Nocturnal Hours Research Articles

Study of Hourly Variability of Association between Land Use Parameters and CO-Pollutant Using LUR Model in Tehran

The models of the association between land use and air pollution have wide applications in urban studies, but the land-use role and its different parameters effective on the variability of air pollution concentration in various hours can be used for more accurate Spatio-temporal prediction of pollution. In this study, to make Spatio-temporal prediction of CO pollutants using hourly land-use regression (LUR), the effective parameters on Spatio-temporal variation of this pollutant are investigated during the day and night. The hourly data are collected from 21 air pollution monitoring stations for the summer in Tehran and the predictive parameters including density and distance from different variables such as road network, vegetation, elevation, and different land-use are generated in the geographic information system (GIS). A general model and 8 hourly models are created at 3 am, 6 am, 9 am, 12 noon, 3 pm, 6 pm and 12 midnight. The coefficient of determination (R2) of the created model is equal to 0.7898, and it shows that the model has an outstanding performance. By analyzing the generated hourly models, because of the differences in the parameters used in these models, it is denoted that both temporal variability and spatial variability play effective roles in forming the models during the day and night. The coefficient of determination (R2) of the hourly models ranges from 0.51 to 0.92 in which the lowest one and the highest one are related to the noon hours’ models and the nocturnal hours’ models, respectively. The parameters including local access roads and official/commercial areas have the most effect on increasing CO pollutants during the day and night, and the parameters including green space, sports, and medical centers lead to the locations with lower CO pollutants concentration.

Glycemic responses to strenuous training in male professional cyclists with type 1 diabetes: a prospective observational study

IntroductionThis prospective observational study sought to establish the glycemic, physiological and dietary demands of strenuous exercise training as part of a 9-day performance camp in a professional cycling team with...

Observed Warm‐Season Characteristics of MCS and Non‐MCS Rainfall and Their Recent Changes in the Central United States

AbstractWarm‐season rainfall characteristics in the central United States are investigated as they play important roles in ecohydrology and agricultural productivity. Using rainfall observations, we compare the April–August mesoscale convective systems (MCS) and non‐MCS rainfall characteristics and examine their linear trends between 1997 and 2018. MCS rainfall is found to be approximately seven times more intense than non‐MCS rainfall but it occurs less frequently in time and space. MCS rainfall peaks in nocturnal hours, with synchronized timing of rainfall intensity, area, and occurrence, while non‐MCS rainfall peaks in late‐afternoon hours, mostly attributed to the timing of peak rainfall area. MCS rainfall has increased in the last 22 years due to an increase in frequency and a longer duration per MCS. In contrast, non‐MCS rainfall has decreased mainly due to a reduction in rainfall area, leading to fewer total wet days and increased dry intervals between events.

Abstract WP278: Air versus Ground Transportation During Inter-Hospital Transfer of Patients for Endovascular Thrombectomy Evaluation

Introduction: Mode of transport utilized during inter-hospital transfers can influence delays in patients with suspected large vessel occlusion (LVO). We hypothesized that air transport is advantageous over ground in this patient population. Method: Suspected LVO patients transferred to our hub from 13 spoke hospitals within our tele-stroke network at UT-Houston, from September 2015 to April 2018 were retrospectively analyzed. Patients were dichotomized into air vs. ground transport. Travel time was calculated as time from transfer center activation to arrival at hub. For each spoke, average air miles/hour and ground miles/hour indices were calculated for comparison. Air transport was considered advantageous if the difference in indices was positive. Results were stratified by time of the day [diurnal (6a-6p) vs. nocturnal (6p-6a)]. Results: In a total of 339 patients, 290 (86%) used air transport, while 49 (14%) used ground. Baseline age, gender, race, use of IV-tPA, mRS in the 2 groups were similar, except air group had higher NIHSS [median 15 vs. 12, p = 0.048]. Overall, mean ground indices were smaller compared to air indices (21.35 ± 10.76 vs. 25.77 ± 14.33, p = 0.006). The advantage of air transport was maintained when stratified by time of the day but more notable during nocturnal hours [air 25.12 ± 14.93 vs. ground 19.85 ± 10.14, p = 0.021)] compared to diurnal hours [(air 28.82 ± 13.68 vs. ground 25.00 ± 10.80, p = 0.17)]. Difference between air and ground indices (y axis) was positively correlated with ground distance (x axis) (Pearson rho = 0.80, 95% CI 0.42 to 0.93, p<0.001) indicating efficiency of air transport becomes more profound as distance increases (Figure 1). Ground transport was faster for distances <20 miles. Conclusion: Irrespective of time of the day, air transport is faster mode of transporting patients during inter hospital transfers and should be utilized particularly for spokes situated farther away (over 20 miles) from hub and during nocturnal hours.

