Função afim e suas propriedades através da resolução de problemas

Pós-graduação em Matemática em Rede Nacional - IBILCE

Uma análise dos livros de André Perez Y Marin: um momento da história da matemática escolar brasileira no início do século XX

Pós-graduação em Educação Matemática - IGCE

Uma análise dos livros de André Perez Y Marin: um momento da história da matemática escolar brasileira no início do século XX

Pós-graduação em Educação Matemática - IGCE

Using occupancy models to investigate space partitioning between two sympatric large predators, the jaguar and puma in central Brazil

Coexistence of sympatric species is mediated by resource partitioning. Pumas occur sympatrically with jaguars throughout most of the jaguar's range but few studies have investigated space partitioning between both species. Here, camera trapping and occupancy models accounting for imperfect detection were employed in a Bayesian framework to investigate space partitioning between the jaguar and puma in Emas National Park (ENP), central Brazil. Jaguars were estimated to occupy 54.1% and pumas 39.3% of the sample sites. Jaguar occupancy was negatively correlated with distance to water and positively correlated with the amount of dense habitat surrounding the camera trap. Puma occupancy only showed a weak negative correlation with distance to water and with jaguar presence. Both species were less often present at the same site than expected under independent distributions. Jaguars had a significantly higher detection probability at cameras on roads than at off-road locations. For pumas, detection was similar on and off-road. Results indicate that both differences in habitat use and active avoidance shape space partitioning between jaguars and pumas in ENP. Considering its size, the jaguar is likely the competitively dominant of the two species. Owing to its habitat preferences, suitable jaguar habitat outside the park is probably sparse. Consequently, the jaguar population is likely largely confined to the park, while the puma population is known to extend into ENP's surroundings. (C) 2011 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.

Stable water isotopes of precipitation and firn cores from the northern Antarctic Peninsula region as a proxy for climate reconstruction

In order to investigate the climate variability in the northern Antarctic Peninsula region, this paper focuses on the relationship between stable isotope content of precipitation and firn, and main meteorological variables (air temperature, relative humidity, sea surface temperature, and sea ice extent). Between 2008 and 2010, we collected precipitation samples and retrieved firn cores from several key sites in this region. We conclude that the deuterium excess oscillation represents a robust indicator of the meteorological variability on a seasonal to sub-seasonal scale. Low absolute deuterium excess values and the synchronous variation of both deuterium excess and air temperature imply that the evaporation of moisture occurs in the adjacent Southern Ocean. The delta O-18-air temperature relationship is complicated and significant only at a (multi)seasonal scale. Backward trajectory calculations show that air-parcels arriving at the region during precipitation events predominantly originate at the South Pacific Ocean and Bellingshausen Sea. These investigations will be used as a calibration for ongoing and future research in the area, suggesting that appropriate locations for future ice core research are located above 600 m a.s.l. We selected the Plateau Laclavere, Antarctic Peninsula as the most promising site for a deeper drilling campaign.

Modelling Mathematical Reasoning in Physics Education

Many findings from research as well as reports from teachers describe students' problem solving strategies as manipulation of formulas by rote. The resulting dissatisfaction with quantitative physical textbook problems seems to influence the attitude towards the role of mathematics in physics education in general. Mathematics is often seen as a tool for calculation which hinders a conceptual understanding of physical principles. However, the role of mathematics cannot be reduced to this technical aspect. Hence, instead of putting mathematics away we delve into the nature of physical science to reveal the strong conceptual relationship between mathematics and physics. Moreover, we suggest that, for both prospective teaching and further research, a focus on deeply exploring such interdependency can significantly improve the understanding of physics. To provide a suitable basis, we develop a new model which can be used for analysing different levels of mathematical reasoning within physics. It is also a guideline for shifting the attention from technical to structural mathematical skills while teaching physics. We demonstrate its applicability for analysing physical-mathematical reasoning processes with an example.

The antioxidative effect of de novo generated vitamin B-6 in Plasmodium falciparum validated by protein interference

The malaria parasite Plasmodium falciparum is able to synthesize de novo PLP (pyridoxal 5'-phosphate), the active form of vitamin B-6. In the present study, we have shown that the de novo synthesized PLP is used by the parasite to detoxify O-1(2) (singlet molecular oxygen), a highly destructive reactive oxygen species arising from haemoglobin digestion. The formation of O-1(2) and the response of the parasite were monitored by live-cell fluorescence microscopy, by transcription analysis and by determination of PLP levels in the parasite. Pull-down experiments of transgenic parasites overexpressing the vitamin B-6-biosynthetic enzymes PfPdx1 and PfPdx2 clearly demonstrated an interaction of the two proteins in vivo which results in an elevated PLP level from 12.5 mu M in wild-type parasites to 36.6 mu M in the PfPdx1/PfPdx2-overexpressing cells and thus to a higher tolerance towards O-1(2). In contrast, by applying the dominant-negative effect on the cellular level using inactive mutants of PfPdx1 and PfPdx2, P. falciparum becomes susceptible to O-1(2). Our results demonstrate clearly the crucial role of vitamin B-6 biosynthesis in the detoxification of O-1(2) in P falciparum. Besides the known role of PLP as a cofactor of many essential enzymes, this second important task of the vitamin B-6 de novo synthesis as antioxidant emphasizes the high potential of this pathway as a target of new anti-malarial drugs.

Sleep length, working hours and socio-demographic variables are associated with time attending evening classes among working college students

It is the aim of the present study to assess factors associated with time spent in class among working college students. Eighty-two working students from 21 to 26 years old participated in this study. They were enrolled in an evening course of the University of Sao Paulo, Brazil. Participants answered a questionnaire on living and working conditions. During seven consecutive days, they wore an actigraph, filled out daily activity diaries (including time spent in classes) and the Karolinska Sleepiness Scale every three hours from waking until bedtime. Linear regression analyses were performed in order to assess the variables associated with time spent in classes. The results showed that gender, sleep length, excessive sleepiness, alcoholic beverage consumption (during workdays) and working hours were associated factors with time spent in class. Thus, those who spent less time in class were males, slept longer hours, reported excessive sleepiness on Saturdays, worked longer hours, and reported alcohol consumption. The combined effects of long work hours (>40 h/week) and reduced sleep length may affect lifestyles and academic performance. Future studies should aim to look at adverse health effects induced by reduced sleep duration, even among working students who spent more time attending evening classes.

Differences in throughfall and net precipitation between soybean and transitional tropical forest in the southern Amazon, Brazil

The expansion of soybean cultivation into the Amazon in Brazil has potential hydrological effects at local to regional scales. To determine the impacts of soybean agriculture on hydrology, a comparison of net precipitation (throughfall, stemflow) in undisturbed tropical forest and soybean fields on the southern edge of the Amazon Basin in the state of Mato Grosso is needed. This study measured throughfall with troughs and stemflow with collar collectors during two rainy seasons. The results showed that in forest 91.6% of rainfall was collected as throughfall and 0.3% as stemflow, while in soybean fields with two-month old plants, 46.2% of rainfall was collected as throughfall and 9.0% as stemflow. Hence, interception of precipitation in soybean fields was far greater than in intact forests. Differences in throughfall, stemflow and net precipitation were found to be mainly associated with differences in plant structure and stem density in transitional forest and soybean cropland. Because rainfall interception in soybean fields is higher than previously believed and because both the area of cropland and the frequency of crop cycles (double cropping) are increasing rapidly, interception needs to be reconsidered in regional water balance models when consequences of land cover changes are analyzed in the Amazon soybean frontier region. Based on the continued expansion of soybean fields across the landscape and the finding that net precipitation is lower in soy agriculture, a reduction in water availability in the long term can be assumed. (C) 2012 Elsevier B.V. All rights reserved.

