Occupational Restrictions Research Articles

Spatial rock-paper-scissors models with inhomogeneous reaction rates

We study several variants of the stochastic four-state rock-paper-scissors game or, equivalently, cyclic three-species predator-prey models with conserved total particle density, by means of Monte Carlo simulations on one- and two-dimensional lattices. Specifically, we investigate the influence of spatial variability of the reaction rates and site occupancy restrictions on the transient oscillations of the species densities and on spatial correlation functions in the quasistationary coexistence state. For small systems, we also numerically determine the dependence of typical extinction times on the number of lattice sites. In stark contrast with two-species stochastic Lotka-Volterra systems, we find that for our three-species models with cyclic competition quenched disorder in the reaction rates has very little effect on the dynamics and the long-time properties of the coexistence state. Similarly, we observe that site restriction only has a minor influence on the system's dynamical properties. Our results therefore demonstrate that the features of the spatial rock-paper-scissors system are remarkably robust with respect to model variations, and stochastic fluctuations as well as spatial correlations play a comparatively minor role.

Assessing Occupation: The Importance of Using Valid Tests and Measures

The primary focus of occupational therapy is promoting the health and wellbeing of individuals who present with occupational performance dysfunction, activity limitations or participation restrictions (College of Occupational Therapists 2004). When therapists initially see a client, they take an occupational history and usually complete some type of assessment. The assessment component of service delivery can include informal clinical observations and formal standardised tests. Coster (2008, p743) stated: ‘In many areas of occupational therapy practice, quantitative measures are required to document need for services and, increasingly, quantitative measures are required to document the value of these services in terms of the outcomes achieved.’ Therapists must be confident that the tests and measures that they use to evaluate clients are assessing what they purport they do in a rigorous and robust manner. In other words, the tests and measures must exhibit a high degree of construct validity. Assessment tools have been classified as bottom-up and top-down (Weinstock-Zlotnick and Hinojosa 2004). Bottom-up assessments are the traditional instruments that look at isolated, decontextualised components of occupational performance (such as whether a child can shift pegs in a board or place coins inside a small container), whereas top-down assessments look at individuals in their day-to-day real life contexts (such as whether a child is able to access the neighbourhood playground if he or she is confined to a wheelchair). Top-down assessments often take into consideration the person, the environment and the occupation. How do we ensure the construct validity of both bottom-up and top-down assessments?

Occurrence of seizures in association with work‐related stress in young male army recruits

To examine the risk of undergoing an epileptic seizure as a function of differing levels of occupational stress (physical and mental) in new military recruits with no previous history of epilepsy or with epilepsy in remission for over 2 years. The medical records of over 300,000 18-year-old men recruited to the Israeli army between mid-eighties and mid-nineties were used to assemble a cohort, which was followed for a period of 30 months. The severity of epilepsy at recruitment was determined according to four categories, 0 (no history of seizures) and 1-3 (history of seizures with different relapse-free periods, with or without treatment). The soldiers were subdivided according to their occupational categories to: combat units (CU), maintenance units (MU), and administrative units (AU). The annual incidence rates per 100,000 in category 0 were 317, 298, and 401 in AU, MU, and CU, respectively. The incidence of seizures in category 0 was higher (relative risk [RR]= 1.29, CI = 1.03-1.62) in CU compared to AU and MU. No differences were found for seizure recurrence among various occupational groups. The increased risk of seizures in CU compared to AU and MU may indicate contribution of service conditions in CU, like physical and mental stress. The equivalent rates of seizure relapse, regardless of the type of occupation, suggests the need for minimal occupational restrictions for epilepsy patients who have been free of seizures for long periods.

A COMPARISON OF IMPORTANT INTERNATIONAL AND NATIONAL STANDARDS FOR LIMITING EXPOSURE TO EMF INCLUDING THE SCIENTIFIC RATIONALE

A comparison of Eastern (from Russia, Hungary, Bulgaria, Poland, and the Czech Republic) and Western (represented by the International Commission on Non-Ionizing Radiation Protection guidelines and the Institute of Electrical and Electronic Engineers standards) radiofrequency standards reveals key differences. The Eastern approach is to protect against non-thermal effects caused by chronic exposure to low level exposure, and the occupational basic restriction is power load (the product of intensity and exposure duration). In contrast, the Western approach is to protect against established acute biological effects that could signal an adverse health effect, and the principal basic restriction is the specific absorption rate to protect against thermal effects. All of the standards are science-based, but a fundamental difference arises from a lack of agreement on the composition of the reference scientific database and of which adverse effect needs to be protected against. However, differences also exist between the ICNIRP and IEEE standards. An additional complication arises when standards are derived or modified using a precautionary approach. For ELF the differences between ICNIRP and IEEE are more fundamental; namely, differences in the basic restriction used (induced current; in-situ electric field) and the location of breakpoints in the strength-frequency curves result in large differences. In 2006, ICNIRP will initiate the review of their ELF and radiofrequency guidelines, and this will provide an opportunity to address differences in standards and the move towards harmonization of EMF standards and guidelines.

