A new approach for evaluating flexible working hours.

Science.gov (United States)

Giebel, Ole; Janssen, Daniela; Schomann, Carsten; Nachreiner, Friedhelm

2004-01-01

Recent studies on flexible working hours show at least some of these working time arrangements seem to be associated with impairing effects of health and well-being. According to available evidence, variability of working hours seems to play an important role. The question, however, is how this variability can be assessed and used to explain or predict impairments. Based on earlier methods used to assess shift-work effects, a time series analysis approach was applied to the matter of flexible working hours. Data on the working hours of 4 week's length of 137 respondents derived from a survey on flexible work hours involving 15 companies of different production and service sectors in Germany were converted to time series and analyzed by spectral analysis. A cluster analysis of the resulting power spectra yielded 5 clusters of flexible work hours. Analyzing these clusters for differences in reported impairments showed that workers who showed suppression of circadian and weekly rhythms experienced severest impairments, especially in circadian controlled functions like sleep and digestion. The results thus indicate that analyzing the periodicity of flexible working hours seems to be a promising approach for predicting impairments which should be investigated further in the future.

X-ray spectra and time variability of active galactic nuclei

International Nuclear Information System (INIS)

Mushotzky, R.F.

1984-02-01

The X-ray spectra of broad line active galactic nuclei (AGN) of all types (Seyfert I's, NELG's, broadline radio galaxies) are well fit by a power law in the .5 to 100 keV band of man energy slope alpha .68 + or - .15. There is, as yet, no strong evidence for time variability of this slope in a given object. The constraints that this places on simple models of the central energy source are discussed. BL Lac objects have quite different X-ray spectral properties and show pronounced X-ray spectral variability. On time scales longer than 12 hours most radio quiet AGN do not show strong, delta I/I .5, variability. The probability of variability of these AGN seems to be inversely related to their luminosity. However characteristics timescales for variability have not been measured for many objects. This general lack of variability may imply that most AGN are well below the Eddington limit. Radio bright AGN tend to be more variable than radio quiet AGN on long, tau approx 6 month, timescales

The Relation Between Skill Levels and the Cyclical Variability of Employment, Hours, and Wages

OpenAIRE

Michael P. Keane; Eswar S Prasad

1993-01-01

This paper uses micro data to examine differences in the cyclical variability of employment, hours, and wages for skilled and unskilled workers. Contrary to conventional wisdom, we find that, at the aggregate level, skilled and unskilled workers are subject to essentially the same degree of cyclical variation in wages. That is, relative offer wage differentials between skilled and unskilled workers are acyclical. However, we do find important differences in the patterns of employment and hour...

High-resolution grids of hourly meteorological variables for Germany

Science.gov (United States)

Krähenmann, S.; Walter, A.; Brienen, S.; Imbery, F.; Matzarakis, A.

2018-02-01

We present a 1-km2 gridded German dataset of hourly surface climate variables covering the period 1995 to 2012. The dataset comprises 12 variables including temperature, dew point, cloud cover, wind speed and direction, global and direct shortwave radiation, down- and up-welling longwave radiation, sea level pressure, relative humidity and vapour pressure. This dataset was constructed statistically from station data, satellite observations and model data. It is outstanding in terms of spatial and temporal resolution and in the number of climate variables. For each variable, we employed the most suitable gridding method and combined the best of several information sources, including station records, satellite-derived data and data from a regional climate model. A module to estimate urban heat island intensity was integrated for air and dew point temperature. Owing to the low density of available synop stations, the gridded dataset does not capture all variations that may occur at a resolution of 1 km2. This applies to areas of complex terrain (all the variables), and in particular to wind speed and the radiation parameters. To achieve maximum precision, we used all observational information when it was available. This, however, leads to inhomogeneities in station network density and affects the long-term consistency of the dataset. A first climate analysis for Germany was conducted. The Rhine River Valley, for example, exhibited more than 100 summer days in 2003, whereas in 1996, the number was low everywhere in Germany. The dataset is useful for applications in various climate-related studies, hazard management and for solar or wind energy applications and it is available via doi: 10.5676/DWD_CDC/TRY_Basis_v001.

Prediction of hourly PM2.5 using a space-time support vector regression model

Science.gov (United States)

Yang, Wentao; Deng, Min; Xu, Feng; Wang, Hang

2018-05-01

Real-time air quality prediction has been an active field of research in atmospheric environmental science. The existing methods of machine learning are widely used to predict pollutant concentrations because of their enhanced ability to handle complex non-linear relationships. However, because pollutant concentration data, as typical geospatial data, also exhibit spatial heterogeneity and spatial dependence, they may violate the assumptions of independent and identically distributed random variables in most of the machine learning methods. As a result, a space-time support vector regression model is proposed to predict hourly PM2.5 concentrations. First, to address spatial heterogeneity, spatial clustering is executed to divide the study area into several homogeneous or quasi-homogeneous subareas. To handle spatial dependence, a Gauss vector weight function is then developed to determine spatial autocorrelation variables as part of the input features. Finally, a local support vector regression model with spatial autocorrelation variables is established for each subarea. Experimental data on PM2.5 concentrations in Beijing are used to verify whether the results of the proposed model are superior to those of other methods.

Long Work Hours: Volunteers and Conscripts

OpenAIRE

Robert Drago; Mark Wooden; David Black

2006-01-01

Panel data from Australia are used to study the prevalence of work hours mismatch among long hours workers and, more importantly, how that mismatch persists and changes over time, and what factors are associated with these changes. Particular attention is paid to the roles played by household debt, ideal worker characteristics and gender. Both static and dynamic multinomial logit models are estimated, with the dependent variable distinguishing long hours workers from other workers, and within...

Circadian Disruptions of Heart Rate Variability among Weekly Consecutive-12-hour 2 Shift Workers in the Automobile Factory in Korea.

Science.gov (United States)

Son, Mia; Sung, Juhon; Yum, Myunggul; Kong, Jung Ok; Lee, Hye Un; Kim, In A; Kim, Jung Yeon

2004-05-01

The objective of this study is to compare the circadian patterns of heart rate variability assessed by 24-hour ambulatory electrocardiographic (ECG) recordings during day shift and night shift among the workers in the 5 days-concecutive- 12-hour shift in an automobile factory in Korea. The study population consisted 300 workers, who were randomly selected among the 8700 total workers in one car factory. To analyse circadian variation, the 24-hour ECG recordings (Marquette) were measured during day shift (08: 00-20: 00 h) and night shift (20: 00-08: 00 h). Analysis was performed for all time and frequency domain measures of HRV. 233 workers completed taking 24-hour ECG recordings. This study shows that the 24 hourcircadian variation mainly follows work/sleep cycle rather than day/night cycle among shift workers. This study also shows that among the night shift, the circadian variation between work and sleep cycle decreased compared to the work/sleep cycle among day shift workers. All time and frequency domain parameters (except LF/HF ratio) show significantly different between work and sleep in the day shift and night shift. These changes in heart rate variability circadian rhythms reflect significant reductions in cardiac parasympathetic activity with the most marked reduction in normal vagal activity among the shift workers. Especially, it suggests the circadian rhytm has blunted among the night workers. The quantification of the circadian variation in HRV can be a surrogates of workers' potential health risk, as well as suggests possible mechanisms through which the shift works compromise workers' health.

Health and psychosocial effects of flexible working hours.

Science.gov (United States)

Janssen, Daniela; Nachreiner, Friedhelm

2004-12-01

To examine whether any impairments in health and social lives can be found under different kinds of flexible working hours, and whether such effects are related to specific characteristics of these working hours. Two studies -- a company based survey (N=660) and an internet survey (N=528) -- have been conducted. The first one was a questionnaire study (paper and pencil) on employees working under some 'typical' kinds of different flexible working time arrangements in different companies and different occupational fields (health care, manufacturing, retail, administration, call centres). The second study was an internet-based survey, using an adaptation of the questionnaire from the first study. The results of both studies consistently show that high variability of working hours is associated with increased impairments in health and well-being and this is especially true if this variability is company controlled. These effects are less pronounced if variability is self-controlled; however, autonomy does not compensate the effects of variability. Recommendations for an appropriate design of flexible working hours should be developed in order to minimize any impairing effects on health and psychosocial well-being; these recommendations should include -- besides allowing for discretion in controlling one's (flexible) working hours -- that variability in flexible working hours should be kept low (or at least moderate), even if this variability is self-controlled.

Effects on employees of controlling working hours and working schedules.

Science.gov (United States)

Kubo, T; Takahashi, M; Togo, F; Liu, X; Shimazu, A; Tanaka, K; Takaya, M

2013-03-01

High levels of control over working time and low variability in working hours have been associated with improved health-related outcomes. The potential mechanisms for this association remain unclear. To examine how work-time control and variability of working times are associated with fatigue recovery, sleep quality, work-life balance, and 'near misses' at work. Manufacturing sector employees completed a questionnaire that assessed work-time control, work-time variability, fatigue recovery, sleep quality, work-life balance and the frequency of near misses in the past 6 months. Mixed model analysis of covariance and multiple logistic regression analysis tested the main effects of work-time control and variability and their interaction, while adjusting for age, sex, work schedules, and overtime work in the past month. Subscales of work-time control were also investigated (control over daily working hours and over days off). One thousand three hundred and seventy-two completed questionnaires were returned, a response rate of 69%. A significantly higher quality of sleep and better work-life balance were found in the 'high control with low variability' reference group than in the other groups. Significantly better recovery of fatigue was also observed in the group having control over days off with low variability. While near misses were more frequent in the group with high control over daily working hours coupled with high variability compared with the reference group this was not significant. High work-time control and low variability were associated with favourable outcomes of health and work-life balance. This combined effect was not observed for the safety outcome addressed here.

Comparison of anthropometric and training characteristics between recreational male marathoners and 24-hour ultramarathoners.

Science.gov (United States)

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas

2012-01-01

Of the anthropometry and training variables used to predict race performance in a 24-hour ultrarun, the personal best marathon time is the strongest predictor in recreational male 24-hour ultramarathoners. This finding raises the question of whether similarities exist between male recreational 24-hour ultramarathoners and male recreational marathoners. The association between age, anthropometric variables (ie, body mass, body height, body mass index, percent body fat, skeletal muscle mass, limb circumference, and skinfold thickness at the pectoral, mid axillary, triceps, subscapular, abdominal, suprailiac, front thigh, and medial calf sites), previous experience and training characteristics (ie, volume, speed, and personal best time), and race time for 79 male recreational 24-hour ultramarathoners and 126 male recreational marathoners was investigated using bivariate and multivariate analysis. The 24-hour ultramarathoners were older (P marathoners. During training, the 24-hour ultramarathoners were running for more hours per week (P marathoners. In the 24-hour ultramarathoners, neither anthropometric nor training variables were associated with kilometers completed in the race (P > 0.05). In the marathoners, percent body fat (P marathon race times. In summary, differences in anthropometric and training predictor variables do exist between male recreational 24-hour ultramarathoners and male recreational marathoners for race performance.

Correlation of 2 hour, 4 hour, 8 hour and 12 hour urine protein with 24 hour urinary protein in preeclampsia.

Directory of Open Access Journals (Sweden)

Savita Rani Singhal

2014-09-01

Full Text Available To find shortest and reliable time period of urine collection for determination of proteinuria.It is a prospective study carried out on 125 pregnant women with preeclampsia after 20 weeks of gestation having urine albumin >1 using dipstick test. Urine was collected in five different time intervals in colors labeled containers with the assistance of nursing staff; the total collection time was 24 hours. Total urine protein of two-hour, four-hour, eight-hour, 12-hour and 24-hour urine was measured and compared with 24-hour collection. Data was analyzed using the Pearson correlation coefficient.There was significant correlation (p value < 0.01 in two, four, eight and 12-hour urine protein with 24-urine protein, with correlation coefficient of 0.97, 0.97, 0.96 and 0.97, respectively. When a cut off value of 25 mg, 50 mg. 100 mg, and 150 mg for urine protein were used for 2-hour, 4-hours, 8-hour and 12-hour urine collection, a sensitivity of 92.45%, 95.28%, 91.51%, and 96.23% and a specificity of 68.42%, 94.74%, 84.21% and 84.21% were obtained, respectively.Two-hour urine proteins can be used for assessment of proteinuria in preeclampsia instead of gold standard 24-hour urine collection for early diagnosis and better patient compliance.

Time for Children, One's Spouse and Oneself among Parents Who Work Nonstandard Hours

Science.gov (United States)

Wight, Vanessa R.; Raley, Sara B.; Bianchi, Suzanne M.

2008-01-01

Using data from the 2003 and 2004 American Time Use Surveys, this article examines nonstandard work hours and their relationship to parents' family, leisure and personal care time--informing the discussion of the costs and benefits of working nonstandard hours. The results suggest that parents who work nonstandard evening hours spend less time in…

Standard deviation of wind direction as a function of time; three hours to five hundred seventy-six hours

International Nuclear Information System (INIS)

Culkowski, W.M.

1976-01-01

The standard deviation of horizontal wind direction sigma/sub theta/ increases with time of averaging up to a maximum value of 104 0 . The average standard deviation of horizontal wind directions averaged over periods of 3, 5, 10, 16, 24, 36, 48, 72, 144, 288, and 576 hours were calculated from wind data obtained from a 100 meter tower in the Oak Ridge area. For periods up to 100 hours, sigma/sub theta/ varies as t/sup .28/; after 100 hours sigma/sub theta/ varies as 6.5 ln t

Unsupervised/supervised learning concept for 24-hour load forecasting

Energy Technology Data Exchange (ETDEWEB)

Djukanovic, M [Electrical Engineering Inst. ' Nikola Tesla' , Belgrade (Yugoslavia); Babic, B [Electrical Power Industry of Serbia, Belgrade (Yugoslavia); Sobajic, D J; Pao, Y -H [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Electrical Engineering and Computer Science

1993-07-01

An application of artificial neural networks in short-term load forecasting is described. An algorithm using an unsupervised/supervised learning concept and historical relationship between the load and temperature for a given season, day type and hour of the day to forecast hourly electric load with a lead time of 24 hours is proposed. An additional approach using functional link net, temperature variables, average load and last one-hour load of previous day is introduced and compared with the ANN model with one hidden layer load forecast. In spite of limited available weather variables (maximum, minimum and average temperature for the day) quite acceptable results have been achieved. The 24-hour-ahead forecast errors (absolute average) ranged from 2.78% for Saturdays and 3.12% for working days to 3.54% for Sundays. (Author)

Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability.

Science.gov (United States)

Wang, Chao; Ding, Mingzhou; Kluger, Benzi M

2014-03-01

Cognitive fatigability is conventionally quantified as the increase over time in either mean reaction time (RT) or error rate from two or more time periods during sustained performance of a prolonged cognitive task. There is evidence indicating that these mean performance measures may not sufficiently reflect the response characteristics of cognitive fatigue. We hypothesized that changes in intraindividual variability over time would be a more sensitive and ecologically meaningful metric for investigations of fatigability of cognitive performance. To test the hypothesis fifteen young adults were recruited. Trait fatigue perceptions in various domains were assessed with the Multidimensional Fatigue Index (MFI). Behavioral data were then recorded during performance of a three-hour continuous cued Stroop task. Results showed that intraindividual variability, as quantified by the coefficient of variation of RT, increased linearly over the course of three hours and demonstrated a significantly greater effect size than mean RT or accuracy. Change in intraindividual RT variability over time was significantly correlated with relevant subscores of the MFI including reduced activity, reduced motivation and mental fatigue. While change in mean RT over time was also correlated with reduced motivation and mental fatigue, these correlations were significantly smaller than those associated with intraindividual RT variability. RT distribution analysis using an ex-Gaussian model further revealed that change in intraindividual variability over time reflects an increase in the exponential component of variance and may reflect attentional lapses or other breakdowns in cognitive control. These results suggest that intraindividual variability and its change over time provide important metrics for measuring cognitive fatigability and may prove useful for inferring the underlying neuronal mechanisms of both perceptions of fatigue and objective changes in performance. Copyright © 2014

Long working hours and emotional well-being in korean manufacturing industry employees.

Science.gov (United States)

Lee, Kyoung-Hye; Kim, Jong-Eun; Kim, Young-Ki; Kang, Dong-Mug; Yun, Myeong-Ja; Park, Shin-Goo; Song, Jae-Seok; Lee, Sang-Gil

2013-12-05

Korea is well known for its long work hours amongst employees. Because workers of the manufacturing industry are constantly exposed to extended work hours, this study was based on how long work hours affect their emotional well-being. The analysis was done using the secondary Korean Working Condition Survey (KWCS). Long work hours were defined to be more than 48 hours, and they were subcategorized into units of 52 hours and 60 hours. Based on the WHO (five) well-being index, emotional state was subdivided into three groups - reference group, low-mood group, and possible depression group- where 28 points and 50 points were division points, and two groups were compared at a time. Association between long work hours and emotional state was analyzed using binary and multinomial logistic regression analysis. Working for extended working hours in the manufacturing industry showed a statistically significant increase (t test p work-related characteristics were fixed as controlled variables, as work hours increased the odds ratio of the possible depression group increased compared to the reference group, and especially the odds ratio was 2.73 times increased for work hours between 48-52 and 4.09 times increased for 60 hours or more and both were statistically significant. In comparing the low-mood group and possible depression group, as work hours increased the odds ratio increased to 1.73, 2.39, and 4.16 times, and all work hours from working 48-52 hours, 53-60 hours, and 60 hours or more were statistically significant. Multinomial logistic regression analysis also showed that among the reference group and possible group, the possible depression group was statistically significant as odds ratio increased to 2.94 times in working 53-60 hours, and 4.35 times in 60 hours or more. Long work hours have an adverse effect on emotional well-being. A more diversified research towards variables that affect long work hours and emotional well-being and how they interact with each

Flexible Work Hours and Other Job Factors in Parental Time with Children

Science.gov (United States)

Baxter, Jennifer

2011-01-01

Flexible working hours are typically seen to be advantageous to working parents, as the flexible hours more easily allow responsibilities of care and employment be balanced. But do flexible work hours actually mean that parents can spend more time with their children? This article explores this for parents of young children in Australia. The…

Globalization and working time: working hours and flexibility in Germany

NARCIS (Netherlands)

Burgoon, B.; Raess, D.

2009-01-01

This article challenges popular wisdom that economic globalization uniformly increases working time in industrialized countries. International investment and trade, they argue, have uneven effects for workplace bargaining over standard hours and over work-time flexibility, such as use of temporary

Stochastic modeling of hourly rainfall times series in Campania (Italy)

Science.gov (United States)

Giorgio, M.; Greco, R.

2009-04-01

Occurrence of flowslides and floods in small catchments is uneasy to predict, since it is affected by a number of variables, such as mechanical and hydraulic soil properties, slope morphology, vegetation coverage, rainfall spatial and temporal variability. Consequently, landslide risk assessment procedures and early warning systems still rely on simple empirical models based on correlation between recorded rainfall data and observed landslides and/or river discharges. Effectiveness of such systems could be improved by reliable quantitative rainfall prediction, which can allow gaining larger lead-times. Analysis of on-site recorded rainfall height time series represents the most effective approach for a reliable prediction of local temporal evolution of rainfall. Hydrological time series analysis is a widely studied field in hydrology, often carried out by means of autoregressive models, such as AR, ARMA, ARX, ARMAX (e.g. Salas [1992]). Such models gave the best results when applied to the analysis of autocorrelated hydrological time series, like river flow or level time series. Conversely, they are not able to model the behaviour of intermittent time series, like point rainfall height series usually are, especially when recorded with short sampling time intervals. More useful for this issue are the so-called DRIP (Disaggregated Rectangular Intensity Pulse) and NSRP (Neymann-Scott Rectangular Pulse) model [Heneker et al., 2001; Cowpertwait et al., 2002], usually adopted to generate synthetic point rainfall series. In this paper, the DRIP model approach is adopted, in which the sequence of rain storms and dry intervals constituting the structure of rainfall time series is modeled as an alternating renewal process. Final aim of the study is to provide a useful tool to implement an early warning system for hydrogeological risk management. Model calibration has been carried out with hourly rainfall hieght data provided by the rain gauges of Campania Region civil

Time spent sitting during and outside working hours in bus drivers: A pilot study.

Science.gov (United States)

Varela-Mato, Veronica; Yates, Thomas; Stensel, David J; Biddle, Stuart J H; Clemes, Stacy A

2016-06-01

This cross-sectional pilot study objectively measured sedentary and non-sedentary time in a sample of bus drivers from the East Midlands, United Kingdom. Participants wore an activPAL3 inclinometer for 7 days and completed a daily diary. Driver's blood pressure, heart rate, waist circumference and body composition were measured objectively at the outset. The proportions of time spent sedentary and non-sedentary were calculated during waking hours on workdays and non-workdays and during working-hours and non-working-hours on workdays. 28 (85% of those enrolled into the study) provided valid objective monitoring data (89.3% male, [median ± IQR] age: 45.2 ± 12.8 years, BMI 28.1 ± 5.8 kg/m(2)). A greater proportion of time was spent sitting on workdays than non-workdays (75% [724 ± 112 min/day] vs. 62% [528 ± 151 min/day]; p working-hours than non-working-hours (83% [417 ± 88 min/day] vs. 68% [307 ± 64 min/day]; p less than 3% of their overall time stepping. Bus drivers accumulate high levels of sitting time during working-hours and outside working-hours. Interventions are urgently needed in this at-risk group, which should focus on reducing sitting and increasing movement during breaks and increasing physical activity during leisure time to improve cardiovascular health.

Spending Time: The Impact of Hours Worked on Work-Family Conflict

Science.gov (United States)

Adkins, Cheryl L.; Premeaux, Sonya F.

2012-01-01

Scholars have long assumed that as workers spend more time at work fewer hours are available for their non-work lives leading to negative effects in both domains, and most studies examining the impact of work hours on work and life domains have supported this viewpoint. However, the majority of these studies have used one-dimensional measures of…

Efficacy of split hours part-time patching versus continuous hours part-time patching for treatment of anisometropic amblyopia in children: a pilot study.

Science.gov (United States)

Sachdeva, Virender; Mittal, Vaibhev; Kekunnaya, Ramesh; Gupta, Amit; Rao, Harsha L; Mollah, Joseph; Sontha, Anand; Gunturu, Rekha; Rao, B Venkateshwar

2013-07-01

To compare efficacy of 'split hours part-time patching' and 'continuous hours part-time patching' for the treatment of anisometropic amblyopia. We designed a prospective, interventional, non-randomised, comparative pilot study involving children between 4 and 11 years of age with anisometropic amblyopia who were treated with either continuous wear (Group A) or split hours part-time patching (Group B) as per parents wish, after appropriate discussion with the parents. Children were followed-up for the improvement in visual acuity and the compliance at each follow-up visit. 44 and 24 children were recruited in Group A and Group B, respectively (mean ± SD baseline BCVA of the amblyopic eye: 0.99 ± 0.32 and 0.95 ± 0.23 logMAR, respectively). BCVA (adjusted for baseline BCVA and age) at 3 months in Group A (0.59 ± 0.24) was comparable (p=0.08) with that in Group B (0.71 ± 0.24). This was same even at 6 months (0.51 ± 0.25 in Group A and 0.59 ± 0.25 in Group B, p=0.25). The improvement in BCVA at 3 months was also comparable (p=0.06) in Group A (0.39 ± 0.23) and Group B (0.26 ± 0.23). The improvement in BCVA at 6 months was also comparable (p=0.14) in Group A (0.47 ± 0.26) and Group B (0.37 ± 0.26). Both patching regimens lead to significant and comparable improvement in BCVA in anisometropic amblyopia up to 6 months of follow-up.

The Association between Long Working Hours and Self-Rated Health

Science.gov (United States)

2014-01-01

Objectives This study was conducted to determine the number of hours worked per week by full-time wage workers by using the data of the Korean Labor and Income Panel Study (KLIPS), which represents the domestic urban area household, and to determine the association between weekly working hours and the level of self-rated health. Methods We used data from the 11th KLIPS conducted in 2008. The subjects of this study were 3,699 full-time wage workers between the ages of 25 and 64 years. The association between weekly working hours and self-rated health was analyzed considering socio-demographic characteristics, work environment, and health-related behaviors. Results Among the workers, 29.7% worked less than 40 hours per week; 39.7%, more than 40 to 52 hours; 19.7%, more than 52 to 60 hours; and 10.9%, more than 60 hours per week. After controlling for socio-demographic variables, work environment-related variables, and health-related behavior variables, the odds ratio (OR) for poor self-rated health for the group working more than 40 hours and up to 52 hours was calculated to be 1.06 (95% confidence interval (CI), 0.89-1.27) when the group working less than 40 hours per week was considered the reference. The OR for the group working more than 60 hours was 1.42 (95% CI, 1.10-1.83) and that for the group working more than 52 hours and up to 60 hours was 1.07 (95% CI, 0.86-1.33). After stratification by gender and tenure, the OR of the female workers group and that of the group with a tenure of more than 1 year were found to be significantly higher than those of the other groups. Conclusions This study showed that workers working more than 60 hours per week have a significantly higher risk of poor self-rated health than workers working less than 40 hours per week. This effect was more obvious for the female workers group and the group with a tenure of more than 1 year. In the future, longitudinal studies may be needed to determine the association between long working

The Association between Long Working Hours and Self-Rated Health.

Science.gov (United States)

Song, Jun-Taek; Lee, Goeun; Kwon, Jongho; Park, Jung-Woo; Choi, Hyunrim; Lim, Sinye

2014-01-20

This study was conducted to determine the number of hours worked per week by full-time wage workers by using the data of the Korean Labor and Income Panel Study (KLIPS), which represents the domestic urban area household, and to determine the association between weekly working hours and the level of self-rated health. We used data from the 11th KLIPS conducted in 2008. The subjects of this study were 3,699 full-time wage workers between the ages of 25 and 64 years. The association between weekly working hours and self-rated health was analyzed considering socio-demographic characteristics, work environment, and health-related behaviors. Among the workers, 29.7% worked less than 40 hours per week; 39.7%, more than 40 to 52 hours; 19.7%, more than 52 to 60 hours; and 10.9%, more than 60 hours per week. After controlling for socio-demographic variables, work environment-related variables, and health-related behavior variables, the odds ratio (OR) for poor self-rated health for the group working more than 40 hours and up to 52 hours was calculated to be 1.06 (95% confidence interval (CI), 0.89-1.27) when the group working less than 40 hours per week was considered the reference. The OR for the group working more than 60 hours was 1.42 (95% CI, 1.10-1.83) and that for the group working more than 52 hours and up to 60 hours was 1.07 (95% CI, 0.86-1.33). After stratification by gender and tenure, the OR of the female workers group and that of the group with a tenure of more than 1 year were found to be significantly higher than those of the other groups. This study showed that workers working more than 60 hours per week have a significantly higher risk of poor self-rated health than workers working less than 40 hours per week. This effect was more obvious for the female workers group and the group with a tenure of more than 1 year. In the future, longitudinal studies may be needed to determine the association between long working hours and various health effects in Korean

Nursing work hours: individual needs versus working conditions.

Science.gov (United States)

Silva, Amanda Aparecida; Rotenberg, Lúcia; Fischer, Frida Marina

2011-12-01

To assess factors associated with professional and total hours of work (work + home) among nursing staff. Cross-sectional study conducted in a university hospital in the city of São Paulo, southeastern Brazil, between 2004 and 2005. A total of 696 workers (nurses, nurse technicians and aids), mostly women (87.8%) working day and/or night shifts, participated in the study. A self-administered questionnaire was used to collected information on demographic characteristics, and working and life conditions. Translated and adapted into Portuguese versions of the Job Stress Scale, Effort-reward imbalance, Short-Form-Health-related quality of life and the Work Ability Index were also administered. Logistic regression models were used for data analysis. Sole breadwinner, working night shifts and effort-reward imbalance were the variables associated with both professional (OR = 3.38, OR = 10.43, OR = 2.07, respectively) and total hours of work (OR = 1.57, OR = 3.37, OR = 2.75, respectively). There was no significant association between the variables related to hours of work and low Work Ability Index. Inadequate rest at home was statistically associated with professional (OR = 2.47) and total hours of work (OR = 1.48). Inadequate leisure time was significantly associated with professional hours of work (OR = 1.58) and barely associated with total hours of work (OR = 1.43). The sole breadwinner, working night shifts and effort-reward imbalance are variables that need to be further investigated in studies on work hours among nursing staff. These studies should explore workers' income and the relationship between effort and reward, taking into consideration gender issues.

Effects of Statin on Arrhythmia and Heart Rate Variability in Healthy Persons With 48-Hour Sleep Deprivation.

Science.gov (United States)

Chen, Wei Ren; Liu, Hong Bin; Sha, Yuan; Shi, Yang; Wang, Hao; Yin, Da Wei; Chen, Yun Dai; Shi, Xiang Min

2016-10-31

It has been reported that sleep deprivation is associated with cardiac autonomic disorder, inflammation, and oxidative stress. Statins have significant cardiovascular protective effects in patients with cardiovascular disease. This study aimed to investigate the protective effect of statins on arrhythmia and heart rate variability in young healthy persons after 48-hour sleep deprivation. This study enrolled 72 young healthy participants aged 26.5±3.5 years. All participants received 48-hour continuous ambulatory electrocardiogram monitoring. Arrhythmia, time, and frequency domain parameters were analyzed for all participants. The primary end point, low/high frequency ratio, was significantly lower in the statin group than in the control group (2.48±1.12 versus 3.02±1.23, Psleep deprivation, low frequency-the frequency of premature atrial complexes and premature ventricular complexes-was significantly decreased in the statin group compared with the control group (Psleep deprivation in the statin group compared with the control group (Psleep deprivation. This finding should be confirmed by larger scale trials. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02496962. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Comparison of anthropometric and training characteristics between recreational male marathoners and 24-hour ultramarathoners

Directory of Open Access Journals (Sweden)

Rüst CA

2012-10-01

Full Text Available Christoph Alexander Rüst,1 Beat Knechtle,1,2 Patrizia Knechtle,2 Thomas Rosemann11Institute of General Practice and for Health Services Research, University of Zurich, Zurich, 2Gesundheitszentrum St Gallen, St Gallen, SwitzerlandBackground: Of the anthropometry and training variables used to predict race performance in a 24-hour ultrarun, the personal best marathon time is the strongest predictor in recreational male 24-hour ultramarathoners. This finding raises the question of whether similarities exist between male recreational 24-hour ultramarathoners and male recreational marathoners.Methods: The association between age, anthropometric variables (ie, body mass, body height, body mass index, percent body fat, skeletal muscle mass, limb circumference, and skinfold thickness at the pectoral, mid axillary, triceps, subscapular, abdominal, suprailiac, front thigh, and medial calf sites, previous experience and training characteristics (ie, volume, speed, and personal best time, and race time for 79 male recreational 24-hour ultramarathoners and 126 male recreational marathoners was investigated using bivariate and multivariate analysis.Results: The 24-hour ultramarathoners were older (P < 0.05, had a lower circumference at both the upper arm (P < 0.05 and thigh (P < 0.01, and a lower skinfold thickness at the pectoral, axillary, and suprailiac sites (P < 0.05 compared with the marathoners. During training, the 24-hour ultramarathoners were running for more hours per week (P < 0.001 and completed more kilometers (P < 0.001, but were running slower (P < 0.01 compared with the marathoners. In the 24-hour ultramarathoners, neither anthropometric nor training variables were associated with kilometers completed in the race (P > 0.05. In the marathoners, percent body fat (P < 0.001 and running speed during training (P < 0.0001 were related to marathon race times.Conclusion: In summary, differences in anthropometric and training predictor variables do

Diastolic blood pressure variability in 24 hour-ABPM and outcomes of chronic kidney disease
.

Science.gov (United States)

Sahutoglu, Tuncay; Sakaci, Tamer

2018-04-10

Blood pressure variability (BPV) has been associated with increased morbidity and mortality. There are a few studies that reported worse outcomes of chronic kidney disease (CKD) with greater visit-to-visit BPV (VVV), but data with ambulatory blood pressure monitoring (ABPM) is scarce. Ambulatory hypertensive CKD (stage 2 - 4) patients (> 18 years old) with complete 24 hours of ABPM study (SpaceLabs), who were followed up between January 2012 and December 2016, were retrospectively analyzed for the baseline characteristics and outcomes of CKD. Coefficient of variation (CV) in diastolic blood pressure (DBP) was used as an index of BPV. Data of 191 patients (mean age 59.7 ± 12.4 years, 54.9% males, 42.1% diabetic, mean eGFR-EPI (Chronic Kidney Disease Epidemiology Collaboration) 51.7 ± 22.0 mL/min/1.73m2, mean follow-up 26.2 ± 10.4 months) were available for the analysis. On multivariate linear regression analysis, greater DBP-CV was associated with slower decline in eGFR-EPI per year (B -0.648, p = 0.000). Likewise, the hazard ratio (HR) for dialysis inception (occurred in 9.4%) was found significantly lower with increasing DBP-CV in unadjusted and fully adjusted Cox models (HR 0.730, 95% CI 0.618 - 0.861, p = 0.000, and HR 0.678, 95% CI 0.526 - 0.874, p = 0.003, respectively). These findings suggest that DBP variability in 24-hour ABPM may be a good prognostic factor for the outcomes of CKD. Further studies are needed to determine the impact of 24-hour ABPM BPV on CKD progression and its differences from VVV.
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Strategies for managing work/life interaction among women and men with variable and unpredictable work hours in retail sales in Québec, Canada.

Science.gov (United States)

Messing, Karen; Tissot, France; Couture, Vanessa; Bernstein, Stephanie

2014-01-01

Increasingly, work schedules in retail sales are generated by software that takes into account variations in predicted sales. The resulting variable and unpredictable schedules require employees to be available, unpaid, over extended periods. At the request of a union, we studied schedule preferences in a retail chain in Québec using observations, interviews, and questionnaires. Shift start times had varied on average by four hours over the previous week; 83 percent had worked at least one day the previous weekend. Difficulties with work/life balance were associated with schedules and, among women, with family responsibilities. Most workers wanted: more advance notice; early shifts; regular schedules; two days off in sequence; and weekends off. Choices varied, so software could be adapted to take preferences into account. Also, employers could give better advance notice and establish systems for shift exchanges. Governments could limit store hours and schedule variability while prolonging the minimum sequential duration of leave per week.

Globalization and working time: Work-place hours and flexibility in Germany

NARCIS (Netherlands)

Burgoon, B.; Raess, D.

2007-01-01

This paper examines how economic globalization affects work-place arrangements regulating working time in industrialized countries. Exposure to foreign direct investment and trade can have off-setting effects for work-place bargaining over standard hours and work-time flexibilization, and can be

The association between long work hours and leisure-time physical activity and obesity.

Science.gov (United States)

Cook, Miranda A; Gazmararian, Julie

2018-06-01

Obesity affects approximately one-third of all U.S. adults, presenting a large economic and public health burden. Long work hours may be contributing to the rising obesity problem by reducing time for physical activity, particularly for individuals working in sedentary occupations. This study sought to investigate the association between long work hours, leisure-time physical activity (LTPA), and obesity across levels of occupational activity in order to identify potentially vulnerable groups. Cross sectional analysis was performed in 2017 using data from the 2015 Georgia Behavioral Risk Factor Surveillance System and prevalence ratios were estimated across work hour and occupational activity groups. Ability to meet guidelines for LTPA did not differ significantly across work hour categories overall. Those working in low activity occupations were more likely to meet aerobic guidelines for LTPA compared to those in intermediate and high activity occupations (χ 2 : 19.3; P -value: work hours on obesity risk and meeting aerobic guidelines are significantly different across OA categories, indicating OA to be an effect modifier of the relationship between long work hours and obesity (χ 2 : 13.33; P -value: working long hours were found to be at the greatest risk for obesity. Further research is required to better understand the mechanisms impacting the relationship between long work hours, domains of physical activity, and obesity risk as well as to identify effective intervention and prevention programs for employees in intermediate activity occupations.

The association between long work hours and leisure-time physical activity and obesity

Directory of Open Access Journals (Sweden)

Miranda A. Cook

2018-06-01

Full Text Available Obesity affects approximately one-third of all U.S. adults, presenting a large economic and public health burden. Long work hours may be contributing to the rising obesity problem by reducing time for physical activity, particularly for individuals working in sedentary occupations. This study sought to investigate the association between long work hours, leisure-time physical activity (LTPA, and obesity across levels of occupational activity in order to identify potentially vulnerable groups. Cross sectional analysis was performed in 2017 using data from the 2015 Georgia Behavioral Risk Factor Surveillance System and prevalence ratios were estimated across work hour and occupational activity groups. Ability to meet guidelines for LTPA did not differ significantly across work hour categories overall. Those working in low activity occupations were more likely to meet aerobic guidelines for LTPA compared to those in intermediate and high activity occupations (χ2: 19.3; P-value: <0.01. Results of interaction assessment demonstrate that the effects of work hours on obesity risk and meeting aerobic guidelines are significantly different across OA categories, indicating OA to be an effect modifier of the relationship between long work hours and obesity (χ2: 13.33; P-value: <0.001; χ2: 4.42; P-value: <0.05. Employees in intermediate activity occupations working long hours were found to be at the greatest risk for obesity. Further research is required to better understand the mechanisms impacting the relationship between long work hours, domains of physical activity, and obesity risk as well as to identify effective intervention and prevention programs for employees in intermediate activity occupations. Keywords: Physical activity, Obesity, Occupation, Long work hours

Hours of Work and Gender Identity : Does Part-time Work make the Family Happier?

OpenAIRE

Booth, A.L.; van Ours, J.C.

2006-01-01

Taking into account inter-dependence within the family, we investigate the relationship between part-time work and happiness. We use panel data from the new Household, Income and Labor Dynamics in Australia Survey. Our analysis indicates that part-time women are more satisfied with working hours than full-time women. Partnered women's life satisfaction is increased if their partners work full-time. Male partners' life satisfaction is unaffected by their partners' market hours but is increased...

[Travel time and distances to Norwegian out-of-hours casualty clinics].

Science.gov (United States)

Raknes, Guttorm; Morken, Tone; Hunskår, Steinar

2014-11-01

Geographical factors have an impact on the utilisation of out-of-hours services. In this study we have investigated the travel distance to out-of-hours casualty clinics in Norwegian municipalities in 2011 and the number of municipalities covered by the proposed recommendations for secondary on-call arrangements due to long distances. We estimated the average maximum travel times and distances in Norwegian municipalities using a postcode-based method. Separate analyses were performed for municipalities with a single, permanently located casualty clinic. Altogether 417 out of 430 municipalities were included. We present the median value of the maximum travel times and distances for the included municipalities. The median maximum average travel distance for the municipalities was 19 km. The median maximum average travel time was 22 minutes. In 40 of the municipalities (10 %) the median maximum average travel time exceeded 60 minutes, and in 97 municipalities (23 %) the median maximum average travel time exceeded 40 minutes. The population of these groups comprised 2 % and 5 % of the country's total population respectively. For municipalities with permanent emergency facilities(N = 316), the median average flight time 16 minutes and median average distance 13 km.. In many municipalities, the inhabitants have a long average journey to out-of-hours emergency health services, but seen as a whole, the inhabitants of these municipalities account for a very small proportion of the Norwegian population. The results indicate that the proposed recommendations for secondary on-call duty based on long distances apply to only a small number of inhabitants. The recommendations should therefore be adjusted and reformulated to become more relevant.

Relationship between 24- hour Holter variables, chest discomfort and syncope: Does age matter?

Directory of Open Access Journals (Sweden)

Samir Kanti Saha

2013-01-01

Full Text Available One hundred and forty four ambulatory, non-emergent human subjects from 20-88 years of age were investigated following routine 24 hour Holter monitoring referred by primary and tertiary care centers primarily for evaluation of palpitations and syncope. The patients were grouped into 3 different age categories: A 20-59 years of age (16%, B 60-69 years of age (26.4% and C > 70 years of age (57.6%. Heart rate profile, RR intervals, symptoms, frequency of premature supra ventricular and ventricular complexes were registered. The data show that though the occurrence and frequency of premature atrial and ventricular contractions over a period of 24 hours did not differ between the groups, the younger subjects documented more subjective discomforts during the Holter monitoring. Extra-systoles in excess of 1000 beats / 24 hour occured incessantly throughout the registration. Patients with syncope and those without did not differ as regards the Holter variables. However, subjects with atrial fibrillation had acceptable rate control and had significantly lower incidence of syncope than those with sinus rhythm. The findings suggest that in a county setting, Holter monitoring for evaluation of syncope may not be the first hand mode of investigation in a non emergent setting. On the contrary, the modality appears to be valuable for monitoring patients with atrial fibrillation. Even mild symptoms in the elderly population may warrant closer clinical follow up to prevent cardiac events and/or syncope leading to serious physical injury.

Long work hours and obesity in Korean adult workers.

Science.gov (United States)

Jang, Tae-Won; Kim, Hyoung-Ryoul; Lee, Hye-Eun; Myong, Jun-Pyo; Koo, Jung-Wan

2014-01-01

The present study was designed to identify the association between work hours and obesity in Korean adult manual and nonmanual workers, and to determine whether there is a gender difference in this association. The study was conducted using Korean National Health and Nutrition Examination Survey data collected between 2007 and 2010. Individuals aged below 25 or over 64 years, pregnant women, part-time workers, soldiers, housewives and students were excluded. The total number of individuals included in the analysis was 8,889 (5,241 male and 3,648 female subjects). The outcome variable was obesity, defined as body mass index ≥25 kg/m(2). Variables considered in the model were age, education, income, marital status, alcohol drinking, smoking, daily energy intake, physical activity, sleep hours per day, the type of job, work hours, and work schedule. Work hours were categorized as 60 hours per week. In the multiple SURVEYLOGISTIC regression analyses, the adjusted odds ratio of obesity for long work hours (>60 hours per week) in male manual workers was 1.647 (95% confidence interval 1.262-2.151). Long work hours did not significantly increase the odds ratio for obesity in male nonmanual workers and female manual and nonmanual workers. More than 60 work hours per week increased the risk of obesity in Korean male manual workers. This result might be helpful in preventing obesity in Korean adult workers, especially male manual workers.

Increasing part-time working hours in the Netherlands. Identifying policy recommendations through Group Model Building

NARCIS (Netherlands)

Bleijenbergh, I.L.; Fokkinga, B.L.A.

2013-01-01

With 73% of women and 19% of men working part-time,the Netherlands is known as the champion of part-time work. In order to increase especially the working hours of women with small part-time jobs (less than 20 hours per week) the Dutch government installed a thinktank of employers, employees

New Approach To Hour-By-Hour Weather Forecast

Science.gov (United States)

Liao, Q. Q.; Wang, B.

2017-12-01

Fine hourly forecast in single station weather forecast is required in many human production and life application situations. Most previous MOS (Model Output Statistics) which used a linear regression model are hard to solve nonlinear natures of the weather prediction and forecast accuracy has not been sufficient at high temporal resolution. This study is to predict the future meteorological elements including temperature, precipitation, relative humidity and wind speed in a local region over a relatively short period of time at hourly level. By means of hour-to-hour NWP (Numeral Weather Prediction)meteorological field from Forcastio (https://darksky.net/dev/docs/forecast) and real-time instrumental observation including 29 stations in Yunnan and 3 stations in Tianjin of China from June to October 2016, predictions are made of the 24-hour hour-by-hour ahead. This study presents an ensemble approach to combine the information of instrumental observation itself and NWP. Use autoregressive-moving-average (ARMA) model to predict future values of the observation time series. Put newest NWP products into the equations derived from the multiple linear regression MOS technique. Handle residual series of MOS outputs with autoregressive (AR) model for the linear property presented in time series. Due to the complexity of non-linear property of atmospheric flow, support vector machine (SVM) is also introduced . Therefore basic data quality control and cross validation makes it able to optimize the model function parameters , and do 24 hours ahead residual reduction with AR/SVM model. Results show that AR model technique is better than corresponding multi-variant MOS regression method especially at the early 4 hours when the predictor is temperature. MOS-AR combined model which is comparable to MOS-SVM model outperform than MOS. Both of their root mean square error and correlation coefficients for 2 m temperature are reduced to 1.6 degree Celsius and 0.91 respectively. The

Telework: timesaving or time-consuming? An investigation into actual working hours

NARCIS (Netherlands)

Peters, P.; Wetzels, C.; Tijdens, K.

2008-01-01

This paper aims to clarify the relationship between telework and the actual time employees put into their jobs. One of the reported threats to teleworkers’ personal lives is that in order to finish their work, they not only use up saved commuting time, but also part of their non-working hours, even

77 FR 44059 - Federal Acquisition Regulation; Payments Under Time-and-Materials and Labor-Hour Contracts

Science.gov (United States)

2012-07-26

... receive more frequent payments than every two weeks. The Contractor shall substantiate vouchers (including...] RIN 9000-AM01 Federal Acquisition Regulation; Payments Under Time-and-Materials and Labor-Hour... the authorization to use time-and-materials and labor-hour contract payment requirements. DATES...

The effects of variable renewable electricity on energy efficiency and full load hours of fossil-fired power plants in the European Union

NARCIS (Netherlands)

de Groot, Mats; Crijns-Graus, Wina; Harmsen, Robert

2017-01-01

This study focused on the effects of variable renewable electricity (VRE) on full load hours and energy efficiency of fossil-fired power generation in the European Union from 1990-2014. Member states were aggregated into three groups based on the level of VRE penetration. Average full load hours are

Activity, time, and subjective happiness: An analysis based on an hourly web survey

OpenAIRE

Sakawa, Hideaki; Ohtake, Fumio; Tsutsui, Yoshiro

2015-01-01

This paper investigates how people's happiness depends on their current activities and on time. We conducted an hourly web survey, in which 70 students reported their happiness every hour on one day every month from December 2006 to February 2008. This method is an extension of the experience sampling method (ESM), since it uses mobile phones and personal computers. Our new method has the same strength of ESM in that it can measure real-time happiness data and thus avoid reflection and memory...

Variability of OH rotational temperatures on time scales from hours to 15 years by kinetic temperature variations, emission layer changes, and non-LTE effects

Science.gov (United States)

Noll, Stefan

2016-07-01

Rotational temperatures derived from hydroxyl (OH) line emission are frequently used to study atmospheric temperatures at altitudes of about 87 km. While the measurement only requires intensities of a few bright lines of an OH band, the interpretation can be complicated. Ground-based temperatures are averages for the entire, typically 8 km wide emission layer. Variations in the rotational temperature are then caused by changes of the kinetic temperature and the OH emission profile. The latter can also be accompanied by differences in the layer-averaged efficiency of the thermalisation of the OH rotational level populations. Since this especially depends on the frequency of collisions with O_2, which is low at high altitudes, the non-local thermodynamic equilibrium (non-LTE) contribution to the measured temperatures can be significant and variable. In order to understand the impact of the different sources of OH rotational temperature variations from time scales of hours to a solar cycle, we have studied spectra from the astronomical echelle spectrographs X-shooter and UVES located at Cerro Paranal in Chile. While the X-shooter data spanning 3.5 years allowed us to measure temperatures for 25 OH and two O_2 bands, the UVES spectra cover no more than 10 OH bands simultaneously but a period of about 15 years. These data have been complemented by kinetic temperature and OH and O_2 emission profiles from the multi-channel radiometer SABER on the TIMED satellite. Taking the O_2 and SABER kinetic temperatures as reference and considering the different band-dependent emission profiles, we could evaluate the contribution of non-LTE effects to the measured OH rotational temperatures depending on line set, band, and time. Non-LTE contributions are significant for most bands and can exceed 10 K. The amplitudes of their average nocturnal and seasonal variation are of the order of 1 to 2 K.

Flexible work in call centres: Working hours, work-life conflict & health.

Science.gov (United States)

Bohle, Philip; Willaby, Harold; Quinlan, Michael; McNamara, Maria

2011-01-01

Call-centre workers encounter major psychosocial pressures, including high work intensity and undesirable working hours. Little is known, however, about whether these pressures vary with employment status and how they affect work-life conflict and health. Questionnaire data were collected from 179 telephone operators in Sydney, Australia, of whom 124 (69.3%) were female and 54 (30.2%) were male. Ninety-three (52%) were permanent full-time workers, 37 (20.7%) were permanent part-time, and 49 (27.4%) were casual employees. Hypothesised structural relationships between employment status, working hours and work organisation, work-life conflict and health were tested using partial least squares modelling in PLS (Chin, 1998). The final model demonstrated satisfactory fit. It supported important elements of the hypothesised structure, although four of the proposed paths failed to reach significance and the fit was enhanced by adding a path. The final model indicated that casual workers reported more variable working hours which were relatively weakly associated with greater dissatisfaction with hours. The interaction of schedule control and variability of hours also predicted dissatisfaction with hours. Conversely, permanent workers reported greater work intensity, which was associated with both lower work schedule control and greater work-life conflict. Greater work-life conflict was associated with more fatigue and psychological symptoms. Labour market factors and the undesirability of longer hours in a stressful, high-intensity work environment appear to have contributed to the results. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

How extreme is extreme hourly precipitation?

