Excellent mathematical achievement in PISA: results for Spain and Portugal

Se realiza un análisis longitudinal para la competencia matemática de los resultados de España y Portugal en las evaluaciones PISA en sus ediciones de los años 2000, 2003, 2006, 2009, 2012 y 2015. PISA es el mecanismo utilizado por la OCDE para evaluar las competencias clave de los sistemas educativos. Es por ello que, a partir de sus conclusiones, dichos países cuentan con un marco de actuación para el desarrollo de políticas educativas propias de la mejora de sus prácticas educativas, en este caso para la competencia matemática, incluidas las dirigidas a alumnos con rendimiento matemático excelente.It is a longitudinal analysis for mathematical competence results from Spain and Portugal in the PISA assessments in their editions of the years 2000, 2003, 2006, 2009, 2012 and 2015. PISA is the mechanism used by the OECD to assess the key competences of the education systems. That is why, from its conclusions, such countries with a framework for the development of own educational policies for the improvement of their educational practices, in this case for mathematical competence, including those aimed at students with excellent mathematical performance.info:eu-repo/semantics/publishedVersio

Integrated complementary graphene inverter

The operation of a digital logic inverter consisting of one p- and one n-type graphene transistor integrated on the same sheet of monolayer graphene is demonstrated. The type of one of the transistors was inverted by moving its Dirac point to lower gate voltages via selective electrical annealing. Boolean inversion is obtained by operating the transistors between their Dirac points. The fabricated inverter represents an important step towards the development of digital integrated circuits on graphene.Comment: 4 pages, 4 figure

Desenvolvimento de uma Interface Cérebro-Computador Não Invasiva Baseada em Potenciais Evocados Visuais de Regime Permanente Aplicada à Comunicação Alternativa e Robô de Telepresença

Uma parcela da população é composta por pessoas que são acometidas de doenças ou vítimas de acidentes graves que as impossibilitam de interagir e se comunicar. Novas tecnologias têm surgido para prover a essas pessoas um canal de comunicação alternativo através de sinais cerebrais. Esses sistemas são conhecidos como Interfaces Cérebro-Computador (ICCs). Este trabalho descreve o desenvolvimento de uma ICC baseada no paradigma de Potenciais Evocados Visuais de Regime Permanente (Steady State Visual Evoked Potential - SSVEP) aplicada à Comunicação Alternativa e Robô de Telepresença. A interface foi construída para quatro comandos de seleção atráves de estímulos visuais desenvolvidos em um software utilizando a biblioteca gráfica OpenGL e executados em frequências distintas (5,6Hz, 6,4Hz, 6,9Hz e 8,0Hz). Todos os voluntários avaliados nos testes utilizando o sistema online conseguiram completar as tarefas propostas com uma taxa de acerto média de 88,3% ± 5,4%, tempo de classificação de 5,6s ± 0,5s e ITR média de 14,2 bits/min ± 3,5 bits/min, não necessitando de treinamento e utilizando apenas um canal para aquisição do sinal eletroencefalográfico. Os resultados demonstraram a possibilidade da construção de uma ICC que poderá ser utilizada nos futuros projetos de tecnologias assistivas desenvolvidos no Laboratório de Automação Inteligente da Universidade Federal do Espírito Santo (LAI-UFES)

