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Classical Notion (classical + notion)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Dynamic spatial cognition: Components, functions, and modifiability of body schema1

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2006
KAORU SEKIYAMA
Abstract:, There has been substantial progress towards the understanding of the classical notion of "body schema," with recent advances in experimental methodology and techniques. Mental rotation of the hands can be used as a tool to investigate body schema. Research has shown that implicit motor imagery (i.e., mental simulated movements) can be generated based on the body schema, by combining both stored and incoming sensory information. Multimodal stimulation of peripersonal space has also served as an experimental paradigm for the study of body schema. Perception of peripersonal space is based on body-part-centered space coding that is considered as a manifestation of the body schema, its function being to integrate visual, tactile, and proprioceptive information, and perhaps motor plans as well. By combining such experimental paradigms with neuroimaging and neurophysiological techniques, research has converged to show that the parietal association cortex and premotor cortex are important for the body schema. Multimodal perception of body parts and peripersonal space have been also studied in relation to prism adaptation and tool use effects, indicating a clear modifiability of the body schema. Following prolonged adaptation to reversed vision, a reversed hand representation can be added to the body schema like a tool. The stored component of the body schema may not be established well in young children. But once established it may not be deleted even after an arm is amputated, although it may be weakened. All of these findings help to specify properties of the body schema, its components, functions, and modifiabilities. [source]

On the solutions of the Moisil,Théodoresco system

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 12 2008
Juan Bory Reyes
Abstract A structure theorem is proved for the solutions to the Moisil,Théodoresco system in open subsets of ,3. Furthermore, it is shown that the Cauchy transform maps L2(,2, ,0, 2+) isomorphically onto H2(,+3, ,0, 3+), thus proving an elegant generalization to ,2 of the classical notion of an analytic signal on the real line. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Host-specificity and coevolution among pollinating and nonpollinating New World fig wasps

MOLECULAR ECOLOGY, Issue 9 2007
WENDY A. MARUSSICH
Abstract Figs (Ficus spp., Moraceae) and their pollinating wasps (Hymenoptera, Agaonidae, Chalcidoidea) constitute a classic example of an obligate plant-pollinator mutualism, and have become an ideal system for addressing questions on coevolution, speciation, and the maintenance of mutualisms. In addition to pollinating wasps, figs host several types of nonpollinating, parasitic wasps from a diverse array of Chalcid subfamilies with varied natural histories and ecological strategies (e.g. competitors, gallers, and parasitoids). Although a few recent studies have addressed the question of codivergence between specific genera of pollinating and nonpollinating fig wasps, no study has addressed the history of divergence of a fig wasp community comprised of multiple genera of wasps associated with a large number of sympatric fig hosts. Here, we conduct phylogenetic analyses of mitochondrial DNA sequences (COI) using 411 individuals from 69 pollinating and nonpollinating fig wasp species to assess relationships within and between five genera of fig wasps (Pegoscapus, Idarnes, Heterandrium, Aepocerus, Physothorax) associated with 17 species of New World Urostigma figs from section Americana. We show that host-switching and multiple wasp species per host are ubiquitous across Neotropical nonpollinating wasp genera. In spite of these findings, cophylogenetic analyses (treemap 1.0, treemap 2.02,, and parafit) reveal evidence of codivergence among fig wasps from different ecological guilds. Our findings further challenge the classical notion of strict-sense coevolution between figs and their associated wasps, and mirror conclusions from detailed molecular studies of other mutualisms that have revealed common patterns of diffuse coevolution and asymmetric specialization among the participants. [source]

Resolving the biodiversity paradox

ECOLOGY LETTERS, Issue 8 2007
James S. Clark
Abstract The paradox of biodiversity involves three elements, (i) mathematical models predict that species must differ in specific ways in order to coexist as stable ecological communities, (ii) such differences are difficult to identify, yet (iii) there is widespread evidence of stability in natural communities. Debate has centred on two views. The first explanation involves tradeoffs along a small number of axes, including ,colonization-competition', resource competition (light, water, nitrogen for plants, including the ,successional niche'), and life history (e.g. high-light growth vs. low-light survival and few large vs. many small seeds). The second view is neutrality, which assumes that species differences do not contribute to dynamics. Clark et al. (2004) presented a third explanation, that coexistence is inherently high dimensional, but still depends on species differences. We demonstrate that neither traditional low-dimensional tradeoffs nor neutrality can resolve the biodiversity paradox, in part by showing that they do not properly interpret stochasticity in statistical and in theoretical models. Unless sample sizes are small, traditional data modelling assures that species will appear different in a few dimensions, but those differences will rarely predict coexistence when parameter estimates are plugged into theoretical models. Contrary to standard interpretations, neutral models do not imply functional equivalence, but rather subsume species differences in stochastic terms. New hierarchical modelling techniques for inference reveal high-dimensional differences among species that can be quantified with random individual and temporal effects (RITES), i.e. process-level variation that results from many causes. We show that this variation is large, and that it stands in for species differences along unobserved dimensions that do contribute to diversity. High dimensional coexistence contrasts with the classical notions of tradeoffs along a few axes, which are often not found in data, and with ,neutral models', which mask, rather than eliminate, tradeoffs in stochastic terms. This mechanism can explain coexistence of species that would not occur with simple, low-dimensional tradeoff scenarios. [source]

Indigeneity across borders: Hemispheric migrations and cosmopolitan encounters

AMERICAN ETHNOLOGIST, Issue 1 2010
ROBIN MARIA DELUGAN
ABSTRACT The increasing migration of indigenous people from Latin America to the United States signals a new horizon for the study of indigeneity,complexly understood as subjectivities, knowledge, and practices of the earliest human inhabitants of a particular place and including legal and racial identities that refer to these people. Focusing on indigenous migration to San Francisco, California, I explore how government, service providers, and community organizations respond to the arrival of new ethnic groups while also contributing to an expanding Urban Indian collective identity. In addition to reviewing such governmental practices as the creation of new census categories and related responses to indigenous ethnic diversity, I illustrate how some members of a diverse Urban Indian population unite through participation in rituals such as the Maya Waqxaqi' B'atz' (Day of Human Perfection), transplanted to San Francisco from Guatemala. The rituals recall homelands near and far in a broader social imagination about being and belonging in the world. The social imagination, borne in part through migration and diaspora, acknowledges the local and the particular in a framework of shared values about what it means to be human. I analyze this meaning making as cosmopolitanism in practice. By merging indigeneity and cosmopolitanism, I join other scholars who strive to decenter classical notions of cosmopolitan "worldliness," drawing attention to alternative sources of beneficent sociality and for cultivating humanity. [source]