As reformas necessárias ao ensino secundário brasileiro nos anos 1950, segundo a Revista Brasileira de Estudos Pedagógicos

Neste artigo, propõe-se uma análise dos artigos sobre o ensino secundário, publicados na Revista Brasileira de Estudos Pedagógicos (RBEP) ao longo dos anos de 1950. Investigam-se as críticas feitas por seus colaboradores à organização dada pela Lei Orgânica do Ensino Secundário (1942) a ramo do ensino médio, assim como as principais propostas de reforma, visando a torná-lo mais ativo, mais prático e mais popular. O objetivo principal é investigar que novo padrão de ensino secundário se projetava da combinação dos argumentos, como ideal para o ensino secundário brasileiro nos anos 1950. Tais necessidades se justificavam pela ideia de que o mundo vinha sendo regido por "novos imperativos" culturais, que a escola brasileira deveria adotar a fim de fomentar o desenvolvimento do país.

STAT3 and SOCS3 expression patterns during murine placenta development

Signal transducers and activators of transcription 3 (STAT3) has been identified as an important signal transducer in the invasive phenotype of the trophoblasts cells in in vitro studies. However, the in situ distribution and patterns of expression of this molecule in trophoblast cells during the development of the placenta are still under-elucidated. Mice uteri of gestational ages between 7 and 14 days of pregnancy (dop) were fixed in methacarn and processed with immunoperoxidase techniques for detection of STAT3 and its phosphorylation at serine (p-ser727) residues, as well as the suppressor of cytokine signaling 3 (SOCS3) expression. STAT3 was observed at 7 through 9 dop in both the antimesometrial and mesometrial deciduas, while continued immunoreactivity between 10 and 13 dop was seen only in the mesometrial decidua. In the placenta, STAT3 was detected in the cytotrophoblast cells of labyrinth and giant trophoblast cells between 10 and 14 dop. Immunoreactivity for STAT3 was also seen in trophoblast cells surrounding the maternal blood vessels. On days 10 and 11 of pregnancy, p-ser727 was detectable in the mesometrial decidua and in giant trophoblasts, while during 12-14 dop in the spongiotrophoblast region. In addition, SOCS3 was immunodetected in maternal and placental tissues, principally in the giant trophoblast cells during the whole period of the study. The present in situ study shows the distribution of STAT3, its serine activation and SOCS3 in different maternal and fetal compartments during murine placental development, thus further supporting the idea that they play a role during physiological placentation in mice.

Synthetic biology: a novel approach for the construction of industrial microorganisms

The recent achievement of synthesising a functioning bacterial chromosome marks a coming of age for engineering living organisms. In the future this should allow the construction of novel organisms to help solve the problems facing the human race, including health care, food, energy and environmental protection. In this minireview, the current state of the field is described and the role of synthetic biology in biotechnology in the short and medium term is discussed. It is particularly aimed at the needs of food technologists, nutritionists and other biotechnologists, who might not be aware of the potential significance of synthetic biology to the research and development in their fields. The potential of synthetic biology to produce interesting new polyketide compounds is discussed in detail.

Reconstructing Quantum Field Theory from an Educational Perspective

The research work concerns the analysis of the foundations of Quantum Field Theory carried out from an educational perspective. The whole research has been driven by two questions: • How the concept of object changes when moving from classical to contemporary physics? • How are the concepts of field and interaction shaped and conceptualized within contemporary physics? What makes quantum field and interaction similar to and what makes them different from the classical ones? The whole work has been developed through several studies: 1. A study aimed to analyze the formal and conceptual structures characterizing the description of the continuous systems that remain invariant in the transition from classical to contemporary physics. 2. A study aimed to analyze the changes in the meanings of the concepts of field and interaction in the transition to quantum field theory. 3. A detailed study of the Klein-Gordon equation aimed at analyzing, in a case considered emblematic, some interpretative (conceptual and didactical) problems in the concept of field that the university textbooks do not address explicitly. 4. A study concerning the application of the “Discipline-Culture” Model elaborated by I. Galili to the analysis of the Klein-Gordon equation, in order to reconstruct the meanings of the equation from a cultural perspective. 5. A critical analysis, in the light of the results of the studies mentioned above, of the existing proposals for teaching basic concepts of Quantum Field Theory and particle physics at the secondary school level or in introductory physics university courses.

