1,965 research outputs found
Viewpoint-Specific Scene Representations in Human Parahippocampal Cortex
AbstractThe “parahippocampal place area” (PPA) responds more strongly in functional magnetic resonance imaging (fMRI) to scenes than to faces, objects, or other visual stimuli. We used an event-related fMRI adaptation paradigm to test whether the PPA represents scenes in a viewpoint-specific or viewpoint-invariant manner. The PPA responded just as strongly to viewpoint changes that preserved intrinsic scene geometry as it did to complete scene changes, but less strongly to object changes within the scene. In contrast, lateral occipital cortex responded more strongly to object changes than to spatial changes. These results demonstrate that scene processing in the PPA is viewpoint specific and suggest that the PPA represents the relationship between the observer and the surfaces that define local space
Digging Deeper into Hardin\u27s Pasture: The Complex Institutional Structure of The Tragedy of the Commons
The institutional and ecological structure of Hardin’s “tragedy of the commons” appears deceptively simple: the open-access pasture eventually will be overexploited and degraded unless (i) it is privatized, (ii) the government regulates access and use, or (iii) the users themselves impose a common-property regime to regulate their own access and use. In this paper, we argue that the institutional structure of the “Herder Problem” (as it is known to game theorists) is far more complicated than it is usually portrayed. Specifically, it is not just about the pasture. It is equally about the grass that grows on the pasture and the cattle that consume the grass. Even Elinor Ostrom — a scholar known for embracing complexity — presented an overly simplistic portrayal of Hardin’s open-access pasture when she described its governance system as a null set of institutions. A more careful assessment of the situation, employing Ostrom’s Social-Ecological System (SES) framework, broadens the focus from the res communes omnium pasture to incorporate the res nullius grass that grows upon it and the res private cattle grazing there. The “tragedy” arises from the combination and interactions of the resources and their governing institutions, not just from the absence of property in the pasture. If the grass was not subject to appropriation, the cattle were not privately owned, or if property- and contract-enforcement institutions supporting market exchange were absent, the “tragedy of the commons” probably would not arise regardless of the pasture’s open-access status
Digging Deeper into Hardin\u27s Pasture: The Complex Institutional Structure of The Tragedy of the Commons
The institutional and ecological structure of Hardin’s “tragedy of the commons” appears deceptively simple: the open-access pasture eventually will be overexploited and degraded unless (i) it is privatized, (ii) the government regulates access and use, or (iii) the users themselves impose a common-property regime to regulate their own access and use. In this paper, we argue that the institutional structure of the “Herder Problem” (as it is known to game theorists) is far more complicated than it is usually portrayed. Specifically, it is not just about the pasture. It is equally about the grass that grows on the pasture and the cattle that consume the grass. Even Elinor Ostrom — a scholar known for embracing complexity — presented an overly simplistic portrayal of Hardin’s open-access pasture when she described its governance system as a null set of institutions. A more careful assessment of the situation, employing Ostrom’s Social-Ecological System (SES) framework, broadens the focus from the res communes omnium pasture to incorporate the res nullius grass that grows upon it and the res private cattle grazing there. The “tragedy” arises from the combination and interactions of the resources and their governing institutions, not just from the absence of property in the pasture. If the grass was not subject to appropriation, the cattle were not privately owned, or if property- and contract-enforcement institutions supporting market exchange were absent, the “tragedy of the commons” probably would not arise regardless of the pasture’s open-access status
Governing the invisible commons: Ozone regulation and the Montreal Protocol
The Montreal Protocol is generally credited as a successful example of international cooperation in response to a global environmental problem. As a result, the production and consumption of ozone-depleting substances has declined rapidly, and it is expected that atmospheric ozone concentrations will return to their normal ranges toward the end of this century. This paper applies the social-ecological system framework and common-pool resource theory to explore the congruence between successful resolution of small-scale appropriation problems and ozone regulation, a large-scale pollution problem. The results of our analysis correspond closely to past studies of the Protocol that highlight the importance of attributes such as a limited number of major industrial producers, advances in scientific knowledge, and the availability of technological substitutes. However, in contrast to previous theoretical accounts that focus on one or a few variables, our analysis suggests that its success may have been the result of interactions between a wider range of SES attributes, many of which are associated with successful small-scale environmental governance. Although carefully noting the limitations of drawing conclusions from the analysis of a single case, our analysis reveals the potential for fruitful interplay between common-pool resource theory and large-scale pollution problems
Dense steerable filter CNNs for exploiting rotational symmetry in histology images
Histology images are inherently symmetric under rotation, where each orientation is equally as likely to appear. However, this rotational symmetry is not widely utilised as prior knowledge in modern Convolutional Neural Networks (CNNs), resulting in data hungry models that learn independent features at each orientation. Allowing CNNs to be rotation-equivariant removes the necessity to learn this set of transformations from the data and instead frees up model capacity, allowing more discriminative features to be learned. This reduction in the number of required parameters also reduces the risk of overfitting. In this paper, we propose Dense Steerable Filter CNNs (DSF-CNNs) that use group convolutions with multiple rotated copies of each filter in a densely connected framework. Each filter is defined as a linear combination of steerable basis filters, enabling exact rotation and decreasing the number of trainable parameters compared to standard filters. We also provide the first in-depth comparison of different rotation-equivariant CNNs for histology image analysis and demonstrate the advantage of encoding rotational symmetry into modern architectures. We show that DSF-CNNs achieve state-of-the-art performance, with significantly fewer parameters, when applied to three different tasks in the area of computational pathology: breast tumour classification, colon gland segmentation and multi-tissue nuclear segmentation
Selfish Bin Covering
In this paper, we address the selfish bin covering problem, which is greatly
related both to the bin covering problem, and to the weighted majority game.
What we mainly concern is how much the lack of coordination harms the social
welfare. Besides the standard PoA and PoS, which are based on Nash equilibrium,
we also take into account the strong Nash equilibrium, and several other new
equilibria. For each equilibrium, the corresponding PoA and PoS are given, and
the problems of computing an arbitrary equilibrium, as well as approximating
the best one, are also considered.Comment: 16 page
Missing ecology: integrating ecological perspectives with the social-ecological system framework
Neural tube expression of pituitary adenylate cyclase-activating peptide (PACAP) and receptor: Potential role in patterning and neurogenesis
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