Phase-Locked Loop design applied to frequency-modulated atomic force microscope

The atomic force microscope (AFM) introduced the surface investigation with true atomic resolution. In the frequency modulation technique (FM-AFM) both the amplitude and the frequency of oscillation of the micro-cantilever must be kept constant even in the presence of tip-surface interaction forces. For that reason, the proper design of the Phase-Locked Loop (PLL) used in FM-AFM is vital to system performance. Here, the mathematical model of the FM-AFM control system is derived considering high order PLL In addition a method to design stable third-order Phase-Locked Loops is presented. (C) 2010 Elsevier B.V. All rights reserved.

Collagen Type I may Influence the Expression of E-Cadherin and Beta-catenin in Carcinoma Ex-pleomorphic Adenoma

Carcinoma ex-pleomorphic adenoma (CXPA) is an aggressive salivary gland malignancy, usually derived from a long-standing or a recurrent benign tumor, the pleomorphic adenoma (PA). In the context of dynamic reciprocity, changes in the composition and structure of extracellular matrix proteins and cell surface receptors have been frequently associated with dysfunctional adhesion and invasive behavior of tumor cells. It is not fully understood if these changes are involved in the conversion of PA to CXPA. In this study, different progression stages of CXPA were investigated regarding the expression of the major extracellular matrix proteins, collagen type I, and of E-cadherin and beta-catenin, the components of adherens junctions. By immunohistochemical analysis, we have demonstrated that direct contact of tumor cells with fibrillar type I collagen, particularly near the invasive front and in invasive areas prevailing small nests of CXPA cells, could be associated with reduced expression of the E-cadherin and beta-catenin adhesion molecules and with invasive behavior of epithelial; but not of CXPA with myoepithelial component. Our results also suggested that this association could depend on the organization of collagen molecules, being prevented by high-order polymeric structures. These findings could implicate the local microenvironment in the transition from the premalignant PA to invasive CXPA.

Exploring the learning potential of an artificial life simulation

CULTURE is an Artificial Life simulation that aims to provide primary school children with opportunities to become actively engaged in the high-order thinking processes of problem solving and critical thinking. A preliminary evaluation of CULTURE has found that it offers the freedom for children to take part in process-oriented learning experiences. Through providing children with opportunities to make inferences, validate results, explain discoveries and analyse situations, CULTURE encourages the development of high-order thinking skills. The evaluation found that CULTURE allows users to autonomously explore the important scientific concepts of life and living, and energy and change within a software environment that children find enjoyable and easy to use.

O administrador p??blico tipo delta para o s??culo 21

O artigo estuda um aspecto da reforma do Estado que, segundo o autor, tem sido sistematicamente negligenciado pelas atuais propostas que focalizam o modelo da administra????o gerencial. Trata-se das fun????es vitais do governo de tomar decis??es cr??ticas e adotar pol??ticas diante das mudan??as provocadas pela revolu????o global. Segundo Dror, as tarefas de alto comando (high-order tasks) de definir trajet??rias e as novas formas de governan??a exigem um ajuste significativo do governo central. Este ajuste refere-se, principalmente, ?? concep????o e ao desenvolvimento de um novo padr??o de funcion??rios do primeiro escal??o p??blico, o qual contribuiria com conhecimento e perspectivas para enfrentar as tarefas de alto comando. O autor estabelece uma tipologia para caraterizar a evolu????o do perfil do servi??o p??blico, marcando suas fases hist??ricas: a) tipo alpha (status atribu??do, fus??o de pap??is pol??ticos e administrativos); b) tipo beta (compra de cargos governamentais) e c) tipo gamma (quase profissionalismo). O novo funcion??rio s??nior, do tipo delta, se concentraria nas quest??es de ordem estrat??gica, deixando as fun????es gerenciais para servidores do tipo gamma e para os servi??os t??cnicos. Ap??s uma breve an??lise, Dror conclui que o funcionalismo p??blico de primeiro escal??o, na maioria dos pa??ses (com exce????o de alguns pa??ses do Sudeste Asi??tico), encontra-se obsoleto, com base profissional inadequada e capacidade insuficiente para lidar com escolhas cr??ticas.

Da criação de uma Ordem Profissional

O objetivo central deste estudo é a análise da perspetiva dos Assistentes Sociais sobre a necessidade/ importância da criação de uma Ordem Profissional e, consequentemente de um Código Deontológico (português) para a profissão. Privilegiou-se a investigação qualitativa, construída a partir da interpretação das narrativas das entrevistas, da pesquisa bibliografia e documental. O carácter qualitativo do trabalho concretiza-se por meio de uma lógica abdutiva, que pretende compreender a realidade através da construção dos seus atores (Blaikie, 2000). Para o efeito construímos duas dimensões de análise: a primeira refere-se à análise e compreensão da necessidade de criação de uma Ordem Profissional e a segunda dimensão integra a análise da opinião dos informantes sobre a necessidade de criação de um código deontológico português. Os resultados obtidos nesta investigação demonstram de forma unânime, a importância da criação de uma Ordem Profissional para a legitimação, representatividade e autorregulação da categoria profissional. Nas razões apontadas para a importância da Ordem surgem, quer justificações que se centram na necessidade de uniformização da prática, demonstrando uma visão mais burocrática e tecnicista da profissão, no qual os métodos se sobrepõem à relação, quer razões de legitimação e de necessidade de representação coletiva junto à classe política, relacionada com uma vertente humanista, no qual os aspetos relacionais e comportamentais devem fazer parte da prática profissional de forma a uma maior adequação dos mecanismos de intervenção no indivíduo. Nas razões apontadas para o insucesso da não criação de uma Ordem Profissional, a maioria realçou motivos internos e externos inerentes à profissão. A questão interna tem a ver com a falta de associativismo e união dos Assistentes Sociais em se mobilizarem por uma causa comum. A questão externa relaciona-se com interesses políticos, bem como a questão coletiva dos profissionais. Os princípios subjacentes a um código deontológico são os inerentes aos direitos humanos e justiça social e de atitudes associadas à profissão.

Analysis of functionally graded sandwich plate structures with piezoelectric skins, using B-spline finite strip method

Functionally graded materials are composite materials wherein the composition of the constituent phases can vary in a smooth continuous way with a gradation which is function of its spatial coordinates. This characteristic proves to be an important issue as it can minimize abrupt variations of the material properties which are usually responsible for localized high values of stresses, and simultaneously providing an effective thermal barrier in specific applications. In the present work, it is studied the static and free vibration behaviour of functionally graded sandwich plate type structures, using B-spline finite strip element models based on different shear deformation theories. The effective properties of functionally graded materials are estimated according to Mori-Tanaka homogenization scheme. These sandwich structures can also consider the existence of outer skins of piezoelectric materials, thus achieving them adaptive characteristics. The performance of the models, are illustrated through a set of test cases. (C) 2012 Elsevier Ltd. All rights reserved.

A study on the modeling of sandwich functionally graded particulate composites

Dual-phase functionally graded materials are a particular type of composite materials whose properties are tailored to vary continuously, depending on its two constituent's composition distribution, and which use is increasing on the most diverse application fields. These materials are known to provide superior thermal and mechanical performances when compared to the traditional laminated composites, exactly because of this continuous properties variation characteristic, which enables among other advantages smoother stresses distribution profile. In this paper we study the influence of different homogenization schemes, namely the schemes due to Voigt, Hashin-Shtrikman and Mod-Tanaka, which can be used to obtain bounds estimates for the material properties of particulate composite structures. To achieve this goal we also use a set of finite element models based on higher order shear deformation theories and also on first order theory. From the studies carried out, on linear static analyses and on free vibration analyses, it is shown that the bounds estimates are as important as the deformation kinematics basis assumed to analyse these types of multifunctional structures. Concerning to the homogenization schemes studied, it is shown that Mori-Tanaka and Hashin-Shtrikman estimates lead to less conservative results when compared to Voigt rule of mixtures.

A numerical analysis of generalized Boussinesq-type equation using continuos/discontinuous FEM

An improved class of Boussinesq systems of an arbitrary order using a wave surface elevation and velocity potential formulation is derived. Dissipative effects and wave generation due to a time-dependent varying seabed are included. Thus, high-order source functions are considered. For the reduction of the system order and maintenance of some dispersive characteristics of the higher-order models, an extra O(mu 2n+2) term (n ??? N) is included in the velocity potential expansion. We introduce a nonlocal continuous/discontinuous Galerkin FEM with inner penalty terms to calculate the numerical solutions of the improved fourth-order models. The discretization of the spatial variables is made using continuous P2 Lagrange elements. A predictor-corrector scheme with an initialization given by an explicit RungeKutta method is also used for the time-variable integration. Moreover, a CFL-type condition is deduced for the linear problem with a constant bathymetry. To demonstrate the applicability of the model, we considered several test cases. Improved stability is achieved.

