bluuebunny/crossref_metadata_2025 huggingface dataset:
Musculoskeletal disorders of the neck and shoulders in female sewing machine operators: prevalence, incidence, and prognosis
Authors: Kaergaard Anette , Andersen Johan H
Published: July 2002

OBJECTIVES

To assess the occurrence and persistence of two restrictively defined neck-shoulder disorders among sewing machine operators. To assess factors associated with the development of neck-shoulder disorder and prognostic factors for remaining a case, when disorders were already present.

METHODS

In an initial group of 243 sewing machine operators, 178 were followed up for 2 years. At baseline and at 1 and 2 years follow up the participants underwent a clinical examination of the neck and arms and filled in a questionnaire about current musculoskeletal complaints. Clinical criteria for two main neck-shoulder disorders were defined: rotator cuff tendinitis and myofascial pain syndrome. A baseline control group consisted of 357 women with varied non-repetitive work.

RESULTS

At baseline the overall prevalence of myofascial pain syndrome and rotator cuff tendinitis was 15.2% and 5.8% among sewing machine operators compared with 9.0% and 2.2%, respectively, among controls. The presence of the disorders was strongly associated with a self perception of poor general health. Although myofascial pain syndrome showed a U shaped association with years as a sewing machine operator, rotator cuff tendinitis was absent among the newest recruits and present among 15% of the women with more than 20 years as a sewing machine operator. Besides years as a sewing machine operator, the risk of having a neck-shoulder disorder at baseline was significantly associated with high stress (prevalence ratio (PR)=2.54; 95% confidence interval (95% CI) 1.28 to 5.05) when adjusted for age, body mass index, smoking, living alone with children, job strain, and social support from colleagues and supervisors. Only one of 13 participants with rotator cuff tendinitis at baseline recovered during follow up. Myofascial pain syndrome showed a much more fluctuating tendency. Low social support (RR 3.72; 95% CI 1.22 to 11.30) and smoking (RR 3.93; 95% CI 1.33 to 11.58) were associated with the development of neck-shoulder disorders, which was also associated with neck-shoulder pain score and living alone with children.

CONCLUSION

Rotator cuff tendinitis showed a higher degree of persistence than myofascial pain syndrome. Both disorders highly influenced the perception of general health. Women who lived alone with children, were smokers, or experienced low support from colleagues and supervisors had a higher risk of contracting a neck-shoulder disorder.
Are neck flexion, neck rotation, and sitting at work risk factors for neck pain? Results of a prospective cohort study
Authors: Ariëns G A M , Bongers P M , Douwes M , Miedema M C , Hoogendoorn W E , van der Wal G , Bouter L M , van Mechelen W
Published: July 2002

OBJECTIVE

To study the relation between neck pain and work related neck flexion, neck rotation, and sitting.

METHODS

A prospective cohort study was performed with a follow up of 3 years among 1334 workers from 34 companies. Work related physical load was assessed by analysing objectively measured exposure data (video recordings) of neck flexion, neck rotation, and sitting posture. Neck pain was assessed by a questionnaire. Adjustments were made for various physical factors that were related or not related to work, psychosocial factors, and individual characteristics.

RESULTS

A significant positive relation was found between the percentage of the working time in a sitting position and neck pain, implying an increased risk of neck pain for workers who were sitting for more than 95% of the working time (crude relative risk (RR) 2.01, 95% confidence interval (95% CI) 1.04 to 3.88; adjusted RR 2.34, 95% CI 1.05 to 5.21). A trend for a positive relation between neck flexion and neck pain was found, suggesting an increased risk of neck pain for people working with the neck at a minimum of 20° of flexion for more than 70% of the working time (crude RR 2.01, 95% CI 0.98 to 4.11; adjusted RR 1.63, 95% CI 0.70 to 3.82). No clear relation was found between neck rotation and neck pain.

CONCLUSION

Sitting at work for more than 95% of the working time seems to be a risk factor for neck pain and there is a trend for a positive relation between neck flexion and neck pain. No clear relation was found between neck rotation and neck pain.
Research priorities in occupational health in Italy
Authors: Iavicoli S , Marinaccio A , Vonesch N , Ursini C L , Grandi C , Palmi S
Published: July 2002

OBJECTIVE

To find a broad consensus on research priorities and strategies in the field of occupational health and safety in Italy.

METHODS

A 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.

RESULTS

Among 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).

CONCLUSIONS

This 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

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

OBJECTIVES

To develop a simulation model to predict the effects of youth access policies on retail compliance, smoking rates, and smoking attributable deaths.

METHODS

A 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.

RESULTS

The 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.

CONCLUSIONS

A 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.
Demystifying suberin
Authors: Bernards Mark A
Published: July 2002

Suberin is a term used to define a specific cell wall component that occurs, for example, in phellem (cork) endodermal and exodermal cells and is characterized by the deposition of both poly(phenolic) and poly(aliphatic) domains. Historically, the poly(phenolic) domain has been likened to lignin, and while there is an element of truth to this comparison, recent evidence supports an alternative view in which the poly(phenolic) domain contains a significant amount of nonlignin precursors (principally hydroxycinnamic acids and their derivatives) that are covalently linked to each other in a manner analogous to the monolignols in lignin. Similarly, the conceptual model in which the poly(aliphatic) domain of suberized tissues is represented as a random network of polyesterified, modified fatty acids and alcohols has been replaced with one comprising a three-dimensional, glycerol-bridged network. Taken together, a new model for suberin is emerging in which a hydroxycinnamic acid  monolignol poly(phenolic) domain, embedded in the primary cell wall, is covalently linked to a glycerol-based poly(aliphatic) domain located between the primary cell wall and the plasma membrane. The structural and biochemical evidence supporting this new suberin paradigm are examined in this minireview, along with the presentation of a new structural model encompassing a current view of the structure of suberin.Key words: suberin, lignin, hydroxycinnamic acid, monolignol, poly(aliphatic) domain, poly(phenolic) domain, glycerol polyester.
Novel genes are enriched in normalized cDNA libraries from drought-stressed seedlings of rice (Oryza sativa L. subsp. indica cv. Nagina 22)
Authors: Reddy Arjula R , Ramakrishna W , Sekhar A Chandra , Ithal Nagabhushana , Babu P Ravindra , Bonaldo M F , Soares M B , Bennetzen Jeffrey L
Published: July 2002

We have utilized an efficient method to enrich cDNA libraries for novel genes and genes responsive to drought stress in rice (Oryza sativa L. subsp. indica). We separately constructed standard and normalized cDNA libraries from leaf tissue of rice seedlings grown under controlled drought stress. Sequencing from the 3' end was performed on 1000 clones from the normalized leaf cDNA library and 200 clones from the standard leaf cDNA library. For the first 200 clones, the clone redundancy in the non-normalized library was about 10%, compared with 3.5% in the normalized cDNA library. Comparison of these cDNAs with the sequences in public databases revealed that 28.2% of the expressed sequence tags (ESTs) from the normalized library were novel. Clones from the standard and normalized leaf libraries and a root library uncovered numerous cDNAs that are highly homologous to known drought-responsive genes including those that encode metallothioneins, late embroyonic abundant (LEA) proteins, heat-shock proteins, cytochrome P450 enzymes, catalases, peroxidases, kinases, phosphatases, and transcription factors.Key words: Oryza sativa L., drought tolerance, normalization, ESTs, redundancy, cDNA library.
Effect of driver and road characteristics on required preview sight distance
Authors: Hassan Yasser , Sayed Tarek
Published: July 2002

