bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-Hodgkin's lymphoma among electric utility workers in Ontario: the evaluation of alternate indices of exposure to 60 Hz electric and magnetic fields
Authors: Villeneuve Paul J , Agnew David A , Miller Anthony B , Corey Paul N 
Published: July 2002

OBJECTIVESTo examine associations between non-Hodgkin's lymphoma (NHL) and exposures to 60 Hz magnetic and electric fields in electric utility workers with a series of indices that capture a variety of aspects of field strength.METHODSThe study population consisted of 51 cases of NHL and 203 individually matched controls identified from within a cohort of male electric utility workers in Ontario. Odds ratios were calculated for several exposure indices with conditional logistic regression models. Aspects of exposure to electric and magnetic fields that were modelled included: the percentage of time spent above selected threshold field intensities, mean transitions in field strength, SD, and the arithmetic and geometric mean field intensities.RESULTSFor the most part, there was a lack of an association between exposure indices of magnetic fields and the incidence of NHL. Subjects in the upper tertile of percentage of time spent above electric field intensities of 10 and 40 V/m had odds ratios of 3.05 (95% confidence interval (95% CI) 1.07 to 8.80) and 3.57 (1.30 to 9.80), respectively, when compared with those in the lowest tertile. Moreover, the percentages of time spent above these electric field thresholds were significant predictors of case status over and above the association explained by duration of employment and the arithmetic or geometric mean exposure.CONCLUSIONSThese data suggest that exposures above electric field threshold intensities of 10 and 40 V/m are important predictors of NHL. Consequently, the findings support the hypothesis that electric fields may play a promoting part in the aetiology of this cancer. Further occupational studies that include assessment of exposure to electric fields and measures of field strength above similar threshold cut off points are needed to confirm these findings.
Exposure biomarkers and risk from gluing and heating of polyurethane: a cross sectional study of respiratory symptoms
Authors: Littorin Margareta , Rylander Lars , Skarping Gunnar , Dalene Marianne , Welinder Hans , Strömberg Ulf , Skerfving Staffan 
Published: July 2002

OBJECTIVESTo define the relation between exposure to polyurethane (PUR) glue, biomarkers of exposure and effect, and work related symptoms that occur at least once a week.METHODSIn a cross sectional study, 152 workers and 14 clerks in a factory with exposure to sprayed and heated PUR glue containing 4,4′-diphenylmethane (MDI) or 1,6-hexamethylene (HDI) di-isocyanate were examined with gas chromatography-mass spectrometry (GC-MS) for metabolites of MDI in plasma (P-MDX) and urine (U-MDX), 2,4- and 2,6-toluene di-isocyanate (TDI; P-TDX, U-TDX) and HDI in plasma and urine, specific serum IgG (S-IgG-MDI, S-IgG-HDI, and S-IgG-TDI, respectively) and IgE (S-IgE-MDI). Work related symptoms of the eyes and airways (nose or lower airways, or both), and lung function were also evaluated.RESULTSP-MDX was detected in 65% of the workers, U-TDX in 47%, HDX in none. Three per cent were positive for S-IgE-MDI, 33% for S-IgG-MDI, 32% for S-IgG-TDI, and 12% for S-IgG-HDI. A few clerks had metabolites, and some had antibodies. Most metabolites and immunoglobulins were slightly correlated—for example, P-MDXvS-IgG-MDI: rs=0.21. Workers who heated glue had increased P-MDX (odds ratio (OR)=12 for a value above the median) and S-IgG-MDI (OR=3.7), sprayers P-2,4-TDX (OR=6.2) and P-2,6-TDX (OR=16). Twenty six per cent of the workers had work related symptoms of the airways, 21% from the nose, 11% from the lower airways. Spraying of glue increased the risk of work related symptoms and slightly decreased lung function. U-MDX was associated with work related symptoms from the airways (OR=3.7) and P-2,6-TDX with work related symptoms from the lower airways (OR=6.6). S-IgG-MDI was related to work related symptoms from the airways (OR=2.6).CONCLUSIONSThere were relations between exposures to sprayed and heated PUR glue based on MDI and HDI, concentrations of metabolites of MDI and TDI in plasma and urine, specific IgG serum antibodies against MDI, TDI, and HDI, and work related symptoms.
109Cd Kxray fluorescence measurements of tibial lead content in young adults exposed to lead in early childhood
Authors: McNeill Fiona E , Stokes Lynette , Brito José A A , Chettle David R , Kaye Wendy E 
Published: July 2002

