Design of a highly-birefringent microstructured photonic crystal fiber for pressure monitoring

We present the design of an air hole microstructured photonic crystal fiber for pressure sensing applications. The air-hole photonic crystal lattices were designed to produce a large intrinsic birefringence of 1.16x10-3. The impact of the surrounding air holes for pressure sensing to the propagation mode profiles and indices were studied and improved, which ensures single mode propagation in the fiber core defined by the photonic crystal lattice. An air hole matrix and a practical chemical etching process during the fiber perform preparation stage is proposed to produce an optical fiber with a birefringence-pressure coefficient of 43.89×10-6MPa-1 or a fiber Bragg grating pressure responsivity of 44.15 pm/MPa, which is a 17 times improvement over previous photonic crystal fiber designs. © 2010 Optical Society of America

A fuzzy approach for feature extraction of brain tissues in Non-Contrast CT

In neuroimaging, brain tissue segmentation is a fundamental part of the techniques that seek to automate the detection of pathologies, the quantification of tissues or the evaluation of the progress of a treatment. Because of its wide availability, lower cost than other imaging techniques, fast execution and proven efficacy, Non-contrast Cerebral Computerized Tomography (NCCT) is the most used technique in emergency room for neuroradiology examination, however, most research on brain segmentation focuses on MRI due to the inherent difficulty of brain tissue segmentation in NCCT. In this work, three brain tissues were characterized: white matter, gray matter and cerebrospinal fluid in NCCT images. Feature extraction of these structures was made based on the radiological attenuation index denoted by the Hounsfield Units using fuzzy logic techniques. We evaluated the classification of each tissue in NCCT images and quantified the feature extraction technique in images from real tissues with a sensitivity of 92% and a specificity of 96% for images from cases with slice thickness of 1 mm, and 96% and 98% respectively for those of 1.5 mm, demonstrating the ability of the method as feature extractor of brain tissues.Postprint (published version

Water and poverty in two Colombian watersheds

Watersheds, especially in the developing world, are increasingly being managed for both environmental conservation and poverty alleviation. How complementary are these objectives? In the context of a watershed, the actual and potential linkages between land and water management and poverty are complex and likely to be very site specific and scale dependent. This study analyses the importance of watershed resources in the livelihoods of the poor in two watersheds in the Colombian Andes. Results of the participatory poverty assessment reveal significant decreases in poverty in both watersheds over the past 25 years, which was largely achieved by the diversification of livelihoods outside of agriculture. Water is an important resource for household welfare. However, opportunities for reducing poverty by increasing the quantity or quality of water available to the poor may be limited. While improved watershed management may have limited direct benefits in terms of poverty alleviation, there are important indirect linkages between watershed management and poverty, mainly through labour and service markets. The results suggest that at the level of the watershed the interests of the rich and the poor are not always in conflict over water. Sectoral as well as socio-economic differences define stakeholder groups in watershed management. The findings have implications for policymakers, planners and practitioners in various sectors involved in the implementation of integrated water resources management (IWRM)

El turismo en Medellín desde la percepción del consumidor como una creciente oportunidad de negocio

La determinación de las características de los pacientes extranjeros permite definir algunos segmentos específicos y sus razones de compra, enocntrándose esto ligado a la percepción de calidad, talento humano, infraestructura, posicionamiento a nivel internacional y reconocimiento de los servicios de salud, que en la actualidad se prestan en Colombia y específicamente en Medellín.The determination of the characteristics of foreign patients to deifne some specific segments and their reasons for purchase, found it linked to the perception of quality, human resource, infrastructure, internacional positioning and recognition of health services, which are currently specifically provided in Colombia and Medellin

Higher Fecal Short-Chain Fatty Acid Levels Are Associated with Gut Microbiome Dysbiosis, Obesity, Hypertension and Cardiometabolic Disease Risk Factors

Fiber fermentation by gut microbiota yields short-chain fatty acids (SCFAs) that are either absorbed by the gut or excreted in feces. Studies are conflicting as to whether SCFAs are beneficial or detrimental to cardiometabolic health, and how gut microbiota associated with SCFAs is unclear. In this study of 441 community-dwelling adults, we examined associations of fecal SCFAs, gut microbiota diversity and composition, gut permeability, and cardiometabolic outcomes, including obesity and hypertension. We assessed fecal microbiota by 16S rRNA gene sequencing, and SCFA concentrations by gas chromatography/mass spectrometry. Fecal SCFA concentrations were inversely associated with microbiota diversity, and 70 unique microbial taxa were differentially associated with at least one SCFA (acetate, butyrate or propionate). Higher SCFA concentrations were associated with a measure of gut permeability, markers of metabolic dysregulation, obesity and hypertension. Microbial diversity showed association with these outcomes in the opposite direction. Associations were significant after adjusting for measured confounders. In conclusion, higher SCFA excretion was associated with evidence of gut dysbiosis, gut permeability, excess adiposity, and cardiometabolic risk factors. Studies assessing both fecal and circulating SCFAs are needed to test the hypothesis that the association of higher fecal SCFAs with obesity and cardiometabolic dysregulation is due to less efficient SCFA absorption