Classical theta constants vs. lattice theta series, and super string partition functions

Recently, various possible expressions for the vacuum-to-vacuum superstring amplitudes has been proposed at genus $g=3,4,5$. To compare the different proposals, here we will present a careful analysis of the comparison between the two main technical tools adopted to realize the proposals: the classical theta constants and the lattice theta series. We compute the relevant Fourier coefficients in order to relate the two spaces. We will prove the equivalence up to genus 4. In genus five we will show that the solutions are equivalent modulo the Schottky form and coincide if we impose the vanishing of the cosmological constant.Comment: 21 page

From Manufacturing to Advanced Services. The (Uneven) Rise and Decline of Mediterranean City-Regions

Uneven changes in the global urban hierarchy have given way to new forms of relationships between urban and rural areas based on complementarities, cooperative and specialized exchange of services and goods, abandoning the additive processes of growth guided by industrialization and urbanization. Representing a distant notion from traditional concepts in regional studies such as 'compact cities' or 'suburbs', 'gravitation' or 'hierarchy', the 'city-region' paradigm has stimulated different visions to be recomposed within the 'sustainability' framework. With global changes, the 'mega-city region' model has starting to take the lead in the development of contemporary urban agglomeration. In this study, considerations over the emergence of this urban model in the Mediterranean region will be presented to investigate the relationship between dispersed urbanization and consolidating southern European city-regions. While Mediterranean cities have been considered for long time as ‘ordinary’ cities, rather distant from the 'globalized' northern urban models, most of these cities are characterized by distinctive socioeconomic traits possibly open to competition and globalization. The present contribution describes the emergence of a Mediterranean urban area, Athens, as a new 'city-region' in the context of urbanization processes in Greece and in the Mediterranean basin as a whole. One of the clearest indications of urban competitiveness amongst emerging and established large city-regions is the fight for hosting mega-events. The final objective of the study is to understand how the efforts for increasing urban competitiveness are impacting new forms of cityregions, mainly based on low-density settlements reflecting discontinuous urbanization

Italian adaptation and psychometric properties of the prejudice against immigrants scale (PAIS): assessment of validity, reliability, and measure invariance

The aim of the current study was to adapt and validate the Prejudice Against Immigrants Scale (PAIS) in the Italian context, based on the Prejudice Against Asylum Seekers Scale by Anderson (2018). The validity, reliability, and measurement invariance across gender, age, and educational levels of the scale were assessed through three sources, which involved 306 Italian individuals (Nmen = 151, 49.3%) between 18 and 60 years old. Both exploratory and confirmatory factor analyses (CFA) confirmed the two-factor solution of the original instrument by excluding two items, which were present in the previous validation study. The first factor is classical prejudice against immigrants, which maps onto theoretical derivations of classical and old-fashioned prejudices, whereas the second factor is conditional prejudice against immigrants, which maps onto theoretical derivations of subtle and modern prejudices. Findings of the multigroup CFAs demonstrated full configural and metric invariance and partial scalar invariance of the scale across gender, age, and educational level. The analyses confirmed that PAIS has high levels of reliability and criterion and construct validity, showing findings that are comparable to those of Anderson (2018). These results suggest that PAIS presents very good psychometric properties and could be considered a valid and reliable instrument to measure prejudice against immigrants, by enabling Italian researchers to detect both covert and more subtle forms of prejudice against immigrants. Limitations and further directions are discussed

The vanishing of two-point functions for three-loop superstring scattering amplitudes

In this paper we show that the two-point function for the three-loop chiral superstring measure ansatz proposed by Cacciatori, Dalla Piazza, and van Geemen vanishes. Our proof uses the reformulation of ansatz in terms of even cosets, theta functions, and specifically the theory of the $\Gamma_{00}$ linear system on Jacobians introduced by van Geemen and van der Geer. At the two-loop level, where the amplitudes were computed by D'Hoker and Phong, we give a new proof of the vanishing of the two-point function (which was proven by them). We also discuss the possible approaches to proving the vanishing of the two-point function for the proposed ansatz in higher genera

Unraveling the (intrinsic) linkage between social spending and regional development: An empirical analysis for European union countries

