246 research outputs found
O design educacional para a modalidade a distância em uma perspectiva inclusiva: contribuições para/na formação docente.
Este estudo, de cunho qualitativo, analisou o Design Educacional para a modalidade a distância no Centro de Educação a Distância do Instituto Federal do Espírito Santo recorrendo a uma pesquisa-ação com três grupos focais: Grupo 1 - equipe de produção de recursos educacionais; Grupo 2 - professores-formadores em Educação a Distância e Grupo 3 - alunosprofessores do curso de Capacitação em Práticas para Educação a Distância para Professores na modalidade a distância. O Design Educacional envolve diferentes áreas de conhecimento e aportes teóricos, sendo que este estudo optou pelas contribuições de Piaget e de Vigotski no que se refere ao processo de aprendizagem e interação social; Moore e Kearsley, nas questões que envolvem a Educação a Distância; Filatro e Torezzan para o Design Instrucional. Nas discussões suscitadas no Grupo 1, da equipe de produção de recursos educacionais, foram identificadas dentre várias questões, as principais dificuldades e desafios do Design Educacional na sociedade contemporânea. A coleta de dados e a análise dos resultados dessas discussões culminaram na criação de uma Taxonomia para o uso das Mídias, além de contribuições relevantes para a criação de alguns recursos educacionais. O Grupo 2, dos professores-formadores, apoiado nos resultados do Grupo 1, tendo em vista a inclusão de alguns alunos-professores convidados, graduados e deficientes - três com surdez e dois deficientes visuais -, contribuiu para evidenciar as ações-reflexões do Design Educacional no curso escolhido, adotando uma perspectiva inclusiva, inspirada no Universal Design for Learning. O Grupo 3, de alunos-professores, avaliou as ações resultantes da pesquisa. Recorreu-se a cinco categorias de análise dos dados: o Design Educacional na instituição pesquisada; a relação entre os professores-formadores e o Design Educacional; representações sobre o processo de ensino e de aprendizagem dos profissionais envolvidos no Design Educacional; alunos-professores em formação para a Educação a Distância; as perspectivas do Design Educacional na sociedade contemporânea. Os resultados obtidos trouxeram contribuições teóricas e práticas para a formação docente, acarretando, ainda: mudanças de conduta dos Grupos 1 e 2 no planejamento e na produção de recursos educacionais; além da proposta de inclusão de uma equipe de Design Educacional junto à equipe de produção, com uma consequente melhora do trabalho colaborativo. Foi destacada, também, a necessidade de uma melhor definição das concepções e do modelo de educação a distância adotado pelo Instituto Federal do Espírito Santo, o que, por sua vez, impactariam no Design Educacional em uma perspectiva inclusiva
Influence of biological activity on 65Zn and 109Cd removal from tidal water by chronically-polluted mangrove sediments
The biological activity influence on the mangrove sediment capacity to remove 65Zn and 109Cd from tidal water was evaluated in a site chronically polluted. Benthic Activity Indexes (BAI), corresponding to relative estimates of biological impact on radiotracer accumulation, were higher for 109Cd (~ 38%) than for 65Zn (~ 10%) in the top centimetre of sediment. However, BAI exceeded 96% for deeper sediment layers. This apparent decrease in radiotracer diffusion into deep sediments through biological activity inhibition is stronger than reported for much less polluted mangrove nearby, suggesting that benthic organisms tolerant of chronic metal pollution may affect metal sorption mechanisms.info:eu-repo/semantics/publishedVersio
Generation of a wave packet tailored to efficient free space excitation of a single atom
We demonstrate the generation of an optical dipole wave suitable for the
process of efficiently coupling single quanta of light and matter in free
space. We employ a parabolic mirror for the conversion of a transverse beam
mode to a focused dipole wave and show the required spatial and temporal
shaping of the mode incident onto the mirror. The results include a proof of
principle correction of the parabolic mirror's aberrations. For the application
of exciting an atom with a single photon pulse we demonstrate the creation of a
suitable temporal pulse envelope. We infer coupling strengths of 89% and
success probabilities of up to 87% for the application of exciting a single
atom for the current experimental parameters.Comment: to be published in Europ. Phys. J.
Structural characterization of anti-inflammatory Immunoglobulin G Fc proteins
Immunoglobulin G (IgG) is a central mediator of host defense due to its ability to recognize and eliminate pathogens. The recognition and effector responses are encoded on distinct regions of IgGs. The diversity of the antigen recognition Fab domains accounts for IgG’s ability to bind with high specificity to essentially any antigen. Recent studies have indicated that the Fc effector domain also displays considerable heterogeneity, accounting for its complex effector functions of inflammation, modulation and immune suppression. Therapeutic anti-tumor antibodies, for example, require the pro-inflammatory properties of the IgG Fc to eliminate tumor cells, while the anti-inflammatory activity of Intravenous Immunoglobulin G (IVIG) requires specific Fc glycans for activity. In particular, the anti-inflammatory activity of IVIG is ascribed to a small population of IgGs in which the Asn297-linked complex N-glycans attached to each Fc C_H2 domain include terminal α2,6-linked sialic acids. We used chemoenzymatic glycoengineering to prepare fully di-sialylated IgG Fc and solved its crystal structure. Comparison of the structures of asialylated Fc, sialylated Fc, and F241A Fc, a mutant that displays increased glycan sialylation, suggests that increased conformational flexibility of the C_H2 domain is associated with the switch from pro- to anti-inflammatory activity of the Fc
Design of a mode converter for efficient light-atom coupling in free space
In this article, we describe how to develop a mode converter that transforms
a plane electromagnetic wave into an inward moving dipole wave. The latter one
is intended to bring a single atom or ion from its ground state to its excited
state by absorption of a single photon wave packet with near-100% efficiency.Comment: RevTex4, 3 figures, revised version, accepted for publication at
Appl. Phys.
Structural Basis for c-di-GMP-Mediated Inside-Out Signaling Controlling Periplasmic Proteolysis
X-ray crystallographic structural analyses of the bacterial transmembrane receptor LapD identify conserved molecular mechanisms that control biofilm formation in response to changes in the intracellular levels of the second messenger c-di-GMP
Dermatologist-like explainable AI enhances trust and confidence in diagnosing melanoma
Although artificial intelligence (AI) systems have been shown to improve the
accuracy of initial melanoma diagnosis, the lack of transparency in how these
systems identify melanoma poses severe obstacles to user acceptance.
Explainable artificial intelligence (XAI) methods can help to increase
transparency, but most XAI methods are unable to produce precisely located
domain-specific explanations, making the explanations difficult to interpret.
Moreover, the impact of XAI methods on dermatologists has not yet been
evaluated. Extending on two existing classifiers, we developed an XAI system
that produces text and region based explanations that are easily interpretable
by dermatologists alongside its differential diagnoses of melanomas and nevi.
To evaluate this system, we conducted a three-part reader study to assess its
impact on clinicians' diagnostic accuracy, confidence, and trust in the
XAI-support. We showed that our XAI's explanations were highly aligned with
clinicians' explanations and that both the clinicians' trust in the support
system and their confidence in their diagnoses were significantly increased
when using our XAI compared to using a conventional AI system. The clinicians'
diagnostic accuracy was numerically, albeit not significantly, increased. This
work demonstrates that clinicians are willing to adopt such an XAI system,
motivating their future use in the clinic
A c-di-GMP Effector System Controls Cell Adhesion by Inside-Out Signaling and Surface Protein Cleavage
In Pseudomonas fluorescens Pf0-1 the availability of inorganic phosphate (Pi) is an environmental signal that controls biofilm formation through a cyclic dimeric GMP (c-di-GMP) signaling pathway. In low Pi conditions, a c-di-GMP phosphodiesterase (PDE) RapA is expressed, depleting cellular c-di-GMP and causing the loss of a critical outer-membrane adhesin LapA from the cell surface. This response involves an inner membrane protein LapD, which binds c-di-GMP in the cytoplasm and exerts a periplasmic output promoting LapA maintenance on the cell surface. Here we report how LapD differentially controls maintenance and release of LapA: c-di-GMP binding to LapD promotes interaction with and inhibition of the periplasmic protease LapG, which targets the N-terminus of LapA. We identify conserved amino acids in LapA required for cleavage by LapG. Mutating these residues in chromosomal lapA inhibits LapG activity in vivo, leading to retention of the adhesin on the cell surface. Mutations with defined effects on LapD's ability to control LapA localization in vivo show concomitant effects on c-di-GMP-dependent LapG inhibition in vitro. To establish the physiological importance of the LapD-LapG effector system, we track cell attachment and LapA protein localization during Pi starvation. Under this condition, the LapA adhesin is released from the surface of cells and biofilms detach from the substratum. This response requires c-di-GMP depletion by RapA, signaling through LapD, and proteolytic cleavage of LapA by LapG. These data, in combination with the companion study by Navarro et al. presenting a structural analysis of LapD's signaling mechanism, give a detailed description of a complete c-di-GMP control circuit—from environmental signal to molecular output. They describe a novel paradigm in bacterial signal transduction: regulation of a periplasmic enzyme by an inner membrane signaling protein that binds a cytoplasmic second messenger
Polymeric human Fc-fusion proteins with modified effector functions
The success of Fc-fusion bio-therapeutics has spurred the development of other Fc-fusion products for treating and/or vaccinating against a range of diseases. We describe a method to modulate their function by converting them into well-defined stable polymers. This strategy resulted in cylindrical hexameric structures revealed by tapping mode atomic force microscopy (AFM). Polymeric Fc-fusions were significantly less immunogenic than their dimeric or monomeric counterparts, a result partly owing to their reduced ability to interact with critical Fc-receptors. However, in the absence of the fusion partner, polymeric IgG1-Fc molecules were capable of binding selectively to FcγRs, with significantly increased affinity owing to their increased valency, suggesting that these reagents may prove of immediate utility in the development of well-defined replacements for intravenous immunoglobulin (IVIG) therapy. Overall, these findings establish an effective IgG Fc-fusion based polymeric platform with which the therapeutic and vaccination applications of Fc-fusion immune-complexes can now be explored
The Lid Domain of Caenorhabditis elegans Hsc70 Influences ATP Turnover, Cofactor Binding and Protein Folding Activity
Hsc70 is a conserved ATP-dependent molecular chaperone, which utilizes the energy of ATP hydrolysis to alter the folding state of its client proteins. In contrast to the Hsc70 systems of bacteria, yeast and humans, the Hsc70 system of C. elegans (CeHsc70) has not been studied to date
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