A mathematically assisted reconstruction of the initial focus of the yellow fever outbreak in Buenos Aires (1871)

We discuss the historic mortality record corresponding to the initial focus of the yellow fever epidemic outbreak registered in Buenos Aires during the year 1871 as compared to simulations of a stochastic population dynamics model. This model incorporates the biology of the urban vector of yellow fever, the mosquito Aedes aegypti, the stages of the disease in the human being as well as the spatial extension of the epidemic outbreak. After introducing the historical context and the restrictions it puts on initial conditions and ecological parameters, we discuss the general features of the simulation and the dependence on initial conditions and available sites for breeding the vector. We discuss the sensitivity, to the free parameters, of statistical estimators such as: final death toll, day of the year when the outbreak reached half the total mortality and the normalized daily mortality, showing some striking regularities. The model is precise and accurate enough to discuss the truthfulness of the presently accepted historic discussions of the epidemic causes, showing that there are more likely scenarios for the historic facts.Comment: 25 pages, 12 figure

Ochratoxigenic aspergillus in wine grapes and ochratoxin a in wines from Northeast Brazil.

Resumo

Aspergillus ocratoxigênicos em uvas e no solo de cultivo da variedade Sauvignon Blanc no Nordeste brasileiro.

A ocratoxina A (OTA) é um metabólito secundário de fungos freqüentemente encontrado como contaminante de uvas, vinhos e suco de uva, sendo considerada uma das micotoxinas mais prejudiciais para a saúde humana. Este estudo teve como objetivo avaliar a incidência de Aspergillusocratoxigênicos em uvas e no solo de cultivo da variedade Sauvignon Blanc utilizada para produção de vinho no nordeste brasileiro. As amostras de uva e de solo foram coletadas em uma região vitivinícola do Submédio São Francisco (Casa Nova, Bahia). Para o isolamento de fungos das uvas e sementes utilizou-se a Técnica de Plaqueamento Direto em meio de cultura DRBC (Dicloran Rosa Bengal Cloranfenicol); para a amostra de solo foi utilizada a técnica de espalhamento superficial, em DG 18 (Dichloran 18% Glycerol Agar), a partir de diluições seriadas. Selecionou-se para obtenção de culturas puras apenas os fungos do gênero Aspergillus que foram identificados por características morfológicas e avaliados, quanto à produção de OTA, pelo Método Plug Agar. Das uvas foram isoladas e identificadas as seguintes espécies A. foetidus, A. tubingensis e A. sp.. Destes isolados nenhum foi ocratoxigênico. Dos vinte e nove isolados obtidos do solo, quatro foram ocratoxigênicos (A. niger agregado (1), A. carbonarius agregado (2) e A. carbonarius (1)), o que realça a importância de evitar durante a colheita o contato das uvas com o solo, visto que este pode representar uma fonte de contaminação com esta micotoxina para as uvas e vinhos. Palavras-chaves: Fungos ocratoxigênicos, Uvas, Aspergillus, Ocratoxina A, Solo, Sauvignon Blan

Fungos ocratoxigênicos em solo de cultivo de uvas viníferas no Nordeste brasileiro.

Ocratoxina A (OTA) é um metabólito secundário de origem fúngica que tem recebido atenção crescente devido ao potencial perigo para os seres humanos e animais. Este estudo teve como objetivo avaliar a incidência de fungos ocratoxigênicos do gênero Aspergillus em solos de cultivo de uvas viníferas no nordeste brasileiro. Foram coletadas amostras de solo de cultivo de três variedades de uvas viníferas, Cabernet Sauvignon, Grenache e Petit Verdot de uma região vitivinícola do nordeste brasileiro. Para o isolamento de fungos foi utilizada a técnica de espalhamento superficial, em DG 18 (Dichloran 18% Glycerol Agar), a partir de diluições seriadas. Selecionou-se para obtenção de culturaspuras apenas os fungos do gênero Aspergillus que foram identificados por características morfológicas e avaliados, quanto à produção de OTA, pelo Método Plug Agar. Das amostras de solo foram isoladas e identificadas as seguintes espécies A. foetidus, A. aculeatus, A. niger, A. tubingensis, A. carbonariuse A. ibericus. Dos vinte e quatro isolados fúngicos obtidos quatro foram ocratoxigênicos (A. niger (1), A. tubingensis (1) e A. carbonarius (2)), o que evidência a importância de evitar durante a colheita o contato das uvas com o solo, visto que este pode representar uma fonte de contaminação com esta micotoxina para as uvas e vinhos.Palavras-chaves: Fungos ocratoxigênicos, Uvas viníferas, Aspergillus, Ocratoxina A, Sol

