Don't Change Much.

Few studies have assessed differences in the prevalence of and economic burden attributable to tobacco smoking, excess weight, physical inactivity, and alcohol use by gender. This article examines these gender differences in Canadians between the ages of 30 and 64 years. It also estimates the potential cost avoidance if the prevalence of the four risk factors (RFs) were reduced modestly in males. Data on the prevalence of the RFs and the relative risk of disease associated with each of the RFs were combined to calculate population-attributable fractions. A prevalence-based cost-of-illness approach was used to estimate the economic burden associated with the four RFs. Middle-aged Canadian males are more likely to smoke tobacco (26.4% vs. 20.2%), consume hazardous or harmful levels of alcohol (14.6% vs. 8.2%), and have excess weight (65.6% vs. 47.1%) than middle-aged Canadian females, resulting in an annual economic burden that is 27% higher in males than females. No significant differences were observed in the proportion of males who are physically inactive (48.4% vs. 49.4%). Modelling only a 1% annual relative reduction each year through to 2036 would result in a cumulative cost avoidance between 2013 and 2036 of $50.7 billion. The differences in RF prevalence between middle-aged males and females have an important effect on the population's economic burden. A modest annual reduction in the four RFs in males can significantly affect population health and the economy over time.

The economic burden of cancers attributable to tobacco smoking, excess weight, alcohol use, and physical inactivity in Canada.

OBJECTIVES: The purpose of the present study was to calculate the proportion of cancers in Canada attributable to tobacco smoking (ts), alcohol use (au), excess weight (ew), and physical inactivity (pia); to explore variation in the proportions of those risk factors (rfs) over time by sex and province; to estimate the economic burden of cancer attributable to the 4 rfs; and to calculate the potential reduction in cancers and economic burden if all provinces achieved rf prevalence rates equivalent to the best in Canada. METHODS: We used a previously developed approach based on population-attributable fractions (pafs) to estimate the cancer-related economic burden associated with the four rfs. Sex-specific relative risk and age- and sex-specific prevalence data were used in the modelling. The economic burden was adjusted for potential double counting of cases and costs. RESULTS: In Canada, 27.7% of incident cancer cases [95% confidence interval (ci): 22.6% to 32.9%] in 2013 [47,000 of 170,000 (95% ci: 38,400-55,900)] were attributable to the four rfs: ts, 15.2% (95% ci: 13.7% to 16.9%); ew, 5.1% (95% ci: 3.8% to 6.4%); au, 3.9% (95% ci: 2.4% to 5.3%); and pia, 3.5% (95% ci: 2.7% to 4.3%). The annual economic burden attributable to the 47,000 total cancers was $9.6 billion (95% ci: $7.8 billion to $11.3 billion): consisting of $1.7 billion in direct and $8.0 billion in indirect costs. Applying the lowest rf rates to each province would result in an annual reduction of 6204 cancers (13.2% of the potentially avoidable cancers) and a reduction in economic burden of $1.2 billion. CONCLUSIONS: Despite substantial reductions in the prevalence and intensity of ts, ts remains the dominant risk factor from the perspective of cancer prevention in Canada, although ew and au are becoming increasingly important rfs.

Regional variations in the economic burden attributable to excess weight, physical inactivity and tobacco smoking across British Columbia.

INTRODUCTION: Prevalence rates of excess weight, tobacco smoking and physical inactivity vary substantially by geographical region within British Columbia (B.C.). The purpose of this study is to determine the potential reduction in economic burden in B.C. if all regions in the province achieved prevalence rates of these three risk factors equivalent to those of the region with the lowest rates. METHODS: We used a previously developed approach based on population-attributable fractions to estimate the economic burden associated with the various risk factors. Sex-specific relative risk and age/sex-specific prevalence data was used in the modelling. RESULTS: The annual economic burden attributable to the three risk factors in B.C. was about $5.6 billion in 2013, with a higher proportion of this total attributable to excess weight ($2.6 billion) than to tobacco smoking ($2.0 billion). While B.C. has lower prevalence rates of the risk factors than any other Canadian province, there is significant variation within the province. If each region in the province were to achieve the best prevalence rates for the three risk factors, then $1.4 billion (24% of the $5.6 billion) in economic burden could be avoided annually. CONCLUSION: There are notable disparities in the prevalence of each risk factor across health regions within B.C., which were mirrored in each region's attributable economic burden. A variety of social, environmental and economic factors likely drive some of this geographical variation and these underlying factors should be considered when developing prevention programs.

TITRE: Écarts régionaux dans le fardeau économique attribuable au surplus de poids, à la sédentarité et à l'usage du tabac en Colombie-Britannique. INTRODUCTION: Les taux de prévalence du surplus de poids, de l'usage du tabac et de la sédentarité varient sensiblement d'une région à l'autre en Colombie-Britannique (C.-B.). La présente étude vise à déterminer la portée d'une éventuelle réduction du fardeau économique en C.-B. si toutes les régions de la province atteignaient des taux de prévalence équivalents à ceux de la région dont les taux sont les plus bas pour ces trois facteurs de risque. MÉTHODOLOGIE: Nous avons utilisé une approche élaborée précédemment fondée sur la fraction étiologique du risque pour estimer le fardeau économique associé aux divers facteurs de risque. Le risque relatif selon le sexe et les données de prévalence selon l'âge et le sexe ont été utilisés dans la modélisation. RÉSULTATS: Le fardeau économique annuel attribuable à ces trois facteurs de risque en C.-B. s'élevait à environ 5,6 milliards de dollars en 2013, la proportion la plus élevée de ce total étant attribuable au surplus de poids (2,6 milliards), suivie de celle de l'usage du tabac (2 milliards). Même si la C.-B. possède des taux de prévalence de ces facteurs de risque plus bas que toute autre province canadienne, il existe d'importants écarts en son sein. Si chaque région de la province devait atteindre les taux de prévalence les plus bas pour les trois facteurs de risque, un fardeau économique de 1,4 milliard (24 % du total de 5,6 milliards) pourrait être supprimé annuellement. CONCLUSION : Il existe des disparités notables dans la prévalence de chacun des facteurs de risque au sein des régions sanitaires de la C.-B., qui se reflètent dans le fardeau économique attribuable à chaque région. Un éventail de facteurs sociaux, environnementaux et économiques expliquent probablement une partie de ces écarts géographiques, et ces facteurs sous-jacents devraient être pris en compte lors de la mise en place de programmes de prévention.

Improved estimation of the health and economic burden of chronic disease risk factors in Manitoba.

INTRODUCTION: There are analytic challenges involved with estimating the aggregate burden of multiple risk factors (RFs) in a population. We describe a methodology to account for overlapping RFs in some sub-populations, a phenomenon that leads to "double-counting" the diseases and economic burden generated by those factors. METHODS: Our method uses an efficient approach to accurately analyze the aggregate economic burden of chronic disease across a multifactorial system. In addition, it involves considering the effect of body weight as a continuous or polytomous exposure that ranges from no excess weight through overweight to obesity. We then apply this method to smoking, physical inactivity and overweight/obesity in Manitoba, a province of Canada. RESULTS: The annual aggregate economic burden of the RFs in Manitoba in 2008 is about $1.6 billion ($557 million for smoking, $299 million for physical inactivity and $747 million for overweight/obesity). The total burden represents a 12.6% downward adjustment to account for the effect of multiple RFs in some individuals in the population. CONCLUSION: An improved estimate of the aggregate economic burden of multiple RFs in a given population can assist in prioritizing and gaining support for primary prevention initiatives.

TITRE: Meilleure estimation du fardeau que représentent les facteurs de risque de maladie chronique pour la santé et l'économie au Manitoba. INTRODUCTION: L'estimation du fardeau global que représentent les facteurs de risque multiples au sein d'une population présente certains défis d'ordre analytique. Nous décrivons une méthodologie permettant de tenir compte des facteurs de risque se chevauchant dans certaines sous-populations et entraînant un « double compte ¼ des maladies et du fardeau économique qu'ils engendrent. MÉTHODOLOGIE: Notre démarche permet d'analyser avec précision le fardeau économique global des maladies chroniques dans un cadre multifactoriel tout en tenant compte de l'incidence du poids en tant qu'exposition continue ou polytomique (allant de l'absence d'excédent de poids au surpoids et à l'obésité). Nous appliquons cette méthode au tabagisme, à l'inactivité physique et au surpoids et à l'obésité à la province du Manitoba (Canada). RÉSULTATS: En 2008, le fardeau économique global annuel des facteurs de risque au Manitoba était d'environ 1,6 milliard de dollars (557 millions pour le tabagisme, 299 millions pour l'inactivité physique et 747 millions pour le surpoids et l'obésité). Le fardeau total représente un rajustement à la baisse de 12,6 % lorsqu'on tient compte de l'effet des facteurs de risque multiples chez certaines personnes. CONCLUSION: Une meilleure estimation du fardeau économique global des facteurs de risque multiples au sein d'une population peut faciliter l'établissement des priorités et améliorer le soutien aux initiatives de prévention primaire.

The economic burden of traumatic spinal cord injury in Canada.

INTRODUCTION: The purpose of this study is to estimate the current lifetime economic burden of traumatic spinal cord injury (tSCI) in Canada from a societal perspective, including both direct and indirect costs, using an incidence-based approach. METHODS: Available resource use and cost information for complete/incomplete tetraplegia and paraplegia was applied to the estimated annual incidence of tSCI, by severity, in Canada. RESULTS: The estimated lifetime economic burden per individual with tSCI ranges from $1.5 million for incomplete paraplegia to $3.0 million for complete tetraplegia. The annual economic burden associated with 1389 new persons with tSCI surviving their initial hospitalization is estimated at $2.67 billion. CONCLUSION: While the number of injuries per year in Canada is relatively small, the annual economic burden is substantial.

TITLE: Fardeau économique lié aux traumatismes de la moelle épinière au Canada. INTRODUCTION: Cette étude vise à mesurer, au moyen d'une approche fondée sur l'incidence, le fardeau économique à vie lié aux traumatismes de la moelle épinière (TME) au Canada du point de vue social, en incluant les coûts directs et indirects. MÉTHODOLOGIE: Les ressources disponibles et l'information sur les coûts liés aux cas de tétraplégie et de paraplégie complètes et incomplètes ont été appliquées à l'incidence annuelle estimative des TME au Canada en fonction de leur gravité. RÉSULTATS: Le fardeau économique à vie d'une personne atteinte d'un TME varie de 1,5 million de dollars pour une paraplégie incomplète à 3 millions de dollars pour une tétraplégie complète. Le fardeau économique annuel lié aux 1 389 nouveaux cas de TME où le patient a survécu à son hospitalisation est estimé à 2,67 milliards de dollars. CONCLUSION: Malgré leur fréquence annuelle relativement faible au Canada, ces blessures entraînent un fardeau économique annuel important.

The influence of depression on physical complications in spinal cord injury: behavioral mechanisms and health-care implications.

STUDY DESIGN: This study is a literature review and a proposed conceptual model. OBJECTIVES: The objective of this study is to develop a conceptual model to explore the relationship between the presence of depressive symptoms and secondary physical complications such as pressure ulcers, urinary tract infections and autonomic dysreflexia in spinal cord injury (SCI). SETTING: Community setting for individuals with SCI. METHODS: A conceptual model explaining the mechanism underlying the relationship between depression and secondary physical SCI complications was developed based on the International Classification of Functioning, Disability and Health (ICF). A literature review was conducted to develop the model and to identify potential mechanisms responsible for the association. RESULTS: A conceptual model based on ICF was created, informed by the literature discussing the link between depression and secondary physical SCI complications. Evidence in the literature was located that supports both a causal connection between depression and increased physical complications and/or the potential mechanisms mediating that connection. CONCLUSION: The proposed model can be utilized to encourage further research on the influence of depression on SCI outcomes and the importance of prompt and effective identification and treatment of depressive symptoms. Additional research is needed to assess the relationship between depression and secondary physical SCI complications, and to test the validity of the model.

Studies and evaluation of the potential toxicity of decabromodiphenyl ethane to five aquatic and sediment organisms.

The potential toxicity of decabromodiphenyl ethane (DBDP-Ethane) was explored in 5 types of organisms residing in the water column and/or sediment, e.g. Oncorhynchus mykiss, Pseudokirchneriella subcapitata, Daphnia magna, Chironmus riparius, and Lumbriculus variegates. Fish, algae or Daphnia were unaffected by acute exposures to water accommodated fractions of 110mg DBDP-Ethane/L. Chronic exposure to DBDP-Ethane at the highest dose tested, 5000mg/kg dry sediment, did not affect midge mean development times, emergence or development rates or oligochaete survival, reproduction or dry weight. The chronic EC50, LOEC and NOEC were ≥5000mg/kg in the two sediment species. Applying an assessment factor of 50, the unbounded predicted no effect concentration (PNEC(sediment)) was 100mg/kg dry sediment. The calculated PNEC indicates DBDPE-Ethane presents little risk to sediment organisms. These results add to DBDP-Ethane's existing database in the terrestrial compartment and mammals.

Terrestrial toxicity evaluation of decabromodiphenyl ethane on organisms from three trophic levels.

Decabromodiphenyl ethane (DBDP-Ethane) was evaluated for its potential to effect sewage sludge respiration, soil nitrification, survival and reproduction in Eisenia fetida, and seedling emergence and growth in Zea mays, Lolium perenne, Glycine max, Allium cepa, Lycopersicon esculentum, and Cucumis sativa. The no observed effect concentrations (NOECs) were identified at the limit concentration level for sewage sludge respiration (>10 mg DBDP-Ethane/kg dry soil), >2500 mg/kg dry soil for soil nitrification, >3720 mg/kg dry soil for earthworm survival, and >6250 mg/kg dry soil for seedling emergence and growth in Z. mays, L. perenne, and G. max . Treatment-related effects were identified for E. fetida reproduction, C. sativa survival, and L. esculentum and A. cepa height and dry weight. The most sensitive endpoints were decreased height and dry weight for A. cepa and decreased reproduction for E. fetida with NOECs of 1563(nominal) (1540(measured)) and 2210(nominal) (1907(mean measured)) mg/kg dry soil. The NOEC for soil nitrification and the lowest NOEC identified for soil (i.e., A. cepa) were used to derive predicted no effect concentrations (PNEC) values of 2500 mg/kg for sewage sludge and 156 mg/kg for soil. The calculated PNECs indicate DBDP-Ethane presents little risk to organisms in the sewage sludge and soil compartments.

[Comparing specific disc findings of a European and a Bantu population]. / Vergleich papillenspezifischer Parameter einer europäischen und einer Bantu-Population.

BACKGROUND: Glaucoma is the main cause of irreversible blindness in the world. Because of the increasing mean age, glaucoma is expected to become more common in the developing countries. Besides tonometry and perimetry the appearance of the optic nerve head is a main part of glaucoma diagnosis. Ethnic differences have to be considered. This study compares the appearance of the optic nerve head between blacks and whites. STUDY DESIGN: This is a retrospective analysis of 225 whites of a Swiss population and 1027 blacks of a Congolese population. Using a matched pairs technique 207 whites and 207 blacks were chosen, regarding age, sex, intraocular pressure and examined eye (right/left). The analysis of the optic nerve head was performed by using the "Heidelberg-Retina-Tomograph II" (HRT). RESULTS: Among the 207 persons of both groups we found 116 females and 91 males. There were 103 right eyes and 104 left eyes examined. The mean age was 45.6 +/- 15.6 years. Compared with European population in the African population we found a greater disc area (2.56 vs. 1.81 mm(2)) as well as a greater cup area (0.65 vs. 0.41 mm(2)) and a greater rim area (1.91 vs. 1.40 mm(2)). Regarding the cup disc area ratio there was no significant difference between both populations found (Kinshasa: 0.24 vs. Basel: 0.21). Although there was no significant difference of the maximum cup depth of both groups we found a deeper mean cup depth in the African population. Furthermore, we found differences regarding the cup shape measure, the RNFL thickness and the height variation contour. CONCLUSION: As already described in different studies, there are significant differences in the morphology of the optic nerve head between blacks and whites. Although blacks are expected to have a greater cup disc area ratio, this fact could not be proved in this study. As a new fact we found a different mean cup depth between Africans and Europeans, which might be explained by the different cup shape of both populations.

Information access at the point of care: what can we learn for designing a mobile CPR system?

OBJECTIVES: Hospitals have started to migrate their paper-based records to computerized patient records (CPR). The majority of today's CPR systems are stationary, which means that physicians use a clinical workstation to access CPR information. But health care professionals need to request and enter information at different locations, for example, on their daily ward round. This suggests the use of mobile computers, enabling an ubiquitous access to needed data. Different studies show that health care professionals are reluctant to use poorly designed mobile CPR systems, as the work at the point of care is very time-pressured and hectic. To design a system with high acceptance, it is essential to obtain empirical insight into the work practices and context in which the mobile CPR system will be used. METHOD: We investigated the physicians' work with the patient record during their daily round. With the help of a compact notation method, the physicians' interaction with the information system was recorded in real time. Fourteen physicians from three different departments (internal medicine, surgery, and geriatrics) of a middle-sized Swiss hospital participated in our study. RESULTS: Physicians have clear access preferences when they interact with the patient record during their daily round. There exists a clear profile of access frequencies and patterns, respectively. As an example, approximately 50% of all patient record accesses concern information about medications, vital signs and lab test results. DISCUSSION/CONCLUSION: A CPR system which is designed to reflect the access frequencies and patterns should improve the efficiency of data entry and retrieval and thus result in a system with high acceptance among physicians in the demanding environment during hospital rounds.

