Energy Demand in Agricultural Biomass Production in Parana state, Brazil

Energy flow analysis is an interesting approach to assess and to improve sustainability of agricultural production systems, represented by the economy of energy resources and other inputs translated into energy terms. This type of analysis can complement the economic view contributing to more efficient production systems. Moreover, assessing crops with traditional food use may play an important role in energy provision. Energy efficiency tools were applied in order to determine the energy demand as well as the efficiency of the biomass production of several forage crops in mechanized systems conducted at Paraná state, Brazil. Material flow, input and output energy, energy balance, energy return over investment and embodied energy were used and identified that maize and sorghum were the crops that uses energy in the most efficient way, represented by the best results at net energy availability, profitability and embodied energy at the final product. Oat and ryegrass were the crops the presented the least efficient energy uses in the biomass production systems.   Keywords: Bioenergy, energy indicators, sustainability, embodied energy. &nbsp

Uso de classificadores para o mapeamento da vegetação nativa de cerrado.

ABSTRACT- The environment is in constant change, and for a better comprehension of these changes it is necessary observations with an amplitude of temporal and spatial scales. The use of geoprocessing and remote sensing techniques to identify the modifications promoted by human race in the environment are becoming more frequent, highlighting the monitoring of deforestation and illegal burning. In this work the objective was to realize the mapping of savannah native vegetation using an image CCD/CBERS-2 and the classification methods visual, supervised and non supervised. The work was realized in the municipal district of Gurupi, TO, coordinates 11° 44' 47" S and 49° 04' 15" W. The delimitation of the area was defined by the map SC-22-Z-DIV-4-NE from the Brazilian Institute of Geography and Statistics (IBGE), scale of 1:25.000, with a total area of 19,093.19 ha. After the image registration it was obtained a mean error of 0.48 pixel or 9.6 m. After the classification using the different methods it is possible to say that for local conditions, the visual and supervised classifications were the most indicated, mapping an area of 6,112.19 and 4,173.40 ha, respectively. The non supervised classification mapped an area of 6,646.00 ha. The exactitude indices were considered excellent for visual and supervised classification. The previous knowledge about the area was indispensable to the results of the visual and supervised classifications. A non supervised classification with a reduced number of classes could reduce the excess of similar classes and increase the exactitude indices for the classification, according to local conditions

Hadronic sizes and observables in high-energy scattering

The functional dependence of the high-energy observables of total cross section and slope parameter on the sizes of the colliding hadrons predicted by the model of the stochastic vacuum and the corresponding relations used in the geometric model of Povh and H\"ufner are confronted with the experimental data. The existence of a universal term in the expression for the slope, due purely to vacuum effects, independent of the energy and of the particular hadronic system, is investigated. Accounting for the two independent correlation functions of the QCD vacuum, we improve the simple and consistent description given by the model of the stochastic vacuum to the high-energy pp and pbar-p data, with a new determination of parameters of non-perturbative QCD. The increase of the hadronic radii with the energy accounts for the energy dependence of the observables.Comment: Latex, using Revtex.style . 2 ps figures. To be published in Physical Review D , July 199

Quark exchange model for charmonium dissociation in hot hadronic matter

A diagrammatic approach to quark exchange processes in meson-meson scattering is applied to the case of inelastic reactions of the type (Q\barQ)+(q\barq)\rightarrow (Q\barq) + (q\barQ), where $Q$ and $q$ refer to heavy and light quarks, respectively. This string-flip process is discussed as a microscopic mechanism for charmonium dissociation (absorption) in hadronic matter. The cross section for the reaction $J/\psi + \pi \to D+ \bar D$ is calculated using a potential model, which is fitted to the meson mass spectrum. The temperature dependence of the relaxation time for the \J/Psi distribution in a homogeneous thermal pion gas is obtained. The use of charmonium for the diagnostics of the state of hot hadronic matter produced in ultrarelativistic nucleus-nucleus collisions is discussed.Comment: 24 pages, 3 tables, 7 figure

Baryon Charge Radii and Quadrupole Moments in the 1/N_c Expansion: The 3-Flavor Case

We develop a straightforward method to compute charge radii and quadrupole moments for baryons both with and without strangeness, when the number of QCD color charges is N_c. The minimal assumption of the single-photon exchange ansatz implies that only two operators are required to describe these baryon observables. Our results are presented so that SU(3) flavor and isospin symmetry breaking can be introduced according to any desired specification, although we also present results obtained from two patterns suggested by the quark model with gluon exchange interactions. The method also permits to extract a number of model-independent relations; a sample is r^2_Lambda / r_n^2 = 3/(N_c+3), independent of SU(3) symmetry breaking.Comment: 30 pages, no figures, REVTeX

