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Explaining sleep duration in adolescents: the impact of socio-demographic and lifestyle factors and working status

FISCHER, Frida Marina; NAGAI, Roberta; TEIXEIRA, Liliane Reis
Fonte: New York Publicador: New York
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.42%
Previous studies found students who both work and attend school undergo a partial sleep deprivation that accumulates across the week. The aim of the present study was to obtain information using a questionnaire on a number of variables (e.g., socio-demographics, lifestyle, work timing, and sleep-wake habits) considered to impact on sleep duration of working (n=51) and non-working (n=41) high-school students aged 14-21 yrs old attending evening classes (19:00-22:30 h) at a public school in the city of So Paulo, Brazil. Data were collected for working days and days off. Multiple linear regression analyses were performed to assess the factors associated with sleep duration on weekdays and weekends. Work, sex, age, smoking, consumption of alcohol and caffeine, and physical activity were considered control variables. Significant predictors of sleep duration were: work (p < 0.01), daily work duration (8-10 h/day; p < 0.01), sex (p=0.04), age 18-21 yrs (0.01), smoking (p=0.02) and drinking habits (p=0.03), irregular physical exercise (p < 0.01), ease of falling asleep (p=0.04), and the sleep-wake cycle variables of napping (p < 0.01), nocturnal awakenings (p < 0.01), and mid-sleep regularity (p < 0.01). The results confirm the hypotheses that young students who work and attend school showed a reduction in night-time sleep duration. Sleep deprivation across the week...

Explaining sleep duration in adolescents: The impact of socio-demographic and lifestyle factors and working status

FISCHER, Frida Marina; NAGAI, Roberta; TEIXEIRA, Liliane Reis
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.42%
Previous studies found students who both work and attend school undergo a partial sleep deprivation that accumulates across the week. The aim of the present study was to obtain information using a questionnaire on a number of variables (e.g., socio-demographics, lifestyle, work timing, and sleep-wake habits) considered to impact on sleep duration of working (n = 51) and non-working (n = 41) high-school students aged 14-21 yrs old attending evening classes (19:00-22:30h) at a public school in the city of Sao Paulo, Brazil. Data were collected for working days and days off. Multiple linear regression analyses were performed to assess the factors associated with sleep duration on weekdays and weekends. Work, sex, age, smoking, consumption of alcohol and caffeine, and physical activity were considered control variables. Significant predictors of sleep duration were: work (p < 0.01), daily work duration (8-10h/day; p < 0.01), sex (p = 0.04), age 18-21 yrs (0.01), smoking (p = 0.02) and drinking habits (p = 0.03), irregular physical exercise (p < 0.01), ease of falling asleep (p = 0.04), and the sleep-wake cycle variables of napping (p < 0.01), nocturnal awakenings (p < 0.01), and mid-sleep regularity (p < 0.01). The results confirm the hypotheses that young students who work and attend school showed a reduction in night-time sleep duration. Sleep deprivation across the week...

Tempo, duração e eternidade na filosofia de Espinosa; Time, duration and eternity in Spinozas Philosophy

Itokazu, Ericka Marie
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 12/12/2008 PT
Relevância na Pesquisa
36.34%
Numerosos são os estudos sobre a eternidade na filosofia de Espinosa, contudo, poucas são as pesquisas sobre o tempo e a duração, afinal, por que perguntar-se sobre o tempo numa filosofia da eternidade? Diferentemente dos seus primeiros escritos, na sua obra máxima, a Ética, a singularidade da definição espinosana da eternidade e da duração encontra-se justamente em se restringir à relação entre essência e existência, sem qualquer relação com o tempo. Contudo, acompanhando a gênese dos conceitos de tempo, duração e eternidade, desde os seus primeiros escritos até a Ética, veremos como este deslocamento conceitual revela um duplo movimento: é por desvincular o tempo da duração e da eternidade que a existência ganhará uma profundidade ontológica, ética e política; por outro lado, o tempo ganhará preponderante papel na constituição da imaginação. Nesse duplo movimento, compreenderemos como os conceitos de duração e eternidade, que têm sua terra natal em âmbito ontológico, permitem iluminar outras paisagens, estas sim diretamente vinculadas ao problema da temporalidade: a vida passional e a vida política.; There are numerous studies about the eternity in Spinozas philosophy, however, there are few researches about the time and duration...

