A New Approach to Animal Flight Mechanics

1979 ◽  
Vol 80 (1) ◽  
pp. 17-54 ◽  
Author(s):  
J. M. V. RAYNER
Keyword(s):  
Body Mass ◽  
Large Body ◽  
Simple Expression ◽  
The Body ◽  
Flight Mechanics ◽  
Total Power ◽  
Forward Flight ◽  
Vortex Theory ◽  
Rate Of Increase ◽  
Total Power Consumption

The mechanics of lift and thrust generation by flying animals are studied by considering the distribution of vorticity in the wake. As wake generation is not continuous, the momentum jet theory, which has previously been used, is not satisfactory, and the vortex theory is a more realistic model. The vorticity shed by the wings in the course of each powered stroke deforms into a small-cored vortex ring; the wake is a chain of such rings. The momentum of each ring sustains and propels the animal; induced power is calculated as the rate of increase of wake kinetic energy. A further advantage of the vortex theory is that lift and induced drag coefficients are not required; estimated instantaneous values of these coefficients are generally too large for steady state aerodynamic theory to be appropriate to natural flapping flight. The vortex theory is applied to hovering of insects and to avian forward flight. A simple expression for induced power in hovering is found. Induced power is always greater than simple momentum jet estimates, and the discrepancy becomes substantial as body mass increases. In hovering the wake is composed of a stack of horizontal, coaxial, circular vortex rings. In forward flight of birds the rings are elliptic; they are neither horizontal nor coaxial because the momentum of each ring balances the vector sum of parasite and profile drag and the bird's weight. Total power consumption as a function of flight velocity is calculated and compared for several species. Power reduction is one of the major factors influencing the choice of flight style. A large body of data is used to obtain an approximate scaling between stroke period and the body mass for birds. Together with relations between other morphological parameters, this is used to estimate the variation of flight speed and power with body mass for birds, and on this basis deviations from allometric scaling can be related to flight proficiency and to the use of such strategies as the bounding flight of small passerines. Note: Present address: Department of Zoology, University of Bristol, Woodland Road, Bristol BS8 IUG, U.K.

LOW-POWER, LOW-VOLTAGE, DUAL-OUTPUT, SECOND GENERATION CURRENT CONVEYOR AND ITS APPLICATION IN LOW-PASS FILTER DESIGN

2013 ◽  
Vol 22 (06) ◽  
pp. 1350044 ◽  
Author(s):  
MOHAMMAD HOSSEIN MAGHAMI ◽  
AMIR M. SODAGAR
Keyword(s):  
Second Generation ◽  
Current Conveyor ◽  
The Body ◽  
Total Power ◽  
Cmos Process ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Silicon Area ◽  
Total Power Consumption ◽  
Low Pass

A new simple dual-output second generation current conveyor (DO-CCII) circuit is proposed. Designed in a standard 0.5-μm CMOS process, the circuit operates at ±1.5 V supply voltages with a total power consumption of 106 nW. Main characteristics of the proposed DO-CCII are its simplicity, small silicon area consumption, and not suffering from the body effect of MOS transistors. The proposed circuit is employed to implement a first-order low-pass filter with upper -3 dB cut-off frequency of as low as 3.2 Hz.

scholarly journals New insights into the genetic mechanisms of body size evolution in Carnivora

2020 ◽  
Author(s):  
Xin Huang ◽  
Di Sun ◽  
Tianzhen Wu ◽  
Xing Liu ◽  
Shixia Xu ◽  
...  
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Rapid Evolution ◽  
Large Body ◽  
The Body ◽  
Molecular Evidence ◽  
Size Evolution ◽  
Body Size Evolution