La professione docente tra rappresentazioni e progetto formativo. Un'analisi pedagogica della competenza degli insegnanti secondari

This thesis deals with the professional characteristics of secondary school teachers, with particular regard to their competence and their education. The topic will be approached starting from the characteristics and trasnformations social research has identified concerning Italian teachers, focusing on secondary teacher training. After a brief look at Europe, the attention will be directed to Italy, with particular regard to the Postgraduate Schools of Specialisation for Secondary School Teachers (SSIS); hence the need for an analysis that focuses on teaching per se and its concrete pratice. For its nature to be fully grasped, teaching must be reconsidered as an independent object of study, a performance in which competence manifests itself and a form of action involving a set of tacit and personal knowledge. A further perspective opens up for analysis, according to which the professional characteristics of teachers are the result of an education in which the whole history of the subject is involved, in its educative, formative, professional and personal aspects. The teaching profession is imbued with implicit meanings which are inaccessible to conscience but orient action and affect the interpretation of experience. Through the analysis of three different empirical data sets, collected among teachers-in-training and teachers qualified at SSIS, I will try to investigate the actual existence, the nature and the features of such implicit knowledge. It appears necessary to put the claims of process-product approaches back in their right perspective, to the benefit of a holistic conception of teaching competence. The teacher is, at the same time, “he who is teaching” and offers a concrete receiver the fruit of an endless work of study, reflection, practice and self-update. To understand this process will mean to penetrate more and more deeply into the core of teaching and teaching competence , a competence that in some respects “is” always “that” teacher, with his or her own story, implicit knowledge and representations.

"Wie eine andere Welt"

„Wie eine andere Welt“ – Eine Grounded Theory-Studie zur Frage der Teilhabe von Eltern an schulischer Kommunikation am Beispiel von RealschülerInnen Autorin: Sabine Rech Die Arbeit geht explizit auf das Verhältnis von Familie und Schule ein, wobei dieses Verhältnis nicht traditionellerweise unter dem Aspekt des Einflusses von Eltern auf die Schule bzw. der Einflussmöglichkeiten und der Zusammenarbeit von Eltern und Schule thematisiert wird, sondern inwiefern Eltern an schulischer Kommunikation teilhaben. Dies schließt unausweichlich die Frage ein, inwiefern das Thema Schule in der familialen Kommunikation aufkommt bzw. ob und welche Irritationen dadurch entstehen. Die Arbeit verfolgt dabei theoretisch einen systemtheoretischen Ansatz, mit dem die Systeme Familie und Schule eingeordnet werden. Methodisch wird mit der Grounded Theory eine eigene Studie an RealschülerInnen und ihren Eltern zur Forschung herangezogen. Nach dem Referat des Forschungsstandes und der theoretischen Rahmung wird die konkrete empirische Studie an zwei Fragen zu entfalten: „Wie gestaltet sich der Lebensalltag im Elternhaus unter dem Einfluss einer komplexen Teilhabe an schulbezogener Kommunikation“ und „Auf welche Weise erfolgt die Inklusion der Kommunikation des formal organisierten Schullebens in den emotional ausgestatteten Familienalltag und damit die Teilhabe der Eltern an der im Elternhaus geführten schulbezogenen Kommunikation?“. Diese Fragen werden in einen empirischen Rahmen gefasst und durch die Auswertung des Datenmaterials der Untersuchungsgruppe (16 RealschülerInnen der achten Klasse und 6 Elternteile) ausgewertet. Die Ergebnisse dieser Analyse, die an dieser Stelle nicht in ihrer Differenziert dargestellt werden können, zeigen als wesentlichen Ertrag das Bild von der Schule als „andere Welt“ für Eltern der RealschülerInnen. Dies lässt sich empirisch durch die Analyse der Kommunikation in der Familie belegen. Die Analyse des Datenmaterials der SchülerInnen weist hingegen darauf hin, dass Jugendliche die Schule nicht als etwas Fremdes und Distanziertes erleben, sondern hier eine Bereicherung ihrer eigenen Lebenswelt definieren.