From Derrida's random energy model to branching random walks: from 1 to 3

We study the extremes of a class of Gaussian fields with in-built hierarchical structure. The number of scales in the underlying trees depends on a parameter alpha in [0,1]: choosing alpha=0 yields the random energy model by Derrida (REM), whereas alpha=1 corresponds to the branching random walk (BRW). When the parameter alpha increases, the level of the maximum of the field decreases smoothly from the REM- to the BRW-value. However, as long as alpha<1 strictly, the limiting extremal process is always Poissonian.Comment: 12 pages, 1 figur

Integrated Empirical-mechanical Seismic Vulnerability Analysis Method for Masonry Buildings in Timișoara: Validation based on the 2009 Italian Earthquake

Background: Timisoara is one of the most important Romanina cities, located in the Banat area and characterised by shallow earthquakes with high ground motion vertical component. The seismicity of the area, in accordance with the P-100 Romanian Code, is affected by medium-high hazard level with an expected maximum PGA of 0.20 g. From a historical-artistic point of view, the city of Timisoara is full of monumental buildings of inestimable values and it was declared as the European Capital of Culture for 2021. Aims: The present work aims to investigate the seismic vulnerability of masonry buildings located in the districts of Fabric and Iosefin, which were grouped in typology classes based on the EMS-98 scale according to their geometrical and structural characteristics. Methods: The performed vulnerability analysis is based on a combined empirical-mechanical procedure to estimate the propensity at the damage of the buildings surveyed. Results: A specific formulation was proposed for typological vulnerability curves of building classes of the examined area, which were calibrated on the basis of the damages detected after occurred earthquakes. Conclusion: The proposed formulation was validated from the application to an urban sector of the municipality of San Pio delle Camere (Italy), which was damaged after the 2009 Abruzzo earthquake

On the REM approximation of TAP free energies

The free energy of TAP-solutions for the SK-model of mean field spin glasses can be expressed as a nonlinear functional of local terms: we exploit this feature in order to contrive abstract REM-like models which we then solve by a classical large deviations treatment. This allows to identify the origin of the physically unsettling quadratic (in the inverse of temperature) correction to the Parisi free energy for the SK-model, and formalizes the $\textit{true}$ cavity dynamics which acts on TAP-space, i.e. on the space of TAP-solutions. From a non-spin glass point of view, this work is the first in a series of refinements which addresses the stability of hierarchical structures in models of evolving populations

Seismic Vulnerability Assessment and Loss Estimation of an Urban District of Timisoara

The seismic risk evaluation of built-up areas is associated to the level of earthquake hazard, building vulnerability and level of exposure. It is well known that the large-scale vulnerability assessment is a very important topic for the protection of historical buildings and the mitigation of effects of natural phenomena on the built-up. In 2020 Timisoara will be the capital of European Culture and, therefore, the knowledge of the number of unusable and collapsed buildings under possible earthquakes is a crucial point to plan suitable future intervention strategies from structural and urban points of view. Based on these premises, the proposed research is conducted in collaboration with the University of Naples "Federico II" with the main purpose to focus on the seismic vulnerability evaluation of buildings located within an urban-sector of Timisoara through the EMS-98 macro-seismic approach. First of all, the typological vulnerability classes of buildings according to the RISK-UE method have been defined in order to classify them from typological and structural viewpoints. Subsequently, a vulnerability form appropriately conceived for masonry aggregates has been filled for the study area buildings and the typological fragility functions have been derived for them aiming at identifying the most vulnerable constructions. Finally, parametric analysis has been carried out by varying the seismic magnitude and site-source distance in order to estimate the seismic loss estimation under earthquakes

Dependence matters: Statistical models to identify the drivers of tie formation in economic networks

Networks are ubiquitous in economic research on organizations, trade, and many other areas. However, while economic theory extensively considers networks, no general framework for their empirical modeling has yet emerged. We thus introduce two different statistical models for this purpose -- the Exponential Random Graph Model (ERGM) and the Additive and Multiplicative Effects network model (AME). Both model classes can account for network interdependencies between observations, but differ in how they do so. The ERGM allows one to explicitly specify and test the influence of particular network structures, making it a natural choice if one is substantively interested in estimating endogenous network effects. In contrast, AME captures these effects by introducing actor-specific latent variables affecting their propensity to form ties. This makes the latter a good choice if the researcher is interested in capturing the effect of exogenous covariates on tie formation without having a specific theory on the endogenous dependence structures at play. After introducing the two model classes, we showcase them through real-world applications to networks stemming from international arms trade and foreign exchange activity. We further provide full replication materials to facilitate the adoption of these methods in empirical economic research

Figures of Merit and Fundamental Processes in the Analysis of Ca from Liquid Samples Using an r.f. CCP Torch with Tubular and Ring Electrodes

A radiofrequency capacitively coupled Ar plasma, obtained with a molybdenum tubular electrode placed inside a quartz tube and one or two copper ring electrodes placed outside the tube, was used as spectral source for determination of atoms, ions and molecular radicals of calcium. A simultaneous spectrometer equipped with a photodiode array was used for detection of emission spectra. The atomization and ionization processes of Ca species were studied in the presence and absence of NaCl and H3PO4 matrix, with both single ring and two rings electrode torches. The limits of detection are 250 ng mL–1 for CaII 393 nm, 100 ng mL–1 for CaI 423 nm, 230 and 100 ng mL–1 for CaOH 555 nm and 622 nm. The recovery degree for certified plasma serum samples was 99.4 &plusmn; 4.4% and the RSD was between 3.8–4.9%. For 5 blood samples the RSD of Ca content is 2.9–4.4%