Dependency and Opportunity

This article explores the work environment as a site for interactions between Chinese and non-Chinese in New York City between 1870 and 1943. A gendered and racially stratified paid labor force, shaped by federal immigration restriction laws, migration and settlement patterns to and within New York City, state occupational restrictions, and the development of a skilled white male urban working class, created the economic conditions within which the Chinese and non-Chinese struggled to survive during the exclusion period (1882-1943). Mutually dependent relationships often developed out of these phenomena. The survival of Chinese communities depended upon whites as well as Chinese and the skills and services offered by men of European descent. In turn, white men in trades and small businesses depended upon Chinese customers and fellow merchants. Chinese/white relations during this period provide a glimpse into how both groups created livelihoods and in the process built ethnic and cross-cultural urban communities.

Does cumulating endurance training at the weekends impair training effectiveness?

Due to occupational restrictions many people's recreational endurance activities are confined to the weekends. We intended to clarify if cumulating the training load in such a way diminishes endurance gains. We conducted a longitudinal study comparing training-induced changes within three independent samples. Thirty-eight healthy untrained participants (45+/-8 years, 80+/-18 kg; 172+/-9 cm) were stratified for endurance capacity and sex and randomly assigned to three groups: 'weekend warrior' (n=13, two sessions per week on consecutive days, 75 min each, intensity 90% of the anaerobic threshold; baseline lactate+1.5 mmol/l), regular training (n=12, five sessions per week, 30 min each, same intensity as weekend warrior), and control (n=13, no training). Training was conducted over 12 weeks and monitored by means of heart rate. Identical graded treadmill protocols before and after the training program served for exercise prescription and assessment of endurance effects. VO2max improved similarly in weekend warrior (+3.4 ml/min per kg) and register training (+1.5 ml/min per kg; P=0.20 between groups). Compared with controls (-1.0 ml/min per kg) this effect was significant for weekend warriors (P<0.01) whereas there was only a tendency for the regular training group (P=0.10). In comparison with controls (mean decrease, 3 beats/min), the average heart rate during exercise decreased significantly by 11 beats/min (weekend warriors, P<0.01) and 9 beats/min (regular training, P<0.05). There was no significant difference, however, between the weekend warrior and regular training groups (P=0.99). In a middle-aged population of healthy untrained subjects, cumulating the training load at the weekends does not lead to an impairment of endurance gains in comparison with a smoother training distribution.

Phase transition of triplet reaction-diffusion models

The phase transitions classes of reaction-diffusion systems with multiparticle reactions are an open challenging problem. Large scale simulations are applied for the 3A --> 4A, 3A --> 2A and the 3A --> 4A, 3A --> [formula : see text] triplet reaction models with site occupation restriction in one dimension. Static and dynamic mean-field scaling are observed with signs of logarithmic corrections suggesting d(c) = 1 upper critical dimension for this family of models.

Potential Single-Occupancy Vehicle Demand for High-Occupancy Vehicle Lanes

In recent years, there has been a growing interest in the use of high-occupancy toll (HOT) lanes as an alternative to high-occupancy vehicle (HOV) lanes to help manage the increasing demand for travel. HOT lanes combine pricing and vehicle occupancy restrictions to optimize the demand for HOV lanes. As two of the five HOT lanes in the world, the HOT lane facilities in Houston, Texas, require peak period travelers in vehicles with two occupants to pay a toll to use the lanes. During other periods of the day, two-occupant vehicles can use the lanes for free. Single-occupancy vehicles (SOVs) are never allowed. There was an opportunity to increase the usage of these HOT lanes by allowing SOV travelers to use the lanes during the off-peak periods, for an appropriate toll. This research examined the potential SOV demand for HOV lane use during the off-peak periods from the Katy Freeway and Northwest Freeway general purpose lane travelers. Of course, allowing SOVs on the HOV lanes is a multifaceted policy decision that has not been tackled by the operating agencies, and this research simply estimates the demand if such an option existed. This included estimating two important factors that influenced travelers’ potential use of the HOV lanes: their value of travel time savings (VTTS) and their value of penalty for changing their travel schedule (VPCS). It was found that respondents had VTTS approximately 45% of their hourly wage rate and VPCS approximately 3% of their hourly wage rate. Combining this information with current travel time savings and available capacity on the HOV lanes, it was found that approximately 2,000 SOV travelers per day would pay a combined total of $4,500 to use the HOV lanes during the off-peak periods.