Solution-Processable Carbon Nanoelectrodes for Single-Molecule Investigations

We gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council under Award EP/M029506/1

Co-firing of biomass with coals Part 1. Thermogravimetric kinetic analysis of combustion of fir (abies bornmulleriana) wood

The chemical composition and reactivity of fir (Abies bornmulleriana) wood under non-isothermal thermogravimetric (TG) conditions were studied. Oxidation of the wood sample at temperatures near 600 A degrees C caused the loss of aliphatics from the structure of the wood and created a char heavily containing C-O functionalities and of highly aromatic character. On-line FTIR recordings of the combustion of wood indicated the oxidation of carbonaceous and hydrogen content of the wood and release of some hydrocarbons due to pyrolysis reactions that occurred during combustion of the wood. TG analysis was used to study combustion of fir wood. Non-isothermal TG data were used to evaluate the kinetics of the combustion of this carbonaceous material. The article reports application of Ozawa-Flynn-Wall model to deal with non-isothermal TG data for the evaluation of the activation energy corresponding to the combustion of the fir wood. The average activation energy related to fir wood combustion was 128.9 kJ/mol, and the average reaction order for the combustion of wood was calculated as 0.30

Quantum size effects in Pb islands on Cu(111): Electronic-structure calculations

The appearance of "magic" heights of Pb islands grown on Cu(111) is studied by self-consistent electronic structure calculations. The Cu(111) substrate is modeled with a one-dimensional pseudopotential reproducing the essential features, i.e. the band gap and the work function, of the Cu band structure in the [111] direction. Pb islands are presented as stabilized jellium overlayers. The experimental eigenenergies of the quantum well states confined in the Pb overlayer are well reproduced. The total energy oscillates as a continuous function of the overlayer thickness reflecting the electronic shell structure. The energies for completed Pb monolayers show a modulated oscillatory pattern reminiscent of the super-shell structure of clusters and nanowires. The energy minima correlate remarkably well with the measured most probable heights of Pb islands. The proper modeling of the substrate is crucial to set the quantitative agreement.Comment: 4 pages, 4 figures. Submitte

Biotin-tagged fluorescent sensor to visualize "mobile' Zn2+ in cancer cells

A cancer cell-targeting fluorescent sensor has been developed to image mobile Zn2+ by introducing a biotin group. It shows a highly selective response to Zn2+ in vitro, no toxicity in cellulo and images 'mobile' Zn2+ specifically in cancer cells. We believe this probe has the potential to help improve our understanding of the role of Zn2+ in the processes of cancer initiation and development

Tissue factor as a novel marker for detection of circulating cancer cells

Tissue factor (TF) is a molecular marker that is up-regulated in cancer cells and aids tumoral dissemination. Our purpose was to develop a nested RT-PCR strategy against TF for detecting blood-borne tumour cells. Our method detected TF expression in a minimum of 1.5 pg total RNA from MCF7 cells. A preliminary study in blood samples from 16 advanced breast carcinoma patients showed that 80% of patients with high TF load progressed and died, while only 18% with low TF load showed the same behaviour. Kaplan-Meier analysis confirmed worse overall survival in patients with high TF load.Fil: Otero, L. L.. Universidad Nacional de Quilmes; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Castro, M.. Universidad de Buenos Aires; ArgentinaFil: Cinat, G.. Universidad de Buenos Aires; ArgentinaFil: Gabri, M. R.. Universidad Nacional de Quilmes; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin