Ultrastructural and Histological Study of Oogenesis and Oocyte Degeneration in the PenshellAtrina maura(Bivalvia: Pinnidae)

The successive stages of oogenesis and the changes involved in the oocyte degeneration process in the penshell Atrina maura were examined using light and transmission electron microscopy. The ovarian maturation process is asynchronous, as oocytes at different developmental stages can be found simultaneously. Oocytes develop from oogonia and then undergo three distinct stages of oogenesis: previtellogenesis, vitellogenesis and postvitellogenesis with mature oocytes. Atrina maura displays a solitary oogenesis type, in which follicular cells become associated with oocytes from the earliest stages of development and seem to play an integral role in vitellogenesis. The cytoplasm of vitellogenic oocytes contains numerous whorls of rough endoplasmic reticulum and Golgi bodies, suggesting that auto-synthetic vitellogenesis may occur in this species. In addition, the degeneration process of postvitellogenic oocytes triggered by a seasonal increase in water temperature (> 25°C) is described.

Heating the Early Universe : Numerical Methods and Their Analysis

During the epoch when the first collapsed structures formed (6<z<50) our Universe went through an extended period of changes. Some of the radiation from the first stars and accreting black holes in those structures escaped and changed the state of the Intergalactic Medium (IGM). The era of this global phase change in which the state of the IGM was transformed from cold and neutral to warm and ionized, is called the Epoch of Reionization.In this thesis we focus on numerical methods to calculate the effects of this escaping radiation. We start by considering the performance of the cosmological radiative transfer code C2-Ray. We find that although this code efficiently and accurately solves for the changes in the ionized fractions, it can yield inaccurate results for the temperature changes. We introduce two new elements to improve the code. The first element, an adaptive time step algorithm, quickly determines an optimal time step by only considering the computational cells relevant for this determination. The second element, asynchronous evolution, allows different cells to evolve with different time steps. An important constituent of methods to calculate the effects of ionizing radiation is the transport of photons through the computational domain or ``ray-tracing''. We devise a novel ray tracing method called PYRAMID which uses a new geometry - the pyramidal geometry. This geometry shares properties with both the standard Cartesian and spherical geometries. This makes it on the one hand easy to use in conjunction with a Cartesian grid and on the other hand ideally suited to trace radiation from a radially emitting source. A time-dependent photoionization calculation not only requires tracing the path of photons but also solving the coupled set of photoionization and thermal equations. Several different solvers for these equations are in use in cosmological radiative transfer codes. We conduct a detailed and quantitative comparison of four different standard solvers in which we evaluate how their accuracy depends on the choice of the time step. This comparison shows that their performance can be characterized by two simple parameters and that the C2-Ray generally performs best.

Avaliação das capacitações de Hanseníase: enfermeiros opinião de médicos e enfermeiros das equipes de saúde da família

MORENO,Cléa Maria da Costa,ENDERS,Bertha Cruz, SIMPSON, Clélia Albino. Avaliação das capacitações de Hanseníase: enfermeiros opinião de médicos e enfermeiros das equipes de saúde da família. Revista Brasileira de Enfermagem, Brasília, v.61,n.esp.p. 671-5.2008.

