Solution of the quantum harmonic oscillator plus a delta-function potential at the origin: The oddness of its even-parity solutions

We derive the energy levels associated with the even-parity wave functions of the harmonic oscillator with an additional delta-function potential at the origin. Our results bring to the attention of students a non-trivial and analytical example of a modification of the usual harmonic oscillator potential, with emphasis on the modification of the boundary conditions at the origin. This problem calls the attention of the students to an inaccurate statement in quantum mechanics textbooks often found in the context of solution of the harmonic oscillator problem.Comment: 9 pages, 3 figure

Delayed mortality effects cut the malaria transmission potential of insecticide resistant mosquitoes

Malaria transmission has been substantially reduced across Africa through the distribution of long-lasting insecticidal nets (LLINs). However, the emergence of insecticide resistance within mosquito vectors risks jeopardizing the future efficacy of this control strategy. The severity of this threat is uncertain because the consequences of resistance for mosquito fitness are poorly understood: while resistant mosquitoes are no longer immediately killed upon contact with LLINs, their transmission potential may be curtailed because of longer-term fitness costs that persist beyond the first 24 h after exposure. Here, we used a Bayesian state-space model to quantify the immediate (within 24 h of exposure) and delayed (>24 h after exposure) impact of insecticides on daily survival and malaria transmission potential of moderately and highly resistant laboratory populations of the major African malaria vector Anopheles gambiae. Contact with LLINs reduced the immediate survival of moderately and highly resistant An. gambiae strains by 60–100% and 3–61%, respectively, and delayed mortality impacts occurring beyond the first 24 h after exposure further reduced their overall life spans by nearly one-half. In total, insecticide exposure was predicted to reduce the lifetime malaria transmission potential of insecticide-resistant vectors by two-thirds, with delayed effects accounting for at least one-half of this reduction. The existence of substantial, previously unreported, delayed mortality effects within highly resistant malaria vectors following exposure to insecticides does not diminish the threat of growing resistance, but posits an explanation for the apparent paradox of continued LLIN effectiveness in the presence of high insecticide resistance

Analytical study of tunneling times in flat histogram Monte Carlo

We present a model for the dynamics in energy space of multicanonical simulation methods that lends itself to a rather complete analytic characterization. The dynamics is completely determined by the density of states. In the \pm J 2D spin glass the transitions between the ground state level and the first excited one control the long time dynamics. We are able to calculate the distribution of tunneling times and relate it to the equilibration time of a starting probability distribution. In this model, and possibly in any model in which entering and exiting regions with low density of states are the slowest processes in the simulations, tunneling time can be much larger (by a factor of O(N)) than the equilibration time of the probability distribution. We find that these features also hold for the energy projection of single spin flip dynamics.Comment: 7 pages, 4 figures, published in Europhysics Letters (2005

Bolsa Floresta: um instrumento inovador para a promoção da saúde em comunidades tradicionais na Amazônia

O Programa Bolsa Floresta implementa uma série de atividades prioneiras no campo da conservação ambiental e desenvolvimento sustentável na Amazônia. Sua concepção se insere no contexto das mudanças climáticas globais e de redução do desmatamento, com especial ênfase para as comunidades tradicionais da "Amazônia profunda". Este artigo descreve o conceito e a estratégia de implementação do Programa, com uma ênfase especial para as ações de saúde. Primeiro, é apresentado o contexto no qual foi concebido. Depois, apresentam-se o conceito, a estrutura e os resultados obtidos até setembro de 2008. Na seqüência, indicam-se o diagnóstico e as ações relacionadas com saúde pública. Finalmente, abordam-se o significado histórico e as perspectivas desse Programa.The program Bolsa Floresta [Forest Conservation Grant] implements a series of pioneering activities in the area of environmental conservation and sustainable development in the Amazon. Its conception is inserted in the context of global climate change and deforestation reduction, and a special emphasis is given to the traditional communities of the "Deep Amazon". This article describes the program's concept and strategies of implementation, highlighting its health related actions. First, the context in which the program was conceived is presented. Then, the concept, structure and results achieved until September 2008 are exposed, followed by a presentation of the diagnosis and of its public health related actions. Finally, the program's historical meaning and perspectives are discussed