Identification and characterization of dendritic, parallel, pinnate, rectangular and trellis networks based on deviations from planform self-similarity

2006 Fall.Covers not scanned.Includes bibliographical references.Print version deaccessioned 2022.Geomorphologists have long recognized that the geometry of channel network planforms can vary significantly between regions depending on the local lithologic and tectonic conditions. This tendency has led to the classification of channel networks using terms such as dendritic, parallel, pinnate, rectangular, and trellis. Unfortunately, available classification methods are scale dependent and have no connection to an underlying quantitative theory of drainage network geometry or evolution. In this study, a new method is developed to classify drainage networks based on their deviations from self-similarity. The planform geometry of dendritic networks is known to be self-similar. It is our hypothesis that parallel, pinnate, rectangular, and trellis networks correspond to distinct deviations from this self-similarity. To identify such deviations, three measures of channel networks are applied to ten networks from each classification. These measures are the incremental accumulation of drainage area along channels, the irregularity of channel courses, and the angles formed by merging channels. The results confirm and characterize the self-similarity of dendritic networks. Parallel and pinnate networks are found to be self-affine with Hurst exponents around 0.8 and 0.7, respectively. Rectangular and trellis networks are approximately self-similar although deviations from self-similarity are observed. Rectangular networks have more sinuous channels than dendritic networks across all scales, and trellis networks have a slower rate of area accumulation than dendritic networks across all scales. Such observations are used to build and test classification trees, which are found to perform well in classifying networks

Kiskeya Reimagined: Relearning the Narratives Told about Dominican and Haitian Communities

Kiskeya Reimagined brings together Dominican and Haitian communities to watch a film documentary on specific causes to the historic conflict between the two societies; allowing for community reflections and expert panel discussions. The research uses conflict theory to describe the opposition between Dominicans and Haitians as a problem between class systems and colonial powers using their capital and racism as a tool to change the history of the island and manipulate the general population. Then mere-exposure theory is used as a method to increase the familiarity and likability between Haitians and Dominicans and lessen the fear created by those in power; this will consequently give space for social education and allow community building. The findings overwhelmingly demonstrate Kiskeya Reimagined is effective for peacebuilding among people of Dominican and Haitian decent. The participants left the event with an increased knowledge regarding the topic, increased willingness to continue being a part of these conversations, and ability to imagine the possibility of positive Dominican-Haitian relations

Dissipative vortex solitons in 2D-lattices

We report the existence of stable symmetric vortex-type solutions for two-dimensional nonlinear discrete dissipative systems governed by a cubic-quintic complex Ginzburg-Landau equation. We construct a whole family of vortex solitons with a topological charge S = 1. Surprisingly, the dynamical evolution of unstable solutions of this family does not alter significantly their profile, instead their phase distribution completely changes. They transform into two-charges swirl-vortex solitons. We dynamically excite this novel structure showing its experimental feasibility.Comment: 4 pages, 20 figure

Degradación de estructuras urbanas generada por crecimiento de plantas y actividad microbiana

The purpose of this study was to isolate microorganisms associated to surface-affected concrete structures and to measure the in vitro dissolution of concrete based on the release of elements such as calcium and silicon. Although many microorganisms were detected only a fungus was capable of significantly decreasing the culture medium pH and releasing both elements. The molecular characterization allowed to identify the microorganism as Aspergillus carbonaurius, a citric-acid producing fungus that dissolved concrete in the in vitro test. After seven days of incubation, the soluble calcium concentration in the uninoculated culture medium containing concrete was 172.3 mg/L, while in the inoculated medium it was 525.0 mg/L. The soluble silicon concentration in the uninoculated medium was 10.3 mg/L, while in the inoculated medium it was 50.1 mg/L. These findings showed that plants and microorganisms rendered a synergistic effect accelerating the biodeterioration of concrete.El objetivo de este estudio fue aislar microorganismos de la superficie de estructuras urbanas de concreto deterioradas y medir su capacidad para disolver in vitro muestras de concreto, basada en la liberación de elementos como el calcio y el silicio. De todos los microorganismos aislados sólo un hongo fue capaz de disminuir el pH y disolver el concreto. Este hongo fue identificado a nivel molecular como Aspergillus carbonaurius, un productor de ácido cítrico. Después de siete días de incubación, se encontró que la concentración de calcio soluble en el medio de cultivo no inoculado fue 172,3 mg/L, mientras que en el medio inoculado era de 525,0 mg/L. La concentración de silicio soluble en el medio no inoculado fue de 10,3 mg/L, mientras que en el medio inoculado fue de 50,1 mg/L. Estos hallazgos mostraron que las plantas y los microorganismos producen un efecto sinérgico que acelera el biodeterioro del concreto

