bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research priorities in occupational health in Italy
Authors: Iavicoli S , Marinaccio A , Vonesch N , Ursini C L , Grandi C , Palmi S 
Published: July 2002

OBJECTIVETo find a broad consensus on research priorities and strategies in the field of occupational health and safety in Italy.METHODSA two phase questionnaire survey was based on the Delphi technique previously described in other reports. 310 Occupational safety and health specialists (from universities and local health units) were given an open questionnaire (to identify three priority research areas). The data obtained from respondents (175, 56.4%) were then used to draw up a list of 27 priority topics grouped together into five macrosectors. Each of these was given a score ranging from 1 (of little importance) to 5 ( extremely important). With the mean scores obtained from a total of 203 respondents (65.4%), it was possible to place the 27 topics in rank order according to a scale of priorities.RESULTSAmong the macrosectors, first place was given to the question of methodological approach to research in this field, and for individual topics, occupational carcinogenesis and quality in occupational medicine were ranked first and second, respectively. The question of exposure to low doses of environmental pollutants and multiple exposures ranked third among the priorities; the development of adequate and effective approaches and methods for worker education and participation in prevention was also perceived as being an important issue (fourth place).CONCLUSIONSThis study (the first of its kind in Italy) enabled us to achieve an adequate degree of consensus on research priorities related to the protection of occupational health and safety. Disparities in the mean scores of some of the issues identified overall as being research priorities, seem to be linked both to geographical area and to whether respondents worked in local health units or universities. This finding requires debate and further analysis.
Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China
Authors: Wong T W , Tam W S , Yu T S , Wong A H S 
Published: July 2002

Objective: To investigate the association between ambient concentrations of air pollutants and respiratory and cardiovascular mortalities in Hong Kong.Methods: Retrospective ecological study. A Poisson regression of concentrations of daily air pollutants on daily mortalities for respiratory and cardiovascular diseases in Hong Kong from 1995 to the end of 1998 was performed using the air pollution and health: the European approach (APHEA) protocol. The effects of time trend, seasonal variations, temperature, and humidity were adjusted. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and particulate matter <10 μm in aerodynamic diameter (PM10) were averaged from eight monitoring stations in Hong Kong. Relative risks (RRs) of respiratory and cardiovascular mortalities (per 10 μg/m3increase in air pollutant concentration) were calculated.Results: Significant associations were found between mortalities for all respiratory diseases and ischaemic heart diseases (IHD) and the concentrations of all pollutants when analysed singly. The RRs for all respiratory mortalities (for a 10 μg/m3increase in the concentration of a pollutant) ranged from 1.008 (for PM10) to 1.015 (for SO2) and were higher for chronic obstructive pulmonary diseases (COPD) with all pollutants except SO2, ranging from 1.017 (for PM10) to 1.034 (for O3). RRs for IHD ranged from 1.009 (for O3) to 1.028 (for SO2). In a multipollutant model, O3and SO2were significantly associated with all respiratory mortalities, whereas NO2was associated with mortality from IHD. No interactions were detected between any of the pollutants or with the winter season. A dose-response effect was evident for all air pollutants. Harvesting was not found in the short term.Conclusions: Mortality risks were detected at current ambient concentrations of air pollutants. The associations with the particulates and some gaseous pollutants when analysed singly were consistent with many reported in temperate countries. PM10was not associated with respiratory or cardiovascular mortalities in multipollutant analyses.
Phyllodes tumours
Authors: Parker S J , Harries S A 
Published: July 2002

Abstract
Phyllodes tumours are rare fibroepithelial lesions that account for less than 1% of all breast neoplasms. With the non-operative management of fibroadenomas widely adopted, the importance of phyllodes tumours today lies in the need to differentiate them from other benign breast lesions. All breast lumps should be triple assessed and the diagnosis of a phyllodes tumour considered in women, particularly over the age of 35 years, who present with a rapidly growing “benign” breast lump. Treatment can be by either wide excision or mastectomy provided histologically clear specimen margins are ensured. Nodal metastases are rare and routine axillary dissection is not recommended. Few reliable clinical and histological prognostic factors have been identified. Local recurrence occurs in approximately 15% of patients and is more common after incomplete excision. It can usually be controlled by further surgery. Repeated local recurrence has been reported without the development of distant metastases or reduced survival. Approximately 20% of patients with malignant phyllodes tumours develop distant metastases. Long term survival with distant metastases is rare. The role of chemotherapy, radiotherapy, and hormonal manipulation in both the adjuvant and palliative settings remain to be defined.
Effect of policies directed at youth access to smoking: results from theSimSmokecomputer simulation model
Authors: Levy David T , Friend Karen , Holder Harold , Carmona Maria 
Published: July 2002

OBJECTIVESTo develop a simulation model to predict the effects of youth access policies on retail compliance, smoking rates, and smoking attributable deaths.METHODSA model of youth access policies is developed based on empirical research and a theory of perceived risk. The model incorporates substitution into other sources as retail sales are restricted, and is used to project the number of smokers and smoking related deaths. Various policies to limit youth access to cigarettes are evaluated, and we explore how efficient policies may be developed.RESULTSThe model predicts that a well designed and comprehensive policy that includes sufficient compliance checks, penalties, and community involvement has the potential to reduce the number of young smokers. Because smoking related deaths occur later in life, the effects on health are largely delayed.CONCLUSIONSA well designed youth access policy has the ability to affect youth smoking rates in the short term, and will lead to savings in lives in future years. The ability of retail oriented policies to reduce youth smoking, however, is limited. Other tobacco control policies, including those directed at non-retail sources of cigarettes, are also needed.
Deuterides of light elements: low-temperature thermonuclear burn-up and applications to thermonuclear fusion problems
Authors: Frolov A M , Smith Jr. V H , Smith G T 
Published: July 2002

Thermonuclear burn-up and thermonuclear applications are discussed for a number of deuterides and DT hydrides of light elements. These deuterides and corresponding DT hydrides are often used as thermonuclear fuels or components of such fuels. In fact, only for these substances thermonuclear energy gain exceeds (at some densities and temperatures) the bremsstrahlung loss and other high-temperature losses, i.e., thermonuclear burn-up is possible. Herein, thermonuclear burn-up in these deuterides and DT hydrides is considered in detail. In particular, a simple method is proposed to determine the critical values of the burn-up parameter xc for these substances and their mixtures at different temperatures and densities. The results for equimolar DT mixtures coincide quite well with the results of previous calculations. Also, the natural or Z limit is determined for low-temperature thermonuclear burn-up in the deuterides of light elements. PACS Nos.: 28.52Cx, 47.40Nm
A new, fast method for 2D polygon clipping
Authors: Maillot Patrick-Gilles 
Published: July 2002

This paper presents a new 2D polygon clipping method, based on an extension to the Sutherland-Cohen 2D line clipping method. After discussing three basic polygon clipping algorithms, a different approach is proposed, explaining the principles of a new algorithm and presenting it step by step.
An example implementation of the algorithm is given along with some results. A comparison between the proposed method, the Liang and Barsky algorithm, and the Sutherland-Hodgman algorithm is also given, showing performances up to eight times the speed of the Sutherland-Hodgman algorithm, and up to three times the Liang and Barsky algorithm. The algorithm proposed here can use floating point or integer operations; this can be useful for fast or simple implementations.
Cryptographic limitations on learning Boolean formulae and finite automata
Authors: Kearns Michael , Valiant Leslie 
Published: July 2002

In this paper, we prove the intractability of learning several classes of Boolean functions in the distribution-free model (also called the Probably Approximately Correct or PAC model) of learning from examples. These results are
representation independent
, in that they hold regardless of the syntactic form in which the learner chooses to represent its hypotheses.

Our methods reduce the problems of cracking a number of well-known public-key cryptosystems to the learning problems. We prove that a polynomial-time learning algorithm for Boolean formulae, deterministic finite automata or constant-depth threshold circuits would have dramatic consequences for cryptography and number theory. In particular, such an algorithm could be used to break the RSA cryptosystem, factor Blum integers (composite numbers equivalent to 3 modulo 4), and detect quadratic residues. The results hold even if the learning algorithm is only required to obtain a slight advantage in prediction over random guessing. The techniques used demonstrate an interesting duality between learning and cryptography.
We also apply our results to obtain strong intractability results for approximating a generalization of graph coloring.
Object orientation in multidatabase systems
Authors: Pitoura Evaggelia , Bukhres Omran , Elmagarmid Ahmed 
Published: July 2002

A multidatabase system (MDBS) is a confederation of preexisting distributed, heterogeneous, and autonomous database systems. There has been a recent proliferation of research suggesting the application of object-oriented techniques to facilitate the complex task of designing and implementing MDBSs. Although this approach seems promising, the lack of a general framework impedes any further development. The goal of this paper is to provide a concrete analysis and categorization of the various ways in which object orientation has affected the task of designing and implementing MDBSs.We identify three dimensions in which the object-oriented paradigm has influenced this task: the general system architecture, the schema architecture, and the heterogeneous transaction management. Then we provide a classification and a comprehensive analysis of the issues related to each of the above dimensions. To demonstrate the applicability of this analysis, we conclude with a comparative review of existing multidatabase systems.
Tabled evaluation with delaying for general logic programs
Authors: Chen Weidong , Warren David S. 
Published: July 2002

