Search results for "mathematics"
showing 10 items of 22031 documents
Acoustic characterization of Silica aerogel clamped plates for perfect absorption purpose
2017
International audience; Silica aerogel has been widely studied as bulk material for its extremely low density and thermal conductivity. Plates or membranes made of this extremely soft materials exhibits interesting properties for sound absorption. A novel signal processing method for the characterization of an acoustic metamaterial made of silica aerogel clamped plates is presented. The acoustic impedance of a silica aerogel clamped plate is derived from the elastic theory for the flexural waves, while the transfer matrix method is used to model reflection and transmission coefficients of a single plate. Experimental results are obtained by using an acoustic impedance tube. The difference b…
Estimation of ADME Properties in Drug Discovery: Predicting Caco-2 Cell Permeability Using Atom-Based Stochastic and Non-stochastic Linear Indices
2007
The in vitro determination of the permeability through cultured Caco-2 cells is the most often-used in vitro model for drug absorption. In this report, we use the largest data set of measured P(Caco-2), consisting of 157 structurally diverse compounds. Linear discriminant analysis (LDA) was used to obtain quantitative models that discriminate higher absorption compounds from those with moderate-poorer absorption. The best LDA model has an accuracy of 90.58% and 84.21% for training and test set. The percentage of good correlation, in the virtual screening of 241 drugs with the reported values of the percentage of human intestinal absorption (HIA), was greater than 81%. In addition, multiple …
Interactions of amino acids with aluminum octacarboxyphthalocyanine hydroxide. Experimental and DFT studies
2017
The influence of albumin and amino acids (l-serine, glycine, l-histidine, l-tryptophan, l-cysteine) on the properties of aluminum octacarboxyphthalocyanine hydroxide (Al(OH)PcOC) was investigated in a phosphate buffer (pH 8.0). Particular attention was paid to the spectroscopic properties and photostability of Al(OH)PcOC. The effect of albumin or amino acids on the photodegradation of Al(OH)PcOC was examined in water using red light: 685 nm and daylight irradiation. Analysis of kinetic curves indicated that interaction with those molecules increases the photostability of Al(OH)PcOC. The molecular structure of Al(OH)PcOC complexes (in vacuum and in water) with axially or equatorially coordin…
Matei Visniec: aproximación a un universo dramático a través de sus animales
2014
Matei Visniec (1956) is an author from Romania, who uses both French and Romanian expression in his plays. The coordinates of his dramatic fictional universe bring together the absurd, the symbolic, the fantastic and the conflicts in the city of men, sometimes with accurate historical and current references. Animals, present onstage in many different ways, are very common in his plays. They constitute a strange wildlife between animal and human, between the real and the fantastic.Their presence in this theatrical universe fits into their symbolic aspect, which defies the imagination by means of what is enigmatic and incomprehensible; but it also falls into their committed side to the extent…
Accuracy combining different brands of implants and abutments
2013
Objective: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Study design: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-to- abutment fit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands,…
Associations between sleep deficit and academic achievement - triangulation across time and subject domains among students and teachers in TIMSS in N…
2022
Abstract Background Sufficient sleep is important to an individual’s health and well-being, but also for school achievement among adolescents. This study investigates the associations between sleepiness, sleep deficits, and school achievements among adolescents. Methods This trend study involved a representative sample of Norwegian adolescents based on the “Trends in International Mathematics and Science Study” (TIMSS), N = 4499 (2015) and N = 4685 (2019) and their teachers. The students were 9th graders from a Norwegian compulsory secondary school. The survey included questions on students’ sleepiness as students reported in 2019 and sleep deficits among students that limited teaching in c…
University Transitions and Gender: From Choice of Studies to Academic Career Development
2014
Based on the results of the authors' research using a case study of a Spanish university, the sociological component of gender is an important factor in building transitions at university. When the authors refer to university transitions they are talking about two periods. Firstly, they refer to the transition of undergraduate students from upper secondary education. The authors detect differences in the choices of studies, in the identification of professional models and in the university admission process. Secondly, they refer to the transition from research grant-holders to teaching and research staff. They explore the construction of social expectations and representations that researc…
From Graz to Göttingen: Neugebauer’s Early Intellectual Journey
2016
Otto Neugebauer’s early academic career was marked by a series of transitions. His interests shifted from physics to mathematics, and finally to the history of ancient mathematics and exact sciences. Yet even from his early years in Graz, Neugebauer was strongly attracted to the mathematical culture of Gottingen. When he arrived there in 1922, he quickly established a strong personal friendship with Richard Courant, the newly appointed Director of the Mathematics Institute. Neugebauer and Courant worked together closely up until 1933, when the Nazi government decimated the Gottingen scientific community. In this essay, Neugebauer’s historical work and his vision for a new approach to the st…
Integrating the Real and Virtual World for Academic Language Education in Second Life
2013
This chapter focuses on a Second Language Acquisition (SLA) study conducted in virtual worlds that could help teachers in terms of knowledge about acquisition processes, in which technology is integration between formal and non formal education. The research comprises of two studies strongly focused on the development of Italian oral language proficiency. It was held within Second Life® (SL™)1 in order to explore the affordances of public spaces to enhance Intercultural Communicative Competence (ICC)2 and to stimulate the oral production through learner’s engagement. Since 2007, a new pilot project, Café Italia, was developed by Carmela Dell’Aria (aka Misy Ferraris) in Second Life®. Startin…
Promoting children’s participation: the role of teachers in preschool and primary school learning sessions
2010
The aim of this study is to provide insights into the social construction of participation in joint activities in Finnish preschool and primary school classrooms. The article deals with two issues: How do teachers promote participation in a preschool classroom as compared with a primary school classroom? What similarities and differences are found? It also considers the question of how the similarities contribute to the continuity from preschool to primary school in terms of participation. Based on observation data insights are provided into the interactions between teachers and children by using extracts from teacher‐led learning sessions. The teachers used a diversity of strategies to pro…