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Abstract ObjectivesAn accident during arboreal locomotion can lead to risky falls, but it remains unclear that the extent to which primates, as adept arborealists, change their locomotion in response to the perceived risk of moving on high supports in the tree canopy. By using more stable forms of locomotion on higher substrates, primates might avoid potentially fatal consequences. Materials and MethodsUsing high‐speed cameras, we recorded the quadrupedal locomotion of four wild lemur species—Eulemur rubriventer,Eulemur rufifrons, Hapalemur aureus, and Lemur catta(N = 113 total strides). We quantified the height, diameter, and angular orientation of locomotor supports using remote sensors and tested the influence of support parameters on gait kinematics, specifically predicting that in response to increasing substrate height, lemurs would decrease speed and stride frequency, but increase stride length and the mean number of supporting limbs. ResultsLemurs did not adjust stride frequency on substrates of varying height. Adjustments to speed, stride length, and the mean number of supporting limbs in response to varying height often ran counter to predictions. OnlyE. rubriventerdecreased speed and increased the mean number of supporting limbs on higher substrates. DiscussionResults suggest that quadrupedal walking is a relatively safe form of locomotion for lemurs, requiring subtle changes in gait to increase stability on higher—that is, potentially riskier—substrates. Continued investigation of the impact of height on locomotion will be important to determine how animals assess risk in their environment and how they choose to use this information to move more safely.
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The Sphere of Semiadditive Height 1
Abstract We construct a lift of the $$p$$-complete sphere to the universal height $$1$$ higher semiadditive stable $$\infty $$-category of Carmeli–Schlank–Yanovski, providing a counterexample, at height $$1$$, to their conjecture that the natural functor $$ _n \to \operatorname{\textrm{Sp}}_{T(n)}$$ is an equivalence. We then record some consequences of the construction, including an observation of Schlank that this gives a conceptual proof of a classical theorem of Lee on the stable cohomotopy of Eilenberg–MacLane spaces.
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- Award ID(s):
- 2002029
- PAR ID:
- 10404114
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- International Mathematics Research Notices
- Volume:
- 2024
- Issue:
- 1
- ISSN:
- 1073-7928
- Format(s):
- Medium: X Size: p. 675-697
- Size(s):
- p. 675-697
- Sponsoring Org:
- National Science Foundation
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