Fast animal pose estimation using deep neural networks

Recent work quantifying postural dynamics has attempted to define the repertoire of behaviors performed by an animal. However, a major drawback to these techniques has been their reliance on dimensionality reduction of images which destroys information about which parts of the body are used in each behavior. To address this issue, we introduce a deep learning-based method for pose estimation, LEAP (LEAP Estimates Animal Pose). LEAP automatically predicts the positions of animal body parts using a deep convolutional neural network with as little as 10 frames of labeled data for training. This framework consists of a graphical interface for interactive labeling of body parts and software for training the network and fast prediction on new data (1 hr to train, 185 Hz predictions). We validate LEAP using videos of freely behaving fruit flies (Drosophila melanogaster) and track 32 distinct points on the body to fully describe the pose of the head, body, wings, and legs with an error rate of <3% of the animal’s body length. We recapitulate a number of reported findings on insect gait dynamics and show LEAP’s applicability as the first step in unsupervised behavioral classification. Finally, we extend the method to more challenging imaging situations (pairs of flies moving on a mesh-like background) and movies from freely moving mice (Mus musculus) where we track the full conformation of the head, body, and limbs.

Swimming Behavior of Selected Species of Archaea

ABSTRACTThe swimming behavior ofBacteriahas been studied extensively, at least for some species likeEscherichia coli. In contrast, almost no data have been published forArchaeaon this topic. In a systematic study we asked how the archaeal model organismsHalobacterium salinarum,Methanococcus voltae,Methanococcus maripaludis,Methanocaldococcus jannaschii,Methanocaldococcus villosus,Pyrococcus furiosus, andSulfolobus acidocaldariusswim and which swimming behavior they exhibit. The twoEuryarchaeota M. jannaschiiandM. villosuswere found to be, by far, the fastest organisms reported up to now, if speed is measured in bodies per second (bps). Their swimming speeds, at close to 400 and 500 bps, are much higher than the speed of the bacteriumE. colior of a very fast animal, like the cheetah, each with a speed of ca. 20 bps. In addition, we observed that two different swimming modes are used by someArchaea. They either swim very rapidly, in a more or less straight line, or they exhibit a slower kind of zigzag swimming behavior if cells are in close proximity to the surface of the glass capillary used for observation. We argue that such a “relocate-and-seek” behavior enables the organisms to stay in their natural habitat.

Spring-Mass Jumping of Underactuated Biped Robots

In many types of fast animal and human locomotion an almost sinusoidal pattern is observed for the ground reaction force; therefore, a simple spring-mass model can approximate the generally observed force pattern. The adjustment of the leg during running, jumping or hopping is addressed using a spring-mass model with a fixed landing angle of attack with the objective of obtaining periodic movement patterns. We found that this self-stabilizing spring-mass model can be applied as a movement criterion for biped joints’ trajectory generation in jumping. To create desired velocity and stride-to-stride length, a synchronization method was applied between biped nonlinear dynamics and spring-mass dynamics as slave and master dynamics, respectively. The results of performed simulations show that while our model lacks the flight phase and impact model for a complete cycle of jumping process, this technique might become of great use in the future’s biped path planning which we call it “dynamic path planning”.

VIII.—A Case of Intersexuality in Bos indicus, with a Theory of the Significance of the Genetic Male Intersex

The Ceylon trotting bull, a small but fast animal, is regarded as a variety of its larger Indian relative, the Zebu, Bos indicus. The case, furnishing the basis of this account, was brought to my notice after the animal had died, so there is no direct evidence regarding its reactions to males and females of the same species. But I am told that although it had been kept for many years in a field with mature cows and bulls it had shown no reaction towards either. Very little is known about the early history of the animal beyond the fact that it was considered to be about seven years old. Nothing is known of its parentage, and as these trotting or racing animals change hands many times in Ceylon, it is impossible to discover whether it had been a twin calf. The animal died of tetanus, and until a fortnight before its death it had been healthy, and, I believe, the winner of many prizes for racing.