Duration Trajectories Research Articles

Night sleep duration trajectories and associated factors among preschool children from the EDEN cohort

ObjectiveSleep duration may vary both interindividually and intraindividually over time. We aimed to identify night-sleep duration (NSD) trajectories among preschoolers and to study associated factors. MethodsNSD was collected within the French birth-cohort study EDEN at ages 2, 3, and 5–6 years through parental questionnaires, and were used to model NSD trajectories among 1205 children. Familial socioeconomic factors, maternal sociodemographic, health and lifestyle characteristics, as well as child health, lifestyle, and sleep characteristics at birth and/or at age two years were investigated in association with NSD using multinomial logistic regressions. ResultsFive distinct NSD trajectories were identified: short (SS, <10 h, 4.9%), medium-low (MLS, <11 h, 47.8%), medium–high (MHS, ≈11.5 h, 37.2%), long (LS, ≥11.5 h, 4.5%) and changing (CS, ie, ≥11.5 h then <11 h, 5.6%) NSD trajectories. Multivariable analyses showed in particular that compared to the MHS trajectory factors associated with increased risk for the SS trajectory were male gender, first child, maternal age and working status, night-waking, parental presence when falling asleep, television-viewing duration, as well as both “Processed and fast foods” and the “Baby food” dietary patterns at age two years. Factors positively associated with the CS trajectory were maternal smoking, feeding at night, and the Processed and fast foods dietary pattern at age two years, whereas child's activity and emotionality scores at age one year were negatively associated. ConclusionWe identified distinct NSD trajectories among preschoolers and associated early life factors. Some of them may reflect less healthy lifestyles, providing cues for early multi-behavioral prevention interventions.

Dual Trajectories of Sleep Duration and Cigarette Smoking during Adolescence: Relation to Subsequent Internalizing Problems.

Decreasing sleep duration and increasing cigarette smoking of adolescents are major public health concerns. However, research examining connections between the developmental trajectories of the outcomes that are evolving contemporaneously and their relation to long-term outcomes is still lacking. This study examined distinct trajectories of sleep duration and cigarette smoking during adolescence, associations between these trajectories, and links with internalizing problems during young adulthood. Data were collected from 2510 adolescents who participated in a longitudinal study spanning from 2006 through 2014 in northern Taiwan. Group-based dual trajectory modeling was used to examine the dynamic relationships between sleep duration and cigarette smoking trajectories during adolescence. Multiple linear regression was used to understand the association between the distinct trajectories and subsequent internalizing problems. Three sleep duration trajectories (short decreasing, typical sleep, and long sleep) and three cigarette smoking trajectories (nonsmokers, late increasing, and escalating smokers) were identified. We found significant inter-relationships for sleep duration and cigarette smoking trajectories during adolescence; all atypical sleep duration trajectories conferred increased risks of increased cigarette smoking and vice versa. In addition, the effects of sleep duration and cigarette smoking on later internalizing problems were found to vary by sex and trajectory patterns. These results provide insight regarding the co-development of sleep duration and cigarette smoking trajectories during adolescence. We also highlight the different roles of sleep duration and cigarette smoking trajectories and their relation to internalizing problems of young adulthood.

Deflection of fictitious asteroid 2017 PDC: Ion beam vs. kinetic impactor

Mission scenarios for the deflection of fictitious asteroid 2017 PDC are investigated. Two deflection options, kinetic impactor (KI) and ion beam shepherd (IBS), are studied and compared on the basis of deflection performance, safety, as well as mission schedule and political aspects. Firstly, we propose the launch of a medium-size rendevous spacecraft equipped with at least two ionic thrusters that can serve as propulsion means for the interplanetary trajectory up to rendezvous with the asteroid and as contactless actuators for a possible follow-up deflection mission. The asteroid, whose uncertainty ellipsoid is initially too large to establish whether (and how) it should be deflected, is reached by the rendezvous spacecraft after a low-thrust interplanetary trajectory of reasonable duration. Following rendezvous the spacecraft is placed in the vicinity of the asteroid to estimate its mass, study its structure and composition and, crucially, reduce its uncertainty ellipsoid by ground tracking to confirm or rule out an impact. Assuming that an impact is confirmed two main deflection scenarios are considered based on the actual asteroid size. Ion beam deflection is considered with the possibility of full deflection (the asteroid misses the Earth by a safe margin) or impact location adjustment (the impact footprint is diplaced to the nearest unpopulated region) depending on the asteroid size and the predicted impact location. The launch of a kinetic impactor mission is also considered with the employment of the rendezvous spacecraft to measure the deflection outcome and possibly to refine the deflection in case it is needed. The deflection performance of the two methods is compared.

