Impact of hand forces and start/stop frequency on physiological responses to three forms of pushing and pulling: a South African perspective

There has been limited attention given to the physiological demands of pushing and pulling, especially in industrially developing countries such as South Africa. Two key factors affecting the physiological demands of these tasks are the hand forces exerted and the start/stop frequency. The purpose of the current study was therefore to investigate the physiological responses to pushing and pulling at various loads and start/stop frequencies. 36 male subjects participated in the study and were required to complete a total of 18 conditions (three techniques: pushing, two- and one-handed pulling; three loads: 200, 350 and 500 kg; and two frequencies: 2 and 4 stops per minute). During each condition the heart rate, oxygen uptake and energy expenditure were measured. Pushing was found to elicit significantly lower responses for all three dependent variables than either form of pulling. The start/stop frequency was also found to have a significant impact on subject responses. The findings of this study indicate that the technique adopted to maneuver loads is critical in determining the physical demands placed on the human operator. Furthermore increasing the frequency of start/stops plays an important role, thus the forces exerted during these two phases are important from a physiological perspective.     

Comparison between static maximal force and handbrake pulling force

The measurement of maximum pulling force is important not only for specifying force limit of industrial workers but also for designing controls requiring high force. This paper presents a comparison between maximal static handbrake pulling force (FST) and force exerted during normal handbrake pulling task (FDY). These forces were measured for different handle locations and subject characteristics. Participants were asked to pull a handbrake on an adjustable car mock-up as they would do when parking their own car, then to exert a force as high as possible on the pulled handbrake. Hand pulling forces were measured using a six-axes force sensor. 5 fixed handbrake positions were tested as well as a neutral handbrake position defined by the subject. FST and FDY were significantly correlated. Both were found to be dependent on handbrake position, age and gender. As expected, women and older subjects exerted lower forces. FST was significantly higher than FDY. The ratio FmR (FDY divided by FST) was also analyzed. Women showed higher FmR than men meaning that the task required a higher amount of muscle capability for women. FmR was also influenced by handbrake location. These data will be useful for handbrake design.     

Cut-points to prevent low back injury due to force exertion at work

Force exertion is related to low back injuries (LBI). This paper critically reviews the literature concerning cut-points for back force exertion, presents available guidelines in a concise manner, and identifies areas that need further research. The studies reviewed were grouped according to the criteria used to set the cut-point values. Most often cut-points differ than concur. The approach considering physiological, psychophysical, epidemiological, and biomechanical aspects of back force exertion meets the most known criteria and presents the lowest common denominator of instantaneous load for lifting tasks. Further experimental and epidemiological studies in peak load and cumulative exposure are necessary. Compound indices should also be developed for pushing, pulling, and carrying. Future indices should consider electromyographically determined fatigue, differential viscoelastic properties of tissues, aging, and the cross sectional area of back muscles. We hope that this paper contributes to a more systematic appraisal of back force exertion at work.     

A case study of smoke detector assembly work method intervention and evaluation

The study aimed to evaluate a work method intervention in a smoke detector assembly line. High hand gripping forces and extreme wrist postures were found in the smoke detector assembly line at UTC Fire & Security Company in Maine. A fixture was introduced to replace the old assembly method. Electromyography (EMG) and electrogoniometry were used to measure the workers' hand gripping force and wrist motions with both the old and new assembly methods. Results show both hand gripping forces and wrist postures improved significantly with the new method.     

Perseveration in Tool Use: A Window for Understanding the Dynamics of the Action‐Selection Process

Two experiments investigated how 3‐year‐old children select a tool to perform a manual task, with a focus on their perseverative parameter choices for the various relationships involved in handling a tool: the actor‐to‐tool relation and the tool‐to‐target relation (topology). The first study concerned the parameter value for the tool‐to‐target relation by asking how children use a cane for either pushing an object further away (exclosure; outside the hook) or pulling an object nearby (enclosure; inside the hook). The second study concerned the parameter value for the hand‐to‐tool relation by assessing the hand used for grasping a spoon to feed a puppet. Results from both studies showed that on the first trial, choices were driven by task information. However, when the task switched from pulling to pushing or from left hand to right hand, or vice versa, children persevered with the choice they made during the 4 previous trials. Results are discussed in terms of the dynamical field modeling work of Esther Thelen and her colleagues. Our findings underscore Thelen's hypotheses that: (a) the action‐selection process is a dynamic affair, affected by multiple influences at different time scales and its own intrinsic dynamics; and (b) that perseverative behavior is a general phenomenon that is neither indicative for a specific period in the development, nor for a particular task. Similarly, we argue that the presence (or absence) of causal understanding emerges from the action‐selection process, rather than determining this process.     