Highway geometric design is a complex process that is closely related to human perception and behaviour. Among the human perception issues that can affect highway geometric design is the preview sight distance, which has been defined as the distance required to perceive a horizontal curve and react properly to it. Previous attempts to quantify preview sight distance included measurement on actual roads, physical modelling, and computer animation. This paper presents a computer animation experiment that was designed to examine the effects of geometric parameters and driver characteristics on preview sight distance and to statistically model preview sight distance. Statistical analysis showed that preview sight distance depends on geometric parameters such as the horizontal curve radius, use of spiral curve and its length, presence of crest vertical curve, algebraic difference of vertical grades, vertical curvature, and road delineation. On the other hand, driver characteristics were mostly found to be insignificant parameters. Finally, statistical models were developed to predict the value of preview sight distance using linear regression analysis. The models vary in simplicity and accuracy and were formulated as a function of the general alignment configuration or as a function of the exact geometric parameters.Key words: highway geometric design, sight distance, driver characteristics, three-dimensional alignment.
Computer-assisted construction methods knowledge management and selection
Authors: Udaipurwala Asad , Russell Alan D
Published: July 2002

The construction industry's information environment is undergoing rapid changes. Construction professionals now expect fast and reliable access to rich data sources. Significant advances have been made in streamlining the creation and dissemination of computer-aided design drawings and construction documents through incorporation of information technology in the workflow. However, there is a need to go beyond just the automation of existing paper flows and provide the construction knowledge worker with tools that can be easily used to document previous project experience, track new technological developments, and then incorporate these in the formulation of construction strategies for future projects. This paper describes work aimed at creating such tools in the context of a comprehensive decision-support system, by developing intelligent representation structures for storing and accessing construction domain knowledge and coupling them with advanced planning tools so as to enable the quick formulation and assessment of initial project plans. The information requirements and features needed for such a system are first examined, followed by a demonstration of how some of these requirements have been addressed in the system design and implementation. Aspects of a hypothetical high-rise building project are used throughout to illustrate application of the concepts developed.Key words: construction methods, integrated project management systems, methods feasibility reasoning, hierarchical scheduling, project views.
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
Influence of the nature of organic compounds on fine soil stabilization with cement
Authors: Tremblay Hélène , Duchesne Josée , Locat Jacques , Leroueil Serge
Published: July 2002

It is well known that organic matter may affect the cementing process in soils, but what happens when cement is added to an organic soil? Both the organic matter content and the nature of this organic matter affect the properties of a treated soil. It appears that some organic compounds delay or even inhibit the hydration process of cement, while others do not affect the reaction at all. This paper presents some results of a laboratory study in which 13 different organic compounds were added separately to two different soils, and then treated with 10% cement. To assess the cementing process, undrained shear strength was measured on the different specimens, and some chemical analyses were performed on the pore liquid. The results indicate that the organic acids producing a pH lower than 9 in the pore solution strongly affect the development of cementing products and almost no strength gain was noted. Also, oils and hydrocarbons, which are insoluble in water, delay the cement hydration but do not affect the final strength. Finally, the pH value and the SO4 concentration in the pore solution are good indicators of the cementing effectiveness of the treated specimens.Key words: soil stabilization, organic compounds, undrained shear strength, cement, chemical analyses.
Effects of stand density on the growth of young Douglas-fir trees
Authors: Woodruff David R , Bond Barbara J , Ritchie Gary A , Scott William
Published: July 2002

The objectives of this study were (i) to provide further evidence of a positive correlation of stand density with early growth of coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii); (ii) to determine when after planting the positive growth response occurs and how long it lasts; and (iii) to use stable isotopes of carbon to test whether the mechanism(s) responsible for the positive growth response to density are related to variables affecting photosynthesis, such as nutrient or moisture availability. We measured annual height (h) and diameter (d) growth (retrospectively) of 8- and 12-year-old trees in initial planting densities of 300, 1360, and 2960 trees/ha. Both height and diameter growth increased with density through the fifth year after planting and decreased with density by year 7. Diameter squared × height (d2h) was used as a volume index to assess increase in tree volume. Second-year increase in d2h for the high-density treatments was 300% of that in the low-density treatments. The δ13C values of wood cellulose from annual rings of the second and third years after planting were not significantly different among densities, suggesting either (i) no significant differences in the effects of water availability, nutrient availability, or source air on photosynthesis in the three density treatments or (ii) differences that produced no net effect on δ13C.
A demographic analysis of a southern snowshoe hare population in a fragmented habitat: evaluating the refugium model
Authors: Wirsing Aaron J , Steury Todd D , Murray Dennis L
Published: July 2002

The allegedly noncyclic dynamics of southern snowshoe hare (Lepus americanus) populations may be explained by a model invoking habitat fragmentation and facultative predation (the refugium model) under which animals dispersing from patches of preferred habitat fail to establish themselves because of predation by facultative carnivores. We compared the refugium model with a revised model invoking heavy on-site predation in preferred habitat as the proximal mechanism responsible for the stability of southern snowshoe hare populations. The survival and movements of hares in a fragmented habitat in central Idaho were monitored via radiotelemetry on 6 sites differing in habitat quality (indexed by understory cover) from 1998 to 2000. In support of the revised model, predation rates were high irrespective of cover availability or hare density, and predators did not kill dispersing animals disproportionately. Furthermore, predation was focused on small hares, suggesting that poor recruitment of juveniles may be the mechanism ultimately responsible for the damped dynamics of southern snowshoe hare populations. The low survival rates we measured suggest that the population under study was undergoing a marked decline. However, the observed decline, determined by comparing study-site population estimates, was less severe, implying that the persistence of local snowshoe hare populations in some areas of the species' southern range may be influenced by metapopulation dynamics. Specifically, southern snowshoe hare populations in small patches of usable habitat may be prevented from going extinct by the arrival of immigrants from similar nearby patches.
AUTOMORPHIC FORMS AND LORENTZIAN KAC–MOODY ALGEBRAS PART II
Authors: GRITSENKO VALERI A. , NIKULIN VIACHESLAV V.
Published: July 2002

We give variants of lifting construction, which define new classes of modular forms on the Siegel upper half-space of complex dimension 3 with respect to the full paramodular groups (defining moduli of Abelian surfaces with arbitrary polarization). The data for these liftings are Jacobi forms of integral and half-integral indices. In particular, we get modular forms which are generalizations of the Dedekind eta-function. Some of these forms define automorphic corrections of Lorentzian Kac–Moody algebras with hyperbolic generalized Cartan matrices of rank three classified in Part I of this paper. We also construct many automorphic forms which give discriminants of moduli of K3 surfaces with conditions on Picard lattice.
ON LOCAL PRISONER'S DILEMMA GAME WITH PARETO UPDATING RULE
Authors: AHMED E. , ELGAZZAR A. S.
Published: July 2002

Prisoner's Dilemma games with two and three strategies are studied. The corresponding replicator equations, their steady states and their asymptotic stability are discussed. Local Prisoner's Dilemma games are studied using Pareto optimality. As in the case with Nash updating rule, the existence of tit for tat strategy is crucial to imply cooperation even in one dimension. Pareto updating implies less erratic behavior since the steady state configurations are mostly fixed points or at most 2-cycle. Finally, Prisoner's Dilemma game is simulated on small-world networks which are closer to real systems than regular lattices. There are no significant changes compared to the results of the regular lattice.
DYNAMICAL BREAKING OF SUPERGAUGE SYMMETRY AND ITS RESTORATION AT HIGH TEMPERATURES
Authors: WANG DIAN-FU , SONG HE-SHAN , AN YING
Published: July 2002

The dynamical breaking of the supergauge symmetry in the massless supergauge Wess–Zumino model is discussed without adding the Fayet–Iliopoulos term to the Lagrangian. It is shown, in terms of the Nambu–Jona-Lasinio mechanism, that the supergauge symmetry breaking can be realized dynamically in the massless supergauge Wess–Zumino model. The supergauge symmetry behavior at finite temperatures is also investigated and it is shown that the supergauge symmetry broken dynamically at zero temperature can be restored at finite temperatures.
RENORMALIZATION GROUP FLOW EQUATIONS AND THE PHASE TRANSITION IN O(N)-MODELS
Authors: BOHR O. , SCHAEFER B.-J. , WAMBACH J.
Published: July 2002

