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Search Results: 1 - 10 of 1628 matches for " Blair Henderson "
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Comparison of CT Dose Reduction Algorithms in a Porcine Model  [PDF]
Mohammed Nazir Khan, Idris Elbakri, Blair Henderson, Jeffrey Mottola, Azeez Omotayo
Advances in Computed Tomography (ACT) , 2015, DOI: 10.4236/act.2015.44008
Abstract: The present study utilized a porcine model for qualitative and quantitative assessment of the diagnostic quality of non-contrast abdominal computed tomography (CT) images generated by Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare, Waukesha, Wisconsin, USA), Model-Based Iterative Reconstruction (GE company name VEO), and conventional Filtered back projection (FBP) technique. Methods: Multiple CT whole-body scans of a freshly euthanized pig carcass were performed on a 64-slice GE CT scanner at varying noise indices (5, 10, 15, 20, 30, 37, 40, 45), and with three different algorithms (VEO, FBP, and ASIR at 30%, 50%, and 70% levels of ASIR-FBP blending). Abdominal CT images were reviewed and scored in a blinded and randomized manner by two board-certified abdominal radiologists. The task was to evaluate the clarity of the images according to a rubric involving edge sharpness, presence of artifact, anatomical clarity (assessed at four regions), and perceived diagnostic acceptability. This amounted to seven criteria, each of which was graded on a scale of 1 to 5. A weighted formula was used to calculate a composite score for each scan. Results: VEO outperforms ASIR and FBP by an average of 0.5 points per the scoring system used (p < 0.05). Above a threshold noise index of 30, diagnostic acceptability is lost by all algorithms, and there is no diagnostic advantage to increasing the dose beyond a noise index of 10. Between a noise index of 25 - 30, VEO retains diagnostic acceptability, as opposed to ASIR and FBP which lose acceptability above noise index of 25. Conclusion: Model-based iterative reconstruction provides superior image quality and anatomical clarity at reduced radiation dosages, supporting the routine use of this technology, particularly in pediatric abdominal CT scans.
The Local Migration of Plant-Based Medicines from Rural Communities to Gral. E. Aquino, Paraguay  [PDF]
Noah Goyke, Blair Orr
Natural Resources (NR) , 2018, DOI: 10.4236/nr.2018.912027
Abstract: Rural Paraguay presents interesting opportunities for investigating the subtle differences in the use of medicinal plants across seasons and the urban versus rural dichotomy in a local setting. This study investigates three aspects of plant-based medicinal use in rural Paraguay: 1) seasonal differences and 2) differences between urban and rural residents and 3) the source of medicinal plants used to treat thirteen common ailments. Interviews performed in January through March 2015 and repeated in June through August 2015 revealed small differences between seasons and between places of residence but a larger homogeneity in the two populations, a homogeneity that stems from the recent migration of urban residents from nearby rural communities. We also found that the important cultural and preventive medicinal use of plant-based additions to yerba mate contributes to the similarities between the urban and rural populations. The findings suggest the continued strength of medicinal plant use going into the near future.
Can Banks Circumvent Minimum Capital Requirements? The Case of Mortgage Portfolio under Basel II  [PDF]
Christopher Henderson, Julapa Jagtiani
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.33A006

The recent mortgage crisis has resulted in several bank failures. Under the current Basel I capital framework, banks are not required to hold a sufficient amount of capital to support the risk associated with their mortgage activities. The new Basel II capital rules are intended to be more risk based and would require the right amount of capital buffer to support bank risk. However, Basel II models could become too complex and too costly to implement, often resulting in a trade-off between complexity and model accuracy. Since the Basel II rules are meant to be principal based (rather than prescriptive), banks have the flexibility to build risk models that best fit their unique structure. We find that the variation of the model, particularly how mortgage portfolios are segmented, could have a significant impact on the default and loss estimated. This paper finds that the calculated Basel II capital varies considerably across the default prediction model and segmentation schemes, thus providing banks with an incentive to choose an approach that results in the least required capital for them. We find that a more granular segmentation model produces smaller required capital, regardless of the economic environment. Our results suggest that banks may have incentives to build risk models that meet the Basel II requirement and still yield the least amount of required capital.