Satisfação no Trabalho: o caso do Município de Condeixa-a-Nova

No âmbito da gestão de Recursos Humanos a análise da satisfação no trabalho considera-se de grande relevância, uma vez que esta variável influencia o desempenho dos trabalhadores, a sua produtividade e, consequentemente o sucesso organizacional. Neste contexto, esta dissertação teve como objectivos analisar o nível de satisfação no trabalho dos funcionários das diferentes categorias profissionais da Câmara Municipal de Condeixa-a-Nova (CMC); verificar se as varáveis socioprofissionais, nomeadamente, a idade, o sexo, o tempo de serviço, a categoria profissional, as habilitações académicas e o tipo de vínculo que têm com a autarquia estão relacionadas com a satisfação no trabalho e analisar até que ponto as diferentes dimensões da satisfação influenciam o trabalho dos funcionários da CMC. A abordagem de investigação foi quantitativa, de âmbito estatístico descritivo e análise inferencial, desenvolvida a partir da aplicação de um questionário sobre a satisfação no trabalho. A amostra é composta por 91 funcionários da CMC, o que representa 41,94% da população total. Da análise dos dados conclui-se que existem diferenças ao nível da satisfação total no trabalho entre as diferentes categorias profissionais, sendo a categoria de encarregado operacional a que apresenta uma média de satisfação total no trabalho mais elevada e as categorias de assistente operacional, técnico superior e assistente técnico as que apresentam valores médios de satisfação no trabalho mais baixos. Por outro lado, e de uma forma geral, os funcionários manifestam uma grande satisfação ao nível da dimensão liderança e uma maior insatisfação ao nível da dimensão dos factores pessoais. / Inside of the human resources management, the study of job satisfaction is considered of great importance since this variable influences the performance of employees, their productivity and consequently the organizational success. In this context, this dissertation aimed to analyze the job satisfaction level from the various professional categories of the city council of Condeixa-a-Nova (CMC), verify the relationship between socio-professional variables (age, sex, length of service, professional category, academic qualifications) and job satisfaction and analyze to what extent the different dimensions of job satisfaction influence the work of employees from CMC. The research approach was quantitative, descriptive and statistical, with a inferential analysis, developed from the application of a questionnaire about job satisfaction. The sample consists of 91 workers of CMC, which represents 41,94 % of the total population. From the data analysis, we concluded that there are differences at the level of total job satisfaction between the different professional categories. The professional category of “encarregado operacional” has a highest average of job total satisfaction and the professional categories of “assistente operacional”, “técnico superior” and “assistente técnico” have the lowest average. On the other hand, and in general, employees express a great satisfaction at the level of leadership and a lower satisfaction of the personal factors dimension.

OFDM-based schemes for next generation wireless systems

The purpose of this study is to investigate two candidate waveforms for next generation wireless systems, filtered Orthogonal Frequency Division Multiplexing (f-OFDM) and Unified Filtered Multi-Carrier (UFMC). The evaluation is done based on the power spectral density analysis of the signal and performance measurements in synchronous and asynchronous transmission. In f-OFDM we implement a soft truncated filter with length 1/3 of OFDM symbol. In UFMC we use the Dolph-Chebyshev filter, limited to the length of zero padding (ZP). The simulation results demonstrates that both waveforms have a better spectral behaviour compared with conventional OFDM. However, the induced inter-symbol interference (ISI) caused by the filter in f-OFDM, and the inter-carrier interference (ICI) induced in UFMC due to cyclic prefix (CP) reduction , should be kept under control. In addition, in a synchronous transmission case with ideal parameters, f-OFDM and UFMC appear to have similar performance with OFDM. When carrier frequency offset (CFO) is imposed in the transmission, UFMC outperforms OFDM and f-OFDM.

& she was like "O_O" : Animation of reported speech on Twitter

This study relates discourse-pragmatic aspects of the use of the quotatives say, be like, be all, and go to the question of the supposed or actual spoken-likeness of written computer-mediated communication (CMC). 1,800 tokens of reported speech, collected from Twitter, were analyzed in a “constructed dialogue” framework (Tannen, 2007). The results show that users of Twitter employ various CMC devices to animate and modally enrich reported speech, especially in speech reports with be like, be all, and go. They perform a style of communication that is reminiscent of conversational speech, even while having qualities that seem to belong uniquely to CMC.

Measuring, Modeling, and Forecasting Volatility and Correlations from High-Frequency Data

