Effects Of Short-term Variation Research Articles

Clinical studies about the influence of calcium intake on the biochemical parameters of bone metabolism

Calcium is a major component of bone, an adequate dietary supply of calcium during growth being considered critically important for the development of strong and healthy bone. The aim of the study was to evaluate the short term effects of dietary calcium intake on the biochemical diagnostic of the hyperparathyroidism in healthy people Subjects. The study was conducted on 36 subjects (age between 21 and 71 years, 4 men and 32 women) recruited from patients refereed to the Endocrinology Department of Elias Hospital who were not diagnosed with diseases proved to influence calcium or bone metabolism and agreed with the study for inclusion in the study, all subjects were checked for thyroid dysfunctions, hypercortisolism, hypogonadism, and active liver diseases which might interfere with total alkaline phosphatase values. The data obtained through this study sustain the significant effect of short term variations in calcium dietary intake on the biochemical diagnosis of hyperparathyroidism.

Effect of short-term variation in air quality index on cardiorespiratory parameters of non-smoking healthy adults during Diwali in Delhi

Background: The adverse impact of air pollution on the human body, particularly on the cardiorespiratory functions, is known and well documented in the past studies. However, limited literature is available on the specific impact of short-term variation in air quality index (AQI) and PM2.5 on the cardiorespiratory functions of young healthy individuals. This is invariably experienced around the festival of Diwali (due to bursting of crackers). This study aims to analyze the adverse impact of such short-term exposure to poor quality air on our cardiorespiratory functions and to suggest specific measures to limit these ill effects. Aim and Objective: This study aims to study the effect of AQI and PM2.5 on pulmonary function test (PFT), heart rate (HR), and blood pressure (BP) in normal non-smoking subjects pre- and post-Diwali. Materials and Methods: This study was done in the Department of Physiology, Maulana Azad Medical College, New Delhi, around the Diwali period in 2019. Subjects were recruited from the general population. This study has been performed on 30 subjects. PFT, HR, and BP measurements of all the subjects were recorded 3 days before Diwali, next day of Diwali, and on the 3rd day of Diwali. AQI and PM2.5 were measured using the System of Air Quality and Weather Forecasting and Research during the above-mentioned 3 specific days. Statistical analysis was done using SPSS-22 statistical software. The two groups were compared using paired Student’s t-test and P < 0.05 will be considered statistically significant. The data were presented as mean ± standard deviation. Results: There was a significant (P < 0.05) decrease in forced expiratory flow at 25 and 75% immediately next day of Diwali. When means of PFT parameters were compared between pre-Diwali and 3rd day of Diwali, all the PFT parameters were significantly decreased. There was a significant increase in HR immediately next day of Diwali. There was a significant increase in HR and systolic BP on the 3rd day of Diwali. Conclusion: Even the short-term exposure of acute surge in AQI and PM2.5 causes adverse effect on cardiorespiratory system of normal healthy adults.

Effect of short term variation in temperature and water content on the bacterial community in a tropical soil

The community dynamics of environmental bacteria is dependent on micro-climatic factors such as temperature and water potentials. A shift in any one of these factors can have a major impact on the richness and composition of the microbes in the soil. However, microbial responses towards these climate stressors are poorly characterised. Here, we undertook a microcosm study to assess the effect of temperature and water content on the bacterial community structure in a tropical soil over a four week period. The microcosms were incubated at three different temperatures (25°C, 30°C, and 35°C) and maintained under two different water levels (2 and 5mL). Using a combination of molecular assessment tools and numerical inference, we showed that short-term variation in both temperature and water content induced significant changes to the soil bacterial community composition. The greatest difference in community structure between treatments was observed in the Week 2 microcosms, but in the Week 4 microcosms, the community structure between treatments became more similar. Compared to temperature, water content exerted a greater effect on the bacterial diversity. Firmicutes was the most abundant phylum in all the analysed samples, and its relative abundance increased with elevation in temperature and water content. Out of six functional genes analysed, the nitrogen fixation gene (nifH) and denitrification gene (nosZ) showed significant correlations to the bacterial community structures.

Intra-individual and inter-individual variation in breath alcohol pharmacokinetics: The effect of short-term variation

Ten male and 8 female students underwent serial breath alcohol concentration (BrAC) measurements on a CAMIC Datamaster on two consecutive occasions, early evening and again the following morning. Subjects were fasted for 6 h before receiving alcohol as white wine (12.5% by volume) at doses of 38–45 g for males and 26–37 g for females, consumed over 10 min. Specific individual doses were calculated individually from height and weight (according to the Forrest Method) to give target C0 breath alcohol concentrations of 35 μg/100 ml breath in males and 31 μg/100 ml breath in females.BrAC versus time curves were constructed for each subject and the values of peak BrAC (Cmax), BrAC extrapolated at zero time (C0), time taken to reach peak (Tmax) and rate of elimination (ß) were recorded directly from the curves. Values of C0 taken from the BrAC–time curves varied widely, from 21 to 47 μg/100 ml on visit 1 and from 22 to 45 μg/100 ml on visit 2. Widmark Factors calculated from these C0 values averaged 0.74 (range, 0.59–1.06) in males and 0.73 (range, 0.58–1.05) in females. Elimination rate was higher in the morning than evening in both males (7.4 versus 5.7 μg/100 ml/h) and females (6.9 versus 5.8 μg/100 ml/h). Elimination rates in males and females were not significantly different. Total body water, measured by electronic scales, averaged 58.7% (range, 56.6–63%) in males and 48.3% (range, 40.9–57.6%) in females. Widmark Factors calculated by various established mathematical methods were 0.73–0.77 in males and 0.61–0.64 in females.

Effects of short-term variation in forage quality and forage to concentrate ratio on lactating dairy cows

Within-farm variation in forage composition can be substantial and potentially costly, and it presents challenges for sampling the forage accurately. We hypothesized that day-to-day variation in forage neutral detergent fiber (FNDF) concentrations and diet variation caused by sampling error would have negative effects on production measures in lactating dairy cows. Twenty-four Holstein cows (73d in milk) were used in 8 replicated 3×3 Latin squares with 21-d periods. Treatments were (1) control (CON), (2) variable (VAR), and (3) overreacting (ORR). On average, over the 21-d period, all 3 treatments were the same [24.7% FNDF and 48.2% forage dry matter (DM) composed of 67% alfalfa silage and 33% grass silage]. The CON treatment was essentially consistent day-to-day in total forage and FNDF concentrations and proportion of alfalfa and grass silages. The VAR treatment changed daily (in a random pattern) in proportion of alfalfa and grass silages fed, which resulted in day-to-day changes in FNDF (range was 21.5 to 28%). The ORR treatment varied in a 5-d cyclic pattern in total forage and FNDF concentrations (26, 24, 28, and 21.5% FNDF). Over the 21d, ORR (25.1kg/d) had higher DM intake compared with CON (24.5kg/d) and VAR (24.3kg/d). Milk production (42.8kg/d), milk fat (3.5%), and milk protein (2.8%) were not affected by treatment; however, a treatment × day interaction was observed for milk production. Lower daily milk yields for VAR and ORR compared with CON were rare; they only followed sustained 4- and 5-d periods of feeding higher FNDF diets compared with CON. In contrast, increased daily milk yields for VAR and ORR versus CON were more frequent and followed sustained diet changes of only 2 or 3d. Lipolytic and lipogenic-related enzyme mRNA abundances in subcutaneous adipose tissue were not affected by treatment. Treatment × day interactions were observed for milk fatty acid markers of cellulolytic bacteria (iso-14:0, iso-15:0, iso-16:0) and lipolysis (18:0) and generally followed the expected response to changes in daily rations. Overall, extreme daily fluctuations in FNDF had no cumulative negative effect on production measures over a 21-d period, and daily responses to transient increases in FNDF were less than expected.

Relationship between Nitrogen Atmospheric Deposition, Discharge and Concentration, and Monthly Change of Those in a River

The hypothesis that the product of discharge and concentration of nitrogen (N) in river water is equal to the atmospheric deposition was verified in the mountainous basin of the Tedori River in Japan. To verify this relationship, long-term data are required to eliminate the effect of short-term variation of the N components. The basin has very high mountains, including Mount Hakusan (2702 maltitude), which is covered with deep snow in winter. Therefore, limited data were used for the estimation of the deposition of the entire basin by assuming a linear relationship of altitude. As a result, it was found that the estimated N concentration coincided well with observed concentrations at six sites—the Shiramine and Kuwajima (upper stream), Nakajima (lower stream) and Dainichi dam, Tedori dam and Senami sites (middle stream). The seasonal variation of N concentrations was low in the snowmelt period and high in autumn through to winter. This was not due to the larger discharge in snowmelt season as it was also found that N deposition was high in winter and low in spring, which indicated a clear relationship between N concentration and monthly atmospheric deposition including N storage in snow pack.

Effects of Short-term Variation in Body Mass Index on Blood Pressure in Middle-aged Japanese Male Workers

We attempted to perform multilevel analyses to explore whether a year-to-year weight variation causes any corresponding effects on blood pressure (BP) among middle-aged Japanese workers. Subjects were 4547 healthy male workers 40-59 in age from whom serial data of systolic and diastolic BP were collected during health checkups conducted in the years 1997-2000. The effects on BP of a time-varying body mass index (BMI) that was rescaled to center around the individual-specific mean of 4 examinations on BP were investigated by statistical analysis with multilevel modeling to adjust for the wide variability among individuals. A significant relationship between the time-varying BMI and both systolic and diastolic BP was confirmed. None of the interaction terms for BMI×potential effect modifiers (smoking history, drinking status, leisure-time physical activity, and preference for salty taste) included in the subanalysis model showed any significant modifying effect. Our result indicated that the year-to-year weight variation, though usually in a much narrower range than the between-individual variation, has a strong impact on the corresponding BP. This result supports the public health significance of interventions in short-term weight control to prevent the development of hypertension among an otherwise healthy workplace population.

Exploring perceived tension as a response to psychosocial work stress.

This study extends the concept of tension, in part by observing changes in tension during the workday, to identify episodes causing elevated tension and relate them to bodily responses. Methods Both questionnaires and qualitative interviews were used to describe the tension concept. Tension was scored on a visual analogue scale (VAS) every hour, and trapezius muscle activity and heart rate were recorded. Ninety-four female workers from four service occupations participated. Tension was described as a musculoskeletal activation response involving the upper body regions, but also autonomic activation responses were described. The cause of elevated tension comprised a variety of situational demands; however, contact with other people causing negative emotions was a common factor. Averaged muscular activity and heart rate responses did not correlate with prolonged perceived tension, but the differential tension score between high- and low-tension periods correlated with the corresponding differential trapezius activity responses. The regression line indicated no effect of short-term variation in perceived tension on median muscle activity for differential VAS scores of < or = 2 cm. An increase of 2% of maximal electromyographic activity for a differential VAS score of 4-5 cm was indicated. This study identifies work exposures that cause tension, and it demonstrates a physiological correlate with the subjective perception of tension in the short term. The low recorded muscle activationresponse does not represent a risk factor for pain by the traditional standards used for recording and evaluating muscle activity responses, but it may point to underlying pain-inducing mechanisms, such as low-threshold overexertion of motor units.

