scaling relationships
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2022 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Xiongwen Chen ◽  
Kimberly A. Bowman ◽  
Zhuo Chen

Plants automatically control the size variations in organs to achieve efficient exploitation of resources. However, it is unclear whether the scaling relationships of plant organs share a similar character for different individuals under varied micro-conditions (e.g., light and soil water). We conducted a case study of the lengths of staghorn sumac leaves and longleaf pine cone scales to test the relationships. Our results indicated that although there were size variations, there existed power laws of frequency in the lengths of staghorn sumac leaves and longleaf pine cone scales. The exponents differed but were positively correlated with the minimum length of leaves or cone scales. Taylor’s Law existed in the lengths of cone scales and some tree leaves, and scale break was observed. This study provides new information on scaling relationships and self-organization in the patterns of tree parts arrangement. Taylor’s Law may be used to detect minor changes in the growth regime.


2022 ◽  
Vol 9 (1) ◽  
Author(s):  
C. D. Perl ◽  
Z. B. Johansen ◽  
V. W. Jie ◽  
Z. Moradinour ◽  
M. Guiraud ◽  
...  

Differences in organ scaling among individuals may play an important role in determining behavioural variation. In social insects, there are well-documented intraspecific differences in colony behaviour, but the extent that organ scaling differs within and between colonies remains unclear. Using 12 different colonies of the bumblebee Bombus terrestris , we aim to address this knowledge gap by measuring the scaling relationships between three different organs (compound eyes, wings and antennae) and body size in workers . Though colonies were exposed to different rearing temperatures, this environmental variability did not explain the differences of the scaling relationships. Two colonies had differences in wing versus antenna slopes, three colonies showed differences in wing versus eye slopes and a single colony has differences between eye versus antenna slopes. There are also differences in antennae scaling slopes between three different colonies, and we present evidence for putative trade-offs in morphological investment. We discuss the utility of having variable scaling among colonies and the implication for understanding variability in colony fitness and behaviour.


Plasma ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 12-29
Author(s):  
Ting Liu ◽  
Igor Timoshkin ◽  
Mark P. Wilson ◽  
Martin J. Given ◽  
Scott J. MacGregor

The present paper investigates the breakdown characteristics—breakdown voltage, with breakdown occurring on the rising edge of the applied HV impulses, and time to breakdown—for gases of significance that are present in the atmosphere: air, N2 and CO2. These breakdown characteristics have been obtained in a 100 µm gap between an HV needle and plane ground electrode, when stressed with sub-µs impulses of both polarities, with a rise time up to ~50 ns. The scaling relationships between the reduced breakdown field Etip/N and the product of the gas number density and inter-electrode gap, Nd, were obtained for all tested gases over a wide range of Nd values, from ~1020 m−2 to ~1025 m−2. The breakdown field-time to breakdown characteristics obtained at different gas pressures are presented as scaling relationships of Etip/N, Nd, and Ntbr for each gas, and compared with data from the literature.


Mathematics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Lei Li ◽  
Zhong Luo ◽  
Fengxia He ◽  
Zhaoye Qin ◽  
Yuqi Li ◽  
...  

The dual-rotor system has been widely used in aero-engines and has the characteristics of large axial size, the interaction between the high-pressure rotor and low-pressure rotor, and stiffness nonlinearity of bolted joints. However, the testing of a full-scale dual-rotor system is expensive and time-consuming. In this paper, the scaling relationships for the dual-rotor system with bolted joints are proposed for predicting the responses of full-scale structure, which are developed by generalized and fundamental equations of substructures (shaft, disk, and bolted joints). Different materials between prototype and model are considered in the derived scaling relationships. Moreover, the effects of bolted joints on the dual-rotor system are analyzed to demonstrate the necessity for considering bolted joints in the similitude procedure. Furthermore, the dynamic characteristics for different working conditions (low-pressure rotor excitation, high-pressure rotor excitation, two frequency excitations, and counter-rotation) are predicted by the scaled model made of a relatively cheap material. The results show that the critical speeds, vibration responses, and frequency components can be predicted with good accuracy, even though the scaled model is made of different materials.


2021 ◽  
Author(s):  
Jeff W. Atkins ◽  
Jonathan A. Walter ◽  
Atticus E. L. Stovall ◽  
Robert T. Fahey ◽  
Christopher M. Gough

Author(s):  
Mingxi Shen ◽  
Ting Fong May Chui

Abstract Recent studies have reached inconsistent conclusions from scaling analysis about whether flood or extreme precipitation is more sensitive to warming climate. To explain the reasons behind the inconsistency, here we first used scaling analysis to illustrate how extreme daily precipitation and streamflow scale with daily air temperature across the Continental United States (CONUS). We found both similar and opposite scaling in extreme precipitation and streamflow. It indicates based on scaling analysis, the sensitivity of extreme streamflow to warming climate can be either similar, higher or lower to that of extreme precipitation. We further explored why there are contrasting scaling relationships in the CONUS. Generally, the similar scaling was found in regions where the timing of extreme precipitation and streamflow is correspondent, as well as with similar temporal evolution in extreme event timing and magnitude, e.g., the west coast and southern plains, implying extreme precipitation is the dominant driver of local floods. However, for regions with dissimilar scaling in extreme precipitation and streamflow (e.g., Rocky Mountains, southern plains), the characteristics of extreme streamflow show large difference to those of extreme precipitation, and the temporal evolution of extreme streamflow timing and magnitude are more correlated with factors/processes such as soil moisture and snowmelt. This study reflects that the contrasting scaling relationships of extreme precipitation and streamflow are oriented from the local hydro-climatological specifics. Using scaling analysis to compare the sensitivity of extreme precipitation and streamflow to warming climate is not suitable. Instead, we should focus more on local flood generating mechanisms or flood drivers when investigating floods in the changing climate.


2021 ◽  
Author(s):  
◽  
Allan Burne

<p><b>The detrimental effects of invasive species on recipient taxa are most frequently reported in terms of displacement or extinction. However, there may be other less obvious effects. For example, a reduction in resource availability mediated by a novel competitor may affect growth and development in recipient species. The cost of aggressive competitive interactions with invasives may promote niche shifts or altered spatial distribution to minimise competition, and intense predation by exotic species may result in a reduced effective population size with a concomitant reduction in genetic diversity. In this thesis I examined the sub-lethal effects of varying densities of the invasive competitor and predator Vespula vulgaris on the morphology, behaviour, population genetics and spatial distribution of the New Zealand endemic ant Prolasius advenus.</b></p> <p>The restriction of food resources can result in reduced worker size and altered scaling relationships of adult body parts in ants. Measurements of nine morphological characters from P. advenus worker ants collected from sites of varying wasp density revealed that workers were significantly smaller where there were more wasps. I also found evidence of allometric scaling relationships among body parts, which varied between areas of high and low wasp density. In particular the scaling relationships between the abdominal segments and overall size were found to be weaker where there were more wasps. This scaling variation resulted in ant workers with proportionally smaller abdomens in areas where wasps were most abundant, which might reduce their resource gathering and defensive efficiency.</p> <p>I tested the hypothesis that tasks performed by workers would be size correlated. In the presence of high densities of wasps, honeydew collection and brood care was undertaken by larger workers, whereas foraging in leaf litter was undertaken by smaller workers. In contrast, no relationship was found between task and worker size where wasp densities were lower. I suggest that in addition to increased efficiency in the collection of liquid carbohydrate resources larger workers may also serve a defensive role. I also tested the hypothesis that where the exclusively diurnal wasps were most abundant P. advenus workers would minimise potential competitive interactions by foraging predominantly at night. However, P. advenus were found to forage as much or more by day in the presence of high densities of wasps and to forage more nocturnally where wasps were sparse. Increasing the number of foragers by day may improve P. advenus’ competitive ability with wasps, but has the potential to come at the cost of other nest functions, energetic gains and increased worker mortality. Competitive mechanisms might influence ant population genetics, but wasps have also been shown to prey on dispersing ant queens. Analysis of microsatellite DNA markers revealed evidence of a genetic bottleneck in P. advenus populations where invasive predatory wasps have persisted at high population densities for more than twenty years. Ant populations at all wasp densities displayed significant heterozygote deficit, which may indicate that even at comparatively low densities predation by wasps has a detrimental effect on P. advenus genetic diversity. Alternatively, the observed heterozygote deficit may be the result of limited dispersal, population substructure or the peculiarities of the ant species‟ mating system. An examination of the broader population genetic structure of P. advenus from the seven sites sampled indicated that they were derived from two distinct populations. However, no individual assigned entirely to either population suggesting either some remaining admixture between the two populations or that they are derived from a common ancestral population.</p> <p>Finally I examined the effects of increasing wasp density, honeydew availability and habitat diversity on the distribution of P. advenus. Prolasius advenus nests tended to be smaller and populations displayed less variation in nest size where wasp densities were highest, which could indicate reduced longevity. Nest distribution was overdispersed relative to both con-and hetero-specific neighbours in high wasp density sites, but apparently randomly distributed in low wasp density sites. Both wasp and ant nest densities were greatest where honeydew was most abundant and plant diversity was lowest. These results suggest that intra- and inter-specific competition in combination with resource and nest site availability influences P. advenus nest distribution.</p> <p>Competition and predation by invasive species may influence recipient species‟ morphology, behaviour, genetic diversity and spatial distribution over a comparatively short period of time. These effects are much more subtle than under situations of direct predation. Such effects may not be immediately obvious in terms of abundance, but have potential long-term implications for the fitness and persistence of P. advenus in the presence of high densities of wasps.</p>


2021 ◽  
Author(s):  
◽  
Allan Burne

<p><b>The detrimental effects of invasive species on recipient taxa are most frequently reported in terms of displacement or extinction. However, there may be other less obvious effects. For example, a reduction in resource availability mediated by a novel competitor may affect growth and development in recipient species. The cost of aggressive competitive interactions with invasives may promote niche shifts or altered spatial distribution to minimise competition, and intense predation by exotic species may result in a reduced effective population size with a concomitant reduction in genetic diversity. In this thesis I examined the sub-lethal effects of varying densities of the invasive competitor and predator Vespula vulgaris on the morphology, behaviour, population genetics and spatial distribution of the New Zealand endemic ant Prolasius advenus.</b></p> <p>The restriction of food resources can result in reduced worker size and altered scaling relationships of adult body parts in ants. Measurements of nine morphological characters from P. advenus worker ants collected from sites of varying wasp density revealed that workers were significantly smaller where there were more wasps. I also found evidence of allometric scaling relationships among body parts, which varied between areas of high and low wasp density. In particular the scaling relationships between the abdominal segments and overall size were found to be weaker where there were more wasps. This scaling variation resulted in ant workers with proportionally smaller abdomens in areas where wasps were most abundant, which might reduce their resource gathering and defensive efficiency.</p> <p>I tested the hypothesis that tasks performed by workers would be size correlated. In the presence of high densities of wasps, honeydew collection and brood care was undertaken by larger workers, whereas foraging in leaf litter was undertaken by smaller workers. In contrast, no relationship was found between task and worker size where wasp densities were lower. I suggest that in addition to increased efficiency in the collection of liquid carbohydrate resources larger workers may also serve a defensive role. I also tested the hypothesis that where the exclusively diurnal wasps were most abundant P. advenus workers would minimise potential competitive interactions by foraging predominantly at night. However, P. advenus were found to forage as much or more by day in the presence of high densities of wasps and to forage more nocturnally where wasps were sparse. Increasing the number of foragers by day may improve P. advenus’ competitive ability with wasps, but has the potential to come at the cost of other nest functions, energetic gains and increased worker mortality. Competitive mechanisms might influence ant population genetics, but wasps have also been shown to prey on dispersing ant queens. Analysis of microsatellite DNA markers revealed evidence of a genetic bottleneck in P. advenus populations where invasive predatory wasps have persisted at high population densities for more than twenty years. Ant populations at all wasp densities displayed significant heterozygote deficit, which may indicate that even at comparatively low densities predation by wasps has a detrimental effect on P. advenus genetic diversity. Alternatively, the observed heterozygote deficit may be the result of limited dispersal, population substructure or the peculiarities of the ant species‟ mating system. An examination of the broader population genetic structure of P. advenus from the seven sites sampled indicated that they were derived from two distinct populations. However, no individual assigned entirely to either population suggesting either some remaining admixture between the two populations or that they are derived from a common ancestral population.</p> <p>Finally I examined the effects of increasing wasp density, honeydew availability and habitat diversity on the distribution of P. advenus. Prolasius advenus nests tended to be smaller and populations displayed less variation in nest size where wasp densities were highest, which could indicate reduced longevity. Nest distribution was overdispersed relative to both con-and hetero-specific neighbours in high wasp density sites, but apparently randomly distributed in low wasp density sites. Both wasp and ant nest densities were greatest where honeydew was most abundant and plant diversity was lowest. These results suggest that intra- and inter-specific competition in combination with resource and nest site availability influences P. advenus nest distribution.</p> <p>Competition and predation by invasive species may influence recipient species‟ morphology, behaviour, genetic diversity and spatial distribution over a comparatively short period of time. These effects are much more subtle than under situations of direct predation. Such effects may not be immediately obvious in terms of abundance, but have potential long-term implications for the fitness and persistence of P. advenus in the presence of high densities of wasps.</p>


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