This dissertation contains four essays that all share a common purpose: developing new methodologies to exploit the potential of high-frequency data for the measurement, modeling and forecasting of financial assets volatility and correlations. The first two chapters provide useful tools for univariate applications while the last two chapters develop multivariate methodologies. In chapter 1, we introduce a new class of univariate volatility models named FloGARCH models. FloGARCH models provide a parsimonious joint model for low frequency returns and realized measures, and are sufficiently flexible to capture long memory as well as asymmetries related to leverage effects. We analyze the performances of the models in a realistic numerical study and on the basis of a data set composed of 65 equities. Using more than 10 years of high-frequency transactions, we document significant statistical gains related to the FloGARCH models in terms of in-sample fit, out-of-sample fit and forecasting accuracy compared to classical and Realized GARCH models. In chapter 2, using 12 years of high-frequency transactions for 55 U.S. stocks, we argue that combining low-frequency exogenous economic indicators with high-frequency financial data improves the ability of conditionally heteroskedastic models to forecast the volatility of returns, their full multi-step ahead conditional distribution and the multi-period Value-at-Risk. Using a refined version of the Realized LGARCH model allowing for time-varying intercept and implemented with realized kernels, we document that nominal corporate profits and term spreads have strong long-run predictive ability and generate accurate risk measures forecasts over long-horizon. The results are based on several loss functions and tests, including the Model Confidence Set. Chapter 3 is a joint work with David Veredas. We study the class of disentangled realized estimators for the integrated covariance matrix of Brownian semimartingales with finite activity jumps. These estimators separate correlations and volatilities. We analyze different combinations of quantile- and median-based realized volatilities, and four estimators of realized correlations with three synchronization schemes. Their finite sample properties are studied under four data generating processes, in presence, or not, of microstructure noise, and under synchronous and asynchronous trading. The main finding is that the pre-averaged version of disentangled estimators based on Gaussian ranks (for the correlations) and median deviations (for the volatilities) provide a precise, computationally efficient, and easy alternative to measure integrated covariances on the basis of noisy and asynchronous prices. Along these lines, a minimum variance portfolio application shows the superiority of this disentangled realized estimator in terms of numerous performance metrics. Chapter 4 is co-authored with Niels S. Hansen, Asger Lunde and Kasper V. Olesen, all affiliated with CREATES at Aarhus University. We propose to use the Realized Beta GARCH model to exploit the potential of high-frequency data in commodity markets. The model produces high quality forecasts of pairwise correlations between commodities which can be used to construct a composite covariance matrix. We evaluate the quality of this matrix in a portfolio context and compare it to models used in the industry. We demonstrate significant economic gains in a realistic setting including short selling constraints and transaction costs.

Avaliação das capacitações de Hanseníase: enfermeiros opinião de médicos e enfermeiros das equipes de saúde da família

MORENO,Cléa Maria da Costa,ENDERS,Bertha Cruz, SIMPSON, Clélia Albino. Avaliação das capacitações de Hanseníase: enfermeiros opinião de médicos e enfermeiros das equipes de saúde da família. Revista Brasileira de Enfermagem, Brasília, v.61,n.esp.p. 671-5.2008.

Comparative performance analysis of drives for induction motors

The asynchronous polyphase induction motor has been the motor of choice in industrial settings for about the past half century because power electronics can be used to control its output behavior. Before that, the dc motor was widely used because of its easy speed and torque controllability. The two main reasons why this might be are its ruggedness and low cost. The induction motor is a rugged machine because it is brushless and has fewer internal parts that need maintenance or replacement. This makes it low cost in comparison to other motors, such as the dc motor. Because of these facts, the induction motor and drive system have been gaining market share in industry and even in alternative applications such as hybrid electric vehicles and electric vehicles. The subject of this thesis is to ascertain various control algorithms’ advantages and disadvantages and give recommendations for their use under certain conditions and in distinct applications. Four drives will be compared as fairly as possible by comparing their parameter sensitivities, dynamic responses, and steady-state errors. Different switching techniques are used to show that the motor drive is separate from the switching scheme; changing the switching scheme produces entirely different responses for each motor drive.

Signposts in the sand: Key issues for e-moderators

E-learning is a vision that has sparked a wide-ranging enthusiasm for moderators, course designers and learners. Asynchronous conferencing is currently central to this vision. Some educators assume that supporting learners who use this medium is the same as supporting them in the classroom. However, this is not the case. This paper outlines the current research into providing signposts that enable us to improve the training and support offered to new e-moderators and e-course designers. It suggests a classification of roles and tasks that together with an e-course framework will help to maximize the benefits of e-learning and enable all participants to migrate successfully to the new environment.