Trajectories of sickness absence duration in Catalonia (Spain) from 2012 to 2014

Trajectories of sickness absence duration in Catalonia (Spain) from 2012 to 2014

Sleep Duration Trajectories and Systemic Inflammation in Young Adults: Results From the National Longitudinal Study of Adolescent to Adult Health (Add Health).

This study examines the effects of short and long sleep duration patterns in young adults on the levels of C-reactive protein (CRP), as well as the potential effect modification by sex. Using data from waves III (age 18-26) and IV (age 24-32) of the National Longitudinal study of adolescent to adult health, we examined the association between sleep trajectories in young adults, and the risk of elevated high sensitivity-CRP (hs-CRP), a marker of systemic inflammation. Short sleep trajectories were associated with significantly elevated log-transformed hs-CRP (coefficient = 0.11, p-value .03) and with significantly higher odds of having hs-CRP levels > 3 mg/L (OR = 1.86, 95% CI 1.29, 2.67). The association was modified by sex, with the association between short sleep duration and hs-CRP limited to males. Both the continuous (coefficient 0.117, p-value = .0362) and the categorized hs-CRP (OR = 2.21, 95% CI 1.48, 3.30) were significantly elevated with short sleep durations in males, whereas no significant associations were seen in females with short sleep durations. By contrast, log hs-CRP was significantly elevated in females with long sleep durations (coefficient = 0.232, p-value = .0296), with a nonsignificant increase in the odds of having hs-CRP levels greater than 3 mg/L (OR = 1.48, 95% CI 0.75, 2.93), whereas there were no associations with long sleep duration in males. Systemic inflammation, measured by an elevated level of hs-CRP, is seen with persistent short sleep duration in young adult men and persistent long sleep duration in young adult women.

Do gender and racial/ethnic disparities in sleep duration emerge in early adulthood? Evidence from a longitudinal study of U.S. adults

ObjectiveGender and racial/ethnic disparities in sleep duration are well documented among the U.S. adult population, but we know little about how these disparities are shaped during the early course of adult life, a period marked by substantial changes in social roles that can influence time for sleep. MethodsProspective data was used from the National Longitudinal Survey of Youth 1997 (NLSY97), a U.S.-based representative sample of persons born between 1980 and 1984, who were first interviewed in 1997. Sleep duration was assessed in 2002, 2007/2008, 2009, 2010, and 2011. Random-coefficient models were estimated to examine gender and racial/ethnic disparities in trajectories of sleep duration across early adulthood as a function of educational experiences, employment, and family relationships. ResultsSleep duration declined during early adulthood. Women reported shorter sleep than men from age 18 to 22, but slept longer than men by age 28. Black Young adults reported sleep durations similar to those of White young adults until age 24, after which blacks slept less than whites. Educational experiences and employment characteristics reduced gender and racial/ethnic disparities, but family relationships exacerbated them. ConclusionThis study is the first to establish the emergence of gender and racial/ethnic disparities in sleep duration during early adulthood.

Memory-induced diffusive-superdiffusive transition: Ensemble and time-averaged observables.

The ensemble properties and time-averaged observables of a memory-induced diffusive-superdiffusive transition are studied. The model consists in a random walker whose transitions in a given direction depend on a weighted linear combination of the number of both right and left previous transitions. The diffusion process is nonstationary, and its probability develops the phenomenon of aging. Depending on the characteristic memory parameters, the ensemble behavior may be normal, superdiffusive, or ballistic. In contrast, the time-averaged mean squared displacement is equal to that of a normal undriven random walk, which renders the process nonergodic. In addition, and similarly to Lévy walks [Godec and Metzler, Phys. Rev. Lett. 110, 020603 (2013)PRLTAO0031-900710.1103/PhysRevLett.110.020603], for trajectories of finite duration the time-averaged displacement apparently become random with properties that depend on the measurement time and also on the memory properties. These features are related to the nonstationary power-law decay of the transition probabilities to their stationary values. Time-averaged response to a bias is also calculated. In contrast with Lévy walks [Froemberg and Barkai, Phys. Rev. E 87, 030104(R) (2013)PLEEE81539-375510.1103/PhysRevE.87.030104], the response always vanishes asymptotically.

Sleep Trajectories Among Pregnant Women and the Impact on Outcomes: A Population-Based Cohort Study.

Objectives Sleep problems and deprivation are common during pregnancy, particularly in the third trimester. Previous studies are mostly descriptive or focused on specific clinical groups and late pregnancy. We aimed to identify sleep duration trajectories during the pregnancy period, their associated factors, and impact on pregnancy and birth outcomes. Methods We studied 200 women from a mother-child cohort recruited in 2009-2011 from the French general population. We used semi-parametric models to analyze data collected through questionnaires. Results We detected three sleep duration trajectories during pregnancy: short-decreasing (<6.5h/night, 10.8% of the sample), medium-decreasing (6.5-8h/night, 57.6%), and long-increasing (>8h/night, 31.6%) trajectories. Factors associated with the short-decreasing trajectory relative to the medium-decreasing trajectory were older age (odds-ratio/year = 1.13 [95%Confidence-Interval 1.00-1.29]) and working > 28 weeks of gestational age (odds-ratio = 0.30 [0.10-0.90]). Sleep duration during pregnancy in this trajectory group was modified by insomniac symptoms (regression coefficient/trimester = -0.74 [Standard-Error 0.12]) and naps (regression coefficient/trimester = 0.58 [0.25]). Restless legs syndrome was the only factor associated with the long-increasing trajectory and decreased sleep duration (regression coefficient/trimester = -0.88 [0.25]). Assisted delivery (i.e. cesarean section and/or instrumental delivery) and post-partum depression were more frequent among women with the short-decreasing and long-increasing trajectories whereas cesarean section alone was more prevalent among those with the short-decreasing trajectory. Proportion of premature births was higher in the short-decreasing trajectory group. Birth-weight-z-score was lower in the long-increasing trajectory group. Conclusion We identified sleep trajectories among pregnant women with specific risk factors that could affect both pregnancy and birth outcomes. Taking these into consideration could improve both maternal and child health.

Relationship between negative affect and smoking topography in heavy drinking smokers

Heavy drinking smokers represent a sizeable subgroup of smokers for whom nicotine deprivation and alcohol use increases the urge to smoke in the laboratory and predicts lapses during smoking cessation. The manner in which individuals smoke a cigarette (i.e. smoking topography) provides a reliable index of smoking intensity and reinforcement, yet the effects of affect on smoking topography have not been thoroughly examined in heavy drinking smokers. The current study examined how affect and nicotine deprivation predict smoking behavior as participants (N=27) smoked one cigarette using a smoking topography device after 12-h of nicotine abstinence and after a priming dose of alcohol (target BrAC=0.06g/dl). Primary smoking topography measures were puff volume, velocity, duration, and inter-puff interval (IPI). The effect of nicotine deprivation was measured by the Minnesota Nicotine Withdrawal Scale (MNWS) and the Profile of Mood States (POMS). Measures were obtained at baseline (i.e. 12-h of nicotine abstinence and pre-alcohol) and 30-minutes after alcohol administration (i.e. peak BrAC). Results revealed post-priming negative affect significantly moderated the trajectories of puff volume, puff duration and IPI (p's<0.05) over the course of the cigarette, such that those with greater negative affect had flatter slopes for volume and duration and increasingly infrequent puffs. Our results suggest that baseline and post-priming negative affect following nicotine deprivation alters smoking patterns and increases nicotine exposure throughout a single cigarette. Future studies need to examine differential amounts of nicotine deprivation on response to alcohol and smoking in heavy drinking smokers.

Sleep Duration Trajectories and Body Composition in Adolescents: Prospective Birth Cohort Study.

We aimed to estimate the association between sleep duration trajectories and body composition in adolescents. We used data from participants of the 1993 Pelotas (Brazil) Birth Cohort Study who were later followed up at age 18 years (response rate of 81.3%). At the time, 3974 adolescents had complete data on body composition, which was assessed by air displacement plethysmography. Sleep duration was self-reported by participants at ages 11 and 18 years. Analyses were sex-stratified. The mean sleep duration at 11 years was 9.7 (SD 1.4) and 8.4 (SD 1.9) at 18 years. Sleep duration was dichotomized as inadequate (<8 hours/day) or adequate (≥8 hours/day). Mean body mass, fat mass, and fat-free mass indices at 18 years were 23.4 kg/m2 (SD 4.5), 6.1 kg/m2 (SD 3.9) and 17.3 kg/m2 (SD 2.5), respectively. Girls who reported inadequate sleep duration at 11 years of age, but adequate sleep duration at 18, on average experienced an increase in body mass index (β = 0.39 z-scores; 95% CI 0.13, 0.65), fat mass index (β = 0.30 z-scores; 95% CI 0.07, 0.53), and fat-free mass index (β = 0.24 z-scores; 95% CI 0.08, 0.39) compared to those who had adequate sleep duration at both time points. The results suggest that changes in sleep duration across adolescence may impact body composition in later adolescence and that this may differ by sex.

Short persistent sleep duration is associated with poor receptive vocabulary performance in middle childhood

The aim of this study was to examine whether short sleep duration is associated with poor receptive vocabulary at age 10years. In the Quebec Longitudinal Study of Child Development, parents reported their children's nocturnal sleep duration annually from ages 2.5 to 10years, and children were assessed for receptive vocabulary using the Peabody PictureVocabulary Test-Revised (PPVT-R) at ages 4 and 10years. Groups with distinct nocturnal sleep duration trajectories were identified and the relationships between sleep trajectories and poor PPVT-R performance were characterized. In all, 1192 children with available sleep duration and PPVT-R data participated in this epidemiological study. We identified four longitudinal nocturnal sleep trajectories: short persistent sleepers (n=72, 6.0%), short increasing sleepers (n=47, 3.9%), 10-h sleepers (n=628, 52.7%) and 11-h sleepers (n=445, 37.3%). In all, 14.8% of the children showed poor PPVT-R performance at age 10years. Nocturnal sleep trajectories and poor PPVT-R performance at age 10 were associated significantly (P=0.003). After adjusting for baseline receptive vocabulary performance at age 4 and other potential confounding variables, logistic regression analyses suggest that, compared to 11-h sleepers, the odds ratio of presenting poor receptive vocabulary at age 10 was 2.67 [95% confidence interval (CI): 1.24-5.74, P=0.012] for short persistent sleepers and 1.66 (95% CI: 1.06-2.59, P=0.026) for 10-h sleepers. These results corroborate previous findings in early childhood, and indicate that short sleep duration is associated with poor receptive vocabulary during middle childhood.

Breastfeeding Duration and Weight Gain Trajectory in Infancy

Breastfeeding Duration and Weight Gain Trajectory in Infancy

Legislative processes as sequences: exploring temporal trajectories of Italian law-making by means of sequence analysis

The study of time in legislative processes has so far understood time mainly as duration (of the process as a whole or of its single stages). This work contributes to existing research by presenting a new approach to the study of time which takes as the unit of analysis the whole temporal trajectory followed by a bill from its introduction to the floor to its final adoption. Legislative processes are conceived of as sequences of stages a bill has to go through before its final adoption. The relative time spent in each of these stages varies considerably. This work aims to explore the determinants of variation in the observed trajectories of relative duration. To this end, it applies the tools of discrepancy sequence analysis, a method commonly employed for the study of occupational histories or life courses. The analysis was conducted on a sample of Italian legislative acts adopted in Italy from 1987 to 2008. Points for practitioners The greater availability of longitudinal data and the increased focus of social science theory on temporal change have contributed to heightening the attention given by social science scholars to the tools of sequence analysis. Scholars are increasingly recognizing that this set of methods may effectively complement existing techniques for the study of temporal data, by allowing new questions to be addressed. This article shows an example of how sequence analysis may be extended beyond the study of life or career histories, where it has been mainly confined. What is more, it presents an application of a novel technique, discrepancy analysis, which allows the study of the relationship between the trajectories and covariates of interest in an explanatory framework.

Trajectories and predictors of nocturnal awakenings and sleep duration in infants.

To examine the trajectories of sleep duration and nocturnal awakenings in infants from 6 to 18 months of age and to identify predictors of short sleep duration and nocturnal awakenings. Data for this study come from the Norwegian Mother and Child Cohort Study conducted at the Norwegian Institute of Public Health. A total of 55,831 mother reports of child sleep were used to estimate the stability and predictors of awakenings and short sleep. Nocturnal awakenings were frequent among 6-month-old children. Although there was an overall reduction in both sleep duration and nocturnal awakenings from 6 to 18 months, the chronicity of sleep problems was high and impacted by prior sleep behavior and sleeping arrangements. Bedsharing was an independent and graded predictor of nocturnal awakenings and short sleep duration, also after controlling for prior sleep. Breastfeeding was related to concurrent nocturnal awakening but was not negatively related to later nocturnal awakenings. Considering the chronicity of nocturnal awakening and its association with bedsharing, our findings support current recommendations of reducing bedsharing to improve sleep among infants.

Partitioning of RNA Polymerase Activity in Live Escherichia coli from Analysis of Single-Molecule Diffusive Trajectories

Superresolution fluorescence microscopy is used to locate single copies of RNA polymerase (RNAP) in live Escherichia coli and track their diffusive motion. On a timescale of 0.1–1 s, most copies separate remarkably cleanly into two diffusive states. The “slow” RNAPs, which move indistinguishably from DNA loci, are assigned to specifically bound copies (with fractional population ftrxn) that are initiating transcription, elongating, pausing, or awaiting termination. The “mixed-state” RNAP copies, with effective diffusion constant Dmixed = 0.21 μm2 s−1, are assigned as a rapidly exchanging mixture of nonspecifically bound copies (fns) and copies undergoing free, three-dimensional diffusion within the nucleoids (ffree). Longer trajectories of 7-s duration reveal transitions between the slow and mixed states, corroborating the assignments. Short trajectories of 20-ms duration enable direct observation of the freely diffusing RNAP copies, yielding Dfree = 0.7 μm2 s−1. Analysis of single-particle trajectories provides quantitative estimates of the partitioning of RNAP into different states of activity: ftrxn = 0.54 ± 0.07, fns = 0.28 ± 0.05, ffree = 0.12 ± 0.03, and fnb = 0.06 ± 0.05 (fraction unable to bind to DNA on a 1-s timescale). These fractions disagree with earlier estimates.

Feature-Points-Based Multimodel Single Dynamic Kernel Principle Component Analysis (M-SDKPCA) Modeling and Online Monitoring Strategy for Uneven-Length Batch Processes

Industrial batch processes are often characterized by durations of uneven lengths and large fluctuation of initial conditions. In this paper, to effectively detect weak faults caused by large fluctuation of initial conditions and capture inherent dynamics and nonlinearities and, meanwhile, to deal with the problem of batch trajectories of unequal duration and reduce computational complexion, a FP-based multimodel single dynamic kernel principle component analysis (M-SDKPCA) modeling and online monitoring method is proposed. Since the method integrates kernel PCA and autoregressive moving average exogenous time series model and refines models, M-SDKPCA improves the models on weak faults detection ability. In order to solve the problem of large amount of calculation brought by kernel operation, a three-step feature points (FP) extraction method is used to reduce the number of samples and equalize all batch length. The FP-based M-SDKPCA monitoring method was applied to fault detection for benchmark of fed-ba...

