264 research outputs found
Traumatic aniridia in a pseudophakic patient 6 years following surgery
Mikel Mikhail1, Keyvan Koushan2, Rajeshvar K Sharda2, Gloria Isaza2, Keith D Mann21Michael G DeGroote School of Medicine, 2Division of Ophthalmology, Department of Surgery, McMaster University, Hamilton, ON, CanadaPurpose: To report a case of aniridia in a pseudophakic patient following blunt trauma to the eye.Case report: The traumatized eye had cataract surgery through a 3.0 mm clear corneal incision 6 years prior to the incident. While there have been previous cases of traumatic aniridia in pseudophakic eyes, previous reports have all occurred closer to the time of the cataract surgery. We believe that the most likely mechanism of loss of iris tissue is through wound dehiscence, which would suggest the relative instability of clear corneal incisions several years postoperatively. The patient's visual acuity returned to 20/20 4 weeks post-trauma, with symptoms of glare which were managed by the use of a colored contact lens.Conclusion: The possibility of wound dehiscence should be recognized as an important clinical entity in the immediate postoperative period, but also several years following cataract surgery.Keywords: anirida, pseudophakia, cataract extraction, cataract, phacoemulsification, traum
A Soft Sensor for Biomass in a Batch Process with Delayed Measurements
This paper presents a soft sensor to estimate the biomass concentration in a batch bioprocess used in production of δ-endotoxins of Bacillus thuringiensis, subject to delayed
measurements. The soft sensor proposed is based on a cascade observer-predictor algorithm. The observer stage is based on a class of second order sliding mode algorithms, allowing a fixed time estimation of the biomass. Additionally, the prediction stage offsets the effect of the delay in measurements. Simulations show the feasibility of the proposed observer.Universidad Nacional de ColombiaCINVESTAV-IPNITESO, A.C
An Equivalent Control Based Observer for Biomass in a Batch Process
In this paper a sliding-mode observer for a batch bioprocess, the d-endotoxins production of bacillus thuringiensis (BT), is presented. The proposed observer is based on the equivalent control method and a class of second-order sliding mode operators. The use of these operators in the observer design allows the fixed-time convergence of the measured variables, while the unmeasured variables converge exponentially. This structure allows to estimate the biomass in the d-endotoxins production of BT, even, under noisy measurement conditions. Simulations show the feasibility of the proposed observer.
Convergence proofs are also presented
Netlang: A software for the linguistic analysis of corpora by means of complex networks
To date there is no software that directly connects the linguistic analysis of a conversation to a network program. Networks programs are able to extract statistical information from data basis with information about systems of interacting elements. Language has also been conceived and studied as a complex system. However, most proposals do not analyze language according to linguistic theory, but use instead computational systems that should save time at the price of leaving aside many crucial aspects for linguistic theory. Some approaches to network studies on language do apply precise linguistic analyses, made by a linguist. The problem until now has been the lack of interface between the analysis of a sentence and its integration into the network that could be managed by a linguist and that could save the analysis of any language. Previous works have used old software that was not created for these purposes and that often produced problems with some idiosyncrasies of the target language. The desired interface should be able to deal with the syntactic peculiarities of a particular language, the options of linguistic theory preferred by the user and the preservation of morpho-syntactic information (lexical categories and syntactic relations between items). Netlang is the first program able to do that. Recently, a new kind of linguistic analysis has been developed, which is able to extract a complexity pattern from the speaker’s linguistic production which is depicted as a network where words are inside nodes, and these nodes connect each other by means of edges or links (the information inside the edge can be syntactic, semantic, etc.). The Netlang software has become the bridge between rough linguistic data and the network program. Netlang has integrated and improved the functions of programs used in the past, namely the DGA annotator and two scripts (ToXML.pl and Xml2Pairs.py) used for transforming and pruning data. Netlang allows the researcher to make accurate linguistic analysis by means of syntactic dependency relations between words, while tracking record of the nature of such syntactic relationships (subject, object, etc). The Netlang software is presented as a new tool that solve many problems detected in the past. The most important improvement is that Netlang integrates three past applications into one program, and is able to produce a series of file formats that can be read by a network program. Through the Netlang software, the linguistic network analysis based on syntactic analyses, characterized for its low cost and the completely non-invasive procedure aims to evolve into a sufficiently fine grained tool for clinical diagnosis in potential cases of language disorders
Coping with climatic extremes: Dietary fat content decreased the thermal resilience of barramundi (Lates calcarifer)
Aquatic organisms, including important cultured species, are forced to contend with acute changes in water temperature as the frequency and intensity of extreme weather events worsen. Acute temperature spikes are likely to threaten aquaculture species, but dietary intervention may play an important protective role. Increasing the concentration of macronutrients, for example dietary fat content, may improve the thermal resilience of aquaculture species, however, this remains unexplored. To evaluate this hypothesis, we used two commercially available diets (20% versus 10% crude fat) to examine if dietary fat content improves the growth performance of juvenile barramundi (Lates calcarifer) while increasing their resilience to acute thermal stress. Fish were fed their assigned diets for 28-days before assessing the upper thermal tolerance (CTMAX) and the thermal sensitivity of swimming performance (UCRIT) and metabolism. We found that feeding fish a high fat diet resulted in heavier fish, but did not affect the thermal sensitivity of swimming performance or metabolism over an 18 °C temperature range (from 20 to 38 °C). Thermal tolerance was compromised in fish fed the high fat diet by 0.48 °C, showing significantly lower CTMAX. Together, these results suggest that while a high fat diet increases juvenile L. calcarifer growth, it does not benefit physiological performance across a range of relevant water temperatures and may even reduce fish tolerance of extreme water temperatures. These data may have implications for aquaculture production in a warming world, where episodic extremes of temperature are likely to become more frequent
Voids by mechanical entrapment in liquid molding processes: mechanism of formation, influence in the mechanical response and reduction
Los vacíos por atrapamiento mecánico se constituyen en unos de los tipos de defectos más comunes en el procesado de Composites por moldeo líquido. Debido a la gran influencia que tienen estos vacíos en el desempeño de la pieza final, una cantidad considerable de investigaciones se han centrado en el estudio de los mecanismos de formación de los mismos, de la influencia que éstos tienen en las propiedades mecánicas del compuesto y de las estrategias para su reducción durante el procesado. El presente trabajo pretende realizar una revisión de algunas investigaciones relevantes que se han hecho en el tema de vacíos formados por atrapamiento mecánico de aire en el procesado de compuestos por LCM (Moldeo Líquido de Composites, por sus siglas en inglés), con el objetivo de generar un material de referencia dirigido a investigadores interesados en esta importante temática relacionada con las áreas del procesado y comportamiento mecánico de materiales compuestos. Serán abordados temas como: el mecanismo de formación por desbalance entre macroflujo y microflujo, y su relación con el número capilar modificado y el efecto de sumidero; los fenómenos de compresibilidad, disolución y movimiento de burbujas en preformas de doble escala; la influencia de los vacíos en las propiedades mecánicas del composite y en los mecanismos de daño; y las estrategias más comunes que pueden ser implementadas a nivel industrial para la reducción de este tipo de defectología.The voids by mechanical entrapment become as one of the most common type of defects in the liquid molding processing of composites. Because of the strong influence of those kind of voids in the general performance of the manufactured part, an important amount of researches have focused on the study of the mechanisms of formation of those voids, of the influence of the those ones on the mechanical properties of the composite and of the strategies for their reduction during the process. The present paper aims to do a review of some relevant investigations that have been done in the topic of voids caused by mechanical entrapment of air in the processing of composites by LCM (Liquid composites molding) with the purpose of generate a reference material addressed to researchers that are interested in this important subject matter related to the areas of processing and mechanical behavior of composites materials. They will be addressed some topics like: the mechanism of void formation by imbalance among macroflow and microflow and its relationship with the modified capillary number and the sink effect; the phenomena of compressibility, dissolution and mobilization of bubbles in dual-scale preforms; the influence of voids on the mechanical properties of the composites and on the damage mechanisms; and the most common strategies that can be implemented in the industry for the reduction of this sort of defects
Búsqueda personalizada en Repositorios de Objetos de Aprendizaje a partir del perfil del estudiante
The personalized searches of Learning Objects(OA) in distributed repositories from the studentprofile require compare the variables the studentmodel and stored OA metadata. This article presentsan approach to a mechanism of personalized searchand proposes the student profile and the relationwith the metadata in some repositories of OA (ROA)better known. This research focuses more on themeta-information that OA content. This work is thefirst step to propose a recommendation model ofOA in the framework of a federation of ROA.Las búsquedas personalizadas de Objetos deAprendizaje (OA) en repositorios distribuidos apartir de caracterizar el perfil de estudiante, requiereequiparar las variables del modelo de estudiantey los metadatos de los OA almacenados. En elpresente artículo, se plantea un acercamiento a unmecanismo de búsqueda personalizada y se proponela caracterización del estudiante y la relación con losmetadatos que utilizan algunos de los Repositoriosde OA (ROA) más conocidos. Esta investigación secentra más en la metainformación de los OA, queen su contenido. Este trabajo es el primer paso paraplantear un modelo de recomendación de OA en elmarco de una Federación de ROA
TÉCNICAS INTELIGENTES, AGENTES ADAPTATIVOS Y REPRESENTACIONES ONTOLÓGICAS EN SISTEMAS DE DETECCIÓN DE INTRUSOS
RESUMEN La seguridad Informática requiere una optimización permanente de los mecanismos de protección y estrategias que permitan prevenir ataques en las redes y sistemas de información. El proceso de monitoreo de eventos que ocurren en un sistema o en una red a partir de patrones y firmas de posibles ataques se conoce como Sistema de Detección de Intrusos (IDS). Los IDS han escalado significativamente al punto de focalizarse en modelos basados en prevención más que en corrección, estos sistemas monitorean tráfico utilizando un conjunto de firmas para detectar actividades malignas, reportar incidentes o tomar acciones correctivas; pero cualquier cambio insertado en el patrón de un ataque, puede comprometer el sistema y evitar que la tecnología subyacente de detección o prevención sea insuficiente. En los últimos años se han planteado diferentes modelos basados en técnicas de Inteligencia Artificial que pueden ayudar a la generación automática de nuevas firmas y detectar nuevos patrones de ataque sin la intervención humana. Algunas investigaciones presentan técnicas como Redes Neuronales, Algoritmos Genéticos, Razonamiento Basado en Casos, árboles de decisión, Lógica Difusa entre otras, aplicadas a la Detección de Intrusos, además de arquitecturas basadas en Agentes Inteligentes sobre IDS Distribuidos incorporando así capacidades de autonomía, reactividad, pro actividad, movilidad y racionalidad. Este artículo es el resultado de un estudio del estado del arte de las diferentes estrategias inteligentes en IDS. Además la introducción de modelos de cooperación a partir de Agentes adaptativos y de representaciones ontológicas en los Sistemas de Detección de Intrusos Distribuidos, adicionalmente se plantean los elementos de una investigación en curso donde se incorporan estos métodos.PALABRAS CLAVE: Sistemas de Detección de Intrusos, Detección de Intrusos Inteligente, Agentes Inteligentes, Seguridad en Redes, Representaciones Ontológicas y Semánticas Conglomerados. ABSTRACT Security Computing requires a permanent optimization in protection mechanisms and strategies that allow preventing attacks in the networks and information systems. The event monitoring process that happens in a system or a network using patterns or signs is known like Intrusion Detection System (IDS). The IDS have been focused more in prevention models than correction models; these systems tests traffic using a set of signs to detect malicious activities, report incidents o take correction actions; but, any change inserted in the attack pattern can compromise the system and avoid the underlying technology and make insufficient the Intrusion Detection. Over the years different models based in Artificial Intelligence techniques have been considered to help the automatic signs and patterns generation without human intervention. Some researching projects present Neuronal Networks, Genetic Algorithms, Case Based Reasoning, decision trees, Fuzzy logic applied to the Intrusion Detection; additionally using Intelligent and Mobile Agents architectures over Distributed IDS incorporating autonomy, reactivity, pro activity, mobility and rationality capabilities. This paper is result of studying state of art of multiples intelligent strategies in IDS and cooperation models using Agents and ontology representation in Intrusion Detection. This paper complements elements in a course research considering integrating these methods.KEYWORDS: Intrusion Detection Systems, Intelligent Intrusion Detection, Intelligent Agents, Network Security, Ontology and Semantic representations
TÉCNICAS INTELIGENTES, AGENTES ADAPTATIVOS Y REPRESENTACIONES ONTOLÓGICAS EN SISTEMAS DE DETECCIÓN DE INTRUSOS
RESUMEN La seguridad Informática requiere una optimización permanente de los mecanismos de protección y estrategias que permitan prevenir ataques en las redes y sistemas de información. El proceso de monitoreo de eventos que ocurren en un sistema o en una red a partir de patrones y firmas de posibles ataques se conoce como Sistema de Detección de Intrusos (IDS). Los IDS han escalado significativamente al punto de focalizarse en modelos basados en prevención más que en corrección, estos sistemas monitorean tráfico utilizando un conjunto de firmas para detectar actividades malignas, reportar incidentes o tomar acciones correctivas; pero cualquier cambio insertado en el patrón de un ataque, puede comprometer el sistema y evitar que la tecnología subyacente de detección o prevención sea insuficiente. En los últimos años se han planteado diferentes modelos basados en técnicas de Inteligencia Artificial que pueden ayudar a la generación automática de nuevas firmas y detectar nuevos patrones de ataque sin la intervención humana. Algunas investigaciones presentan técnicas como Redes Neuronales, Algoritmos Genéticos, Razonamiento Basado en Casos, árboles de decisión, Lógica Difusa entre otras, aplicadas a la Detección de Intrusos, además de arquitecturas basadas en Agentes Inteligentes sobre IDS Distribuidos incorporando así capacidades de autonomía, reactividad, pro actividad, movilidad y racionalidad. Este artículo es el resultado de un estudio del estado del arte de las diferentes estrategias inteligentes en IDS. Además la introducción de modelos de cooperación a partir de Agentes adaptativos y de representaciones ontológicas en los Sistemas de Detección de Intrusos Distribuidos, adicionalmente se plantean los elementos de una investigación en curso donde se incorporan estos métodos.PALABRAS CLAVE: Sistemas de Detección de Intrusos, Detección de Intrusos Inteligente, Agentes Inteligentes, Seguridad en Redes, Representaciones Ontológicas y Semánticas Conglomerados. ABSTRACT Security Computing requires a permanent optimization in protection mechanisms and strategies that allow preventing attacks in the networks and information systems. The event monitoring process that happens in a system or a network using patterns or signs is known like Intrusion Detection System (IDS). The IDS have been focused more in prevention models than correction models; these systems tests traffic using a set of signs to detect malicious activities, report incidents o take correction actions; but, any change inserted in the attack pattern can compromise the system and avoid the underlying technology and make insufficient the Intrusion Detection. Over the years different models based in Artificial Intelligence techniques have been considered to help the automatic signs and patterns generation without human intervention. Some researching projects present Neuronal Networks, Genetic Algorithms, Case Based Reasoning, decision trees, Fuzzy logic applied to the Intrusion Detection; additionally using Intelligent and Mobile Agents architectures over Distributed IDS incorporating autonomy, reactivity, pro activity, mobility and rationality capabilities. This paper is result of studying state of art of multiples intelligent strategies in IDS and cooperation models using Agents and ontology representation in Intrusion Detection. This paper complements elements in a course research considering integrating these methods.KEYWORDS: Intrusion Detection Systems, Intelligent Intrusion Detection, Intelligent Agents, Network Security, Ontology and Semantic representations
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