9,934 research outputs found
Concerning periodic points in mappings of continua
In this paper we present some conditions which are sufficient for a mapping to have periodic points. © 1988 American Mathematical Society
Teoría tradicional de los continuos que surgen en los límites inversos con funciones multivaluadas
In the years since their introduction in 2004, almost 100 articles and books have been written on the subject of inverse limits with set-valued functions. Although such inverse limits do not always produce continua, much traditional continuum theory arises in investigations of these interesting objects. In this survey article we discuss several tradtional topics that have arisen in research into the subject.En los años desde su introducción en 2004, casi 100 artículos y libros han sido escritos sobre límites inversos con funciones multivaluadas. Aunque tales límites inversos no siempre producen continuos, muchos aspectosde la teoría clásica de los continuos aparecen en las investigaciones de estos objetos interesantes. En este artículo discutimos varios de los temas tradicionales que han surgido en el estudio de este tema
Traditional continuum theory arising in inverse limits with set-valued functions
In the years since their introduction in 2004, almost 100 articles and books have been written on the subject of inverse limits with set-valued functions. Although such inverse limits do not always produce continua, much traditional continuum theory arises in investigations of these interesting objects. In this survey article we discuss several tradtional topics that have arisen in research into the subject
Internal Friction and Vulnerability of Mixed Alkali Glasses
Based on a hopping model we show how the mixed alkali effect in glasses can
be understood if only a small fraction c_V ofthe available sites for the mobile
ions is vacant. In particular, we reproduce the peculiar behavior of the
internal friction and the steep fall (''vulnerability'') of the mobility of the
majority ion upon small replacements by the minority ion. The single and mixed
alkali internal friction peaks are caused by ion-vacancy and ion-ion exchange
processes. If c_V is small, they can become comparable in height even at small
mixing ratios. The large vulnerability is explained by a trapping of vacancies
induced by the minority ions. Reasonable choices of model parameters yield
typical behaviors found in experiments.Comment: 4 pages, 4 figure
Using nestedness and species-accumulation analyses to strengthen a conservation plan for littoral forest birds in south-eastern Madagascar
The littoral forests of south-eastern Madagascar are among the most threatened ecosystems on the island. A conservation plan has been developed for the region due to a proposed mining venture. Here, we provide a novel methodology to assess if the planned conservation measures would effectively conserve the bird diversity inhabiting these forests. Bird community composition within 30 littoral forest fragments was quantified with each fragment characterized by measures of fragment area, isolation, and internal habitat complexity. A nestedness and cumulative species–area analysis was conducted to ascertain the contribution of forest fragments of different sizes in capturing the overall bird species richness. Datasets representing the overall and forest-dependent bird assemblages were found to be significantly nested. The pattern of nestedness appeared to be driven by fragment size. However, cumulative species–area analyses showed that the assemblages were imperfectly nested with ten species displaying idiosyncratic distribution patterns. When a modest conservation target was set (the occurrence of a bird species in three or more fragments), the proposed conservation plan would only protect approximately half the species found in the littoral forests. We show that protecting an additional four large patches would mean that the proportion of forest-birds captured in three or more patches would increase to 70%
Hungry for change: the Sydney Food Fairness Alliance
The Sydney Food Fairness Alliance is one of a growing number of nascent food movements in Australia to have emerged out of concern for the country’s food future, as well as the deleterious effect the present food system is having on its citizens’ health and the continent’s fragile environment. The Alliance’s structure and activities clearly position it as a new social movement (NSM) engaged in collective action on a specific issue, in this instance, food security/justice, and operating outside the political sphere while aiming to influence and affect societal change. Food security as a human right lies at the heart of the Alliance’s philosophy, and equitable, sustainable food policies for New South Wales are a core focus of its advocacy work. The authors argue that the Alliance is a distinctive food movement in that it positions itself as an \u27umbrella\u27 organization representing a wide range of stakeholders in the food system. This chapter reflects on the values, achievements, issues of concern, strengths and weaknesses, and future of the Sydney Food Fairness Alliance.
This resource is Chapter 8 in \u27Food Security in Australia: Challenges and Prospects for the Future\u27 published by Springer in 2013
Mesoporous stilbene-based lanthanide metal organic frameworks: synthesis, photoluminescence and radioluminescence characteristics
Mesoporous non-interpenetrating stilbene-based lanthanide metal organic frameworks exhibits photo and radioluminescence behavior.</p
Matrix controlled channel diffusion of sodium in amorphous silica
To find the origin of the diffusion channels observed in sodium-silicate
glasses, we have performed classical molecular dynamics simulations of
NaO--4SiO during which the mass of the Si and O atoms has been
multiplied by a tuning coefficient. We observe that the channels disappear and
that the diffusive motion of the sodium atoms vanishes if this coefficient is
larger than a threshold value. Above this threshold the vibrational states of
the matrix are not compatible with those of the sodium ions. We interpret hence
the decrease of the diffusion by the absence of resonance conditions.Comment: 5 pages, 4 figure
The pd <--> pi+ t reaction around the Delta resonance
The pd pi+ t process has been calculated in the energy region around the
Delta-resonance with elementary production/absorption mechanisms involving one
and two nucleons. The isobar degrees of freedom have been explicitly included
in the two-nucleon mechanism via pi-- and rho-exchange diagrams. No free
parameters have been employed in the analysis since all the parameters have
been fixed in previous studies on the simpler pp pi+ d process. The
treatment of the few-nucleon dynamics entailed a Faddeev-based calculation of
the reaction, with continuum calculations for the initial p-d state and
accurate solutions of the three-nucleon bound-state equation. The integral
cross-section was found to be quite sensitive to the NN interaction employed
while the angular dependence showed less sensitivity. Approximately a 4% effect
was found for the one-body mechanism, for the three-nucleon dynamics in the p-d
channel, and for the inclusion of a large, possibly converged, number of
three-body partial states, indicating that these different aspects are of
comparable importance in the calculation of the spin-averaged observables.Comment: 40 Pages, RevTex, plus 5 PostScript figure
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