184 research outputs found

    Evaluación de la amenaza sísmica de Colombia. Actualización y uso en las nuevas normas colombianas de diseño sismo resistente NSR-10

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    La disponibilidad de modelos y técnicas de cálculo más refinadas para la evaluación de la amenaza sísmica, así como la existencia de una mayor cantidad de registros de eventos sísmicos, permite realizar una actualización de los estudios de amenaza sísmica a nivel nacional. Este artículo describe la nueva metodología utilizada para estimar diferentes intensidades sísmicas esperadas para diseño y construcción de edificaciones sismorresistentes en el territorio colombiano. Se presentan los resultados de intensidad obtenidos para diferentes períodos de retorno y ordenadas espectrales para edificaciones de diferentes períodos estructurales, los cuales, además de servir para establecer los valores de diseño en las nuevas Normas NSR-10, también son un insumo necesario para la realización de estudios de microzonificación y de riesgo sísmico dentro del territorio nacional de la República de Colombia

    Fragility Curves for Thin-Walled Cold-Formed Steel Wall Frames Affected by Ground Settlements Due to Land Subsidence

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    Land subsidence phenomenon due to ground water withdrawal is a current problem in many places around the world, particularly in the shallows of Mexico. This causes ground differential settlements that affect structures, mainly dwellings and buildings based on reinforced concrete and masonry. Eventually, these structural materials do not exhibit an adequate performance beyond a certain level of angular distortion. This work presents the results about a study regarding the performance of thin-walled cold-formed steel wall frames with different sheathing systems affected by angular distortions simulating ground differential settlements due to land subsidence. The wall frames are composed by vertical (studs) and horizontal elements (tracks), with different sheathing systems: polystyrene, OSB, gypsum and calcium silicate. By means of experimental testing of wall frames subjected to monotonic lateral loads, the rotational stiffness was obtained for the wall frames with polystyrene. Likewise the rotational stiffness of the other wall frame systems was calculated based on the data provided by other author’s publications. On the other hand, by means of numerical simulation, all the wall frame systems were modeled in structural analysis software, calibrating them based on the rotational stiffness. Also, the moment-rotation curves were calculated for the studs and tracks based on the direct strength method. A non-linear static pull down analysis was performed producing several degrees of angular distortion simulating ground settlements for all the wall frames sheathing systems. With the data acquired fragility curves were calculated according three levels of damage for the wall frames with different sheathing system

    Dosimetric evaluation of radionuclides for VCAM-1-targeted radionuclide therapy of early brain metastases

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    CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOBrain metastases develop frequently in patients with breast cancer, and present a pressing therapeutic challenge. Expression of vascular cell adhesion molecule 1 (VCAM-1) is upregulated on brain endothelial cells during the early stages of metastasis and provides a target for the detection and treatment of early brain metastases. The aim of this study was to use a model of early brain metastasis to evaluate the efficacy of a-emitting radionuclides, Tb-149, At-211, Pb-212, Bi-213 and Ac-225|| beta-emitting radionuclides, Y-90, Tb-161 and Lu-177|| and Auger electron (AE)-emitters Ga-67, Zr-89, In-111 and I-124, for targeted radionuclide therapy (TRT). METHODS: Histologic sections and two photon microscopy of mouse brain parenchyma were used to inform a cylindrical vessel geometry using the Geant4 general purpose Monte Carlo (MC) toolkit with the Geant4-DNA low energy physics models. Energy deposition was evaluated as a radial function and the resulting phase spaces were superimposed on a DNA model to estimate double-strand break (DSB) yields for representative beta- and alpha-emitters, Lu-177 and Pb-212. Relative biological effectiveness (RBE) values were determined by only evaluating DNA damage due to physical interactions. RESULTS: Lu-177 produced 2.69 +/- 0.08 DSB per GbpGy, without significant variation from the lumen of the vessel to a radius of 100 mu m. The DSB yield of Pb-212 included two local maxima produced by the 6.1 MeV and 8.8 MeV alpha-emissions from decay products, Bi-212 and Po-212, with yields of 7.64 +/- 0.12 and 9.15 +/- 0.24 per GbpGy, respectively. Given its higher DSB yield Pb-212 may be more effective for short range targeting of early micrometastatic lesions than Lu-177. CONCLUSION: MC simulation of a model of early brain metastases provides invaluable insight into the potential efficacy of alpha-, beta- and AE-emitting radionuclides for TRT. Pb-212, which has the attributes of a theranostic radionuclide since it can be used for SPECT imaging, showed a favorable dose profile and RBE.81292303CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO306775/2015-8190154/2013-6Agências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig

    Registro inusual de Potos flavus (Schreber, 1774) (Mammalia: Carnivora: Procyonidae) con dermatitis severa en Montes de María, Sucre, Colombia

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    On April 5 and 9, 2018, between approximately 5:00 p.m. and 6:00 p.m., sightings were made of an isolated male individual with signs compatible with severe acariasis in the same location (9 ° 31ʼ47,215ˮN-75 ° 21ʼ06,185ˮW; 165 , 7 masl; Figure 1). During the first observation, the individual found himself inside a hollow formed between a fallen trunk (Fabaceae) and the ground; subsequently he was seen in a place with high herbaceous growth and difficulty in movement was denoted. The animal was observed with extensive allopecic areas, especially in the head, anterior and posterior limbs, abdomen, tail and costal area with crusted wounds at the base of the tail compatible with severe pruritus; In addition, weakness, cachexia and mild ataxia were identified.Durante los días 5 y 9 de abril de 2018, entre las 17h00 y 18h00 aproximadamente, se realizaron avistamientos de un individuo macho aislado con signos compatibles con acariasis severa en la misma localidad (9°31ʼ47,215ˮN-75°21ʼ06,185ˮW; 165,7 msnm; Figura 1). Durante la primera observación, el individuo se encontró dentro de una oquedad formada entre un tronco caído (Fabaceae) y el suelo; posteriormente se le vio dentro de un lugar con alto crecimiento herbáceo y se denotó dificultad para el movimiento. El animal se observó con extensas zonas alopécicas, especialmente en cabeza, miembros anteriores y posteriores, abdomen, cola y zona costal con heridas costrosas en la base de la cola compatibles con prurito severo; además, se identificó debilidad, caquexia y ataxia leve

    Contribution of genetic and epigenetic mechanisms to Wnt pathway activity in prevalent skeletal disorders

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    Producción CientíficaWe reported previously that the expression of Wnt-related genes is lower in osteoporotic hip fractures than in 26 osteoarthritis. We aimed to confirm those results by analyzing β-catenin levels and explored potential genetic 27 and epigenetic mechanisms involved. 28 β-Catenin gene expression and nuclear levelswere analyzed by real time PCR and confocal immunofluorescence. 29 Increased nuclear β-catenin was found in osteoblasts isolated from patients with osteoarthritis (99 ± 4 30 units vs. 76 ± 12, p = 0.01, n = 10), without differences in gene transcription, which is consistent with 31 a post-translational down-regulation of β-catenin and decreased Wnt pathway activity. 32 Twenty four single nucleotide polymorphisms (SNPs) of genes showing differential expression between fractures 33 and osteoarthritis (WNT4, WNT10A, WNT16 and SFRP1) were analyzed in DNA isolated from blood of 853 pa- 34 tients. The genotypic frequencies were similar in both groups of patients, with no significant differences. 35 Methylation ofWnt pathway genes was analyzed in bone tissue samples (15 with fractures and 15 with osteo- 36 arthritis) by interrogating a CpG-based methylation array. Six genes showed significant methylation differences 37 between both groups of patients: FZD10, TBL1X, CSNK1E, WNT8A, CSNK1A1L and SFRP4. The DNA demethylating 38 agent 5-deoxycytidine up-regulated 8 genes, including FZD10, in an osteoblast-like cell line, whereas it down- 39 regulated other 16 genes. 40 In conclusion,Wnt activity is reduced in patientswith hip fractures, in comparisonwith thosewith osteoarthritis. 41 It does not appear to be related to differences in the allele frequencies of the Wnt genes studied. On the other 42 hand, methylation differences between both groups could contribute to explain the differences inWnt activit

    Elastic scattering and α -particle production in 6 He + 208 Pb collisions at 22 MeV

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    Experimental results of the elastic scattering of 6He on 208Pb at E LAB=22 MeV, measured at the CRC facility (Louvain-la-Neuve, Belgium), are presented, including results on the 4He production channel. These data were taken with full angular coverage and high angular resolution. Both experimental cross sections are compared with continuum discretized coupled channels and distorted-wave Born approximation calculations, where direct breakup and transfer to the continuum processes are considered. The elastic data confirm the absence of the Coulomb rainbow, while the distribution of α particles indicates that such production is mostly generated by transfer to the continuum.MICINN FPA2005-04460 FPA200502379 FPA2006-13807-c02-01 FPA2007-63074 FPA2009-07653 FPA2009-07387 FPA2010-22131-C02-01Junta de Andalucía FQM-4964Programa Consolider-Ingenio 2010 CSD2007-00042Comisión Europea HPRI-CT-1999-0011

    Brain Functional Connectivity Is Modified By A Hypocaloric Mediterranean Diet And Physical Activity In Obese Women

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    Functional magnetic resonance imaging (fMRI) in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 +/- 4.07 years. Before and after the intervention program, the body mass index (BMI) (kg/m(2)) was 38.15 +/- 4.7 vs. 34.18 +/- 4.5 (p < 0.02), and body weight (kg) was 98.5 +/- 13.1 vs. 88.28 +/- 12.2 (p < 0.03). All subjects underwent a pre- and post-intervention fMRI under fasting conditions. Functional connectivity was assessed using seed-based correlations. After the intervention, we found decreased connectivity between the left inferior parietal cortex and the right temporal cortex (p < 0.001), left posterior cingulate (p < 0.001), and right posterior cingulate (p < 0.03); decreased connectivity between the left superior frontal gyrus and the right temporal cortex (p < 0.01); decreased connectivity between the prefrontal cortex and the somatosensory cortex (p < 0.025); and decreased connectivity between the left and right posterior cingulate (p < 0.04). Results were considered significant at a voxel-wise threshold of p <= 0.05, and a cluster-level family-wise error correction for multiple comparisons of p <= 0.05. In conclusion, functional connectivity between brain structures involved in the pathophysiology of obesity ( the inferior parietal lobe, posterior cingulate, temporo-insular cortex, prefrontal cortex) may be modified by a weight loss program including a Mediterranean diet and physical exercise
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