Are there thermoregulatory constraints on the timing of pupping for harbour seals?

1998 ◽  
Vol 76 (12) ◽  
pp. 2245-2254 ◽  
Author(s):  
A T Hind ◽  
WSC Gurney
Keyword(s):  
Metabolic Rate ◽  
Indirect Evidence ◽  
Minimum Cost ◽  
Experimental Information ◽  
Energetic Cost ◽  
Detailed Model ◽  
Harbour Seals ◽  
Seal Population ◽  
Moray Firth

In this paper we describe a detailed model of the thermal balance of a seal in air. We tested the model against the limited experimental information available on thermoregulation for harbour seals (Phoca vitulina) in air. Since a mother must meet both her own and her pups' energetic costs, we suggest that there may be an energetic advantage for harbour seals in Scotland if lactation is timed to coincide with the most favourable conditions for hauling out. To test this hypothesis, we used the harbour seals in the Moray Firth as our case study. The model does predict an energetic cost resulting from thermoregulation during haul-out for a mother and her pup in the Moray Firth. Taking the mother and pup as a unit, we estimate the minimum cost during lactation. This combined cost, which must be met by the female seal, is similar to the minimum metabolic rate during haul-out for the summer predicted from the model. In winter the predicted minimum metabolic rate exceeds the lactation cost, and an additional cost of thermoregulation results. The model predicts the most energetically favourable time for lactation to be June and July, and this is coincident with the timing of pupping in this seal population. We suggest that for harbour seals in Scotland, the timing of pupping may be influenced by the thermoregulation costs of haul-out. This provides indirect evidence that thermoregulation influences haul-out behaviour in this small phocid species.

Seasonal and between-year variations in the diet of harbour seals in the Moray Firth, Scotland

1996 ◽  
Vol 74 (6) ◽  
pp. 1110-1121 ◽  
Author(s):  
D. J. Tollit ◽  
P. M. Thompson
Keyword(s):  
Diet Composition ◽  
Gadus Morhua ◽  
Prey Species ◽  
Temporal Variations ◽  
Short Term ◽  
Harbour Seals ◽  
Faecal Samples ◽  
Poor Indicator ◽  
Moray Firth ◽  
Merlangius Merlangus

Predictions concerning the effect of seals upon prey stocks require an understanding of temporal variations in diet composition. This study examined the extent of between-year and seasonal variations in the diet of harbour seals (Phoca vitulina) from the Moray Firth, Scotland, between 1989 and 1992. Analyses of fish otoliths and cephalopod beaks collected from 1129 faecal samples were used to derive estimates of the contribution made by each of 35 prey species, based on the number and mass consumed. The key prey, by mass, were sand eels (Ammodytidae) (47%), lesser octopus (Eledone cirrhosa) (27%), whiting (Merlangius merlangus) (6%), flounder (Platichthys flesus) (5%), and cod (Gadus morhua) (4%). Between-year and seasonal fluctuations in the contributions of these species were observed. Sand eels contributed 86–20% in summer and 91–49% in winter. Lesser octopus contributed 0–62% in summer and < 5% in winter, whilst whiting and cod contributed 2–34% in winter and 1–4% in summer. In contrast to 1988, clupeids were unimportant in winter. Differences in diet composition appeared to reflect local changes in the availability of food, especially overwintering clupeids. Results indicate that dietary information obtained from short-term studies can be a poor indicator of subsequent diet composition and should be treated with caution when used to predict the effect of seals on prey populations.

scholarly journals Humans use minimum cost movements in a whole-body task

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lijia Liu ◽  
Dana Ballard
Keyword(s):  
Dynamic Model ◽  
Tool Use ◽  
Large Scale ◽  
Minimum Cost ◽  
Whole Body ◽  
Energetic Cost ◽  
Body Movements ◽  
Closed Curves ◽  
General Movements ◽  
Musculoskeletal Systems

AbstractHumans have elegant bodies that allow gymnastics, piano playing, and tool use, but understanding how they do this in detail is difficult because their musculoskeletal systems are extraordinarily complicated. Nonetheless, common movements like walking and reaching can be stereotypical, and a very large number of studies have shown their energetic cost to be a major factor. In contrast, one might think that general movements are very individuated and intractable, but our previous study has shown that in an arbitrary set of whole-body movements used to trace large-scale closed curves, near-identical posture sequences were chosen across different subjects, both in the average trajectories of the body’s limbs and in the variance within trajectories. The commonalities in that result motivate explanations for its generality. One explanation could be that humans also choose trajectories that are economical in cost. To test this hypothesis, we situate the tracing data within a forty eight degree of freedom human dynamic model that allows the computation of movement cost. Using the model to compare movement cost data from nominal tracings against various perturbed tracings shows that the latter are more energetically expensive, inferring that the original traces were chosen on the basis of minimum cost.

scholarly journals Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

2021 ◽  
Author(s):  
Heiko T. Jansen ◽  
Brandon Evans Hutzenbiler ◽  
Hannah R. Hapner ◽  
Madeline L. McPhee ◽  
Anthony M. Carnahan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Insulin Sensitivity ◽  
Metabolic Rate ◽  
Ursus Arctos ◽  
Metabolic Effects ◽  
Energetic Cost ◽  
Grizzly Bears ◽  
Flux Analysis ◽  
Active Season ◽  
Ursus Arctos Horribilis

ABSTRACTHibernation is characterized by suppression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) glucose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (ß-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free-fatty acids and indices of metabolic rate, such as general activity, heart rate, and strength of the daily heart rate rhythm and insulin sensitivity were restored to roughly 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to these metabolic effects of glucose feeding we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a roughly 33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared to fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial suppression of circulating FFA with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further suppression of metabolic function is likely an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

Efficiency of uphill locomotion in nocturnal and diurnal lizards

1996 ◽  
Vol 199 (3) ◽  
pp. 587-592 ◽  
Author(s):  
C Farley ◽  
M Emshwiller
Keyword(s):  
Body Mass ◽  
Low Cost ◽  
Minimum Cost ◽  
Mechanical Work ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
Unit Distance ◽  
Cost Of Locomotion ◽  
Average Body Mass ◽  
Average Body

Nocturnal geckos can walk on level ground more economically than diurnal lizards. One hypothesis for why nocturnal geckos have a low cost of locomotion is that they can perform mechanical work during locomotion more efficiently than other lizards. To test this hypothesis, we compared the efficiency of the nocturnal gecko Coleonyx variegatus (average body mass 4.2 g) and the diurnal skink Eumeces skiltonianus (average body mass 4.8 g) when they performed vertical work during uphill locomotion. We measured the rate of oxygen consumption when each species walked on the level and up a 50 slope over a range of speeds. For Coleonyx variegatus, the energetic cost of traveling a unit distance (the minimum cost of transport, Cmin) increased from 1.5 to 2.7 ml O2 kg-1 m-1 between level and uphill locomotion. For Eumeces skiltonianus, Cmin increased from 2.5 to 4.7 ml O2 kg-1 m-1 between level and uphill locomotion. By taking the difference between Cmin for level and uphill locomotion, we found that the efficiency of performing vertical work during locomotion was 37 % for Coleonyx variegatus and 19 % for Eumeces skiltonianus. The similarity between the 1.9-fold difference in vertical efficiency and the 1.7-fold difference in the cost of transport on level ground is consistent with the hypothesis that nocturnal geckos have a lower cost of locomotion than other lizards because they can perform mechanical work during locomotion more efficiently.

An Integrated Product-Process Design Approach Considering Material Selection and Product Assembly

2020 ◽  
Vol 19 (04) ◽  
pp. 675-699
Author(s):  
Abadi Chaimae ◽  
Abadi Asmae ◽  
Manssouri Imad
Keyword(s):  
Process Design ◽  
Material Selection ◽  
Minimum Cost ◽  
Integrated Approach ◽  
Design Approach ◽  
Manufacturing Processes ◽  
Design Requirements ◽  
Product Assembly ◽  
Manufacturing Parameters

Nowadays, industries face very strong challenges because of the high competitiveness between them. In fact, they are required to offer products with high quality and minimum cost in the minimum time. Since most of the characteristics and costs of the product and its manufacturing process are fixed in the design phase, this paper is focused on this strategic phase. Indeed, a new integrated product design approach is presented. It considers at the same time design requirements, materials characteristics, manufacturing parameters and the assembly process specifications. The developed approach is quantitative. Actually, the decision making is based on all its steps on objective and subjective indicators. To validate the integrated approach, a case study on the Schrader Robot is developed. This application allows to choose the most appropriate materials, manufacturing processes and assembly solution of its different components.

Compensatory effect of the heat increment of feeding on thermoregulation costs of white-tailed deer fawns in winter

1999 ◽  
Vol 77 (9) ◽  
pp. 1474-1485 ◽  
Author(s):  
Paul G Jensen ◽  
Peter J Pekins ◽  
James B Holter
Keyword(s):  
Metabolic Rate ◽  
Heat Production ◽  
Resting Metabolic Rate ◽  
Energetic Cost ◽  
Critical Temperatures ◽  
Metabolic Chamber ◽  
Heat Increment Of Feeding ◽  
Heat Increment ◽  
Minor Portion ◽  
A Minor

For northern white-tailed deer (Odocoileus virginianus) fawns, the energetic cost of thermoregulation (HcE) during severe winters can result in substantial catabolism of body-tissue reserves. The heat increment of feeding (HiE) has the potential to offset thermoregulatory energy expenditure that would otherwise require the catabolism of these reserves. During winters 1996 and 1997, we conducted 18 fasting and 18 on-feed heat-production trials using indirect respiration calorimetry in a metabolic chamber. Nonlinear regression analysis was used to estimate the lower critical temperatures (Tlc) and determine the fasting metabolic rate (FMR) and resting metabolic rate (RMR). Resulting models were used to calculate HiE, HcE, and percent substitution of HiE for HcE. For fawns fed a natural browse diet, estimated FMR and RMR were 352 and 490 kJ·kg body mass (BM)-0.75·d-1, respectively; this 40% increase in thermoneutral heat production reduced Tlc from -0.8 to -11.2°C between the fasted and fed states, respectively, and reduced HcE by 59% for fed fawns. For fawns fed a concentrate diet, estimated FMR and RMR were 377 and 573 kJ·kg BM-0.75·d-1, respectively. Level of browse intake had a significant effect on RMR andTlc. RMR was 12% higher for fawns on a high versus a low level of intake, and estimated Tlc was -15.6 and -5.8°C, respectively. Our data indicate that the energetic cost of thermoregulation is probably a minor portion of the energy budget of a healthy fawn consuming natural forage.

Fractal Fault Displacements: A Case Study from the Moray Firth, Scotland

1994 ◽  
pp. 105-119 ◽  
Author(s):  
Giles Pickering ◽  
Jonathan M. Bull ◽  
David J. Sanderson ◽  
Paul V. Harrison
Keyword(s):  
Moray Firth

scholarly journals Inferring Biological Mechanisms by Data-Based Mathematical Modelling: Compartment-Specific Gene Activation during Sporulation in Bacillus subtilis as a Test Case

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Dagmar Iber
Keyword(s):  
Bacillus Subtilis ◽  
Gene Activation ◽  
Experimental Information ◽  
Specific Gene ◽  
Model Parameters ◽  
Test Case ◽  
Detailed Model ◽  
Wide Range ◽  
Technical Advances ◽  
Biological Functionality

Biological functionality arises from the complex interactions of simple components. Emerging behaviour is difficult to recognize with verbal models alone, and mathematical approaches are important. Even few interacting components can give rise to a wide range of different responses, that is, sustained, transient, oscillatory, switch-like responses, depending on the values of the model parameters. A quantitative comparison of model predictions and experiments is therefore important to distinguish between competing hypotheses and to judge whether a certain regulatory behaviour is at all possible and plausible given the observed type and strengths of interactions and the speed of reactions. Here I will review a detailed model for the transcription factor , a regulator of cell differentiation during sporulation in Bacillus subtilis. I will focus in particular on the type of conclusions that can be drawn from detailed, carefully validated models of biological signaling networks. For most systems, such detailed experimental information is currently not available, but accumulating biochemical data through technical advances are likely to enable the detailed modelling of an increasing number of pathways. A major challenge will be the linking of such detailed models and their integration into a multiscale framework to enable their analysis in a larger biological context.

scholarly journals On Best Corrected Mixture Problems in Metallurgy: A Case Study

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
F. Dubeau ◽  
M. E. Ntigura Habingabwa
Keyword(s):  
Minimum Weight ◽  
Minimum Cost ◽  
The Third ◽  
Pareto Curve ◽  
Correction Problem ◽  
The Cost ◽  
Extreme Solutions ◽  
Weight Correction

We consider three simple mixture problems occurring in metallurgy. The first problem considered is the classic minimum cost mixture problem. For the second problem, we consider finding a correction to a given mixture, a premix, without considering the cost of this premix. We only consider the cost and the weight of the quantity used as a correction. We show that the minimum cost correction does not correspond to the minimum weight correction, and we built the Pareto curve that gives all intermediate solutions between these two extreme solutions. Finally, the third problem is the correction problem for a nonfree premix. The correction is done to obtain a minimum cost corrected mixture.

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