Genitalic autogrooming in the male cricket, Gryllus bimaculatus DeGeer.

The genitalia of the male cricket, Gryllus bimaculatus, is automatically maintained. It is carried out by spontaneous undulation of the scaled membrane consisting of the genital chamber floor. To understand the mechanism of that movement, part of the membrane was cut out and examined in vitro with biogenic amines, and the spike activity of neurons innervating muscle fibers of the membrane was analyzed. The esults indicated that the fragment of the membrane, which showed spontaneous twitching in saline, increased its frequency at 5-HT application. In contrast, mianserin (5-HT antagonist) decreased its occurence. Immunocytochemical study indicated that massive 5-HT-positive branchibgs of one main axon nnervated muscle fibers of the genital membrane. Centrally, one of the motoneurons backfilled with ucifer Yellow through the cut end of the nerve 9v of the terminal abdominal ganglion was determined 5-HT positive. These results suggested that the undulatory movement of the genital membrane for genitalic autogrooming is mediated by 5-HT.

Risk of serious adverse events in hypertensive patients receiving isradipine: a meta-analysis.

A meta-analysis was performed to compare the risk of serious adverse events associated with the use of all formulations of isradipine, when used as monotherapy in hypertension, to active drug or placebo controls. Eligible studies totalled 65 published and unpublished randomised controlled trials involving 9903 subjects and 10,675 treatment exposures: 4492 to isradipine, 1473 to isradipine sustained release, 2768 to other active drugs, and 1942 to placebo. Mortality, cardiovascular outcomes, other serious incident illnesses, such as cancer, and withdrawals were sought. Seventy-five per cent of the isradipine exposures were to standard-release formulations and 25% were to sustained-release formulations. Overall, isradipine therapy shows no difference in risk of major adverse events or withdrawals compared to other active controls or placebo (odds ratios [OR] 0.9; 95% CI 0.7-1.46 and 0.5; 95% CI 0.2-1.3). These major adverse events included angina, fatal and non-fatal myocardial infarction, stroke and overall mortality. Isradipine sustained release could be compared only to placebo, based on available data, and shows a lower risk of withdrawals (OR 0.5; 95% CI 0.3-0.9), and a similar trend was observed for major adverse events, (OR 0.8; 95% CI 0.3-2.5). Published and unpublished randomised controlled trials were analysed in separate meta-analyses and later combined when this sensitivity analysis of risk showed no differences between the groups. In conclusion, we find no evidence for increased risk of serious adverse events in patients receiving isradipine as monotherapy for hypertension.

Power spectral analysis of heart rate variability in Type As during solo and competitive mental arithmetic task.

It has been reported that there are differences in autonomic balance between Type As and Type Bs. This study evaluated the sympathovagal interaction in Type A (N = 10) and Type B (N = 10) male students during mental arithmetic task in a solo and a competitive condition by the spectral component analysis of heart rate variability (HRV). The low-frequency (LF) component to high-frequency (HF) component ratio was significantly greater in Type As than in Type Bs, though no significant differences were found in task performance, heart rate change, and blood pressure between the two subject groups in both conditions. The present findings indicate that there was a significant difference in sympathovagal balance between Type As and Type Bs, and that Type As showed dominant sympathetic activity. The results suggest that the power spectral analysis of HRV, which is convenient and non-invasive, has enough sensitivity to discriminate differences in autonomic balance between Type A subjects and Type B subjects, not only during the solo and competitive task period but also during the resting period.

Power spectral analysis of heart rate variability in type A females during a psychomotor task.

This study investigated changes in autonomic nervous activities due to psychological stress in Type A females. Eight Type A and eight Type B females performed a psychomotor task for 30 minutes. Power spectral analysis of heart rate variability (HRV) was used to examine the autonomic nervous activities. Results showed the low frequency (LF) component and LF/HF ratio in Type A females increased after the onset of the task. There were no significant differences in task performance between Type A and Type B females. The subjective mental workload increased gradually in Type A females during the tasks, whereas in Type B females this parameter did not change in a consistent manner. The results suggest that the sympathetic nervous system in Type A females was more stimulated by the task and Type A females felt a greater subjective mental workload than did Type B females.

Dynamic analysis of wrist circumduction: a new application of the biaxial flexible electrogoniometer.

A new technique for quantifying wrist circumduction was developed and evaluated using a biaxial flexible electrogoniometer. The reliability and validity of the electrogoniometer for the measurement of wrist motion were first tested, and then the device was applied clinically. The reliability tests demonstrated sufficient accuracy of the device. Also, validity of the measurement was recognized because the tests simulating wrist circumduction and cineradiography revealed that it could accurately detect the angle between the long axis of the forearm and the third metacarpal bone. Lissajous's figure was made from the two channel signals of the electrogoniometer, and the Range of Motion index for wrist circumduction was newly defined from this figure. This index represents the dynamic range of motion of wrist circumduction. Ten healthy men (ages 19-31 years) and three patients with wrist disorders were studied. In the patients, Lissajous's figures and Range of Motion indexes were markedly different from the healthy. In addition to this study, preliminary data on the 'velocity-angle loci' of healthy men during wrist circumduction were obtained for further detailed analysis.

Differences in heart rate variability between young and elderly normal men during graded head up tilt.

An autoregressive spectral analysis of heart rate variability (HRV) was used to analyze the differences in autonomic functions during graded head up tilt (HUT) between young and elderly men. After recording at the 0 degree position, the table was rotated to an upright position. The incline of the table was increased progressively to 15 degrees, 30 degrees and 60 degrees. The data obtained from seven young subjects (mean age of 20.0 years) and nine elderly subjects (mean age of 63.3 years) were analyzed. The high frequency components expressed by normalized units (HFnu) were used as the parasympathetic indicators, and HFnu decreased with tilt angle in both age groups. These results suggested that parasympathetic withdrawal have an important role in adaptation to an upright posture in both age groups. However, mean HF amplitude at the 0 degree position in elderly men was not significantly different from that of young men at 60 degrees tilt. A significant interaction effect (age group x tilt angle) was found for mean HF amplitude. The increase of the low frequency components expressed by normalized units (LFnu) and the LF-to-HF ratio in elderly subjects from 0 degree to 15 degrees seemed to be larger than that in young subjects. Sympathetic activities may be sensitive to lower levels of orthostatic stress in the elderly, and the elderly workers are easily affected by a change in workload. Therefore, keeping the workload lower and constant may be recommended to avoid excessive sympathetic activation among the elderly.

The present state of ergonomics in Japan.

The purpose of this study was to investigate the state of ergonomics teaching in Japan and the research interests of those concerned with this teaching. The name "Ergonomics" became well known between 1965 and 1969. Most Japanese researchers in ergonomics came from an engineering background and most teaching and research were carried out at Departments of Industrial Management. The next largest group of researchers came from Departments of Psychology, but in their teaching or research they were not necessarily carrying out research in ergonomics in those departments even though many of them were conducting ergonomics projects before 1959. University courses in ergonomics were first launched in 1953; 1967 was a turning point, and they have rapidly become more popular since then. However, the courses of ergonomics are optional at the majority of universities, taught over a period of only one term at half of the universities and one year at the other half. Furthermore, there were very few experiments which were separate from the courses of the lectures. Most of the work of Japanese researchers is in the areas of "Man as a system component" and "Methods, techniques and equipment in ergonomics". These are also the main subjects of undergraduate and graduate theses and experiments.

[Workers' subjective feeling of fatigue and attitudes towards work--effects of age and job difference].

The present study is an attempt to assess attitudes towards work and subjective feelings of fatigue. To discover the relationships between these factors, a field study was conducted in a large-sized electric company. The subjects were 1376 male workers. The results of the 30 questions concerning subjective feelings of fatigue published by the Japan Association of Industrial Health showed that the complaint rate of fatigue in younger workers (18-29 yrs.) was higher than that of older workers (30-66 yrs.). In the middle aged (44-49 yrs.), feelings of fatigue in the administrative group were lower than that of the non-administrative group. Finally, workers who had a high complaint rate of fatigue were less favourably disposed towards their work and felt an increase in boredom, loneliness and monotony. Overall, the results indicated that the difference of labor mode exerts an influence on the onset of self-reported stress.

Effects of listening to music with headphones on hearing--especially under noisy conditions.

The purpose of this experiment was to clarify the effects of exposure to music using headphones under noisy conditions on hearing. The most comfortable loudness (MCL) for three kinds of music (Rock, Popular, Japanese songs) decided by two normal hearing subjects was measured under 6 noisy conditions (Train, Subway, Tram, Bus, Underground, Street) in a soundproof room. In the same manner, the MCL of favorite tunes of five subjects were measured. Temporary threshold shift 2 min after exposure (TTS2) to music for 30 min at the highest MCL was obtained. Furthermore, the characteristics such as spectral structures in one-third octave band or level fluctuations (coefficient of variation) were obtained for noise and music and compared. Statistical analysis revealed that MCL in Street was significantly higher than under other conditions and there was no significant differences in MCL among the various types of music. However, the highest MCL was found for Rock. About 20 dB of TTS was observed in one ear and the hazardous of headphones use in noisy conditions was suggested.

[Instabilities in tactile, visual and auditory sense--application of stochastic catastrophe model].

As a fundamental study on management of the working environment, instabilities in tactile, visual and auditory sense are discussed. The effects of localized vibration on the ability to discriminate the surface roughness are analyzed by means of the stochastic cusp catastrophe model. Also, bistable perception of the ambiguous man/girl figure is modelled in the same way. Furthermore, the instable phenomenon of a pure tone when heard under the masking noise is pointed out and analyzed by the catastrophe model.

[Anxiety symptoms and their association with work environment and other factors].

Anxiety symptoms and their association with work, work environment, family environment and physical health were studied by mailed questionnaire in 1379 male and 1427 female employees working in a Tokyo-based company and a Kyushu branch of a government-subsidized corporation. Subjective anxiety symptoms were found to increase with poor physical health, poor marital relationship and physical work overload and when the employee felt his superior(s) difficult to deal with. They were little influenced by whether the employee felt his work environment dangerous or not.

[Health check on radiation workers in the nuclear energy industry using Todai Health Index].

In the nuclear energy industry, the plants are located far from urban areas and the working environments are generally separate from each other for radiation protection purposes. The health investigation on radiation workers in the nuclear energy industry was carried out using the Todai Health Index questionnaire in 1982, 1983 and 1984. As a control study non-radiation workers on the other several working fields were investigated in the same manner. The results showed that the status of radiation workers in the nuclear energy industry is similar to that of the workers in the other working fields and the THI questionnaire is useful to know health and working status of a group of workers.

Auto-spermatophore extrusion reveals that the reproductive timer functions in the separated terminal abdominal ganglion in the male cricket.

Auto-spermatophore extrusion is a kind of spermatophore extrusion without genital coupling in the male cricket. It rarely occurred in intact males paired with a female, while it frequently occurred in all the males with the connectives cut under restraint and dissection. The time interval (SPaSE) between spermatophore preparation and auto-spermatophore extrusion was found to be comparable to that (RS2) of the time-fixed sexually refractory stage measured by the calling song. According to extracellular spike recording, the dorsal pouch motoneuron (mDP), which singly innervates the dorsal pouch muscles and is responsible for spermatophore extrusion, showed a burst discharge in association with auto-spermatophore extrusion with an interval similar to RS2 in males with the connectives transected between the 6th abdominal ganglion and the terminal abdominal ganglion (TAG) after spermatophore preparation. These results strengthened our previous conclusion that the reproductive timer for RS2 is located in the TAG, and demonstrated that it functions normally even in the TAG separated from the rest of the central nervous system.

Genitalic autogrooming: a self-filling trash collection system in crickets.

Insects groom almost all parts of the body surface with their legs and mouth parts. However, some body regions are difficult to reach and keep clean. One is the genital chamber located in the last abdominal segment in males which houses the phallic complex for copulation and production of the spermatophore. In the male cricket, foreign substances can enter the genital chamber when it is opened during copulation and spermatophore formation. Moreover, the dorsal pouch and ventral lobes of the phallic complex, which mould the attachment plate, tube, and ampulla of the spermatophore, are inevitably soiled as a result of spermatophore production. We found a unique cleaning system in which foreign substances accumulated during copulation and spermatophore debris left in the dorsal pouch after copulation are quickly removed and collected in special pockets in the genital chamber. This trash is collected by undulation of the genital chamber's membranous floor which is entirely covered by small scales ( approximately 10 microm) similar to those in the ovipositor of female crickets. This self-filling trash collecting system may be used in some other insects which produce the spermatophore in a similar manner to that of crickets.

Ergonomics strategies and actions for achieving productive use of an ageing work-force.

In this report, a basic ERGOMA (Ergonomics in Industrial Management) strategy is proposed as a policy for corporate production and employment in countries where ageing populations and reduced birth rates are imminent, and a strategy related to this is proposed. Specifically, as a strategy at the company level, the results of survey studies aimed at the development of methods for determining job capacity, to enable effective use of the labour of ageing workers, were summarized. A number of the insights gained here are steps in the development of a foundational methodology for practical use, and in actual practice a number of these insights must be subjected to measurements. However, the theory and newly developed methodology described here are thought to represent significant changes from the approaches to job capacity diagnosis and assessment published in the past and from the stance towards utilization of an ageing work-force. The author is confident that this represents new progress in one of the ergonomics approach to dealing with the working environment of ageing workers and an ageing work-force in general.

How to benefit from ergonomic interventions through participation by workers, managers and the company: an example of a small- to medium-sized factory with no ergonomic knowledge.

Many of the managers, and supervisors in small- and medium-sized businesses are technicians. These are workers with many years of experience in one specialized technical area. They know, in their minds, what should be improved, and how, in order to make the work easier to do. However, their knowledge of work improvement techniques, and how to think together with the workers, and further how to best lead their troops, is nil. This report focuses on managers and supervisors who had never even heard the word "ergonomics," and touches on cases of successful implementation of ergonomic work improvements. The subject work-places are part of an automobile parts manufacturing plant operating under a typical production system of small amounts of many product types: cutting process machinery workshop, press workshop and packing and distribution workshop. At the stage when they became aware of ergonomics, the key words for improvement which they mentioned were "manual lifting" and "working posture." As a result of various observations, analysis techniques and meetings, they introduced a push car with lifters as support equipment. However, the most significant result was that they were able to convince the company's owner of its contribution to productivity improvement, using objective data. Also, with regard to the push car manufacturer, they designed the specifications for the push car themselves and participated in its production. Of course, they were also praised by the workers for achieving a work method involving no strain or waste.

Strategy and actions for achieving productive aging in Japan.

The objective of this study was to develop basic strategies for determining the ideal form of corporate management that meets the needs of an aging work force, specifically with the intent to develop a method of calculating functional age, one of the determining factors of such strategies. A literature search was made of annual reports of research conducted jointly by the Association of Employment for Senior Citizens and Japanese corporations. We tested the physical, physiological, and psychomotor functions of 271 male workers ranging in age from 20 to 59, and we used the results to examine the means of creating a formula to calculate functional age. Many of the measures adopted by Japanese corporations to deal with aging involve job redesign. This category accounts for 58.5% of such measures in all research fields. Night vision, standing trunk flexion, timed vital capacity, systolic blood pressure, and jumping reaction time each have an important influence on functional age calculation.

Reproductive behaviour in the male cricket Gryllus bimaculatus DeGeer. I. Structure and function of the genitalia.

We have investigated the morphology and physiology of the genitalia of the male cricket to establish a basis for neuroethological study of its reproductive behaviour. First, the structure of the phallic complex, including the dorsal pouch, guiding rod, epiphallus, ventral lobes and median pouch, are described, as are the muscles, cuticle, membranes and biomechanics of copulation. The innervation and sensory receptors have also been examined. Second, the functional role of the muscle in each genital organ has been determined by direct observation of muscle contraction during spontaneous or evoked movements and by analysis of the changes in movements after the ablation of the muscle. Third, for the flexible membranous organs, the ventral lobes and median pouch, the passages for haemolymph and their dynamic properties have been examined using petroleum jelly. Fourth, the sequence of coordinated motor actions performed by the internal and external genital organs, which were induced in both restrained and dissected males using newly developed techniques, has been analyzed during tethered copulation and spermatophore formation. As a result, the mechanisms of copulation and spermatophore formation are now more fully understood.

Reproductive behaviour in the male cricket Gryllus bimaculatus DeGeer. II. Neural control of the genitalia.

To understand the neural mechanisms of reproductive behaviour in the male cricket, we identified motor neurones innervating the muscles in each genital organ by backfilling with cobalt/nickel and recording their extracellular spike activity from nerve bundles of the terminal abdominal ganglion during tethered copulation and spermatophore formation. During tethered copulation, at least two motor neurones innervating two ipsilateral muscles were activated during projection of the guiding rod of the phallic dorsal pouch. Only one motor neurone, innervating four ipsilateral muscles of the dorsal pouch, was responsible for spermatophore extrusion by deforming the dorsal pouch. For spermatophore transfer, three motor neurones, singly innervating three epiphallus muscles, played a major role in opening passages for haemolymph to enter the ventral lobes and median pouch by bending the epiphallus. Two ventral lobe and 3-5 median pouch motor neurones seemed to play a role in expanding or folding the two membranous structures by relaxing or contracting their muscle fibres. After spermatophore transfer, most of the genital motor neurones exhibited a rhythmic burst of action potentials causing movement of the phallic complex coupled with strong abdominal contractions. For spermatophore formation, the genital motor neurones began to accelerate their rhythmic bursts approximately 30 s prior to subgenital plate opening and then changed their activity to tonic bursting or silence. The results have allowed us to describe the timing of the onset and termination of genital muscle contraction more precisely than before, to examine the neural mechanisms of copulatory motor control and to speculate on the neural organization of the reproductive centre for spermatophore extrusion and protrusion.

Effects of armrests on workload with ten-key operation.

The constrained posture used for work using a visual display terminal (VDT), such as data entry, can produce static muscular fatigue. Based on the application of ergonomic principles, we conducted an experiment using a prototype VDT chair designed with an armrest adjustable to heights from 22 to 28 cm. The experiment--conducted to assess the static muscular strain based on varying heights of the armrest and distance from the keyboard--was performed with male subjects. The subjects were asked to input five-figure numbers using the 10 keys arranged on the right side. Using a surface electromyogram, we measured the strain imposed on the arm and the shoulder. This was followed up with a performance, weight-loading onto the armrests and a questionnaire. Results show that use of armrests is effective for the alleviation of muscles in one-handed keyboard operation where operators work on a desk whose height is unadjustable according to their body height or where operators are unable to rest their wrist on the desk. A chair with height-adjustable armrests is considered desirable when used by several people.