Geographic space, assets, livelihoods and well-being in rural Central America

"This paper uses an asset-base framework to analyze the determinants of rural growth and sustainable poverty reduction for the three poorest countries in Central America: Guatemala, Honduras and Nicaragua...Using a combination of GIS mapping techniques, quantitative household analysis, and qualitative analyses of assets and livelihoods, the authors generate a description of rural territories that recognizes the differential effects of policies and asset bundles across space and households. They identify the combinations of human, natural and physical, social and location-specific assets that matter most to raise household well-being and take advantage of prospects for poverty-reducing growth." from Authors' AbstractPoverty reduction ,rural livelihoods ,Households Economic aspects ,

Density waves in the shearing sheet I. Swing amplification

The shearing sheet model of a galactic disk is studied anew. The theoretical description of its dynamics is based on three building blocks: Stellar orbits, which are described here in epicyclic approximation, the collisionless Boltzmann equation determining the distribution function of stars in phase space, and the Poisson equation in order to take account of the self-gravity of the disk. Using these tools I develop a new formalism to describe perturbations of the shearing sheet. Applying this to the unbounded shearing sheet model I demonstrate again how the disturbances of the disk evolve always into `swing amplified' density waves, i.e. spiral-arm like, shearing density enhancements, which grow and decay while the wave crests swing by from leading to trailing orientation. Several examples are given how such `swing amplification' events are incited in the shearing sheet.Comment: small corrections, uses new A&A style fil

Evidence for a meteoritic origin of the September 15, 2007, Carancas crater

On September 15th, 2007, around 11:45 local time in Peru, near the Bolivian border, the atmospheric entry of a meteoroid produced bright lights in the sky and intense detonations. Soon after, a crater was discovered south of Lake Titicaca. These events have been detected by the Bolivian seismic network and two infrasound arrays operating for the Comprehensive Nuclear-Test-Ban Treaty Organization, situated at about 80 and 1620 km from the crater. The localization and origin time computed with the seismic records are consistent with the reported impact. The entry elevation and azimuthal angles of the trajectory are estimated from the observed signal time sequences and backazimuths. From the crater diameter and the airwave amplitudes, the kinetic energy, mass and explosive energy are calculated. Using the estimated velocity of the meteoroid and similarity criteria between orbital elements, an association with possible parent asteroids is attempted. The favorable setting of this event provides a unique opportunity to evaluate physical and kinematic parameters of the object that generated the first actual terrestrial meteorite impact seismically recorded

Propagators in Lagrangian space

It has been found recently that propagators, e.g. the cross-correlation spectra of the cosmic fields with the initial density field, decay exponentially at large-k in an Eulerian description of the dynamics. We explore here similar quantities defined for a Lagrangian space description. We find that propagators in Lagrangian space do not exhibit the same properties: they are found not to be monotonic functions of time, and to track back the linear growth rate at late time (but with a renormalized amplitude). These results have been obtained with a novel method which we describe alongside. It allows the formal resummation of the same set of diagrams as those that led to the known results in Eulerian space. We provide a tentative explanation for the marked differences seen between the Eulerian and the Lagrangian cases, and we point out the role played by the vorticity degrees of freedom that are specific to the Lagrangian formalism. This provides us with new insights into the late-time behavior of the propagators.Comment: 14 pages, 5 figure

Class of invariants for the 2D time-dependent Landau problem and harmonic oscillator in a magnetic field

We consider an isotropic two dimensional harmonic oscillator with arbitrarily time-dependent mass $M(t)$ and frequency $\Omega(t)$ in an arbitrarily time-dependent magnetic field $B(t)$. We determine two commuting invariant observables (in the sense of Lewis and Riesenfeld) $L,I$ in terms of some solution of an auxiliary ordinary differential equation and an orthonormal basis of the Hilbert space consisting of joint eigenvectors $\phi_\lambda$ of $L,I$. We then determine time-dependent phases $\alpha_\lambda(t)$ such that the $\psi_\lambda(t)=e^{i\alpha_\lambda}\phi_\lambda$ are solutions of the time-dependent Schr\"odinger equation and make up an orthonormal basis of the Hilbert space. These results apply, in particular to a two dimensional Landau problem with time-dependent $M,B$, which is obtained from the above just by setting $\Omega(t) \equiv 0$. By a mere redefinition of the parameters, these results can be applied also to the analogous models on the canonical non-commutative plane.Comment: 13 pages, 3 references adde

Approche semi-quantitative de la minéralisation des aquifères schisteux en zone équatoriale de transition : Cas de la région Sikensi-Agboville (Côte d’Ivoire)

L’aquifère des schistes (Sikensi-Agboville) compte d’importants ouvrages permettant l’approvisionnement en eau potable des populations locales. Toute fois, la couleur et le goût inhabituels, par endroit, des eaux prélevées sont quelques peu inquiétants, bien qu’aucun risque sanitaire grave n’est jusqu’à présent décelé. Pour tenter d’apporter un élément de compréhension à cette question, nous utilisons la géochimie des roches, laminéralogie et l’hydrochimie pour étudier les interactions entre l’eau et son aquifère. Les résultats montrent que les schistes en question sont constitués d’albite, de chlorites, de micas noirs, d’épidotes, du sphène et de l’apatite, susceptibles de fournir leurs cations majeurs à la nappe. La dissolution incongruente de ces minéraux au contact de l’eau à pH 6 et à ~26 °C, montre que le Na+ provient majoritairement de l’albite et le Mg2+ des chlorites, qui sont en proportion considérable dans les schistes, avec des concentrations respectives de ~0,463 mmol.L-1 et de ~0,171 mmol.L-1. Un faible taux de 0,025 mmol.L-1 de Mg2+ est fourni par la biotite tandis que le K+, avec une concentration de ~0,018 mmol.L-1, provient à la fois de la biotite et de l’annite. La principale source du Ca2+ concerne les épidotes, avec un taux de ~0,188 mmol.L-1 puis viennent l’apatite et le sphène, avec des taux moyens respectifs de 0,251 mmol.L-1 et de ~0,090 mmol.L-1.Mots clés: Nappe, silicates, hydrolyse, interaction, concentration, cations majeurs

Simultaneous infection of Ixodes ricinus nymphs by two Borrelia burgdorferi sensu lato species: possible implications for clinical manifestations.

info:eu-repo/semantics/publishe

Reduced Gutzwiller formula with symmetry: case of a finite group

We consider a classical Hamiltonian $H$ on $\mathbb{R}^{2d}$, invariant by a finite group of symmetry $G$, whose Weyl quantization $\hat{H}$ is a selfadjoint operator on $L^2(\mathbb{R}^d)$. If $\chi$ is an irreducible character of $G$, we investigate the spectrum of its restriction $\hat{H}\_\chi$ to the symmetry subspace $L^2\_\chi(\mathbb{R}^d)$ of $L^2(\mathbb{R}^d)$ coming from the decomposition of Peter-Weyl. We give reduced semi-classical asymptotics of a regularised spectral density describing the spectrum of $\hat{H}\_\chi$ near a non critical energy $E\in\mathbb{R}$. If $\Sigma\_E:=\{H=E \}$ is compact, assuming that periodic orbits are non-degenerate in $\Sigma\_E/G$, we get a reduced Gutzwiller trace formula which makes periodic orbits of the reduced space $\Sigma\_E/G$ appear. The method is based upon the use of coherent states, whose propagation was given in the work of M. Combescure and D. Robert.Comment: 20 page