Diurnal Variation In Rate Research Articles

Diurnal and seasonal patterns in presentations with hip fracture-data from the national hip fracture database.

we set out to examine diurnal and seasonal variation in hip fracture presentations to question their origin and to consider their implications for the organisation of health services for older people. we used the National Hip Fracture Databaseto identify the time of presentation and surgery for 64,102 patients; all those older than60 years who sustained this injury in England, Wales and Northern Ireland during 2014. we found marked diurnal variation in rates of presentation, increasing sharply after0800 hours and decreasing only after 1800 hours. Among people who sustained their hip fracture in hospital (n=2,761) or in a care home (n=12,141), there were peaks in presentations around0900 and 1800 hours. Time of presentation had a very marked effect on whether surgery was delayed by more than 24 hours but less against the national guidelines of surgery within 36 hours or by the next day. There were 15.6% more presentations during December compared to all other months (9.5% versus 8.2%, P <0.001), a pattern also found among people living in care homes (9.1% versus 8.3%, P <0.001). we have identified morning and evening peaks of presentation for inpatients and care home residents and a December increase in overall hip fracture numbers. These patterns warrant further investigation if those organising health services are to prevent this injury, and to provide appropriate beds and prompt operations for the people who sustain it.

The effect of Ramadan fasting on the diurnal variations in aerobic and anaerobic performances in Tunisian youth soccer players

The purpose of this investigation was to assess the effects of Ramadan fasting on physical performance in youth Muslim athletes their diurnal fluctuations. In a balanced and randomized study design, 10 Tunisian junior male soccer players completed the Yo-Yo intermittent recovery test level 1 (YYIRT) and the repeated sprint ability (RSA) at 07:00 and 17:00 h on three different occasions: 1 week before Ramadan (BR), the second week of Ramadan (SWR) and the fourth week of Ramadan (ER). There was an interval of 36 h between any two successive tests. Oral temperature was measured before each test. Under each condition, the results showed a time-of-day effect on oral temperature. However, no significant diurnal variations in rate of perceived exertion (RPE) scores were observed during the three periods (BR, SWR and ER). Performances during the YYIRT and the first two sprints of the RSA improved significantly from morning to evening during BR. However, daily fluctuations disappeared during the SWR and ER. Considering the effect of Ramadan on physical performances, in comparison with BR, no significant difference was observed during Ramadan at 07:00 h. However, the variables were significantly lower in SWR and ER at 17:00 h. The RPE scores were higher during SWR and ER in the evening after the YYIRT and RSA tests. In conclusion, the time-of-day effects on physical performances variables tend to disappear during Ramadan. In comparison with the period BR, physical performances were unaffected at 07:00 h but impaired at 17:00 h during Ramadan.

Daily patterns of nest visits are correlated with ambient temperature in the Northern Wheatear

The diurnal pattern of foraging behaviour in birds is commonly linked to the risk of starvation and predation. During the breeding season, when offspring place additional demands on the quantity of food adults need to collect, diurnal foraging patterns may be influenced to a greater extent by food availability because adults need to balance starvation-predation risks not only for themselves but also their offspring. We used data-loggers to measure diurnal variation in rates of nest visits to 7- to 10-day-old nestlings of the insectivorous Northern Wheatear Oenanthe oenanthe in Swedish farmland habitat. Adults provisioned the nestlings with food for an average 19.5 h each day (n = 11 pairs), with visitation rates sharply increasing during the morning, remaining relatively stable between 0800 and 1700 hours, and then declining in the evening. This pattern is similar to daily temperature fluctuations and is consistent with the hypothesis that nest visit rates are a function of temperature-dependent prey availability. Higher rates of nest visits on warm days support this correlation between temperature and offspring feeding. However, without data on the rate of self-feeding by adults it is difficult to distinguish between patterns of nest visits being driven by food availability, or starvation-predation constraints being imposed on the parents; thus, future studies of patterns of offspring feeding should collect data on the self-feeding behaviour of the adults.

No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest

Characterization of soil respiration rates and delta(13)C values of soil-respired CO(2) are often based on measurements at a particular time of day. A study by Gower et al. (2001) in a boreal forest demonstrated diurnal patterns of soil CO(2) flux using transparent measurement chambers that included the understory vegetation. It is unclear whether these diurnal patterns were solely the result of photosynthetic CO(2) uptake during the day by the understory or whether there were underlying trends in soil respiration, perhaps driven by plant root allocation, as recently demonstrated in Mediterranean oak savannah. We undertook intensive sampling campaigns in a boreal Picea abies L. Karst. forest to investigate whether diurnal variations in soil respiration rate and stable carbon isotope ratio (delta(13)C) exist in this ecosystem when no understory vegetation is present in the measurement chamber. Soil respiration rates and delta(13)C were measured on plots in which trees were either girdled (to terminate the fraction of soil respiration directly dependent on recent photosynthate from the trees), or not girdled, every 4 h over two 48-hour cycles during the growth season of 2004. Shoot photosynthesis and environmental parameters were measured concurrently. No diurnal patterns in soil respiration rates and delta(13)C were observed in either treatment, despite substantial variations in climatic conditions and shoot photosynthetic rates in non-girdled trees. Consequently, assessment of daily soil respiration rates and delta(13)C in boreal forest systems by single, instantaneous daily measurements does not appear to be confounded by substantial diurnal variation.

