2,612 research outputs found
Suscetibilidade a inseticidas e parasitismo natural por Trichogramma sp. em Traça-do-tomateiro.
A traça-do-tomateiro é uma praga importante do tomate e inseticidas são freqüentemente empregados para o seu controle. Porém, devido ao impacto ambiental e a possibilidade de resistência aos produtos utilizados para o controle do inseto, o controle biológico com o uso de Trichogramma pode ser uma alternativa para eliminar os dois problemas. Neste trabalho foi avaliada em bioensaios de laboratório a eficiência da dose recomendada de inseticidas do grupo químico dos organofosforados, piretróides e benzoiluréia para o controle da traça-do-tomateiro. Foi também avaliada a ocorrência natural de Trichogramma sp. em áreas pulverizadas ou não pulverizadas com inseticidas. A ocorrência do parasitismo natural foi determinada por meio da coleta de folhas em campo contendo ovos de traça-do-tomateiro, a fim de determinar, em avaliações de laboratório, a percentagem de ovos parasitados. Os resultados mostraram que todos os inseticidas testados causaram uma mortalidade de larvas menor que 70%, o que sugere uma eficiência reduzida dos produtos. O parasitóide Trichogramma sp. ocorreu naturalmente em todas as áreas, mas a percentagem de parasitismo foi menor nas áreas pulverizadas. Outros estudos devem ser realizados a fim de avaliar o potencial dos parasitóides locais, provavelmente mais bem adaptados as condições locais, para o controle da traça-do-tomateiro. Se esses organismos forem efetivos, o uso de inseticidas em lavouras de tomate pode ser reduzido.bitstream/CNPH-2009/33237/1/bpd_28.pd
Construção em altura com MLCC
Com o objetivo de dar resposta aos problemas identificados nas soluções e propostas já conhecidas, e como parte resultante de uma investigação sobre a construção em altura com MLCC a decorrer na Escola de Engenharia da Universidade do Minho (EEUM), encontra-se em desenvolvimento o Urban Timber System (UT System)
Small violations of unitarity, the phase in Bs mixing and visible t->cZ decays at the LHC
We show that it is possible to accommodate the observed size of the phase in
--, mixing in the framework of a model with violation of
unitarity. This violation is associated to the presence of a new
isosinglet quark , which mixes both with and and has a mass
not exceeding 500 GeV. The crucial point is the fact that this framework allows
for of order , to be
contrasted with the situation in the Standard Model, where is
constrained to be of order . We point out that this scenario implies
rare top decays at a rate observable at the LHC and
significantly different from unity. In this framework, one may also account for
the observed size of -- mixing without having to invoke long
distance contributions. It is also shown that in the present scenario, the
observed size of -- mixing constrains
to be of order
, which is significantly smaller than what is allowed in generic
models with violations of unitarity.Comment: 20 pages. References added. Additional observables considered,
updated numerical examples, conclusions unchange
Jarlskog-like invariants for theories with scalars and fermions
Within the framework of theories where both scalars and fermions are present,
we develop a systematic prescription for the construction of CP-violating
quantities that are invariant under basis transformations of those matter
fields. In theories with Spontaneous Symmetry Breaking, the analysis involves
the vevs' transformation properties under a scalar basis change, with a
considerable simplification of the study of CP violation in the scalar sector.