Density dependent hadron field theory for hypernuclei

The Density Dependent Relativistic Hadron Field (DDRH) theory, previously introduced and applied to isospin nuclei, is extended to hypernuclei by including the octet hyperons. Infinite matter Dirac-Brueckner theory for octet baryons and the derivation of in-medium DDRH baryon-meson vertices is discussed. From the properties of Dirac-Brueckner interactions it is found that hyperon and nucleon self-energies and vertices are related by the ratios of free space coupling constants. This leads to simple scaling laws for the in-medium hyperon and nucleon vertices. The model is applied in relativistic DDRH mean-field calculations to singl$\Lambda nuclei. Free space N-Lambda T-matrix results are used for the scalar vertex. As the only free parameter the hyperon vector vertex scaling factor is adjusted to a selected set of hypernuclear data. Spectroscopic data of single Lambda hypernuclei over the full mass range are well described. The reduced Lambda spin-orbit splitting is reproduced and found to be related closely the medium dependence of scalar and vector interactions.Comment: 38 pages, 9 figure

The QCD Phase Structure at High Baryon Density

We consider the possibility that color deconfinement and chiral symmetry restoration do not coincide in dense baryonic matter at low temperature. As a consequence, a state of massive "constituent" quarks would exist as an intermediate phase between confined nuclear matter and the plasma of deconfined massless quarks and gluons. We discuss the properties of this state and its relation to the recently proposed quarkyonic matter.Comment: 17 pages, 9 figure

Gravitational clustering of relic neutrinos and implications for their detection

We study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter (CDM) and baryonic structures within the flat $\Lambda$CDM model, using both numerical simulations and a semi-analytical linear technique, with the aim of understanding the neutrinos' clustering properties for direct detection purposes. In a comparative analysis, we find that the linear technique systematically underestimates the amount of clustering for a wide range of CDM halo and neutrino masses. This invalidates earlier claims of the technique's applicability. We then compute the exact phase space distribution of relic neutrinos in our neighbourhood at Earth, and estimate the large scale neutrino density contrasts within the local Greisen--Zatsepin--Kuzmin zone. With these findings, we discuss the implications of gravitational neutrino clustering for scattering-based detection methods, ranging from flux detection via Cavendish-type torsion balances, to target detection using accelerator beams and cosmic rays. For emission spectroscopy via resonant annihilation of extremely energetic cosmic neutrinos on the relic neutrino background, we give new estimates for the expected enhancement in the event rates in the direction of the Virgo cluster.Comment: 38 pages, 8 embedded figures, iopart.cls; v2: references added, minor changes in text, to appear in JCA

Parity Violating Measurements of Neutron Densities

Parity violating electron nucleus scattering is a clean and powerful tool for measuring the spatial distributions of neutrons in nuclei with unprecedented accuracy. Parity violation arises from the interference of electromagnetic and weak neutral amplitudes, and the $Z^0$ of the Standard Model couples primarily to neutrons at low $Q^2$. The data can be interpreted with as much confidence as electromagnetic scattering. After briefly reviewing the present theoretical and experimental knowledge of neutron densities, we discuss possible parity violation measurements, their theoretical interpretation, and applications. The experiments are feasible at existing facilities. We show that theoretical corrections are either small or well understood, which makes the interpretation clean. The quantitative relationship to atomic parity nonconservation observables is examined, and we show that the electron scattering asymmetries can be directly applied to atomic PNC because the observables have approximately the same dependence on nuclear shape.Comment: 38 pages, 7 ps figures, very minor changes, submitted to Phys. Rev.

Analysis of NN Amplitudes up to 2.5 GeV: An Optical Model and Geometric Interpretation

We analyse the SM97 partial wave amplitudes for nucleon--nucleon (NN) scattering to 2.5 GeV, in which resonance and meson production effects are evident for energies above pion production threshold. Our analyses are based upon boson exchange or quantum inversion potentials with which the sub-threshold data are fit perfectly. Above 300 MeV they are extrapolations, to which complex short ranged Gaussian potentials are added in the spirit of the optical models of nuclear physics and of diffraction models of high energy physics. The data to 2.5 GeV are all well fit. The energy dependences of these Gaussians are very smooth save for precise effects caused by the known $\Delta$ and N$^\star$ resonances. With this approach, we confirm that the geometrical implications of the profile function found from diffraction scattering are pertinent in the regime 300 MeV to 2.5 GeV and that the overwhelming part of meson production comes from the QCD sector of the nucleons when they have a separation of their centres of 1 to 1.2 fm. This analysis shows that the elastic NN scattering data above 300 MeV can be understood with a local potential operator as well as has the data below 300 MeV.Comment: 49 pages, including 23 figures, LaTeX2e/RevTeX/ps fil