Continuous Forest Fire Propagation in a Local Small World Network Model

This paper presents the development of a new continuous forest fire model implemented as a weighted local small-world network approach. This new approach was designed to simulate fire patterns in real, heterogeneous landscapes. The wildland fire spread is simulated on a square lattice in which each cell represents an area of the land's surface. The interaction between burning and non-burning cells, in the present work induced by flame radiation, may be extended well beyond nearest neighbors. It depends on local conditions of topography and vegetation types. An approach based on a solid flame model is used to predict the radiative heat flux from the flame generated by the burning of each site towards its neighbors. The weighting procedure takes into account the self-degradation of the tree and the ignition processes of a combustible cell through time. The model is tested on a field presenting a range of slopes and with data collected from a real wildfire scenario. The critical behavior of the spreading process is investigated

Surface-peaked medium sensitivity of the optical potential: an exact result

Microscopic optical model potentials for elastic hadron-nucleus scattering usually take the form of a convolution of a two-body effective interaction with the target ground-state mixed density. Within the Brueckner-Bethe-Goldstone gmatrix approach for the effective interaction, nuclear medium effects are made explicit by means spatial integrals throughout the bulk of the nucleus. In this contribution we discuss a novel and exact approach to track down the manifestation of intrinsic nuclear medium effects. After examining the momentumand coordinate-space structure of a two-body effective interaction –spherically symmetric in its mean coordinate– it is demonstrated that the intrinsic medium effects in the optical potential depend solely on the gradient of a reduced interaction. This feature implies the confinement of intrinsic medium effects to regions where the density varies most, i.e. the nuclear surface. This finding may be of special significance in the study of nuclear collisions sensitive to the peripheric structure of nuclei. We illustrate some of its implications in the context of 10Be + p elastic scattering at 39.1A MeV

Efectos de los temporales sobre las playas de la Bahía de Cádiz

[Resumen] En el presente trabajo se estudian los efectos que los temporales de Diciembre e 1995 y Enero de 1996 tuvieron sobre las playas de la Bahía de Cádiz. Del análisis del oleaje incidente se observa cómo sus efectos se multiplican cuando los picos de temporal coinciden con el máximo rango de mareas. Los cambios morfológicos registrados en las playas se estudian mediante el perfilamiento pre y post-temporal de playas tanto naturales como regeneradas artificialmente. La cuantificación de dichos cambios muestra cómo la forma inicial de los perfiles es determinante en el tipo de respuesta de las playas frente a olejaes de gran energía. También se manifiestan procesos de erosión en cordones dunares, mediante incisiones, desbordamientos, etc. La estimación final de los daños sufridos por las playas revela mayores pérdidas en aquellas zonas donde la presión antrópica es mayor[Abstract] The work deals with the effects that the storm surges of December-1995 and January-1996 made upon the beaches of Cádiz Bay (SW Spain). From the incidentwave analysis it can be deduced that the effects are much stronger when the surge peak coincides with maximum tidal ranges. The morphological changes recorded in the beaches are studied through pre- and post-surge profiling of both natural and artificially nourished beaches. The quantification of such morphological transformations shows that the initial beach profile is determinant in the kind of response of the beach to high wave-energy conditions. The erosive processes upon dune ridges are represented by gullying, overwashing, etc. The final estimation of losses in the beaches reveals higher damages in zones where anthropic preassure is higher

Why Ni3_3Al is an itinerant ferromagnet but Ni3_3Ga is not

Ni$_3$Al and Ni$_3$Ga are closely related materials on opposite sides of a ferromagnetic quantum critical point. The Stoner factor of Ni is virtually the same in both compounds and the density of states is larger in Ni$_3$Ga. So, according to the Stoner theory, it should be more magnetic, and, in LDA calculations, it is. However, experimentally, it is a paramagnet, while Ni$_3$Al is an itinerant ferromagnet. We show that the critical spin fluctuations are stronger than in Ni$_3$Ga, due to a weaker q-dependence of the susceptibility, and this effect is strong enough to reverse the trend. The approach combines LDA calculations with the Landau theory and the fluctuation-dissipation theorem using the same momentum cut-off for both materials. The calculations provide evidence for strong, beyond LDA, spin fluctuations associated with the critical point in both materials, but stronger in Ni$_3$Ga than in Ni$_3$Al.Comment: replaced (incorrect version submitted

Comparative Genomics Analysis of a New Exiguobacterium Strain from Salar de Huasco Reveals a Repertoire of Stress-Related Genes and Arsenic Resistance

Indexación: Web of Science; Scopus.The Atacama Desert hosts diverse ecosystems including salt flats and shallow Andean lakes. Several heavy metals are found in the Atacama Desert, and microorganisms growing in this environment show varying levels of resistance/tolerance to copper, tellurium, and arsenic, among others. Herein, we report the genome sequence and comparative genomic analysis of a new Exiguobacterium strain, sp. SH31, isolated from an altiplanic shallow athalassohaline lake. Exiguobacterium sp. SH31 belongs to the phylogenetic Group II and its closest relative is Exiguobacterium sp. S17, isolated from the Argentinian Altiplano (95% average nucleotide identity). Strain SH31 encodes a wide repertoire of proteins required for cadmium, copper, mercury, tellurium, chromium, and arsenic resistance. Of the 34 Exiguobacterium genomes that were inspected, only isolates SH31 and S17 encode the arsenic efflux pump Acr3. Strain SH31 was able to grow in up to 10 mM arsenite and 100 mM arsenate, indicating that it is arsenic resistant. Further, expression of the ars operon and acr3 was strongly induced in response to both toxics, suggesting that the arsenic efflux pump Acr3 mediates arsenic resistance in Exiguobacterium sp. SH31.http://journal.frontiersin.org/article/10.3389/fmicb.2017.00456/ful

Gulf of Cadiz beaches: A comparative response to storm events

The aim of the present paper is to compare the profile response of two mesotidal beaches (Faro, 10 km long, Algarve; La Barrosa, 8 km long, Cadiz) within a single regional physiographic unit (the Gulf of Cadiz) to the same storm event (January, 1996). For this comparison, a series of beach surveys was used, including a total of 10 study sites, five at each study area. The two beaches belong to exposed, mesotidal, sandy shores, and have a similar coastal orientation. However, the response time-scale is different for each one. Faro showed a total amount of 130 000 m³ of erosion due to the storm, with a complete post-storm recovery after one tidal cycle. La Barrosa had a total sand loss of 80 000 m³ due to the storm, with a final recovery of 60 000 m³, 4-6 months after the event. These differences are due to the beaches' different morphodynamic behaviours. Whereas Faro is a reflective beach, with dominant plunging breakers, La Barrosa is mainly dissipative, having spilling breakers. The difference in beach slope and grain size could also be important in determining their response to storm events.El objetivo del presente trabajo es comparar la respuesta, ante un mismo episodio de tormenta (enero de 1996), de dos playas mesomareales de comportamiento distinto (Praia de Faro, de 10 km de longitud en el Algarve, y La Barrosa, de 8 km de longitud en Cádiz) pero pertenecientes a la misma unidad fisiográfica (el golfo de Cádiz). Para esta comparación se han estudiado una serie de levantamientos topográficos que incluyen un total de diez líneas de perfilamiento, cinco en cada área de estudio. Ambas playas se localizan en costas arenosas, expuestas, mesomareales y con una orientación similar. Sin embargo, el tiempo de respuesta es diferente en cada caso. Praia de Faro mostró una erosión total de 130 000 m³ debida a temporales y una recuperación completa tras un único ciclo mareal. La Barrosa presentó una pérdida total de arena de 80 000 m³ asociada a los temporales, con una recuperación final de 60 000 m³ después de 4 a 6 meses de los temporales. Estas diferencias son debidas al desigual comportamiento morfodinámico mostrado por ambas playas. Así, mientras Praia de Faro es una playa reflectiva con rotura dominante de tipo plunging, La Barrosa es predominantemente disipativa y con una rotura de tipo spilling. Del mismo modo, las diferencias en la pendiente y el tamaño de grano pueden ser también importantes a la hora de explicar la respuesta de ambas playas ante la llegada de temporales.Instituto Español de Oceanografí

Surface-peaked medium effects in the interaction of nucleons with finite nuclei

We investigate the asymptotic separation of the optical model potential for nucleon-nucleus scattering in momentum space, where the potential is split into a medium-independent term and another depending exclusively on the gradient of the density-dependent g matrix. This decomposition confines the medium sensitivity of the nucleon-nucleus coupling to the surface of the nucleus. We examine this feature in the context of proton-nucleus scattering at beam energies between 30 and 100 MeV and find that the pn coupling accounts for most of this sensitivity. Additionally, based on this general structure of the optical potential we are able to treat both, the medium dependence of the effective interaction and the full mixed density as described by single-particle shell models. The calculated scattering observables agree within 10% with those obtained by Arellano, Brieva and Love in their momentum-space g-folding approach.Comment: 16 pages, 8 figures, submitted to PR

Governance for Sustainability in an Organization in Central Mexico

Often, the total quality has been instrumented before being weighted. The strategies even precede a diagnosis in Mexican organizations, but in an opposite sense, the present work set out to establish the reliability and validity of an instrument to measure the perception of total quality based on three indicators related to management. , production and transfer of knowledge. A nonperimental study was carried out with a non-probabilistic selection of 124 administrative staff and employees from an organization in central Mexico. From a structural model ⌠X2 = 123,24 (23df) p = 0,010; GFI = 0,990; CFI =,991; IFI = 0,993; RMSEA = 0,007⌡, it was found that management affects production (0,38) and this about the total perceived quality (0,35), although there are lines of research concerning empathy, commitment, entrepreneurship, satisfaction and happiness in relation to the implementation of continuous improvements to the quality of processes and products

Joint Distribution of Distance and Angles in Finite Wireless Networks

Directional beamforming will play a paramount role in 5G and beyond networks in order to combat the higher path losses incurred at millimeter wave bands. Appropriate modeling and analysis of the angles and distances between transmitters and receivers in these networks are thus essential to understand performance and limiting factors. Most existing literature considers either infinite and uniform networks, where nodes are drawn according to a Poisson point process, or finite networks with the reference receiver placed at the origin of a disk. Under either of these assumptions, the distance and azimuth angle between transmitter and receiver are independent, and the angle follows a uniform distribution between $0$ and $2\pi$. Here, we consider a more realistic case of finite networks where the reference node is placed at any arbitrary location. We obtain the joint distribution between the distance and azimuth angle and demonstrate that these random variables do exhibit certain correlation, which depends on the shape of the region and the location of the reference node. To conduct the analysis, we present a general mathematical framework which is specialized to exemplify the case of a rectangular region. We then also derive the statistics for the 3D case where, considering antenna heights, the joint distribution of distance, azimuth and zenith angles is obtained. Finally, we describe some immediate applications of the present work, including the analysis of directional beamforming, the design of analog codebooks and wireless routing algorithms.Comment: 14 pages, 14 figure