Diurnal variation in rates of calcification and carbonate sediment dissolution in Florida Bay

Water quality and criculation in Florida Bay (a shallow, subtropical estuary in south Florida) are highly dependent upon the development and evolution of carbonate mud banks distributed throughout the Bay. Predicting the effect of natural and anthropogenic perturbations on carbonate sedimentation requires an understanding of annual, seasonal, and daily variations in the biogenic and inorganic processes affecting carbonate sediment precipitation and dissolution. In this study, net calcification rates were measured over diurnal cycles on 27 d during summer and winter from 1999 to 2003 on mud banks and four representative substrate types located within basins between mud banks. Substrate types that were measured in basins include seagrass beds of sparse and intermediate densityThalassia sp., mud bottom, and hard bottom communities. Changes in total alkalinity were used as a proxy for calcification and dissolution. On 22 d (81%), diurnal variation in rates of net calcification was observed. The highest rates of net carbonate sediment production (or lowest rates of net dissolution) generally occurred during daylight hours and ranged from 2.900 to −0.410 g CaCO3 m−2d−1. The lowest rates of carbonate sediment production (or net sediment dissolution) occurred at night and ranged from 0.210 to −1.900 g CaCO3 m−2 night−1. During typical diurnal cycles, dissolution during the night consumed an average of 29% of sediment produced during the day on banks and 68% of sediment produced during the day in basins. Net sediment dissolution also occurred during daylight, but only when there was total cloud cover, high turbidity, or hypersalinity. Diurnal variation in calcification and dissolution in surface waters and surface sediments of Florida Bay is linked to cycling of carbon dioxide through photosynthesis and respiration. Estimation of long-term sediment accumulation rates from diurnal rates of carbonate sediment production measured in this study indicates an overall average accumulation rate for Florida Bay of 8.7 cm 1000 yr−1 and suggests that sediment dissolution plays a more important role than sediment transport in loss of sediment from Florida Bay.

Self‐harm shows diurnal variation

AbstractIncidents of self‐harm at a medium secure unit in England over a four‐year period showed a clear evening peak in frequency. This observation of a diurnal variation in rate of self‐harm supports work from other studies and merits further investigation. Copyright © 1998 Whurr Publishers Ltd.

Circadian stage-dependent changes in diazepam kinetics.

The effect of dosing time on diazepam kinetics was investigated in 28 healthy men. A 5-mg dose of diazepam was given orally or intravenously on two occasions, in the morning (9:30 A.M.) or in the evening (9:30 P.M.) under the postprandial condition or after a 9-hr fast. After oral doses under postprandial conditions, the mean peak total diazepam concentration in plasma was higher and the time to peak concentration was faster after morning dosing than after evening dosing, but neither mean elimination t1/2 nor AUC between morning and evening dosings differ. Intravenous diazepam did not eliminate the time-dependent changes in diazepam kinetics occurring soon after injection under postprandial conditions, although it diminished the difference. During the 9-hr fast, time-dependent changes in diazepam kinetics were marked, especially after intravenous injection. Diazepam free fraction was lower 0.5 hr after intravenous dosing in the morning, and there was a negative correlation (r = -0.678) between the diazepam free fraction and total diazepam plasma concentration. These results suggest that diurnal variations in rate of drug distribution because of alterations in protein binding as well as in absorption from the gastrointestinal tract contribute to time-dependent changes in diazepam kinetics.

Circadian stage-dependent changes in diazepam kinetics.

The effect of dosing time on diazepam kinetics was investigated in 28 healthy men. A 5-mg dose of diazepam was given orally or intravenously on two occasions, in the morning (9:30 A.M.) or in the evening (9:30 P.M.) under the postprandial condition or after a 9-hr fast. After oral doses under postprandial conditions, the mean peak total diazepam concentration in plasma was higher and the time to peak concentration was faster after morning dosing than after evening dosing, but neither mean elimination t1/2 nor AUC between morning and evening dosings differ. Intravenous diazepam did not eliminate the time-dependent changes in diazepam kinetics occurring soon after injection under postprandial conditions, although it diminished the difference. During the 9-hr fast, time-dependent changes in diazepam kinetics were marked, especially after intravenous injection. Diazepam free fraction was lower 0.5 hr after intravenous dosing in the morning, and there was a negative correlation (r = -0.678) between the diazepam free fraction and total diazepam plasma concentration. These results suggest that diurnal variations in rate of drug distribution because of alterations in protein binding as well as in absorption from the gastrointestinal tract contribute to time-dependent changes in diazepam kinetics.

