2,901 research outputs found
Exploring modality switching effects in negated sentences: further evidence for grounded representations
Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing “not”). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation
A comparison of radar measurements of atmospheric turbulence intensities by both C sub n sup 2 and spectral width methods
There are two main techniques by which turbulence intensities in the atmosphere can be measured by radars. One is to utilize the absolute backscattered power received by the radar, and use this to deduce C sub n sup 2 (refractivity turbulence structure constant). With appropriate assumptions, this parameter can then be converted to an energy dissipation rate. The second method utilizes the width of the spectrum of the signal received by the radar. Neither of these techniques have been used a great deal, and they have never been properly compared. Thus it was not possible to determine the validity of the assumptions made in applying each technique, nor was it possible to determine the limitations of each method. The first comparisons of the two techniques are presented. Measurements were made with the Adelaide VHF ST radar, and the results of the comparison are discussed
Effects of shade and predation on survival and growth of larval gray treefrogs (hyla versicolor) [abstract]
Abstract only availableAmphibians are experiencing population reductions and species extinctions on a worldwide scale and most biologists agree that loss or degradation of local habitats is the major factor causing declines. As part of the larger Land-use Effects on Amphibian Populations (LEAP) project, we examined some of the effects of timber harvest on the pond environment of larval gray treefrogs (Hyla versicolor). We manipulated shade and predator levels (dragonfly larvae; family Libellulidae) in cattle tanks to test the impact of clear-cutting on the tadpole populations. Survival and size of the metamorphosed frogs differed in response to shade and predation level, but larval period was unaffected. The percent survival in low shade treatments was 71.0% compared to 65.7% for high shade treatments and average mass at metamorphosis was 0.3347 g compared to 0.2960 g. This greater growth was supported by previous research and suggests open canopy ponds have more periphyton which tadpoles utilize as food. In the predator treatments, ponds that had no dragonfly larvae had a greater percent survival than the high predator density ponds (81.2% and 61.8%), however, the average mass of the zero and high predator treatments were similar and smaller than masses in the low and medium treatments. The smaller size at metamorphosis in the high predator treatments can be attributed to reduced feeding activity in order to avoid predators. The higher survival rate from the lack of predation in low treatments resulted in greater tadpole density and less resources available resulting in smaller average mass at metamorphosis. These results imply that clear-cutting does not negatively impact amphibian populations because the tadpoles seemed to thrive from the benefits of open canopy ponds. However, this is the only the first stage in their life history and would probably differ in canopy preference as the frogs mature and begin to use trees for refugia.McNair Scholars Progra
The Potential For UK Portfolio Investors To Finance Sustainable Tropical Forestry
Environmental Economics and Policy, Resource /Energy Economics and Policy,
Topological constraints on spiral wave dynamics in spherical geometries with inhomogeneous excitability
We analyze the way topological constraints and inhomogeneity in the
excitability influence the dynamics of spiral waves on spheres and punctured
spheres of excitable media. We generalize the definition of an index such that
it characterizes not only each spiral but also each hole in punctured,
oriented, compact, two-dimensional differentiable manifolds and show that the
sum of the indices is conserved and zero. We also show that heterogeneity and
geometry are responsible for the formation of various spiral wave attractors,
in particular, pairs of spirals in which one spiral acts as a source and a
second as a sink -- the latter similar to an antispiral. The results provide a
basis for the analysis of the propagation of waves in heterogeneous excitable
media in physical and biological systems.Comment: 5 pages, 6 Figures, major revisions, accepted for publication in
Phys. Rev.