Cardiovascular risk assessment by electrocardiographic Holter monitoring in patients with chronic hepatitis C.

IntroductionCardiovascular diseases are ranked as the third cause of mortality among people infected with hepatitis C virus (HCV), but the relationship of infection with cardiovascular risk remains disputable. We have focused on the comprehensive use of parameters obtainable during long-term electrocardiographic (ECG) Holter monitoring.Material and methodsHeart rate variability and turbulence (HRV and HRT), deceleration/acceleration capacity (DC/AC), corrected QT interval (QTc) and late potential (LP) were used. 36 persons were included, and 30 healthy subjects formed a control group. All were submitted to 24-hour Holter ECG-monitoring.ResultsThe studied groups were not statistically significantly different with regards to basic anthropometric parameters. Statistically significantly higher medium and maximum heart rhythm and aminotransferase activities were recorded in patients with hepatitis C. The HRV parameters r-MSSD, p50NN, HF, and absolute DC/AC values were significantly lower in the subjects with hepatitis C than those in the control group. The QTc interval, measured for nocturnal hours, was also significantly longer in that group. There were no differences in the albumin level or basic echocardiographic parameters, including left ventricle ejection fraction. Nor was there any difference in the HRT parameters, or LP. The most interesting observation was the positive correlation among the number of viral RNA copies and DC, and LF.ConclusionsWe confirmed the presence of autonomic disorders with prevalence of sympathetic system activity and prolonged QTc interval in patients with chronic hepatitis C. Those parameters significantly correlated with infection intensity. Our results suggest that HCV infection could be an independent cardiovascular risk factor, not associated with the lipid profile. Further prospective studies are needed.

Effect of urinary sodium-to-potassium ratio change on blood pressure in participants of the longitudinal health of adults study - ELSA-Brasil.

To assess the effect of changing the sodium to potassium (Na/K) ratio on blood pressure at 4 years of follow-up.The measurements were carried out under identical conditions in two study periods (2008–2010 and 2012–2014). Urinary excretion of sodium and potassium (mmol/L) over 12 nocturnal hours was used to calculate the Na/K ratio and categorized by quintile. The 24-hour sodium and potassium intake was estimated using a validated equation. The mean BP was calculated from 3 measurements after 5 minutes of rest. Of the 15,105 participants at baseline, 14,014 completed the first follow-up. Participants without validated urine collection (n = 5,041), using antihypertensive medication (n = 3,860) at either time points or reporting bariatric surgery during follow-up (n = 45) were excluded. The differences between follow-up and baseline values were calculated for BP and the Na/K ratio. Analyses were stratified by sex and adjusted for confounding variables.Sodium intake did not change from baseline, but potassium intake increased by approximately 150 mg in both sexes (P < .001), with a consequent reduction of the Na/K ratio. The highest quintile of change in the Na/K ratio was associated with greater variation in BP. When adjusted for covariates, it is possible to observe an increase in SBP in women from the third quintile of the Na/K ratio, in men this increase was observed from the fourth quintile. However, for DBP this increase is observed from the third quintile in both men and women.Increase in SBP was observed in women from the third quintile of the Na/K ratio, in men this increase is observed from the fourth quintile. However, for DBP this increase is observed from the third quintile in both men and women. The Na/K ratio demonstrated a greater association in BP.

