333 research outputs found
Associação de caracterĂsticas de planta em cultivares de aveia com habilidade competitiva
CaracterĂsticas morfolĂłgicas de plantas cultivadas que confiram maior habilidade competitiva podem integrar medidas de manejo cultural de plantas daninhas e, com isso, reduzir o uso de herbicidas. O objetivo deste trabalho foi investigar se o crescimento inicial por plantas de cultivares de aveia se associa ao seu potencial competitivo com plantas infestantes. Para isso, foi conduzido um experimento a campo na Universidade Federal de Pelotas, em CapĂŁo do LeĂŁo-RS, durante a estação de crescimento de 2006. Compararam-se os cultivares de aveia: ALBASUL, CFT 1, UPFA 22 e URS 22, os quais foram testados sob trĂȘs condiçÔes de competição (ausĂȘncia de plantas concorrentes, presença de trigo ou de linho, como competidores). O delineamento experimental utilizado foi completamente casualizado, com quatro repetiçÔes. Avaliaram-se diversas caracterĂsticas morfolĂłgicas em plantas de aveia no inĂcio do ciclo de desenvolvimento e outras caracterĂsticas agronĂŽmicas no final do ciclo da aveia e de seus competidores. Os cultivares de aveia responderam diferentemente Ă presença de plantas competidoras. O cultivar UPFA 22, em geral, apresentou maiores valores para caracterĂsticas morfolĂłgicas de planta associadas com habilidade competitiva, enquanto o cultivar URS 22, ao contrĂĄrio, mostrou deficiĂȘncias em caracterĂsticas vantajosas Ă competição. Os cultivares UPFA 22 e CFT 1 demonstraram elevada capacidade de competir com as espĂ©cies concorrentes. CaracterĂsticas morfolĂłgicas em plantas de cultivares de aveia no inĂcio do ciclo de desenvolvimento, de modo geral, nĂŁo mostraram habilidade competitiva atĂ© o final do ciclo.Morphological crop plant traits which confer greater competitive ability may integrate cultural weed management measures, thus reducing the use of herbicides. The aim of this study was to investigate whether a fast initial growth of oat cultivars relate to their competitive potential with concurrent plants. A field experiment was conducted at the Universidade Federal de Pelotas, in CapĂŁo do LeĂŁo-RS, during the 2006 growing season. The oat cultivars ALBASUL, CFT 1, UPFA 22, and URS 22, which were tested under three competition conditions (absence of concurrent plants, presence of flax or of wheat as competitors) were used. The experiment was arranged in a completely randomized design, with four replicates. Many morphological characteristics in oat plants were evaluated at the initial phase of their development, as well as other agronomic traits at the end of the oat cycle and of the cycle of its competitors. Oat cultivars reacted differently to the presence of concurrent plants. The UPFA 22 cultivar generally presented greater values for the morphological plant traits associated with competitive ability; whereas URS 22 showed deficiencies in traits advantageous to competition. The cultivars UPFA 22 and CFT 1 demonstrated a high potential to compete with concurrent plants. The morphological traits of oat cultivars evaluated at the beginning of their development, in general, did not sustain the competitive ability until the end of their cycles
The Position of High Frequency Waves with Respect to the Granulation Pattern
High frequency velocity oscillations were observed in the spectral lines Fe I
543.45nm and 543.29nm, using 2D spectroscopy with a Fabry- Perot and speckle
reconstruction, at the VTT in Tenerife. We investigate the radial component of
waves with frequencies in the range 8 - 22mHz in the internetwork, network and
a pore. We find that the occurrence of waves do not show any preference on
location and are equally distributed over down-flows and up-flows, regardless
of the activity of the observed area in the line of Fe I 543.45nm. The waves
observed in the lower formed line of Fe I 543.29nm seem to appear
preferentially over down-flows.Comment: Article has 12 pages and 7 images. It is accepted in Solar Physics
Journa
SU(3) Predictions for Weak Decays of Doubly Heavy Baryons -- including SU(3) breaking terms
We find expressions for the weak decay amplitudes of baryons containing two b
quarks (or one b and one c quark -- many relationship are the same) in terms of
unknown reduced matrix elements. This project was originally motivated by the
request of the FNAL Run II b Physics Workshop organizers for a guide to
experimentalists in their search for as yet unobserved hadrons. We include an
analysis of linear SU(3) breaking terms in addition to relationships generated
by unbroken SU(3) symmetry, and relate these to expressions in terms of the
complete set of possible reduced matrix elements.Comment: 49 page
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
Atmospheric parameters, such as pressure (P), temperature (T) and density,
affect the development of extensive air showers initiated by energetic cosmic
rays. We have studied the impact of atmospheric variations on extensive air
showers by means of the surface detector of the Pierre Auger Observatory. The
rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find
that the observed behaviour is explained by a model including the effects
associated with the variations of pressure and density. The former affects the
longitudinal development of air showers while the latter influences the Moliere
radius and hence the lateral distribution of the shower particles. The model is
validated with full simulations of extensive air showers using atmospheric
profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle
Physic
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