1,064 research outputs found
Integrating across memory episodes: Developmental trends
Memory enables us to use information from our past experiences to guide new behaviours, calling for the need to integrate or form inference across multiple distinct episodic experiences. Here, we compared children (aged 9-10 years), adolescents (aged 12-13 years), and young adults (aged 19-25 years) on their ability to form integration across overlapping associations in memory. Participants first encoded a set of overlapping, direct AB- and BC-associations (object-face and face-object pairs) as well as non-overlapping, unique DE-associations. They were then tested on these associations and inferential AC-associations. The experiment consisted of four such encoding/retrieval cycles, each consisting of different stimuli set. For accuracy on both unique and inferential associations, young adults were found to outperform teenagers, who in turn outperformed children. However, children were particularly slower than teenagers and young adults in making judgements during inferential than during unique associations. This suggests that children may rely more on making inferences during retrieval, by first retrieving the direct associations, followed by making the inferential judgement. Furthermore, young adults showed a higher correlation between accuracy in direct (AB, BC) and inferential AC-associations than children. This suggests that, young adults relied closely on AB- and BC-associations for making AC decisions, potentially by forming integrated ABC-triplets during encoding or retrieval. Taken together, our findings suggest that there may be an age-related shift in how information is integrated across experienced episodes, namely from relying on making inferences at retrieval during middle childhood to forming integrated representations at different memory processing stages in adulthood
Dynamics and Pattern Formation in Large Systems of Spatially-Coupled Oscillators with Finite Response Times
We consider systems of many spatially distributed phase oscillators that
interact with their neighbors. Each oscillator is allowed to have a different
natural frequency, as well as a different response time to the signals it
receives from other oscillators in its neighborhood. Using the ansatz of Ott
and Antonsen (Ref. \cite{OA1}) and adopting a strategy similar to that employed
in the recent work of Laing (Ref. \cite{Laing2}), we reduce the microscopic
dynamics of these systems to a macroscopic partial-differential-equation
description. Using this macroscopic formulation, we numerically find that
finite oscillator response time leads to interesting spatio-temporal dynamical
behaviors including propagating fronts, spots, target patterns, chimerae,
spiral waves, etc., and we study interactions and evolutionary behaviors of
these spatio-temporal patterns
Relationships between estuarine habitats and coastal fisheries in Queensland, Australia
Worldwide, estuaries have been recognized as critical habitats for nearshore fish productivity through their capacity as nursery grounds and nutrient sources. The purpose of this study was to demonstrate the importance of the habitat characteristics of estuaries to commercial fish catch in Queensland, Australia, with particular focus on the role of mangrove, saltmarsh, and seagrass habitats, and their connectivity. Traditionally, such analyses have taken the single-habitat approach, i.e., assessing the value of individual habitat types. Combined occurrence of these habitats and their collective accessibility may better explain the importance of estuaries to nekton. A literature review identifies the role of estuaries as integrated systems for fisheries. Our study provides strong supportive evidence for habitat-based, not species-based, management of fisheries in Queensland. Outcomes from preliminary analyses in Queensland suggest that collective spatial characteristics of estuarine habitats such as size and structural connectivity significantly correlate with fish catch data with r(2) values > 0.7 for 17 commercial species groups. The catch of one quarter of the investigated species was best explained by the presence of mud- and sandflats. An exploration of currently available data on habitat distribution and fisheries catch shows the need to scrutinise their spatial and temporal accuracy, and how best to use them to understand estuarine-fisheries links. We conclude that structural connectivity of estuarine habitats is fundamental to the size of fish stocks and to optimizing the sustainable yield for commercial and recreational fishers
Natural or Artificial? Habitat-Use by the Bull Shark, Carcharhinus leucas
BACKGROUND: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN ‘Near-threatened’ species - one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species. METHODOLOGY/FINDINGS: We used longline surveys and long-term passive acoustic tracking of neonate and juvenile bull sharks to determine the ontogenetic value of natural and artificial habitats to bull sharks associated with the Nerang River and adjoining canals on the Gold Coast, Australia. Long-term movements of tagged sharks suggested a preference for the natural river over artificial habitat (canals). Neonates and juveniles spent the majority of their time in the upper tidal reaches of the Nerang River and undertook excursions into adjoining canals. Larger bull sharks ranged further and frequented the canals closer to the river mouth. CONCLUSIONS/SIGNIFICANCE: Our work suggests with increased destruction of natural habitats, artificial coastal habitat may become increasingly important to large juvenile bull sharks with associated risk of attack on humans. In this system, neonate and juvenile bull sharks utilised the natural and artificial habitats, but the latter was not the preferred habitat of neonates. The upper reaches of tidal rivers, often under significant modification pressure, serve as nursery sites for neonates. Analogous studies are needed in similar systems elsewhere to assess the spatial and temporal generality of this research
DeformerNet: Learning Bimanual Manipulation of 3D Deformable Objects
Applications in fields ranging from home care to warehouse fulfillment to
surgical assistance require robots to reliably manipulate the shape of 3D
deformable objects. Analytic models of elastic, 3D deformable objects require
numerous parameters to describe the potentially infinite degrees of freedom
present in determining the object's shape. Previous attempts at performing 3D
shape control rely on hand-crafted features to represent the object shape and
require training of object-specific control models. We overcome these issues
through the use of our novel DeformerNet neural network architecture, which
operates on a partial-view point cloud of the manipulated object and a point
cloud of the goal shape to learn a low-dimensional representation of the object
shape. This shape embedding enables the robot to learn a visual servo
controller that computes the desired robot end-effector action to iteratively
deform the object toward the target shape. We demonstrate both in simulation
and on a physical robot that DeformerNet reliably generalizes to object shapes
and material stiffness not seen during training. Crucially, using DeformerNet,
the robot successfully accomplishes three surgical sub-tasks: retraction
(moving tissue aside to access a site underneath it), tissue wrapping (a
sub-task in procedures like aortic stent placements), and connecting two
tubular pieces of tissue (a sub-task in anastomosis).Comment: Submitted to IEEE Transactions on Robotics (T-RO). 18 pages, 25
figures. arXiv admin note: substantial text overlap with arXiv:2110.0468
- …