Urbanization suitability maps: a dynamic spatial decision support system for sustainable land use

Abstract. Recent developments in land consumption assessment identify the need to implement integrated evaluation approaches, with particular attention to the development of multidimensional tools for guiding and managing sustainable land use. Land use policy decisions are implemented mostly through spatial planning and its related zoning. This involves trade-offs between many sectorial interests and conflicting challenges seeking win-win solutions. In order to identify a decision-making process for land use allocation, this paper proposes a methodological approach for developing a Dynamic Spatial Decision Support System (DSDSS), denominated Integrated Spatial Assessment (ISA), supported by Geographical Information Systems (GIS) combined with the Analytic Hierarchy Process (AHP). Through empirical investigation in an operative case study, an integrated evaluation approach implemented in a DSDSS helps produce "urbanization suitability maps" in which spatial analysis combined with multi-criteria evaluation methods proved to be useful for both facing the main issues relating to land consumption as well as minimizing environmental impacts of spatial planning

Phase transition in a super superspin glass

We here confirm the occurrence of spin glass phase transition and extract estimates of associated critical exponents of a highly monodisperse and densely compacted system of bare maghemite nanoparticles. This system has earlier been found to behave like an archetypal spin glass, with e.g. a sharp transition from paramagnetic to non-equilibrium behavior, suggesting that this system undergoes a spin-glass phase transition at a relatively high temperature, $T_g$ $\sim$ 140 K.Comment: 4 pages, 3 figure

High temperature magnetic stabilization of cobalt nanoparticles by an antiferromagnetic proximity effect

Thermal activation tends to destroy the magnetic stability of small magnetic nanoparticles, with crucial implications in ultra-high density recording among other applications. Here we demonstrate that low blocking temperature ferromagnetic (FM) Co nanoparticles (TB<70 K) become magnetically stable above 400 K when embedded in a high N\'eel temperature antiferromagnetic (AFM) NiO matrix. The origin of this remarkable TB enhancement is due to a magnetic proximity effect between a thin CoO shell (with low N\'eel temperature, TN; and high anisotropy, KAFM) surrounding the Co nanoparticles and the NiO matrix (with high TN but low KAFM). This proximity effect yields an effective AFM with an apparent TN beyond that of bulk CoO, and an enhanced anisotropy compared to NiO. In turn, the Co core FM moment is stabilized against thermal fluctuations via core-shell exchange-bias coupling, leading to the observed TB increase. Mean-field calculations provide a semi-quantitative understanding of this magnetic- proximity stabilization mechanism

Venedikov, A. P., Vieira, R., & Toro y Llaca, C. D. (1993). Nuevas aportaciones al análisis de observaciones de mareas terrestres.

A new method recently developed in Spain is briefly discussed. The method suggests to use a sophisticated scheme for the appproximation of the drift of the tidal records. The drift is represented separately in subintervals of the record through polynomials of a variable power. An optimum power is estimated for every subinterval by testing statistical hypotheses through the criteria of Fisher and Akaike (AJC) and multiple analysis of all data for every value of the polynomial's power

Perturbed Angular Correlation Studies in SrTi0₃ Single Crystals

The quadrupole hyperfine interactions of ^111Cd/^111 probe nuclei in single-crystalline SrTiO₃ perovskite samples were investigated using Perturbed Angular Correlation spectroscopy. Three electric field gradients were detected and their fractions and hyperfine parameters were measured in the temperature range from 26 to 700 K. The fraction f₀ having a vanishing quadrupole frequency, as expected for ^111Cd on substitutional sites in a cubic lattice, starts to develop around 300 K and reaches 100% at 700 K. Two well-defined EFG's having closely lying quadrupole frequencies and asymmetry parameters of ω_(Q1) = 49.1(3) Mrad/s, η_(1) = 0.10(2) and ω_(Q2) = 51 8(3) Mrad/s, η_(2)= 0.12(2), at room temperature, were identified in the temperature range from 250 to 530 K, and their (100) orientation in the lattice was determined. They are associated with electronic defects at the probe atoms

Ligand exchange in gold-coated FePt nanoparticles

In this work, we present the magnetic properties of gold-coated FePt nanoparticles and the study of stable aqueous dispersions of FePt@Au and FePt synthesized after ligand exchange with mercaptoundecanoic acid. The particle size determined from transmission electron microscopy (TEM) micrographs goes from 4 nm for the uncoated nanoparticles to a maximum of 10 nm for the gold-coated ones indicating that the thickness of the shell ranges from 1 to 3 nm. The magnetic characterization consists in hysteresis cycles at 10 and 300 K. The results show that, at low field and room temperature, the magnetic behavior of uncoated and coated nanoparticles are surprisingly quite similar. Because the gold-coated nanoparticles keep the magnetic properties of FePt and the presence of gold improves the functionalization of nanoparticles, the system is suitable for biological application. Mercaptoundecanoic ligand transfer was used to render water stable nanoparticles in a wide pH range. Transmission electron microscopy and dynamic light scattering (DLS) results show the nanoparticles slightly agglomerate after ligand exchange. Fourier transform infrared spectroscopy results suggest that thiol binds to the gold atoms of the surface

Structural phase transitions in BaTi0₃ studied via perturbed angular correlations

Phase transitions in the ferroelectric perovskite BaTiO₃ were studied for ^111In-implanted polycrystalline samples by measuring the electric field gradients by means of Perturbed Angular Correlation spectroscopy. The phase transitions between the orthorhombic double left right arrow rhombohedral double left right arrow tetragonal double left right arrow cubic lattices were investigated in 2 - 10 K steps, for increasing and decreasing temperatures, in order to determine their hysteresis. The transition parameters are compared with results from measurements of the spontaneous polarization, electric susceptibility and neutron scattering

A model of Mira's cometary head/tail entering the Local Bubble

We model the cometary structure around Mira as the interaction of an AGB wind from Mira A, and a streaming environment. Our simulations introduce the following new element: we assume that after 200 kyr of evolution in a dense environment Mira entered the Local Bubble (low density coronal gas). As Mira enters the bubble, the head of the comet expands quite rapidly, while the tail remains well collimated for a 100 kyr timescale. The result is a broad-head/narrow-tail structure that resembles the observed morphology of Mira's comet. The simulations were carried out with our new adaptive grid code WALICXE, which is described in detail.Comment: 12 pages, 8 figures (4 in color). Accepted for publication in The Astrophysical Journa

Interplay disorder-interaction in one dimensional quantum models

URL: http://www-spht.cea.fr/articles/S98/116 Compétition entre le désordre et les interactions dans des modèles quantiques unidimensionnels 210th WE-Heraeus Seminar (PILS'98), Berlin, Germany, October 6-9, 1998We show that the crossover from the weak interaction limit towards the strong interaction limit may be accompanied by a delocalization effect in one dimensional disordered quantum models. The spin degrees of freedom are frozen and the spatial wave functions remain symmetric or antisymmetric when the strength $U$ of a short range interaction is varied. The study concerns the excited states for two interacting particles and the ground state for a finite density of carriers. First, for two particles in a chain of length $L$, we establish a duality transformation mapping the behavior at weak $U$ onto the behavior at strong $U$. For intermediate $U$, the mixing of the one body states and the interaction induced delocalization effect are maximum. Furthermore, if $L \approx L_1$ (the one particle localization length), the system becomes weakly chaotic with critical spectral statistics. This weak chaos is related to the multifractality of the interaction matrix. For two particles starting close to each other, localization is reached in two steps. Before the time $t_1$ necessary to propagate over $L_1$, $U$ de-favors the propagation. On the contrary, $U$ favors a very slow delocalization after $t_1$, characterized by a $\log(t)$ spreading of the center of mass. Similarly, the curvatures of the energy levels with respect to an enclosed magnetic flux decrease as a function of $U$ for $LL_1$. The changes of the curvatures can be described by a conductance-like single scaling parameter. Second, using the density renormalization group algorithm, we have studied the ground state energy of a finite density of spinless fermions and its change under twisted boundary conditions. For a large disorder, a charge reorganization is induced by the interaction: When the system becomes instable between the inhomogeneous configuration driven by the random potential (Anderson insulator) and the homogeneous one driven by repulsive interactions (Mott insulator), the ground state sensitivity can be enhanced by orders of magnitude. In contrast, no enhancement occurs at weaker disorder, when there are many particles on a scale $L_1$. ----- Cet article est une revue des résultats obtenus récemment par les auteurs sur le rôle joué par l'interaction dans des systèmes unidimensionnels désordonnés. La première partie de l'article traite le problème de deux particules en interaction dans un potentiel aléatoire. On montre que les deux particules peuvent se propager de façon cohérente sur une distance $L_2$ beaucoup plus grande que la longueur de localisation $L_1$ d'une particule sans interaction. L'effet de délocalisation maximale se manifeste pour une valeur de l'interaction $U$ intermédiaire entre les deux limites $U=0$ et $U\to\infty$ et une transformation de dualité permet de passer d'une limite à l'autre. La structure multifractale des termes d'interaction de l'hamiltonien dans la base des états sans interaction influence la relation entre $L_2$ et $L_1$ et empêche la transition, engendrée par l'interaction, à un régime complètement chaotique. En changeant $U$ on parvient à un régime de ``chaos faible'', caractérisé par une statistique spectrale critique intermédiaire entre la statistique de Poisson (systèmes intégrables) et de Wigner (systèmes ergodiques). On montre que l'interaction est favorable au transport quand la longueur de localisation $L_1$ est plus petite que la taille $L$ du système et au contraire est défavorable quand $L_1>L$. Ceci est montré dans l'étude de la dynamique d'une paire de particules et de la courbure des niveaux énergétiques pour une boucle traversée par un flux d'Aharonov--Bohm. La deuxième partie de l'article étudie les propriétés de l'état fondamental d'un système de fermions sans spin. Des effets importants de délocalisation se manifestent quand le système devient instable entre les configurations limites $U=0$ (isolant d'Anderson) et $U\to\infty$ (isolant de Mott). La réorganisation des charges d'une limite à l'autre s'accompagne d'une grande sensibilité de l'énergie de l'état fondamental quand les conditions de bord de périodiques deviennent antipériodiques. L'article montre que l'effet de délocalisation semble persister à la limite thermodynamique. \hfill{G. Benenti