Data entry on a computer terminal: repetitive work strains on the oculomotor and central nervous systems

Continuous telemetric recordings including E.K.G., E.O.G., and E.E.G. were carried out on two subjects during 4 working days: 1 day of "reference work" or classical clerical activities, 3 days of "data entry work". Although the time allowed for the task was not limited, the performance assessed from oculomotor patterns remained stable throughout the day, from one day to the next and from one subject to another. This stability was reflected on the stereotyped E.E.G. patterns recorded during the work period, the differences occurring between reading and typing were more acute in the left cortical hemisphere than in the right. As a result of these stable patterns, the ultradian oscillations of the behavioural and physiological parameters were less during data entry than during work reference. The only possible time adjustments were the interruptions or breaks between two document pages and their variations could be considered as indicators of work load.     

When Are We Most Vulnerable to Temperature Variations in a Day?

Daily temperature measures are commonly used when examining the association between temperature and mortality. In fact, temperature measures are available 24 hours a day and more detailed records may provide a better prediction of mortality compared to daily statistics. In this article, monthly stratified analysis modeling for mortality is conducted for the total population as well as the stratified elderly and younger subgroups. We identified the most significant time during the day that is associated with daily mortality. Surprisingly, the estimates of relative risk and magnitude of associations derived from the hourly temperature measures are similar or even stronger compared to those modeled by the daily statistics. This phenomenon remains true for lagged hourly temperature measures and the changing patterns of associations from January through December are revealed. In summary, people are the most vulnerable to temperature variations in the early morning around 5 am and the night time around 8 pm.     

Development of a Wearable Framework for the Assessment of a Mechanical-Based Indicator of Falling Risk in the Field

ObjectivesThe characterization of the instability of gait is a current challenge of biomechanics. Indeed, risks of falling naturally result from the difficulty to control perturbations of the locomotion pattern. Hence, the assessment of a synthetic parameter able to quantify the instability in real time will be useful for the prevention of falls occurring in this context. Thus, the objective of the present study, in two steps, was to propose and evaluate a relevant parameter to quantify the risk of fallings.Material and MethodsExperimental analysis of the gait of 11 able-bodied subjects from a motion capture system in laboratory condition was performed. The distance of the Body Center of Mass (BCOM) to the Minimal Moment Axis (MMA) was computed as a proxy of whole-body angular momentum variations. In a second step, we quantified the kinematics during gait with wearable Inertial Measurement Units (IMU) fixed on two individuals (one able bodied person and one person with transfemoral amputation). We compared the IMU-based BCOM kinematics with a motion capture reference system to verify the accuracy of our measures in the field.ResultsNormative thresholds of the distance of the Body Center of Mass (BCOM) to the Minimal Moment Axis (MMA) during able-bodied level walking were assessed. The average error between the BCoM displacement computed from the IMU and from the reference vicon data of 4 mm, 3 mm and 53 mm on the mediolateral, anteroposterior and vertical axes respectively.ConclusionAll these results make it possible to consider the determination of the risks of falls in the field at mid-term. the research on an optimal configuration that maintain the performance while simplifying the device will be essential to make it acceptable by the individuals.     

Semi-empirical power-law scaling of new infection rate to model epidemic dynamics with inhomogeneous mixing

The expected number of new infections per day per infectious person during an epidemic has been found to exhibit power-law scaling with respect to the susceptible fraction of the population. This is in contrast to the linear scaling assumed in traditional epidemiologic modeling. Based on simulated epidemic dynamics in synthetic populations representing Los Angeles, Chicago, and Portland, we find city-dependent scaling exponents in the range of 1.7-2.06. This scaling arises from variations in the strength, duration, and number of contacts per person. Implementation of power-law scaling of the new infection rate is quite simple for SIR, SEIR, and histogram-based epidemic models. Treatment of the effects of the social contact structure through this power-law formulation leads to significantly lower predictions of final epidemic size than the traditional linear formulation.     

