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M D Cunha

Publications and source records attributed to M D Cunha.

3 recordsLinked to original sources

A qualitative assessment of long distance truck drivers' vulnerability to HIV/AIDS in Itajaí, southern Brazil.

Itajaí is the largest port in southern Brazil and has one of the nation's highest AIDS incidence rates. Since over 400 truck drivers enter the city daily, they may play a key role in the HIV/AIDS epidemic due to transactions with commercial sex workers (CSWs) and/or substance use. We conducted a rapid assessment to establish the context of HIV vulnerability among truckers and CSWs in Itajaí. Forty three in-depth interviews and eight focus groups were conducted with truckers and CSWs. Two truck-driving routes involving brothels, meeting places and drug-use locations were mapped and field observations were collected. Tapes and field notes were transcribed and analyzed for emerging themes. Truck drivers typically had unprotected sex with several partners, including CSWs and truckstop employees. Both truckers and CSWs had low perceived HIV risk in spite of being engaged in high-risk sex behaviors. Use of alcohol and amphetamine-like drugs was frequent among truckers and appeared to influence unsafe sex practices. Knowledge about amphetamine-related risks was low, as was access to health services and HIV/AIDS behavioral interventions. Interventions, targeting truckers, CSWs and truckstop employees, are needed that traverse cities, states and borders and take into account seasonality, spatial context and workplace conditions.

Alcohol Drinking↗

Bifurcation points in the theory of axially symmetric arc cathodes.

Steady-state current transfer from arc plasmas to axially symmetric cathodes is treated in the framework of the model of nonlinear surface heating. An approach is developed to calculate the bifurcation points at which three-dimensional spot-mode solutions branch off from solutions describing the diffuse mode and axially symmetric spot modes. In particular, the first bifurcation point positioned on the diffuse-mode solution has been calculated, and thus its stability limit, i.e., the current below which the diffuse mode becomes unstable. Calculation results are given for the case of a tungsten cathode in the form of a circular cylinder in high-pressure plasmas. The effect produced on the stability limit by variations of control parameters (cathode dimensions, work function of the cathode material, plasma-producing gas, and its pressure) is studied and found to conform to trends observed experimentally. The stability limit is found to be much more sensitive to variations of control parameters than characteristics of the diffuse mode are, the strongest effect being produced by variations of cathode dimensions and of the work function of the cathode material. This finding conforms to the fact that the diffuse-spot transition is difficult to reproduce in the experiment.

Journal Article↗

Three-wave interaction in two-component quadratic nonlinear lattices.

We investigate a two-component lattice with a quadratic nonlinearity and find with the multiple scale technique that integrable three-wave interaction takes place between plane wave solutions when these fulfill resonance conditions. We demonstrate that energy conversion and pulse propagation known from three-wave interaction is reproduced in the lattice and that exact phase matching of parametric processes can be obtained in non-phase-matched lattices by tilting the interacting plane waves with respect to each other.

Journal Article↗