scholarly journals The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs

2019 ◽  
Author(s):  
T. Alexander Dececchi ◽  
Aleksandra M. Mloszewska ◽  
Thomas R. Holtz ◽  
Michael B. Habib ◽  
Hans C.E. Larsson
Keyword(s):  
Body Size ◽  
Large Body ◽  
Limb Lengthening ◽  
Limb Length ◽  
Energetic Cost ◽  
Energetic Efficiency ◽  
Leg Length ◽  
Distal Limb ◽  
Cost Of Transport ◽  
The Impact

AbstractLimb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology as locomotory capacity, especially running ability, is critical in not just in prey pursuit but also to avoid become prey oneself. One aspect that is traditionally overlooked is the impact of allometry on running ability and the limiting effect of large body size. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ∼1000kg or more, the effect that such larger mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here using expansive datasets, incorporating several different metrics to estimate body size, limb length and running speed, to calculate the effects of allometry running We test both on traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length as well as comparing the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroids or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated, no commonly used metric including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length) shows a significant correlation to top speed. The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organisms’ size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods while no one strategy dictated hindlimb evolution. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole.

scholarly journals Terrain-blind walking of planar underactuated bipeds via velocity decomposition-enhanced control

2019 ◽  
Vol 38 (10-11) ◽  
pp. 1307-1323 ◽  
Author(s):  
Martin Fevre ◽  
Bill Goodwine ◽  
James P Schmiedeler
Keyword(s):  
Feedback Control ◽  
Biped Robot ◽  
Rate Of Change ◽  
Energetic Cost ◽  
Practical Implementation ◽  
Leg Length ◽  
Cost Of Transport ◽  
Velocity Decomposition ◽  
Novel Approach ◽  
Hybrid Zero Dynamics

In this article, we develop and assess a novel approach for the control of underactuated planar bipeds that is based on velocity decomposition. The new controller employs heuristic rules that mimic the functionality of transverse linearization feedback control and that can be layered on top of a conventional hybrid zero dynamics (HZD)-based controller. The heuristics sought to retain HZD-based control’s simplicity and enhance disturbance rejection for practical implementation on realistic biped robots. The proposed control strategy implements a feedback on the time rate of change of the decomposed uncontrolled velocity and is compared with conventional HZD-based control and transverse linearization feedback control for both vanishing and non-vanishing disturbances. Simulation studies with a point-foot, three-link biped show that the proposed method has nearly identical performance to transverse linearization feedback control and outperforms conventional HZD-based control. For the non-vanishing case, the velocity decomposition-enhanced controller outperforms HZD-based control, but takes fewer steps on average before failure than transverse linearization feedback control when walking on uneven terrain without visual perception of the ground. The findings were validated experimentally on a planar, five-link biped robot for eight different uneven terrains. The velocity decomposition-enhanced controller outperformed HZD-based control while maintaining a relatively low specific energetic cost of transport (~0.45). The biped robot “blindly” traversed uneven terrains with changes in terrain height accumulating to 5% of its leg length using the stand-alone low-level controller.

scholarly journals Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Christopher Fang ◽  
Kenneth McAlpine ◽  
Michael Gustin ◽  
Ruijia Niu ◽  
David Freccero ◽  
...  
Keyword(s):  
Primary Total Knee Arthroplasty ◽  
Limb Lengthening ◽  
Limb Length ◽  
Patient Specific ◽  
Leg Length ◽  
Patient Specific Instrumentation ◽  
Primary Tkas ◽  
Significant Difference ◽  
Total Knee ◽  
Length Changes

Introduction. Expectations for limb length differences after TKA are important for patient perception and outcomes. Limb length discrepancies may occur due to postoperative leg length increases, which can lead to decreased patient functionality and satisfaction and even possible litigation. The purpose of this study is to examine the frequency and extent of limb lengthening among various preoperative deformities and between two different implant systems. Methods. Preoperative and postoperative full-length standing radiographs were obtained between August 2018 and August 2019 to measure mechanical axis and limb length of operative limbs. Demographic information such as age, sex, and BMI was also collected. Patients were grouped into categories for pre- and postoperative subgroup analysis: valgus, varus, customized implant, and conventional implant. Regression analysis was performed to evaluate significant relationships. Results. Of the 121 primary TKAs analyzed, 62% of the knees showed an increase in limb length after TKA, with an average lengthening of 5.32 mm. Preoperative varus alignment was associated with a mean lengthening of 3.14 mm, while preoperative valgus alignment was associated with a mean lengthening of 16.2 mm. Overall, there were no statistically significant differences in limb lengths pre- and postoperatively ( p  = 0.23) and no significant changes in limb length for any subgroup. Further, no variables were associated with limb length changes ( p  = 0.49), including the use of customized implants ( p  = 0.2). Conclusions. Limb lengthening after TKA is common and, on average, occurs more significantly in valgus knees. No significant difference in limb lengthening could be demonstrated using customized over conventional implants. Preoperative counseling is important to manage patient expectations.

scholarly journals Determinants of climbing energetic costs in humans

2021 ◽  
Author(s):  
Elaine E. Kozma ◽  
Herman Pontzer
Keyword(s):  
Body Size ◽  
Energy Expenditure ◽  
Body Mass ◽  
Anatomical Variation ◽  
Negligible Effect ◽  
Energetic Cost ◽  
Energetic Costs ◽  
Cost Of Transport ◽  
Specific Cost ◽  
Limb Proportions

Previous studies in primates and other animals have shown that mass specific cost of transport (J kg−1 m−1) for climbing is independent of body size across species, but little is known about within-species allometry of climbing costs or the effects of difficulty and velocity. Here, we assess the effects of velocity, route difficulty, and anatomical variation on the energetic cost of climbing within humans. Twelve experienced rock climbers climbed on an indoor wall over a range of difficulty levels and velocities, with energy expenditure measured via respirometry. We found no effect of body mass or limb proportions on mass-specific cost of transport among subjects. Mass-specific cost of transport was negatively correlated with climbing velocity. Increased route difficulty was associated with slower climbing velocities and thus higher costs, but there was no statistically significant effect of route difficulty on energy expenditure independent of velocity. Finally, human climbing costs measured in this study were similar to published values for other primates, suggesting arboreal adaptations have a negligible effect on climbing efficiency.

scholarly journals Distance from the magnification device contributes to differences in lower leg length measured in patients with TSF correction

2021 ◽  
Author(s):  
Marc-Daniel Ahrend ◽  
Michael Rühle ◽  
Fabian Springer ◽  
Heiko Baumgartner
Keyword(s):  
Sagittal Plane ◽  
Weight Bearing ◽  
Deformity Correction ◽  
Limb Lengthening ◽  
High Variability ◽  
Limb Length ◽  
Bone Lengthening ◽  
Leg Length ◽  
Length Difference ◽  
Measured Length

Abstract Introduction In absence of deformity or injury of the contralateral leg, the contralateral leg length is used to plan limb lengthening. Length variability on long-leg weight-bearing radiographs (LLR) can lead to inaccurate deformity correction. The aim of the study was to (1) examine the variability of the measured limb length on LLR and (2) to examine the influence of the position of the magnification device. Materials and methods The limb lengths of 38 patients during deformity correction with a taylor-spatial-frame were measured retrospectively on 7.3 ± 2.6 (4–13) LLR per patient. The measured length of the untreated limb between LLR were used to determine length variability between LLR in each patient. To answer the secondary aim, we took LLR from a 90 cm validation distance. A magnification device was placed in different positions: at the middle of the 90 cm distance (z-position), 5 cm anterior and 5 cm posterior from the z-position, at the bottom and top of the validation distance as well as 5 cm medial and 15 cm lateral from the z-position. Results The measured length variability ranged within a patient from 10 to 50 mm. 76% of patients had a measured limb length difference of ≥ 2 cm between taken LLR. Compared to length measurement of the 90 cm test object with the magnification device in the z-position (90.1 cm), positioning the device 5 cm anterior led to smaller (88.6 cm) and 5 cm posterior led to larger measurements (91.7 cm). The measured length with the magnification device at the bottom, top, medial or lateral (90.4; 89.9; 90.2; 89.8 cm) to the object differed not relevantly. Conclusions High variability of limb length between different LLR within one patient was observed. This can result from different positions of the magnification device in the sagittal plane. These small changes in positioning the device should be avoided to achieve accurate deformity correction and bone lengthening. This should be considered for all length and size measurements on radiographs.

scholarly journals The impact of maternal uterine genotype on postnatal growth and adult body size in mice.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 193-203 ◽  
Author(s):  
D E Cowley ◽  
D Pomp ◽  
W R Atchley ◽  
E J Eisen ◽  
D Hawkins-Brown
Keyword(s):  
Body Size ◽  
Embryo Transfer ◽  
Small Body ◽  
Large Body ◽  
Tail Length ◽  
Postnatal Growth ◽  
Adult Body Size ◽  
Adult Mice ◽  
Adult Body ◽  
The Impact

Abstract Embryo transfers were used to demonstrate that the genotype of the mother providing the uterine developmental environment significantly influences postnatal growth and adult body size of her progeny. Irrespective of their own genotype, mouse embryos transferred into the uterus of an inbred strain with large body size (C3H) had greater body weights, longer tails and higher growth rates than those transferred into the uterus of a strain with small body size (SWR). Uterine heterosis on body size was smaller than progeny heterosis, and both progeny and uterine heterosis persisted in adult mice. Uterine litter size was significantly negatively associated with body weight, tail length, growth rate and the timing of developmental events. The inbred SWR strain was more sensitive to the embryo transfer procedure than the C3H strain, but effects due to embryo transfer were moderate. Prenatal uterine effects have ramifications for biotechnologies utilizing embryo transfer as well as predictions about evolutionary change by selection.

scholarly journals Large Body Size as a Socially Valued Factor Determining Excess Weight and Obesity in the Context of the Nutritional Transition in Senegal

2018 ◽  
Vol 30 (1-2) ◽  
pp. 59-69 ◽  
Author(s):  
E. Cohen ◽  
A. Ndao ◽  
B. Faye ◽  
S. Ndiaye ◽  
E.H.M. Ndiaye ◽  
...  
Keyword(s):  
Body Size ◽  
Weight Status ◽  
Large Body ◽  
Excess Weight ◽  
African Countries ◽  
Large Body Size ◽  
Anthropometric Measures ◽  
Suburban Areas ◽  
Nutritional Transition ◽  
The Impact

Like most African countries, Senegal is experiencing a nutritional transition. Global drivers of sedentary behavior and high-calorie dietary intake, together with local anthropological drivers of large body size as a socially valued characteristic could be exposing the population to obesity. This study therefore set out to assess the impact of this sociocultural factor on the nutritional status of Senegalese adults. We set up 14 focus groups (n=84 participants) and a crosssectional quantitative survey (n=313 women; n=284 men) of adults in three different socio-ecological areas in Senegal (rural: n=204; suburban: n=206; urban: n=187). We also assessed perceptions of body weight (Body Size Scale) and weight status (anthropometric measures). Middle-aged and older Senegalese people value excess weight more than younger Senegalese in all the areas studied. Being female, older, living in urban/suburban areas and valuing excess weight/obesity were independently associated with being overweight/obese. A higher socio-economic status was also associated with being overweight/obese. A nutritional transition is under way in Senegal in urban/suburban areas, particularly affecting older urban women, with specific cultural factors contributing to this phenomenon. This suggests a need for local measures targeting women and is accounted for by specific anthropological characteristics in the Senegalese population.

Impact of perceptions of body size on obesity and weight management behaviour: a large representative population study in an African setting

2019 ◽  
Author(s):  
C O Chigbu ◽  
U U Aniebue ◽  
U Berger ◽  
K G Parhofer
Keyword(s):  
Body Size ◽  
Weight Management ◽  
Large Body ◽  
Household Survey ◽  
Large Body Size ◽  
Cross Sectional ◽  
Promotion Policies ◽  
Management Behaviour ◽  
High Level ◽  
The Impact

Abstract Background Perception of body size is an important psycho-cultural cause of obesity with wide racial and ethnic variations. Method Cross-sectional household survey using multistage cluster-randomised sampling. Prevalence estimates were weighted. Logistic regressions were done to determine the impact of perception of large body size on obesity and the impact of perception of own body size on weight-management behaviour. Adjusted odds ratios (AOR) were reported. Results The survey involved 6628 adults from 2843 households. More than a quarter of the population is either obese or overweight. Nearly half, 44.07% (95% confidence interval [CI]: 42.48–45.66%) of the population perceive large body size as desirable. Positive perception of large body size significantly increases the odds of obesity by 1.5 (AOR: 1.45; 95% CI: 1.09–1.9). Some 42.03% (95% CI: 35.52–48.55%) obese persons misperceive their weight to be normal. Perceiving own body size as normal decreases the odds of weight-losing behaviour (AOR: 0.019; 95% CI: 0.014–0.026). Conclusion There is a high level of veneration of large body size in southeast Nigeria, and this has a significant impact on obesity burden. Perception of own body size has a significant impact on weight-management behaviour. Health-promotion policies aimed at changing the social desirability of large body size and misperception of body size are recommended.

scholarly journals Decomposing the effects of ocean environments on predator–prey body-size relationships in food webs

2018 ◽  
Vol 5 (7) ◽  
pp. 180707 ◽  
Author(s):  
Tomoya Dobashi ◽  
Midori Iida ◽  
Kazuhiro Takemoto
Keyword(s):  
Body Size ◽  
Food Webs ◽  
Oxygen Concentration ◽  
Large Scale ◽  
Small Body ◽  
Large Body ◽  
Predator Prey ◽  
Body Sizes ◽  
And Function ◽  
The Impact

Body-size relationships between predators and their prey are important in ecological studies because they reflect the structure and function of food webs. Inspired by studies on the impact of global warming on food webs, the effects of temperature on body-size relationships have been widely investigated; however, the impact of environmental factors on body-size relationships has not been fully evaluated because climate warming affects various ocean environments. Thus, here, we comprehensively investigated the effects of ocean environments and predator–prey body-size relationships by integrating a large-scale dataset of predator–prey body-size relationships in marine food webs with global oceanographic data. We showed that various oceanographic parameters influence prey size selection. In particular, oxygen concentration, primary production and salinity, in addition to temperature, significantly alter body-size relationships. Furthermore, we demonstrated that variability (seasonality) of ocean environments significantly affects body-size relationships. The effects of ocean environments on body-size relationships were generally remarkable for small body sizes, but were also significant for large body sizes and were relatively weak for intermediate body sizes, in the cases of temperature seasonality, oxygen concentration and salinity variability. These findings break down the complex effects of ocean environments on body-size relationships, advancing our understanding of how ocean environments influence the structure and functioning of food webs.

scholarly journals Biocultural determinants of overweight and obesity in the context of nutrition transition in Senegal: a holistic anthropological approach

2018 ◽  
Vol 51 (4) ◽  
pp. 469-490 ◽  
Author(s):  
Emmanuel Cohen ◽  
Philippe Jean-Luc Gradidge ◽  
Amadou Ndao ◽  
Priscilla Duboz ◽  
Enguerran Macia ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Size ◽  
Dietary Intake ◽  
Dietary Diversity ◽  
Nutrition Transition ◽  
Large Body ◽  
Overweight And Obesity ◽  
Suburban Areas ◽  
The Impact ◽  
High Calorie

AbstractSenegal is experiencing a rising obesity epidemic, due to the nutrition transition occurring in most African countries, and driven by sedentary behaviour and high-calorie dietary intake. In addition, the anthropological local drivers of the social valorization of processed high-calorie food and large body sizes could expose the population to obesity risk. This study aimed to determine the impact of these biocultural factors on the nutritional status of Senegalese adults. A mixed methods approach was used, including qualitative and quantitative studies. Between 2011 and 2013, fourteen focus group discussions (n=84) and a cross-sectional quantitative survey (n=313 women;n=284 men) of adults in three different socio-ecological areas of Senegal (rural:n=204; suburban:n=206; urban:n=187) were conducted. Dietary intake (Dietary Diversity Scores), physical activity (International Physical Activity Questionnaire), body weight norms (Body Size Scale), weight and health statuses (anthropometric measures and blood pressure) were measured. Middle-aged and older Senegalese women were found to value overweight/obesity more than younger Senegalese in all regions. In addition, young urban/suburban adults had a tendency for daily snacking whilst urban/suburban adults tended to be less physically active and had higher anthropometric means. A binary logistic regression model showed that being female, older, living in urban/suburban areas and valuing larger body size were independently associated with being overweight/obese, but not high-calorie diet. Univariate analyses showed that lower physical activity and higher socioeconomic status were associated with being overweight/obese. Finally, overweight/obesity, which is low in men, is associated with hypertension in the total sample. The nutrition transition is currently underway in Senegal’s urban/suburban areas, with older women being more affected. Since several specific biocultural factors jointly contribute to this phenomenon, the study’s findings suggest the need for local public health interventions that target women and which account for the anthropological specificities of the Senegalese population.

A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

2020 ◽  
Vol 29 (2) ◽  
pp. 278-283
Author(s):  
S.G. Ermilov
Keyword(s):  
New Species ◽  
Body Size ◽  
Leaf Litter ◽  
Related Species ◽  
Large Body ◽  
Oribatid Mite ◽  
Neotropical Region ◽  
Large Body Size ◽  
First Time ◽  
A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

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