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Field studies have shown that there is a seasonal variation in mitosis of lens and corneal epithelium (high in May and June, low during the rest of the year). This phenomenon can be reproduced in the laboratory by temperature manipulation. The response in the lens depends on the presence of the pituitary gland while the corneal one seems to be independent of it.
A field study among workers in the fish processing industry (n = 143) was performed to obtain information about skin surface temperature, transepidermal water loss (TEWL), and electrical capacitance and their relationships during work. The skin temperature, TEWL and electrical capacitance were measured on the fingers, hands and forearms. A linear positive relation was found between the temperature and TEWL (in all measured areas), a linear negative relation between the temperature and capacitance (fingers and palms), and a linear negative relation between the capacitance and TEWL (fingers). The results on the fingers among workers in the fish processing industry were compared with results among metal workers (n = 52), cleaners (n = 30), gut cleaners (n = 25), nurses (n = 16), office workers with indoor climate syndrome (n = 20) and normal controls (n = 29). A linear positive relation was found between the respective temperature-TEWL values and a linear negative relation between the respective temperature-capacitance values in the various groups. Furthermore the slope of the temperature-TEWL relations was identical in all groups. Therefore, differences in TEWL levels (comparison at the same temperature) between the respective groups and controls and between the various groups might indicate damage to the skin barrier caused by contact with different irritants and chemicals. However, differences in environment-related variables in the various occupations might also affect TEWL levels. This field study demonstrates, from a practical point of view, how the skin temperature affects TEWL in the various occupations and, as a new point, how sensitive capacitance is to changes in skin temperature. Seasonal variation in TEWL and capacitance was demonstrated among workers in the fish processing industry, with a low TEWL and a high capacitance during summer when the workload is lower.
A field study was conducted to evaluate the delayed-type hypersensitivity (DTH) test in diagnosing brucellosis in cattle, in particular the diagnosis of infection in individual cows. A total of 93 cows that were negative, suspect, or positive to the serum agglutination test (SAT), complement fixation test (CFT), or the milk ring test (MRT) were subjected to the DTH test. The cows were then slaughtered and the supramammary lymph nodes were collected for bacteriologic examination. In 989 cows the DTH test, MRT and serologic tests were negative. When the DTH test results were compared with bacteriologic results, 12 of the 93 cows with CFT titres greater than 1:200 tested negative in the DTH test while bacteriologic results were positive. The sensitivity of the DTH test (calculated on the remaining 81 cows) was 100%; the specificity was 83%. The sensitivity of the DTH test (calculated on 93 cows) was 81%; the specificity was 83%. The sensitivity and specificity of the DTH test correlated well with those of the CFT (86-83%). We conclude that the DTH test is very sensitive, and specific enough to diagnose brucellosis in individual cows. The DTH test should be used in combination with serologic tests in the diagnosis of brucellosis.
Two field studies explored the relationship between self-awareness and transgressive behavior. In the first study, 363 Halloween trick-or-treaters were instructed to only take one candy. Self-awareness induced by the presence of a mirror placed behind the candy bowl decreased transgression rates for children who had been individuated by asking them their name and address, but did not affect the behavior of children left anonymous. Self-awareness influenced older but not younger children. Naturally occurring standards instituted by the behavior of the first child to approach the candy bowl in each group were shown to interact with the experimenter's verbally stated standard. The behavior of 349 subjects in the second study replicated the findings in the first study. Additionally, when no standard was stated by the experimenter, children took more candy when not self-aware than when self-aware.
A field study on respiratory muscle function and basic pulmonary mechanics was conducted at an international convention of 200 individuals with Charcot-Marie-Tooth disease. Forty patients with respiratory symptoms were evaluated; 15 had significant respiratory muscle dysfunction and 25 were normal. The results suggest that proximal upper limb involvement in individuals with Charcot-Marie-Tooth disease is a simple but significant predictor of respiratory muscle dysfunction.
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A field experiment was conducted with preschool children to test the effect of rewards on a familiar, spontaneous play activity, in conditions as close as possible to the children's natural school context, and to examine the role of familiarity of the person who administered rewards. In three experimental conditions, children were rewarded either by their own teacher or by an unknown adult for playing with toys at the school playground and stayed with either the teacher or the unknown adult in the remaining part of reward sessions. Spontaneous play was significantly reduced by the reward relative to baseline levels and recovered after a 3-wk. interval. However, no difference due to familiarity/unfamiliarity of reward agent could be found. Results, discussed in terms of an incentive contrast hypothesis, attest to the generality and external validity of the undermining effects of rewards.