Discovering the Role of Lichens in the Nitrogen Cycle in Boreal-Arctic Ecosystems

Discovering the Role of Lichens in the Nitrogen Cycle in Boreal-Arctic Ecosystems

Relationship between diurnal variations in biosynthesis cholesterol and bile acids

The rate of incorporation of acetate into cholesterol by rat liver slices and the rates of 7 α-hydroxylation of cholesterol, of 12 α-hydroxylation of 7 α-hydroxy-4-cholesten-3-one and of 7 α-hydroxylation of taurodeoxycholic acid by rat liver microsomes were assayed at six different times of the day. The diurnal variations in rate of incorporation of acetate into cholesterol (maximum between 8 p.m. and midnight and minimum at noon) and in rate of 7 α-hydroxylation of cholesterol (maximum at 8 p.m. and minimum at noon) followed each other closely. 12 α-Hydroxylation of 7 α-hydroxy-4-cholesten-3-one and 7 α-hydroxylation of taurodeoxycholic acid remained at about the same level during the day. The pattern of diurnal variations in incorporation of acetate into cholesterol and in 7 α-hydroxylation of cholesterol was changed by reversing the daily rhythm of the rats. The results indicate that changes in rates of biosynthesis of cholesterol and bile acids occur practically concomitantly.

Ozone Suppression of White Pine Net Photosynthesis

Reduction in rates of net photosynthesis following exposure to ozone was observed in eastern white pine saplings prior to the development of visible injury. Branches exposed to consecutive doses of 50-80 pphM ozone for 4 hr and 80-90 pphM ozone for 3 hr appeared to have suppressed net photosynthetic rates but results were confounded by diurnal rate variation. Photosynthetic rates of treated branches returned to normal levels following this initial ozone exposure. A second ozonation involving dosages of 90-100 pphM for 5 and 3 hr was sufficient to reduce rates of net photosynthesis by approximately 80%. 13 references, 1 figure.

Diurnal Variation in Root Respiration

The existence of a diurnal fluctuation in root metabolism can be deduced from several studies. While studying root respiration, Harris (13) noted a diurnal variation in the rate of CO2 production by roots of tomatoes and certain deciduous fruit trees. Cannon (5) found oxygen consumption of roots to be increased in light under conditions conducive to high transpiration. Grossenbacher (7), Speidel (24), and Went (26) found autonomic diurnal fluctuations in root pressure and exudation from decapitated plants; Hagan (8) observed basically the same phenomenon in non-exuding root systems, and showed it dependent on aerobic respiration. Arisz, Helder, and van Nie (2), van Andel (1), and Vaadia (25) have extended these observations to implicate the transfer of salt to the xylem elements as the process primarily concerned. Hanson and Biddulph (11) demonstrated a diurnal variation in ion transfer to the shoot of intact bean plants grown at constant temperature and humidity under artificial light, which Hylmo (16) believes may be associated with increased transpiration during the period of illumination. Went (26) observed that the accumulation of p32 in the shoots of tomato plants was more rapid during the day. These diurnal fluctuations in root activity could be a reflection of a diurnal variation in respiration rate, as suggested by the experiments of Harris (13). However, Grossenbacher (7) found no correlation between fluctuations in root pressure of excised root systems and respiration. Since the completion of our work Vaadia (25) has published experiments showing no diurnal variation in the respiration or ion uptake of excised roots or root sections. On the other hand, one of us (Hageman) had observed a diurnal variation in root respiration of intact Derris plants; these results are reported here. The objective of this work was to determine if there was in fact a diurnal variation in root respiration. Respiration measurements were accordingly made with excised root tissue and the roots of intact corn and soybean plants. The experiments showed intact roots to respire more rapidly during daylight hours, but root tissue excised from these plants exhibited no such diurnal variation.

Diurnal variation in rate of alcohol metabolism.

Diurnal variation in rate of alcohol metabolism.

Diurnal Variation in Excretion Rate of Formed Elements in Urine in Hemorrhagic Bright's Disease

The enumeration and differential counting of the formed elements in the urine forms the basis of the most useful clinical methods for distinguishing the different types of Bright's Disease and yields valuable information concerning prognosis. The usual method consists in examining a fairly concentrated specimen of urine collected over 9 or 12 hours during the night. Frequently it becomes desirable to examine specimens of urine over a shorter period and in the daytime, often without any particular precautions of diet. To this end the diurnal variation in the rate of excretion of the formed elements in the urine was made in 2 patients with hemorrhagic Bright's Disease. Two observations were made upon each of these subjects. They were both young adult males (case 1 was 28 years old and case 2, 20 years old). The specific gravity of the specimens (1.012-1.018) was frequently not so high as is desirable, but this was compensated for in large degree by the prompt examination of the specimens shortly after they were voided. The formed elements were counted by the method devised by Addis. Urine was collected over 2-hour periods from 6 A.M. to 10 P.M. and then the 8 hours night urine collected in a single specimen. In the first experiment on both patients they remained in bed all day while in the second experiment they were up and about during the day. The second experiments were made 5 days (case 1) and 2 days (case 2) respectively after the first ones. Both patients had a mild hypertension but no anemia or nitrogen retention. The renal function in case 1 was 60% and in case 2 about 45% of normal. Both patients were recovering from the initial stage of hemorrhagic Bright's Disease. The results in Fig. 1 (the significance of the various lines on the charts is indicated by the legends used in the ordinate scales, e. g., the heavy continuous line is urine volume rate, etc.) show a considerable degree of uniformity in the several experiments.