Comparing Latent Dirichlet Allocation and Latent Semantic Analysis as Classifiers

In the Information Age, a proliferation of unstructured text electronic documents exists. Processing these documents by humans is a daunting task as humans have limited cognitive abilities for processing large volumes of documents that can often be extremely lengthy. To address this problem, text data computer algorithms are being developed. Latent Semantic Analysis (LSA) and Latent Dirichlet Allocation (LDA) are two text data computer algorithms that have received much attention individually in the text data literature for topic extraction studies but not for document classification nor for comparison studies. Since classification is considered an important human function and has been studied in the areas of cognitive science and information science, in this dissertation a research study was performed to compare LDA, LSA and humans as document classifiers. The research questions posed in this study are: R1: How accurate is LDA and LSA in classifying documents in a corpus of textual data over a known set of topics? R2: How accurate are humans in performing the same classification task? R3: How does LDA classification performance compare to LSA classification performance? To address these questions, a classification study involving human subjects was designed where humans were asked to generate and classify documents (customer comments) at two levels of abstraction for a quality assurance setting. Then two computer algorithms, LSA and LDA, were used to perform classification on these documents. The results indicate that humans outperformed all computer algorithms and had an accuracy rate of 94% at the higher level of abstraction and 76% at the lower level of abstraction. At the high level of abstraction, the accuracy rates were 84% for both LSA and LDA and at the lower level, the accuracy rate were 67% for LSA and 64% for LDA. The findings of this research have many strong implications for the improvement of information systems that process unstructured text. Document classifiers have many potential applications in many fields (e.g., fraud detection, information retrieval, national security, and customer management). Development and refinement of algorithms that classify text is a fruitful area of ongoing research and this dissertation contributes to this area

Diet, microhabitat use, and thermal preferences of Ptychoglossus bicolor (Squamata: Gymnophthalmidae) in an organic coffee shade plantation in Colombia

Ptychoglossus bicolor is a small gymnophthalmid lizard distributed in the Magdalena Valley of Colombia. We studied ecological features of diet, microhabitat use, and thermal preferences of a population found in an organic coffee shade plantation at the Cordillera Oriental of the Colombian Andes. The studied population had a diet composed predominantly of isopods. The Relative Importance Index of isopods was 98.8%; there were no significant monthly differences in the full stomach content and volume of isopods eaten during the sampling year, neither between rainy and dry seasons. A large number of lizards were found active in the leaf-litter, buried around coffee tree roots, and under or in rotting logs. Lizard body temperature was positively correlated with substrate temperature and air temperature; sex differences in body temperature were not significant. At the studied locality we did not find lizards out of the coffee fields. Our results suggested that these lizards successfully cope with the conditions offered by the organic coffee areas as a result of the cultivation system. Thus, this population might be vulnerable to any modification of the habitat that changes microhabitat availability and abundance of isopods.Ptychoglossus bicolor es un pequeño lagarto de la familia Gymnophthalmidae, que habita el valle del Río Magdalena de Colombia. Se estudiaron las características ecológicas de la dieta, uso de microhábitat y preferencias termales de una población que habita una plantación de café orgánico bajo sombra en la Cordillera Oriental colombiana. La dieta en esta población está dominada por isópodos. El Índice Valor de Importancia Relativa fue del 98.8% y no hubo diferencias mensuales significativas en el contenido estomacal y el volumen de isópodos consumidos durante el año, ni tampoco entre las estaciones de lluvia y seca. Un gran número de lagartos fueron encontrados activos entre la hojarasca, enterrados junto a las raíces de los árboles y bajo o dentro de troncos en descomposición. La temperatura corporal estuvo positivamente correlacionada con las temperaturas del suelo y del aire y no hubo diferencias significativas en temperatura corporal entre los sexos. En esta localidad no encontramos lagartos fuera de los campos de cultivo de café. Nuestros resultados sugieren que estos lagartos sobrellevan exitosamente las condiciones ofrecidas por los cafetales orgánicos como resultado del sistema de cultivo. Así, esta población podría ser vulnerable a cualquier modificación del hábitat que cambie la disponibilidad de microhábitats y la abundancia de isópodos

