Sentinel 2 as a visualization tool of the historical urban growth of cities

La observación multiespectral de las ciudades desde el espacio es una herramienta sumamente valiosa para conocer la situación actual de las mismas. Sin embargo, estas mismas imágenes pueden aportar información también sobre la historia pasada de las mismas. En este trabajo se propone el procesado de imágenes Sentinel 2 para visualizar el crecimiento urbano de las ciudades a lo largo del tiempo. En concreto, se ha usado la combinación de bandas 12,11,4 y 12,8,3 para obtener imágenes en falso color que resaltan intensamente los diferentes materiales de techado utilizados en el tiempo. Esta combinación de bandas infrarrojas y roja resultan muy útiles para diferenciar materiales como la teja, el cemento o los materiales sintéticos impermeabilizantes, permitiendo diferenciar a simple vista los distintos barrios que forman la ciudad en función de su época de construcción, dando una visión global de las fases de crecimiento de la ciudad. Este tipo de imágenes resultan muy intuitivas para los estudiantes, convirtiéndose en una valiosa herramienta didáctica y de divulgaciónMultispectral observation of cities from space is a key tool for understanding their current state. Moreover, this kind of imagery may provide insight into the past history of cities. This work proposes the process of Sentinel 2 images for visualizing urban growth of cities in time. In particular, RGB composite of bands 12,11,4 and 12,8,3 provide false color images that highlight the different roofing materials used through history. This particular combination of infrared and red bands are very useful for differentiating materials such as red tile, cement or sinthetic impermeabilization materials, allowing to visually different phases of city growth. These images are very intuitive for students and non professionals, becoming a valuable tool for history teaching and divulgatio

Influence of the track quality and of the properties of the wheel rail rolling contact on vehicle dynamics

This work describes an analytical approach to determine what degree of accuracy is required in the definition of the rail vehicle models used for dynamic simulations. This way it would be possible to know in advance how the results of simulations may be altered due to the existence of errors in the creation of rolling stock models, whilst also identifying their critical parameters. This would make it possible to maximize the time available to enhance dynamic analysis and focus efforts on factors that are strictly necessary.In particular, the parameters related both to the track quality and to the rolling contact were considered in this study. With this aim, a sensitivity analysis was performed to assess their influence on the vehicle dynamic behaviour. To do this, 72 dynamic simulations were performed modifying, one at a time, the track quality, the wheel-rail friction coefficient and the equivalent conicity of both new and worn wheels. Three values were assigned to each parameter, and two wear states were considered for each type of wheel, one for new wheels and another one for reprofiled wheels.After processing the results of these simulations, it was concluded that all the parameters considered show very high influence, though the friction coefficient shows the highest influence. Therefore, it is recommended to undertake any future simulation job with measured track geometry and track irregularities, measured wheel profiles and normative values of wheel-rail friction coefficient

Spatio-temporal analysis of the degradation of salts-affected soils in the lacustre system of Texcoco Valley (Mexico)

El Valle de Texcoco, uno de los cinco lagos que conformaban el gran lago de Tenochticlan en el periodo colonial de la ciudad de México (año 1520), es hoy en día una de las regiones del planeta con mayor superficie de suelos afectados por salinidad extrema (>10 000 ha). La salinidad de los suelos es un grave problema en regiones áridas o semiáridas, ya que afecta a la productividad agrícola y la calidad de las aguas, con graves consecuencias socioeconómicas, como la desertificación y migración a las ciudades. Además, las sales se disuelven con facilidad en el suelo, por lo que se requieren herramientas de monitorización precisas que permitan evaluar la alta variabilidad espacio-temporal de los suelos afectados por sales. Este trabajo tiene como objetivo evaluar el estado de los suelos afectados por salinidad en el valle de Texcoco, así como los cambios de uso de suelo acontecidos en los últimos 30 años. Para ello se emplearán técnicas de GIS, imágenes de satélite Landsat desde la década de los 80 hasta la actualidad (1985-2015), y radiómetros de campo para identificar las firmas espectrales de los suelos en condiciones de laboratorio. Una vez procesadas las imágenes de satélite Landsat (corrección radiométrica y atmosférica, y aplicación de filtros), se identificaron diferentes cubiertas o usos de suelo: agua, vegetación semi-natural, tierras de cultivo, suelos sin vegetación y suelos salinos. Se calcularon diferentes índices radiométricos para distinguir la vegetación de las tierras de cultivo y de los suelos salinos. El sistema de clasificación no supervisada mostró cambios de uso de la tierra en el 80% de la superficie en 30 años. Disminuye el agua potable y las tierras agrícolas e incrementan en más de un 20% los suelos degradados por sales o de uso urbano. Se trata de una región con riesgo extremo por pérdida y degradación de las tierras de cultivo por efecto de la salinidadThe Valley of Texcoco, one of the five lakes that formed the great lake of Tenochticlan in the colonial period of Mexico City (year 1520), is today one of the regions with the largest surface area of soils affected by extreme salinity (>10 000 ha). The salinity of soil is a serious problem in arid or semi-arid regions. It affects to agricultural productivity and water quality, with serious socioeconomic consequences, such as desertification and migration of the rural populations to the cities. So, salts dissolve easily in the soil, so precise monitoring tools are necessary to evaluate the high spatiotemporal variability by salts-affected soils. The aim is to evaluate the state of salts-affected soils in the Texcoco Valley, as well as the land use changes in the last 30 years. GIS, Landsat satellite images from the 1980s to the present (1985-2015), and field radiometers will be used to identify the spectral signatures of salts-affected soils under laboratory conditions. Once processed the multispectral images (radiometric and atmospheric correction, and filters application), different land uses were identified: water, semi-natural vegetation, agricultural lands, soil without vegetation and saline soils. Different radiometric indices were used to differentiate vegetation from agricultural and saline soils. The unsupervised classification system showed changes at 80% of the surface in land use in 30 years. Clear water and agricultural land decreased and increased at 20% the soils degraded by salts or urban use. It is a region with extreme risk due to the salts-affected soil