Science.gov (United States)

Papalexiou, Simon Michael; Dialynas, Yannis G.; Pappas, Christoforos

2016-04-01

The importance of accurate representation of precipitation at fine time scales (e.g., hourly), directly associated with flash flood events, is crucial in hydrological design and prediction. The upper part of a probability distribution, known as the distribution tail, determines the behavior of extreme events. In general, and loosely speaking, tails can be categorized in two families: the subexponential and the hyperexponential family, with the first generating more intense and more frequent extremes compared to the latter. In past studies, the focus has been mainly on daily precipitation, with the Gamma distribution being the most popular model. Here, we investigate the behaviour of tails of hourly precipitation by comparing the upper part of empirical distributions of thousands of records with three general types of tails corresponding to the Pareto, Lognormal, and Weibull distributions. Specifically, we use thousands of hourly rainfall records from all over the USA. The analysis indicates that heavier-tailed distributions describe better the observed hourly rainfall extremes in comparison to lighter tails. Traditional representations of the marginal distribution of hourly rainfall may significantly deviate from observed behaviours of extremes, with direct implications on hydroclimatic variables modelling and engineering design.

The Effect of Fatherhood on Employment Hours: Variation by Birth Timing, Marriage and Coresidence.

Science.gov (United States)

Weinshenker, Matthew

2015-01-01

Drawing on the life course paradigm, I assess how the effect of fatherhood on employment hours varies by age of becoming a parent and time elapsed since the birth. Using the National Longitudinal Survey of Youth - 1979 Cohort from 1979 to 2002 (N = 28,514 observations), separate effects are estimated based on fathers' marital status and co-residence with own children. Only unmarried men who became fathers before 24 work longer hours immediately after a first birth, but in the long run, most early fathers work fewer hours as a result of parenthood. Over time, unmarried but coresident men who became fathers between 24 and 29 increase their hours, as do married, coresident men who delayed fatherhood until 30 or older. However, the latter increase is moderated by support for egalitarian gender roles. The findings shed light on the contemporary transition to adulthood and on men's work-family balance.

Neighborhood walkability, income, and hour-by-hour physical activity patterns.

Science.gov (United States)

Arvidsson, Daniel; Eriksson, Ulf; Lönn, Sara Larsson; Sundquist, Kristina

2013-04-01

This study aimed to investigate both the mean daily physical activity and the hour-by-hour physical activity patterns across the day using accelerometry and how they are associated with neighborhood walkability and individual income. Moderate physical activity (MPA) was assessed by accelerometry in 2252 adults in the city of Stockholm, Sweden. Neighborhood walkability (residential density, street connectivity, and land use mix) was objectively assessed within 1000m network buffers around the participants' residence and individual income was self-reported. Living in a high walkability neighborhood was associated with more mean daily MPA compared with living in a low walkability neighborhood on weekdays and weekend days. Hour-by-hour analyses showed that this association appeared mainly in the afternoon/early evening during weekdays, whereas it appeared across the middle of the day during weekend days. Individual income was associated with mean daily MPA on weekend days. On weekdays, the hour-by-hour analyses showed that high income was associated with more MPA around noon and in late afternoon/early evening, whereas low income was associated with more MPA at the hours before noon and in the early afternoon. During the weekend, high income was more consistently associated with higher MPA. Hour-by-hour accelerometry physical activity patterns provides a more comprehensive picture of the associations between neighborhood walkability and individual income and physical activity and the variability of these associations across the day.

Bullying Behavior, Parents' Work Hours and Early Adolescents' Perceptions of Time Spent with Parents

Science.gov (United States)

Christie-Mizell, C. Andre; Keil, Jacqueline M.; Laske, Mary Therese; Stewart, Jennifer

2011-01-01

This research investigates the relationships among bullying behavior, mother's and father's work hours, and early adolescents' perceptions of whether they spend sufficient time with their parents. In cross-sectional models, we find maternal work hours are modestly associated with increases in bullying behavior. However, in more rigorous change…

Variability of interconnected wind plants: correlation length and its dependence on variability time scale

Science.gov (United States)

St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

2015-04-01

The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

[Twenty-four hour time and frequency domain variability of systolic blood pressure and heart rate in an experimental model of arterial hypertension plus obesity].

Science.gov (United States)

Pelat, M; Verwaerde, P; Lazartiques, E; Cabrol, P; Galitzky, J; Berlan, M; Montastruc, J L; Senard, J M

1998-08-01

Modifications of heart rate (HR) and systolic blood pressure (SBP) variabilities (V) have been reported in the human syndrome arterial hypertension plus insulin-resistance. The aim of this study was to characterize the 24 h SBPV and HRV in both time and frequency domains during weight increase in dogs fed ad libitum with a high fat diet. Implantable transmitter units for measurement of blood pressure and heart rate were surgically implanted in five beagle male dogs. BP and HR were continuously recorded using telemetric measurements during 24 hours, before and after 6 and 9 weeks of hypercaloric diet in quiet animals submitted to a 12h light-dark cycle. To study nychtemeral cycle of SBP and HR, two periods were chosen: day (from 6.00 h to 19.00 h) and night (from 23.00 h to 6.00 h). Spontaneous baroreflex efficiency was measured using the sequence method. Spectral variability of HR and SBP was analyzed using a fast Fourier transformation on 512 consecutive values and normalized units of low (LF: 50-150 mHz, reflecting sympathetic activity) and high (HF: respiratory rate +/- 50 mHz, reflecting parasympathetic activity) frequency bands were calculated. The energy of total spectrum (from 0.004 to 1 Hz) was also studied. Body weight (12.4 +/- 0.9 vs 14.9 +/- 0.9 kg, p vs 147 +/- 1 mmHg, p vs night: 71 +/- 1 bpm) but not after 9 weeks (day: 91 +/- 4 bpm ; night: 86 +/- 2 bpm). Concomitantly, the efficiency of spontaneous baroreflex decreased at 6 weeks (36 +/- 1 vs 42 +/- 2 mmHg/ms, p energy of HRV was found after 6 but not after 9 weeks. LF energy of SBPV was increased at 6 but not at 9 weeks (table). [table: see text] In conclusion, this study shows that an hyperlipidic and hypercaloric diet induces transient variations in autonomic nervous system activity which could be the physiopathological link between obesity, insulin-resistance and arterial hypertension.

Delay of constant light-induced persistent vaginal estrus by 24-hour time cues in rats.

Science.gov (United States)

Weber, A L; Adler, N T

1979-04-20

The normal ovarian cycle of female rats is typically replaced by persistent estrus when these animals are housed under constant light. Evidence presented here shows that the maintenance of periodicity in the environment can at least delay (if not prevent) the photic induction of persistent vaginal estrus. Female rats in constant light were exposed to vaginal smearing at random times or at the same time every day. In another experiment, female rats were exposed to either constant bright light, constant dim light, or a 24-hour photic cycle of bright and dim light. The onset of persistent vaginal estrus was delayed in rats exposed to 24-hour time cues even though the light intensities were the same as or greater than those for the aperiodic control groups. The results suggest that the absence of 24-hour time cues in constant light contributes to the induction of persistent estrus.

Stochastic generation of hourly wind speed time series

International Nuclear Information System (INIS)

Shamshad, A.; Wan Mohd Ali Wan Hussin; Bawadi, M.A.; Mohd Sanusi, S.A.

2006-01-01

In the present study hourly wind speed data of Kuala Terengganu in Peninsular Malaysia are simulated by using transition matrix approach of Markovian process. The wind speed time series is divided into various states based on certain criteria. The next wind speed states are selected based on the previous states. The cumulative probability transition matrix has been formed in which each row ends with 1. Using the uniform random numbers between 0 and 1, a series of future states is generated. These states have been converted to the corresponding wind speed values using another uniform random number generator. The accuracy of the model has been determined by comparing the statistical characteristics such as average, standard deviation, root mean square error, probability density function and autocorrelation function of the generated data to those of the original data. The generated wind speed time series data is capable to preserve the wind speed characteristics of the observed data

Additive measures of travel time variability

DEFF Research Database (Denmark)

Engelson, Leonid; Fosgerau, Mogens

2011-01-01

This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference...... parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway....

49 CFR 398.6 - Hours of service of drivers; maximum driving time.

Science.gov (United States)

2010-10-01

... REGULATIONS TRANSPORTATION OF MIGRANT WORKERS § 398.6 Hours of service of drivers; maximum driving time. No person shall drive nor shall any motor carrier permit or require a driver employed or used by it to drive...

A space-time hybrid hourly rainfall model for derived flood frequency analysis

Directory of Open Access Journals (Sweden)

U. Haberlandt

2008-12-01

Full Text Available For derived flood frequency analysis based on hydrological modelling long continuous precipitation time series with high temporal resolution are needed. Often, the observation network with recording rainfall gauges is poor, especially regarding the limited length of the available rainfall time series. Stochastic precipitation synthesis is a good alternative either to extend or to regionalise rainfall series to provide adequate input for long-term rainfall-runoff modelling with subsequent estimation of design floods. Here, a new two step procedure for stochastic synthesis of continuous hourly space-time rainfall is proposed and tested for the extension of short observed precipitation time series.

First, a single-site alternating renewal model is presented to simulate independent hourly precipitation time series for several locations. The alternating renewal model describes wet spell durations, dry spell durations and wet spell intensities using univariate frequency distributions separately for two seasons. The dependence between wet spell intensity and duration is accounted for by 2-copulas. For disaggregation of the wet spells into hourly intensities a predefined profile is used. In the second step a multi-site resampling procedure is applied on the synthetic point rainfall event series to reproduce the spatial dependence structure of rainfall. Resampling is carried out successively on all synthetic event series using simulated annealing with an objective function considering three bivariate spatial rainfall characteristics. In a case study synthetic precipitation is generated for some locations with short observation records in two mesoscale catchments of the Bode river basin located in northern Germany. The synthetic rainfall data are then applied for derived flood frequency analysis using the hydrological model HEC-HMS. The results show good performance in reproducing average and extreme rainfall characteristics as well as in

Real-time continuous glucose monitoring shows high accuracy within 6 hours after sensor calibration: a prospective study.

Directory of Open Access Journals (Sweden)

Xiao-Yan Yue

Full Text Available Accurate and timely glucose monitoring is essential in intensive care units. Real-time continuous glucose monitoring system (CGMS has been advocated for many years to improve glycemic management in critically ill patients. In order to determine the effect of calibration time on the accuracy of CGMS, real-time subcutaneous CGMS was used in 18 critically ill patients. CGMS sensor was calibrated with blood glucose measurements by blood gas/glucose analyzer every 12 hours. Venous blood was sampled every 2 to 4 hours, and glucose concentration was measured by standard central laboratory device (CLD and by blood gas/glucose analyzer. With CLD measurement as reference, relative absolute difference (mean±SD in CGMS and blood gas/glucose analyzer were 14.4%±12.2% and 6.5%±6.2%, respectively. The percentage of matched points in Clarke error grid zone A was 74.8% in CGMS, and 98.4% in blood gas/glucose analyzer. The relative absolute difference of CGMS obtained within 6 hours after sensor calibration (8.8%±7.2% was significantly less than that between 6 to 12 hours after calibration (20.1%±13.5%, p<0.0001. The percentage of matched points in Clarke error grid zone A was also significantly higher in data sets within 6 hours after calibration (92.4% versus 57.1%, p<0.0001. In conclusion, real-time subcutaneous CGMS is accurate in glucose monitoring in critically ill patients. CGMS sensor should be calibrated less than 6 hours, no matter what time interval recommended by manufacturer.

Associations between hours worked, symptoms and health resource utilization among full-time male Japanese workers.

Science.gov (United States)

Sato, Keiko; Yamazaki, Shin; Hayashino, Yasuaki; Takegami, Misa; Tokuda, Yasuharu; Takahashi, Osamu; Shimbo, Takuro; Hinohara, Shigeaki; Fukui, Tsuguya; Fukuhara, Shunichi

2011-01-01

To investigate the association between hours worked, symptoms experienced, and health resource utilization. Data were collected from a nationally representative sample of households in Japan. We studied full-time male workers aged 18-65 yr who worked 100 h or more per month. First, we examined the association between hours worked and symptoms experienced. Second, we examined the association between hours worked and the type of health resource utilized, such as physician visits, over-the-counter (OTC) medication use, dietary supplement use, and complementary and alternative medicine (CAM) provider visits. We used a multivariable negative binominal model in each analysis. Of the 762 male workers, 598 reported experiencing symptoms at least once a month. We categorized participants based on the number of hours worked per month (h/mo): 100-200 h/mo, 201-250 h/mo, and over 250 h/mo. Compared with those working 201-250 h/mo, those working 100-200 h/mo had more frequent physician visits (rate ratio:1.67, 95% CI: 1.17 to 2.38) and those working over 250 h/mo had significantly lower rates of CAM provider visits and tended to use dietary supplements for symptoms. Participants who worked 201-250 h/mo used OTC medication most frequently. No significant association was observed between the number of hours worked and number of symptoms experienced. The more hours worked by full-time male workers, the more likely they were to use health resources that had a lower time requirement. Greater attention should be paid to patterns of health resource utilization among workers and their consequent influence on long-term health status.

Poorer Health – Shorter Hours? Health and Flexibility of Hours of Work

OpenAIRE

Geyer, Johannes; Myck, Michal

2010-01-01

We analyse the role of health in determining the difference between desired and actual hours of work in a sample of German men using the Socio-Economic Panel Data for years 1996-2007. The effects of both self-assessed health and legal disability status are examined. About 60% of employees report working more than they would wish with the mean difference of -3.9 hours/week. We estimate static and dynamic model specifications allowing for auto-regressive nature of the dependent variable and tes...

Commuters’ valuation of travel time variability in Barcelona

OpenAIRE

Javier Asensio; Anna Matas

2007-01-01

The value given by commuters to the variability of travel times is empirically analysed using stated preference data from Barcelona (Spain). Respondents are asked to choose between alternatives that differ in terms of cost, average travel time, variability of travel times and departure time. Different specifications of a scheduling choice model are used to measure the influence of various socioeconomic characteristics. Our results show that travel time variability.

The Effect of Working Hours on Health

OpenAIRE

Berniell, Maria Ines; Bietenbeck, Jan

2017-01-01

Does working time causally affect workers' health? We study this question in the context of a French reform which reduced the standard workweek from 39 to 35 hours, at constant earnings. Our empirical analysis exploits variation in the adoption of this shorter workweek across employers, which is mainly driven by institutional features of the reform and thus exogenous to workers' health. Difference-in-differences and lagged dependent variable regressions reveal a negative effect of working hou...

The generation of hourly diffuse irradiation: A model from the analysis of the fluctuation of global irradiance series

International Nuclear Information System (INIS)

Posadillo, R.; Lopez Luque, R.

2010-01-01

An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction k d and the hourly clearness index k t , has concluded that k t is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse component for a specific clearness index under partly cloudy sky conditions has led to analyzing how the variability in the instantaneous clearness index influences this dispersion. The data sets correspond to 10 years of hourly and instantaneous value records of global and diffuse radiation collected in Cordoba, Spain. In addition to the inclusion of the sine of solar elevation as a variable into the k d -k t correlations, this model propose the inclusion of others parameters related to the variability in the normalized clearness index within an hour and with the fluctuations presented by the time series of the instantaneous values of that index. Also presented is the implementation of an algorithm permitting both the determination of the hourly diffuse irradiation and the discrimination between the different sky conditions in those situations known by the designation partly cloudy sky.

EFFECTS OF LONG-TIME COMMUTING AND LONG-HOUR WORKING ON LIFESTYLE AND MENTAL HEALTH AMONG SCHOOL TEACHERS IN TOKYO, JAPAN.

Science.gov (United States)

Nomoto, Marino; Hara, Akiko; Kikuchi, Kimiyo

2015-06-01

The objective of this study was to investigate the effects of long-time commuting and long-hour working on lifestyle including sleeping, physical exercise, breakfast, smoking, alcohol intake and mental health. In this cross-sectional study, data were collected from 146 school teachers in Tokyo. The binary associations of commuting time and working hours with lifestyle, mental stress measured by the General Health Questionnaire (GHQ) and stress coping measured by the Sense of Coherence (SOC) scores were examined. The Chi-square test was used for statistical analyses. Our results indicated that the mean commuting time and working hours per week of the respondents were 42.1 (SD 22.5) minutes and 50.4 (SD 8.6) hours, respectively. Longer commuting time was significantly associated with shorter working hours (p = 0.023), less physical exercise (p hours (p = 0.001). Longer working hours were significantly associated with more frequent working on holidays (p = 0.001), higher SOC scores (p = 0.001) and more smoking (p = 0.028). The negative association between GHQ and SOC scores was also significant (p long-time commuters were more likely to sleep less, exercise less and work less long. Long-hour workers were more likely to commute shorter, work on holidays more frequently, smoke more and their stress coping potentials were higher. Some kinds of strategies are required to improve the healthy lifestyle for long-time com- muters or long-hour workers. Key words: stress; stress coping; general health questionnaire; sense of coherence

Reciprocal Interaction of 24-Hour Blood Pressure Variability and Systolic Blood Pressure on Outcome in Stroke Thrombolysis.

Science.gov (United States)

Kellert, Lars; Hametner, Christian; Ahmed, Niaz; Rauch, Geraldine; MacLeod, Mary J; Perini, Francesco; Lees, Kennedy R; Ringleb, Peter A

2017-07-01

Significance and management of blood pressure (BP) changes in acute stroke care are unclear. Here, we aimed to investigate the impact of 24-hour BP variability (BPV) on outcome in patients with acute ischemic stroke treated with intravenous thrombolysis. From the Safe Implementation of Treatment in Stroke International Stroke Thrombolysis registry, 28 976 patients with documented pre-treatment systolic BP at 2 and 24 hours were analyzed. The primary measure of BP variability was successive variability. Data were preprocessed using coarsened exact matching. We assessed early neurological improvement, symptomatic intracerebral hemorrhage (SICH), and long-term functional outcome (modified Rankin Scale [mRS] at 90 days) by binary and ordinal regression analyses. Attempts to explain successive variation for analysis of BPV with patients characteristics at admission found systolic BP (5.5% variance) to be most influential, yet 92% of BPV variance remained unexplained. Independently from systolic BP, successive variation for analysis of BPV was associated with poor functional outcome mRS score of 0 to 2 (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90-0.98), disadvantage across the shift of mRS (OR, 1.04; 95% CI, 1.01-1.08), mortality (OR, 1.10; 95% CI, 1.01-1.08), SICH SITS (OR, 1.14; 95% CI, 1.06-1.23), and SICH ECASS (OR, 1.24; 95% CI, 1.10-1.40; ECASS [European Cooperative Acute Stroke Study 2]). Analyzing successive variation for analysis of BPV as a function of pre-treatment, systolic BP significantly improved the prediction of functional outcome (mRS score of 0-1, mRS score of 0-2, neurological improvement, mRS-shift: all P interaction accounting for pre-treatment BP and the acute BP course (ie, BPV) to achieve best possible outcome for the patient. © 2017 American Heart Association, Inc.

Hours of Work and Gender Identity : Does Part-time Work make the Family Happier?

NARCIS (Netherlands)

Booth, A.L.; van Ours, J.C.

2006-01-01

Taking into account inter-dependence within the family, we investigate the relationship between part-time work and happiness.We use panel data from the new Household, Income and Labor Dynamics in Australia Survey.Our analysis indicates that part-time women are more satisfied with working hours than

Spatial and temporal variability of interhemispheric transport times

Science.gov (United States)

Wu, Xiaokang; Yang, Huang; Waugh, Darryn W.; Orbe, Clara; Tilmes, Simone; Lamarque, Jean-Francois

2018-05-01

The seasonal and interannual variability of transport times from the northern midlatitude surface into the Southern Hemisphere is examined using simulations of three idealized age tracers: an ideal age tracer that yields the mean transit time from northern midlatitudes and two tracers with uniform 50- and 5-day decay. For all tracers the largest seasonal and interannual variability occurs near the surface within the tropics and is generally closely coupled to movement of the Intertropical Convergence Zone (ITCZ). There are, however, notable differences in variability between the different tracers. The largest seasonal and interannual variability in the mean age is generally confined to latitudes spanning the ITCZ, with very weak variability in the southern extratropics. In contrast, for tracers subject to spatially uniform exponential loss the peak variability tends to be south of the ITCZ, and there is a smaller contrast between tropical and extratropical variability. These differences in variability occur because the distribution of transit times from northern midlatitudes is very broad and tracers with more rapid loss are more sensitive to changes in fast transit times than the mean age tracer. These simulations suggest that the seasonal-interannual variability in the southern extratropics of trace gases with predominantly NH midlatitude sources may differ depending on the gases' chemical lifetimes.

Travel time variability and rational inattention

DEFF Research Database (Denmark)

Fosgerau, Mogens; Jiang, Gege

2017-01-01

This paper sets up a rational inattention model for the choice of departure time for a traveler facing random travel time. The traveler chooses how much information to acquire about the travel time out-come before choosing departure time. This reduces the cost of travel time variability compared...

The generation of hourly diffuse irradiation: A model from the analysis of the fluctuation of global irradiance series

Energy Technology Data Exchange (ETDEWEB)

Posadillo, R.; Lopez Luque, R. [Grupo de Investigacion de Fisica para las Energias y Recursos Renovables, Dpto. de Fisica Aplicada, UCO, Edificio C2 Campus de Rabanales, 14071 Cordoba (Spain)

2010-04-15

An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction k{sub d} and the hourly clearness index k{sub t}, has concluded that k{sub t} is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse component for a specific clearness index under partly cloudy sky conditions has led to analyzing how the variability in the instantaneous clearness index influences this dispersion. The data sets correspond to 10 years of hourly and instantaneous value records of global and diffuse radiation collected in Cordoba, Spain. In addition to the inclusion of the sine of solar elevation as a variable into the k{sub d}-k{sub t} correlations, this model propose the inclusion of others parameters related to the variability in the normalized clearness index within an hour and with the fluctuations presented by the time series of the instantaneous values of that index. Also presented is the implementation of an algorithm permitting both the determination of the hourly diffuse irradiation and the discrimination between the different sky conditions in those situations known by the designation partly cloudy sky. (author)

Association between sleeping hours, working hours and obesity in Hong Kong Chinese: the 'better health for better Hong Kong' health promotion campaign.

Science.gov (United States)

Ko, G T C; Chan, J C N; Chan, A W Y; Wong, P T S; Hui, S S C; Tong, S D Y; Ng, S-M; Chow, F; Chan, C L W

2007-02-01

To study the inter-relationships between sleeping hours, working hours and obesity in subjects from a working population. A cross-sectional observation study under the 'Better Health for Better Hong Kong' Campaign, which is a territory-wide health awareness and promotion program. 4793 subjects (2353 (49.1%) men and 2440 (50.9%) women). Their mean age (+/-s.d.) was 42.4+/-8.9 years (range 17-83 years, median 43.0 years). Subjects were randomly selected using computer-generated codes in accordance to the distribution of occupational groups in Hong Kong. The mean daily sleeping time was 7.06+/-1.03 h (women vs men: 7.14+/-1.08 h vs 6.98+/-0.96 h, Pworking hours reaching significance in the whole group as well as among male subjects. Those with short sleeping hour (6 h or less) and long working hours (>9 h) had the highest BMI and waist in both men and women. Based on multiple regression analysis with age, smoking, alcohol drinking, systolic and diastolic blood pressure, mean daily sleeping hours and working hours as independent variables, BMI was independently associated with age, systolic and diastolic blood pressure in women, whereas waist was associated with age, smoking and blood pressure. In men, blood pressure, sleeping hours and working hours were independently associated with BMI, whereas waist was independently associated with age, smoking, blood pressure, sleeping hours and working hours in men. Obesity is associated with reduced sleeping hours and long working hours in men among Hong Kong Chinese working population. Further studies are needed to investigate the underlying mechanisms of this relationship and its potential implication on prevention and management of obesity.

Attempt to determine radon entry rate and air exchange rate variable in time from the time course of indoor radon concentration

Energy Technology Data Exchange (ETDEWEB)

Thomas, J [State Office for Nuclear Protection, Prague (Czech Republic)

1996-12-31

For radon diagnosis in houses the `ventilation experiment` was used as a standard method. After removal of indoor radon by draught the build-up of radon concentration a(t) [Bq/m{sup 3}] was measured continuously and from the time course the constant radon entry rate A [Bq/h] and the exchange rate k [h{sup -1}] was calculated by regression analysis using model relation a(t) A(1-e{sup -kt})/kV with V [m{sup 3}] for volume of the room. The conditions have to be stable for several hours so that the assumption of constant A and k was justified. During the day both quantities were independently (?) changing, therefore a method to determine variable entry rate A(t) and exchange rate k(t) is needed for a better understanding of the variability of the indoor radon concentration. Two approaches are given for the determination of variable in time radon entry rates and air exchange rates from continuously measured indoor radon concentration - numerical solution of the equivalent difference equations in deterministic or statistic form. The approaches are not always successful. Failures giving a right ration for the searched rates but not of the rates them self could not be explained.

Time dependence of the UV resonance lines in the cataclysmic variables SU UMa, RX And and 0623+71

International Nuclear Information System (INIS)

Woods, J.A.; Drew, J.E.; Verbunt, Frank

1990-01-01

We present IUE observations of the dwarf novae SU UMa and RX And, and of the nova-like variable 0623 + 71. At the time of observation, SU UMa and RX And were in outburst. All three systems show variability in the wind-formed UV resonance lines of N v λ 1240, Si IV λ 1397 and C IV λ 1549 on timescale of hours. The amplitude of variation is smallest in RX And and largest in 0623 + 71. There is evidence that the variations observed in SU UMa's UV spectrum repeat on the orbital period. Our observations of SU UMa also reveal variability in the continuum flux during the decline from outburst maximum that is much more marked in the UV than at optical wavelengths. (author)

Prelude to a RIF: older workers, part-time hours, and unemployment.

Science.gov (United States)

Reynolds, Jeremy; Wenger, Jeffrey B

2010-04-01

Since the beginning of the most recent recession in December 2007, involuntary part-time employment (part-time for economic reasons) in the United States has increased from 4.2 million workers to 9.1 million, more than doubling. In this paper, we examine whether such increases in involuntary part-time employment have helped combat unemployment in the past or placed a disproportionate burden on older workers. Using Current Population Survey (outgoing rotation group) data from 1983 to 2002, we find that increases in involuntary part-time work in an industry raise the industry unemployment rate. Furthermore, the connection between rising rates of involuntary part-time work and unemployment is stronger among older workers than among younger workers. We conclude that reducing work hours through the use of part-time work does not ameliorate the effects of recessions on workers. Rather, it is a harbinger of unemployment, especially among those older than 55.

Health and psychosocial effects of flexible working hours

Directory of Open Access Journals (Sweden)

Daniela Janssen

2004-12-01

Full Text Available OBJECTIVE: To examine whether any impairments in health and social lives can be found under different kinds of flexible working hours, and whether such effects are related to specific characteristics of these working hours. METHODS: Two studies - a company based survey (N=660 and an internet survey (N=528 - have been conducted. The first one was a questionnaire study (paper and pencil on employees working under some 'typical' kinds of different flexible working time arrangements in different companies and different occupational fields (health care, manufacturing, retail, administration, call centres. The second study was an internet-based survey, using an adaptation of the questionnaire from the first study. RESULTS: The results of both studies consistently show that high variability of working hours is associated with increased impairments in health and well-being and this is especially true if this variability is company controlled. These effects are less pronounced if variability is self-controlled; however, autonomy does not compensate the effects of variability. CONCLUSIONS: Recommendations for an appropriate design of flexible working hours should be developed in order to minimize any impairing effects on health and psychosocial well-being; these recommendations should include - besides allowing for discretion in controlling one's (flexible working hours - that variability in flexible working hours should be kept low (or at least moderate, even if this variability is self-controlled.OBJETIVO: Investigar se ocorre prejuízo à saúde e à vida social com diferentes tipos de horas de trabalho flexíveis e se há relação entre estes efeitos e características específicas das horas de trabalho. MÉTODOS: Foram realizados dois estudos, uma pesquisa em uma empresa (N=660 e outra pela Internet (N=528. O primeiro estudo consistiu de um questionário (papel e lápis aplicado a funcionários sujeitos a diferentes ajustes "típicos" de horas de

48 CFR 52.216-30 - Time-and-Materials/Labor-Hour Proposal Requirements-Non-Commercial Item Acquisition without...

Science.gov (United States)

2010-10-01

...-Hour Proposal Requirements-Non-Commercial Item Acquisition without Adequate Price Competition. 52.216... Price Competition. As prescribed in 16.601(e)(2), insert the following provision: Time-and-Materials/Labor-Hour Proposal Requirements—Non-Commercial Item Acquisition Without Adequate Price Competition (FEB...

The predictability of a lake phytoplankton community, over time-scales of hours to years

DEFF Research Database (Denmark)

Thomas, Mridul K.; Fontana, Simone; Reyes, Marta

2018-01-01

monitoring data (biological, physical and chemical) to assess the predictability of phytoplankton cell density in one lake across an unprecedented range of time-scales. Communities were highly predictable over hours to months: model R2 decreased from 0.89 at 4 hours to 0.74 at 1 month, and in a long......Forecasting changes to ecological communities is one of the central challenges in ecology. However, nonlinear dependencies, biotic interactions and data limitations have limited our ability to assess how predictable communities are. Here, we used a machine learning approach and environmental...

Working Hours and Productivity

OpenAIRE

Collewet, Marion; Sauermann, Jan

2017-01-01

This paper studies the link between working hours and productivity using daily information on working hours and performance of a sample of call centre agents. We exploit variation in the number of hours worked by the same employee across days and weeks due to central scheduling, enabling us to estimate the effect of working hours on productivity. We find that as the number of hours worked increases, the average handling time for a call increases, meaning that agents become less productive. Th...

MODELS OF HOURLY DRY BULB TEMPERATURE AND ...

African Journals Online (AJOL)

Hourly meteorological data of both dry bulb temperature and relative humidity for 18 locations in Nigeria for the period 1995 to 2009 were analysed to obtain the mean monthly average and monthly hourly average of each of the two meteorological variables for each month for each location. The difference between the ...

Operator alertness and performance on 8-hour and 12-hour work shifts

International Nuclear Information System (INIS)

Baker, T.L.; Campbell, S.S.; Dawson, D.; Moore-Ede, M.

1989-01-01

Recently, much attention has been paid to the alertness and performance problems of rotational shiftworkers in the nuclear power industry. Growing awareness of higher rates of human errors and accidents on night shifts and reports of operations personnel falling asleep on the job have contributed to the heightened interest in this subject. The industry is now considering the effects of different shift rotation systems, including evaluation of the most recent of industry trends in shift scheduling-schedules that include 12 hour work shifts. Surveys show that within the past 5 years about 20% of commercially operational nuclear power plants have instituted schedules that use only 12 hour shifts, or schedules using a combination of 8-hour and 12-hour shifts. Many more plants routinely use 12-hour work shifts during plant outages and refueling operations. In response to this growing trend, the NRC has funded research which is a first attempt to compare alertness, operator performance, and sleep-wake patterns in subjects working simulated 8-hour and 12-hour shifts at the Human Alertness Research Center (HARC), located at the Institute of Circadian Physiology in Boston, MA. This paper will describe in greater detail the design of the study, measurement techniques for alertness and sleep, work routine, work task performance measures, and cognitive performance test protocols. It will review the role of circadian factors in human alertness and performance, and discuss previous research findings in this area. It will discuss other variables that are known to influence human alertness in the workplace, such as caffeine, alcohol, and working environment. The physiological basis for shift worker sleep problems will be explained in the context of the ongoing research project at HARC. Finally, the paper presents previous research on shift work and fatigue which may be relevant to a comparison of 8-hour and 12-hour shifts

Effect of 16-hour duty periods on patient care and resident education.

Science.gov (United States)

McCoy, Christopher P; Halvorsen, Andrew J; Loftus, Conor G; McDonald, Furman S; Oxentenko, Amy S

2011-03-01

To measure the effect of duty periods no longer than 16 hours on patient care and resident education. As part of our Educational Innovations Project, we piloted a novel resident schedule for an inpatient service that eliminated shifts longer than 16 hours without increased staffing or decreased patient admissions on 2 gastroenterology services from August 29 to November 27, 2009. Patient care variables were obtained through medical record review. Resident well-being and educational variables were collected by weekly surveys, end of rotation evaluations, and an electronic card-swipe system. Patient care metrics, including 30-day mortality, 30-day readmission rate, and length of stay, were unchanged for the 196 patient care episodes in the 5-week intervention month compared with the 274 episodes in the 8 weeks of control months. However, residents felt less prepared to manage cross-cover of patients (P = .006). There was a nonsignificant trend toward decreased perception of quality of education and balance of personal and professional life during the intervention month. Residents reported working fewer weekly hours overall during the intervention (64.3 vs 68.9 hours; P = .40), but they had significantly more episodes with fewer than 10 hours off between shifts (24 vs 2 episodes; P = .004). Inpatient hospital services can be staffed with residents working shifts less than 16 hours without additional residents. However, cross-cover of care, quality of education, and time off between shifts may be adversely affected.

Change in working characteristics of the steam turbine metal with operating time of more than 330000 hours

Science.gov (United States)

Gladshteyn, V. I.; Troitskiy, A. I.

2017-01-01

Research of a metal of the stop valve case (SVC) of the K-300-23.5 LMZ turbine (steel grade 15Kh1M1FL), destroyed after operation for 331000 hours, is performed. It's chemical composition and properties are determined as follows: a short-term mechanical tensile stress at 20°C and at elevated temperature, critical temperature, fragility, critical crack opening at elevated temperature, and long-term strength. Furthermore, nature of the microstructure, packing density of carbide particles and their size, and chemical composition of carbide sediment are estimated. A manifestation of metal properties for the main case components by comparison with a forecast of the respective characteristics made for the operating time of 331000 hours is tested. Property-time relationships are built for the forecast using statistical treatment of the test results for the samples cut out from more than 300 parts. Representativeness of the research results is proved: the statistical treatment of their differences are within the range of ±5%. It has been found that, after 150000 hours of operation, only the tensile strength insignificantly depends on the operating time at 20°C, whereas indicators of strength at elevated temperature significantly reduce, depending on the operating time. A brittle-to-ductile transition temperature (BDTT) raises, a critical notch opening changes in a complicated way, a long-term strength reduces. It has been found empirically that the limit of a long-term strength of the SVC metal at 540°C and the operating time of 105 hours is almost 1.6 times less than the required value in the as-delivered state. It is possible to evaluate a service life of the operating valves with the operating time of more than 330000 hours with respect to the long-term strength of the metal taking into account the actual temperature and stress. Guidelines for the control of similar parts are provided.

Periodicity and stability for variable-time impulsive neural networks.

Science.gov (United States)

Li, Hongfei; Li, Chuandong; Huang, Tingwen

2017-10-01

The paper considers a general neural networks model with variable-time impulses. It is shown that each solution of the system intersects with every discontinuous surface exactly once via several new well-proposed assumptions. Moreover, based on the comparison principle, this paper shows that neural networks with variable-time impulse can be reduced to the corresponding neural network with fixed-time impulses under well-selected conditions. Meanwhile, the fixed-time impulsive systems can be regarded as the comparison system of the variable-time impulsive neural networks. Furthermore, a series of sufficient criteria are derived to ensure the existence and global exponential stability of periodic solution of variable-time impulsive neural networks, and to illustrate the same stability properties between variable-time impulsive neural networks and the fixed-time ones. The new criteria are established by applying Schaefer's fixed point theorem combined with the use of inequality technique. Finally, a numerical example is presented to show the effectiveness of the proposed results. Copyright © 2017 Elsevier Ltd. All rights reserved.

OPERATIONS THROUGHPUT AS A DETERMINANT OF GOLDEN-HOUR IN MASS-GATHERING MEDICINE

Directory of Open Access Journals (Sweden)

I. D. Khan

2017-07-01

Full Text Available BACKGROUND Golden-hour, a time-tested concept for trauma-care, involves a systems approach encompassing healthcare, logistics, geographical, environmental and temporal variables. Golden-hour paradigm in mass-gathering-medicine such as the Hajj-pilgrimage entwines along healthcare availability, accessibility, efficiency and interoperability; expanding from the patient-centric to public-health centric approach. The realm of mass-gathering-medicine invokes an opportunity for incorporating operations-throughput as a determinant of golden-hour for overall capacity-building and interoperability. METHODS Golden-hour was evaluated during the Indian-Medical-Mission operations for Hajj-2016; which established, operated and coordinated a strategic network of round-the-clock medical operations. Throughput was evaluated as deliverables/time, against established Standard-Operating-Procedures for various clinical, investigation, drug-dispensing and patient-transfer algorithms. Patient encounter-time, waiting-time, turnaround-time were assessed throughout echeloned healthcare under a patient-centric healthcare-delivery model. Dynamic evaluation was carried out to cater for variation and heterogeneity. RESULTS Massive surge of 3,94,013 patients comprising 2,25,103 males (57.1% and 1,68,910 females (42.9% overwhelmed the throughput capacities of outpatient attendance, pharmacy, laboratory, imaging, ambulance, referrals and documentation. There was delay in attendance, suspicion, diagnosis and isolation of patients with communicable infections. The situational-analysis of operations-throughput highlights wasted turnaround-time due to mobilization of medical-team, diverting critical healthcare resources away from emergency situations. CONCLUSION Time being a crucial factor in the complexity of medical-care, operations-throughput remains an important determinant towards interoperability of bottlenecks, thereby being a determinant of golden-hour in mass

Hourly awakening vs continuous contact lens sensor measurements of 24-hour intraocular pressure: effect on sleep macrostructure and intraocular pressure rhythm.

Science.gov (United States)

Aptel, Florent; Tamisier, Renaud; Pépin, Jean-Louis; Mottet, Benjamin; Hubanova, Ralitsa; Romanet, Jean-Paul; Chiquet, Christophe

2014-10-01

All studies of 24-hour intraocular pressure (IOP) rhythm conducted to date have used repeated IOP measurements requiring nocturnal awakenings, potentially disturbing sleep macrostructure. To evaluate the effects on sleep architecture and IOP rhythm of hourly awakening vs a contact lens sensor (CLS) to continuously monitor IOP without awakening. Cross-sectional study at a referral center of chronobiology among 12 young healthy volunteers, with a mean (SD) age of 22.3 (2.3) years. Volunteers underwent two 24-hour IOP measurement sessions during a 2-month period. The eye order and session order were randomized. During one session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was measured hourly using a portable noncontact tonometer (session with nocturnal hourly awakening). During the other session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was not measured (session without nocturnal awakening). Overnight polysomnography was performed during the 2 sessions. A nonlinear least squares, dual-harmonic regression analysis was used to model the 24-hour IOP rhythm from the CLS data. Comparisons of acrophase, bathyphase, amplitude, and the midline estimating statistic of rhythm were used to evaluate the effect of hourly awakening on IOP rhythm. To evaluate the effects of hourly awakening on sleep architecture, comparisons of sleep structure were used, including total sleep period, rapid eye movement, wake after sleep onset, absolute and relative total sleep time, and non-rapid eye movement sleep (N1, N2, and N3). A 24-hour IOP rhythm was found in all individuals for the sessions with and without awakening (P  .30). Hourly awakening during noncontact tonometer IOP measurements did not seem to alter the mean variables of the 24-hour IOP pattern evaluated using CLS, including signal, maximum signal, minimum signal, acrophase, and bathyphase (P > .15). The 24-hour IOP

The Persistence of Long Work Hours

OpenAIRE

Robert Drago; David Black; Mark Wooden

2005-01-01

Previous research hypothesizes that long working hours are related to consumerism, the ideal worker norm, high levels of human capital, and a high cost-of-job-loss. The authors test these hypotheses using panel data on working hours for an Australian sample of full-time employed workers. Analyses include a static cross-sectional model and a persistence model for long hours over time. The results suggest that long hours (50 or more hours in a usual week) are often persistent, and provide stron...

Time-trend analyses of bleeding and mortality after primary percutaneous coronary intervention during out of working hours versus in-working hours: an observational study of 11 466 patients.

Science.gov (United States)

Iqbal, M Bilal; Khamis, Ramzi; Ilsley, Charles; Mikhail, Ghada; Crake, Tom; Firoozi, Sam; Kalra, Sundeep; Knight, Charles; Archbold, Andrew; Lim, Pitt; Mathur, Anthony; Meier, Pascal; Rakhit, Roby D; Redwood, Simon; Whitbread, Mark; Bromage, Dan; Rathod, Krishna; Jones, Daniel A; Wragg, Andrew; Dalby, Miles; MacCarthy, Phil; Malik, Iqbal S

2015-06-01

Primary percutaneous coronary intervention (PPCI) is the treatment of choice for ST-segment-elevation myocardial infarction. Resources are limited during out of working hours (OWH). Whether PPCI outside working hours is associated with worse outcomes and whether outcomes have improved over time are unknown. We analyzed 11 466 patients undergoing PPCI between 2004 and 2011 at all 8 tertiary cardiac centers in London, United Kingdom. We defined working hours as 9 am to 5 pm (Monday to Friday). We analyzed in-hospital bleeding and all-cause mortality ≤3 years, comparing OWH versus in-working hours. A total of 7494 patients (65.3%) were treated during OWH. Multivariable analyses demonstrated that PPCI during OWH was not a predictor for bleeding (odds ratio, 1.47; 95% confidence interval [CI], 0.97-2.24; P=0.071) or 3-year mortality (hazard ratio, 1.11; 95% CI, 0.94-1.32; P=0.20). This was confirmed in propensity-matched analyses. Time-stratified analyses demonstrated that PPCI during OWH was a predictor for bleeding (odds ratio, 2.00; 95% CI, 1.06-3.80; P=0.034) and 3-year mortality during 2005 to 2008 (hazard ratio, 1.23; 95% CI, 1.00-1.50; P=0.050), but this association was lost during 2009 to 2011. During 2005 to 2008, transradial access was predominantly used during in-working hours and PPCI during OWH was predictive of reduced transradial access use (odds ratio, 0.83; 95% CI, 0.71-0.98; P=0.033), but this association was lost during 2009 to 2011. In this study of unselected patients with ST-segment-elevation myocardial infarction, PPCI during OWH versus in-working hours had comparable bleeding and mortality. Time-stratified analyses demonstrated a reduction in adjusted bleeding and mortality during OWH over time. This may reflect the improved service provision, but the increased adoption of transradial access during OWH may also be contributory. © 2015 American Heart Association, Inc.

Intra-Hour Dispatch and Automatic Generator Control Demonstration with Solar Forecasting - Final Report

Energy Technology Data Exchange (ETDEWEB)

Coimbra, Carlos F. M. [Univ. of California, San Diego, CA (United States

2016-02-25

In this project we address multiple resource integration challenges associated with increasing levels of solar penetration that arise from the variability and uncertainty in solar irradiance. We will model the SMUD service region as its own balancing region, and develop an integrated, real-time operational tool that takes solar-load forecast uncertainties into consideration and commits optimal energy resources and reserves for intra-hour and intra-day decisions. The primary objectives of this effort are to reduce power system operation cost by committing appropriate amount of energy resources and reserves, as well as to provide operators a prediction of the generation fleet’s behavior in real time for realistic PV penetration scenarios. The proposed methodology includes the following steps: clustering analysis on the expected solar variability per region for the SMUD system, Day-ahead (DA) and real-time (RT) load forecasts for the entire service areas, 1-year of intra-hour CPR forecasts for cluster centers, 1-year of smart re-forecasting CPR forecasts in real-time for determination of irreducible errors, and uncertainty quantification for integrated solar-load for both distributed and central stations (selected locations within service region) PV generation.

Resolving issues concerning Eskdalemuir geomagnetic hourly values

Directory of Open Access Journals (Sweden)

S. Macmillan

2011-02-01

Full Text Available The hourly values of the geomagnetic field from 1911 to 1931 derived from measurements made at Eskdalemuir observatory in the UK, and available online from the World Data Centre for Geomagnetism at http://www.wdc.bgs.ac.uk/, have now been corrected. Previously they were 2-point averaged and transformed from the original north, east and vertical down values in the tables in the observatory yearbooks. This paper documents the course of events from discovering the post-processing done to the data to the final resolution of the problem. As it was through the development of a new index, the Inter-Hour Variability index, that this post-processing came to light, we provide a revised series of this index for Eskdalemuir and compare it with that from another European observatory. Conclusions of studies concerning long-term magnetic field variability and inferred solar variability, whilst not necessarily consistent with one another, are not obviously invalidated by the incorrect hourly values from Eskdalemuir. This series of events illustrates the challenges that lie ahead in removing any remaining errors and inconsistencies in the data holdings of different World Data Centres.

Lean principles optimize on-time vascular surgery operating room starts and decrease resident work hours.

Science.gov (United States)

Warner, Courtney J; Walsh, Daniel B; Horvath, Alexander J; Walsh, Teri R; Herrick, Daniel P; Prentiss, Steven J; Powell, Richard J

2013-11-01

Lean process improvement techniques are used in industry to improve efficiency and quality while controlling costs. These techniques are less commonly applied in health care. This study assessed the effectiveness of Lean principles on first case on-time operating room starts and quantified effects on resident work hours. Standard process improvement techniques (DMAIC methodology: define, measure, analyze, improve, control) were used to identify causes of delayed vascular surgery first case starts. Value stream maps and process flow diagrams were created. Process data were analyzed with Pareto and control charts. High-yield changes were identified and simulated in computer and live settings prior to implementation. The primary outcome measure was the proportion of on-time first case starts; secondary outcomes included hospital costs, resident rounding time, and work hours. Data were compared with existing benchmarks. Prior to implementation, 39% of first cases started on time. Process mapping identified late resident arrival in preoperative holding as a cause of delayed first case starts. Resident rounding process inefficiencies were identified and changed through the use of checklists, standardization, and elimination of nonvalue-added activity. Following implementation of process improvements, first case on-time starts improved to 71% at 6 weeks (P = .002). Improvement was sustained with an 86% on-time rate at 1 year (P < .001). Resident rounding time was reduced by 33% (from 70 to 47 minutes). At 9 weeks following implementation, these changes generated an opportunity cost potential of $12,582. Use of Lean principles allowed rapid identification and implementation of perioperative process changes that improved efficiency and resulted in significant cost savings. This improvement was sustained at 1 year. Downstream effects included improved resident efficiency with decreased work hours. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All

Prewhitening of hydroclimatic time series? Implications for inferred change and variability across time scales

Science.gov (United States)

Razavi, Saman; Vogel, Richard

2018-02-01

Prewhitening, the process of eliminating or reducing short-term stochastic persistence to enable detection of deterministic change, has been extensively applied to time series analysis of a range of geophysical variables. Despite the controversy around its utility, methodologies for prewhitening time series continue to be a critical feature of a variety of analyses including: trend detection of hydroclimatic variables and reconstruction of climate and/or hydrology through proxy records such as tree rings. With a focus on the latter, this paper presents a generalized approach to exploring the impact of a wide range of stochastic structures of short- and long-term persistence on the variability of hydroclimatic time series. Through this approach, we examine the impact of prewhitening on the inferred variability of time series across time scales. We document how a focus on prewhitened, residual time series can be misleading, as it can drastically distort (or remove) the structure of variability across time scales. Through examples with actual data, we show how such loss of information in prewhitened time series of tree rings (so-called "residual chronologies") can lead to the underestimation of extreme conditions in climate and hydrology, particularly droughts, reconstructed for centuries preceding the historical period.

Short time-scale optical variability properties of the largest AGN sample observed with Kepler/K2

Science.gov (United States)

Aranzana, E.; Körding, E.; Uttley, P.; Scaringi, S.; Bloemen, S.

2018-05-01

We present the first short time-scale (˜hours to days) optical variability study of a large sample of active galactic nuclei (AGNs) observed with the Kepler/K2 mission. The sample contains 252 AGN observed over four campaigns with ˜30 min cadence selected from the Million Quasar Catalogue with R magnitude <19. We performed time series analysis to determine their variability properties by means of the power spectral densities (PSDs) and applied Monte Carlo techniques to find the best model parameters that fit the observed power spectra. A power-law model is sufficient to describe all the PSDs of our sample. A variety of power-law slopes were found indicating that there is not a universal slope for all AGNs. We find that the rest-frame amplitude variability in the frequency range of 6 × 10-6-10-4 Hz varies from 1to10 per cent with an average of 1.7 per cent. We explore correlations between the variability amplitude and key parameters of the AGN, finding a significant correlation of rest-frame short-term variability amplitude with redshift. We attribute this effect to the known `bluer when brighter' variability of quasars combined with the fixed bandpass of Kepler data. This study also enables us to distinguish between Seyferts and blazars and confirm AGN candidates. For our study, we have compared results obtained from light curves extracted using different aperture sizes and with and without detrending. We find that limited detrending of the optimal photometric precision light curve is the best approach, although some systematic effects still remain present.

Physical attraction to reliable, low variability nervous systems: Reaction time variability predicts attractiveness.

Science.gov (United States)

Butler, Emily E; Saville, Christopher W N; Ward, Robert; Ramsey, Richard

2017-01-01

The human face cues a range of important fitness information, which guides mate selection towards desirable others. Given humans' high investment in the central nervous system (CNS), cues to CNS function should be especially important in social selection. We tested if facial attractiveness preferences are sensitive to the reliability of human nervous system function. Several decades of research suggest an operational measure for CNS reliability is reaction time variability, which is measured by standard deviation of reaction times across trials. Across two experiments, we show that low reaction time variability is associated with facial attractiveness. Moreover, variability in performance made a unique contribution to attractiveness judgements above and beyond both physical health and sex-typicality judgements, which have previously been associated with perceptions of attractiveness. In a third experiment, we empirically estimated the distribution of attractiveness preferences expected by chance and show that the size and direction of our results in Experiments 1 and 2 are statistically unlikely without reference to reaction time variability. We conclude that an operating characteristic of the human nervous system, reliability of information processing, is signalled to others through facial appearance. Copyright © 2016 Elsevier B.V. All rights reserved.

Culture of human dental pulp cells at variable times post-tooth extraction

Directory of Open Access Journals (Sweden)

BENÍCIO Daniela Ferreira Araújo

2018-02-01

Full Text Available Abstract The aim of this study was to investigate the viability of human dental pulp cells from extracted teeth kept at standard room temperature and atmospheric pressure for different periods of time. Twenty-one healthy permanent teeth were used. They were divided into five groups according to the expected time from extraction to processing. One group was tested immediately after extraction; the other groups were each tested at one of the following time points: 30 minutes, 1 hour, 2 hours, and 5 hours post-extraction. Cell morphology was analysed by light microscopy; cell proliferation was analysed using MTT assay and by counting the viable cells in a haemocytometer. Similar results were observed in all groups (p < 0.05. A delay of up to five hours for tooth processing and tissue collection does not preclude the establishment of dental pulp cell cultures, affect the morphology of these cells, or reduce their proliferative potential.

48 CFR 52.216-29 - Time-and-Materials/Labor-Hour Proposal Requirements-Non-Commercial Item Acquisition With Adequate...

Science.gov (United States)

2010-10-01

...-Hour Proposal Requirements-Non-Commercial Item Acquisition With Adequate Price Competition. 52.216-29... Proposal Requirements—Non-Commercial Item Acquisition With Adequate Price Competition (FEB 2007) (a) The... Time-and-Materials/Labor-Hour Proposal Requirements—Non-Commercial Item Acquisition With Adequate Price...

Travel time variability and airport accessibility

NARCIS (Netherlands)

Koster, P.R.; Kroes, E.P.; Verhoef, E.T.

2011-01-01

We analyze the cost of access travel time variability for air travelers. Reliable access to airports is important since the cost of missing a flight is likely to be high. First, the determinants of the preferred arrival times at airports are analyzed. Second, the willingness to pay (WTP) for

A model for AGN variability on multiple time-scales

Science.gov (United States)

Sartori, Lia F.; Schawinski, Kevin; Trakhtenbrot, Benny; Caplar, Neven; Treister, Ezequiel; Koss, Michael J.; Urry, C. Megan; Zhang, C. E.

2018-05-01

We present a framework to link and describe active galactic nuclei (AGN) variability on a wide range of time-scales, from days to billions of years. In particular, we concentrate on the AGN variability features related to changes in black hole fuelling and accretion rate. In our framework, the variability features observed in different AGN at different time-scales may be explained as realisations of the same underlying statistical properties. In this context, we propose a model to simulate the evolution of AGN light curves with time based on the probability density function (PDF) and power spectral density (PSD) of the Eddington ratio (L/LEdd) distribution. Motivated by general galaxy population properties, we propose that the PDF may be inspired by the L/LEdd distribution function (ERDF), and that a single (or limited number of) ERDF+PSD set may explain all observed variability features. After outlining the framework and the model, we compile a set of variability measurements in terms of structure function (SF) and magnitude difference. We then combine the variability measurements on a SF plot ranging from days to Gyr. The proposed framework enables constraints on the underlying PSD and the ability to link AGN variability on different time-scales, therefore providing new insights into AGN variability and black hole growth phenomena.

Surgeon and type of anesthesia predict variability in surgical procedure times.

Science.gov (United States)

Strum, D P; Sampson, A R; May, J H; Vargas, L G

2000-05-01

Variability in surgical procedure times increases the cost of healthcare delivery by increasing both the underutilization and overutilization of expensive surgical resources. To reduce variability in surgical procedure times, we must identify and study its sources. Our data set consisted of all surgeries performed over a 7-yr period at a large teaching hospital, resulting in 46,322 surgical cases. To study factors associated with variability in surgical procedure times, data mining techniques were used to segment and focus the data so that the analyses would be both technically and intellectually feasible. The data were subdivided into 40 representative segments of manageable size and variability based on headers adopted from the common procedural terminology classification. Each data segment was then analyzed using a main-effects linear model to identify and quantify specific sources of variability in surgical procedure times. The single most important source of variability in surgical procedure times was surgeon effect. Type of anesthesia, age, gender, and American Society of Anesthesiologists risk class were additional sources of variability. Intrinsic case-specific variability, unexplained by any of the preceding factors, was found to be highest for shorter surgeries relative to longer procedures. Variability in procedure times among surgeons was a multiplicative function (proportionate to time) of surgical time and total procedure time, such that as procedure times increased, variability in surgeons' surgical time increased proportionately. Surgeon-specific variability should be considered when building scheduling heuristics for longer surgeries. Results concerning variability in surgical procedure times due to factors such as type of anesthesia, age, gender, and American Society of Anesthesiologists risk class may be extrapolated to scheduling in other institutions, although specifics on individual surgeons may not. This research identifies factors associated

A coupled weather generator - rainfall-runoff approach on hourly time steps for flood risk analysis

Science.gov (United States)

Winter, Benjamin; Schneeberger, Klaus; Dung Nguyen, Viet; Vorogushyn, Sergiy; Huttenlau, Matthias; Merz, Bruno; Stötter, Johann

2017-04-01

The evaluation of potential monetary damage of flooding is an essential part of flood risk management. One possibility to estimate the monetary risk is to analyze long time series of observed flood events and their corresponding damages. In reality, however, only few flood events are documented. This limitation can be overcome by the generation of a set of synthetic, physically and spatial plausible flood events and subsequently the estimation of the resulting monetary damages. In the present work, a set of synthetic flood events is generated by a continuous rainfall-runoff simulation in combination with a coupled weather generator and temporal disaggregation procedure for the study area of Vorarlberg (Austria). Most flood risk studies focus on daily time steps, however, the mesoscale alpine study area is characterized by short concentration times, leading to large differences between daily mean and daily maximum discharge. Accordingly, an hourly time step is needed for the simulations. The hourly metrological input for the rainfall-runoff model is generated in a two-step approach. A synthetic daily dataset is generated by a multivariate and multisite weather generator and subsequently disaggregated to hourly time steps with a k-Nearest-Neighbor model. Following the event generation procedure, the negative consequences of flooding are analyzed. The corresponding flood damage for each synthetic event is estimated by combining the synthetic discharge at representative points of the river network with a loss probability relation for each community in the study area. The loss probability relation is based on exposure and susceptibility analyses on a single object basis (residential buildings) for certain return periods. For these impact analyses official inundation maps of the study area are used. Finally, by analyzing the total event time series of damages, the expected annual damage or losses associated with a certain probability of occurrence can be estimated for

Evaluation of patient preferences towards treatment during extended hours for patients receiving radiation therapy for the treatment of cancer: A time trade-off study

International Nuclear Information System (INIS)

Brown, Alison M.; Atyeo, John; Field, Nikki; Cox, Jennifer; Bull, Colin; Gebski, Val J.

2009-01-01

Background: To reduce the waiting time between diagnosis and the start of radiation therapy, some departments have introduced appointments outside of conventional working hours, but the inconvenience this may cause to patients is unknown. We examined, from the patient's perspective, whether reduced waiting times to treatment would be sufficient to trade off against potentially inconvenient appointment times. Method: We interviewed patients receiving radiation therapy at a major teaching hospital between January and May 2005. Two patient groups were considered: those treated during conventional working hours (8.30 am to 4.30 pm), and those treated outside these hours. Patients were asked to trade a reduction in waiting time to the start of treatment against treatment outside conventional working hours. Results: Of 129 patients interviewed, 77 were treated during conventional working hours and 52 outside these hours. Fifty-seven (44%) were male and 52 (40%) were aged over 60 years. To prefer treatment out of working hours, patients being treated during conventional working hours required a larger reduction in waiting time (odds ratio 2.36, 95% CI 0.97-5.76). Patients with curable disease and those who had made few changes in their lifestyle throughout the treatment were more likely to accept treatment outside of conventional working hours. Conclusion: It is impractical to satisfy the treatment-time preferences of all patients. However, many patients prefer treatment outside of normal treatment times if this would reduce the time until the start of radiation therapy. Evaluating the effect of waiting times on patients' perceptions of their disease control provides important information in allocating treatment hours and appointment times

Discrete-time BAM neural networks with variable delays

Science.gov (United States)

Liu, Xin-Ge; Tang, Mei-Lan; Martin, Ralph; Liu, Xin-Bi

2007-07-01

This Letter deals with the global exponential stability of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Using a Lyapunov functional, and linear matrix inequality techniques (LMI), we derive a new delay-dependent exponential stability criterion for BAM neural networks with variable delays. As this criterion has no extra constraints on the variable delay functions, it can be applied to quite general BAM neural networks with a broad range of time delay functions. It is also easy to use in practice. An example is provided to illustrate the theoretical development.

Discrete-time BAM neural networks with variable delays

International Nuclear Information System (INIS)

Liu Xinge; Tang Meilan; Martin, Ralph; Liu Xinbi

2007-01-01

This Letter deals with the global exponential stability of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Using a Lyapunov functional, and linear matrix inequality techniques (LMI), we derive a new delay-dependent exponential stability criterion for BAM neural networks with variable delays. As this criterion has no extra constraints on the variable delay functions, it can be applied to quite general BAM neural networks with a broad range of time delay functions. It is also easy to use in practice. An example is provided to illustrate the theoretical development

Wind and load variability in the Nordic countries

Energy Technology Data Exchange (ETDEWEB)

Holttinen, H.; Rissanen, S. [VTT Technical Research Centre of Finland, Espoo (Finland); Larsen, X. [Danmarks Tekniske Universitet, Lyngby (Denmark); Loevholm, A. L. [Kjeller Vindteknikk (Norway)

2013-04-15

This publication analysed the variability of wind production and load in Denmark, Finland, Sweden, and the Nordic region as a whole, based on real data measured from large-scale wind power during 2009-2011. The Nordic-wide wind power time series was scaled up such that Sweden had same amount of wind power production than Denmark, and Finland and Norway only 50% of the wind power production in Denmark. Wind power production in Denmark and Sweden is somewhat correlated (coefficient 0.7) but less correlation is found between the other countries. The variations from one hour to the next are only weakly correlated between all countries, even between Denmark and Sweden. Largest variations occur when the production is approximately 30-70% of installed capacity and variability is low during periods of light winds. The variability in shorter time scales was less than the hourly variations. During the three years analysed in this publication there were few storm incidents and they did not produce dramatic wind power ramps in the Nordic region. Wind and load variations are not correlated between the countries, which is beneficial from the viewpoint of wind integration. The smoothing effect is shown as reduction of variability from a single country to Nordic-wide wind power. The impact of wind power on the variability that the system experiences is evaluated by analysing the variability of net load with different wind power penetration levels. The Nordic-wide wind power production increases the highest hourly ramps by 2.4% (up) and -3.6% (down) of installed wind power capacity when there is 20% wind power penetration and by 2.7% (up) and -4.7% (down) for 30% wind penetration. These results assess the impacts of variability only. The next step will be assessing the uncertainty from forecast errors. The timing of ramp events, and occurrence of high-wind and low-load are studied. With current wind penetration, low production levels (2-5% of installed wind power) can occur in a

Hourly differences in air pollution and risk of respiratory disease in the elderly: a time-stratified case-crossover study.

Science.gov (United States)

Yorifuji, Takashi; Suzuki, Etsuji; Kashima, Saori

2014-08-13

Epidemiological studies have shown adverse effects of short-term exposure to air pollution on respiratory disease outcomes; however, few studies examined this association on an hourly time scale. We evaluated the associations between hourly changes in air pollution and the risk of respiratory disease in the elderly, using the time of the emergency call as the disease onset for each case. We used a time-stratified case-crossover design. Study participants were 6,925 residents of the city of Okayama, Japan, aged 65 or above who were taken to hospital emergency rooms between January 2006 and December 2010 for onset of respiratory disease. We calculated city-representative hourly average concentrations of air pollutants from several monitoring stations. By using conditional logistic regression models, we estimated odds ratios per interquartile-range increase in each pollutant by exposure period prior to emergency call, adjusting for hourly ambient temperature, hourly relative humidity, and weekly numbers of reported influenza cases aged ≥60. Suspended particulate matter (SPM) exposure 24 to respiratory disease. For example, following one interquartile-range increase, odds ratios were 1.05 (95% confidence interval: 1.01, 1.09) for SPM exposure 24 to respiratory disease of SPM or ozone. Overall, the effect estimates for chronic obstructive pulmonary disease and allied conditions were equivocal. This study provides further evidence that hourly changes in air pollution exposure increase the risks of respiratory disease, and that SO2 may be related with more immediate onset of the disease than other pollutants.

Investigating the associations between work hours, sleep status, and self-reported health among full-time employees.

Science.gov (United States)

Nakata, Akinori

2012-04-01

The extent to which work hours and sleep are associated with self-rated health (SRH) was investigated in full-time employees of small- and medium-scale businesses (SMBs) in a suburb of Tokyo. A total of 2,579 employees (1,887 men and 692 women), aged 18-79 (mean 45) years, in 296 SMBs were surveyed using a self-administered questionnaire from August to December 2002. Work hours, sleep, and SRH were evaluated. Compared with those working 6-8 h/day, participants working >8 to 10 h/day and >10 h/day had significantly higher odds of suboptimal SRH [adjusted odds ratio (aOR) 1.36 and 1.87, respectively]. Similarly, compared with those sleeping 6+ h/day and sufficient sleep, participants with short sleep (work hours with short sleep (aOR 3.30) or insufficient sleep (aOR 3.40) exerted synergistic negative associations on SRH. This study suggests that long work hours and poor sleep and its combination are associated with suboptimal SRH.

Training for the future NHS: training junior doctors in the United Kingdom within the 48-hour European working time directive.

Science.gov (United States)

Datta, Shreelatta T; Davies, Sally J

2014-01-01

Since August 2009, the National Health Service of the United Kingdom has faced the challenge of delivering training for junior doctors within a 48-hour working week, as stipulated by the European Working Time Directive and legislated in the UK by the Working Time Regulations 1998. Since that time, widespread concern has been expressed about the impact of restricted duty hours on the quality of postgraduate medical training in the UK, particularly in the "craft" specialties--that is, those disciplines in which trainees develop practical skills that are best learned through direct experience with patients. At the same time, specialist training in the UK has experienced considerable change since 2007 with the introduction of competency-based specialty curricula, workplace-based assessment, and the annual review of competency progression. The challenges presented by the reduction of duty hours include increased pressure on doctors-in-training to provide service during evening and overnight hours, reduced interaction with supervisors, and reduced opportunities for learning. This paper explores these challenges and proposes potential responses with respect to the reorganization of training and service provision.

Observations of fast variable objects

International Nuclear Information System (INIS)

Alekseev, G.N.

1978-01-01

A problem on studying fast variable astronomic objects is considered. The basis of the method used in the experiment is a detailed photoelectric study of a fast variableness along with spectroscopy of a high time resolution. Power spectrum of the SS Cyg brightness oscillations and autocorrelation function of the AX Mon brightness are analyzed as an example. To provide a reliable identification of parameters of star active regions responsible for the fast variableness, an experiment is proposed, the ''synchronous spectroscopy'' method being used. The method is based on the supposition about temporary stationarity of occasional processes within the limits of the time scale of several hours. The block diagram of the experiment is described

Living hours under pressure

DEFF Research Database (Denmark)

Ilsøe, Anna; Larsen, Trine Pernille; Felbo-Kolding, Jonas

2017-01-01

Purpose The purpose of this paper is to investigate the effect of part-time work on absolute wages. The empirical focus is wages and working hours in three selected sectors within private services in the Danish labour market – industrial cleaning, retail, hotels and restaurants – and their agreem......Purpose The purpose of this paper is to investigate the effect of part-time work on absolute wages. The empirical focus is wages and working hours in three selected sectors within private services in the Danish labour market – industrial cleaning, retail, hotels and restaurants...... in industrial cleaning includes a minimum floor of 15 weekly working hours – this is not the case in retail, hotels and restaurants. This creates a loophole in the latter two sectors that can be exploited by employers to gain wage flexibility through part-time work. Originality/value The living wage literature...

Time series linear regression of half-hourly radon levels in a residence

International Nuclear Information System (INIS)

Hull, D.A.

1990-01-01

This paper uses time series linear regression modelling to assess the impact of temperature and pressure differences on the radon measured in the basement and in the basement drain of a research house in the Princeton area of New Jersey. The models examine half-hour averages of several climate and house parameters for several periods of up to 11 days. The drain radon concentrations follow a strong diurnal pattern that shifts 12 hours in phase between the summer and the fall seasons. This shift can be linked both to the change in temperature differences between seasons and to an experiment which involved sealing the connection between the drain and the basement. We have found that both the basement and the drain radon concentrations are correlated to basement-outdoor and soil-outdoor temperature differences (the coefficient of determination varies between 0.6 and 0.8). The statistical models for the summer periods clearly describe a physical system where the basement drain pumps radon in during the night and sucks radon out during the day

Working hours and all-cause mortality in relation to the EU Working Time Directive: a Danish cohort study.

Science.gov (United States)

Hannerz, Harald; Soll-Johanning, Helle

2018-03-12

In keeping with the need to protect the safety and health of workers, the EU Working Time Directive stipulates that a worker's average working time for each 7-day period, including overtime, does not exceed 48 h. It has, however, not been settled whether or not the threshold at 48 working hours a week is low enough to protect against excess mortality from long work weeks. The aim of the present study was to examine all-cause mortality in relation to weekly working hours among employees in the general population of Denmark. A special attention was given to mortality rates among employees with moderately long work weeks, 41-48 h. Interview data from cohorts of 20-64 year-old employees were drawn from the Danish Labour Force Survey. The participants (N = 159 933) were followed through national registers from the end of the calendar year of the interview (1999-2013) until the end of 2014. Rate ratios (RRs) for all-cause mortality were estimated as a function of weekly working hours while controlling for age, sex, social class, night-time work and calendar year. We found 3374 deaths during an average follow-up time of 7.7 years. With 32-40 working hours a week as reference, the RRs for all-cause mortality were 0.75 (95% CI: 0.66-0.85) for 41-48 and 0.92 (0.80-1.05) for >48 h. Mortality rates in Denmark are significantly lower among employees with moderately long work weeks than they are among full-time employees without overtime work.

Impact of Age and Hearing Impairment on Work Performance during Long Working Hours

Directory of Open Access Journals (Sweden)

Verena Wagner-Hartl

2018-01-01

Full Text Available Based on demographic prognoses, it must be assumed that a greater number of older workers will be found in the future labor market. How to deal with their possible age-related impairments of sensory functions, like hearing impairment and work performance during extended working time, has not been addressed explicitly until now. The study addresses this interplay. The study was performed on two consecutive days after normal working hours. The 55 participants had to “work” in the study at least three additional hours to simulate a situation of long working hours. The tested measures for (job performance were: general attention, long-term selective attention, concentration, and reaction time. All of the investigated variables were taken at both days of the study (2 × 2 × 2 repeated measurement design. The results show effects for age, the interaction of hearing impairment and time of measurement, and effects of the measurement time. Older participants reacted slower than younger participants did. Furthermore, younger participants reacted more frequently in a correct way. Hearing impairment seems to have a negative impact especially on measures of false reactions, and therefore especially on measurement time 1. The results can be interpreted in a way that hearing-impaired participants are able to compensate their deficits over time.

Impact of Age and Hearing Impairment on Work Performance during Long Working Hours.

Science.gov (United States)

Wagner-Hartl, Verena; Grossi, Nina R; Kallus, K Wolfgang

2018-01-09

Based on demographic prognoses, it must be assumed that a greater number of older workers will be found in the future labor market. How to deal with their possible age-related impairments of sensory functions, like hearing impairment and work performance during extended working time, has not been addressed explicitly until now. The study addresses this interplay. The study was performed on two consecutive days after normal working hours. The 55 participants had to "work" in the study at least three additional hours to simulate a situation of long working hours. The tested measures for (job) performance were: general attention, long-term selective attention, concentration, and reaction time. All of the investigated variables were taken at both days of the study (2 × 2 × 2 repeated measurement design). The results show effects for age, the interaction of hearing impairment and time of measurement, and effects of the measurement time. Older participants reacted slower than younger participants did. Furthermore, younger participants reacted more frequently in a correct way. Hearing impairment seems to have a negative impact especially on measures of false reactions, and therefore especially on measurement time 1. The results can be interpreted in a way that hearing-impaired participants are able to compensate their deficits over time.

Breaking the Long Hours Culture.

Science.gov (United States)

Kodz, J.; Kersley, B.; Strebler, M. T.; O'Regan, S.

Case studies of 12 leading British employers were driven by employers' interest in issues related to working long hours in light of introduction of the Working Time Directive, a European Community initiative enacted into British law that sets limits on working hours per week. Data showed over one-fourth of full-time employees worked over 48 hours…

Relative value of clinical variables, bicycle ergometry, rest radionuclide ventriculography and 24 hour ambulatory electrocardiographic monitoring at discharge to predict 1 year survival after myocardial infarction

NARCIS (Netherlands)

P.M. Fioretti (Paolo); R.W. Brower (Ronald); M.L. Simoons (Maarten); H.J. ten Katen (Harald); A. Beelen (Anita); T. Baardman (Taco); J. Lubsen (Jacob); P.G. Hugenholtz (Paul)

1986-01-01

textabstractThe relative value of predischarge clinical variables, bicycle ergometry, radionuclide ventriculography and 24 hour ambulatory electrocardiographic monitoring for predicting survival during the first year in 351 hospital survivors of acute myocardial infarction was assessed. Discriminant

Analysis and comparison of safety models using average daily, average hourly, and microscopic traffic.

Science.gov (United States)

Wang, Ling; Abdel-Aty, Mohamed; Wang, Xuesong; Yu, Rongjie

2018-02-01

There have been plenty of traffic safety studies based on average daily traffic (ADT), average hourly traffic (AHT), or microscopic traffic at 5 min intervals. Nevertheless, not enough research has compared the performance of these three types of safety studies, and seldom of previous studies have intended to find whether the results of one type of study is transferable to the other two studies. First, this study built three models: a Bayesian Poisson-lognormal model to estimate the daily crash frequency using ADT, a Bayesian Poisson-lognormal model to estimate the hourly crash frequency using AHT, and a Bayesian logistic regression model for the real-time safety analysis using microscopic traffic. The model results showed that the crash contributing factors found by different models were comparable but not the same. Four variables, i.e., the logarithm of volume, the standard deviation of speed, the logarithm of segment length, and the existence of diverge segment, were positively significant in the three models. Additionally, weaving segments experienced higher daily and hourly crash frequencies than merge and basic segments. Then, each of the ADT-based, AHT-based, and real-time models was used to estimate safety conditions at different levels: daily and hourly, meanwhile, the real-time model was also used in 5 min intervals. The results uncovered that the ADT- and AHT-based safety models performed similar in predicting daily and hourly crash frequencies, and the real-time safety model was able to provide hourly crash frequency. Copyright © 2017 Elsevier Ltd. All rights reserved.

A model for estimating pathogen variability in shellfish and predicting minimum depuration times.

Science.gov (United States)

McMenemy, Paul; Kleczkowski, Adam; Lees, David N; Lowther, James; Taylor, Nick

2018-01-01

Norovirus is a major cause of viral gastroenteritis, with shellfish consumption being identified as one potential norovirus entry point into the human population. Minimising shellfish norovirus levels is therefore important for both the consumer's protection and the shellfish industry's reputation. One method used to reduce microbiological risks in shellfish is depuration; however, this process also presents additional costs to industry. Providing a mechanism to estimate norovirus levels during depuration would therefore be useful to stakeholders. This paper presents a mathematical model of the depuration process and its impact on norovirus levels found in shellfish. Two fundamental stages of norovirus depuration are considered: (i) the initial distribution of norovirus loads within a shellfish population and (ii) the way in which the initial norovirus loads evolve during depuration. Realistic assumptions are made about the dynamics of norovirus during depuration, and mathematical descriptions of both stages are derived and combined into a single model. Parameters to describe the depuration effect and norovirus load values are derived from existing norovirus data obtained from U.K. harvest sites. However, obtaining population estimates of norovirus variability is time-consuming and expensive; this model addresses the issue by assuming a 'worst case scenario' for variability of pathogens, which is independent of mean pathogen levels. The model is then used to predict minimum depuration times required to achieve norovirus levels which fall within possible risk management levels, as well as predictions of minimum depuration times for other water-borne pathogens found in shellfish. Times for Escherichia coli predicted by the model all fall within the minimum 42 hours required for class B harvest sites, whereas minimum depuration times for norovirus and FRNA+ bacteriophage are substantially longer. Thus this study provides relevant information and tools to assist

Work hours, sleep sufficiency, and prevalence of depression among full-time employees: a community-based cross-sectional study.

Science.gov (United States)

Nakata, Akinori

2011-05-01

Depression due to long work hours and sleep deprivation is a major occupational health concern. The extent to which work hours and sleep are associated with depression was investigated in employees of small- and medium-scale businesses in the Japanese city of Yashio, Saitama, and in the Ohta ward of Tokyo, a suburb of Tokyo, controlling for various potential confounders. In this cross-sectional study, a total of 2,643 full-time employees (1,928 men and 715 women), aged 18-79 years (mean = 45 years), in 296 small- and medium-scale businesses were surveyed from August 2002 to December 2002 using a self-administered questionnaire evaluating work hours, sleep status, and covariates including sociodemographic and socioeconomic factors, health behaviors, biological factors, medication usage, and occupational factors. Depression was assessed using the Center for Epidemiologic Studies Depression Scale. Prevalence of depression by work hours, sleep status, and covariates was analyzed by χ² test. Risk of depression by work hours, sleep status, and both combined was estimated by multivariate logistic regression analysis. Participants working > 10 hours per day, sleeping hours per day, and reporting insufficient sleep were, respectively, 37%, 43%, and 97% more likely to be depressed than those working 6 to 8 hours per day, sleeping 6 to hours per day, and reporting sufficient sleep (P working > 10 hours per day or > 8 to 10 hours per day with hours per day of sleep showed a 41%-169% higher prevalence of depression versus those working 6 to 8 hours per day with 6+ hours per day of sleep (P work-hour categories (6 to 8, > 8 to 10, and > 10 hours per day) showed a 62%-179% increase in the prevalence of depression versus those working 6 to 8 hours per day and reporting sufficient sleep (P work-hour category with 6+ hours of sleep or with subjective sufficient sleep. Depression associated with long work hours is primarily a result of sleep deprivation. Greater attention should be

Vigorous physical activity predicts higher heart rate variability among younger adults.

Science.gov (United States)

May, Richard; McBerty, Victoria; Zaky, Adam; Gianotti, Melino

2017-06-14

Baseline heart rate variability (HRV) is linked to prospective cardiovascular health. We tested intensity and duration of weekly physical activity as predictors of heart rate variability in young adults. Time and frequency domain indices of HRV were calculated based on 5-min resting electrocardiograms collected from 82 undergraduate students. Hours per week of both moderate and vigorous activity were estimated using the International Physical Activity Questionnaire. In regression analyses, hours of vigorous physical activity, but not moderate activity, significantly predicted greater time domain and frequency domain indices of heart rate variability. Adjusted for weekly frequency, greater daily duration of vigorous activity failed to predict HRV indices. Future studies should test direct measurements of vigorous activity patterns as predictors of autonomic function in young adulthood.

Pulse timing for cataclysmic variables

International Nuclear Information System (INIS)

Chester, T.J.

1979-01-01

It is shown that present pulse timing measurements of cataclysmic variables can be explained by models of accretion disks in these systems, and thus such measurements can constrain disk models. The model for DQ Her correctly predicts the amplitude variation of the continuum pulsation and can also perhaps explain the asymmetric amplitude of the pulsed lambda4686 emission line. Several other predictions can be made from the model. In particular, if pulse timing measurements that resolve emission lines both in wavelength and in binary phase can be made, the projected orbital radius of the white dwarf could be deduced

Working hours and common mental disorders in English police officers.

Science.gov (United States)

Houdmont, J; Randall, R

2016-12-01

There is a paucity of evidence on working hours and their psychological correlates in police officers of the federated ranks in England. An exploratory study to establish the extent to which a sample of English police officers worked long hours and the association between long working hours and common mental disorder (CMD). Officers of the federated ranks (constable, sergeant, inspector) from two English county forces completed a questionnaire to report their typical weekly working hours and symptoms of CMD. We also collected socio- and occupational-demographic data. We defined long working hours as ≥49 h in a typical week in accordance with 48-h weekly limit specified in the 1993 European Directive on the Organisation of Working Time. We established associations between long working hours and self-reported CMDs using binary logistic regression to generate odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for potential confounding variables. Twenty-seven per cent (n = 327/1226) of respondents reported long working hours. The ORs for psychological distress (OR 2.05, 95% CI 1.57-2.68), emotional exhaustion (OR 1.99, 95% CI 1.52-2.59), and depersonalization (OR 1.30, 95% CI 1.00-1.71) were significantly increased for long working hours after adjustment for socio- and occupational-demographic characteristics. More than one quarter of sampled police officers reported working long hours and were significantly more likely to report CMD. National and longitudinal research is required to confirm these findings, which suggest management of working hours may effectively promote psychological well-being. © The Author 2016. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

distribution of hourly variability index of sky clearness

African Journals Online (AJOL)

Mgina

Clouds affect the values of insolation for solar technology and other applications. To detect the presence of variability in the sky ... It appears that the site has great potential for application of solar technologies. INTRODUCTION. Knowledge about the .... for solar collectors-part 1. Thermal performance of glazed liquid heating.

76 FR 44884 - Federal Acquisition Regulation; Payments Under Time-and-Materials and Labor-Hour Contracts

Science.gov (United States)

2011-07-27

... under revised Alternate I. (b) Completion Voucher. The Allowable Cost and Payment, FAR clause 52.216-7.... * * * * * Payments Under Time-and-Material and Labor-Hour Contracts (Date) * * * * * (a) * * * (5) Vouchers may be... final payment under this contract, the Contracting Officer may request audit of the vouchers and...

Cross-National Differences in the Association Between Parental Work Hours and Time with Children in Europe: A Multilevel Analysis.

Science.gov (United States)

Roeters, Anne

2013-01-01

This study investigates cross-national differences in the association between parental work hours and parent-child interaction time and explains differences in this individual-level association on the basis of country characteristics. It extends prior research by testing the moderating effects of country characteristics through multilevel analyses and by considering the possibility of selection effects. The presumption was that parents employ strategies to protect family life from work encroachments and that these strategies are enhanced by reconciliation policies, stronger parenthood ideologies, access to part-time work and higher income levels. Multilevel analyses were based on a subset of 5.183 parents in 23 countries from the 2005 European Working Conditions Survey that was complemented with country-level data. The negative association between parental work hours and parent-child time indeed varied significantly across countries and was weaker in countries where formal child care coverage was higher, part-time work was less prevalent, and earnings were lower. The effects of part-time work and earnings mainly applied to mothers. These findings suggest that child care coverage limits the availability of children and that differences in parent-child time between parents who work short and long hours are more pronounced when part-time work is more accessible and affordable.

Working hours: Past, present, and future

OpenAIRE

Dolton, Peter

2017-01-01

Working hours across the world are falling, but considerable variation remains. In some countries people work 70% more hours per year, on average, than in other countries. Much of this variation is due to differences in the prevalence of part-time work and patterns of female labor market participation. Looking ahead, the question of how reducing working hours will affect productivity is significant. In addition, how individuals divide up their leisure and work time and what the appropriate wo...

Who gains from hourly time-of-use retail prices on electricity? An analysis of consumption profiles for categories of Danish electricity customers

DEFF Research Database (Denmark)

Møller Andersen, Frits; Larsen, Helge V.; Kitzing, Lena

2014-01-01

include a systematic component in the hourly variation, we show that customers with different consumption profiles experience different average cost of their electricity consumption when billed according to hourly time-of-use prices. Thus, some categories of customers stand to gain from time......Studies of the aggregated hourly electricity load in geographical areas typically show a systematic variation over the day, the week, and seasons. With hourly metering of individual customers, data for individual consumption profiles have become available. Looking into these data we show...... that consumption profiles for specific categories of customers are equally systematic but quite distinct for different categories of customers. That is, different categories of customers contribute quite differently to the aggregated load profile. Coupling consumption profiles with hourly market prices which also...

Bottleneck congestion and distribution of work start times: The economics of staggered work hours revisited

OpenAIRE

Takayama, Yuki

2014-01-01

Since the seminal work of Henderson (1981), a number of studies examined the effect of staggered work hours by analyzing models of work start time choice that consider the trade-off between negative congestion externalities and positive production externalities. However, these studies described traffic congestion using flow congestion models. This study develops a model of work start time choice with bottleneck congestion and discloses the intrinsic properties of the model. To this end, this ...

Predicting Patients with Inadequate 24- or 48-Hour Urine Collections at Time of Metabolic Stone Evaluation.

Science.gov (United States)

McGuire, Barry B; Bhanji, Yasin; Sharma, Vidit; Frainey, Brendan T; McClean, Megan; Dong, Caroline; Rimar, Kalen; Perry, Kent T; Nadler, Robert B

2015-06-01

We aimed to understand the characteristics of patients who are less likely to submit adequate urine collections at metabolic stone evaluation. Inadequate urine collection was defined using two definitions: (1) Reference ranges for 24-hour creatinine/kilogram (Cr/24) and (2) discrepancy in total 24-hour urine Cr between 24-hour urine collections. There were 1502 patients with ≥1 kidney stone between 1998 and 2014 who performed a 24- or 48-hour urine collection at Northwestern Memorial Hospital and who were identified retrospectively. Multivariate analysis was performed to analyze predictor variables for adequate urine collection. A total of 2852 urine collections were analyzed. Mean age for males was 54.4 years (range 17-86), and for females was 50.2 years (range 8-90). One patient in the study was younger than 17 years old. (1) Analysis based on the Cr 24/kg definition: There were 50.7% of patients who supplied an inadequate sample. Females were nearly 50% less likely to supply an adequate sample compared with men, Pcollections were achieved in 82.8%, 66.9%, 51.7%, 38.5%, and 26.4% of patients, respectively. Statistical significance was observed based on differences of ≥40%, and this was defined as the threshold for an inadequate sample. Female sex (OR 0.73 [0.54-0.98], P=0.037) predicted supplying inadequate samples. Adequate collections were more likely to be received on a Sunday (OR 1.6 [1.03-2.58], P=0.038) and by sedentary workers (OR 2.3 [1.12-4.72], P=0.023). Urine collections from patients during metabolic evaluation for nephrolithiasis may be considered inadequate based on two commonly used clinical definitions. This may have therapeutic or economic ramifications and the propensity for females to supply inadequate samples should be investigated further.

Variability in the behavior of kids born of primiparous goats during the first hour after parturition: effect of the type of parturition, sex, duration of birth, and maternal behavior.

Science.gov (United States)

Martínez, M; Otal, J; Ramírez, A; Hevia, M L; Quiles, A

2009-05-01

The aim of the study was to determine the effect of the type of birth, the sex of the kids, the duration of the birth (categorized as short, medium, or long), and the level of maternal care (categorized as low, medium, or high) on the behavioral variables of kids during the first hour after birth. The parturitions of 78 primiparous goats of Murciano-Granadina breed (46 single-birth and 32 twin-birth) along with the behavior of the kids (44 males and 66 females) during the first hour of life were studied. Birth weight and duration of parturition were greater in single-birth kids (2.94 kg and 60.5 min, respectively) than in twin-birth kids (2.27 kg and 43.2 min, respectively). Birth weight and duration of parturition was greater in males (2.74 kg and 54.61 min) than in females (2.43 kg and 47.70 min). All the kids attempted to stand during the first hour of life, but only 83% attempted to suckle with 65% succeeding. Single-birth kids attempted to stand earlier than twin-birth kids (7.05 vs. 9.08 min), although they achieved this later (16.87 vs. 13.21 min). Compared with twin-birth kids, single-birth kids attempted to suckle later (22.45 vs. 34.76 min, respectively) and achieved it later (25.69 vs. 37.32 min). In the single-birth kids the duration of the first suckling was shorter (16.11 vs. 22.26 s), although total suckling time was greater (5.86 min) than in the twin-birth kids. Males tried to stand sooner than females (7.41 vs. 8.78 min), but took longer (16.12 vs. 13.81 min). The sex factor had no significant effect on suckling-related variables. Compared with medium- and long-duration-birth kids, short-duration-birth kids attempted to suckle earlier, (29.34, 34.23, and 12.82 min, respectively), achieved suckling earlier (31.75, 37.00, and 16.70 min, respectively), and suckled longer at first attempt (0.32, 0.17, and 0.45 min, respectively). Total suckling time was longer in long-duration-birth kids than in medium- and short-duration birth (9.07, 2.63, and 3

Work time control and mental health of workers working long hours: the role of gender and age.

Science.gov (United States)

Zołnierczyk-Zreda, Dorota; Bedyńska, Sylwia; Warszewska-Makuch, Magdalena

2012-01-01

The aim of this study was to examine the relationship between work time control and mental health in workers working long hours. The study also attempted to show how that relationship depended on age and gender. Three hundred and six white-collar workers doing clerical work for over 8 h daily were diagnosed on work time control and mental health with the 28-item General Health Questionnaire. The results of an analysis of variance (ANOVA) showed that participants working long hours but having high control over their work time had a significantly higher level of their mental health with regard to somatic complaints and anxiety and marginally higher with regard to social dysfunction than workers with low control over their work time. Male and female workers reported different problems with their mental health depending on what age (stage of life) they were at. It is hypothesized that the work-family conflict, inability to fulfil social commitments and poor working conditions can influence those effects.

Towards a More Biologically-meaningful Climate Characterization: Variability in Space and Time at Multiple Scales

Science.gov (United States)

Christianson, D. S.; Kaufman, C. G.; Kueppers, L. M.; Harte, J.

2013-12-01

Sampling limitations and current modeling capacity justify the common use of mean temperature values in summaries of historical climate and future projections. However, a monthly mean temperature representing a 1-km2 area on the landscape is often unable to capture the climate complexity driving organismal and ecological processes. Estimates of variability in addition to mean values are more biologically meaningful and have been shown to improve projections of range shifts for certain species. Historical analyses of variance and extreme events at coarse spatial scales, as well as coarse-scale projections, show increasing temporal variability in temperature with warmer means. Few studies have considered how spatial variance changes with warming, and analysis for both temporal and spatial variability across scales is lacking. It is unclear how the spatial variability of fine-scale conditions relevant to plant and animal individuals may change given warmer coarse-scale mean values. A change in spatial variability will affect the availability of suitable habitat on the landscape and thus, will influence future species ranges. By characterizing variability across both temporal and spatial scales, we can account for potential bias in species range projections that use coarse climate data and enable improvements to current models. In this study, we use temperature data at multiple spatial and temporal scales to characterize spatial and temporal variability under a warmer climate, i.e., increased mean temperatures. Observational data from the Sierra Nevada (California, USA), experimental climate manipulation data from the eastern and western slopes of the Rocky Mountains (Colorado, USA), projected CMIP5 data for California (USA) and observed PRISM data (USA) allow us to compare characteristics of a mean-variance relationship across spatial scales ranging from sub-meter2 to 10,000 km2 and across temporal scales ranging from hours to decades. Preliminary spatial analysis at

Travel time variability and airport accessibility

OpenAIRE

Koster, P.R.; Kroes, E.P.; Verhoef, E.T.

2010-01-01

This discussion paper resulted in a publication in Transportation Research Part B: Methodological (2011). Vol. 45(10), pages 1545-1559. This paper analyses the cost of access travel time variability for air travelers. Reliable access to airports is important since it is likely that the cost of missing a flight is high. First, the determinants of the preferred arrival times at airports are analyzed, including trip purpose, type of airport, flight characteristics, travel experience, type of che...

Change from an 8-hour shift to a 12-hour shift, attitudes, sleep, sleepiness and performance.

Science.gov (United States)

Lowden, A; Kecklund, G; Axelsson, J; Akerstedt, T

1998-01-01

The present study sought to evaluate the effect of a change from a rotating 3-shift (8-hour) to a 2-shift shift (12 hour) schedule on sleep, sleepiness, performance, perceived health, and well-being. Thirty-two shift workers at a chemical plant (control room operators) responded to a questionnaire a few months before a change was made in their shift schedule and 10 months after the change. Fourteen workers also filled out a diary, carried activity loggers, and carried out reaction-time tests (beginning and end of shift). Fourteen day workers served as a reference group for the questionnaires and 9 were intensively studied during a week with workdays and a free weekend. The questionnaire data showed that the shift change increased satisfaction with workhours, sleep, and time for social activities. Health, perceived accident risk, and reaction-time performance were not negatively affected. Alertness improved and subjective recovery time after night work decreased. The quick changes in the 8-hour schedule greatly increased sleep problems and fatigue. Sleepiness integrated across the entire shift cycle showed that the shift workers were less alert than the day workers, across workdays and days off (although alertness increased with the 12-hour shift). The change from 8-hour to 12-hour shifts was positive in most respects, possibly due to the shorter sequences of the workdays, the longer sequences of consecutive days off, the fewer types of shifts (easier planning), and the elimination of quick changes. The results may differ in groups with a higher work load.

Impact of in or out of office hours at admission time on outcome in out-of-hospital cardiac arrest patients.

Science.gov (United States)

Genbrugge, Cornelia; Viaene, Els; Meex, Ingrid; De Vadder, Katrien; Eertmans, Ward; Boer, Willem; Jans, Frank; De Deyne, Cathy; Dens, Jo; Ferdinande, Bert

2017-08-01

In out-of-hospital cardiac arrest (OHCA), neurological outcome is determined by the severity of neurological injury, early percutaneous coronary intervention, and application of neuroprotective temperature management. As this is a very time-intensive and manpower-intensive protocol, we hypothesized that there would be a difference in outcome between OHCA patients admitted during and out of office hours. We prospectively collected demographic data of OHCA patients in two hospitals. All patients included were treated at 33°C for 24 h, followed by a rewarming phase until 36.6°C. During office hours were defined as arriving between 8:00 a.m. and 5:00 p.m. on weekdays. Neurological outcome at 180 days was assessed following the Cerebral Performance Category scale. Forty-seven (31%) patients were admitted during office hours and 105 (69%) out of office hours (P=0.199). Patients admitted during office hours were significantly older, respectively, 66±14 and 59±15 years (P=0.014). There was no significant difference between both groups in the number of patients who underwent coronary angiography, door to angiography time, and number of affected vessels. The median time spent in the target range of PaO2, PaCO2, and lactate was also not significantly different. We found no significant difference in survival until 180 days between both groups (P=0.599), even after adjustment for age (95% confidence interval: 0.44-1.90, hazard ratio: 0.912). Survival until 180 days between OHCA patients admitted during office hours or out of office hours was not significantly different in two hospitals with a fixed protocol for neuroprotection and 24/7 streamlined access to coronary angiography.

Energy and Reserve under Distributed Energy Resources Management-Day-Ahead, Hour-Ahead and Real-Time

DEFF Research Database (Denmark)

Soares, Tiago; Silva, Marco; Sousa, Tiago

2017-01-01

and evaluates a generic model for day-ahead, intraday (hour-ahead) and real-time scheduling, considering the joint optimization of energy and reserve in the scope of the virtual power player concept. The model aims to minimize the operation costs in the point of view of one aggregator agent taking into account...

Variability of Travel Times on New Jersey Highways

Science.gov (United States)

2011-06-01

This report presents the results of a link and path travel time study conducted on selected New Jersey (NJ) highways to produce estimates of the corresponding variability of travel time (VTT) by departure time of the day and days of the week. The tra...

The existence and persistence of long work hours

OpenAIRE

Drago, Robert William; Black, David; Wooden, Mark

2005-01-01

Previous research hypothesizes that long working hours are related to consumerism, the ideal worker norm, high levels of human capital, and a high cost-of-job-loss. The authors test these hypotheses using panel data on working hours for an Australian sample of full-time employed workers. Analyses include a static cross-sectional model and a persistence model for long hours over time. The results suggest that long hours (50 or more hours in a usual week) are often persistent, and provide stron...

Variability of gastric emptying time using standardized radiolabeled meals

International Nuclear Information System (INIS)

Christian, P.E.; Brophy, C.M.; Egger, M.J.; Taylor, A.; Moore, J.G.

1984-01-01

To define the range of inter- and intra-subject variability on gastric emptying measurements, eight healthy male subjects (ages 19-40) received meals on four separate occasions. The meal consisted of 150 g of beef stew labeled with Tc-99m SC labeled liver (600 μCi) and 150 g of orange juice containing In-111 DTPA (100 μCi) as the solid- and liquid-phase markers respectively. Images of the solid and liquid phases were obtained at 20 min intervals immediately after meal ingestion. The stomach region was selected from digital images and data were corrected for radionuclide interference, radioactive decay and the geometric mean of anterior and posterior counts. More absolute variability was seen with the solid than the liquid marker emptying for the group. The mean solid half-emptying time was 58 +- 17 min (range 29-92) while the mean liquid half-emptying time was 24 +- 8 min (range 12-37). A nested random effects analysis of variance showed moderate intra-subject variability for solid half-emptying times (rho = 0.4594), and high intra-subject variability was implied by a low correlation (rho = 0.2084) for liquid half-emptying. The average inter-subject differences were 58.3% of the total variance for solids (rho = 0.0017). For liquids, the inter-subject variability was 69.1% of the total variance, but was only suggestive of statistical significance (rho = 0.0666). The normal half emptying time for gastric emptying of liquids and solids is a variable phenomenon in healthy subjects and has great inter- and intra-individual day-to-day differences

Variability of gastric emptying time using standardized radiolabeled meals

Energy Technology Data Exchange (ETDEWEB)

Christian, P.E.; Brophy, C.M.; Egger, M.J.; Taylor, A.; Moore, J.G.

1984-01-01

To define the range of inter- and intra-subject variability on gastric emptying measurements, eight healthy male subjects (ages 19-40) received meals on four separate occasions. The meal consisted of 150 g of beef stew labeled with Tc-99m SC labeled liver (600 ..mu..Ci) and 150 g of orange juice containing In-111 DTPA (100 ..mu..Ci) as the solid- and liquid-phase markers respectively. Images of the solid and liquid phases were obtained at 20 min intervals immediately after meal ingestion. The stomach region was selected from digital images and data were corrected for radionuclide interference, radioactive decay and the geometric mean of anterior and posterior counts. More absolute variability was seen with the solid than the liquid marker emptying for the group. The mean solid half-emptying time was 58 +- 17 min (range 29-92) while the mean liquid half-emptying time was 24 +- 8 min (range 12-37). A nested random effects analysis of variance showed moderate intra-subject variability for solid half-emptying times (rho = 0.4594), and high intra-subject variability was implied by a low correlation (rho = 0.2084) for liquid half-emptying. The average inter-subject differences were 58.3% of the total variance for solids (rho = 0.0017). For liquids, the inter-subject variability was 69.1% of the total variance, but was only suggestive of statistical significance (rho = 0.0666). The normal half emptying time for gastric emptying of liquids and solids is a variable phenomenon in healthy subjects and has great inter- and intra-individual day-to-day differences.

Precarious employment, working hours, work-life conflict and health in hotel work.

Science.gov (United States)

McNamara, Maria; Bohle, Philip; Quinlan, Michael

2011-01-01

Precarious or temporary work is associated with adverse outcomes including low control over working hours, work-life conflict and stress. The rise in precarious employment is most marked in the service sector but little research has been done on its health effects in this sector. This study compares permanent and temporary workers in the hotel industry, where working hours are highly variable. Survey data from 150 workers from eight 3-Star hotels in urban and regional areas around Sydney were analyzed. Forty-five per cent were male and 52 per cent were female. Fifty four per cent were permanent full-time and 46 per cent were temporary workers. The effects of employment status on perceived job security, control over working hours, and work-life conflict are investigated using PLS-Graph 3.0. The effects of control over working hours, on work-life conflict and subsequent health outcomes are also explored. Temporary workers perceived themselves as less in control of their working hours, than permanent workers (β = .27). However, they also reported lower levels of work intensity (β = .25) and working hours (β = .38). The effects of low hours control (β = .20), work intensity (β = .29), and excessive hours (β = .39) on work-life conflict (r² = .50), and subsequent health effects (r² = .30), are illustrated in the final structural equation model. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Sources of variability and systematic error in mouse timing behavior.