We derive and solve numerically self-consistent flow equations for a general O(N)-symmetric effective potential without any polynomial truncation. The flow equations combined with a sort of a heat-kernel regularization are approximated in next-to-leading order of the derivative expansion. We investigate the method at finite temperature and study the nature of the phase transition in detail. Several beta functions, the Wilson–Fisher fixed point in three dimensions for various N are analyzed and various critical exponents β, ν, δ and η are independently calculated in order to emphasize the reliability of this novel approach.
QUANTUM CONFINEMENT EFFECTS ON THE OPTICAL PROPERTIES OF ION BEAM SPUTTERED NICKEL OXIDE THIN FILMS
Authors: KRISHNA M. GHANASHYAM , BHATTACHARYA A. K.
Published: July 2002

Quantum confinement effects on the optical properties of ion beam sputtered nickel oxide thin films are reported. Thin films with crystallite sizes in the range 9 to 14 nm have been deposited on to fused silica substrates. There is an increase in band gap, from 3.4 to 3.9 eV, and a decrease in refractive index, from 2.4 to 1.6, with decrease in crystallite size, that can be attributed to quantum confinement effects. The effective mass approximation has been used to explain the observed behaviour in band gap variation.
SPATIAL AND MOMENTUM DIFFUSION OF ENERGETIC HOLES IN InAs BY TWO COLOR PUMP-PROBE METHOD
Authors: SAITO SHINGO , SUEMOTO TOHRU
Published: July 2002

Time-resolved electronic Raman scattering of a direct-gap semiconductor, InAs was measured by pump-probe method. We used fundamental pulses and second harmonic pulses of mode-locked Ti:S laser as excitation sources, and fundamental pulses as the probe beam. The time-resolved Raman intensities corresponding to the transition from heavy hole band to light hole band showed different features depending on the excitation energy. In case of the fundamental beam excitation, Raman intensity decreased monotonously. On the contrary, Raman intensity under the second harmonic excitation showed a maximum at a few picosecond after excitation. From the analysis, the temperature of photo-excited hole changed from 5300K to 1300K in 2psec and from 1300K to RT within 4 psec under the second harmonics excitation. It has been shown that the time-resolved Raman scattering measurement is a useful tool to investigate dynamics of the energetic carriers.
MULTILINGUAL MACHINE PRINTED OCR
Authors: NATARAJAN PREMKUMAR , LU ZHIDONG , SCHWARTZ RICHARD , BAZZI ISSAM , MAKHOUL JOHN
Published: July 2002

This paper presents a script-independent methodology for optical character recognition (OCR) based on the use of hidden Markov models (HMM). The feature extraction, training and recognition components of the system are all designed to be script independent. The training and recognition components were taken without modification from a continuous speech recognition system; the only component that is specific to OCR is the feature extraction component. To port the system to a new language, all that is needed is text image training data from the new language, along with ground truth which gives the identity of the sequences of characters along each line of each text image, without specifying the location of the characters on the image. The parameters of the character HMMs are estimated automatically from the training data, without the need for laborious handwritten rules. The system does not require presegmentation of the data, neither at the word level nor at the character level. Thus, the system is able to handle languages with connected characters in a straightforward manner. The script independence of the system is demonstrated in three languages with different types of script: Arabic, English, and Chinese. The robustness of the system is further demonstrated by testing the system on fax data. An unsupervised adaptation method is then described to improve performance under degraded conditions.
SEGMENTATION OF HANDWRITTEN CHINESE CHARACTERS FROM DESTINATION ADDRESSES OF MAIL PIECES
Authors: LU YUE , TAN CHEW LIM , SHI PENGFEI , ZHANG KEHUA
Published: July 2002

In this paper, we illustrate a method to segment handwritten Chinese characters from destination addresses of mail pieces. Fast Hough transform is utilized to detect the reference lines preprinted on the mail piece. In the segmentation, subassemblies of Chinese characters are merged based on the structural features of Chinese characters and the subassemblies' topological relations, viz. upper–lower, inside–outside and left–right relations. The width of subassemblies and the spacing between neighboring subassemblies in the whole image of the destination address are analyzed to guide the merging of the left–right subassemblies. Experimental results with real mail piece images show that the proposed approach has achieved a promising performance for segmenting handwritten Chinese characters.
ON A NORMAL-FORM ANALYSIS FOR A CLASS OF PASSIVE BIPEDAL WALKERS
Authors: PIIROINEN PETRI T. , DANKOWICZ HARRY J. , NORDMARK ARNE B.
Published: July 2002