OBJECTIVESTibia lead measurements were performed in a population of 19–29 year old people who had been highly exposed to lead in childhood to find whether lead had persisted in the bone matrix until adulthood.METHODS109Cd Kxray fluorescence was used to measure the tibia lead concentrations of 262 exposed subjects and 268 age and sex matched controls. Questionnaire data allowed a years of residence index to be calculated for exposed subjects. A cumulative blood lead index was calculated from the time weighted integration of available data of blood lead.RESULTSThe mean (SEM) difference between exposed and control men was 4.51 (0.35) μg Pb/g bone mineral, and between exposed and control women was 3.94 (0.61) μg Pb/g bone mineral. Grouped mean bone lead concentrations of exposed subjects were predicted best by age. When exposed and control subjects' data were combined, grouped mean bone lead concentrations were predicted best by cumulative blood lead index. The years of residence index was neither a good predictor of bone lead concentrations for exposed subjects nor for exposed and control subjects combined. Finally, exposed subjects had increased current blood lead concentrations that correlated significantly with bone lead values.CONCLUSIONBone lead concentrations of exposed subjects were significantly increased compared with those of control subjects. Lead from exposure in early childhood had persisted in the bone matrix until adulthood. Exposed subjects had increased blood lead concentrations compared with controls. Some of this exposure could be related to ongoing exposure. However, some of the increase in blood lead concentration in adult exposed subjects seemed to be a result of endogenous exposure from increased bone lead stores. The endogenous exposure relation found for men was consistent with reported data, but the relation found for women was significantly lower. Further research is needed to find whether the observed differences are due to sex, or pregnancy and lactation.
Evaluation of a postgraduate educational programme for occupational physicians on work rehabilitation guidelines for patients with low back pain: Table 1
Authors: Smits P B A , Verbeek J H A M , van Dijk F J H , Metz J C M , ten Cate Th J 
Published: July 2002

OBJECTIVESThe postgraduate educational programme for occupational physicians on guidelines for work rehabilitation of patients with low back pain was evaluated as to what extent did knowledge of the guidelines increase, and did the workers improve their performance at work.METHODSAn experimental group (n=25) attended an educational programme and a reference group did so (n=20) 6 months later. Knowledge and performance were assessed for both groups, before and after education of the experimental group. Knowledge was assessed for the reference group after education.RESULTSKnowledge increased significantly more in the experimental group. The reference group's score increased further after education. The experimental group's adjusted gain score for performance indicators was significantly positive. Analysis of covariance also showed a significant effect for the experimental group for increased performance score.CONCLUSIONSThe educational programme improved the quality of care because knowledge and performance of occupational physicians improved and complied better with practice guidelines.
Acute respiratory effects of particles: mass or number?
Authors: Osunsanya T , Prescott G , Seaton A 
Published: July 2002

OBJECTIVESTo determine whether associations might be found, in patients with chronic airflow obstruction, between symptoms, peak flow rate (PEF), and particle mass and numbers, and to assess which measure was most closely associated with changes in health. Epidemiological studies have shown associations between particulate air pollution and cardiovascular and respiratory disease, and it has been proposed that these may be mediated by particles of nm size (ultrafine).METHODSRelations were investigated between symptom scores, PEF, and bronchodilator use in 44 patients aged ⩾50 years with chronic obstructive pulmonary disease, and daily measurements of both mass of ambient particles of aerodynamic diameter less than 10 μm (PM10) and numbers of ultrafine particles (<100 nm), allowing for meteorological variables. Symptom scores, bronchodilator use, and PEF were recorded daily for 3 months. Counts of ultrafine particles were made by the TSI model 3934 scanning mobility particle sizer (SMPS) and PM10measurements by the tapered element oscillating microbalance (TEOM).RESULTSUltrafine particle counts indoors and outdoors were significantly correlated, those indoors being about half of those outdoors. No associations were found between actual PEF and PM10or ultrafine particles. However, there was a 19% increase in the rate of 10% decrements in daytime PEF with increases in PM10from 10 to 20 μg/m3which was of borderline significance (p=0.05). A change in PM10from 10 to 20 μg/m3was significantly associated with a 14% increase in the rate of high scores of shortness of breath (p=0.003). A similar change in PM10as a moving average of the same day and 2 previous days was associated with a 31% increase in the rate of high scores for cough (p=0.02). Cough symptoms were also associated with lower temperatures (p=0.02). Higher use of medicines was also associated with higher PM10, but the increases were very small in clinical terms.CONCLUSIONSEvidence was not found to support the hypothesis that the component of particulate pollution responsible for effects on respiratory symptoms or function resides in the fraction below 100 nm diameter. The consistent associations between symptoms and PM10suggest that a contribution of the coarser fraction should not be dismissed. Further studies will be needed before the conclusions of this specific project may be generalised.
Response of finger circulation to energy equivalent combinations of magnitude and duration of vibration
Authors: Bovenzi M , Lindsell C J , Griffin M J 
Published: July 2002

OBJECTIVESTo investigate the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same “energy equivalent” acceleration magnitude according to current standards for hand transmitted vibration.METHODSFinger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men who had not used hand held vibrating tools regularly. With a static load of 10 N, the right hand was exposed to 125 Hz vibration with the following unweighted root mean square (rms) acceleration magnitudes and durations of exposure: 44 m/s2for 30 minutes; 62 m/s2for 15 minutes; 88 m/s2for 7.5 minutes; 125 m/s2for 3.75 minutes; and 176 m/s2for 1.88 minutes. These vibration exposures produce the same 8 hour energy equivalent frequency weighted acceleration magnitude (∼1.4 m/s2rms) according to international standard ISO 5349 (1986). Finger circulation was measured in both the right (vibrated) and the left (non-vibrated) middle fingers before application of the vibration, and at fixed intervals during exposure to vibration and during a 45 minute recovery period.RESULTSThe FST did not change during exposure to vibration, whereas vibration with any combination of acceleration magnitude and duration produced significant percentage reductions in the FBF of the vibrated finger compared with the FBF before exposure (from −40.1% (95% confidence interval (95% CI) −24.3% to −57.2%) to −61.4% (95% CI −45.0% to −77.8%). The reduction in FBF during vibration was stronger in the vibrated finger than in the non-vibrated finger. Across the five experimental conditions, the various vibration stimuli caused a similar degree of vasoconstriction in the vibrated finger during exposure to vibration. There was a progressive decrease in the FBF of both fingers after the end of exposure to vibration with acceleration magnitudes of 44 m/s2for 30 minutes and 62 m/s2for 15 minutes. Significant vasoconstrictor after effects were not found in either finger after exposure to any of the other vibration stimuli with greater acceleration magnitudes for shorter durations.CONCLUSIONSFor the range of vibration magnitudes investigated (44 to 176 m/s2rms unweighted; 5.5 to 22 m/s2rms when frequency weighted according to ISO 5349), the vasoconstriction during exposure to 125 Hz vibration was independent of vibration magnitude. The after effect of vibration was different for stimuli with the same energy equivalent acceleration, with greater effects after longer durations of exposure. The energy equivalent acceleration therefore failed to predict the acute effects of vibration both during and after exposure to vibration. Both central and local vasoregulatory mechanisms are likely to be involved in the response of finger circulation to acute exposures to 125 Hz vibration.
Psychological factors and visual fatigue in working with video display terminals
Authors: Mocci F , Serra A , Corrias G A 
Published: July 2002