Trajectories of sleep changes during the acute phase of traumatic brain injury: A 7-day actigraphy study

To examine trajectories of change in sleep during the acute phase of traumatic brain injury (TBI), and whether specific demographic and disease characteristics predicted the initial levels of sleep and the trajectories of change in sleep parameters. This was a prospective observational study. Fifty-two patients with first-ever TBI were enrolled. Sleep parameters were measured using actigraphy for 7 consecutive days after admission. Hierarchical linear modeling was used for data analyses in 52 TBI patients and in a subgroup of mild TBI patients (n = 31). Participants had significant lower sleep efficiency, longer wake time after sleep onset, and longer 24-hour total sleep time (TST) than the normative data (all p < 0.05). Seventy-two percent of participants experienced prolonged 24-hour TST. Both daytime and 24-hour TST showed a significant downward trend across the study period. An initial Glasgow Coma Scale score < 11 significantly predicted the slope of change of daytime TST over time. Without initial loss of consciousness and age < 40 years were independent predictors of the change pattern of 24-hour TST over time. In the mild TBI subgroup, 24-hour TST significantly and gradually declined over time. Gender significantly predicted the trajectory of 24-hour sleep duration. Poor sleep efficiency and longer sleep duration are common symptoms in acute TBI patients. Both head injury severity and age predicted the trajectories of daytime and 24-hour sleep duration during the acute phase of TBI, whereas gender predicted the trajectories of 24-hour sleep duration in the mild TBI subgroup.

Defining the illness trajectory of metastatic breast cancer

BackgroundWith significant developments in the management of metastatic breast cancer, the trajectory of progressive breast cancer is becoming increasingly complex with little understanding of the illness course experienced by women,...

Genetic and Environmental Influences on Daytime and Nighttime Sleep Duration in Early Childhood

To determine the relative contributions of genetic and environmental factors on daytime and nighttime continuous sleep duration at 6, 18, 30, and 48 months of age, and to identify different subgroups of children who followed different daytime and nighttime sleep duration trajectories and to investigate their etiology. The current study included 995 twins (405 monozygotic and 586 dizygotic) of the Quebec Newborn Twin Study recruited from the birth records of the Quebec Statistics Institute. Daytime and nighttime sleep was assessed through maternal reports at 6, 18, 30, and 48 months of age. A semiparametric modeling strategy was used to estimate daytime and nighttime sleep duration trajectories. Quantitative genetic models were used to examine to what extent genetic and environmental factors influenced daytime and nighttime continuous sleep duration. Genetic modeling analyses revealed environmental influences for all daytime sleep duration trajectories. In contrast, strong genetic influences were found for consolidated nighttime sleep duration (except at 18 months and for the short-increasing sleep duration trajectory). This is the first indication that early childhood daytime sleep duration may be driven by environmental settings, whereas the variance in consolidated nighttime sleep duration is largely influenced by genetic factors with a critical environmental time-window influence at ∼18 months.

Finite-Time Effects and Ultraweak Ergodicity Breaking in Superdiffusive Dynamics

We study the ergodic properties of superdiffusive, spatiotemporally coupled Lévy walk processes. For trajectories of finite duration, we reveal a distinct scatter of the scaling exponents of the time averaged mean squared displacement δx2 around the ensemble value 3-α (1<α<2) ranging from ballistic motion to subdiffusion, in strong contrast to the behavior of subdiffusive processes. In addition we find a significant dependence of the average of δx2 over an ensemble of trajectories as a function of the finite measurement time. This so-called finite-time amplitude depression and the scatter of the scaling exponent is vital in the quantitative evaluation of superdiffusive processes. Comparing the long time average of the second moment with the ensemble mean squared displacement, these only differ by a constant factor, an ultraweak ergodicity breaking.