Theoretical approaches and place-specific solutions are required to face with the intrinsic linkage between social welfare and macroeconomic stability in advanced economies, especially in Europe. In this regard, the 2007 recession has influenced extensively the wide spectrum of social policies applicable in the European Community. New socioeconomic divides emerged and fiscal austerity urged Member States to resettle policy discourses, advancing social needs in a more effective way. In line with this evidence, our commentary discusses recent literature and it outlines policy implications of different political, institutional and socioeconomic settings. By analyzing cross-country variations in the shape and extent of welfare policies at the European level, our study evaluates apparent (and latent) performances of welfare systems in a comparative perspective, with a specific focus on Southern European countries. The existence of a latent relationship between social policy expenditures (SPE) and per-capita GDP was demonstrated. However, social expenditures may differ for a given level of income: for instance, Latvia had a lower level of social expenditures given its income level. Italy, Greece, Spain and Portugal were clustered together displaying a lower share of social spending in the total GDP in respect with the remaining European countries. This comparison suggests how Mediterranean countries are institutionally fragile and with a moderately higher level of corruption in respect with North-western countries. The results of this work contribute to bridge the semantic dichotomy between theoretical approaches and empirical findings in socioeconomic policy impact analysis

Unravelling the role of socioeconomic forces in the early stage of covid-19 pandemic: A global analysis

The COVID-19 pandemic has rapidly evolved into an acute health crisis with extensive socioeconomic and demographic consequences. The severity of the COVID-19 pandemic requires a refined (and more comprehensive) understanding of virus dissemination over space, transmission mechanisms, clinical features, and risk factors. In line with this assumption, the present study illustrates a comparative, empirical analysis of the role of socioeconomic and demographic dimensions in the early stages of the COVID-19 pandemic grounded on a large set of indicators comparing the background context across a global sample of countries. Results indicate that—in addition to epidemiological factors—basic socioeconomic forces significantly shaped contagions as well as hospitalization and death rates across countries. As a response to the global crisis driven by the COVID-19 pandemic, all-embracing access to healthcare services should be strengthened along with the development of sustainable health systems supported by appropriate resources and skills. The empirical findings of this study have direct implications for the coordination of on-going, global efforts aimed at containing COVID-19 (and other, future) pandemics

Spectral decomposition of starbursts and AGNs in 5-8 micron Spitzer IRS spectra of local ULIRGs

We present an analysis of the 5-8 micron Spitzer-IRS spectra of a sample of 68 local Ultraluminous Infrared Galaxies (ULIRGs). Our diagnostic technique allows a clear separation of the active galactic nucleus (AGN) and starburst (SB) components in the observed mid-IR emission, and a simple analytic model provides a quantitative estimate of the AGN/starburst contribution to the bolometric luminosity. We show that AGNs are ~30 times brighter at 6 micron than starbursts with the same bolometric luminosity, so that even faint AGNs can be detected. Star formation events are confirmed as the dominant power source for extreme infrared activity, since ~85% of ULIRG luminosity arises from the SB component. Nonetheless an AGN is present in the majority (46/68) of our sources.Comment: 5 Pages, 3 figures. MNRAS Letters, Accepte

On the significance of diffuse crack width self-evolution in the phase-field model for residually stressed brittle materials

The Phase-Field method is an attractive numerical technique to simulate fracture propagation in materials relying on Finite Element Method. Its peculiar diffuse representation of cracks makes it suitable for a myriad of problems, especially those involving multiple physics and complex-shaped crack patterns. Recent literature provided linear relationships between the width of the diffuse crack and the material intrinsic fracture toughness, through a material characteristic length. However, lately, it was shown how the existence of a residual stress field can affect the represented crack width even for fully homogeneous materials, in terms of toughness. In this short note, the authors tried to shed some light on the factors influencing the width of the diffuse crack representation. By simulating crack propagation in several residually stressed brittle materials, it was shown how the width of the diffuse crack is affected by the ratio between the driving force - due to the externally applied load - and the driving force required to propagate the crack. In other words, the diffuse crack extent can be linked to the degree of crack propagation stability/instability. Monitoring the evolution of the studied quantity can be of great interest to rapidly assess crack instability circumstances, under displacement control

Experimental characterization and modelling of cyclic elastoplastic response of an AISI 316L steel lattice structure produced by laser-powder bed fusion

In the last few years, many studies have been devoted to elucidating the mechanical properties of lattice structures produced by additive manufacturing (AM) techniques. Nevertheless, virtually none of the works dealt with the cyclic elastoplastic response, which is instead the focus of the present study. An AISI 316L steel FBCCZ (face and body-centered cell with vertical struts along the z-axis) lattice structure, produced by the AM technique laser-powder bed fusion (L-PBF), was experimentally tested and modelled using the finite element method. The mechanical behavior of the L-PBF AISI 316L steel was described by a non-linear kinematic (Chaboche's model) and isotropic (Voce's model) hardening model. Numerical results and their comparison with experimental evidence suggested that the study of a single unit cell by exploiting the periodicity condition can be severely impaired by the numerousness of the cells involved. More faithful models, accounting for the sample's edges effects, and including the effective dimension of the fabricated features by AM, lead to a highly satisfactory match, thus confirming the applicability of the proposed approach