Arithmetica da infancia (1890) de Joaquim Maria de Lacerda e o conteúdo da prova dos noves

https://aplicacoes.ifs.edu.br/periodicos/index.php/caminhos_da_educacao_matematica/article/view/92Este artigo está inserido no campo da história da educação matemática e busca compreender e analisar um conteúdo de ensino de aritmética, a prova dos noves, prescrito no livro Arithmetica da Infancia, autoria de Joaquim Maria de Lacerda, publicado em 1890. Estas análises se apoiam nos pressupostos da história cultural, particularmente nas referências de Chervel (1990) e Choppin (2004). Primeiramente o artigo apresenta algumas informações acerca do autor e a destinação da obra. Em seguida, investiga-se a forma como o autor apresenta a prova dos nove no tópico que trata das quatro operações fundamentais. Constata-se que a prova dos nove, assim como também a prova real, aparecem no final da seção das operações fundamentais: adição, subtração, multiplicação e divisão. Para o autor, as provas são definidas como modos de verificação dos cálculos

Ageing of alkylthiol-stabilized gold nanoparticles

The ageing of spherical gold nanoparticles having 6-nm-diameter cores and a ligand shell of dodecanethiol is investigated under different storage conditions. Losses caused by agglomeration and changes in optical particle properties are quantified. Changes in colloidal stability are probed by analytical centrifugation in a polar solvent mixture. Chemical changes are detected by elementary analysis of particles and solvent. Fractionation occurs under all storage conditions. Ageing is not uniform but broadens the property distributions of the particles. Small-number statistics in the ligand shell density and the morphological heterogeneity of particles are possible explanations. Washing steps exacerbate ageing, a process that could not be fully reversed by excess ligands. Dry storage is not preferable to storage in solvent. Storage under inert argon atmosphere reduces losses more than all other conditions but could not prevent it entirely

Fibre-optic metadevice for all-optical signal modulation based on coherent absorption

Recently, coherent control of the optical response of thin films of matter in standing waves has attracted considerable attention, ranging from applications in excitation-selective spectroscopy and nonlinear optics to demonstrations of all-optical image processing. Here we show that integration of metamaterial and optical fibre technologies allows the use of coherently controlled absorption in a fully fiberized and packaged switching metadevice. With this metadevice, that controls light with light in a nanoscale plasmonic metamaterial film on an optical fibre tip, we provide proof-of-principle demonstrations of logical functions XOR, NOT and AND that are performed within a coherent fully fiberized network at wavelengths between 1530 nm and 1565 nm. The metadevice performance has been tested with optical signals equivalent to a bitrate of up to 40 Gbit/s and sub-milliwatt power levels. Since coherent absorption can operate at the single photon level and also with 100 THz bandwidth, we argue that the demonstrated all-optical switch concept has potential applications in coherent and quantum information networks.Comment: 9 pages, 6 figure