1,789 research outputs found
Recovering -invariant metrics on from the equivariant spectrum
We prove an inverse spectral result for -invariant metrics on
based on the so-called asymptotic equivariant spectrum. This is roughly the
spectrum together with large weights of the action on the eigenspaces.
Our result generalizes an inverse spectral result of the first and last named
authors, together with Victor Guillemin, concerning -invariant metrics on
which are invariant under the antipodal map. We use higher order terms in
the asymptotic expansion of a natural spectral measure associated with the
Laplacian and the action.Comment: 16 pages; minor revisions throughout following comments from referee
Hearing Delzant polytopes from the equivariant spectrum
Let M^{2n} be a symplectic toric manifold with a fixed T^n-action and with a
toric K\"ahler metric g. Abreu asked whether the spectrum of the Laplace
operator on determines the moment polytope
of M, and hence by Delzant's theorem determines M up to symplectomorphism. We
report on some progress made on an equivariant version of this conjecture. If
the moment polygon of M^4 is generic and does not have too many pairs of
parallel sides, the so-called equivariant spectrum of M and the spectrum of its
associated real manifold M_R determine its polygon, up to translation and a
small number of choices. For M of arbitrary even dimension and with integer
cohomology class, the equivariant spectrum of the Laplacian acting on sections
of a naturally associated line bundle determines the moment polytope of M.Comment: 23 pages, 9 figures; v2 is published versio
Multiband tunneling in trilayer graphene
The electronic tunneling properties of the two stable forms of trilayer
graphene (TLG), rhombohedral ABC and Bernal ABA, are examined for pn and pnp
junctions as realized by using a single gate (SG) or a double gate (DG). For
the rhombohedral form, due to the chirality of the electrons, the Klein paradox
is found at normal incidence for SG devices while at high energy interband
scattering between additional propagation modes can occur. The electrons in
Bernal ABA TLG can have a monolayer- or bilayer-like character when incident on
a SG device. Using a DG however both propagation modes will couple by breaking
the mirror symmetry of the system which induces intermode scattering and
resonances that depend on the width of the DG pnp junction. For ABC TLG the DG
opens up a band gap which suppresses Klein tunneling. The DG induces also an
unexpected asymmetry in the tunneling angle for single valley electrons
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Conspecific and allospecific larval extracts entice mosquitoes to lay eggs and may be used in attract-and-kill control strategy.
One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with no deterrent effect. Bacillus thuringiensis var. israelensis (Bti) satisfies the latter criterion, but lures for these autocidal gravid traps are sorely needed. We observed that gravid Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus laid significantly more eggs in cups with extracts from 4th-stage larvae (4 L) of the same or different species. No activity was found when 4 L were extracted with hexane, diethyl ether, methanol, or butanol, but activity was observed with dimethyl sulfoxide extracts. Larval extracts contained both oviposition stimulant(s)/attractant(s) and deterrent(s), which partitioned in the water and hexane phases, respectively. Lyophilized larval extracts were active after a month, but activity was reduced by keeping the sample at 4 °C. In the tested range of 0.1 to 1 larvae-equivalent per milliliter, oviposition activity increased in a dose-dependent manner. In field experiments, Ae. aegpti laid significantly more eggs in traps loaded with larval extracts plus Bti than in control traps with water plus Bti
Fingolimod Treatment Modulates PPARγ and CD36 Gene Expression in Women with Multiple Sclerosis
Fingolimod is an oral immunomodulatory drug used in the treatment of multiple sclerosis (MS) that may change lipid metabolism. Peroxisome proliferator-activated receptors (PPAR) are transcription factors that regulate lipoprotein metabolism and immune functions and have been implicated in the pathophysiology of MS. CD36 is a scavenger receptor whose transcription is PPAR regulated. The objective of this study was to evaluate whether fingolimod treatment modifies PPAR and CD36 gene expression as part of its action mechanisms. Serum lipoprotein profiles and PPAR and CD36 gene expression levels in peripheral leukocytes were analysed in 17 female MS patients before and at 6 and 12 months after fingolimod treatment initiation. Clinical data during the follow-up period of treatment were obtained. We found that fingolimod treatment increased HDL-Cholesterol and Apolipoprotein E levels and leukocyte PPARγ and CD36 gene expression. No correlations were found between lipid levels and variations in PPARγ and CD36 gene expression. PPARγ and CD36 variations were significantly correlated during therapy and in patients free of relapse and stable disease. Our results suggest that PPARγ and CD36-mediated processes may contribute to the mechanisms of action of fingolimod in MS. Further studies are required to explore the relation of the PPARγ/CD36 pathway to the clinical efficacy of the drug and its involvement in the pathogenesis of the disease.info:eu-repo/semantics/publishedVersio
Flexão simples : análise comparativa REBAP vs. EC2
O Eurocódigo 2 recomenda a utilização de relações tensões-extensões de cálculo quer para o betão quer para o aço, diferentes das propostas pelo REBAP. Com o objectivo de analisar a influência desta alteração normativa no dimensionamento à flexão simples de secções rectangulares, efectuou-se um estudo comparativo em termos de grandezas adimensionais. Na comunicação descreve-se o estudo efectuado, assim como, as principais conclusões obtidas
Flexão composta : análise comparativa REBAP vs. EC2
No contexto actual nacional, o dimensionamento de estruturas de betão armado tem sido maioritariamente efectuado em conformidade com a norma nacional, o Regulamento de Estruturas de Betão Armado e Pré Esforçado (REBAP). Com a aprovação, no passado recente, do Eurocódigo 2 (EC2) a nível europeu, antevê-se que em breve lhe seja atribuído o estatuto de norma nacional, através da publicação de um texto idêntico. Em termos gerais o EC2, quando comparado com o REBAP, apresenta diferenças consideráveis na forma e no conteúdo que se repercutem no dimensionamento das estruturas de betão armado. Perante este cenário torna se imperioso efectuar estudos comparativos entre as duas normas aos mais diferentes níveis.
O caso particular do dimensionamento à flexão ao nível da secção transversal em elementos estruturais lineares, que tem por base a hipótese de Navier Bernoulli (secções planas antes e após a deformação), recorre a leis tensões extensões de cálculo dos materiais intervenientes: o betão e o aço. As propostas do REBAP e do EC2 para definir estas leis são ligeiramente diferentes. Em trabalhos anteriores demonstrou se que as diferenças obtidas no dimensionamento de secções rectangulares à flexão simples adoptando as duas regulamentações (REBAP e EC2) são marginais.
No presente trabalho pretende se avaliar a mesma diferença, mas desta feita para o caso em que o elemento estrutural se encontra sujeito a flexão composta. Deste modo, o objectivo é o de analisar a influência das diferenças que existem entre o REBAP e o EC2 ao nível dos diagramas tensões extensões de cálculo para os materiais betão e aço, no dimensionamento de secções rectangulares à flexão composta. No presente trabalho descreve se o estudo comparativo efectuado, assim como as principais conclusões obtidas
New biodegradable polylactide material with antimicrobial properties
This study aimed to investigate the bactericidal, fungicidal and non-phytotoxic properties of vapor permeable polylactide films containing five different concentrations (in the range of 0.2–1.0%) of thiabendazole. All films showed bactericidal properties on Staphylococcus aureus and Escherichia coli. Thiabendazole introduced into polylactide affected the antifungal activity of the materials containing 0.8 and 1.0% thiabendazole. The films containing thiabendazole were characterized by increased permeability. The vapor permeability of the film increased with the increase of the biocide content in the composites. The new materials had no a negative effect on the growth and development of monocotyledonous and dicotyledonous plants. It has been shown that the presence of thiabendazole increases the water vapor permeability of polylactide films. The obtained materials are biodegradable and can be used in horticulture and agriculture to protect plants against pathogens. The use of films with biocide properties will reduce the use of plant protection products. This is particularly important due to the need to protect biodiversity in the ecosystem of agricultural soils
A comparative analysis of EU member states and their performance regarding the UN climate change agenda (UN SDG 13 - climate action)
The objective of this research is to assess the performance of the European Union 27 (EU27), its regions and Member States (MSs) towards the Climate Action Sustainable Development Goal (SDG13) from the United Nations 2030 Agenda. To do so, we used the Alkire-Foster (AF) method, developing the Multidimensional Climate Action Index (MCAI) framework. Results show that the EU27 and its regions are not performing satisfactorily. The individual composite scores of the MCAI framework revealed a better individual performance of individual Member States when compared to their group performances. There is a relationship between high level of GDP per capita and satisfactory performance. Southern Europe and Central and Eastern Europe are the regions that perform most poorly against SDG13. Southern Europe, most exposed to Climate Change related losses, is suffering the greatest negative effects related to Climate Change. Central and Eastern Europe perform poorly in promoting social political awareness of Climate Change.info:eu-repo/semantics/publishedVersio
Social policies and emotions in Latin America: A theoretical approach to their analysis
This article aims at making a conceptual analysis of the links between social policies, emotions and World Images. It tries to frame the theoretical and epistemic plots of subjacent assumptions that involve (and activate) State interventions on "the social". The following is the argumentative strategy that has been chosen: firstly, we will account for the links between social policies and the capitalist regime of accumulation; secondly, we will explain the proposed theoretical links between World Image and policies of emotions; thirdly, we will offer some arguments which show the analytical richness of linking social policies and policies of emotions through the concept of World Image; fourthly, as an example, we will frame the massiveness of social policies as a World Image that transmits emotionalities linked to the reproduction of the regime of accumulation. Lastly, as a conclusion, we ask and warn about some components of social policies which make them stand as tools for coloniality
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