Soil moisture, field-scale toposequential position, and slope effects on yields in irrigated rice (Oryza sativa L.) fields in Honduras  [PDF]
Kyle M. Earnshaw, Blair Orr
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.48A001

Rice (Oryza sativa L.) is an important cash crop in Honduras. The availability of inexpensive irrigation in the study area (Flores, La Villa de San Antonio, Comayagua) encourages rice farmers to neglect prescribed methods of soil and water conservation, such land leveling, puddling, and soil bunds. This study looked at the effect of failure to mitigate water loss on sloping fields. Soil moisture (Volumetric Water Content) was measured using a soil moisture probe after the termination of the first irrigation within the tillering/vegetative, panicle emergence/flowering, post-flowering/pre-maturation and maturation stages. Yield data were obtained by harvesting on 1 m2 plots in each soil moisture testing site. Data analyses looked at the relationship between yield and slope, soil moisture, farmers, and toposequential position along transects. Toposequential position influenced yields more than slope and soil moisture was not a significant predictor of yields. Irrigation politics, high water inputs, and land tenure were proposed as the major reasons for this result.

Quantification of drought tolerance in Ethiopian common bean varieties  [PDF]
Asrat Asfaw, Matthew W. Blair
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.52016

Understanding the level of drought tolerance of the varieties available in each country is of paramount importance for breeding common bean for drought adaptation. The goal of this study was to evaluate 25 common bean genotypes of which 24 were released/recommended varieties for production by farmers and one was a drought tolerant check. The genotypes were planted at two sites in Ethiopia, Hawasssa and Amaro, using variable sowing dates, one that was early to avoid drought and one that was late to expose the crop to drought. The experiments were repeated over two years in Hawassa and one year in Amaro. This resulted in treatments with high and low total seasonal rainfall and six environments for analysis. The impact of drought stress on the trait expression of the varieties was not uniform across traits assessed and varieties tested. The effect of drought on photosynthate translocation and partitioning traits was much greater than on yield component traits in the varieties studied. This indicating less breeding efforts has been made in improving the varieties ability to mobilize photosynthate to the developing grain as compared to the yield component traits. Drought tolerant varieties like Hawassa Dume maintained better photosynthate translocation and partitioning than the drought sensitive varieties like Brown Speckled bean. Hawassa Dume also showed better yield stability and performed well under both drought stress and nonstress conditions. Our results indicate the relevance of high levels of photosynthate translocation and partitioning as an effective selection objective for improving drought tolerance in common bean. The information generated on the drought tolerance of the available varieties should help in the design of a breeding strategy that incorporates adaptation traits with commercial characteristics preferred by common bean farmers for varieties to be grown in diverse environments.

