199 research outputs found
Experimental determination of distance and orientation of metallic nanodimers by polarization dependent plasmon coupling
Live cell imaging using metallic nanoparticles as tags is an emerging
technique to visualize long and highly dynamic processes due to the lack of
photobleaching and high photon rate. However, the lack of excited states as
compared to fluorescent dyes prevents the use of resonance energy transfer and
recently developed super resolution methods to measure distances between
objects closer that the resolution limit. In this work, we experimentally
demonstrate a technique to determine subdiffraction distances based on the near
field coupling of metallic nanoparticles. Due to the symmetry breaking in the
scattering cross section, not only distances but also relative orientations can
be measured. Gold nanoparticles were prepared on glass in such way that a small
fraction of dimers was present. The sample was sequentially illuminated with
two wavelengths to separate background from nanoparticle scattering based on
their spectral properties. A novel total internal reflection illumination
scheme in which the polarization can be rotated was used to further minimize
background contributions. In this way, radii, distance and orientation were
measured for each individual dimer and their statistical distributions were
found to be in agreement with the expected ones. We envision that this
technique will allow fast and long term tracking of relative distance and
orientation in biological processes.Comment: 9 pages, 5 figures, Commentary from the reviewer available in Papers
in Physic
Um método proativo para gerenciamento da segurança em instalações nucleares
Em razão da abordagem moderna para tratar a segurança em instalações nucleares que destaca que estas
organizações devem ser capazes de avaliar e gerenciar de forma proativa suas atividades torna-se cada vez mais importante a necessidade de instrumentos de avaliação das condições de trabalho. Nesse contexto, este trabalho apresenta um método proativo de gerenciamento da segurança organizacional, o qual apresenta três características inovadoras: 1) a utilização de indicadores preditivos que fornecem informações atuais sobre o desempenho das atividades, permitindo ações preventivas e não somente reativas na gestão da segurança, diferente dos indicadores de segurança tradicionalmente utilizados (indicadores reativos) que são obtidos após a ocorrência de eventos indesejados; 2) a adoção do enfoque da engenharia de resiliência no desenvolvimento dos indicadores – os indicadores são baseados em seis princípios da engenharia de resiliência: comprometimento da alta direção, aprendizagem, flexibilidade, consciência, cultura de justiça e preparação para os problemas; 3) a adoção dos conceitos e propriedades da teoria dos conjuntos fuzzy para lidar com a subjetividade e a consistência dos julgamentos humanos na avaliação dos indicadores. A teoria fuzzy é usada essencialmente para mapear modelos qualitativos de tomada de decisão, e para métodos de representação imprecisa. Os resultados deste trabalho objetivam uma melhoria no desempenho e na segurança nas organizações. O método foi aplicado no setor de expedição de radiofármacos de uma instalação nuclear. Os resultados mostraram que o método é uma boa
ferramenta de monitoramento de forma objetiva e proativa das condições de trabalho de um domínio organizacional
The Autodepalmitoylating activity of APT maintains the spatial organization of Palmitoylated membrane proteins
The localization and signaling of S-palmitoylated peripheral membrane proteins is sustained by an acylation cycle in which acyl protein thioesterases (APTs) depalmitoylate mislocalized palmitoylated proteins on endomembranes. However, the APTs are themselves reversibly S-palmitoylated, which localizes thioesterase activity to the site of the antagonistc palmitoylation activity on the Golgi. Here, we resolve this conundrum by showing that palmitoylation of APTs is labile due to autodepalmitoylation, creating two interconverting thioesterase pools: palmitoylated APT on the Golgi and depalmitoylated APT in the cytoplasm, with distinct functionality. By imaging APT-substrate catalytic intermediates, we show that it is the depalmitoylated soluble APT pool that depalmitoylates substrates on all membranes in the cell, thereby establishing its function as release factor of mislocalized palmitoylated proteins in the acylation cycle. The autodepalmitoylating activity on the Golgi constitutes a homeostatic regulation mechanism of APT levels at the Golgi that ensures robust partitioning of APT substrates between the plasma membrane and the Golgi.Fil: Vartak, Nachiket. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Papke, Bjoern. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Grecco, Hernan Edgardo. Institut Max Planck Fur Molekulare Physiologie; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rossmannek, Lisaweta. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Waldmann, Herbert. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Hedberg, Christian. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Bastiaens, Philippe I. H.. Institut Max Planck Fur Molekulare Physiologie; Alemani