Spatial rogue waves in photorefractive SBN crystals

We report on the excitation of large-amplitude waves, with a probability of around 1% of total peaks, on a photorefractive SBN crystal by using a simple experimental setup at room temperature. We excite the system using a narrow Gaussian beam and observe different dynamical regimes tailored by the value and time rate of an applied voltage. We identify two main dynamical regimes: a caustic one for energy spreading and a speckling one for peak emergence. Our observations are well described by a two-dimensional Schr\"odinger model with saturable local nonlinearity.Comment: 4 pages, 4 figure

Diagnóstico de los Niveles I: Acercar y II: Promoción de la producción y el consumo sostenible, del Programa de Gestión Ambiental Empresarial en Bogotá D.C.

(Eng) Evaluation and feedback are essential in all management processes, especially when actions are aimed at target level of a local authority, especially as complex as a capital district. This document presents the main findings of the diagnosis that was made in Levels I and II of the Environmental Business Management Program (GAE by its acronym in spanish) in Bogota. For its development, management reports generated by the Secretaría Distrital de Ambiente (SDA) were consulted, and the approach of the actions in levels I and II quantitatively and qualitatively were evaluated. On the other hand, surveys were formulated and applied to both participating and external companies, the first ones, in spaces of the GAE Program, provided by the SDA, and the second through visits, phone calls and electronic mails. The analysis and processing of these data allowed us to establish the impact of levels I and II of the GAE Program on the perception, support and management of Cleaner Production (CP) and Sustainable Consumption (SC) in companies grounded in Bogota, the Capital District. Finally, based on the above, as well as in consultations with external entities, the recommendations for the planning and execution in order to contribute to the continuous improvement in the promotion of CP and SC in the productive sector were made.(Spa) La evaluación y la retroalimentación son fundamentales en todos los procesos de gestión, aún más cuando están dirigidos a orientar actuaciones a nivel de un ente territorial, especialmente tan complejo como lo es un Distrito Capital. El presente documento expone los principales hallazgos del diagnóstico que se realizó en los niveles I y II del Programa de Gestión Ambiental Empresarial (GAE) en la ciudad de Bogotá. Para su desarrollo, se consultaron los informes de gestión generados por la Secretaría Distrital de Ambiente (SDA) y se evaluaron cuantitativa y cualitativamente los planteamientos de las acciones consideradas en los niveles I y II. Por otra parte, se formularon y aplicaron encuestas tanto a empresas participantes como empresas externas, las primeras, en espacios propios del Programa GAE, facilitados por la SDA y las segundas a través de visitas, llamadas y correos electrónicos. El análisis y procesamiento de estos datos permitió establecer el impacto que han tenido los niveles I y II del Programa GAE en la percepción, el apoyo y la gestión de la Producción Más Limpia (PML) y Consumo Sostenible (CS) en las empresas con sede en Bogotá, Distrito Capital. Finalmente, basado en lo anterior, así como en consultas en entes externos, se formularon las recomendaciones pertinentes para la planeación y la ejecución con el fin de contribuir a la mejora continua en el fomento de la PML y CS en el sector productivo