Cardiovascular drug therapy for human newborn: review of pharmacodynamic data

BACKGROUND: Circulatory failure in preterm and term newborn infants is commonly treated with inotropes or vasoactive medications. In this structured literature review, the available data on pharmacodynamic effects of the inotropes adrenaline, dobutamine, dopamine, levosimendan, milrinone, noradrenaline, and the vasoactive drugs vasopressin and hydrocortisone are presented. METHODS: Structured searches were conducted to identify relevant articles according to pre-defined inclusion criteria which were human clinical trials published after 2000. RESULTS: Out of 101 identified eligible studies only 22 studies met the criteria for evidence based practice guidelines level I to IV. The most prevalent pharmacodynamic effects were increase in blood pressure and/or heart rate, which were also the most frequently studied circulatory parameters. CONCLUSION: This review demonstrates the need for further systematic studies on all reviewed drugs with incorporation of novel non-invasive biomarkers in this vulnerable patient group, for more timely and appropriate treatment for clinical efficacy

Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

The thermal transport in polycrystalline diamond films near its nucleation region is still not well understood. Here, a steady-state technique to determine the thermal transport within the nano-crystalline diamond present at their nucleation site has been demonstrated. Taking advantage of silicon nanowires as surface temperature nano-sensors, and using Raman Thermography, the in-plane and cross-plane components of the thermal conductivity of ultra-thin diamond layers and their thermal barrier to the Si substrate were determined. Both components of the thermal conductivity of the nano-crystalline diamond were found to be well below the values of polycrystalline bulk diamond, with a cross-plane thermal conductivity larger than the in-plane thermal conductivity. Also a depth dependence of the lateral thermal conductivity through the diamond layer was determined. The results impact the design and integration of diamond for thermal management of AlGaN/GaN high power transistors and also show the usefulness of the nanowires as accurate nano-thermometers. (C) 2015 AIP Publishing LLC

Sequential heuristic optimisation of a real offshore wind farm site considering turbine placement and cable layout

Competition within the energy generation industry provides an incentive for developers to build offshore wind farms with a low levelised cost of energy. Therefore, there is a need for design optimisation to reduce costs and increase energy capture. A sequential approach to optimise turbine placement and cable layout is presented, using a heuristic k-opt algorithm and mixed-integer linear programming respectively. Energy storage is considered as a means to further improve the cable selection process. A case study is carried out on the Lillgrund offshore wind farm and the resulting layout improves energy capture by 6%. Cable costs are increased but the electrical losses are reduced such that there is an overall saving over the project lifetime of 20%. Energy storage as a means to peak shave the power seen by a cable in order to reduce electrical losses or de-rate a cable section was found to be impractically large and not profitable. Future work will consider secondary revenue streams to remedy this

Assessment of multi-use offshore platforms: structure classification and design challenges

As the world continues to experience problems including a lack of seafood and high energy demands, this paper provides an assessment for integrated multi-use offshore platforms (MUPs) as a step towards exploiting open seawater in a sustainable way to harvest food and energy. The paper begins with background about MUPs, including information regarding what an MUP is and why it is used. The potential energy technologies that can be involved in an offshore platform are introduced while addressing similar applications all over the world. The paper presents the state of the art of MUP structures on the light of EU-funded programs. An MUP would have a positive impact on various marine activities such as tourism, aquaculture, transport, oil and gas and leisure. However, there are concerns about the negative impact of MUPs on the marine environment and ecosystem. Building an MUP with 100% renewable energy resources is still a challenge because a large storage capacity must be considered with a well-designed control system. However, marine bio-mass would play a vital role in reducing battery size and improving power supply reliability. Direct Current (DC) systems have never been considered for offshore platforms, but they could be a better alternative as a simpler control system that requires with lower costs, has lower distribution losses, and has an increased system efficiency, so studying the feasibility of using DC systems for MUPs is required