Environmental and Intrinsic Control of Filtering and Feeding Rates in Arctic Daphnia

1975 ◽  
Vol 32 (2) ◽  
pp. 219-226 ◽  
Author(s):  
S. W. Chisholm ◽  
Raymond G. Stross ◽  
Paul A. Nobbs
Keyword(s):  
Feeding Rate ◽  
Functional Relationship ◽  
Time Of Day ◽  
Temperature Cycle ◽  
Food Density ◽  
Feeding Rates ◽  
Daily Food ◽  
Filtering Rate ◽  
Daphnia Middendorffiana ◽  
The Mean

Filtering and feeding rates of Daphnia middendorffiana at Point Barrow, Alaska were measured as a function of temperature, food density, animal length, and time of day.The functional relationship between feeding rate and food density followed the hyperbolic pattern typical for filter feeders. Daphnia middendorffiana was found to have comparatively high filtering capabilities at its temperature optimum (around 11 C), with filtering rate increasing with length according to the equation F =.458L3.17. The exponent of this equation was found to be a function of temperature, and the coefficient a function of food density.A bimodal diel rhythm in feeding rate was found in this species in experiments where the animals were held under constant conditions. Feeding rates were maximum at 1400 and 2400, the time of day when the temperature cycle in the ponds passes through the mean daily temperature, which is optimum for feeding in D. middendorffiana. Thus the timing of the rhythm may serve to maximize the daily food gathering ability of this species.

Hatching asynchrony and food stress in Ring-billed Gulls: an experimental study

1999 ◽  
Vol 77 (4) ◽  
pp. 515-523 ◽  
Author(s):  
Percy N Hébert ◽  
Raymond McNeil
Keyword(s):  
Feeding Rate ◽  
Peak Load ◽  
Adaptive Significance ◽  
Hatching Asynchrony ◽  
Brood Reduction ◽  
Load Reduction ◽  
Feeding Rates ◽  
Fledging Success ◽  
Clutch Initiation ◽  
The Mean

We examined predictions derived from three hypotheses (hurry-up, peak-load reduction, and brood reduction) regarding the adaptive significance of hatching asynchrony. The study was conducted, in 1991 and 1992, in a colony of Ring-billed Gulls (Larus delawarensis) on l'île de la Couvée, Montréal, Québec, Canada. The hypotheses were examined by comparing the mass and size of 18- to 20-day-old chicks from broods that hatched asynchronously (unmanipulated) and synchronously (manipulated). We also compared feeding rates and fledging success between asynchronous and synchronous broods. Also, in 1992, a sample of asynchronous and synchronous broods was experimentally food stressed by providing them with an additional chick when the oldest resident chick was 4 or 5 days old. Consistent with the hurry-up hypothesis, hatch spreads were significantly shorter in 1991 when the mean clutch initiation date was significantly earlier compared with 1992. Also consistent with the hypothesis, hatch spreads increased significantly through the breeding season. In agreement with the peak-load-reduction hypothesis, feeding rates were significantly lower in asynchronous broods compared with synchronous broods. Contrary to the hypothesis, however, the feeding rate was similar for food-stressed asynchronous and food-stressed synchronous broods. As predicted by the brood-reduction hypothesis, survivorship was higher for first-hatched chicks in asynchronous broods compared with chicks in synchronous broods. Total brood loss as a result of starvation tended to occur less often in asynchronous broods compared with synchronous broods. Likewise, fledging success was higher in asynchronous broods compared with synchronous broods. However, contrary to the brood-reduction hypothesis, survival rate of first-hatched chicks, total brood loss, and fledging success were similar in food-stressed asynchronous and synchronous broods. The above results indicate that several benefits accure to Ring-billed Gulls from hatching asynchrony.

scholarly journals Regular monitoring of breast-feeding rates: feasible and sustainable. The Emilia-Romagna experience

2017 ◽  
Vol 20 (11) ◽  
pp. 1895-1902 ◽  
Author(s):  
Simona Di Mario ◽  
Silvana Borsari ◽  
Eleonora Verdini ◽  
Sergio Battaglia ◽  
Luca Cisbani ◽  
...  
Keyword(s):  
Monitoring System ◽  
Breast Feeding ◽  
Record Linkage ◽  
Feeding Rate ◽  
Local Health ◽  
Feeding Rates ◽  
Regional Survey ◽  
Health Authorities ◽  
The Mean ◽  
Local Health Authorities

AbstractObjectiveAn efficient breast-feeding monitoring system should be in place in every country to assist policy makers and health professionals plan activities to reach optimal breast-feeding rates.Design/Setting/SubjectsFrom March to June 2015, breast-feeding rates at 3 and 5 months of age were monitored in Emilia-Romagna, an Italian region, using four questions added to a newly developed paediatric immunization database with single records for each individual. Data were collected at primary-care centres. Breast-feeding definitions and 24 h recall as recommended by the WHO were used. Direct age standardization was applied to breast-feeding rates. Record linkage with the medical birth database was attempted to identify maternal, pregnancy and delivery factors associated with full breast-feeding rates at 3 and 5 months of age.ResultsData on breast-feeding were collected for 14044 infants. The mean regional full breast-feeding rate at 3 months was 52 %; differences between local health authorities ranged from 42 to 62 %. At 5 months of age, the mean regional full breast-feeding rate dropped to 33 % (range between local health authorities: 26 to 46 %). Record linkage with the birth certificate database was successful for 93 % of records. Total observations more than doubled with respect to the previous regional survey.ConclusionsThe new monitoring system implemented in 2015 in Emilia-Romagna region, totally integrated with the immunization database, has proved to be feasible, sustainable and more efficient than the previous one. This system can be a model for other regions and countries where the vast majority of mothers obtain vaccinations from public health facilities and that already have an immunization database in place.

Abundance and Consumption Rate of Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae) on Peaches and Plums

2008 ◽  
Vol 43 (4) ◽  
pp. 394-407 ◽  
Author(s):  
Peter C. Andersen ◽  
Russell F. Mizell ◽  
Brent V. Brodbeck ◽  
Thomas G. Beckman ◽  
Gerard Krewer
Keyword(s):  
Feeding Rate ◽  
Consumption Rate ◽  
Prunus Persica ◽  
Feeding Rates ◽  
Homalodisca Vitripennis ◽  
Prunus Salicina ◽  
Nocturnal Feeding ◽  
Primary Vector ◽  
The Mean ◽  
Nighttime Feeding

Homalodisca vitripennis (Germar), the glassy-winged sharpshooter, is a primary vector of phony peach and plum leaf scald diseases caused by Xylella fastidiosa Wells et al. A survey of H. vitripennis on peach [Prunus persica (L.) Batsch] varieties established that leafhopper abundances varied from 0–13 per tree. Prunus persica cvs. Flordaking and June Gold and Prunus salicina Lindl. (cvs. Methley and Santa Rosa) were then budded on each of 3 P. persica rootstocks (cvs. Aldrighi, Lovell and Nemaguard). Leafhopper abundance was monitored on each of the two scions budded on each rootstock and on non budded rootstocks over a 2-yr period. The genotypes were container-grown in Year 1 and were planted in the field in Year 2. For both years leafhopper abundance was greatest during early June and on Methley and Santa Rosa cultivars compared with the peach genotypes. The feeding rates of leafhoppers were substantially higher on plum scions than on peach scions, and nocturnal feeding rates were often higher than daytime feeding rates. Mean leafhopper feeding rates were correlated with leafhopper abundance on Prunus genotypes from 3–8 June in a quadratic manner (F = 53.8; df = 2,12; R2 = 0.90; P < 0.0001); the mean nighttime feeding rate was best correlated linearly to mean cumulative leafhopper abundance (F= 446.9; df = 1,13; R2 = 0.972; P < 0.0001).

Thermoregulatory responses to cold water at different times of day

1999 ◽  
Vol 87 (1) ◽  
pp. 243-246 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
James E. Kain ◽  
Michael N. Sawka
Keyword(s):  
Cold Water ◽  
Water Immersion ◽  
Early Morning ◽  
Cold Water Immersion ◽  
Time Of Day ◽  
Mean Skin Temperature ◽  
Mean Body Temperature ◽  
Metabolic Heat ◽  
Body Temperature Change ◽  
The Mean

This study examined how time of day affects thermoregulation during cold-water immersion (CWI). It was hypothesized that the shivering and vasoconstrictor responses to CWI would differ at 0700 vs. 1500 because of lower initial core temperatures (Tcore) at 0700. Nine men were immersed (20°C, 2 h) at 0700 and 1500 on 2 days. No differences ( P > 0.05) between times were observed for metabolic heat production (M˙, 150 W ⋅ m−2), heat flow (250 W ⋅ m−2), mean skin temperature (T sk, 21°C), and the mean body temperature-change in M˙(ΔM˙) relationship. Rectal temperature (Tre) was higher ( P < 0.05) before (Δ = 0.4°C) and throughout CWI during 1500. The change in Tre was greater ( P < 0.05) at 1500 (−1.4°C) vs. 0700 (−1.2°C), likely because of the higher Tre-T skgradient (0.3°C) at 1500. These data indicate that shivering and vasoconstriction are not affected by time of day. These observations raise the possibility that CWI may increase the risk of hypothermia in the early morning because of a lower initial Tcore.

On kinematic waves II. A theory of traffic flow on long crowded roads

1955 ◽  
Vol 229 (1178) ◽  
pp. 317-345 ◽  
Keyword(s):  
Traffic Flow ◽  
Functional Relationship ◽  
Vehicle Speed ◽  
Main Road ◽  
The Road ◽  
Traffic Distribution ◽  
Kinematic Waves ◽  
The Subject ◽  
The Mean ◽  
Starting Flow

This paper uses the method of kinematic waves, developed in part I, but may be read independently. A functional relationship between flow and concentration for traffic on crowded arterial roads has been postulated for some time, and has experimental backing (§2). From this a theory of the propagation of changes in traffic distribution along these roads may be deduced (§§2, 3). The theory is applied (§4) to the problem of estimating how a ‘hump’, or region of increased concentration, will move along a crowded main road. It is suggested that it will move slightly slower than the mean vehicle speed, and that vehicles passing through it will have to reduce speed rather suddenly (at a ‘shock wave’) on entering it, but can increase speed again only very gradually as they leave it. The hump gradually spreads out along the road, and the time scale of this process is estimated. The behaviour of such a hump on entering a bottleneck, which is too narrow to admit the increased flow, is studied (§5), and methods are obtained for estimating the extent and duration of the resulting hold-up. The theory is applicable principally to traffic behaviour over a long stretch of road, but the paper concludes (§6) with a discussion of its relevance to problems of flow near junctions, including a discussion of the starting flow at a controlled junction. In the introductory sections 1 and 2, we have included some elementary material on the quantitative study of traffic flow for the benefit of scientific readers unfamiliar with the subject.

Twenty-four-hour rhythms of plasma glucose and insulin secretion rate in regular night workers

2000 ◽  
Vol 278 (3) ◽  
pp. E413-E420 ◽  
Author(s):  
C. Simon ◽  
L. Weibel ◽  
G. Brandenberger
Keyword(s):  
Insulin Secretion ◽  
Mean Amplitude ◽  
Sampling Procedure ◽  
Time Of Day ◽  
Secretion Rate ◽  
Nocturnal Sleep ◽  
Sleep Condition ◽  
The Mean ◽  
Nighttime Sleep ◽  
Insulin Secretion Rate

