Abstract
We measured the thermoregulatory characteristics of a common, tropical murid rodent,
Sundamys muelleri
. Subcutaneous body temperatures and evaporative water loss increased at ambient ...temperatures above 33°C, but no increases in metabolic rate were observed as high as 38.2°C, indicating tropical rodents may be resilient as climate change progresses.
Abstract in Malay is available with online material.
Abstrak
Kami telah mengukur ciri‐ciri termoregulasi
Sundamys muelleri
iaitu tikus biasa murid tropika. Suhu badan subkutin dan kehilangan air melalui sejatan telah meningkat pada suhu sekeliling atas 33°C, namun demikian tiada peningkatan pada kadar metabolisma diperhatikan pada atas suhu 38.2°C. Hal ini menunjukkan bahawa roden tropika berkemungkin mempunyai daya tahan pada peningkatan perubahan iklim.
Aim
A central question in ecology has been that of why animal home ranges scale more steeply with body size than do metabolic rates. Yet, the generality of this notion has scarcely been tested in ...non‐model species like ectotherms, which have lower metabolic requirements than endotherms and which may, therefore, have different home range area requirements. Our aim was to examine how home range area scales with body size in snakes and to shed light on how other factors may shape home range area requirements in an understudied group of ectotherms.
Location
Global.
Time period
1984–2018.
Major taxon studied
Serpents.
Methods
We compiled and analysed a dataset of snake home ranges from the literature to evaluate how body size, sex, climate, foraging ecology, and biogeographic factors shape home range area requirements.
Results
Home range area scaled more gradually with body size in snakes (log‐linear slope of simple linear regression 0.72 with 95% confidence interval 0.48–0.96) than has been reported for mammals and birds, and instead more closely followed the scaling of metabolic rates with body size. Male snakes had larger home ranges than females and this difference increased as temperature increased at a study site, possibly from mate‐searching behaviour of males and greater ease reaching optimal body temperatures in warmer areas. Finally, home range area scaled more steeply for snakes that forage actively than for those that rely on sit‐and‐wait ambush foraging, a reflection of their foraging ecology.
Main conclusions
Our results question the general notion that animal home range areas scale more steeply with body size than does metabolism. Key distinctions in the energy demands of endotherms and ectotherms and their responses to those demands give rise to differing home range area requirements. More attention to non‐model species is needed when creating and evaluating ecological theory.
This article presents a statistically grounded method for the comparative analysis of polygonal masonry and the calculation of their architectural energetics. Four wall stretches of different Samnite ...hillforts (5th-3rd century BCE) have been recorded through 3D modelling to generate models suitable for calculating three variables (area, rectangularity and gap area) used for a comparative assessment of the different building techniques involved in their construction. This allowed the identification of masonry styles related to different costs of labor which were used to produce cross-regional energetic indexes suitable for the cost analysis of several hundred hillforts in south-central Italy. This formal and replicable approach to the cost analysis of polygonal masonry is not only suitable for analysing sites in Italy, but can also be applied to similar sites found widely in the Mediterranean.
•First method for statically grounded cross-regional comparison of polygonal masonry.•Identification of different masonry styles within single wall stretches.•Statistically derived calculation of architectural energetics of Italian polygonal masonry.•Transferable method for the analysis of other polygonal walls in the Mediterranean and beyond.•Full code and article are written in Quarto and available online.
•Unlike conventional BCC metals, small vacancy clusters do not prefer compact cluster configurations in the studied refractory high-entropy alloy.•The energetics of small vacancy clusters exhibits ...large site-to-site variation due to severe local lattice distortion and chemical complexity.•The degree of short-range order in the refractory high-entropy alloy has a significant impact on vacancy properties.•Small vacancy clusters in Nb0.75ZrTiV0.5 have a higher probability of dissociation compared to pure metals, which impacts void nucleation, vacancy diffusion, as well as long-term evolution of irradiation defects.
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The stability of small vacancy clusters including divacancy, trivacancy and tetravacancy has been studied in body-centered cubic high-entropy alloy Nb0.75ZrTiV0.5 in structures of random solid solution and short-range order by first-principles calculations and molecular dynamics simulations. Different from conventional body-centered cubic metals, the tightly bound configurations have a lower structural stability and are not preferred energetically in the studied high-entropy alloy. Instability of vacancy configurations leads to vacancy-atom exchanges that favor less compact configurations. The formation energy of small vacancy clusters is much smaller than its constituent elements of Nb and V due to the large structural adjustment induced by severe local lattice distortion. The difference in local lattice distortion and elemental arrangement in the vacancy neighborhood leads to significant site-to-site variation in vacancy cluster energy and configuration. The formation energy has a strong correlation with the local energy state of the vacancy configuration and the extent of structural relaxation. Compared to random solid solution, the structure of short-range order has a higher stability for the most compact cluster configurations and tends to have higher vacancy cluster formation energy. According to classical molecular dynamics simulations of cluster diffusion at high temperature, the studied high-entropy alloy has a higher probability of cluster dissociation compared to Nb and V. The unconventional energetics of small vacancy clusters is expected to have a profound impact on their generation, diffusion, dissociation, coalescence, as well as the defect microstructure evolution during irradiation.
•Functionalization of carbon nanotubes with polylithiated molecules.•Determination of structural and electronic properties.•Charge transfer mechanism through bader analysis.•Hydrogen storage ...characteristics of the functionalized systems.
In a quest to find optimum materials for efficient storage of clean energy, we have performed first principles calculations to study the structural and energy storage properties of one-dimensional carbon nanotubes (CNTs) functionalized with polylithiated molecules (PLMs). Van der Waals corrected calculations disclosed that various PLMs like CLi, CLi2, CLi3, OLi, OLi2, OLi3, bind strongly to CNTs even at high doping concentrations ensuring a uniform distribution of dopants without forming clusters. Bader charge analysis reveals that each Li in all the PLMs attains a partial positive charge and transform into Li+ cations. This situation allows multiple H2 molecules adsorbed with each Li+ through the polarization of incident H2 molecules via electrostatic and van der Waals type of interaction. With a maximum doping concentration, that is 3CLi2/3CLi3 and 3OLi2/3OLi3 a maximum of 36 H2 molecules could be adsorbed that corresponds to a reasonably high H2 storage capacity with the adsorption energies in the range of −0.33 to −0.15 eV/H2. This suits the ambient condition applications.
The aims of the study were to analyze metabolic power (MP) and MP derived parameters for different positions in the German Soccer Bundesliga and to evaluate if classification of high-intensity is ...more suited using the metabolic power approach instead of using traditional speed-based methods. 1,345 video match analysis (25 Hz) datasets from 380 players in 96 matches of the German first Bundesliga were gathered by an automatic player tracking system. Displacement (speed, acceleration, distance) and energetic (MP, energy expenditure) variables were determined. Intensity was classified utilizing conventional thresholds. Metabolic and running profiles were compared among six positional groups and between the halves of the match respectively (one-way ANOVA). Further, time spent, distance covered and energy expended at high speed (>15.5 km h
) and high acceleration (>2 m s
) were compared to those at high MP (>20 W kg
) (one-way ANOVA) for evaluating if metabolic power is more suited to describe intensity in team sports. Main findings are that central-attacking midfielders (CAM) and central midfielders (CM) expended more energy (CAM: 59.8 ± 4.2 kJ kg
; CM: 59.6 ± 3.6 kJ kg
) and covered more distance (CAM: 11,494 ± 765 m; CM: 11,445 ± 638 m) than all other positions (
< 0.001). In the whole group of players, less time (t) and less energy were expended (EE) in high speed (t: 302 ± 84 s; EE: 10.1 ± 2.9 kJ kg
) and at high acceleration zones (t: 147 ± 24 s; EE: 5.5 ± 1.2 kJ kg
) when compared to high MP zone (t: 617 ± 141 s; EE: 20.0 ± 4.4 kJ kg
) (
< 0.001). Furthermore, players covered more distance at high MP (2,464 ± 597 m) than at high speed (1,638 ± 458 m) and much less at high acceleration (359 ± 67 m) (
< 0.001). The higher activity profiles of CAM and CM compared to the other positions indicate the need for higher developed physiological performance in players of these positions. High intensity activities should be interpreted differently when using MP and displacement parameters as indicators of high intensity in soccer.
The objective of this study was to assess the effects of municipal wastewater treatment plant effluent on the energetics and stress response of rainbow darter (Etheostoma caeruleum). Male and female ...rainbow darter were collected upstream and downstream of the Waterloo WWTP in the Grand River watershed, ON, Canada. To assess the effects of wastewater treatment plant effluent on whole-body and tissue specific metabolic capacity, closed-chamber respirometry and muscle-enzyme activity analyses were performed. Plasma cortisol was also collected from fish before and after an acute air-exposure stressor to evaluate the cortisol stress response in fish exposed to additional stressors. Male and female rainbow darter collected downstream of the effluent had higher oxygen consumption rates, while differences in enzyme activities were primarily associated with sex rather than collection site. No impairment in the cortisol stress response between downstream and upstream fish was observed, however baseline cortisol levels in female fish from the downstream site were significantly higher compared to other baseline groups. Stress-induced cortisol levels were also higher in female fish from both sites when compared to their male counterparts. Overall, this study demonstrates that chronic exposure to WWTP effluent impacts whole-body metabolic performance. This study was also able to demonstrate that sex-differences are a key determinant of various metabolic changes in response to physiological stress, thereby, providing a novel avenue to be considered and further explored.
Least cost analysis (LCA) has emerged as a favored geospatial method used by archaeologists to model potential pathways of movement. To produce increasingly effective least cost models, we must more ...thoroughly consider the role that energetics have played throughout human history and understand how physiological conditions tied to energetics, such as fatigue, influence peoples’ decisions when moving. We illustrate this need by modeling a physically demanding case study from the American Southwest and demonstrate that the interpretive consequences of using time- versus energy-based cost function can have meaningful impacts on archaeological reconstructions of the past. Therefore, to better inform the selection of least cost functions in LCA, regardless of the material record in a specific study context, we present a theoretically informed strategy for classifying whether time or energy was a more pertinent cost to past movers by focusing on the role of fatigue and its influence on energetically efficient decision making.
Walking on compliant substrates requires more energy than walking on hard substrates but the biomechanical factors that contribute to this increase are debated. Previous studies suggest various ...causative mechanical factors, including disruption to pendular energy recovery, increased muscle work, decreased muscle efficiency and increased gait variability. We test each of these hypotheses simultaneously by collecting a large kinematic and kinetic dataset of human walking on foams of differing thickness. This allowed us to systematically characterize changes in gait with substrate compliance, and, by combining data with mechanical substrate testing, drive the very first subject-specific computer simulations of human locomotion on compliant substrates to estimate the internal kinetic demands on the musculoskeletal system. Negative changes to pendular energy exchange or ankle mechanics are not supported by our analyses. Instead we find that the mechanistic causes of increased energetic costs on compliant substrates are more complex than captured by any single previous hypothesis. We present a model in which elevated activity and mechanical work by muscles crossing the hip and knee are required to support the changes in joint (greater excursion and maximum flexion) and spatio-temporal kinematics (longer stride lengths, stride times and stance times, and duty factors) on compliant substrates.
