Elementary processes governing the evolution of road networks

Urbanisation is a fundamental phenomenon whose quantitative characterisation is still inadequate. We report here the empirical analysis of a unique data set regarding almost 200 years of evolution of the road network in a large area located north of Milan (Italy). We find that urbanisation is characterised by the homogenisation of cell shapes, and by the stability throughout time of high-centrality roads which constitute the backbone of the urban structure, confirming the importance of historical paths. We show quantitatively that the growth of the network is governed by two elementary processes: (i) `densification', corresponding to an increase in the local density of roads around existing urban centres and (ii) `exploration', whereby new roads trigger the spatial evolution of the urbanisation front. The empirical identification of such simple elementary mechanisms suggests the existence of general, simple properties of urbanisation and opens new directions for its modelling and quantitative description.Comment: 10 pages, 6 figure

Proposal for a new classification of a deep branching bacterial phylogenetic lineage: Transfer of Coprothermobacter proteolyticus and Coprothermobacter platensis to Coprothermobacteraceae fam. nov., within Coprothermobacterales ord. nov., Coprothermobacteria classis nov. and Coprothermobacterota phyl. nov. and emended description of the family Thermodesulfobiaceae

The genus Coprothermobacter (initially named Thermobacteroides) is currently placed within the phylum Firmicutes. Early 16S rRNA gene based phylogenetic studies pointed out the great differences between Coprothermobacter and other members of the Firmicutes, revealing that it constitutes a new deep branching lineage. Over the years, several studies based on 16S rRNA gene and whole genome sequences have indicated that Coprothermobacter is very distant phylogenetically to all other bacteria, supporting its placement in a distinct deeply rooted novel phylum. In view of this, we propose its allocation to the new family Coprothermobacteraceae within the novel order Coprothermobacterales, the new class Coprothermobacteria, and the new phylum Coprothermobacterota, and an emended description of the family Thermodesulfobiaceae.Fil: Pavan, Maria Elisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Pavan, Esteban E.. Politecnico di Milano; ItaliaFil: Glaeser, Stefanie P.. Universitat Giessen; AlemaniaFil: Etchebehere, Claudia. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: Kämpfer, Peter. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Pettinari, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: López, Nancy Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

Tribological performance of novel Nickel-based composite coatings with lubricant particles

Abstract The present study is focused on the evaluation of the tribological performance of novel Ni/hBN and Ni/WS2 composite coatings electrodeposited from an additive-free Watts bath with the assistance of ultrasound. Lubricated and non-lubricated scratch tests were performed on both novel composite coatings and on standard Ni deposits used as a benchmark coating to have an initial idea of the effect of the presence of particles within the Ni matrix. Under lubricated conditions, the performance of the Ni/hBN composite coating was very similar to the benchmark Ni coating, whereas the Ni/WS2 behaved quite differently, as the latter did not only show a lower coefficient of friction, but also prevented the occurrence of stick-slip motion that was clearly observed in the other coatings. Under non-lubricated conditions, whereas the tribological performance of the Ni/hBN composite coating was again very similar to that of the benchmark Ni coating, the Ni/WS2 composite coatings again showed a remarkable enhancement, as the incorporation of the WS2 particles into the Ni coating not only resulted in a lower coefficient of friction, but also in the prevention of coating failure

Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being

This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics

Modeling house price dynamics with heterogeneous speculators

This paper investigates the impact of speculative behavior on house price dynamics. Speculative demand for housing is modeled using a heterogeneous agent approach, whereas ‘real’ demand and housing supply are represented in a standard way. Together, real and speculative forces determine excess demand in each period and house price adjustments. Three alternative models are proposed, capturing in different ways the interplay between fundamental trading rules and extrapolative trading rules, resulting in a 2D, a 3D, and a 4D nonlinear discretetime dynamical system, respectively. While the destabilizing effect of speculative behavior on the model’s steady state is proven in general, the three specific cases illustrate a variety of situations that can bring about endogenous dynamics, with lasting and significant price swings around the ‘fundamental ’ price, as we have seen in many real markets

Effects of the Cryptochrome CryB from Rhodobacter sphaeroides on Global Gene Expression in the Dark or Blue Light or in the Presence of Singlet Oxygen

Several regulators are controlling the formation of the photosynthetic apparatus in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. Among the proteins affecting photosynthesis gene expression is the blue light photoreceptor cryptochrome CryB. This study addresses the effect of CryB on global gene expression. The data reveal that CryB does not only influence photosynthesis gene expression but also genes for the non-photosynthetic energy metabolism like citric acid cycle and oxidative phosphorylation. In addition several genes involved in RNA processing and in transcriptional regulation are affected by a cryB deletion. Although CryB was shown to undergo a photocycle it does not only affect gene expression in response to blue light illumination but also in response to singlet oxygen stress conditions. While there is a large overlap in these responses, some CryB-dependent effects are specific for blue-light or photooxidative stress. In addition to protein-coding genes some genes for sRNAs show CryB-dependent expression. These findings give new insight into the function of bacterial cryptochromes and demonstrate for the first time a function in the oxidative stress response

Ethnic Concentration, Cultural Identity and Immigrant Self-Employment in Switzerland

Immigrant self-employment rates vary considerably across regions in Switzerland. Business ownership provides an alternative to wage labour, where immigrants have to face structural barriers such as the limited knowledge of the local language, or difficulties in fruitfully making use of their own human capital. Despite their historically high unemployment rates with respect to natives, immigrants in Switzerland are less entrepreneurial. It is therefore important to uncover factors that may facilitate the transition from the status of immigrant to the one of economic agent. Among others factors, concentration in ethnic enclaves, as well as accumulated labour market experience and time elapsed since immigration, have been associated to higher business ownership rates. In this paper, we use a cross-section of 2,490 Swiss municipalities in order to investigate the role played by the ethnic concentration of immigrants, as well as cultural factors, in determining self-employment rates