Potential Single-Occupancy Vehicle Demand for High-Occupancy Vehicle Lanes: Results from Stated-Preference Survey of Travelers in High-Occupancy Toll Corridors

In recent years, there has been a growing interest in the use of high-occupancy toll (HOT) lanes as an alternative to high-occupancy vehicle (HOV) lanes to help manage the increasing demand for travel. HOT lanes combine pricing and vehicle occupancy restrictions to optimize the demand for HOV lanes. As two of the five HOT lanes in the world, the HOT lane facilities in Houston, Texas, require peak period travelers in vehicles with two occupants to pay a toll to use the lanes. During other periods of the day, two-occupant vehicles can use the lanes for free. Single-occupancy vehicles (SOVs) are never allowed. There was an opportunity to increase the usage of these HOT lanes by allowing SOV travelers to use the lanes during the off-peak periods, for an appropriate toll. This research examined the potential SOV demand for HOV lane use during the off-peak periods from the Katy Freeway and Northwest Freeway general purpose lane travelers. Of course, allowing SOVs on the HOV lanes is a multifaceted policy decisi...

Factor Structure of the Trinity Amputation and Prosthesis Experience Scales (TAPES) with Individuals with Acquired Upper Limb Amputations

To investigate the factorial composition of the Trinity Amputation and Prosthesis Experience Scales (TAPES), a multidimensional assessment of adaptation to amputation and prosthesis, for use with individuals with acquired upper limb amputations. Cross-sectional survey of members of the British Limbless Ex-Service Men's Association. A total of 101 individuals (men, 100; mean age, 73.8 yrs, SD 11.94) with acquired upper limb amputations (98 traumatic cases) completed the TAPES. Principal components analyses with varimax rotation revealed four psychosocial subscales (general adjustment, social adjustment, optimal adjustment, and adjustment to limitation), four activity-restriction subscales (restriction of lifestyle, social restriction, occupational restriction, and restriction of mobility), and a single prosthesis-satisfaction subscale. Each of these subscales had high internal reliability. The TAPES structure can be meaningfully represented in terms of nine internally consistent subscales. Additional research needs to be done on the TAPES for use with individuals with upper limb amputations. In particular studies of the scales, predictive validity is warranted.

Polyvalence des allogreffes massives dans le traitement de tumeurs de l?hum�rus proximal

Endoprosthetic replacement (EPR) of the proximal humerus following tumour resection has resulted in proximal subluxation, pain, instability and poor function. Alternative reconstructive options to EPR include leaving the shoulder flail, insertion of a passive spacer and arthrodesis. Five patients were treated using massive cadaveric allografts as the method of reconstruction following tumour resection. The pathology was three osteosarcoma, one chondrosarcoma and one metastasis from a renal primary. The patients were evaluated clinically using the Musculoskeletal Tumour Society (MSTS) and Constant shoulder assessments. All four patients with primary tumours were alive and disease free at review after a median follow-up of 23 months (range 14–112). No patients suffered immediate complications. Three of the four patients were pain free. Function was limited, causing at least partial occupational restriction in three of four patients. Allograft remains a viable alternative to EPR in reconstruction following tumour resection. Costs are favourable, and patients gain good analgesia. Function is sacrificed (as it is in EPR), especially if tumour resection necessitates nerve sacrifice. In our patients, the allograft was used either as a passive spacer, arthrodesis or arthroplasty, demonstrating its versatility.