Abstract Background The range of body sizes in Carnivora is unparalleled in any other mammalian order, with more than 130,000 times in body mass and 50 times in length. However, the molecular mechanisms underlying the huge difference in body size of Carnivora have not been explored so far. Results Herein, we performed a comparative genomics analysis of 20 carnivores to explore the genetic basis of great body size variation in carnivores. Phylogenetic generalized least squares (PGLS) revealed that 337 genes were significantly related to both head body length and body mass, these genes were defined as body size associated genes (BSAGs). Fourteen positively related BSAGs were found to be associated with obesity and three of which were identified to be under rapid evolution in the extremely large body-sized carnivores, which suggested that these obesity-related BSAGs might have driven the body size expansion in carnivores. Interestingly, 100 BSAGs were examined to be associated with cancer control in carnivores, particularly 15 cancer-related genes were found to be under rapid evolution in extremely large carnivores. These results strongly suggested that large body-sized carnivores might have evolved effective mechanism to resist cancer, which could be regarded as molecular evidence to support for the Peto’s paradox. For small carnivores, we identified 15 rapidly evolving genes and found six genes with fixed amino acid changes that were reported to reduce body size. Conclusion This study brings new insights into the molecular mechanisms that drove the diversifying evolution of body size in carnivores, and provides new target genes for exploring the mysteries of body size evolution in mammals.

The anthropometric generalization of the Body Mass Index (Preprint)

2020 ◽  
Author(s):  
Alexandru Godescu
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Experimental Research ◽  
Large Body ◽  
The Body ◽  
Fat Free Mass ◽  
Physical Work ◽  
Healthy Weight ◽  
Quantification Theory ◽  
Highly Cited

BACKGROUND While he BMI is assumed to indicate obesity in sedentary people and in people who do not practice sports, it is undisputed and a consensus among researchers that Body Mass Index (BMI) is not a good indicator for obesity in people who developed their body through heavy physical work or sport but also in other segments of population such as those who appear to have a normal weight but in fact have a high body fat percentage and obese methabolism. The BMI also does not include all the variables essential for a health predictor. The BMI is not always a good predictor of metabolic disease, people who appear of healthy weight according to BMI have in some cases an obese metabolic syndrome. OBJECTIVE Develop a generalization of the body mass index explaining the results of a number of highly cited research papers showing how fat distribution and muscle strength are predictors or mortality, morbidity, ill health, loss of function METHODS In essence, my method is theoretic, to develop a formula explaining highly cited experimental research. It is like theoretical physics, developing a formula to explain important experiments and building a theory to generalize the body mass index. I use also data and perform numerical simulation of the formulae RESULTS My formulae explain the causality in the important experiments in medicine and sport cited by me. the formulae can be used to develop new experiments CONCLUSIONS I develop a direct generalization of BMI, in the mathematical and physiological sense to account for fat and fat free mass and muscles, small and large body frames. It is the first such generalization because the classic BMI can be determined as a particular case of my formulae in the strict mathematical and practical physiologic sense. Most of the experimental proof I bring in support of my formulae and bodyweight quantification theory comes from many highly cited experimental research publications in medicine, sports medicine, sport science and physiology. My formulae explain also performance in decades of competitive sports and athletics

A vortex theory of animal flight. Part 2. The forward flight of birds

1979 ◽  
Vol 91 (4) ◽  
pp. 731-763 ◽  
Author(s):  
J. M. V. Rayner
Keyword(s):  
Steady State ◽  
Lift Coefficient ◽  
Vortex Rings ◽  
Forward Flight ◽  
Induced Drag ◽  
Vortex Theory ◽  
Rate Of Increase ◽  
A Chain ◽  
Animal Flight ◽  
Wing Stroke

The vortex wake of a bird in steady forward flight is modelled by a chain of elliptical vortex rings, each generated by a single downstroke. The shape and inclination of each ring are determined by the downstroke geometry, and the size of each ring by the wing circulation; the momentum of the ring must overcome parasitic and profile drags and the bird's weight for the duration of a stroke period. From the equation of motion it is possible to determine exactly the kinematics of the wing-stroke for any flight velocity. This approach agrees more readily with the nature of the wing-stroke than the classical actuator disk and momentum-jet theory; it also dispenses with lift and induced drag coefficients and is not bound by the constraints of steady-state aerodynamics. The induced power is calculated as the mean rate of increase of wake kinetic energy. The remaining components of the flight power (parasite and profile) are calculated by traditional methods; there is some consideration of different representations of body parasite drag. The lift coefficient required for flight is also calculated; for virtually all birds the lift coefficient in slow flight and hovering is too large to be consistent with steady-state aerodynamics.A bird is concerned largely to reduce its power consumption on all but the shortest flights. The model suggests that there are a number of ways in which power reduction can be achieved. These various strategies are in good agreement with observation.

