Three-dimensional nanoscopy of colloidal crystals.

We demonstrate the direct three-dimensional imaging of densely packed colloidal nanostructures using stimulated emission depletion microscopy. A combination of two de-excitation patterns yields a resolution of 43 nm in the lateral and 125 nm in the axial direction and an effective focal volume that is by 126-fold smaller than that of a corresponding confocal microscope. The mapping of a model system of spheres organized by confined convective assembly unambiguously identified face-centered cubic, hexagonal close-packed, random hexagonal close-packed, and body-centered cubic structures. An increasing need for noninvasive visualization on the nanoscale has fueled the development of far-field optical microscopy with resolution far below the wavelength of light.1,2 In materials science, structural studies with length scales of interest in the (sub-) micrometer range have typically been conducted either by collective scattering-based techniques or electron and scanning probe microscopes. Far-field optical methods however retain the advantage of simultaneously providing local, dynamic, and noninvasiv

Approaches to learning and academic performance in pharmacology among second-year undergraduate medical students = Abordagens de aprendizagem e desempenho acadêmico em farmacologia entre estudantes de medicina do segundo ano

OBJETIVOS: Investigar a abordagem de aprendizagem de estudantes de medicina do segundo ano de graduação e se uma abordagem superficial ou profunda teve alguma correlação com as notas obtidas na disciplina de farmacologia e nos exames universitários. MÉTODOS: Um estudo transversal foi conduzido entre estudantes do segundo ano de medicina em seu quinto semestre. Para determinar a abordagem de aprendizagem dos alunos, como superficial ou profunda, usamos o questionário Revised Two Factor Study Process Questionnaire (R-SPQ-2F), que contém 20 itens em forma de uma escala Likert de cinco pontos, sendo o seu uso adequado para ambientes de ensino superior. O alfa de Cronbach foi calculado usando as pontuações obtidas de uma amostra de 20 alunos para determinar a consistência interna. Para determinar a relação entre a abordagem de aprendizagem e as pontuações do exame, calculou-se a média das notas dos exames individuais e as pontuações dos exames universitários obtidas pelos alunos. RESULTADOS: Dos 170 alunos que participaram do estudo, 87 (51,2%) eram do gênero feminino. O alpha de Cronbach foi considerado bom tanto para a abordagem superficial quanto profunda. Enquanto o desempenho acadêmico foi significativamente melhor em mulheres (U=2571,5; p=0,001), nenhuma diferença baseada no gênero foi observada na abordagem de aprendizagem. Cinquenta (29,4%) estudantes tiveram uma pontuação mais alta para a abordagem superficial. Esse grupo teve escores de exame mais baixos em comparação com aqueles com escores iguais para abordagem superficial e profunda ou escores mais altos para a abordagem profunda. Uma fraca correlação negativa foi observada entre as notas do exame e a abordagem superficial (τb=-0,167; p=0,002). Quando analisada com base no gênero, encontrou-se uma correlação de magnitude fraca e negativa apenas no gênero feminino (τb=-0,173; p=0,02). CONCLUSÕES: Uma fraca correlação negativa foi observada entre as notas do exame e a abordagem superficial para a aprendizagem. Embora estatisticamente significativa, a diferença real entre os grupos foi de pequena magnitude. Portanto, se a promoção de uma abordagem de aprendizagem profunda melhora o desempenho acadêmico em termos de notas obtidas no exame, isso precisa ser confirmado por outros estudo

Rtt107 Phosphorylation Promotes Localisation to DNA Double-Stranded Breaks (DSBs) and Recombinational Repair between Sister Chromatids

