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The importance of students being acquainted with algebraic ideas before secondary education has been revealed in the research literature. It is therefore essential that prospective elementary teachers (PTs) be prepared to instill an early algebra perspective in their teaching. However, PTs often show difficulties in algebra content knowledge, which need to be diagnosed aiming to assist them in developing the required knowledge to teach according to that perspective. This study aims to understand what aspects of functional thinking Spanish and Portuguese elementary PTs exhibit at the beginning of their teacher education program. The findings show that although PTs from both countries use different strategies to generalize functional relationships, the occurrence of successful strategies is low. Also, most participants provide local approaches in their interpretation of relationships between variables and reveal difficulties in understanding and connecting different representations of functions. These difficulties show that PTs lack important knowledge about functional thinking. By providing a framework concerning the functional thinking required for PTs to teach within an early algebra perspective, we shed light on a necessary step for teacher education programs to diagnose PTs’ functional thinking and to assist them in developing the needed mathematical knowledge to teach accordingly.

This paper demonstrates why VCSEL-based transmitter systems are not able to capitalize on higher-order PAM modulation formats (such as PAM-4) to push the link data rate towards 100 Gbit/s with BER of better than 10−5. First, the non-linear and biasing-dependent VCSEL behavior is analyzed in great detail to prove why state-of-the-art VCSELs with linear equalization are not able to reach these bandwidth targets. Consequently, based on an enhanced VCSEL model, a digital non-linear transmit equalizer is proposed to overcome voltage-dependent relaxation frequency shifts as well as data-dependent VCSEL bandwidth variations. The proposed digital non-linear equalizer is compared with a standard linear FFE structure using PAM-4 transmission experiments of 100 Gbit/s and beyond. This way, the proposed non-linear equalizer reveals a BER improvement of more than 30-fold compared to a linear FFE at a data rate of 80 Gbit/s. Finally, at 112 Gbit/s PAM-4 the non-linear equalizer was successfully demonstrated at a BER of 1.5·10−7.

Este estudo busca compreender as aprendizagens profissionais de professores acerca do ensino de Estatística, evidenciadas nas reflexões elicitadas na análise de um caso multimídia assente em uma prática de ensino exploratório envolvendo o conceito de média. Os seis professores participantes de um programa de formação, em foco neste artigo, analisaram episódios do referido caso focalizados em: (i) manifestação pelos alunos de componentes do pensamento estatístico e (ii) ações do professor na promoção do pensamento estatístico dos alunos. O quadro teórico que orienta a análise interpretativa dos dados produzidos, principalmente por observação participante, combina a noção de noticing e três níveis de reflexão sobre a prática: descritiva, fundamentada e crítica. Os resultados revelam mudanças na natureza e incidência das reflexões dos professores sobre: conceitos estatísticos e a natureza do conhecimento estatístico; modos de encaminhar uma aula de estatística; e a plausibilidade da efetivação de práticas semelhantes em seus contextos de trabalho. A natureza das interações e dos episódios, as questões orientadoras do caso, a dimensão cooperativa da exploração e o planejamento intencional emergem como aspectos centrais do dispositivo de formação favorecedores dessas mudanças. Conclui-se, assim, que contextos de formação com tais características podem contribuir para a aprendizagem profissional do professor no campo da Educação Estatística, na medida que promovem a sua capacidade de noticing orientada para os temas propostos.

O presente estudo foi realizado no âmbito da formação didática do mestrado em ensino da Matemática para o 3º ciclo do ensino básico e o ensino secundário, da Universidade de Lisboa, com o objetivo de compreender que conhecimentos profissionais os futuros professores apresentam no que diz respeito à integração das tecnologias digitais em aulas, na perspectiva do ensino exploratório. Adotando-se o modelo teórico de Technological Pedagogical Content Knowledge (TPACK), procura-se especificamente conhecer o nível de desenvolvimento de TPACK demonstrado pelos futuros professores, nas dimensões do currículo, da aprendizagem e do ensino. A análise de dados incide sobre os planos de aula detalhados que os grupos de futuros professores elaboraram e nas suas justificativas para as opções tomadas, em dois semestres consecutivos do curso. Os resultados evidenciam uma evolução positiva do TPACK dos futuros professores em várias dimensões, tendo este se mostrado mais desenvolvido na dimensão relativa à aprendizagem. No entanto, nas propostas inclusas em seus planos, observa-se que não são suficientemente visadas atividades de pensamento de nível elevado nem é promovida a autonomia do aluno no que diz respeito a sua aprendizagem sobre o uso da tecnologia para resolução das tarefas propostas. Reconhecendo-se que a planificação da integração da tecnologia no ensino da Matemática é uma prática complexa, são requeridas experiências significativas durante a formação inicial, mais próximas à realidade de sala de aula, para que os futuros professores aprendam a usar a tecnologia de modo a transformar o ensino e criar oportunidades para a aprendizagem dos alunos no quadro de uma abordagem exploratória.

