Articoli di riviste: "Animal mechanics"

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Alexander, R. McNeill. "Mechanics of animal movement". Current Biology 15, n. 16 (agosto 2005): R616—R619. http://dx.doi.org/10.1016/j.cub.2005.08.016.

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Kalinowski, Anna Maria. "“My pockets are full”: The Emotional and Mechanical Function of Goodbyes in Animal Crossing". Animal Crossing Special Issue 13, n. 22 (16 febbraio 2021): 59–71. http://dx.doi.org/10.7202/1075263ar.

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This article focuses on goodbyes within the Animal Crossing series, describing them as an important but often overlooked mechanic afforded through the inventory space. Beginning with defining the general mechanics withing the series, the article highlights the value of inventory space and argues that inventory space affords the central mechanic of collecting to emerge. As inventory space is not infinite, collecting is accompanied by the necessary mechanic of goodbyes. In order to make more room to collect players will be faced with choices of departing from both items and villagers, the game’s NPCs (Non-Playable Characters), emphasizing goodbyes’ mechanical and emotional function within this virtual world. Ultimately, this article concludes by highlighting how these mechanics serve to emphasize the parasocial attachments and agency players encounter when faced with the dilemma of departure.

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Gans, Carl. "Animal Mechanics. R. McNeill Alexander". Quarterly Review of Biology 60, n. 2 (giugno 1985): 227. http://dx.doi.org/10.1086/414369.

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Blake, Robert W. "Mechanics and physiology of animal swimming". Journal of Experimental Marine Biology and Ecology 191, n. 1 (agosto 1995): 131–32. http://dx.doi.org/10.1016/0022-0981(95)90071-3.

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Gomes, R. F. M., X. Shen, R. Ramchandani, R. S. Tepper e J. H. T. Bates. "Comparative respiratory system mechanics in rodents". Journal of Applied Physiology 89, n. 3 (1 settembre 2000): 908–16. http://dx.doi.org/10.1152/jappl.2000.89.3.908.

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Because of the wide utilization of rodents as animal models in respiratory research and the limited data on measurements of respiratory input impedance (Zrs) in small animals, we measured Zrs between 0.25 and 9.125 Hz at different levels (0–7 hPa) of positive end-expiratory pressure (PEEP) in mice, rats, guinea pigs, and rabbits using a computer-controlled small-animal ventilator (Schuessler TF and Bates JHT, IEEE Trans Biomed Eng 42: 860–866, 1995). Zrs was fitted with a model, including a Newtonian resistance (R) and inertance in series with a constant-phase tissue compartment characterized by tissue damping (Gti) and elastance (Hti) parameters. Inertance was negligible in all cases. R, Gti, and Hti were normalized to body weight, yielding normalized R, Gti, and Hti (NHti), respectively. Normalized R tended to decrease slightly with PEEP and increased with animal size. Normalized Gti had a minimal dependence on PEEP. NHti decreased with increasing PEEP, reaching a minimum at ∼5 hPa in all species except mice. NHti was also higher in mice and rabbits compared with guinea pigs and rats at low PEEPs, which we conclude is probably due to a relatively smaller air space volume in mice and rabbits. Our data also suggest that smaller rodents have proportionately wider airways than do larger animals. We conclude that a detailed, comparative study of respiratory system mechanics shows some evidence of structural differences among the lungs of various species but that, in general, rodent lungs obey scaling laws similar to those described in other species.

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Dudley, R., e P. Chai. "Animal flight mechanics in physically variable gas mixtures". Journal of Experimental Biology 199, n. 9 (1 settembre 1996): 1881–85. http://dx.doi.org/10.1242/jeb.199.9.1881.

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Empirical studies of animal flight performance have generally been implemented within the contemporary atmosphere. Experimental alteration of the physical composition of gas mixtures, however, permits construction of novel flight media and the non-invasive manipulation of flight biomechanics. For example, replacement of atmospheric nitrogen with various noble gases results in a tenfold variation in air density at a constant oxygen concentration. Such variation in air density correspondingly elicits extraordinary biomechanical effort from flying animals; hummingbirds and euglossine orchid bees hovering in such low-density but normoxic mixtures have demonstrated exceptionally high values for the mechanical power output of aerobic flight muscle. As with mechanical power, lift coefficients during hovering increase at low air densities in spite of a concomitant decline in the Reynolds number of the wings. The physical effects of variable gas density may also be manifest in morphological and physiological adaptations of animals to flight across altitudinal gradients. Global variation in atmospheric composition during the late Paleozoic may also have influenced the initial evolution and subsequent diversification of ancestral pterygotes. For the present-day experimenter, the use of physically variable flight media represents a versatile opportunity to explore the range of kinematic and aerodynamic modulation available to flying animals.

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Pouillard, Violette. "Animal Biographies: Beyond Archetypal Figures". Journal of Animal Ethics 12, n. 2 (1 ottobre 2022): 172–78. http://dx.doi.org/10.5406/21601267.12.2.07.

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Abstract The biographies of animal celebrities published by the historians John Simons and Eric Baratay aim to place animals in and of themselves at the center of academic narratives. Both excavate the lived experiences concealed behind official discourses and collective representations, notably by relying on cross-fertilization with ethological research. They unveil the ways in which information was reshaped in order to portray animal celebrities as benevolent members of human-animal communities, and thereby shed light on the mechanics of animal commodification. The close examination of a few individual animal trajectories enlightens the condition of many historical animals living under human tutelage in the 19th and early 20th century and highlights long-term historical evolutions, such as the succession of animal cultures and generations largely determined by human actions.

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Xiao, Shuhai. "Mitotic topologies and mechanics of Neoproterozoic algae and animal embryos". Paleobiology 28, n. 2 (2002): 244–50. http://dx.doi.org/10.1666/0094-8373(2002)028<0244:mtamon>2.0.co;2.