Quantitative trait loci for bone traits segregating independently of those for growth in an F-2 broiler X layer cross
An F broiler-layer cross was phenotyped for 18 skeletal traits at 6, 7 and 9 weeks of age and genotyped with 120 microsatellite markers. Interval mapping identified 61 suggestive and significant QTL on 16 of the 25 linkage groups for 16 traits. Thirty-six additional QTL were identified when the assumption that QTL were fixed in the grandparent lines was relaxed. QTL with large effects on the lengths of the tarsometatarsus, tibia and femur, and the weights of the tibia and femur were identified on GGA4 between 217 and 249 cM. Six QTL for skeletal traits were identified that did not co-locate with genome wide significant QTL for body weight and two body weight QTL did not coincide with skeletal trait QTL. Significant evidence of imprinting was found in ten of the QTL and QTL x sex interactions were identified for 22 traits. Six alleles from the broiler line for weight- and size-related skeletal QTL were positive. Negative alleles for bone quality traits such as tibial dyschondroplasia, leg bowing and tibia twisting generally originated from the layer line suggesting that the allele inherited from the broiler is more protective than the allele originating from the layer
A phenomenological study of occupational engagement in recovery from mental illness
This study aimed to uncover the meaning of occupation for 13 people who self identified as being in recovery from mental illness. Recovery narratives were collected from the participants in a series of open ended conversational interviews that were recorded and transcribed. The interview transcripts were analysed using phenomenological and hermeneutic approaches, with a focus on participants’ descriptions of engagement in everyday occupations. A range of experiences were evident, from complete disengagement to complete absorption in occupations. Participants described significant shifts in their experience of time, space, body and other people while in different modes of occupation and these were captured under the themes of ‘non-doing’, ‘half-doing’, ‘engaged doing’ and ‘absorbed doing’. Each mode had the potential to support recovery by creating opportunities for participants to reconnect with aspects of their being-in-the-world. The findings highlight the dynamics at play in different modes of occupation and suggest that all forms of engagement, including disengagement, can be significant in the recovery process. A greater understanding of the dynamics of occupation for people experiencing mental illness will enable carers and mental health services to more effectively support people in their recovery
Disjoining Potential and Spreading of Thin Liquid Layers in the Diffuse Interface Model Coupled to Hydrodynamics
The hydrodynamic phase field model is applied to the problem of film
spreading on a solid surface. The disjoining potential, responsible for
modification of the fluid properties near a three-phase contact line, is
computed from the solvability conditions of the density field equation with
appropriate boundary conditions imposed on the solid support. The equation
describing the motion of a spreading film are derived in the lubrication
approximation. In the case of quasi-equilibrium spreading, is shown that the
correct sharp-interface limit is obtained, and sample solutions are obtained by
numerical integration. It is further shown that evaporation or condensation may
strongly affect the dynamics near the contact line, and accounting for kinetic
retardation of the interphase transport is necessary to build up a consistent
theory.Comment: 14 pages, 5 figures, to appear in PR
Hydrodynamic theory of de-wetting
A prototypical problem in the study of wetting phenomena is that of a solid
plunging into or being withdrawn from a liquid bath. In the latter, de-wetting
case, a critical speed exists above which a stationary contact line is no
longer sustainable and a liquid film is being deposited on the solid.
Demonstrating this behavior to be a hydrodynamic instability close to the
contact line, we provide the first theoretical explanation of a classical
prediction due to Derjaguin and Levi: instability occurs when the outer, static
meniscus approaches the shape corresponding to a perfectly wetting fluid
Assessment of Gravity Wave Momentum Flux Measurement Capabilities by Meteor Radars Having Different Transmitter Power and Antenna Configurations
Measurement capabilities of five meteor radars are assessed and compared to determine how well radars having different transmitted power and antenna configurations perform in defining mean winds, tidal amplitudes, and gravity wave (GW) momentum fluxes. The five radars include two new-generation meteor radars on Tierra del Fuego, Argentina (53.8 deg S) and on King George Island in the Antarctic (62.1 deg S) and conventional meteor radars at Socorro, New Mexico (34.1 deg N, 106.9 deg W), Bear Lake Observatory, Utah (approx 41.9 deg N, 111.4 deg W), and Yellowknife, Canada (62.5 deg N, 114.3 deg W). Our assessment employs observed meteor distributions for June of 2009, 2010, or 2011 for each radar and a set of seven test motion fields including various superpositions of mean winds, constant diurnal tides, constant and variable semidiurnal tides, and superposed GWs having various amplitudes, scales, periods, directions of propagation, momentum fluxes, and intermittencies. Radars having higher power and/or antenna patterns yielding higher meteor counts at small zenith angles perform well in defining monthly and daily mean winds, tidal amplitudes, and GW momentum fluxes, though with expected larger uncertainties in the daily estimates. Conventional radars having lower power and a single transmitting antenna are able to describe monthly mean winds and tidal amplitudes reasonably well, especially at altitudes having the highest meteor counts. They also provide qualitative estimates of GW momentum fluxes at the altitudes having the highest meteor counts; however, these estimates are subject to uncertainties of approx 20 to 50% and uncertainties rapidly become excessive at higher and lower altitudes. Estimates of all quantities degrade somewhat for more complex motion fields
- …