The effects of short-term variation in abortion funding on pregnancy outcomes

The appropriations for North Carolina's abortion fund have proven inadequate during five of the years between 1980 and 1994. This on-again, off-again funding pattern provides a natural experiment for estimating the short-run effect of changes in the cost of abortions on the number of abortions to indigent women. Using an unusually detailed dataset, we estimate the effects of funding termination on the monthly abortion and birth rates. Overall, approximately one-third of pregnancies that would have resulted in an abortion, had state funds been available, are instead carried to term.

Effects of short-term variation in food availability on larval development in the barnacle Balanus amphitrite amphitrite

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 161:83-91 (1997) - doi:10.3354/meps161083 Effects of short-term variation in food availability on larval development in the barnacle Balanus amphitrite amphitrite Jian-Wen Qiu*, Louis A. Gosselin**, Pei-Yuan Qian Department of Biology, The Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong *E-mail: bojwqiu@uxmail.ust.hk **Present address: Department of Biology, University College of the Cariboo, Kamloops, British Columbia, Canada V2C 5N3 The effects of short-term variation in food availability on larval survival and development of the barnacle Balanus amphitrite amphitrite Darwin were studied in the laboratory. We found that 0.5 and 1 d intervals of alternating feeding and starvation did not influence survivorship of stage II nauplii, but lengthened the duration of development by about 40%; survivorship of nauplius II initially starved for 2 and 3 d was >25% lower than in the continuously fed controls, and larval development was prolonged by >1.5 d. Four-day initial starvation in nauplius II led to 100% larval mortality. Initial starvation also significantly affected feeding time required to complete nauplius II. Although initial starvation in nauplius II affected larval survival and duration of development, those larvae reaching cypris stage all metamorphosed into juveniles. The minimum feeding time required for completion of nauplius II was extended by >8 h for each day of initial starvation, for up to 2 d initial starvation. Feeding time required to complete individual naupliar stages also increased with larval development. Continuous access to food beyond the minimum feeding time shortened the duration of development. Our data suggest that B. amphitrite amphitrite larvae can survive short-term starvation and that such ability may help them overcome a patchy food supply in the field. However, sublethal starvation will lengthen the duration of development, thus increasing exposure to sources of mortality such as predation or misrouting. Since initial starvation in the nauplius II stage did not influence the metamorphic capacity of cyprids in the laboratory, sublethal starvation during larval development should not affect bioassay results. Barnacle · Balanus · Larval development · Starvation · Larvae Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 161. Publication date: December 31, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Effect of short-term variation in irradiance on light harvesting and photosynthesis of the marine diatom Skeletonema costatum: a laboratory study simulating vertical mixing

SUMMARY: A laboratory study was conducted into the physiology of Skeletonema costatum grown under a simple sinusoidal and a fluctuating light regime. The latter simulated a light regime similar to that which could result from the vertical mixing caused by Langmuir circulation. It was shown that the culture simulating vertical mixing reacted by decreasing the photosynthetic unit (PSU) size and increasing the number of PSUs, and hence optimized the rate of maximal photosynthesis at high, saturating irradiances. This culture also showed some change in photosynthetic parameters during the light period, which was especially pronounced during the shift from a low to a higher irradiance. The effect of this on estimates of primary production in a water column is discussed. Further, it is speculated that the assimilation number is regulated by the maximum light intensity experienced during the day rather than the total daily light dose, because only the culture submitted to a fluctuating light regime showed a real change in the maximum rate of photosynthesis (P B max) upon transfer to higher light levels.

Feed utilization by the dairy cow over multiple lactations: a review

Compared with the intensive research into the effects of short term variation of feeding the dairy cow, that into multi-lactation feeding is very modest. The evidence is conflicting regarding cumulative beneficial effects on milk production from a single increment in plane of nutrition repeated lactation by lactation: some experiments do, others do not, show a positive build-up of milk production over at least a double lactation. The general concensus of evidence is that liveweight stabilizes at a level commensurate with plane of nutrition but interpretations differ regarding the course of liveweight change over successive lactations of underfeeding. Evidence is uniform on residual effects on resumption of normal intakes after a lactation of underfeeding: milk yield is reduced for a lactation and body reserves are re-established. This effect constitutes a change in partition of nutrients between milk and body, a change that is in fact initiated in the later phases of the lactation of underfeeding itself. Neither diet composition in ad lib. feeding regimes nor system of allocation of compound feeds with ad lib. forage allowance had specific multi-lactation effects. Variation in rations applied over multiple lactations did not produce definitive effects on milk composition beyond those observed in the short term, and did not affect calving interval; but some health disorders were associated with protracted intensive feeding.

