Topological characterization of antireflective and hydrophobic rough surfaces: are random process theory and fractal modeling applicable?

The random process theory (RPT) has been widely applied to predict the joint probability distribution functions (PDFs) of asperity heights and curvatures of rough surfaces. A check of the predictions of RPT against the actual statistics of numerically generated random fractal surfaces and of real rough surfaces has been only partially undertaken. The present experimental and numerical study provides a deep critical comparison on this matter, providing some insight into the capabilities and limitations in applying RPT and fractal modeling to antireflective and hydrophobic rough surfaces, two important types of textured surfaces. A multi-resolution experimental campaign by using a confocal profilometer with different lenses is carried out and a comprehensive software for the statistical description of rough surfaces is developed. It is found that the topology of the analyzed textured surfaces cannot be fully described according to RPT and fractal modeling. The following complexities emerge: (i) the presence of cut-offs or bi-fractality in the power-law power-spectral density (PSD) functions; (ii) a more pronounced shift of the PSD by changing resolution as compared to what expected from fractal modeling; (iii) inaccuracy of the RPT in describing the joint PDFs of asperity heights and curvatures of textured surfaces; (iv) lack of resolution-invariance of joint PDFs of textured surfaces in case of special surface treatments, not accounted by fractal modeling.Comment: 21 pages, 13 figure

El movimiento estudiantil en Chile (2001-2014). La renovación de la educación como aliciente para el cambio político-social

Our contribution takes into consideration the more significant aspects of the student movement in Chile since 2001, year of the so-called mochilazo, up to nowadays, adopting a perspective aimed to outline the features of a historic process still in progress and in continuous transformation. Special attention is paid to the so-called revolucion de los pinginos and, above all, to the university student movement of 2011, which has been considered by many Chilean sociologists as a new social movement, to be deemed similar to the ones arisen during the recent past also in Europe, that represented the awakening of the civil society in front of the official political affairs. In this respect the relevant bibliography largely refers to Chilean works and is quite disparate, since it consists of documentary texts (investigative reports, memoirs of the protagonists, interviews) as well as historical texts, as the Historia contemporànea de Chile written by Gabriel Salazar and Julio Pinto (2014) and the sociological analysis of Mario Garcés (2012) and of Manuel A. Garretón (2014).

Sapori italiani in Cile. I casi di Capitán Pastene e dell’impresa Ambrosoli

At the beginning of the 20th century, despite the number of Italian immigrants to Chile was not very high, they had a remarkable cultural impact in that country. In this context, our essay aims to analyse a phenomenon which has not been dealt with until today: the production of Italian food in the village of Capitán Pastene (1905) as well as in the confectionary factory Costantino Ambrosoli in Viña del Mar (1948). Their products had been obtained by adapting traditional Italian food to the taste of Chilean consumers and have now become very popular all over the country

E. Lucas Bridges, Ultimo confine del mondo. Viaggio nella Terra del Fuoco

E. Lucas Bridges, Ultimo confine del mondo. Viaggio nella Terra del Fuoco.(Torino, Einaudi, 2009, ISBN 9788806197582, XX- 590 pp.

Arte per il popolo. I murales di David Alfaro Siqueiros (1896-1974) e di Roberto S. Matta (1911-2002) in Cile

