Aerosol and precipitation chemistry in a remote site in Central Amazonia: the role of biogenic contribution

International audienceA long-term (2?3 years) measurement of aerosol and precipitation chemistry was carried out in a remote site in Central Amazonia, Balbina, (1°55' S, 59°29' W, 174 m above sea level), about 200 km north of Manaus city. Aerosols were sampled using stacked filter units (SFU), which separate fine (d<2.5 ?m) and coarse mode (2.5 ?

Modeling and control of malaria dynamics in fish farming regions

In this work we propose a model that represents the relation between fish ponds, the mosquito population and the transmission of malaria. It has been observed that in the Amazonic region of Acre, in the North of Brazil, fish farming is correlated to the transmission of malaria when carried out in artificial ponds that become breeding sites. Evidence has been found indicating that cleaning the vegetation from the edges of the crop tanks helps to control the size of the mosquito population. We use our model to determine the effective contribution of the fish tanks to the epidemic. The model consists of a nonlinear system of ordinary differential equations with jumps at the cleaning time, which act as impulsive controls. We study the asymptotic behaviour of the system in function of the intensity and periodicity of the cleaning, and the value of the parameters. In particular, we state sufficient conditions under which the mosquito population is exterminated or prevails, and under which the malaria is eradicated or becomes endemic. We prove our conditions by applying results for cooperative systems with concave nonlinearities

The role of point-like topological excitations at criticality: from vortices to global monopoles

We determine the detailed thermodynamic behavior of vortices in the O(2) scalar model in 2D and of global monopoles in the O(3) model in 3D. We construct new numerical techniques, based on cluster decomposition algorithms, to analyze the point defect configurations. We find that these criteria produce results for the Kosterlitz-Thouless temperature in agreement with a topological transition between a polarizable insulator and a conductor, at which free topological charges appear in the system. For global monopoles we find no pair unbinding transition. Instead a transition to a dense state where pairs are no longer distinguishable occurs at T<Tc, without leading to long range disorder. We produce both extensive numerical evidence of this behavior as well as a semi-analytic treatment of the partition function for defects. General expectations for N=D>3 are drawn, based on the observed behavior.Comment: 14 pages, REVTEX, 13 eps figure

Numerical simulation of stochastic vortex tangles

We present the results of simulation of the chaotic dynamics of quantized vortices in the bulk of superfluid He II. Evolution of vortex lines is calculated on the base of the Biot-Savart law. The dissipative effects appeared from the interaction with the normal component, or/and from relaxation of the order parameter are taken into account. Chaotic dynamics appears in the system via a random forcing, e.i. we use the Langevin approach to the problem. In the present paper we require the correlator of the random force to satisfy the fluctuation-disspation relation, which implies that thermodynamic equilibrium should be reached. In the paper we describe the numerical methods for integration of stochastic differential equation (including a new algorithm for reconnection processes), and we present the results of calculation of some characteristics of a vortex tangle such as the total length, distribution of loops in the space of their length, and the energy spectrum.Comment: 8 pages, 5 figure

Effect of Cytisus multiflorus in the control of Type-2 Diabetes

Medicinal plants display diverse pharmacological activities with marked therapeutic effects. Type-2 diabetes (T2D) remains a major health problem among industrialized countries, therefore the investigation of formulas to prevent or attenuate the metabolic syndrome, including new therapeutic agents. Currently the interest of medicinal plants is increasing. Portuguese native flora includes several plants known for their hypoglycemic properties. The aim of this work was to study the pharmacological effect of Cytisus multiflorus, one plant from the Portuguese flora traditionally used as an ethnopharmacological agent in diabetes control

Produção de semente genética de soja na Embrapa Trigo em 2014/2015.

bitstream/item/141071/1/ID43632-2015PLDocOnline155sojaresultadosp30.pd

Numerical simulations of string networks in the Abelian-Higgs model

We present the results of a field theory simulation of networks of strings in the Abelian Higgs model. Starting from a random initial configuration we show that the resulting vortex tangle approaches a self-similar regime in which the length density of lines of zeros of $\phi$ reduces as $t^{-2}$. We demonstrate that the network loses energy directly into scalar and gauge radiation. These results support a recent claim that particle production, and not gravitational radiation, is the dominant energy loss mechanism for cosmic strings. This means that cosmic strings in Grand Unified Theories are severely constrained by high energy cosmic ray fluxes: either they are ruled out, or an implausibly small fraction of their energy ends up in quarks and leptons.Comment: 4pp RevTeX, 3 eps figures, clarifications and new results included, to be published in Phys. Rev. Let

Impact of Sewage Effluent Discharges prediction using QUAL2Kw in a sensitive protected area – Portugal

The quality of water, under the influence of the wastewater treatment plant's discharges, makes the simulation of the water parameters a key issue, broadly when considering intermittent rivers. In the case of study, the Pracana reservoir works as an example of the characterization, monitoring, and control of the impact of several, wastewater treatment plant's discharges, directly contributing to water quality. Proença-a-Nova's wastewater treatment plant contributes directly to the Pracana reservoir (Central Portugal), which is a protected field. Twelve georeferenced water samples were gathered, between the sewage discharge and downstream to the Pracana reservoir, at almost equal distances. Sampling campaigns were taken during three different periods: rainy winter (January), intermediate conditions (March) and dry season (June). The following chemical parameters were analyzed: Biochemical Oxygen Demand (BOD5), Dissolved Oxygen (DO), Dry Residue, Ptotal, Ntotal, pH, Temperature, and Microbiological Parameters. DO, BOD5 and Microbiological Parameters served as indicators, for environmental pollution evaluation. A coupled hydrodynamic and water dispersion model, QUAL2kw, was used for water's quality simulation. The results lead to conclude that the water quality is acceptable for multiple purposes, except for human consumption, mainly due to moderate to high values of BOD5.Águas do Centro Enterprise and by the Institute of Earth Sciences (ICT), under contracts UID/GEO/04683/2013 with FCT (the Portuguese Science and Technology Foundation

Slow 4He^{4}He Quenches Produce Fuzzy, Transient Vortices

We examine the Zurek scenario for the production of vortices in quenches of liquid $^{4}He$ in the light of recent experiments. Extending our previous results to later times, we argue that short wavelength thermal fluctuations make vortices poorly defined until after the transition has occurred. Further, if and when vortices appear, it is plausible that that they will decay faster than anticipated from turbulence experiments, irrespective of quench rates.Comment: 4 pages, Revtex file, no figures Apart from a more appropriate title, this paper differs from its predecessor by including temperature, as well as pressure, quenche

Defect formation and local gauge invariance

We propose a new mechanism for formation of topological defects in a U(1) model with a local gauge symmetry. This mechanism leads to definite predictions, which are qualitatively different from those of the Kibble-Zurek mechanism of global theories. We confirm these predictions in numerical simulations, and they can also be tested in superconductor experiments. We believe that the mechanism generalizes to more complicated theories.Comment: REVTeX, 4 pages, 2 figures. The explicit form of the Hamiltonian and the equations of motion added. To appear in PRL (http://prl.aps.org/