Efficient repair of DNA double-stranded breaks (DSB) requires a coordinated response at the site of lesion. Nucleolytic resection commits repair towards homologous recombination, which preferentially occurs between sister chromatids. DSB resection promotes recruitment of the Mec1 checkpoint kinase to the break. Rtt107 is a target of Mec1 and serves as a scaffold during repair. Rtt107 plays an important role during rescue of damaged replication forks, however whether Rtt107 contributes to the repair of DSBs is unknown. Here we show that Rtt107 is recruited to DSBs induced by the HO endonuclease. Rtt107 phosphorylation by Mec1 and its interaction with the Smc5–Smc6 complex are both required for Rtt107 loading to breaks, while Rtt107 regulators Slx4 and Rtt101 are not. We demonstrate that Rtt107 has an effect on the efficiency of sister chromatid recombination (SCR) and propose that its recruitment to DSBs, together with the Smc5–Smc6 complex is important for repair through the SCR pathway

Proteolysis of proBDNF Is a Key Regulator in the Formation of Memory

It is essential to understand the molecular processes underlying long-term memory to provide therapeutic targets of aberrant memory that produce pathological behaviour in humans. Under conditions of recall, fully-consolidated memories can undergo reconsolidation or extinction. These retrieval-mediated memory processes may rely on distinct molecular processes. The cellular mechanisms initiating the signature molecular events are not known. Using infusions of protein synthesis inhibitors, antisense oligonucleotide targeting brain-derived neurotrophic factor (BDNF) mRNA or tPA-STOP (an inhibitor of the proteolysis of BDNF protein) into the hippocampus of the awake rat, we show that acquisition and extinction of contextual fear memory depended on the increased and decreased proteolysis of proBDNF (precursor BDNF) in the hippocampus, respectively. Conditions of retrieval that are known to initiate the reconsolidation of contextual fear memory, a BDNF-independent memory process, were not correlated with altered proBDNF cleavage. Thus, the processing of BDNF was associated with the acquisition of new information and the updating of information about a salient stimulus. Furthermore, the differential requirement for the processing of proBDNF by tPA in distinct memory processes suggest that the molecular events actively engaged to support the storage and/or the successful retrieval of memory depends on the integration of ongoing experience with past learning

What is damaging the kidney in lupus nephritis?

Despite marked improvements in the survival of patients with severe lupus nephritis over the past 50 years, the rate of complete clinical remission after immune suppression therapy i

Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions

At sufficiently high temperature and energy density, nuclear matter undergoes a transition to a phase in which quarks and gluons are not confined: the quark-gluon plasma (QGP)(1). Such an exotic state of strongly interacting quantum chromodynamics matter is produced in the laboratory in heavy nuclei high-energy collisions, where an enhanced production of strange hadrons is observed(2-6). Strangeness enhancement, originally proposed as a signature of QGP formation in nuclear collisions(7), is more pronounced for multi-strange baryons. Several effects typical of heavy-ion phenomenology have been observed in high-multiplicity proton-proton (pp) collisions(8,9), but the enhanced production of multi-strange particles has not been reported so far. Here we present the first observation of strangeness enhancement in high-multiplicity proton-proton collisions. We find that the integrated yields of strange and multi-strange particles, relative to pions, increases significantly with the event charged-particle multiplicity. The measurements are in remarkable agreement with the p-Pb collision results(10,11), indicating that the phenomenon is related to the final system created in the collision. In high-multiplicity events strangeness production reaches values similar to those observed in Pb-Pb collisions, where a QGP is formed.Peer reviewe

D-Meson Azimuthal Anisotropy in Midcentral Pb-Pb Collisions root S-NN=5.02 TeV

The azimuthal anisotropy coefficient v(2) of prompt D-0, D+, D*+, and D-s(+) mesons was measured in midcentral (30%-50% centrality class) Pb-Pb collisions at a center-of-mass energy per nucleon pair root s(NN)=5.02 TeV, with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays at midrapidity, |y| < 0.8, in the transverse momentum interval 1 < p(T) < 24 GeV/c. The measured D-meson v(2) has similar values as that of charged pions. The D-s(+) v(2), measured for the first time, is found to be compatible with that of nonstrange D mesons. The measurements are compared with theoretical calculations of charm-quark transport in a hydrodynamically expanding medium and have the potential to constrain medium parameters.Peer reviewe