Editorial: cancer ecosystems

Oncology research pioneers such as Stephen Paget focused on how cancer cells favor particular environments and Judah Folkman on how nutrients are provided to these harsh environments. The tumors consist of a heterogeneous population of cancer cells and a stroma with different cell types that define a specific microenvironment and form a tumoral ecosystem. The evolution of the tumors depends on the interactions of the cancer cells with their tumor microenvironment (TME), determining the progression, eradication, or tumor metastasis. A coral ecosystem is similar to tumors in that it is highly complex and energetically productive. A tropical reef-building coral holobiont is composed of the coral metazoan host (the polyp), its endosymbiotic photosynthetic dinoflagellates (Symbiodiniaceae) and other microorganisms, including protozoans, fungi, bacteria, and archaea. Despite their complexity and very high productivity, corals commonly thrive in nutrient-poor environments, which are similar to what is observed in tumors. The contradiction of high coral productivity and limited nutrient availability has been named as the 'Darwin Paradox,' in reference to its first discoverer. This paradox can be explained by the high uptake and efficient recycling of nutrients by coral reef organisms. A similar paradox has been observed in tumors since it is unclear how this complex ecosystem thrives in such nutrient deprived conditions

Frost formation: optimizing solutions under a finite volume approach

Published under licence in Journal of Physics: Conference Series by IOP Publishing Ltd. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.A three-dimensional transient formulation of the frost formation process is developed by means of a finite volume approach. Emphasis is put on the frost surface boundary condition as well as the wide range of empirical correlations related to the thermophysical and transport properties of frost. A study of the numerical solution is made, establishing the parameters that ensure grid independence. Attention is given to the algorithm, the discretised equations and the code optimization through dynamic relaxation techniques. A critical analysis of four cases is carried out by comparing solutions of several empirical models against tested experiments. As a result, a discussion on the performance of such parameters is started and a proposal of the most suitable models is presented.Peer ReviewedPostprint (published version

Numerical simulation of frost growth and densification using deformable and static grids

The present thesis aims at developing a basis for the numerical simulation of the growth and densification of macroscopic frost sheets. Notwithstanding the fact that icing has still a long way to fully understand its physics, this work is potentially important, since a broad range of empirical correlations as well as the implementation of formerly neglected physical effects are studied herewith. In particular, this research is focused on developing methodologies for three-dimensional meshes, capable to predict the frost growth and densification of complex geometries. This work comprises five chapters. The first one is an introduction to icing and frost formation. The main motives that urge to numerically simulate frosting are detailed. Moreover, the different methods and approaches to model frosting are presented. From these, the main objectives and outline of the thesis are derived. The next two chapters are the core of this dissertation, which comprehend the two developed methods. In detail, the second chapter introduces a model that simulates the frost growth and densification using a moving mesh method. First, the most relevant empirical correlations used to describe the frost layer conductivity and diffusivity among others are tested by means of parametric studies. A thorough discussion on the performance of such parameters is made, emphasizing the fact of using diffusion resistance factors above 1.0 in order to capture the frost growth. The best-fitted solutions validate the model input combinations which give good agreements against experimental data under certain experimental conditions. Furthermore, the method is tested against a 2D numerical case, highlighting the main advantages of using a deformable grid, i.e. the accurate tracking of the air-frost interface. The third chapter introduces a fixed-grid-porous-media method capable of simulating the growth and densification of frost sheets. In pursuance of finding out possible explanations to the needed artificially enhanced diffusion resistance factors, a velocity field is calculated across all the domain. A porous media treatment is given to the frost layer, whereas the transported temperature and vapour density are used to define the thermophysical state of each cell, which might enable phase change. The method is tested with a study case of a duct flow with a non-homogeneously cooled lower boundary. The influence of accounting for the convection, as well as the enhanced diffusion resistance factors within the frost layer, are studied. The last two chapters contain the concluding remarks, as well as ideas on how the present work could be continued.La present tesi desenvolupa una base per a la simulació numèrica del creixement i densificació de capes de gebre macroscòpiques. Malgrat que la física de la formació de gel té encara un llarg camí per recórrer, aquest treball és potencialment important, ja que s'hi estudia un ampli rang de correlacions empíriques i la implementació d'efectes físics anteriorment negligits. En particular, aquesta recerca se centra en el desenvolupament de metodologies per a malles tridimensionals, capaces de predir la formació de gebre en geometries complexes. Aquest treball està format per cinc capítols. El primer és una introducció a la formació de gel. En aquest s'hi detallen els motius principals pels quals són necessàries eines numèriques per a la predicció d'aquest fenomen. A més, es presenten els mètodes existents per modelar el gebre. A partir d'aquests, es deriven els principals objectius de la tesi. El segon capítol introdueix un model que simula el creixement i densificació de gebre mitjançant un mètode de malla mòbil. En primer lloc, les correlacions empíriques més rellevants utilitzades per descriure la conductivitat de la capa de gel i la seva difusió entre d'altres són provades mitjançant estudis paramètrics. Es realitza una discussió exhaustiva del rendiment d'aquests paràmetres, fent èmfasi en l'ús de factors de resistència de difusió superiors a 1.0 per tal de capturar el creixement del gebre. A més, el mètode es prova amb un cas numèric 2D, destacant els principals avantatges d'utilitzar una malla deformable, és a dir, el seguiment precís de la interfície gel-aire. El tercer capítol introdueix un mètode de medi porós amb malla fixa, capaç de simular el creixement i densificació de capes de gebre. Amb la intenció de cercar explicacions que verifiquin la necessitat d'utilitzar factors de resistència de difusió artificialment augmentats, es calcula el camp de velocitat a tot el domini. Es realitza un tractament de medi porós en la zona del gebre, i la temperatura i densitat del vapor transportat s'utilitzen per definir l'estat termofísic de cada cel·la, que pot desencadenar un canvi de fase. El mètode es prova amb un cas d'estudi d'un canal de vent amb la paret inferior refredada de forma no homogènia. S'estudia la influència de tenir en compte la convecció, així com els factors de resistència augmentats dins de la capa de gel. Els dos darrers capítols contenen comentaris finals, així com idees sobre com es podria continuar el treball realitzat

