scholarly journals Shear-sensitive adhesion enables size-independent adhesive performance in stick insects

2019 ◽  
Author(s):  
David Labonte ◽  
Marie-Yon Struecker ◽  
Aleksandra Birn-Jeffery ◽  
Walter Federle
Keyword(s):  
Body Weight ◽  
Adhesive Force ◽  
Whole Body ◽  
Small Animals ◽  
Shear Forces ◽  
Stick Insects ◽  
Adhesive Pads ◽  
The Difference ◽  
Large Animals ◽  
Adhesive Performance

The ability to climb with adhesive pads conveys significant advantages, and is hence widespread in the animal kingdom. The physics of adhesion predict that attachment is more challenging for large animals, whereas detachment is harder for small animals, due to the difference in surface-to-volume ratios. Here, we use stick insects to show that this problem is solved at both ends of the scale by linking adhesion to the applied shear force. Adhesive forces of individual insect pads, measured with perpendicular pull-offs, increased approximately in proportion to a linear pad dimension across instars. In sharp contrast, whole-body force measurements suggested area-scaling of adhesion. This discrepancy is explained by the presence of shear forces during whole-body measurements, as confirmed in experiments with pads sheared prior to detachment. When we applied shear forces proportional to either pad area or body weight, pad adhesion also scaled approximately with area or mass, respectively, providing a mechanism that can compensate for the size-related loss of adhesive performance predicted by isometry. We demonstrate that the adhesion-enhancing effect of shear forces is linked to pad sliding, which increased the maximum adhesive force per area sustainable by the pads. As shear forces in natural conditions are expected to scale with mass, sliding is more frequent and extensive in large animals, thus ensuring that large animals can attach safely, while small animals can still detach their pads effortlessly. Our results therefore help to explain how nature’s climbers maintain a dynamic attachment performance across seven orders of magnitude in body weight.

scholarly journals Shear-sensitive adhesion enables size-independent adhesive performance in stick insects

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191327 ◽  
Author(s):  
David Labonte ◽  
Marie-Yon Struecker ◽  
Aleksandra V. Birn-Jeffery ◽  
Walter Federle
Keyword(s):  
Body Weight ◽  
Adhesive Force ◽  
Whole Body ◽  
Small Animals ◽  
Shear Forces ◽  
Stick Insects ◽  
Adhesive Pads ◽  
The Difference ◽  
Large Animals ◽  
Adhesive Performance

The ability to climb with adhesive pads conveys significant advantages and is widespread in the animal kingdom. The physics of adhesion predict that attachment is more challenging for large animals, whereas detachment is harder for small animals, due to the difference in surface-to-volume ratios. Here, we use stick insects to show that this problem is solved at both ends of the scale by linking adhesion to the applied shear force. Adhesive forces of individual insect pads, measured with perpendicular pull-offs, increased approximately in proportion to a linear pad dimension across instars. In sharp contrast, whole-body force measurements suggested area scaling of adhesion. This discrepancy is explained by the presence of shear forces during whole-body measurements, as confirmed in experiments with pads sheared prior to detachment. When we applied shear forces proportional to either pad area or body weight, pad adhesion also scaled approximately with area or mass, respectively, providing a mechanism that can compensate for the size-related loss of adhesive performance predicted by isometry. We demonstrate that the adhesion-enhancing effect of shear forces is linked to pad sliding, which increased the maximum adhesive force per area sustainable by the pads. As shear forces in natural conditions are expected to scale with mass, sliding is more frequent and extensive in large animals, thus ensuring that large animals can attach safely, while small animals can still detach their pads effortlessly. Our results therefore help to explain how nature’s climbers maintain a dynamic attachment performance across seven orders of magnitude in body weight.

EMPTY BODY WEIGHTS, CARCASS WEIGHTS AND OFFAL PROPORTIONS IN BULLS AND STEERS OF DIFFERENT MATURE SIZE

1984 ◽  
Vol 64 (1) ◽  
pp. 53-57 ◽  
Author(s):  
S. D. M. JONES ◽  
R. E. ROMPALA ◽  
J. W. WILTON ◽  
C. H. WATSON
Keyword(s):  
Body Weight ◽  
Small Animal ◽  
High Energy ◽  
Carcass Weight ◽  
Small Animals ◽  
Beef Steers ◽  
Body Weights ◽  
Breed Crosses ◽  
Large Animals ◽  
Animal Size

Empty body weights, carcass weights and offal proportions were compared in 33 young beef bulls and 33 beef steers of different mature body size (35 small or mainly British breed crosses, 31 large or Continental crosses). All cattle were fed a high energy diet based on corn silage and high moisture corn from weaning to slaughter. Slaughter was carried out once 6 mm of fat had been attained at the 11/12th ribs, determined ultrasonically. Feed was removed 24 h and water 16 h prior to slaughter. The offal components were all weighed fresh and the alimentary components emptied of digesta. Bulls weighed 8.0% heavier (P < 0.05) than steers at slaughter, while large animals were 38.7% heavier (P < 0.0001) than small animals. Bulls and large animals had carcasses that dressed out 1.5% heavier than steers and small animals. To eliminate the effect of gutfill, carcass weights and offal components were expressed as a proportion of empty body weight. Bulls had a higher proportion of warm carcass weight and lower proportions of liver, spleen, heart, lungs, rumen, abomasum, large intestine and front feet relative to empty body weight than steers. Large animals had a greater proportion of warm carcass weight and hind feet, and a lower proportion of head, hide, liver, kidneys, omasum and small intestine relative to empty body weight than small animals. All castration by size interactions for liveweight, carcass weight, empty body weight and offal proportions were not significant. Castration and small animal size both increased the proportion of noncarcass parts relative to empty body weight in animals slaughtered at similar finish. Key words: Body, carcass, offal, bull, steer, maturity

Influence of Temperature on Performance in Guinea Pigs

1957 ◽  
Vol 190 (3) ◽  
pp. 457-458 ◽  
Author(s):  
Charles G. Wilber
Keyword(s):  
Low Temperatures ◽  
Guinea Pigs ◽  
Peak Performance ◽  
Albino Rats ◽  
Small Animals ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Endocrine Factors ◽  
The Difference ◽  
Large Animals

Guinea pigs were forced to swim to total exhaustion in water at various temperatures. Small animals (400 gm) showed peak performance at about 40°C, large ones (1000 gm) at about 35°C. Large animals swam longer at low temperatures but shorter at high temperatures than did small ones. At 35°C all guinea pigs swam for an average of about 150 minutes. In general this species shows much less capacity for swimming than do albino rats. The difference may be related to diet or to endocrine factors.

scholarly journals Influence of mild cold on 24 h energy expenditure in ‘normally’ clothed adults

1990 ◽  
Vol 63 (3) ◽  
pp. 481-488 ◽  
Author(s):  
P. M. Warwick ◽  
R. Busby
Keyword(s):  
Body Weight ◽  
Individual Differences ◽  
Energy Expenditure ◽  
Dietary Intake ◽  
Weight Status ◽  
Whole Body ◽  
Body Weight Status ◽  
Two Temperatures ◽  
The Difference

Ten subjects aged 19–35 years (four men and six women) underwent two measurements of 24 h energy expenditure (EE) in a whole-body respiration calorimeter, one at a temperature of 28° and one at 20°. Choice of clothing was allowed. Dietary intake was standardized and subjects were asked to follow the same pattern of activity during both measurements. Mean 24 h EE was significantly greater at the cooler temperature by 5.0 (SD 5.5) %, with individual differences ranging from 4.6% lower to 12.6% higher. The difference in EE at the two temperatures was similar during the day and the night and occurred even though subjects wore more clothes and used more bedding at 20°. No relationship was observed between response to 20° and body-weight status. In conclusion, the assumption that mild cold is unlikely to affect EE in subjects wearing normal clothing may be incorrect.

scholarly journals Sliding-induced adhesion of stiff polymer microfibre arrays. II. Microscale behaviour

2008 ◽  
Vol 5 (25) ◽  
pp. 845-853 ◽  
Author(s):  
Bryan Schubert ◽  
Jongho Lee ◽  
Carmel Majidi ◽  
Ronald S Fearing
Keyword(s):  
Shear Force ◽  
Strong Dependence ◽  
Adhesive Force ◽  
Shear Forces ◽  
Spherical Probe ◽  
Adhesive Pads ◽  
Normal Adhesion ◽  
Fibre Angle ◽  
First Time ◽  
Adhesion Effect

The adhesive pads of geckos provide control of normal adhesive force by controlling the applied shear force. This frictional adhesion effect is one of the key principles used for rapid detachment in animals running up vertical surfaces. We developed polypropylene microfibre arrays composed of vertical, 0.3 μm radius fibres with elastic modulus of 1 GPa which show this effect for the first time using a stiff polymer. In the absence of shear forces, these fibres show minimal normal adhesion. However, sliding parallel to the substrate with a spherical probe produces a frictional adhesion effect which is not seen in the flat control. A cantilever model for the fibres and the spherical probe indicates a strong dependence on the initial fibre angle. A novel feature of the microfibre arrays is that adhesion improves with use. Repeated shearing of fibres temporarily increases maximum shear and pull-off forces.

scholarly journals The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness

2020 ◽  
Author(s):  
Austin M. Garner ◽  
Michael C. Wilson ◽  
Caitlin Wright ◽  
Anthony P. Russell ◽  
Peter H. Niewiarowski ◽  
...  
Keyword(s):  
Functional Morphology ◽  
Empirical Work ◽  
Field Configuration ◽  
Clinal Variation ◽  
Adhesive Systems ◽  
Adhesive Pads ◽  
The Difference ◽  
Biological Adhesive ◽  
Pattern Of Variation ◽  
Adhesive Performance

AbstractThe functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings introduce Anolis lizards as an additional source of inspiration for bio-inspired design and set the stage for comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

Evaluation of a New Preparation of Urokinase

1973 ◽  
Vol 30 (01) ◽  
pp. 114-122
Author(s):  
C.R.M Prentice ◽  
K.M Rogers ◽  
G.P McNicol
Keyword(s):  
Body Weight ◽  
Maintenance Therapy ◽  
Initial Dose ◽  
Fibrinolytic Activity ◽  
Pharmacological Effect ◽  
Whole Body ◽  
Fibrinolytic Agent ◽  
Thromboplastic Activity

SummaryThe pharmacological effect of a new preparation of urokinase (Leo) has been studied, both in vitro and in six patients suffering from thrombo-embolic disorders. It was a non-toxic, effective fibrinolytic agent if given in sufficient dosage. A regimen consisting of an initial dose of 7,200 ploug units per kg body weight, followed by hourly maintenance therapy with 3,600 ploug units per kg intravenously, gave satisfactory evidence of whole body fibrinolytic activity. The preparation had minor but insignificant thromboplastic activity both when assayed in the laboratory and when given to patients.

Kinematic contribution and synchronization of the trunk, hip, and knee during free-dynamic lifting

2003 ◽  
Vol 3 (2) ◽  
pp. 99-108
Author(s):  
Kermit G. Davis ◽  
Riley E. Splittstoesser ◽  
William S. Marras
Keyword(s):  
Whole Body ◽  
Knee Height ◽  
Squat Lifting ◽  
The Difference ◽  
Free Dynamic ◽  
Body Lifting ◽  
And Task ◽  
Kinematic Contribution ◽  
Stoop Lifting

