Aedes aegypti is the main vector for dengue and urban yellow fever. It is extended around the world not only in the tropical regions but also beyond them, reaching temperate climates. Because of its importance as a vector of deadly diseases, the significance of its distribution in urban areas and the possibility of breeding in laboratory facilities, Aedes aegypti is one of the best-known mosquitoes. In this work the biology of Aedes aegypti is incorporated into the framework of a stochastic population dynamics model able to handle seasonal and total extinction as well as endemic situations. The model incorporates explicitly the dependence with temperature. The ecological parameters of the model are tuned to the present populations of Aedes aegypti in Buenos Aires city, which is at the border of the present day geographical distribution in South America. Temperature thresholds for the mosquito survival are computed as a function of average yearly temperature and seasonal variation as well as breeding site availability. The stochastic analysis suggests that the southern limit of Aedes aegypti distribution in South America is close to the 15 degrees C average yearly isotherm, which accounts for the historical and current distribution better than the traditional criterion of the winter (July) 10 degrees C isotherm.

We develop a stochastic spatial model for Aedes aegypti populations based on the life cycle of the mosquito and its dispersal. Our validation corresponds to a monitoring study performed in Buenos Aires. Lacking information with regard to the number of breeding sites per block, the corresponding parameter (BS) was adjusted to the data. The model is able to produce numerical data in very good agreement with field results during most of the year, the exception being the fall season. Possible causes of the disagreement are discussed. We analyzed the mosquito dispersal as an advantageous strategy of persistence in the city and simulated the dispersal of females from a source to the surroundings along a 3-year period observing that several processes occur simultaneously: local extinctions, recolonization processes (resulting from flight and the oviposition performed by flyers), and colonization processes resulting from the persistence of eggs during the winter season. In view of this process, we suggest that eradication campaigns in temperate climates should be performed during the winter time for higher efficiency.

Layer-by-layer supramolecular structures composed of alternate layers of negatively charged enzymes and cationic redox polyelectrolyte have been assembled. Glucose oxidase (GOx), lactate oxidase (LOx) and soybean peroxidase (SBP) have been electrically wired to the underlying electrode by means of poly(allylamine) with [Os(bpy)2 ClPyCOH]c ovalently attached (PAAÈOs) in organized structures with high spatial resolution. Biotinylated glucose oxidase has also been used to assemble step-by-step on antibiotin goat immunoglobulin (IgG) layers and the enzyme was electrically wired by PAAÈOs. These spatially organized multilayers with mono-and bienzymatic schemes can work efficiently in molecular recognition, redox mediation and generation of an electrical signal. The concentration of redox mediator integrated into the multilayers, obtained from the voltammetric charge and an estimation of the layer thickness, exceeds by 100-fold the amount of deposited enzyme assessed by quartz crystal microbalance. Di †erences in GOx electrical wiring efficiency have been detected with the di †erent assembling strategies. The surface concentration of electrically wired enzyme represents a small proportion of all the enzyme molecules present in the multilayers which can be oxidized by the soluble mediator PyCOOH]Cl. This proportion, as well as the rate of [Os(bpy) 2 Cl FADH 2 oxidation by PAAÈOs, increases with the number of electrically wired enzyme layers and with the spatial accessibility of the Os moiety to the enzyme active center.

Self-assembled multilayers composed of alternated layers of glucose oxidase (GOx) and poly(allylamine) covalently attached to [Os(bpy)2ClPyCOH]+ (PAH−Os), deposited on a 3-mercaptopropanesulfonic acid (MPS)-modified gold surface were studied “ex situ” and “in situ” (with the films in contact with water) by ellipsometry and quartz crystal microbalance (QCM). The ellipsometric parameters of the thiol film on gold in the first layer were analyzed in terms of an anisotropic single-layer model. For the subsequent (PAH−Os) n (GOx) n multilayers on Au, a two-layer model with the anisotropic thiol film and the isotropic enzyme/polyelectrolyte film yielded identical results with an isotropic one-layer model with the substrate parameters measured after thiol adsorption to offset any effect due to the Au−S bond. Film thickness and complex refractive index for each adsorbed layer in Au/MPS/(PAH−Os) n (GOx) n multilayers were determined for dry films and for films in contact with water. Quartz crystal impedance analysis showed that the self-assembled multilayers behave as acoustically thin films (rigid), and therefore the observed shifts in the resonance frequency were interpreted in gravimetric terms. The mass of enzyme in each adsorption step was determined by the quartz crystal microbalance for both dry films and films exposed to water. From comparison of the ellipsometric thickness and acoustic mass, the average apparent film density (1.7 ± 0.2 g cm-3) was estimated. A model for the enzyme and redox polyelectrolyte distribution in the (PAH−Os) n (GOx) n multilayer structure is presented on the basis of combined ellipsometric and QCM results. A comparison of the QCM mass and the ellipsometric mass based on the de Feijter equation fails to sense the layer near the film/water interface while the acoustic method senses the coupled water and open polymer−enzyme structure at the polymer/liquid interface.

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In this work we explore the effects of human mobility on the dispersion of a vector borne disease. We combine an already presented stochastic model for dengue with a simple representation of the daily motion of humans on a schematic city of 20 × 20 blocks with 100 inhabitants in each block. The pattern of motion of the individuals is described in terms of complex networks in which links connect different blocks and the link length distribution is in accordance with recent findings on human mobility. It is shown that human mobility can turn out to be the main driving force of the disease dispersal.

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