These techniques are then applied in detail to the two Higgs-doublet model with
quarks. It is shown that there are new invariants involving scalar-fermion
interactions, besides those already derived in previous analyses for the
fermion-gauge and scalar-gauge sectors.Comment: 12 pages, Latex, no figure
CP-odd Weak Basis Invariants for Neutrino Mass Matrices with a Texture Zero and a Vanishing Minor
We construct the -odd weak basis invariants in the flavor basis for all
the phenomenologically viable neutrino mass matrices with a texture zero and a
vanishing minor and, also, find the necessary and sufficient conditions for
invariance . We examine the interrelationships between different -odd
weak basis invariants for these texture structures and investigate their
implications for Dirac- and Majorana-type violation.Comment: To appear in Journal of Physics
Removal of Cr(VI) from aqueous solutions by a bacterial biofilm supported on zeolite : optimisation of the operational conditions and scale-up of the bioreactor
The aim of this study was to investigate the feasibility of a bioreactor system and its scale-up to remove Cr(VI) from solution. The bioreactor is based on an innovative process that combines bioreduction of Cr(VI) to Cr(III) by the bacterium Arthrobacter viscosus and Cr(III) sorption by a specific zeolite. Batch studies were conducted in a laboratory-scale bioreactor, taking into account different operating conditions. Several variables, such as biomass concentration, pH and zeolite pre-treatment, were evaluated to increase removal efficiency. The obtained results suggest that the Cr removal efficiency is improved when the initial biomass concentration is approximately 5 g L–1 and the pH in the system is maintained at an acidic level. Under the optimised conditions, approximately 100 % of the Cr(VI) was removed. The scale-up of the developed biofilm process operating under the optimised conditions was satisfactorily tested in a 150-L bioreactor.Xunta de Galicia - programa Angeles Alvariñ
Mixing in the Presence of Isosinglet Quarks
We analyse transitions in the framework of a minimal extension
of the Standard Model where either a or a isosinglet quark is
added to the standard quark spectrum. In the case of a isosinglet
quark, it is shown that there is a significant region of parameter space where
mixing is sufficiently enhanced to be observed at the next
round of experiments. On the contrary, in the case of a isosinglet
quark, it is pointed out that obtaining a substancial enhancement of mixing, while complying with the experimental constraints on rare
kaon decays, requires a contrived choice of parameters.Comment: 10 pages plus four figures. The figures are not included but are
available upon reques
Parameterizing Majorana Neutrino Couplings in the Higgs Sector
Nonzero masses for the active neutrinos - regardless of their nature or
origin - arise only after electroweak symmetry breaking. We discuss the
parameterization of neutrino couplings to a Higgs sector consisting of one
SU(2)_L scalar doublet and one SU(2)_L scalar triplet, and allow for
right-handed neutrinos whose Majorana mass parameters arise from the vacuum
expectation value of a Standard Model scalar singlet. If the neutrinos are
Majorana fermions, all Yukawa couplings can be expressed as functions of the
neutrino mass eigenvalues and a subset of the elements of the neutrino mixing
matrix. In the mass basis, the Yukawa couplings are, in general, not diagonal.
This is to be contrasted to the case of charged-fermions or Dirac neutrinos,
where couplings to the Higgs-boson are diagonal in the mass basis and
proportional only to the fermion masses. Nonetheless, all physically
distinguishable parameters can be reached if all neutrino masses are
constrained to be positive, all mixing angles constrained to lie in the first
quadrant (theta in [0,pi/2]), and all Majorana phases to lie in the first two
quadrants (phi in [0,pi]), as long as all Dirac phases vary within the entire
unit circle (delta in [0,2pi}). We discuss several concrete examples and
comment on the Casas-Ibarra parameterization for the neutrino Yukawa couplings
in the case of the type-I Seesaw Lagrangian.Comment: 13 pages, 2 eps figure
The impact of media pressure on corporate sustainability in the cement industry: a Portuguese case study
In this study we examine the sustainability reporting practices and sustainability strategies of a leading Portuguese cement company. The Portuguese cement industry had to deal since 1997 with scrutiny and pressure because of its involvement in co-incineration of hazardous industrial waste. Grounded on a lens of analysis combining legitimacy theory and media agenda-setting theory and based on a content analysis of sustainability reports and semi-structured interviews, we analyse the strategies used by the company to deal with said scrutiny and pressure and present its sustainability performance. Media pressure does seem to have impacted sustainability reporting and sustainability strategies as tools for the company to restore its legitimacy. Findings generally suggest that strategies of communication designed to legitimate the company actions were used. In particular, we suggest that the company managed its legitimacy by using simultaneously two sustainability reporting strategies: one of image enhancement and other of avoidance of threatening topics.info:eu-repo/semantics/publishedVersio
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