Study on the wintry thermal improvement of makeshift shelters built after Nepal earthquake 2015

After massive earthquake 2015, thousands of Nepalese who lost their permanent houses by the hardest hits were forced to live in makeshift temporary shelters. The field measurement on indoor thermal environment in five shelters was conducted in one of the district hit by the earthquake, Lalitpur, in winter. The mean indoor and outdoor air temperatures during the measured nighttime were found to be 10.3 °C and 7.6 °C, respectively, and the nocturnal indoor air temperature remained below the lowest acceptable temperature of 11 °C. This result assured that these shelters are not good for winter and must create various problems. We therefore analyzed the thermal characteristics of those shelters based on the measured results in order to seek a possible improvement. The total heat loss coefficient estimated per floor area in five shelters ranged from 11.3 to 15.2 W/(m2·K); that is thermal insulation was very low. We made a simple numerical analysis on the variation of indoor air temperature with the assumption of improved thermal characteristics and thereby found that it needs to be reduced about 2∼7 W/(m2·K) to have the indoor air temperature higher than 11 °C for 70% of the whole nocturnal hours. Such reduction of heat loss was found to be realized by adding affordable materials, e.g., cellular polyethylene foam and clothes for respective walls and roof. Thus, the knowledge obtained from this study should hopefully be applied to actual improvement of indoor thermal environment in existing shelters and also to a development for the preparation against future disaster.

Examination of the Predictability of Nocturnal Tornado Events in the Southeastern United States

Abstract Tornadoes that occur at night pose particularly dangerous societal risks, and these risks are amplified across the southeastern United States. The purpose of this study is to highlight some of the characteristics distinguishing the convective environment accompanying these events. This is accomplished by building upon previous research that assesses the predictive power of meteorological parameters. In particular, this study uses the Statistical Severe Convective Risk Assessment Model (SSCRAM) to determine how well convective parameters explain tornado potential across the Southeast during the months of November–May and during the 0300–1200 UTC (nocturnal) time frame. This study compares conditional tornado probabilities across the Southeast during November–May nocturnal hours to those probabilities for all other November–May environments across the contiguous United States. This study shows that effective bulk shear, effective storm-relative helicity, and effective-layer significant tornado parameter yield the strongest predictability for the November–May nocturnal Southeast regime among investigated parameters. This study demonstrates that November–May southeastern U.S. nocturnal predictability is generally similar to that within other regimes across the contiguous United States. However, selected ranges of multiple parameters are associated with slightly better predictability for the nocturnal Southeast regime. Additionally, this study assesses conditional November–May nocturnal tornado probabilities across a coastal domain embedded within the Southeast. Nocturnal coastal tornado predictability is shown to generally be lower than the other regimes. All of the differences highlight several forecast challenges, which this study analyzes in detail.

Temporal pattern of adult emergence and sexual behavior of Scopula subpunctaria (Lepidoptera: Geometridae)

The objective of this research was to study the reproductive behavior (emergence, calling, mating and oviposition) of Scopula subpunctaria (Lepidoptera: Geometridae) under laboratory conditions (26 ± 1 °C, 12 h photophase and 75 ± 1% RH). The emergence occurred during the scotophase and photophase, but mainly during the scotophase. Females and males simultaneously emerged during the 1st to 12th h of scotophase. However, the calling and mating behavior were limited to nocturnal hours. Adults were engaged in sexual activity (calling) as soon as one day after emergence. Virgin females began calling actively at 2.5 h–3 h into the scotophase, and with a peak occurring at 7.5 h of the scotophase. The maximum number of mating occurred when the couple was 2-d-old, the longest mating duration occurred when the couple was 5-d-old (230 ± 20.2 min), and the mating peak occurred from 6 h to 8 h of scotophase. The males could mate twice and females only mate once. Oviposition behavior also occurred during the scotophase. Females laid eggs from the first day after mating until the eighth day, with a peak occurring at the second day (111 ± 5.6). The emergence, calling, mating and oviposition patterns of S. subpunctaria are discussed and future research is outlined. New technology is currently available for the control of this pest, possibly involving the use of pheromones for trapping or disrupting the mating cycle of the insect.