SLD resolution with negation as finite failure (SLDNF) reflects the procedural interpretation of predicate calculus as a programming language and forms the computational basis for Prolog systems. Despite its advantages for stack-based memory management, SLDNF is often not appropriate for query evaluation for three reasons: (a) it may not terminate due to infinite positive recursion; (b) it may be terminate due to infinite recursion through negation; and (c) it may repeatedly evaluate the same literal in a rule body, leading to unacceptable performance.We address all three problems for goal-oriented query evaluation of general logic programs by presenting tabled evaluation with delaying, called SLG resolution. It has three distinctive features:(i) SLG resolution is a partial deduction procedure, consisting of seven fundamental transformations. A query is transformed step by step into a set of answers. The use of transformations separates logical issues of query evaluation from procedural ones. SLG allows an arbitrary computation rule for selecting a literal from a rule body and an arbitrary control strategy for selecting transformations to apply.(ii) SLG resolution is sound and search space complete with respect to the well-founded partial model for all non-floundering queries, and preserves all three-valued stable models. To evaluate a query under differenc three-valued stable models, SLG resolution can be enhanced by further processing of the answers of subgoals relevant to a query.(iii) SLG resolution avoids both positive and negative loops and always terminates for programs with the bounded-term-size property. It has a polynomial time data complexity for well-founded negation of function-free programs. Through a delaying mechanism for handling ground negative literals involved in loops, SLG resolution avoids the repetition of any of its derivation steps.Restricted forms of SLG resolution are identified for definite, locally stratified, and modularly stratified programs, shedding light on the role each transformation plays.
A combinatorial treatment of balancing networks
Authors: Busch Costas , Mavronicolas Marios 
Published: July 2002

Balancing networks, originally introduced by Aspnes et al.(Proceedings of the 23rd Annual ACM Symposium on Theory of Computing, pp. 348-358, May 1991), represent a new class of distributed, low-contention data structures suitable for solving many fundamental multi-processor coordination problems that can be expressed asbalancing problems. In this work, we present a mathematical study of the combinatorial structure of balancing networks, and a variety of its applications.Our study identifies important combinatorialtransfer parametersof balancing networks. In turn, necessary and sufficient combinatorial conditions are established, expressed in terms of transfer parameters, which precisely characterize many important and well studied classes of balancing networks such ascounting networksandsmoothing networks. We propose these combinatorial conditions to be “balancing analogs” of the well knownZero-One principleholding forsorting networksWithin the combinatorial framework we develop, our first application is in deriving combinatorial conditions, involving the transfer parameters, which precisely delimit the boundary between counting networks and sorting networks.
Formal verification in hardware design
Authors: Kern Christoph , Greenstreet Mark R. 
Published: July 2002

In recent years, formal methods have emerged as an alternative approach to ensuring the quality and correctness of hardware designs, overcoming some of the limitations of traditional validation techniques such as simulation and testing.There are two main aspects to the application of formal methods in a design process: the formal framework used to specify desired properties of a design and the verification techniques and tools used to reason about the relationship between a specification and a corresponding implementation. We survey a variety of frameworks and techniques proposed in the literature and applied to actual designs. The specification frameworks we describe include temporal logics, predicate logic, abstraction and refinement, as well as containment between ω-regular languages. The verification techniques presented include model checking, automata-theoretic techniques, automated theorem proving, and approaches that integrate the above methods.In order to provide insight into the scope and limitations of currently available techniques, we present a selection of case studies where formal methods were applied to industrial-scale designs, such as microprocessors, floating-point hardware, protocols, memory subsystems, and communications hardware.
A cell organized raster display for line drawings
Authors: Jordan B. W. , Barrett R. C. 
Published: July 2002

Raster scan computer graphics displays with “real time” character generators have previously been limited to alphanumeric characters. A display is described which extends the capabilities of this organization to include general graphics.The feasibility of such a display is shown by deriving the minimum number of patterns required in the read only memory of the character generator to synthesize an arbitrary line. The synthesis process does not compromise picture quality, since the resulting dot patterns are identical with those of a conventional raster display. Furthermore, the time constraints of a raster display are shown to be satisfied for a typical design for very complex line drawings.
Methods for analyzing data from computer simulation experiments
Authors: Naylor Thomas H. , Wertz Kenneth , Wonnacott Thomas H. 
Published: July 2002