Science.gov (United States)

Gallistel, C R; King, Adam; McDonald, Robert

2004-01-01

In the peak procedure, starts and stops in responding bracket the target time at which food is expected. The variability in start and stop times is proportional to the target time (scalar variability), as is the systematic error in the mean center (scalar error). The authors investigated the source of the error and the variability, using head poking in the mouse, with target intervals of 5 s, 15 s, and 45 s, in the standard procedure, and in a variant with 3 different target intervals at 3 different locations in a single trial. The authors conclude that the systematic error is due to the asymmetric location of start and stop decision criteria, and the scalar variability derives primarily from sources other than memory.

Variability in reaction time performance of younger and older adults.

Science.gov (United States)

Hultsch, David F; MacDonald, Stuart W S; Dixon, Roger A

2002-03-01

Age differences in three basic types of variability were examined: variability between persons (diversity), variability within persons across tasks (dispersion), and variability within persons across time (inconsistency). Measures of variability were based on latency performance from four measures of reaction time (RT) performed by a total of 99 younger adults (ages 17--36 years) and 763 older adults (ages 54--94 years). Results indicated that all three types of variability were greater in older compared with younger participants even when group differences in speed were statistically controlled. Quantile-quantile plots showed age and task differences in the shape of the inconsistency distributions. Measures of within-person variability (dispersion and inconsistency) were positively correlated. Individual differences in RT inconsistency correlated negatively with level of performance on measures of perceptual speed, working memory, episodic memory, and crystallized abilities. Partial set correlation analyses indicated that inconsistency predicted cognitive performance independent of level of performance. The results indicate that variability of performance is an important indicator of cognitive functioning and aging.

A comparison of various forecasting techniques applied to mean hourly wind speed time series

Energy Technology Data Exchange (ETDEWEB)

Sfetsos, A. [7 Pirsou Street, Athens (Greece)

2000-09-01

This paper presents a comparison of various forecasting approaches, using time series analysis, on mean hourly wind speed data. In addition to the traditional linear (ARMA) models and the commonly used feed forward and recurrent neural networks, other approaches are also examined including the Adaptive Neuro-Fuzzy Inference Systems (ANFIS) and Neural Logic Networks. The developed models are evaluated for their ability to produce accurate and fast forecasts. (Author)

Influence of the time of day and fasting duration on glucose level following a 1-hour, 50-gram glucose challenge test in pregnant women.

Directory of Open Access Journals (Sweden)

Panchalli Wang

Full Text Available BACKGROUND: Previous studies have shown that the time of day (TD of glucose measurement and the fasting duration (FD influence the glucose levels in adults. Few studies have examined the effects of the TD and FD on the glucose level following a 1-hour, 50-gram glucose challenge test (GCT in pregnant women in screening for or diagnosing gestational diabetes mellitus (GDM. The objective of this study was to investigate the influence of the TD (morning, afternoon, night and the FD (the time of the last food ingestion as follows: ≤1 hour, 1-2 hours, and >2 hours by examining their combined effects on the glucose levels following a 50-gram GCT in pregnant women. METHODS AND RESULTS: We analyzed the data of 1,454 non-diabetic pregnant Taiwanese women in a prospective study. Multiple linear regression and multiple logistic regression were used to estimate the relationships between the 9 TD-FD groups and the continuous and binary glucose levels (cut-off at 140 mg/dL following a 50-gram GCT, after adjusting for maternal age, nulliparity, pre-pregnancy body mass index, and weight gain. Different TD and FD groups were associated with variable glucose responses to the 50-gram GCT, some of which were significant. The estimate coefficients (β of the TD-FD groups "night, ≤1 hr" and "night, 1-2 hr" revealed significantly lower glucose concentrations [β (95% confidence interval [CI]: -6.46 (-12.53, -0.38 and -6.85 (-12.50, -1.20] compared with the "morning, >2 hr" group. The TD-FD groups "afternoon, ≤1 hr" and "afternoon, 1-2 hr" showed significantly lower odds ratios (OR of a positive GCT; the adjusted ORs (95% CI were 0.54 (0.31-0.95 and 0.58 (0.35-0.96, respectively. CONCLUSIONS: Our findings demonstrate the importance of standardizing the TD and FD for the 1-hour, 50-gram GCT. In screening for and diagnosing GDM, the TD and FD are modifiable factors that should be considered in clinical practice and epidemiological studies.

Can time be a discrete dynamical variable

International Nuclear Information System (INIS)

Lee, T.D.

1983-01-01

The possibility that time can be regarded as a discrete dynamical variable is examined through all phases of mechanics: from classical mechanics to nonrelativistic quantum mechanics, and to relativistic quantum field theories. (orig.)

Time of day variation in polyp detection rate for colonoscopies performed on a 3-hour shift schedule.

LENUS (Irish Health Repository)

Munson, Gregory W

2011-03-01

Recent research suggests that the colonoscopy polyp detection rate (PDR) varies by time of day, possibly because of endoscopist fatigue. Mayo Clinic Rochester (MCR) schedules colonoscopies on 3-hour shifts, which should minimize fatigue.

Using probabilistic finite automata to simulate hourly series of global radiation

Energy Technology Data Exchange (ETDEWEB)

Mora-Lopez, L. [Universidad de Malaga (Spain). Dpto. Lenguajes y Computacion; Sidrach-de-Cardona, M. [Universidad de Malaga (Spain). Dpto. Fisica Aplicada II

2003-03-01

A model to generate synthetic series of hourly exposure of global radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of global radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the ''variable memory'' of cloudiness. A method to generate new series of hourly global radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar global radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties. (author)

Increased error rates in preliminary reports issued by radiology residents working more than 10 consecutive hours overnight.

Science.gov (United States)

Ruutiainen, Alexander T; Durand, Daniel J; Scanlon, Mary H; Itri, Jason N

2013-03-01

To determine if the rate of major discrepancies between resident preliminary reports and faculty final reports increases during the final hours of consecutive 12-hour overnight call shifts. Institutional review board exemption status was obtained for this study. All overnight radiology reports interpreted by residents on-call between January 2010 and June 2010 were reviewed by board-certified faculty and categorized as major discrepancies if they contained a change in interpretation with the potential to impact patient management or outcome. Initial determination of a major discrepancy was at the discretion of individual faculty radiologists based on this general definition. Studies categorized as major discrepancies were secondarily reviewed by the residency program director (M.H.S.) to ensure consistent application of the major discrepancy designation. Multiple variables associated with each report were collected and analyzed, including the time of preliminary interpretation, time into shift study was interpreted, volume of studies interpreted during each shift, day of the week, patient location (inpatient or emergency department), block of shift (2-hour blocks for 12-hour shifts), imaging modality, patient age and gender, resident identification, and faculty identification. Univariate risk factor analysis was performed to determine the optimal data format of each variable (ie, continuous versus categorical). A multivariate logistic regression model was then constructed to account for confounding between variables and identify independent risk factors for major discrepancies. We analyzed 8062 preliminary resident reports with 79 major discrepancies (1.0%). There was a statistically significant increase in major discrepancy rate during the final 2 hours of consecutive 12-hour call shifts. Multivariate analysis confirmed that interpretation during the last 2 hours of 12-hour call shifts (odds ratio (OR) 1.94, 95% confidence interval (CI) 1.18-3.21), cross

Increased timing variability in schizophrenia and bipolar disorder.

Directory of Open Access Journals (Sweden)

Amanda R Bolbecker

Full Text Available Theoretical and empirical evidence suggests that impaired time perception and the neural circuitry underlying internal timing mechanisms may contribute to severe psychiatric disorders, including psychotic and mood disorders. The degree to which alterations in temporal perceptions reflect deficits that exist across psychosis-related phenotypes and the extent to which mood symptoms contribute to these deficits is currently unknown. In addition, compared to schizophrenia, where timing deficits have been more extensively investigated, sub-second timing has been studied relatively infrequently in bipolar disorder. The present study compared sub-second duration estimates of schizophrenia (SZ, schizoaffective disorder (SA, non-psychotic bipolar disorder (BDNP, bipolar disorder with psychotic features (BDP, and healthy non-psychiatric controls (HC on a well-established time perception task using sub-second durations. Participants included 66 SZ, 37 BDNP, 34 BDP, 31 SA, and 73 HC who participated in a temporal bisection task that required temporal judgements about auditory durations ranging from 300 to 600 milliseconds. Timing variability was significantly higher in SZ, BDP, and BDNP groups compared to healthy controls. The bisection point did not differ across groups. These findings suggest that both psychotic and mood symptoms may be associated with disruptions in internal timing mechanisms. Yet unexpected findings emerged. Specifically, the BDNP group had significantly increased variability compared to controls, but the SA group did not. In addition, these deficits appeared to exist independent of current symptom status. The absence of between group differences in bisection point suggests that increased variability in the SZ and bipolar disorder groups are due to alterations in perceptual timing in the sub-second range, possibly mediated by the cerebellum, rather than cognitive deficits.

Space and time evolution of two nonlinearly coupled variables

International Nuclear Information System (INIS)

Obayashi, H.; Totsuji, H.; Wilhelmsson, H.

1976-12-01

The system of two coupled linear differential equations are studied assuming that the coupling terms are proportional to the product of the dependent variables, representing e.g. intensities or populations. It is furthermore assumed that these variables experience different linear dissipation or growth. The derivations account for space as well as time dependence of the variables. It is found that certain particular solutions can be obtained to this system, whereas a full solution in space and time as an initial value problem is outside the scope of the present paper. The system has a nonlinear equilibrium solution for which the nonlinear coupling terms balance the terms of linear dissipation. The case of space and time evolution of a small perturbation of the nonlinear equilibrium state, given the initial one-dimensional spatial distribution of the perturbation, is also considered in some detail. (auth.)

Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide

NARCIS (Netherlands)

Mu, M.; Randerson, J.T; van der Werf, G.R.; Giglio, L.; Kasibhatla, P.; Morton, D.; Collatz, G.J.; DeFries, R.S.; Hyer, E.J.; Prins, E.M.; Griffith, D.; Wunch, D.; Toon, G.C.; Sherlock, V.; Wennberg, P.O.

2011-01-01

Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic-and diurnal-scale temporal variability in fire emissions for

The impact of long working hours on psychosocial stress response among white-collar workers.

Science.gov (United States)

Lee, Kyungjin; Suh, Chunhui; Kim, Jong-Eun; Park, Jae Oh

2017-02-07

This study examined the association between long working hours and psychosocial stress responses. In total, 1,122 white-collar workers from a company in Korea completed self-administered questionnaires following a lecture about the study aim, procedures, and confidentiality. Psychosocial stress responses were evaluated using the Psychosocial Well-being Index - Short Form (PWI-SF), and psychosocial working conditions were evaluated with the Korean Occupational Stress Scale - Short Form (KOSS-SF). Multivariate logistic regression analysis was performed after adjusting for demographic variables and psychosocial working conditions to examine associations between long working hours and psychosocial stress responses. In comparison with the reference group, which worked 40-44 hours per week, the crude odds ratio (OR) of the respondents who worked 60 or more hours was 4.56 (95% confidence interval (CI), 2.55-8.15) in terms of psychosocial stress responses. After adjusting for demographic variables, the adjusted OR of those working ≥60 hours was 5.61 (95% CI, 3.01-10.47). After adjusting for both demographic variables and psychosocial working conditions, the adjusted OR of those working ≥60 hours was 3.25 (95% CI, 1.56-6.79). This study found that long working hours are significantly related to psychosocial stress responses among white-collar workers in one Korean company.

Introduction of summer time system and study of staggered office hours system

Energy Technology Data Exchange (ETDEWEB)

Lee, S I [Korea Energy Economics Institute, Euiwang (Korea, Republic of)

1998-06-01

Summer time system (daylight saving time) was introduced for energy saving during economic crisis such as the World War I and II and oil crisis, and now implemented in seventy (70) countries including advanced countries. In the west, it is perceived as energy saving and enriching leisure activities and family- oriented life. In case implementing it, it is expected to save 8.1% of illuminating light for household use and 5.0% of cooling power for business use on a daily average basis. Besides, the quality of life can be improved since the chance to use more leisure time by individual increases. And according to the implementation experience of advanced countries, considerable effects are expected in the decrease of social problems such as consumption for pleasure-seeking, night crime, and traffic accidents rate, etc. Now may be the good time to implement summer time system that can kill two birds with one stone such as overcoming economic crisis and improvement of individual`s quality of life. But, there can happen side effects such as confusion in one`s life rhythm and prolonging of work hours, etc. pursuant to the implementation of summer time system. Since it is directly affecting national life, sufficient sympathy should be formed before the introduction, and countermeasures to the side effects should be carried out concurrently. 15 refs., 15 figs., 14 tabs.

Valuing travel time variability: Characteristics of the travel time distribution on an urban road

DEFF Research Database (Denmark)

Fosgerau, Mogens; Fukuda, Daisuke

2012-01-01

This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...

Is Reaction Time Variability in ADHD Mainly at Low Frequencies?

Science.gov (United States)

Karalunas, Sarah L.; Huang-Pollock, Cynthia L.; Nigg, Joel T.

2013-01-01

Background: Intraindividual variability in reaction times (RT variability) has garnered increasing interest as an indicator of cognitive and neurobiological dysfunction in children with attention deficit hyperactivity disorder (ADHD). Recent theory and research has emphasized specific low-frequency patterns of RT variability. However, whether…

Increasing work-time influence

DEFF Research Database (Denmark)

Nabe-Nielsen, Kirsten; Garde, Anne Helene; Aust, Birgit

2012-01-01

This quasi-experimental study investigated how an intervention aiming at increasing eldercare workers' influence on their working hours affected the flexibility, variability, regularity and predictability of the working hours. We used baseline (n = 296) and follow-up (n = 274) questionnaire data......), or discussion of working hours (subgroup C). Only computerised self-scheduling changed the working hours and the way they were planned. These changes implied more flexible but less regular working hours and an experience of less predictability and less continuity in the care of clients and in the co...... that while increasing the individual flexibility, increasing work-time influence may also result in decreased regularity of the working hours and less continuity in the care of clients and co-operation with colleagues....

Long time scale hard X-ray variability in Seyfert 1 galaxies

Science.gov (United States)

Markowitz, Alex Gary

This dissertation examines the relationship between long-term X-ray variability characteristics, black hole mass, and luminosity of Seyfert 1 Active Galactic Nuclei. High dynamic range power spectral density functions (PSDs) have been constructed for six Seyfert 1 galaxies. These PSDs show "breaks" or characteristic time scales, typically on the order of a few days. There is resemblance to PSDs of lower-mass Galactic X-ray binaries (XRBs), with the ratios of putative black hole masses and variability time scales approximately the same (106--7) between the two classes of objects. The data are consistent with a linear correlation between Seyfert PSD break time scale and black hole mass estimate; the relation extrapolates reasonably well over 6--7 orders of magnitude to XRBs. All of this strengthens the case for a physical similarity between Seyfert galaxies and XRBs. The first six years of RXTE monitoring of Seyfert 1s have been systematically analyzed to probe hard X-ray variability on multiple time scales in a total of 19 Seyfert is in an expansion of the survey of Markowitz & Edelson (2001). Correlations between variability amplitude, luminosity, and black hole mass are explored, the data support the model of PSD movement with black hole mass suggested by the PSD survey. All of the continuum variability results are consistent with relatively more massive black holes hosting larger X-ray emission regions, resulting in 'slower' observed variability. Nearly all sources in the sample exhibit stronger variability towards softer energies, consistent with softening as they brighten. Direct time-resolved spectral fitting has been performed on continuous RXTE monitoring of seven Seyfert is to study long-term spectral variability and Fe Kalpha variability characteristics. The Fe Kalpha line displays a wide range of behavior but varies less strongly than the broadband continuum. Overall, however, there is no strong evidence for correlated variability between the line and

Heart rate variability in healthy population

International Nuclear Information System (INIS)

Alamgir, M.; Hussain, M.M.

2010-01-01

Background: Heart rate variability has been considered as an indicator of autonomic status. Little work has been done on heart rate variability in normal healthy volunteers. We aimed at evolving the reference values of heart rate variability in our healthy population. Methods: Twenty-four hour holter monitoring of 37 healthy individuals was done using Holter ECG recorder 'Life card CF' from 'Reynolds Medical'. Heart rate variability in both time and frequency domains was analysed with 'Reynolds Medical Pathfinder Digital/700'. Results: The heart rate variability in normal healthy volunteers of our population was found in time domain using standard deviation of R-R intervals (SDNN), standard deviation of average NN intervals (SDANN), and Square root of the mean squared differences of successive NN intervals (RMSSD). Variation in heart rate variability indices was observed between local and foreign volunteers and RMSSD was found significantly increased (p<0.05) in local population. Conclusions: The values of heart rate variability (RMSSD) in healthy Pakistani volunteers were found increased compared to the foreign data reflecting parasympathetic dominance in our population. (author)

Verification of models for ballistic movement time and endpoint variability.

Science.gov (United States)

Lin, Ray F; Drury, Colin G

2013-01-01

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices. This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.

Long hours in paid and domestic work and subsequent sickness absence: does control over daily working hours matter?

Science.gov (United States)

Ala-Mursula, L; Vahtera, J; Kouvonen, A; Väänänen, A; Linna, A; Pentti, J; Kivimäki, M

2006-09-01

To explore the associations of working hours (paid, domestic, commuting, and total) with sickness absence, and to examine whether these associations vary according to the level of employee control over daily working hours. Prospective cohort study among 25 703 full-time public sector employees in 10 towns in Finland. A survey of working hours and control over working hours was carried out in 2000-01. The survey responses were linked with register data on the number of self-certified (3 days) sickness absences until the end of 2003. Poisson regression analyses with generalised estimating equations were used to take into account the fact that the employees were nested within work units. Adjustments were made for work and family characteristics and health behaviour. The mean follow-up period was 28.1 (SD 8.1) months. Long domestic and total working hours were associated with higher rates of medically certified sickness absences among both genders. In contrast, long paid working hours were associated with lower rates of subsequent self-certified sickness absences. Long commuting hours were related to increased rates of sickness absence of both types. Low control over daily working hours predicted medically certified sickness absences for both the women and men and self-certified absences for the men. In combinations, high control over working hours reduced the adverse associations of long domestic and total working hours with medically certified absences. Employee control over daily working hours may protect health and help workers successfully combine a full-time job with the demands of domestic work.

Employees’ Preferences for more or fewer Working Hours. The Effects of Usual, Contractual and Standard Working Time, Family Phase and Household Characteristics, and Job Satisfaction

OpenAIRE

Tijdens, K.

2002-01-01

This study seeks explanations for working time preferences, using cross-sectional multinomial logits for the 2001/2002 Wage Indicator dataset (N=21,727). As expected, the preferences are predominately influenced by working hours’ characteristics, showing that employees with long hours prefer to work shorter hours and that short-hours workers prefer longer hours. New is the finding that salaried employees indeed want to reduce hours whereas hourly paid employees prefer to work longer hours. In...

First-Passage-Time Distribution for Variable-Diffusion Processes

Science.gov (United States)

Barney, Liberty; Gunaratne, Gemunu H.

2017-05-01

First-passage-time distribution, which presents the likelihood of a stock reaching a pre-specified price at a given time, is useful in establishing the value of financial instruments and in designing trading strategies. First-passage-time distribution for Wiener processes has a single peak, while that for stocks exhibits a notable second peak within a trading day. This feature has only been discussed sporadically—often dismissed as due to insufficient/incorrect data or circumvented by conversion to tick time—and to the best of our knowledge has not been explained in terms of the underlying stochastic process. It was shown previously that intra-day variations in the market can be modeled by a stochastic process containing two variable-diffusion processes (Hua et al. in, Physica A 419:221-233, 2015). We show here that the first-passage-time distribution of this two-stage variable-diffusion model does exhibit a behavior similar to the empirical observation. In addition, we find that an extended model incorporating overnight price fluctuations exhibits intra- and inter-day behavior similar to those of empirical first-passage-time distributions.

Competency-Based, Time-Variable Education in the Health Professions: Crossroads.

Science.gov (United States)

Lucey, Catherine R; Thibault, George E; Ten Cate, Olle

2018-03-01

Health care systems around the world are transforming to align with the needs of 21st-century patients and populations. Transformation must also occur in the educational systems that prepare the health professionals who deliver care, advance discovery, and educate the next generation of physicians in these evolving systems. Competency-based, time-variable education, a comprehensive educational strategy guided by the roles and responsibilities that health professionals must assume to meet the needs of contemporary patients and communities, has the potential to catalyze optimization of educational and health care delivery systems. By designing educational and assessment programs that require learners to meet specific competencies before transitioning between the stages of formal education and into practice, this framework assures the public that every physician is capable of providing high-quality care. By engaging learners as partners in assessment, competency-based, time-variable education prepares graduates for careers as lifelong learners. While the medical education community has embraced the notion of competencies as a guiding framework for educational institutions, the structure and conduct of formal educational programs remain more aligned with a time-based, competency-variable paradigm.The authors outline the rationale behind this recommended shift to a competency-based, time-variable education system. They then introduce the other articles included in this supplement to Academic Medicine, which summarize the history of, theories behind, examples demonstrating, and challenges associated with competency-based, time-variable education in the health professions.

Predicting travel time variability for cost-benefit analysis

NARCIS (Netherlands)

Peer, S.; Koopmans, C.; Verhoef, E.T.

2010-01-01

Unreliable travel times cause substantial costs to travelers. Nevertheless, they are not taken into account in many cost-benefit-analyses (CBA), or only in very rough ways. This paper aims at providing simple rules on how variability can be predicted, based on travel time data from Dutch highways.

Work hours and turnover intention among hospital physicians in Taiwan: does income matter?

Science.gov (United States)

Tsai, Yu-Hsuan; Huang, Nicole; Chien, Li-Yin; Chiang, Jen-Huai; Chiou, Shu-Ti

2016-11-21

Physician shortage has become an urgent and critical challenge to many countries. According to the workforce dynamic model, long work hours may be one major pressure point to the attrition of physicians. Financial incentive is a common tool to human power retention. Therefore, this large-scale physician study investigated how pay satisfaction may influence the relationship between work hours and hospital physician's turnover intention. Data were obtained from a nationwide survey of full-time hospital staff members working at 100 hospitals in Taiwan. The analysis sample comprised 2423 full-time physicians. Dependent variable was degree of the physicians' turnover intention to leave the current hospital. The pay satisfaction was assessed by physicians themselves. We employed ordinal logistic regression models to analyze the association between the number of work hours and turnover intention. To consider the cluster effect of hospitals, we used the "gllamm" command in the statistical software package Stata Version 12.1. The results show that 351 (14.5%) of surveyed physicians reported strong intention to leave current hospital. The average work hours per week among hospital physicians was 59.8 h. As expected, work hours exhibited an independent relationship with turnover intention. More importantly, pay satisfaction could not effectively moderate the positive relationship between work hours and intentions to leave current hospital. The findings show that overtime work is prevalent among hospital physicians in Taiwan. Both the Taiwanese government and hospitals must take action to address the emerging problem of physician high turnover rate. Furthermore, hospitals should not consider relying solely on financial incentives to solve the problem. This study encouraged tackling work hour problem, which would lead to the possibility of solving high turnover intention among hospital physicians in Taiwan.

Work hours and turnover intention among hospital physicians in Taiwan: does income matter?

Directory of Open Access Journals (Sweden)

Yu-Hsuan Tsai

2016-11-01

Full Text Available Abstract Background Physician shortage has become an urgent and critical challenge to many countries. According to the workforce dynamic model, long work hours may be one major pressure point to the attrition of physicians. Financial incentive is a common tool to human power retention. Therefore, this large-scale physician study investigated how pay satisfaction may influence the relationship between work hours and hospital physician’s turnover intention. Methods Data were obtained from a nationwide survey of full-time hospital staff members working at 100 hospitals in Taiwan. The analysis sample comprised 2423 full-time physicians. Dependent variable was degree of the physicians’ turnover intention to leave the current hospital. The pay satisfaction was assessed by physicians themselves. We employed ordinal logistic regression models to analyze the association between the number of work hours and turnover intention. To consider the cluster effect of hospitals, we used the “gllamm” command in the statistical software package Stata Version 12.1. Results The results show that 351 (14.5% of surveyed physicians reported strong intention to leave current hospital. The average work hours per week among hospital physicians was 59.8 h. As expected, work hours exhibited an independent relationship with turnover intention. More importantly, pay satisfaction could not effectively moderate the positive relationship between work hours and intentions to leave current hospital. Conclusions The findings show that overtime work is prevalent among hospital physicians in Taiwan. Both the Taiwanese government and hospitals must take action to address the emerging problem of physician high turnover rate. Furthermore, hospitals should not consider relying solely on financial incentives to solve the problem. This study encouraged tackling work hour problem, which would lead to the possibility of solving high turnover intention among hospital physicians in

Flexible working hours, health, and well-being in Europe: some considerations from a SALTSA project.

Science.gov (United States)

Costa, Giovanni; Akerstedt, Torbjorn; Nachreiner, Friedhelm; Baltieri, Federica; Carvalhais, José; Folkard, Simon; Dresen, Monique Frings; Gadbois, Charles; Gartner, Johannes; Sukalo, Hiltraud Grzech; Härmä, Mikko; Kandolin, Irja; Sartori, Samantha; Silvério, Jorge

2004-01-01

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the "company-based flexibility" and the "individual-oriented flexibility"; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and "irregular" working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic

Predictor Variables for Marathon Race Time in Recreational Female Runners

OpenAIRE

Schmid, Wiebke; Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2012-01-01

Purpose We intended to determine predictor variables of anthropometry and training for marathon race time in recreational female runners in order to predict marathon race time for future novice female runners. Methods Anthropometric characteristics such as body mass, body height, body mass index, circumferences of limbs, thicknesses of skin-folds and body fat as well as training variables such as volume and speed in running training were related to marathon race time using bi- and multi-varia...

Dissociable effects of practice variability on learning motor and timing skills.

Science.gov (United States)

Caramiaux, Baptiste; Bevilacqua, Frédéric; Wanderley, Marcelo M; Palmer, Caroline

2018-01-01

Motor skill acquisition inherently depends on the way one practices the motor task. The amount of motor task variability during practice has been shown to foster transfer of the learned skill to other similar motor tasks. In addition, variability in a learning schedule, in which a task and its variations are interweaved during practice, has been shown to help the transfer of learning in motor skill acquisition. However, there is little evidence on how motor task variations and variability schedules during practice act on the acquisition of complex motor skills such as music performance, in which a performer learns both the right movements (motor skill) and the right time to perform them (timing skill). This study investigated the impact of rate (tempo) variability and the schedule of tempo change during practice on timing and motor skill acquisition. Complete novices, with no musical training, practiced a simple musical sequence on a piano keyboard at different rates. Each novice was assigned to one of four learning conditions designed to manipulate the amount of tempo variability across trials (large or small tempo set) and the schedule of tempo change (randomized or non-randomized order) during practice. At test, the novices performed the same musical sequence at a familiar tempo and at novel tempi (testing tempo transfer), as well as two novel (but related) sequences at a familiar tempo (testing spatial transfer). We found that practice conditions had little effect on learning and transfer performance of timing skill. Interestingly, practice conditions influenced motor skill learning (reduction of movement variability): lower temporal variability during practice facilitated transfer to new tempi and new sequences; non-randomized learning schedule improved transfer to new tempi and new sequences. Tempo (rate) and the sequence difficulty (spatial manipulation) affected performance variability in both timing and movement. These findings suggest that there is a

Predictor variables for marathon race time in recreational female runners.

Science.gov (United States)

Schmid, Wiebke; Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2012-06-01

We intended to determine predictor variables of anthropometry and training for marathon race time in recreational female runners in order to predict marathon race time for future novice female runners. Anthropometric characteristics such as body mass, body height, body mass index, circumferences of limbs, thicknesses of skin-folds and body fat as well as training variables such as volume and speed in running training were related to marathon race time using bi- and multi-variate analysis in 29 female runners. The marathoners completed the marathon distance within 251 (26) min, running at a speed of 10.2 (1.1) km/h. Body mass (r=0.37), body mass index (r=0.46), the circumferences of thigh (r=0.51) and calf (r=0.41), the skin-fold thicknesses of front thigh (r=0.38) and of medial calf (r=0.40), the sum of eight skin-folds (r=0.44) and body fat percentage (r=0.41) were related to marathon race time. For the variables of training, maximal distance ran per week (r=- 0.38), number of running training sessions per week (r=- 0.46) and the speed of the training sessions (r= - 0.60) were related to marathon race time. In the multi-variate analysis, the circumference of calf (P=0.02) and the speed of the training sessions (P=0.0014) were related to marathon race time. Marathon race time might be partially (r(2)=0.50) predicted by the following equation: Race time (min)=184.4 + 5.0 x (circumference calf, cm) -11.9 x (speed in running during training, km/h) for recreational female marathoners. Variables of both anthropometry and training were related to marathon race time in recreational female marathoners and cannot be reduced to one single predictor variable. For practical applications, a low circumference of calf and a high running speed in training are associated with a fast marathon race time in recreational female runners.

Work shift duration: a review comparing eight hour and 12 hour shift systems.

Science.gov (United States)

Smith, L; Folkard, S; Tucker, P; Macdonald, I

1998-04-01

Shiftwork is now a major feature of working life across a broad range of industries. The features of the shift systems operated can impact on the wellbeing, performance, and sleep of shiftworkers. This paper reviews the current state of knowledge on one major characteristic of shift rotas-namely, shift duration. Evidence comparing the relative effects of eight hour and 12 hour shifts on fatigue and job performance, safety, sleep, and physical and psychological health are considered. At the organisational level, factors such as the mode of system implementation, attitudes towards shift rotas, sickness absence and turnover, overtime, and moonlighting are discussed. Manual and electronic searches of the shiftwork research literature were conducted to obtain information on comparisons between eight hour and 12 hour shifts. The research findings are largely equivocal. The bulk of the evidence suggests few differences between eight and 12 hour shifts in the way they affect people. There may even be advantages to 12 hour shifts in terms of lower stress levels, better physical and psychological wellbeing, improved durations and quality of off duty sleep as well as improvements in family relations. On the negative side, the main concerns are fatigue and safety. It is noted that a 12 hour shift does not equate with being active for only 12 hours. There can be considerable extension of the person's time awake either side of the shift. However, the effects of longer term exposure to extended work days have been relatively uncharted in any systematic way. Longitudinal comparative research into the chronic impact of the compressed working week is needed.

Public transport travel time and its variability

OpenAIRE

Mazloumi Shomali, Ehsan

2017-01-01

Executive Summary Public transport agencies around the world are constantly trying to improve the performance of their service, and to provide passengers with a more reliable service. Two major measures to evaluate the performance of a transit system include travel time and travel time variability. Information on these two measures provides operators with a capacity to identify the problematic locations in a transport system and improve operating plans. Likewise, users can benefit through...

Is the Office Hour Obsolete?

Science.gov (United States)

Behrens, Susan

2013-01-01

A colleague can't make a coffee date at a time the author proposes because it would conflict with his office hour. No student has actually made an appointment with him during the hour, but he is committed to being in his office as promised in case someone drops by. The author's reaction to her colleague's faithfulness to his posted office hour…

Complexity Variability Assessment of Nonlinear Time-Varying Cardiovascular Control

Science.gov (United States)

Valenza, Gaetano; Citi, Luca; Garcia, Ronald G.; Taylor, Jessica Noggle; Toschi, Nicola; Barbieri, Riccardo

2017-02-01

The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier. We apply the proposed methodology to four exemplary studies involving disorders which stem from cardiology, neurology and psychiatry: Congestive Heart Failure (CHF), Major Depression Disorder (MDD), Parkinson’s Disease (PD), and Post-Traumatic Stress Disorder (PTSD) patients with insomnia under a yoga training regime. We show that complexity assessments derived from simple time-averaging are not able to discern pathology-related changes in autonomic control, and we demonstrate that between-group differences in measures of complexity variability are consistent across pathologies. Pathological states such as CHF, MDD, and PD are associated with an increased complexity variability when compared to healthy controls, whereas wellbeing derived from yoga in PTSD is associated with lower time-variance of complexity.

Cost-efficient staffing under annualized hours

NARCIS (Netherlands)

van der Veen, Egbert; Hans, Elias W.; Veltman, Bart; Berrevoets, Leo M.; Berden, Hubert J.J.M.

2012-01-01

We study how flexibility in workforce capacity can be used to efficiently match capacity and demand. Flexibility in workforce capacity is introduced by the annualized hours regime. Annualized hours allow organizations to measure working time per year, instead of per month or per week. An additional

The impact of small changes in bar closing hours on violence. The Norwegian experience from 18 cities.

Science.gov (United States)

Rossow, Ingeborg; Norström, Thor

2012-03-01

To estimate the effect on violence of small changes in closing hours for on-premise alcohol sales, and to assess whether a possible effect is symmetrical. A quasi-experimental design drawing on data from 18 Norwegian cities that have changed (extended or restricted) the closing hours for on-premise alcohol sales. All changes were ≤ 2 hours. Closing hours were measured in terms of the latest permitted hour of on-premise trading, ranging from 1 a.m. to 3 a.m. The outcome measure comprised police-reported assaults that occurred in the city centre between 10 p.m. and 5 a.m. at weekends. Assaults outside the city centre during the same time window should not be affected by changes in closing hours but function as a proxy for potential confounders, and was thus included as a control variable. The data spanned the period Q1 2000-Q3 2010, yielding 774 observations. Outcomes from main analyses suggested that each 1-hour extension of closing hours was associated with a statistically significant increase of 4.8 assaults (95% CI 2.60, 6.99) per 100,000 inhabitants per quarter (i.e. an increase of about 16%). Findings indicate that the effect is symmetrical. These findings were consistent across three different modelling techniques. In Norway, each additional 1-hour extension to the opening times of premises selling alcohol is associated with a 16% increase in violent crime. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

Behavioral Variables Associated with Obesity in Police Officers

Science.gov (United States)

CAN, S. Hakan; HENDY, Helen M.

2014-01-01

Past research has documented that non-behavioral variables (such as long work hours, exposure to police stressors) are associated with obesity risk in police officers, but limited research has examined behavioral variables that might be targeted by Employee Assistance Programs for police weight management. The present study compared non-obese and obese officers for behavioral variables found associated with obesity in other adult samples: physical activity (cardiovascular, strength-training, stretching), sleep duration, and consumption of alcohol, fruit and vegetables, and snack foods. Participants included 172 male police officers who completed questionnaires to report height and weight, used to calculate body mass index (BMI = kg/m2) and to divide them into “non-obese” and “obese” groups. They also reported the above behaviors and six non-behavioral variables found associated with obesity risk: age, health problems, family support, police work hours, police stressors, police support. ANCOVAs compared each behavioral variable across obesity status (non-obese, obese), with the six non-behavioral variables used as covariates. Results revealed that cardiovascular and strength-training physical activity were the only behavioral variables that differed significantly between non-obese and obese police officers. The use of self-reported height and weight values may provide Employee Assistance Program with improved cost, time, and officer participation. PMID:24694574

Variable Selection in Time Series Forecasting Using Random Forests

Directory of Open Access Journals (Sweden)

Hristos Tyralis

2017-10-01

Full Text Available Time series forecasting using machine learning algorithms has gained popularity recently. Random forest is a machine learning algorithm implemented in time series forecasting; however, most of its forecasting properties have remained unexplored. Here we focus on assessing the performance of random forests in one-step forecasting using two large datasets of short time series with the aim to suggest an optimal set of predictor variables. Furthermore, we compare its performance to benchmarking methods. The first dataset is composed by 16,000 simulated time series from a variety of Autoregressive Fractionally Integrated Moving Average (ARFIMA models. The second dataset consists of 135 mean annual temperature time series. The highest predictive performance of RF is observed when using a low number of recent lagged predictor variables. This outcome could be useful in relevant future applications, with the prospect to achieve higher predictive accuracy.

Daily and Hourly Variability in Global Fire Emissions and Consequences for Atmospheric Model Predictions of Carbon Monoxide

Science.gov (United States)

Mu, M.; Randerson, J. T.; van der Werf, G. R.; Giglio, L.; Kasibhatla, P.; Morton, D.; Collatz, G. J.; DeFries, R. S.; Hyer, E. J.; Prins, E. M.;

Flexibility of working hours in the 24-hour society.

Science.gov (United States)

Costa, G

2006-01-01

The 24-hour Society undergoes an ineluctable process towards a social organisation where time constraints are no more restricting human life. The borders between working and social times are no more fixed and rigidly determined, and the value of working time changes according to the different economic and social effects you may consider. Shift and night work, irregular and flexible working hours, together with new technologies, are the milestone of this epochal passage. What are the advantages and disadvantages for the individual, the companies, and the society? What is the cost/benefit ratio in terms of health and social well-being? Coping properly with this process means avoiding a passive acceptance of it with consequent maladjustments at both individual and social level, but adopting effective preventive and compensative strategies aimed at building up a more sustainable society. Flexible working times now appear to be one of the best ways to cope with the demands of the modern life, but there are different points of view about labour and temporal 'flexibility" between employers and employees. For the former it means a prompt adaptation to market demands and technological innovations; for the latter it is a way to improve working and social life, by decreasing work constraints and increasing control and autonomy. Although it can be easily speculated that individual-based 'flexibility" should improve health and well-being, and especially satisfaction, whereas company-based flexibility" might interfere negatively, the effective consequences on health and well-being have still to be analysed properly.

Credit Hours with No Set Time: A Study of Credit Policies in Asynchronous Online Education

Science.gov (United States)

Prasuhn, Frederick Carl

2014-01-01

U.S. public university system policies were examined to learn how credit hours were determined for asynchronous online education. Findings indicated that (a) credit hour meaning and use are not consistent, (b) primary responsibility for credit hour decisions was at the local level, and (c) no policies exist to guide credit hour application for…

Reoperations within 48 hours following 7942 pediatric neurosurgery procedures.

Science.gov (United States)

Roy, Anil K; Chu, Jason; Bozeman, Caroline; Sarda, Samir; Sawvel, Michael; Chern, Joshua J

2017-06-01

OBJECTIVE Various indicators are used to evaluate the quality of care delivered by surgical services, one of which is early reoperation rate. The indications and rate of reoperations within a 48-hour time period have not been previously reported for pediatric neurosurgery. METHODS Between May 1, 2009, and December 30, 2014, 7942 surgeries were performed by the pediatric neurosurgery service in the operating rooms at a single institution. Demographic, socioeconomic, and clinical characteristics associated with each of the operations were prospectively collected. The procedures were grouped into 31 categories based on the nature of the procedure and underlying diseases. Reoperations within 48 hours at the conclusion of the index surgery were reviewed to determine whether the reoperation was planned or unplanned. Multivariate logistic regression was employed to analyze risk factors associated with unplanned reoperations. RESULTS Cerebrospinal fluid shunt-and hydrocephalus-related surgeries accounted for 3245 (40.8%) of the 7942 procedures. Spinal procedures, craniotomy for tumor resections, craniotomy for traumatic injury, and craniofacial reconstructions accounted for an additional 8.7%, 6.8%, 4.5%, and 4.5% of surgical volume. There were 221 reoperations within 48 hours of the index surgery, yielding an overall incidence of 2.78%; 159 of the reoperation were unplanned. Of these 159 unplanned reoperations, 121 followed index operations involving shunt manipulations. Using unplanned reoperations as the dependent variable (n = 159), index operations with a starting time after 3 pm and admission through the emergency department (ED) were associated with a two- to threefold increase in the likelihood of reoperations (after-hour surgery, odds ratio [OR] 2.01 [95% CI 1.43-2.83, p < 0.001]; ED admission, OR 1.97 (95% CI 1.32-2.96, p < 0.05]). CONCLUSIONS Approximately 25% of the reoperations within 48 hours of a pediatric neurosurgical procedure were planned. When

Working hours and Work-Life Balance Satisfaction in Couples

OpenAIRE

Nathalie Georges; Dominique Méda; Danièle Trancart

2010-01-01

Over the past several years, many studies have highlighted the strategic nature of working hours, the way they are determined, their regularity and their predictability to judge the qualities of a job and how family life and work life are reconciled. Our results confirm those obtained by previous studies and clarify them, while also showing that both the working hours of the persons questioned and those of their spouse constitute a central variable. We will first review the results from the a...

How many hours do you usually work? An analysis of the working hours questions in 26 large-scale surveys in 6 countries and the European Union.

NARCIS (Netherlands)

Dragstra, A.; Tijdens, K.

2004-01-01

This paper reviews how working hours are asked in 26 large-scale surveys in 6 countries plus the European Union. Four dimensions of working time were investigated, notably number of working hours, timing of work, predictability and control over hours, and commuting time. Although almost all

How many hours do you usually work? An analysis of the working hours questions in 26 large-scale surveys in six countries and the European Union

NARCIS (Netherlands)

Tijdens, K.; Dragstra, A.

2007-01-01

This article reviews how working hours are asked for in 26 large-scale surveys in six countries plus the European Union. Four dimensions of working time were investigated, notably number of working hours, timing of work, predictability and control over hours, and commuting time. Although almost all

Hourly cooling load forecasting using time-indexed ARX models with two-stage weighted least squares regression

International Nuclear Information System (INIS)

Guo, Yin; Nazarian, Ehsan; Ko, Jeonghan; Rajurkar, Kamlakar

2014-01-01

Highlights: • Developed hourly-indexed ARX models for robust cooling-load forecasting. • Proposed a two-stage weighted least-squares regression approach. • Considered the effect of outliers as well as trend of cooling load and weather patterns. • Included higher order terms and day type patterns in the forecasting models. • Demonstrated better accuracy compared with some ARX and ANN models. - Abstract: This paper presents a robust hourly cooling-load forecasting method based on time-indexed autoregressive with exogenous inputs (ARX) models, in which the coefficients are estimated through a two-stage weighted least squares regression. The prediction method includes a combination of two separate time-indexed ARX models to improve prediction accuracy of the cooling load over different forecasting periods. The two-stage weighted least-squares regression approach in this study is robust to outliers and suitable for fast and adaptive coefficient estimation. The proposed method is tested on a large-scale central cooling system in an academic institution. The numerical case studies show the proposed prediction method performs better than some ANN and ARX forecasting models for the given test data set

A moving mesh method with variable relaxation time

OpenAIRE

Soheili, Ali Reza; Stockie, John M.

2006-01-01

We propose a moving mesh adaptive approach for solving time-dependent partial differential equations. The motion of spatial grid points is governed by a moving mesh PDE (MMPDE) in which a mesh relaxation time \\tau is employed as a regularization parameter. Previously reported results on MMPDEs have invariably employed a constant value of the parameter \\tau. We extend this standard approach by incorporating a variable relaxation time that is calculated adaptively alongside the solution in orde...

Lack of sensitivity of staffing for 8-hour sessions to standard deviation in daily actual hours of operating room time used for surgeons with long queues.

Science.gov (United States)

Pandit, Jaideep J; Dexter, Franklin

2009-06-01

At multiple facilities including some in the United Kingdom's National Health Service, the following are features of many surgical-anesthetic teams: i) there is sufficient workload for each operating room (OR) list to almost always be fully scheduled; ii) the workdays are organized such that a single surgeon is assigned to each block of time (usually 8 h); iii) one team is assigned per block; and iv) hardly ever would a team "split" to do cases in more than one OR simultaneously. We used Monte-Carlo simulation using normal and Weibull distributions to estimate the times to complete lists of cases scheduled into such 8 h sessions. For each combination of mean and standard deviation, inefficiencies of use of OR time were determined for 10 h versus 8 h of staffing. When the mean actual hours of OR time used averages standard deviation and relative cost of over-run to under-run. When mean > or = 8 h 50 min, 10 h staffing has higher OR efficiency. For 8 h 25 min standard deviation of 60 min and relative cost of over-run to under-run of 2.0 versus (b) 8 h 48 min for normal, standard deviation of 0 min and relative cost ratio of 1.50. Although the simplest decision rule would be to staff for 8 h if the mean workload is standard deviation 60 min, and relative cost ratio of 2.00, the inefficiency of use of OR time would be 34% larger if staffing were planned for 8 h instead of 10 h. For surgical teams with 8 h sessions, use the following decision rule for anesthesiology and OR nurse staffing. If actual hours of OR time used averages or = 8 h 50 min, plan 10 h staffing. For averages in between, perform the full analysis of McIntosh et al. (Anesth Analg 2006;103:1499-516).

Use and Underlying Reasons for Duty Hour Flexibility in the Flexibility in Duty Hour Requirements for Surgical Trainees (FIRST) Trial.

Science.gov (United States)

Bilimoria, Karl Y; Quinn, Christopher M; Dahlke, Allison R; Kelz, Rachel R; Shea, Judy A; Rajaram, Ravi; Love, Remi; Kreutzer, Lindsey; Biester, Thomas; Yang, Anthony D; Hoyt, David B; Lewis, Frank R

2017-02-01

The Flexibility in Duty Hour Requirements for Surgical Trainees (FIRST) Trial randomly assigned surgical residency programs to either standard duty hour policies or flexible policies that eliminated caps on shift lengths and time off between shifts. Our objectives were to assess adherence to duty hour requirements in the Standard Policy arm and examine how often and why duty hour flexibility was used in the Flexible Policy arm. A total of 3,795 residents in the FIRST trial completed a survey in January 2016 (response rate >95%) that asked how often and why they exceeded current standard duty hour limits in both study arms. Flexible Policy interns worked more than 16 hours continuously at least once in a month more frequently than Standard Policy residents (86% vs 37.8%). Flexible Policy residents worked more than 28 hours once in a month more frequently than Standard Policy residents (PGY1: 64% vs 2.9%; PGY2 to 3: 62.4% vs 41.9%; PGY4 to 5: 52.2% vs 36.6%), but this occurred most frequently only 1 to 2 times per month. Although residents reported working more than 80 hours in a week 3 or more times in the most recent month more frequently under Flexible Policy vs Standard Policy (19.9% vs 16.2%), the difference was driven by interns (30.9% vs 19.6%), and there were no significant differences in exceeding 80 hours among PGY2 to 5 residents. The most common reasons reported for extending duty hours were facilitating care transitions (76.6%), stabilizing critically ill patients (70.7%), performing routine responsibilities (67.9%), and operating on patients known to the trainee (62.0%). There were differences in duty hours worked by residents in the Flexible vs Standard Policy arms of the FIRST trial, but it appeared that residents generally used the flexibility for patient care and educational opportunities selectively. Copyright © 2016 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Climate variability and sustainable food production: Insights from ...

African Journals Online (AJOL)

They are integrated and balance the ... implement resilient agricultural practices that increase productivity and production; that help maintain ecosystems ... other forms of life, the manner in which human beings respond to climate variability is critical not ..... work for longer hours and at the same time its effect on their health.

Characteristics and outcomes for women physicians who work reduced hours.

Science.gov (United States)

Carr, Phyllis L; Gareis, Karen C; Barnett, Rosalind C

2003-05-01

To understand the characteristics of women physicians who work reduced hours in dual-earner couples and how such work schedules affect the quality of the marital role, parental role, and job role, as well as indicators of psychological distress, burnout, career satisfaction, and life satisfaction. Survey of a random sample of female physicians between 25 and 50 years of age, working within 25 miles of Boston, whose names were obtained from the Registry of Board Certification in Medicine in Massachusetts. Interviewers conducted a 60-minute face-to-face close-ended interview after a 20-minute mailed questionnaire had been completed. Fifty-one full-time physicians and 47 reduced-hours physicians completed the study, for a completion rate of 49.5%. There was no difference in age, number of years as a physician, mean household income, number of children, or presence of an infant in the home between reduced-hours and full-time physicians. Reduced-hours physicians, however, were more likely to be in a generalist specialty (40% vs. 12%, p = 0.001) and to spend a greater portion of their time in patient care (64.5% vs. 50.1%, p = 0.003) and less time in research (4.9% vs. 18.0%, p = 0.002) than full-time physicians. In addition, there was no difference between the two groups in the perception of work interfering with family life (1.8 vs. 1.7, p = 0.17; scale 1-7 with 7 high) or family life interfering with work (1.4 vs. 1.5, p = 0.62). Physicians who worked their preferred number of hours (25% of full-time and 57% of reduced-hours physicians), regardless of full-time (self-reported hours 35-90 hours per week) or reduced-hours (20-60 hours per week) status, reported better job role quality (r = 0.35, p = 0.001), schedule fit (r = 0.41, p Women physicians who work their preferred number of hours achieve the best balance of work and family outcomes.

Timing variability in children with early-treated congenital hypothyroidism

NARCIS (Netherlands)

Kooistra, L.; Snijders, T.A.B.; Schellekens, J.M.H.; Kalverboer, A.F.; Geuze, R.H.

This study reports on central and peripheral determinants of timing variability in self-paced tapping by children with early-treated congenital hypothyroidism (CH). A theoretical model of the timing of repetitive movements developed by Wing and Kristofferson was applied to estimate the central

Work hours, weight status, and weight-related behaviors: a study of metro transit workers.