The democratic governments of Chile have taken care of the restoration of these murales by revaluing what the dictatorship tried to wipe out. The Author aims at investigating their origin as well their meaning, with reference to both the society and the political ideologies that inspired the painters during the governments of Frente Popular (1938-1941) and of Unidad Popular (1970-1973). In this perspective, the two murales represent meaningful clues for the widening of an inquiry about the relationship between the intellectuals and the political power, within the scope of a specific artistic production, originated as a tool for the class struggle. Keywords: Chile, art, power, mural paintings, intellectuals. L’iniziativa dei governi democratici del Cile di restaurare i murales di Siqueiros e di Matta ha voluto rivalutare ciò che la dittatura aveva cancellato. Nel saggio si è inteso ricostruirne la genesi e il significato rispetto alla società in cui vennero alla luce e alle ideologie politiche a cui si ispirarono gli autori durante i governi del Frente Popular (1938-1941) e quello di Unidad Popular (1970-1973). In questo contesto i due murales costituiscono degli “indizi” significativi per ricostruire i rapporti tra intellettuali e potere, nell’ambito di una produzione artistica che era nata come strumento di lotta. Parole Chiave: Cile, arte, potere, muralismo, intellettuali.The democratic governments of Chile have taken care of the restoration of these murales by revaluing what the dictatorship tried to wipe out. The Author aims at investigating their origin as well their meaning, with reference to both the society and the political ideologies that inspired the painters during the governments of Frente Popular (1938-1941) and of Unidad Popular (1970-1973). In this perspective, the two murales represent meaningful clues for the widening of an inquiry about the relationship between the intellectuals and the political power, within the scope of a specific artistic production, originated as a tool for the class struggle. Keywords: Chile, art, power, mural paintings, intellectuals. L’iniziativa dei governi democratici del Cile di restaurare i murales di Siqueiros e di Matta ha voluto rivalutare ciò che la dittatura aveva cancellato. Nel saggio si è inteso ricostruirne la genesi e il significato rispetto alla società in cui vennero alla luce e alle ideologie politiche a cui si ispirarono gli autori durante i governi del Frente Popular (1938-1941) e quello di Unidad Popular (1970-1973). In questo contesto i due murales costituiscono degli “indizi” significativi per ricostruire i rapporti tra intellettuali e potere, nell’ambito di una produzione artistica che era nata come strumento di lotta. Parole Chiave: Cile, arte, potere, muralismo, intellettuali

A two-scale constitutive parameters identification procedure for elasto-plastic fracture

Constitutive parameters identification for elasto-plastic fracture is a complex problem due to the interplay between two forms of material nonlinearity, viz. plasticity and cohesive fracture. In the present study we examine this problem in relation to Copper specimens covered by Silver used in photovoltaic modules as electrical conductors. Uniaxial tensile tests on un-notched and notched specimens are performed with a tensile stage inside a scanning electron microscope, monitoring crack growth for each imposed far-field displacement. Parameters identification is then performed by considering an elasto-plastic constitutive relation with isotropic hardening for the continuum and a polynomial cohesive zone model (CZM) with two free parameters. For a better numerical-experimental fitting, a four-parameter CZM should be used to independently control the CZM stiffness and the fracture energy. To do so effectively, a constrained optimization procedure with a two-scale objective function is outlined

Quantitative spatiotemporal chemical profiling of individual lipid droplets by hyperspectral CARS microscopy in living human adipose-derived stem cells

There is increasing evidence showing that cytosolic lipid droplets, present in all eucaryotic cells, play a key role in many cellular functions. Yet their composition at the individual droplet level and how it evolves over time in living cells is essentially unknown due to the lack of suitable quantitative non-destructive measurement techniques. In this work we demonstrate the ability of label-free hyperspectral coherent anti-Stokes Raman scattering (CARS) microscopy, together with a quantitative image analysis algorithm developed by us, to quantify the lipid type and content in vol:vol concentration units of individual lipid droplets in living human adipose-derived stem cells during differentiation over 9 days in media supplemented with different fatty acids. Specifically, we investigated the addition of the poly-unsaturated linoleic and alpha-linolenic fatty acids into the normal differentiation medium (mostly containing mono-unsaturated fatty acids). We observe a heterogeneous uptake which is droplet-size dependent, time dependent, and lipid dependent. Cells grown in linoleic acid-supplemented medium show the largest distribution of lipid content across different droplets at all times during differentiation. When analyzing the average lipid content, we find that adding linoleic or alpha-linolenic fatty acids at day 0 results in uptake of the new lipid components with an exponential time constant of 22±2hr. Conversely, switching lipids at day 3 results in an exponential time constant of 60±5hr. These are unprecedented findings, exemplifying that the quantitative imaging method demonstrated here could open a radically new way of studying and understanding cytosolic lipid droplets in living cells