Modelling urban networks using Variational Autoencoders

A long-standing question for urban and regional planners pertains to the ability to describe urban patterns quantitatively. Cities’ transport infrastructure, particularly street networks, provides an invaluable source of information about the urban patterns generated by peoples’ movements and their interactions. With the increasing availability of street network datasets and the advancements in deep learning methods, we are presented with an unprecedented opportunity to push the frontiers of urban modelling towards more data-driven and accurate models of urban forms.In this study, we present our initial work on applying deep generative models to urban street network data to create spatially explicit urban models. We based our work on Variational Autoencoders (VAEs) which are deep generative models that have recently gained their popularity due to the ability to generate realistic images. Initial results show that VAEs are capable of capturing key high-level urban network metrics using low-dimensional vectors and generating new urban forms of complexity matching the cities captured in the street network data

Urban Transfer Entropy across Scales

The morphology of urban agglomeration is studied here in the context of information exchange between different spatio-temporal scales. Urban migration to and from cities is characterised as non-random and following non-random pathways. Cities are multidimensional non-linear phenomena, so understanding the relationships and connectivity between scales is important in determining how the interplay of local/regional urban policies may affect the distribution of urban settlements. In order to quantify these relationships, we follow an information theoretic approach using the concept of Transfer Entropy. Our analysis is based on a stochastic urban fractal model, which mimics urban growing settlements and migration waves. The results indicate how different policies could affect urban morphology in terms of the information generated across geographical scales

Multifractal methodology

Various methods have been developed independently to study the multifractality of measures in many different contexts. Although they all convey the same intuitive idea of giving a “dimension” to sets where a quantity scales similarly within a space, they are not necessarily equivalent on a more rigorous level. This review article aims at unifying the multifractal methodology by presenting the multifractal theoretical framework and principal practical methods, namely the moment method, the histogram method, multifractal detrended fluctuation analysis (MDFA) and wavelet transform modulus maxima (WTMM), with a comparative and interpretative eye

A new species of coral snake (Serpentes, Elapidae) from the Sierra de Tamaulipas, Mexico

We describe a new species of Micrurus from the Mexican state of Tamauliupas. All of our specimens were encountered in pine-oak forest above an elevation of 750 meters. The new species is related to Micrurus tener, but differs in the absence of a yellow parietal ring and the presence of a tricolored tail

The angular nature of road networks

Road networks are characterised by several structural and geometrical properties. The topological structure determines partially the hierarchical arrangement of roads, but since these are networks that are spatially constrained, geometrical properties play a fundamental role in determining the network’s behaviour, characterising the influence of each of the street segments on the system. In this work, we apply percolation theory to the UK’s road network using the relative angle between street segments as the occupation probability. The appearance of the spanning cluster is marked by a phase transition, indicating that the system behaves in a critical way. Computing Shannon’s entropy of the cluster sizes, different stages of the percolation process can be discerned, and these indicate that roads integrate to the giant cluster in a hierarchical manner. This is used to construct a hierarchical index that serves to classify roads in terms of their importance. The obtained classification is in very good correspondence with the official designations of roads. This methodology hence provides a framework to consistently extract the main skeleton of an urban system and to further classify each road in terms of its hierarchical importance within the system

Uncovering inequality through multifractality of land prices: 1912 and contemporary Kyoto

Multifractal analysis offers a number of advantages to measure spatial economic segregation and inequality, as it is free of categories and boundaries definition problems and is insensitive to some shape-preserving changes in the variable distribution. We use two datasets describing Kyoto land prices in 1912 and 2012 and derive city models from this data to show that multifractal analysis is suitable to describe the heterogeneity of land prices. We found in particular a sharp decrease in multifractality, characteristic of homogenisation, between older Kyoto and present Kyoto, and similarities both between present Kyoto and present London, and between Kyoto and Manhattan as they were a century ago. In addition, we enlighten the preponderance of spatial distribution over variable distribution in shaping the multifractal spectrum. The results were tested against the classical segregation and inequality indicators, and found to offer an improvement over those

Cities and regions in Britain through hierarchical percolation

Urban systems present hierarchical structures at many different scales. These are observed as administrative regional delimitations which are the outcome of complex geographical, political and historical processes which leave almost indelible footprints on infrastructure such as the street network. In this work, we uncover a set of hierarchies in Britain at different scales using percolation theory on the street network and on its intersections which are the primary points of interaction and urban agglomeration. At the larger scales, the observed hierarchical structures can be interpreted as regional fractures of Britain, observed in various forms, from natural boundaries, such as National Parks, to regional divisions based on social class and wealth such as the well-known North–South divide. At smaller scales, cities are generated through recursive percolations on each of the emerging regional clusters. We examine the evolution of the morphology of the system as a whole, by measuring the fractal dimension of the clusters at each distance threshold in the percolation. We observe that this reaches a maximum plateau at a specific distance. The clusters defined at this distance threshold are in excellent correspondence with the boundaries of cities recovered from satellite images, and from previous methods using population density

Understanding sources of measurement error in the Wi-Fi sensor data in the Smart City

Data quality audits are a necessary precursor to quantitative analysis of human activity patterns using primary data collected using automated sensors. This paper reports detailed exploration of the sources of measurement errors that potentially impact upon the quality of the footfall data collected as part of the Consumer Data Research Centre SmartStreetSensor project. Depiction and analysis of activity patterns is integral to numerous applications in urban management, retail and transport planning, and emergency management, yet most analysis to date has remained focused upon data pertaining to nighttime residence as from the Census of Population and daytime estimates through sample surveys or traffic counts. Here we investigate how Wi-Fi signals from mobile devices can be used to estimate levels of human activity at different times and locations and argue about the opportunities and issues arising when using them for estimating footfall

The Mexican consensus on the diagnosis, treatment, and prevention of NSAID-induced gastropathy and enteropathy

Más de 30 millones de personas consumen diariamente antiinflamatorios noesteroideos (AINE) en el mundo, y este consumo se ve incrementado anualmente. Aunque losAINE poseen propiedades analgésicas y antiinflamatorias, sus eventos adversos gastrointesti-nales son bien reconocidos. En nuestro país no existía un consenso respecto al diagnóstico,tratamiento y prevención de la gastropatía y la enteropatía por AINE, por lo que la AsociaciónMexicana de Gastroenterología reunió a un grupo de expertos para establecer recomendacionesde utilidad para la comunidad médica. En este consenso se emitieron 33 recomendaciones. Elconsenso destaca que el riesgo de toxicidad gastrointestinal de los AINE varía según el fármacoempleado y su farmacocinética, lo cual debe ser considerado al momento de su prescripción. Losfactores de riesgo de complicación gastroduodenal por AINE son: antecedente de úlcera pép-tica, edad mayor a 65 a˜nos, dosis altas del AINE, infección por Helicobacter pylori (H.pylori), ypresencia de comorbilidades graves. Los síntomas y el da˜no gastroduodenal inducido por AINEson variables ya que puede cursar asintomático o manifestarse como anemia por deficiencia dehierro, hemorragia, estenosis y perforación. La cápsula endoscópica y la enteroscopia son méto-dos diagnósticos directos en la enteropatía por AINE. Respecto a la prevención, se recomiendaprescribir la dosis mínima necesaria de un AINE para obtener el efecto deseado y durante elmenor tiempo. Finalmente, los inhibidores de la bomba de protones (IBP) representan el están-dar de oro para la profilaxis y tratamiento de los efectos gastroduodenales, mas no son útilesen la enteropatía

Consenso mexicano sobre diagnóstico, prevención y tratamiento de la gastropatía y enteropatía por antiinflamatorios no esteroideos

Más de 30 millones de personas consumen diariamente antiinflamatorios no este-roideos (AINE) en el mundo y este consumo se ve incrementado a˜no tras a˜no. Aunque los AINEposeen propiedades analgésicas y antiinflamatorias, sus eventos adversos gastrointestinales sonbien reconocidos. En nuestro país no existía un consenso respecto al diagnóstico, tratamientoy prevención de la gastropatía y la enteropatía por AINE, por lo que la Asociación Mexicana deGastroenterología reunió a un grupo de expertos para establecer recomendaciones de utilidadpara la comunidad médica. En este consenso se emitieron 33 recomendaciones. El consensodestaca que el riesgo de toxicidad gastrointestinal de los AINE varía según el fármaco empleadoy su farmacocinética, lo cual debe ser considerado al momento de su prescripción. Los factoresde riesgo de complicación gastroduodenal por AINE son: antecedente de úlcera péptica, edadmayor de 65 a˜nos, dosis altas del AINE, infección por Helicobacter pylori y presencia de comor-bilidades graves. Los síntomas y el da˜no gastroduodenal inducido por AINE son variables, ya quepuede cursar asintomático o manifestarse como anemia por deficiencia de hierro, hemorragia,estenosis y perforación. La cápsula endoscópica y la enteroscopia son métodos diagnósticosdirectos en la enteropatía por AINE. Respecto a la prevención, se recomienda prescribir la dosismínima necesaria de un AINE para obtener el efecto deseado y durante el menor tiempo. Porúltimo, los inhibidores de la bomba de protones representan el estándar de oro para la profilaxisy tratamiento de los efectos gastroduodenales, mas no son útiles en la enteropatí