1,620 research outputs found
Hybrid and Orbitally Excited Mesons in Full QCD
We present results for the hybrid meson spectrum produced by gluonic
excitations in full QCD using Wilson fermions. For the spin-exotic mesons with
J^{PC}=1^{-+}, 0^{+-}, and 2^{+-} we find the lightest state to be 1^{-+} with
a mass of 1.9(2) GeV. Results obtained for orbitally excited mesons are also
presented.Comment: LATTICE98(spectrum),3 pages, LaTeX2e File, 4 PS Figure
Validation of the Lower Tagus Valley velocity and structural model using ambient noise broadband measurements
Along his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them were
produced in large ruptures of offshore structures located southwest of the Portuguese coastline, among these we
the Lisbon earthquake of 1 November 1755; other moderates earthquakes were produced by local sources such as
the 1344, 1531 and the 1909 Benavente earthquake.
In order to promote an improved assessment of the seismic hazard in this region, we propose the introduction
of realistic methods on the prediction of ground motion produced by moderate to large earthquakes in LTV.
This process involves the establishment of a structural 3D model based on all the available geophysical and
geotechnical data on the area (seismic, gravimetric, deep wells and geological outcrops) and the determination of
wave propagation from a finite difference method: by applying the E3D program [1,2].
To confirm this model we use broadband ambient noise measurements collected in two profiles with azimuth
perpendicular to the basin axis and we applied the horizontal to vertical (H/V) spectral ratio method [3] to the
recordings in order to estimate the amplification of the basin. The H/V curves obtained reveals the existence of two
low frequency peaks centered on 0.2 a 1 Hz frequencies[4]. These peaks are strongly related with the thickness
of Cenozoic and alluvial sediments. By inversion of the H/V curve, we obtain a more detailed velocity model for
the region where the profile were determined, which is in good agreement with borehole data and other results
obtained with magnetic and seismic reflection methods
Sensibilidade de diferentes cultivares de oliveira aos ataques da mosca da azeitona, Bactrocera oleae (Gmel.) e da traça da oliveira, Prays oleae (Bern.).
Com o presente estudo pretendeu-se avaliar a diferenças de sensibilidade de três
cultivares de oliveira à mosca da azeitona, Bactrocera oleae (Geml.) e/ou a sua
preferência pelos adultos da traça da oliveira, Prays oleae (Bern.), para a realização das
posturas. Os dados apresentados referem-se a 2000 e 2001, tendo sido obtidos através
de amostragens realizadas em seis oliveiras de ‘Cobrançosa’, de ‘Verdeal
Transmontana’ e de ‘Madural’. Os resultados obtidos mostram diferenças na data de
ocorrência do estado receptivo à postura na geração antófaga da traça da oliveira (estado
fenológico D) – que ocorreu cerca de uma semana mais cedo na ‘Madural’ e na
‘Verdeal Transmontana’ do que na ‘Cobrançosa’ –, bem como na maturação dos frutos
– tendo sido a ‘Madural’ a mais temporã. A percentagem de frutos atacados pela traça
da oliveira foi superior na ‘Cobrançosa’ e na ‘Madural’ comparativamente à ‘Verdeal
Transmontana’. No caso da mosca da azeitona, observaram-se diferenças significativas
entre cultivares, no que respeita à intensidade do ataque, com valores superiores a
85,0 % na ‘Madural’, em fins de Outubro. A ‘Verdeal Transmontana’ apresentou
intensidades de ataque intermédios (superiores a 70,0 %), enquanto a ‘Cobrançosa’
apresentou os ataques mais baixos, com 38,0 %, em 2000 e 59,0 %, em 2001
Outer Regions of the Milky Way
With the start of the Gaia era, the time has come to address the major
challenge of deriving the star formation history and evolution of the disk of
our MilkyWay. Here we review our present knowledge of the outer regions of the
Milky Way disk population. Its stellar content, its structure and its dynamical
and chemical evolution are summarized, focussing on our lack of understanding
both from an observational and a theoretical viewpoint. We describe the
unprecedented data that Gaia and the upcoming ground-based spectroscopic
surveys will provide in the next decade. More in detail, we quantify the expect
accuracy in position, velocity and astrophysical parameters of some of the key
tracers of the stellar populations in the outer Galactic disk. Some insights on
the future capability of these surveys to answer crucial and fundamental issues
are discussed, such as the mechanisms driving the spiral arms and the warp
formation. Our Galaxy, theMilkyWay, is our cosmological laboratory for
understanding the process of formation and evolution of disk galaxies. What we
learn in the next decades will be naturally transferred to the extragalactic
domain.Comment: 22 pages, 10 figures, Invited review, Book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
Shelf-life extension of watermelon juice preserved by hyperbaric storage at room temperature compared to refrigeration
This work reports Hyperbaric Storage (HS) preservation of raw watermelon juice at variable/uncontrolled
room temperature (RT,z21 C) for 7 days at 100 MPa and compared it with refrigeration (RF). At the end
of storage, there was an increase in microbial counts (total aerobic mesophiles, psychrophiles, and yeasts
and moulds) to above 6 log10 CFU/mL for samples stored at atmospheric pressure (RF and RT), while juice
stored under HS/RT showed maximum values of about 2 log10 CFU/mL for total aerobic mesophiles/
psychrophiles and below the detection limit for yeasts and moulds. HS/RT juice showed also physicochemical
parameters at levels similar to the initial juice. Thus, HS/RT can not only be used to preserve foods with no refrigeration energetic costs (since it does not require temperature control), but additionally, has also a great potential to extend the shelf-life of food products, compared to RF. This is the first case in the literature showing this additional potential/advantage of HS/RT
Evaluation of the almond shell oxypropylation process trough the surface response methodology
The efficiency of an oxypropylation process depends on several variables and operating conditions, which may not be generalized due to the diverse nature of subtracts. In lignocellulosic biomasses, the content of each fraction (lignin, cellulose and hemicellulose) can differ, as well as, the crystalline organization, which may limit reagent’s access to biomass. Also, the hydroxyl content can vary among biomasses; high values demand higher amounts of reactants, namely catalyst content, and more severe reaction conditions. Therefore, owing to biomass variability, selection of the operating conditions for oxypropylation their optimization is a key issue. In this context, one-factor-at-a-time approaches are commonly used to optimize processes; but it is well-known that optimal operating conditions or interactions between variables cannot be predicted by this simplistic method. Both problems may be overcome by employing the response surface methodology (RSM).info:eu-repo/semantics/publishedVersio
Metal-insulator transition in one-dimensional lattices with chaotic energy sequences
We study electronic transport through a one-dimensional array of sites by
using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic
sequence. The correlation degree between these energies is controlled by a
parameter regulating the dynamic Lyapunov exponent measuring the degree of
chaos. We observe the effect of chaotic sequences on the localization length,
conductance, conductance distribution and wave function, finding evidence of a
Metal-Insulator Transition (MIT) at a critical degree of chaos. The
one-dimensional metallic phase is characterized by a Gaussian conductance
distribution and exhibits a peculiar non-selfaveraging.Comment: 5 pages, 5 figures (one figure replaced). Includes new results and a
few additional references. Improved style for publication. Accepted in
Physics Letters
- …