Spatial and temporal trends of organic pollutants in vegetation from remote and rural areas

Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) used in agricultural, industrial, and domestic applications are widely distributed and bioaccumulate in food webs, causing adverse effects to the biosphere. A review of published data for 1977-2015 for a wide range of vegetation around the globe indicates an extensive load of pollutants in vegetation. On a global perspective, the accumulation of POPs and PAHs in vegetation depends on the industrialization history across continents and distance to emission sources, beyond organism type and climatic variables. International regulations initially reduced the concentrations of POPs in vegetation in rural areas, but concentrations of HCB, HCHs, and DDTs at remote sites did not decrease or even increased over time, pointing to a remobilization of POPs from source areas to remote sites. The concentrations of compounds currently in use, PBDEs and PAHs, are still increasing in vegetation. Differential congener specific accumulation is mostly determined by continent-in accordance to the different regulations of HCHs, PCBs and PBDEs in different countries-and by plant type (PAHs). These results support a concerning general accumulation of toxic pollutants in most ecosystems of the globe that for some compounds is still far from being mitigated in the near future

La invención de la historia de la arquitectura

El Palacio de Cristal, levantado en Londres para la Gran Exposición de 1851, integró uno de los capítulos más conocidos de la historia de la arquitectura y los diseños. Sin embargo, prácticamente desconocida es la historia del Palacio de Cristal, luego de su traslado al parque de Sydenham, al sudeste de Londres. Relocalizado tres años después, parte del enorme espacio –casi toda el ala norte, de unos 10.000 m2– fue ocupado por una serie de recreaciones de arquitecturas del pasado. Dos grandes patios dedicados al arte grecolatino y medieval estaban acompañados de varios courts: egipcio, griego, romano, bizantino, medieval y renacentista. Uno más celebraba la arquitectura de Asiria en Nínive; y otro, el Islam español, mediante una reproducción del Patio de los Leones de la Alhambra. El edificio y su interior continuaron en pie hasta que un pavoroso incendio destruyó las instalaciones en 1936.Reseña de Designing Antiquity. Owen Jones, Ancien Egypt and the Crystal Palace: Moser S. New Haven, Estados Unidos: Paul Mellon Centre for British Art, Yale University Press, 2012, 320 páginasFacultad de Arquitectura y Urbanism

El saqueo a la historia: cien años de Fletchers : Sir Banister Fletcher: pillar to post-colonial readings

Con veinte ediciones y más de una decena de reimpresiones, pocos libros de historia de la arquitectura tuvieron tal expectativa de vida. En 1896, Banister Fletcher (junior y no sir aún) publicó junto a su padre A history of Architecture, on the Comparative Method. Sin embargo, aquella edición era muy diferente a la que conocimos varias generaciones de estudiantes de arquitectura en toda América Latina. Tenía pocas imágenes y el “método comparado” era más discursivo que gráfico. No obstante, la estructura básica se mantuvo durante el medio siglo siguiente.Reseña de Sir Banister Fletcher: pillar to post-colonial readings McKean, John. The Journal of Architecture, 11(2), Londres, Gran Bretaña: Routledge, the Royal Institute of British Architects, 2006, pp. 187-201. Idioma: inglésFacultad de Arquitectura y Urbanism

Ashes of orchids: stories of the underworld of Buenos Aires in the early 20th century

Este breve ensayo trata de lugares marginales –y a veces ocultos– de la ciudad de Buenos Aires, durante las tres primeras décadas del siglo XX. Los protagonistas fueron dos visitantes, cuya vida ganaría fama y renombre: Eugene O’Neill y Albert Londres. Los relatos de estas dos personalidades, que en los años siguientes se convertirían en famosos protagonistas de la cultura literaria internacional, contribuyeron en buena medida a dar a difundir la imagen oprobiosa y denigrante que la capital argentina tuvo por aquellos años. Sus crónicas de la noche porteña, de sus incontables prostíbulos, cines pornográficos, “garitos” y lugares de diversión nocturna, promovieron la triste celebridad de la que, como “ciudad del pecado”, gozaría Buenos Aires en varios ámbitos internacionales durante las décadas de 1930 y 1940.This short essay is about the marginal, sometimes hidden places of the city of Buenos Aires, during the first three decades of the 20th century. Its main protagonists were two visitors, whose lives would gain fame and popularity: Eugene O’Neill and Albert Londres. The stories of these two personalities, who in later years would become famous protagonists of international literary culture, contributed largely to publicize the shameful and demeaning image that Argentina’s capital was in those years. His chronicles of the “porteña” night –its countless brothels, pornographic movie theaters, gambling houses, and nightlife venues– promoted the sad celebrity as “sin city” that Buenos Aires had internationally during the 1930’s and 1940’s.Instituto de Historia, Teoría y Praxis de la Arquitectura y la Ciuda