Manobras de condução assistida para veículos submarinos subactuados

A intervenção humana no manuseamento de veículos submarinos operados remotamente (ROVs) é um requisito necessário para garantir o sucesso da missão e a integridade do equipamento. Contudo, a sua teleoperação não é fácil, pelo que a condução assistida destes veículos torna-se relevante. Esta dissertação propõe uma solução para este problema para ROVs de 3DOF (surge, heave e yaw). São propostas duas abordagens distintas – numa primeira propõe-se um sistema de controlo Image Based Visual Servoing (IBVS) tendo em vista a utilização exclusiva de uma câmara (sensor existente neste tipo de sistemas) por forma a melhorar significativamente a teleoperação de um pequeno ROV; na segunda, propõe-se um sistema de controlo cinemático para o plano horizontal do veículo e um algoritmo de uma manobra capaz de dotar o ROV de movimento lateral através de uma trajectória dente-de-serra. Demonstrou-se em cenários de operação real que o sistema proposto na primeira abordagem permite ao operador de um ROV com 3DOF executar tarefas de alguma complexidade (estabilização) apenas através de comandos de alto nível, melhorando assim drasticamente a teleoperação e qualidade de inspecção do veículo em questão. Foi também desenvolvido um simulador do ROV em MATLAB para validação e avaliação das manobras, onde o sistema proposto na segunda abordagem foi validado com sucesso.

Synthesis of new peptide derivatives that self-assemble into nanostructured hydrogels for biomedical applications

Tese de Doutoramento em Ciências (área de especialização em Química)

Multidimensional schemes for hyperbolic conservation laws on triangular meshes

Genuinely multidimensional schemes, hyperbolic systems, wave equations, Euler equations, evolution Galerkin schemes, space-time conservative methods, high order accuracy, shock solutions

Kinetic schemes for the relativistic hydrodynamics

Hyperbolic systems, non-relativistic and relativistic Euler equations, kinetic schemes, conservation laws, discontinuous solutions, high order accuracy

Impact of cannabis inhalation on driving skills in occasional smokers

Objectives: Our aim was to study the brain regions involved in a divided attention tracking task related to driving in occasional cannabis smokers. In addition we assessed the relationship between THC levels in whole blood and changes in brain activity, behavioural and psychomotor performances. Methods: Twenty-one smokers participated to two independent cross-over fMRI experiments before and after smoking cannabis and a placebo. The paradigm was based on a visuo-motor tracking task, alternating active tracking blocks with passive tracking viewing and rest condition. Half of the active tracking conditions included randomly presented traffic lights as distractors. Blood samples were taken at regular intervals to determine the time-profiles of the major cannabinoids. Their levels during the fMRI experiments were interpolated from concentrations measured by GCMS/ MS just before and after brain imaging. Results: Behavioural data, such as the discard between target and cursor, the time of correct tracking and the reaction time during traffic lights appearance showed a statistical significant impairment of subject s skills due to THC intoxication. Highest THC blood concentrations were measured soon after smoking and ranged between 28.8 and 167.9 ng/ml. These concentrations reached values of a few ng/ml during the fMRI. fMRI results pointed out that under the effect of THC, high order visual areas (V3d) and Intraparietal sulcus (IPS) showed an higher activation compared to the control condition. The opposite comparison showed a decrease of activation during the THC condition in the anterior cingulate gyrus and orbitofrontal areas. In these locations, the BOLD showed a negative correlation with the THC level. Conclusion: Acute cannabis smoking significantly impairs performances and brain activity during active tracking tasks, partly reorganizing the recruitment of brain areas of the attention network. Neural activity in the anterior cingulate might be responsible of the changes in the cognitive controls required in our divided attention task.

Adaptación y validación al español del cuestionario 4CornerSAT para la medida de la satisfacción profesional del personal médico de atención especializada.

BACKGROUND Satisfaction of physicians is a concern in the healthcare sector, and it requires a multi-dimensional questionnaire in Spanish which studies their high-order needs. The objectives of this study are to adapt the 4CornerSAT Questionnaire to measure career satisfaction of physicians and to evaluate its validity in our context. METHOD The 4CornerSAT Questionnaire was adapted into Spanish, validating it among physicians of hospitals in Andalusia, Spain. A confirmatory factor analysis (CFA) was performed to corroborate the a priori model, and it was evaluated the internal consistency and the construct validity through the Cronbach's alpha and the correlation between the scale and the global item, respectively. RESULTS The adapted questionnaire was administrated to 121 specialist physicians. The CFA corroborated the four dimensions of the questionnaire (χ2=114.64, df=94, p<0.07; χ2/df=1.22; RMSEA=0.04). The internal consistency obtained an α=0.92 and the correlation between the summed scale and the global item verified the construct validity (r=0.77; p<0.001). CONCLUSIONS The 4CornerSAT questionnaire was adapted to Spanish, identifying an adequate construct validity and internal consistency.

Spontaneous pre-stimulus fluctuations in the activity of right fronto-parietal areas influence inhibitory control performance.

Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials (ERPs), a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance. To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited [correct rejection (CR)] vs. committed [false alarms (FAs)] during an auditory spatial Go/NoGo task. We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before FAs. There was no evidence for an EEG topography occurring more frequently before FAs than before CR. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network. Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms.