Gene Expression in Brain: A Window on Ethanol Dependence, Neuroadaptation, and Preference

This article represents the proceedings of a symposium at the 2002 joint RSA/ISBRA Conference in San Francisco, California. The organizer was Paula L. Hoffman and the co-chairs were Paula L. Hoffman and Michael Miles. The presentations were (1) Introduction and overview of the use of DNA microarrays, by Michael Miles; (2) DNA microarray analysis of gene expression in brains of P and NP rats, by Howard J. Edenberg; (3) Gene expression patterns in brain regions of AA and ANA rats, by Wolfgang Sommer; (4) Patterns of gene expression in brains of selected lines of mice that differ in ethanol tolerance, by Boris Tabakoff; (5) Gene expression profiling related to initial sensitivity and tolerance in gamma-protein kinase C mutants, by Jeanne Wehner; and (6) Gene expression patterns in human alcoholic brain: from microarrays to protein profiles, by Joanne Lewohl.

Effect of cold wire inclination on temperature fluctuation measurements in a heated jet

Hot-wire anemometers at low operating currents are used as fast response resistance thermometers for the study of heated turbulent flows. Simultaneous measurement of temperature and velocity is generally performed with multi-wire arrays. In order to give good spatial resolution a new layout has been tested which uses an inclined temperature wire positioned parallel to the nearest inclined velocity wire. This leads to an asymmetric wire arrangement relative to the mean flow direction. As expected, a reduction in thermal interference from the velocity wires results when compared with an array containing a temperature wire placed normal to the flow. However, measurement of higher order moments of fluctuating quantities in an axisymmetric jet shows considerable distortion of radial distributions which is traced to alteration of the temperature field sensed by the temperature wire. When inclined velocity sensitive wires contain a temperature component, the latter may be affected by the same phenomenon.

Numerical study of hydrogenic effective mass theory for an impurity P donor in Si in the presence of an electric field and interfaces

In this paper we examine the effects of varying several experimental parameters in the Kane quantum computer architecture: A-gate voltage, the qubit depth below the silicon oxide barrier, and the back gate depth to explore how these variables affect the electron density of the donor electron. In particular, we calculate the resonance frequency of the donor nuclei as a function of these parameters. To do this we calculated the donor electron wave function variationally using an effective-mass Hamiltonian approach, using a basis of deformed hydrogenic orbitals. This approach was then extended to include the electric-field Hamiltonian and the silicon host geometry. We found that the phosphorous donor electron wave function was very sensitive to all the experimental variables studied in our work, and thus to optimize the operation of these devices it is necessary to control all parameters varied in this paper.

Modeling diffraction in free-space optical interconnects by the mode expansion method

Free-space optical interconnects (FSOIs), made up of dense arrays of vertical-cavity surface-emitting lasers, photodetectors and microlenses can be used for implementing high-speed and high-density communication links, and hence replace the inferior electrical interconnects. A major concern in the design of FSOIs is minimization of the optical channel cross talk arising from laser beam diffraction. In this article we introduce modifications to the mode expansion method of Tanaka et al. [IEEE Trans. Microwave Theory Tech. MTT-20, 749 (1972)] to make it an efficient tool for modelling and design of FSOIs in the presence of diffraction. We demonstrate that our modified mode expansion method has accuracy similar to the exact solution of the Huygens-Kirchhoff diffraction integral in cases of both weak and strong beam clipping, and that it is much more accurate than the existing approximations. The strength of the method is twofold: first, it is applicable in the region of pronounced diffraction (strong beam clipping) where all other approximations fail and, second, unlike the exact-solution method, it can be efficiently used for modelling diffraction on multiple apertures. These features make the mode expansion method useful for design and optimization of free-space architectures containing multiple optical elements inclusive of optical interconnects and optical clock distribution systems. (C) 2003 Optical Society of America.

The effect of volition on the stability of bimanual coordination

The authors investigated how the intention to passively perform a behavior and the intention to persist with a behavior impact upon the spatial and temporal properties of bimanual coordination. Participants (N = 30) were asked to perform a bimanual coordination task that demanded the continuous rhythmic extension-flexion of the wrists. The frequency of movement was scaled by an auditory metronome beat from 1.5 Hz, increasing to 3.25 Hz in .25-Hz increments. The task was further defined by the requirement that the movements be performed initially in a prescribed pattern of coordination (in-phase or antiphase) while the participants assumed one of two different intentional states: stay with the prescribed pattern should it become unstable or do not intervene should the pattern begin to change. Transitions away from the initially prescribed pattern were observed only in trials conducted in the antiphase mode of coordination. The time at which the antiphase pattern of coordination became unstable was not found to be influenced by the intentional state. In addition, the do-not-intervene set led to a switch to an in-phase pattern of coordination whereas the stay set led to phase wandering. Those findings are discussed within the framework of a dynamic account of bimanual coordination.

Protein film voltammetry of Rhodobacter capsulatus xanthine dehydrogenase

Xanthine dehydrogenase (XDH) from the bacterium Rhodobacter capsulatus catalyzes the hydroxylation of xanthine to uric acid with NAD(+) as the electron acceptor. R. capsulatus XDH forms an (alphabeta)(2) heterotetramer and is highly homologous to homodimeric eukaryotic XDHs. The crystal structures of bovine XDH and R. capsulatus XDH showed that the two proteins have highly similar folds; however, R. capsulatus XDH is at least 5 times more active than bovine XDH and, unlike mammalian XDH, does not undergo the conversion to the oxidase form. Here we demonstrate electrocatalytic activity of the recombinant enzyme, expressed in Escherichia coli, while immobilized on an edge plane pyrolytic graphite working electrode. Furthermore, we have determined all redox potentials of the four cofactors (Mo-VI/V, Mo-V/IV, FAD/FADH, FADH/FADH(2) and two distinct [2Fe-2S](2+/+) clusters) using a combination of potentiometric and voltammetric methods. A novel feature identified in catalytic voltammetry of XDH concerns the potential for the onset of catalysis (ca. 400 mV), which is at least 600 mV more positive than that of the highest potential cofactor. This unusual observation is explained on the basis of a pterin-associated oxidative switch during voltammetry that precedes catalysis.

Thermomechanical environment characterisation in injection moulding and its relation to the mechanical properties of talc-filled polypropylene

This study is focused on the establishment of relationships between the injection moulding processing conditions, the applied thermomechanical environment (TME) and the tensile properties of talc-filled polypropylene,adopting a new extended concept of thermomechanical indices (TMI). In this approach, TMI are calculated from computational simulations of the moulding process that characterise the TME during processing, which are then related to the mechanical properties of the mouldings. In this study, this concept is extended to both the filling and the packing phases, with new TMI defined related to the morphology developed during these phases. A design of experiments approach based on Taguchi orthogonal arrays was adopted to vary the injection moulding parameters (injection flow rate, injection temperature, mould wall temperature and holding pressure), and thus, the TME. Results from analysis of variance for injection-moulded tensile specimens have shown that among the considered processing conditions, the flow rate is the most significant parameter for the Young’s modulus; the flow rate and melt temperature are the most significant for the strain at break; and the holding pressure and flow rate are the most significant for the stress at yield. The yield stress and Young’s modulus were found to be governed mostly by the thermostress index (TSI, related to the orientation of the skin layer), whilst the strain at break depends on both the TSI and the cooling index (CI, associated to the crystallinity degree of the core region). The proposed TMI approach provides predictive capabilities of the mechanical response of injection-moulded components, which is a valuable input during their design stage.

Effect of the Impact Conditions on the Mechanical Properties of Injection-Molded Parts

This work focused on the study of the impact event on molded parts in the framework of automotive components. The influence of the impact conditions and processing parameters on the mechanical behavior of talc-filled polypropylene specimens was analyzed. The specimens were lateral-gate discs produced by injection molding, and the mechanical characterization was performed through instrumented falling weight impact tests concomitantly assisted with high-speed videography. Results analyzed using the analysis of variance (ANOVA) method have shown that from the considered parameters, only the dart diameter and test temperature have significant influence on the falling weight impact properties. Higher dart diameter leads to higher peak force and peak energy results. Conversely, higher levels of test temperatures lead to lower values of peak force and peak energy. By means of high-speed videography, a more brittle fracture was observed for experiments with higher levels of test velocity and dart diameter and lower levels of test temperature. The injection-molding process conditions assessed in this study have an influence on the impact response of moldings, mainly on the deformation capabilities of the moldings.

Motivação dos trabalhadores na sociedade do conhecimento

RESUMO: Nas sociedades avançadas da actualidade, aqui denominadas por sociedades do conhecimento, os níveis de responsabilidade e de exigência mental das organizações para com os seus trabalhadores é superior a qualquer outra realidade anterior. É emergente a necessidade de redefinir a estrutura das organizações, para que os reponsáveis e os seus respectivos colaboradores usufruam de condições potenciadoras do seu desempenho profissional. Os perfis ideais dos responsáveis de equipas e , em especial, dos «novos» trabalhadores produtores de conhecimento, incorporam determinadas características fundamentais para favorecerem o processo criativo e o trabalho autónomo. Mas as alterações não estão confinadas à dimensão laboral, pois surgiram igualmente mudanças profundas no seio da sociedade, as quais obrigam à existência de uma nova relação entre a vida pessoal e a vida profissional dos cidadãos. Todas estas transformações resultam na necessidade de uma componente motivacional muito forte por parte dos trabalhadores, os quais dependem apenas de si mesmos para a conseguir obter e manter. A solução desta problemática surge aqui configurada sob a forma de uma mudança de atitude por parte de todos os trabalhadores, a qual deverá fomentar a ocorrência de «Experiências óptimas» provenientes do desenvolvimento da actividade profissional dos mesmos, tal como é sugerido pela Teoria do Fluxo. Esta versão profunda da motivação intrínseca e estável é proposta como modelar e mesmo fulcral para o trabalhador na Sociedade do conhecimento. ABSTRACT: In today’s advanced societies, here referred as Knowledge Societies, the levels of responsibility and mental demanding which organizations require from their workers is higher than ever before. The need to redefine organizations structures is now emerging in order to allow CEO’s and their co-workers having access to encouraging conditions which improve their work performance. The ideal profile for a team leader and especially for the «new» Knowledge production workers, incorporate a defined group of fundamental characteristics to encourage the creative process and the autonomous work. But changes are not confined to the labor dimension. The Society core also suffered profound changes which demand the existence of a new relation between personal and professional life of its citizens. All these changes create the need for the existence of high motivational levels inside all workers, which now have to find their own ways to get and maintain it. The solution for this problem is presented here as a switch in workers attitude, which will increase the occurrence of optimal experiences coming directly from the development of their professional activity like it’s suggested in the flow theory. This version of the deep intrinsic and stable motivation is proposed as a model or even a central solution to the worker in the Knowledge Society.

Conceito de volume

Este estudo analisa o modo como se desenvolve a aprendizagem do conceito de volume nos alunos do 6º ano de escolaridade, no quadro de uma proposta pedagógica que dá ênfase a actividades que apelam à visualização e ao raciocínio espacial. O seu objectivo principal foi o de compreender as ideias que os alunos do 6.º ano têm sobre volume e perceber como se desenvolvem quando são envolvidos numa experiência de ensino, tendo por base uma cadeia de tarefas que apelam à visualização e ao raciocínio espacial. O estudo seguiu uma metodologia de investigação qualitativa baseada em estudos de caso. A proposta pedagógica foi desenvolvida em quatro aulas; três de noventa minutos e uma de quarenta e cinco minutos, durante os 2º e 3º períodos do ano lectivo de 2009/2010. A recolha de dados envolveu a realização de gravações áudio, em ambiente de sala de aula, dos alunos que constituíram os estudos de caso, registo de observações do desempenho dos alunos e os documentos produzidos por estes. Os resultados mostram que, ao longo da proposta pedagógica, os alunos adquiriram estratégias de contagem que lhes permitiram criar estruturas, para compreender a organização dos paralelepípedos e desenvolver o conceito de volume. iii ABSTRACT This study examines how 6th graders’ students develop the concept of volume in a learning experience context which emphasizes the visualization and spatial reasoning. The main objective of this study is to understand the ideas of 6th grade students about volume and see how they develop them when they are involved in a learning experience, based on a sequence of tasks that call for visualization and spatial reasoning. The study followed a qualitative research methodology based on case studies. The learning experience was developed in four classes, three ninety minutes period and one forty-five minutes, during the 2nd and 3rd terms of the school year 2009/2010. Data collection involved the use of audio recordings in the classroom environment, recording observations of student performance and the documents produced by them. The results showed that, over the learning experience, students acquired counting strategies that allowed them to create structures for understanding the organization of cubes arrays and develop the concept of volume.

A DC Voltage-Multiplier Circuit Working as a High-Voltage Pulse Generator

The intensive use of semiconductor devices enabled the development of a repetitive high-voltage pulse-generator topology from the dc voltage-multiplier (VM) concept. The proposed circuit is based on an odd VM-type circuit, where a number of dc capacitors share a common connection with different voltage ratings in each one, and the output voltage comes from a single capacitor. Standard VM rectifier and coupling diodes are used for charging the energy-storing capacitors, from an ac power supply, and two additional on/off semiconductors in each stage, to switch from the typical charging VM mode to a pulse mode with the dc energy-storing capacitors connected in series with the load. Results from a 2-kV experimental prototype with three stages, delivering a 10-mu s pulse with a 5-kHz repetition rate into a resistive load, are discussed. Additionally, the proposed circuit is compared against the solid-state Marx generator topology for the same peak input and output voltages.

Field effect and light-assisted a-Si:H sensors for detection of ions in solution

In this paper we present an amorphous silicon device that can be used in two operation modes to measure the concentration of ions in solution. While crystalline devices present a higher sensitivity, their amorphous counterpart present a much lower fabrication cost, thus enabling the production of cheap disposable sensors for use, for example, in the food industry. The devices were fabricated on glass substrates by the PECVD technique in the top gate configuration, where the metallic gate is replaced by an electrolytic solution with an immersed Ag/AgCl reference electrode. Silicon nitride is used as gate dielectric enhancing the sensitivity and passivation layer used to avoid leakage and electrochemical reactions. In this article we report on the semiconductor unit, showing that the device can be operated in a light-assisted mode, where changes in the pH produce changes on the measured ac photocurrent. In alternative the device can be operated as a conventional ion selective field effect device where changes in the pH induce changes in the transistor's threshold voltage.

Limiting Internal Supply Voltage Spikes in DC-DC Converters

Implementing monolithic DC-DC converters for low power portable applications with a standard low voltage CMOS technology leads to lower production costs and higher reliability. Moreover, it allows miniaturization by the integration of two units in the same die: the power management unit that regulates the supply voltage for the second unit, a dedicated signal processor, that performs the functions required. This paper presents original techniques that limit spikes in the internal supply voltage on a monolithic DC-DC converter, extending the use of the same technology for both units. These spikes are mainly caused by fast current variations in the path connecting the external power supply to the internal pads of the converter power block. This path includes two parasitic inductances inbuilt in bond wires and in package pins. Although these parasitic inductances present relative low values when compared with the typical external inductances of DC-DC converters, their effects can not be neglected when switching high currents at high switching frequency. The associated overvoltage frequently causes destruction, reliability problems and/or control malfunction. Different spike reduction techniques are presented and compared. The proposed techniques were used in the design of the gate driver of a DC-DC converter included in a power management unit implemented in a standard 0.35 mu m CMOS technology.

Repetitive Solid State Pulse Modulator Based on a DC Voltage Multiplier

A newly developed solid-state repetitive high-voltage (HV) pulse modulator topology created from the mature concept of the d.c. voltage multiplier (VM) is described. The proposed circuit is based in a voltage multiplier type circuit, where a number of d.c. capacitors share a common connection with different voltage rating in each one. Hence, besides the standard VM rectifier and coupling diodes, two solid-state on/off switches are used, in each stage, to switch from the typical charging VM mode to a pulse mode with the d.c. capacitors connected in series with the load. Due to the on/off semiconductor configuration, in half-bridge structures, the maximum voltage blocked by each one is the d.c. capacitor voltage in each stage. A 2 kV prototype is described and the results are compared with PSPICE simulations.

Conversor estático de potência tolerante a falhas

O trabalho apresentado nesta dissertação refere-se à concepção, projecto e realização experimental de um conversor estático de potência tolerante a falhas. Foram analisados trabalhos de investigação sobre modos de falha de conversores electrónicos de potência, topologias de conversores tolerantes a falhas, métodos de detecção de falhas, entre outros. Com vista à concepção de uma solução, foram nomeados e analisados os principais modos de falhas para três soluções propostas de conversores com topologias tolerantes a falhas onde existem elementos redundantes em modo de espera. Foram analisados os vários aspectos de natureza técnica dos circuitos de potência e guiamento de sinais onde se salientam a necessidade de tempos mortos entre os sinais de disparo de IGBT do mesmo ramo, o isolamento galvânico entre os vários andares de disparo, a necessidade de minimizar as auto-induções entre o condensador DC e os braços do conversor de potência. Com vista a melhorar a fiabilidade e segurança de funcionamento do conversor estático de potência tolerante a falhas, foi concebido um circuito electrónico permitindo a aceleração da actuação normal de contactores e outro circuito responsável pelo encaminhamento e inibição dos sinais de disparo. Para a aplicação do conversor estático de potência tolerante a falhas desenvolvido num accionamento com um motor de corrente contínua, foi implementado um algoritmo de controlo numa placa de processamento digital de sinais (DSP), sendo a supervisão e actuação do sistema realizados em tempo-real, para a detecção de falhas e actuação de contactores e controlo de corrente e velocidade do motor utilizando uma estratégia de comando PWM. Foram realizados ensaios que, mediante uma detecção adequada de falhas, realiza a comutação entre blocos de conversores de potência. São apresentados e discutidos resultados experimentais, obtidos usando o protótipo laboratorial.