968 resultados para Active Power Filter


Relevância:

20.00% 20.00%

Publicador:

Resumo:

INTRODUCTION: Aedes albopictus was first detected in Brazil in 1986. This mosquito species presents a major threat to public health because Brazilian populations have shown substantial vector competence for arboviruses such as dengue and chikungunya. METHODS: We updated the records of Ae. albopictus in several States of Brazil, focusing on areas in which its presence had been reported after 2002. RESULTS: Twenty-eight years after its arrival in Brazil, Ae. albopictus has been detected in 24 of 27 States. CONCLUSIONS: The rapid spread of this species and its high vector competence demonstrate the danger of Ae. albopictus in Brazil.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This thesis provides an alternative framework to analyze power and ethics practiced in everyday conversations, which constitute processes of organizing. Drawing upon narrative frameworks, the analyses of messages posted on an online message board demonstrate people’s imaginative capacity to create relevant stories, in respect of their precise grasp of factual understandings, contextual relevance and evaluative/moral appropriateness, by appropriating others’ words. Based on the empirical analyses, the thesis indicates that studies on power and ethics in organizations can be re-oriented towards appreciating irremediable power imbalances by offering alternative ways of member’s denoting experiences of power.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

INTRODUCTION : In this study, clinical-laboratory and epidemiological characteristics are described for a group of 700 individuals with HIV (human immunodeficiency virus)/AIDS (acquired immunodeficiency syndrome) in the ART (antiretroviral therapy) era at a teaching hospital that provides a quaternary level of care, with an emphasis on opportunistic infections (OIs), co-infections and immune profile. METHODS : A retrospective cross-sectional study of AIDS cases was conducted from 1998 to 2008 by reviewing medical records from the Base Hospital/FUNFARME (Fundação Faculdade Regional de Medicina), São José do Rio Preto, São Paulo, Brazil. RESULTS: The individuals were 14 to 75 years of age, and 458 were males. Heterosexuals accounted for 31.1% of all patients. Eighty-three percent were on ART, and 33.8% of those presented difficulties with treatment adherence. OIs were analyzed from medical records, and Pneumocystis jiroveci pneumonia was the most prevalent, regardless of the LTCD4+ (TCD4+ Lymphocytes) levels. Individuals whose viral loads were ≥10,000 showed a 90% greater chance of neurotoxoplasmosis. For P. jiroveci pneumonia, neurotoxoplasmosis, esophageal candidiasis, pulmonary tuberculosis and neurocryptococcosis, the chances of infection were higher among patients with LTCD4+ levels below 200 cells/mm3. HIV/hepatitis C virus (HCV) and HIV/hepatitis B virus (HBV) co-infections were significantly associated with death. CONCLUSIONS : OIs remain frequent in the ART era even in populations where the access to medical care is considered satisfactory.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

White Color tuning is an attractive feature that Organic Light Emitting Diodes (OLEDs) offer. Up until now, there hasn’t been any report that mix both color tuning abilities with device stability. In this work, White OLEDs (W-OLEDs) based on a single RGB blend composed of a blue emitting N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) doped with a green emitting Coumarin-153 and a red emitting 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM1) dyes were produced. The final device structure was ITO/Blend/Bathocuproine (BCP)/ Tris(8-hydroxyquinolinato)aluminium (Alq3)/Al with an emission area of 0.25 cm2. The effects of the changing in DCM1’s concentration (from 0.5% to 1% wt.) allowed a tuning in the final white color resulting in devices capable of emitting a wide range of tunes – from cool to warm – while also keeping a low device complexity and a high stabilitty. Moreover, an explanation on the optoelectrical behavior of the device is presented. The best electroluminescense (EL) points toward 160 cd/m2 of brightness and 1.1 cd/A of efficiency, both prompted to being enhanced. An Impedance Spectroscopy (IS) analysis allowed to study both the effects of BCP as a Hole Blocking Layer and as an aging probe of the device. Finally, as a proof of concept, the emission was increased 9 and 64 times proving this structure can be effectively applied for general lighting.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

AbstractINTRODUCTION: The use of the Self-Image Form (SIF) expands the identification of active leprosy cases to neighbors of index cases.METHODS: The SIF was used to screen two groups: case (neighbors of index cases of leprosy) and control (individuals residing next to houses without leprosy) group. A specialist investigated suspected leprosy cases for disease confirmation.RESULTS: New cases of leprosy were diagnosed in the case group (n = 7, 8.6%), but not the control group.CONCLUSIONS: The new surveillance strategy is inexpensive, efficient, and feasible within a primary health strategy. Future studies can help improve the use of the SIF.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cylindrical specimens of bone measuring 15 mm in diameter were obtained from the lateral cortical layer of 10 pairs of femurs and tibias. A central hole 3.2 mm in diameter was drilled in each specimen. The hole was tapped, and a 4.5 mm cortical bone screw was inserted from the outer surface. The montage was submitted to push-out testing up to a complete strip of the bone threads. The cortical thickness and rupture load were measured, and the shear stress was calculated. The results were grouped according to the bone segment from which the specimen was obtained. The results showed that bone cortex screw holding power is dependent on the bone site. Additionally, the diaphyseal cortical bone tissue is both quantitatively and qualitatively more resistant to screw extraction than the metaphyseal tissue.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Modern fully integrated transceivers architectures, require circuits with low area, low cost, low power, and high efficiency. A key block in modern transceivers is the power amplifier, which is deeply studied in this thesis. First, we study the implementation of a classical Class-A amplifier, describing the basic operation of an RF power amplifier, and analysing the influence of the real models of the reactive components in its operation. Secondly, the Class-E amplifier is deeply studied. The different types of implementations are reviewed and theoretical equations are derived and compared with simulations. There were selected four modes of operation for the Class-E amplifier, in order to perform the implementation of the output stage, and the subsequent comparison of results. This led to the selection of the mode with the best trade-off between efficiency and harmonics distortion, lower power consumption and higher output power. The optimal choice was a parallel circuit containing an inductor with a finite value. To complete the implementation of the PA in switching mode, a driver was implemented. The final block (output stage together with the driver) got 20 % total efficiency (PAE) transmitting 8 dBm output power to a 50 W load with a total harmonic distortion (THD) of 3 % and a total consumption of 28 mW. All implementations are designed using standard 130 nm CMOS technology. The operating frequency is 2.4 GHz and it was considered an 1.2 V DC power supply. The proposed circuit is intended to be used in a Bluetooth transmitter, however, it has a wider range of applications.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Modern telecommunication equipment requires components that operate in many different frequency bands and support multiple communication standards, to cope with the growing demand for higher data rate. Also, a growing number of standards are adopting the use of spectrum efficient digital modulations, such as quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM). These modulation schemes require accurate quadrature oscillators, which makes the quadrature oscillator a key block in modern radio frequency (RF) transceivers. The wide tuning range characteristics of inductorless quadrature oscillators make them natural candidates, despite their higher phase noise, in comparison with LC-oscillators. This thesis presents a detailed study of inductorless sinusoidal quadrature oscillators. Three quadrature oscillators are investigated: the active coupling RC-oscillator, the novel capacitive coupling RCoscillator, and the two-integrator oscillator. The thesis includes a detailed analysis of the Van der Pol oscillator (VDPO). This is used as a base model oscillator for the analysis of the coupled oscillators. Hence, the three oscillators are approximated by the