Effects of short-term variation in weather on diurnal canopy CO 2 flux and evapotranspiration of a juvenile douglas-fir stand

Using a modified Bowen ratio method, measurements of canopy energy balances and CO 2, flux densities ( F c) of a 22-year-old low productivity Douglas-fir stand, were made successfully at a remote site, during wet and dry growing seasons. Canopy conductances ( g c) were calculated from canopy evapotranspiration rates ( E) using the Penman-Monteith equation, and used to estimate mean sink level intercellular CO 2 concentration ( c i). Canopy responses of g c, E 1 F c and c i were related to variations in weather conditions. As observed in other work, g c was found to be strongly influenced by variation in vapour pressure deficit ( D) caused by changes in air temperature. Night-time F c measurements indicated that canopy respiration rates were often very high and also strongly dependent on air temperature. Hence air temperature was concluded to be a major factor limiting overall forest productivity. Variation in solar irradiance ( S) appeared to have little direct effect on g c, while no simple relationship was apparent between S and F c at the canopy level. In general, F c was not limited by g c although these two variables were often correlated. Highest F c and canopy water use efficiency ratios were observed on cloudy days with low air temperature and low D, suggesting maximum productivity occurred under these conditions.

Nonlinear nature of the unavoidable long-lived isotopic, trace and major element contamination of a developing magma chamber

Contamination of magmas by crustal materials is a possible alternative explanation of many of the trace element and isotopic features of basalts which have been advanced as evidence of mantle heterogeneity. The space problems associated with the emplacement of large masses of plutonic cumulates in most central volcanoes, and with the formation of the gabbro-dunite portion of the oceanic crust, indicates that at least some digestion of pre-existing crustal rocks has occurred. Contamination is therefore unavoidable. In the ocean basins, contamination is not due directly to incorporation of sea water, but to the digestion of previously erupted basalts which may have been hydrothermally altered by circulating sea water, plus some sediment. In a magma chamber that is periodically replenished with parental magma and periodically tapped to provide lava flows during fractional crystallization, contamination produces changes in the composition of the erupted product which are not, in general, linear between the initial and final states of the system. Moreover, the change in composition produced need not lead towards the composition of the contaminant. Provided that the periodic additions and subtractions of magma are small relative to the size of the magma chamber, the effects of short-term variations in the amount of contamination are smoothed out, while the effects on incompatible element concentrations are persistent long after active contamination has ceased. The effects on major components that enter the crystallizing phases are constrained by the need for the remaining liquid to conform to the relevant low-pressure phase equilibria.

Effect of short-term variations in light intensity on photosynthesis of a marine phytoplankter: A laboratory simulation study

Parameters of photosynthesis and growth were measured for a marine diatom (Lauderia borealis) grown in axenic continuous culture under three different light regimes: constant, simulated diurnal variation, and fluctuating. The light fluctuations were systematic increases and decreases in light intensity superimposed on the diurnal regime. In the first two regimes, a morning maximum and an afternoon depression in photosynthesis were observed. In the fluctuating light regime, the afternoon depression was less pronounced and the morning maximum was enhanced. The results may be explained by postulating a time-dependent value for the light-saturated rate of photosynthesis. Light utilization [mmol O2 cell-1 (E m-2)-1] was the same for the diurnally varying and fluctuating regimes, despite the fact that the peak light intensity in the fluctuating regime was double that of the diurnally varying regime.