Educación y actividad intraempresarial en egresados universitarios colombianos

This article analyzes entrepreneurship education from the perspective of curricular courses, extracurricular activities, and postgraduate or continuing education in universities; and seeks to contribute to the theoretical evidence of the positive relationship between intrapreneurial activity and education in Colombian universities. For this purpose, a descriptive, correlational and non-experimental study has used contingency tables and a binomial logistic regression model with 3,152 graduates of various undergraduate degree programs from 120 universities. The findings suggest that taking entrepreneurship courses, participating in extracurricular activities, and having additional training after undergraduate degree studies increases the probability of being an intrapreneur. However, the probability is not significant if the graduate participated simultaneously in curricular and extracurricular activities. Post-undergraduate training is the one with the highest odd ratio in the model.El artículo analiza la educación emprendedora en los cursos curriculares, las actividades extracurriculares y la formación de posgrado o continua en universidades, y busca aportar evidencia de la relación positiva entre actividad intraempresarial y educación en egresados de universidades colombianas. Para ello, se llevó a cabo un estudio descriptivo, correlacional y no experimental, a través de tablas de contingencia y un modelo de regresión logística binomial, con 3.152 egresados de diversos programas de pregrado de 120 universidades. Los hallazgos sugieren que el hecho de haber cursado asignaturas curriculares de emprendimiento, participar en actividades extracurriculares y tener formación adicional después del pregrado aumenta la probabilidad de que un egresado sea intraempresario. No obstante, la probabilidad no es significativa si el egresado participó, de manera simultánea, tanto en actividades curriculares como en extracurriculares. La formación posterior al pregrado es la que presenta un odd ratio mayor en el modelo

Effectiveness and safety of sofosbuvir‐based regimens plus an NS5A inhibitor for patients with HCV genotype 3 infection and cirrhosis: results of a multicenter real‐life cohort

[Abstract] Patients with HCV genotype 3 (GT3) infection and cirrhosis are currently the most difficult to cure. We report our experience with sofosbuvir+daclatasvir (SOF+DCV) or sofosbuvir/ledipasvir (SOF/LDV), with or without ribavirin (RBV) in clinical practice in this population. This was a multicenter observational study including cirrhotic patients infected by HCV GT3, treated with sofosbuvir plus an NS5A inhibitor (May 2014‐October 2015). In total, 208 patients were included: 98 (47%) treatment‐experienced, 42 (20%) decompensated and 55 (27%) MELD score >10. In 131 (63%), treatment was SOF+DCV and in 77 (37%), SOF/LDV. Overall, 86% received RBV. RBV addition and extension to 24 weeks was higher in the SOF/LDV group (95% vs 80%, P=.002 and 83% vs 72%, P=.044, respectively). A higher percentage of decompensated patients were treated with DCV than LDV (25% vs 12%, P=.013). Overall, SVR12 was 93.8% (195/208): 94% with SOF+DCV and 93.5% with SOF/LDV. SVR12 was achieved in 90.5% of decompensated patients. Eleven treatment failures: 10 relapses and one breakthrough. RBV addition did not improve SVR (RR: 1.08; P=.919). The single factor associated with failure to achieve SVR was platelet count <75×10E9/mL (RR: 3.50, P=.019). In patients with MELD <10, type of NS5A inhibitor did not impact on SVR12 (94% vs 97%; adjusted RR: 0.49). Thirteen patients (6.3%) had serious adverse events, including three deaths (1.4%) and one therapy discontinuation (0.5%), higher in decompensated patients (16.7% vs 3.6%, P<.006). In patients with GT3 infection and cirrhosis, SVR12 rates were high with both SOF+DCV and SOF/LDV, with few serious adverse events

Search for tt¯ resonances in fully hadronic final states in pp collisions at √s = 13 TeV with the ATLAS detector

This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb of proton-proton collision data recorded at a centre-of-mass energy of s = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a tt¯ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new Z′ boson in a topcolor-assisted-technicolor model. The Z′ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively. [Figure not available: see fulltext.

Human immunodeficiency virus/hepatits C virus coinfection in Spain: Elimination is feasible, but the burden of residual cirrhosis will be significant

Background We assessed the prevalence of antibodies against hepatitis C virus (HCV-Abs) and active HCV infection in patients infected with human immunodeficiency virus (HIV) in Spain in 2016 and compared the results with those of similar studies performed in 2002, 2009, and 2015. Methods The study was performed in 43 centers during October-November 2016. The sample was estimated for an accuracy of 2% and selected by proportional allocation and simple random sampling. During 2016, criteria for therapy based on direct-acting antiviral agents (DAA) were at least significant liver fibrosis, severe extrahepatic manifestations of HCV, and high risk of HCV transmissibility. Results The reference population and the sample size were 38904 and 1588 patients, respectively. The prevalence of HCV-Abs in 2002, 2009, 2015, and 2016 was 60.8%, 50.2%, 37.7%, and 34.6%, respectively (P trend <.001, from 2002 to 2015). The prevalence of active HCV in 2002, 2009, 2015, and 2016 was 54.0%, 34.0%, 22.1%, and 11.7%, respectively (P trend <.001). The anti-HCV treatment uptake in 2002, 2009, 2015, and 2016 was 23.0%, 48.0%, 59.3%, and 74.7%, respectively (P trend <.001). In 2016, HCV-related cirrhosis was present in 7.6% of all HIV-infected individuals, 15.0% of patients with active HCV, and 31.5% of patients who cleared HCV after anti-HCV therapy. Conclusions Our findings suggest that with universal access to DAA-based therapy and continued efforts in prevention and screening, it will be possible to eliminate active HCV among HIV-infected individuals in Spain in the short term. However, the burden of HCV-related cirrhosis will continue to be significant among HIV-infected individuals

Evidence for the production of three massive vector bosons with the ATLAS detector

A search for the production of three massive vector bosons in proton–proton collisions is performed using data at s=13 TeV recorded with the ATLAS detector at the Large Hadron Collider in the years 2015–2017, corresponding to an integrated luminosity of 79.8 fb. Events with two same-sign leptons ℓ (electrons or muons) and at least two reconstructed jets are selected to search for WWW→ℓνℓνqq. Events with three leptons without any same-flavour opposite-sign lepton pairs are used to search for WWW→ℓνℓνℓν, while events with three leptons and at least one same-flavour opposite-sign lepton pair and one or more reconstructed jets are used to search for WWZ→ℓνqqℓℓ. Finally, events with four leptons are analysed to search for WWZ→ℓνℓνℓℓ and WZZ→qqℓℓℓℓ. Evidence for the joint production of three massive vector bosons is observed with a significance of 4.1 standard deviations, where the expectation is 3.1 standard deviations.Peer Reviewe

Measurement of the ratio of cross sections for inclusive isolated-photon production in pp collisions at √s = 13 and 8 TeV with the ATLAS detector

The ratio of the cross sections for inclusive isolated-photon production in pp collisions at centre-of-mass energies of 13 and 8 TeV is measured using the ATLAS detector at the LHC. The integrated luminosities of the 13 TeV and 8 TeV datasets are 3.2 fb and 20.2 fb , respectively. The ratio is measured as a function of the photon transverse energy in different regions of the photon pseudorapidity. The predictions from next-to-leading-order perturbative QCD calculations are compared with the measured ratio. The experimental systematic uncertainties as well as the uncertainties affecting the predictions are evaluated taking into account the correlations between the two centre-of-mass energies, resulting in a reduction of up to a factor of 2.5 (5) in the experimental (theoretical) systematic uncertainties. The predictions based on several parameterisations of the proton parton distribution functions agree with the data within the reduced experimental and theoretical uncertainties. In addition, this ratio to that of the fiducial cross sections for Z boson production at 13 and 8 TeV using the decay channels Z → e e and Z → μ μ is made and compared with the theoretical predictions. In this double ratio, a further reduction of the experimental uncertainty is obtained because the uncertainties arising from the luminosity measurement cancel out. The predictions describe the measurements of the double ratio within the theoretical and experimental uncertainties.[Figure not available: see fulltext.].Peer Reviewe

Measurement of isolated-photon plus two-jet production in pp collisions at √s = 13 TeV with the ATLAS detector

The dynamics of isolated-photon plus two-jet production in pp collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, γ + jet + jet. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from Sherpa and Pythia as well as the next-to-leading-order QCD predictions from Sherpa are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data. [Figure not available: see fulltext.