Broad Range Of Body Sizes Research Articles

Allometric wing growth links parental care to pterosaur giantism.

Pterosaurs evolved a broad range of body sizes, from small-bodied early forms with wingspans of mostly 1-2 m to the last-surviving giants with sizes of small airplanes. Since all pterosaurs began life as small hatchlings, giant forms must have attained large adult sizes through new growth strategies, which remain largely unknown. Here we assess wing ontogeny and performance in the giant Pteranodon and the smaller-bodied anurognathids Rhamphorhynchus, Pterodactylus and Sinopterus. We show that most smaller-bodied pterosaurs shared negative allometry or isometry in the proximal elements of the fore- and hindlimbs, which were critical elements for powering both flight and terrestrial locomotion, whereas these show positive allometry in Pteranodon. Such divergent growth allometry typically signals different strategies in the precocial-altricial spectrum, suggesting more altricial development in Pteranodon. Using a biophysical model of powered and gliding flight, we test and reject the hypothesis that an aerodynamically superior wing planform could have enabled Pteranodon to attain its larger body size. We therefore propose that a shift from a plesiomorphic precocial state towards a derived state of enhanced parental care may have relaxed the constraints of small body sizes and allowed the evolution of derived flight anatomies critical for the flying giants.

Ecomorphological correlates of inner and middle ear anatomy within phyllostomid bats.

Echolocation is the primary sense used by most bats to navigate their environment. However, the influence of echolocating behaviors upon the morphology of the auditory apparatus remains largely uninvestigated. While it is known that middle ear ossicle size scales positively with body mass across mammals, and that peak call frequency scales negatively with body mass among bats, there are still large gaps in our understanding of the degree to which allometry or ecology influences the morphology of the chiropteran auditory apparatus. To investigate this, we used μCT datasets to quantify three morphological components of the inner and middle ear: ossicle size, ossicle shape, and cochlear spirality. These data were collected across 27 phyllostomid species, spanning a broad range of body sizes, habitats, and dietary categories, and the relationships between these variables and ear morphology were assessed using a comparative phylogenetic approach. Ossicle size consistently scaled with strong negative allometry relative to body mass. Cochlear spirality was significantly (p=.025) associated with wing aspect ratio (a proxy for habitat use) but was not associated with body mass. From a morphological perspective, the malleus and incus exhibited some variation in kind with diet and call frequency, while stapes morphology is more closely tied to body size. Future work will assess these relationships within other chiropteran lineages, and investigate potential morphological differences in the middle and inner ear of echolocating-vs-non-echolocating taxa.

#bodypositivity: A content analysis of body positive accounts on Instagram

In the last decade, the body image literature has begun to extend beyond a primary focus on body image disturbances and examine the construct of positive body image. Similarly, “Body positivity” is a growing social media trend that seeks to challenge dominant societal appearance ideals and promote acceptance and appreciation of all bodies and appearances. The present study provides a content analysis of body positive posts on Instagram. A set of 640 Instagram posts sampled from popular body positive accounts were coded for physical appearance-related attributes and central themes featured. Results showed that body positive imagery typically depicted a broad range of body sizes and appearances. Additionally, while a proportion of posts were appearance-focused, the majority of posts conveyed messages aligned with theoretical definitions of positive body image. This study clarifies body positive content on Instagram, as well as highlights points of overlap and distinction from academic principles of positive body image and other appearance-focused social media content. Accordingly, the results offer theoretical and practical implications for future research and prevention efforts.

Size-based quality-informed framework for quantitative optimization of pediatric CT.

The purpose of this study was to formulate a systematic, evidence-based method to relate quantitative diagnostic performance to radiation dose, enabling a multidimensional system to optimize computed tomography imaging across pediatric populations. Based on two prior foundational studies, radiation dose was assessed in terms of organ doses, effective dose ([Formula: see text]), and risk index for 30 patients within nine color-coded pediatric age-size groups as a function of imaging parameters. The cases, supplemented with added noise and simulated lesions, were assessed in terms of nodule detection accuracy in an observer receiving operating characteristic study. The resulting continuous accuracy-dose relationships were used to optimize individual scan parameters. Before optimization, the nine protocols had a similar [Formula: see text] of [Formula: see text] with accuracy decreasing from 0.89 for the youngest patients to 0.67 for the oldest. After optimization, a consistent target accuracy of 0.83 was established for all patient categories with [Formula: see text] ranging from 1 to 10mSv. Alternatively, isogradient operating points targeted a consistent ratio of accuracy-per-unit-dose across the patient categories. The developed model can be used to optimize individual scan parameters and provide for consistent diagnostic performance across the broad range of body sizes in children.

Gait changes in a line of mice artificially selected for longer limbs.

In legged terrestrial locomotion, the duration of stance phase, i.e., when limbs are in contact with the substrate, is positively correlated with limb length, and negatively correlated with the metabolic cost of transport. These relationships are well documented at the interspecific level, across a broad range of body sizes and travel speeds. However, such relationships are harder to evaluate within species (i.e., where natural selection operates), largely for practical reasons, including low population variance in limb length, and the presence of confounding factors such as body mass, or training. Here, we compared spatiotemporal kinematics of gait in Longshanks, a long-legged mouse line created through artificial selection, and in random-bred, mass-matched Control mice raised under identical conditions. We used a gait treadmill to test the hypothesis that Longshanks have longer stance phases and stride lengths, and decreased stride frequencies in both fore- and hind limbs, compared with Controls. Our results indicate that gait differs significantly between the two groups. Specifically, and as hypothesized, stance duration and stride length are 8–10% greater in Longshanks, while stride frequency is 8% lower than in Controls. However, there was no difference in the touch-down timing and sequence of the paws between the two lines. Taken together, these data suggest that, for a given speed, Longshanks mice take significantly fewer, longer steps to cover the same distance or running time compared to Controls, with important implications for other measures of variation among individuals in whole-organism performance, such as the metabolic cost of transport.

Pump size of Berlin Heart EXCOR pediatric device influences clinical outcome in children

The pediatric Berlin Heart (BH) EXCOR device provides mechanical circulatory support as a bridge to transplantation or recovery in children. Despite the availability of various pump sizes, information on the impact of pump size on clinical outcome is still lacking. We aimed to evaluate whether pump size in relation to body surface area (BSA) has an impact on clinical outcome. Children requiring implantation of a BH between 2000 and 2013 were included in this retrospective study. Primary end-points were events leading to BH explantation (transplantation, recovery or death) and the secondary end-point was occurrence of thromboembolic events. Patients were categorized into three groups according to BH stroke volume per BSA: optimal (30 to 50 ml/m(2)); small (<30 ml/m(2)); and large (>50 ml/m(2)). Eighty children (median age 2.2 years, median BSA 0.50 m(2)) underwent BH implantation. Fifty-five (69%) children had an optimally sized pump implanted, whereas 8 children (10%) had small pump and 17 (21%) large pump implantation. Overall survival rate was 69%. Weaning was possible in 15 children (19%), and 39 children (49%) were transplanted. Mortality, myocardial recovery and transplantation were not related to age, BSA or pump size. Thromboembolic events occurred significantly more frequently in children treated with large pumps. The broad range of body sizes in children from newborns to adolescents requires a wide choice of appropriately sized devices. Large pump size in relation to BSA is an independent risk factor for occurrence of thromboembolic events.

Carrion fly‐derived DNA as a tool for comprehensive and cost‐effective assessment of mammalian biodiversity

Large-scale monitoring schemes are essential in assessing global mammalian biodiversity, and in this framework, leeches have recently been promoted as an indirect source of DNA from terrestrial mammal species. Carrion feeding flies are ubiquitous and can be expected to feed on many vertebrate carcasses. Hence, we tested whether fly-derived DNA analysis may also serve as a novel tool for mammalian diversity surveys. We screened DNA extracted from 201 carrion flies collected in tropical habitats of Côte d'Ivoire and Madagascar for mammal DNA using multiple PCR systems and retrieved DNA sequences from a diverse set of species (22 in Côte d'Ivoire, four in Madagascar) exploiting distinct forest strata and displaying a broad range of body sizes. Deep sequencing of amplicons generated from pools of flies performed equally well as individual sequencing approaches. We conclude that the analysis of fly-derived DNA can be implemented in a very rapid and cost-effective manner and will give a relatively unbiased picture of local mammal diversity. Carrion flies therefore represent an extraordinary and thus far unexploited resource of mammal DNA, which will probably prove useful for future inventories of wild mammal communities.

Agreement between pQCT- and DXA-derived indices of bone geometry, density, and theoretical strength in females of varying age, maturity, and physical activity

Measurement of bone mass, geometry, density, and strength are critical in bone research and clinical studies. For peripheral quantitative computed tomography (pQCT), single and repeated measurements are particularly adversely affected by movement and positional variation. Dual-energy X-ray absorptiometry (DXA)-derived indices may alleviate these problems and provide useful alternative assessments. To evaluate this hypothesis, distal radius DXA and pQCT indices were compared in 101 healthy females aged 8.0 to 22.8 years (prepuberty to adulthood), reflecting a broad range of body sizes, physical maturity, and activity exposures. At the diaphysis, correlations were ρ = +0.74 to +0.98, with strong intermethod agreement for most indices. At the metaphysis, correlations were ρ = +0.64 to +0.97; intermethod agreement improved with modifications to the simplified geometric formulas more closely reflecting metaphyseal bone geometry. Further improvements may be possible because skeletal size and maturity-related biases in agreement were detected. Overall, DXA-derived indices may provide a useful assessment of bone geometry, density, and theoretical strength contingent on appropriate consideration of their limitations.

Relationship of metabolic rate to body size in Orthoptera

Abstract Metabolic rate determines an individual's rate of resource acquisition, assimilation, growth, survival and reproduction. Studies involving a broad range of taxa and body sizes typically result in whole-organism metabolic rate scaling to the ¾ power of body mass. Competing models have been proposed to explain this allometric relationship. The nutrient supply network model of West et al. (1997) proposes that the ¾ power relationship results from the fractal nature of space-filling nutrient supply networks. The model of Kozlowski et al. (2003) proposes that the scaling of metabolic rate with body mass will vary from 2/3 to 1 among different taxa, depending on the degree to which increasing body size depends on increasing cell size or number. The present study measured resting metabolic rates across a broad range of body sizes in nymphs of Melanoplus sanguinipes F. and also analyzed published reports of metabolic rates in adult Orthoptera. The two sets of data were in close agreement: the scaling exp...

Allometric Scaling and Seasonality in the Epidemics of Wildlife Diseases

We present a susceptibles-exposed-infectives (SEI) model to analyze the effects of seasonality on epidemics, mainly of rabies, in a wide range of wildlife species. Model parameters are cast as simple allometric functions of host body size. Via nonlinear analysis, we investigate the dynamical behavior of the disease for different levels of seasonality in the transmission rate and for different values of the pathogen basic reproduction number (R(0)) over a broad range of body sizes. While the unforced SEI model exhibits long-term epizootic cycles only for large values of R(0), the seasonal model exhibits multiyear periodicity for small values of R(0). The oscillation period predicted by the seasonal model is consistent with those observed in the field for different host species. These conclusions are not affected by alternative assumptions for the shape of seasonality or for the parameters that exhibit seasonal variations. However, the introduction of host immunity (which occurs for rabies in some species and is typical of many other wildlife diseases) significantly modifies the epidemic dynamics; in this case, multiyear cycling requires a large level of seasonal forcing. Our analysis suggests that the explicit inclusion of periodic forcing in models of wildlife disease may be crucial to correctly describe the epidemics of wildlife that live in strongly seasonal environments.

Weighty matters: Body size, diet and specialization in aphidophagous ladybird beetles (Coleoptera: Coccinellidae)

Aphidophagous ladybirds exhibit a broad range of body sizes. Until now this has been thought to be a function of the different prey densities that they feed at, with smaller ladybirds feeding at lower prey densities. The size of the prey species they feed on has been considered to have no relationship with ladybird body size. However, these arguments possess a limited capacity to explain observed data from the field. I here demonstrate a more realistic, complex approach incorporating both prey density and the size of prey species. Small ladybirds can feed on small aphids at both low and high densities. However when the aphid species is large they cannot catch the older, bigger, more energy-rich aphid instars due to their small size. They are thus unable to feed on large aphid prey at low densities, although at higher densities numbers of the smaller instars may be sufficient to sustain them. By contrast large ladybirds can feed on large aphids at both low and high densities due to their superior ability to catch the bigger, more energy-rich older aphids; however they cannot be sustained by low densities of small aphids due to food limitation consequent on their large size. This more complex association between ladybird size, prey size and prey density possesses a better explanatory power for earlier field data. Because of this relationship, ladybird body size also provides an important trade-off determining dietary breadth and specialization in the aphidophagous Coccinellidae. Dietary specialists more closely match the size of their limited prey species, have higher overall capture efficiencies and can thus continue to reproduce at lower aphid densities for longer. By contrast dietary generalists adopt a one-size-fits-all strategy, are medium-sized and have lower capture efficiencies of individual prey species, thus requiring higher aphid densities. The role of body-size in dietary specialization is supported by data from the British fauna. Rather than trade-offs related to prey chemistry, which have hitherto been the centre of attention, body size trade-offs are the likely most important universal factor underlying dietary specialization in aphidophagous coccinellids.

Weight‐Length Relationships in Fisheries Studies: The Standard Allometric Model Should Be Applied with Caution

AbstractThe standard allometric weight‐length relationship W = aLb is widely used in fisheries science to estimate the weight of fish of known length and to compute body condition indices. This relationship is used in abundance surveys such as acoustic surveys to convert abundance at length into estimates of population biomass. Although fitting this relationship to weight‐length data over a broad range of body sizes is common practice, the fit of this relationship often does not receive careful scrutiny. We explored the fit of the allometric model as well as alternative weight‐length relationships to data from acoustic surveys of walleye pollock Theragra chalcogramma from the North Pacific and found a subtle but persistent lack of fit for the allometric relationship, particularly for the largest and smallest fish in the population. This lack of fit results in biased estimates of population biomass. Analysis of weight‐length measurements of 10 additional species indicates that these biases are not restricted to walleye pollock; indeed, the lack of fit of the allometric weight‐length relationship is likely to be a general concern. Our results suggest that the allometric relationship should not be applied to generate weight‐length relations over a broad range of body sizes without careful examination of the potential consequences. In some applications, such as the walleye pollock surveys examined here, use of alternative, less biased, methods to estimate mean weight at length will be beneficial. Such methods include fitting the allometric relationship in a piecewise fashion over restricted size or age intervals and simply computing the mean weight at length. In applications with spawning fish, incorporating the maturity state in weight‐length prediction methods is likely to further improve predictions of weight at length.

Evolution of large body size in abalones (Haliotis): patterns and implications

Kelps and other fleshy macroalgae—dominant reef-inhabiting organisms in cool seas—may have radiated extensively following late Cenozoic polar cooling, thus triggering a chain of evolutionary change in the trophic ecology of nearshore temperate ecosystems. We explore this hypothesis through an analysis of body size in the abalones (Gastropoda; Haliotidae), a widely distributed group in modern oceans that displays a broad range of body sizes and contains fossil representatives from the late Cretaceous (60–75 Ma). Geographic analysis of maximum shell length in living abalones showed that small-bodied species, while most common in the Tropics, have a cosmopolitan distribution, whereas large-bodied species occur exclusively in cold-water ecosystems dominated by kelps and other macroalgae. The phylogeography of body size evolution in extant abalones was assessed by constructing a molecular phylogeny in a mix of large and small species obtained from different regions of the world. This analysis demonstrates that small body size is the plesiomorphic state and largeness has likely arisen at least twice. Finally, we compiled data on shell length from the fossil record to determine how (slowly or suddenly) and when large body size arose in the abalones. These data indicate that large body size appears suddenly at the Miocene/Pliocene boundary. Our findings support the view that fleshy-algal dominated ecosystems radiated rapidly in the coastal oceans with the onset of the most recent glacial age. We conclude with a discussion of the broader implications of this change.

Automobile seat comfort: occupant preferences vs. anthropometric accommodation

Automobile seat design specifications cannot be established without considering the comfort expectations of the target population. This contention is supported by published literature, which suggests that ergonomics criteria, particularly those related to physiology, do not satisfy consumer comfort. The objective of this paper is to challenge ergonomics criteria related to anthropometry in the same way. In this context, 12 subjects, representing a broad range of body sizes, evaluated five different compact car seats during a short-term seating session. Portions of a reliable and valid survey were used for this purpose. The contour and geometry characteristics of the five seats were quantified and compared to the survey information. Discrepancies were discovered between published anthropometric accommodation criteria and subject-preferred lumbar height, seatback width, cushion length, and cushion width. Based on this finding, it was concluded that automobile seat comfort is a unique science. Ergonomics criteria, while serving as the basis for this science, cannot be applied blindly for they do not ensure comfortable automobile seats.

Effect of body size and temperature on generation time in zooplankton

Effect of body size and temperature on generation time in zooplankton

Converting Chattecx Balance System vertical reaction force measurements to center of pressure excursion measurements.

The purpose of this study was to determine the precision with which the postural stability data generated by the Chattecx Balance System could be converted to center of pressure displacement measurements. Two men and one woman were selected to represent a broad range of body sizes (age = 23-33 years, height = 154-175 cm, weight = 45-80 kg). The Balance System load cells were placed on a force plate, and data were collected simultaneously from the Balance System and the force plate while the subjects performed standardized postural tasks. Linear regression analysis was used to characterize the relationship between the estimated center of pressure from the Balance System and the calculated center of pressure from the force plate. Significant linear relationships between the center of pressure estimated from the Balance System and the center of pressure calculated from the force plate were determined (all R2 values = > .90). System data can be converted, and the methods recommended for use with the Balance System are described.

An analytic study of impact ejecta trajectories in the atmospheres of Venus, Mars, and Earth

Calculations have been made to determine the effects of atmospheric drag and gravity on impact ejecta trajectories on Venus, Mars, and the Earth. The equations of motion were numerically integrated for a broad range of body sizes, initial velocities, and initial elevation angles. A dimensionless parameter was found from approximate analytic solutions which correlated the ejecta range, final impact angle, and final impact velocity for all three planets.