In a work physiology field study, the work flow and the electrocardiogram were recorded throughout whole shifts for six male refuse (garbage) collection workers who transported and emptied 1.1 m3 refuse containers. The work rate (WR), indicated by the number of 1.1 m3 containers emptied per unit of time, and the work pulse rate (WPR) were determined in the data evaluation. The work pulse rate increases with the work rate. The functional relationship can be approximated by a linear regression function (WPR = 20.9 + 35.8.WR). The work pulse rate reaches such high values that it must be assumed that the work cannot be performed continuously throughout the whole working day. Consequently, regular breaks should be provided. When determining the necessary duration of the breaks, it was assumed that an equilibrium between fatigue and recovery should be maintained during the working day. The recovery breaks should be at least long enough for the heart rate to return to the resting level. The necessary duration of the breaks was determined on the basis of the present field study and the laboratory investigations described in the literature. A minimum duration of 10 min per working hour results from the calculations. The breaks should be taken regularly at about hourly intervals. A transportation-capacity model is provided for the planning of the deployment of refuse workers. It permits calculation of the number of 1.1 m3 containers a three-man crew, comprising the refuse collection truck driver and two loaders, can empty during one shift. Both the logistical and ergonomic transportation capacities can be determined using the model. The logistical transportation capacity (TCL) indicates the number of containers which can be emptied per shift by a crew when only criteria such as the optimal utilization of the working time are considered. The ergonomic transportation capacity (TCE) is understood as the number of containers which can be emptied per shift taking into consideration the workers' strain and the recovery breaks they require. TCE amounts to between about 140 and 160 containers per shift depending on the type of city district. TCL is higher by between 20 and 30 containers per shift. In order to meet the demand of protecting workers' health, the number of containers to be emptied per shift by a three-man crew should not exceed the ergonomic transportation capacity.
The problems and prospects in the use of case-control studies to assess the effects of improvements in environmental sanitation on diarrhoea morbidity are discussed on the basis of two field studies. It is concluded that an adequate design is available for assessing the effects of a single improvement on diarrhoeal disease. The estimates of effect appear to be valid and sufficiently precise. For addressing more complex questions of interactions, sample sizes would have to be increased substantially. The experience with two field studies suggests that there is hope that a simpler protocol may be feasible, in which only limited information is collected, in which few home visits are made, and in which analytical techniques are simple. Until more field studies have been conducted definitive conclusions cannot be reached on the applicability of such a simple, rapid and inexpensive approach.
In an internordic field study of the effect of the Ca dose (6, 9 and 12 g) on the therapeutic result in parturient paresis, considerably better results were recorded in Finland than in the other countries at all dose levels. In Finland a full effect was obtained with 6 g, while in all others 9 g Ca yielded a significantly better result than 6 g. Raising of the dose to 12 g produced no improvement. There was a significant difference in therapeutic results between the two Finnish breeds. A larger number of fatal cases was recorded among paretic cows with plasma Ca greater then 8.0 mg/100 ml.
Field studies in 160 flocks of broiler chickens in two areas in the Netherlands showed that Mycoplasma synoviae infection, the presence of which was detected by serological testing in 17.5 per cent, had only a slight adverse effect on the results of fattening. Mycoplasma synoviae as well as IB infections were found to be more common in flocks affected with colibacillosis and/or in which higher proportions of birds were condemned because of polyserositis. Infectious bursal disease, IB and CELO virus infections are very common particularly in the southern areas of the Netherlands, and have a significantly adverse effect on the results of fattening. The findings suggest that vaccination against IB and Gumboro disease often fails in flocks in areas showing a high incidence of infection.
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In the Upper Bavarian Field Study a total of 1536 persons (15 years and older) were interviewed by research psychiatrists. 8.1% of all respondents took a psychotropic drug during the 7 days prior to the interview. The consumption rate among women was about three times as high as that for men. The use of psychotropic drugs increased with age. No consistent pattern was found with respect to social class. According to psychiatric/physical health status the highest consumption rate (29.4%) was found among those suffering solely from psychiatric disorders. The simultaneous occurrence of both psychiatric and physical disorder did not increase the risk of drug taking (21.4%). Less than 5% of the healthy respondents and of those suffering solely from a physical disorder used psychotropic drugs. A large proportion (63.0%) of those with previous psychiatric in- and outpatient treatment received psychotropic medication, as well as those suffering from schizophrenia (66.7%), affective psychoses (52.6%) and anxiety disorders (50.0%). The higher consumption of psychotropic drugs among women could not be explained by higher psychiatric or physical morbidity or the fact that women consult primary care physicians more frequently than do men. Controlling for co-morbidity and annual consultation of family physicians, significant sex differences in the consumption of psychotropic drugs persist.
In the Upper Bavarian Field Study a representative community sample of 1,536 persons (from 15 years of age and upwards) was interviewed by research psychiatrists. Twenty-seven percent of the respondents reported taking regular and 26.2% occasional physical exercise. Physical inactivity as well as depression were significantly associated with the female gender, increasing age, low socioeconomic status and the presence of a somatic disorder. Using a logistic regression model, the relation between physical activity and depression was measured by the odds ratio with subjects reporting regular physical activity as the reference group. Cross-sectional analysis revealed that after controlling for potential confounder variables the odds ratio for depression was, at 3.15, significantly higher for the physically inactive compared to the regular exercisers. The odds ratio for the group practising occasionally (1.55) was also elevated but not statistically significant, 87.3% of the subjects who participated in the baseline study were reinterviewed five years later. In contrast to the cross-sectional findings, low physical activity at wave 1 was not a risk factor for developing depression at wave 2.
In the Upper Bavarian Field Study a total of 1,536 persons (15 yr of age and older) were interviewed by research psychiatrists. The prevalence of insomnia (last 7 days) identified with the aid of the Clinical Interview Schedule (CIS) was 28.5% (mild: 15.0%; moderate/severe: 13.5%). For both sexes sleep disorders increased with age. The female preponderance of insomnia was mainly associated with the middle and older age groups. In contrast to other psychiatric disorders, sleep disturbances were not associated with social class. Moderate/severe insomnia was strongly related to psychiatric diagnoses, the use of psychiatric in- and outpatient services and general hospitals. It also constituted a significant burden for the primary-care physicians, whereby the average annual consultation rate among mild (10.61) and moderate/severe insomniacs (12.87) was significantly higher compared to that for those without sleep disorders (5.25). A total of 33.7% of the insomniacs were treated with hypnotic and/or other psychotropic drugs during the week prior to the interview, whereby the drug consumption among moderate/severe insomniacs (48.5%) was significantly higher than that of mild insomniacs (20.4%).
Four field studies assessing the caries preventive value of partial substitution of sucrose by xylitol or a mixture of xylitol and sorbitol were recently conducted. The trials (in Thailand, Hungary and two in French Polynesia) had certain common features, i.e. protocols approved by the WHO; low intake of polyol(s); non-randomized young study populations, differing baseline caries prevalences between groups; and planned duration of 32-36 months. Analysis of the findings was facilitated through the use of rates to measure caries increments expressed as DMF teeth and surface counts in relation to the numbers of teeth at risk. Irrespective of baseline differences, all studies revealed, in comparison to known methods, that partial substitution of sucrose was associated with a preventive effect.
In an operational Schistosoma mansoni field-study in an area about 20 km 2 (population approximately 8000), transmission detection by simple snail sampling was compared with cercariometry. Between 1985 and 1987, 62 field sites were sampled at fortnightly intervals. Of a total of 2758 field observations, 89.8% gave full snail data; 64.4% full cercarial data; and 61.7% complete data for both methods. The complete data sets showed significant but not strong correlations between Biomphalaria pfeifferi (total and infected with S. mansoni or other trematodes) and cercarial (S. mansoni and non-human) recoveries. Non-human (but not S. mansoni) cercarial recovery decreased with deteriorating cercariometry filter quality. Both snail and cercarial recoveries diminished significantly with increasing water flows at the time of collection. Many samples yielded infected snails or cercariae, but not both, and neither method detected significantly more transmission sites. The method of choice for detecting transmission in a large-scale field-study depends on logistical and financial considerations. Relatively simple snail sampling allows quick, cheap and widespread data collection adequate for most purposes but more complicated cercariometry is still valuable for specific, small-scale studies.