Social referencing in the domestic horse

Dogs and cats use human emotional information directed to an unfamiliar situation to guide their behavior, known as social referencing. It is not clear whether other domestic species show similar socio-cognitive abilities in interacting with humans. We investigated whether horses (n = 46) use human emotional information to adjust their behavior to a novel object and whether the behavior of horses differed depending on breed type. Horses were randomly assigned to one of two groups: an experimenter positioned in the middle of a test arena directed gaze and voice towards the novel object with either (a) a positive or (b) a negative emotional expression. The duration of subjects’ position to the experimenter and the object in the arena, frequency of gazing behavior, and physical interactions (with either object or experimenter) were analyzed. Horses in the positive condition spent more time between the experimenter and object compared to horses in the negative condition, indicating less avoidance behavior towards the object. Horses in the negative condition gazed more often towards the object than horses in the positive condition, indicating increased vigilance behavior. Breed types differed in their behavior: thoroughbreds showed less human-directed behavior than warmbloods and ponies. Our results provide evidence that horses use emotional cues from humans to guide their behavior towards novel objects

Conceptual Framework and Physical Implementation of a Systematic Design Strategy for Tissue-Engineered Devices

Tissue-engineered and biologically inspired devices promise to advance medical implants, robotic devices and diagnostic tools. Ideally, biohybrid constructs combine the versatility and fine control of traditional building substrates with dynamic properties of living tissues including sensory modalities and mechanisms of repair, plasticity and self-organization. These dynamic properties also complicate the design process as they arise from, and act upon, structure-function relationships across multiple spatiotemporal scales that need to be recapitulated in the engineered tissue. Biomimetic designs merely copying the structure of native organs and organisms, however, are likely to reflect evolutionary constraints, phenotypic variability and environmental factors rather than rendering optimal engineering solutions. This thesis describes an alternative to biomimetic design, i.e., a systematic approach to tissue engineering based on mechanistic analysis and a focus on functional, not structural, approximation of native and engineered system. As proof of concept, the design, fabrication and evaluation of a tissue-engineered jellyfish medusa with biomimetic propulsion and feeding currents is presented with an emphasis on reasoning and strategy of the iterative design process. A range of experimental and modeling approaches accomplishes mechanistic analysis at multiple scales, control of individual and emergent cell behavior, and quantitative testing of functional performance. The main achievement of this thesis lies in presenting both conceptual framework and physical implementation of a systematic design strategy for muscular pumps and other bioinspired and tissue-engineered applications.</p

The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds' Search Performance in Spatial Rotation Tasks

Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children

Opportunities (and challenges) in dairy cattle cognition research: A key area needed to design future high welfare housing systems

The ability of dairy cattle to adapt to husbandry systems and management routines is crucial for ensuring higher welfare and efficient production. However, this ability can be compromised by our limited knowledge of their cognitive abilities, which may result in suboptimal husbandry and management standards. In this narrative review, we highlight three topics of cattle cognition research that are currently understudied, and yet key to developing future high welfare dairy cattle housing systems: 1) transmission of information from cow to calf, 2) mechanisms to attenuate fear, and 3) cognitive processes involved in the human-cattle relationship. We review the currently available literature on all three topics and highlight promising research areas from an animal husbandry point of view. We conclude that future studies should focus on elucidating what, and how much, calves learn from their dam during prolonged cow-calf contact in dairy cattle systems. Such information could constitute an important part of the discussion of whether to keep cows and calves together for a longer time after calving in the dairy industry. Fear in the cattle group might be lowered by the use of calm companions and future studies could uncover if attenuation of fear might even be induced by conditioning positive experiences of cattle with unrelated stimuli such as odours. Lastly, the human-cattle relationship might benefit from utilising the already established training regimes from other species, for example positive reinforcement training or target training, which may have the potential to decrease risk of injury during handling for both the cow and the handler