Biomechanical analysis of loading/unloading a ladder on a truck

Loading/unloading a ladder on vehicles are frequent tasks and involve overhead handling that may expose workers to risk factors of shoulder musculoskeletal disorders. The objective of the present study was to evaluate posture, forces required and perceived exertion when loading and unloading the ladder on a utility truck. Thirteen male overhead line workers from an electric utility in Brazil participated in this study. Shoulder elevation angle was measured using inclinometers. The required force to load/unload the ladder was measured by dynamometer. Subjective assessment of the perceived exertion was recorded to compare the exertion reported during the test conditions to the field conditions. The task of loading/unloading the ladder presented risks of shoulder musculoskeletal disorders (MSDs) to workers because it requires high levels of force (approximately 60% of the maximal force) combined with overhead posture of the shoulders (more than 100° from the neutral posture). Age and height presented to interfere in biomechanical risks presented in load/unload task. There was no significant difference between the subjective exertion during the test conditions and handling the ladder in the field. Ergonomic intervention is recommended to reduce these risks for shoulder MSDs.     

GENDER-COHORT SUCCESSION AND RETIREMENT AMONG OLDER MEN AND WOMEN, 1951 TO 1984

Long-term trends in occupational change and retirement policy have influenced the relative labor force participation and retirement patterns of subgroups of the older population. Structural changes in the economy have had a large impact on older men and women, pushing the former out of the labor force while pulling the latter in. Meanwhile, the expansion of pension programs for the aged has generally increased the early retirement of men under age 65. Time-series analyses of these trends between 1951 and 1984 point to the specific influences of these factors on gender-cohorts.     

An analysis of the basic population structure of Shanghai Municipality

This paper analyzes the changes in Shanghai's population structure over the last 30 years in the 4 aspects of age structure, sex composition, urban and rural composition, and labor and employment structure. In 1953 those of the 0 to 6 age group accounted for 21.2% of the total population; in 1957 the group represented a proportion of 24.6%. Since the 1960s, especially after the 1970s, the family planning program gradually took effect, and the birthrate of the entire municipality fell drastically. The number of school-age children in 1979 was 1 1/2 times more than the same age group in 1953; there should be no worry that population control may result in a shortage of manpower to meet the needs of the work force and the armed forces either toward the end of this century or at the beginning of the next. The economy in China is underdeveloped, production and technology remain at a low level, average wages for employees are low, and for a long time the low living standard of the people has shown little sign of improvement. The problem is mainly manifest in the following areas: 1) distribution of the work force in heavy and light industries is not sufficiently rational, 2) the distribution of the work force between captial construction and transport and communications on the 1 hand and the national economy on the other is out of proportion, 3) the distribution of the work force between commerce, service trades, and public utilities on the 1 hand and the national economy on the other is disproportionated, and 4) the distribution of the work force between undertakings of culture, education, scientific research, health, and medical care on the 1 hand and economic construction on the other is improper. How to control population growth and adjust parts of the population structure to suit the national economic development poses a problem that calls for further in-depth study and analysis to resolve it step by step.     

The Gezi Park movement: a Turkish experience of the twenty-first-century collective movements

Based on the results of a field study conducted during the summer following the wave of mobilizations in Gezi, this article analyzes the development and the social, cultural, and political meanings of this collective movement, which began in Turkey at the end of May 2013 and has been evolving during the summer. The first part of the article addresses the subject of these mobilizations that are opposed to the planning policy, implemented by the government in a process of neo-liberal economic development. The second part discusses the subjective engagement of the protesters and the meaning they give it, by considering alternatives not only to this policy but to the influence exerted on the individual and social life by the technostructures of the systemic forces. The third part analyzes, on the one hand, the methods of direct and online communication for organizing protests and, on the other, the creation of new living constructs, where protesters experiment with the alternatives to the dominations they contest. It is through protest, but also creative and performative actions, that the individuals try to become subjects of their own lives, against these dominations in which the Turkish dimension is part of a global systemic context.     