Este estudo decorre de uma experiência de formação com futuros professores (FPs) de física e de matemática, assente numa perspetiva STEM, num cenário de aprendizagem com tecnologia. A investigação foca-se no Pedagogical Content Knowledge (PCK) dos FPs relativo à promoção da articulação das duas áreas, procurando perceber-se como integram a tecnologia na planificação de aulas do 8.º ano e os desafios e dificuldades que emergem nesse contexto. A análise dos dados, recolhidos através dos planos de aula e reflexões escritas dos FPs, incidiu sobre os modos como perspetivam e refletem sobre o uso da tecnologia nas três dimensões do modelo de articulação adotado. Evidencia-se que os FPs integram a tecnologia para sustentar os processos de inquiry e argumentação na presença das duas áreas disciplinares. Contudo, o uso da tecnologia para promover síntese de conhecimentos constituiu um ponto crítico, sendo um dos aspetos do PCK a merecer maior atenção na formação.

Background: This study aimed to evaluate the role of efflux pump regulator and OXA-23 genes in imipenem resistance Acinetobacter baumannii strains isolated from hospitalized patients in Tehran, Iran. Methods: This study was conducted on 60 A. baumannii isolates collected from patients admitted to the Shahid Motahari and Taleghani Hospitals in Tehran during 2013-14. Antibiotic susceptibility tests (AST) and minimal inhibitory concentration (MIC) was determined by broth micro dilution methods according to CLSI 2014 guidelines. The frequency of efflux pump adeRS and OXA-23 genes were detected by PCR and further sequencing. Results: The resistance of A. baumannii isolates to tested antibiotics was 100% to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole and piperacillin/tazobactam, 97% to imipenem, 94% to gentamicin, 83% to amikacin, 76% to tetracycline, and 0.0% to colistin. The MIC of 58 (96.6%) strains to imipenem was highly decreased in the presence of efflux pump inhibitor (PaβN), by 4 to 64 folds. The adeR and adeS genes were detected in 36 (60%) and 59 (98.3%), respectively and the frequency of OXA-23 gene was 57 (95%) of isolates. Conclusion: Existence of adeRS and OXA-23 genes in more than 50% of A. baumannii isolates in this study shows the presumptiverole of efflux pump in simultaneous of carbapenemase production. Therefore, using new strategies are required in order to stop the vertical or horizontal exchanges mentioned genes from the resistant A. baumannii isolates to sensitive strains.

Este artigo tem como objetivo compreender as justificações matemáticas de alunos portugueses, do 5.º ano, na validação de uma conjetura sobre propriedades de triângulos, no contexto de uma experiência de ensino que privilegiou uma abordagem de ensino exploratório. A metodologia de pesquisa é de natureza qualitativa, com uma recolha de dados que incidiu nas produções escritas dos alunos nas quais estes procuram validar ou refutar uma conjetura, assim como no registo vídeo de alguns momentos de discussão coletiva. A análise das justificações dos alunos adotou um referencial baseado em Balacheff (1988) e Harel e Sowder (1998), com três níveis. Os resultados mostram que as justificações de conjeturas dos alunos situam-se nos níveis 2 e 3 do modelo adotado, ou seja, baseiam-se em desenhos, gestos ou verificação aleatória de alguns casos e na justificação que recorre a exemplos cuidadosamente selecionados.

Neste trabalho, discutimos a prática de uma Comunidade de Professores de Matemática no empreendimento Análise de Tarefas Estatísticas (ATE), abrangendo, particularmente, medidas de tendência central. O objetivo que norteia a investigação é compreender e explicitar: Que aspectos do conhecimento estatístico para ensinar se salientam no empreendimento? Que elementos do empreendimento contribuem para isso? Os resultados revelaram que reflexões compartilhadas e significados negociados no desenvolvimento do empreendimento promoveram uma (re)significação para os professores do conhecimento estatístico necessário para ensinar. Salientaram-se, como elementos favorecedores da emergência desses aspectos, as características das tarefas analisadas e sua relação com a aprendizagem dos alunos, a dinâmica que suportou o empreendimento e as ações do formador. Dessa forma, o ATE configurou uma prática vantajosa ao desenvolvimento profissional dos professores na Educação Estatística.

O presente artigo tem por finalidade a apresentação do modelo de formação inicial de professores vigente em Portugal na sequência do enquadramento proporcionado pelo chamado processo de Bolonha. Procuraremos aqui traçar as principais características desse modelo, aproveitando para refletir sobre alguns aspetos da sua concretização, tomando como exemplo o caso da Universidade de Lisboa. Refletiremos, ao longo do texto, sobre as soluções encontradas por esse modelo para alguns dos grandes dilemas associados historicamente à formação de professores.

