Search for Neutral Heavy Leptons Produced in Z Decays

Weak isosinglet Neutral Heavy Leptons ($\nu_m$) have been searched for using data collected by the DELPHI detector corresponding to $3.3\times 10^{6}$ hadronic~Z$^{0}$ decays at LEP1. Four separate searches have been performed, for short-lived $\nu_m$ production giving monojet or acollinear jet topologies, and for long-lived $\nu_m$ giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio $BR($Z$^0\rightarrow \nu_m \overline{\nu})$ of about $1.3\times10^{-6}$ at 95\% confidence level for $\nu_m$ masses between 3.5 and 50 GeV/$c^2$. Outside this range the limit weakens rapidly with the $\nu_m$ mass. %Special emphasis has been given to the search for monojet--like topologies. One event %has passed the selection, in agreement with the expectation from the reaction: %$e^+e^- \rightarrow\ell \bar\ell \nu\bar\nu$. The results are also interpreted in terms of limits for the single production of excited neutrinos

Search for Lepton Flavour Number violating Z0Z^0-Decays

A search for lepton flavour number violating $Z^0$ decays in the channels \begin{center} $Z^0\rightarrow \mu\tau$,\\ $Z^0\rightarrow e\tau$, \\ $Z^0\rightarrow e\mu$, \\ \end{center} using the DELPHI detector with data collected during the 1991--94 LEP runs, is described. No signal was found. Upper limits at 95\% confidence level for the respective branching fractions of $1.2\times 10^{-5}$, $2.2\times 10^{-5}$, and $0.25\times 10^{-5}$, were obtained

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Morphological and physiological responses of açaí seedlings subjected to different watering regimes

ABSTRACT Seedlings of açaí obtained from plant material native to floodplains (from Laranjeira and Muaná) and adapted to upland areas (cv. BRS-Pará and ecotype Hideo) were cultivated between March and October 2013 in a greenhouse, to test the hypothesis that water requirement for seedling production varies according to the origin of plant material. The seedlings were subjected to watering regimes corresponding to 40, 70, 100 and 130% of field capacity. Regardless of plant material, the production of vigorous seedlings was feasible only under irrigation of 100 and 130% of field capacity. The seedlings produced under 130% of field capacity showed higher plant height, stem diameter, number of leaves, total leaf area, leaf and root biomass, total plant biomass and root/shoot ratio than those produced under 100% of field capacity. The former also showed higher net CO2 assimilation rate, lower stomatal conductance and transpiration and higher instantaneous water use efficiency. In conclusion, the water requirement to produce vigorous seedlings of açaí does not vary within plant material and more vigorous seedlings are produced under irrigation of 130% of field capacity

Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary Treatments

Fenton-chemistry-based detemplation combined with secondary treatments offers options to tune the hierarchical porosity of SBA-15. This approach has been studied on a series of SBA-15 mesophases and has been compared to the conventional calcination. The as-synthesized and detemplated materials were studied with regard to their template content (TGA, CHN), structure (SAXS, TEM), surface hydroxylation (BlinCarterets approach), and texture (high-resolution argon physisorption). Fenton detemplation achieves 99% of template removal, leading to highly hydroxylated materials. The structure is better preserved when a secondary treatment is applied after the Fenton oxidation, due to the intense capillary forces during drying in water. Two successful approaches are presented: drying in a low-surface-tension solvent (such as n-BuOH) and a hydrothermal stabilization to further condense the structure and make it structurally more robust. Both approaches give rise to remarkably low structural shrinkage, lower than calcination and the direct water-dried Fenton. Interestingly, the derived textural features are remarkably different. The n-BuOH exchange route gives rise to highly hierarchical structures with enhanced interconnecting pores and the highest surface areas. The hydrothermal stabilization produces large-pore SBA-15 structures with high pore volume, intermediate interconnectivity, and minimal micropores. Therefore, the hierarchical texture can be fine-tuned in these two fashions while the template is removed under mild conditions

A precise measurement of the Bd0B^{0}_{d} meson lifetime using a new technique

From data recorded by DELPHI between 1991 and 1994, which correspond to 3.2 million hadronic \mbox{Z}^0 decays, a measurement of the \Bdb meson lifetime has been performed based on the inclusive reconstruction of $3520 \pm 150$ semileptonic decays of the type \bc \Bdb \rightarrow \Dstarp ~X~\ell^-~ \overline{\nu_{\ell}}, \ec The result is: \bc \tau(\Bdb) = 1.537~\pm 0.041 (stat.) \pm 0.039 (syst.) ~\mathrm{ps}. \ec \noindent The contribution to the systematic uncertainty which depends on external errors is $\pm 0.014~\mathrm{ps}$