OBJECTIVESTo examine the part played by psychological factors in complaints about visual health reported by banking officers who work at video display terminals (VDTs).METHODSOut of a population of 385 bank workers, a group of 212 subjects without organic visual disturbances (as determined by opthalmological examination) who share a work environment and job duties was selected. Three questionnaires were administered to these subjects: (a) the NIOSH job stress questionnaire; (b) a questionnaire investigating subjective discomfort related to environmental and lighting conditions of the workplace; (c) a questionnaire on the existence of oculovisual disturbances. Correlation and multiple regression analyses were performed to examine for the presence of predictors of asthenopia.RESULTSSocial support, group conflict, self esteem, work satisfaction, and underuse of skills were found to be predictors of visual complaints; social support played a part also as a moderating factor in the stress and strain model; this model accounted for 30% of the variance. Subjective environmental factors, although in some cases significantly correlated with asthenopia, were not found to be strong predictors of the symptoms.CONCLUSIONSSome part of the complaints about visual health reported by VDT workers are likely indirect expressions of psychological discomfort related to working conditions.
An increased standardised mortality ratio for liver cancer among polyvinyl chloride workers in Taiwan
Authors: Wong R-H , Chen P-C , Du C-L , Wang J-D , Cheng T-J 
Published: July 2002

Aims:To determine the standardised mortality ratio (SMR) corresponding to different causes of death in workers from polyvinyl chloride polymerisation factories in Taiwan.Methods:Retrospective cohort study of workers from six polyvinyl chloride polymerisation factories in Taiwan. A total of 3293 male workers who had been employed for at least one year during the period 1 January 1950 to 31 December 1992, and were alive on 1 January 1985 were included for analysis. Using data acquired from Taiwan's National Mortality Registry, it was found that 144 of these workers died during the period 1985–97. The follow up rate was 99% with a total number of person-years at risk of 40 557.Results:SMR for all causes of death was 0.78, indicating a possible “healthy worker” effect. The SMR for liver cancer decreased with increasing age of first exposure to vinyl chloride monomer. This association was more prominent for workers who were first employed in the industry prior to 1970 (SMR 4.82). Medical records indicated that most liver cancers in this study were hepatocellular carcinoma.Conclusions:Polyvinyl chloride workers may experience a higher risk of developing liver cancer, particularly hepatocelluar carcinoma.
Specialist follow up of patients before end stage renal failure and its relationship to survival on dialysis
Authors: Stoves J , Bartlett C N , Newstead C G 
Published: July 2002

Abstract
The high mortality rate of patients with end stage renal failure (ESRF) treated by dialysis is determined principally by irreversible factors such as age and comorbidity. In this single centre retrospective study of all 1260 ESRF patients who started dialysis between 1980 and 1999 it has been demonstrated that a short duration of specialist predialysis follow up is associated with a worse long term outcome on dialysis.
Kaplan-Meier survival curves were plotted according to duration of predialysis follow up (group A, ⩽ 90 days; group B &gt;90 days), censoring for first transplant, and compared using a log rank test. Differences between groups were examined using an unpaired t test. Cox regression analysis was performed to examine the influence of selected variables on survival.
Group A had the worst mortality (survival proportions of 87%, 74%, and 31% in A and 94%, 87%, and 55% in B at four months, one year, and five years respectively, p&lt;0.001). The increased risk of death was seen principally during the first few months of dialysis. ESRF associated with systemic disease was more prevalent in A. There were small but significant differences in predialysis clinical data, including age and serum albumin (p&lt;0.001). Fewer patients in A were suitable for transplant listing (p&lt;0.01). In the regression analysis, age, diabetes, predialysis serum albumin, suitability for transplant work-up and listing (“transplantability”), and the interval between referral and dialysis were significant predictors of survival.
In summary, this study strengthens the previously reported association between late referral of ESRF patients and subsequent poor survival on dialysis. This important message is relevant to all potential referring physicians. Key pointsThe high mortality rate of patients with ESRF treated by dialysis is determined principally by irreversible factors such as age and comorbidity.We have demonstrated in a single centre retrospective study of more than 1200 patients with ESRF that a short duration of specialist predialysis follow up is associated with an increased risk of death on dialysis, principally during the first few months of treatment.Delays in the referral to renal specialist services of patients with advanced chronic renal failure should be minimised.
Primary care referral protocol for carpal tunnel syndrome
Authors: Hayward A C , Bradley M J , Burke F D 
Published: July 2002

Abstract
Carpal tunnel syndrome is an extremely common upper limb nerve compression syndrome, widely distributed in the community. There are a variety of treatment options which may be applied to the syndrome, depending on the severity of symptoms. Some options are available in a primary care setting, others require secondary referral. This paper is a detailed review of the available literature and provides a protocol that could be used to assist in the referral of patients from primary care.
An unusual case of infective endocarditis
Authors: Houghton T , Kaye G C , Meigh R E 
Published: July 2002

Abstract
A rare case of Corynebacterium striatum endocarditis on a bioprosthetic aortic valve replacement, treated medically, is reported. The presentation was subacute, and initially endocarditis screening was negative. Because of the failure of symptoms to settle further screening was performed which confirmed the organism in several sets of blood cultures. This emphasises the importance of persistent screening for endocarditis if the history raises any suspicion of this potentially serious infection, especially in the presence of prosthetic valves.
TIME SCALES IN A NON-AUTONOMOUS LINEAR DISCRETE MODEL
Authors: SANZ LUIS , DE LA PARRA RAFAEL BRAVO 
Published: July 2002

In this work we extend approximate aggregation methods in time discrete linear models to the case of time varying environments. Approximate aggregation consists of describing some features of the dynamics of a general system involving many coupled variables in terms of the dynamics of a reduced system with a few "global" variables. We present a time varying discrete model in which we distinguish two processes with different time scales. By defining the global variables as appropriate linear combinations of the state variables, we transform the system into a reduced one. The variables corresponding to the original and reduced systems can be related, therefore allowing one the study of the former in terms of the latter. The property of weak ergodicity, which has to do with the capacity of a system to become asymptotically independent of initial conditions, is explored for the original and reduced systems. The general method is also applied to aggregate a time-dependent multiregional model which appears in the field of population dynamics in two different cases: Fast migration with respect to demography and fast demography with respect to migration.
Public-key cryptography and password protocols
Authors: Halevi Shai , Krawczyk Hugo 
Published: July 2002

We study protocols for strong authentication and key exchange in asymmetric scenarios where the authentication server possesses ~a pair of private and public keys while the client has only a weak human-memorizable password as its authentication key. We present and analyze several simple password authentication protocols in this scenario, and show that the security of these protocols can be formally proven based on standard cryptographic assumptions. Remarkably, our analysis shows optimal resistance to off-line password guessing attacks under the choice of suitable public key encryption functions. In addition to user authentication, we describe ways to enhance these protocols to provide two-way authentication, authenticated key exchange, defense against server's compromise, and user anonymity. We complement these results with a proof that strongly indicates that public key techniques are unavoidable for password protocols that resist off-line guessing attacks.As a further contribution, we introduce the notion ofpublic passwordsthat enables the use of the above protocols in situations where the client's machine does not have the means to validate the server's public key. Public passwords serve as "hand-held certificates" that the user can carry without the need for specal computing devices.
On the foundations of the universal relation model
Authors: Maier David , Ullman Jeffrey D. , Vardi Moshe Y. 
Published: July 2002

The universal relation model aims at achieving complete access-path independence in relational databases by relieving the user of the need for logical navigation among relations. We clarify the assumptions underlying it and explore the approaches suggested for implementing it.
The essential idea of the universal relation model is that access paths are embedded in attribute names. Thus attribute names must play unique “roles.” Furthermore, it assumes that for every set of attributes there is a basic relationship that the user has in mind. The user's queries refer to these basic relationships rather than to the underlying database.
Two fundamentally different approaches to the universal relation model have been taken. According to the first approach, the user's view of the database is a universal relation or many universal relations, about which the user poses queries. The second approach sees the model as having query-processing capabilities that relieve the user of the need to specify the logical access path. Thus, while the first approach gives a denotational semantics to query answering, the second approach gives it an operational semantics. We investigate the relationship between these two approaches.