This paper implements a center-manifold technique to arrive at a normal-form for the natural dynamics of a passive, bipedal rigid-body mechanism in the vicinity of infinite foot width and near-symmetric body geometry. In particular, numerical schemes are developed for finding approximate forms of the relevant invariant manifolds and the near-singular dynamics on these manifolds. The normal-form approximations are found to be highly accurate for relatively large foot widths with a range of validity extending to widths on the order of the mechanisms' height.
Invariants of degree one of almost generic plane immersed curves
Authors: Mohanty Sara
Published: July 2002

In 1993, V.I. Arnold used the approach of singularity theory to construct invariants of plane generic immersed curves. This approach suggests a hierarchy of invariants, the coarsest and most fundamental being Arnold's invariants of degree 1. Consider the infinite dimensional space Ω, of all immersions of S1↬ℛ2. The non-generic immersions form a hypersurface called the discriminant which is stratified. The immersions with only one singularity of degree 1 form Σ1, the main part of the discriminant. Given a generic curve on Σ1 (the codim 1 strata), we introduce new invariants of degree 1 in the following sense: when this generic curve passes through Σ2 (immersions with one singularity of degree 2), the value of the invariant jumps by a number which depends only on the stratum of codim 2. The natural stratification of the discriminant yields information about the topology of Σ1, necessary to prove that the invariants are well defined. Of the seen invariants found, five have values in ℤ and two have values in ℤ3. This paper provides an axiomatic description of these invariants.
TYPE II FLUID SOLUTIONS TO EINSTEIN'S FIELD EQUATIONS IN N-DIMENSIONAL SPHERICAL SPACETIMES
Authors: Da ROCHA JAIME F. VILLAS
Published: July 2002

A large class of Type II fluid solutions to Einstein field equations in N-dimensional spherical spacetimes is found, wich includes most of the known solutions. A family of the generalized collapsing Vaidya solutions with homothetic self-similarity, parametrized by a constant λ, is studied, and found that when λ>λ c (N), the collapse always forms black holes, and when λ<λ c (N), it always forms naked singularities, where λ c (N) is function of the spacetime dimension N only.
TACHYONS IN ROBERTSON–WALKER COSMOLOGY
Authors: TOMASCHITZ ROMAN
Published: July 2002

Superluminal signal transfer is studied in the context of a preferred cosmic frame of reference provided by the galactic background. The receding galaxies constitute a frame of absolute rest, in which the energy of tachyons (faster-than-light particles) is unambi-guously defined as a positive quantity. The causality violation which arises in relativistic tachyonic theories is avoided. We define interactions of particles and tachyons in terms of elastic head-on collisions and energy-momentum conservation. To compare the theory developed with existing relativistic theories, tachyons are studied at first in a Minkowski universe, and the causality of a superluminal communication process is analyzed. Then we discuss the dynamics of tachyons in a Robertson–Walker universe with linear expansion factor and negatively curved three-space. We point out the consequences that the space expansion has on tachyons, like a finite life-time in the frame of absolute rest, and multiple images in the rest frames of moving observers.
QUANTUM-TO-CLASSICAL TRANSITION FOR FLUCTUATIONS IN THE EARLY UNIVERSE
Authors: KIEFER CLAUS , POLARSKI DAVID , STAROBINSKY ALEXEI A.
Published: July 2002

According to the inflationary scenario for the very early Universe, all inhomogeneities in the Universe are of genuine quantum origin. On the other hand, looking at these inhomogeneities and measuring them, clearly no specific quantum mechanical properties are observed. We show how the transition from their inherent quantum gravitational nature to classical behavior comes about — a transition whereby none of the successful quantitative predictions of the inflationary scenario for the present-day universe is changed. This is made possible by two properties. First, the quantum state for the spacetime metric perturbations produced by quantum gravitational effects in the early Universe becomes very special (highly squeezed) as a result of the expansion of the Universe (as long as the wavelength of the perturbations exceeds the Hubble radius). Second, decoherence through the environment distinguishes the field amplitude basis as being the pointer basis. This renders the perturbations presently indistinguishable from stochastic classical inhomogeneities.
CARTILAGE REPAIR BY OSTEOCHONDRAL GRAFT IN THE KNEES OF PIGS — A HISTOLOGICAL STUDY
Authors: Wang Ching-Jen , Chen Han-Shiang , Cheng Sheng-Ming , Chen Chris Y. C. , Huang Hsuan-Ying , Chen Wei-Jen , Yeh Wen-Ling
Published: July 2002

Purpose: To investigate the mechanism of free autogenous osteochondral graft in full thickness cartilage defect in the knees of pigs aged three to four months old and weighing 8.5 to 11.5 kg, by histological examination. Methods: Full thickness cartilage defects were created on the medial femoral condyles of both knees. The defects on the right knee served as control study. The defects on the left knee were grafted with free autogenous osteochondral grafts. Biopsies were performed in 4, 8 and 12 weeks and the specimens were examined for predominant tissues, structure characteristics and cell changes as well as the healing of bone and cartilage between the graft and host tissue. Results: The control lesions showed extensive fibrous tissues with increased neovascularization, but no cartilage. With osteochondral grafts, bone remodeling took place in four weeks; and cartilage healing by direct bonding in approximately 12 weeks. There were transient degenerative changes of chondrocyte cellularity and morphology and increased neovascularization in four to eight weeks, which improved by 12 weeks. Conclusions: The mechanism of free autogenous osteochondral grafts started off with bone remodeling in as early as four weeks, which in turn provided better graft stability and promoted neovascularization and nutrition to the cartilage. The healing of hyaline cartilage by direct bonding to the host tissue took place in 12 weeks. There were transient interval changes of chondrocyte cellularity and morphology that warrant postoperative protection of the knees for 8 to 12 weeks.
A random polynomial-time algorithm for approximating the volume of convex bodies
Authors: Dyer Martin , Frieze Alan , Kannan Ravi
Published: July 2002

A randomized polynomial-time algorithm for approximating the volume of a convex body
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in
n
-dimensional Euclidean space is presented. The proof of correctness of the algorithm relies on recent theory of rapidly mixing Markov chains and isoperimetric inequalities to show that a certain random walk can be used to sample nearly uniformly from within
K
.
The multicast policy and its relationship to replicated data placement
Authors: Wolfson Ouri , Milo Amir
Published: July 2002

In this paper we consider the communication complexity of maintaining the replicas of a logical data-item, in a database distributed over a computer network. We propose a new method, called the minimum spanning tree write, by which a processor in the network should multicast a write of a logical data-item, to all the processors that store replicas of the items. Then we show that the minimum spanning tree write is optimal from the communication cost point of view. We also demonstate that the method by which a write is multicast to all the replicas of a data-item affects the optimal replication scheme of the item, i.e., at which processors in the network the replicas should be located. Therefore, next we consider the problem of determining an optimal replicaiton scheme for a data item, assuming that each processor employs the minimum spanning tree write at run-time. The problem for general networks is shown NP-Complete, but we provide efficient algorithms to obtain an optimal allocation scheme for three common types of network topologies. They are completely-connected, tree, and ring networks. For these topologies, efficient algorithms are also provided for the case in which reliability considerations dictate a minimum number of replicas.
Towards an algebraic theory of recursion
Authors: Ioannidis Yannis E. , Wong Eugene
Published: July 2002