This paper addresses itself to the problem of analyzing data generated by computer simulations of economic systems. We first turn to a hypothetical firm, whose operation is represented by a single-channel, multistation queueing model. The firm seeks to maximize total expected profit for the coming period by selecting one of five operating plans, where each plan incorporates a certain marketing strategy, an allocation of productive inputs, and a total cost.The results of the simulated activity under each plan are subjected to anF-test, two multiple comparison methods, and a multiple ranking method. We illustrate, compare, and evaluate these techniques. The paper adopts the position that the particular technique of analysis (possibly not any one of the above) chosen by the experimenter should be an expression of his experimental objective: TheF-test tests the homogeneity of the plans; multiple comparison methods quantify their differences; and multiple ranking methods directly identify the one best plan or best plans.
A model for concurrency in nested transactions systems
Authors: Beeri Catriel , Bernstein Philip A. , Goodman Nathan 
Published: July 2002

Today's standard model for database concurrency control, called serializability theory, represents executions of transactions as partial orders of operations. The theory tells when an execution is serializable, that is, when the set of operations of a transaction execute atomically with respect to those of other transactions. It has been used successfully to prove correctness of most database concurrency control algorithms. Its most serious limitation is its inability to represent nested computations conveniently.This paper presents a more general model that permits nested transactions. In this model, transactions may execute subtransactions, giving rise to tree-structured computations. A serializability theory is developed for this model, which can be used to prove the correctness of concurrency control algorithms for nested transactions and for multilevel database systems.The theory is based on an abstract model of computation that allows arbitrary operations, and parallel and even nondeterministic programs. Axioms are presented that express the basic properties that programs that manage or access data need to satisfy. We use these axioms to derive proof techniques. One new technique—substitution—shows the equivalence of two executions by substituting one subcomputation by another, usually shallower (i.e., less nested), one. Our proof techniques are illustrated by applying them to several well-known concurrency control problems.
Insect Mouthparts: Ascertaining the Paleobiology of Insect Feeding Strategies
Authors: Labandeira Conrad C. 
Published: July 2002

One of the most intensively examined and abundantly documented structures in the animal world is insect mouthparts. Major structural types of extant insect mouthparts are extensive, consisting of diverse variations in element structure within each of the five mouthpart regions—labrum, hypopharynx, mandibles, maxillae, and labium. Numerous instances of multielement fusion both within and among mouthpart regions result in feeding organs capable of ingesting in diverse ways foods that are solid, particulate, and liquid in form. Mouthpart types have a retrievable and interpretable fossil history in well-preserved insect deposits. In addition, the trace-fossil record of insect-mediated plant damage, gut contents, coprolites, and insect-relevant floral features provides complementary data documenting the evolution of feeding strategies during the past 400 million years.From a cluster analysis of insect mouthparts, I recognize 34 fundamental mouthpart classes among extant insects and their geochronological evolution by a five-phase pattern. This pattern is characterized, early in the Devonian, by coarse partitioning of food by mandibulate and piercing-and-sucking mouthpart classes, followed by a rapid rise in herbivore mouthpart types for fluid- and solid-feeding during the Late Carboniferous and Early Permian. Mouthpart innovation during the Late Triassic to Early Jurassic added mouthpart classes for fluid and aquatic particle-feeding. This ecomorphological expansion of mouthpart design was associated with the radiation of holometabolous insects, especially Diptera. The final phase of mouthpart class expansion occurred during the Late Jurassic and Early Cretaceous, with addition of surface-fluid-feeding mouthpart classes that subsequently became important during the ecological expansion of angiosperms. Conclusions about the evolution of mouthpart design are based on the mapping of phenetic mouthpart classes onto (ideally) cladistic phylogenies of lineages bearing those same mouthpart classes. The plotting of phenetic and associated ecological attributes onto baseline phylogenies is one of the most important uses of cladistic data.
DISCOVERING THE ORIGINS OF IMMUNOLOGICAL COMPETENCE
Authors: Miller Jacques F. A. P. 
Published: July 2002

[Figure: see text]▪ Abstract  Work done in the late 1950s and in the 1960s revealed the role of the thymus in virus-induced leukemia in mice. Thymectomizing mice at birth to test whether the virus first multiplied in thymus tissue and then spread elsewhere ultimately led to the conclusion that the thymus was essential to the normal development of the immune system. Subsequent testing to try to understand how the thymus contributes to the pool of immunocompetent lymphocytes opened a new chapter in immunology and required a reappraisal of many immunological phenomena and an understanding of the molecular interactions that take place during cell-to-cell interactions.