Suicide in doctors: A psychological autopsy study

Objectives: Doctors are at higher risk of suicide than many other occupational groups. This study was conducted to investigate factors associated with suicide in doctors. Method: Psychological autopsy study of 38 working doctors who died by suicide in England and Wales between January 1991 and December 1993. Results: Psychiatric illness was present in 25 of the doctors. Depressive illness and drug or alcohol abuse were the most common diagnoses. Twenty-five doctors had significant problems related to work, 14 had relationship problems and 10 had financial problems. Multiple and interrelated problems were often present. The most common method of suicide was self-poisoning, often with drugs taken from work. Conclusion: Prevention of suicide in doctors requires a range of strategies, including improved management of psychiatric disorder, measures to reduce occupational stress and restriction of access to means of suicide when doctors are depressed.

Phase transitions of the binary production 2A-->3A, 4A--> X model.

Phase transitions of the 2A-->3A, 4A--> X reaction-diffusion model is explored by dynamical, N-cluster approximations and by simulations. The model exhibits site occupation restriction and explicit diffusion of isolated particles. While the site mean-field approximation shows a single transition at zero branching rate introduced by Odor [G. Odor, Phys. Rev. E 67, 056114 (2003)], N>2 cluster approximations predict the appearance of another transition line for weak diffusion (D) as well. The latter phase transition is continuous, occurs at finite branching rate, and exhibits different scaling behavior. I show that the universal behavior of these transitions is in agreement with that of the diffusive pair contact process model both on the mean-field level and in one dimension. Therefore this model exhibiting annihilation by quadruplets does not fit in the recently suggested classification of universality classes of absorbing state transitions in one dimension [J. Kockelkoren and H. Chaté, Phys. Rev. Lett. 90, 125701 (2003)]. For high diffusion rates the effective 2A-->3A-->4A--> X reaction becomes irrelevant and the model exhibits a mean-field transition only. The two regions are separated by a nontrivial critical end point at D*.

Assessment of specific energy absorption rate (SAR) in the head from a TETRA handset

Finite-difference time-domain (FDTD) calculations of the specific energy absorption rate (SAR) from a representative TETRA handset have been performed in an anatomically realistic model of the head. TETRA (Terrestrial Trunked Radio) is a modern digital private mobile radio system designed to meet the requirements of professional users, such as the police and fire brigade. The current frequency allocations in the UK are 380–385 MHz and 390–395 MHz for the public sector network. A comprehensive set of calculations of SAR in the head was performed for positions of the handset in front of the face and at both sides of the head. The representative TETRA handset considered, operating at 1 W in normal use, will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a monopole antenna operating at 3 W in normal use will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a helical antenna operating at 3 W in normal use will show compliance with the ICNIRP occupational exposure restriction but will be over the public exposure restriction by up to ∼50% if kept in the position of maximum SAR for 6 min continuously.

Critical behavior in reaction-diffusion systems exhibiting absorbing phase transitions

Phase transitions of reaction-diffusion systems with site occupation restriction and with particle creation that requires n>1 parents and where explicit diffusion of single particles (A) exists are reviewed. Arguments based on mean-field approximation and simulations are given which support novel kind of non-equilibrium criticality. These are in contradiction with the implications of a suggested phenomenological, multiplicative noise Langevin equation approach and with some of recent numerical analysis. Simulation results for the one and two dimensional binary spreading 2A -> 4A, 4A -> 2A model display a new type of mean-field criticality characterized by alpha=1/3 and beta=1/2 critical exponents suggested in cond-mat/0210615.

Clinical Neuropsychology: Cognitive Function in Epilepsy

Clinical Neuropsychology: Cognitive Function in Epilepsy

Proximal row carpectomy: a minimum 10-year follow-up study

Purpose: To assess the long-term clinical and radiographic results after a proximal row carpectomy (PRC). Methods: Twenty patients with various degenerative and posttraumatic disorders of the wrist were evaluated. The evaluation consisted of a physical examination, plain radiographs, and completion of a questionnaire that assessed patient satisfaction, return to work status, occupational and recreational activities and restrictions, and pain level. Results: Two patients (10%) had persistent pain after a PRC requiring a radiocapitate arthrodesis. The remaining 18 patients were evaluated at an average follow-up of 13.1 years (range, 10.0–17.2 y). The average wrist range of motion was 63% and the average maximal grip strength was 83% of the opposite extremity, respectively. Seventeen patients were satisfied with their outcome. One patient complained of persistent pain and was not satisfied but did not want further surgery. All but 2 patients returned to their original occupation and activity level including all 5 patients involved in workers’ compensation. Follow-up radiographs showed flattening of the proximal capitate in 6 patients. Radiocapitate arthrosis was absent/minimal in 13 patients and moderate/severe in 4 patients. The presence of radiographic changes did not correlate with patient satisfaction or degree of wrist pain. Conclusions: Proximal row carpectomy is a dependable and durable procedure that results in satisfactory pain relief in the majority of patients, maintenance of functional wrist motion and grip strength, high patient satisfaction, and ability to return to work. Progressive symptomatic deterioration of the radiocapitate articulation was not observed.

