21 research outputs found
Analysis of water erosion using GIS and remote sensing for the management of protected natural environments in the south of the province of Salamanca (Spain)
Resumen del trabajo presentado al IV International Symposium on Gully Erosion, celebrado en la Universidad Pública de Navarra del 17 al 19 de septiembre de 2007.The soil is a natural resource that must be conserved in
protected natural areas since it is one of the determinant
physical supports in territorial planning because it governs
its different uses. Accordingly, specific studies must be
carried out aimed at estimating soil losses at individual
project level and at the general level of Natural Environments
in order to establish methodologies for the control and
ordering of activities, above all in protected environments
whose focus is on sustainable activities. The basic objective
should delimit different erosive forms where best it reflects
the risk of water erosion (gullies, rills) and the degree
(weak, light, important, and burden) and the processes
induced (slides, scarp, remontant erosion...) in addition the
evolution with time.Part of the work reported in this paper was financially
supported by the GCL 2005-04655/BTE and CGL 2005-01336/BTE
Projects
Flux-induced SUSY-breaking soft terms on D7-D3 brane systems
We study the effect of RR and NSNS 3-form fluxes on the effective action of
the worldvolume fields of Type IIB D7/D3-brane configurations. The D7-branes
wrap 4-cycles on a local Calabi-Yau geometry. This is an extension of previous
work on hep-th/0311241, where a similar analysis was applied to the case of
D3-branes. Our present analysis is based on the D7- and D3-brane
Dirac-Born-Infeld and Chern-Simons actions, and makes full use of the
R-symmetries of the system, which allow us to compute explicitly results for
the fields lying at the D3-D7 intersections. A number of interesting new
properties appear as compared to the simpler case of configurations with only
D3-branes. As a general result one finds that fluxes stabilize some or all of
the D7-brane moduli. We argue that this is important for the problem of
stabilizing Kahler moduli through non-perturbative effects in KKLT-like vacua.
We also show that (0,3) imaginary self-dual fluxes, which lead to
compactifications with zero vacuum energy, give rise to SUSY-breaking soft
terms including gaugino and scalar masses, and trilinear terms. Particular
examples of chiral MSSM-like models of this class of vacua, based on D3-D7
brane systems at orbifold singularities are presented.Comment: 58 pages, no figures; v2: numerical factor in section 7.2 correcte
M5-brane geometries, T-duality and fluxes
We describe a duality relation between configurations of M5-branes in
M-theory and type IIB theory on Taub-NUT geometries with NSNS and RR 3-form
field strength fluxes. The flux parameters are controlled by the angles between
the M5-brane and the (T)duality directions. For one M5-brane, the duality leads
to a family of supersymmetric flux configurations which interpolates between
imaginary self-dual fluxes and fluxes similar to the Polchinski-Strassler kind.
For multiple M5-branes, the IIB configurations are related to fluxes for
twisted sector fields in orbifolds. The dual M5-brane picture also provides a
geometric interpretation for several properties of flux configurations (like
the supersymmetry conditions, their contribution to tadpoles, etc), and for
many non-trivial effects in the IIB side. Among the latter, the dielectric
effect for probe D3-branes is dual to the recombination of probe M5-branes with
background ones; also, a picture of a decay channel for non-supersymmetric
fluxes is suggested.Comment: 30 pages, 3 figure
Topological A-Type Models with Flux
We study deformations of the A-model in the presence of fluxes, by which we
mean rank-three tensors with antisymmetrized upper/lower indices, using the
AKSZ construction. Generically these are topological membrane models, and we
show that the fluxes are related to deformations of the Courant bracket which
generalize the twist by a closed 3-from , in the sense that satisfying the
AKSZ master equation implies the integrability conditions for an almost
generalized complex structure with respect to the deformed Courant bracket. In
addition, the master equation imposes conditions on the fluxes that generalize
. The membrane model can be defined on a large class of - and -structure manifolds, including geometries inspired by
supersymmetric -models with additional supersymmetries due to almost
complex (but not necessarily complex) structures in the target space.
Furthermore, we show that the model can be defined on three particular
half-flat manifolds related to the Iwasawa manifold.
When only -flux is turned on it is possible to obtain a topological string
model, which we do for the case of a Calabi-Yau with a closed 3-form turned on.
The simplest deformation from the A-model is due to the
component of a non-trivial -field. The model is generically no longer
evaluated on holomorphic maps and defines new topological invariants.
Deformations due to -flux can be more radical, completely preventing
auxiliary fields from being integrated out.Comment: 30 pages. v2: Improved Version. References added. v3: Minor changes,
published in JHE
Present and potential erosion at Protected Landscape “El Rebollar” (Sierra de Gata – Salamanca)
Este estudio permitirá conocer la importancia de los procesos erosivos actuales y potenciales en estudios del medio físico, en zonas protegidas, lo que ayudará a tomar decisiones más adecuadas en la ordenación del territorio, y a establecer medidas de protección, con el fin de evitar la pé.rdida de suelo. Entre los muchos métodos para estudiar la erosión, se ha elegido el método USLE (Universal Soil Loss Equation) por erosión laminar y en regueros, al no requerir un gran volumen de datos de entrada y por haber sido aplicado a numerosos estudios ofreciendo buenos resultados, sin olvidar sus limitaciones y adaptándolo a la zona. Mediante el uso del SIG se han generado cartografías para cada uno de los parámetros de la USLE, a partir de las cuales se ha obtenido la erosión potencial y actual. Los resultados muestran que los valores potenciales de pérdida de suelo son débiles en la mayor parte, coincidiendo con los dominios geomorfológicos de pedimento y colinas y lomas. Las zonas más erosionables (erosión actual) coinciden con las de mayor altitud, en laderas con escasa vegetación en la vertiente norte de la Sierra de Francia, este de Martiago y en el escarpe e incisiones fluviales; atenuándose sensiblemente en la vertiente norte de la Sierra de Gata.This study will allow knowing the importance of present and potential erosive processes that will help to make adequate decisions in protected areas, and to establish protection measures if it would be necessary in order to avoid soil losses. Among all available methods to study soil erosion, the USLE (Universal Soil Loss Equation) one was chosen, because it is not necessary a huge volume of input data and it has been applied in several studies offering good results (it is important to know its limitations and to adapt it to the study area). Cartographies for each of the parameters in USLE equation were generated with the use of G.I.S, from which was calculated potential and present erosion. Results show that potential values of soil losses are low in the most of the area, coinciding with geomorphologic domains of pediment and hills. The areas more subject to erosion (present erosion) correspond to the ones with higher altitude, in slopes with limited vegetation in the north slope of Sierra de Francia, east of Martiago and in the fall scarp and fluvial incisions; decreasing considerably in the north slope of Sierra de Gata .Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEMinisterio de Ciencia e Innovación (MICINN)Junta de Castilla y Leónpu
Fluxes, moduli fixing and MSSM-like vacua in a simple IIA orientifold
We study the effects of adding RR, NS and metric fluxes on a T^6/(\Omega
(-1)^{F_L} I_3) Type IIA orientifold. By using the effective flux-induced
superpotential we obtain Minkowski or AdS vacua with broken or unbroken
supersymmetry. In the Minkowski case some combinations of real moduli remain
undetermined, whereas all can be stabilized in the AdS solutions. Many flux
parameters are available which are unconstrained by RR tadpole cancellation
conditions allowing to locate the minima at large volume and small dilaton. We
also find that in AdS supersymmetric vacua with metric fluxes, the overall flux
contribution to RR tadpoles can vanish or have opposite sign to that of
D6-branes, allowing for new model-building possibilities. In particular, we
construct the first N=1 supersymmetric intersecting D6-brane models with
MSSM-like spectrum and with all closed string moduli stabilized. Some
axion-like fields remain undetermined but they are precisely required to give
St\"uckelberg masses to (potentially anomalous) U(1) brane fields. We show that
the cancellation of the Freed-Witten anomaly guarantees that the axions with
flux-induced masses are orthogonal to those giving masses to the U(1)'s.
Cancellation of such anomalies also guarantees that the D6-branes in our N=1
supersymmetric AdS vacua are calibrated so that they are forced to preserve one
unbroken supersymmetry.Comment: 61 pages, Latex, v2: added references, v3: minor correction
Dominant soil map in ‘Las Batuecas-Sierra De Francia’ and ‘Quilamas’ nature parks (Central System, Salamanca, Spain)
<p>To correctly and rationally plan human activities in fragile conservation areas, an exhaustive study of the soil-forming factors (climate, lithology, geomorphology, topography, hydrology and vegetation) including the soil relationships, should be conducted. We analysed the geospatial distributions of different soil types in the ‘Las Batuecas – Sierra de Francia’ and ‘Quilamas’ natural areas using soil sampling and laboratory analyses to determine the soil associations and dominant soil types and so create toposequence maps. These maps were used to assess potential soil uses and resources and to identify environmental problems from natural and/or anthropogenic causes. The GIS techniques used in this study provide georeferenced maps of forming factors and soil distribution that can be used to create databases that include fact sheets and photographs of the soil profiles. This soil information was exported in ‘kmz’ format to geospatially visualise the different soil units in 3D virtual tours using the Google Earth platform. This method of soil mapping allows a multidisciplinary approach that utilises other thematic layers and facilitates decision-making processes by the managers and directors of the natural areas studied in this work.</p