Forest Management Plans in Los Planes de La Palma, El Salvador  [PDF]
Gisselle A. Mejia, Blair Orr
Natural Resources (NR) , 2015, DOI: 10.4236/nr.2015.611050
Abstract: Fourteen farmers with small woodlots were interviewed about the forest management plans promoted by the government of El Salvador. As expected, farmers managed for many utilitarian products such as firewood and timber, but the farmers also expressed a strong set of environmental concerns revolved around the ecological value of their woodlots. Farmers generally approved of forest management plans as they saw how plans contributed to sustainable forestry on their woodlots. Farmers had concerns about specific silvicultural practices and about transportation of harvested timber.
Nutrient Use Efficiency of Three Fast Growing Hardwood Species across a Resource Gradient  [PDF]
Dawn E. Henderson, Shibu Jose
Open Journal of Forestry (OJF) , 2012, DOI: 10.4236/ojf.2012.24023
Abstract: Attitudes regarding traditional energy sources have shifted toward renewable resources. Specifically, short-rotation woody crop supply systems have become more prevalent for biomass and biofuel production. However, a number of factors such as environmental and inherent resource availability can limit tree production. Given the intensified demand for wood biomass production, forest and plantation management practices are focusing on increasing productivity. Fertilizer application, while generally one of the least expensive silvicultural tools, can become costly if application rates exceed nutrient uptake or demand of the trees especially if it does not result in additional biomass production. We investigated the effect of water and varying levels of nitrogen application (56, 112, and 224 kg·N·ha-1·yr-1) on nutrient content, resorption efficiency and proficiency, N:P and the relationship with ANPP, as well as leaf- and canopy-level nutrient use efficiency of nitrogen, phosphorus, and potassium for Populus deltoides, Quercus pagoda, and Platanus occidentalis. P. deltoides and P. occidentalis reached their maximum nitrogen budget with the application of water suggesting old agricultural fields may have sufficient nutrient levels to sustain short-rotation woody crops negating the application of additional nitrogen for these two species. Additionally, for P. deltoides and Q. pagoda application of nitrogen appeared to increase the uptake of phosphorus however, resorption efficiency for these two species were more similar to studies conducted on nutrient poor sites. Nutrient resorption proficiency for all three nutrients and all three species were at levels below the highest rates of nitrogen application. These findings suggest maximum biomass production may not necessarily be tied to maximum nutrient application.
La política punitiva del cuerpo: "economía del castigo" o mecánica del sufrimiento en Colombia
Estudios Políticos , 2010,
Abstract: el artículo propone explorar la relación cuerpo/violencia desde la perspectiva de la biopolítica, y mostrar la importancia que ella reviste en trminos del poder, esto es, su dimensión política o el carácter político de la corporalidad. en el marco de las explicaciones que, tradicionalmente, nos han sido dadas sobre las guerras en el ámbito macropolítico del poder, es difícil establecer una relación entre el cuerpo y la guerra; en efecto, ellas aducen razones como las relaciones que se establecen entre los actores armados y el estado, por ejemplo, o las de control y dominio de los territorios o las de las disputas por el control de recursos y poblaciones, entre otras, pero en ellas los cuerpos parecerían inexistentes o, en todo caso, supeditados a "lógicas" y presencias bélicas de otra naturaleza. pero también -y es lo que se pretende mostrar- existen otros ámbitos micropolíticos o unas tecnologías corporales específicas que, adicionalmente, resultan muy fecundas para explicar el "cómo" del poder. la violencia sobre los cuerpos, en el ámbito de la guerra es, pues, un dispositivo de poder que se ejerce a través de una serie de tecnologías corporales utilizadas con la finalidad de dominar, a través del terror, a individuos y poblaciones. desde esta perspectiva, esa violencia sobre los cuerpos en el caso de la guerra en colombia -similar a lo que ocurre en otras guerras contemporáneas-, sería la expresión de una "economía del castigo" o más concretamente de lo que foucault llamó una política punitiva del cuerpo, máxima expresión de esa micropolítica corporal y una forma extrema de ejercicio del poder.
Retos para la eliminación de la malaria en Colombia: un problema de saber o de poder
Biomédica , 2012,
Abstract: introduction. practices to end malaria in the world have evolved from the sanitary control programs, known in colombia as the fight for hygiene, in the early twentieth century, to the eradication efforst in the 5′s and back to control in 1978. today, after 43 years of failure of the malaria eradication program, the world health organization proposes its members a program to eliminate malaria malaria with eradication in view. will this be possible in colombia? objective. to review the possibilities of eliminating malaria in colombia, from a historical analysis of the knowledge and practices developed to reach this aim. results. we present the obstacles and opportunities for the development of a malaria elimination program in colombia, where the etiopathogenic model of infectious diseases, based on the germ theory, still remains valid and supports practices such as eradication. conclusion. eliminating malaria is not just a scientific problem of the gaps in knowledge, but a way of supporting that knowledge with a single theory, the microbial or the etiopathogenic theory, to explain diseases such as malaria; it is also a problem of power. even though the political power can be a form of knowledge, understanding it as a mixture of strategies and interests of the institutions that dictate the public policies, the international agencies, the companies selling sellers of insecticides and antimalarials and the producers of new reagents and diagnostic tools.
Global warming and avian occupancy of hot deserts: a physiological and behavioral perspective
Revista chilena de historia natural , 2000, DOI: 10.4067/S0716-078X2000000300003
Abstract: avian adjustments to desert environments are characterized by an integration of behavior and physiology. these responses serve to maintain homeostasis and conserve vital resources such as water. the small size of birds confers a close coupling to the thermal environment and demands rapid adjustments to environmental challenges. physiological responses to heat stress include hyperthermia, and increased evaporative cooling as environmental temperatures approach body temperature. behaviorally, desert birds respond to heat stress by drastically reducing activity during the hottest parts of the day and selecting cool shaded microsites. this characteristic behavioral response presents a potential problem in the face of global warming. if birds totally forgo foraging during extremely hot periods, increased evaporative water loss rates due to higher environmental temperatures could lead to significant episodes of direct mortality for birds in these regions. a simple model is presented which integrates behavior and physiology to predict survival times based on dehydration tolerance, microsite selection and environmental temperature.
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