Effect of habitat quality on the ecological behaviour of a temperate-living primate: time-budget adjustments

Barbary macaques, like other non-human primates living in highly seasonal temperate environments, display high monthly variations in their diet. In addition, their diet changes according to the habitat type they colonize and to the degree of habitat degradation due to resource exploitation by local people, in particular through pastoralism. We studied the time-budget adjustments of wild Barbary macaques in three cedar–oak forests impacted by different intensities of grazing pressure from goats and sheep. We examined how diet variations influenced the time monkeys spent in their activities and their day range lengths (i.e. their energy costs). At three studied sites, diet composition and time budgets showed marked seasonal variations. Diet composition had a strong influence on monkeys’ time budget. In the forest where pastoralism was the highest, diet included a greater proportion of underground resources, shrub fruit and acorns, which led to an increase in the time spent foraging and moving, as well as an important increase in day range lengths. Energy costs were therefore higher in a degraded environment than in a suitable habitat. The monkeys living in forests subjected to pastoralism took advantage of increased day lengths to spend more time searching for food. However, in the forest with the highest pastoralism pressure, although monkeys spent more time foraging, they spent less time feeding than monkeys at the other sites. In addition, they appeared to have reached the limits of the available time they could devote to these activities, as their diurnal resting time was at its lowest level over several months. Temperature variations did not appear to modify monkeys’ time budgets. In the least favourable habitat, saving time from resting activity allowed monkeys to maintain a relatively high level of social activity, partly linked to rearing constraints.     

The variability and volatility of sleep: An ARCHetypal behavior

Using 1975–2005 Dutch time-diary data covering over 10,000 respondents for 7 consecutive days each, we show that sleep time exhibits non-constant variability, or volatility, characterized by stationary autoregressive conditional heteroscedasticity: The absolute values of deviations from a person’s average sleep on one day are positively correlated with those on adjacent days. Sleep is more variable on weekends and among younger people, those without young children, or with less education. Volatility is greater among parents with young children, slightly greater among men, but independent of other demographics. Economic incentives to minimize the dispersion of sleep imply higher-wage workers will exhibit less dispersion, which we observe. Sleep volatility spills over onto volatility in other personal activities, with no reverse causation onto sleep. The results illustrate a novel dimension of inequality among people and could be applied to a wide variety of human behavior and biological processes.     

La medición de la dependencia a partir del tiempo de cuidado y del baremo de valoración de dependencia

AimsTo assign care time to the activities collected in the Dependency Assessment Scale (BVD) and to analyse the relationship between care time and the score received on the BVD.MethodsA cross-sectional observational study of 148 dependent persons was carried out. Socioeconomic and clinical data, the BVD, the 6-dimensional dependency indicator (DEP-6D), as well as data from a diary with the time of care received, were collected. The median time needed to carry out the activities included in the BVD was estimated from the diary. Following the BVD methodology, those who had their mental functions affected were separated. Each person was assigned two scores, one based on BVD and the other based on the time that the caregivers spent to care for them. The correlation between the two was estimated, and a regression was performed to identify the main explanatory factors for the disparity between the two indicators.ResultsBVD and hours of care show a moderate positive correlation. The mental impairment of the dependent person increased the time of care in most activities. The regression analysis suggests that while mental impairment is the main explanatory factor of obtaining a higher assessment with care time than with BVD, being bedridden is the main predictor of having a higher sore with the BVD.ConclusionsThe construct that underlies BVD is moderately related to care time. Future research must contrast the robustness of these results and address whether the normative criteria that underlie the BVD is aligned with the weights that characterise it.     

Learning Low-Rank Class-Specific Dictionary and Sparse Intra-Class Variant Dictionary for Face Recognition

Face recognition is challenging especially when the images from different persons are similar to each other due to variations in illumination, expression, and occlusion. If we have sufficient training images of each person which can span the facial variations of that person under testing conditions, sparse representation based classification (SRC) achieves very promising results. However, in many applications, face recognition often encounters the small sample size problem arising from the small number of available training images for each person. In this paper, we present a novel face recognition framework by utilizing low-rank and sparse error matrix decomposition, and sparse coding techniques (LRSE+SC). Firstly, the low-rank matrix recovery technique is applied to decompose the face images per class into a low-rank matrix and a sparse error matrix. The low-rank matrix of each individual is a class-specific dictionary and it captures the discriminative feature of this individual. The sparse error matrix represents the intra-class variations, such as illumination, expression changes. Secondly, we combine the low-rank part (representative basis) of each person into a supervised dictionary and integrate all the sparse error matrix of each individual into a within-individual variant dictionary which can be applied to represent the possible variations between the testing and training images. Then these two dictionaries are used to code the query image. The within-individual variant dictionary can be shared by all the subjects and only contribute to explain the lighting conditions, expressions, and occlusions of the query image rather than discrimination. At last, a reconstruction-based scheme is adopted for face recognition. Since the within-individual dictionary is introduced, LRSE+SC can handle the problem of the corrupted training data and the situation that not all subjects have enough samples for training. Experimental results show that our method achieves the state-of-the-art results on AR, FERET, FRGC and LFW databases.     

Short-term repeatability of parameters extracted from radial displacement of muscle belly.

The aim of this study is to analyse the short-term repeatability of the parameters extracted from radial muscle belly response on a stimulation pulse. The method uses a prefixed tension of a displacement sensor tip to the muscle and is being developed for noninvasive and selective evaluation of skeletal muscle contraction properties. Five parameters were extracted and statistically evaluated from the measured displacement: maximal displacement, delay time, contraction time, sustain time and half relaxation time. Care has been taken to leave sufficient time between stimulation pulses in order to reduce the effect of muscle fatigue and a constant pre-tension was assured by controlled step motor in consecutive measurement by withdrawal and anew placement of the sensor to the muscle belly after each measurement. Intra-class correlation coefficient (ICC) and normalized squared error (NSEM) were used as measures of short-term repeatability and accuracy (precision) of the measurements while fatigue rate was evaluated using area ratio fatigue index and normalized slope. All five measured parameters have been found highly repeatable (ICC from 0.86 to 0.98) and can be measured with high precision (NSEM from 0.43 to 1.93). Maximal displacement and half relaxation time show largest influence to muscle fatigue rate and are also expected to be the best measure of the fatigue rate. This investigation should serve as an initial study of repeatability of the presented method that should help in subsequent investigations and use of the method.     

Gene and Genome Parameters of Mammalian Liver Circadian Genes (LCGs)

The mammalian circadian system controls various physiology processes and behavior responses by regulating thousands of circadian genes with rhythmic expressions. In this study, we redefined circadian-regulated genes based on published results in the mouse liver and compared them with other gene groups defined relative to circadian regulations, especially the non-circadian-regulated genes expressed in liver at multiple molecular levels from gene position to protein expression based on integrative analyses of different datasets from the literature. Based on the intra-tissue analysis, the liver circadian genes or LCGs show unique features when compared to other gene groups. First, LCGs in general have less neighboring genes and larger in both genomic and 3′-UTR lengths but shorter in CDS (coding sequence) lengths. Second, LCGs have higher mRNA and protein abundance, higher temporal expression variations, and shorter mRNA half-life. Third, more than 60% of LCGs form major co-expression clusters centered in four temporal windows: dawn, day, dusk, and night. In addition, larger and smaller LCGs are found mainly expressed in the day and night temporal windows, respectively, and we believe that LCGs are well-partitioned into the gene expression regulatory network that takes advantage of gene size, expression constraint, and chromosomal architecture. Based on inter-tissue analysis, more than half of LCGs are ubiquitously expressed in multiple tissues but only show rhythmical expression in one or limited number of tissues. LCGs show at least three-fold lower expression variations across the temporal windows than those among different tissues, and this observation suggests that temporal expression variations regulated by the circadian system is relatively subtle as compared with the tissue expression variations formed during development. Taken together, we suggest that the circadian system selects gene parameters in a cost effective way to improve tissue-specific functions by adapting temporal variations from the environment over evolutionary time scales.     

How to monitor environmental pressures of a circular economy: An assessment of indicators

Understanding how a circular economy (CE) can reduce environmental pressures from economic activities is crucial for policy and practice. Science provides a range of indicators to monitor and assess CE activities. However, common CE activities, such as recycling and eco‐design, are contested in terms of their contribution to environmental sustainability. This article assesses whether and to what extent current approaches to assess CE activities sufficiently capture environmental pressures to monitor progress toward environmental sustainability. Based on a material flow perspective, we show that most indicators do not capture environmental pressures related to the CE activities they address. Many focus on a single CE activity or process, which does not necessarily contribute to increased environmental sustainability overall. Based on these results, we suggest complementing CE management indicators with indicators capturing basic environmental pressures related to the respective CE activity. Given the conceptual linkage between CE activities, resource extraction, and waste flows, we suggest that a resource‐based footprint approach accounting for major environmental inputs and outputs is necessary—while not sufficient—to assess the environmental sustainability of CE activities. As footprint approaches can be used across scales, they could aid the challenging process of developing indicators for monitoring progress toward an environmentally sustainable CE at the European, national, and company levels.     

Obesity and skill attainment in early childhood

This paper investigates the association between obesity and skill attainment in early childhood (aged 2-3 years). Data from the German Socio-Economic Panel Study are used to estimate models of developmental functioning in four critical areas (verbal skills, activities of daily living, motor skills, and social skills) as a function of various measures of weight (including body mass index and obesity) controlling for a rich set of child, parent, and family characteristics. The findings indicate that, among boys, obesity is associated with reduced verbal skills, social skills, motor skills, and activities of daily living. Among girls, obesity is associated with reduced verbal skills. Further investigations show that the correlations exist even for those preschool children who spend no time in day care, which implies that the correlations cannot be due solely to discrimination by teachers, classmates, or day care providers.     

An Experience Sampling Approach to Investigating Associations between Pet Presence and Indicators of Psychological Wellbeing and Mood in Older Australians

ABSTRACT

In this study we examined associations between pet ownership and presence and indicators of psychological wellbeing in older Australians, using an innovative, experience sampling methodology and a community-living sample of 68 adults, including 41 pet owners, all aged over 65 years. In response to randomized prompts the participants provided information about their location, social companions, activities, and mood state six times daily for seven consecutive days. They also completed a number of surveys measuring various aspects of wellbeing. There were no significant differences in our outcome measures between pet owners and those who did not own at least one pet, and few of our pet owners reported engaging in pet-focused human– animal activities, such as walking their dog or playing with their cat. However, frequency of pet presence during activities of daily living was associated with, and statistically predictive of, several measures of wellbeing and mood. From our results we tentatively conclude that more frequent presence of a pet, particularly a dog, may be associated with greater psychological wellbeing in this cohort. More importantly, we confirm that the intensive experience sampling methodology provides a novel means of examining human–pet interactions, enabling a closer analysis of moment-by-moment pet presence than has been possible using alternative approaches.     

Using multiple indicators to assess the environmental status in impacted and non-impacted bathing waters in the Iranian Caspian Sea

Human activities have increased in the Caspian Sea in last decades, impacting the coastal zone ecosystems. One of the increasing activities is recreation, including bathing areas in the south of the Caspian Sea, which have been scarcely studied and assessed. Investigating the interactions between human activities and the resulting environmental status in bathing areas, by using adequate indicators and assessment methods, is necessary to undertake management measures for ecosystem restoration. In this study, for the first time, we use the Nested Environmental status Assessment Tool (NEAT) outside the European waters to assess environmental status in bathing waters, to differentiate areas impacted and non-impacted by bathing activities. We have assessed the status in winter and summer seasons, by combining multiple indicators from different ecosystem components (8 physico-chemical, 4 bacteria, 2 plankton, and 1 benthos indicators). Despite the interactions between season and human affection, NEAT determined that the Caspian Seas is not in good status, differentiating, in summer, between impacted and non-impacted bathing areas, with a significant correlation with the number of beach users. Accordingly, management measures should be taken in the southern Caspian Sea to improve the environmental status in general and that of bathing areas in particular.     

Bridging the gap: transnational and ethnic organizations in the political incorporation of immigrants in the United States

This study was prompted by concerns about the ways in which immigrant organizations, especially those of a transnational character, may retard or prevent political integration among recent migrants to the United States. For this purpose, we constructed an inventory of all organizations created by Colombian, Dominican and Mexican immigrants in the United States, interviewed leaders of the twenty largest organizations from each group in person, and conducted a survey of 178 additional organizations by telephone or Internet. Results reveal a near-absence of perceived conflict between transnational activism and political incorporation. Almost without exception, leaders asserted that there was no contradiction between home-country loyalties and activities and US citizenship and voting. These results appear to reflect genuine conviction, rather than any social desirability syndrome. Objective indicators show that most organizations maintain close ties with US political authorities at various levels and engage in a number of US-focused civic and political activities. Determinants of such engagement are examined. Implications of the results for theory and public policy are discussed.     

Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos

Understanding the variations of the functional response of an organism, i.e. the predation rate in relation to prey density, is necessary to understand the interactions between the animal and its food supply. This has received little attention in dabbling ducks so we investigated experimentally the shape of the functional response of mallard feeding on poultry pellets, and assessed the influence of several factors such as the size of food items, sex or individual performance on this functional response. Individual differences in intake rate are of crucial importance in group or gregarious foraging species. We used two approaches of the functional response: 1) the relation between feeding rate (pellets/s) and pellet densities (pellets/m²), and 2) the relationship between instantaneous intake rate (g/s) and biomass density (g/m²). For both approaches, we found that the Type II functional response gave better estimates than a Type I linear functional response but explained only a third of the variance. Our results show that pellet size has a large effect on instantaneous intake rate. The comparison of the functional response parameters suggest that handling time per prey may not reflect the real constraints on intake rate, but that handling time per gram ingested may be more appropriate to integrate the effect of item size in the functional response. We then discuss the possible mechanisms involved. We also found individual variations in the functional response for each of the experiments, with some consistency in the hierarchy regarding feeding efficiency. We did not find any differences between males and females. Our results provide an evaluation of individual variations in intake rate in interference-free conditions, which has rarely been done, and call for more controlled experiments to allow a finer understanding of the mechanisms of food acquisition in dabbling ducks.     

Diel and Seasonal Variations in Abundance,Activity, and Community Structure of Particle-Attached and Free-Living Bacteria in NW Mediterranean Sea

Diel and seasonal variations in abundance, activity, and structure of particle-attached vs free-living bacterial communities were investigated in offshore NW Mediterranean Sea (0–1000 m). Attached bacteria were always less abundant and less diverse but generally more active than free-living bacteria. The most important finding of this study was that the activity of attached bacteria showed pronounced diel variations in the upper mixed water column with higher activities at night. Under mesotrophic conditions, the contribution of attached bacteria to total bacterial activity increased from less than 10% at day time to 83% at night time. At high chlorophyll a concentration, the highest cell-specific activities and contribution to total bacterial activity were due to free-living bacteria at day and to attached bacteria at night. Under summer oligotrophic conditions, free-living bacteria dominated and contributed to the most important part of the bacterial activity at both day and night, whereas attached bacteria were much less abundant but presented the highest cell-specific activities. These diel and seasonal variations in activities were concomitant to changes in bacterial community structure, mainly in the upper layer. The number of attached ribotypes was fairly constant suggesting that particles are colonized by a relatively limited number of ubiquitous ribotypes. Most of these ribotypes were also free-living ribotypes suggesting that attached bacteria probably originate from colonization of newly formed particles by free-living bacteria in the upper layer. These results reinforce the biogeochemical role of attached bacteria in the cycling of particulate organic carbon in the NW Mediterranean Sea and the importance of diel variability in these processes.     

Cognitive and behavioral characteristics of turner syndrome: exploring a role for ovarian hormones in female sexual differentiation

To better understand factors contributing to behavioral development, we studied patients with Turner syndrome (TS), a disorder typically marked by prenatal onset of ovarian dysfunction. We compared girls and women (ages 12 and up) with TS (n = 21) to matched controls (n = 21) in cognitive and motor skills, as well as sex-typed personality characteristics and activity preferences. Measures were categorized (based on prior studies) as showing an average male advantage (male-superior measures), female advantage (female-superior measures), or no sex difference (sex-neutral measures). It was hypothesized that, if gonadal function contributes to behavioral development, effects of this deficiency would be more prominent on sexually differentiated than sex-neutral measures and thus that patient-control differences would be most marked for measures that show sex differences. Our findings indicated that TS patients and controls differed more on cognitive and motor domains that show sex differences than on sex-neutral domains. Patients also had more "undifferentiated" personalities and showed reduced sex-typed interests and activities. Differing experiences, as indexed by interests and activities, did not explain the observed cognitive and motor differences. These results are consistent with a role for ovarian hormones acting on the brain to influence cognitive and behavioral development, although they do not rule out other possible interpretations.     

Homeostatic and circadian regulation of cognitive performance

Cognitive processes are crucial for human performance. Basic cognitive processes, such as attention, working memory, and executive functions, show homeostatic (time awake, sleep deprivation) and circadian (time of day) variations. Each of these cognitive processes includes several components, which contribute sequentially to the homeostatic and circadian modulation of performance. Sudden (lapses) and gradual changes in cognitive performance occur with sleep deprivation or with time of day. The time course of human cognitive processes throughout the day is relevant to the programming of different human activities. The lowest level of cognitive performance occurs during nighttime and early in the morning, a better level occurs around noon, and even higher levels occur during afternoon and evening hours. However, this time course can be modulated by conditions such as chronotype, sleep deprivation, sleep disorders or medication that affects the central nervous system.     

Turnover of rod photoreceptor outer segments. II. Membrane addition and loss in relationship to light

The rate of disk addition to rod outer segments (ROS) varies widely in Xenopus laevis tadpoles kept in cyclic light (12L:12D). When measured as radioactive band (3H-band) displacement during the 2nd day after injection of [3H]leucine, 75% of the daily increment of displacement occurred during the first 8 h of light. During the same interval, the number of open disks at the ROS base increased more than threefold. During the last 8 h of darkness, 3H-band displacement was undetectable and the number of open disks was reduced. These observations suggest the possibility that disk addition may occur discontinuously. During the 3rd and 4th days after injection of [3H]leucine, maximal displacement of the 3H-band occurred later in the day than on the 2nd day, its movement no longer corresponding to the increase in open disks. This delay in 3H-band displacement may reflect a time delay as a result of propagation of compressive stress in an elastic ROS system. Maximal disk loss from ROS as reflected in counts of phagosomes in the pigment epithelium occurred within 1 h of light exposure, and phagosome counts remained high for 4 h before declining to a low level in darkness. Modified lighting regimes affected the daily rhythms of shedding and disk addition differently, suggesting that control mechanisms for the two processes are not directly coupled. During 3 days in darkness, disk addition was reduced 50% compared to controls (12L:12D), whereas shedding was reduced by about 40%. Although reduced in level, shedding occurred as a free-running circadian rhythm. There was no evidence of rhythmicity of disk addition in darkness. In constant light, the rate of disk addition was not different from controls, but shedding was reduced by about 80% after the 1st day. This resulted in a 21% increase in ROS length. Among animals kept on a 2.5L:21.5D cycle, the rate of disk addition was reduced by 40% while shedding was maintained near control levels, resulting in a slight decrease in ROS length. These observations indicate that normal shedding requires alternating light and darkness, and that the daily rhythm of disk addition is due primarily to daily stimulation by light.