The duration of economic expansions and recessions : more than duration dependence

Castro, Vítor
Fonte: Universidade do Minho. Núcleo de Investigação em Políticas Económicas Publicador: Universidade do Minho. Núcleo de Investigação em Políticas Económicas
Tipo: Trabalho em Andamento
Publicado em /05/2008 ENG
Relevância na Pesquisa
36.43%
One widespread idea in the business cycles literature is taht the older is an expansion or contraction, the more likely it is to end. This paper tries to provide further empirical support for this idea of positive duration dependence and, at the same time, control for the effects of other factors like leading indicators, the duration of the previous phase, investment, price of oil and external influences on the duration of expansions and contractions. This study employs a discrete-time duration model to analyse the impact of those variables on the likelihood of an expansion and contraction ending for a group of industrial countries over the last fifty years. The evidence provided in this paper suggests that the duration of expansions and contractions is not only dependent on their actual age: the duration of expansions is also positively dependent on the behaviour of the variables in the OECD composite leading indicator and on private investment, and negatively affected by the price of oil and by the occurence of a peak in the US business cycle; the duration of a contraction is negatively affected by its actual age and by the duration of the previous expansion.; NIPE – Núcleo de Investigação em Políticas Económicas – is supported by the Portuguese Foundation for Science and Technology through the Programa Operacional Ciência e Inovação 2010 (POCI 2010) of the III Quadro Comunitário de Apoio (QCA III)...

The duration of business cycle expansions and contractions : are there change-points in duration dependence?

Castro, Vítor
Fonte: Universidade do Minho. Núcleo de Investigação em Políticas Económicas (NIPE) Publicador: Universidade do Minho. Núcleo de Investigação em Políticas Económicas (NIPE)
Tipo: Trabalho em Andamento
Publicado em //2010 ENG
Relevância na Pesquisa
36.46%
The issue of whether the likelihood of an expansion or contraction ending is dependent on its age, i.e whether they are duration dependent, is widely addressed in the business cycles literature and evidence of positive duration dependence is found in several studies. However, there is an important issue that has not been explored in this literature yet: the presence of change-points in duration dependence. All the studies in this field depart from the assumption that the magnitude of duration dependence is the same over time. However, we conjecture that the degree of likeliness of an expansion or contraction ending as it gets older might change after a specific duration. To test for that possibility, this paper will allow for the presence of a change-point in the analysis of the duration of expansions and contractions for a group of 13 European and Non-European industrial countries over the period 1948-2009. The evidence provided by the estimation of a continuous-time Weibull duration model shows strong support for the presence of positive duration dependence, which is stronger for contractions than for expansions. Results also show that contractions have become longer over time and that their length is negatively a¤ected by the length of the previous expansion. Most importantly...

Duration dependence and change-points in the likelihood of credit booms ending

Castro, Vítor; Kubota, Megumi
Fonte: Universidade do Minho. Núcleo de Investigação em Políticas Económicas (NIPE) Publicador: Universidade do Minho. Núcleo de Investigação em Políticas Económicas (NIPE)
Tipo: Trabalho em Andamento
Publicado em //2013 ENG
Relevância na Pesquisa
36.4%
Whether the likelihood of credit booms ending is dependent on its age or not, or whether the respective behaviour is smooth or bumpy are important issues to which the economic literature has not given attention yet. This paper tries to fill that gap in the literature, exploring those issues with a proper duration analysis. Credit booms are identified considering two criteria well established in the literature: (i) the Mendoza-Terrones criteria; (ii) and the Gourinchas-Valdes-Landarretche criteria. A continuous-time Weibull duration model is employed over a group of 71 countries for the period 1975q1-2010q4 to investigate whether credit booms are duration dependent or not. Our findings show that the likelihood of credit booms ending increases over its duration and that these events have become longer over the last decades. Additionally, we extend the baseline Weibull duration model in order to allow for change-points in the duration dependence parameter. The empirical findings support the presence of a change-point: increasing positive duration dependence is observed in booms that last less than eight to ten quarters, but it becomes decreasing or even irrelevant for longer events. Analogous results are found for those credit boom episodes that are followed by systemic banking crisis (bad credit booms). Our findings also show that credit booms are...

Sleep duration and plasma leptin concentrations in early pregnancy among lean and overweight/obese women: a cross sectional study

Qiu, Chunfang; Frederick, Ihunnaya O; Sorensen, Tanya K; Enquobahrie, Daniel A; Williams, Michelle A
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.44%
Background: Early-pregnancy short sleep duration is predictive of gestational diabetes and preeclampsia; mechanisms for these associations are unknown. Leptin, an adipocyte-derived peptide involved in regulating food intake and energy expenditure, may play a role in these observed associations. Given inconsistent reports linking short sleep duration with leptin, and absence of studies among pregnant women, we examined the association of maternal sleep duration with plasma leptin in early pregnancy. Methods: This cross-sectional study included 830 pregnant women. Plasma leptin was measured in samples collected around 13 weeks gestation. Sleep duration was categorized as: ≤5, 6, 7–8 (reference), and ≥9 hours. Differences in leptin concentrations across categories were estimated using linear regression. Analyses were completed for lean and overweight/obese women. Results: Overall, women with long sleep duration had elevated plasma leptin (p-value = 0.04). However, leptin concentrations were not statistically significantly elevated in women with a short sleep duration. There was no association of leptin with sleep duration among lean women. Among overweight/obese women, a U-shaped relation between leptin and sleep duration was observed: Mean leptin was elevated (β = 21.96 ng/ml...

Sleep duration, vital exhaustion, and odds of spontaneous preterm birth: a case–control study

Kajeepeta, Sandhya; Sanchez, Sixto E; Gelaye, Bizu; Qiu, Chunfang; Barrios, Yasmin V; Enquobahrie, Daniel A; Williams, Michelle A
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.34%
Background: Preterm birth is a leading cause of perinatal morbidity and mortality worldwide, resulting in a pressing need to identify risk factors leading to effective interventions. Limited evidence suggests potential relationships between maternal sleep or vital exhaustion and preterm birth, yet the literature is generally inconclusive. Methods: We examined the relationship between maternal sleep duration and vital exhaustion in the first six months of pregnancy and spontaneous (non-medically indicated) preterm birth among 479 Peruvian women who delivered a preterm singleton infant (<37 weeks gestation) and 480 term controls who delivered a singleton infant at term (≥37 weeks gestation). Maternal nightly sleep and reports of vital exhaustion were ascertained through in-person interviews. Spontaneous preterm birth cases were further categorized as those following either spontaneous preterm labor or preterm premature rupture of membranes. In addition, cases were categorized as very (<32 weeks), moderate (32–33 weeks), and late (34- <37 weeks) preterm birth for additional analyses. Logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Results: After adjusting for confounders, we found that short sleep duration (≤6 hours) was significantly associated with preterm birth (aOR = 1.56; 95% CI 1.11-2.19) compared to 7–8 hours of sleep. Vital exhaustion was also associated with increased odds of preterm birth (aOR = 2.41; 95% CI 1.79-3.23) compared to no exhaustion (Ptrend <0.001). These associations remained significant for spontaneous preterm labor and preterm premature rupture of membranes. We also found evidence of joint effects of sleep duration and vital exhaustion on the odds of spontaneous preterm birth. Conclusions: The results of this case–control study suggest maternal sleep duration...

Influence of equine chorionic gonadotropin on weaning-to-estrus interval and estrus duration In Early-Weaned Primiparous Female Swine

Lucia Junior, Thomaz; Corr??a, Marcio Nunes; Deschamps, Jo??o Carlos; Peruzzo, Ivan A.; Matheus, Jairo E. M.; Aleixo, Jos?? A. G.
Fonte: Universidade Federal de Pelotas Publicador: Universidade Federal de Pelotas
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.4%
The weaning-to-estrus interval (WEI) influences the total nonproductive days (NPD) accumulated by the breeding herd and affects herd productivity. Short lactation lengths (LL) are commonly followed by prolonged WEI, which are also associated with short estrus duration (ED). Equine chorionic gonadotropin treatment is a tool that has been used to reduce WEI, especially for low-parity females. The objectives for this study were to evaluate the effect of LL on the association between WEI and ED and to estimate the effects of postweaning eCG administration on WEI and ED for early-weaned females. Two treatments (TREAT) consisting of 750 IU of eCG (n = 96) or control (n = 77) were applied 1 d after weaning to first-parity, weaned females. The study was conducted on a commercial farm having a target LL of 18 d. Estrus detection was conducted three times daily, and estrus duration was determined as the interval between the first and the last positive response to back pressure. Analyses of variance were conducted to estimate the effects of LL andTREAT on WEI and the effects of TREAT and WEI on estrus duration. Mean LL was 17.9 ?? 1.7 d, mean WEI was 106.6 ?? 29.2 h, and mean estrus duration was 55.9 ?? 15.5 h. Even though the frequency of short WEI tended to increase with longer LL...

Duration Dependence and Change-Points in the Likelihood of Credit Booms Ending

Castro, Vitor; Kubota, Megumi
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.4%
Whether the likelihood of a credit boom ending is dependent on its age or not, or whether the respective behavior is smooth or bumpy are important issues to which the economic literature has not given attention yet. This paper tries to fill that gap, exploring those issues with a proper duration analysis. Credit booms are identified considering two criteria well established in the literature: (i) the Mendoza-Terrones criteria and (ii) and the Gourinchas-Valdes-Landarretche criteria. A continuous-time Weibull duration model is employed over a group of 71 countries for the period 1975q1-2010q4 to investigate whether credit booms are duration dependent or not. The findings show that the likelihood of credit booms ending increases over their duration and that these events have become longer over the past decades. In addition, the paper extends the baseline Weibull duration model in order to allow for change-points in the duration dependence parameter. The empirical findings support the presence of a change-point: increasing positive duration dependence is observed in booms that last less than eight to ten quarters...

Duration of sexual relationship and its effect on preeclampsia and small for gestational age perinatal outcome

Kho, E.; McCowan, L.; North, R.; Roberts, C.; Chan, E.; Black, M.; Taylor, R.; Dekker, G.
Fonte: Elsevier Sci Ireland Ltd Publicador: Elsevier Sci Ireland Ltd
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
36.37%
The aim of this study was to determine if women with preeclampsia or delivering small for gestational age (SGA) babies are more likely to have a short duration of sexual relationship compared with those who have uncomplicated pregnancies. In a prospective cohort study, 2507 nulliparous women with singleton pregnancies were interviewed at 15+/-1 weeks gestation about the duration of their sexual relationship with the biological father. Short duration of sexual relationship (< or =6 months, < or =3 months, or first intercourse) was compared between women with preeclampsia (N=131) or SGA babies (N=263) and those with uncomplicated pregnancies (N=1462). Short duration of sexual relationship was more common in women with preeclampsia compared with uncomplicated pregnancies (< or =6 months 14.5% versus 6.9%, adjusted odds ratio [adjOR] 1.88, 95% CI 1.05-3.36; < or =3 months 6.9% versus 2.5%, adjOR 2.32, 95% CI 1.03-5.25; first intercourse 1.5% versus 0.5%, adjOR 5.75, 95% CI 1.13-29.3). Although the total number of semen exposures was lower in SGA, SGA was not associated with a shorter duration of sexual relationship. On post hoc analysis, the subgroup of SGA with abnormal uterine artery Doppler at 20 weeks (N=58) were more likely to have had a short sexual relationship compared with controls (< or =6 months adjOR 2.33...

