms.
We focus on a particular implementation of the SCMS simulation using the so-called Standard Clock (SC) technique and also on the massively parallel implementation of the SC algorithms on the SIMD Connection Machine. Orders of magnitude of speedup is possible. Furthermore, the possibility of concurrent performance evaluation and comparison at many system parameter values offers new and significant opportunities for performance optimization.
Query evaluation techniques for large databases
Authors: Graefe Goetz 
Published: July 2002

Database management systems will continue to manage large data volumes. Thus, efficient algorithms for accessing and manipulating large sets and sequences will be required to provide acceptable performance. The advent of object-oriented and extensible database systems will not solve this problem. On the contrary, modern data models exacerbate the problem: In order to manipulate large sets of complex objects as efficiently as today's database systems manipulate simple records, query-processing algorithms and software will become more complex, and a solid understanding of algorithm and architectural issues is essential for the designer of database management software.This survey provides a foundation for the design and implementation of query execution facilities in new database management systems. It describes a wide array of practical query evaluation techniques for both relational and postrelational database systems, including iterative execution of complex query evaluation plans, the duality of sort- and hash-based set-matching algorithms, types of parallel query execution and their implementation, and special operators for emerging database application domains.
Contention resolution with constant expected delay
Authors: Goldberg Leslie Ann , Mackenzie Philip D. , Paterson Mike , Srinivasan Aravind 
Published: July 2002

We study contention resolution in a multiple-access channel such as the Ethernet channel. In the model that we consider,nusers generate messages for the channel according to a probability distribution. Raghavan and Upfal have given a protocol in which the expecteddelay(time to get serviced) of every message is O(logn) when messages are generated according to a Bernoulli distribution with generation rate up to about 1/10. Our main results are the following protocols: (a) one in which the expected average message delay is O(1) when messages are generated according to a Bernoulli distribution with a generation rate smaller than 1/e, and (b) one in which the expected delay of any message is O(1) for an analogous model in which users are synchronized (i.e., they agree about the time), there are potentially an infinite number of users, and messages are generated according to a Poisson distribution with generation rate up to 1/e. (Each message constitutes a new user.)To achieve (a), we first show how to simulate (b) usingnsynchronized users, and then show how to build the synchronization into the protocol.
DIAGRAM
Authors: Robinson Jane J. 
Published: July 2002

An explanatory overview is given of DIAGRAM, a large and complex grammar used in an artificial intelligence system for interpreting English dialogue. DIAGRAM is an augmented phrase-structure grammar with rule procedures that allow phrases to inherit attributes from their constituents and to acquire attributes from the larger phrases in which they themselves are constituents. These attributes are used to set context-sensitive constraints on the acceptance of an analysis. Constraints can be imposed by conditions on dominance as well as by conditions on constituency. Rule procedures can also assign scores to an analysis to rate it as probable or unlikely. Less likely analyses can be ignored by the procedures that interpret the utterance. For every expression it analyzes, DIAGRAM provides an annotated description of the structure. The annotations supply important information for other parts of the system that interpret the expression in the context of a dialogue.
Major design decisions are explained and illustrated. Some contrasts with transformational grammars are pointed out and problems that motivate a plan to use metarules in the future are discussed. (Metarules derive new rules from a set of base rules to achieve the kind of generality previously captured by transformational grammars but without having to perform transformations on syntactic analyses.)
A randomized protocol for signing contracts
Authors: Even Shimon , Goldreich Oded , Lempel Abraham 
Published: July 2002

Randomized protocols for signing contracts, certified mail, and flipping a coin are presented. The protocols use a 1-out-of-2 oblivious transfer subprotocol which is axiomatically defined.The 1-out-of-2 oblivious transfer allows one party to transfer exactly one secret, out of two recognizable secrets, to his counterpart. The first (second) secret is received with probability one half, while the sender is ignorant of which secret has been received.An implementation of the 1-out-of-2 oblivious transfer, using any public key cryptosystem, is presented.
Formative design evaluation of superbook
Authors: Egan Dennis E. , Remde Joel R. , Gomez Louis M. , Landauer Thomas K. , Eberhardt Jennifer , Lochbaum Carol C. 
Published: July 2002

SuperBook is a hypertext browsing system designed to improve the usability of conventional documents. Successive versions of SuperBook were evaluated in a series of behavioral studies. Students searched for information in a statistics text. presented either in conventional printed form or in SuperBook form. The best version of SuperBook enabled students to answer search questions more quickly and accurately than they could with the conventional text. Students wrote higher quality “open-book” essays using SuperBook than they did with the conventional text, and their subjective ratings of the documentation strongly favored SuperBook.
This work is a case study of formative design-evaluation. Behavioral evaluation of the first version of SuperBook showed how design factors and user strategies affected search and established baseline performance measures with printed text. The second version of SuperBook was implemented with the goal of improving search accuracy and speed. User strategies that had proved effective in the first study were made very easy and attractive to use. System response time for common operations was greatly improved. Behavioral evaluation of the new SuperBook demonstrated its superiority to printed text and suggested additional improvements that were incorporated into “MiteyBook,” a SuperBook implementation for PC-size screens. Search with MiteyBook proved to be approximately 25 percent faster and 25 percent more accurate than that obtained with a conventional printed book.