Classification and Diurnal Variations of Precipitation Echoes Observed by a C-band Vertically-Pointing Radar in Central Tibetan Plateau during TIPEX-III 2014-IOP

This study investigates classification and diurnal variations of the precipitation echoes over the central Tibetan Plateau based on the observations collected from a C-band vertically-pointing frequency-modulated continuous-wave (C-FMCW) radar during the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX-III) 2014-Intensive Observation Period (2014-IOP). The results show that 51.32% of the vertical profiles have valid echoes with reflectivity > –10 dBZ, and 35.06% of the valid echo profiles produce precipitation at the ground (precipitation profiles); stratiform precipitation with an evident bright-band signature, weak convective precipitation, and strong convective precipitation account for 52.03%, 42.98%, and 4.99% of the precipitation profiles, respectively. About 59.84% of the precipitation occurs in the afternoon to midnight, while 40.16% of the precipitation with weaker intensity is observed in the nocturnal hours and in the morning. Diurnal variation of occurrence frequency of precipitation shows a major peak during 2100–2200 LST (local solar time) with 59.02% being the stratiform precipitation; the secondary peak appears during 1300–1400 LST with 59.71% being the weak convective precipitation; the strong convective precipitation occurs mostly (81.83%) in the afternoon and evening with two peaks over 1200–1300 and 1700–1800 LST, respectively. Starting from approximately 1100 LST, precipitation echoes develop with enhanced vertical air motion, elevated echo top, and increasing radar reflectivity. Intense upward air motion occurs most frequently in 1700–1800 LST with a secondary peak in 1100–1400 LST, while the tops of precipitation echoes and intense upward air motion reach their highest levels during 1600–1800 LST. The atmospheric conditions in the early morning are disadvantageous for convective initiation and development. Around noon, the convective available potential energy (CAPE) increases markedly, convective inhibition (CIN) is generally small, and a super-dry-adiabatic layer is present near the surface (0–400 m). In the early evening, some larger values of CAPE, level of neutral buoyancy, and total precipitable water are present, suggesting more favorable thermodynamic and water vapor conditions.

Activity Patterns by Feral Hogs in the Texas Panhandle

The state of Texas has the highest population of feral hogs, Sus scrofa, than any state in the U.S.A. The expanding abundance and distribution of feral hogs throughout North America is testimony to their ability to adapt to differing environmental and habitat conditions. We evaluated movements and activity of 18 feral hogs fitted with Global Positioning System (GPS) collars between March 2015 through July 2017 in the Texas Panhandle, U.S.A., following three toxicant field studies. We investigated movements of feral hogs in response to individual, weather, and environmental variables using generalized linear mixed models. Nocturnal and diurnal 3 h movements were 753.8 ± 14.28 m and 277.45 ± 8.04 m for all hogs, respectively. Overall mean distance (± se) traveled by feral hogs was 3666.9 ± 64.7 m per day (range: 7.9 to 12985.33 m). Daily distance by males and females averaged 3903.6 ± 112.05 m and 3546.1 ± 78.88 m, respectively, and were not found to be significantly different between sexes. Behavior of feral hogs showed a unimodal pattern, peaking during nocturnal hours. Time of day, land cover type, and temperature were important explanatory variables driving 3 h movements. Sex, temperature, and previous day precipitation were important explanatory variables driving daily distances. Predicting what drives hog movement (e.g., individual and external factors) can allow managers to identify when and where to locate individuals for control efforts, possibly preventing initial invasions by feral hogs.

Numerical investigation of a solar air heater comprising longitudinally finned absorber plate and thermal energy storage system

In the present work, the thermal performance of a double glazed single pass solar air heater consisting of a longitudinally finned absorber plate on its top surface and attached to a phase change material (PCM) with its bottom surface is investigated, theoretically. Paraffin wax (Rubitherm RT42) is used as a PCM. The main idea of this solar air heater design is to use it during nocturnal hours or off sunshine hours. A computational heat transfer and fluid dynamics solution using an implicit scheme has been developed and employed to study the effects of the mass flow rate and number of fins on its thermal performance under transient conditions. The maximum outlet air temperature of the finned type solar air heater with latent heat storage is achieved as 40 °C, 37 °C, and 35 °C for mass flow rates of 0.01, 0.015, and 0.02 kg/s, respectively, and it is predicted that the system can be used for 14, 12, and 10 h after sunset at respective mass flow rates. The maximum daily average thermal efficiency is predicted to be 62.4% at a mass flow rate of 0.02 kg/s which is higher than the other designs considered in the present investigation.

Blood-pressure variability in patients with obstructive sleep apnea: current perspectives.

Obstructive sleep apnea (OSA) is often associated with hypertension and other cardiovascular diseases. Blood pressure (BP) variability is part of the assessment of cardiovascular risk. In OSA, BP variability has been studied mainly as very short-term (beat-by-beat) and short-term (24-hour BP profile) variability. BP measured on consecutive heartbeats has been demonstrated to be highly variable, due to repeated peaks during sleep, so that an accurate assessment of nocturnal BP levels in OSA may require peculiar methodologies. In 24-hour recordings, BP frequently features a “nondipping” profile, ie, <10% fall from day to night, which may increase cardiovascular risk and occurrence of major cardiovascular events in the nocturnal hours. Also, BP tends to show a large “morning BP surge”, a still controversial negative prognostic sign. Increased very short-term BP variability, high morning BP, and nondipping BP profile appear related to the severity of OSA. Treatment of OSA slightly reduces mean 24-hour BP levels and nocturnal beat-by-beat BP variability by abolishing nocturnal BP peaks. In some patients OSA treatment turns a nondipping into a dipping BP profile. Treatment of arterial hypertension in OSA usually requires both antihypertensive pharmacological therapy and treatment of apnea. Addressing BP variability could help improve the management of OSA and reduce cardiovascular risk. Possibly, drug administration at an appropriate time would ensure a dipping-BP profile.

Intraspecific temporal resource partitioning at white-tailed deer feeding sites.

Individuals may reduce competition by temporally partitioning their use of a shared resource. Behavioral differences between sexes in ungulates may encourage segregation as individuals attempt to avoid antagonistic interactions. However, dominant sex and age groups may reduce subordinates’ access to food resources, regardless of the subordinate’s sex. We hypothesized that white-tailed deer Odocoileus virginianus temporally segregated at supplemental feeding sites based on social rank (subordinate: yearling males and adult females; dominant: adult males) and that segregation was affected by phase of the breeding season and diel cycle. If deer temporally segregate according to social rank, we predicted that the resulting activity patterns would manifest in one social class being relatively more susceptible to hunter-induced mortality. We used a multi-state modeling approach to quantify temporal segregation and calculated the probability that a feeding site was in a particular state during diurnal and nocturnal hours for each of the 3 phases of the breeding season. We determined that transition probabilities differed by season and diel cycle and dominant and subordinate social classes clearly avoided each other, with <1% co-occurrence at feeding sites. During the pre-breeding season, the probability of a subordinate being present during diurnal hours was 3.0× more likely than a dominant being present, but did not differ during nocturnal hours. There was no difference for dominants and subordinates during diurnal or nocturnal hours during the breeding season. In the post-breeding season, subordinates were 1.7× more likely to occur at the feeding site than a dominant during diurnal hours but they did not differ during nocturnal hours. Our results indicate that dominance status influences temporal segregation at feeding sites and is affected by the phase of the breeding season. Therefore, the resulting activity patterns may increase subordinates’ risk to human predation during the pre-breeding and post-breeding seasons.

Diel variation of ichthyoplankton recruitment in a wind-dominated temperate coastal lagoon (Argentina)

This study aimed to assess the diel changes of ichthyoplankton occurrence, during a known recruitment period, to a wind-dominated coastal lagoon (Argentina). We collected plankton samples at three sites of the lagoon's inlet area every 3 h during four 24 h cycles in mid austral summer. For each early-life history stage (eggs, yolk sac, preflexion larvae, postflexion larvae and early juveniles), the relationship between the abundance and possible combinations of the time of sampling, the wind effect, the wave period and the tidal state was evaluated by fitting generalized linear mix-effects models (GLMM). The wind effects depending on the time of sampling mainly affected fish abundance in all developmental stages. Overall, the highest abundances were collected at nocturnal hours when low-speed offshore winds blew. In addition, higher abundances of eggs, yolk sac and preflexion larvae were related to the incoming flood tide; whereas higher abundances of postflexion larvae and early juveniles were related to longer wave periods. We argued that the daily variation in the abundance of early-life history stages of fishes is related to the sea-land breeze cycle. Therefore, a conceptual framework of the recruitment process of eggs, larvae and early juveniles of fishes into this estuarine system considering the daily effect of winds is proposed.

Short sleep duration is related to kidney-related biomarkers, but not lipid profile and diet quality in diabetic nephropathy patients.