Interaction between physical activity and sleep duration in relation to insulin resistance among non-diabetic Chinese adults

Zuo, H.; Shi, Z.; Yuan, B.; Dai, Y.; Hu, G.; Wu, G.; Hussain, A.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.37%
It is of a public health interest to explore the relationship between different types of physical activity, sleep duration and diabetes/insulin resistance. However, little is known about such relationship. This study examines the single and joint associations of different types of physical activity, and sleep duration on insulin resistance among non-diabetic Chinese adults. Methods: Data was collected from 1124 non-diabetic adults in Jiangsu Province from the China Health and Nutrition Survey (CHNS). Domestic, occupational, transportation and leisure physical activity were assessed in terms of metabolic equivalent (MET)-hours-per-week to account for both intensity and time spent. Sleep duration was categorized into three groups: ≤ 7 hours, 7-9 hours, and ≥ 9 hours. Insulin resistance was evaluated by the homeostasis model of assessment (HOMA) and defined as the highest quartile of HOMA. Results: Total physical activity was mainly composed of occupational activity (75.1%), followed orderly by domestic, transportation and leisure time activity in both men and women. Total physical activity level was strongly negatively associated with fasting insulin and HOMA (p < 0.001). Among four types of physical activity, occupational activity was significantly negatively associated with HOMA after full adjustment (p < 0.05). Transportation activity was also negatively associated with HOMA when adjusted for age and gender (p = 0.028). Moreover...

Does duration of hysteroscopy increase the risk of disease recurrence in patients with endometrial cancer? A multi-centre trial

Tempfer, C.; Froese, G.; Buerkle, B.; Polterauer, S.; Grimm, C.; Concin, N.; Hofstetter, G.; Weigert, M.; Oehler, M.K.
Fonte: SPANDIDOS PUBL LTD Publicador: SPANDIDOS PUBL LTD
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
36.4%
Women with endometrial cancer often undergo hysteroscopy during their diagnostic work-up. Whether or not the duration of hysteroscopy affects the rate of positive peritoneal cells and the duration of recurrence-free survival is unknown. In a retrospective multi-centre study, the records of 552 patients with endometrial cancer were investigated. Duration of hysteroscopy was correlated with clinicopathological parameters and patient survival data. The mean [standard deviation (SD)] duration of hysteroscopy was 18.2 (10.5) min in the study population and 17.9 (10.1) min and 17.9 (10.2) min in patients with positive (n=109) and negative peritoneal cytology (n=443), respectively (p=0.9). There were no statistically significant correlations between duration of hysteroscopy and positive peritoneal cytology (p=0.6; rho=−0.028), FIGO stage (p=0.2; rho=−0.080), lymph node involvement (p=0.2; rho=0.106) and patient age (p=0.5; rho=0.033). Longer duration of hysteroscopy (>15 min) was not associated with positive peritoneal cytology (yes vs. no, p=0.8), advanced tumour stage (FIGO I vs. II, III and IV, p=0.3), lymph node involvement (yes vs. no, p=0.1) and patient age (≤65 vs. >65 years, p=0.4). In a multivariate analysis, FIGO stage [p<0.0001; hazard ratio (HR)=5.1...

NDVI and vegetation phenology dynamics under the influence of sunshine duration on the Tibetan plateau

Wang, Hongshuo; Liu, Desheng; Lin, Hui; Montenegro, Alvaro; Zhu, Xiaolin
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 687-698
ENG
Relevância na Pesquisa
36.37%
Climate change has significantly influenced vegetation dynamics on the Tibetan Plateau (TP). Past research mainly focused on vegetation responses to temperature variation and water stress, but the influence of sunshine duration on NDVI and vegetation phenology on the TP is not well understood. In this study, NDVI time series from 1982-2008 were used to retrieve spatiotemporal vegetation dynamics on the TP. Empirical orthogonal function (EOF) analysis was conducted to understand the spatiotemporal variations of NDVI. The Start of Season (SOS) was estimated from NDVI time series with a local threshold method. The first EOF, accounting for 35.1% of NDVI variations on the TP, indicates that NDVI variations are larger in areas with shorter sunshine duration. The needle-leaved forest and shrub in the southeastern TP are more sensitive to sunshine duration anomalies (p < 0.01) than broad-leaved forest, steppe, and meadow due to spatial and altitudinal distribution of sunshine duration and vegetation types. The decrease in sunshine duration for the growing season on the TP has resulted in a decreased NDVI trend in some areas of southeastern TP (p ranging from 0.32-0.05 with threshold ranging from 0.05 to 0.25) in spite of the overall NDVI increase. SOS dynamics in most parts of the TP were mainly related to temperature variability...

External Interventions and the Duration of Civil Wars

Elbadawi, Ibrahim A.; Sambanis, Nicholas
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
36.39%
The authors combine an empirical model of external intervention, with a theoretical model of civil war duration. Their empirical model of intervention allows them to analyze civil war duration, using "expected" rather than "actual" external intervention as an explanatory variable in the duration model. Unlike previous studies, they find that external intervention is positively associated with the duration of civil war. They distinguish partial third-party interventions that extend the length of war, from multilateral "peace" operations, which have a mandate to restore peace without taking sides - and which typically take place at war's end, or at least when both sides have agreed to a cease-fire. In a future paper, the authors will examine whether partial third-party interventions - whatever their effect on a war's duration - increase the risk of war's recurrence. If that proves true, then even if interventions reduce the length of civil war, they may do so at the cost of further destabilizing the political system...

Does in-hospital breastfeeding self-efficacy predict breastfeeding duration?

POON, KAREN KIT YING
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.37%
Background: Health Canada recommends exclusive breastfeeding for the first 6 months postpartum with continued breastfeeding up to 2 years and beyond. While 88% of Canadian mothers initiate breastfeeding, only 70% of mothers continue to do so at 4 weeks postpartum and only 14% are exclusively breastfeeding at 6 months. Breastfeeding self-efficacy is a potentially modifiable variable that has been associated with mothers’ breastfeeding practices. The Breastfeeding Self-Efficacy Scale (Short-Form) is an instrument that could potentially identify women with low breastfeeding self-efficacy during the in hospital period. Purpose: To describe the breastfeeding practices of new mothers in the Kingston, Frontenac and Lennox & Addington area and to assess the association between in-hospital scores on the Breastfeeding Self-Efficacy Scale (Short-Form) and duration of breastfeeding. Methods: This study was a secondary analysis of a dataset from the 2008 Infant Feeding Survey, a prospective study of 463 mothers with 12-month longitudinal follow-up. Data were weighted according to the maternal age distribution of the general population of new mothers. Breastfeeding practices were described using Kaplan-Meier survival distributions. Four outcomes were described: ‘exclusive breastfeeding from birth’...

Speech rhythm: the language-specific integration of pitch and duration

Cumming, Ruth Elizabeth
Fonte: University of Cambridge; Department of Linguistics Publicador: University of Cambridge; Department of Linguistics
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.39%
Experimental phonetic research on speech rhythm seems to have reached an impasse. Recently, this research field has tended to investigate produced (rather than perceived) rhythm, focussing on timing, i.e. duration as an acoustic cue, and has not considered that rhythm perception might be influenced by native language. Yet evidence from other areas of phonetics, and other disciplines, suggests that an investigation of rhythm is needed which (i) focuses on listeners? perception, (ii) acknowledges the role of several acoustic cues, and (iii) explores whether the relative significance of these cues differs between languages. This thesis, the originality of which derives from its adoption of these three perspectives combined, indicates new directions for progress. A series of perceptual experiments investigated the interaction of duration and f0 as perceptual cues to prosody in languages with different prosodic structures ? Swiss German, Swiss French, and French (i.e. from France). The first experiment demonstrated that a dynamic f0 increases perceived syllable duration in contextually isolated pairs of monosyllables, for all three language groups. The second experiment found that dynamic f0 and increased duration interact as cues to rhythmic groups in series of monosyllabic digits and letters; the two cues were significantly more effective than one when heard simultaneously...