An algebraic framework for the study of recursion has been developed. For immediate linear recursion, a Horn clause is represented by a relational algebra operator. It is shown that the set of all such operators forms a closed semiring. In this formalism, query answering corresponds to solving a linear equation. For the first time, the query answer is able to be expressed in an explicit algebraic form within an algebraic structure. The manipulative power thus afforded has several implications on the implementation of recursive query processing algorithms. Several possible decompositions of a given operator are presented that improve the performance of the algorithms, as well as several transformations that give the ability to take into account any selections or projections that are present in a givin query. In addition, it is shown that mutual linear recursion can also be studied within a closed semiring, by using relation vectors and operator matrices. Regarding nonlinear recursion, it is first shown that Horn clauses always give rise to multilinear recursion, which can always be reduced to bilinear recursion. Bilinear recursion is then shown to form a nonassociative closed semiring. Finally, several sufficient and necessary-and-sufficient conditions for bilinear recursion to be equivalent to a linear one of a specific form are given. One of the sufficient conditions is derived by embedding to bilinear recursion in an algebra.
Software reuse
Authors: Krueger Charles W.
Published: July 2002

Software reuse is the process of creating software systems from existing software rather than building software systems from scratch. This simple yet powerful vision was introduced in 1968. Software reuse has, however, failed to become a standard software engineering practice. In an attempt to understand why, researchers have renewed their interest in software reuse and in the obstacles to implementing it.

This paper surveys the different approaches to software reuse found in the research literature. It uses a taxonomy to describe and compare the different approaches and make generalizations about the field of software reuse. The taxonomy characterizes each reuse approach in terms of its reusable
artifacts
and the way these artifacts are
abstracted, selected, specialized,
and
integrated
.

Abstraction plays a central role in software reuse. Concise and expressive abstractions are essential if software artifacts are to be effectively reused. The effectiveness of a reuse technique can be evaluated in terms of
cognitive distance
—an intuitive gauge of the intellectual effort required to use the technique. Cognitive distance is reduced in two ways: (1) Higher level abstractions in a reuse technique reduce the effort required to go from the initial concept of a software system to representations in the reuse technique, and (2) automation reduces the effort required to go from abstractions in a reuse technique to an executable implementation.

This survey will help answer the following questions: What is software reuse? Why reuse software? What are the different approaches to reusing software? How effective are the different approaches? What is required to implement a software reuse technology? Why is software reuse difficult? What are the open areas for research in software reuse?
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.
Synchronization mechanisms for distributed event-driven computation
Authors: Madisetti Vijay K. , Hardaker David A.
Published: July 2002

We analyze distributed event-driven computation on message-passing parallel computing systems. Synchronization is the mechanism that ensures that causality in the ordering of stochastically generated events for execution during the computation is maintained. We characterize distributed event-driven computation into weakly coupled (weak interactions) and strongly coupled (strong interactions) distributed systems and propose and analyze a number of new algorithms for efficient synchronization. The analytical results for steady state performance are complemented with detailed simulations of the transient performance. We show that synchronization enforced separately from computation results in an efficient implementation. Effects of the memory hierarchy and communication delays are also incorporated.
Model-based object recognition in dense-range images—a review
Authors: Arman Farshid , Aggarwal J. K.
Published: July 2002

The goal in computer vision systems is to analyze data collected from the environment and derive an interpretation to complete a specified task. Vision system tasks may be divided into data acquisition, low-level processing, representation, model construction, and matching subtasks. This paper presents a comprehensive survey of model-based vision systems using dense-range images. A comprehensive survey of the recent publications in each subtask pertaining to dense-range image object recognition is presented.
State assignment for hardwired VLSI control units
Authors: Eschermann Bernhard
Published: July 2002

Finding a binary encoding of symbolic control states, such that the implementation area of a digital control unit is minimized is well known to be NP-complete. Many heuristic algorithms have been proposed for thisstate assignment problem. The objective of this article is to present a comprehensive survey and systematic categorization of the various techniques, in particular, for synchronous sequential circuits with nonmicroprogrammed implementations. The problem is partitioned into the generation and the satisfaction of coding constraints. Three types of coding constraints—adjacency, covering, and disjunctive constraints—are widely used. The constraint satisfaction algorithms are classified into column-based, row-based, tree-based, dichotomy-based, and global minimization approaches. All of them are illustrated with examples. Special coding requirements and testability-related aspects of state assignment are considered in a separate section. Different implementations of the algorithms presented are also compared.
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.