2,872 research outputs found
A fileira das plantas aromáticas e medicinais em Portugal : transformação e distribuição
Esta comunicação insere-se no âmbito do projecto Agro nº 800 “ Rede Nacional
para a Conservação e Utilização de Plantas Aromáticas e Medicinais” e pretende
analisar a fileira PAM em Portugal, com o objectivo de conhecer os agentes
intervenientes, as operações técnicas realizadas, o grau de integração entre agentes, a
organização interna da fileira e suas articulações com o exterior.
Neste sentido foram efectuados inquéritos a produtores, transformadores e
distribuidores de PAM e seus derivados.
Aqui serão abordados, exclusivamente, os dados referentes à distribuição e
comercialização.
Os dados recolhidos mostram uma desarticulação quase total da fileira. Apesar
de se verificarem alguns casos de integração vertical, de modo geral, o grau de
integração entre a produção e os sectores de transformação e distribuição é muito ténue
e as relações comerciais caracterizam-se por uma ausência de vínculo contratual.
A produção nacional sofre uma forte concorrência externa, patente na
disparidade de preços das matérias-primas de origem nacional e estrangeira. Assim
sendo, verifica-se que a indústria transformadora praticamente não utiliza matéria-prima
de origem nacional o que constitui um estrangulamento à produção de PAM.
O sector da distribuição é o elemento mais dinâmico da fileira e o que mais
contribui para a geração de valor
Kinky D-branes and straight strings of open string tachyon effective theory
In this letter we construct the kink D1-brane super D-helix solution and its
T-dual the D2-brane supertube using the effective action of non-BPS tachyonic
D-branes . In the limit of zero angular momentum, both types of solutions
collapse to zero radius, giving rise respectively to a degenerate string
configuration corresponding to a particle travelling with the speed of light
and to a static straight string configuration. These solutions share all the
properties of fundamental strings and do not have the pathological behavior of
other solutions previously found in this context. A short discussion on the
``generalized gauge transformations'' suggested by Sen is used to justify the
validity of our approach.Comment: 10 pages, latex, typos corrected and references adde
Preoptic area activation and vasotocin involvement in the reproductive behavior of a weakly pulse-type electric fish, Brachyhypopomus gauderio
Social behavior exhibits a wide diversity among vertebrates though it is controlled by a conserved neural network, the social behavior network (SBN). The activity of the SBN is shaped by hypothalamic nonapeptides of the vasopressin-oxytocin family. The weakly electric fish Brachyhypopomus gauderio emits social electrical signals during courtship. Three types of vasotocin (AVT) cells occur in the preoptic area (POA), one of the SBN nodes. In this study, we aimed to test if POA neurons of the nucleus preopticus ventricularis anterior (PPa) and posterior (PPp), and in particular AVT+ cells, were activated by social stimuli using a 2-day behavioral protocol. During the first night, male-female dyads were recorded to identify courting males. During the second night, these males were divided in two experimental conditions: isolated and social (male with a female). Both AVT cells and the cellular activation of the POA neurons (measured by FOS) were identified. We found that the PPa of social males showed more FOS+ cells than the PPa of isolated males, and that the PPa had more AVT+ cells in social males than in isolated males. The double-immunolabeling for AVT and FOS indicated the activation of AVT+ neurons. No significant differences in the activation of AVT+ cells were found between conditions, but a clear association was observed between the number of AVT+ cells and certain behavioral traits. In addition, a different activation of AVT+ cell-types was observed for social vs. isolated males. We conclude that the POA of B. gauderio exhibits changes induced by social stimuli in reproductive context, involving an increase in AVT production and a different profile activation among AVT+ cell populations
Adaptação ao cultivo e valorização de Lavandula luisieri
Foram estudadas diversas populações de Lavandula luisieri (Rozeira) Rivas-Martínez
endémicas da Península Ibérica (Beira Interior, Castilla-la-Mancha e Andaluzia; acessos
de Casal da Fraga, Mata, Penamacor e Vila Velha de Ródão – Portugal; Toledo e
Sevilha – Espanha), comparando as populações relativamente ao óleo essencial
(quantitativamente e qualitativamente), assim como, a sua actividade insecticida sobre
pragas fitófagas (Spodoptera littoralis, Mysus persicae e Leptinotarsa decemlineata).
Em função dos seus componentes escolheram-se as duas populações mais interessantes
em termos da sua actividade biológica (Penamacor e Toledo) e instalaram-se dois
campos produtivos em Castelo Branco e Saragoça, por forma a inferir sobre a influência
do local de produção na qualidade do material vegetal obtido. Será fornecida
informação técnica sobre a instalação destes campos
Theory of a magnetic microscope with nanometer resolution
We propose a theory for a type of apertureless scanning near field microscopy
that is intended to allow the measurement of magnetism on a nanometer length
scale. A scanning probe, for example a scanning tunneling microscope (STM) tip,
is used to scan a magnetic substrate while a laser is focused on it. The
electric field between the tip and substrate is enhanced in such a way that the
circular polarization due to the Kerr effect, which is normally of order 0.1%
is increased by up to two orders of magnitude for the case of a Ag or W tip and
an Fe sample. Apart from this there is a large background of circular
polarization which is non-magnetic in origin. This circular polarization is
produced by light scattered from the STM tip and substrate. A detailed retarded
calculation for this light-in-light-out experiment is presented.Comment: 17 pages, 8 figure
Mass spectrometry based metabolomics comparison of liver grafts from donors after circulatory death (DCD) and donors after brain death (DBD) used in human orthotopic liver transplantation
Use of marginal liver grafts, especially those from donors after circulatory death (DCD), has been considered as a solution to organ shortage. Inferior outcomes have been attributed to donor warm ischaemic damage in these DCD organs. Here we sought to profile the metabolic mechanisms underpinning donor warm ischaemia. Non-targeted Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry metabolomics was applied to biopsies of liver grafts from donors after brain death (DBD; n = 27) and DCD (n = 10), both during static cold storage (T1) as well as post-reperfusion (T2). Furthermore 6 biopsies from DBD donors prior to the organ donation (T0) were also profiled. Considering DBD and DCD together, significant metabolic differences were discovered between T1 and T2 (688 peaks) that were primarily related to amino acid metabolism, meanwhile T0 biopsies grouped together with T2, denoting the distinctively different metabolic activity of the perfused state. Major metabolic differences were discovered between DCD and DBD during cold-phase (T1) primarily related to glucose, tryptophan and kynurenine metabolism, and in the post-reperfusion phase (T2) related to amino acid and glutathione metabolism. We propose tryptophan/kynurenine and S-adenosylmethionine as possible biomarkers for the previously established higher graft failure of DCD livers, and conclude that the associated pathways should be targeted in more exhaustive and quantitative investigations
Estudo das argamassas do Cais das Colunas (Séc. XVIII), Lisboa, Portugal
O Cais das Colunas é o único cais monumental construído, em Lisboa, no âmbito do projeto de reconstrução da cidade depois do terramoto de 1755. O cais foi parcialmente desmontado em 1997 e reconstruído em 2008. Durante os trabalhos de reposição foram recolhidas amostras de argamassas originais, datáveis das décadas de 1770 a 1790, do núcleo do embarcadouro, tendo em vista o seu estudo e caracterização. A metodologia analítica envolveu a realização de ensaios químicos, mineralógicos e físicos, nomeadamente de espetrometria de fluorescência de raios X (FRX), difração de raios X (DRX) e absorção capilar por contacto (ACC). Os resultados obtidos foram comparados com os de argamassas de período cronológico e localização congéneres, confirmando-se a sua consonância, nomeadamente do uso, para a formulação das argamassas, de areias locais e da cal aérea como ligante.info:eu-repo/semantics/publishedVersio
Eruptions of Magnetic Ropes in Two Homologous Solar Events on 2002 June 1 and 2: a Key to Understanding of an Enigmatic Flare
The goal of this paper is to understand the drivers, configurations, and
scenarios of two similar eruptive events, which occurred in the same solar
active region 9973 on 2002 June 1 and 2. The June 2 event was previously
studied by Sui, Holman, and Dennis (2006, 2008), who concluded that it was
challenging for popular flare models. Using multi-spectral data, we analyze a
combination of the two events. Each of the events exhibited an evolving
cusp-like feature. We have revealed that these apparent ``cusps'' were most
likely mimicked by twisted magnetic flux ropes, but unlikely to be related to
the inverted Y-like magnetic configuration in the standard flare model. The
ropes originated inside a funnel-like magnetic domain whose base was bounded by
an EUV ring structure, and the top was associated with a coronal null point.
The ropes appear to be the major drivers for the events, but their rise was not
triggered by reconnection in the coronal null point. We propose a scenario and
a three-dimensional scheme for these events in which the filament eruptions and
flares were caused by interaction of the ropes.Comment: 22 pages, 11 figure
The low energy limit of the non-commutative Wess-Zumino model
The non-commutative Wess-Zumino model is used as a prototype for studying the
low energy behaviour of a renormalizable non-commutative field theory. We start
by deriving the potential mediating the fermion-fermion and boson-boson
interactions in the non-relativistic regime. The quantum counterparts of these
potentials are afflicted by irdering ambiguities but we show that there exists
an ordering prescription which makes them hermitean. For space/space
noncommutativity it turns out that Majorana fermions may be pictured as rods
oriented perpendicularly to the direction of motion showing a lack of
localituy, while bosons remain insensitive to the effects of noncommutativity.
For time/space noncommutativity bosopns and fermions can be regarded as rods
oriented along the direction of motion. For both cases of noncommutativity the
scattering state described scattered waves, with at least one wave having
negative time delay signalizing the underlying nonlocality. The superfield
formulation of the model is used to compute the corresponding effective action
in the one- and two-loop approximations. In the case of time/space
noncommutativity, unitarity is violated in the relativistic regime. However,
this does not preclude the existence of the unitary low energy limit.Comment: 14 pages, 2 figures, minor correction
- …