The sun and heliosphere at solar maximum.

Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun's rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.

Course of low back pain among nurses: a longitudinal study across eight years.

AIMS: To describe the course of low back pain (LBP) among nurses across eight years. METHODS: A longitudinal study was performed with a follow up at 1 and 8 years among nurses employed by a large university hospital in Switzerland. A modified version of the Nordic Questionnaire was distributed to obtain information about demographic data, occupational activities, and various aspects of LBP. A clinical examination and several functional tests were used to overcome the problems associated with subjective pain reporting. Nurses having answered the questionnaire on all three occasions (n = 269) were classified into subgroups according to their pain intensity. For each subgroup the course of LBP was recorded. RESULTS: LBP was highly prevalent with an annual prevalence varying from 73% to 76%. A large percentage (38%) indicated the same intensity of LBP on all three occasions. The proportion of nurses reporting repeated increase of LBP (19%) was approximately as large as the proportion who complained about repeated decrease of LBP (17%). CONCLUSION: It became evident that LBP poses a persistent problem among nurses. Over an eight year period almost half of the nurses indicated the same intensity of LBP, thus supporting a recurrent rather than a progressive nature of LBP.

Continuous, intermitted and sporadic motor unit activity in the trapezius muscle during prolonged computer work.

The Cinderella hypothesis postulates the continuous activity of specific motor units (MUs) during low-level muscle contraction. The MUs may become metabolically overloaded, with the subject developing muscle pain and strain. The hypothesis requires MUs that are active for a time long enough to actually damage muscle fibers. The aim of this study was to determine if there are continuously active MUs in the right trapezius muscle during normal computer work using a computer mouse. Fourteen healthy subjects executed an interactive computer-learning program (ErgoLight) for 30 min. Six-channel intramuscular EMG and two-channel surface EMG signals were recorded from two positions of the trapezius muscle. Decomposition was achieved with automated, multi-channel, long-term decomposition software (EMG-LODEC). In two out of the 14 subjects, three MUs were continuously active throughout the 30 min. Although the majority of the MUs were active during only part of the experimental session, an ordered on-off behavior (e.g. substitution) pattern was not observed. As long-lasting activity was verified in some subjects, the results support the Cinderella hypothesis. However, it cannot be concluded here how long the MUs could stay active. If continuous activity overloads low threshold MUs, the potential exists for selective fibre injuries in low threshold MUs of the trapezius muscle in subjects exposed to long-term computer work.

[Participation--oriented analysis of the anesthesia workplace. A work system for anesthesia in a multidisciplinary operating room]. / Beteiligungsorientierte Arbeitsplatzanalyse. Schwachstellen im Arbeitssystem der Anästhesie in einem multidisziplinären OP-Trakt.

INTRODUCTION: The aim of this study was the detection and understanding of weak points in the ergonomic design of anaesthesia workplaces in a multidisciplinary operating room facility. METHODS: Analysis of workplaces and of working processes by means of observations, computer-supported task recording and video-photo documentation. During guided interviews the participants were provided with material for naming-by-pointing and drawing. Subsequently, the background of the problems encountered and possible improvements were visualised. RESULTS: Important deficits were devices not positioned within reach and view, difficulties in operating the lines connecting the patient and the devices, and inconsistent workplace layouts. These were caused by erroneous planning of the facility and disregarding ergonomic principles in equipment design. The initial improvements implemented were the development of a new concept for a flexible equipment positioning and the design of a tool for cable handling. DISCUSSION AND CONCLUSION: Although from the very beginning of the study the anaesthesia personnel quoted the handling of the lines connecting patients and devices as the main cause for working difficulties, the external ergonomist could contribute to a broader view of the problems. The method presented here initiated a mutual learning process between ergonomist and users and resulted in a common understanding of the problems and their causes. Compared to the traditional consulting process, more time and efforts were necessary but were offset by the users' acceptance of the improvements and the prevention of design errors.

Economic analysis of basiliximab in renal transplantation.

BACKGROUND: Basiliximab is a chimeric monoclonal directed against the alpha-chain of the interleukin-2 receptor. International studies have shown that it is highly effective in preventing acute rejection in patients receiving Neoral, and causes no measurable incremental toxicity, but its economic value remains unknown. METHODS: This study employed an economic model to examine the potential economic benefit of basiliximab. Parameter estimates were derived from a randomized, prospective, double-blind study conducted in 21 renal transplant centers in seven countries in which 380 adult primary allograft recipients were randomized within center to receive basiliximab (20 mg i.v.) on days 0 and 4 or placebo in addition to dual immunosuppression with Neoral and steroids. Key clinical events included primary hospitalization, immunosuppressive drug use, patient and graft survival, graft rejection, treatment of rejection, dialysis, and repeat hospitalization. Health resources were valued via a comprehensive electronic cost dictionary, based upon a detailed economic evaluation of renal transplantation in Canada. Medication costs were calculated from hospital pharmacy acquisition costs; basiliximab was assessed a zero cost. RESULTS: The average estimated cost per patient for the first year after transplant was $55,393 (Canadian dollars) for placebo and $50,839 for basiliximab, rising to $141,690 and $130,592, respectively, after 5 years. A principal component of the cost in both groups was accrued during the initial transplant hospitalization ($14,663 for standard therapy and $14,099 for basiliximab). An additional $15,852 and $14,130 was attributable to continued care, graft loss, and dialysis in the two groups, whereas follow-up hospitalization consumed an additional $15,538 for placebo and $13,916 for basiliximab. The mean incremental cost of dialysis was $5,397 for placebo compared with $3,821 for basiliximab, whereas incremental costs of graft loss were $2,548 compared with $2,295 in the two treatment groups. The principal costs associated with repeat admission to the transplant ward and the general ward were marginally higher for placebo ($7,395 vs. $6,300 and $5,986 vs. $4,625). Treatment of acute rejection and maintenance immunosuppressive drug use were associated with only limited savings as a result of basiliximab (savings <$200 each). Sensitivity analysis indicated that the most influential parameters affecting the savings as a result of using basiliximab were a reduction in the duration of initial and repeat hospitalization followed by the reduced risks of acute rejection and graft loss. CONCLUSIONS: Before accounting for the cost of the therapy itself, basiliximab produces an estimated economic saving of $4,554 during the first year after transplant, of which $3,344 is attributable to the reduced costs of graft dysfunction, including graft loss and dialysis ($1,722) and follow-up hospitalizations ($1,622). When marketed, basiliximab is expected to cost approximately $3,000 per course (two doses of 20 mg), resulting in a net first-year saving of $1,554. Under these circumstances, basiliximab can be considered a dominant therapy in renal transplantation.

[Virtual retinal display system with nodal point image of a laser beam: construction example and evaluation of subjective brightness perception]. / Netzhautanzeigesystem ("virtual retinal display") mit Knotenpunktabbildung eines Laserstrahles: Konstruktionsbeispiel und Bewertung des subjektiven helligkeitseindruckes.

We investigated the perception of brightness for red monochromatic laser light. For this purpose, a modified virtual retinal display (VRD) was constructed. The modification involved projecting the laser beam into the eye. In our VRD, the laser beam pivots in the nodal point of the eye (badal system). The displayed image therefore does not depend on the refractive state of the eye. Brightness perception was assessed by means of psychophysical experiments. The results of these experiments indicate that perception of brightness at 652 nm increases more rapidly with increasing physical stimulus than does the perception of white light (colour temperature 2'935 K). At a wavelength of 652 nm, an optical power of 79 nW is required to produce an image subtending 2 degrees of equal brightness, as is perceived with an image of about 2'900 cd/m2 subtending 2 degrees.

Contraception. Myths, facts and methods.

OBJECTIVES: After reading this article, the reader should be able to: 1. Recognize the mechanism of action, side effects, contraindications, precautions and instructions for use of a variety of contraceptive methods. 2. Understand the advantages and disadvantages of the various contraceptive methods. 3. List the common myths and misconceptions about conception and contraception, and recognize how they can influence contraceptive decisions. Unintended pregnancy is a serious problem in the United States. Counseling a patient about conception and contraception involves more than simply imparting information and answering questions. Clinicians should actively detect and correct any myths and misapprehensions on the patient's part. These myths are quite common and can interfere with treatment if not attended to. This article summarizes common myths about pregnancy and contraception and reviews the key facts about both.

Motor-unit activity in the trapezius muscle during rest, while inputting data, and during fast finger tapping.

The Cinderella hypothesis postulates the continuous activity of specific motor units during low-level muscle contraction and contradicts the concept of motor-unit substitution. Constant trapezius muscle activity has been reported in typical visual-display-unit-related tasks. If it can be shown that constant muscle activity can be caused by the continuous firing of single motor units, this could explain the frequent complaints of muscular neck pain reported by computer users. The present study was undertaken to investigate motor-unit activity in the trapezius muscle during resting with closed eyes, while inputting three-digit numbers with auditory presentation at a rate of 0.5 Hz, and while tapping on a key with the right index finger at a rate of 5 Hz. Electrodes with four fine wires were inserted into the right upper trapezius muscle of six healthy subjects, and three-channel intramuscular electromyography was recorded. The decomposition programme MAPQuest, developed to analyse short-term one-channel signals, was complemented with MAPView, a programme that merges the short-term results of 10 s to a 3-min analysis. The results showed that activity in the trapezius muscle was induced in one subject while resting, in two subjects while inputting data, and in five subjects while finger tapping. Long-lasting single motor-unit firing was observed in two subjects while inputting data and in one subject while finger tapping. Whilst our findings may support the Cinderella hypothesis, the measurement periods are too short to confirm it fully, and for further discussion it is necessary to record and analyse for longer periods.

Co-activity of the trapezius and upper arm muscles with finger tapping at different rates and trunk postures.

In the context of finding a model that describes the pathophysiological mechanisms leading to muscle pain at low-intensity repetitive work, in this study we investigated whether a simplified finger motor task that requires little mental demand can cause increased muscle activity in the upper arms and neck, and examined the impact of the variation of two parameters, finger tapping rate and body posture. Using the 5th and 95th percentiles from the surface electromyogram of six muscles of the fingers, upper arm and neck, we determined the static and dynamic components of the muscle activity. Correlation methods were used to find a component in the muscle activity that originated from the rhythm of the finger tapping. Further investigations included tapping steadiness and finger force. It was found that in many, but not all subjects, low or even high activity was constantly present in the upper arm and trapezius muscles, sometimes even during relaxation. Fast tapping and a forward-leaning body posture caused considerable increases, while a slightly reclined posture helped to reduce co-activity. However, motor control patterns varied strongly between individuals. Since certain subjects showed no co-activity at all we can assume that trapezius and upper-arm activation is not necessarily required for the completion of a task similar to ours. This may explain why some VDU users develop work-related musculoskeletal disorders while others remain healthy.

Isopropanol and methylformate exposure in a foundry: exposure data and neurobehavioural measurements.

OBJECTIVES: The aim of this study was to determine the dose-effect relationship between solvent exposure and acute neurobehavioural effects at the worksite. METHODS: In a balanced design, ten workers in a Swiss foundry were monitored for 15 days at ten different times during work. Urine samples were taken in the morning and at the time of examination, and personal exposure to isopropanol and methylformate was measured with active samplers. Neurobehavioural tests such as postural balance (bipedal, bipedal blind, monopedal), simple reaction time and digit span of the Neurobehavioural Evaluation System (NES2) and a combined memory and reaction-time test, the combi-test, were performed. A rating of well-being, and the last consumption of alcohol, caffeine, nicotine and medication were reported. RESULTS: Average environmental concentrations of isopropanol were at 44 ppm ( +/- 16 ppm), and at 36 ppm (+/-21 ppm) for methylformate. Maximum values of personal exposure to isopropanol reached barely the maximal allowable concentration (MAC) value (400 ppm); the methylformate personal exposure of three workers exceeded the MAC value (100 ppm). Urine concentrations of methanol were high (3.1 +/- 2.3 mg/l in the morning, 7.8 +/- 4.9 mg/l after exposure) compared with the results of other studies; concentrations of isopropanol were rather low (0.88 +/- 0.73 mg/l after exposure). CONCLUSIONS: Nevertheless, between personal exposure and biomonitoring, linear correlation was found. Methylformate exposure correlated with methanol and formic acid concentration in the urine, and isopropanol exposure with its concentration in the urine. With the neurobehavioural tests used, no solvent effect in relation to the dose could be determined.