Sleep-wake patterns of student workers and non-workers

Adolescents usually exhibit late sleep phase and irregular sleep patterns. As a result, they do not get enough sleep and report daytime sleepiness. This condition could be aggravated in working students who have a more limited time for sleep. In this survey, we investigated the impact of evening classes and employment on the sleep patterns of adolescents. We compared female (n = 17) and male (n = 14) non-worker students to female (n = 28) and male (n = 20) worker students who attended the same high school. The volunteers (aged 17.4 years +/- 11 months) answered a sleep log during a 16-day period. Worker students slept and woke up earlier, had a shorter nocturnal sleep length and a shorter daily (nocturnal plus diurnal) sleep length compared to non-working pupils. The four groups of students delayed sleep onset time on weekends, but only worker students delayed wake-up time on Sundays. The wake-up time was similar among groups on Sundays. While student workers tended to increase the sleep length in the weekends, non-working students increased it on Mondays and/or Tuesdays. The results showed that sleep schedules and sleep length were different according to the work status. Going to bed later on Saturday by the four groups of students suggests the influence of social activities, while a later wake-up time on Sundays could result from a shorter sleep length on workdays.

The influence of study schedules and work on the sleep-wake cycle of college students

College students usually exhibit an irregular sleep-wake cycle characterized by great phase delays on weekends and short sleep length on weekdays. As the temporal organization of social activities is an important synchronizer of human biological rhythms, we investigated the role played by study's schedules and work on the sleep-wake cycle. Three groups of female college students were investigated: (1) no-job morning group, (2) no-job evening group, (3) job evening group. The volunteers answered a sleep questionnaire in the classroom. The effects of day of the week and group on the sleep schedules and sleep length were analyzed by a two way ANOVA for repeated measures. The three groups showed delays in the wake up time on weekends. No-job evening and morning groups also delayed bedtime, but the job evening group slept at the same time on weekdays as on weekends. Sleep length increased on weekends for morning group and job evening group, whereas the no-job evening group maintained the amount of sleep from weekdays to weekends. This survey showed that the tendency of phase delay on weekends was differently expressed according to study's schedules and work.

Measurement of B(B)over-bar angular correlations based on secondary vertex reconstruction at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the inclusive W and Z production cross sections in pp collisions at root s = 7 TeV with the CMS experiment

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Jet production rates in association with W and Z bosons in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for a Higgs boson in the decay channel H -> ZZ((*)) -> q(q)over-barl(-)l(+) in pp collisions at root s=7 TeV

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inclusive b-jet production in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Serotonin and circadian rhythms

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A industrialização das editoras e dos livros didáticos nos Estados Unidos (do século XIX ao começo do século XX)

Cet article examine la création de l'industrie du livre didactique aux États-Unis à partir des années 30 du XIXe siècle. Dès les années 20 de ce siècle, des maisons d'éditions sises dans les villes de New York et Boston étaient déjà capables de publier différents types de livres didactiques et de petits livres pour enfants et de les vendre aux quatre coins du pays, où elles avaient détaché des fonctionnaires pour ce faire. À la fin de cette décennie, le processus de production s'est sophistiqué avec l'organisation et l'entraînement d'équipes spécialisées dans l'écriture de schoolbooks. Dans le sillage de ces premières maisons d'éditions, d'autres se sont affirmées et sont devenues des puissances nationales et internationales jouant un rôle décisif aussi bien dans l'américanisation des énormes vagues d'immigrants qui sont arrivées dans ce pays, dès la moitié du XIXe siècle, que dans celle des peuples soumis à la domination militaire ou économique des EUA.

Sleep patterns of day-working, evening high-schooled adolescents of São Paulo, Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven São Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14-18 yrs of age who attended school Monday-Friday between 19:00 to 22:30h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F-(1,F-23) = 6.1; p = 0.02] and woke up earlier work days than nonworking students [F-(1,F-23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F-(1,F-23) = 16.7; p < 0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F-(1,F-23) = 10.8; P < 0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays, working girls took the shortest naps [F-(1,F-23) = 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F-(1.23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F-(1,F-23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.

Strong selection against hybrids at a hybrid zone in the Ensatina ring species complex and its evolutionary implications

The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders E. eschscholtzii xanthoptica and E. eschscholtzii platensis hybridize in the central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was resampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (1) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730 m to 2000 m; (2) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over five generations; (3) there were very few if any putative F1s, but a relatively high number of backcrossed individuals in the central portion of transects: and (4) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit showed maximum values near the center of the zones. Using estimates of cline width and dispersal, we infer strong selection against hybrids. This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent selection and reinforces the value of Ensatina as a system for the study of divergence and speciation at multiple stages. © 2005 The Society for the Study of Evolution. All rights reserved.

Measurement of melatonin in body fluids: Standards, protocols and procedures

Background and Purpose: The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6-sulfatoxymelatonin (a6MTs) in urine, is a defining feature of suprachiasmatic nucleus (SCN) function, the body's endogenous oscillatory pacemaker. The primary objective of this review is to ascertain the clinical benefits and limitations of current methodologies employed for detection and quantification of melatonin in biological fluids and tissues. Data Identification: A search of the English-language literature (Medline) and a systematic review of published articles were carried out. Study Selection: Articles that specified both the methodology for quantifying melatonin and indicated the clinical purpose were chosen for inclusion in the review. Data Extraction: The authors critically evaluated the methodological issues associated with various tools and techniques (e.g. standards, protocols, and procedures). Results of Data Synthesis: Melatonin measurements are useful for evaluating problems related to the onset or offset of sleep and for assessing phase delays or advances of rhythms in entrained individuals. They have also become an important tool for psychiatric diagnosis, their use being recommended for phase typing in patients suffering from sleep and mood disorders. Additionally, there has been a continuous interest in the use of melatonin as a marker for neoplasms of the pineal region. Melatonin decreases such as found with aging are or post pinealectomy can cause alterations in the sleep/wake cycle. The development of sensitive and selective methods for the precise detection of melatonin in tissues and fluids has increasingly been shown to have direct relevance for clinical decision making. Conclusions: Due to melatonin's low concentration, as well as the coexistence of numerous other compounds in the blood, the routine determination of melatonin has been an analytical challenge. The available evidence indicates however that these challenges can be overcome and consequently that evaluation of melatonin's presence and activity can be an accessible and useful tool for clinical diagnosis. © Springer-Verlag 2010.

A estética do BijaRi: em busca da permanência

Pós-graduação em Artes - IA

A aventura do risco entre os trabalhadores do corte de cana-de-açúcar

Pós-graduação em Ciências Sociais - FFC

Análise experimental e numérica de convecção forçada em arranjo de obstáculos dentro de canal

Pós-graduação em Engenharia Mecânica - FEIS