Fluorescence spectrum of a two-level atom driven by a multiple modulated field

We investigate the fluorescence spectrum of a two-level atom driven by a multiple amplitude-modulated field. The driving held is modeled as a polychromatic field composed of a strong central (resonant) component and a large number of symmetrically detuned sideband fields displaced from the central component by integer multiples of a constant detuning. Spectra obtained here differ qualitatively from those observed for a single pair of modulating fields [B. Blind, P.R. Fontana, and P. Thomann, J. Phys. B 13, 2717 (1980)]. In the case of a small number of the modulating fields, a multipeaked spectrum is obtained with the spectral features located at fixed frequencies that are independent of the number of modulating fields and their Rabi frequencies. As the number of the modulating fields increases, the spectrum ultimately evolves to the well-known Mellow triplet with the sidebands shifted from the central component by an effective Rabi frequency whose magnitude depends on the initial relative phases of the components of the driving held. For equal relative phases, the effective Rabi frequency of the driving field can be reduced to zero resulting in the disappearance of fluorescence spectrum, i.e., the atom can stop interacting with the field. When the central component and the modulating fields are 180 degrees out of phase, the spectrum retains its triplet structure with the sidebands located at frequencies equal to the sum of the Rabi frequencies of the component of the driving field. Moreover, we shaw that the frequency of spontaneous emission can be controlled and switched from one frequency to another when the Rabi frequency or initial phase of the modulating fields are varied.

Tillage and traffic effects on runoff

Traffic and tillage effects on runoff and crop performance on a heavy clay soil were investigated over a period of 4 years. Tillage treatments and the cropping program were representative of broadacre grain production practice in northern Australia, and a split-plot design used to isolate traffic effects. Treatments subject to zero, minimum, and stubble mulch tillage each comprised pairs of 90-m 2 plots, from which runoff was recorded. A 3-m-wide controlled traffic system allowed one of each pair to be maintained as a non-wheeled plot, while the total surface area of the other received a single annual wheeling treatment from a working 100-kW tractor. Rainfall/runoff hydrographs demonstrate that wheeling produced a large and consistent increase in runoff, whereas tillage produced a smaller increase. Treatment effects were greater on dry soil, but were still maintained in large and intense rainfall events on wet soil. Mean annual runoff from wheeled plots was 63 mm (44%) greater than that from controlled traffic plots, whereas runoff from stubble mulch tillage plots was 38 mm (24%) greater than that from zero tillage plots. Traffic and tillage effects appeared to be cumulative, so the mean annual runoff from wheeled stubble mulch tilled plots, representing conventional cropping practice, was more than 100 mm greater than that from controlled traffic zero tilled plots, representing best practice. This increased infiltration was reflected in an increased yield of 16% compared with wheeled stubble mulch. Minimum tilled plots demonstrated a characteristic midway between that of zero and stubble mulch tillage. The results confirm that unnecessary energy dissipation in the soil during the traction process that normally accompanies tillage has a major negative effect on infiltration and crop productivity. Controlled traffic farming systems appear to be the only practicable solution to this problem.

A uniform white-noise model for fixed-point roundoff errors in digital systems

Fixed-point roundoff noise in digital implementation of linear systems arises due to overflow, quantization of coefficients and input signals, and arithmetical errors. In uniform white-noise models, the last two types of roundoff errors are regarded as uniformly distributed independent random vectors on cubes of suitable size. For input signal quantization errors, the heuristic model is justified by a quantization theorem, which cannot be directly applied to arithmetical errors due to the complicated input-dependence of errors. The complete uniform white-noise model is shown to be valid in the sense of weak convergence of probabilistic measures as the lattice step tends to zero if the matrices of realization of the system in the state space satisfy certain nonresonance conditions and the finite-dimensional distributions of the input signal are absolutely continuous.

