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Search Results: 1 - 10 of 34050 matches for " Thomas Fischer "
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Fischer Thomas
Anuario Colombiano de Historia Social y de la Cultura , 1998,
Abstract: José C. Moya, Cousins and Strangers; Spanish Immigrants in Buenos Aires 1850-1930. Berkeley-Los Angeles-London: University of California Press 1998. 567 páginas. / Jeffrey Lesser: Welcoming the Undesirables: Brazil and the Jewish Question. Berkeley-Los Angeles-London: University of California Press 1995. 280 páginas.
State the building and conflict resolution in Colombia, 1986-1994
Fischer Thomas
Anuario Colombiano de Historia Social y de la Cultura , 2000,
Abstract: Harvey F. Kline. State Building and Conflict Resolution in Colombia, 1986-1994. Tuscaloosa/London: The University of Alabama Press 1999. 240 páginas. últimamente el conflicto interno de Colombia llama la atención de reputados politólogos norteamericanos que anteriormente se habían dedicado a la investigación de la democracia más estable de América Latina, cuyos pilares son los dos partidos políticos centristas, el ejercicio militar y los gremios económicos. Harvey F. Kline es uno de ellos, pero a diferencia de otros, en sus textos siempre ha prevalecido la preocupación por las deficiencias del sistema político respecto a los derechos humanos, la policía y la justicia. Su último estudio, titulado State Building and Conflict Resolution in Colombia, 1986-1994, se centra en la ingobernabilidad colombiana. Ello resulta de la incapacidad y escasa voluntad de la clase dirigente de resolver los conflictos del país.
Antes de la separación de Panamá: la guerra de los mil días, el contexto internacional y el canal
Fischer Thomas
Anuario Colombiano de Historia Social y de la Cultura , 1998,
Abstract: Los contemporáneos de finales del siglo pasado eran conscientes de vivir en un periodo de transición, que llevaba en su seno profundas contradicciones, sin saber qué les depararia el nuevo siglo. Así pues, se sentían los hombres que hacían historia al final del siglo pasado en Colombia. En 1899 empezó una guerra civil, la llamada guerra de los mil días. Este enfrentamiento significó la culminación de una serie de guerras civiles que marcaron el siglo XIX. Aunque el conflicto armado entre liberales y conservadores no afectó a todas las regiones de la misma manera, dividió a la población más que nunca. Fue quizá la guerra más desastrosa, tanto en lo referente a los da os ocasionados en la economía nacional como en relación a las bajas humanas registradas. Un a o después del final de la guerra se separó el departamento de Panamá. Esto se debió a la fragilidad del concepto nacional de Colombia que tenía un sistema político poco apto para asistir a la negociación del problema más urgente de la agenda internacional del país: la transacción de los derechos para excavar y construir por territorio colombiano un canal que uniría el Oceano Atlántico con el Pacífico en favor de los Estados Unidos. Con la ocupación de Cuba y Puerto Rico esta potencia se había establecido como poder hegemónico en la región, desplazando a las potencias europeas. No cabe duda de que la crisis que atravesó Colombia marcó un cambio fundamental en la conciencia nacional.
A Necessary Solution Condition for Sudoku
Thomas Fischer
Mathematics , 2012,
Abstract: We develop a new discrete mathematical model which includes the classical Sudoku puzzle, Latin Squares and gerechte designs. This problem is described by integer equations and a special type of inequality constraint. We consider solutions of this generalized problem and derive a necessary condition on these solutions. The results are illustrated with examples.
Duality for Sudoku
Thomas Fischer
Mathematics , 2013,
Abstract: We consider a mathematical model for the classical Sudoku puzzle, which we call the primal problem and introduce a corresponding dual problem. Both problems are constraint satisfaction models and a duality relation between them is proved. Based on these models, we introduce a primal and a dual optimization problem and show weak and strong duality properties.
Unicity Concepts for Sudoku
Thomas Fischer
Mathematics , 2014,
Abstract: This paper deals with a generalized Sudoku problem and investigates the unicity of a given solution. We introduce constraint sets, which is a generalization of the rows, columns and blocks of a classical Sudoku puzzle. The unicity property is characterized by three different properties. We describe unicity by permutations, by unicity cells and by rectangles. These terms are defined in this paper and are illustrated with examples. Throughout this paper we are not concerned with the existence of a solution.
Long-Term Release of Iron-Cyanide Complexes from the Soils of a Manufactured Gas Plant Site  [PDF]
Magdalena Sut, Thomas Fischer, Frank Repmann, Thomas Raab
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.411B002
Abstract:

Iron-cyanide (Fe-CN) complexes have been detected at Manufactured Gas Plant sites (MGP) worldwide. The risk of groundwater contamination depends mainly on the dissolution of ferric ferrocyanide. In order to design effective remediation strategies, it is relevant to understand the contaminant’s fate and transport in soil, and to quantify and mathematically model a release rate. The release of iron-cyanide complexes from four contaminated soils, originating from the former MGP in Cottbus, has been studied by using a column experiment. Results indicated that long-term cyanide (CN) release is governed by two phases: one readily dissolved and one strongly fixed. Different isotherm and kinetic equations were used to investigate the driving mechanisms for the ferric ferrocyanide release. Applying the isotherm equations assumed an approach by which two phases were separate in time, whereas the multiple first order equation considered simultaneous occurrence of both cyanide pools. Results indicated varying CN release rates according to the phase and soil. According to isotherm and kinetic models, the long-term iron cyanide release from the MGP soils is a complex phenomenon driven by various mechanisms parallely involving desorption, diffusion and transport processes. Phase I (rapid release) is presumably mainly constrained by the transport process of readily dissolved iron-cyanide complexes combined with desorption of CN bound to reactive heterogeneous surfaces that are in direct contact with the aqueous phase (outer-sphere complexation). Phase II (limited rate) is presumably driven by the diffusion controlled processes involving dissolution of precipitated ferric ferrocyanide from the mineral or inner-sphere complexation of ferricyanides. CN release rates in phase I and II were mainly influenced by the pH, organic matter (OM) and the total CN content. The cyanide release rates increased with increasing pH, decreased with low initial CN concentration and were retarded by the increase in OM content.

A contribution to the Adaptive Numerical Solution of Compressible Flow Problems
Fischer, Thomas R.
Informes de la Construccion , 1996,
Abstract:
Using ω-Circulant Matrices for the Preconditioning of Toeplitz Systems
Rainer Fischer,Thomas Huckle
Sel?uk Journal of Applied Mathematics , 2003,
Abstract: Toeplitz systems can be solved efficiently by using iterative methods such as the conjugate gradient algorithm. If a suitable preconditioner is used, the overall cost of the method is O(n log(n)) arithmetic operations. Circulant matrices are frequently employed for the preconditioning of Toeplitz systems.They can be chosen as preconditioners themselves, or they can be used for the computation of approximate inverses. In this article, we take the larger class of ω -circulant matrices instead of the well-known circulants to extend preconditioners of both types.This extension yields an additional free parameter ω which can be chosen in a way that speeds up convergence of the conjugate gradient method. The additional computational effort arising from the use of ω-circulant instead of circulant matrices is low.
Network processes involved in the mediation of short-term habituation in Aplysia: contribution of intrinsic regulation of excitability and synaptic augmentation
Thomas M. Fischer
Frontiers in Integrative Neuroscience , 2014, DOI: 10.3389/fnint.2014.00015
Abstract: Short-term habituation (STH) is the decrease in behavioral responding observed during repeated stimulation at regular intervals. For siphon-elicited siphon withdrawal in Aplysia (S-SWR), we previously showed that the amplitude of responses measured in LFS-type siphon motor neurons (LFS MNs) during training is dependent on the stimulus interval used and is training-site specific. The major source of excitation from siphon stimulation onto the LFS MNs comes from the L29 interneurons. Here we examined the role of the L29s in STH by addressing two questions:
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