Understanding bubbly episodes

bubbles, dynamic inefficiency, economic growth, financial frictions, pyramid schemes

A narrativa cabo-verdiana, nacionalidade e nacionalismo.

Sin resume

Desenvolvimento de aplicações em perl com freeLing 3

O FreeLing é uma ferramenta para processamento de linguagem natural, em especial para análise morfossintáctica e cálculo de árvores de dependências. Embora a escolha de implementação em C++ seja relevante pela eficiência, torna complicado o desenvolvimento de pequenas ferramentas. Além disso, a interface Perl disponibilizada com o próprio FreeLing não é mais que um mapeamento directo da API C++ para Perl, o que não é o mais adequado. Este artigo apresenta as decisões de implementação do módulo Perl FL3, e discute como esta interface torna simples a escrita de pequenos processadores de linguagem natural em Perl

A firm-level analysis of differences between adopters and non-adopters of ICT

Information and Communication Technologies investments have drastically modified the competitive markets due to the impact on firm performance and productivity. This paper aims to analyse the differences between ICT adopter firms and non-adopter firms. OLS regressions and ordered logit models provide the methodological approach. From data based on a questionnaire survey to 327 Spanish firms in 2002, the empirical results indicate the essential role played by some variables in the ICT adoption. The results confirm, for example, the influence of variables such as firm size. The role of human capital and competitive strategies based on product and service quality are relevant in ICT adoption. The paper is organised as follows. First, the section 1 introduces the paper. The section 2 provides the establishment and explanation of the theoretical hypotheses. This section is followed in the section 3 by the methodology adopted in this study, including both the model and the data sources employed in the estimations. Some basic statistics and the results of the model estimations are presented and interpreted in the penultimate section, before concluding the paper with some remarks on the findings and important implications in the ICT adoption

Virtual reality substation training tool for industry workers

Performing specific tasks or operating hazardous machinery or materials requires a specialized skill set. Often this means training workers! Such task involves risks and many times the assignment of specialized personnel for teaching, what could mean delays and consequent money lost for the companies. This is where the Substation Training Tool comes in, a Virtual Reality system that with the use of two inertial sensors (hand control), will allow the control and handling of a multitude of objects, teaching new employees in a safer/controlled way for a scenario of maintenance in a substation. This research evidence that this new learning methodology works and motivates users to learn the proposed procedures. All the users felt that they had improved their skill set, a lot due to the possibility of trial/error and to the system which has short and easy to follow indications. Due to the used inertial sensors it was possible to collect data from each training session, providing more efficient final feedback for the users. The final prototype will allow EFACEC to train technicians, exploring multiple cases and avoiding all the mentioned problems that come with the traditional training methods.Executar tarefas especializadas, operar maquinaria ou materiais perigosos requer um conjunto especializado de conhecimentos. Frequentemente isto significa treinar operários! Adquirir este conhecimento envolve riscos e muitas vezes a alocação de pessoal especializado para ensinar, o que pode significar atrasos e consequentes perdas de dinheiro para as empresas. Aqui entra a ferramenta de treino em Substações, um sistema de realidade virtual que com o uso de dois sensores inerciais (controlo das mãos) permite o controlo e manuseamento dos mais diversificados objetos, ensinando assim novos funcionários de uma forma mais segura e controlada num cenário de manutenção numa sub-estação. O trabalho de investigação evidencia que esta nova técnica de ensino funciona e motiva os utilizadores a aprender os procedimentos propostos. Todos os utilizadores sentiram que melhoraram o seu conjunto de habilidades, muito pela possibilidade de tentativa/erro e pelo sistema que possui indicações curtas e fáceis de seguir. Graças à utilização dos dois sensores inerciais foi possível recolher informação de cada uma das sessões de treino, o que permite transmitir aos utilizadores no final informação mais precisa de todo o seu desempenho. A solução final (protótipo) irá permitir à EFACEC treinar técnicos, explorando múltiplos casos e evitando os já mencionados problemas que advêm do uso dos métodos tradicionais

Memory-augmented conformer for improved end-to-end long-form ASR

Conformers have recently been proposed as a promising modelling approach for automatic speech recognition (ASR), outperforming recurrent neural network-based approaches and transformers. Nevertheless, in general, the performance of these end-to-end models, especially attention-based models, is particularly degraded in the case of long utterances. To address this limitation, we propose adding a fully-differentiable memory-augmented neural network between the encoder and decoder of a conformer. This external memory can enrich the generalization for longer utterances since it allows the system to store and retrieve more information recurrently. Notably, we explore the neural Turing machine (NTM) that results in our proposed Conformer-NTM model architecture for ASR. Experimental results using Librispeech train-clean-100 and train-960 sets show that the proposed system outperforms the baseline conformer without memory for long utterances

Transimpedance amplifier for integrated SpO2 optic sensor

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresThe oxygen level in blood, usually referred as SpO2 (Saturation of hemoglobin with oxygen as measured by pulse oximetry) is an essential medical information. Measuring the oxygen level of the human blood using non- intrusive techniques is a vital achievement in modern medicine. This can be performed by processing the infrared and red light transmitted through the patient’s finger and received by a photoreceptor. Before being applied to an analog-to-digital converter (ADC), the incoming light has to be converted to a voltage and the range should be dynamically adjusted in order to use the full input range of the ADC. Since the photoreceptor generates an output current, a transimpedance amplifier (TIA) with gain control is required. The two-stage TIA proposed in this paper, uses a regulated common-gate (RCG), in the first stage, employing noise cancellation and balun operation using an additional common-source (CS) stage, while the adjustable gain is implemented in the second-stage, which is based on an intrinsically noiseless MOS parametric amplifier(MPA). This MPA operates in the discrete-time domain, thus, eliminating the need of an input sample-and-hold (S&H) block in the ADC. The proposed circuit has been designed in a 130 nm digital 1.2 V CMOS technology with a power consumption lower than 350µW

Non-minimal coupling, exponential potentials and the w<−1w<-1 regime of dark energy

Recent observations and theoretical considerations have motivated the study of models for dark energy with equation of state characterized by a parameter $w=p/\rho<-1$. Such models, however, are usually believed to be inviable due to their instabilities against classical perturbations or potentially catastrophic vacuum decays. In this paper, we show that a simple quintessential model with potential $V(\phi)=Ae^{-\sigma\phi}$ and a gravitational coupling of the form $(1+|\xi|\phi^2)R$ can exhibit, for large sets of initial conditions, asymptotic de Sitter behavior with $w<-1$ regimes. Nevertheless, the model is indeed stable at classical and quantum level.Comment: 5 pages, 4 figure