Time patterns and metabolic rates of natural torpor in the Richardson's ground squirrel

1979 ◽  
Vol 57 (1) ◽  
pp. 149-155 ◽  
Author(s):  
Lawrence C. H. Wang
Keyword(s):  
Ground Squirrel ◽  
Energy Savings ◽  
Time Budget ◽  
Metabolic Rates ◽  
Energetic Costs ◽  
Ambient Temperatures ◽  
Spermophilus Richardsonii ◽  
Time Patterns ◽  
Metabolic Costs ◽  
Metabolic Data

Using radiotelemetry for body-temperature sensing in field animals, torpor season in the Richardson's ground squirrel (Spermophilus richardsonii) was found to commence from mid-July in adults and mid-September in juveniles and to terminate for both groups in mid-March. The duration of torpor averaged 3 and 4.3 days in July and August and gradually lengthened to 19.1 days in January, after which it shortened to 14.2 and 6.0 days in February and March. The duration of intertorpor homeothermy ranged from 300 to 1500 min. The metabolic costs associated with entry into torpor, during torpor, arousal from torpor, and intertorpor were quantified in the laboratory at ambient temperatures comparable with those observed in burrow. Applying these metabolic data to the time budget for torpor in field animals, the estimated seasonal energetic costs for entry into torpor averaged 12.8% of total, deep torpor 16.6%, arousal from torpor 19.0%, and intertorpor 51.6%. The monthly energy savings by utilization of torpor ranged from 38.8% in July and 51.2% in March to between 81.6 and 96.0% between August and February. For the whole torpor season, which extended 8 months, the energy savings amounted to 87.8%.

Investigation of Thermal Effects in Direct Driven Hydraulic System for Off-Road Machinery

2016 ◽  
Author(s):  
Niko Karlén ◽  
Tatiana Minav ◽  
Matti Pietola
Keyword(s):  
Energy Efficiency ◽  
Hydraulic System ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Hydraulic Model ◽  
Energy Losses ◽  
Total Efficiency ◽  
Ambient Temperatures ◽  
Wheel Loaders ◽  
Save Energy

Several types of off-road machinery, such as industrial trucks, forklifts, excavators, mobile cranes, and wheel loaders, are set to be operated in environments which can differ considerably from each other. This sets certain limits for both the drive transmissions and working hydraulics of these machines. The ambient temperature must be taken into account when selecting the hydraulic fluid since the viscosity and density of the fluid are changing at different operating temperatures. In addition to the temperature, energy efficiency can also be a problem in off-road machinery. In most off-road machines, diesel engines are employed to produce mechanical energy. However, there are energy losses during the working process, which causes inefficiency in produced energy. For better energy efficiency, hybridization in off-road machinery is an effective method to decrease fuel consumption and increase energy savings. One of the possible methods to save energy with hybrids is energy regeneration. However, it means that the basic hydraulic system inside off-road machinery needs to be modified. One solution for this is to utilize zonal or decentralized approach by means of direct driven hydraulic (DDH) system. This paper aims to investigate a DDH system for off-road machinery by means of modelling and analyzing the effect of the temperature. In the direct-driven hydraulic system, the actuator is controlled directly by the hydraulic pump which is operated by the electric motor. Specifically, it is a valveless closed-loop hydraulic system. Thus, there will be no energy losses caused by the valves, and the total efficiency is assumed to be significantly higher. In order to examine the DDH system, a thermo-hydraulic model was created. Additionally, a thermal camera was utilized in order to illustrate the temperature changes in the components of the DDH system. To reproduce the action of the system in different circumstances DDH system was run at different ambient temperatures, and the component temperatures in the system were measured and saved for the analysis. The thermo hydraulic model was proven capable to follow the general trend of heating up.

Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations

2017 ◽  
Vol 122 (4) ◽  
pp. 976-984 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Lower Limb ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Metabolic Rates ◽  
Distance Running ◽  
Cost Of Transport ◽  
Leg Stiffness ◽  
Metabolic Costs ◽  
In Series ◽  
Reaction Forces

Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer’s recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer’s recommended and ± 1) and heights (International Paralympic Committee’s maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = −0.139; P = 0.044) and 1E90 Sprinter prostheses (β = −0.176; P = 0.009) reduced net metabolic costs by 4.3–4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the metabolic rates and biomechanics of five athletes with bilateral transtibial amputations while running with different prosthetic configurations. The metabolic cost of running for these athletes is minimized by using an optimal prosthetic model and reducing prosthetic stiffness. The metabolic cost of running was independent of prosthetic height, suggesting that longer legs are not advantageous for distance running. Moreover, the in-series prosthetic stiffness governs the leg stiffness of athletes with bilateral leg amputations.

Data Analysis and Presentation

2018 ◽  
pp. 177-192
Author(s):  
John R. B. Lighton
Keyword(s):  
Data Analysis ◽  
Temperature Effects ◽  
Final Analysis ◽  
Analysis Of Covariance ◽  
Neutral Zone ◽  
Metabolic Rates ◽  
Treatment Groups ◽  
Metabolic Data ◽  
Interspecific Comparisons ◽  
Selection Of

This chapter discusses ways of analyzing and presenting metabolic data while avoiding common mistakes. Topics covered include vital information often omitted from manuscripts; how to analyze the allometry of metabolic rate on mass; the mistake of reporting mass-specific or “mass-independent” metabolic rates; methods for quantifying differences between treatment groups by analysis of covariance; the importance of phylogeny in interspecific comparisons; the importance of the temperature at which measurements are made, including mammals (the thermal neutral zone); the necessity of leaving an “audit trail” from raw data through to final analysis; analyzing temperature effects such as Q10 correctly; and the proper selection of metabolic data.

scholarly journals Temperature alters the physiological response of spiny lobsters under predation risk

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Felipe A Briceño ◽  
Quinn P Fitzgibbon ◽  
Elias T Polymeropoulos ◽  
Iván A Hinojosa ◽  
Gretta T Pecl
Keyword(s):  
Climate Change ◽  
Predation Risk ◽  
Environmental Changes ◽  
Environmental Drivers ◽  
Climate Change Scenarios ◽  
Metabolic Rates ◽  
Energetic Costs ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Spiny Lobsters

Abstract Predation risk can strongly shape prey ecological traits, with specific anti-predator responses displayed to reduce encounters with predators. Key environmental drivers, such as temperature, can profoundly modulate prey energetic costs in ectotherms, although we currently lack knowledge of how both temperature and predation risk can challenge prey physiology and ecology. Such uncertainties in predator–prey interactions are particularly relevant for marine regions experiencing rapid environmental changes due to climate change. Using the octopus (Octopus maorum)–spiny lobster (Jasus edwardsii) interaction as a predator–prey model, we examined different metabolic traits of sub adult spiny lobsters under predation risk in combination with two thermal scenarios: ‘current’ (20°C) and ‘warming’ (23°C), based on projections of sea-surface temperature under climate change. We examined lobster standard metabolic rates to define the energetic requirements at specific temperatures. Routine metabolic rates (RMRs) within a respirometer were used as a proxy of lobster activity during night and day time, and active metabolic rates, aerobic scope and excess post-exercise oxygen consumption were used to assess the energetic costs associated with escape responses (i.e. tail-flipping) in both thermal scenarios. Lobster standard metabolic rate increased at 23°C, suggesting an elevated energetic requirement (39%) compared to 20°C. Unthreatened lobsters displayed a strong circadian pattern in RMR with higher rates during the night compared with the day, which were strongly magnified at 23°C. Once exposed to predation risk, lobsters at 20°C quickly reduced their RMR by ~29%, suggesting an immobility or ‘freezing’ response to avoid predators. Conversely, lobsters acclimated to 23°C did not display such an anti-predator response. These findings suggest that warmer temperatures may induce a change to the typical immobility predation risk response of lobsters. It is hypothesized that heightened energetic maintenance requirements at higher temperatures may act to override the normal predator-risk responses under climate-change scenarios.

scholarly journals Nocturnal Hypothermia in Seasonally Acclimatized Mountain Chickadees and Juniper Titmice

The Condor ◽  
2005 ◽  
Vol 107 (1) ◽  
pp. 151-155 ◽  
Author(s):  
Sheldon J. Cooper ◽  
James A. Gessaman
Keyword(s):  
Body Temperature ◽  
Body Mass ◽  
Energy Savings ◽  
Ambient Temperatures ◽  
Energy Expenditures ◽  
Poecile Gambeli ◽  
Daily Energy ◽  
Para Determinar ◽  
Mountain Chickadees

AbstractWe measured body temperature of Mountain Chickadees (Poecile gambeli) and Juniper Titmice (Baeolophus ridgwayi) at different times of day and under a range of ambient temperatures in order to determine the use of nocturnal hypothermia in seasonally acclimatized small passerines. Our findings show both species used nocturnal hypothermia year-round. Depth of hypothermia was inversely correlated to body mass in Juniper Titmice but not in Mountain Chickadees. In both species, depth of hypothermia did not vary seasonally but nocturnal body temperature was regulated 3–11°C lower than daytime values. Nocturnal energy savings range from 7%–50% in chickadees and from 10%–28% in titmice. These nocturnal energy savings translate into ecologically important reductions in daily energy expenditures for these two species.Hipotermia Nocturna en Individuos de Poecile gambeli y Baeolophus ridgwayi Aclimatados EstacionalmenteResumen. Medimos la temperatura corporal de Poecile gambeli y Baeolophus ridgwayi a diferentes horas del día y en un rango de temperaturas ambientales para determinar el uso de hipotermia nocturna en pequeñas aves paserinas aclimatadas estacionalmente. Nuestros resultados muestran que ambas especies presentaron hipotermia nocturna durante todo el año. La profundidad de la hipotermia estuvo inversamente correlacionada con la masa corporal en B. ridgwayi, pero no en P. gambeli. En ambas especies, la profundidad de la hipotermia no varió estacionalmente, pero la temperatura corporal nocturna estuvo regulada 3–11°C por debajo de los valores diurnos. El ahorro nocturno de energía varió entre 7%–50% en P. gambeli y entre 10%–28% en B. ridgwayi. Estos ahorros nocturnos de energía se tradujeron en reducciones ecológicamente importantes en los gastos diarios de energía para ambas especies.

scholarly journals Subtropical mouse-tailed bats use geothermally heated caves for winter hibernation

2015 ◽  
Vol 282 (1804) ◽  
pp. 20142781 ◽  
Author(s):  
Eran Levin ◽  
Brit Plotnik ◽  
Eran Amichai ◽  
Luzie J. Braulke ◽  
Shmulik Landau ◽  
...  
Keyword(s):  
High Temperature ◽  
Skin Temperature ◽  
Metabolic Rates ◽  
Evaporative Water ◽  
Open Flow ◽  
Ambient Temperatures ◽  
Northern Edge ◽  
Average Skin ◽  
World Distribution ◽  
Winter Hibernation

We report that two species of mouse-tailed bats ( Rhinopoma microphyllum and R. cystops ) hibernate for five months during winter in geothermally heated caves with stable high temperature (20°C). While hibernating, these bats do not feed or drink, even on warm nights when other bat species are active. We used thermo-sensitive transmitters to measure the bats’ skin temperature in the natural hibernacula and open flow respirometry to measure torpid metabolic rate at different ambient temperatures ( T a , 16–35°C) and evaporative water loss (EWL) in the laboratory. Bats average skin temperature at the natural hibernacula was 21.7 ± 0.8°C, and no arousals were recorded. Both species reached the lowest metabolic rates around natural hibernacula temperatures (20°C, average of 0.14 ± 0.01 and 0.16 ± 0.04 ml O 2 g −1 h −1 for R. microphyllum and R. cystops , respectively) and aroused from torpor when T a fell below 16°C. During torpor the bats performed long apnoeas (14 ± 1.6 and 16 ± 1.5 min, respectively) and had a very low EWL. We hypothesize that the particular diet of these bats is an adaptation to hibernation at high temperatures and that caves featuring high temperature and humidity during winter enable these species to survive this season on the northern edge of their world distribution.

scholarly journals Basal metabolic rate of birds is associated with habitat temperature and precipitation, not primary productivity

2006 ◽  
Vol 274 (1607) ◽  
pp. 287-293 ◽  
Author(s):  
Craig R White ◽  
Tim M Blackburn ◽  
Graham R Martin ◽  
Patrick J Butler
Keyword(s):  
Metabolic Rate ◽  
Primary Productivity ◽  
Generalized Least Squares ◽  
Arid Environments ◽  
Metabolic Rates ◽  
Habitat Temperature ◽  
Ambient Temperatures ◽  
Temperature And Precipitation ◽  
The World ◽  
The Relationship

A classic example of ecophysiological adaptation is the observation that animals from hot arid environments have lower basal metabolic rates (BMRs, ml O 2  min −1 ) than those from non-arid (luxuriant) ones. However, the term ‘arid’ conceals within it a multitude of characteristics including extreme ambient temperatures ( T a , °C) and low annual net primary productivities (NPPs, g C m −2 ), both of which have been shown to correlate with BMR. To assess the relationship between environmental characteristics and metabolic rate in birds, we collated BMR measurements for 92 populations representing 90 wild-caught species and examined the relationships between BMR and NPP, T a , annual temperature range ( T r ), precipitation and intra-annual coefficient of variation of precipitation ( P CV ). Using conventional non-phylogenetic and phylogenetic generalized least-squares approaches, we found no support for a relationship between BMR and NPP, despite including species captured throughout the world in environments spanning a 35-fold range in NPP. Instead, BMR was negatively associated with T a and T r , and positively associated with P CV .

scholarly journals Improvements in CO2 Booster Architectures with Different Economizer Arrangements

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1271 ◽  
Author(s):  
J. Catalán-Gil ◽  
L. Nebot-Andrés ◽  
D. Sánchez ◽  
R. Llopis ◽  
R. Cabello ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Energy Savings ◽  
Ambient Temperatures ◽  
Phase Out

CO2 transcritical booster architectures are widely analyzed to be applied in centralized commercial refrigeration plants in consonance with the irrevocable phase-out of HFCs. Most of these analyses show the limitations of CO2 cycles in terms of energy efficiency, especially in warm countries. From the literature, several improvements have been proposed to raise the booster efficiency in high ambient temperatures. The use of economizers is an interesting technique to reduce the temperature after the gas cooler and to improve the energy efficiency of transcritical CO2 cycles. The economizer cools down the high pressure’s line of CO2 by evaporating the same refrigerant extracted from another point of the facility. Depending on the extraction point, some configurations are possible. In this work, different booster architectures with economizers have been analyzed and compared. From the results, the combination of the economizer with the additional compressor allows obtaining energy savings of up to 8.5% in warm countries and up to 4% in cold countries with regard to the flash-by-pass arrangement and reduce the volumetric displacement required of the MT compressors by up to 37%.

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