Science.gov (United States)

Escoto, Kamisha H; French, Simone A; Harnack, Lisa J; Toomey, Traci L; Hannan, Peter J; Mitchell, Nathan R

2010-12-20

Associations between hours worked per week and Body Mass Index (BMI), food intake, physical activity, and perceptions of eating healthy at work were examined in a sample of transit workers. Survey data were collected from 1086 transit workers. Participants reported hours worked per week, food choices, leisure-time physical activity and perceptions of the work environment with regard to healthy eating. Height and weight were measured for each participant. Multivariate linear and logistic regressions were conducted to examine associations between work hours and behavioral variables. Associations were examined in the full sample and stratified by gender. Transit workers working in the highest work hour categories had higher BMI and poorer dietary habits, with results differing by gender. Working 50 or more hours per week was associated with higher BMI among men but not women. Additionally, working 50 or more hours per week was significantly associated with higher frequency of accessing cold beverage, cold food, and snack vending machines among men. Working 40 or more hours per week was associated with higher frequency of accessing cold food vending machines among women. Reported frequency of fruit and vegetable intake was highest among women working 50 or more hours per week. Intake of sweets, sugar sweetened beverages, and fast food did not vary with work hours in men or women. Physical activity and perception of ease of eating healthy at work were not associated with work hours in men or women. Long work hours were associated with more frequent use of garage vending machines and higher BMI in transit workers, with associations found primarily among men. Long work hours may increase dependence upon food availability at the worksite, which highlights the importance of availability of healthy food choices.

Work hours, weight status, and weight-related behaviors: a study of metro transit workers

Directory of Open Access Journals (Sweden)

Hannan Peter J

2010-12-01

Full Text Available Abstract Background Associations between hours worked per week and Body Mass Index (BMI, food intake, physical activity, and perceptions of eating healthy at work were examined in a sample of transit workers. Methods Survey data were collected from 1086 transit workers. Participants reported hours worked per week, food choices, leisure-time physical activity and perceptions of the work environment with regard to healthy eating. Height and weight were measured for each participant. Multivariate linear and logistic regressions were conducted to examine associations between work hours and behavioral variables. Associations were examined in the full sample and stratified by gender. Results Transit workers working in the highest work hour categories had higher BMI and poorer dietary habits, with results differing by gender. Working 50 or more hours per week was associated with higher BMI among men but not women. Additionally, working 50 or more hours per week was significantly associated with higher frequency of accessing cold beverage, cold food, and snack vending machines among men. Working 40 or more hours per week was associated with higher frequency of accessing cold food vending machines among women. Reported frequency of fruit and vegetable intake was highest among women working 50 or more hours per week. Intake of sweets, sugar sweetened beverages, and fast food did not vary with work hours in men or women. Physical activity and perception of ease of eating healthy at work were not associated with work hours in men or women. Conclusions Long work hours were associated with more frequent use of garage vending machines and higher BMI in transit workers, with associations found primarily among men. Long work hours may increase dependence upon food availability at the worksite, which highlights the importance of availability of healthy food choices.

Physical activity levels of community-dwelling older adults are influenced by winter weather variables.

Science.gov (United States)

Jones, G R; Brandon, C; Gill, D P

2017-07-01

Winter weather conditions may negatively influence participation of older adults in daily physical activity (PA). Assess the influence of winter meteorological variables, day-time peak ambient temperature, windchill, humidity, and snow accumulation on the ground to accelerometer measured PA values in older adults. 50 community-dwelling older adults (77.4±4.7yrs; range 71-89; 12 females) living in Southwestern Ontario (Latitude 42.9°N Longitude 81.2° W) Canada, wore a waist-borne accelerometer during active waking hours (12h) for 7 consecutive days between February and April 2007. Hourly temperature, windchill, humidity, and snowfall accumulation were obtained from meteorological records and time locked to hourly accelerometer PA values. Regression analysis revealed significant relationships between time of day, ambient daytime high temperature and a humidity for participation in PA. Windchill temperature added no additional influence over PA acclamation already influenced by ambient day-time temperature and the observed variability in PA patterns relative to snow accumulation over the study period was too great to warrant its inclusion in the model. Most PA was completed in the morning hours and increased as the winter month's transitioned to spring (February through April). An equation was developed to adjust for winter weather conditions using temperature, humidity and time of day. Accurate PA assessment during the winter months must account for the ambient daytime high temperatures, humidity, and time of day. These older adults were more physically active during the morning hours and became more active as the winter season transitioned to spring. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of a change in sleep-wakefulness timing, bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature.

Science.gov (United States)

Iskra-Golec, I; Fafrowicz, M; Marek, T; Costa, G; Folkard, S; Foret, J; Kundi, M; Smith, L

2001-12-01

Experiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post-treatment conditions.

Analysis of Hourly Climatic Variables-Meteorological Test Reference Year for Beijing

DEFF Research Database (Denmark)

Qin, Lin

1997-01-01

The climatic data which was surveyed from 1981 to 1993 in Beijing was analysed to generate a representative year, a Test Reference Year (TRY). This TRY consists of just one year of hourly data that could yield the same simulation results as the long-term data, thereby minimizing the computation...... need to assess long-term system performance. It can be used as input data for the simulation of the performance of solar energy and indoor climate systems. The application of this TRY in the simulation of a solar domestic hot water system is also presented....

Consciousness Level and Off‐Hour Admission Affect Discharge Outcome of Acute Stroke Patients: A J‐ASPECT Study

Science.gov (United States)

Kamitani, Satoru; Nishimura, Kunihiro; Nakamura, Fumiaki; Kada, Akiko; Nakagawara, Jyoji; Toyoda, Kazunori; Ogasawara, Kuniaki; Ono, Junichi; Shiokawa, Yoshiaki; Aruga, Toru; Miyachi, Shigeru; Nagata, Izumi; Matsuda, Shinya; Miyamoto, Yoshihiro; Iwata, Michiaki; Suzuki, Akifumi; Ishikawa, Koichi B.; Kataoka, Hiroharu; Morita, Kenichi; Kobayashi, Yasuki; Iihara, Koji

2014-01-01

Background Poor outcomes have been reported for stroke patients admitted outside of regular working hours. However, few studies have adjusted for case severity. In this nationwide assessment, we examined relationships between hospital admission time and disabilities at discharge while considering case severity. Methods and Results We analyzed 35 685 acute stroke patients admitted to 262 hospitals between April 2010 and May 2011 for ischemic stroke (IS), intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH). The proportion of disabilities/death at discharge as measured by the modified Rankin Scale (mRS) was quantified. We constructed 2 hierarchical logistic regression models to estimate the effect of admission time, one adjusted for age, sex, comorbidities, and number of beds; and the second adjusted for the effect of consciousness levels and the above variables at admission. The percentage of severe disabilities/death at discharge increased for patients admitted outside of regular hours (22.8%, 27.2%, and 28.2% for working‐hour, off‐hour, and nighttime; P<0.001). These tendencies were significant in the bivariate and multivariable models without adjusting for consciousness level. However, the effects of off‐hour or nighttime admissions were negated when adjusted for consciousness levels at admission (adjusted OR, 1.00 and 0.99; 95% CI, 1.00 to 1.13 and 0.89 to 1.10; P=0.067 and 0.851 for off‐hour and nighttime, respectively, versus working‐hour). The same trend was observed when each stroke subtype was stratified. Conclusions The well‐known off‐hour effect might be attributed to the severely ill patient population. Thus, sustained stroke care that is sufficient to treat severely ill patients during off‐hours is important. PMID:25336463

The 24-hour society between myth and reality.

Science.gov (United States)

Costa, G

2001-12-01

The 24-hour society appears to be an ineluctable process towards a social organisation where time constraints are no more "restricting" the human life. But, what kind of 24-hour society do we need? At what costs? Are they acceptable/sustainable? Shift work, night work, irregular and flexible working hours, together with new technologies, are the milestone of this epochal passage, of which shift workers are builders and victims at the same time. The borders between working and social times are no more fixed and rigidly determined: not only the link between work place and working hours is broken, but also the value of working time changes according to the different economic/productive/social effects it can make. What are the advantages and disadvantages for the individual, the companies, and the society? What is the cost/benefit ratio in terms of physical health; psychological well-being, family and social life? The research on irregular working hours and health shows us what can be the negative consequences of non-human-centered working times organisations. Coping properly with this process means avoiding a passive acceptance of it with consequent maladjustments at both individual and social level, but adopting effective preventive and compensative strategies aimed at building a more sustainable society, at acceptable costs and with the highest possible benefits.

Gender-specific dynamics in hours worked : Exploring the potential for increasing hours worked in an ageing society

NARCIS (Netherlands)

Noback, Inge; Broersma, Lourens; van Dijk, Jouke; Karlsson, Charlie; Andersson, Martin; Norman, Therese

2015-01-01

The Dutch labour market differs from that of other countries due to a unique combination of high employment rates and a low average number of hours worked. Dutch employment rates are among the highest in the world, at 77 per cent in 2011. At the same time, the average number of hours worked annually

Time dependent analysis of assay comparability: a novel approach to understand intra- and inter-site variability over time

Science.gov (United States)

Winiwarter, Susanne; Middleton, Brian; Jones, Barry; Courtney, Paul; Lindmark, Bo; Page, Ken M.; Clark, Alan; Landqvist, Claire

2015-09-01

We demonstrate here a novel use of statistical tools to study intra- and inter-site assay variability of five early drug metabolism and pharmacokinetics in vitro assays over time. Firstly, a tool for process control is presented. It shows the overall assay variability but allows also the following of changes due to assay adjustments and can additionally highlight other, potentially unexpected variations. Secondly, we define the minimum discriminatory difference/ratio to support projects to understand how experimental values measured at different sites at a given time can be compared. Such discriminatory values are calculated for 3 month periods and followed over time for each assay. Again assay modifications, especially assay harmonization efforts, can be noted. Both the process control tool and the variability estimates are based on the results of control compounds tested every time an assay is run. Variability estimates for a limited set of project compounds were computed as well and found to be comparable. This analysis reinforces the need to consider assay variability in decision making, compound ranking and in silico modeling.

Predictor variables for a half marathon race time in recreational male runners.

Science.gov (United States)

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Lepers, Romuald; Rosemann, Thomas

2011-01-01

The aim of this study was to investigate predictor variables of anthropometry, training, and previous experience in order to predict a half marathon race time for future novice recreational male half marathoners. Eighty-four male finishers in the 'Half Marathon Basel' completed the race distance within (mean and standard deviation, SD) 103.9 (16.5) min, running at a speed of 12.7 (1.9) km/h. After multivariate analysis of the anthropometric characteristics, body mass index (r = 0.56), suprailiacal (r = 0.36) and medial calf skin fold (r = 0.53) were related to race time. For the variables of training and previous experience, speed in running of the training sessions (r = -0.54) were associated with race time. After multivariate analysis of both the significant anthropometric and training variables, body mass index (P = 0.0150) and speed in running during training (P = 0.0045) were related to race time. Race time in a half marathon might be partially predicted by the following equation (r(2) = 0.44): Race time (min) = 72.91 + 3.045 * (body mass index, kg/m(2)) -3.884 * (speed in running during training, km/h) for recreational male runners. To conclude, variables of both anthropometry and training were related to half marathon race time in recreational male half marathoners and cannot be reduced to one single predictor variable.

Online Synthesis for Operation Execution Time Variability on Digital Microfluidic Biochips

DEFF Research Database (Denmark)

Alistar, Mirela; Pop, Paul

2014-01-01

have assumed that each biochemical operation in an application is characterized by a worst-case execution time (wcet). However, during the execution of the application, due to variability and randomness in biochemical reactions, operations may finish earlier than their wcets. In this paper we propose...... an online synthesis strategy that re-synthesizes the application at runtime when operations experience variability in their execution time, obtaining thus shorter application execution times. The proposed strategy has been evaluated using several benchmarks....

Reducing bed rest time from five to three hours does not increase complications after cardiac catheterization: the THREE CATH Trial 1

Science.gov (United States)

Matte, Roselene; Hilário, Thamires de Souza; Reich, Rejane; Aliti, Graziella Badin; Rabelo-Silva, Eneida Rejane

2016-01-01

Abstract Objective: to compare the incidence of vascular complications in patients undergoing transfemoral cardiac catheterization with a 6F introducer sheath followed by 3-hour versus 5-hour rest. Methods: randomized clinical trial. Subjects in the intervention group (IG) ambulated 3 hours after sheath removal, versus 5 hours in the control group (CG). All patients remained in the catheterization laboratory for 5 hours and were assessed hourly, and were contacted 24, 48, and 72 h after hospital discharge. Results: the sample comprised 367 patients in the IG and 363 in the GC. During cath lab stay, hematoma was the most common complication in both groups, occurring in 12 (3%) IG and 13 (4%) CG subjects (P=0.87). Bleeding occurred in 4 (1%) IG and 6 (2%) CG subjects (P=0.51), and vasovagal reaction in 5 (1.4%) IG and 4 (1.1%) CG subjects (P=0.75). At 24-h, 48-h, and 72-h bruising was the most commonly reported complication in both groups. None of the comparisons revealed any significant between-group differences. Conclusion: the results of this trial show that reducing bed rest time to 3 hours after elective cardiac catheterization is safe and does not increase complications as compared with a 5-hour rest. ClinicalTrials.gov Identifier: NCT-01740856 PMID:27463113

Continuous performance task in ADHD: Is reaction time variability a key measure?

Science.gov (United States)

Levy, Florence; Pipingas, Andrew; Harris, Elizabeth V; Farrow, Maree; Silberstein, Richard B

2018-01-01

To compare the use of the Continuous Performance Task (CPT) reaction time variability (intraindividual variability or standard deviation of reaction time), as a measure of vigilance in attention-deficit hyperactivity disorder (ADHD), and stimulant medication response, utilizing a simple CPT X-task vs an A-X-task. Comparative analyses of two separate X-task vs A-X-task data sets, and subgroup analyses of performance on and off medication were conducted. The CPT X-task reaction time variability had a direct relationship to ADHD clinician severity ratings, unlike the CPT A-X-task. Variability in X-task performance was reduced by medication compared with the children's unmedicated performance, but this effect did not reach significance. When the coefficient of variation was applied, severity measures and medication response were significant for the X-task, but not for the A-X-task. The CPT-X-task is a useful clinical screening test for ADHD and medication response. In particular, reaction time variability is related to default mode interference. The A-X-task is less useful in this regard.

How many hours do you usually work? An analysis of the working hours questions in 26 large-scale surveys in six countries and the European Union

OpenAIRE

Tijdens, K.; Dragstra, A.

2007-01-01

This article reviews how working hours are asked for in 26 large-scale surveys in six countries plus the European Union. Four dimensions of working time were investigated, notably number of working hours, timing of work, predictability and control over hours, and commuting time. Although almost all questionnaires ask for hours worked, the terminology varies greatly. In only half of the cases a reference period is taken into account and in half the reasons for working more/less in the survey w...

How many hours do you usually work? An analysis of the working hours questions in 26 large-scale surveys in 6 countries and the European Union.

OpenAIRE

Dragstra, A.; Tijdens, K.

2004-01-01

This paper reviews how working hours are asked in 26 large-scale surveys in 6 countries plus the European Union. Four dimensions of working time were investigated, notably number of working hours, timing of work, predictability and control over hours, and commuting time. Although almost all questionnaires ask for hours worked, the terminology varies largely. In only half of the cases a reference period is taken into account and in half the reasons for working more/less in the survey week than...

Assessment of the methods for determining net radiation at different time-scales of meteorological variables

Directory of Open Access Journals (Sweden)

Ni An

2017-04-01

Full Text Available When modeling the soil/atmosphere interaction, it is of paramount importance to determine the net radiation flux. There are two common calculation methods for this purpose. Method 1 relies on use of air temperature, while Method 2 relies on use of both air and soil temperatures. Nowadays, there has been no consensus on the application of these two methods. In this study, the half-hourly data of solar radiation recorded at an experimental embankment are used to calculate the net radiation and long-wave radiation at different time-scales (half-hourly, hourly, and daily using the two methods. The results show that, compared with Method 2 which has been widely adopted in agronomical, geotechnical and geo-environmental applications, Method 1 is more feasible for its simplicity and accuracy at shorter time-scale. Moreover, in case of longer time-scale, daily for instance, less variations of net radiation and long-wave radiation are obtained, suggesting that no detailed soil temperature variations can be obtained. In other words, shorter time-scales are preferred in determining net radiation flux.

Do difficulties in accessing in-hours primary care predict higher use of out-of-hours GP services? Evidence from an English National Patient Survey.

Science.gov (United States)

Zhou, Yin; Abel, Gary; Warren, Fiona; Roland, Martin; Campbell, John; Lyratzopoulos, Georgios

2015-05-01

It is believed that some patients are more likely to use out-of-hours primary care services because of difficulties in accessing in-hours care, but substantial evidence about any such association is missing. We analysed data from 567,049 respondents to the 2011/2012 English General Practice Patient Survey who reported at least one in-hours primary care consultation in the preceding 6 months. Of those respondents, 7% also reported using out-of-hours primary care. We used logistic regression to explore associations between use of out-of-hours primary care and five measures of in-hours access (ease of getting through on the telephone, ability to see a preferred general practitioner, ability to get an urgent or routine appointment and convenience of opening hours). We illustrated the potential for reduction in use of out-of-hours primary care in a model where access to in-hours care was made optimal. Worse in-hours access was associated with greater use of out-of-hours primary care for each access factor. In multivariable analysis adjusting for access and patient characteristic variables, worse access was independently associated with increased out-of-hours use for all measures except ease of telephone access. Assuming these associations were causal, we estimated that an 11% relative reduction in use of out-of-hours primary care services in England could be achievable if access to in-hours care were optimal. This secondary quantitative analysis provides evidence for an association between difficulty in accessing in-hours care and use of out-of-hours primary care services. The findings can motivate the development of interventions to improve in-hour access. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

The cost of travel time variability: three measures with properties

DEFF Research Database (Denmark)

Engelson, Leonid; Fosgerau, Mogens

2016-01-01

This paper explores the relationships between three types of measures of the cost of travel time variability: measures based on scheduling preferences and implicit departure time choice, Bernoulli type measures based on a univariate function of travel time, and mean-dispersion measures. We...

Quadratic time dependent Hamiltonians and separation of variables

International Nuclear Information System (INIS)

Anzaldo-Meneses, A.

2017-01-01

Time dependent quantum problems defined by quadratic Hamiltonians are solved using canonical transformations. The Green’s function is obtained and a comparison with the classical Hamilton–Jacobi method leads to important geometrical insights like exterior differential systems, Monge cones and time dependent Gaussian metrics. The Wei–Norman approach is applied using unitary transformations defined in terms of generators of the associated Lie groups, here the semi-direct product of the Heisenberg group and the symplectic group. A new explicit relation for the unitary transformations is given in terms of a finite product of elementary transformations. The sequential application of adequate sets of unitary transformations leads naturally to a new separation of variables method for time dependent Hamiltonians, which is shown to be related to the Inönü–Wigner contraction of Lie groups. The new method allows also a better understanding of interacting particles or coupled modes and opens an alternative way to analyze topological phases in driven systems. - Highlights: • Exact unitary transformation reducing time dependent quadratic quantum Hamiltonian to zero. • New separation of variables method and simultaneous uncoupling of modes. • Explicit examples of transformations for one to four dimensional problems. • New general evolution equation for quadratic form in the action, respectively Green’s function.

24-Hour protein, arginine and citrulline metabolism in fed critically ill children – a stable isotope tracer study

Science.gov (United States)

de Betue, Carlijn T.I.; Garcia Casal, Xiomara C.; van Waardenburg, Dick A.; Schexnayder, Stephen M.; Joosten, Koen F.M.; Deutz, Nicolaas E.P.; Engelen, Marielle P.K.J.

2017-01-01

Background & aims The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4–8h) time period and extrapolate results to 24-hour. However, 24-hour measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-hour appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children. Methods In eight critically ill children, admitted to the pediatric (n=4) or cardiovascular (n=4) intensive care unit, aged 0–10 years, receiving continuous (par)enteral nutrition with protein intake 1.0–3.7 g/kg/day, a 24-hour stable isotope tracer protocol was carried out. L-[ring-2H5]-phenylalanine, L-[3,3-2H2]-tyrosine, L-[5,5,5-2H3]-leucine, L-[guanido-15N2]-arginine and L-[5-13C-3,3,4,4-2H4]-citrulline were infused intravenously and L-[15N]-phenylalanine and L-[1-13C]leucine enterally. Arterial blood was sampled every hour. Results Coefficients of variation, representing intra-individual variability, of the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline were high, on average 14–19% for intravenous tracers and 23–26% for enteral tracers. No evident circadian rhythm was present. The pattern and overall 24-hour level of whole body protein balance differed per individual. Conclusions In continuously fed stable critically ill children, the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline show high variability. This should be kept in mind when performing stable isotope studies in this population. There was no apparent circadian rhythm. PMID:28089618

Time-series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

Science.gov (United States)

Philip, Brendan T.; Denny, Alden R.; Solomon, Evan A.; Kelley, Deborah S.

2016-03-01

An estimated 500-2500 gigatons of methane carbon is sequestered in gas hydrate at continental margins and some of these deposits are associated with overlying methane seeps. To constrain the impact that seeps have on methane concentrations in overlying ocean waters and to characterize the bubble plumes that transport methane vertically into the ocean, water samples and time-series acoustic images were collected above Southern Hydrate Ridge (SHR), a well-studied hydrate-bearing seep site ˜90 km west of Newport, Oregon. These data were coregistered with robotic vehicle observations to determine the origin of the seeps, the plume rise heights above the seafloor, and the temporal variability in bubble emissions. Results show that the locations of seep activity and bubble release remained unchanged over the 3 year time-series investigation, however, the magnitude of gas release was highly variable on hourly time scales. Bubble plumes were detected to depths of 320-620 m below sea level (mbsl), in several cases exceeding the upper limit of hydrate stability by ˜190 m. For the first time, sustained gas release was imaged at the Pinnacle site and in-between the Pinnacle and the Summit area of venting, indicating that the subseafloor transport of fluid and gas is not restricted to the Summit at SHR, requiring a revision of fluid-flow models. Dissolved methane concentrations above background levels from 100 to 300 mbsl are consistent with long-term seep gas transport into the upper water column, which may lead to the build-up of seep-derived carbon in regional subsurface waters and to increases in associated biological activity.

Validity and reproducibility of self-reported working hours among Japanese male employees.

Science.gov (United States)

Imai, Teppei; Kuwahara, Keisuke; Miyamoto, Toshiaki; Okazaki, Hiroko; Nishihara, Akiko; Kabe, Isamu; Mizoue, Tetsuya; Dohi, Seitaro

2016-07-22

Working long hours is a potential health hazard. Although self-reporting of working hours in various time frames has been used in epidemiologic studies, its validity is unclear. The objective of this study was to examine the validity and reproducibility of self-reported working hours among Japanese male employees. The participants were 164 male employees of four large-scale companies in Japan. For validity, the Spearman correlation between self-reported working hours in the second survey and the working hours recorded by the company was calculated for the following four time frames: daily working hours, monthly overtime working hours in the last month, average overtime working hours in the last 3 months, and the frequency of long working months (≥45 h/month) within the last 12 months. For reproducibility, the intraclass correlation between the first (September 2013) and second surveys (December 2013) was calculated for each of the four time frames. The Spearman correlations between self-reported working hours and those based on company records were 0.74, 0.81, 0.85, and 0.89 for daily, monthly, 3-monthly, and yearly time periods, respectively. The intraclass correlations for self-reported working hours between the two questionnaire surveys were 0.63, 0.66, 0.73, and 0.87 for the respective time frames. The results of the present study among Japanese male employees suggest that the validity of self-reported working hours is high for all four time frames, whereas the reproducibility is moderate to high.

WP RR 15 - Employees' preferences for more or fewer working hours: The effects of usual, contractual and standard working time, family phase and household characteristics and job satisfaction

OpenAIRE

Kea Tijdens

2002-01-01

This study seeks explanations for working time preferences, using cross-sectional multinomial logits for the 2001/2002 Wage Indicator dataset (N=21,727). As expected, the preferences are predominately influenced by working hours’ characteristics, showing that employees with long hours prefer to work shorter hours and that short-hours workers prefer longer hours. New is the finding that salaried employees indeed want to reduce hours whereas hourly paid employees prefer to work longer hours. In...

Effects of implementing time-variable postgraduate training programmes on the organization of teaching hospital departments.

Science.gov (United States)

van Rossum, Tiuri R; Scheele, Fedde; Sluiter, Henk E; Paternotte, Emma; Heyligers, Ide C

2018-01-31

As competency-based education has gained currency in postgraduate medical education, it is acknowledged that trainees, having individual learning curves, acquire the desired competencies at different paces. To accommodate their different learning needs, time-variable curricula have been introduced making training no longer time-bound. This paradigm has many consequences and will, predictably, impact the organization of teaching hospitals. The purpose of this study was to determine the effects of time-variable postgraduate education on the organization of teaching hospital departments. We undertook exploratory case studies into the effects of time-variable training on teaching departments' organization. We held semi-structured interviews with clinical teachers and managers from various hospital departments. The analysis yielded six effects: (1) time-variable training requires flexible and individual planning, (2) learners must be active and engaged, (3) accelerated learning sometimes comes at the expense of clinical expertise, (4) fast-track training for gifted learners jeopardizes the continuity of care, (5) time-variable training demands more of supervisors, and hence, they need protected time for supervision, and (6) hospital boards should support time-variable training. Implementing time-variable education affects various levels within healthcare organizations, including stakeholders not directly involved in medical education. These effects must be considered when implementing time-variable curricula.

The Impacts of Tuition Rate Changes on College Undergraduate Headcounts and Credit Hours Over Time--A Case Study.

Science.gov (United States)

Chressanthis, George A.

1986-01-01

Using 1964-1983 enrollment data for a small Michigan state college, this paper charts tuition rate change impacts on college undergraduate headcounts and credit hours over time. Results indicate that student behavior follows the law of demand, varies with class standing, corroborates human capital investment models, and invalidates uniform tuition…

Continuous 24-hour ocular dimensional profile recording in medically treated normal-tension glaucoma

Directory of Open Access Journals (Sweden)

Lee JWY

2015-01-01

Full Text Available Jacky WY Lee,1,2 Lin Fu,1 Jennifer WH Shum,1 Jonathan CH Chan,3 Jimmy SM Lai1 1Department of Ophthalmology, The University of Hong Kong, Hong Kong; 2Department of Ophthalmology, Caritas Medical Centre, Hong Kong; 3Department of Ophthalmology, Queen Mary Hospital, Hong Kong Purpose: To analyze the 24-hour ocular dimensional profile in normal-tension glaucoma (NTG patients on medical treatment.Methods: Consecutive, medically treated NTG subjects were recruited from a university eye center. Subjects were on a mean of 1.7±0.7 types of antiglaucoma medications and 56.6% were on a prostaglandin analog. A contact lens-based sensor device was worn in one eye of NTG patients to record the intraocular pressure (IOP-related profile for 24 hours, recording the following: variability from mean over 24 hours, nocturnally and diurnally, as well as the number of peaks and troughs diurnally and nocturnally.Results: In 18 NTG subjects, the nocturnal variability around the mean contact lens-based sensor device signal was 48.9% less than the diurnal variability around the mean. The number of peaks was 54.7% less during the nocturnal period than during the diurnal period. The rate of increase in the ocular dimensional profile when going to sleep was significantly greater than the rate of decrease upon waking (P<0.001.Conclusion: In medically treated NTG subjects, there was more variability in the IOP-related pattern during the daytime and there were fewer peaks during sleep. Keywords: intraocular pressure, 24-hour, normal tension glaucoma

Multi-time-step ahead daily and hourly intermittent reservoir inflow prediction by artificial intelligent techniques using lumped and distributed data

Science.gov (United States)

Jothiprakash, V.; Magar, R. B.

2012-07-01

SummaryIn this study, artificial intelligent (AI) techniques such as artificial neural network (ANN), Adaptive neuro-fuzzy inference system (ANFIS) and Linear genetic programming (LGP) are used to predict daily and hourly multi-time-step ahead intermittent reservoir inflow. To illustrate the applicability of AI techniques, intermittent Koyna river watershed in Maharashtra, India is chosen as a case study. Based on the observed daily and hourly rainfall and reservoir inflow various types of time-series, cause-effect and combined models are developed with lumped and distributed input data. Further, the model performance was evaluated using various performance criteria. From the results, it is found that the performances of LGP models are found to be superior to ANN and ANFIS models especially in predicting the peak inflows for both daily and hourly time-step. A detailed comparison of the overall performance indicated that the combined input model (combination of rainfall and inflow) performed better in both lumped and distributed input data modelling. It was observed that the lumped input data models performed slightly better because; apart from reducing the noise in the data, the better techniques and their training approach, appropriate selection of network architecture, required inputs, and also training-testing ratios of the data set. The slight poor performance of distributed data is due to large variations and lesser number of observed values.

Constructing Proxy Variables to Measure Adult Learners' Time Management Strategies in LMS

Science.gov (United States)

Jo, Il-Hyun; Kim, Dongho; Yoon, Meehyun

2015-01-01

This study describes the process of constructing proxy variables from recorded log data within a Learning Management System (LMS), which represents adult learners' time management strategies in an online course. Based on previous research, three variables of total login time, login frequency, and regularity of login interval were selected as…

Regulating danger on the highways: hours of service regulations.

Science.gov (United States)

Mansfield, Daniel; Kryger, Meir

2015-12-01

Current hours of service regulations governing commercial truck drivers in place in the United States, Canada, Australia, and the European Union are summarized and compared to facilitate the assessment of the effectiveness of such provisions in preventing fatigue and drowsiness among truck drivers. Current hours of service provisions governing commercial truck drivers were derived from governmental sources. The commercial truck driver hours of service provisions in the United States, Canada, and the European Union permit drivers to work 14 hours and those of Australia permit drivers to work 12 hours a day on a regular basis. The regulations do not state what a driver may do with time off. They are consistent with a driver being able to drive after 24 hours without sleep. They do not take into account circadian rhythm by linking driving or rest to time of day. Current hours of service regulations governing commercial truck drivers leave gaps--permitting drivers to work long hours on a regular basis, permitting driving after no sleep for 24 hours, and failing to take into account the importance of circadian rhythm, endangering the public safety and the truck drivers themselves. Copyright © 2015 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.

Variable selection for mixture and promotion time cure rate models.

Science.gov (United States)

Masud, Abdullah; Tu, Wanzhu; Yu, Zhangsheng

2016-11-16

Failure-time data with cured patients are common in clinical studies. Data from these studies are typically analyzed with cure rate models. Variable selection methods have not been well developed for cure rate models. In this research, we propose two least absolute shrinkage and selection operators based methods, for variable selection in mixture and promotion time cure models with parametric or nonparametric baseline hazards. We conduct an extensive simulation study to assess the operating characteristics of the proposed methods. We illustrate the use of the methods using data from a study of childhood wheezing. © The Author(s) 2016.

Daily and 3-hourly Variability in Global Fire Emissions and Consequences for Atmospheric Model Predictions of Carbon Monoxide

Science.gov (United States)

Mu, M.; Randerson, J. T.; vanderWerf, G. R.; Giglio, L.; Kasibhatla, P.; Morton, D.; Collatz, G. J.; DeFries, R. S.; Hyer, E. J.; Prins, E. M.;

Job search, hours restrictions, and desired hours of work

NARCIS (Netherlands)

Bloemen, H.G.

2008-01-01

A structural empirical job search model is presented that incorporates the labor supply decision of individuals. The arrival of a job offer is modeled as a random draw from a wage-hours offer distribution. Subjective information is used on desired working hours to identify optimal hours from offered

29 CFR 778.318 - Productive and nonproductive hours of work.

Science.gov (United States)

2010-07-01

... Special Problems Effect of Failure to Count Or Pay for Certain Working Hours § 778.318 Productive and... Act; such nonproductive working hours must be counted and paid for. (b) Compensation payable for... which such nonproductive hours are properly counted as working time but no special hourly rate is...

Chaos synchronization in time-delayed systems with parameter mismatches and variable delay times

International Nuclear Information System (INIS)

Shahverdiev, E.M.; Nuriev, R.A.; Hashimov, R.H.; Shore, K.A.

2004-06-01

We investigate synchronization between two undirectionally linearly coupled chaotic nonidentical time-delayed systems and show that parameter mismatches are of crucial importance to achieve synchronization. We establish that independent of the relation between the delay time in the coupled systems and the coupling delay time, only retarded synchronization with the coupling delay time is obtained. We show that with parameter mismatch or without it neither complete nor anticipating synchronization occurs. We derive existence and stability conditions for the retarded synchronization manifold. We demonstrate our approach using examples of the Ikeda and Mackey Glass models. Also for the first time we investigate chaos synchronization in time-delayed systems with variable delay time and find both existence and sufficient stability conditions for the retarded synchronization manifold with the coupling-delay lag time. (author)

Mistimed food intake and sleep alters 24-hour time-of-day patterns of the human plasma proteome.

Science.gov (United States)

Depner, Christopher M; Melanson, Edward L; McHill, Andrew W; Wright, Kenneth P

2018-06-05

Proteomics holds great promise for understanding human physiology, developing health biomarkers, and precision medicine. However, how much the plasma proteome varies with time of day and is regulated by the master circadian suprachiasmatic nucleus brain clock, assessed here by the melatonin rhythm, is largely unknown. Here, we assessed 24-h time-of-day patterns of human plasma proteins in six healthy men during daytime food intake and nighttime sleep in phase with the endogenous circadian clock (i.e., circadian alignment) versus daytime sleep and nighttime food intake out of phase with the endogenous circadian clock (i.e., circadian misalignment induced by simulated nightshift work). We identified 24-h time-of-day patterns in 573 of 1,129 proteins analyzed, with 30 proteins showing strong regulation by the circadian cycle. Relative to circadian alignment, the average abundance and/or 24-h time-of-day patterns of 127 proteins were altered during circadian misalignment. Altered proteins were associated with biological pathways involved in immune function, metabolism, and cancer. Of the 30 circadian-regulated proteins, the majority peaked between 1400 hours and 2100 hours, and these 30 proteins were associated with basic pathways involved in extracellular matrix organization, tyrosine kinase signaling, and signaling by receptor tyrosine-protein kinase erbB-2. Furthermore, circadian misalignment altered multiple proteins known to regulate glucose homeostasis and/or energy metabolism, with implications for altered metabolic physiology. Our findings demonstrate the circadian clock, the behavioral wake-sleep/food intake-fasting cycle, and interactions between these processes regulate 24-h time-of-day patterns of human plasma proteins and help identify mechanisms of circadian misalignment that may contribute to metabolic dysregulation.

Long working hours and alcohol use

DEFF Research Database (Denmark)

Virtanen, Marianna; Jokela, Markus; Nyberg, Solja T

2015-01-01

.20) in the analysis of prospective published and unpublished data. In the 18 studies with individual participant data it was possible to assess the European Union Working Time Directive, which recommends an upper limit of 48 hours a week. Odds ratios of new onset risky alcohol use for those working 49-54 hours......OBJECTIVE: To quantify the association between long working hours and alcohol use. DESIGN: Systematic review and meta-analysis of published studies and unpublished individual participant data. DATA SOURCES: A systematic search of PubMed and Embase databases in April 2014 for published studies......, supplemented with manual searches. Unpublished individual participant data were obtained from 27 additional studies. REVIEW METHODS: The search strategy was designed to retrieve cross sectional and prospective studies of the association between long working hours and alcohol use. Summary estimates were...

24-Hour Holter Monitoring at the Lagos State University Teaching ...

African Journals Online (AJOL)

However, only a minority of such patients have documented and confirmed clinically significant tachyarrhythmias in this study. A subsequent larger prospective study would shed more light on this subject. Key Words: Electrocardiogram (ECG), 24-hour Holter, Heart Rate variability. Paroxysmal tachyarrhythmias.

Forecasting Hourly Water Demands With Seasonal Autoregressive Models for Real-Time Application

Science.gov (United States)

Chen, Jinduan; Boccelli, Dominic L.

2018-02-01

Consumer water demands are not typically measured at temporal or spatial scales adequate to support real-time decision making, and recent approaches for estimating unobserved demands using observed hydraulic measurements are generally not capable of forecasting demands and uncertainty information. While time series modeling has shown promise for representing total system demands, these models have generally not been evaluated at spatial scales appropriate for representative real-time modeling. This study investigates the use of a double-seasonal time series model to capture daily and weekly autocorrelations to both total system demands and regional aggregated demands at a scale that would capture demand variability across a distribution system. Emphasis was placed on the ability to forecast demands and quantify uncertainties with results compared to traditional time series pattern-based demand models as well as nonseasonal and single-seasonal time series models. Additional research included the implementation of an adaptive-parameter estimation scheme to update the time series model when unobserved changes occurred in the system. For two case studies, results showed that (1) for the smaller-scale aggregated water demands, the log-transformed time series model resulted in improved forecasts, (2) the double-seasonal model outperformed other models in terms of forecasting errors, and (3) the adaptive adjustment of parameters during forecasting improved the accuracy of the generated prediction intervals. These results illustrate the capabilities of time series modeling to forecast both water demands and uncertainty estimates at spatial scales commensurate for real-time modeling applications and provide a foundation for developing a real-time integrated demand-hydraulic model.

Simulating variable-density flows with time-consistent integration of Navier-Stokes equations

Science.gov (United States)

Lu, Xiaoyi; Pantano, Carlos

2017-11-01

In this talk, we present several features of a high-order semi-implicit variable-density low-Mach Navier-Stokes solver. A new formulation to solve pressure Poisson-like equation of variable-density flows is highlighted. With this formulation of the numerical method, we are able to solve all variables with a uniform order of accuracy in time (consistent with the time integrator being used). The solver is primarily designed to perform direct numerical simulations for turbulent premixed flames. Therefore, we also address other important elements, such as energy-stable boundary conditions, synthetic turbulence generation, and flame anchoring method. Numerical examples include classical non-reacting constant/variable-density flows, as well as turbulent premixed flames.

CORRELATION OF SPOT URINE ALBUMIN AND 12-HOUR URINE PROTEIN WITH 24-HOUR URINE PROTEIN IN PRE-ECLAMPSIA

Directory of Open Access Journals (Sweden)

S. Vinayachandran

2017-11-01

Full Text Available BACKGROUND Pre-eclampsia is defined as the development of new-onset hypertension in the second half of pregnancy often accompanied by new-onset proteinuria with other signs and symptoms. Proteinuria is defined by the excretion of 300 mg or more of protein in a 24-hour urine collection. To avoid time consumed in collection of 24-hour urine specimens, efforts have been made to develop faster methods to determine concentration of urine protein. Preliminary studies have suggested that 12-hour urine protein collection maybe adequate for evaluation of pre-eclampsia with advantage of early diagnosis and treatment of pre-eclampsia as well as potential for early hospital discharge and increased compliance with specimen collection. The aim of the study is to evaluate and correlate spot urine albumin and 12-hour urine protein with 24-hour urine protein in pre-eclampsia. MATERIALS AND METHODS A diagnostic evaluation study- a 24-hour urine protein, 12-hour urine protein and spot urine albumin results are analysed. Correlation of 12-hour urine protein and spot urine albumin with 24-hour urine protein is analysed using SPSS software. The strength of correlation was measured by Pearson’s correlation coefficient (r. Student’s t-test and Chi-square tests were used to compare patients with and without 24-hour urine protein ≥300 mg. Probability value of 165 mg with 24-hour urine protein ≥300 mg suggest that this test has role in the evaluation of women with suspected pre-eclampsia and could be substituted for 24-hour urine protein as a simple, faster and cheaper method.

Evidence for a time-invariant phase variable in human ankle control.

Directory of Open Access Journals (Sweden)

Robert D Gregg

Full Text Available Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms. In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control.

Long working hours and physical activity.

Science.gov (United States)

Angrave, David; Charlwood, Andy; Wooden, Mark

2015-08-01

It is widely believed that persons employed in jobs demanding long working hours are at greater risk of physical inactivity than other workers, primarily because they have less leisure time available to undertake physical activity. The aim of this study was to test this hypothesis using prospective data obtained from a nationally representative sample of employed persons. Longitudinal data from the Household, Income and Labour Dynamics in Australia Survey (93,367 observations from 17,893 individuals) were used to estimate conditional fixed effects logistic regression models of the likelihood of moderate or vigorous physical exercise for at least 30 min, at least four times a week. No significant associations between long working hours and the incidence of healthy levels of physical activity were uncovered once other exogenous influences on activity levels were controlled for. The odds of men or women who usually work 60 or more hours per week exercising at healthy levels were 6% and 11% less, respectively, than those of comparable persons working a more standard 35-40 h/week; however, neither estimate was significantly different from 0 at 95% CI. The findings suggest that there is no trade-off between long working hours and physical activity in Australia. It is argued that these findings are broadly consistent with previous research studies from Anglo-Saxon countries (where long working hours are pervasive) that employed large nationally representative samples. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Predictor variables for a half marathon race time in recreational male runners

Directory of Open Access Journals (Sweden)

Rüst CA

2011-08-01

Full Text Available Christoph Alexander Rüst1, Beat Knechtle1,2, Patrizia Knechtle2, Ursula Barandun1, Romuald Lepers3, Thomas Rosemann11Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland; 2Gesundheitszentrum St Gallen, St Gallen, Switzerland; 3INSERM U887, University of Burgundy, Faculty of Sport Sciences, Dijon, FranceAbstract: The aim of this study was to investigate predictor variables of anthropometry, training, and previous experience in order to predict a half marathon race time for future novice recreational male half marathoners. Eighty-four male finishers in the ‘Half Marathon Basel’ completed the race distance within (mean and standard deviation, SD 103.9 (16.5 min, running at a speed of 12.7 (1.9 km/h. After multivariate analysis of the anthropometric characteristics, body mass index (r = 0.56, suprailiacal (r = 0.36 and medial calf skin fold (r = 0.53 were related to race time. For the variables of training and previous experience, speed in running of the training sessions (r = –0.54 were associated with race time. After multivariate analysis of both the significant anthropometric and training variables, body mass index (P = 0.0150 and speed in running during training (P = 0.0045 were related to race time. Race time in a half marathon might be partially predicted by the following equation (r2 = 0.44: Race time (min = 72.91 + 3.045 * (body mass index, kg/m2 –3.884 * (speed in running during training, km/h for recreational male runners. To conclude, variables of both anthropometry and training were related to half marathon race time in recreational male half marathoners and cannot be reduced to one single predictor variable.Keywords: anthropometry, body fat, skin-folds, training, endurance

29 CFR 778.319 - Paying for but not counting hours worked.

Science.gov (United States)

2010-07-01

... working time under the Act, coupled with a provision that these hours will not be counted as working time... more hours have been worked, the employee must be paid overtime compensation at not less than one and... 29 Labor 3 2010-07-01 2010-07-01 false Paying for but not counting hours worked. 778.319 Section...

Working hours in a period of low economic growth

OpenAIRE

Walterskirchen, Ewald

2016-01-01

Collectively agreed reductions of working hours phased out in Europe in the 1990s. During the last two decades, working time became more flexible and heterogeneous. Working hours of full-time employees in the EU hardly changed. The strong increase in part-time work was the outstanding phenomenon. Today, one third of female employees and almost ten percent of male employees work part-time. In a period of slow growth, productivity gains will be squeezed by subdued investment and low capacity ut...

THE TIME DOMAIN SPECTROSCOPIC SURVEY: VARIABLE SELECTION AND ANTICIPATED RESULTS

Energy Technology Data Exchange (ETDEWEB)

Morganson, Eric; Green, Paul J. [Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Anderson, Scott F.; Ruan, John J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Eracleous, Michael; Brandt, William Nielsen [Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802 (United States); Kelly, Brandon [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106-9530 (United States); Badenes, Carlos [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara St, Pittsburgh, PA 15260 (United States); Bañados, Eduardo [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Blanton, Michael R. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Bershady, Matthew A. [Department of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53706 (United States); Borissova, Jura [Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Casilla 5030, and Millennium Institute of Astrophysics (MAS), Santiago (Chile); Burgett, William S. [GMTO Corp, Suite 300, 251 S. Lake Ave, Pasadena, CA 91101 (United States); Chambers, Kenneth, E-mail: emorganson@cfa.harvard.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); and others

2015-06-20

We present the selection algorithm and anticipated results for the Time Domain Spectroscopic Survey (TDSS). TDSS is an Sloan Digital Sky Survey (SDSS)-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) subproject that will provide initial identification spectra of approximately 220,000 luminosity-variable objects (variable stars and active galactic nuclei across 7500 deg{sup 2} selected from a combination of SDSS and multi-epoch Pan-STARRS1 photometry. TDSS will be the largest spectroscopic survey to explicitly target variable objects, avoiding pre-selection on the basis of colors or detailed modeling of specific variability characteristics. Kernel Density Estimate analysis of our target population performed on SDSS Stripe 82 data suggests our target sample will be 95% pure (meaning 95% of objects we select have genuine luminosity variability of a few magnitudes or more). Our final spectroscopic sample will contain roughly 135,000 quasars and 85,000 stellar variables, approximately 4000 of which will be RR Lyrae stars which may be used as outer Milky Way probes. The variability-selected quasar population has a smoother redshift distribution than a color-selected sample, and variability measurements similar to those we develop here may be used to make more uniform quasar samples in large surveys. The stellar variable targets are distributed fairly uniformly across color space, indicating that TDSS will obtain spectra for a wide variety of stellar variables including pulsating variables, stars with significant chromospheric activity, cataclysmic variables, and eclipsing binaries. TDSS will serve as a pathfinder mission to identify and characterize the multitude of variable objects that will be detected photometrically in even larger variability surveys such as Large Synoptic Survey Telescope.

Determining optimal interconnection capacity on the basis of hourly demand and supply functions of electricity

International Nuclear Information System (INIS)

Keppler, Jan Horst; Meunier, William; Coquentin, Alexandre

2017-01-01

Interconnections for cross-border electricity flows are at the heart of the project to create a common European electricity market. At the time, increase in production from variable renewables clustered during a limited numbers of hours reduces the availability of existing transport infrastructures. This calls for higher levels of optimal interconnection capacity than in the past. In complement to existing scenario-building exercises such as the TYNDP that respond to the challenge of determining optimal levels of infrastructure provision, the present paper proposes a new empirically-based methodology to perform Cost-Benefit analysis for the determination of optimal interconnection capacity, using as an example the French-German cross-border trade. Using a very fine dataset of hourly supply and demand curves (aggregated auction curves) for the year 2014 from the EPEX Spot market, it constructs linearized net export (NEC) and net import demand curves (NIDC) for both countries. This allows assessing hour by hour the welfare impacts for incremental increases in interconnection capacity. Summing these welfare increases over the 8 760 hours of the year, this provides the annual total for each step increase of interconnection capacity. Confronting welfare benefits with the annual cost of augmenting interconnection capacity indicated the socially optimal increase in interconnection capacity between France and Germany on the basis of empirical market micro-data. (authors)

Out of hours ophthalmic surgery: a UK national survey.

Science.gov (United States)

O'Colmain, U; Wright, M; Bennett, H; MacEwen, C J

2013-03-01

There have been significant changes in the management of out of hours services in ophthalmology recently. The European Working Time Directive (EWTD) and economic measures have anecdotally reduced the availability of staff and facilities outside normal working hours, and there have been various responses to the provision of emergency surgical care. There are disparate attitudes to the optimum management of the emergency surgical case. We sought to establish a nationwide picture of the management of out of hours surgery. A questionnaire was distributed to every consultant ophthalmologist working in the NHS and registered with the Royal College of Ophthalmologists (n=947). Information was requested regarding departmental and personal policies, local facilities, and personal beliefs regarding emergency surgery. A total of 440 (46.5%) questionnaires were returned from 155 units; 18.7% of the units had no out of hours services or no operating facilities. Sixty-three percent of units reported a local policy regarding a time after which patients should not be taken to theatre. For 57%, this time began between 2100 hours and midnight. The most common reasons for not operating after a certain time were 'belief that delay does not significantly affect the outcome' (41.6%), 'delayed access to theatre due to competition with other surgical specialities' (40%), and 'no specialist ophthalmic-theatre nursing input' (32.7%). We report the first nationwide study on out of hours ophthalmological surgical working practices. This demonstrates variation in work patterns. It is significant to patients and ophthalmologists that there should be units in United Kingdom without full local facilities and staff.

Emotional exhaustion may trigger cut in working hours

NARCIS (Netherlands)

Koppes, L.

2012-01-01

Researchers in the Netherlands have been examining to what extent workers are modifying their hours to cope with high levels of work-related emotional exhaustion. Findings reveal that most full-time employees would prefer a cut in their hours, with those reporting emotional exhaustion wanting a

Between-centre variability versus variability over time in DXA whole body measurements evaluated using a whole body phantom

Energy Technology Data Exchange (ETDEWEB)

Louis, Olivia [Department of Radiology, AZ-VUB, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussel (Belgium)]. E-mail: olivia.louis@az.vub.ac.be; Verlinde, Siska [Belgian Study Group for Pediatric Endocrinology (Belgium); Thomas, Muriel [Belgian Study Group for Pediatric Endocrinology (Belgium); De Schepper, Jean [Department of Pediatrics, AZ-VUB, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussel (Belgium)

2006-06-15

This study aimed to compare the variability of whole body measurements, using dual energy X-ray absorptiometry (DXA), among geographically distinct centres versus that over time in a given centre. A Hologic-designed 28 kg modular whole body phantom was used, including high density polyethylene, gray polyvinylchloride and aluminium. It was scanned on seven Hologic QDR 4500 DXA devices, located in seven centres and was also repeatedly (n = 18) scanned in the reference centre, over a time span of 5 months. The mean between-centre coefficient of variation (CV) ranged from 2.0 (lean mass) to 5.6% (fat mass) while the mean within-centre CV ranged from 0.3 (total mass) to 4.7% (total area). Between-centre variability compared well with within-centre variability for total area, bone mineral content and bone mineral density, but was significantly higher for fat (p < 0.001), lean (p < 0.005) and total mass (p < 0.001). Our results suggest that, even when using the same device, the between-centre variability remains a matter of concern, particularly where body composition is concerned.

Using exogenous variables in testing for monotonic trends in hydrologic time series

Science.gov (United States)

Alley, William M.

1988-01-01

One approach that has been used in performing a nonparametric test for monotonic trend in a hydrologic time series consists of a two-stage analysis. First, a regression equation is estimated for the variable being tested as a function of an exogenous variable. A nonparametric trend test such as the Kendall test is then performed on the residuals from the equation. By analogy to stagewise regression and through Monte Carlo experiments, it is demonstrated that this approach will tend to underestimate the magnitude of the trend and to result in some loss in power as a result of ignoring the interaction between the exogenous variable and time. An alternative approach, referred to as the adjusted variable Kendall test, is demonstrated to generally have increased statistical power and to provide more reliable estimates of the trend slope. In addition, the utility of including an exogenous variable in a trend test is examined under selected conditions.

Stability of Delayed Hopfield Neural Networks with Variable-Time Impulses

Directory of Open Access Journals (Sweden)

Yangjun Pei

2014-01-01

Full Text Available In this paper the globally exponential stability criteria of delayed Hopfield neural networks with variable-time impulses are established. The proposed criteria can also be applied in Hopfield neural networks with fixed-time impulses. A numerical example is presented to illustrate the effectiveness of our theoretical results.

Correlated Temporal and Spectral Variability

Science.gov (United States)

Swank, Jean H.

2007-01-01

The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.

Association between different measurements of blood pressure variability by ABP monitoring and ankle-brachial index.

Science.gov (United States)

Wittke, Estefânia; Fuchs, Sandra C; Fuchs, Flávio D; Moreira, Leila B; Ferlin, Elton; Cichelero, Fábio T; Moreira, Carolina M; Neyeloff, Jeruza; Moreira, Marina B; Gus, Miguel

2010-11-05

Blood pressure (BP) variability has been associated with cardiovascular outcomes, but there is no consensus about the more effective method to measure it by ambulatory blood pressure monitoring (ABPM). We evaluated the association between three different methods to estimate BP variability by ABPM and the ankle brachial index (ABI). In a cross-sectional study of patients with hypertension, BP variability was estimated by the time rate index (the first derivative of SBP over time), standard deviation (SD) of 24-hour SBP; and coefficient of variability of 24-hour SBP. ABI was measured with a doppler probe. The sample included 425 patients with a mean age of 57 ± 12 years, being 69.2% women, 26.1% current smokers and 22.1% diabetics. Abnormal ABI (≤ 0.90 or ≥ 1.40) was present in 58 patients. The time rate index was 0.516 ± 0.146 mmHg/min in patients with abnormal ABI versus 0.476 ± 0.124 mmHg/min in patients with normal ABI (P = 0.007). In a logistic regression model the time rate index was associated with ABI, regardless of age (OR = 6.9, 95% CI = 1.1- 42.1; P = 0.04). In a multiple linear regression model, adjusting for age, SBP and diabetes, the time rate index was strongly associated with ABI (P < 0.01). None of the other indexes of BP variability were associated with ABI in univariate and multivariate analyses. Time rate index is a sensible method to measure BP variability by ABPM. Its performance for risk stratification of patients with hypertension should be explored in longitudinal studies.

29 CFR 785.21 - Less than 24-hour duty.

Science.gov (United States)

2010-07-01

... Sleeping Time and Certain Other Activities § 785.21 Less than 24-hour duty. An employee who is required to be on duty for less than 24 hours is working even though he is permitted to sleep or engage in other... 29 Labor 3 2010-07-01 2010-07-01 false Less than 24-hour duty. 785.21 Section 785.21 Labor...

Electric Motors Maintenance Planning From Its Operating Variables

Science.gov (United States)

Rodrigues, Francisco; Fonseca, Inácio; Farinha, José Torres; Ferreira, Luís; Galar, Diego

2017-09-01

The maintenance planning corresponds to an approach that seeks to maximize the availability of equipment and, consequently, increase the levels of competitiveness of companies by increasing production times. This paper presents a maintenance planning based on operating variables (number of hours worked, duty cycles, number of revolutions) to maximizing the availability of operation of electrical motors. The reading of the operating variables and its sampling is done based on predetermined sampling cycles and subsequently is made the data analysis through time series algorithms aiming to launch work orders before reaching the variables limit values. This approach is supported by tools and technologies such as logical applications that enable a graphical user interface for access to relevant information about their Physical Asset HMI (Human Machine Interface), including the control and supervision by acquisition through SCADA (Supervisory Control And data acquisition) data, also including the communication protocols among different logical applications.

Meeting the Canadian 24-Hour Movement Guidelines for Children and Youth.

Science.gov (United States)

Roberts, Karen C; Yao, Xiaoquan; Carson, Valerie; Chaput, Jean-Philippe; Janssen, Ian; Tremblay, Mark S

2017-10-18

The Canadian 24-Hour Movement Guidelines for Children and Youth: An Integration of Physical Activity, Sedentary Behaviour, and Sleep , provide specific recommendations on the amount of time over a typical 24-hour day that children and youth aged 5 to 17 should spend in moderate-to-vigorous physical activity (at least 60 minutes), recreational screen time (no more than 2 hours), and sleep (9 to 11 hours for 5- to 13-year-olds; 8 to 10 hours for 14- to 17-year-olds). Based on combined results of cycles 2 (2009-to-2011) and 3 (2012-to-2013) of the Canadian Health Measures Survey, this analysis examines average daily moderate-to-vigorous physical activity, screen time and sleep duration of 5- to 11-year-olds and 12- to 17-year-olds, and the percentages meeting the 24-Hour Guidelines' recommendations. Findings are presented overall and by age group and sex. Differences in average daily times between groups were tested for statistical significance, as weredifferences between groups in the percentages meeting each recommendation and combination of recommendations. Overall, 17.5% of children and youth met the 24-Hour Guidelines' specific time recommendations. Higher percentages of children than youth (29.6% versus 5.5%) and boys than girls (22.9% versus 11.8%) met the recommendations. About a third (36.3%) met two of the three recommendations. Recommendations for moderate-to-vigorous physical activity, sedentary behaviour, and sleep have higher levels of adherence among children than youth.

Association between different measurements of blood pressure variability by ABP monitoring and ankle-brachial index

Directory of Open Access Journals (Sweden)

Moreira Leila B

2010-11-01

Full Text Available Abstract Background Blood pressure (BP variability has been associated with cardiovascular outcomes, but there is no consensus about the more effective method to measure it by ambulatory blood pressure monitoring (ABPM. We evaluated the association between three different methods to estimate BP variability by ABPM and the ankle brachial index (ABI. Methods and Results In a cross-sectional study of patients with hypertension, BP variability was estimated by the time rate index (the first derivative of SBP over time, standard deviation (SD of 24-hour SBP; and coefficient of variability of 24-hour SBP. ABI was measured with a doppler probe. The sample included 425 patients with a mean age of 57 ± 12 years, being 69.2% women, 26.1% current smokers and 22.1% diabetics. Abnormal ABI (≤ 0.90 or ≥ 1.40 was present in 58 patients. The time rate index was 0.516 ± 0.146 mmHg/min in patients with abnormal ABI versus 0.476 ± 0.124 mmHg/min in patients with normal ABI (P = 0.007. In a logistic regression model the time rate index was associated with ABI, regardless of age (OR = 6.9, 95% CI = 1.1- 42.1; P = 0.04. In a multiple linear regression model, adjusting for age, SBP and diabetes, the time rate index was strongly associated with ABI (P Conclusion Time rate index is a sensible method to measure BP variability by ABPM. Its performance for risk stratification of patients with hypertension should be explored in longitudinal studies.

Sleep and circadian variability in people with delayed sleep-wake phase disorder versus healthy controls.

Science.gov (United States)

Burgess, Helen J; Park, Margaret; Wyatt, James K; Rizvydeen, Muneer; Fogg, Louis F

2017-06-01

To compare sleep and circadian variability in adults with delayed sleep-wake phase disorder (DSWPD) to healthy controls. Forty participants (22 DSWPD, 18 healthy controls) completed a ten-day protocol, consisting of DLMO assessments on two consecutive nights, a five-day study break, followed by two more DLMO assessments. All participants were instructed to sleep within one hour of their self-reported average sleep schedule for the last four days of the study break. We analyzed the participants' wrist actigraphy data during these four days to examine intraindividual variability in sleep timing, duration and efficiency. We also examined shifts in the DLMO from before and after the study break. Under the same conditions, people with DSWPD had significantly more variable wake times and total sleep time than healthy controls (p ≤ 0.015). Intraindividual variability in sleep onset time and sleep efficiency was similar between the two groups (p ≥ 0.30). The DLMO was relatively stable across the study break, with only 11% of controls but 27% of DSWPDs showed more than a one hour shift in the DLMO. Only in the DSWPD sample was greater sleep variability associated with a larger shift in the DLMO (r = 0.46, p = 0.03). These results suggest that intraindividual variability in sleep can be higher in DSWPD versus healthy controls, and this may impact variability in the DLMO. DSWPD patients with higher intraindividual variability in sleep are more likely to have a shifting DLMO, which could impact sleep symptoms and the optimal timing of light and/or melatonin treatment for DSWPD. Circadian Phase Assessments at Home, http://clinicaltrials.gov/show/NCT01487252, NCT01487252. Copyright © 2017 Elsevier B.V. All rights reserved.

Long Pulse Integrator of Variable Integral Time Constant

International Nuclear Information System (INIS)

Wang Yong; Ji Zhenshan; Du Xiaoying; Wu Yichun; Li Shi; Luo Jiarong

2010-01-01

A kind of new long pulse integrator was designed based on the method of variable integral time constant and deducting integral drift by drift slope. The integral time constant can be changed by choosing different integral resistors, in order to improve the signal-to-noise ratio, and avoid output saturation; the slope of integral drift of a certain period of time can be calculated by digital signal processing, which can be used to deduct the drift of original integral signal in real time to reduce the integral drift. The tests show that this kind of long pulse integrator is good at reducing integral drift, which also can eliminate the effects of changing integral time constant. According to experiments, the integral time constant can be changed by remote control and manual adjustment of integral drift is avoided, which can improve the experiment efficiency greatly and can be used for electromagnetic measurement in Tokamak experiment. (authors)

Automatic classification of time-variable X-ray sources

Energy Technology Data Exchange (ETDEWEB)

Lo, Kitty K.; Farrell, Sean; Murphy, Tara; Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia)

2014-05-01

To maximize the discovery potential of future synoptic surveys, especially in the field of transient science, it will be necessary to use automatic classification to identify some of the astronomical sources. The data mining technique of supervised classification is suitable for this problem. Here, we present a supervised learning method to automatically classify variable X-ray sources in the Second XMM-Newton Serendipitous Source Catalog (2XMMi-DR2). Random Forest is our classifier of choice since it is one of the most accurate learning algorithms available. Our training set consists of 873 variable sources and their features are derived from time series, spectra, and other multi-wavelength contextual information. The 10 fold cross validation accuracy of the training data is ∼97% on a 7 class data set. We applied the trained classification model to 411 unknown variable 2XMM sources to produce a probabilistically classified catalog. Using the classification margin and the Random Forest derived outlier measure, we identified 12 anomalous sources, of which 2XMM J180658.7–500250 appears to be the most unusual source in the sample. Its X-ray spectra is suggestive of a ultraluminous X-ray source but its variability makes it highly unusual. Machine-learned classification and anomaly detection will facilitate scientific discoveries in the era of all-sky surveys.

Automatic classification of time-variable X-ray sources

International Nuclear Information System (INIS)

Lo, Kitty K.; Farrell, Sean; Murphy, Tara; Gaensler, B. M.

2014-01-01

To maximize the discovery potential of future synoptic surveys, especially in the field of transient science, it will be necessary to use automatic classification to identify some of the astronomical sources. The data mining technique of supervised classification is suitable for this problem. Here, we present a supervised learning method to automatically classify variable X-ray sources in the Second XMM-Newton Serendipitous Source Catalog (2XMMi-DR2). Random Forest is our classifier of choice since it is one of the most accurate learning algorithms available. Our training set consists of 873 variable sources and their features are derived from time series, spectra, and other multi-wavelength contextual information. The 10 fold cross validation accuracy of the training data is ∼97% on a 7 class data set. We applied the trained classification model to 411 unknown variable 2XMM sources to produce a probabilistically classified catalog. Using the classification margin and the Random Forest derived outlier measure, we identified 12 anomalous sources, of which 2XMM J180658.7–500250 appears to be the most unusual source in the sample. Its X-ray spectra is suggestive of a ultraluminous X-ray source but its variability makes it highly unusual. Machine-learned classification and anomaly detection will facilitate scientific discoveries in the era of all-sky surveys.

Temporal changes in climatic variables and their impact on crop yields in southwestern China.

Science.gov (United States)

Liu, Hong-Bin; Gou, Yu; Wang, Hong-Ye; Li, Hong-Mei; Wu, Wei

2014-08-01

Knowledge of variability in climatic variables changes and its impact on crop yields is important for farmers and policy makers, especially in southwestern China where rainfed agriculture is dominant. In the current study, six climatic parameters (mean temperature, rainfall, relative humidity, sunshine hours, temperature difference, and rainy days) and aggregated yields of three main crops (rice: Oryza sativa L., oilseed rape: Brassica napus L., and tobacco: Nicotiana tabacum L.) during 1985-2010 were collected and analyzed for Chongqing-a large agricultural municipality of China. Climatic variables changes were detected by Mann-Kendall test. Increased mean temperature and temperature difference and decreased relative humidity were found in annual and oilseed rape growth time series (Pchanges in climatic variables in this region. Yield of rice increased with rainfall (Pclimatic variables to crop yields. Temperature difference and sunshine hours had higher direct and indirect effects via other climatic variables on yields of rice and tobacco. Mean temperature, relative humidity, rainy days, and temperature difference had higher direct and indirect effects via others on yield of oilseed rape.

Hourly changes in sea surface salinity in coastal waters recorded by Geostationary Ocean Color Imager

Science.gov (United States)

Liu, Rongjie; Zhang, Jie; Yao, Haiyan; Cui, Tingwei; Wang, Ning; Zhang, Yi; Wu, Lingjuan; An, Jubai

2017-09-01

In this study, we monitored hourly changes in sea surface salinity (SSS) in turbid coastal waters from geostationary satellite ocean color images for the first time, using the Bohai Sea as a case study. We developed a simple multi-linear statistical regression model to retrieve SSS data from Geostationary Ocean Color Imager (GOCI) based on an in situ satellite matched-up dataset (R2 = 0.795; N = 41; Range: 26.4 to 31.9 psμ). The model was then validated using independent continuous SSS measurements from buoys, with the average percentage difference of 0.65%. The model was applied to GOCI images from the dry season during an astronomical tide to characterize hourly changes in SSS in the Bohai Sea. We found that the model provided reasonable estimates of the hourly changes in SSS and that trends in the modeled and measured data were similar in magnitude and direction (0.43 vs 0.33 psμ, R2 = 0.51). There were clear diurnal variations in the SSS of the Bohai Sea, with a regional average of 0.455 ± 0.079 psμ (0.02-3.77 psμ). The magnitude of the diurnal variations in SSS varied spatially, with large diurnal variability in the nearshore, particularly in the estuary, and small variability in the offshore area. The model for the riverine area was based on the inverse correlation between SSS and CDOM absorption. In the offshore area, the water mass of the North Yellow Sea, characterized by high SSS and low CDOM concentrations, dominated. Analysis of the driving mechanisms showed that the tidal current was the main control on hourly changes in SSS in the Bohai Sea.

Forecasting Kp from solar wind data: input parameter study using 3-hour averages and 3-hour range values

Science.gov (United States)

Wintoft, Peter; Wik, Magnus; Matzka, Jürgen; Shprits, Yuri

2017-11-01

We have developed neural network models that predict Kp from upstream solar wind data. We study the importance of various input parameters, starting with the magnetic component Bz, particle density n, and velocity V and then adding total field B and the By component. As we also notice a seasonal and UT variation in average Kp we include functions of day-of-year and UT. Finally, as Kp is a global representation of the maximum range of geomagnetic variation over 3-hour UT intervals we conclude that sudden changes in the solar wind can have a big effect on Kp, even though it is a 3-hour value. Therefore, 3-hour solar wind averages will not always appropriately represent the solar wind condition, and we introduce 3-hour maxima and minima values to some degree address this problem. We find that introducing total field B and 3-hour maxima and minima, derived from 1-minute solar wind data, have a great influence on the performance. Due to the low number of samples for high Kp values there can be considerable variation in predicted Kp for different networks with similar validation errors. We address this issue by using an ensemble of networks from which we use the median predicted Kp. The models (ensemble of networks) provide prediction lead times in the range 20-90 min given by the time it takes a solar wind structure to travel from L1 to Earth. Two models are implemented that can be run with real time data: (1) IRF-Kp-2017-h3 uses the 3-hour averages of the solar wind data and (2) IRF-Kp-2017 uses in addition to the averages, also the minima and maxima values. The IRF-Kp-2017 model has RMS error of 0.55 and linear correlation of 0.92 based on an independent test set with final Kp covering 2 years using ACE Level 2 data. The IRF-Kp-2017-h3 model has RMSE = 0.63 and correlation = 0.89. We also explore the errors when tested on another two-year period with real-time ACE data which gives RMSE = 0.59 for IRF-Kp-2017 and RMSE = 0.73 for IRF-Kp-2017-h3. The errors as function

The effects of Smoke Free Work Hours in Danish municipalities

OpenAIRE

Tina Termansen; Simon Rask

2017-01-01

Since 2011, 15 Danish municipalities have implemented smoke free work hours, meaning that an employee working for the municipality may not smoke in his or her work time (about 7,5 hours a day). This is a much stricter prevention method, than former strategies preventing smoking mostly at locations and not during working hours. Research concerning the effects of smoke free work hours is non-existing. We therefore wish to look into the specific outcomes of smoke free work hours related to smoki...

Important variables in explaining real-time peak price in the independent power market of Ontario

International Nuclear Information System (INIS)

Rueda, I.E.A.; Marathe, A.

2005-01-01

This paper uses support vector machines (SVM) based learning algorithm to select important variables that help explain the real-time peak electricity price in the Ontario market. The Ontario market was opened to competition only in May 2002. Due to the limited number of observations available, finding a set of variables that can explain the independent power market of Ontario (IMO) real-time peak price is a significant challenge for the traders and analysts. The kernel regressions of the explanatory variables on the IMO real-time average peak price show that non-linear dependencies exist between the explanatory variables and the IMO price. This non-linear relationship combined with the low variable-observation ratio rule out conventional statistical analysis. Hence, we use an alternative machine learning technique to find the important explanatory variables for the IMO real-time average peak price. SVM sensitivity analysis based results find that the IMO's predispatch average peak price, the actual import peak volume, the peak load of the Ontario market and the net available supply after accounting for load (energy excess) are some of the most important variables in explaining the real-time average peak price in the Ontario electricity market. (author)

Lower wages for less hours? A simultaneous wage-hours model for Germany

OpenAIRE

Wolf, Elke

2000-01-01

In this paper the impact of working hours on the gross hourly wage rate of West German women is analyzed. We use a simultaneous wage-hours model which takes into account the participation decision. First, our estimates show that the hourly wage rate is strongly a¤ected by the working hours. In order to avoid any assumptions about the functional form, we estimate linear spline functions. Second, we detect di¤erent wage-hours profiles for specific groups of individuals. Despite these di¤erences...

Long Work Hours, Part-Time Work, and Trends in the Gender Gap in Pay, the Motherhood Wage Penalty, and the Fatherhood Wage Premium

Directory of Open Access Journals (Sweden)

Kim A. Weeden

2016-08-01

Full Text Available We assess how changes in the social organization and compensation of work hours over the last three decades are associated with changes in wage differentials among mothers, fathers, childless women, and childless men. We find that large differences between gender and parental status groups in long work hours (fifty or more per week, coupled with sharply rising hourly wages for long work hours, contributed to rising gender gaps in wages (especially among parents, motherhood wage penalties, and fatherhood wage premiums. Changes in the representation of these groups in part-time work, by contrast, is associated with a decline in the gender gap in wages among parents and in the motherhood wage penalty, but an increase in the fatherhood wage premium. These findings offer important clues into why gender and family wage differentials still persist.

Forecasting hourly patient visits in the emergency department to counteract crowding

DEFF Research Database (Denmark)

Hertzum, Morten

2017-01-01

visits. The data for 2012-2014 were used to create linear regression models, autoregressive integrated moving average (ARIMA) models, and – for purposes of comparison – naïve models of hourly patient arrivals and ED occupancy. Using the models, patient arrivals and ED occupancy were forecasted for every...... hour of January 2015. Results: Hourly patient arrivals were forecasted with a mean percentage error of 47-58% (regression), 49-58% (ARIMA), and 60-76% (naïve). Increasing the forecasting interval decreased the mean percentage error. ED occupancy was forecasted with better accuracy by ARIMA than...... regression models. With ARIMA the mean percentage error of the forecasts of the hourly ED occupancy was 69-73% for three of the EDs and 101% for the last ED. Factors beyond calendar variables might possibly have improved the models of ED occupancy, provided that information about these factors had been...

Relationship between long working hours and depression in two working populations: a structural equation model approach.

Science.gov (United States)

Amagasa, Takashi; Nakayama, Takeo

2012-07-01

To test the hypothesis that relationship reported between long working hours and depression was inconsistent in previous studies because job demand was treated as a confounder. Structural equation modeling was used to construct five models, using work-related factors and depressive mood scale obtained from 218 clerical workers, to test for goodness of fit and was externally validated with data obtained from 1160 sales workers. Multiple logistic regression analysis was also performed. The model that showed that long working hours increased depression risk when job demand was regarded as an intermediate variable was the best fitted model (goodness-of-fit index/root-mean-square error of approximation: 0.981 to 0.996/0.042 to 0.044). The odds ratio for depression risk with work that was high demand and 60 hours or more per week was estimated at 2 to 4 versus work that was low demand and less than 60 hours per week. Long working hours increased depression risk, with job demand being an intermediate variable.

Only so Many Hours: Correlations between Personality and Daily Time Use in a Representative German Panel

Directory of Open Access Journals (Sweden)

Julia M. Rohrer

2018-01-01

Full Text Available Time is a finite resource, strictly limited to 24 hours a day. How people spend these resources is in many ways determined by necessities and external constraints, yet research on personality-situation transactions shows that people also choose their environments to resonate with their personality. This finding implies that daily time use and individual traits should be correlated. However, few studies have linked modern methods for assessing time use to individual differences in personality traits. In this study, we investigate correlations between the Big Five traits and time spent on various daily activities in the German Socio-Economic Panel (SOEP, including 5,456 days in the lives of 1,364 individuals. Results converged towards previously reported personality-situation transactions. For example, extraversion predicted whether or not respondents reported meeting their friends, whereas openness was correlated negatively with watching TV. Effects were modest in size, ranging from r~~.10 to .25. Taking together, our findings corroborate the notion that our personality is robustly associated with the way we spend our lives.

Preliminary results of variable star search using KMTNet data

Directory of Open Access Journals (Sweden)

Jeon Young-Beom

2017-01-01

Full Text Available The KMTNet (Korea Microlensing Telescope Network was completed on October 2nd in 2015. There are three 1.6 m telescopes in Chile (CTIO, Australia (SSO and South Africa (SAAO. The field of view of the CCD camera is 2 degree × 2 degree. We are monitoring and observing the bulge region for 24-hour continuous observations using the KMTNet telescopes. I present the characteristics of CCD camera and telescope, and the status of observation programs. We are still developing CCD cameras to accurate photometry. From the KMTNet data, we can obtain accurate 24-hour continuous time-series data for many variable stars.

Do economic stresses influence child work hours on family farms?

Science.gov (United States)

Gadomski, Anne; de Long, Rachel; Burdick, Patrick; Jenkins, Paul

2005-01-01

Economic stresses are a frequently cited reason for children doing farm work. To explore the relationship between economic indicators and child agricultural work hours between January 2001 and October 2003. This ecologic study design compares trends in aggregate child work hours with national and regional economic indicators. Child work hours were obtained from quarterly surveillance data from a randomized field trial of agricultural task guidelines for children. 2,360 children living or working on 845 farms in central New York participated in the original study. The relationship between child work hours and three economic indicators: national all farm index (AFI) ratio, national fuel index, and regional milk prices was analyzed using times series plots, correlation, and multiple linear regression. The AFI ratio was positively correlated with child work hours (r = 0.49, p = 0.008) but there was no significant correlation between child work hours and fuel or milk prices. Multiple linear regression demonstrated that the relationship between AFI and child work hours is independent of a seasonal effect. Increased child work hours may be associated with periods of higher farm sector productivity, rather than economic stress per se. Findings are limited by the ecologic study design, use of national economic indicators, and the limited number of cycles of child work hours available for time series analysis. Economic conditions may influence decisions about children's farm work.

29 CFR 785.22 - Duty of 24 hours or more.

Science.gov (United States)

2010-07-01

... employee is required to be on duty for 24 hours or more, the employer and the employee may agree to exclude... from hours worked, provided adequate sleeping facilities are furnished by the employer and the employee... of sleeping time and lunch periods constitute hours worked. (Armour v. Wantock, 323 U.S. 126 (1944...

The new Toyota variable valve timing and lift system

Energy Technology Data Exchange (ETDEWEB)

Shimizu, K.; Fuwa, N.; Yoshihara, Y. [Toyota Motor Corporation (Japan); Hori, K. [Toyota Boshoku Corporation (Japan)

2007-07-01

A continuously variable valve timing (duration and phase) and lift system was developed. This system was applied to the valvetrain of a new 2.0L L4 engine (3ZRFAE) for the Japanese market. The system has rocker arms, which allow continuously variable timing and lift, situated between a conventional roller-rocker arm and the camshaft, an electromotor actuator to drive it and a phase mechanism for intake and exhaust camshafts (Dual VVT-i). The rocking center of the rocker arm is stationary, and the axial linear motion of a helical spline changes the initial phase of the rocker arm which varies the timing and lift. The linear motion mechanism uses an original planetary roller screw and is driven by a brushless motor with a built-in electric control unit. Since the rocking center and the linear motion helical spline center coincide, a compact cylinder head design was possible, and the cylinder head is a common design with a conventional engine. Since the ECU controls intake valve duration and timing, a fuel economy gain of maximum 10% (depending on driving condition) is obtained by reducing light to medium load pumping losses. Also intake efficiency was maximized throughout the speed range, resulting in a power gain of 10%. Further, HC emissions were reduced due to increased air speed at low valve lift. (orig.)

Shortened preoperative fasting time to allow oral rehydration solution clear liquid up to two hours before elective major surgery in adults

International Nuclear Information System (INIS)

Shah, J.N.; Maharjan, S.; Curung, R.

2018-01-01

To generate evidence of feasibility to allow clear liquid 2 hours before elective surgery. Study Design: Cross-sectional observational study. Place and Duration of Study: The Department of Surgery, Patan Hospital, Patan Academy of Health Sciences, Nepal, from October to December 2016. Methodology: One hundred consecutive adult elective major surgery patients of American Society of Anesthesiologist criteria 1 or 2 were enrolled. The protocol was discussed with patients, nurses, anesthetists and surgeons to allow 500 ml clear liquid (ORS) up to 0600 hours on the day of surgery to maintain minimum of 2 hours (h) nil per os (NPO) before surgery. Compliance, discomfort, nausea and vomiting were observed. Institutional review committee approved the study. Microsoft excel was used for descriptive analysis. Results: All 100 patients completed the protocol of shortened fasting time. Two patients had incomplete records and were excluded from analysis. Among the 98 patients analysed, age was 48 +-12.38 years with 74 females (75.51% of 98). There were 68 gastrointestinal, 20 urosurgery and 10 others surgeries. There was no discomfort, nausea or vomiting reported due to ORS 2-h before elective surgery. Conclusion: Preoperative clear liquid up to 2-h before elective surgery in adults is feasible and safe in our set-up to shorten the fasting time. (author)

Downscaling reanalysis data to high-resolution variables above a glacier surface (Cordillera Blanca, Peru)

Science.gov (United States)

Hofer, Marlis; Mölg, Thomas; Marzeion, Ben; Kaser, Georg

2010-05-01

Recently initiated observation networks in the Cordillera Blanca provide temporally high-resolution, yet short-term atmospheric data. The aim of this study is to extend the existing time series into the past. We present an empirical-statistical downscaling (ESD) model that links 6-hourly NCEP/NCAR reanalysis data to the local target variables, measured at the tropical glacier Artesonraju (Northern Cordillera Blanca). The approach is particular in the context of ESD for two reasons. First, the observational time series for model calibration are short (only about two years). Second, unlike most ESD studies in climate research, we focus on variables at a high temporal resolution (i.e., six-hourly values). Our target variables are two important drivers in the surface energy balance of tropical glaciers; air temperature and specific humidity. The selection of predictor fields from the reanalysis data is based on regression analyses and climatologic considerations. The ESD modelling procedure includes combined empirical orthogonal function and multiple regression analyses. Principal component screening is based on cross-validation using the Akaike Information Criterion as model selection criterion. Double cross-validation is applied for model evaluation. Potential autocorrelation in the time series is considered by defining the block length in the resampling procedure. Apart from the selection of predictor fields, the modelling procedure is automated and does not include subjective choices. We assess the ESD model sensitivity to the predictor choice by using both single- and mixed-field predictors of the variables air temperature (1000 hPa), specific humidity (1000 hPa), and zonal wind speed (500 hPa). The chosen downscaling domain ranges from 80 to 50 degrees west and from 0 to 20 degrees south. Statistical transfer functions are derived individually for different months and times of day (month/hour-models). The forecast skill of the month/hour-models largely depends on

The swan song in context: long-time-scale X-ray variability of NGC 4051

Science.gov (United States)

Uttley, P.; McHardy, I. M.; Papadakis, I. E.; Guainazzi, M.; Fruscione, A.

1999-07-01

On 1998 May 9-11, the highly variable, low-luminosity Seyfert 1 galaxy NGC 4051 was observed in an unusual low-flux state by BeppoSAX, RXTE and EUVE. We present fits of the 4-15keV RXTE spectrum and BeppoSAX MECS spectrum obtained during this observation, which are consistent with the interpretation that the source had switched off, leaving only the spectrum of pure reflection from distant cold matter. We place this result in context by showing the X-ray light curve of NGC 4051 obtained by our RXTE monitoring campaign over the past two and a half years, which shows that the low state lasted for ~150d before the May observations (implying that the reflecting material is >10^17cm from the continuum source) and forms part of a light curve showing distinct variations in long-term average flux over time-scales > months. We show that the long-time-scale component to X-ray variability is intrinsic to the primary continuum and is probably distinct from the variability at shorter time-scales. The long-time-scale component to variability maybe associated with variations in the accretion flow of matter on to the central black hole. As the source approaches the low state, the variability process becomes non-linear. NGC 4051 may represent a microcosm of all X-ray variability in radio-quiet active galactic nuclei (AGNs), displaying in a few years a variety of flux states and variability properties which more luminous AGNs may pass through on time-scales of decades to thousands of years.

The impact of transitioning from a 24-hour to a 16-hour call model amongst a cohort of Canadian anesthesia residents at McMaster University – a survey study

Directory of Open Access Journals (Sweden)

Sussman D

2015-08-01

Full Text Available David Sussman, James E Paul Department of Anesthesia, McMaster University, Hamilton, ON, Canada Purpose: The primary objective of this study was to assess anesthesia residents' opinions and perceptions on wellness/burnout, fatigue, education, and patient safety after the initiation of a reduced call model (16-hour call. Methods: A prospective cohort study was conducted at three time points during the 2013–2014 academic year. A web-based questionnaire consisting of 23 questions was electronically distributed to all anesthesia residents from postgraduate years (PGY 1 to 5 who were part of the active call roster (n=84 at McMaster University in Hamilton, Ontario. Descriptive summaries were calculated, counts and percentages were used for categorical variables, and answers to open text questions were reviewed for themes. Results: A response rate of 67% was obtained for this study. A majority of anesthesia residents (65% approved of 16-hour call, felt that their overall quality of life as a senior resident (PGY3 or greater or junior resident (PGY2 and below had improved (73% and 55%, respectively, and reported overall feeling less fatigued. Most respondents indicated that the quality of education remained unchanged (47%, or had improved (31%. And most felt better prepared for the royal college exam (52%. Most felt patient safety had improved or was unchanged (both 48%. Conclusion: The study demonstrates that 16-hour call improved resident wellness, reduced burnout and fostered an environment where residents are less fatigued and more satisfied with their educational experience promoting an environment of patient safety. Overall, the anesthesia residency group demonstrated that not only is 16-hour call preferred but beneficial. Keywords: resident wellness, reduced call model, duty hours, patient safety, cohort study, fatigue 

Ecosystem functioning is enveloped by hydrometeorological variability.

Science.gov (United States)

Pappas, Christoforos; Mahecha, Miguel D; Frank, David C; Babst, Flurin; Koutsoyiannis, Demetris

2017-09-01

Terrestrial ecosystem processes, and the associated vegetation carbon dynamics, respond differently to hydrometeorological variability across timescales, and so does our scientific understanding of the underlying mechanisms. Long-term variability of the terrestrial carbon cycle is not yet well constrained and the resulting climate-biosphere feedbacks are highly uncertain. Here we present a comprehensive overview of hydrometeorological and ecosystem variability from hourly to decadal timescales integrating multiple in situ and remote-sensing datasets characterizing extra-tropical forest sites. We find that ecosystem variability at all sites is confined within a hydrometeorological envelope across sites and timescales. Furthermore, ecosystem variability demonstrates long-term persistence, highlighting ecological memory and slow ecosystem recovery rates after disturbances. However, simulation results with state-of-the-art process-based models do not reflect this long-term persistent behaviour in ecosystem functioning. Accordingly, we develop a cross-time-scale stochastic framework that captures hydrometeorological and ecosystem variability. Our analysis offers a perspective for terrestrial ecosystem modelling and paves the way for new model-data integration opportunities in Earth system sciences.

Analysis of hourly crash likelihood using unbalanced panel data mixed logit model and real-time driving environmental big data.

Science.gov (United States)

Chen, Feng; Chen, Suren; Ma, Xiaoxiang

2018-06-01

Driving environment, including road surface conditions and traffic states, often changes over time and influences crash probability considerably. It becomes stretched for traditional crash frequency models developed in large temporal scales to capture the time-varying characteristics of these factors, which may cause substantial loss of critical driving environmental information on crash prediction. Crash prediction models with refined temporal data (hourly records) are developed to characterize the time-varying nature of these contributing factors. Unbalanced panel data mixed logit models are developed to analyze hourly crash likelihood of highway segments. The refined temporal driving environmental data, including road surface and traffic condition, obtained from the Road Weather Information System (RWIS), are incorporated into the models. Model estimation results indicate that the traffic speed, traffic volume, curvature and chemically wet road surface indicator are better modeled as random parameters. The estimation results of the mixed logit models based on unbalanced panel data show that there are a number of factors related to crash likelihood on I-25. Specifically, weekend indicator, November indicator, low speed limit and long remaining service life of rutting indicator are found to increase crash likelihood, while 5-am indicator and number of merging ramps per lane per mile are found to decrease crash likelihood. The study underscores and confirms the unique and significant impacts on crash imposed by the real-time weather, road surface, and traffic conditions. With the unbalanced panel data structure, the rich information from real-time driving environmental big data can be well incorporated. Copyright © 2018 National Safety Council and Elsevier Ltd. All rights reserved.

ELECTRIC MOTORS MAINTENANCE PLANNING FROM ITS OPERATING VARIABLES

Directory of Open Access Journals (Sweden)

Francisco RODRIGUES

2017-07-01

Full Text Available The maintenance planning corresponds to an approach that seeks to maximize the availability of equipment and, conse-quently, increase the levels of competitiveness of companies by increasing production times. This paper presents a maintenance planning based on operating variables (number of hours worked, duty cycles, number of revolutions to maximizing the availability of operation of electrical motors. The reading of the operating variables and its sampling is done based on predetermined sampling cycles and subsequently is made the data analysis through time series algo-rithms aiming to launch work orders before reaching the variables limit values. This approach is supported by tools and technologies such as logical applications that enable a graphical user interface for access to relevant information about their Physical Asset HMI (Human Machine Interface, including the control and supervision by acquisition through SCADA (Supervisory Control And data acquisition data, also including the communication protocols among different logical applications.

Nurse dose: linking staffing variables to adverse patient outcomes.

Science.gov (United States)

Manojlovich, Milisa; Sidani, Souraya; Covell, Christine L; Antonakos, Cathy L

2011-01-01

Inconsistent findings in more than 100 studies have made it difficult to explain how variation in nurse staffing affects patient outcomes. Nurse dose, defined as the level of nurses required to provide patient care in hospital settings, draws on variables used in staffing studies to describe the influence of many staffing variables on outcomes. The aim of this study was to examine the construct validity of nurse dose by determining its association with methicillin-resistant Staphylococcus aureus (MRSA) infections and reported patient falls on a sample of inpatient adult acute care units. Staffing data came from 26 units in Ontario, Canada, and Michigan. Financial and human resource data were data sources for staffing variables. Sources of data for MRSA came from infection control departments. Incident reports were the data source for patient falls. Data analysis consisted of bivariate correlations and Poisson regression. Bivariate correlations revealed that nurse dose attributes (active ingredient and intensity) were associated significantly with both outcomes. Active ingredient (education, experience, skill mix) and intensity (full-time employees, registered nurse [RN]:patient ratio, RN hours per patient day) were significant predictors of MRSA. Coefficients for both attributes were negative and almost identical. Both attributes were significant predictors of reported patient falls, and coefficients were again negative, but coefficient sizes differed. By conceptualizing nurse and staffing variables (education, experience, skill mix, full-time employees, RN:patient ratio, RN hours per patient day) as attributes of nurse dose and by including these in the same analysis, it is possible to determine their relative influence on MRSA infections and reported patient falls.

Preferences for travel time variability – A study of Danish car drivers

DEFF Research Database (Denmark)

Hjorth, Katrine; Rich, Jeppe

Travel time variability (TTV) is a measure of the extent of unpredictability in travel times. It is generally accepted that TTV has a negative effect on travellers’ wellbeing and overall utility of travelling, and valuation of variability is an important issue in transport demand modelling...... preferences, to exclude non-traders, and to avoid complicated issues related to scheduled public transport services. The survey uses customised Internet questionnaires, containing a series of questions related to the traveller’s most recent morning trip to work, e.g.: • Travel time experienced on this day......, • Number of stops along the way, their duration, and whether these stops involved restrictions on time of day, • Restrictions regarding departure time from home or arrival time at work, • How often such a trip was made within the last month and the range of experienced travel times, • What the traveller...

Prevalence of Pterygia in Hawaii: Examining Cumulative Surfing Hours as a Risk Factor.

Science.gov (United States)

Lin, Alexander D; Miles, Ku'ulei; Brinks, Mitchel V

2016-08-01

To examine the association between surfing and pterygium prevalence in Hawaii. A convenience sampling was performed at four beaches on the island of Oahu, Hawaii. A total of 169 individuals were interviewed and underwent penlight examination to assess grade and extent of pterygium. Of 169 participants aged 18-80 years, 88 non-surfers, 41 occasional surfers, 15 recreational surfers and 25 surfing enthusiasts were identified based on their lifetime surfing hours. Overall, 19 participants were found to have pterygia (28 pterygia total) including two non-surfers (2.3%), five occasional surfers (12.2%), three recreational surfers (20.0%), and nine enthusiast surfers (36.0%). Variables associated with pterygium prevalence were lifetime surfing hours (p surfing hours as the primary explanatory variable. After adjustment for confounders, a significant linear relationship was observed between chord length and lifetime surfing hours (p = 0.01). Surfing was associated with an increased pterygium prevalence and trend towards an association with increased pterygium severity. Increased risk of exposure to wind, particle irritation, and ultraviolet (UV) radiation while surfing may contribute to pterygium development. Implications for public health include promoting UV protective eyewear during surfing, in addition to raising awareness about the association of pterygia and the sport of surfing.

Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

International Nuclear Information System (INIS)

Veronesi, F; Grassi, S

2016-01-01

Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners. (paper)

Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

Science.gov (United States)

Veronesi, F.; Grassi, S.

2016-09-01

Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners.

Leisure time physical activity, screen time, social background, and environmental variables in adolescents.

Science.gov (United States)

Mota, Jorge; Gomes, Helena; Almeida, Mariana; Ribeiro, José Carlos; Santos, Maria Paula

2007-08-01

This study analyzes the relationships between leisure time physical activity (LTPA), sedentary behaviors, socioeconomic status, and perceived environmental variables. The sample comprised 815 girls and 746 boys. In girls, non-LTPA participants reported significantly more screen time. Girls with safety concerns were more likely to be in the non-LTPA group (OR = 0.60) and those who agreed with the importance of aesthetics were more likely to be in the active-LTPA group (OR = 1.59). In girls, an increase of 1 hr of TV watching was a significant predictor of non-LTPA (OR = 0.38). LTPA for girls, but not for boys, seems to be influenced by certain modifiable factors of the built environment, as well as by time watching TV.

Living hours under pressure:flexibility loopholes in the Danish IR-model

OpenAIRE

Ilsøe, Anna; Larsen, Trine Pernille; Felbo-Kolding, Jonas

2017-01-01

PurposeThe purpose of this paper is to investigate the effect of part-time work on absolute wages. The empirical focus is wages and working hours in three selected sectors within private services in the Danish labour market – industrial cleaning, retail, hotels and restaurants – and their agreement-based regulation of working time and wages. Theoretically, this analysis is inspired by the concept of living hours, which addresses the interaction between working hours and living wages, but adds...

Who breaches the four-hour emergency department wait time target? A retrospective analysis of 374,000 emergency department attendances between 2008 and 2013 at a type 1 emergency department in England.

Science.gov (United States)

Bobrovitz, Niklas; Lasserson, Daniel S; Briggs, Adam D M

2017-11-02

The four-hour target is a key hospital emergency department performance indicator in England and one that drives the physical and organisational design of the ED. Some studies have identified time of presentation as a key factor affecting waiting times. Few studies have investigated other determinants of breaching the four-hour target. Therefore, our objective was to describe patterns of emergency department breaches of the four-hour wait time target and identify patients at highest risk of breaching. This was a retrospective cohort study of a large type 1 Emergency department at an NHS teaching hospital in Oxford, England. We analysed anonymised individual level patient data for 378,873 emergency department attendances, representing all attendances between April 2008 and April 2013. We examined patient characteristics and emergency department presentation circumstances associated with the highest likelihood of breaching the four-hour wait time target. We used 374,459 complete cases for analysis. In total, 8.3% of all patients breached the four-hour wait time target. The main determinants of patients breaching the four-hour wait time target were hour of arrival to the ED, day of the week, patient age, ED referral source, and the types of investigations patients receive (p target were older, presented at night, presented on Monday, received multiple types of investigation in the emergency department, and were not self-referred (p target including patient age, ED referral source, the types of investigations patients receive, as well as the hour, day, and month of arrival to the ED. Efforts to reduce the number of breaches could explore late-evening/overnight staffing, access to diagnostic tests, rapid discharge facilities, and early assessment and input on diagnostic and management strategies from a senior practitioner.

Analysis of relationships between hourly electricity price and load in deregulated real-time power markets

International Nuclear Information System (INIS)

Lo, K.L.; Wu, Y.K.

2004-01-01

Risk management in the electric power industry involves measuring the risk for all instruments owned by a company. The value of many of these instruments depends directly on electricity prices. In theory, the wholesale price in a real-time market should reflect the short-run marginal cost. However, most markets are not perfectly competitive, therefore by understanding the degree of correlation between price and physical drivers, electric traders and consumers can manage their risk more effectively and efficiently. Market data from two power-pool architectures, both pre-2003 ISO-NE and Australia's NEM, have been studied. The dynamic character of electricity price is mean-reverting, and consists of intra-day and weekly variations, seasonal fluctuations, and instant jumps. Parts of them are affected by load demands. Hourly signals on both price and load are divided into deterministic and random components with a discrete Fourier transform algorithm. Next, the real-time price-load relationship for periodic and random signals is examined. In addition, time-varying volatility models are constructed on random price and random load with the GARCH model, and the correlation between them analysed. Volatility plays a critical role on evaluating option pricing and risk management. (author)

Time domain heart rate variability in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy

Directory of Open Access Journals (Sweden)

Evandro Zacché

Full Text Available ABSTRACT: The aim of the present study was to assess heart rate variability (HRV in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC. Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours or unaffected (<20 VPCs/24 hours by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Student’s t test, linear regression and Spearman’s test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01, SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002 and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002 were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.

Measuring excessive hours of work, low hourly pay, and informal employment through a labour force survey a pilot survey in the Philippines

OpenAIRE

Mehran, Farhad

2005-01-01

Using 2004 data of the Philippines' labour force survey, evaluates the hours of work at all jobs, hourly pay among time-rated wage and salary workers, informal employment etc., with the aim to quantify a decent-work situation (i.e. acceptable productive employment, social protection, social dialogue, and rights at work).

No Correlation Between Work-Hours and Operative Volumes

DEFF Research Database (Denmark)

Kjærgaard, Jane; Sillesen, Martin; Beier-Holgersen, Randi

2016-01-01

OBJECTIVE: Since 2003, United States residents have been limited to an 80-hour workweek. This has prompted concerns of reduced educational quality, especially inadequate operating exposure. In contrast, the Danish surgical specialty-training program mandates a cap on working hours of 37 per week....... We hypothesize that there is no direct correlation between work-hours and operative volume achieved during surgical residency. To test the hypothesis, we compare Danish and US operative volumes achieved during surgical residency training. DESIGN: Retrospective comparative study. PARTICIPANTS...... find no difference in overall surgical volumes between Danes and US residents during their surgical training. When time in training was accounted for, differences between weekly surgical volumes achieved were minor, indicating a lack of direct correlation between weekly work-hours and operative volumes...

Inverse Ising problem in continuous time: A latent variable approach

Science.gov (United States)

Donner, Christian; Opper, Manfred

2017-12-01

We consider the inverse Ising problem: the inference of network couplings from observed spin trajectories for a model with continuous time Glauber dynamics. By introducing two sets of auxiliary latent random variables we render the likelihood into a form which allows for simple iterative inference algorithms with analytical updates. The variables are (1) Poisson variables to linearize an exponential term which is typical for point process likelihoods and (2) Pólya-Gamma variables, which make the likelihood quadratic in the coupling parameters. Using the augmented likelihood, we derive an expectation-maximization (EM) algorithm to obtain the maximum likelihood estimate of network parameters. Using a third set of latent variables we extend the EM algorithm to sparse couplings via L1 regularization. Finally, we develop an efficient approximate Bayesian inference algorithm using a variational approach. We demonstrate the performance of our algorithms on data simulated from an Ising model. For data which are simulated from a more biologically plausible network with spiking neurons, we show that the Ising model captures well the low order statistics of the data and how the Ising couplings are related to the underlying synaptic structure of the simulated network.

Optimizing wellfield operation in a variable power price regime

DEFF Research Database (Denmark)

Bauer-Gottwein, Peter; Schneider, Raphael; Davidsen, Claus

Wellfield management is a multi-objective optimization problem. One important management objective has been energy efficiency in terms of minimizing the energy footprint (EFP) of delivered water (MWh/m3). However, power systems in most countries are moving in the direction of deregulated power...... use itself. We estimated energy footprint as a function of wellfield pumping rate (EFP-Q relationship) for a wellfield in Denmark using a coupled well and pipe network model. This EFP-Q relationship was subsequently used in a stochastic dynamic programming framework to minimize total cost of operating...... the combined wellfield-storage-demand system over the course of a 2-year planning period based on a time series of observed price on the Danish power market and a deterministic, time-varying hourly water demand. In the SDP setup, hourly pumping rates are the decision variables. Constraints include storage...

Optimizing Wellfield Operation in a Variable Power Price Regime

DEFF Research Database (Denmark)

Bauer-Gottwein, Peter; Schneider, Raphael; Davidsen, Claus

2016-01-01

Wellfield management is a multiobjective optimization problem. One important objective has been energy efficiency in terms of minimizing the energy footprint (EFP) of delivered water (MWh/m3). However, power systems in most countries are moving in the direction of deregulated markets and price...... itself. We estimated EFP of pumped water as a function of wellfield pumping rate (EFP-Q relationship) for a wellfield in Denmark using a coupled well and pipe network model. This EFP-Q relationship was subsequently used in a Stochastic Dynamic Programming (SDP) framework to minimize total cost...... of operating the combined wellfield-storage-demand system over the course of a 2-year planning period based on a time series of observed price on the Danish power market and a deterministic, time-varying hourly water demand. In the SDP setup, hourly pumping rates are the decision variables. Constraints include...

Application of several variable-valve-timing concepts to an LHR engine

Science.gov (United States)

Morel, T.; Keribar, R.; Sawlivala, M.; Hakim, N.

1987-01-01

The paper discusses advantages provided by electronically controlled hydraulically activated valves (ECVs) when applied to low heat rejection (LHR) engines. The ECV concept provides additional engine control flexibility by allowing for a variable valve timing as a function of speed and load, or for a given transient condition. The results of a study carried out to assess the benefits that this flexibility can offer to an LHR engine indicated that, when judged on the benefits to BSFC, volumetric efficiency, and peak firing pressure, ECVs would provide only modest benefits in comparison to conventional valve profiles. It is noted, however, that once installed on the engine, the ECVs would permit a whole range of certain more sophisticated variable valve timing strategies not otherwise possible, such as high compression cranking, engine braking, cylinder cutouts, and volumetric efficiency timing with engine speed.

Long work hours and the wellbeing of fathers and their families

OpenAIRE

Ruth Weston; Matthew Gray; Lixia Qu; David Stanton

2004-01-01

The average hours worked by full-time employees in Australia have increased since the late 1970s. This, combined with increases in female labour force participation, has led to concerns about the impact of long work hours on family life. This paper explores the relationship between fathers' work hours, their own wellbeing and that of their families using data from the Household, Income and Labour Dynamics in Australia survey. The analysis is restricted to full-time employed fathers with a par...

Deep venous thrombophlebitis: detection with 4-hour versus 24-hour platelet scintigraphy

International Nuclear Information System (INIS)

Seabold, J.E.; Conrad, G.R.; Ponto, J.A.; Kimball, D.A.; Frey, E.E.; Ahmed, F.; Coughlan, J.D.; Jensen, K.C.

1987-01-01

Thirty-one nonheparinized patients with suspected deep venous thrombophlebitis (DVT) underwent contrast venography and indium-111 platelet scintigraphy (In-111 PS). Venography permitted identification of acute DVT in 12 of 31 cases (39%). One additional patient was considered to have acute DVT despite nonconclusive venography results. In-111 PS results were positive at 4 hours in nine of 13 cases (69%) and at 24 hours in 12 of 13 cases (92%). Two of four patients with false-negative 4-hour In-111 PS studies had received warfarin. Thus, the sensitivity of 4-hour In-111 PS in patients not receiving anticoagulants was 82%. Venography results were negative for acute DVT in 18 cases, and 4-hour In-111 PS studies were negative or equivocal in each. In-111 PS is an alternative to contrast venography for detecting acute DVT. If 4-hour In-111 PS results are positive, anticoagulation can be initiated. Delayed images are necessary if the 4-hour images are negative or equivocal

Modeling Hourly Resident Productivity in the Emergency Department.

Science.gov (United States)

Joseph, Joshua W; Henning, Daniel J; Strouse, Connie S; Chiu, David T; Nathanson, Larry A; Sanchez, Leon D

2017-08-01

Resident productivity, defined as new patients per hour, carries important implications for emergency department operations. In high-volume academic centers, essential staffing decisions can be made on the assumption that residents see patients at a static rate. However, it is unclear whether this model mirrors reality; previous studies have not rigorously examined whether productivity changes over time. We examine residents' productivity across shifts to determine whether it remained consistent. This was a retrospective cohort study conducted in an urban academic hospital with a 3-year emergency medicine training program in which residents acquire patients ad libitum throughout their shift. Time stamps of all patient encounters were automatically logged. A linear mixed model was constructed to predict productivity per shift hour. A total of 14,364 8- and 9-hour shifts were worked by 75 residents between July 1, 2010, and June 20, 2015. This comprised 6,127 (42.7%) postgraduate year (PGY) 1 shifts, 7,236 (50.4%) PGY-2 shifts, and 998 (6.9%) PGY-3 nonsupervisory shifts (Table 1). Overall, residents treated a mean of 10.1 patients per shift (SD 3.2), with most patients at Emergency Severity Index level 3 or more acute (93.8%). In the initial hour, residents treated a mean of 2.14 patients (SD 1.2), and every subsequent hour was associated with a significant decrease, with the largest in the second, third, and final hours. Emergency medicine resident productivity during a single shift follows a reliable pattern that decreases significantly hourly, a pattern preserved across PGY years and types of shifts. This suggests that resident productivity is a dynamic process, which should be considered in staffing decisions and studied further. Copyright © 2016 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

The added value of time-variable microgravimetry to the understanding of how volcanoes work

Science.gov (United States)

Carbone, Daniele; Poland, Michael; Greco, Filippo; Diament, Michel

2017-01-01

During the past few decades, time-variable volcano gravimetry has shown great potential for imaging subsurface processes at active volcanoes (including some processes that might otherwise remain “hidden”), especially when combined with other methods (e.g., ground deformation, seismicity, and gas emissions). By supplying information on changes in the distribution of bulk mass over time, gravimetry can provide information regarding processes such as magma accumulation in void space, gas segregation at shallow depths, and mechanisms driving volcanic uplift and subsidence. Despite its potential, time-variable volcano gravimetry is an underexploited method, not widely adopted by volcano researchers or observatories. The cost of instrumentation and the difficulty in using it under harsh environmental conditions is a significant impediment to the exploitation of gravimetry at many volcanoes. In addition, retrieving useful information from gravity changes in noisy volcanic environments is a major challenge. While these difficulties are not trivial, neither are they insurmountable; indeed, creative efforts in a variety of volcanic settings highlight the value of time-variable gravimetry for understanding hazards as well as revealing fundamental insights into how volcanoes work. Building on previous work, we provide a comprehensive review of time-variable volcano gravimetry, including discussions of instrumentation, modeling and analysis techniques, and case studies that emphasize what can be learned from campaign, continuous, and hybrid gravity observations. We are hopeful that this exploration of time-variable volcano gravimetry will excite more scientists about the potential of the method, spurring further application, development, and innovation.

Modified Pressure-Correction Projection Methods: Open Boundary and Variable Time Stepping

KAUST Repository

Bonito, Andrea

2014-10-31

© Springer International Publishing Switzerland 2015. In this paper, we design and study two modifications of the first order standard pressure increment projection scheme for the Stokes system. The first scheme improves the existing schemes in the case of open boundary condition by modifying the pressure increment boundary condition, thereby minimizing the pressure boundary layer and recovering the optimal first order decay. The second scheme allows for variable time stepping. It turns out that the straightforward modification to variable time stepping leads to unstable schemes. The proposed scheme is not only stable but also exhibits the optimal first order decay. Numerical computations illustrating the theoretical estimates are provided for both new schemes.

Modified Pressure-Correction Projection Methods: Open Boundary and Variable Time Stepping

KAUST Repository

Bonito, Andrea; Guermond, Jean-Luc; Lee, Sanghyun

2014-01-01

© Springer International Publishing Switzerland 2015. In this paper, we design and study two modifications of the first order standard pressure increment projection scheme for the Stokes system. The first scheme improves the existing schemes in the case of open boundary condition by modifying the pressure increment boundary condition, thereby minimizing the pressure boundary layer and recovering the optimal first order decay. The second scheme allows for variable time stepping. It turns out that the straightforward modification to variable time stepping leads to unstable schemes. The proposed scheme is not only stable but also exhibits the optimal first order decay. Numerical computations illustrating the theoretical estimates are provided for both new schemes.

Intraindividual variability in reaction time predicts cognitive outcomes 5 years later.

Science.gov (United States)

Bielak, Allison A M; Hultsch, David F; Strauss, Esther; Macdonald, Stuart W S; Hunter, Michael A

2010-11-01

Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitive status (i.e., cognitive impairment, no dementia [CIND] classification) and attrition 5 years later. Two hundred twelve community-dwelling older adults, initially aged 64-92 years, remained in the study after 5 years. Inconsistency was calculated from baseline reaction time performance. Participants were assigned to groups on the basis of their fluctuations in CIND classification over time. Logistic and Cox regressions were used. Baseline inconsistency significantly distinguished among those who remained or transitioned into CIND over the 5 years and those who were consistently intact (e.g., stable intact vs. stable CIND, Wald (1) = 7.91, p < .01, Exp(β) = 1.49). Average level of inconsistency over time was also predictive of study attrition, for example, Wald (1) = 11.31, p < .01, Exp(β) = 1.24. For both outcomes, greater inconsistency was associated with a greater likelihood of being in a maladaptive group 5 years later. Variability based on moderately cognitively challenging tasks appeared to be particularly sensitive to longitudinal changes in cognitive ability. Mean rate of responding was a comparable predictor of change in most instances, but individuals were at greater relative risk of being in a maladaptive outcome group if they were more inconsistent rather than if they were slower in responding. Implications for the potential utility of intraindividual variability in reaction time as an early marker of cognitive decline are discussed. (c) 2010 APA, all rights reserved

Predictability and environmental drivers of chlorophyll fluctuations vary across different time scales and regions of the North Sea

Science.gov (United States)

Blauw, Anouk N.; Benincà, Elisa; Laane, Remi W. P. M.; Greenwood, Naomi; Huisman, Jef

2018-02-01

Phytoplankton concentrations display strong temporal variability at different time scales. Recent advances in automated moorings enable detailed investigation of this variability. In this study, we analyzed phytoplankton fluctuations at four automated mooring stations in the North Sea, which measured phytoplankton abundance (chlorophyll) and several environmental variables at a temporal resolution of 12-30 min for two to nine years. The stations differed in tidal range, water depth and freshwater influence. This allowed comparison of the predictability and environmental drivers of phytoplankton variability across different time scales and geographical regions. We analyzed the time series using wavelet analysis, cross correlations and generalized additive models to quantify the response of chlorophyll fluorescence to various environmental variables (tidal and meteorological variables, salinity, suspended particulate matter, nitrate and sea surface temperature). Hour-to-hour and day-to-day fluctuations in chlorophyll fluorescence were substantial, and mainly driven by sinking and vertical mixing of phytoplankton cells, horizontal transport of different water masses, and non-photochemical quenching of the fluorescence signal. At the macro-tidal stations, these short-term phytoplankton fluctuations were strongly driven by the tides. Along the Dutch coast, variation in salinity associated with the freshwater influence of the river Rhine played an important role, while in the central North Sea variation in weather conditions was a major determinant of phytoplankton variability. At time scales of weeks to months, solar irradiance, nutrient conditions and thermal stratification were the dominant drivers of changes in chlorophyll concentrations. These results show that the dominant drivers of phytoplankton fluctuations differ across marine environments and time scales. Moreover, our findings show that phytoplankton variability on hourly to daily time scales should not be

Rapid variability of extragalactic radio sources

Energy Technology Data Exchange (ETDEWEB)

Quirrenbach, A.; Witzel, A.; Krichbaum, T.; Hummel, C.A.; Alberdi, A.; Schalinski, C.

1989-02-02

Since its discovery more than 20 years ago, variability of extragalactic radio sources on timescales of weeks to years has been the subject of many investigations. We have examined the variability of these sources on timescales of hours at wavelengths of 6 and 11 cm using the 100-m telescope of the Max-Planck-Institut fuer Radioastronomie and report the results for two sources. The quasar QSO0917 + 62 showed variations with amplitudes of up to 23% in /similar to/ 24 hours, which were correlated at the two wavelengths; in the BL Lac object 0716 + 71 we found variations with amplitudes of 7-11%. We discuss intrinsic effects, gravitational lensing and scattering in the interstellar medium as possible explanations for rapid radio variability.

Rapid variability of extragalactic radio sources

International Nuclear Information System (INIS)

Quirrenbach, A.; Witzel, A.; Krichbaum, T.; Hummel, C.A.; Alberdi, A.; Schalinski, C.

1989-01-01

Since its discovery more than 20 years ago, variability of extragalactic radio sources on timescales of weeks to years has been the subject of many investigations. We have examined the variability of these sources on timescales of hours at wavelengths of 6 and 11 cm using the 100-m telescope of the Max-Planck-Institut fuer Radioastronomie and report the results for two sources. The quasar QSO0917 + 62 showed variations with amplitudes of up to 23% in ∼ 24 hours, which were correlated at the two wavelengths; in the BL Lac object 0716 + 71 we found variations with amplitudes of 7-11%. We discuss intrinsic effects, gravitational lensing and scattering in the interstellar medium as possible explanations for rapid radio variability. (author)

TEC variability over Havana

International Nuclear Information System (INIS)

Lazo, B.; Alazo, K.; Rodriguez, M.; Calzadilla, A.

2003-01-01

The variability of total electron content (TEC) measured over Havana using ATS-6, SMS-1 and GOES-3 geosynchronous satellite signals has been investigated for low, middle and high solar activity periods from 1974 to 1982. The obtained results show that standard deviation is smooth during nighttime hours and maximum at noon or postnoon hours. Strong solar activity dependence of standard deviation with a maximum values during HSA has been found. (author)

Seasonality in trauma admissions - Are daylight and weather variables better predictors than general cyclic effects?

Science.gov (United States)

Røislien, Jo; Søvik, Signe; Eken, Torsten

2018-01-01

Trauma is a leading global cause of death, and predicting the burden of trauma admissions is vital for good planning of trauma care. Seasonality in trauma admissions has been found in several studies. Seasonal fluctuations in daylight hours, temperature and weather affect social and cultural practices but also individual neuroendocrine rhythms that may ultimately modify behaviour and potentially predispose to trauma. The aim of the present study was to explore to what extent the observed seasonality in daily trauma admissions could be explained by changes in daylight and weather variables throughout the year. Retrospective registry study on trauma admissions in the 10-year period 2001-2010 at Oslo University Hospital, Ullevål, Norway, where the amount of daylight varies from less than 6 hours to almost 19 hours per day throughout the year. Daily number of admissions was analysed by fitting non-linear Poisson time series regression models, simultaneously adjusting for several layers of temporal patterns, including a non-linear long-term trend and both seasonal and weekly cyclic effects. Five daylight and weather variables were explored, including hours of daylight and amount of precipitation. Models were compared using Akaike's Information Criterion (AIC). A regression model including daylight and weather variables significantly outperformed a traditional seasonality model in terms of AIC. A cyclic week effect was significant in all models. Daylight and weather variables are better predictors of seasonality in daily trauma admissions than mere information on day-of-year.

Comparison of 24-hour cardiovascular and autonomic function in paraplegia, tetraplegia, and control groups: implications for cardiovascular risk.

Science.gov (United States)

Rosado-Rivera, Dwindally; Radulovic, M; Handrakis, John P; Cirnigliaro, Christopher M; Jensen, A Marley; Kirshblum, Steve; Bauman, William A; Wecht, Jill Maria

2011-01-01

Fluctuations in 24-hour cardiovascular hemodynamics, specifically heart rate (HR) and blood pressure (BP), are thought to reflect autonomic nervous system (ANS) activity. Persons with spinal cord injury (SCI) represent a model of ANS dysfunction, which may affect 24-hour hemodynamics and predispose these individuals to increased cardiovascular disease risk. To determine 24-hour cardiovascular and ANS function among individuals with tetraplegia (n=20; TETRA: C4-C8), high paraplegia (n=10; HP: T2-T5), low paraplegia (n=9; LP: T7-T12), and non-SCI controls (n=10). Twenty-four-hour ANS function was assessed by time domain parameters of heart rate variability (HRV); the standard deviation of the 5-minute average R-R intervals (SDANN; milliseconds/ms), and the root-mean square of the standard deviation of the R-R intervals (rMSSD; ms). Subjects wore 24-hour ambulatory monitors to record HR, HRV, and BP. Mixed analysis of variance (ANOVA) revealed significantly lower 24-hour BP in the tetraplegic group; however, BP did not differ between the HP, LP, and control groups. Mixed ANOVA suggested significantly elevated 24-hour HR in the HP and LP groups compared to the TETRA and control groups (Pcontrol groups (Pcontrol groups (P<0.01). Twenty-four-hour SDANN was significantly increased in the HP group compared to the LP and TETRA groups (P<0.05) and rMSSD was significantly lower in the LP compared to the other three groups (P<0.05). Elevated 24-hour HR in persons with paraplegia, in concert with altered HRV dynamics, may impart significant adverse cardiovascular consequences, which are currently unappreciated.

Reaction Time Variability in Children With ADHD Symptoms and/or Dyslexia

OpenAIRE

Gooch, Debbie; Snowling, Margaret J.; Hulme, Charles

2012-01-01

Reaction time (RT) variability on a Stop Signal task was examined among children with attention deficit hyperactivity disorder (ADHD) symptoms and/or dyslexia in comparison to typically developing (TD) controls. Children’s go-trial RTs were analyzed using a novel ex-Gaussian method. Children with ADHD symptoms had increased variability in the fast but not the slow portions of their RT distributions compared to those without ADHD symptoms. The RT distributions of children with d...

Does 6 Hours of Contact With Alginate Impression Material Affect Dental Cast Properties?

Science.gov (United States)

Ibrahim, Amna Adam; Alhajj, Mohammed Nasser; Khalifa, Nadia; Gilada, Magdi Wadie

2017-06-01

Alginate impression (irreversible hydrocolloid) material is commonly used in dental practice because it is easy to mix, low in cost, and well tolerated by patients. The material is not dimensionally stable, however; thus, it is necessary to pour the impression immediately after the molding is accomplished, or within 60 minutes if the impression is kept in 100% humidity. Excessive contact of the alginate impression with the cast model over time may affect the model's properties. In this study, the authors tested the effect of contact time between an alginate impression and type III dental stone on cast model properties. Sixty-seven cast models were obtained from a stainless steel cylinder by using irreversible hydrocolloid impression material and type III dental stone. Thirty-seven cast models were separated from the impression after 1 hour (control group) and 30 cast models were separated after 6 hours (study group). The samples were evaluated under light microscope for surface details and measured by digital caliper for dimensional stability. An indentation on the cast was made and the depth of the indentation was then measured with a digital caliper to measure hardness. The dimensional stability of the cast models was not affected when contact time was increased from 1 hour to 6 hours (P = .507). Surface details did not deteriorate when contact time was increased, as all of the samples could reproduce all details after the 1-hour and 6-hour interval periods. However, hardness was greater after 1 hour of contact time (P = .001) than after 6 hours of contact time. In conclusion, contact between alginate impression material and type III dental stone up to 6 hours did not affect the dimensional stability and richness of the surface; hardness, though, was significantly affected.

BAYESIAN TECHNIQUES FOR COMPARING TIME-DEPENDENT GRMHD SIMULATIONS TO VARIABLE EVENT HORIZON TELESCOPE OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan; Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios, E-mail: junhankim@email.arizona.edu [Department of Astronomy and Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)

2016-12-01

The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore the robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.

GPS Imaging of Time-Variable Earthquake Hazard: The Hilton Creek Fault, Long Valley California

Science.gov (United States)

Hammond, W. C.; Blewitt, G.

2016-12-01

The Hilton Creek Fault, in Long Valley, California is a down-to-the-east normal fault that bounds the eastern edge of the Sierra Nevada/Great Valley microplate, and lies half inside and half outside the magmatically active caldera. Despite the dense coverage with GPS networks, the rapid and time-variable surface deformation attributable to sporadic magmatic inflation beneath the resurgent dome makes it difficult to use traditional geodetic methods to estimate the slip rate of the fault. While geologic studies identify cumulative offset, constrain timing of past earthquakes, and constrain a Quaternary slip rate to within 1-5 mm/yr, it is not currently possible to use geologic data to evaluate how the potential for slip correlates with transient caldera inflation. To estimate time-variable seismic hazard of the fault we estimate its instantaneous slip rate from GPS data using a new set of algorithms for robust estimation of velocity and strain rate fields and fault slip rates. From the GPS time series, we use the robust MIDAS algorithm to obtain time series of velocity that are highly insensitive to the effects of seasonality, outliers and steps in the data. We then use robust imaging of the velocity field to estimate a gridded time variable velocity field. Then we estimate fault slip rate at each time using a new technique that forms ad-hoc block representations that honor fault geometries, network complexity, connectivity, but does not require labor-intensive drawing of block boundaries. The results are compared to other slip rate estimates that have implications for hazard over different time scales. Time invariant long term seismic hazard is proportional to the long term slip rate accessible from geologic data. Contemporary time-invariant hazard, however, may differ from the long term rate, and is estimated from the geodetic velocity field that has been corrected for the effects of magmatic inflation in the caldera using a published model of a dipping ellipsoidal

Comparison of 44-hour and fixed 24-hour ambulatory blood pressure monitoring in dialysis patients.

Science.gov (United States)

Liu, Wenjin; Ye, Hong; Tang, Bing; Sun, Zhiping; Wen, Ping; Wu, Wenhui; Bian, Xueqing; Shen, Xia; Yang, Junwei

2014-01-01

The two most commonly used strategies to evaluate dialysis patients' blood pressure (BP) level are 44-hour and 24-hour ambulatory blood pressure monitoring (ABPM). The objective of this study was to find an appropriate 24-hour period that correlated well with the 44-hour BP level and determine the differences between these strategies. In a group of 51 dialysis patients, the authors performed 44-hour ABPM and extracted data for a fixed 24-hour ABPM. The fixed 24-hour ABPM started at 6 am on the nondialysis day. A strong correlation was found between all parameters of 44-hour and the fixed 24-hour ABPM, with paired sample t test showing only small magnitude changes in a few parameters. Both 24-hour ABPM and 44-hour ABPM were superior to clinic BP in predicting left ventricular mass index (LVMI) by multiple regression analysis. It was found that 44-hour ambulatory arterial stiffness index (AASI), but not 24-hour AASI, had a positive association with LVMI (r=0.328, P=.021). However, after adjustment for 44-hour systolic blood pressure, this association disappeared. Fixed 24-hour ABPM is a good surrogate of 44-hour ABPM to some extent, while 44-hour ABPM can provide more accurate and detailed information. ©2013 Wiley Periodicals, Inc.

Working hours, work-life conflict and health in precarious and "permanent" employment.

Science.gov (United States)

Bohle, Philip; Quinlan, Michael; Kennedy, David; Williamson, Ann

2004-12-01

The expansion of precarious employment in OECD countries has been widely associated with negative health and safety effects. Although many shiftworkers are precariously employed, shiftwork research has concentrated on full-time workers in continuing employment. This paper examines the impact of precarious employment on working hours, work-life conflict and health by comparing casual employees to full-time, "permanent" employees working in the same occupations and workplaces. Thirty-nine convergent interviews were conducted in two five-star hotels. The participants included 26 full-time and 13 casual (temporary) employees. They ranged in age from 19 to 61 years and included 17 females and 22 males. Working hours ranged from zero to 73 hours per week. Marked differences emerged between the reports of casual and full-time employees about working hours, work-life conflict and health. Casuals were more likely to work highly irregular hours over which they had little control. Their daily and weekly working hours ranged from very long to very short according to organisational requirements. Long working hours, combined with low predictability and control, produced greater disruption to family and social lives and poorer work-life balance for casuals. Uncoordinated hours across multiple jobs exacerbated these problems in some cases. Health-related issues reported to arise from work-life conflict included sleep disturbance, fatigue and disrupted exercise and dietary regimes. This study identified significant disadvantages of casual employment. In the same hotels, and doing largely the same jobs, casual employees had less desirable and predictable work schedules, greater work-life conflict and more associated health complaints than "permanent" workers.

Intraday X-Ray Variability of QSOs/AGN Using the Chandra Archives

Science.gov (United States)

Tartamella, C.; Busche, J.

2005-05-01

X-ray variability is a common characteristic of Active Galactic Nuclei (AGN), and it can be used to probe the nuclear region at short time scales. Quantitative analysis of this variability has been difficult due to low signal-to-noise ratios and short time baselines, but serendipitous Chandra data acquired within the last six years have opened the door to such analysis. Cross-correlation of the Chandra archives with QSO/AGN catalogs on NASA's HEASARC website (e.g. Veron, Sloan) yields a sample of 50+ objects that satisfy the following criteria: absolute magnitude M≤ -22.5, proper time baselines greater than 2 hours, and count rates leading to 10% error bars for 8+ flux points on the light curve. The sample includes a range of red-shifts, magnitudes, and type (e.g. radio loud, radio quiet), and hence may yield empirical clues about luminosity or evolutionary trends. As a beginning of such analysis, we present 11 light curves for 9 objects for which the exposure time was greater than 10 hours. The variability was analyzed using three different statistical methods. The Kolmogorov-Smirnov (KS) test proved to be impractical because of the unavoidably small number of data points and the simplistic nature of the test. A χ2 test indicated in most cases that there were significant departures from constant brightness (as expected). Autocorrelation plots were also generated for each light curve. With more work and a larger sample size, these plots can be used to identify any trends in the lightcurve such as whether the variability is stochastic or periodic in nature. This test was useful even with the small number of datapoints available. In future work, more sophisticated analyses based on Fourier series, power density spectra, or wavelets are likely to yield more meaningful and useful results.

Did liberalising bar hours decrease traffic accidents?

Science.gov (United States)

Green, Colin P; Heywood, John S; Navarro, Maria

2014-05-01

Legal bar closing times in England and Wales have historically been early and uniform. Recent legislation liberalised closing times with the object of reducing social problems thought associated with drinking to "beat the clock." Indeed, using both difference in difference and synthetic control approaches we show that one consequence of this liberalisation was a decrease in traffic accidents. This decrease is heavily concentrated among younger drivers. Moreover, we provide evidence that the effect was most pronounced in the hours of the week directly affected by the liberalisation: late nights and early mornings on weekends. This evidence survives a series of robustness checks and suggests at least one socially positive consequence of extending bar hours. Copyright © 2014 Elsevier B.V. All rights reserved.

Long working hours and pregnancy complications: women physicians survey in Japan.

Science.gov (United States)

Takeuchi, Masumi; Rahman, Mahbubur; Ishiguro, Aya; Nomura, Kyoko

2014-07-23

Previous studies have investigated the impact of occupational risk factors on health outcomes among physicians. However, few studies have investigated the effects on pregnancy outcomes among physicians. In this study, we examined the association between working hours during pregnancy and pregnancy complications among physicians. A cross-sectional study was based on a survey conducted in 2009-2011 of 1,684 alumnae (mean age, 44 ± 8 years) who had graduated from 13 private medical schools in Japan. Data on threatened abortion (TA), preterm birth (PTB), and the number of working hours during the first trimester of pregnancy were obtained via retrospective assessments. Of the 939 physicians with a first pregnancy, 15% experienced TA and 12% experienced PTB. Women who experienced TA (mean weekly working hours: 62 h vs. 50 h, P working hours during the first trimester than did those without pregnancy complications. Compared with women who worked 40 hours or less per week, women who worked 71 hours or more per week had a three-fold higher risk of experiencing TA (95% confidence interval (CI): 1.7-6.0) even after adjusting for medical specialty, maternal age, and current household income. The risk of experiencing PTB was 2.5 times higher (95% CI:1.2-5.2) in women who worked 51-70 hours and 4.2 times higher (95% CI: 1.9-9.2) in women who worked 71 hours or more even after adjusting for specialty, maternal age, and current household income. The trend in the P statistic reflecting the effect of the quartile of hours worked per week (40 hours, 41-50 hours, 51-70 hours, ≥ 71 hours) on TA or PTB was 0.0001 in the multivariate logistic regression models. These results suggest that working long hours during the first trimester of pregnancy is associated with TA and PTB.

The Associations Between Long Working Hours, Physical Inactivity, and Burnout.

Science.gov (United States)

Hu, Nien-Chih; Chen, Jong-Dar; Cheng, Tsun-Jen

2016-05-01

To examine the correlations between long working hours, physical activity, and burnout. A cross-sectional survey was administered to 1560 full-time employees, who underwent periodic health examinations in the year 2013. The subjects were divided into upper, middle, and lower tertiles according to the Copenhagen Burnout Inventory (CBI) score. The comparison of the high- and low-burnout groups revealed that long working hours were significantly correlated with burnout in a dose-dependent manner. Long working hours were more significantly associated with burnout among individuals younger than 50 years, females, and physically inactive employees. Long working hours are correlated with burnout when working over 40 hours per week and is even stronger when working over 60 hours per week. Limiting working hours to 40 weekly may be beneficial for the prevention of burnout. Physical activity helps reduce the risk of burnout.

When policy meets physiology: the challenge of reducing resident work hours.

Science.gov (United States)

Lockley, Steven W; Landrigan, Christopher P; Barger, Laura K; Czeisler, Charles A

2006-08-01

Considerable controversy exists regarding optimal work hours for physicians and surgeons in training. In a series of studies, we assessed the effect of extended work hours on resident sleep and health as well as patient safety. In a validated nationwide survey, we found that residents who had worked 24 hours or longer were 2.3 times more likely to have a motor vehicle crash following that shift than when they worked hours, and that the monthly risk of a crash increased by 16.2% after each extended duration shift. We also found in a randomized trial that interns working a traditional on-call schedule slept 5.8 hours less per week, had twice as many attentional failures on duty overnight, and made 36% more serious medical errors and nearly six times more serious diagnostic errors than when working on a schedule that limited continuous duty to 16 hours. While numerous opinions have been published opposing reductions in extended work hours due to concerns regarding continuity of patient care, reduced educational opportunities, and traditionally-defined professionalism, there are remarkably few objective data in support of continuing to schedule medical trainees to work shifts > 24 hours. An evidence-based approach is needed to minimize the well-documented risk that current work hour practices confer on resident health and patient safety while optimizing education and continuity of care.

Is it acceptable to use coagulation plasma samples stored at room temperature and 4°C for 24 hours for additional prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and D-dimer testing?

Science.gov (United States)

Rimac, V; Coen Herak, D

2017-10-01

Coagulation laboratories are faced on daily basis with requests for additional testing in already analyzed fresh plasma samples. This prompted us to examine whether plasma samples stored at room temperature (RT), and 4°C for 24 hours can be accepted for additional prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (Fbg), antithrombin (AT), and D-dimer testing. We measured PT, aPTT, Fbg in 50 and AT in 30 plasma samples with normal and pathological values, within 4 hours of blood collection (baseline results) and after 24-hours storage at RT (primary tubes), and 4°C (aliquots). D-dimer stability was investigated in 20 samples stored in primary tubes at 4°C. No statistically significant difference between baseline results and results in samples stored at RT and 4°C was observed for PT (P=.938), aPTT (P=.186), Fbg (P=.962), AT (P=.713), and D-dimers (P=.169). The highest median percentage changes were found for aPTT, being more pronounced for samples stored at 4°C (13.0%) than at RT (8.7%). Plasma samples stored both at RT and 4°C for 24 hours are acceptable for additional PT, Fbg, and AT testing. Plasma samples stored 24 hours in primary tubes at 4°C are suitable for D-dimer testing. © 2017 John Wiley & Sons Ltd.

Association between general practice characteristics and use of out-of-hours GP cooperatives.

Science.gov (United States)

Smits, Marleen; Peters, Yvonne; Broers, Sanne; Keizer, Ellen; Wensing, Michel; Giesen, Paul

2015-05-01

The use of out-of-hours healthcare services for non-urgent health problems is believed to be related to the organisation of daytime primary care but insight into underlying mechanisms is limited. Our objective was to examine the association between daytime general practice characteristics and the use of out-of-hours care GP cooperatives. A cross-sectional observational study in 100 general practices in the Netherlands, connected to five GP cooperatives. In each GP cooperative, we took a purposeful sample of the 10 general practices with the highest use of out-of-hours care and the 10 practices with the lowest use. Practice and population characteristics were obtained by questionnaires, interviews, data extraction from patient registration systems and telephone accessibility measurements. To examine which aspects of practice organisation were associated with patients' use of out-of-hours care, we performed logistic regression analyses (low versus high out-of-hours care use), correcting for population characteristics. The mean out-of-hours care use in the high use group of general practices was 1.8 times higher than in the low use group. Day time primary care practices with more young children and foreigners in their patient populations and with a shorter distance to the GP cooperative had higher out-of-hours primary care use. In addition, longer telephone waiting times and lower personal availability for palliative patients in daily practice were associated with higher use of out-of-hours care. Moreover, out-of-hours care use was higher when practices performed more diagnostic tests and therapeutic procedures and had more assistant employment hours per 1000 patients. Several other aspects of practice management showed some non-significant trends: high utilising general practices tended to have longer waiting times for non-urgent appointments, lower availability of a telephone consulting hour, lower availability for consultations after 5 p.m., and less frequent

New Results on the Effect of Mothers’ Working Hours on Children’s Overweight Status

DEFF Research Database (Denmark)

Greve, Jane

in exploring possible bias due to omitted variable bias. In contrast to the existing literature this paper shows that an increase in mothers’ working hours has a reducing effect on child weight. Subgroup analyses on formal and informal daycare suggest that the quality of childcare determines the effect...... weight. This paper uses the Danish Longitudinal Survey of Children (DALSC) merged with Danish register data from 1995 to 2002 to explore whether a causal relationship exists between maternal working hours and Danish children’s overweight status at age 7½. The instrumental variables technique is used......, as results show that maternal employment has a reducing effect on children’s overweight status in formal daycare (kindergarten). For children in informal daycare (family daycare), maternal employment has no significant effect....

Impacts of licensed premises trading hour policies on alcohol-related harms.

Science.gov (United States)

Atkinson, Jo-An; Prodan, Ante; Livingston, Michael; Knowles, Dylan; O'Donnell, Eloise; Room, Robin; Indig, Devon; Page, Andrew; McDonnell, Geoff; Wiggers, John

2018-07-01

Evaluations of alcohol policy changes demonstrate that restriction of trading hours of both 'on'- and 'off'-licence venues can be an effective means of reducing rates of alcohol-related harm. Despite this, the effects of different trading hour policy options over time, accounting for different contexts and demographic characteristics, and the common co-occurrence of other harm reduction strategies in trading hour policy initiatives, are difficult to estimate. The aim of this study was to use dynamic simulation modelling to compare estimated impacts over time of a range of trading hour policy options on various indicators of acute alcohol-related harm. An agent-based model of alcohol consumption in New South Wales, Australia was developed using existing research evidence, analysis of available data and a structured approach to incorporating expert opinion. Five policy scenarios were simulated, including restrictions to trading hours of on-licence venues and extensions to trading hours of bottle shops. The impact of the scenarios on four measures of alcohol-related harm were considered: total acute harms, alcohol-related violence, emergency department (ED) presentations and hospitalizations. Simulation of a 3 a.m. (rather than 5 a.m.) closing time resulted in an estimated 12.3 ± 2.4% reduction in total acute alcohol-related harms, a 7.9 ± 0.8% reduction in violence, an 11.9 ± 2.1% reduction in ED presentations and a 9.5 ± 1.8% reduction in hospitalizations. Further reductions were achieved simulating a 1 a.m. closing time, including a 17.5 ± 1.1% reduction in alcohol-related violence. Simulated extensions to bottle shop trading hours resulted in increases in rates of all four measures of harm, although most of the effects came from increasing operating hours from 10 p.m. to 11 p.m. An agent-based simulation model suggests that restricting trading hours of licensed venues reduces rates of alcohol-related harm and extending trading hours of bottle

Achieving Accreditation Council for Graduate Medical Education duty hours compliance within advanced surgical training: a simulation-based feasibility assessment.

Science.gov (United States)

Obi, Andrea; Chung, Jennifer; Chen, Ryan; Lin, Wandi; Sun, Siyuan; Pozehl, William; Cohn, Amy M; Daskin, Mark S; Seagull, F Jacob; Reddy, Rishindra M

2015-11-01

Certain operative cases occur unpredictably and/or have long operative times, creating a conflict between Accreditation Council for Graduate Medical Education (ACGME) rules and adequate training experience. A ProModel-based simulation was developed based on historical data. Probabilistic distributions of operative time calculated and combined with an ACGME compliant call schedule. For the advanced surgical cases modeled (cardiothoracic transplants), 80-hour violations were 6.07% and the minimum number of days off was violated 22.50%. There was a 36% chance of failure to fulfill any (either heart or lung) minimum case requirement despite adequate volume. The variable nature of emergency cases inevitably leads to work hour violations under ACGME regulations. Unpredictable cases mandate higher operative volume to ensure achievement of adequate caseloads. Publically available simulation technology provides a valuable avenue to identify adequacy of case volumes for trainees in both the elective and emergency setting. Copyright © 2015 Elsevier Inc. All rights reserved.

Identifying Factors Reinforcing Robotization: Interactive Forces of Employment, Working Hour and Wage

Directory of Open Access Journals (Sweden)

Joonmo Cho

2018-02-01

Full Text Available Unlike previous studies on robotization approaching the future based on the cutting-edge technologies and adopting a framework where robotization is considered as an exogenous variable, this study considers that robotization occurs endogenously and uses it as a dependent variable for an objective examination of the effect of robotization on the labor market. To this end, a robotization indicator is created based on the actual number of industrial robots currently deployed in workplaces, and a multiple regression analysis is performed using the robotization indicator and labor variables such as employment, working hours, and wage. The results using the multiple regression considering the triangular relationship of employment–working-hours–wages show that job destruction due to robotization is not too remarkable yet that use. Our results show the complementary relation between employment and robotization, but the substituting relation between working hour and robotization. The results also demonstrate the effects of union, the size of the company and the proportion of production workers and simple labor workers etc. These findings indicate that the degree of robotization may vary with many factors of the labor market. Limitations of this study and implications for future research are also discussed.

Variability of African Farming Systems from Phenological Analysis of NDVI Time Series

Science.gov (United States)

Vrieling, Anton; deBeurs, K. M.; Brown, Molly E.

2011-01-01

Food security exists when people have access to sufficient, safe and nutritious food at all times to meet their dietary needs. The natural resource base is one of the many factors affecting food security. Its variability and decline creates problems for local food production. In this study we characterize for sub-Saharan Africa vegetation phenology and assess variability and trends of phenological indicators based on NDVI time series from 1982 to 2006. We focus on cumulated NDVI over the season (cumNDVI) which is a proxy for net primary productivity. Results are aggregated at the level of major farming systems, while determining also spatial variability within farming systems. High temporal variability of cumNDVI occurs in semiarid and subhumid regions. The results show a large area of positive cumNDVI trends between Senegal and South Sudan. These correspond to positive CRU rainfall trends found and relate to recovery after the 1980's droughts. We find significant negative cumNDVI trends near the south-coast of West Africa (Guinea coast) and in Tanzania. For each farming system, causes of change and variability are discussed based on available literature (Appendix A). Although food security comprises more than the local natural resource base, our results can perform an input for food security analysis by identifying zones of high variability or downward trends. Farming systems are found to be a useful level of analysis. Diversity and trends found within farming system boundaries underline that farming systems are dynamic.

Hours of television viewing and sleep duration in children: a multicenter birth cohort study.

Science.gov (United States)

Marinelli, Marcella; Sunyer, Jordi; Alvarez-Pedrerol, Mar; Iñiguez, Carmen; Torrent, Maties; Vioque, Jesús; Turner, Michelle C; Julvez, Jordi

2014-05-01

This study used longitudinal data to examine potential associations between hours of television viewing and sleep duration in children. To examine the association between hours of television viewing and sleep duration in preschool and school-aged children. Longitudinal, multicenter study among birth cohorts in Menorca, Sabadell, and Valencia from the Spanish Infancia y Medio Ambiente (environment and childhood) project. The study sample included 1713 children (468 from Menorca, 560 from Sabadell, and 685 from Valencia). Parent-reported child television viewing duration measured in hours per day at 2 and 4 years of age in Sabadell and Valencia and at 6 and 9 years of age in Menorca. Parent-reported child sleep duration measured in hours per day at 2 and 4 years of age in Sabadell and Valencia and at 6 and 9 years of age in Menorca. In cross-sectional analysis, children with longer periods of television viewing reported at baseline (≥ 1.5 hours per day) had shorter sleep duration. Longitudinally, children with reported increases in television viewing duration over time (from <1.5 to ≥ 1.5 hours per day) had a reduction in sleep duration at follow-up visits. Results were similar when examining television viewing duration as a continuous variable, with each 1 hour per day of increased viewing decreasing sleep duration at follow-up visits (β = -0.11; 95% CI, -0.18 to -0.05). Associations were similar when television viewing duration was assessed during weekends and after adjusting for potential intermediate factors (child executive function and attention-deficit/hyperactivity disorder symptoms) and confounders (child physical activity level, parental mental health status, maternal IQ, and maternal marital status). Children spending longer periods watching television had shorter sleep duration. Changes in television viewing duration were inversely associated with changes in sleep duration in longitudinal analysis. Parents should consider avoiding long periods of

Do Working Hours and Type of Work Affect Obesity in South Korean Female Workers? Analysis of the Korean Community Health Survey.

Science.gov (United States)

Yoon, Chang-Gyo; Kang, Mo-Yeol; Bae, Kyu-Jung; Yoon, Jin-Ha

2016-02-01

The prevalence of obesity and the female labor participation rate have been rapidly increasing in South Korea. To examine the relationship between these factors, we investigated the association between timing and type of work and obesity in the Korean female working population. Data collected by the 2008 Community Health Survey (CHS) were analyzed using a complex, stratified, multistage, probability cluster sampling method. Descriptive analysis of relevant variables was performed using the chi-square test, and work-related variables by work type were identified using multivariate logistic regression. The relationship between long working hours, night/shift work, and body-mass index in female workers and explanatory, stratifying, and dependent variables and covariates was analyzed using multiple logistic regression models. A total of 42,234 CHS participants were eligible for study inclusion. Among both manual and nonmanual workers, working less than 40 (adjusted odds ratio [aOR] 1.18, 95% confidence interval [CI] 1.07-1.31 and aOR 1.29; 95% CI 1.09-0.52, respectively) or more than 60 (aOR 1.18, 95% CI 1.06-1.30 and aOR 1.28, 95% CI 1.04-1.57, respectively) hours per week was significantly associated with obesity after controlling for covariates. However, working type (day or night/shift) was significantly associated with obesity only in nonmanual workers (aOR 1.20, 95% CI 1.01-1.42). When we controlled working type in the model, manual workers who work more than 60 hours show higher likelihood of being obese (OR 1.10, 95% CI 1.02-1.18). Working fewer (60) hours per week is significantly associated with obesity in the Korean female working population, regardless of the type of work. The type of work (day vs. night/shift work) was significantly associated with obesity only in only nonmanual workers.

Occurrence of hypotension in older participants. Which 24-hour ABPM parameter better correlate with?

Science.gov (United States)

Scuteri, Angelo; Modestino, Anna; Frattari, Alessandra; Di Daniele, Nicola; Tesauro, Manfredi

2012-06-01

The aim of the present study was to investigate the prevalence of hypotension in older participants and to identify which 24-hour ambulatory blood pressure monitoring parameter better correlated with the occurrence of hypotension. We studied 588 elderly participants (mean age 78.7 ± 7.1 years; 70% women) who underwent a 24-hour ambulatory blood pressure (BP) monitoring, without moderate-to-severe cognitive impairment, myocardial infarction, or stroke within the previous 6 months; renal (serum creatinine > 2.5 mg/dL), respiratory, or liver insufficiency; and atrial fibrillation. In older participants, the occurrence of systolic hypotension is very common (≈55% presenting at least one episode of systolic blood pressure (SBP) < 100 mmHg and about 20% presenting ≥10% of the SBP registrations < 100 mmHg). More than 30% of participants with 24-hour SBP, daytime, and nighttime above the reference threshold had hypotension. Hypotension did not correlated with BP variability indices (standard deviation of BPs). None of the parameters commonly present in 24-hour ambulatory BP monitoring clinical reports is able to accurately identify those older participants with episode of hypotension. Episodes of SBP hypotension are extremely common in older participants and do not appear to relate to BP variability indices. Indeed, no parameter of 24-hour ambulatory BP monitoring was capable to accurately identify the occurrence of hypotension. We expect that ongoing studies will contribute to identification of specific factors predicting hypotensive episodes in the older participants.

Analysis of Modal Travel Time Variability Due to Mesoscale Ocean Structure

National Research Council Canada - National Science Library

Smith, Amy

1997-01-01

.... First, for an open ocean environment away from strong boundary currents, the effects of randomly phased linear baroclinic Rossby waves on acoustic travel time are shown to produce a variable overall...

Resting heart rate variability is associated with ex-Gaussian metrics of intra-individual reaction time variability.

Science.gov (United States)

Spangler, Derek P; Williams, DeWayne P; Speller, Lassiter F; Brooks, Justin R; Thayer, Julian F

2018-03-01

The relationships between vagally mediated heart rate variability (vmHRV) and the cognitive mechanisms underlying performance can be elucidated with ex-Gaussian modeling-an approach that quantifies two different forms of intra-individual variability (IIV) in reaction time (RT). To this end, the current study examined relations of resting vmHRV to whole-distribution and ex-Gaussian IIV. Subjects (N = 83) completed a 5-minute baseline while vmHRV (root mean square of successive differences; RMSSD) was measured. Ex-Gaussian (sigma, tau) and whole-distribution (standard deviation) estimates of IIV were derived from reaction times on a Stroop task. Resting vmHRV was found to be inversely related to tau (exponential IIV) but not to sigma (Gaussian IIV) or the whole-distribution standard deviation of RTs. Findings suggest that individuals with high vmHRV can better prevent attentional lapses but not difficulties with motor control. These findings inform the differential relationships of cardiac vagal control to the cognitive processes underlying human performance. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Month-hour distributions of zenith luminance and diffuse illuminance in Madrid

International Nuclear Information System (INIS)

Soler, Alfonso; Gopinathan, Kannam K.; Robledo, Luis; Ruiz, Enrique

2004-01-01

Month-hour equal mean zenith luminance contours are obtained from one year of data of zenith luminance measurements for cloudless, overcast and partly cloudy skies and also when the combined data for all sky types are considered. For many hours in different months, the overcast sky luminance values are roughly about three times the cloudless sky luminance values and one and a half times the partly cloudy sky values. The dependence of month-hour equal mean zenith luminance contours on the ratio of global to extraterrestrial illuminance on a horizontal surface is also given. From equal mean zenith luminance contours, the approximate values of the mean zenith luminance for different sky conditions and different hours and months of the year can be easily obtained. Month-hour equal mean diffuse illuminance contours are obtained from diffuse illuminance measurements performed during the period 1992-1998. The dependence on solar altitude of the monthly average hourly values of diffuse illuminance is given and compared to the corresponding one obtained from data for Bet Dagan (Israel)

Gender and the Effect of Working Hours on Firm-Sponsored Training

OpenAIRE

Picchio, Matteo; van Ours, Jan C.

2015-01-01

Using employees' longitudinal data, we study the effect of working hours on the propensity of firms to sponsor training of their employees. We show that, whereas male part-time workers are less likely to receive training than male full-timers, part-time working women are as likely to receive training as full-time working women. Although we cannot rule out gender-working time specific monopsony power, we speculate that the gender-specific effect of working hours on training has to do with gend...

Work Hours, Social Value of Leisure and Globalisation

DEFF Research Database (Denmark)

Hansen, Jørgen Drud; Nielsen, Jørgen Ulff-Møller; Montagna, Catia

We examine how openness interacts with the coordination of consumption-leisure decisions in determining the equilibrium working hours and wage rate when there are leisure externalities (e.g., due to social interactions). The latter are modelled by allowing a worker's marginal utility of leisure...... to be increasing in the leisure time taken by other workers. Coordination takes the form of internalising the leisure externality and other relevant constraints (e.g., labour demand). The extent of openness is measured by the degree of capital mobility. We find that: coordination lowers equilibrium work hours...... and raises the wage rate; there is a U-shaped (inverse-U-shaped) relationship between work hours (wages) and the degree of coordination; coordination is welfare improving; and, the gap between the coordinated and uncoordinated work hours (and the corresponding wage rates) is affected by the extent and nature...

Work Hours, Social Value of Leisure and Globalisation

DEFF Research Database (Denmark)

Hansen, Jørgen Drud; Molana, Hassan; Montagna, Catia

2010-01-01

We examine how openness interacts with the coordination of consumption-leisure decisions in determining the equilibrium working hours and wage rate when there are leisure externalities (e.g., due to social interactions). The latter are modelled by allowing a worker's marginal utility of leisure...... to be increasing in the leisure time taken by other workers. Coordination takes the form of internalising the leisure externality and other relevant constraints (e.g., labour demand). The extent of openness is measured by the degree of capital mobility. We find that: coordination lowers equilibrium work hours...... and raises the wage rate; there is a U-shaped (inverse-U-shaped) relationship between work hours (wages) and the degree of coordination; coordination is welfare improving; and, the gap between the coordinated and uncoordinated work hours (and the corresponding wage rates) is affected by the extent and nature...

Work hours, social value of leisure and globalisation

DEFF Research Database (Denmark)

Hansen, Jørgen Drud; Molana, Hassan; Montagna, Catia

2012-01-01

We examine how openness interacts with the coordination of consumption-leisure decisions in determining the equilibrium working hours and wage rate when there are leisure externalities (e.g., due to social interactions). The latter are modelled by allowing a worker’s marginal utility of leisure...... to be increasing in the leisure time taken by other workers. Coordination takes the form of internalising the leisure externality and other relevant constraints (e.g., labour demand). The extent of openness is measured by the degree of capital mobility. We find that: coordination lowers equilibrium work hours...... and raises the wage rate; there is a U-shaped (inverse-U-shaped) relationship between work hours (wages) and the degree of coordination; coordination is welfare improving; and, the gap between the coordinated and uncoordinated work hours (and the corresponding wage rates) is affected by the extent and nature...