SDSS-IV MaNGA: Radial Gradients in Stellar Population Properties of Early-Type and Late-Type Galaxies
We derive ages, metallicities, and individual element abundances of early-
and late-type galaxies (ETGs and LTGs) out to 1.5 R. We study a large
sample of 1900 galaxies spanning in stellar mass,
through key absorption features in stacked spectra from the SDSS-IV/MaNGA
survey. We use mock galaxy spectra with extended star formation histories to
validate our method for LTGs and use corrections to convert the derived ages
into luminosity- and mass-weighted quantities. We find flat age and negative
metallicity gradients for ETGs and negative age and negative metallicity
gradients for LTGs. Age gradients in LTGs steepen with increasing galaxy mass,
from Gyr/R for the lowest mass galaxies to
Gyr/R for the highest mass ones. This strong
gradient-mass relation has a slope of . Comparing local age and
metallicity gradients with the velocity dispersion within galaxies
against the global relation with shows that internal processes
regulate metallicity in ETGs but not age, and vice versa for LTGs. We further
find that metallicity gradients with respect to local show a much
stronger dependence on galaxy mass than radial metallicity gradients. Both
galaxy types display flat [C/Fe] and [Mg/Fe], and negative [Na/Fe] gradients,
whereas only LTGs display gradients in [Ca/Fe] and [Ti/Fe]. ETGs have
increasingly steep [Na/Fe] gradients with local reaching
dex/ km/s for the highest masses. [Na/Fe] ratios are correlated with
metallicity for both galaxy types across the entire mass range in our sample,
providing support for metallicity dependent supernova yields.Comment: 21 pages, 21 figures, 4 tables + Appendi
Liberação de nutrientes das frações minerais mesocrática e leucocráticados granitóides da pedreira silveira - Pelotas/RS.
Combined treatment with caffeic and ferulic acid from Baccharis uncinella C. DC. (Asteraceae) protects against metabolic syndrome in mice
Fractionation of the EtOH extract from aerial parts of Baccharis uncinella C. DC. (Asteraceae) led to isolation of caffeic and ferulic acids, which were identified from spectroscopic and spectrometric evidence. These compounds exhibit antioxidant and anti-inflammatory properties and have been shown to be effective in the prevention/treatment of metabolic syndrome. This study investigated whether the combined treatment of caffeic and ferulic acids exhibits a more significant beneficial effect in a mouse model with metabolic syndrome. The combination treatment with caffeic and ferulic acids was tested for 60 days in C57 mice kept on a high-fat (40%) diet. The data obtained indicated that treatment with caffeic and ferulic acids prevented gain in body weight induced by the high-fat diet and improved hyperglycemia, hypercholesterolemia and hypertriglyceridemia. The expression of a number of metabolically relevant genes was affected in the liver of these animals, showing that caffeic and ferulic acid treatment results in increased cholesterol uptake and reduced hepatic triglyceride synthesis in the liver, which is a likely explanation for the prevention of hepatic steatosis. In conclusion, the combined treatment of caffeic and ferulic acids displayed major positive effects towards prevention of multiple aspects of the metabolic syndrome and liver steatosis in an obese mouse model.CAPESFAPESPMackPesquisaUniv Presbiteriana Mackenzie, Programa Posgrad Disturbios Desenvolvimento, Ctr Ciencias Biol & Saude, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Med Translac, Escola Paulista Med, Sao Paulo, SP, BrazilUniv Fed ABC, Ctr Ciencias Nat & Humanas, Sao Paulo, SP, BrazilEscola Ciencias Med, Dept Ciencias Patol, Sao Paulo, SP, BrazilUniv Presbiteriana Mackenzie, Escola Engn, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Sao Paulo, SP, BrazilRush Univ & Med Ctr, Dept Internal Med, Div Endocrinol & Metab, Chicago, IL 60612 USAUniv Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Sao Paulo, SP, BrazilFAPESP: 2011/21847-6Web of Scienc
Eugenia uniflora fruit (red type) standardized extract: a potential pharmacological tool to diet-induced metabolic syndrome damage management.
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Intoxicação aguda e abortos em cobaias pelas favas de Enterolobium contortisiliquum (Leg. Mimosoideae)
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