Homenajes

Fil: Pró, Diego F..

Quantum Dots As Biophotonics Tools.

This chapter provides a short review of quantum dots (QDs) physics, applications, and perspectives. The main advantage of QDs over bulk semiconductors is the fact that the size became a control parameter to tailor the optical properties of new materials. Size changes the confinement energy which alters the optical properties of the material, such as absorption, refractive index, and emission bands. Therefore, by using QDs one can make several kinds of optical devices. One of these devices transforms electrons into photons to apply them as active optical components in illumination and displays. Other devices enable the transformation of photons into electrons to produce QDs solar cells or photodetectors. At the biomedical interface, the application of QDs, which is the most important aspect in this book, is based on fluorescence, which essentially transforms photons into photons of different wavelengths. This chapter introduces important parameters for QDs' biophotonic applications such as photostability, excitation and emission profiles, and quantum efficiency. We also present the perspectives for the use of QDs in fluorescence lifetime imaging (FLIM) and Förster resonance energy transfer (FRET), so useful in modern microscopy, and how to take advantage of the usually unwanted blinking effect to perform super-resolution microscopy.

Measuring The Hydrodynamic Radius Of Quantum Dots By Fluorescence Correlation Spectroscopy.

Fluorescence Correlation Spectroscopy (FCS) is an optical technique that allows the measurement of the diffusion coefficient of molecules in a diluted sample. From the diffusion coefficient it is possible to calculate the hydrodynamic radius of the molecules. For colloidal quantum dots (QDs) the hydrodynamic radius is valuable information to study interactions with other molecules or other QDs. In this chapter we describe the main aspects of the technique and how to use it to calculate the hydrodynamic radius of quantum dots (QDs).

ENVIRONMENTAL TEMPERATURES IN FLORIDA DAIRY HOUSING

Environmental conditions in all air-conditioned barn and in evaporatively cooled sprinkler and fall and tunnel-ventilated barns are compared and recommendations for dairy barn design for hot, humid climates arc, given. Temperature Humidity Indexes (THI) observed in the air-conditioned barn were always below 72. Average THIs ill the evaporatively cooled barns during afternoon hours were seldom less than 75. The environmental conditions observed in these studies are typical for many, areas adjacent to the Gulf Coast of the United States and for tropical regions throughout the world. Providing comfortable environmental conditions for cows housed in area with hot, humid climates is difficult using only evaporative cooling and ventilation. Air-conditioning dairy housing is a possible alternative method, particularly for high value cows.

Prostate cryoablation: Prospective analysis comparing high- and low-risk prostate cancer outcomes

Aim: To evaluate percutaneous cryotherapy as a primary treatment option for prostate cancer, comparing different risk groups. Patients and Methods: Forty-seven prostate cryoablation procedures were performed on 44 patients. Patients median age was 70.9, and average pretreatment PSA of 13.8 ng/dl. Patients were divided into low-risk (13 patients), high-risk (24 patients) and radiation failure patients (7 patients). The follow-up period ranged from 18 to 60 months (median 41 months). Results: In the low-risk group, we found after 12 and 24 months of follow-up, 92 and 86% of patients free of PSA relapse (PSA < 1 ng/ml), respectively. In the high-risk group, the PSA failure was 39 and 52.9%. For the radiation failure group, 86 and 71.4% of patients had PSA below 1 ng/dl. At 48 months of follow-up, 80% of the low-risk patients, 42.8% of the high-risk group and 71.4% of the radiation failure group were free of PSA relapse. The complication rates were low, with 13% of urinary incontinence and no cases of rectal injury. Conclusion: Prostate cryoablation is a viable and promising minimally invasive alternative for localized or locally advanced prostate cancer patients. Copyright (c) 2008 S. Karger AG, Basel.

Influência governamental e estratégias institucionais na difusão de inovações em economias emergentes

Em economias emergentes, programas públicos têm sido criados para estimular as empresas locais a investir em inovações, com o objetivo de alavancar o desenvolvimento econômico. Este artigo procura identificar, preliminarmente, fatores associados às influências institucionais na difusão de inovações em economias emergentes, assim como propor algumas relações básicas entre as variáveis envolvidas, tais como: as intervenções governamentais e os estágios do processo de difusão de inovações; as ações de governo e as forças que impulsionam o processo; e as políticas públicas e as características do quadro institucional geralmente encontrado nestas áreas. Buscando integrar conceitos de diversas áreas das ciências sociais, o trabalho oferece proposições, em diferentes níveis de análise, que descrevem vários aspectos da potencialmente forte influência que os governos nacionais detêm sobre o processo de difusão das inovações nos ambientes institucionais, de características particulares, existentes nas economias emergentes.

"Segurando na mão de Deus": organizações religiosas e apoio ao empreendedorismo

Este artigo investiga mecanismos de apoio ao empreendedorismo proporcionados por organizações religiosas. Foram pesquisadas duas organizações, uma católica e outra evangélica, por meio de estudo de caso qualitativo. A análise comparativa baseou-se em três dimensões específicas do apoio ao empreendedorismo que emergiram na própria pesquisa de campo e que denominamos espaços de informação, formação e motivação. Consideramos tais dimensões como importantes achados desta pesquisa e as utilizamos como categorias para investigar o impacto dos mecanismos oferecidos pelas organizações religiosas nas etapas do processo de empreendedorismo. Os resultados do trabalho indicam uma confluência entre os dois casos: o pertencimento às igrejas resulta na formação de capital social orientado para as várias dimensões econômicas e no reforço religioso à motivação econômica. As diferenças, contudo, encontram-se na representação religiosa do significado do sucesso econômico e na articulação e fechamento de suas respectivas redes sociais.

Fulminant hepatic failure in children and adolescents in Northern Brazil

The histological findings of fulminant hepatic failure were correlated to the demographic, clinical, biochemical and virological features in children and adolescents, native to the Amazonas State in Northern Brazil. 96.2% had evidence of infection by primary hepatotrophic viruses. Histological analysis revealed three distinct patterns of fulminant hepatic failure.

Creencias de Autoeficacia Profesional en alumnos del Instituto de Ciencias de la Administración (ICDA) de la Universidad Católica de Córdoba (UCC)

El tema del presente proyecto es la descripción de los niveles de ‘autoeficacia profesional’ en alumnos que cursan las diferentes opciones académicas del Instituto de Ciencias de la Administración (alumnos—ICDA), Universidad Católica de Córdoba. Se toma como marco teórico general los aportes actuales de la Psicología Organizacional Positiva (Salanova, Martínez, Llorens. 2005) y la Teoría Social Cognitiva (Bandura, 1977, 1986). Se presentan comparaciones de los resultados obtenidos en muestras locales (de las diferentes unidades académicas) con resultados de otra muestra anterior, llevada a cabo en España (que mide ‘autoeficacia profesional’ en trabajadores españoles), y muestras tomadas en otras localidades y empresas nacionales.

Construcción de un modelo explicativo del Burnout y Engagement en trabajadores cordobeses: el rol de las emociones y la autoeficacia profesional

Este proyecto trata sobre la construcción de un modelo explicativo del Burnout y Engagement en trabajadores cordobeses. Se presentan como variables fundamentales al rol de las emociones y la autoeficacia profesional en este modelo. Se detallan primero los antecedentes del tema, los objetivos general y específicos, luego la metodología a implementar en una muestra de 300 trabajadores cordobeses. Se describen los procedimientos estadísticos a utilizar y las escalas psicométricas (Escala de Autoeficacia Profesional, AP-10, Escala PANAS, Escala de Burnout Maslach, Escala de Engagement (en las versiones adaptadas al medio local)

Screening and fractionation of plant extracts with antiproliferative activity on human peripheral blood mononuclear cells

Three hundred and thirteen extracts from 136 Brazilian plant species belonging to 36 families were tested for their suppressive activity on phytohemaglutinin (PHA) stimulated proliferation of human peripheral blood mononuclear cells (PBMC). The proliferation was evaluated by the amount of [³H]-thymidine incorporated by the cells. Twenty extracts inhibited or strongly reduced the proliferation in a dose-dependent manner at doses between 10 and 100 µg/ml. Three of these extracts appeared to be non-toxic to lymphocytes, according to the trypan blue permeability assay and visual inspection using optical microscopy. Bioassay-guided fractionation of Alomia myriadenia extract showed that myriadenolide, a labdane diterpene known to occur in this species, could account for the observed activity of the crude extract. Using a similar protocol, an active fraction of the extract from Gaylussacia brasiliensis was obtained. Analysis of the ¹H and13C NMR spectra of this fraction indicates the presence of an acetylated triterpene whose characterization is underway. The extract of Himatanthus obovatus is currently under investigation.

8-Methoxy-naphtho[2,3-b]thiophen-4,9-quinone, a non-competitive inhibitor of trypanothione reductase

The enzyme trypanothione reductase is a recognised drug target in trypanosomatids and has been used in the search of new compounds with potential activity against diseases such as leishmaniasis, Chagas disease and African trypanosomiasis. 8-Methoxy-naphtho [2,3-b] thiophen-4,9-quinone was selected in a screening of natural and synthetic compounds using an in vitro assay with the recombinant enzyme from Trypanosoma cruzi. Its mode of inhibition fits a non-competitive model with respect to the substrate (trypanothione) and to the co-factor (NADPH), with Ki-values of 5 and 3.6 µM, respectively. When tested against human glutathione reductase, this compound did not display any significant inhibition at 100 µM, indicating a good selectivity against the parasite enzyme.