O desenvolvimento do conceito de ��rea: um estudo com alunos do 3.�� ano de escolaridade

O objetivo desta investiga����o �� compreender como �� que alunos do 3.�� ano de escolaridade desenvolvem o conceito de ��rea com ��nfase em conhecimentos sobre figuras e propriedades geom��tricas. Para melhor objetivar o estudo, formulei tr��s quest��es que orientaram a investiga����o. Pretendo (1) compreender como �� que os alunos mobilizam conhecimentos sobre as propriedades das figuras geom��tricas no estudo da ��rea de uma figura plana? A que estrat��gias recorrem? Que dificuldades sentem? (2) que compreens��o �� que os alunos t��m sobre o processo de medi����o? e (3) que ideias e/ou experi��ncias s��o relevantes no desenvolvimento do conceito de ��rea? Este �� um estudo que se insere no paradigma interpretativo e que segue uma abordagem qualitativa, pelo que n��o visa generaliza����o de resultados, mas uma descri����o compreensiva dos processos vivenciados, tendo em conta os contextos pessoais e sociais. Optei por realizar dois Estudos de Caso. Os dados foram recolhidos atrav��s de fontes diversificadas, donde se destacam a observa����o participante e a an��lise de registos audiovisuais e escritos dos alunos. A an��lise dos dados teve por refer��ncia categorias criadas com base em contributos da literatura de refer��ncia. As conclus��es desta investiga����o centram-se numa an��lise acerca das estrat��gias a que os alunos em estudo tendencialmente mais recorrem, visando tamb��m algumas das suas dificuldades mais relevantes e sobre as quais importa refletir. Destaca-se que ambos os alunos foram capazes de recorrer a racioc��nios baseados e n��o baseados na medida, embora seja evidente uma tend��ncia para racioc��nios baseados na medida. �� igualmente importante referir que os dois alunos revelaram um bom conhecimento acerca do processo de medi����o, mesmo quando ele implicava a defini����o de uma unidade de medida adequada e/ou mudan��a de unidade. �� dado, tamb��m, destaque ��s experi��ncias matem��ticas que devem ser proporcionadas aos alunos no sentido do desenvolvimento de um conhecimento amplo e flex��vel do conceito de ��rea. - Abstract The purpose of this investigation is to understand the development of 3rd year students��� concept of area based on their knowledge of geometrical properties and figures. As means to orientate the present study, the following investigation questions were formulated: 1) how do students use their knowledge about geometrical properties in order to understand geometrical shape���s areas? Which strategies do they use? What do they struggle with? (2) What is their understanding about measurement? And (3) what are the most relevant mathematical reasonings and classroom tasks in the development of the concept of area? This is a study that follows a qualitative approach: it does not intend to be a generalization, but a fully comprehensive description of the witnessed learning processes, bearing in mind the social and personal contexts. As such, two study-cases were developed. The data were collected through various sources, such as direct observation and analysis of audiovisual records or written worksheets. The scrutiny of the generated data was undertaken following criteria based on the literature of reference. The conclusions of this investigation are centered on the most used strategies as well as the students��� difficulties upon which it is important to discuss. It was noticed that the two students were able to use both measurement and non measurement thinking ��� although, preferably, they tend to use the first one. On the other hand, it is equally demonstrated that the two students have shown good acquaintance about measurement, even if obliged to the establishment of a suitable unit of measurement and/or change of units. At last, it is also referred which mathematical classroom tasks are important to develop a sustained and comprehensive concept of area.

Synthesis, Antimicrobial and Antiproliferative Activity of Novel Silver(I) Tris(pyrazolyl)methanesulfonateand 1,3,5-Triaza-7-phosphadamantane Complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)-(PPh3)] (2), [Ag(Tpms)(PCy3)] (3), [Ag(PTA)][BF4] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh3 = triphenylphosphane, PCy3 = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane) have been synthesized and fully characterized by elemental analyses, H-1, C-13, and P-31 NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N-3-facially coordinating mode, while in 2 and 5 a N2O-coordination is found, with the SO3 group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA1S9), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA EB system on addition of Ag complexes shows that the fluorescence quenching of DNA EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO3, which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO3 >> 4.

Trends in properties of para-substituted 3-(phenylhydrazo)pentane-2,4-diones

Trends between the Hammett's sigma(p) and related normal sigma(n)(p), inductive sigma(I), resonance sigma(R), negative sigma(-)(p) and positive sigma(+)(p) polar conjugation and Taft's sigma(o)(p) substituent constants and the N-H center dot center dot center dot O distance, delta(N-H) NMR chemical shift, oxidation potential (E-p/2(ox), measured in this study by cyclic voltammetry (CV)) and thermodynamic parameters (pK, Delta G(0), Delta H-0 and Delta S-0) of the dissociation process of unsubstituted 3-(phenylhydrazo)pentane-2,4-dione (HL1) and its para-substituted chloro (HL2), carboxy (HL3), fluoro (HL4) and nitro (HL5) derivatives were recognized. The best fits were found for sigma(p) and/or sigma(-)(p) in the cases of d(N center dot center dot center dot O), delta(N-H) and E-p/2(ox), showing the importance of resonance and conjugation effects in such properties, whereas for the above thermodynamic properties the inductive effects (sigma(I)) are dominant. HL2 exists in the hydrazo form in DMSO solution and in the solid state and contains an intramolecular H-bond with the N center dot center dot center dot O distance of 2.588(3)angstrom. It was also established that the dissociation process of HL1-5 is non-spontaneous, endothermic and entropically unfavourable, and that the increase in the inductive effect (sigma(I)) of para-substitutents (-H < -Cl < -COOH < -F < -NO2) leads to the corresponding growth of the N center dot center dot center dot O distance and decrease of the pK and of the changes of Gibbs free energy, of enthalpy and of entropy for the HL1-5 acid dissociation process. The electrochemical behaviour of HL1-5 was interpreted using theoretical calculations at the DFT/HF hybrid level, namely in terms of HOMO and LUMO compositions, and of reactivities induced by anodic and cathodic electron-transfers. Copyright (C) 2010 John Wiley & Sons, Ltd.

Analysis of the interference of endogenous circadian rhythms on 3'- deoxy- 3'- [18F]Fluorothymidine physiological uptake at the human bone marrow

The main purpose of the present study is to determine if the circadian rhythms present in the human bone marrow are likely to influence 3���- deoxy- 3���-[18F] Fluorothymidine (18F-FLT) uptake in the same organ. The 18F-FLT is a Thymidine analogous proliferation agent. The relatively high physiological uptake of this tracer in the bone marrow diminishes the Tumor/Background (T/B) ratio, decreasing the detection accuracy of PET/CT and possibly affecting SUV quantifications.

A realidade da obesidade infantil em Portugal: epidemiologia, determinantes e interven����o

A obesidade �� apontada como o dist��rbio nutricional mais frequente em crian��as e adolescentes nos pa��ses desenvolvidos e a sua preval��ncia tem vindo a aumentar a n��vel mundial a um ritmo alarmante. Neste artigo, s��o apresentados tr��s estudos que se coordenam entre si. No primeiro estudo, avalia-se a preval��ncia de pr��-obesidade (22,6%) e de obesidade (7,8%) infantojuvenil em Portugal, apresentando valores superiores nos rapazes e nos adolescentes mais jovens. Em rela����o aos h��bitos alimentares, verifica-se que o consumo de alimentos de caracter��sticas nutricionais de baixa qualidade �� superior no grupo normoponderal. Em rela����o �� atividade f��sica, quanto maior o ��ndice de atividade f��sica menor o percentil de I.M.C. No estudo sobre determinantes parentais, salienta-se que a grande maioria dos pais das crian��as com excesso de peso tendem a sub-avaliar o peso da crian��a. Outro aspeto relevante �� a confirma����o de que o conhecimento nutricional dos pais influencia claramente os h��bitos alimentares das crian��as. Por fim, �� apresentado um projeto de interven����o que, intervindo nos determinantes parentais, visa a mudan��a das suas cren��as e comportamentos, de modo a promoverem mudan��as alimentares nos seus filhos.

Synthesis, structure and electrochemical behaviour of Na, Mg-II, Mn-II, Cd-II and Ni-II complexes of 3-(2-carboxyphenylhydrazone)pentane-2,4-dione

Mononuclear manganese(II) [Mn(kappa O-HL)(2)(CH3OH)(4)] (4), nickel(II) [Ni(kappa O-2, kappa N-L)(H2O)(3)] (5), cadmium(II) [Cd(kappa O-2-HL)(2)(CH3OH)(3)] (7), tetranuclear zinc(II) [Zn-4(mu-OH)(2)(1 kappa O:2 kappa O-HL)(4)(kappa O-HL)(2)(H2O)(4)] (6) and polynuclear aqua sodium(I) [Na(H2O)(2)(mu-H2O)(2)](n)(HL)(n) (2) and magnesium(II) [Mg(OH)(H2O)(mu-H2O)(2)](n)(-HL)(n) (3) complexes were synthesized using 3-(2-carboxyphenyl-hydrazone)pentane-2,4-dione (H2L, 1) as a ligand precursor. The complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR, H-1 and C-13 NMR (for 2, 3, 6 and 7) spectroscopies. Mono- or dianionic deprotonated derivatives of H2L display different coordination modes and lead to topologies and nuclearities of the complexes depending on metal ions and conditions used for the syntheses. Extensive intermolecular H-bonds form supramolecular arrangements in 1D chains (4 and 6), 1D chains of the organic anion and 2D networks of the metal-aqua aggregates (2 and 3), 2D networks (7) or even 3D frameworks (5). Electrochemical studies, by cyclic voltammetry and controlled potential electrolysis, show ligand centred redox processes as corroborated by theoretical DFT calculations in terms of LUMO and HOMO compositions. (C) 2012 Elsevier Ltd. All rights reserved.

Avalia����o e promo����o da qualidade dos cuidados prestados em creche familiar: primeiros resultados de um estudo de investiga����o/ac����o

Neste artigo apresentam-se os resultados do projecto de investiga����o/ac����o Promo����o da qualidade dos cuidados prestados em amas e creche familiar (resposta enquadrada pelo Decreto-Lei n.��158/84). �� um estudo explorat��rio, de car��cter longitudinal, que teve como principais objectivos: (1) avaliar a qualidade da resposta creche familiar em duas institui����es do Distrito de Lisboa; (2) analisar se vari��veis como a idade, n��vel de escolaridade e tempo de experi��ncia das amas, o r��cio TE/ama e a idade das crian��as estavam associadas �� qualidade de cuidados prestada; (3) sistematizar os passos de um programa de promo����o da qualidade baseado numa metodologia de consultoria; e (4) determinar os efeitos do programa de consultoria na promo����o da qualidade. Participaram neste projecto 10 amas enquadradas na creche familiar de um centro infantil do Centro Distrital de Seguran��a Social de Lisboa, 21 amas de centros infantis da Santa Casa da Miseric��rdia de Lisboa e os T��cnicos de Enquadramento respons��veis pelo apoio t��cnico. A Family Child Care Environment Rating Scale, Revised Edition (FCCERS-R) de Harms, Cryer e Clifford (2007), traduzida pela equipa de investiga����o, foi o principal instrumento utilizado. A recolha de dados decorreu em tr��s momentos: (1) avalia����o inicial; (2) reuni��o de consultoria; e (3) avalia����o final.Os resultados encontrados mostram que a qualidade dos cuidados prestados pelas amas �� adequada/m��nima, com excep����o dos itens relacionados com a interac����o ama-crian��a onde a qualidade �� boa, sendo a subescala actividades aquela onde foram encontrados valores mais baixos. N��o foram encontradas associa����es significativas entre a qualidade e o tempo experi��ncia das amas. Relativamente ��s restantes vari��veis ��� idade das amas, r��cio TE/ama e idade das crian��as ��� encontraram-se algumas associa����es com a qualidade global e em algumas das subescalas da FCCERS-R. Foram encontradas diferen��as entre os dados da 1�� e da 2�� observa����o que parecem poder associar-se ao processo de consultoria implementado.

A metodologia de trabalho de projeto na nossa pr��tica pedag��gica

Por que raz��o se tornou a Metodologia de Trabalho de Projeto uma op����o de fundo e um foco central do nosso curr��culo para a Educa����o Pr��-escolar e 1�� Ciclo do Ensino B��sico? O que nos traz essa metodologia em termos da realiza����o dos nossos pr��prios objetivos e da qualidade do ensino que pretendemos promover? Como se enquadra esta metodologia no conjunto de abordagens que utilizamos e na organiza����o geral do nosso curr��culo? S��o estas as principais quest��es a que o presente artigo ��� extrato adaptado de uma publica����o interna que fizemos ��� procura dar resposta: num primeiro momento, atrav��s de uma reflex��o mais te��rica; depois, atrav��s do relato breve de um projeto concreto, sobre ���Os Romanos���, desenvolvido numa sala de crian��as de 5 anos.

Cobalt and Zinc Compounds Bearing 1,10-Phenanthroline-5,6-dione or 1,3,5-Triaza-7-phosphaadamantane Derivatives - Synthesis, Characterization, Cytotoxicity, and Cell Selectivity Studies

The compounds [mPTA][CoCl4] (1, mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation), [CoCl(H2O)(DION)(2)][BF4] (2, DION = 1,10-phenanthroline-5,6-dione), [Zn(DION)(2)]Cl-2 (3) and [ZnCl(O-PTA=O)(DION)][BF4] (4) were synthesized by reaction of CoCl2 with [mPTA]I or DION and ZnCl2 with DION or 1,3,5-triaza-7-phosphaadamantane-7-oxide (PTA=O) and DION, respectively. All complexes are water soluble and have been characterized by IR, far-IR, H-1, C-13 and P-31{H-1} NMR spectroscopy, ESI-MS, elemental analyses and single-crystal X-ray diffraction structural analysis (for 1). They were screened against the human tumour cell lines HCT116, HepG2 and MCF7. Complexes 2 and 3 exhibit the highest in vitro cytotoxicity and show lower cytotoxic activities in normal human fibroblast cell line than in HCT116 tumour cell line, which demonstrates their slight specificity for this type of tumour cell.