The Development of Anticipatory Postural Adjustments in Infancy

Efficient voluntary action requires postural adjustments that compensate for potential balance disturbances before they occur. These anticipatory postural adjustments have been widely investigated in adults, but relatively little is known about their development, especially during infancy. This study examined the early development of anticipatory postural activity in support of pulling action while standing. A total of 34 infants between 10 and 17 months were tested. The task required infants to open a cabinet drawer to retrieve toys while a force resisting the pulling action was applied to the drawer. The experiment included between 9 and 13 pulling trials. The force resisting the pull was doubled after the first 4 initial trials and returned again to its original value after another 4 trials. Electromyographic activity from the gastrocnemius and biceps brachii muscles was recorded. The proportion of pulls involving anticipatory activity in the gastrocnemius muscles progressively increased between 10 and 17 months. In addition, infants with considerable experience in opening drawers learned to recruit greater strength of their anticipatory postural adjustments for heavier pulls. Implications for the role of motoric experience in anticipatory postural activity are discussed.     

How did the financial crisis affect the transnationality of the global financial elite? One step forward and one step back

Over the last few decades, transnational elite formation progressed hand in hand with a deterioration in national business elites. Most studies regard this process as progressive and linear. However, we argue that transnational elite formation is subject to a variety of opposing forces, and the assumed progression is not a given fact. As an intriguing case, we analyse the financial business elite with a focus on the financial crisis of 2008. This international event had substantial ramifications, including a possible external shock to transnational elite formation. To study the consequences of the crisis, we collected the board composition data of the 48 largest transnational financial companies for the period 2006–11. Changes in board composition show opposing effects. For example, transnationality increased during the crisis, but reversals appeared when national governments intervened.     

Patterns of correlation between vehicle occupant seat pressure and anthropometry

Seat pressure is known as a major factor of seat comfort in vehicles. In passenger vehicles, there is lacking research into the seat comfort of rear seat occupants. As accurate seat pressure measurement requires significant effort, simulation of seat pressure is evolving as a preferred method. However, analytic methods are based on complex finite element modeling and therefore are time consuming and involve high investment. Based on accurate anthropometric measurements of 64 male subjects and outboard rear seat pressure measurements in three different passenger vehicles, this study investigates if a set of parameters derived from seat pressure mapping are sensitive enough to differentiate between different seats and whether they correlate with anthropometry in linear models. In addition to the pressure map analysis, H-Points were measured with a coordinate measurement system based on palpated body landmarks and the range of H-Point locations in the three seats is provided. It was found that for the cushion, cushion contact area and cushion front area/force could be modeled by subject anthropometry, while only seatback contact area could be modeled based on anthropometry for all three vehicles. Major differences were found between the vehicles for other parameters.     

Die Wahl der Soziologie als Studienfach

Sociology is one of the fields of study with the highest dropout rates. How can this be explained? Using data on students of sociology at the University of Bamberg, the authors examine three aspects of the decision making process for this subject: (1) the information gathering strategy of prospective studens, (2) the timing aspect of the decision process, and (3) the consideration of labour market issues. Based on rational choice theory, it is shown that on the one hand the problems erst upon the subject itself, since sociology is not enough professionalized and still not clear-cut enough towards specific occupational fields. On the other hand, the information gathering process of prospective students is often insufficient and there is too little consideration of the labour market aspects of the subject. Finally, the decision is often hastily made, which is also caused by the fact that for many students of sociology this subjectwas not their “first choice”.     

Using walker during walking: a pilot study for health elder

Walker operation completely relies on the walker handle, however most marketed walkers possess two horizontal handles. Several researchers have suggested that horizontal handles might lead to wrist injury. Therefore, the purpose of this study is to assess the relevant design aspects of walker for elderly people. 28 elders participated in this study; when the experiment was started, subject walked on the tile for 3 meter distance twice by using walker. Data for analysis were selected at the corresponding wrist deviation and vertical force. The results showed that during walker using, the mean wrist deviation was greater than zero. The largest vertical force is significantly larger than the smallest one, and different wrist deviation occurred at three phases, the largest wrist deviation while raising walker is larger than the smallest one, however, no significant different was found between the largest and smallest wrist deviation while pressing walker. No significant correlation occurred between weight and wrist deviation. The correlation between weight and vertical force was significantly positive. With wrist deviation walker use may cause injury to upper-limb, however wrists remain in a neutral position during hand movement to prevent damage. The findings of this study should improve the design of walker handles to reduce the wrist deviations of users.     