The Derivation of a New Model of Equity Duration

Lewin, R. A.; Satchell, Stephen E.
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Trabalho em Andamento Formato: 260323 bytes; application/pdf; application/pdf
EN_GB
Relevância na Pesquisa
36.4%
This paper sets out to address the issue of equity duration, one of several risk measures available for asset and liability management. Equity duration, as derived from the use of traditional dividend discount models, results in extremely long duration estimated for equities - often in excess of 50 years for growth stocks. Leibowitz, in his seminal paper (1986), identified an alternative framework for assessing equity duration empirically. This methodology yields equity duration measures more consistent with the experience of practitioners, implying that equities behave as if they are much shorter duration instruments. In our paper, based on an application to UK data, we develop the intuition behind the Leibowitz approach to generate equity duration as a by-product of asset pricing, Our analysis suggests that the equity premium puzzle may comprise an important element in reconciling the Leibowitz approach to equity duration, with the more traditional dividend discount model alternative.

Minimum Duration of Reactivation at 3 Months of Age

Joh, AS; Sweeney, B; Rovee-Collier, C
Fonte: John Wiley & Sons, Inc Publicador: John Wiley & Sons, Inc
Tipo: Artigo de Revista Científica Formato: 23 - 32
Publicado em 01/01/2002
Relevância na Pesquisa
36.37%
Brie ̄y exposing subjects to an isolated component of an event after they have forgotten can reactivate their memory of it, leading to renewed retention on an ensuing test. In two experiments with forty-eight 3-month-old infants, we asked what minimum duration of a reactivation treatment could recover their forgotten memory of an operant mobile task and whether the mini- mum duration was affected by how long the memory was forgotten. In Experiment 1, the minimum duration for reactivating the memory 1 week after forgetting was 120 sÐsubstantially longer than the minimum duration required for reactivation at 6 months after the same relative delay. In Experiment 2, the minimum effective duration for reactivation increased linearly with the time since forgetting, from 7.5 s after 1 day to 180 s after 3 weeks. This study reveals that the duration of an effective memory prime is directly related to age and to memory accessibility.

Neural estimation of strong ground motion duration

Alcántara Nolasco,Leonardo; García,Silvia; Ovando-Shelley,Efraín; Macías Castillo,Marco Antonio
Fonte: Instituto de Geofísica, UNAM Publicador: Instituto de Geofísica, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2014 EN
Relevância na Pesquisa
36.39%
This paper presents and discusses the use of neural networks to determine strong ground motion duration. Accelerometric data recorded in the Mexican cities of Puebla and Oaxaca are used to develop a neural model that predicts this duration in terms of the magnitude, epicenter distance, focal depth, soil characterization and azimuth. According to the above the neural model considers the effect of the seismogenic zone and the contribution of soil type to the duration of strong ground motion. The final scheme permits a direct estimation of the duration since it requires easy-to-obtain variables and does not have restrictive hypothesis. The results presented in this paper indicate that the soft computing alternative, via the neural model, is a reliable recording-based approach to explore and to quantify the effect of seismic and site conditions on duration estimation. An essential and significant aspect of this new model is that, while being extremely simple, it also provides estimates of strong ground motions duration with remarkable accuracy. Additional but important side benefits arising from the model's simplicity are the natural separation of source, path, and site effects and the accompanying computational efficiency.