Solving math problems by regular and high-ability students

O desempenho cognitivo e académico de alunos com altas capacidades nem sempre é entendido em termos dos processos cognoscitivos envolvidos na sua aprendizagem. Na ausência dessa análise, psicólogos e professores estão limitados na real avaliação das competências destes alunos e na implementação de práticas de ensino que atendam às suas especificidades e necessidades. Partindo desta realidade, procura-se averiguar como um grupo de alunos de Portugal e de Espanha, com idades entre os 9 e os 12 anos, resolvem problemas. A amostra foi constituída para efeitos comparativos por alunos com elevado potencial intelectual e por alunos regulares. Os dados obtidos mostram um superior desempenho por parte dos alunos com alta capacidade, mesmo controlando o efeito de outras variáveis.The cognitive and academic performance of high ability students is not always understood in terms of the cognitive processes involved in their learning. In the absence of this analysis, psychologists and teachers are limited in the real evaluation of the competences of these students and in the implementation of teaching practices that meet their specificities and needs. Starting from this reality, we try to find out how a group of students from Portugal and Spain, between the ages of 9 and 12, solve math problems. The sample was composed for comparison purposes by students with high intellectual potential and by regular students. The data obtained show a superior performance on the part of the students with high capacity, even controlling the effect of other variables.info:eu-repo/semantics/publishedVersio

The ex vivo neurotoxic, myotoxic and cardiotoxic activity of cucurbituril-based macrocyclic drug delivery vehicles

The cucurbituril family of drug delivery vehicles have been examined for their tissue specific toxicity using ex vivo models. Cucurbit[6]uril (CB[6]), cucurbit[7]uril (CB[7]) and the linear cucurbituril-derivative Motor2 were examined for their neuro-, myo- and cardiotoxic activity and compared with β-cyclodextrin. The protective effect of drug encapsulation by CB[7] was also examined on the platinum-based anticancer drug cisplatin. The results show that none of the cucurbiturils have statistically measurable neurotoxicity as measured using mouse sciatic nerve compound action potential. Cucurbituril myotoxicity was measured by nerve-muscle force of contraction through chemical and electrical stimulation. Motor2 was found to display no myotoxicity, whereas both CB[6] and CB[7] showed myotoxic activity via a presynaptic effect. Finally, cardiotoxicity, which was measured by changes in the rate and force of right and left atria contraction, was observed for all three cucurbiturils. Free cisplatin displays neuro-, myo- and cardiotoxic activity, consistent with the side-effects seen in the clinic. Whilst CB[7] had no effect on the level of cisplatin's neurotoxic activity, drug encapsulation within the macrocycle had a marked reduction in both the drug's myo- and cardiotoxic activity. Overall the results are consistent with the relative lack of toxicity displayed by these macrocycles in whole animal acute systemic toxicity studies and indicate continued potential of cucurbiturils as drug delivery vehicles for the reduction of the side effects associated with platinum-based chemotherapy

The ex vivo neurotoxic, myotoxic and cardiotoxic activity of cucurbituril-based macrocyclic drug delivery vehicles

The cucurbituril family of drug delivery vehicles have been examined for their tissue specific toxicity using ex vivo models. Cucurbit[6]uril (CB[6]), cucurbit[7]uril (CB[7]) and the linear cucurbituril-derivative Motor2 were examined for their neuro-, myo- and cardiotoxic activity and compared with β-cyclodextrin. The protective effect of drug encapsulation by CB[7] was also examined on the platinum-based anticancer drug cisplatin. The results show that none of the cucurbiturils have statistically measurable neurotoxicity as measured using mouse sciatic nerve compound action potential. Cucurbituril myotoxicity was measured by nerve-muscle force of contraction through chemical and electrical stimulation. Motor2 was found to display no myotoxicity, whereas both CB[6] and CB[7] showed myotoxic activity via a presynaptic effect. Finally, cardiotoxicity, which was measured by changes in the rate and force of right and left atria contraction, was observed for all three cucurbiturils. Free cisplatin displays neuro-, myo- and cardiotoxic activity, consistent with the side-effects seen in the clinic. Whilst CB[7] had no effect on the level of cisplatin’s neurotoxic activity, drug encapsulation within the macrocycle had a marked reduction in both the drug’s myo- and cardiotoxic activity. Overall the results are consistent with the relative lack of toxicity displayed by these macrocycles in whole animal acute systemic toxicity studies and indicate continued potential of cucurbiturils as drug delivery vehicles for the reduction of the side effects associated with platinum-based chemotherapy

Atrazine bound residues formation and dissipation in subtropical soil under swine wastewater application

The effects of swine wastewater on atrazine dissipation and formation of bound residues in subtropical clay soil were investigated in this study. The experiment was carried out in laboratory, under room conditions, where samples of Rhodic Hapludox soil received 168.61 mg kg-1 of atrazine and were incubated for 60 days in the following treatments: T1 (sterilized soil + swine wastewater), T2 (sterilized soil + distilled water), T3 (Non sterilized soil + swine wastewater) and T4 (Non sterilized soil + distilled water). The extractable residues and bound residues of atrazine were extracted and analyzed by high performance liquid chromatography. The results showed no effect of swine wastewater on atrazine dissipation. However, the addition of swine wastewater favored the increase of bound residues, which can increase the persistence of atrazine in the environment and reduce its bioavailabilityinfo:eu-repo/semantics/publishedVersio

Molecular mechanisms underlying differential odor responses of a mouse olfactory receptor

The prevailing paradigm for G protein-coupled receptors is that each receptor is narrowly tuned to its ligand and closely related agonists. An outstanding problem is whether this paradigm applies to olfactory receptor (ORs), which is the largest gene family in the genome, in which each of 1,000 different G protein-coupled receptors is believed to interact with a range of different odor molecules from the many thousands that comprise “odor space.” Insights into how these interactions occur are essential for understanding the sense of smell. Key questions are: (i) Is there a binding pocket? (ii) Which amino acid residues in the binding pocket contribute to peak affinities? (iii) How do affinities change with changes in agonist structure? To approach these questions, we have combined single-cell PCR results [Malnic, B., Hirono, J., Sato, T. & Buck, L. B. (1999) Cell 96, 713–723] and well-established molecular dynamics methods to model the structure of a specific OR (OR S25) and its interactions with 24 odor compounds. This receptor structure not only points to a likely odor-binding site but also independently predicts the two compounds that experimentally best activate OR S25. The results provide a mechanistic model for olfactory transduction at the molecular level and show how the basic G protein-coupled receptor template is adapted for encoding the enormous odor space. This combined approach can significantly enhance the identification of ligands for the many members of the OR family and also may shed light on other protein families that exhibit broad specificities, such as chemokine receptors and P450 oxidases

CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS

Context. CARMENES is a stabilised, high-resolution, double-channel spectrograph at the 3.5 m Calar Alto telescope. It is optimally designed for radial-velocity surveys of M dwarfs with potentially habitable Earth-mass planets. Aims. We prepare a list of the brightest, single M dwarfs in each spectral subtype observable from the northern hemisphere, from which we will select the best planet-hunting targets for CARMENES. Methods. In this first paper on the preparation of our input catalogue, we compiled a large amount of public data and collected low-resolution optical spectroscopy with CAFOS at the 2.2 m Calar Alto telescope for 753 stars. We derived accurate spectral types using a dense grid of standard stars, a double least-squares minimisation technique, and 31 spectral indices previously defined by other authors. Additionally, we quantified surface gravity, metallicity, and chromospheric activity for all the stars in our sample. Results. We calculated spectral types for all 753 stars, of which 305 are new and 448 are revised. We measured pseudo-equivalent widths of Halpha for all the stars in our sample, concluded that chromospheric activity does not affect spectral typing from our indices, and tabulated 49 stars that had been reported to be young stars in open clusters, moving groups, and stellar associations. Of the 753 stars, two are new subdwarf candidates, three are T Tauri stars, 25 are giants, 44 are K dwarfs, and 679 are M dwarfs. Many of the 261 investigated dwarfs in the range M4.0-8.0 V are among the brightest stars known in their spectral subtype. Conclusions. This collection of low-resolution spectroscopic data serves as a candidate target list for the CARMENES survey and can be highly valuable for other radial-velocity surveys of M dwarfs and for studies of cool dwarfs in the solar neighbourhood.Comment: A&A, in pres