Induced drift by a self-propelled swimmer at intermediate Reynolds numbers

Swimming organisms have been proposed to contribute to the mixing of stratified water in the ocean, thereby facilitating the vertical transport of nutrients and dissolved gases. In general, mixing results from increasing the interface available for molecular diffusion between neighboring fluid volumes. At high Reynolds numbers (Re), swimmers generate such interfaces through their turbulent wake structures. At lower Re, however, turbulent mixing becomes ineffective as viscous effects dissipate small-scale fluid motions as heat, and diffusion is not significantly enhanced. In this regime, it appears that the dominant mechanism for mixing by a swimmer is induced drift, i.e., the propagation and stretching of a fluid volume by a moving body's pressure field, which increases the diffusion-enabling interface between the drift volume and surrounding fluid. The ratio of drift volume to body volume is called the “added-mass” coefficient and depends on the shape of the body. Importantly, previous computational analysis suggested that the total drift volume increases at low and intermediate Re, 3 implying that in contrast to turbulent mixing, mixing through induced drift becomes more efficient in viscous conditions. As pointed out by others, the limitation of previous numerical simulations, however, is that the simulated objects were towed through viscous fluid, which is dynamically distinct from a self-propelled swimmer. Using qualitative flow visualization, we here demonstrate the presence of induced drift in self-propelled swimmers operating at intermediate Re (1–100). In these experiments, the spatiotemporal pattern of a fluid volume initially surrounding a juvenile Moon jellyfish ( Aurelia aurita) is visualized using Fluorescein dye (see Fig. 1 ). For details on the experimental methods see supplemental material in Ref. 13

Design standards for engineered tissues

Traditional technologies are required to meet specific, quantitative standards of safety and performance. In tissue engineering, similar standards will have to be developed to enable routine clinical use and customized tissue fabrication. In this essay, we discuss a framework of concepts leading towards general design standards for tissue-engineering, focusing in particular on systematic design strategies, control of cell behavior, physiological scaling, fabrication modes and functional evaluation

Phenotypic Plasticity in Juvenile Jellyfish Medusae Facilitates Effective Animal–Fluid Interaction

Locomotion and feeding in marine animals are intimately linked to the flow dynamics created by specialized body parts. This interaction is of particular importance during ontogeny, when changes in behaviour and scale challenge the organism with shifts in fluid regimes and altered functionality. Previous studies have indicated that Scyphozoan jellyfish ontogeny accommodates the changes in fluid dynamics associated with increasing body dimensions and velocities during development. However, in addition to scale and behaviour that—to a certain degree—underlie the control of the animal, flow dynamics are also dependent on external factors such as temperature. Here, we show phenotypic plasticity in juvenile Aurelia aurita medusae, where morphogenesis is adapted to altered fluid regimes imposed by changes in ambient temperature. In particular, differential proportional growth was found to compensate for temperature-dependent changes in viscous effects, enabling the animal to use adhering water boundary layers as ‘paddles’—and thus economize tissue—at low temperatures, while switching to tissue-dominated propulsion at higher temperatures where the boundary layer thickness is insufficient to serve for paddling. This effect was predicted by a model of animal–fluid interaction and confirmed empirically by flow-field visualization and assays of propulsion efficiency

Invited review: Socio-cognitive capacities of goats and their impact on human-animal interactions

C. N. was supported by a fellowship from the Deutsche Forschungsgemeinschaft (NA 1233/1-1) and a grant from Farm Sanctuary's ‘The Someone Project’

Goats show higher behavioural flexibility than sheep in a spatial detour task

The ability to adapt to changing environments is crucial for survival and has evolved based on socio-ecological factors. Goats and sheep are closely related, with similar social structures, body sizes and domestication levels, but different feeding ecologies, i.e. goats are browsers and sheep are grazers. We investigated whether goats' reliance on more patchily distributed food sources predicted an increased behavioural flexibility compared to sheep. We tested 21 goats and 28 sheep in a spatial A-not-B detour task. Subjects had to navigate around a straight barrier through a gap at its edge. After one, two, three or four of these initial A trials, the gap was moved to the opposite end and subjects performed four B trials. Behaviourally more flexible individuals should move through the new gap faster, while those less behaviourally flexible should show greater perseveration. While both species showed an accuracy reduction following the change of the gap position, goats recovered from this perseveration error from the second B trial onwards, whereas sheep did so only in the fourth B trial, indicating differences in behavioural flexibility between the species. This higher degree of flexibility in goats compared to sheep could be linked to differences in their foraging strategies

Improved estimation of Fokker-Planck equations through optimisation

An improved method for the description of hierarchical complex systems by means of a Fokker-Planck equation is presented. In particular the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm for constraint problems (L-BFGS-B) is used to minimize the distance between the numerical solutions of the Fokker-Planck equation and the empirical probability density functions and thus to estimate properly the drift and diffusion term of the Fokker-Planck equation. The optimisation routine is applied to a time series of velocity measurements obtained from a turbulent helium gas jet in order to demonstrate the benefits and to quantify the improvements of this new optimisation routine