Evaluating Risks of Dam-Reservoir Systems Using Efficient Importance Sampling

The occurrence frequency of failure events serve as critical indexes representing the safety status of dam-reservoir systems. Although overtopping is the most common failure mode with significant consequences, this type of event, in most cases, has a small probability. Estimation of such rare event risks for dam-reservoir systems with crude Monte Carlo (CMC) simulation techniques requires a prohibitively large number of trials, where significant computational resources are required to reach the satisfied estimation results. Otherwise, estimation of the disturbances would not be accurate enough. In order to reduce the computation expenses and improve the risk estimation efficiency, an importance sampling (IS) based simulation approach is proposed in this dissertation to address the overtopping risks of dam-reservoir systems. Deliverables of this study mainly include the following five aspects: 1) the reservoir inflow hydrograph model; 2) the dam-reservoir system operation model; 3) the CMC simulation framework; 4) the IS-based Monte Carlo (ISMC) simulation framework; and 5) the overtopping risk estimation comparison of both CMC and ISMC simulation. In a broader sense, this study meets the following three expectations: 1) to address the natural stochastic characteristics of the dam-reservoir system, such as the reservoir inflow rate; 2) to build up the fundamental CMC and ISMC simulation frameworks of the dam-reservoir system in order to estimate the overtopping risks; and 3) to compare the simulation results and the computational performance in order to demonstrate the ISMC simulation advantages. The estimation results of overtopping probability could be used to guide the future dam safety investigations and studies, and to supplement the conventional analyses in decision making on the dam-reservoir system improvements. At the same time, the proposed methodology of ISMC simulation is reasonably robust and proved to improve the overtopping risk estimation. The more accurate estimation, the smaller variance, and the reduced CPU time, expand the application of Monte Carlo (MC) technique on evaluating rare event risks for infrastructures.

Asynchronus design for improved EMC behavior of ICs

International audience

Conditional moment closure for chemical reactions in laminar chaotic flows

We implement conditional moment closure (CMC) for simulation of chemical reactions in laminar chaotic flows. The CMC approach predicts the expected concentration of reactive species, conditional upon the concentration of a corresponding nonreactive scalar. Closure is obtained by neglecting the difference between the local concentration of the reactive scalar and its conditional average. We first use a Monte Carlo method to calculate the evolution of the moments of a conserved scalar; we then reconstruct the corresponding probability density function and dissipation rate. Finally, the concentrations of the reactive scalars are determined. The results are compared (and show excellent agreement) with full numerical simulations of the reaction processes in a chaotic laminar flow. This is a preprint of an article published in AlChE Journal copyright (2007) American Institute of Chemical Engineers: http://www3.interscience.wiley.com/

Réseau calculant asynchrone dédié à la segmentation d'images

National audience

Metabolite profiling of somatic embryos of Cyclamen persicum in comparison to zygotic embryos, endosperm, and testa

Somatic embryogenesis has been shown to be an efficient in vitro plant regeneration system for many crops such as the important ornamental plant Cyclamen persicum, for which this regeneration pathway of somatic embryogenesis is of interest for the vegetative propagation of parental lines as well as elite plants. However, somatic embryogenesis is not commercially used in many crops due to several unsolved problems, such as malformations, asynchronous development, deficiencies in maturation and germination of somatic embryos. In contrast, zygotic embryos in seeds develop and germinate without abnormalities in most cases. Instead of time-consuming and labor-intensive experiments involving tests of different in vitro culture conditions and plant growth regulator supplements, we follow a more directed approach. Zygotic embryos served as a reference and were compared to somatic embryos in metabolomic analyses allowing the future optimization of the in vitro system. The aims of this study were to detect differences in the metabolite profiles of torpedo stage somatic and zygotic embryos of C. persicum. Moreover, major metabolites in endosperm and testa were identified and quantified. Two sets of extracts of two to four biological replicates each were analyzed. In total 52 metabolites were identified and quantified in the different tissues. One of the most significant differences between somatic and zygotic embryos was that the proline concentration in the zygotic embryos was about 40 times higher than that found in somatic embryos. Epicatechin, a scavenger for reactive oxygen species, was found in highest abundance in the testa. Sucrose, the most abundant metabolite was detected in significantly higher concentrations in zygotic embryos. Also, a yet unknown trisaccharide, was significantly enriched in zygotic embryos.