Although there have been numerous studies evaluating the difference between stooped and squat lifting styles, there remains a lack of understanding of whole body kinematics during unrestricted lifting. The current study evaluated nine males and nine females while lifting two box weights (9.1 kg, 18.2 kg) from five origins below the waist (0, 19, 38, 57, and 76 cm above the floor) and from three task asymmetries (sagittally symmetric, 45° clockwise, 45° counter-clockwise). While the lifting style was significantly influenced by the height of lift origin and to a lesser extent gender, box weight, and task asymmetry, none of the conditions resulted in pure squat or stoop lifting style. However, for lifts above knee height, the lifting style resembled more of a stoop lift while lifts originating below knee height were more of a squat lift. As the origin moved closer to the floor, participants relied more on their hips to accomplish the sagittal flexion but overall adopted a more coordinated whole-body lifting style. All together, as more sagittal flexion is required, more joints are relied upon in a more coordinated effort. The current study indicates that caution needs to be exercised when applying results of pure squat or pure stoop lifting studies to free-style (realistic) lifting.

scholarly journals In Vivo Radioprotective Activity of Cell-Permeable Bifunctional Antioxidant Enzyme GST-TAT-SOD against Whole-Body Ionizing Irradiation in Mice

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Jianru Pan ◽  
Huocong He ◽  
Ying Su ◽  
Guangjin Zheng ◽  
Junxin Wu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Antioxidant Activity ◽  
Body Weight ◽  
Whole Body ◽  
White Pulp ◽  
Radioprotective Activity ◽  
Significant Difference ◽  
Wbc Count

GST-TAT-SOD was the fusion of superoxide dismutase (SOD), cell-permeable peptide TAT, and glutathione-S-transferase (GST). It was proved to be a potential selective radioprotector in vitro in our previous work. This study evaluated the in vivo radioprotective activity of GST-TAT-SOD against whole-body irradiation. We demonstrated that intraperitoneal injection of 0.5 ml GST-TAT-SOD (2 kU/ml) 2 h before the 6 Gy whole-body irradiation in mice almost completely prevented the splenic damage. It could significantly enhance the splenic antioxidant activity which kept the number of splenic white pulp and consequently resisted the shrinkage of the spleen. Moreover, the thymus index, hepatic antioxidant activity, and white blood cell (WBC) count of peripheral blood in irradiated mice pretreated with GST-TAT-SOD also remarkably increased. Although the treated and untreated irradiated mice showed no significant difference in the growth rate of animal body weight at 7 days postirradiation, the highest growth rate of body weight was observed in the GST-TAT-SOD-pretreated group. Furthermore, GST-TAT-SOD pretreatment increased resistance against 8 Gy whole-body irradiation and enhanced 30 d survival. The overall effect of GST-TAT-SOD seemed to be a bit more powerful than that of amifostine. In conclusion, GST-TAT-SOD would be a safe and potentially promising radioprotector.

Seasonal variations in wool growth and heat tolerance of sheep. I. Wool growth

1960 ◽  
Vol 11 (1) ◽  
pp. 75 ◽  
Author(s):  
M Wodzicka
Keyword(s):  
Body Weight ◽  
Day Treatment ◽  
The Other ◽  
Seasonal Rhythm ◽  
Group Iii ◽  
Wool Growth ◽  
Group I ◽  
The Mean ◽  
Group Ii ◽  
The Difference

The monthly wool growth of three groups of rams was studied at Beltsville, Maryland. Group I received natural daylight (at 38° 53' N.) and was shorn monthly. Group II had a 7:17 hours of daylight to hours of darkness rhythm and was shorn every 6 months, once in winter and once in summer. Group III received natural daylight and was likewise shorn every 6 months. The rams of all groups produced more wool in summer than in winter. This difference was significant (P<0.001). The mean body weight and food intake were both greater in the winter months, which indicated that the seasonal rhythm of wool growth was not a consequence of poorer feeding in winter. The rams which were shorn monthly (group I) grew considerably more wool than the other two groups, but the difference was not statistically significant. The short-day treatment of group II did not increase the annual wool production nor decrease the seasonal rhythm of wool growth. The balance of evidence from this and other experiments indicates that temperature rather than light controls the seasonal rhythm of wool growth.

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