Phase transition classes in triplet and quadruplet reaction-diffusion models.

Phase transitions of reaction-diffusion systems with site occupation restriction and with particle creation that requires n=3,4 parents, whereas explicit diffusion of single particles (A) is present are investigated in low dimensions by the mean-field approximation and simulations. The mean-field approximation of general nA-->(n+k)A, mA-->(m-l)A type of lattice models is solved and a different kind of critical behavior is pointed out. In d=2 dimensions, the 3A-->4A, 3A-->2A model exhibits a continuous mean-field type of phase transition, that implies d(c)<2 upper critical dimension. For this model in d=1 extensive simulations support a mean-field type of phase transition with logarithmic corrections unlike the recent study of Park et al. [Phys. Rev E 66, 025101 (2002)]. On the other hand, the 4A-->5A, 4A-->3A quadruplet model exhibits a mean-field type of phase transition with logarithmic corrections in d=2, while quadruplet models in one-dimensional show robust, nontrivial transitions suggesting d(c)=2. Furthermore, I show that a parity conserving model 3A-->5A, 2A--> zero in d=1 has a continuous phase transition with different kinds of exponents. These results are in contradiction with the recently suggested implications of a phenomenological, multiplicative noise Langevin equation approach and with the simulations on suppressed bosonic systems by Kockelkoren and Chaté [Phys. Rev. Lett. 90, 125701 (2003)].

Burden of relatives and their expectations towards psychiatric institutions. A review of the literature and own results

This article aimed to provide an overview regarding the burden of relatives of mentally ill patients and their expectations towards psychiatric institutions. The literature was selected from Medline covering the years 1996 - 2002. 342 articles were reviewed, 145 of which were described in this review. The burden of relatives are manifold and can be classified into the following categories: time spent on caring, financial difficulties, occupational restrictions, detrimental effects on relatives own physical and psychological well-being, reduction in leisure activities, negative effects on social relationships, experiences of discrimination and refusal, deficiencies in information about illness, feelings of not being taken seriously, insufficient service support, long distance to mental health service, emotional burdens of caregivers and difficulties with the patients behaviour. The expectations of the relatives mainly refer to the categories "relationship between staff and relatives", "information about illness" and "establishing of institutions required". The various burdens of relatives and their expectations towards psychiatric services point to necessary improvements of mental health services in the sense of a consumer-oriented psychiatric care.

Analysis of arthroscopically assisted ankle arthrodesis

Purpose: Evaluation of an arthroscopically assisted ankle arthrodesis technique for clinical and radiographic union, function, and patient satisfaction. Type of Study: Retrospective analysis and review of the literature. Methods: Twenty-one patients with a mean age of 52.7 years who underwent arthroscopic ankle arthrodesis were examined at an average follow-up time of 34 months. The mean duration of symptoms was 4.4 years. The most common diagnosis for patients who underwent arthrodesis was post-traumatic arthritis (19 of 21) with 1 patient having a diagnosis of avascular necrosis of the talus and the other patient having rheumatoid arthritis. All patients described severe mechanical pain as the most important reason for undergoing the procedure. Results: Fusion occurred in 20 of 21 patients. The average time to clinical and radiographic union was 8.9 weeks. Nine patients were graded as excellent; no pain, limp, or occupational restriction, and a stable fusion. Eleven were graded as good; mild pain, occasional limp, or occupational restriction with a stable fusion. One was graded as poor; failed union and pain. The failure had extensive avascular necrosis involving approximately 50% of the talus as a preoperative diagnosis. Conclusions: The advantages of the arthroscopic technique include a high fusion rate, decreased time to fusion, and decreased cost. There are considerable advantages to the arthroscopic technique in appropriately selected patients with no or mild angular deformity and no avascular necrosis greater than 30% of the talus. There is a substantial reduction in time to fusion in the arthroscopic procedure compared with published reports on open procedures for ankle arthrodesis. While this procedure is not indicated in all instances, selected patients with disabling ankle arthrosis may be more appropriately treated with an arthroscopic arthrodesis than by open surgery.