271 research outputs found
On the curvature of vortex moduli spaces
We use algebraic topology to investigate local curvature properties of the
moduli spaces of gauged vortices on a closed Riemann surface. After computing
the homotopy type of the universal cover of the moduli spaces (which are
symmetric powers of the surface), we prove that, for genus g>1, the holomorphic
bisectional curvature of the vortex metrics cannot always be nonnegative in the
multivortex case, and this property extends to all Kaehler metrics on certain
symmetric powers. Our result rules out an established and natural conjecture on
the geometry of the moduli spaces.Comment: 25 pages; final version, to appear in Math.
EstratĂ©gias de coping utilizadas por familiares de indivĂduos em tratamento hemodialĂtico
This descriptive, qualitative study aims to identify the coping strategies used most by the family members of patients with chronic kidney disease receiving hemodialysis. The data were collected through interviews, with the Coping Strategies Inventory questionnaire administered to ten family members, and were submitted to descriptive statistics and to thematic content analysis. The strategy used most was escape-avoidance, demonstrating that the family members prefer not to face the situation. The second most-used strategy was social support, ratified by the fact that they stated that they talk with other persons and professionals, seeking information about the problem, and because they accept the support received positively. The third was problem resolution, represented by the attitude of accepting responsibility for the care, either through strong affective bonds or through a feeling of responsibility established prior to the disease. The families use coping strategies of different intensities, while, nevertheless, indicating involvement and major participation in the care for the patient.Estudio cualitativo, que tratĂł de identificar las estrategias de afrontamiento empleadas por las familias de los pacientes con insuficiencia renal crĂłnica en hemodiĂĄlisis. Se aplicĂł el Inventario de Estrategias de Afrontamiento y una questiĂłn abierta con diez familiares. Los datos cuantitativos fueron sometidos a procedimientos estatĂsticos y anĂĄlisis de contenido cualitativo. La estrategia de mayor utilizaciĂłn fue el escape y evitaciĂłn (oito), lo que demuestra que los miembros de las familisa preferĂan no tener que enfrentar esta situaciĂłn. La siguiente estrategia fue utilizada mĂĄs apoyo social, ya hablĂ© con otras personas y profesionales que buscan informaciĂłn sobre el problema, y aceptar el apoyo positivo recibido. A terceira foi resolução de problemas, representada pela atitude em assumir o cuidado, seja pelo forte vĂnculo afetivo ou pelo sentimento de responsabilidade jĂĄ estabelecido antes da doença. Familias de las estrategias de afrontamiento empleadas con diferentes intensidades, pero mostrando una gran implicaciĂłn y la participaciĂłn en el cuidado del paciente crĂłnico.Estudo descritivo, de natureza quali-quantitativa, que objetivou identificar as estratĂ©gias de enfrentamento mais utilizadas por familiares de pacientes com doença renal crĂŽnica em hemodiĂĄlise. Os dados foram coletados por meio de entrevista, com aplicação do InventĂĄrio de EstratĂ©gias de Coping a dez familiares, e submetidos Ă estatĂstica descritiva e Ă anĂĄlise de conteĂșdo temĂĄtica. A estratĂ©gia mais utilizada foi fuga e esquiva, demonstrando que os familiares preferiam nĂŁo enfrentar a situação. A segunda estratĂ©gia mais usada foi suporte social, ratificada ao afirmarem que conversaram com outras pessoas e profissionais buscando informaçÔes sobre o problema, e por aceitarem positivamente o apoio recebido. A terceira foi resolução de problemas, representada pela atitude em assumir o cuidado, seja pelo forte vĂnculo afetivo ou pelo sentimento de responsabilidade jĂĄ estabelecido antes da doença. As famĂlias empregaram estratĂ©gias de enfrentamento com intensidades diferentes, porĂ©m indicando envolvimento e grande participação no cuidado ao doente.Universidade Federal de SĂŁo Paulo (UNIFESP)aff2Universidade Estadual de MaringĂĄUEMUNIFESPSciEL
A Philosophically Plausible Formal Interpretation of Intuitionistic Logic
This study addresses the mediating role of settlement patterns in the relationship between urbanization and start-up activity. Places do not operate in a vacuum and to understand the effect of 'own' density on start-up patterns, we need to account for the urban spillovers or borrowed size that they may experience from other places nearby. The results can explain the empirical ambiguity in the relationship between urbanization and start-up patterns: the relationship between urbanization and start-up rates becomes more similar between countries when controlling for country-specific settlement patterns by including a spatially lagged urbanization variable and variables measuring the distance to urban centers. Accounting for the relative location of places and relevant sorting effects, we find that 'own' density has a consistently negative effect on start-up activity. Yet, access to other places has a generally positive effect. This implies that nearby regions profit from the advantages offered by urban environments without having to deal with the costs involved
The N-P-K soil nutrient balance of portuguese cropland in the 1950s: the transition from organic to chemical fertilization
Agricultural nutrient balances have been receiving increasing attention in both historical and
nutrient management research. The main objectives of this study were to further develop balance
methodologies and to carry out a comprehensive assessment of the functioning and nutrient cycling
of 1950s agroecosystems in Portugal. Additionally, the main implications for the history of agriculture
in Portugal were discussed from the standpoint of soil fertility. We used a mass balance approach
that comprises virtually all nitrogen (N), phosphorus (P) and potassium (K) inputs and outputs from
cropland topsoil for average conditions in the period 1951â56. We found a consistent deficit in N, both
for nationwide (â2.1 kg.haâ1.yrâ1) and arable crops (â1.6 kg.haâ1.yrâ1) estimates, that was rectified
in the turn to the 1960 decade. P and K were, in contrast, accumulating in the soil (4.2â4.6 kg.haâ1.yrâ1
and 1.0â3.0 kg.haâ1.yrâ1, respectively). We observed that the 1950s is the very moment of inflection
from an agriculture fertilized predominantly through reused N in biomass (livestock excretions plus
marine, plant and human waste sources) to one where chemical fertilizers prevailed. It is suggested that
N deficiency played an important role in this transitioninfo:eu-repo/semantics/publishedVersio
Human oral isolate Lactobacillus fermentum AGR1487 induces a proinflammatory response in germ-free rat colons
Lactobacilli are thought to be beneficial for human health, with lactobacilli-associated infections being confined to immune-compromised individuals. However, Lactobacillus fermentum AGR1487 negatively affects barrier integrity in vitro so we hypothesized that it caused a pro-inflammatory response in the host. We compared germ-free rats inoculated with AGR1487 to those inoculated with another L. fermentum strain, AGR1485, which does not affect in vitro barrier integrity. We showed that rats inoculated with AGR1487 had more inflammatory cells in their colon, higher levels of inflammatory biomarkers, and increased colonic gene expression of pro-inflammatory pathways. In addition, our in vitro studies showed that AGR1487 had a greater capacity to activate TLR signaling and induce pro-inflammatory cytokines in immune cells. This study indicates the potential of strains of the same species to differentially elicit inflammatory responses in the host and highlights the importance of strain characterization in probiotic approaches to treat inflammatory disorders
Voltage-gated Na<sup>+</sup> channel activity increases colon cancertranscriptional activity and invasion via persistent MAPK signaling
© 2015 Macmillan Publishers Limited. All rights reserved. Functional expression of voltage-gated Na+ channels (VGSCs) has been demonstrated in multiple cancer cell types where channel activity induces invasive activity. The signaling mechanisms by which VGSCs promote oncogenesis remain poorly understood. We explored the signal transduction process critical to VGSC-mediated invasion on the basis of reports linking channel activity to gene expression changes in excitable cells. Coincidentally, many genes transcriptionally regulated by the SCN5A isoform in colon cancer have an over-representation of cis-acting sites for transcription factors phosphorylated by ERK1/2 MAPK. We hypothesized that VGSC activity promotes MAPK activation to induce transcriptional changes in invasion-related genes. Using pharmacological inhibitors/activators and siRNA-mediated gene knockdowns, we correlated channel activity with Rap1-dependent persistent MAPK activation in the SW620 human colon cancer cell line. We further demonstrated that VGSC activity induces downstream changes in invasion-related gene expression via a PKA/ERK/c-JUN/ELK-1/ETS-1 transcriptional pathway. This is the first study illustrating a molecular mechanism linking functional activity of VGSCs to transcriptional activation of invasion-related genes
The type VII secretion system of <i>Staphylococcus aureus</i> secretes a nuclease toxin that targets competitor bacteria
The type VII protein secretion system (T7SS) plays a critical role in the virulence of human pathogens including Mycobacterium tuberculosis and Staphylococcus aureus. Here we report that the S. aureus T7SS secretes a large nuclease toxin, EsaD. The toxic activity of EsaD is neutralised during its biosynthesis through complex formation with an antitoxin, EsaG, which binds to its C-terminal nuclease domain. The secretion of EsaD is dependent upon a further accessory protein, EsaE, that does not interact with the nuclease domain, but instead binds to the EsaD N-terminal region. EsaE has a dual cytoplasmic/membrane localization and membrane-bound EsaE interacts with the T7SS secretion ATPase, EssC, implicating EsaE in targeting the EsaDG complex to the secretion apparatus. EsaD and EsaE are co-secreted whereas EsaG is found only in the cytoplasm and may be stripped off during the secretion process. Strain variants of S. aureus that lack esaD encode at least two copies of EsaG-like proteins most likely to protect themselves from the toxic activity of EsaD secreted by esaD(+) strains. In support of this, a strain overproducing EsaD elicits significant growth inhibition against a sensitive strain. We conclude that T7SSs may play unexpected and key roles in bacterial competitiveness
Silencing α-Synuclein Gene Expression Enhances Tyrosine Hydroxylase Activity in MN9D Cells
α-Synuclein has been implicated in the pathogenesis of Parkinsonâs disease (PD). Previous studies have shown that α-synuclein is involved in the regulation of dopamine (DA) metabolism, possibly by down-regulating the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in DA biosynthesis. In this study, we constructed α-synuclein stably silenced MN9D/α-SYNâ cells by vector mediated RNA interference and examined its effects on DA metabolism. We found that there were no significant differences in TH protein and mRNA levels between MN9D, MN9D/α-SYNâ and MN9D/CON cells, suggesting that silencing α-synuclein expression does not affect TH gene expression. However, significant increases in phosphorylated TH, cytosolic 3, 4-dihydroxyphenylalanine (l-DOPA) and DA levels were observed in MN9D/α-SYNâ cells. Our data show that TH activity and DA biosynthesis were enhanced by down-regulation of α-synuclein, suggesting that α-synuclein may act as a negative regulator of cytosolic DA. With respect to PD pathology, a loss of functional α-synuclein may result in increased DA levels in neurons that may lead to cell injury or even death
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