scholarly journals Body mass index at calving on performance and efficiency of Zebu cow herds

2022 ◽  
Vol 43 (1) ◽  
pp. 197-210
Author(s):  
Ricardo Zambarda Vaz ◽  
◽  
Liliane Cérdotes ◽  
Rangel Fernandes Pacheco ◽  
Dayana Bernardi Sartori ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Milk Yield ◽  
Direct Method ◽  
Large Body ◽  
The Body ◽  
Breeding Period ◽  
Early Weaning ◽  
Yield And Quality ◽  
The Impact

This study examines the impact of the body mass index (BMI) at calving on the development and postpartum efficiency of cows of Zebu origin. The study involved 87 cows and their calves [pure Nellore (N) or predominant Nellore composition in a cross with Charolais (C) (3/4N1/4C and 5/8N3/8C)]. The mothers were grouped into classes according to their BMI at calving, namely, ‘small’, ‘moderate’ and ‘large’. Body mass index was determined by dividing the body weight of the cows by their length and by hip height and then dividing the result by 10. Cows were weighed at calving, at weaning, at the end of the breeding period and at the diagnosis of pregnancy. Calves were weighed at birth, at early weaning (63 days) and at 210 of age. To evaluate milk yield and quality, milk was collected at 21, 42 and 63 days after calving. Milk yield was measured by the direct method, with manual milking, followed by analysis of the lactose, fat, total solids and crude protein contents. Pregnancy rate was similar between the three BMI groups; however, cows with a lower BMI were more efficient at calving in producing kilograms of calf per kilogram of cow kept. Higher BMI provide higher milk yields, without affecting its quality, as well as heavier calves at early weaning and at 210 days of age.

CLIMBING PERFORMANCE OF MIGRATING BIRDS AS A BASIS FOR ESTIMATING LIMITS FOR FUEL-CARRYING CAPACITY AND MUSCLE WORK

1992 ◽  
Vol 164 (1) ◽  
pp. 19-38 ◽  
Author(s):  
ANDERS HEDENSTRÖM ◽  
THOMAS ALERSTAM
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Bird Species ◽  
Flapping Flight ◽  
Fuel Load ◽  
Total Power ◽  
Total Body Mass ◽  
Muscle Work ◽  
Total Power Consumption ◽  
Migrating Birds

Sustained climb rates and airspeeds in flapping flight were measured by radar tracking fifteen species of migrating birds ranging in body mass between 10 g and 10 kg. There was an inverse correlation between body size and climb rate: the lowest mean climb rate, 0.32 m s−1, was observed in the mute swan and the highest mean value, 1.63ms−1, in the dunlin. Some dunlin flocks achieved sustained climb rates exceeding 2ms−1, up to 2.14ms−1. Assuming that the migrants expend maximum sustained power during their climbs, the climbing power can be used as a conservative estimate of the power margin. Estimates of climbing power for the species tracked by radar were used, in conjunction with aerodynamic theory, to calculate the amount of extra load the migrants should be able to carry if their power margin was used for load transportation rather than for climbing. Calculated ratios of total body mass with maximum load to lean body mass ranged between 1.28 and 2.75, showing an overall negative correlation with body size. There was a broad agreement with maximum fuel loads observed among freeliving birds, indicating that the upper limits of fuel-carrying capacities and flight ranges in migrating birds are determined by power margin constraints in sustained flapping flight. Markedly reduced climb rates have been recorded for shorebirds departing with very large fuel reserves from W. Africa and Iceland, supporting the calculated trade-off between climb rate and fuel load. Total power consumption was estimated as the sum of calculated aerodynamic power for forward flight and climbing power. The ratio of total power to the expected minimum aerodynamic power was 1.1-1.3 in the three largest species, increasing to 2–4 in the smallest species. Medium- and small-sized species seem to allocate power in excess of the minimum aerodynamic power not only for climbing but also for maintaining a forward speed faster than the minimum power speed. Given provisional estimates of flight muscle masses and wingbeat frequencies, the mass-specific sustained muscle work for the different climbing bird species was calculated to be in the range 16–41 joules per kilogram muscle mass, showing a significant positive correlation with body mass

scholarly journals Fatness and thermoregulation of qualified rugby players

2019 ◽  
Vol 68 ◽  
pp. 02011
Author(s):  
Inese Pontaga ◽  
Jekaterina Liepina ◽  
Dzintra Kazoka ◽  
Silvija Umbrasko
Keyword(s):  
Body Mass ◽  
Body Fat ◽  
Large Body ◽  
The Body ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Wide Range ◽  
The Mean ◽  
Body Fat Percent ◽  
Rugby Players

A large body size and mass are advantages in rugby. The desire to gain weight can bring players to become overweight or obese. This can worsen their thermoregulation and health risks. The aim was to evaluate anthropometric characteristics and to determine the effect of additional body fat percentage on sweat loss during play-match in male rugby players. Nineteen qualified male rugby players were tested during play-match. The age, height, body mass, body mass index (BMI) and body fat percent of participants were: 29 ± 6 years, 183 ± 7 cm, 96.86 ± 12.88 kg, 29.07 ± 3.90 kg/m2, 20.52 ± 5.64%, respectively. The skin fold thickness measurement was used to assess body fat percent. Body mass loss was detected by weighting. The mean BMI was 26.18 ± 2.37 (kg/m2) and the body fat 15.87 ± 3.97% in backs. Forwards were significantly heavier and had BMI 31.18 ± 3.44 (kg/m2)(p = 0.002) and the body fat 23.91 ± 4.02% (p < 0.001). The mean body mass decrease in the play-match was 1.83 ± 0.84%. The mean sweating intensity was 2.24 ± 1.07 l/h, but individual varied among players in very wide range (1.12–6.16 l/h). Relationships between the body fat percentage and sweating intensity was not determined (p > 0.05). Recommendation is to increase the volume of regular strength training, to correct the diet and liquid consumption.

The mechanical power output of the flight muscles of blue-breasted quail (Coturnix chinensis) during take-off

2001 ◽  
Vol 204 (21) ◽  
pp. 3601-3619 ◽  
Author(s):  
Graham N. Askew ◽  
Richard L. Marsh ◽  
Charles P. Ellington
Keyword(s):  
Body Mass ◽  
Power Output ◽  
High Speed ◽  
The Body ◽  
Three Dimensions ◽  
Total Power ◽  
Muscle Fibres ◽  
Wingbeat Frequency ◽  
Mechanical Power Output ◽  
Flight Muscles

SUMMARYBlue-breasted quail (Coturnix chinensis) were filmed during take-off flights. By tracking the position of the centre of mass of the bird in three dimensions, we were able to calculate the power required to increase the potential and kinetic energy. In addition, high-speed video recordings of the position of the wings over the course of the wing stroke, and morphological measurements, allowed us to calculate the aerodynamic and inertial power requirements. The total power output required from the pectoralis muscle was, on average, 390 W kg–1, which was similar to the highest measurements made on bundles of muscle fibres in vitro (433 W kg–1), although for one individual a power output of 530 W kg–1 was calculated. The majority of the power was required to increase the potential energy of the body. The power output of these muscles is the highest yet found for any muscle in repetitive contractions.We also calculated the power requirements during take-off flights in four other species in the family Phasianidae. Power output was found to be independent of body mass in this family. However, the precise scaling of burst power output within this group must await a better assessment of whether similar levels of performance were measured across the group. We extended our analysis to one species of hawk, several species of hummingbird and two species of bee. Remarkably, we concluded that, over a broad range of body size (0.0002–5 kg) and contractile frequency (5–186 Hz), the myofibrillar power output of flight muscles during short maximal bursts is very high (360–460 W kg–1) and shows very little scaling with body mass. The approximate constancy of power output means that the work output varies inversely with wingbeat frequency and reaches values of approximately 30–60 J kg–1 in the largest species.

Testosterone, Physical Aggression, Dominance, and Physical Development in Early Adolescence

1998 ◽  
Vol 22 (4) ◽  
pp. 753-777 ◽  
Author(s):  
Richard E. Tremblay ◽  
Benoist Schaal ◽  
Bernard Boulerice ◽  
Louise Arseneault ◽  
Robert G. Soussignan ◽  
...  
Keyword(s):  
Body Mass ◽  
Early Adolescence ◽  
Testosterone Level ◽  
Physical Aggression ◽  
Social Dominance ◽  
Large Body ◽  
Antisocial Behaviour ◽  
Physical Development ◽  
The Body ◽  
Regression Analyses

The associations among testosterone, physical development, social dominance, and antisocial behaviour during early adolescence were assessed in a sample of boys followed from 6 to 13 years. Saliva testosterone level was positively correlated with height, and uncorrelated with measures of fatness, including the body mass index. Physical aggression and social dominance were not significantly correlated. Regression analyses revealed that testosterone level and body mass additively predicted social dominance, whereas only body mass predicted physical aggression. Thus, early adolescents with high levels of testosterone were more likely to be socially dominant, especially if they had a large body mass. Those who had a large body mass were more likely to be physically aggressive, independently of their testosterone level. The observed pattern of correlations between testosterone, body mass, dominance, and physical aggression offers an interesting example of the complex hormone-physique-behaviour relations at puberty. They support the hypothesis that testosterone level and social dominance are related, and that the association between testosterone level and physical aggression is probably observed in contexts where physical aggression leads to social dominance.

scholarly journals Using body mass index ignores the intensive training of elite special force personnel

2019 ◽  
Vol 244 (11) ◽  
pp. 873-879 ◽  
Author(s):  
Erwin Tafeit ◽  
Gerhard Cvirn ◽  
Manfred Lamprecht ◽  
Markus Hohensinn ◽  
Reinhard Moeller ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Muscle Mass ◽  
Body Mass ◽  
Body Fat ◽  
Task Force ◽  
Large Body ◽  
Overweight And Obesity ◽  
The Body ◽  
Body Fatness ◽  
Intensive Training

Body mass index is a common and well-known measure in daily life. A body mass index higher than 25 is assumed to be an indicator for overweight and obesity and a high amount of total body fat. But body mass index overestimates body fat in subjects with high muscle mass and underestimates it in persons with a low lean body mass, especially in elderly and diseased persons. In the present study, we investigate the performance of the body mass index as a measure of body fatness and its ability to distinguish between well-trained and untrained subjects. Twenty-one well-trained male members of a police task force named “Cobra” and 38 non-active controls, matched by age, weight and height were participants of the study. The age range of these subjects was between 30 and 45 years. Subcutaneous adipose tissue thicknesses and body fat distributions were measured non-invasively by an optical device named the “Lipometer.” Statistics were performed with SPSS. We found that the body mass index did not show a difference between the two groups, whereas all Lipometer results were able to discriminate significantly between the trained and untrained subjects. Furthermore, the receiver operating characteristic curve analysis was calculated and all Lipometer measurements provided significant results up to a correct classification of all subjects of 86.4%, which was for the lateral thigh body site. In conclusion, the body mass index was not able to recognize the difference between trained and untrained participants, while body fat distribution measured with the Lipometer was able to distinguish more clearly the large body fat differences between these two groups. Impact statement Body mass index (BMI) is a common measure of body fatness but overestimates body fat in subjects with high muscle mass. We have developed previously a device named “Lipometer,” an alternative way to measure body fatness. We show herein that the Lipometer is able to distinguish more clearly (than the BMI) the large body fat differences between well-trained and untrained subjects. Thus, the Lipometer is superior to BMI with respect to body fat measurements.

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