Serfati solutions to the 2D Euler equations on exterior domains

We prove existence and uniqueness of a weak solution to the incompressible 2D Euler equations in the exterior of a bounded smooth obstacle when the initial data is a bounded divergence-free velocity field having bounded scalar curl. This work completes and extends the ideas outlined by P. Serfati for the same problem in the whole-plane case. With non-decaying vorticity, the Biot-Savart integral does not converge, and thus velocity cannot be reconstructed from vorticity in a straightforward way. The key to circumventing this difficulty is the use of the Serfati identity, which is based on the Biot-Savart integral, but holds in more general settings.Comment: 50 page

Existence and analyticity of solutions of the Kuramoto-Sivashinsky equation with singular data

We prove existence of solutions to the Kuramoto-Sivashinsky equation with low-regularity data, in function spaces based on the Wiener algebra and in pseudomeasure spaces. In any spatial dimension, we allow the data to have its antiderivative in the Wiener algebra. In one spatial dimension, we also allow data which is in a pseudomeasure space of negative order. In two spatial dimensions, we also allow data which is in a pseudomeasure space one derivative more regular than in the one-dimensional case. In the course of carrying out the existence arguments, we show a parabolic gain of regularity of the solutions as compared to the data. Subsequently, we show that the solutions are in fact analytic at any positive time in the interval of existence.Comment: 26 page

Brazilian solar saltworks - ancient uses and future possibilities

Coastal solar saltworks of Brazil are exploited for sea salt, which becomes progressively concentrated by evaporation. This study aimed to review the current and new potential uses of these systems, in order to provide more dynamic for this activity. The first evaporation ponds are also used for artisanal fisheries, ensuring the livelihood of many families. All the brine rich in secondary salts (bittern) can be widely used by the chemical industry, while the Brazil shows an incipient production of "flower of salt", a salt with distinct characteristics with higher market value than sodium chloride. On the other hand, the saltponds have a high potential for management and obtaining of large populations of Artemia spp., purifying the brine through the action as biological filter. This microcrustacean occurs naturally in intermediate salinity ponds, being commonly used in aquaculture. Species of microalgae and halobacteria found in the saltworks are employed for extraction of beta-carotene and glycerol, used in an extensive list of products with high commercial value. These ecosystems represent refuge zones for many species of migratory birds, becoming imperative to promote the conservation of these hypersaline wetlands

Weak stability of Lagrangian solutions to the semigeostrophic equations

In [1], Cullen and Feldman proved existence of Lagrangian solutions for the semigeostrophic system in physical variables with initial potential vorticity in $L^p$, $p>1$. Here, we show that a subsequence of the Lagrangian solutions corresponding to a strongly convergent sequence of initial potential vorticities in $L^1$ converges strongly in $L^q$, $q<\infty$, to a Lagrangian solution, in particular extending the existence result of Cullen and Feldman to the case $p=1$. We also present a counterexample for Lagrangian solutions corresponding to a sequence of initial potential vorticities converging in $\mathcal{BM}$. The analytical tools used include techniques from optimal transportation, Ambrosio's results on transport by $BV$ vector fields, and Orlicz spaces. [1] M. Cullen and M. Feldman, {\it Lagrangian solutions of semigeostrophic equations in physical space.} SIAM J. Math. Anal., {\bf 37} (2006), 1371--1395.Comment: 19 page

Tecnologia educacional: mídias e suas linguagens

O trabalho reflete sobre a natureza da integração, através do computador, de linguagens de múltiplos meios de comunicação, como o vídeo, o áudio e as animações, sugerindo a necessidade de se planejar a sinergia entre elas, em produtos de hipermídia educacional, atendendo às características de suas linguagens específicas, estruturadas e já consolidadas pelo uso como veículo de comunicação social, anterior à sua integração pelos computadores. Sugere que o uso adequado dessas linguagens específicas favorece o processamento cognitivo dos alunos, em função do reconhecimento de padrões de visualização, de ritmo de apresentação e de narratividade, que compõem o seu próprio repertório de representações. Descreve o diálogo de linguagens propiciado pela hipermídia como uma marca já integrada ao panorama visual – e, portanto, cultural e cognitivo - da comunicação social do Século XXI, observável tanto na produção de produtos para a Web quanto na composição de elementos que formam as imagens da televisão contemporânea. Apresenta exemplos de pesquisa de uso de vídeos e animações, com suas respectivas linguagens, aplicadas em tecnologia informatizada para uso educacional, presencial e a distância, em produtos desenvolvidos pelo Núcleo de Multimídia e Ensino a Distância da Escola de Engenharia da Universidade Federal do Rio Grande do Sul, equipe à qual pertencem os autores

Promover os direitos das crianças - apostar na construção de melhores políticas públicas para a criança

Comunicação apresentada no 3º Encontro de Conhecimento e Cooperação, INA, Lisboa, 17 de setembro de 201

[evidences For Subclinic Chronic Autoimmune Thyroid Disease In Girls With Turner Syndrome].

Patients with Turner syndrome (TS) frequently exhibit transient, recurrent and asymptomatic variations of TSH and/or thyroid hormones (TH). This work was carried out to evaluate thyroid function and structure in patients with TS who had had such variations in hormone concentrations. Our sample comprised 24 patients, 17 less than 20-years old. Evaluation included serum levels of TSH, free T4, total T3, TPO and Tg autoantibodies, thyroid ultrasound (US) and scintigraphy with 99mTc-pertechnetate. Thirteen patients had abnormal TSH and/or TH levels; 23 exhibited US features compatible with chronic thyroid disorder, particularly thyromegaly (established according to volume expected for stature) and heterogeneous echogenicity. Uptake was normal in 21 cases and tracer distribution was homogeneous in 22. The finding of abnormal hormone concentrations was independent of age, length of time since the first similar finding, thyroid autoantibodies, number of abnormalities at US and abnormal scintigraphic findings. Patients aged more than 20 years had higher frequency of thyroid antibodies and heterogeneous echogenicity, and thyroid volume was significantly correlated to length of time since detection of the first hormone variation, indicating progressive thyroid disease. These results suggest that subclinical thyroid dysfunction in TS is due to chronic autoimmune thyroid disease.51401-

The Dark Sides of Social Policy: From Neoliberalism to Resurgent Right-wing Populism

This Forum Debate explores the confluence of neoliberal, populist, conservative and reactionary influences on contemporary ideologies and practices of social policy, with a focus on the poorer peripheries of global

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic