Cartographie de la dynamique du couvert vegetal de la foret Classee d’Agbo 1 Cote d’Ivoire

Pour garantir l’utilisation durable et l’équilibre écologique de la forêt classée d’Agbo 1, il est important d’acquérir des informations sur la dynamique de la végétation. Ainsi la présente étude a pour objectif d’évaluer la dynamique spatio-temporelle de la forêt classée d’Agbo 1 (Côte d’Ivoire) à partir des images Landsat datant de 1987, 2002 et 2017. Une analyse diachronique des données satellitaires a été réalisée et l’approche de la classification dirigée par la méthode de maximum de vraisemblance à partir des compositions colorées de type 4/5/7 (TM et ETM+) et 5/6/7 (OLI) ont été retenues en vue de la discrimination des classes et l’élaboration des cartes d’occupation du sol de la forêt de 1987, 2002 et 2017. Cinq classes d’occupation du sol ont été discriminées. Les précisions globales et les coefficients Kappa obtenus pour les images classifiées sont respectivement de 90,70 % (0,89) ; 91,78% (0,90) et de 92,19 % (0,91) pour 1987, 2002 et 2017. La couverture forestière de cette forêt qui déjà, en 1987 ne représentaient que 50,64 % de la superficie totale cette forêt classée a régressé davantage jusqu’à 28,85 % de la superficie totale en 2017. Les taux moyens annuels calculés pour la période de 1987 à 2017 montrent une régression des forêts anciennes (-3,26) et des forêts secondaires (- 1,26). On observe parallèlement une progression des classes zone agricole (0,08) et (2,35).Mots-clés: Dynamique, Télédétection, Déforestation, Gestion durable, Forêt classée Agbo 1English Title: Mapping of vegetation cover dynamics of the Agbo 1 Forest (Côte d’Ivoire)English AbstractTo ensure the sustainable use and ecological balance of the Agbo 1 Forest, it is important to acquire information on vegetation dynamics. Thus, the objective of this study is to evaluate the spatio-temporal dynamics of the Agbo 1 forest (Ivory Coast) using Landsat images dating back to 1987, 2002 and 2017. A diachronic analysis of the satellite data was carried out and the maximum likelihood-directed classification approach from type 4/5/7 (TM and ETM +) and 5/6/7 (OLI) color compositions were selected for the discrimination of classes and development of forest land cover maps of 1987, 2002 and 2017. Five classes of land use were discriminated against. The overall accuracies and Kappa coefficients obtained for the classified images are respectively 90.70% (0.89); 91.78% (0.90) and 92.19% (0.91) for 1987, 2002 and 2017. The forest cover of this forest, which in 1987 represented only 50.64% of the total area of this forest. Forest decreased further to 28.85% of the total area in 2017. The annual average rates calculated for the period 1987 to 2017 show a regression of old-growth forests (-3.26) and secondary forests (-1.26). At the same time, there is an increase in agricultural classes (0.08) and (2.35).Keywords: Dynamic, Remote Sensing, Deforestation, Sustainable Management, Agbo Fores

Following Gluonic World Lines to Find the QCD Coupling in the Infrared

Using a parametrization of the Wilson loop with the minimal-area law, we calculate the polarization operator of a valence gluon, which propagates in the confining background. This enables us to obtain the infrared freezing (i.e. finiteness) of the running strong coupling in the confinement phase, as well as in the deconfinement phase up to the temperature of dimensional reduction. The momentum scale defining the onset of freezing is found both analytically and numerically. The nonperturbative contribution to the thrust variable, originating from the freezing, makes the value of this variable closer to the experimental one.Comment: 25 pages, 5 figure

A nondiagrammatic calculation of the Rho parameter from heavy fermions

A simple nondiagrammatic evaluation of the nondecoupling effect of heavy fermions on the Veltman's Rho parameter is presented in detail. This calculation is based on the path integral approach, the electroweak chiral Lagrangian formalism, and the Schwinger proper time method.Comment: 11 page

Parton content of the real photon: astrophysical implications

We possess convincing experimental evidence for the fact that the real photon has non-trivial parton structure. On the other hand, interactions of the cosmic microwave background photons with high energy particles propagating through the Universe play an important role in astrophysics. In this context, to invoke the parton content could be convenient for calculations of the probabilities of different processes involving these photons. As an example, the cross section of inclusive resonant $W^+$ boson production in the reaction $\nu \gamma\to W^+X$ is calculated by using the parton language. Neutrino--photon deep inelastic scattering is considered.Comment: 4 pages, 2 figures. The spin states of the initial particles in the reaction $\nu\gamma\to W^+X$ are correctly treated. As a result, the corresponding cross section becomes two times greater than the one from the previous version. Some changes in the tex

Two parton shower background for associate W Higgs production

The estimates of the background for the associate W Higgs production, which stems from the two parton shower production. It is about 1 - 2.5 times larger than the signal. However, this background does not depend on the rapidity difference between the W and the $b \bar{b}$ pair, while the signal peaks when the rapidity difference is zero. The detailed calculations for the enhanced diagrams' contribution to this process, are presented, and it is shown that the overlapping singularities, being important theoretically, lead to a negligible contribution for the LHC range of energiesComment: 35 pages and 10 figures in eps file

Transformation of β-Ni(OH)2to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)2to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices

Total photoproduction cross-section at very high energy

In this paper we apply to photoproduction total cross-section a model we have proposed for purely hadronic processes and which is based on QCD mini-jets and soft gluon re-summation. We compare the predictions of our model with the HERA data as well as with other models. For cosmic rays, our model predicts substantially higher cross-sections at TeV energies than models based on factorization but lower than models based on mini-jets alone, without soft gluons. We discuss the origin of this difference.Comment: 13 pages, 9 figures. Accepted for publication in EPJC. Changes concern added references, clarifications of the Soft Gluon Resummation method used in the paper, and other changes requested by the Journal referee which do not change the results of the original versio

Analysis of B_s->\phi \ell^+ \ell^- decay with new physics effects

The rare B_s-> \phi \ell^+ \ell^- decay is investigated by using the most general model independent effective Hamiltonian for $\ell= \mu, \tau$. The calculated Br(B_s \rar \phi \mu^+ \mu^-) = 1.92 \times 10^{-6} is in consistent with the experimental upper bound. The dependencies of the branching ratios and polarization asymmetries of leptons and combined lepton-antilepton asymmetries on the new Wilson coefficients are presented. The analysis shows that the branching ratios and the lepton polarization asymmetries are very sensitive to the scalar and tensor type interactions. The results obtained in this work will be very useful in searching new physics beyond the standard model.Comment: 28 pages, 14 figure

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm

The PHENIX experiement has measured the electron-positron pair mass spectrum from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions from light meson decays to e^+e^- pairs have been determined based on measurements of hadron production cross sections by PHENIX. They account for nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair yield remaining after subtracting these contributions is dominated by semileptonic decays of charmed hadrons correlated through flavor conservation. Using the spectral shape predicted by PYTHIA, we estimate the charm production cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which is consistent with QCD calculations and measurements of single leptons by PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables. Submitted to Physics Letters B. v2 fixes technical errors in matching authors to institutions. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm