Geologic Survey of the Ewing Bank, Northern Gulf of Mexico

Located along the edge of the continental shelf in the northwestern Gulf of Mexico, the Ewing Bank is a significant geologic feature: yet, little information about the bank is generally available. This thesis represents a preliminary survey of the distribution and structure of the seafloor sediments that comprise the bank and the surrounding area. Two research vessels were utilized to accomplish the survey: the RV Gyre collected geologic cores and sub-bottom profiler lines courtesy of TDI-Brooks International and the RV Falkor collected multibeam echo sounder bathymetry courtesy of the Schmidt Ocean Institute. The bathymetry collected by the sub-bottom profiler and multibeam echo sounder data for this study is consistent with the coarser resolution data previously available. The pattern of seismic reflectors in the sub-bottom profiles indicated the orientation and type of faults as well as other structures. The geologic cores and sub-bottom profiler data helped to identify the different types and distributions of the sediments that made up this two terrace bank system. A core from the surface of the top terrace contained coarse carbonate sands while the seafloor surrounding this bank was comprised of firm clay sediment. The characteristics of surficial sediments on the second, deeper terrace were closer to those on the seafloor surrounding the bank than the top terrace of the Ewing Bank itself. This difference may reflect winnowing by the shelf edge currents interacting with the structure of the Ewing Bank together with the fact that the top terrace was subject to shallow water wave action and subaerial exposure during the lowstand of sea level associated with the last glactiation; while the surficial sediments of the second terrace were deposited since sea level rose after the end of the last glaciation. The features of the Ewing Bank compared well with those of the surrounding banks of the area. The results of this preliminary survey of the Ewing Bank contribute to the general understanding of the geologic features and biological habitat at the many banks in the north western Gulf of Mexico and the geologic processes that affect them

An Optimal Linear Time Algorithm for Quasi-Monotonic Segmentation

Monotonicity is a simple yet significant qualitative characteristic. We consider the problem of segmenting a sequence in up to K segments. We want segments to be as monotonic as possible and to alternate signs. We propose a quality metric for this problem using the l_inf norm, and we present an optimal linear time algorithm based on novel formalism. Moreover, given a precomputation in time O(n log n) consisting of a labeling of all extrema, we compute any optimal segmentation in constant time. We compare experimentally its performance to two piecewise linear segmentation heuristics (top-down and bottom-up). We show that our algorithm is faster and more accurate. Applications include pattern recognition and qualitative modeling.Comment: This is the extended version of our ICDM'05 paper (arXiv:cs/0702142

A vortex population viability analysis model for the Chacoan peccary (catagonus wagneri)

El quimilero o taguá (Catagonus wagneri) es una especie amenazada, endémica del Chaco Seco, para la cual disponemos de poca información. Para estimar cuantitativamente el riesgo de disminución y extinción de sus poblaciones silvestres generamos modelos de viabilidad poblacional. Con estos modelos matemáticos se pueden identificar factores naturales y antrópicos complejos que interactúan y que influyen en la persistencia y la salud de una población. Los modelos también se pueden utilizar para evaluar los efectos de diferentes estrategias de gestión, permitiendo identificar las acciones de conservación más efectivas para una población o especie. Además, estos modelos se pueden usar para identificar las necesidades de investigación debido a que ponen en evidencia los vacíos de información sobre la especie. Utilizando estos modelos, evaluamos la proyección poblacional en las condiciones actuales y en comparación con posibles variaciones existentes en el sistema. Para generar los parámetros ingresados en los modelos realizamos una reunión de especialistas y una revisión bibliográfica. Trabajó con valores de línea de base (base), mínimos (mín.) y máximos (máx.). Generamos diferentes modelos ante diferentes escenarios y testeamos la sensibilidad a la incertidumbre de cada modelo. Esto permitió establecer prioridades de investigación. Además, determinamos los tamaños mínimos de población viable considerando la incertidumbre y analizamos los posibles efectos de la caza en una población de esta especie.Fil: Leus, Kritin. International Union for Conservation of Nature. Species Survival Commission; DinamarcaFil: Altrichter, Mariana. International Union for Conservation of Nature. Species Survival Commission; Estados UnidosFil: Desbiez, Arnaud. International Union for Conservation of Nature. Species Survival Commission; BrasilFil: Camino, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Giordano, Anthony J.. S.P.E.C.I.E.S.; Estados UnidosFil: Campos Krauer, Juan Manuel. University of Florida. Department of Wildlife Ecology and Conservation; Estados Unidos. Centro Chaqueño para la Conservación y la Investigación; ParaguayFil: Brooks, Daniel M.. Houston Museum Of Natural Science; Estados UnidosFil: Thompson, Jeffrey. Consejo Nacional de Ciencia y Tecnología; ParaguayFil: Núñez Regueiro, Mauricio Manuel. University of Florida. Department of Wildlife Ecology and Conservation; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin