DESCRIPCIÓN DEL DESARROLLO DE LA NAVEGABILIDAD COMERCIAL DEL RÍO MAGDALENA

Este artículo explora las actuales condiciones de navegabilidad del ríoMagdalena. Para ello determina sus características físicas, económicas y logísticas relevantes en términos de navegabilidad para cada uno de los tramos del río y las condiciones de infraestructura, inversión en el canal y la oferta y demanda de los productos transportados. Finalmente, se realizan comparaciones con los demás medios de transporte (terrestre, aéreo y ferroviario) evidenciando de esta manera las ventajas y desventajas más relevantes del medio en cuanto a accidentalidad, tiempo de viajes, costosasociados y máxima carga admisible

Effect of Ni on MCM-41 in the Adsorption of Nitrogen and Sulfur Compounds to Obtain Ultra-Low-Sulfur Diesel

Adsorption of heterocyclic sulfur and nitrogen compounds like dibenzothiophene (DBT) and quinoline (Q), respectively, was carried out using mesostructured adsorbent MCM-41 and Ni/MCM-41 in calcined (C) and reduced (R) form. These materials were proved in a batch adsorption system using a model fuel diesel: a mixture of dodecane, DBT and Q with the same concentrations of ppmw of sulfur and nitrogen at 313 K and atmospheric pressure. When MCM-41 was impregnated with Ni, an important modification of the adsorption properties was observed, for example, the uptake of DBT was increased and this adsorption was twice in Ni/MCM-41 in reduce form than in the calcined form. On the other hand, for the nitrogen adsorption of Q diminished by 62 and 58%, considering Ni/MCM-41 in reduce form and in calcined form as adsorbent, respectively. This is a significant achievement regarding the desulfurization and denitrogenation, especially for commercial diesel without pretreatment. Moreover, the kinetic results were adjusted with second order considering Q as nitrogen and DBT as sulfur molecule. Data fitting for Q was achieved better by the Langmuir model for all materials than the Freundlich model, meanwhile the experimental adsorption data of DBT was fitted to the Freundlich model for Ni/MCM-41 calcinated and reduced form

The Menstrual Cycle Modulates Whole-Brain Turbulent Dynamics

Brain dynamics have recently been shown to be modulated by rhythmic changes in female sex hormone concentrations across an entire menstrual cycle. However, many questions remain regarding the specific differences in information processing across spacetime between the two main follicular and luteal phases in the menstrual cycle. Using a novel turbulent dynamic framework, we studied whole-brain information processing across spacetime scales (i.e., across long and short distances in the brain) in two open-source, dense-sampled resting-state datasets. A healthy naturally cycling woman in her early twenties was scanned over 30 consecutive days during a naturally occurring menstrual cycle and under a hormonal contraceptive regime. Our results indicated that the luteal phase is characterized by significantly higher information transmission across spatial scales than the follicular phase. Furthermore, we found significant differences in turbulence levels between the two phases in brain regions belonging to the default mode, salience/ventral attention, somatomotor, control, and dorsal attention networks. Finally, we found that changes in estradiol and progesterone concentrations modulate whole-brain turbulent dynamics in long distances. In contrast, we reported no significant differences in information processing measures between the active and placebo phases in the hormonal contraceptive study. Overall, the results demonstrate that the turbulence framework is able to capture differences in whole-brain turbulent dynamics related to ovarian hormones and menstrual cycle stages

Impaired Mitophagy and Protein Acetylation Levels in Fibroblasts from Parkinson's Disease Patients

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder. While most PD cases are idiopathic, the known genetic causes of PD are useful to understand common disease mechanisms. Recent data suggests that autophagy is regulated by protein acetylation mediated by histone acetyltransferase (HAT) and histone deacetylase (HDAC) activities. The changes in histone acetylation reported to be involved in PD pathogenesis have prompted this investigation of protein acetylation and HAT and HDAC activities in both idiopathic PD and G2019S leucine-rich repeat kinase 2 (LRRK2) cell cultures. Fibroblasts from PD patients (with or without the G2019S LRRK2 mutation) and control subjects were used to assess the different phenotypes between idiopathic and genetic PD. G2019S LRRK2 mutation displays increased mitophagy due to the activation of class III HDACs whereas idiopathic PD exhibits downregulation of clearance of defective mitochondria. This reduction of mitophagy is accompanied by more reactive oxygen species (ROS). In parallel, the acetylation protein levels of idiopathic and genetic individuals are different due to an upregulation in class I and II HDACs. Despite this upregulation, the total HDAC activity is decreased in idiopathic PD and the total HAT activity does not significantly vary. Mitophagy upregulation is beneficial for reducing the ROS-induced harm in genetic PD. The defective mitophagy in idiopathic PD is inherent to the decrease in class III HDACs. Thus, there is an imbalance between total HATs and HDACs activities in idiopathic PD, which increases cell death. The inhibition of HATs in idiopathic PD cells displays a cytoprotective effect

The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory

The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne telesocope in June 2009 for almost six days over the Arctic Circle. As a polarimeter IMaX uses fast polarization modulation (based on the use of two liquid crystal retarders), real-time image accumulation, and dual beam polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to achieve a spectral resolution of 85 mAA. IMaX uses the high Zeeman sensitive line of Fe I at 5250.2 AA and observes all four Stokes parameters at various points inside the spectral line. This allows vector magnetograms, Dopplergrams, and intensity frames to be produced that, after reconstruction, reach spatial resolutions in the 0.15-0.18 arcsec range over a 50x50 arcsec FOV. Time cadences vary between ten and 33 seconds, although the shortest one only includes longitudinal polarimetry. The spectral line is sampled in various ways depending on the applied observing mode, from just two points inside the line to 11 of them. All observing modes include one extra wavelength point in the nearby continuum. Gauss equivalent sensitivities are four Gauss for longitudinal fields and 80 Gauss for transverse fields per wavelength sample. The LOS velocities are estimated with statistical errors of the order of 5-40 m/s. The design, calibration and integration phases of the instrument, together with the implemented data reduction scheme are described in some detail.Comment: 17 figure

Neurovascular Structures at Risk During Anterolateral and Medial Arthroscopic Approaches of the Hip

To describe the safety areas for placement of 5 anterolateral portals (anterior, anterior lateral, posterior lateral, proximal anterior medial and distal anterior medial portals) and 3 recently described medial portals (anterior medial, posterior medial and distal posterior medial portals) to provide topographical description of the safety of each. A descriptive, observational and crosssectional study in which femoral triangle dissection was performed in 12 hips. 5 lateral portals and the 3 medial portals were placed. Clinically relevant neurovascular structures associated with each portal, were identified measured and documented. The lateral portal with the highest risk of injury to a nearby neurovascular structure was the anterior portal, the most adjacent to the femoral cutaneous nerve, 1.42 cm (±0.85) lateral to the portal. In the medial portals, the anterior medial portal has the narrowest margin in relation to the femoral artery, 2.14 cm (±0.35) lateral to the portal and medial to the obturator nerve by 0.87 cm (±0.62). The lateral portals have a higher safety margin; the portal with the most proximity to a neurovascular structure is the anterior portal, associated laterally with the femoral cutaneous nerve, presenting a higher risk of injury. Medial portals have a higher risk of injuring the femoral neurovascular bundle as well as the obturator nerve

Detección de limitantes reproductivas en una granja porcícola integral.

Se identificaron las limitantes reproductivas de una granja porcícola de Risaralda, dada la importancia de esta industria en la región, con los objetivos siguientes: determinar reactividad serológica a brucelosis, pseudorabia, parvovirosis, encefalomiocarditis viral (EMC), leptospirosis y síndrome de infertilidad respiratoria (SIRS), elaborar programas de control para las limitantes halladas, analizar los parámetros reproductivos y evaluar el efecto de las medidas, y contribuir al fomento de una asistencia técnica integral. La porcícola reunía 115 cerdas de cría y un total de 1228 animales de varias razas y sus cruces. El trabajo se efectuó durante 22 meses, en una fase retrospectiva de 12 meses en la cual se analizaron datos de 176 nulíparas y 237 multíparas, y una fase prospectiva de 10 meses, en la cual se analizaron datos de 87 nulíparas y 215 multíparas, siguiendo el diagnóstico e implementación de medidas de control. Se analizaron 11 parámetros reproductivos, para clasificarlos como limitantes o no. Se correlacionaron buscando causalidad común, y se concluyó que la parvovirosis, la leptospirosis y la encefalomiocarditis fueron la causa de las fallas reproductivas halladas en esta explotación. Algunas de las medidas recomendadas no fueron implementadas, o lo fueron tardíamente, por lo cual no se obtuvo el cambio deseado en los parámetros limitantes. El efecto de la EMC se desconoce, y podría ser la causa de una proporción no conocida del problema. Los resultados del trabajo son válidos para esta porcícola y la metodología empleada puede usarse en cualquier explotación simila

Diabetes y enfermedad cardiovascular, aspectos actuales de su manejo: la visión del cardiólogo

La diabetes es una enfermedad prevalente, con casos en aumento en todo el mundo, y se relaciona de forma directa con otras condiciones entre ellas la obesidad. Así, la diabetes supone un riesgo cardiovascular mayor en aquellos pacientes que la padecen y una vez se manifiesta es la causa más importante de morbimortalidad. A lo largo de los últimos años, hemos tenido un cambio en el paradigma del manejo de esta condición, razón por la cual se ha soslayado el enfoque glucocéntrico para hacer una aproximación integral al riesgo global y los demás factores asociados. Los estudios recientes han aportado una valiosa información de seguridad cardiovascular, pero lo más interesante es que han demostrado que algunos grupos farmacológicos generan un beneficio adicional en la población con condición cardiovascular. Es tan fuerte el impacto de estos medicamentos que se están posesionando como la estrategia de manejo inicial para la diabetes

Family History and Breast Cancer Hormone Receptor Status in a Spanish Cohort

Breast cancer is a heterogenous disease that impacts racial/ethnic groups differently. Differences in genetic composition, lifestyles, reproductive factors, or environmental exposures may contribute to the differential presentation of breast cancer among Hispanic women.A population-based study was conducted in the city of Santiago de Compostela, Spain. A total of 645 women diagnosed with operable invasive breast cancer between 1992 and 2005 participated in the study. Data on demographics, breast cancer risk factors, and clinico-pathological characteristics of the tumors were collected. Hormone receptor negative tumors were compared with hormone receptor postive tumors on their clinico-pathological characteristics as well as risk factor profiles.Among the 645 breast cancer patients, 78% were estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+), and 22% were ER−&PR−. Women with a family history of breast cancer were more likely to have ER−&PR− tumors than women without a family history (Odds ratio, 1.43; 95% confidence interval, 0.91–2.26). This association was limited to cancers diagnosed before age 50 (Odds ratio, 2.79; 95% confidence interval, 1.34–5.81).An increased proportion of ER−&PR− breast cancer was observed among younger Spanish women with a family history of the disease