169 research outputs found

    On the restriction of the Fourier transform to polynomial curves

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    We prove a Fourier restriction theorem on curves parametrised by the mapping P(t) = (P1(t),..., Pn(t)), where each of the P1,..., Pn is a real-valued polynomial and t belongs to an interval on which each of the P1,..., Pn "resembles" a monomial

    Fourier restriction to polynomial curves I: a geometric inequality

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    We prove a Fourier restriction result for general polynomial curves in Rd. Measuring the Fourier restriction with respect to the affine arclength measure of the curve, we obtain a universal estimate for the class of all polynomial curves of bounded degree. Our method relies on establishing a geometric inequality for general polynomial curves which is of interest in its own right. Applications of this geometric inequality to other problems in euclidean harmonic analysis have recently been established

    Rationals, periodicity and chaos: A Pythagorean view and a conjecture into socio-spatial dynamics

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    Deep in the fascinating world of numbers there still might lurk useful insights into the processes of the socio-spatial world. A rich section of the world of numbers is of course Number Theory and its pantheon of findings, a part of which is revisited here

    Stimulus, expectations, desires and response strategies:The building blocks of nonlinear interaction dynamics

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    Stimulus and response functions, as the fundamental blocks of nonlinear interaction dynamics, are analyzed and modeled here, under a variety of interaction strategies. The backbone of the suggested model is a simple iterative dynamical formulation: the magnitude of a signal sent at present is a function of a relevant signal sent—as well as of a signal received—in the past; in turn, a signal received at present is a function of a signal received—as well as of a signal sent—in the past; namely,Ss(n+1)=fs{Ss(n)Sr(n)}    and   Sr(n+1)=fr{Sr(n)Ss(n)} where Ss/r is the size of a signal sent/received, and n is a point in time

    Static and relative fluctuating pressure results of a wind tunnel investigation of subsonic and supersonic separated flow about cylindrical and Saturn 5 model protuberances

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    Shadowgraph, pressure, and flow visualization experiments in blowdown wind tunnel on series of cylindrical and scale model Saturn 5 protuberance

    The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications

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    Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas

    Issues of ideology in English language education worldwide: an overview

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    The relatively limited consideration of ideology in mainstream theory and research of teaching the English language to speakers of other languages has arguably prevented the problematization of many taken-for-granted perceptions and practices of the field. In this article I attempt to bring part of this marginalized body of scholarship on issues of ideology in the area of English language teaching (ELT) to highlight its potential insights for the field. The article sets out from a view of ideology as the most fundamental beliefs in any social practice, which may provide a less-formidable conception of the term and lessen the divergence among the minority of ELT researchers and professionals that do concern themselves with ideology. Then, after a brief sketch of the notion of ideology of language (education), I present an overview of aspects of this marginal but vibrant stream of thought on issues of ideology in ELT worldwide. Overall, the discussion is aimed to act as a call for the further understanding and embracement of sociopolitically-sensitive and ideologically-informed approaches to ELT theory, research, and practice
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