742 research outputs found
Trade-offs, condition dependence and stopover site selection by migrating sandpipers
Western sandpipers Calidris mauri on southward migration fly over the Gulf of Alaska to the Strait of Georgia, British Columbia, where they stop for a few days to replenish reserves before continuing. In the Strait, individuals captured on the extensive tidal mudflats of the Fraser estuary (âŒ25000 ha) are significantly heavier (2.71 g, or >10% of lean body mass) than those captured on the small (<100 ha) mudflat of nearby Sidney Island. Previous work has shown that the difference cannot be attributed to seasonal timing, size, age or gender effects, and here we compare predictions made by six hypotheses about a diverse set of data to explain why, partway through a migratory journey of âŒ10000 km, birds have such different body masses at two stopover sites within 40 km of each other. The âtrade-offâ hypothesis â that the large Fraser estuary offers safety from predators, but a lower fattening rate, while the small Sidney Island site is more dangerous, but offers a higher fattening rate â made six successful predictions, all of which were upheld by the data. All other hypotheses failed at least one prediction. We infer that calidrid sandpipers arriving in the Strait of Georgia with little fat remaining (and therefore low body mass) choose to take advantage of the high feeding rate at small sites like Sidney Island because they are less vulnerable to avian predators than are individuals with higher fat reserves, who instead elect to feed at large open sites like the Fraser estuary mudflats
The need for a supply of high quality organic vegetable seeds
Production of high quality organic vegetable seeds encounters several challenges. Research is performed to support seed companies in producing vigorous and healthy organic vegetable seeds. Examples are provided with respect to research on seed vigour, determining critical control points to avoid disease transmission to the seeds, seed treatments with natu-ral compounds, new seed sorting techniques and enhancement of the natural plant defence. It is noticed that the restrictions in EU regulation 2092/91 on organic production are at present blocking the use of promising natural and sustainable components for seed treatments
Improvement of the quality of propagation material for organic farming system
The use of organic propagation material is obligatory according to the current EU regulations for organic production. However, frequently difficulties are en-countered regarding the availability, the costs or the quality. In the Netherlands a national research program aims at developing solutions, needed for improving the production of high quality organic propagation material. The main emphasis in the pro-gram is on the model crops cabbage, onion, wheat and potato. Individual projects within the program include epidemiological studies of seed borne dis-eases to develop disease prevention strategies, meth-ods to improve resistance of seeds and seedlings towards pathogens and methods to control silver scurf in seed potatoes, development of multi-spectral analysis and sorting techniques and methods for analysis and improvement of seed vigour. Active involvement of producers and users of the seeds or seed potatoes ensures that the results will be imple-mented in practice. The program also aims at strengthening the international collaboration, amongst others through involvement in international research projects
Molecular dynamics study of melting of a bcc metal-vanadium II : thermodynamic melting
We present molecular dynamics simulations of the thermodynamic melting
transition of a bcc metal, vanadium using the Finnis-Sinclair potential. We
studied the structural, transport and energetic properties of slabs made of 27
atomic layers with a free surface. We investigated premelting phenomena at the
low-index surfaces of vanadium; V(111), V(001), and V(011), finding that as the
temperature increases, the V(111) surface disorders first, then the V(100)
surface, while the V(110) surface remains stable up to the melting temperature.
Also, as the temperature increases, the disorder spreads from the surface layer
into the bulk, establishing a thin quasiliquid film in the surface region. We
conclude that the hierarchy of premelting phenomena is inversely proportional
to the surface atomic density, being most pronounced for the V(111) surface
which has the lowest surface density
Biharmonic pattern selection
A new model to describe fractal growth is discussed which includes effects
due to long-range coupling between displacements . The model is based on the
biharmonic equation in two-dimensional isotropic defect-free
media as follows from the Kuramoto-Sivashinsky equation for pattern formation
-or, alternatively, from the theory of elasticity. As a difference with
Laplacian and Poisson growth models, in the new model the Laplacian of is
neither zero nor proportional to . Its discretization allows to reproduce a
transition from dense to multibranched growth at a point in which the growth
velocity exhibits a minimum similarly to what occurs within Poisson growth in
planar geometry. Furthermore, in circular geometry the transition point is
estimated for the simplest case from the relation
such that the trajectories become stable at the growing surfaces in a
continuous limit. Hence, within the biharmonic growth model, this transition
depends only on the system size and occurs approximately at a distance far from a central seed particle. The influence of biharmonic patterns on
the growth probability for each lattice site is also analysed.Comment: To appear in Phys. Rev. E. Copies upon request to
[email protected]
Bilingualism alters childrenâs frontal lobe functioning for attentional control
Bilingualism is a typical linguistic experience, yet relatively little is known about its impact on childrenâs cognitive and brain development. Theories of bilingualism suggest that early dualĂą language acquisition can improve childrenâs cognitive abilities, specifically those relying on frontal lobe functioning. While behavioral findings present much conflicting evidence, little is known about its effects on childrenâs frontal lobe development. Using functional nearĂą infrared spectroscopy (fNIRS), the findings suggest that SpanishĂą English bilingual children (nĂÂ =ĂÂ 13, ages 7Ăą 13) had greater activation in left prefrontal cortex during a nonĂą verbal attentional control task relative to ageĂą matched English monolinguals. In contrast, monolinguals (nĂÂ =ĂÂ 14) showed greater right prefrontal activation than bilinguals. The present findings suggest that early bilingualism yields significant changes to the functional organization of childrenâs prefrontal cortex for attentional control and carry implications for understanding how early life experiences impact cognition and brain development.This fNIRS study investigated the impact of bilingual exposure on childrenâs brain organization for attentional control (N = 27, ages 7Ăą 13). During a nonĂą verbal attention task, bilinguals showed greater left frontal lobe activation than monolinguals. Monolinguals showed greater right frontal lobe activation than bilinguals. The findings suggest that bilingualism affects the functionality of childrenâs left prefrontal cortex for attentional control.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/1/desc12377-sup-0001-FigS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/2/desc12377.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/3/desc12377_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/4/desc12377-sup-0003-SupInfo.pd
Bekalking en toevoegen van nutriënten; evaluatie van de effecten op het bosecosysteem; een veldonderzoek naar vegetatie, humus en bodemfauna
Dit rapport doet verslag van een deelonderzoek uit de Evaluatie van effectgerichte maatregelen in multifunctionele bossen 2004-2005 en is gericht op de effecten van de maatregelen bemesting en bekalking in bossen als overbruggingsmaatregel in het ka-der van het Overlevingsplan Bos en Natuur (OBN). In dit rapport worden de effecten besproken van de uitgevoerde maatregelen bekalking en mineralengiften (`bemestingÂż) op de vegetatie, het humusprofiel en de bodemfauna in een veldonderzoek. Bemesting en bekalking leiden beide tot een significante (sterke) toename van het aantal planten-soorten en tot hogere indicatiewaarden voor vocht, zuur en stikstof. Ook is een duide-lijk toename zichtbaar van de verjonging van struiken en Âż alleen bij bemesting - ook van loofbomen. Bekalking en bemesting hebben beide effect op de dikte van de ver-schillende humuslagen. Beide maatregelen leiden dus tot een snellere omzetting van strooisel en tot accumulatie van humus bovenin de Hr-laag. De aard van de humusla-gen is niet veranderd. De maatregelen bemesting en bekalking verschillen sterk van elkaar in het effect dat ze hebben op de bodemfauna. Bemesting laat enkele jaren na uitvoering geen aantoonbare veranderingen zien ten opzichte van de onbemeste situa-tie. Bekalking heeft enkele jaren na uitvoering van de maatregel wĂšl geleid tot aan-toonbare veranderingen in de bodemfauna. Het is mogelijk dat de veranderingen in de bodemfauna die na bekalking zijn opgetreden slechts tijdelijk zijn
Tunneling spectra of submicron BiSrCaCuO intrinsic Josephson junctions: evolution from superconducting gap to pseudogap
Tunneling spectra of near optimally doped, submicron
BiSrCaCuO intrinsic Josephson junctions are presented,
and examined in the region where the superconducting gap evolves into
pseudogap. The spectra are analyzed using a self-energy model, proposed by
Norman {\it et al.}, in which both quasiparticle scattering rate and
pair decay rate are considered. The density of states derived
from the model has the familiar Dynes' form with a simple replacement of
by = ( + )/2. The
parameter obtained from fitting the experimental spectra shows a roughly linear
temperature dependence, which puts a strong constraint on the relation between
and . We discuss and compare the Fermi arc behavior
in the pseudogap phase from the tunneling and angle-resolved photoemission
spectroscopy experiments. Our results indicate an excellent agreement between
the two experiments, which is in favor of the precursor pairing view of the
pseudogap.Comment: 7 pages, 6 figure
Non-western contexts: the invisible half
Like many other disciplines within the broad area of social sciences (e.g., anthropology, gender studies, psychology, sociology, etc.), consumer research is also highly navigated by scholars from Western countries. This, however, does not mean, by any means, that consumer research is devoted to studying Western contexts only. As evident from the ever-increasing number of regional conferences (e.g., Asia-Pacific and Latin American conferences of the Association for Consumer Research) and non-Western students' enrolment in doctoral programs at Western universities, there are many more researchers (from non-Western countries) who are entering the field and enriching it by their colourful contributions. Yet, given the low number of publications on consumer research in non-Western contexts, it seems that our current knowledge in these societies has a long way to go to flourish. More specifically, and in the domain of consumption culture research, this gap is even further widened by the fact that the culture of consumption in such contexts is largely interpreted with reference to the 'grand narratives' of Western scholars (e.g., Foucault, Mafessoli, Bourdieu, Deleuze, Baudrillard, Nietzsche, Durkheim, Derrida, etc.). Therefore, from an ontological perspective, it seems that our existing knowledge about non-Western societies lies heavily on the 'theoretical structures' that are 'constructed' by Western philosophy as a set of ideas, beliefs, and practices (Said, 1978). As Belk (1995) reminds us, consumption culture always existed in all human societies. What makes contemporary societies different from that of our predecessors' is not the fact that consumption culture did not exist in those societies, but that consumption culture has become a prevailing feature in modern society (Slater, 1997; Lury, 1996; Fırat and Venkatesh, 1995; McCracken, 1988). Therefore, the nature and dynamics of consumption culture in each society should be studied not only against the sociocultural, historical, and economic background of a given context (Western or non-Western) but also with reference to the philosophical and epistemological viewpoints that analyse and interpret cultural practices of that society from within that culture. Addressing such issues, this paper discusses some of the key reasons for lack of theory development in the field from non-western contexts. The paper invites scholars in non-Western contexts to introduce the less articulated, and sometime hidden, body of knowledge from their own contexts into the field of marketing in general and consumer research in particular
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