scholarly journals Torpor duration, more than temperature, is key to hummingbird nighttime energy savings

2018 ◽  
Author(s):  
A Shankar ◽  
RJ Schroeder ◽  
SM Wethington ◽  
CH Graham ◽  
DR Powers
Keyword(s):  
Energy Management ◽  
Energy Savings ◽  
Natural Habitat ◽  
Natural Environments ◽  
List Type ◽  
Laboratory Studies ◽  
Ambient Temperatures ◽  
Torpor Bout ◽  
Bout Duration ◽  
Temperature Regimes

ABSTRACTTorpor is an important energy saving strategy in small endotherms, but it has been insufficiently studied in natural field conditions. Building on what we know from laboratory studies, we compared torpor use across hummingbird species and different natural temperature regimes to explore predominant hypotheses about torpor use and evaluate the possible effects of environmental variation on energy management.We found that the probability of an individual entering torpor was correlated with mass and unrelated to nighttime temperature, and that hummingbirds at both warm tropical and cooler temperate sites used torpor.Energy savings in torpor were maximized as ambient temperatures approached a species’ minimum body temperature consistent with laboratory studies; energy savings ranged between 65-92% of energy per hour in torpor compared to normothermy.However, variation in total nighttime energy expenditure was more significantly influenced by torpor bout duration than by the variation in energy savings in torpor.Our results show that a small endotherm’s nighttime energy management in its natural habitat is more affected by torpor bout duration, which is linked to photoperiod, than by temperature. This result suggests that in their natural environments, hummingbirds are able to save energy in torpor across a range nighttime temperature, indicating that they may have sufficient physiological flexibility to tolerate climatic variation.

scholarly journals Implicating a Temperature-Dependent Clock in the Regulation of Torpor Bout Duration in Classic Hibernation

2018 ◽  
Vol 33 (6) ◽  
pp. 626-636 ◽  
Author(s):  
André Malan ◽  
Dominique Ciocca ◽  
Etienne Challet ◽  
Paul Pévet
Keyword(s):  
Winter Season ◽  
The Body ◽  
Circadian Clocks ◽  
Subjective Time ◽  
Daily Torpor ◽  
Thermal Compensation ◽  
Temperature Dependent ◽  
Ambient Temperatures ◽  
Torpor Bout ◽  
Bout Duration

Syrian hamsters may present 2 types of torpor when exposed to ambient temperatures in the winter season, from 8°C to 22°C (short photoperiod). The first is daily torpor, which is controlled by the master circadian clock of the body, located in the SCN. In this paper, we show that daily torpor bout duration is unchanged over the 8°C to 22°C temperature range, as predicted from the thermal compensation of circadian clocks. These findings contrast with the second type of torpor: multi-day torpor or classic hibernation. In multi-day torpor, bout duration increases as temperature decreases, following Arrhenius thermodynamics. We found no evidence of hysteresis from metabolic inhibition and the process was thus reversible. As a confirmation, at any temperature, the arousal from multi-day torpor occurred at about the same subjective time given by this temperature-dependent clock. The temperature-dependent clock controls the reduced torpor metabolic rate while providing a reversible recovery of circadian synchronization on return to euthermy.

Effect of Iron Limitation on the Ultrastructure of Agmenellum Quadruplicatum

1981 ◽  
Vol 39 ◽  
pp. 410-411
Author(s):  
L. P. Hardie ◽  
D. L. Balkwill ◽  
S. E. Stevens
Keyword(s):  
Growth Medium ◽  
Green Alga ◽  
Natural Habitat ◽  
Iron Limitation ◽  
Natural Environments ◽  
Blue Green Alga ◽  
Marine Cyanobacterium ◽  
Natural Systems ◽  
Thin Sectioning ◽  
Agmenellum Quadruplicatum

Agmenellum quadruplicatum is a unicellular, non-nitrogen-fixing, marine cyanobacterium (blue-green alga). The ultrastructure of this organism, when grown in the laboratory with all necessary nutrients, has been characterized thoroughly. In contrast, little is known of its ultrastructure in the specific nutrient-limiting conditions typical of its natural habitat. Iron is one of the nutrients likely to limit this organism in such natural environments. It is also of great importance metabolically, being required for both photosynthesis and assimilation of nitrate. The purpose of this study was to assess the effects (if any) of iron limitation on the ultrastructure of A. quadruplicatum. It was part of a broader endeavor to elucidate the ultrastructure of cyanobacteria in natural systemsActively growing cells were placed in a growth medium containing 1% of its usual iron. The cultures were then sampled periodically for 10 days and prepared for thin sectioning TEM to assess the effects of iron limitation.

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.

Aspects of the Water, Electrolyte and Carbohydrate Physiology of the Silvereye, Zosterops Lateralis (Aves).

1983 ◽  
Vol 31 (5) ◽  
pp. 695 ◽  
Author(s):  
IJ Rooke ◽  
SD Bradshaw ◽  
RA Langworthy
Keyword(s):  
Natural Habitat ◽  
Tritiated Water ◽  
Free Water ◽  
Laboratory Studies ◽  
Turnover Rates ◽  
Natural Habitats ◽  
Water Influx ◽  
Zosterops Lateralis ◽  
Total Body ◽  
Free Ranging