To determine whether the ultradian and circadian rhythms of glucose and insulin secretion rate (ISR) are adapted to their permanent nocturnal schedule, eight night workers were studied during their usual 24-h cycle with continuous enteral nutrition and a 10-min blood sampling procedure and were compared with 8 day-active subjects studied once with nocturnal sleep and once with an acute 8-h-shifted sleep. The mean 24-h glucose and ISR levels were similar in the three experiments. The duration and the number of the ultradian oscillations were influenced neither by the time of day nor by the sleep condition or its shift, but their mean amplitude increased during sleep whenever it occurred. In day-active subjects, glucose and ISR levels were high during nighttime sleep and then decreased to a minimum in the afternoon. After the acute sleep shift, the glucose and ISR rhythms were split in a biphasic pattern with a slight increase during the night of deprivation and another during daytime sleep. In night workers, the glucose and ISR peak levels exhibited an 8-h shift in accordance with the sleep shift, but the onset of the glucose rise underwent a shift of only 6 h and the sleep-related amplification of the glucose and ISR oscillations did not occur simultaneously. These results demonstrate that despite a predominant influence of sleep, the 24-h glucose and ISR rhythms are only partially adapted in permanent night workers.

scholarly journals Assessment of intraocular pressure in chinchillas of different age groups using rebound tonometry

2016 ◽  
Vol 46 (8) ◽  
pp. 1466-1471 ◽  
Author(s):  
Flor Diana Yokoay Claros Chacaltana ◽  
João Antonio Tadeu Pigatto ◽  
Ione Terezinha Denardin
Keyword(s):  
Intraocular Pressure ◽  
Age Groups ◽  
Time Of Day ◽  
Age Group ◽  
Group Iii ◽  
Rebound Tonometer ◽  
Indirect Ophthalmoscopy ◽  
Group I ◽  
Schirmer Tear Test ◽  
The Mean

ABSTRACT: The aim of this research was to measure the intraocular pressure (IOP) of normal chinchilla eyes using the rebound tonometer. A further aim was to assess whether there were differences in the values of intraocular pressure in relation to animals age, gender and time of day. Thirty-six chinchillas were divided into three groups of 12 chinchillas each, by age: Group I (2-6-month-old), Group II (20 and 34 months) and Group III (37 and 135 months). Ophthalmic examination was performed previously by Schirmer tear test, slit lamp biomicroscopy, indirect ophthalmoscopy and fluorescein test in all chinchillas. Three measurements of intraocular pressure were assessed on the same day (7, 12 and 19h). Tonometry was performed on both eyes using the rebound tonometer after calibration in "p" mode. Statistical analysis was performed with SigmaPlot for Windows. The mean IOP for groups I, II and III were 2.47±0.581mmHg, 2.47±0.581mmHg and 2.51±0.531mmHg, respectively. No significant differences were reported between age and IOP and no significant differences were reported between the time of day and IOP. The IOP in chinchillas did not differ significantly between genders or ages of the animals, and did not change with time of day.

Estimates of the energy required for maintenance by adult sheep 2. Grazing sheep

1963 ◽  
Vol 5 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. P. Langlands ◽  
J. L. Corbett ◽  
I. McDonald ◽  
G. W. Reid
Keyword(s):  
Organic Matter ◽  
Energy Cost ◽  
Functional Relationship ◽  
Adult Sheep ◽  
Maintenance Requirement ◽  
Digestible Organic Matter ◽  
Faecal Nitrogen ◽  
Grazing Period ◽  
The Mean ◽  
Maintenance Requirements

SUMMARYThe mean daily digestible organic matter intake (D) of each of 47 adult sheep during a grazing period of mean length 48 days was estimated by the chromium sesquioxide/faecal nitrogen technique. Mean live-weights (W) and mean daily weight gains (G) were also measured.The regression of D on W and G, and the underlying or functional relationship between D, W and G were both estimated. From the underlying relationship, the preferred equation, the maintenance requirement of a 100 lb. sheep at pasture is estimated to be 1·02 lb. digestible organic matter daily. This value is 24% higher than the corresponding value for housed sheep obtained previously by us.This result is compared with other estimates of the energy cost of grazing and it is concluded that further work is needed in order to define those circumstances which elevate the maintenance requirements of grazing animals.

scholarly journals Scale Characterization and Correction of Diurnal Cycle Errors in MAPLE

2017 ◽  
Vol 56 (9) ◽  
pp. 2561-2575 ◽  
Author(s):  
Aitor Atencia ◽  
Isztar Zawadzki ◽  
Marc Berenguer
Keyword(s):  
Diurnal Cycle ◽  
Spatial Scales ◽  
Time Of Day ◽  
Precipitation Forecast ◽  
Systematic Bias ◽  
Correction Scheme ◽  
Average Rainfall ◽  
The Mean ◽  
Scale Characterization ◽  
Composite Data

AbstractThe most widely used technique for nowcasting of quantitative precipitation in operational and research centers is the Lagrangian extrapolation of the latest radar observations. However, this technique has a limited forecast skill because of the assumption made on its formulation, such as the fact that the motion vectors do not change and, even more important for convective events, neglect any growth or decay in the precipitation field. In this work, the McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation (MAPLE) errors have been computed for 10 yr of radar composite data over the continental United States. The study of these errors shows systematic bias depending on the time of day. This effect is related to the solar cycle, whose heating energy results in an increase in the average rainfall in the afternoon. This external forcing interacts with the atmospheric system, creating local initiation and dissipation of convection depending on orography, land use, cloud coverage, etc. The signal of the diurnal cycle in MAPLE precipitation forecast has been studied in different locations and spatial scales as a function of lead time in order to recognize where, when, and for which spatial scales the signal is significant. This information has been used in the development of a scaling correction scheme where the mean errors due to the diurnal cycle are adjusted. The results show that the developed methodology improves the forecast for the spatial scales and locations where the diurnal cycle signal is significant.

scholarly journals Comparative verification in complex topography

2021 ◽  
Author(s):  
Jonas Bhend ◽  
Jean-Christophe Orain ◽  
Vera Schönenberger ◽  
Christoph Spirig ◽  
Lionel Moret ◽  
...  
Keyword(s):  
Weather Forecasting ◽  
Absolute Error ◽  
Time Of Day ◽  
Probabilistic Forecasts ◽  
Wide Range ◽  
Direct Model ◽  
Forecasting System ◽  
The Mean ◽  
Update Frequency ◽  
Core Activity

&lt;p&gt;Verification is a core activity in weather forecasting. Insights from verification are used for monitoring, for reporting, to support and motivate development of the forecasting system, and to allow users to maximize forecast value. Due to the broad range of applications for which verification provides valuable input, the range of questions one would like to answer can be very large. Static analyses and summary verification results are often insufficient to cover this broad range. To this end, we developed an interactive verification platform at MeteoSwiss that allows users to inspect verification results from a wide range of angles to find answers to their specific questions.&lt;/p&gt;&lt;p&gt;We present the technical setup to achieve a flexible yet performant interactive platform and two prototype applications: monitoring of direct model output from operational NWP systems and understanding of the capabilities and limitations of our pre-operational postprocessing. We present two innovations that illustrate the user-oriented approach to comparative verification adopted as part of the platform. To facilitate the comparison of a broad range of forecasts issued with varying update frequency, we rely on the concept of time of verification to collocate the most recent available forecasts at the time of day at which the forecasts are used. In addition, we offer a matrix selection to more flexibly select forecast sources and scores for comparison. Doing so, we can for example compare the mean absolute error (MAE) for deterministic forecasts to the MAE and continuous ranked probability scores of probabilistic forecasts to illustrate the benefit of using probabilistic forecasts.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document