Objectives: Diabetic nephropathy may adversely influence on sleep duration. The quality of diet may also be affected by both sleep duration and diabetes nephropathy. Therefore, lower diet quality in short sleepers-diabetic nephropathy patients might be related to higher metabolic abnormalities. In the present study, we investigated if sleep duration is related to diet quality indices and biochemical markers in diabetic nephropathy patients. Method: This cross-sectional study was conducted among 237 diabetic nephropathy patients, randomly selected from patients attending in the Alzahra University Hospital, Isfahan, Iran. Usual dietary intake was assessed using validated food frequency questionnaire. Diet quality indices (including diet diversity score, dietary energy density, mean adequacy ratio, and nutrient adequacy ratio) were calculated based on standard definitions. Sleep duration was estimated using self-reported nocturnal hours of sleep. Results: Short sleepers (5-6 h) had higher blood urea nitrogen and creatinine compared with those who slept more than 7.5 h (20.26 + 0.23 mg/dl vs. 17.61 + 0.30 mg/dl, P < 0.0001, and 1.98 + 0.27 mg/dl vs. 1.90 + 0.24 mg/dl, P = 0.03, respectively). Serum triglyceride levels were positively correlated with sleep duration (P = 0.02). Diet quality indices were not significantly associated with sleep duration. Conclusion: Higher sleep duration is significantly related to lower kidney-related biomarkers in diabetic nephropathy patients. Diet quality indices were not associated with sleep duration in diabetic nephropathy patients. More longitudinal studies are required to evaluate the associations of sleep duration, diet quality and biochemical markers in diabetic nephropathy patients.

Residency and movement patterns of an apex predatory shark (Galeocerdo cuvier) at the Galapagos Marine Reserve.

The potential effectiveness of marine protected areas (MPAs) as a conservation tool for large sharks has been questioned due to the limited spatial extent of most MPAs in contrast to the complex life history and high mobility of many sharks. Here we evaluated the movement dynamics of a highly migratory apex predatory shark (tiger shark Galeocerdo cuvier) at the Galapagos Marine Reserve (GMR). Using data from satellite tracking passive acoustic telemetry, and stereo baited remote underwater video, we estimated residency, activity spaces, site fidelity, distributional abundances and migration patterns from the GMR and in relation to nesting beaches of green sea turtles (Chelonia mydas), a seasonally abundant and predictable prey source for large tiger sharks. Tiger sharks exhibited a high degree of philopatry, with 93% of the total satellite-tracked time across all individuals occurring within the GMR. Large sharks (> 200 cm TL) concentrated their movements in front of the two most important green sea turtle-nesting beaches in the GMR, visiting them on a daily basis during nocturnal hours. In contrast, small sharks (< 200 cm TL) rarely visited turtle-nesting areas and displayed diurnal presence at a third location where only immature sharks were found. Small and some large individuals remained in the three study areas even outside of the turtle-nesting season. Only two sharks were satellite-tracked outside of the GMR, and following long-distance migrations, both individuals returned to turtle-nesting beaches at the subsequent turtle-nesting season. The spatial patterns of residency and site fidelity of tiger sharks suggest that the presence of a predictable source of prey and suitable habitats might reduce the spatial extent of this large shark that is highly migratory in other parts of its range. This highly philopatric behaviour enhances the potential effectiveness of the GMR for their protection.

Periodic repolarization dynamics in patients with moderate to severe aortic stenosis

BackgroundPeriodic repolarization dynamics (PRD) refers to low-frequency oscillations of cardiac repolarization, most likely related to phasic sympathetic activation. Increased PRD is a validated predictor of mortality after myocardial infarction and in ischemic heart disease, but has not been tested in aortic valve stenosis (AS). Here, we assessed PRD in patients with AS and tested its correlation with clinical and hemodynamic parameters as well as markers of heart rate variability (HRV). Materials and methodsWe prospectively enrolled 139 consecutive patients with moderate to severe AS in sinus rhythm. In all patients we performed a 24-h Holter ECG in Frank–leads configuration. We assessed PRD according to previously published technologies from the nocturnal hours (0am–6am) and dichotomized PRD at the established cut-off value of ≥5.75deg2. In addition to clinical and hemodynamic markers, we also assessed deceleration capacity (DC) of heart rate, heart rate turbulence and standard HRV parameters. ResultsIn the patients studied, PRD was 6.55±3.96deg2. Seventy-three patients (52.5%) had increased PRD. Among them, 36 (49.9%) patients were classified as being asymptomatic. There was no association between increased PRD and clinical or hemodynamic markers, including presence of symptoms, NYHA-classification, aortic valve area, and left-ventricular ejection fraction. Thirty-three of the 73 (45.2%) patients with PRD ≥5.75deg2 also suffered from decreased vagal tonic activity by means of abnormal DC (≤2.5ms) indicating severe autonomic dysfunction. ConclusionPrevalence of increased PRD is high among patients with moderate to severe AS. Patients with increased PRD cannot be identified by clinical or hemodynamic markers Future studies should test the prognostic value of PRD in patients with AS.

0982 SHORT SLEEP DURATION AND OBJECTIVE BEHAVIORAL PATTERNS IN VERY YOUNG AFRICAN AMERICAN AND CAUCASIAN URBAN CHILDREN: A CANDLE STUDY DATA ANALYSIS

Racial and socioeconomic disparities are known to negatively affect sleep duration in school-aged children and adults. Little is known about how very young African American (AA) and Caucasian (C) children (1-year-olds) differ in nocturnal and daytime sleep duration and how this may affect daytime behavioral patterns. The purpose of this study was to determine differences in total sleep duration between AA and C 1-year-olds and how nighttime and daytime total sleep hours and number of minutes awake during the night relates to objective behavioral performance measures. We analyzed data from the first-year clinic visits (N=1056) (mean SD) (1.08 years 0.12) of predominantly AA (n=663) and C (n=393) children living in Shelby County, TN enrolled in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study. T-tests for differences between total nocturnal and daytime sleep hours and number of minutes awake during the night (all reported by parent) between races and bivariate correlations determined if sleep periods were associated with Brief Infant Toddler Social Emotional Assessment (BITSEA) total and subscale scores for externalizing and internalizing behavior problems. AA children slept significantly fewer hours than C children during daytime (7am-7pm) (2.6 1.5 v 2.9 1.1, p<0.001) and nighttime (7pm - 7am) hours (9.2 1.4 v 10.4 1.1) respectively. AA were awake more minutes during the night (18.7 40.9) than C (8.9 25.3, p <0.001). Total nighttime sleep hours were significantly correlated with Externalizing (r= -.20, p < 0.001) and Internalizing BITSEA subscales (r= -.20, p < 0.001) as were nighttime wake minutes (r= .14, p<0.001 and r= .11, p<0.001, respectively). Daytime hours of sleep were non-significantly correlated to the BITSEA scores. Urban 1-year-old AA children sleep significantly less during nighttime and daytime hours than their C counterparts. Fewer total night minutes of sleep corresponded with higher (i.e, more impaired) scores for externalizing and internalizing behaviors while more minutes of wake during the night resulted in similar behavior patterns. More focus must be given to alerting urban communities of the importance of adequate nighttime sleep for their very young children. Urban Child Institute

Energy balance in the semiarid area of the Loess Plateau, China

AbstractTo understand the energy balance over the complex terrain of the Loess Plateau, we analyzed data from the Semi‐Arid Climate and Environment Observatory of Lanzhou University (SACOL). From 1 June to 15 August 2008, the energy balance closure ratio ranged from 0.52 to 0.90 during the daytime when the available energy was greater than 150 W m−2; during nocturnal hours, it was about 0.25. We proposed a method based on water mass conservation to estimate the energy transmitted by the vertical movement of moisture in the soil and set out to explain the imbalance. During the daytime, the heat stored in the soil above the heat flux plate placed at 5 cm below the surface, the energy transmitted by the vertical movement of moisture in the soil, and the energy assimilated by plant photosynthesis contributed to 29.6%, 2.0%, and 1.8% of the energy residual, respectively. During stable conditions, the soil heat storage contributed to 46.4% of the energy residual, whereas the other energy terms contributed little. The instantaneous energy closure ratio was about 0.80 during unstable conditions; it was about 0.40 when the wind speed U was greater than 3.0 m s−1, while depends systematically on U under condition of U &lt; 3.0 m s−1 during stable conditions. Under the weak wind stable condition, affected by topography‐induced nonstationary motions, the turbulence is anisotropic with a strong horizontal fluctuation and a weak vertical fluctuation, resulting in weakened heat mixing in the vertical direction and stronger unclosure of energy.