Total body water content (TBW) and TBW turnover were measured by means of tritiated water (HTO) in free-ranging populations of silvereyes, Zosterops lateralis, near Margaret River, W.A. Birds were studied in their natural habitats during spring and summer, and compared with a vineyard population in summer. In the natural habitat TBW content was found to be 77.6% in spring, which was not significantly different from that measured in summer (78.3%). Birds in vineyards in summer, however, were dehydrated, with a TBW content of 69.4%. Calculated rates of water influx for spring, summer and summer vineyards birds were 1.44,2.20 and 0.65 ml g.day-' respectively. These water turnover rates are much higher than those of any other bird yet studied. Dehydration was marked in the vineyard birds, with a significantly lower TBW content and an average net water loss of 0.63 ml day-'. Laboratory studies showed that silvereyes have a low tolerance to sodium loading. Their tolerance is, however, quite adequate for them to drink the most concentrated free water available to them in the field. Ingestion of concentrated sugar solutions of up to 25% did not provoke an osmotic diuresis and thus cannot account for the dehydration and negative water balance of vineyard birds.

scholarly journals Energy management in sensor networks

2012 ◽  
Vol 370 (1958) ◽  
pp. 52-67 ◽  
Author(s):  
John A. Stankovic ◽  
Tian He
Keyword(s):  
Energy Consumption ◽  
Sensor Networks ◽  
Energy Management ◽  
Large Scale ◽  
Energy Savings ◽  
Time Synchronization ◽  
Media Access Control ◽  
Media Access ◽  
Energy Aware ◽  
Holistic View

This paper presents a holistic view of energy management in sensor networks. We first discuss hardware designs that support the life cycle of energy, namely: (i) energy harvesting, (ii) energy storage and (iii) energy consumption and control. Then, we discuss individual software designs that manage energy consumption in sensor networks. These energy-aware designs include media access control, routing, localization and time-synchronization. At the end of this paper, we present a case study of the VigilNet system to explain how to integrate various types of energy management techniques to achieve collaborative energy savings in a large-scale deployed military surveillance system.

People or Systems: Does Productivity Enhancement Matter More than Energy Management in LEED Certified Buildings?

2021 ◽  
Vol 13 (24) ◽  
pp. 13863
Author(s):  
Yana Akhtyrska ◽  
Franz Fuerst
Keyword(s):  
Energy Consumption ◽  
Energy Management ◽  
Energy Use ◽  
Management Practices ◽  
Energy Savings ◽  
Occupant Comfort ◽  
Energy Use Intensity ◽  
Using Data ◽  
Advanced Metering ◽  
The Impact

This study examines the impact of energy management and productivity-enhancing measures, implemented as part of LEED Existing Buildings Operations and Management (EBOM) certification, on source energy use intensity and rental premiums of office spaces using data on four major US markets. Energy management practices, comprised of commissioning and advanced metering, may reduce energy usage. Conversely, improving air quality and occupant comfort in an effort to increase worker productivity may in turn lead to higher overall energy consumption. The willingness to pay for these features in rental office buildings is hypothesised to depend not only on the extent to which productivity gains enhance the profits of a commercial tenant but also on the lease arrangements for passing any energy savings to the tenant. We apply a difference-in-differences method at a LEED EBOM certification group level and a multi-level modelling approach with a panel data structure. The results indicate that energy management and indoor environment practices have the expected effect on energy consumption as described above. However, the magnitude of the achieved rental premiums appears to be independent of the lease type.

scholarly journals Perancangan sistem manajemen energi pada industri manufaktur berdasarkan ISO 50001:2011

2020 ◽  
Vol 12 (1) ◽  
pp. 88
Author(s):  
Taufik Ridwan
Keyword(s):  
Energy Management ◽  
Distribution System ◽  
Management System ◽  
Manufacturing Industry ◽  
Energy Savings ◽  
Energy Performance ◽  
Energy Management System ◽  
Steam Boiler ◽  
System Implementation ◽  
Self Assessment

As one manufacturing industry with a large level of energy consumption makes energy management mandatory applied at PT. XYZ, the purpose of this research is to design energy management system implementation strategy in PT. XYZ based on ISO 50001. Started by self assessment and by collecting data on the use of primary energy sources in the company, followed by processing and analyzing using simple linear regression. The self assessment results show 38% of the total value’s completeness of existing program in the clause of ISO 50001. From the processing and analyzing’s energy usage showed energy baseline and energy performance indicators (EnPI) of the company. The result of research is identifies and proposes the potential of energy savings in air compressor distribution system, steam boiler distribution, and electrical distribution system with good housekeeping, control system, and modification, proposes the energy management system implementation based on Deming’s PDCA cycle, and continued by recommending roadmap towards the implementation of energy management systems. 

scholarly journals Review of existing energy management standards and possibilities for its introduction in Serbia

2010 ◽  
Vol 14 (3) ◽  
pp. 613-623 ◽  
Author(s):  
Dubravka Jelic ◽  
Dusan Gordic ◽  
Milun Babic ◽  
Davor Koncalovic ◽  
Vanja Sustersic
Keyword(s):  
Best Practices ◽  
Energy Management ◽  
Energy Efficient ◽  
Management Practices ◽  
Energy Savings ◽  
Management Strategies ◽  
Current Status ◽  
Positive Effects ◽  
Management Standards ◽  
Current State

Until recent times, energy management practices primarily consisted in replacing inefficient equipment and then using any number of methods to estimate obtained savings. Experience shows that positive effects of energy efficient improvements were decreased over time. There have been significant efforts over the last decade to define appropriate standards and best practices and implement the consistent energy management system to increase and maintain the energy savings. The knowledge gained from thousands of energy efficient projects is driving a transition from traditional tactical practice (one-time "build and forget" projects) to energy management strategies proposed and endorsed by a number of international organizations. The current status of internationally developed energy management standards, including an analysis of their shared features and differences is presented in this paper. The purpose of the analysis is to describe the current state of ?best practices? for this emerging area of energy efficiency policymaking in order to study the possibility of implementation of energy management standards in Serbia and to estimate the effects and the potential for energy saving that would be made by its implementation.

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