Sub-hourly impacts of high solar penetrations in the Western United States

Energy Technology Data Exchange (ETDEWEB)

Lew, Debra; Brinkman, Greg; Florita, Anthony; Heaney, Michael; Hodge, Bri-Mathias; Hummon, Marissa; Ibanez, Eduardo [National Renewable Energy Lab. (NREL), Golden, CO (United States); King, Jack [RePPAE, Wexford, PA (United States)

2012-07-01

Until recently, it has been difficult to study the impacts of significant penetrations of hypothetical, utility-scale solar photovoltaic (PV) plants over large geographic regions. This was because of the lack of credible data to simulate the output of these plants with appropriate spatial and temporal correlation, especially on a sub-hourly basis. In the Western Wind and Solar Integration Study Phase 2 (WWSIS2), we used new technigues to synthesize sub-hourly high-resolution solar output for PV rooftops, utility-scale PV, and concentrating solar power (CSP). This allowed us to examine implications of 25 % solar (60/40 split of PV and CSP) and 8 % wind. In this paper, we present results of analysis on the sub-hourly impacts of high solar penetrations. Extreme event analysis showed that most of the large ramps were because of sunrise and sunset events, which have a significant predictability component. Variability in general was much higher with high penetrations of solar than with high penetrations of wind. Reserve methodologies that had already been developed for wind were therefore modified to take into account the predictability component of solar variability. Significantly less transmission was required for high solar penetrations than wind and significantly less curtailment occurred in the high solar cases. (orig.)

Long working hours and alcohol risk among Australian and New Zealand nurses and midwives: a cross-sectional study.

Science.gov (United States)

Schluter, Philip J; Turner, Catherine; Benefer, Christine

2012-06-01

The relationship between long working hours and harmful alcohol consumption reported in the literature is equivocal. This study aimed to investigate this relationship in a methodologically rigorous fashion. A cross-sectional analysis of a large cohort study of Australian and New Zealand nurses and midwives was undertaken. Psychometrically robust standardised assessments of alcohol consumption and problems and other key variables were elicited using an electronic survey. Crude and adjusted logistic regression models using complete case and multistage multiple imputed data were employed. The study included 4419 participants, 3552 from Australia and 867 from New Zealand. Long working hours were common, with 33.2% working 40-49 h/week and 7.5% working ≥50 h/week. Overall, 13.9% engaged in harmful daily drinking. Significant associations between long working hours and harmful daily alcohol consumption was seen in crude and adjusted complete case and imputed logistic regression models. In the adjusted model with imputed data, the odds of harmful daily drinking increased by 1.17 (95% confidence interval: 1.01, 1.36) between work long hours. Since the late 1970s, the average hours worked by full-time employees in Australia has increased. Unless these long working hours can be curbed, workforce policies and programmes aimed at prevention, supportive and empathetic intervention, and recovery need to be instigated; both to protect patients and the nurses and midwives themselves. Copyright © 2012 Elsevier Ltd. All rights reserved.

Quadratic time dependent Hamiltonians and separation of variables

Science.gov (United States)

Anzaldo-Meneses, A.

2017-06-01

Time dependent quantum problems defined by quadratic Hamiltonians are solved using canonical transformations. The Green's function is obtained and a comparison with the classical Hamilton-Jacobi method leads to important geometrical insights like exterior differential systems, Monge cones and time dependent Gaussian metrics. The Wei-Norman approach is applied using unitary transformations defined in terms of generators of the associated Lie groups, here the semi-direct product of the Heisenberg group and the symplectic group. A new explicit relation for the unitary transformations is given in terms of a finite product of elementary transformations. The sequential application of adequate sets of unitary transformations leads naturally to a new separation of variables method for time dependent Hamiltonians, which is shown to be related to the Inönü-Wigner contraction of Lie groups. The new method allows also a better understanding of interacting particles or coupled modes and opens an alternative way to analyze topological phases in driven systems.

In the aftermath of SPRINT: further comparison of unattended automated office blood pressure measurement and 24-hour blood pressure monitoring.

Science.gov (United States)

Seidlerová, Jitka; Gelžinský, Julius; Mateřánková, Markéta; Ceral, Jiří; König, Petr; Filipovský, Jan

2018-03-22

Several papers reported that unattended automated office blood pressure (uAutoOBP) is closely related to daytime ambulatory blood pressure monitoring (ABPM). In the present study, we aim to study uAutoOBP and its relation to 24-hour ABPM and ABPM variability. Stable treated hypertensive subjects were examined in two Czech academic hypertension centres. uAutoOBP was measured with the BP Tru device; attended BP three times with auscultatory method (AuscOBP) by the physician. ABPM was performed within one week from the clinical visit. Data on 98 subjects aged 67.7 ± 9.3 years with 24-hour ABPM 120.3 ± 10.6/72.7 ± 7.9 mm Hg are reported. uAutoOBP was lower than 24-hour (by -5.2 ± 11.3/-0.5 ± 6.9 mm Hg) and daytime (by -6.7 ± 12.82.4 ± 8.0 mm Hg) ABPM and the individual variability of the difference was very large (up to 30 mm Hg). The correlation coefficients between ABPM and uAutoOBP were similar compared to AuscOBP (p ≥ .17). Variability of uAutoOBP, but not AuscOBP, readings during one clinical visit was related to short-term blood pressure variability of ABPM. The difference between AuscOBP and uAutoOBP was larger in patients with white-coat effect compared to other blood pressure control groups (25.1 ± 7.0 vs. 2.2 ± 10.3 mm Hg; p = .0036). Our study shows that uAutoOBP is not good predictor of ambulatory blood pressure monitoring, not even of the daytime values. It might, however, indicate short-term blood pressure variability and, when compared with AuscOBP, also detect patients with white-coat effect.

Appropriate working hours for surgical training according to Australasian trainees.

Science.gov (United States)

O'Grady, Gregory; Harper, Simon; Loveday, Benjamin; Adams, Brandon; Civil, Ian D; Peters, Matthew

2012-04-01

The demands of surgical training, learning and service delivery compete with the need to minimize fatigue and maintain an acceptable lifestyle. The optimal balance of working hours is uncertain. This study aimed to define the appropriate hours to meet these requirements according to trainees. All Australian and New Zealand surgical trainees were surveyed. Roster structures, weekly working hours and weekly 'sleep loss hours' (work practices were then correlated with sufficiency of training time, time for study, fatigue and its impacts, and work-life balance preferences. Multivariate and univariate analyses were performed. The response rate was 55.3% with responders representative of the total trainee body. Trainees who worked median 60 h/week (interquartile range: 55-65) considered their work hours to be appropriate for 'technical' and 'non-technical' training needs compared with 55 h/week (interquartile range: 50-60) regarded as appropriate for study/research needs. Working ≥65 h/week, or accruing ≥5.5 weekly 'sleep loss hours', was associated with increased fatigue, reduced ability to study, more frequent dozing while driving and impaired concentration at work. Trainees who considered they had an appropriate work-life balance worked median 55 h/week. Approximately, 60 h/week proved an appropriate balance of working hours for surgical training, although study and lifestyle demands are better met at around 55 h/week. Sleep loss is an important determinant of fatigue and its impacts, and work hours should not be considered in isolation. © 2012 The Authors. ANZ Journal of Surgery © 2012 Royal Australasian College of Surgeons.

The Impact of Hours Flexibility on Career Employment, Bridge Jobs, and the Timing of Retirement

OpenAIRE

Kevin E. Cahill; Michael D. Giandrea; Joseph F. Quinn

2014-01-01

To what extent does hours flexibility in career employment impact the retirement process? Workplace flexibility policies have the potential to improve both the welfare of employees and the business outcomes of employers. These policies, and hours flexibility in particular for older Americans, have also been touted as a way to reduce turnover. For older Americans, reductions in turnover could mean more years in career employment, fewer years in bridge employment, and little or no impact on the...

Hourly and daily variation of sediment redox potential in tidal wetland sediments

Science.gov (United States)

Catallo, W. James

1999-01-01

Variation of electrochemical oxidation-reduction (redox) potential was examined in surface salt march sediments under conditions of flooding and tidal simulation in mesocosms and field sites. Time series were generated of redox potential measured in sediment profiles at 2-10 cm depth using combination Pt-Ag/AgCl (ORP) electrodes. Redox potential data were acquired at rapid rates (1-55 samples/h) over extended periods (3-104 days) along with similar times series of temperature (water, air, soil) and pH. It was found that redox potential vaired as a result of water level changes and was unrelated to diurnal changes in temperature or pH, the latter of which changed by 370 mV redox potential decrease in under 48 hours). Attenuatoin of microbial activity by [gamma] y-radiation and toxic chemicals elimintated this response. In tidal salt marsh mesocosms where the sediment-plant assemblages were exposed to a simulated diurnal tide, redox potenial oscillations of 40-300 mV amplitude were recoded that has the same periodicity as the flood-drain cycle. Periodic redoc potential time series were observed repeatedly in sediments receiving tidal pulsing but not in those sediments exposed to static hydrological conditions. Data collected over 12 days from a coastal marsh site experiencing diurnal tides showed similar fluctuations in redox potential. Data from the experimentents indicated that (a) redox potential can be a dynamic, nonlinear variable in coastal and estuarine wetland sediments over hourly and daily scales, and the designs of biogeochemical experiments should reflect this, (b) redox potential can change rapidly and signigicantly in coastal wetland sediments in response of flooding and draining, (c) microbial community processes are primarily determinants of the time course of redox potential in wetland sediments, and elimination of inhibition of microbial activity (e.g. by pollutants) can significantly alter that behavior, and (d) fast redox potential dynamics appear

A Time-Series Water Level Forecasting Model Based on Imputation and Variable Selection Method.

Science.gov (United States)

Yang, Jun-He; Cheng, Ching-Hsue; Chan, Chia-Pan

2017-01-01

Reservoirs are important for households and impact the national economy. This paper proposed a time-series forecasting model based on estimating a missing value followed by variable selection to forecast the reservoir's water level. This study collected data from the Taiwan Shimen Reservoir as well as daily atmospheric data from 2008 to 2015. The two datasets are concatenated into an integrated dataset based on ordering of the data as a research dataset. The proposed time-series forecasting model summarily has three foci. First, this study uses five imputation methods to directly delete the missing value. Second, we identified the key variable via factor analysis and then deleted the unimportant variables sequentially via the variable selection method. Finally, the proposed model uses a Random Forest to build the forecasting model of the reservoir's water level. This was done to compare with the listing method under the forecasting error. These experimental results indicate that the Random Forest forecasting model when applied to variable selection with full variables has better forecasting performance than the listing model. In addition, this experiment shows that the proposed variable selection can help determine five forecast methods used here to improve the forecasting capability.

Averaging and sampling for magnetic-observatory hourly data

Directory of Open Access Journals (Sweden)

J. J. Love

2010-11-01

Full Text Available A time and frequency-domain analysis is made of the effects of averaging and sampling methods used for constructing magnetic-observatory hourly data values. Using 1-min data as a proxy for continuous, geomagnetic variation, we construct synthetic hourly values of two standard types: instantaneous "spot" measurements and simple 1-h "boxcar" averages. We compare these average-sample types with others: 2-h average, Gaussian, and "brick-wall" low-frequency-pass. Hourly spot measurements provide a statistically unbiased representation of the amplitude range of geomagnetic-field variation, but as a representation of continuous field variation over time, they are significantly affected by aliasing, especially at high latitudes. The 1-h, 2-h, and Gaussian average-samples are affected by a combination of amplitude distortion and aliasing. Brick-wall values are not affected by either amplitude distortion or aliasing, but constructing them is, in an operational setting, relatively more difficult than it is for other average-sample types. It is noteworthy that 1-h average-samples, the present standard for observatory hourly data, have properties similar to Gaussian average-samples that have been optimized for a minimum residual sum of amplitude distortion and aliasing. For 1-h average-samples from medium and low-latitude observatories, the average of the combination of amplitude distortion and aliasing is less than the 5.0 nT accuracy standard established by Intermagnet for modern 1-min data. For medium and low-latitude observatories, average differences between monthly means constructed from 1-min data and monthly means constructed from any of the hourly average-sample types considered here are less than the 1.0 nT resolution of standard databases. We recommend that observatories and World Data Centers continue the standard practice of reporting simple 1-h-average hourly values.

Suicidality, psychopathology, and the internet: Online time vs. online behaviors.

Science.gov (United States)

Harris, Keith M; Starcevic, Vladan; Ma, Jing; Zhang, Wei; Aboujaoude, Elias

2017-09-01

This study investigated whether several psychopathology variables, including suicidality, could predict the time people spend using the internet (hours online). Next, we examined a specific at-risk population (suicidal individuals) by their online behaviors, comparing suicidal individuals who went online for suicide-related purposes with suicidal individuals who did not go online for suicide-related purposes. An anonymous online sample of 713 (aged 18-71) reported hours online, psychiatric histories, and completed several standardized scales. After accounting for age and education, hierarchical regression modeling showed that the assessed psychopathology variables, including suicidality, did not explain significant variance in hours online. Hours online were better predicted by younger age, greater willingness to develop online relationships, higher perceived social support, higher curiosity, and lower extraversion. Suicidal participants, who did or did not go online for suicide-related purposes, did not differ on hours online. Multiple regression modeling showed that those who went online for suicide-related purposes were likely to be younger, more suicidal, and more willing to seek help from online mental health professionals. These findings revealed that hours online are not a valid indicator of psychopathology. However, studying online behaviors of specific at-risk groups could be informative and useful, including for suicide prevention efforts. Copyright © 2017. Published by Elsevier B.V.

Multi-Band Intra-Night Optical Variability of BL Lacertae

Directory of Open Access Journals (Sweden)

Haritma Gaur

2017-12-01

Full Text Available We monitored BL Lacertae frequently during 2014–2016 when it was generally in a high state. We searched for intra-day variability for 43 nights using quasi-simultaneous measurements in the B, V, R, and I bands (totaling 143 light curves; the typical sampling interval was about eight minutes. On hour-like timescales, BL Lac exhibited significant variations during 13 nights in various optical bands. Significant spectral variations are seen during most of these nights such that the optical spectrum becomes bluer when brighter. The amplitude of variability is usually greater for longer observations but is lower when BL Lac is brighter. No evidence for periodicities or characteristic variability time-scales in the light curves was found. The color variations are mildly chromatic on long timescales.

2011 Hours against hate

OpenAIRE

Cátedra Intercultural. UCO

2011-01-01

2011 Hours Against Hate is a campaign to stop bigotry and promote respect across lines of culture, religion, tradition, class, and gender. Launched by Special Representative to Muslim Communities Farah Pandith, and Special Envoy to Monitor and Combat Anti-Semitism Hannah Rosenthal, the State Department is asking young people around the world to pledge their time to stop hate—to do something for someone who doesn’t look like you, pray like you, or live like you. We are asking the next generati...

Numerical counting ratemeter with variable time constant and integrated circuits

International Nuclear Information System (INIS)

Kaiser, J.; Fuan, J.

1967-01-01

We present here the prototype of a numerical counting ratemeter which is a special version of variable time-constant frequency meter (1). The originality of this work lies in the fact that the change in the time constant is carried out automatically. Since the criterion for this change is the accuracy in the annunciated result, the integration time is varied as a function of the frequency. For the prototype described in this report, the time constant varies from 1 sec to 1 millisec. for frequencies in the range 10 Hz to 10 MHz. This prototype is built entirely of MECL-type integrated circuits from Motorola and is thus contained in two relatively small boxes. (authors) [fr

Sensitivity of Variables with Time for Degraded RC Shear Wall with Low Steel Ratio under Seismic Load

International Nuclear Information System (INIS)

Park, Jun Hee; Choun, Young Sun; Choi, In Kil

2011-01-01

Various factors lead to the degradation of reinforced concrete (RC) shear wall over time. The steel section loss, concrete spalling and strength of material have been considered for the structural analysis of degraded shear wall. When all variables with respect to degradation are considered for probabilistic evaluation of degraded shear wall, many of time and effort were demanded. Therefore, it is required to define important variables related to structural behavior for effectively conducting probabilistic seismic analysis of structures with age-related degradation. In this study, variables were defined by applying the function of time to consider degradation with time. Importance of variables with time on the seismic response was investigated by conducting sensitivity analysis

Cataclysmic Variable Stars

Science.gov (United States)

Hellier, Coel

2001-01-01

Cataclysmic variable stars are the most variable stars in the night sky, fluctuating in brightness continually on timescales from seconds to hours to weeks to years. The changes can be recorded using amateur telescopes, yet are also the subject of intensive study by professional astronomers. That study has led to an understanding of cataclysmic variables as binary stars, orbiting so closely that material transfers from one star to the other. The resulting process of accretion is one of the most important in astrophysics. This book presents the first account of cataclysmic variables at an introductory level. Assuming no previous knowledge of the field, it explains the basic principles underlying the variability, while providing an extensive compilation of cataclysmic variable light curves. Aimed at amateur astronomers, undergraduates, and researchers, the main text is accessible to those with no mathematical background, while supplementary boxes present technical details and equations.

Efficient conservative ADER schemes based on WENO reconstruction and space-time predictor in primitive variables

Science.gov (United States)

Zanotti, Olindo; Dumbser, Michael

2016-01-01

We present a new version of conservative ADER-WENO finite volume schemes, in which both the high order spatial reconstruction as well as the time evolution of the reconstruction polynomials in the local space-time predictor stage are performed in primitive variables, rather than in conserved ones. To obtain a conservative method, the underlying finite volume scheme is still written in terms of the cell averages of the conserved quantities. Therefore, our new approach performs the spatial WENO reconstruction twice: the first WENO reconstruction is carried out on the known cell averages of the conservative variables. The WENO polynomials are then used at the cell centers to compute point values of the conserved variables, which are subsequently converted into point values of the primitive variables. This is the only place where the conversion from conservative to primitive variables is needed in the new scheme. Then, a second WENO reconstruction is performed on the point values of the primitive variables to obtain piecewise high order reconstruction polynomials of the primitive variables. The reconstruction polynomials are subsequently evolved in time with a novel space-time finite element predictor that is directly applied to the governing PDE written in primitive form. The resulting space-time polynomials of the primitive variables can then be directly used as input for the numerical fluxes at the cell boundaries in the underlying conservative finite volume scheme. Hence, the number of necessary conversions from the conserved to the primitive variables is reduced to just one single conversion at each cell center. We have verified the validity of the new approach over a wide range of hyperbolic systems, including the classical Euler equations of gas dynamics, the special relativistic hydrodynamics (RHD) and ideal magnetohydrodynamics (RMHD) equations, as well as the Baer-Nunziato model for compressible two-phase flows. In all cases we have noticed that the new ADER

Effects of gender and game type on autonomic nervous system physiological parameters in long-hour online game players.

Science.gov (United States)

Lin, Tung-Cheng

2013-11-01

Online game playing may induce physiological effects. However, the physical mechanisms that cause these effects remain unclear. The purpose of this study was to examine the physiological effects of long-hour online gaming from an autonomic nervous system (ANS) perspective. Heart rate variability (HRV), a valid and noninvasive electrocardiographic method widely used to investigate ANS balance, was used to measure physiological effect parameters. This study used a five-time, repeated measures, mixed factorial design. Results found that playing violent games causes significantly higher sympathetic activity and diastolic blood pressure than playing nonviolent games. Long-hour online game playing resulted in the gradual dominance of the parasympathetic nervous system due to physical exhaustion. Gaming workload was found to modulate the gender effects, with males registering significantly higher sympathetic activity and females significantly higher parasympathetic activity in the higher gaming workload group.

“Friday off”: Reducing Working Hours in Europe

Directory of Open Access Journals (Sweden)

Jack Rossiter

2013-04-01

Full Text Available This article explores the pros and cons for reducing working hours in Europe. To arrive to an informed judgment we review critically the theoretical and empirical literature, mostly from economics, concerning the relation between working hours on the one hand, and productivity, employment, quality of life, and the environment, on the other. We adopt a binary economics distinction between capital and labor productiveness, and are concerned with how working hours may be reduced without harming the earning capacity of workers. There are reasons to believe that reducing working hours may absorb some unemployment, especially in the short-run, even if less than what is advocated by proponents of the proposal. Further, there may well be strong benefits for the quality of peoples’ lives. Environmental benefits are likely but depend crucially on complementary policies or social conditions that will ensure that the time liberated will not be directed to resource-intensive or environmentally harmful consumption. It is questionable whether reduced working hours are sustainable in the long-term given resource limits and climate change. We conclude that while the results of reducing working hours are uncertain, this may be a risk worth taking, especially as an interim measure that may relieve unemployment while other necessary structural changes are instituted.

TEC variability near northern EIA crest and comparison with IRI model

Science.gov (United States)

Aggarwal, Malini

2011-10-01

Monthly median values of hourly total electron content (TEC) is obtained with GPS at a station near northern anomaly crest, Rajkot (geog. 22.29°N, 70.74°E; geomag. 14.21°N, 144.9°E) to study the variability of low latitude ionospheric behavior during low solar activity period (April 2005 to March 2006). The TEC exhibit characteristic features like day-to-day variability, semiannual anomaly and noon bite out. The observed TEC is compared with latest International Reference Ionosphere (IRI) - 2007 model using options of topside electron density, NeQuick, IRI01-corr and IRI-2001 by using both URSI and CCIR coefficients. A good agreement of observed and predicted TEC is found during the daytime with underestimation at other times. The predicted TEC by NeQuick and IRI01-corr is closer to the observed TEC during the daytime whereas during nighttime and morning hours, IRI-2001 shows lesser discrepancy in all seasons by both URSI and CCIR coefficients.

Time-variable gravity fields derived from GPS tracking of Swarm

Czech Academy of Sciences Publication Activity Database

Bezděk, Aleš; Sebera, Josef; da Encarnacao, J.T.; Klokočník, Jaroslav

2016-01-01

Roč. 205, č. 3 (2016), s. 1665-1669 ISSN 0956-540X R&D Projects: GA MŠk LG14026; GA ČR GA13-36843S Institutional support: RVO:67985815 Keywords : satellite geodesy * time variable gravity * global change from geodesy Subject RIV: DD - Geochemistry Impact factor: 2.414, year: 2016

Energy and Reserve under Distributed Energy Resources Management—Day-Ahead, Hour-Ahead and Real-Time

Directory of Open Access Journals (Sweden)

Tiago Soares

2017-11-01

Full Text Available The increasing penetration of distributed energy resources based on renewable energy sources in distribution systems leads to a more complex management of power systems. Consequently, ancillary services become even more important to maintain the system security and reliability. This paper proposes and evaluates a generic model for day-ahead, intraday (hour-ahead and real-time scheduling, considering the joint optimization of energy and reserve in the scope of the virtual power player concept. The model aims to minimize the operation costs in the point of view of one aggregator agent taking into account the balance of the distribution system. For each scheduling stage, previous scheduling results and updated forecasts are considered. An illustrative test case of a distribution network with 33 buses, considering a large penetration of distribution energy resources allows demonstrating the benefits of the proposed model.

Correlates of adolescent sleep time and variability in sleep time: the role of individual and health related characteristics.

Science.gov (United States)

Moore, Melisa; Kirchner, H Lester; Drotar, Dennis; Johnson, Nathan; Rosen, Carol; Redline, Susan

2011-03-01

Adolescents are predisposed to short sleep duration and irregular sleep patterns due to certain host characteristics (e.g., age, pubertal status, gender, ethnicity, socioeconomic class, and neighborhood distress) and health-related variables (e.g., ADHD, asthma, birth weight, and BMI). The aim of the current study was to investigate the relationship between such variables and actigraphic measures of sleep duration and variability. Cross-sectional study of 247 adolescents (48.5% female, 54.3% ethnic minority, mean age of 13.7years) involved in a larger community-based cohort study. Significant univariate predictors of sleep duration included gender, minority ethnicity, neighborhood distress, parent income, and BMI. In multivariate models, gender, minority status, and BMI were significantly associated with sleep duration (all pminority adolescents, and those of a lower BMI obtaining more sleep. Univariate models demonstrated that age, minority ethnicity, neighborhood distress, parent education, parent income, pubertal status, and BMI were significantly related to variability in total sleep time. In the multivariate model, age, minority status, and BMI were significantly related to variability in total sleep time (all pminority adolescents, and those of a lower BMI obtaining more regular sleep. These data show differences in sleep patterns in population sub-groups of adolescents which may be important in understanding pediatric health risk profiles. Sub-groups that may particularly benefit from interventions aimed at improving sleep patterns include boys, overweight, and minority adolescents. Copyright © 2011 Elsevier B.V. All rights reserved.

More hours, more jobs? The employment effects of longer working hours

OpenAIRE

Martyn Andrews; Hans-Dieter Gerner; Thorsten Schank; Richard Upward

2015-01-01

Increases in standard hours of work have been a contentious policy issue in Germany. Whilst this might directly lead to a substitution of workers by hours, there may also be a positive employment effect due to reduced costs. Moreover, the response of firms may differ between firms that offer overtime and those that do not. For a panel of German plants (2001–2006) drawn from the IAB Establishment Panel, we are the first to analyse the effect of increased standard hours on employment. Using dif...

Out-of-office hours' elective surgical intensive care admissions and their associated complications.

Science.gov (United States)

Morgan, David J R; Ho, Kwok Ming; Ong, Yang Jian; Kolybaba, Marlene L

2017-11-01

The 'weekend' effect is a controversial theory that links reduced staffing levels, staffing seniority and supportive services at hospitals during 'out-of-office hours' time periods with worsening patient outcomes. It is uncertain whether admitting elective surgery patients to intensive care units (ICU) during 'out-of-office hours' time periods mitigates this affect through higher staffing ratios and seniority. Over a 3-year period in Western Australia's largest private hospital, this retrospective nested-cohort study compared all elective surgical patients admitted to the ICU based on whether their admission occurred 'in-office hours' (Monday-Friday 08.00-18.00 hours) or 'out-of-office hours' (all other times). The main outcomes were surgical complications using the Dindo-Clavien classification and length-of-stay data. Of the total 4363 ICU admissions, 3584 ICU admissions were planned following elective surgery resulting in 2515 (70.2%) in-office hours and 1069 (29.8%) out-of-office hours elective ICU surgical admissions. Out-of-office hours ICU admissions following elective surgery were associated with an increased risk of infection (P = 0.029), blood transfusion (P = 0.020), total parental nutrition (P office hours ICU admissions were also associated with an increased hospital length-of-stay, with (1.74 days longer, P office hours ICU admissions following elective surgery is common and associated with serious post-operative complications culminating in significantly longer hospital length-of-stays and greater transfers with important patient and health economic implications. © 2017 Royal Australasian College of Surgeons.

Optimizing Wellfield Operation in a Variable Power Price Regime.

Science.gov (United States)

Bauer-Gottwein, Peter; Schneider, Raphael; Davidsen, Claus

2016-01-01

Wellfield management is a multiobjective optimization problem. One important objective has been energy efficiency in terms of minimizing the energy footprint (EFP) of delivered water (MWh/m(3) ). However, power systems in most countries are moving in the direction of deregulated markets and price variability is increasing in many markets because of increased penetration of intermittent renewable power sources. In this context the relevant management objective becomes minimizing the cost of electric energy used for pumping and distribution of groundwater from wells rather than minimizing energy use itself. We estimated EFP of pumped water as a function of wellfield pumping rate (EFP-Q relationship) for a wellfield in Denmark using a coupled well and pipe network model. This EFP-Q relationship was subsequently used in a Stochastic Dynamic Programming (SDP) framework to minimize total cost of operating the combined wellfield-storage-demand system over the course of a 2-year planning period based on a time series of observed price on the Danish power market and a deterministic, time-varying hourly water demand. In the SDP setup, hourly pumping rates are the decision variables. Constraints include storage capacity and hourly water demand fulfilment. The SDP was solved for a baseline situation and for five scenario runs representing different EFP-Q relationships and different maximum wellfield pumping rates. Savings were quantified as differences in total cost between the scenario and a constant-rate pumping benchmark. Minor savings up to 10% were found in the baseline scenario, while the scenario with constant EFP and unlimited pumping rate resulted in savings up to 40%. Key factors determining potential cost savings obtained by flexible wellfield operation under a variable power price regime are the shape of the EFP-Q relationship, the maximum feasible pumping rate and the capacity of available storage facilities. © 2015 The Authors. Groundwater published by Wiley

The relationship between hours of sleep, screen time and frequency of food and drink consumption in Spain in the 2011 and 2013 ALADINO: a cross-sectional study.

Science.gov (United States)

Pérez-Farinós, Napoleón; Villar-Villalba, Carmen; López Sobaler, Ana María; Dal Re Saavedra, María Ángeles; Aparicio, Aránzazu; Santos Sanz, Sara; Robledo de Dios, Teresa; Castrodeza-Sanz, José Javier; Ortega Anta, Rosa María

2017-01-06

The frequency of intake of food and beverages depends on a number of ill-defined behaviour patterns. The objectives of this study were to evaluate the effects of screen time and sleep duration on food consumption frequency, and to describe frequencies and types of food consumption according to BMI category and parents' level of education. We studied 6287 and 2806 children drawn from the 2011 and 2013 cross-sectional ALADINO studies respectively. Data were collected on number of hours of sleep, screen time, and weekly frequency of consumption of 17 food groups. Weight status was measured, and information was also collected on parents' educational level. Average food consumption frequencies were calculated by reference to hours of sleep and hours of screen time, and were defined as ≥4 times or education. High levels of screen time were associated with a greater frequency of consumption of energy-dense, micronutrient-poor products and a lower frequency of consumption of fruit and vegetables. Sleeping a sufficient number of hours was associated with a higher consumption of fruit and vegetables. The results for 2011 were concordant with those for 2013. If efforts to ensure healthier eating habits among children are to be at all successful, they should focus on promoting a sufficient amount of sleep for children, limiting the time they spend watching television and/or playing with computers or video games, and educating parents accordingly.

Development of Electronic Medical Record-Based "Rounds Report" Results in Improved Resident Efficiency, More Time for Direct Patient Care and Education, and Less Resident Duty Hour Violations.

Science.gov (United States)

Ham, Phillip B; Anderton, Toby; Gallaher, Ryan; Hyrman, Mike; Simmerman, Erika; Ramanathan, Annamalai; Fallaw, David; Holsten, Steven; Howell, Charles Gordon

2016-09-01

Surgeons frequently report frustration and loss of efficiency with electronic medical record (EMR) systems. Together, surgery residents and a programmer at Augusta University created a rounds report (RR) summarizing 24 hours of vitals, intake/output, labs, and other values for each inpatient that were previously transcribed by hand. The objective of this study was to evaluate the RR's effect on surgery residents. Surgery residents were queried to assess the RR's impact. Outcome measures were time spent preparing for rounds, direct patient care time, educational activity time, rates of incorrect/incomplete data on rounds, and rate of duty hour violations. Hospital wide, 17,200 RRs were generated in the 1-month study. Twenty-three surgery residents participated. Time spent preparing for rounds decreased per floor patient (15.6 ± 3.0 vs 6.0 ± 1.2, P care unit patient (19.9 ± 2.9 vs 7.5 ± 1.2 P care increased from 45.1 ± 5.6 to 54.0 ± 5.7 per cent (P = 0.0044). Educational activity time increased from 35.2 ± 5.4 to 54.7 ± 7.1 minutes per resident per day (P = 0.0004). Reported duty hour violations decreased 58 per cent (P care at academic medical centers.

The relationship between hours of sleep, screen time and frequency of food and drink consumption in Spain in the 2011 and 2013 ALADINO: a cross-sectional study

Directory of Open Access Journals (Sweden)

Napoleón Pérez-Farinós

2017-01-01

Full Text Available Abstract Background The frequency of intake of food and beverages depends on a number of ill-defined behaviour patterns. The objectives of this study were to evaluate the effects of screen time and sleep duration on food consumption frequency, and to describe frequencies and types of food consumption according to BMI category and parents’ level of education. Methods We studied 6287 and 2806 children drawn from the 2011 and 2013 cross-sectional ALADINO studies respectively. Data were collected on number of hours of sleep, screen time, and weekly frequency of consumption of 17 food groups. Weight status was measured, and information was also collected on parents’ educational level. Average food consumption frequencies were calculated by reference to hours of sleep and hours of screen time, and were defined as ≥4 times or <4 times per week (once per week for soft drinks and diet soft drinks. Differences in frequency were evaluated for screen times of more and less than 2 h per day, and for sleep durations longer or shorter than the daily average. We fitted logistic regression models to evaluate the independent association between screen exposure and hours of sleep on the one hand, and food consumption frequency on the other. Results Consumption of fruit and vegetables was lower among children who had parents with no formal or only primary school education. High levels of screen time were associated with a greater frequency of consumption of energy-dense, micronutrient-poor products and a lower frequency of consumption of fruit and vegetables. Sleeping a sufficient number of hours was associated with a higher consumption of fruit and vegetables. The results for 2011 were concordant with those for 2013. Conclusions If efforts to ensure healthier eating habits among children are to be at all successful, they should focus on promoting a sufficient amount of sleep for children, limiting the time they spend watching television and/or playing with

Working hours and productivity

NARCIS (Netherlands)

Collewet, Marion; Sauermann, Jan

2017-01-01

This paper studies the link between working hours and productivity using daily information on working hours and performance of a sample of call centre agents. We exploit variation in the number of hours worked by the same employee across days and weeks due to central scheduling, enabling us to

29 CFR 778.320 - Hours that would not be hours worked if not paid for.

Science.gov (United States)

2010-07-01

... working hours fall in this category. The agreement of the parties to provide compensation for such hours... regular rate of an employee if the hours are compensated at the same rate as other working hours. The.... Activities of this type include eating meals between working hours. Where it appears from all the pertinent...

[Organization of socially acceptable working hours in nursing].

Science.gov (United States)

Büssing, A; Glaser, J

1994-05-01

Three dimensions in the structure of the working hour system of nurses, rendering them socially acceptable, are becoming important: duration of the working day, the time of day which is being worked and the distribution of working hours. The latter two are of particular importance because flexible shift is becoming the dominant pattern in nursing. Six indicators are discussed as criteria for social acceptability: security of employment which includes access to the labour-market, level of income, health, opportunity for social relationships, social participation, and autonomy. Responses of 297 nurses in one General Hospital taking part in a study, were analysed to examine empirically the concept of 'socially acceptable structure of the working hours'. Ideal and factual patterns are considered first. Secondly aspects of autonomy are considered and the way this depends on time, thirdly the criteria used to define 'social acceptability' are examined for validity. Results show firstly the cross contrast between the hospital's expectation and the nurses' wishes with regard to working hours. Furthermore, inspite of the demand for flexibility, staff have very little choice and there is little sign of joint decision making. Thirdly results show that health, interpersonal and social aspects are of special importance and that, correspondingly, in the view of nurses, financial and practical problems are of lesser importance in their every day life.

Do Japanese Work Shorter Hours than before?: Measuring Trends in Market Work and Leisure Using 1976-2006 Japanese Time-Use Survey

OpenAIRE

Kuroda, Sachiko

2009-01-01

Using Japanese time-use data from the Survey on Time Use and Leisure Activities (STULA), this paper measures trends in average hours worked (market work) and leisure for Japanese over the past three decades. OECD reports at least a 15 percent decline in market work for Japan since the 1970s. However, holding demographic changes constant, we found that market work per week increased from the 1970s until mid 1980s, and has been relatively stable for the last two decades for both male and female...

Office workers' objectively measured sedentary behavior and physical activity during and outside working hours.

Science.gov (United States)

Clemes, Stacy A; O'Connell, Sophie E; Edwardson, Charlotte L

2014-03-01

To examine objectively determined sedentary behavior and physical activity (PA) during and outside working hours in full-time office workers. A total of 170 participants wore an ActiGraph GT1M accelerometer for 7 days. Time spent sedentary (working hours and nonworking hours) and nonworkdays. Participants accumulated significantly higher levels of sedentary behavior (68% vs 60%) and lower levels of light-intensity activity (28% vs 36%) on workdays in comparison with nonworkdays. Up to 71% of working hours were spent sedentary. Individuals who were most sedentary at work were also more sedentary outside work. Those who are most sedentary at work do not compensate by increasing their PA or reducing their sedentary time outside work. Occupational interventions should address workplace and leisure-time sedentary behavior.

Excitation of Earth Rotation Variations "Observed" by Time-Variable Gravity

Science.gov (United States)

Chao, Ben F.; Cox, C. M.

2005-01-01

Time variable gravity measurements have been made over the past two decades using the space geodetic technique of satellite laser ranging, and more recently by the GRACE satellite mission with improved spatial resolutions. The degree-2 harmonic components of the time-variable gravity contain important information about the Earth s length-of-day and polar motion excitation functions, in a way independent to the traditional "direct" Earth rotation measurements made by, for example, the very-long-baseline interferometry and GPS. In particular, the (degree=2, order= 1) components give the mass term of the polar motion excitation; the (2,O) component, under certain mass conservation conditions, gives the mass term of the length-of-day excitation. Combining these with yet another independent source of angular momentum estimation calculated from global geophysical fluid models (for example the atmospheric angular momentum, in both mass and motion terms), in principle can lead to new insights into the dynamics, particularly the role or the lack thereof of the cores, in the excitation processes of the Earth rotation variations.

A Time-Series Water Level Forecasting Model Based on Imputation and Variable Selection Method

Directory of Open Access Journals (Sweden)

Jun-He Yang

2017-01-01

Full Text Available Reservoirs are important for households and impact the national economy. This paper proposed a time-series forecasting model based on estimating a missing value followed by variable selection to forecast the reservoir’s water level. This study collected data from the Taiwan Shimen Reservoir as well as daily atmospheric data from 2008 to 2015. The two datasets are concatenated into an integrated dataset based on ordering of the data as a research dataset. The proposed time-series forecasting model summarily has three foci. First, this study uses five imputation methods to directly delete the missing value. Second, we identified the key variable via factor analysis and then deleted the unimportant variables sequentially via the variable selection method. Finally, the proposed model uses a Random Forest to build the forecasting model of the reservoir’s water level. This was done to compare with the listing method under the forecasting error. These experimental results indicate that the Random Forest forecasting model when applied to variable selection with full variables has better forecasting performance than the listing model. In addition, this experiment shows that the proposed variable selection can help determine five forecast methods used here to improve the forecasting capability.

Improved Hourly and Sub-Hourly Gauge Data for Assessing Precipitation Extremes in the U.S.

Science.gov (United States)

Lawrimore, J. H.; Wuertz, D.; Palecki, M. A.; Kim, D.; Stevens, S. E.; Leeper, R.; Korzeniewski, B.

2017-12-01

The NOAA/National Weather Service (NWS) Fischer-Porter (F&P) weighing bucket precipitation gauge network consists of approximately 2000 stations that comprise a subset of the NWS Cooperative Observers Program network. This network has operated since the mid-20th century, providing one of the longest records of hourly and 15-minute precipitation observations in the U.S. The lengthy record of this dataset combined with its relatively high spatial density, provides an important source of data for many hydrological applications including understanding trends and variability in the frequency and intensity of extreme precipitation events. In recent years NOAA's National Centers for Environmental Information initiated an upgrade of its end-to-end processing and quality control system for these data. This involved a change from a largely manual review and edit process to a fully automated system that removes the subjectivity that was previously a necessary part of dataset quality control and processing. An overview of improvements to this dataset is provided along with the results of an analysis of observed variability and trends in U.S. precipitation extremes since the mid-20th century. Multi-decadal trends in many parts of the nation are consistent with model projections of an increase in the frequency and intensity of heavy precipitation in a warming world.

Variable slip wind generator modeling for real-time simulation

Energy Technology Data Exchange (ETDEWEB)

Gagnon, R.; Brochu, J.; Turmel, G. [Hydro-Quebec, Varennes, PQ (Canada). IREQ

2006-07-01

A model of a wind turbine using a variable slip wound-rotor induction machine was presented. The model was created as part of a library of generic wind generator models intended for wind integration studies. The stator winding of the wind generator was connected directly to the grid and the rotor was driven by the turbine through a drive train. The variable resistors was synthesized by an external resistor in parallel with a diode rectifier. A forced-commutated power electronic device (IGBT) was connected to the wound rotor by slip rings and brushes. Simulations were conducted in a Matlab/Simulink environment using SimPowerSystems blocks to model power systems elements and Simulink blocks to model the turbine, control system and drive train. Detailed descriptions of the turbine, the drive train and the control system were provided. The model's implementation in the simulator was also described. A case study demonstrating the real-time simulation of a wind generator connected at the distribution level of a power system was presented. Results of the case study were then compared with results obtained from the SimPowerSystems off-line simulation. Results showed good agreement between the waveforms, demonstrating the conformity of the real-time and the off-line simulations. The capability of Hypersim for real-time simulation of wind turbines with power electronic converters in a distribution network was demonstrated. It was concluded that hardware-in-the-loop (HIL) simulation of wind turbine controllers for wind integration studies in power systems is now feasible. 5 refs., 1 tab., 6 figs.

Seventy two-hour glucose monitoring profiles in mild gestational diabetes mellitus: differences from healthy pregnancies and influence of diet counseling.

Science.gov (United States)

Carreiro, Marina Pimenta; Lauria, Márcio W; Naves, Gabriel Nino T; Miranda, Paulo Augusto C; Leite, Ricardo Barsaglini; Rajão, Kamilla Maria Araújo Brandão; de Aguiar, Regina Amélia Lopes Pessoa; Nogueira, Anelise Impeliziere; Ribeiro-Oliveira, Antônio

2016-09-01

To study glucose profiles of gestational diabetes (GDM) patients with 72 h of continuous glucose monitoring (CGM) either before (GDM1) or after (GDM2) dietary counseling, comparing them with nondiabetic (NDM) controls. We performed CGM on 22 GDM patients; 11 before and 11 after dietary counseling and compared them to 11 healthy controls. Several physiological and clinical characteristics of the glucose profiles were compared across the groups, including comparisons for pooled 24-h measures and hourly median values, summary measures representing glucose exposure (area under the median curves) and variability (amplitude, standard deviation, interquartile range), and time points related to meals. Most women (81.8%) in the GDM groups had fasting glucose 0.05). Both GDM groups spent more time with glucose levels above 140mg/dL when compared with the NDM group. No differences among the groups were found for: pooled measurements and hourly comparisons, exposure, nocturnal, fasting, between lunch and dinner and before meals, as well as after lunch (P>0.05 for all). The main differences between the mild GDM1 group and healthy controls were related to glucose variability and excursions above 140mg/dL, while glucose exposure was similar. Glucose levels after breakfast and dinner also discerned the GDM1 group. Dietary counseling was able to keep glucose levels to those of healthy patients. © 2016 European Society of Endocrinology.

Work Hours of Immigrant Versus U.S.-Born Female Workers.

Science.gov (United States)

Bae, Sung-Heui

2017-10-01

This study was a secondary analysis of cross-sectional data extracted from the 2011-2012 California Health Interview Survey. Data from 8,931 full-time (i.e., 21 hours or more per week) women workers aged 18 to 85 years were analyzed to examine the nature and prevalence of immigrant female workers' work hours, overtime, and related factors in the United States compared to U.S.-born female workers. Results showed that foreign-born female workers did not work longer hours than U.S.-born female workers. Foreign-born female workers who reported poor health worked longer hours than did their U.S.-born counterparts. Foreign-born female workers who were self-employed or worked in family businesses tended to work longer hours than did those women who worked for private companies or nonprofit organizations.

Working hours and sleep duration in midlife as determinants of health-related quality of life among older businessmen.

Science.gov (United States)

von Bonsdorff, Mikaela Birgitta; Strandberg, Arto; von Bonsdorff, Monika; Törmäkangas, Timo; Pitkälä, Kaisu H; Strandberg, Timo E

2017-01-25

Long working hours and short sleep duration are associated with a range of adverse health consequences. However, the combined effect of these two exposures on health-related quality of life (HRQoL) has not been investigated. We studied white men born between 1919 and 1934 in the Helsinki Businessmen Study (HBS, initial n = 3,490). Data on clinical variables, self-rated health (SRH), working hours and sleep duration in 1974, and RAND-36 (SF-36) HRQoL survey in the year 2000 were available for 1,527 men. Follow-up time was 26 years. By combining working hours and sleep duration, four categories were formed: (i) normal work (≤50 hours/week) and normal sleep (>47 hours/week); (ii) long work (>50 hours/week) and normal sleep; (iii) normal work and short sleep (≤47 hours/week); and (iv) long work and short sleep. The association with RAND-36 domains was examined using multiple linear regression models adjusted for age, smoking and SRH. Compared to those with normal work and sleep in midlife, men with long work and short sleep had poorer RAND-36 scores for physical functioning, vitality and general health, and those with long work and normal sleep had poorer scores for physical functioning in old age. Adjustment for midlife smoking and SRH attenuated the associations, but the one for long work and short sleep and physical functioning remained significant (difference in mean physical functioning score −4.58, 95% confidence interval −9.00 to −0.15). Businessmen who had long working hours coupled with short sleep duration in midlife had poorer physical health in old age. © The Author 2016. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Electrical Activity in a Time-Delay Four-Variable Neuron Model under Electromagnetic Induction

Directory of Open Access Journals (Sweden)

Keming Tang

2017-11-01

Full Text Available To investigate the effect of electromagnetic induction on the electrical activity of neuron, the variable for magnetic flow is used to improve Hindmarsh–Rose neuron model. Simultaneously, due to the existence of time-delay when signals are propagated between neurons or even in one neuron, it is important to study the role of time-delay in regulating the electrical activity of the neuron. For this end, a four-variable neuron model is proposed to investigate the effects of electromagnetic induction and time-delay. Simulation results suggest that the proposed neuron model can show multiple modes of electrical activity, which is dependent on the time-delay and external forcing current. It means that suitable discharge mode can be obtained by selecting the time-delay or external forcing current, which could be helpful for further investigation of electromagnetic radiation on biological neuronal system.

The predicted CLARREO sampling error of the inter-annual SW variability

Science.gov (United States)

Doelling, D. R.; Keyes, D. F.; Nguyen, C.; Macdonnell, D.; Young, D. F.

2009-12-01

The NRC Decadal Survey has called for SI traceability of long-term hyper-spectral flux measurements in order to monitor climate variability. This mission is called the Climate Absolute Radiance and Refractivity Observatory (CLARREO) and is currently defining its mission requirements. The requirements are focused on the ability to measure decadal change of key climate variables at very high accuracy. The accuracy goals are set using anticipated climate change magnitudes, but the accuracy achieved for any given climate variable must take into account the temporal and spatial sampling errors based on satellite orbits and calibration accuracy. The time period to detect a significant trend in the CLARREO record depends on the magnitude of the sampling calibration errors relative to the current inter-annual variability. The largest uncertainty in climate feedbacks remains the effect of changing clouds on planetary energy balance. Some regions on earth have strong diurnal cycles, such as maritime stratus and afternoon land convection; other regions have strong seasonal cycles, such as the monsoon. However, when monitoring inter-annual variability these cycles are only important if the strength of these cycles vary on decadal time scales. This study will attempt to determine the best satellite constellations to reduce sampling error and to compare the error with the current inter-annual variability signal to ensure the viability of the mission. The study will incorporate Clouds and the Earth's Radiant Energy System (CERES) (Monthly TOA/Surface Averages) SRBAVG product TOA LW and SW climate quality fluxes. The fluxes are derived by combining Terra (10:30 local equator crossing time) CERES fluxes with 3-hourly 5-geostationary satellite estimated broadband fluxes, which are normalized using the CERES fluxes, to complete the diurnal cycle. These fluxes were saved hourly during processing and considered the truth dataset. 90°, 83° and 74° inclination precessionary orbits as

Enhanced Requirements for Assessment in a Competency-Based, Time-Variable Medical Education System.

Science.gov (United States)

Gruppen, Larry D; Ten Cate, Olle; Lingard, Lorelei A; Teunissen, Pim W; Kogan, Jennifer R

2018-03-01

Competency-based, time-variable medical education has reshaped the perceptions and practices of teachers, curriculum designers, faculty developers, clinician educators, and program administrators. This increasingly popular approach highlights the fact that learning among different individuals varies in duration, foundation, and goal. Time variability places particular demands on the assessment data that are so necessary for making decisions about learner progress. These decisions may be formative (e.g., feedback for improvement) or summative (e.g., decisions about advancing a student). This article identifies challenges to collecting assessment data and to making assessment decisions in a time-variable system. These challenges include managing assessment data, defining and making valid assessment decisions, innovating in assessment, and modeling the considerable complexity of assessment in real-world settings and richly interconnected social systems. There are hopeful signs of creativity in assessment both from researchers and practitioners, but the transition from a traditional to a competency-based medical education system will likely continue to create much controversy and offer opportunities for originality and innovation in assessment.

Discrete-time bidirectional associative memory neural networks with variable delays

International Nuclear Information System (INIS)

Liang Jinling; Cao Jinde; Ho, Daniel W.C.