Hankel operators on Fock spaces

We study Hankel operators on the weighted Fock spaces Fp. The boundedness and compactness of these operators are characterized in terms of BMO and VMO, respectively. Along the way, we also study Berezin transform and harmonic conjugates on the plane. Our results are analogous to Zhu's characterization of bounded and compact Hankel operators on Bergman spaces of the unit disk.

Self-assembly of a model amphiphilic oligopeptide incorporating an arginine headgroup

The self-assembly in aqueous solution of the alanine-rich peptide A12R2 containing twelve alanine residues and two arginine residues has been investigated. This oligomeric peptide was synthesized via NCA-polymerization methods. The surfactant-like peptide is found via FTIR to form antiparallel dimers which aggregate into twisted fibrils, as revealed by cryogenic-transmission electron microscopy. The fibril substructure is probed via detailed X-ray scattering experiments, and are uniquely comprised of twisted tapes only 5 nm wide, set by the width of the antiparallel A12R2 dimers. The packing of the alanine residues leads to distinct “b-sheet” spacings compared to those for amyloid-forming peptides. For this peptide, b-sheet structure coexists with some a-helical content. These ultrafine amyloid fibrils present arginine at high density on their surfaces, and this may lead to applications in nanobiotechnology.

A Riemann-Hilbert problem with a vanishing coefficient and applications to Toeplitz operators

We study the homogeneous Riemann-Hilbert problem with a vanishing scalar-valued continuous coefficient. We characterize non-existence of nontrivial solutions in the case where the coefficient has its values along several rays starting from the origin. As a consequence, some results on injectivity and existence of eigenvalues of Toeplitz operators in Hardy spaces are obtained.

Climate and biome simulations for the past 21,000 years

This paper reports on a set of paleoclimate simulations for 21, 16, 14, 11 and 6 ka (thousands of years ago) carried out with the Community Climate Model, Version 1 (CCM1) of the National Center for Atmospheric Research (NCAR). This climate model uses four interactive components that were not available in our previous simulations with the NCAR CCM0 (COHMAP, 1988Science, 241, 1043–1052; Wright et al., 1993Global Climate Since the Last Glocial Maximum, University of Minnesota Press, MN): soil moisture, snow hydrology, sea-ice, and mixed-layer ocean temperature. The new simulations also use new estimates of ice sheet height and size from ( Peltier 1994, Science, 265, 195–201), and synchronize the astronomically dated orbital forcing with the ice sheet and atmospheric CO2 levels corrected from radiocarbon years to calendar years. The CCM1 simulations agree with the previous simulations in their most general characteristics. The 21 ka climate is cold and dry, in response to the presence of the ice sheets and lowered CO2 levels. The period 14–6 ka has strengthened northern summer monsoons and warm mid-latitude continental interiors in response to orbital changes. Regional differences between the CCM1 and CCM0 simulations can be traced to the effects of either the new interactive model components or the new boundary conditions. CCM1 simulates climate processes more realistically, but has additional degrees of freedom that can allow the model to ‘drift’ toward less realistic solutions in some instances. The CCM1 simulations are expressed in terms of equilibrium vegetation using BIOME 1, and indicate large shifts in biomes. Northern tundra and forest biomes are displaced southward at glacial maximum and subtropical deserts contract in the mid-Holocene when monsoons strengthen. These vegetation changes could, if simulated interactively, introduce additional climate feedbacks. The total area of vegetated land remains nearly constant through time because the exposure of continental shelves with lowered sea level largely compensates for the land covered by the expanded ice sheets.

Tuning self-assembled nanostructures through enzymatic degradation of a peptide amphiphile

The enzymatic cleavage of a peptide amphiphile (PA) is investigated. The self-assembly of the cleaved products is distinct from that of the PA substrate. The PA C16-KKFFVLK is cleaved by α-chymotrypsin at two sites leading to products C16-KKF with FVLK and C16-KKFF with VLK. The PA C16-KKFFVLK forms nanotubes and helical ribbons at room temperature. Both PAs C16-KKF and C16-KKFF corresponding to cleavage products instead self-assemble into 5-6 nm diameter spherical micelles, while peptides FVLK and VLK do not adopt well-defined aggregate structures. The secondary structures of the PAs and peptides are examined by FTIR and circular dichroism spectroscopy and X-ray diffraction. Only C16-KKFFVLK shows substantial β-sheet secondary structure, consistent with its self-assembly into extended aggregates, based on PA layers containing hydrogen-bonded peptide headgroups. This PA also exhibits a thermoreversible transition to twisted tapes on heating.

Toeplitz operators on Dirichlet-Besov spaces

We study Toeplitz operators on the Besov spaces in the case of the open unit disk. We prove that a symbol satisfying a weak Lipschitz type condition induces a bounded Toeplitz operator. Such symbols do not need to be bounded functions or have continuous extensions to the boundary of the open unit disk. We discuss the problem of the existence of nontrivial compact Toeplitz operators, and also consider Fredholm properties and prove an index formula.

Schatten class Toeplitz operators on generalized Fock spaces

In this paper we characterize the Schatten p class membership of Toeplitz operators with positive measure symbols acting on generalized Fock spaces for the full range p>0.

Evidensbaserad munvård för att förebygga ventilatorassocierad pneumoni hos ventilatorbehandlande patienter : en systematisk litteraturstudie

Utgångspunkten för denna litteraturstudie är att ventilatorassocierad pneumoni (VAP) går att förebygga. Syftet med detta arbete var att kartlägga olika evidensbaserade munvårdsmetoder som används av intensivvårdssjuksköterskor för att förebygga VAP hos ventilatorbehandlade patienter. Syftet var också att belysa vilka faktorer som påverkar intensivvårdssjuksköterskans utförande av evidensbaserad munvård till ventilatorbehandlade patienter. Studien utfördes som en systematisk litteraturstudie. Till resultatet användes 16 vetenskapliga artiklar. För att kunna bedöma artiklarnas vetenskapliga kvalitet granskades artiklarna utifrån en modifierad granskningsmall. Samtliga artiklar fick höga kvalitetspoäng, vilket innebär hög vetenskaplig relevans. Resultatet av litteraturstudien visar att i flera av de evidensbaserade munvårdsprotokoll som publicerats den senaste tiden finns några återkommande punkter. Dessa punkter är; bedömning av munhålans status, tandborstning med barntandborste, munsköljmedel och att munnen fuktas med ett intervall av två till sex timmar. Flera faktorer påverkar intensivvårdssjuksköterskans utförande av evidensbaserad munvård. Genom att införa ett evidensbaserat munvårdsprotokoll för ventilatorbehandlade intensivvårdspatienter och ge personalen utbildning i munvård kan incidensen av VAP minska. Resultatet visar också att generellt sett är kunskapsnivån låg hos intensivvårdssjuksköterskor gällande förebyggande åtgärder för att förhindra VAP. Om sjuksköterskan anser att hon/han har tid att utföra munvård blir resultatet av högre kvalitet och hon/han upplever också åtgärden som mindre obehaglig. Detta innebär att försök att förbättra omvårdnaden och därmed minska antalet vårdrelaterade infektioner även är en organisatorisk fråga.

Efeitos do treinamento resistido sobre variáveis relacionadas com a baixa densidade óssea de mulheres menopausadas tratadas com alendronato

A osteoporose é uma doença crônica que atinge o esqueleto humano. OBJETIVO: Verificar os efeitos do treinamento resistido sobre a densidade mineral óssea (DMO), força muscular, equilíbrio e qualidade de vida em mulheres menopausadas em tratamento com alendronato. MÉTODOS: Participaram do estudo 16 voluntárias. Elas foram separadas em dois grupos: que praticaram o treino resistido (n = 9, 49,7 ± 4,2 idade) e que constituíram o grupo controle (n = 7, 53,8 ± 4,4 idade). Os instrumentos de avaliação seguintes foram usados: a absorciometria de dupla energia por raios X -DXA (que mediu a coluna lombar L2-L4, colo do fêmur, triângulo de Wards e trocanter maior), o Osteoporosis Assessment Questionnaire (OPAQ) e um teste de equilíbrio. O treinamento foi periodizado em 12 meses, divididos em seis ciclos com intensidade de 70-90% da carga máxima (10RM). Testes paramétricos (t ou Wilcoxon), para análise intragrupo e (Anova) para intergrupos, foram usados. RESULTADOS: Foram encontradas diferenças significativas favoráveis ao grupo que treinou nos sítios da lombar L2-L4 (6,8%, p = 0,001), colo do fêmur (4,8%, p = 0,005) e trocanter (0,76%, p = 0,005). Além de diferenças significativas também para o equilíbrio corporal (21,4%, p = 0,001), qualidade de vida (9,1%, p = 0,001) e todas as medidas de força como na pressão de pernas 45° (49,3%, p < 0,001). CONCLUSÃO: Os resultados sugerem que a metodologia aplicada ao treino resistido pode ser recomendada a mulheres menopausadas com baixa DMO.

O quadro de escrever como mediador para construção de relações de autonomia no ambiente de sala de aula

O quadro de escrever tem sido nos dias atuais alvo de críticas por parte de muitos professores que o consideram tradicional. Entretanto, alguns professores e pedagogos dentre os quais eu me incluo, consideram que, desde que usado de forma diferenciada, é de suma importância para o ensino e aprendizagem, principalmente na disciplina de Matemática. Essa dissertação versa sobre um estudo feito em uma turma de 7 série do Ensino Fundamental, cujo objetivo foi verificar quais os fatores que dificultam a participação dos alunos nas atividades no quadro de escrever. O estudo mostra que o quadro não é, em sua materialidade, um recurso tradicional. Em sua utilização estão presentes relações de poder que fazem com que os alunos não aceitem participar de suas atividades. As discussões são feitas em torno da necessidade de envolver os alunos e o professor em atividades interativas via quadro de escrever, haja vista que, esse artefato é adequado para a viabilização da comunicação matemática entre professor e alunos e dos alunos entre si.

Metacommunity structuring in stream networks: roles of dispersal mode, distance type, and regional environmental context

Within a metacommunity, both environmental and spatial processes regulate variation in local community structure. The strength of these processes may vary depending on species traits (e.g., dispersal mode) or the characteristics of the regions studied (e.g., spatial extent, environmental heterogeneity). We studied the metacommunity structuring of three groups of stream macroinvertebrates differing in their overland dispersal mode (passive dispersers with aquatic adults; passive dispersers with terrestrial adults; active dispersers with terrestrial adults). We predicted that environmental structuring should be more important for active dispersers, because of their better ability to track environmental variability, and that spatial structuring should be more important for species with aquatic adults, because of stronger dispersal limitation. We sampled a total of 70 stream riffle sites in three drainage basins. Environmental heterogeneity was unrelated to spatial extent among our study regions, allowing us to examine the effects of these two factors on metacommunity structuring. We used partial redundancy analysis and Moran's eigenvector maps based on overland and watercourse distances to study the relative importance of environmental control and spatial structuring. We found that, compared with environmental control, spatial structuring was generally negligible, and it did not vary according to our predictions. In general, active dispersers with terrestrial adults showed stronger environmental control than the two passively dispersing groups, suggesting that the species dispersing actively are better able to track environmental variability. There were no clear differences in the results based on watercourse and overland distances. The variability in metacommunity structuring among basins was not related to the differences in the environmental heterogeneity and spatial extent. Our study emphasized that (1) environmental control is prevailing in stream metacommunities, (2) dispersal mode may have an important effect on metacommunity structuring, and (3) some factors other than spatial extent or environmental heterogeneity contributed to the differences among the basins.

Nutrient enrichment is related to two facets of beta diversity for stream invertebrates across the united states

Beta diversity, the spatial or temporal variability of species composition, is a key concept in community ecology. However, our ability to predict the relative importance of the main drivers of beta diversity (e. g., environmental heterogeneity, dispersal limitation, and environmental productivity) remains limited. Using a comprehensive data set on stream invertebrate assemblages across the continental United States, we found a hump-shaped relationship between beta diversity and within-ecoregion nutrient concentrations. Within-ecoregion compositional dissimilarity matrices were mainly related to environmental distances in most of the 30 ecoregions analyzed, suggesting a stronger role for species-sorting than for spatial processes. The strength of these relationships varied considerably among ecoregions, but they were unrelated to within-ecoregion environmental heterogeneity or spatial extent. Instead, we detected a negative correlation between the strength of species sorting and nutrient concentrations. We suggest that eutrophication is a major mechanism disassembling invertebrate assemblages in streams at a continental scale.

Educação Profissional e Ideologia das Competências: Elementos para uma Crítica da Nova Pedagogia Empresarial sob a Mundialização do Capital

This article aims to address the relationship between work and professional education, specifically the ideology skills and the new pedagogy business under the globalization of capital. Is analyzed at first, the world-historical context, the restructuring of the productive and political capital from the 1970s, and the demand for a new organization of work based on model Toyota. Second, discuss such changes are productive within the Brazilian state and its influence on educational policies geared to work, permeated by the ideology skills as an instrument that seeks to obscure the relationshipcapital. It discusses the emergence of new education business connected to the ideals of human capital. It is the influence of international organizations in Brazil of the United Nations (UN) and the United Nations Organization for Education, Science and Culture (UNESCO), aimed at articulating the education according to the ideological aspect global, verified legislative apparatus in education. Ends up not only to reflect the content of the skills ideology, but it is suggested the redemption value of the denied promise of emancipation human-general.

A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)