CMOS-based active pixel for low-light-level detection: Analysis and measurements

An analysis of the active pixel sensor (APS), considering the doping profiles of the photodiode in an APS fabricated in a 0.18 μm standard CMOS technology, is presented. A simple and accurate model for the junction capacitance of the photodiode is proposed. An analytic expression for the output voltage of the APS obtained with this capacitance model is in good agreement with measurements and is more accurate than the models used previously. A different mode of operation for the APS based on the dc level of the output is suggested. This new mode has better low-light-level sensitivity than the conventional APS operating mode, and it has a slower temporal response to the change of the incident light power. At 1μW/cm2 and lower levels of light, the measured signal-to-noise ratio (SNR) of this new mode is more than 10 dB higher than the SNR of previously reported APS circuits. Also, with an output SNR of about 10 dB, the proposed dc level is capable of detecting light powers as low as 20 nW/cm2, which is about 30 times lower than the light power detected in recent reports by other groups. © 2007 IEEE.

Optimal allocation of distributed generators providing reactive power support ancillary service

Problems as voltage increase at the end of a feeder, demand supply unbalance in a fault condition, power quality decline, increase of power losses, and reduction of reliability levels may occur if Distributed Generators (DGs) are not properly allocated. For this reason, researchers have been employed several solution techniques to solve the problem of optimal allocation of DGs. This work is focused on the ancillary service of reactive power support provided by DGs. The main objective is to price this service by determining the costs in which a DG incurs when it loses sales opportunity of active power, i.e, by determining the Loss of Opportunity Costs (LOC). The LOC will be determined for different allocation alternatives of DGs as a result of a multi-objective optimization process, aiming the minimization of losses in the lines of the system and costs of active power generation from DGs, and the maximization of the static voltage stability margin of the system. The effectiveness of the proposed methodology in improving the goals outlined was demonstrated using the IEEE 34 bus distribution test feeder with two DGs cosidered to be allocated. © 2011 IEEE.

Análise do comportamento de pacientes atendidos na Bebê Clínica da Disciplina de Odontopediatria da Faculdade de Odontologia de Araçatuba-UNESP: estudo longitudinal

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Access of children to the oral health service

Dental caries still affect a considerable proportion of children, however the epidemiological profile of oral diseases is changing, social inequalities cause different disease patterns. The same problems occur for the use of services, which damage those who are more susceptible to oral diseases in numerous ways. To verify the association between the variables: socioeconomic condition, oral health and access to dental services providing oral health care for preschool children. The study population consisted of 2,759 children up to 6 years-old. The clinical exams followed the World Health Organization (WHO) criteria. The data were collected using a self-applied questionnaire, answered by the carers of children, with questions about socioeconomic variables and access to dental services. In terms of social class, a majority of the subjects came from the middle socioeconomic level (babies, 84.7%; children, 82.8%). Babies who had caries, 48.4% and 67.2% of the children that had decayed teeth had access to dental service. There was a association between the variables: the reason for the last dental appointment and the parent's perception of the treatment need of their children (babies p=0.0004 and children p < 0.0001); the parent's perception of the treatment need of their children and the oral health condition (babies p=0.0008 and children p < 0.0001); access to dental services and oral health condition (babies p=0.0021 and children p < 0.0001). The majority of the population studied sought care from public dental service and was from the middle class.

Pedagogical practices carried out during an in-service teachers education project: approaching history and philosophy of science to physics teaching

We report here part of a research project developed by the Science Education Research Group, titled: "Teachers’ Pedagogical Practices and formative processes in Science and Mathematics Education" which main goal is the development of coordinated research that can generate a set of subsidies for a reflection on the processes of teacher training in Sciences and Mathematics Education. One of the objectives was to develop continuing education activities with Physics teachers, using the History and Philosophy of Science as conductors of the discussions and focus of teaching experiences carried out by them in the classroom. From data collected through a survey among local Science, Physics, Chemistry, Biology and Mathematics teachers in Bauru, a São Paulo State city, we developed a continuing education proposal titled “The History and Philosophy of Science in the Physics teachers’ pedagogical practice”, lasting 40 hours of lessons. We followed the performance of five teachers who participated in activities during the 2008 first semester and were teaching Physics at High School level. They designed proposals for short courses, taking into consideration aspects of History and Philosophy of Science and students’ alternative conceptions. Short courses were applied in real classrooms situations and accompanied by reflection meetings. This is a qualitative research, and treatment of data collected was based on content analysis, according to Bardin [1].