Neste estudo debruçamo-nos sobre o conhecimento para ensinar investigações estatísticas de futuros professores do 3.º ciclo do ensino básico e do ensino secundário, tendo por base um quadro teórico que articula dois domínios: o conhecimento estatístico para ensinar e o pensamento estatístico. Os resultados mostram: i) a pertinência do quadro teórico adotado, podendo constituir uma referência para a construção de situações a explorar na Didática da Estatística, e para colocar em evidência aspetos importantes do conhecimento estatístico para ensinar que os futuros professores estão a desenvolver; e ii) a potencialidade da discussão de episódios de sala de aula, na formação inicial de professores.

This study aims to understand the knowledge of inquiry-based teaching that prospective mathematics teachers reveal when analysing a multimedia case featuring one mathematics teacher´s practice in one 7th grade lesson. Data analysis focused on individual reflections that prospective teachers had written, covering four major points: the nature of the task, articulation and purpose of the lesson phases, the teacher’s role in inquiry-based teaching, and anticipated challenges. The results show that the use of the multimedia case enabled prospective teachers to develop an understanding of various dimensions of inquiry teaching practice and its complexity, while they simultaneously began to predict specific difficulties they would face in their future professional practice. Significant elements of a dialogical perspective of learning also emerged from the study, as the prospective teachers recognize the central roles of language in knowledge construction, and of the interaction between teacher and student and among the students, in different moments of the lesson.

Apresentamos e discutimos resultados preliminares relativos à caracterização e evolução dos procedimentos de alunos do 3.º ano quando resolvem tarefas de multiplicação. Estes inserem-se numa investigação que pretende compreender como os alunos desenvolvem o sentido de número, nos aspetos associados à multiplicação, no âmbito de uma trajetória de aprendizagem. A análise das produções dos alunos e episódios relativos às discussões coletivas revela grande diversidade de procedimentos. Evidencia também a sua evolução, verificando-se, em certos casos, o retorno a procedimentos menos potentes, associado a particularidades das tarefas.

The ability for plant regeneration from dedifferentiated cells opens up the possibility for molecular bioengineering to produce crops with desirable traits. Developmental and environmental signals that control cell totipotency are regulated by gene expression via dynamic chromatin remodeling. Using a mass spectrometry-based approach, we investigated epigenetic changes to the histone proteins during callus formation from roots and shoots of Arabidopsis thaliana seedlings. Increased levels of the histone H3.3 variant were found to be the major and most prominent feature of 20-day calli, associated with chromatin relaxation. The methylation status in root- and shoot-derived calli reached the same level during long-term propagation, whereas differences in acetylation levels provided a long-lasting imprint of root and shoot origin. On the other hand, epigenetic signs of origin completely disappeared during 20 days of calli propagation in the presence of histone deacetylase inhibitors (HDACi), sodium butyrate, and trichostatin A. Each HDACi affected the state of post-translational histone modifications in a specific manner; NaB-treated calli were epigenetically more similar to root-derived calli, and TSA-treated calli resembled shoot-derived calli.

Hydroponic experiments were performed to examine the effect of prolonged sulfate limitation combined with cadmium (Cd) exposure in Arabidopsis thaliana and a potential Cd hyperaccumulator, Nicotiana tabacum. Low sulfate treatments (20 and 40 µM MgSO 4 ) and Cd stress (4 µM CdCl 2 ) showed adverse effects on morphology, photosynthetic and biochemical parameters and the nutritional status of both species. For example, Cd stress decreased NO 3 - root content under 20 µM MgSO 4 to approximately 50% compared with respective controls. Interestingly, changes in many measured parameters, such as chlorophyll and carotenoid contents, the concentrations of anions, nutrients and Cd, induced by low sulfate supply, Cd exposure or a combination of both factors, were species-specific. Our data showed opposing effects of Cd exposure on Ca, Fe, Mn, Cu and Zn levels in roots of the studied plants. In A. thaliana, levels of glutathione, phytochelatins and glucosinolates demonstrated their distinct involvement in response to sub-optimal growth conditions and Cd stress. In shoot, the levels of phytochelatins and glucosinolates in the organic sulfur fraction were not dependent on sulfate supply under Cd stress. Altogether, our data showed both common and species-specific features of the complex plant response to prolonged sulfate deprivation and/or Cd exposure., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Organic ammonium salts of N-(2-benzoyloxyethyl)-alkyldimethylammonium bromide (BCHn-1) type are formed by the homological series Ar-COO(CH2)2-N+(CH3)2CnH2a + 1.Br-, whose structure contains a biodegradably labile ester bond, on the basis of which they rank among disinfectants and antiseptics of soft character. They are preferentially biotransformed hydrolytically to produce benzoic acid and substituted choline. The rapidity of enzymatic hydrolysis depends on the chemical structure (the length of the aliphatic chain on the ammonium nitrogen), it increases up to the number of 10 nitrogens of the aliphatic chain, and it rapidly decreases with further prolongation. The paper aimed to demonstrate the catalytic activity of butyrylcholinesterase on the enzymatic hydrolysis of selected organic ammonium salts in the medium of the microsomal fraction of the rat liver on the basis of inhibitory kinetic studies with physostigmine, a cholinesterase inhibitor. The product of enzymatic hydrolysis of BCHn-1, benzoic acid, was determined after extraction with chloroform from the acid medium by means of HPLC analysis with the use of the internal standard p-iodobenzoic acid at the wavelength of 228 nm. Kinetic parameters K(M) and VMAX were evaluated following Lineweaver-Burke using the method of linear regression analysis. The specific activity of butyrylcholinesterase (E.C.3.1.1.8) in the enzymatic hydrolytic process of BCHn-1 was significantly influenced by the presence of physostigmine, which was manifested by increased K(M), KI, and IC50 values in the investigated enzymatic process of selected substrates of the homological series BCHn-1, and by decreased VMAX and rate constants.

The study evaluated the rate and kinetics of enzymatic hydrolysis of N-(2-benzoyloxyethyl)-alkyl-dimethylammonium bromides, potential easily biodegradable disinfectants of soft character. The products of enzymatic hydrolysis of the substrates under study, catalysed by microsomal esterase, included substituted substrates choline and benzoic acid which, as a hydrolytic product, was essayed by HPLC. The effect of the length of the alkyl chain of the individual homologues on the rate of enzymatic hydrolysis and their affinity to microsomal esterase of the rat liver and lung in vitro was examined. The structural modification (varying length of the aliphatic chain on the ammonium nitrogen of these compounds) was found to significantly influence the kinetics of enzymatic hydrolysis of the esteric bond. From the viewpoint of the rate of enzymatic hydrolysis no significant inter-organ variability was observed: in the liver as well as the lung the dependence of the rate of enzymatic hydrolysis on the length of the aliphatic chain possesses the shape of a falling hyperbole with the maxima for BCH2 > BCH4 > BCH8 = BCH10. The specific activity of both esterases ranges within 0.2-3.5 nmol.min-1.mg-1. From the viewpoint of affinity, a marked inter-organ difference was manifested by 10 times higher affinity of the substrates to the lung microsomal esterase in comparison with the liver one. The effect of the length of the alkyl of the individual homologues on the affinity is of a non-linear character also in this case. In both organs, a certain correlation was found between the rate of enzymatic hydrolysis and affinity to microsomal esterases.

Dokloxytepin in the medium of the induced monooxygenase system of the microsomal fraction of the liver of the rat, rabbit and mice is metabolized into three metabolites: two identical, i.e., N-oxide and 5-sulfoxide, and a third different one. In the rat and rabbit it is the hitherto unknown metabolite M1, and in the mouse S,N-dioxide of dokloxytepin. The metabolites were identified by thin-layer chromatography by comparing with synthetic standards.

Oxyprothepine in the medium of the microsomal fraction of the rat liver is biotransformed to the corresponding metabolites originating by oxidation of both sulfur atoms. The formation of S-oxygenation products is bound to the presence of NADPH, with a marked synergism with NADH. Induction with phenobarbital increases the formation of the individual metabolites.

A new procedure for obtaining rat lung microsomes essentially free of interfering hemoproteins has been developed. The method includes Sepharose 2B column chromatography of the 12,000 X g supernatant of lung homogenates, followed by ultracentrifugation of the material eluted in the void volume. Microsomes isolated in this manner contain specific levels of cytochromes b5 and P-450 and of NADPH-cytochrome c reductase that are among the highest ever reported for a rat lung microsomal fraction. After treatment of rats with 3-methylcholanthrene, the specific content of cytochrome P-450 in lung microsomes is doubled and that of cytochrome b5 increases 1.5 times. Several spectral differences between hepatic and lung microsomal cytochrome P-450 are apparent. In lung microsomes, the maximum of the reduced CO-bound cytochrome complex in a difference spectrum is at 453 nm for the noninduced hemoprotein and shifts to 451 nm after 3-methylcholanthrene induction. In contrast, no significant change in the ethylisocyanide difference spectra of reduced microsomes is obtained after induction; moreover, the spectra obtained with induced and noninduced cytochrome P-450 are similar to the one shown by hepatic microsomes from polycyclic hydrocarbon-treated rats. Furthermore, spectrophotometric studies on n-octylamine binding to control and induced lung cytochrome P-450 yielded results different from those previously obtained with rabbit liver microsomes. It is concluded that the cytochrome P-450 present in rat lung microsomes before and after 3-methylcholanthrene treatment of the animals is distinctly different from the liver hemoprotein.