Alguns teoremas limites para sequ��ncias de vari��veis aleat��rias

O Teorema Central do Limite e a Lei dos Grandes N��meros est��o entre os mais importantes resultados da teoria da probabilidade. O primeiro deles busca condi����es sob as quais [f��rmula] converge em distribui����o para a distribui����o normal com par��metros 0 e 1, quando n tende ao infinito, onde Sn �� a soma de n vari��veis aleat��rias independentes. Ao mesmo tempo, o segundo estabelece condi����es para que [f��rmula] convirja a zero, ou equivalentemente, para que [f��rmula] convirja para a esperan��a das vari��veis aleat��rias, caso elas sejam identicamente distribu��das. Em ambos os casos as sequ��ncias abordadas s��o do tipo [f��rmula], onde [f��rmula] e [f��rmula] s��o constantes reais. Caracterizar os poss��veis limites de tais sequ��ncias �� um dos objetivos dessa disserta����o, j�� que elas n��o convergem exclusivamente para uma vari��vel aleat��ria degenerada ou com distribui����o normal como na Lei dos Grandes N��meros e no Teorema Central do Limite, respectivamente. Assim, somos levados naturalmente ao estudo das distribui����es infinitamente divis��veis e est��veis, e os respectivos teoremas limites, e este vem a ser o objetivo principal desta disserta����o. Para as demonstra����es dos teoremas utiliza-se como estrat��gia principal a aplica����o do m��todo de Lyapunov, o qual consiste na an��lise da converg��ncia da sequ��ncia de fun����es caracter��sticas correspondentes ��s vari��veis aleat��rias. Nesse sentido, faremos tamb��m uma abordagem detalhada de tais fun����es neste trabalho.

Colour filtering in a-SiC : H based p-i-n-p-i-n cells: A trade-off between bias polarity and absorption regions

A large area colour imager optically addressed is presented. The colour imager consists of a thin wide band gap p-i-n a-SiC:H filtering element deposited on the top of a thick large area a-SiC:H(-p)/a-Si:H(-i)/a-SiC:H(-n) image sensor, which reveals itself an intrinsic colour filter. In order to tune the external applied voltage for full colour discrimination the photocurrent generated by a modulated red light is measured under different optical and electrical bias. Results reveal that the integrated device behaves itself as an imager and a filter giving information not only on the position where the optical image is absorbed but also on it wavelength and intensity. The amplitude and sign of the image signals are electrically tuneable. In a wide range of incident fluxes and under reverse bias, the red and blue image signals are opposite in sign and the green signal is suppressed allowing blue and red colour recognition. The green information is obtained under forward bias, where the blue signal goes down to zero and the red and green remain constant. Combining the information obtained at this two applied voltages a RGB colour image picture can be acquired without the need of the usual colour filters or pixel architecture. A numerical simulation supports the colour filter analysis.

The condensation and ordering of models of empty liquids

We consider a simple model consisting of particles with four bonding sites ("patches"), two of type A and two of type B, on the square lattice, and investigate its global phase behavior by simulations and theory. We set the interaction between B patches to zero and calculate the phase diagram as the ratio between the AB and the AA interactions, epsilon(AB)*, varies. In line with previous work, on three-dimensional off-lattice models, we show that the liquid-vapor phase diagram exhibits a re-entrant or "pinched" shape for the same range of epsilon(AB)*, suggesting that the ratio of the energy scales - and the corresponding empty fluid regime - is independent of the dimensionality of the system and of the lattice structure. In addition, the model exhibits an order-disorder transition that is ferromagnetic in the re-entrant regime. The use of low-dimensional lattice models allows the simulation of sufficiently large systems to establish the nature of the liquid-vapor critical points and to describe the structure of the liquid phase in the empty fluid regime, where the size of the "voids" increases as the temperature decreases. We have found that the liquid-vapor critical point is in the 2D Ising universality class, with a scaling region that decreases rapidly as the temperature decreases. The results of simulations and theoretical analysis suggest that the line of order-disorder transitions intersects the condensation line at a multi-critical point at zero temperature and density, for patchy particle models with a re-entrant, empty fluid, regime. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3657406]

Symbolic Knowledge Extraction from Trained Neural Networks Governed by Lukasiewicz Logics

This work describes a methodology to extract symbolic rules from trained neural networks. In our approach, patterns on the network are codified using formulas on a Lukasiewicz logic. For this we take advantage of the fact that every connective in this multi-valued logic can be evaluated by a neuron in an artificial network having, by activation function the identity truncated to zero and one. This fact simplifies symbolic rule extraction and allows the easy injection of formulas into a network architecture. We trained this type of neural network using a back-propagation algorithm based on Levenderg-Marquardt algorithm, where in each learning iteration, we restricted the knowledge dissemination in the network structure. This makes the descriptive power of produced neural networks similar to the descriptive power of Lukasiewicz logic language, minimizing the information loss on the translation between connectionist and symbolic structures. To avoid redundance on the generated network, the method simplifies them in a pruning phase, using the "Optimal Brain Surgeon" algorithm. We tested this method on the task of finding the formula used on the generation of a given truth table. For real data tests, we selected the Mushrooms data set, available on the UCI Machine Learning Repository.

Infestation of Aedes aegypti estimated by oviposition traps in Brazil

OBJECTIVE: To assess infestation levels of Aedes aegypti using the oviposition trap (ovitrap) method and to compare these results with data obtained with the use of indices traditionally applied in public programs aimed at fighting this vector. METHODS: Nine sentinel areas in Northeastern, Brazil, were assessed and infestation levels were measured for a nine-month period. Egg density and container indices were estimated and compared with previous results found using the house index and Breteau index. RESULTS: The results indicated that the area studied was infested with this vector during the entire study period and that the infestation was widespread in all areas. Different results were found with the different indices studied. There were areas in which the house index and the Breteau index were negative or close to zero, whereas the container index for the same area was 11% and the egg density index was 8.3%. CONCLUSIONS: The container and egg density indices allow better assessment of infestation rates in a city than the conventionally used indices (house index and Breteau index). At lower operational costs and easier standardization, these indices can be applied as a measurement tool for assessing infestation rates during entomological surveillance in programs to fight Aedes aegypti.

Numerical experiments with a modified regularization scheme for mathematical programs with complementarity constraints

On this paper we present a modified regularization scheme for Mathematical Programs with Complementarity Constraints. In the regularized formulations the complementarity condition is replaced by a constraint involving a positive parameter that can be decreased to zero. In our approach both the complementarity condition and the nonnegativity constraints are relaxed. An iterative algorithm is implemented in MATLAB language and a set of AMPL problems from MacMPEC database were tested.

O efeito da inibi����o dos m��sculos Sub-occipitais na dor cervical e de cabe��a e nas amplitudes articulares

Caso cl��nico: Este estudo observacional descritivo - tipo estudo de caso, tem como amostra uma senhora de 36 anos com dor cervical superior esquerda e de cabe��a. Ap��s uma avalia����o inicial, a paciente foi submetida a tr��s aplica����es da t��cnica de inibi����o dos m��sculos sub-occipitais durante uma semana em dias alternados, com o objetivo de quantificar o seu efeito nas amplitudes articulares cervicais, na dor e na funcionalidade. Para o efeito foram utilizados como instrumentos o Cervical Range of Motion Instrument, a Escala Visual Anal��gica e o ��ndice de Incapacidade relacionada com a Cervical. A paciente foi reavaliada em tr��s momentos distintos (1��� ap��s a primeira aplica����o da t��cnica e oito e quinze dias depois). O resultado imediato da t��cnica foi de um ligeiro aumento nalgumas amplitudes articulares mas noutras ocorreu uma diminui����o dos seus valores. Ap��s 8 e 15 dias houve um aumento de todas as amplitudes articulares cervicais �� exce����o da inclina����o e da rota����o esquerda que diminu��ram ligeiramente em rela����o �� avalia����o inicial e da extens��o que manteve a mesma amplitude articular. Quanto �� sintomatologia dolorosa foi eliminada por completo e a pontua����o da funcionalidade passou de 18 para zero logo ap��s a primeira interven����o. A aplica����o desta t��cnica, nesta paciente, aumentou as amplitudes articulares cervicais, eliminou a dor cervical e de cabe��a e melhorou a funcionalidade.

Avalia����o da dose efetiva recebida pelo t��cnico de radiologia no contexto ocupacional

Introdu����o ��� As fun����es a desempenhar pelos t��cnicos de radiologia (TR) envolvem exposi����o ocupacional ��s radia����es ionizantes, podendo acarretar potenciais efeitos biol��gicos. Metodologia ��� De modo a avaliar a dose efetiva recebida pelo TR nos diferentes m��todos de estudo radiol��gico em que este trabalha, procedeu-se �� realiza����o de um estudo explorat��rio-descritivo. Efetuaram-se medi����es com dos��metros termoluminescentes em cinco val��ncias radiol��gicas e foram aplicados question��rios aos TR para determinar o tempo total de trabalho, bem como as medidas gerais de prote����o radiol��gica utilizadas durante o per��odo de medi����es. Resultados ��� Verificou-se que as doses efetivas, calculadas por hora, foram mais elevadas na val��ncia de radiologia de interven����o, com os dados obtidos sobre a prote����o plumb��nea, sendo que a val��ncia com menor dose efetiva calculada por hora foi a de mamografia, que apresentou um valor de medi����o igual a zero. Conclus��es ��� Com o presente estudo conclui-se que existem diferen��as de dose efetiva recebida de acordo com a fun����o desempenhada pelo TR. Pela extrapola����o dos valores calculados para doses efetivas anuais, verificou-se que os valores correspondentes a cada val��ncia se encontram muito abaixo do limite anual legal de 20mSv.

Performance assessment of a wind energy conversion system using a hierarchical controller structure

This paper deals with a hierarchical structure composed by an event-based supervisor in a higher level and two distinct proportional integral (PI) controllers in a lower level. The controllers are applied to a variable speed wind energy conversion system with doubly-fed induction generator, namely, the fuzzy PI control and the fractional-order PI control. The event-based supervisor analyses the operation state of the wind energy conversion system among four possible operational states: park, start-up, generating or brake and sends the operation state to the controllers in the lower level. In start-up state, the controllers only act on electric torque while pitch angle is equal to zero. In generating state, the controllers must act on the pitch angle of the blades in order to maintain the electric power around the nominal value, thus ensuring that the safety conditions required for integration in the electric grid are met. Comparisons between fuzzy PI and fractional-order PI pitch controllers applied to a wind turbine benchmark model are given and simulation results by Matlab/Simulink are shown. From the results regarding the closed loop point of view, fuzzy PI controller allows a smoother response at the expense of larger number of variations of the pitch angle, implying frequent switches between operational states. On the other hand fractional-order PI controller allows an oscillatory response with less control effort, reducing switches between operational states. (C) 2015 Elsevier Ltd. All rights reserved.

The effect of temperature on mobility of Angiostrongylus costaricensis third stage larvae

Third stage larvae (L3) from Angiostrongylus costaricensis were incubated in water at room temperature and at 5 <FONT FACE="Symbol">��</font> C and their mobility was assessed daily for 17 days. Viability was associated with the mobility and position of the L3, and it was confirmed by inoculation per os in albino mice. The number of actively moving L3 sharply decreased within 3 to 4 days, but there were some infective L3 at end of observation. A mathematical model estimated 80 days as the time required to reduce the probability of infective larvae to zero. This data does not support the proposition of refrigerating vegetables and raw food as an isolated procedure for prophylaxis of human abdominal angiostrongylosis infection.

Avalia����o de funcionamento de duas esta����es de tratamento de ��guas residuais do interior de Vila Nova de Gaia

Esta disserta����o descreve o trabalho desenvolvido ao longo de um ano e um m��s desde a pesquisa te��rica at�� �� pr��tica experimental no ��mbito da unidade curricular de Disserta����o/est��gio do Mestrado em Engenharia Qu��mica, no ramo Tecnologias em Prote����o Ambiental. O tema desta disserta����o consiste na avalia����o do funcionamento de duas esta����es de tratamento de ��guas residuais (ETAR) do interior do munic��pio de Vila Nova de Gaia no que diz respeito ao poss��vel aumento da resist��ncia a antibi��ticos na ETAR de Febros e na ETAR de Lever. Os testes de sensibilidade a antibi��ticos (TSA) foram executados para ambas as ETAR, sendo as amostras de ��gua recolhidas na entrada e na sa��da dos reatores biol��gicos (tratamento secund��rio). Al��m disso, foram realizados testes de avalia����o da efici��ncia de desinfe����o por radia����o ultravioleta (UV) relativamente �� Escherichia coli (E. coli) na ETAR de Lever. Os antibi��ticos selecionados para a realiza����o deste trabalho foram a Eritromicina, a Azitromicina, a Claritromicina, a Ofloxacina, a Ciprofloxacina, o Sulfametoxazol, o Trimetoprim e o Metronidazol. Esta sele����o baseou-se no facto de estes serem alguns dos antibi��ticos mais consumidos e mais persistentes no meio ambiente. A bact��ria E. coli (isolada a partir de amostras das ��guas residuais estudadas) foi escolhida para a realiza����o deste estudo uma vez que est�� sempre presente nas ��guas residuais dom��sticas e est�� associada a fen��menos de multirresist��ncia a antibi��ticos. Os testes de TSA foram realizados seguindo a metodologia de difus��o por discos. No per��odo do estudo (Mar��o a Junho de 2015) identificaram-se situa����es quer de aumento de resist��ncia quer de aumento de sensibilidade aos antibi��ticos testados. As situa����es mais graves de aumento de resist��ncia, a que corresponderam a halos nulos, verificaram-se para os antibi��ticos Claritromicina, Trimetoprim e Metronidazol, ocorrendo com maior frequ��ncia para os dois ��ltimos, que ali��s s��o f��rmacos que s��o administrados em simult��neo. Os per��odos mais problem��ticos em termos de aumento das resist��ncias foram ligeiramente diferentes nas duas ETAR. No caso da ETAR de Febros correspondeu ao m��s Abril e na ETAR de Lever ocorreu entre o final de Abril e o in��cio de Maio. Considera-se que estes per��odos poder��o coincidir com um aumento do consumo destes f��rmacos devido �� sua utiliza����o no combate a infe����es respirat��rias muito comuns nesta altura do ano. N��o se observou qualquer sensibilidade da E. coli para o Metronidazol porque �� um antibi��tico com indica����o para algumas bact��rias anaer��bias, fungos e giardia, e que �� partida n��o tem capacidade para eliminar a E. coli. A efici��ncia da desinfe����o na ETAR de Lever relativamente �� remo����o de E. coli foi satisfat��ria. Sendo de salientar a import��ncia da manuten����o, no que se refere �� identifica����o de poss��veis avarias nas l��mpadas e correspondente limpeza. Os resultados deste trabalho provam a exist��ncia de estirpes da bact��ria E. coli resistentes a alguns dos antibi��ticos estudados, o que refor��a a import��ncia da desinfe����o no tratamento de ��guas residuais dom��sticas.

Aumento das taxas moderadoras nas urg��ncias hospitalares : que impacto sobre a procura?

RESUMO - Objetivo: Quantificar a varia����o da procura ocorrida no Servi��o de Urg��ncia Hospitalar (SUH) de um hospital na zona de Lisboa face ao aumento de pre��o da taxa moderadora da urg��ncia em janeiro de 2012. Metodologia: O presente trabalho recorre �� an��lise de micro dados sobre a utiliza����o do Servi��o de Urg��ncia do Hospital Garcia de Orta (HGO) em dois per��odos: 1 de janeiro de 2011 a 30 de junho de 2011 e 1 de janeiro de 2012 a 30 de junho de 2012. A amostra �� constitu��da por 156.654 idas ao SUH do HGO. Aferiu-se ainda a elasticidade da procura face ao pre��o por sexo, escal��o et��rio, proveni��ncia, local e causa da admiss��o e destino dos utentes. Resultados: Existiram 80.344 epis��dios de urg��ncia em 2011 e 76.310 em 2012 (-5%).Em rela����o aos utentes n��o isentos, houve uma redu����o de 12% no total de epis��dios de urg��ncia (26.168 em 2011 e 23.037 em 2012). O pre��o da urg��ncia aumentou 108% para os indiv��duos n��o isentos (���9,6 para ���20). Os valores obtidos para a elasticidade da procura face ao pre��o s��o pr��ximos de zero para o total da procura bem como para as restantes vari��veis. Conclus��es: Conclui-se que a procura de cuidados de urg��ncia �� inel��stica face ao aumento do pre��o no hospital analisado. Embora se tenha verificado uma redu����o dos cuidados procurados (12%), esta foi muito inferior ao aumento ocorrido no pre��o (108%).