VDPO. From the nonlinear Van der Pol equations, the oscillators’ key parameters are obtained. It is analysed first the case without component mismatches and then the case with mismatches. The research is focused on determining the impact of the components’ mismatches on the oscillator key parameters: frequency, amplitude-, and quadrature-errors. Furthermore, the minimization of the errors by adjusting the circuit parameters is addressed. A novel quadrature RC-oscillator using capacitive coupling is proposed. The advantages of using the capacitive coupling are that it is noiseless, requires a small area, and has low power dissipation. The equations of the oscillation amplitude, frequency, quadrature-error, and amplitude mismatch are derived. The theoretical results are confirmed by simulation and by measurement of two prototypes fabricated in 130 nm standard complementary metal-oxide-semiconductor (CMOS) technology. The measurements reveal that the power increase due to the coupling is marginal, leading to a figure-of-merit of -154.8 dBc/Hz. These results are consistent with the noiseless feature of this coupling and are comparable to those of the best state-of-the-art RC-oscillators, in the GHz range, but with the lowest power consumption (about 9 mW). The results for the three oscillators show that the amplitude- and the quadrature-errors are proportional to the component mismatches and inversely proportional to the coupling strength. Thus, increasing the coupling strength decreases both the amplitude- and quadrature-errors. With proper coupling strength, a quadrature error below 1° and amplitude imbalance below 1% are obtained. Furthermore, the simulations show that increasing the coupling strength reduces the phase noise. Hence, there is no trade-off between phase noise and quadrature error. In the twointegrator oscillator study, it was found that the quadrature error can be eliminated by adjusting the transconductances to compensate the capacitance mismatch. However, to obtain outputs in perfect quadrature one must allow some amplitude error.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Based on the report for the unit “Métodos Interactivos de Participação e Decisão A” (Interactive methods of participation and decision A), coordinated by Prof. Lia Maldonado Teles de Vasconcelos and Prof. Nuno Miguel Ribeiro Videira Costa. This unit was provided for the PhD Program in Technology Assessment in 2015/2016.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Modern fully integrated receiver architectures, require inductorless circuits to achieve their potential low area, low cost, and low power. The low noise amplifier (LNA), which is a key block in such receivers, is investigated in this thesis. LNAs can be either narrowband or wideband. Narrowband LNAs use inductors and have very low noise figure, but they occupy a large area and require a technology with RF options to obtain inductors with high Q. Recently, wideband LNAs with noise and distortion cancelling, with passive loads have been proposed, which can have low NF, but have high power consumption. In this thesis the main goal is to obtain a very low area, low power, and low-cost wideband LNA. First, it is investigated a balun LNA with noise and distortion cancelling with active loads to boost the gain and reduce the noise figure (NF). The circuit is based on a conventional balun LNA with noise and distortion cancellation, using the combination of a common-gate (CG) stage and common-source (CS) stage. Simulation and measurements results, with a 130 nm CMOS technology, show that the gain is enhanced by about 3 dB and the NF is reduced by at least 0.5 dB, with a negligible impact on the circuit linearity (IIP3 is about 0 dBm). The total power dissipation is only 4.8 mW, and the active area is less than 50 x 50 m2 . It is also investigated a balun LNA in which the gain is boosted by using a double feedback structure.We propose to replace the load resistors by active loads, which can be used to implement local feedback loops (in the CG and CS stages). This will boost the gain and reduce the noise figure (NF). Simulation results, with the same 130 nm CMOS technology as above, show that the gain is 24 dB and NF is less than 2.7 dB. The total power dissipation is only 5.4 mW (since no extra blocks are required), leading to a figure-of-merit (FoM) of 3.8 mW

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The recent proposals presented by EPA aimed to reduce the dependency of fossil fuels and to lower current emissions levels, hoping to gradually shift electric generation units to renewable energy sources. Actually, the Final Rule Proposal announcement day exhibited a negative Abnormal Return on Fossil Fuels but the following days had positive Abnormal Returns, mostly due to legislative change perceived by financial markets which eased up implementation periods of the proposed measures in the Final Rule when compared to the Draft Rule. Oppositely, Renewables and Solar Portfolios exhibited negative Cumulative Abnormal Returns over the period surrounding the Final Rule.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This thesis aims to develop an alternative active managed portfolio strategy based on companies‟ Fundamental and Technical Analysis and analyze its finals results. There is a big distinction between the two approaches and the main objective is to understand if it is possible to take advantage of both. With this in mind a Hybrid investment strategy for the US stock market, due to its dimension and liquidity, which was able to outperform the S&P 500 index, the benchmark, during both Bear and Bull Markets between 2000 and 2015.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Esta pesquisa foca-se na comunidade imigrante portuguesa em Macau e na comunidade imigrante nepalesa em Portugal. Analisa os usos dos média – étnicos, mainstream e transnacionais - por imigrantes durante o processo de integração: na manutenção de laços com o país de origem e na adaptação à sociedade de acolhimento, em que a língua de acolhimento assume um papel crucial. A investigação enquadra-se nos estudos de audiências e baseia-se na teoria dos Usos e Gratificações dos Média (Katz, Blumler, & Gurevitch, 1974). No que respeita à integração assenta no modelo de estratégias de aculturação de Berry & Sam (2001, 2006). Quanto à língua, assenta na teoria do poder e da prática de Bourdieu (1991), especificamente na parte relativa ao poder simbólico da língua. Quanto à metodologia, foram realizadas oito entrevistas em profundidade na comunidade nepalesa e 29 entrevistas na comunidade portuguesa. A amostra foi de conveniência e teoricamente sustentada. A seguir às entrevistas, foi feita uma análise de conteúdo individual e transversal. Esta tese pretende contribuir para o enriquecimento de linhas de investigação sobre audiências activas dos média. Poderá servir de fonte de informação para políticas relacionadas com a integração de imigrantes, nomeadamente, para reformulação de políticas relacionadas com os média e com a língua de acolhimento. No caso de empresas de comunicação, a informação obtida poderá ser útil para adaptarem melhor os seus conteúdos a este público específico.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This work is devoted to the broadband wireless transmission techniques, which are serious candidates to be implemented in future broadband wireless and cellular systems, aiming at providing high and reliable data transmission and concomitantly high mobility. In order to cope with doubly-selective channels, receiver structures based on OFDM and SC-FDE block transmission techniques, are proposed, which allow cost-effective implementations, using FFT-based signal processing. The first subject to be addressed is the impact of the number of multipath components, and the diversity order, on the asymptotic performance of OFDM and SC-FDE, in uncoded and for different channel coding schemes. The obtained results show that the number of relevant separable multipath components is a key element that influences the performance of OFDM and SC-FDE schemes. Then, the improved estimation and detection performance of OFDM-based broadcasting systems, is introduced employing SFN (Single Frequency Network) operation. An initial coarse channel is obtained with resort to low-power training sequences estimation, and an iterative receiver with joint detection and channel estimation is presented. The achieved results have shown very good performance, close to that with perfect channel estimation. The next topic is related to SFN systems, devoting special attention to time-distortion effects inherent to these networks. Typically, the SFN broadcast wireless systems employ OFDM schemes to cope with severely time-dispersive channels. However, frequency errors, due to CFO, compromises the orthogonality between subcarriers. As an alternative approach, the possibility of using SC-FDE schemes (characterized by reduced envelope fluctuations and higher robustness to carrier frequency errors) is evaluated, and a technique, employing joint CFO estimation and compensation over the severe time-distortion effects, is proposed. Finally, broadband mobile wireless systems, in which the relative motion between the transmitter and receiver induces Doppler shift which is different or each propagation path, is considered, depending on the angle of incidence of that path in relation to the direction of travel. This represents a severe impairment in wireless digital communications systems, since that multipath propagation combined with the Doppler effects, lead to drastic and unpredictable fluctuations of the envelope of the received signal, severely affecting the detection performance. The channel variations due this effect are very difficult to estimate and compensate. In this work we propose a set of SC-FDE iterative receivers implementing efficient estimation and tracking techniques. The performance results show that the proposed receivers have very good performance, even in the presence of significant Doppler spread between the different groups of multipath components.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O objetivo deste trabalho era verificar como, nos jornais e revistas, o Primeiro Modernismo tinha sido acolhido. Depois do escândalo de Orpheu e da forma agressiva como os seus colaboradores tinham sido recebidos, cabia verificar se tinha havido, ou não, uma evolução na análise da sua obra ao longo dos anos, de 1916 a 1935, tanto mais que as vidas de cada um destes tinha evoluído de forma diferenciada. As mortes prematuras de uns, a subida a postos de influência e poder, ou a longevidade de outros foram fatores que poderiam ter condicionado a evolução da crítica jornalística. Por um lado, os críticos poderiam ter alterado a sua visão face a estes criadores, podendo o tempo ter funcionado a favor destes. O que em 1915 era estranho e bizarro poderia em 1935 ser inédito e original. Por outro lado, a conjuntura política poderia condicionar não só a criação artística, mas também o seu enquadramento social. Em 1915, a guerra entre monárquicos e republicanos foi marcada pelas referências a Orpheu. Mais tarde com a ditadura militar e a ascensão do Estado Novo poderão os nossos artistas voltar a ser alvo de referências políticas. A verdade é que tal não acontece. O poder político menospreza-os, apesar de nalguns casos terem uma participação ativa nas suas fileiras. A verdade é que os autores mais importantes e significativos foram, pouco a pouco, e com o passar dos anos, integrados na sociedade literária e começaram a ser vistos como criadores a ter em conta, senão mesmo de referência. O seu aparecimento em jornais e revistas na qualidade de escritores, jornalistas, artistas plásticos ou mesmo críticos fez com que estivessem sob os holofotes da imprensa e como tal sujeitos a uma análise permanente. E esta foi-se alterando com o passar do tempo e com o reconhecimento dos mesmos. Hoje ninguém duvida do seu valor, mas entre 1915 (data da publicação de Orpheu e 1935 (ano da morte de Pessoa) todos eram vistos como loucos, jovens com alguma habilidade para a escrita, promessas do panorama literário e finalmente, em alguns casos, motivos de orgulho para o nosso património artístico. Só uma leitura dos periódicos mais relevantes permitiria estudar a receção do nosso Primeiro Modernismo. E foi esse o objetivo desta tese.