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Cell division is a key biological process in growth, morphogenesis, and reproduction. Despite our improved understanding of the genetics and dynamics of cell division in all major groups of living organisms, paleontological evidence for cell division is largely restricted to silicified (and some carbonaceous) algae and vascular plants where three-dimensional observation is possible. Animal cell division has been documented in the fossil record to a lesser extent; however, such knowledge is highly desirable in the recently revitalized field of evolutionary developmental biology. Two fundamentally different mitotic cell division topologies are preserved in late Neoproterozoic Doushantuo phosphorites (ca. 550–600 million years old) in South China. Doushantuo algal cells (∼20 μm in diameter) are successively cleaved by mitotic division planes that are offset but not deformed by subsequent cytokinesis. Mitotic division planes in successively cleaving Doushantuo animal embryos (several hundred microns in diameter) are also offset. However, in sharp contrast to Doushantuo algae, Doushantuo animal blastomeres repeatedly shift to mechanically stable configurations by disturbing preexisting division planes. This divergence reflects the underlying cytological and developmental differences between algae and animals. Specifically, the presence/absence of rigid cell walls and different cytokinetic mechanisms, coupled with mechanics at mitotic offsets, contribute to the diverging mitotic topologies in Doushantuo algae and animal embryos. These findings not only confirm previous interpretation of Doushantuo fossils but also provide direct paleontological evidence of cell movement in the development of these early animal fossils.

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Oliveira, Maria A., Alembert E. Lino-Alvarado, Henrique T. Moriya e Renato L. Vitorasso. "Drug class effects on respiratory mechanics in animal models: access and applications". Experimental Biology and Medicine 246, n. 9 (18 febbraio 2021): 1094–103. http://dx.doi.org/10.1177/1535370221993095.

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Assessment of respiratory mechanics extends from basic research and animal modeling to clinical applications in humans. However, to employ the applications in human models, it is desirable and sometimes mandatory to study non-human animals first. To acquire further precise and controlled signals and parameters, the animals studied must be further distant from their spontaneous ventilation. The majority of respiratory mechanics studies use positive pressure ventilation to model the respiratory system. In this scenario, a few drug categories become relevant: anesthetics, muscle blockers, bronchoconstrictors, and bronchodilators. Hence, the main objective of this study is to briefly review and discuss each drug category, and the impact of a drug on the assessment of respiratory mechanics. Before and during the positive pressure ventilation, the experimental animal must be appropriately sedated and anesthetized. The sedation will lower the pain and distress of the studied animal and the plane of anesthesia will prevent the pain. With those drugs, a more controlled procedure is carried out; further, because many anesthetics depress the respiratory system activity, a minimum interference of the animal’s respiration efforts are achieved. The latter phenomenon is related to muscle blockers, which aim to minimize respiratory artifacts that may interfere with forced oscillation techniques. Generally, the respiratory mechanics are studied under appropriate anesthesia and muscle blockage. The application of bronchoconstrictors is prevalent in respiratory mechanics studies. To verify the differences among studied groups, it is often necessary to challenge the respiratory system, for example, by pharmacologically inducing bronchoconstriction. However, the selected bronchoconstrictor, doses, and administration can affect the evaluation of respiratory mechanics. Although not prevalent, studies have applied bronchodilators to return (airway resistance) to the basal state after bronchoconstriction. The drug categories can influence the mathematical modeling of the respiratory system, systemic conditions, and respiratory mechanics outcomes.

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Chiou, Kevin, e Eva-Maria S. Collins. "Why we need mechanics to understand animal regeneration". Developmental Biology 433, n. 2 (gennaio 2018): 155–65. http://dx.doi.org/10.1016/j.ydbio.2017.09.021.

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Fenwick, Axel J., Vivek P. Jani, David A. Kass e Anthony Cammarato. "HFpEF animal models display differences in myofibril mechanics". Biophysical Journal 122, n. 3 (febbraio 2023): 122a. http://dx.doi.org/10.1016/j.bpj.2022.11.830.

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Bates, Jason H. T., Mercedes Rincon e Charles G. Irvin. "Animal models of asthma". American Journal of Physiology-Lung Cellular and Molecular Physiology 297, n. 3 (settembre 2009): L401—L410. http://dx.doi.org/10.1152/ajplung.00027.2009.

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Studies in animal models form the basis for much of our current understanding of the pathophysiology of asthma, and are central to the preclinical development of drug therapies. No animal model completely recapitulates all features of the human disease, however. Research has focused primarily on ways to generate allergic inflammation by sensitizing and challenging animals with a variety of foreign proteins, leading to an increased understanding of the immunological factors that mediate the inflammatory response and its physiological expression in the form of airways hyperresponsiveness. Animal models of exaggerated airway narrowing are also lending support to the notion that asthma may represent an abnormality of the airway smooth muscle. The mouse is now the species of choice for asthma research involving animals. This presents practical challenges for physiological study because the mouse is so small, but modern imaging methodologies, coupled with the forced oscillation technique for measuring lung mechanics, have allowed the asthma phenotype in mice to be precisely characterized.

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Schipper, Henk, Sander Kranenbarg, Johan van Leeuwen, Merel Gijsen, Monique Haazelager e Mark van Turnhout. "Quantitative description of collagen structure in the articular cartilage of the young and adult equine distal metacarpus". Animal Biology 58, n. 4 (2008): 353–70. http://dx.doi.org/10.1163/157075608x383674.

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AbstractThe orientation and organisation of collagen fibrils play an important role in the mechanical functioning of the articular cartilage (AC) that covers the surfaces in the diarthrodial joints. In the adult animal, typically an arcade like 'Benninghoff structure' is found. Because the remodelling capacity of the collagen network in the adult animal is limited, this Benninghoff structure needs to develop before the animal reaches maturity, and it needs to develop correctly. The aim of this study is to use quantitative polarised light microscopy (qPLM) and scanning electron microscopy (SEM) techniques to investigate if this Benninghoff structure is already present in the young animal, and to quantitatively investigate possible differences in collagen structure in the equine distal metacarpus of the young and adult animal. In total, 21 forelimbs of 13 horses are used. In animals of age 10 months and older, we find an arcade like Benninghoff structure for the collagen fibril network in both the qPLM and SEM study. The qPLM study shows that the collagen's predominant orientation is parallel to the articular surface throughout the entire cartilage depth in two animals directly after birth. These findings are supported by SEM results on a foal. We conclude that structural remodelling of the collagen network in AC occurs in the first months after birth. Because animals start with collagen parallel to the articular surface and need to remodel this structure to a Benninghoff architecture, and because collagen structure is an important parameter for AC mechanics and mechanobiology, these results suggest implications for AC epigenetics.

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Usherwood, James Richard (Jim). "The muscle-mechanical compromise framework: Implications for the scaling of gait and posture". Journal of Human Kinetics 52, n. 1 (1 settembre 2016): 107–14. http://dx.doi.org/10.1515/hukin-2015-0198.

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Abstract Many aspects of animal and human gait and posture cannot be predicted from purely mechanical work minimization or entirely based on optimizing muscle efficiency. Here, the Muscle-Mechanical Compromise Framework is introduced as a conceptual paradigm for considering the interactions and compromises between these two objectives. Current assumptions in implementing the Framework are presented. Implications of the compromise are discussed and related to the scaling of running mechanics and animal posture.

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Dzendolet, Ernest. "On the Theory of Behavioral Mechanics". Psychological Reports 85, n. 3 (dicembre 1999): 707–42. http://dx.doi.org/10.2466/pr0.1999.85.3.707.

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The Theory of Behavioral Mechanics is the behavioral analogue of Newton's laws of motion, with the rate of responding in operant conditioning corresponding to physical velocity. In an earlier work, the basic relation between rate of responding and sessions under two FI schedules and over a range of commonly used session values had been shown to be a power function. Using that basic relation, functions for behavioral acceleration, mass, and momentum are derived here. Data from other laboratories also support the applicability of a power function to VI schedules. A particular numerical value is introduced here to be the standard reference value for the behavioral force under the VI-60-S schedule. This reference allows numerical values to be calculated for the behavioral mass and momentum of individual animals. A comparison of the numerical values of the momenta of two animals can be used to evaluate their relative resistances to change, e.g., to extinction, which is itself viewed as a continuously changing behavioral force being imposed on the animal. This overall numerical approach allows behavioral force-values to be assigned to various experimental conditions such as the evaluation of the behavioral force of a medication dosage.

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McCormack, G. S., R. H. Moreno, J. C. Hogg e P. D. Pare. "Lung mechanics in papain-treated rabbits". Journal of Applied Physiology 60, n. 1 (1 gennaio 1986): 242–46. http://dx.doi.org/10.1152/jappl.1986.60.1.242.

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To further investigate the effects of airway cartilage softening on static and dynamic lung mechanics, 11 rabbits were treated with 100 mg/kg iv papain, whereas 9 control animals received no pretreatment. Lung mechanics were studied 24 h after papain injection. There was no significant difference in lung volumes, lung pressure-volume curves, or chest wall compliance. Papain-treated rabbits showed increased lung resistance: 91 +/- 63 vs. 39 +/- 22 cmH2O X l-1 X s (mean +/- SD; P less than 0.05), decreased maximal expiratory flows at all lung volumes, and preserved density dependence of maximal expiratory flows. We conclude that increased airway wall compliance is probably the mechanism that limited maximal expiratory flow in this animal model. In addition the increased lung resistance suggests that airway cartilage plays a role in the regulation of airway caliber during quiet tidal breathing.

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Kiss, Attila, e Gábor Pusztai. "Animal Farm—a complex artificial life 3D framework". Acta Universitatis Sapientiae, Informatica 13, n. 1 (1 giugno 2021): 60–85. http://dx.doi.org/10.2478/ausi-2021-0004.

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Abstract The development of computer-generated ecosystem simulations are becoming more common due to the greater computational capabilities of machines. Because natural ecosystems are very complex, simplifications are required for implementation. This simulation environment o er a global view of the system and generate a lot of data to process and analyse, which are difficult or impossible to do in nature. 3D simulations, besides of the scientific advantages in experiments, can be used for presentation, educational and entertainment purposes too. In our simulated framework (Animal Farm) we have implemented a few basic animal behaviors and mechanics to observe in 3D. All animals are controlled by an individual logic model, which determines the next action of the animal, based on their needs and surrounding environment.

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Wootton, Robin. "Charlie Ellington (1952-2019) – a career in animal flight mechanics". International Journal of Odonatology 23, n. 1 (2 gennaio 2020): 5–8. http://dx.doi.org/10.1080/13887890.2019.1682372.

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De Groot, Jean. "Dunamis and the Science of Mechanics: Aristotle on Animal Motion". Journal of the History of Philosophy 46, n. 1 (2008): 43–67. http://dx.doi.org/10.1353/hph.2008.1828.

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Hansen, Paul. "Becoming bovine: Mechanics and metamorphosis in Hokkaido's animal-human-machine". Journal of Rural Studies 33 (gennaio 2014): 119–30. http://dx.doi.org/10.1016/j.jrurstud.2013.02.001.

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Abramowitch, Steven D., Andrew Feola, Zegbeh Jallah e Pamela A. Moalli. "Tissue mechanics, animal models, and pelvic organ prolapse: A review". European Journal of Obstetrics & Gynecology and Reproductive Biology 144 (maggio 2009): S146—S158. http://dx.doi.org/10.1016/j.ejogrb.2009.02.022.

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Wang, Liyu, Luzius Brodbeck e Fumiya Iida. "Mechanics and energetics in tool manufacture and use: a synthetic approach". Journal of The Royal Society Interface 11, n. 100 (6 novembre 2014): 20140827. http://dx.doi.org/10.1098/rsif.2014.0827.

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Tool manufacture and use are observed not only in humans but also in other animals such as mammals, birds and insects. Manufactured tools are used for biomechanical functions such as effective control of fluids and small solid objects and extension of reaching. These tools are passive and used with gravity and the animal users' own energy. From the perspective of evolutionary biology, manufactured tools are extended phenotypes of the genes of the animal and exhibit phenotypic plasticity. This incurs energetic cost of manufacture as compared to the case with a fixed tool. This paper studies mechanics and energetics aspects of tool manufacture and use in non-human beings. Firstly, it investigates possible mechanical mechanisms of the use of passive manufactured tools. Secondly, it formulates the energetic cost of manufacture and analyses when phenotypic plasticity benefits an animal tool maker and user. We take a synthetic approach and use a controlled physical model, i.e. a robot arm. The robot is capable of additively manufacturing scoop and gripper structures from thermoplastic adhesives to pick and place fluid and solid objects, mimicking primates and birds manufacturing tools for a similar function. We evaluate the effectiveness of tool use in pick-and-place and explain the mechanism for gripper tools picking up solid objects with a solid-mechanics model. We propose a way to formulate the energetic cost of tool manufacture that includes modes of addition and reshaping, and use it to analyse the case of scoop tools. Experiment results show that with a single motor trajectory, the robot was able to effectively pick and place water, rice grains, a pebble and a plastic box with a scoop tool or gripper tools that were manufactured by itself. They also show that by changing the dimension of scoop tools, the energetic cost of tool manufacture and use could be reduced. The work should also be interesting for engineers to design adaptive machines.

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Costello, John H., Sean P. Colin, John O. Dabiri, Brad J. Gemmell, Kelsey N. Lucas e Kelly R. Sutherland. "The Hydrodynamics of Jellyfish Swimming". Annual Review of Marine Science 13, n. 1 (3 gennaio 2021): 375–96. http://dx.doi.org/10.1146/annurev-marine-031120-091442.

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Jellyfish have provided insight into important components of animal propulsion, such as suction thrust, passive energy recapture, vortex wall effects, and the rotational mechanics of turning. These traits are critically important to jellyfish because they must propel themselves despite severe limitations on force production imposed by rudimentary cnidarian muscular structures. Consequently, jellyfish swimming can occur only by careful orchestration of fluid interactions. Yet these mechanics may be more broadly instructive because they also characterize processes shared with other animal swimmers, whose structural and neurological complexity can obscure these interactions. In comparison with other animal models, the structural simplicity, comparative energetic efficiency, and ease of use in laboratory experimentation allow jellyfish to serve as favorable test subjects for exploration of the hydrodynamic bases of animal propulsion. These same attributes also make jellyfish valuable models for insight into biomimetic or bioinspired engineeringof swimming vehicles. Here, we review advances in understanding of propulsive mechanics derived from jellyfish models as a pathway toward the application of animal mechanics to vehicle designs.

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Daoud, Ehab, e Claudio Franck. "Alveolar mechanics: A new concept in respiratory monitoring". Journal of Mechanical Ventilation 3, n. 4 (15 dicembre 2022): 178–88. http://dx.doi.org/10.53097/jmv.10065.

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A detailed understanding of respiratory mechanics during mechanical ventilation aids diagnostic accuracy and facilitates close monitoring of patient progress, allowing individualized ventilator adjustments aimed at minimizing ventilator induced lung injury. Respiratory mechanics can be described in terms of total respiratory, lung, and chest wall components and include compliance, resistance and are dependent on tidal volume, airway pressures, and flow for calculation. The interplay between the respiratory mechanics and ventilator delivered volume, flow, and pressure have an important role in the development of ventilator induced lung injury. The knowledge of alveolar dynamics and mechanics in the critically ill are lacking with much information originating mainly from bench and animal models of healthy and injured lungs. In this article we introduce the concept of alveolar compliance, resistance that depend on measuring the trans-alveolar pressure using esophageal balloon manometry and alveolar tidal volume using volumetric capnometry. This may have multiple implications in the understanding of components of ventilator induced lung injury specifically alveolar stress, strain, and mechanical power. Further studies are warranted to further understanding the monitoring and usefulness of alveolar mechanics. Keywords: Alveolar compliance and resistance, alveolar tidal volume, trans-alveolar pressure, alveolar stress and strain, alveolar mechanical power

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Liu, Sheng Xiong, Zhi Yong Yin, Kui Li, Dai Qin Tao, Ya Fang Luo, Cui Lian Ye, Chen Xu, Qin Jiang, Shu Ying Li e Yuan Sun. "Experimental Design and Mechanics Study on Brain Injury Tolerance under Sagittal Angular Acceleration Based on Shearing Strain Equivalent Coupling Method". Applied Mechanics and Materials 387 (agosto 2013): 55–58. http://dx.doi.org/10.4028/www.scientific.net/amm.387.55.

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s: Brain impact injury is the leading cause of death in traffic accidents. In this paper, a brain multi-functional rotary impacting platform will first be set up. After this, the living animal brain sagittally rotary impacts will be executed and the injury tolerance will be achieved. Then, the sagittal physical models of animal and human brains will be produced and the four-point markers will be placed widely on the models sagittal sections. In succession, the high-speed camera and the three-dimension infrared motion analysis meter will be used to record the rotary impacting process, the exterior angular acceleration course and the shearing strain data of interior four-point markers. Thus, with the exterior angular acceleration course, the living animals experiments and the experiments based on the animal physical brain model can be coupled equivalently. In the same way, through the maximum shearing strain data of interior four-point markers, the experiments based on the animal physical brain model can be equivalently coupled with the experiments based on the human physical brain model. Finally, according to the comparability in pathology and physiology between animal and human brain tissue, the injury tolerance of human brain under its sagittally rotary impacts can expect to be obtained through the mechanics study.

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Hughey, Lacey F., Andrew M. Hein, Ariana Strandburg-Peshkin e Frants H. Jensen. "Challenges and solutions for studying collective animal behaviour in the wild". Philosophical Transactions of the Royal Society B: Biological Sciences 373, n. 1746 (26 marzo 2018): 20170005. http://dx.doi.org/10.1098/rstb.2017.0005.

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Mobile animal groups provide some of the most compelling examples of self-organization in the natural world. While field observations of songbird flocks wheeling in the sky or anchovy schools fleeing from predators have inspired considerable interest in the mechanics of collective motion, the challenge of simultaneously monitoring multiple animals in the field has historically limited our capacity to study collective behaviour of wild animal groups with precision. However, recent technological advancements now present exciting opportunities to overcome many of these limitations. Here we review existing methods used to collect data on the movements and interactions of multiple animals in a natural setting. We then survey emerging technologies that are poised to revolutionize the study of collective animal behaviour by extending the spatial and temporal scales of inquiry, increasing data volume and quality, and expediting the post-processing of raw data. This article is part of the theme issue ‘Collective movement ecology’.

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Zilianti, Camilla, Erfan Bashar, Anna Kyriakoudi e Matteo Pecchiari. "Interrupter Technique Revisited: Building an Experimental Mechanical Ventilator to Assess Respiratory Mechanics in Large Animals". Fluids 9, n. 6 (14 giugno 2024): 142. http://dx.doi.org/10.3390/fluids9060142.

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Large animals are increasingly used as experimental models of respiratory diseases. Precise characterization of respiratory mechanics requires dedicated equipment with specific characteristics which are difficult to find together in the same commercial device. In this work, we describe building and validation of a computer-controlled ventilator able to perform rapid airways occlusions during constant flow inflations followed by a prolonged inspiratory hold. A constant airflow is provided by a high pressure source (5 atm) connected to the breathing circuit by three proportional valves. The combined action of three 2-way valves produces the phases of the breath. During non-inspiratory breath phases, airflow is diverted to a flowmeter for precise feedback regulation of the proportional valves. A computer interface enables the user to change the breathing pattern, trigger test breaths or run predetermined breaths sequences. A respiratory system model was used to test the ability of the ventilator to correctly estimate interrupter resistance. The ventilator was able to produce a wide range of constant flows (0.1–1.6 L/s) with the selected timing. Errors in the measurement of interrupter resistance were small (1 ± 5% of the reference value). The device described reliably estimated interrupter resistance and can be useful as a measuring tool in large animal research.

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Neil, Thomas R., e Graham N. Askew. "Swimming mechanics and propulsive efficiency in the chambered nautilus". Royal Society Open Science 5, n. 2 (febbraio 2018): 170467. http://dx.doi.org/10.1098/rsos.170467.

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The chambered nautilus ( Nautilus pompilius ) encounters severe environmental hypoxia during diurnal vertical movements in the ocean. The metabolic cost of locomotion ( C met ) and swimming performance depend on how efficiently momentum is imparted to the water and how long on-board oxygen stores last. While propulsive efficiency is generally thought to be relatively low in jet propelled animals, the low C met in Nautilus indicates that this is not the case. We measured the wake structure in Nautilus during jet propulsion swimming, to determine their propulsive efficiency. Animals swam with either an anterior-first or posterior-first orientation. With increasing swimming speed, whole cycle propulsive efficiency increased during posterior-first swimming but decreased during anterior-first swimming, reaching a maximum of 0.76. The highest propulsive efficiencies were achieved by using an asymmetrical contractile cycle in which the fluid ejection phase was relatively longer than the refilling phase, reducing the volume flow rate of the ejected fluid. Our results demonstrate that a relatively high whole cycle propulsive efficiency underlies the low C met in Nautilus , representing a strategy to reduce the metabolic demands in an animal that spends a significant part of its daily life in a hypoxic environment.

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Muller, Eliara Solange, Mariléa Fátima Matiazzo, Angélica Soligo Cassol e Vanessa Barbisan Fortes. "CRIMES AGAINST WILD ANIMALS IN THE WEST OF SANTA CATARINA, BRAZIL: AN ANALYSIS FROM ASSESSMENTS AND SEIZURES CARRIED OUT BY THE ENVIRONMENTAL MILITARY POLICE OF CHAPECÓ". Revista Acta Ambiental Catarinense 19, n. 1 (4 luglio 2022): 01–20. http://dx.doi.org/10.24021/raac.v19i1.6108.

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Several reports carried out by public agencies are related to conducts that altogether may constitute animal trafficking, which, along with other anthropic practices, contribute to the process of decline in animal species. Our objective was to collect data on environmental crimes related to fauna in the area of jurisdiction of the Environmental Military Police of Chapecó (EMPC), in the state of Santa Catarina_Brazil. For that, a documentary survey was carried out in the archives of that organ from January/1999 to December/2017. Environmental crimes related to fauna comprised 196 complaints, with 56 of them resulting in assessments, and 1,016 animals were seized in 33 municipalities. Chapecó was the municipality with the largest number of cases (97 assessments/539 animals seized), but the per capita values are below of 56.2% of the surveyed municipalities. Out of the total number of animals seized, 980 were birds, 28 were mammals, six were lizards and two were turtles. Most of the animals seized were released into nature (752). It is likely that the data do not represent the actual amount of wild animals kept in captivity or hunted in the region because of the difficulty of the inspection and/or structure for proper allocation of the animals.

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Südy, Roberta, Gergely H. Fodor, André Dos Santos Rocha, Álmos Schranc, József Tolnai, Walid Habre e Ferenc Peták. "Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits". Journal of Applied Physiology 127, n. 1 (1 luglio 2019): 198–204. http://dx.doi.org/10.1152/japplphysiol.00048.2019.

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Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly used in respiratory research. Thus, we compared these contributions in intact-chest mice, rats, and rabbits and further characterized the influence of positive end-expiratory pressure (PEEP). Forced oscillation technique was applied to anesthetized mechanically ventilated healthy animals to obtain total respiratory system impedance (Zrs) at 0, 3, and 6 cmH2O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Zrs into pulmonary (ZL) and chest wall (Zcw) components. A model containing a frequency-independent Newtonian resistance (RN), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Zrs, ZL, and Zcw spectra. The contribution of Zcw to RN was negligible in all species and PEEP levels studied. However, the participation of Zcw in G and H was significant in all species and increased significantly with increasing PEEP and animal size (rabbit > rat > mice). Even in mice, the chest wall contribution to G and H was still considerable, reaching 47.0 ± 4.0(SE)% and 32.9 ± 5.9% for G and H, respectively. These findings demonstrate that airway parameters can be assessed from respiratory system mechanical measurements. However, the contribution from the chest wall should be considered when intact-chest measurements are used to estimate lung parenchymal mechanics in small laboratory models (even in mice), particularly at elevated PEEP levels. NEW & NOTEWORTHY In species commonly used in respiratory research (rabbits, rats, mice), esophageal pressure-based estimates revealed negligible contribution from the chest wall to the Newtonian resistance. Conversely, chest wall participation in the viscoelastic tissue mechanical parameters increased with body size (rabbit > rat > mice) and positive end-expiratory pressure, with contribution varying between 30 and 50%, even in mice. These findings demonstrate the potential biasing effects of the chest wall when lung tissue mechanics are inferred from intact-chest measurements in small laboratory animals.

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31

Etter, Tom, e H. Pierre Noyes. "Process, System, Causality, and Quantum Mechanics: A Psychoanalysis of Animal Faith". Physics Essays 12, n. 4 (dicembre 1999): 733–65. http://dx.doi.org/10.4006/1.3028803.

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32

Wheatley, S. "UPDATES ON THE MECHANICS AND REGULATION OF CYTOKINESIS IN ANIMAL CELLS". Cell Biology International 23, n. 12 (dicembre 1999): 797–803. http://dx.doi.org/10.1006/cbir.1999.0475.

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33

Daniel, Thomas L. "Forward flapping flight from flexible fins". Canadian Journal of Zoology 66, n. 3 (1 marzo 1988): 630–38. http://dx.doi.org/10.1139/z88-094.

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The mechanics and energetics of aquatic flight by the clearnose skate (Raja eglanteria) are examined with cinefilm and a new theoretical approach toward flight mechanics. Film analyses show that these animals move with a flapping, flexing wing that has a propulsive wave travelling rearward at twice the forward speed of the animal. A combination of blade-element theory and unsteady airfoil theory is used to examine the mechanics and energetics of this mode of locomotion. The theoretical analysis shows that (i) unsteady effects determine the overall performance of the wings, and (ii) there exist wing shapes that minimize the cost of transport or maximize the thrust. The theory indicates that the wings of swimming skates closely approach the minimum cost of transport. The results are extended to explore other modes of flapping wing propulsion, including those in animals whose wings deform passively in response to hydro- or aero-dynamic loads.

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34

Fomovsky, Gregory M., e Jeffrey W. Holmes. "Evolution of scar structure, mechanics, and ventricular function after myocardial infarction in the rat". American Journal of Physiology-Heart and Circulatory Physiology 298, n. 1 (gennaio 2010): H221—H228. http://dx.doi.org/10.1152/ajpheart.00495.2009.

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The mechanical properties of the healing scar are an important determinant of heart function following myocardial infarction. Yet the relationship between scar structure, scar mechanics, and ventricular function remains poorly understood, in part because no published study has tracked all of these factors simultaneously in any animal model. We therefore studied the temporal evolution of scar structure, scar mechanics, and left ventricular (LV) function in large anterior myocardial infarcts in rats. At 1, 2, 3, and 6 wk after left anterior descending coronary ligation, we examined LV function using sonomicrometry, infarct mechanical properties using biaxial mechanical testing, infarct structure using polarized light microscopy, and scar collagen content and cross-linking using biochemical assays. Healing infarcts in the rat were structurally and mechanically isotropic at all time points. Collagen content increased with time and was the primary determinant of scar mechanical properties. The presence of healing infarcts influenced systolic LV function through a rightward shift of the end-systolic pressure-volume relationship (ESPVR) that depended on infarct size, infarct collagen content, and LV dilation. We conclude that in sharp contrast to previous reports in large animal models, healing infarcts are structurally and mechanically isotropic in the standard rat model of myocardial infarction. On the basis of the regional strain patterns we observed in healing rat infarcts in this study and in healing pig infarcts in previous studies, we hypothesize that the local pattern of stretching determines collagen alignment in healing myocardial infarct scars.

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35

Daemen, Mat J., Frank J. H. Gijsen, Kim Van der Heiden e Ayla Hoogendoorn. "Animal models for plaque rupture: a biomechanical assessment". Thrombosis and Haemostasis 115, n. 03 (2016): 501–8. http://dx.doi.org/10.1160/th15-07-0614.

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SummaryRupture of atherosclerotic plaques is the main cause of acute cardiovascular events. Animal models of plaque rupture are rare but essential for testing new imaging modalities to enable diagnosis of the patient at risk. Moreover, they enable the design of new treatment strategies to prevent plaque rupture. Several animal models for the study of atherosclerosis are available. Plaque rupture in these models only occurs following severe surgical or pharmaceutical intervention. In the process of plaque rupture, composition, biology and mechanics each play a role, but the latter has been disregarded in many animal studies. The biomechanical environment for atherosclerotic plaques is comprised of two parts, the pressure-induced stress distribution, mainly - but not exclusively – influenced by plaque composition, and the strength distribution throughout the plaque, largely determined by the inflammatory state. This environment differs considerably between humans and most animals, resulting in suboptimal conditions for plaque rupture. In this review we describe the role of the biomechanical environment in plaque rupture and assess this environment in animal models that present with plaque rupture.

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36

Arold, Stephen P., Béla Suki, Adriano M. Alencar, Kenneth R. Lutchen e Edward P. Ingenito. "Variable ventilation induces endogenous surfactant release in normal guinea pigs". American Journal of Physiology-Lung Cellular and Molecular Physiology 285, n. 2 (agosto 2003): L370—L375. http://dx.doi.org/10.1152/ajplung.00036.2003.

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Variable or noisy ventilation, which includes random breath-to-breath variations in tidal volume (Vt) and frequency, has been shown to consistently improve blood oxygenation during mechanical ventilation in various models of acute lung injury. To further understand the effects of variable ventilation on lung physiology and biology, we mechanically ventilated 11 normal guinea pigs for 3 h using constant-Vt ventilation ( n = 6) or variable ventilation ( n = 5). After 3 h of ventilation, each animal underwent whole lung lavage for determination of alveolar surfactant content and composition, while protein content was assayed as a possible marker of injury. Another group of animals underwent whole lung lavage in the absence of mechanical ventilation to serve as an unventilated control group ( n = 5). Although lung mechanics did not vary significantly between groups, we found that variable ventilation improved oxygenation, increased surfactant levels nearly twofold, and attenuated alveolar protein content compared with animals ventilated with constant Vt. These data demonstrate that random variations in Vt promote endogenous release of biochemically intact surfactant, which improves alveolar stability, apparently reducing lung injury.

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37

Neves, Mario Fritsch, Daniel Arthur B. Kasal, Ana Rosa Cunha e Fernanda Medeiros. "Vascular Dysfunction as Target Organ Damage in Animal Models of Hypertension". International Journal of Hypertension 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/187526.

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Endothelial dysfunction is one of the main characteristics of chronic hypertension and it is characterized by impaired nitric oxide (NO) bioactivity determined by increased levels of reactive oxygen species. Endothelial function is usually evaluated by measuring the vasodilation induced by the local NO production stimulated by external mechanical or pharmacological agent. These vascular reactivity tests may be carried out in different models of experimental hypertension such as NO-deficient rats, spontaneously hypertensive rats, salt-sensitive rats, and many others. Wire myograph and pressurized myograph are the principal methods used for vascular studies. Usually, increasing concentrations of the vasodilator acetylcholine are added in cumulative manner to perform endothelium-dependent concentration-response curves. Analysis of vascular mechanics is relevant to identify arterial stiffness. Both endothelial dysfunction and vascular stiffness have been shown to be associated with increased cardiovascular risk.

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38

Blickhan, Reinhard, Andre Seyfarth, Hartmut Geyer, Sten Grimmer, Heiko Wagner e Michael Günther. "Intelligence by mechanics". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, n. 1850 (17 novembre 2006): 199–220. http://dx.doi.org/10.1098/rsta.2006.1911.

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Research on the biomechanics of animal and human locomotion provides insight into basic principles of locomotion and respective implications for construction and control. Nearly elastic operation of the leg is necessary to reproduce the basic dynamics in walking and running. Elastic leg operation can be modelled with a spring-mass model. This model can be used as a template with respect to both gaits in the construction and control of legged machines. With respect to the segmented leg, the humanoid arrangement saves energy and ensures structural stability. With the quasi-elastic operation the leg inherits the property of self-stability, i.e. the ability to stabilize a system in the presence of disturbances without sensing the disturbance or its direct effects. Self-stability can be conserved in the presence of musculature with its crucial damping property. To ensure secure foothold visco-elastic suspended muscles serve as shock absorbers. Experiments with technically implemented leg models, which explore some of these principles, are promising.

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39

Bose, Shirsha, Simin Li, Elisa Mele e Vadim V. Silberschmidt. "Exploring the Mechanical Properties and Performance of Type-I Collagen at Various Length Scales: A Progress Report". Materials 15, n. 8 (8 aprile 2022): 2753. http://dx.doi.org/10.3390/ma15082753.

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Collagen is the basic protein of animal tissues and has a complex hierarchical structure. It plays a crucial role in maintaining the mechanical and structural stability of biological tissues. Over the years, it has become a material of interest in the biomedical industries thanks to its excellent biocompatibility and biodegradability and low antigenicity. Despite its significance, the mechanical properties and performance of pure collagen have been never reviewed. In this work, the emphasis is on the mechanics of collagen at different hierarchical levels and its long-term mechanical performance. In addition, the effect of hydration, important for various applications, was considered throughout the study because of its dramatic influence on the mechanics of collagen. Furthermore, the discrepancies in reports of the mechanical properties of collagenous tissues (basically composed of 20–30% collagen fibres) and those of pure collagen are discussed.

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40

Bishai, John M., e Wayne Mitzner. "Effect of severe calorie restriction on the lung in two strains of mice". American Journal of Physiology-Lung Cellular and Molecular Physiology 295, n. 2 (agosto 2008): L356—L362. http://dx.doi.org/10.1152/ajplung.00514.2007.

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There is a body of literature in animal models that has suggested the development of emphysema following severe calorie restriction. This has led to the notion of “nutritional emphysema” that might have relevance in COPD patients. There have been few studies, however, that have looked closely at both the mechanics and lung structure in the same animals. In the present work, we examined lung mechanics and histological changes in two strains of mice that have substantial differences in alveolar size, the C57BL/6 and C3H/HeJ strains. We quantified the dynamic elastance and resistance at 2.5 Hz, the quasistatic pressure volume curve, and the alveolar chord lengths in lungs inflated to a lung capacity at 25–30 cmH2O. We found that after 2 or 3 wk of calorie restriction to 1/3 their normal diet, the lungs became stiffer with increased resistance. In addition, the lung capacity was also decreased. These mechanical changes were reversed after 2 wk on a normal ad libitum diet. Histology of the postmortem fixed lungs showed no changes in the mean alveolar chord lengths with calorie restriction. Although the baseline mechanics and alveolar size were quantitatively different in the two strains, both strains showed similar qualitative changes during the starvation and refeeding periods. Thus, in two strains of mice with genetically determined differences in alveolar size, neither the mechanics nor the histology show any evidence of emphysema-like changes with this severe caloric insult.

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41

Hsieh, S. Tonia. "Three-axis optical force plate for studies in small animal locomotor mechanics". Review of Scientific Instruments 77, n. 5 (maggio 2006): 054303. http://dx.doi.org/10.1063/1.2202910.

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42

Pennycuick, C. J. "The concept of energy height in animal locomotion: separating mechanics from physiology". Journal of Theoretical Biology 224, n. 2 (settembre 2003): 189–203. http://dx.doi.org/10.1016/s0022-5193(03)00157-7.

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43

Ansell, A. D. "Advances in comparative and environmental physiology, vol. 11: mechanics of animal locomotion". Journal of Experimental Marine Biology and Ecology 178, n. 2 (maggio 1994): 287–88. http://dx.doi.org/10.1016/0022-0981(94)90042-6.

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44

Feng, Xi Qiao, e Mao Sun. "About the special topic of mechanics and biomimetics of biomaterials and animal locomotion". Acta Mechanica Sinica 26, n. 1 (13 febbraio 2010): 3–4. http://dx.doi.org/10.1007/s10409-010-0333-8.

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45

Gautestad, Arild O. "Brownian motion or Lévy walk? Stepping towards an extended statistical mechanics for animal locomotion". Journal of The Royal Society Interface 9, n. 74 (28 marzo 2012): 2332–40. http://dx.doi.org/10.1098/rsif.2012.0059.

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Animals moving under the influence of spatio-temporal scaling and long-term memory generate a kind of space-use pattern that has proved difficult to model within a coherent theoretical framework. An extended kind of statistical mechanics is needed, accounting for both the effects of spatial memory and scale-free space use, and put into a context of ecological conditions. Simulations illustrating the distinction between scale-specific and scale-free locomotion are presented. The results show how observational scale (time lag between relocations of an individual) may critically influence the interpretation of the underlying process. In this respect, a novel protocol is proposed as a method to distinguish between some main movement classes. For example, the ‘power law in disguise’ paradox—from a composite Brownian motion consisting of a superposition of independent movement processes at different scales—may be resolved by shifting the focus from pattern analysis at one particular temporal resolution towards a more process-oriented approach involving several scales of observation. A more explicit consideration of system complexity within a statistical mechanical framework, supplementing the more traditional mechanistic modelling approach, is advocated.

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46

Farley, C. T., e T. C. Ko. "Mechanics of locomotion in lizards." Journal of Experimental Biology 200, n. 16 (1 agosto 1997): 2177–88. http://dx.doi.org/10.1242/jeb.200.16.2177.

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Lizards bend their trunks laterally with each step of locomotion and, as a result, their locomotion appears to be fundamentally different from mammalian locomotion. The goal of the present study was to determine whether lizards use the same two basic gaits as other legged animals or whether they use a mechanically unique gait due to lateral trunk bending. Force platform and kinematic measurements revealed that two species of lizards, Coleonyx variegatus and Eumeces skiltonianus, used two basic gaits similar to mammalian walking and trotting gaits. In both gaits, the kinetic energy fluctuations due to lateral movements of the center of mass were less than 5% of the total external mechanical energy fluctuations. In the walking gait, both species vaulted over their stance limbs like inverted pendulums. The fluctuations in kinetic energy and gravitational potential energy of the center of mass were approximately 180 degrees out of phase. The lizards conserved as much as 51% of the external mechanical energy required for locomotion by the inverted pendulum mechanism. Both species also used a bouncing gait, similar to mammalian trotting, in which the fluctuations in kinetic energy and gravitational potential energy of the center of mass were nearly exactly in phase. The mass-specific external mechanical work required to travel 1 m (1.5 J kg-1) was similar to that for other legged animals. Thus, in spite of marked lateral bending of the trunk, the mechanics of lizard locomotion is similar to the mechanics of locomotion in other legged animals.

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47

Green, P. A., M. J. McHenry e A. Rico-Guevara. "Mechanoethology: The Physical Mechanisms of Behavior". Integrative and Comparative Biology 61, n. 2 (14 giugno 2021): 613–23. http://dx.doi.org/10.1093/icb/icab133.

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Abstract Research that integrates animal behavior theory with mechanics—including biomechanics, physiology, and functional morphology—can reveal how organisms accomplish tasks crucial to their fitness. Despite the insights that can be gained from this interdisciplinary approach, biomechanics commonly neglects a behavioral context and behavioral research generally does not consider mechanics. Here, we aim to encourage the study of “mechanoethology,” an area of investigation intended to encompass integrative studies of mechanics and behavior. Using examples from the literature, including papers in this issue, we show how these fields can influence each other in three ways: (1) the energy required to execute behaviors is driven by the kinematics of movement, and mechanistic studies of movement can benefit from consideration of its behavioral context; (2) mechanics sets physical limits on what behaviors organisms execute, while behavior influences ecological and evolutionary limits on mechanical systems; and (3) sensory behavior is underlain by the mechanics of sensory structures, and sensory systems guide whole-organism movement. These core concepts offer a foundation for mechanoethology research. However, future studies focused on merging behavior and mechanics may reveal other ways by which these fields are linked, leading to further insights in integrative organismal biology.

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48

Fritzsche, Marco, Christoph Erlenkämper, Emad Moeendarbary, Guillaume Charras e Karsten Kruse. "Actin kinetics shapes cortical network structure and mechanics". Science Advances 2, n. 4 (aprile 2016): e1501337. http://dx.doi.org/10.1126/sciadv.1501337.

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The actin cortex of animal cells is the main determinant of cellular mechanics. The continuous turnover of cortical actin filaments enables cells to quickly respond to stimuli. Recent work has shown that most of the cortical actin is generated by only two actin nucleators, the Arp2/3 complex and the formin Diaph1. However, our understanding of their interplay, their kinetics, and the length distribution of the filaments that they nucleate within living cells is poor. Such knowledge is necessary for a thorough comprehension of cellular processes and cell mechanics from basic polymer physics principles. We determined cortical assembly rates in living cells by using single-molecule fluorescence imaging in combination with stochastic simulations. We find that formin-nucleated filaments are, on average, 10 times longer than Arp2/3-nucleated filaments. Although formin-generated filaments represent less than 10% of all actin filaments, mechanical measurements indicate that they are important determinants of cortical elasticity. Tuning the activity of actin nucleators to alter filament length distribution may thus be a mechanism allowing cells to adjust their macroscopic mechanical properties to their physiological needs.

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49

Potts, Jonathan R., Karl Mokross e Mark A. Lewis. "A unifying framework for quantifying the nature of animal interactions". Journal of The Royal Society Interface 11, n. 96 (6 luglio 2014): 20140333. http://dx.doi.org/10.1098/rsif.2014.0333.

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Collective phenomena, whereby agent–agent interactions determine spatial patterns, are ubiquitous in the animal kingdom. On the other hand, movement and space use are also greatly influenced by the interactions between animals and their environment. Despite both types of interaction fundamentally influencing animal behaviour, there has hitherto been no unifying framework for the models proposed in both areas. Here, we construct a general method for inferring population-level spatial patterns from underlying individual movement and interaction processes, a key ingredient in building a statistical mechanics for ecological systems. We show that resource selection functions, as well as several examples of collective motion models, arise as special cases of our framework, thus bringing together resource selection analysis and collective animal behaviour into a single theory. In particular, we focus on combining the various mechanistic models of territorial interactions in the literature with step selection functions, by incorporating interactions into the step selection framework and demonstrating how to derive territorial patterns from the resulting models. We demonstrate the efficacy of our model by application to a population of insectivore birds in the Amazon rainforest.

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Templin, R. J. "The spectrum of animal flight: insects to pterosaurs". Progress in Aerospace Sciences 36, n. 5-6 (agosto 2000): 393–436. http://dx.doi.org/10.1016/s0376-0421(00)00007-5.

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