Impact of lightweight and conventional jackhammers on the operator

Jackhammer manufacturers have recently developed lightweight (45-60 lbs) jackhammers intended to reduce the required lifting and pushing forces during operation. However, the vibration characteristics of the lightweight jackhammers and their effect on muscle activity are currently unknown. The objective of this study was to compare the measured vibration and muscle activity between: (i) conventional (90 lb) and light weight (60 lb) jackhammers, (ii) different pavement type/thickness combinations, and (iii) pneumatic and hydraulic jackhammers. Five jackhammers were tested on 4 and 6 inch thick asphalt and concrete pavements by four experienced operators. Analysis of the results revealed that both weight classes averaged 9.7 m/s(2) at the 20 Hz weighted 1/3 octave band frequency, and the TLV of daily exposure for either weight class of jackhammer was less than 1.5 hours/per day. There was an approximately 33% difference in vibration measured on the hand of the operators due to pavement thickness, 30% due pavement type, and no difference due to power source. Conventional jackhammers overall produced higher muscle activity than lightweight jackhammers. Although selection of the correct jackhammer for the job involves many factors including pavement type and thickness, the results of this research can be used to assist in selecting the appropriate jackhammer.     

Sexual Pleasure and Wellbeing

ABSTRACT

Pleasure may be the key to the successful working of the reproductive systems of humans. However, for all the enjoyment sexual relationships can provide, there are countervailing forces of guilt and disappointment at work on the individual psyche. Religious and social norms enforce limits on sexual expressiveness. These controls are defended as means to protect individuals and their partners from unhappiness due to infidelity. The contrasting balance of potential pleasure on the one hand and deeply felt self-controls on the other gives rise to many problems of sexual health. Couples with discordant expectations about sexual pleasures can find their relationships crumbling. Deeply planted understandings about inappropriate behavior can cause individuals to feel shame or fear when faced with choices about their sexuality and particularly their desires. People unable to achieve desired pleasures due to physical handicaps experience a loss of wellbeing that can be extremely distressing. Simultaneously society struggles to control the individual expression of harmful sexual behavior such as child molestation while protecting the rights of individuals to enjoy personal satisfaction. The recognition and promotion of sexual pleasure as an integral part of wellbeing is one of the most challenging elements on the sexual health agenda. Progress in this area will require extraordinary efforts by professional groups and political leaders to forge a forthright understanding of the meaning of pleasure in people's lives, and the priority of promoting healthy sexuality as a part of a global health agenda.     

Examining Interactions of Marriage and Self-Efficacy Beliefs of Individuals with Rheumatoid Arthritis: A Conceptual Framework

The systemic and chronic nature of rheumatoid arthritis (RA) impacts functional and emotional health of the individuals including marital, family, and work responsibilities. Due to the costs and side effects of drugs, proponents of arthritis management advocate for examining psychosocial factors that improve the disease management of RA. In this paper, we propose that marital quality is associated with perceived self-efficacy among individuals with RA. We further hypothesize that this relationship is moderated by functional disability, pain levels, and the demographics of the individual. Based on the literature review we draw conclusions about the potential implications of marital quality on perceived self-efficacy. We also discuss practice and research implications of this association, including the development of educational initiatives.     

Dialect contact and distinctiveness: The social meaning of language variation in an island community

In this paper, we analyse linguistic variables which are well‐established in British English, the vowels in the trap and bath lexical sets. We demonstrate that the social meanings of these variables are both historically substantiated and locally‐elaborated. Our data is taken from the speech of individuals living on the Isles of Scilly, a group of islands off the south‐west coast of England. Our initial analysis shows that trap and bath variants found on the islands are linked to contact with Standard English English, on the one hand, and the nearest neighbouring variety of Cornish English, on the other. The general distribution of variants is shown to reflect educational differences amongst our speakers. However, two case studies show speakers using forms atypical of their education type in order to position themselves in interactionally‐dynamic ways. This reveals how speakers exploit the multidimensional meanings of linguistic variants to reflect and construct local practices and alignments.     

The Networked Household

The authors argue that individuals, rather than family solidarities, have become the primary unit of household connectivity. Many households do not operate as traditional densely knit groups but as more sparsely knit social networks where individuals juggle their somewhat separate agendas and schedules. At a time when many people enact multiple, individual roles at home, in the community and at work, the authors ask: how do adult household members communicate with each other? How do adult household members use information and communication technologies (ICTs) to organize, communicate and coordinate their leisure and social behavior both inside and outside the home? Interviews and surveys conducted in 2004-2005 in the Toronto, Canada area of East York show that households remain connected - but as networks rather than solidary groups. The authors describe how networked individuals bridge their relationships and connect with each other inside and outside the home. ICTs have afforded household members the ability to go about on their separate ways while staying more connected - by mobile phone, email and IM - as well as by traditional landlines. In such ways, rather than pulling families apart, ICTs often facilitate communication, kinship and functional integration.