Search results for "ECs"

Threshold rule and scaling behavior in a multi-agent supply chain

2010

In this paper an agent-based model of self organized criticality is developed in a network economy characterized by lead time and a threshold behavior of firms. Instead of considering the aggregate production of the economy as a whole, we focus on both the propagation and amplification effects of a demand shock in the sectorial productions of a multi-agent supply chain. We study a static network structure representing a relation of firms in a lower-upper stream in an industrial organization. In our model, the individual (R, nQ) policies play an important role in generating a propagation effect across the different layers of the economy, and the propagation turns into the large fluctuations …

I gruppi aziendali come fattispecie di aggregazione

2008

Estimating COVID-19-induced Excess Mortality in Lombardy, Italy.

2022

We compare the expected all-cause mortality with the observed one for different age classes during the pandemic in Lombardy, which was the epicenter of the epidemic in Italy. The first case in Italy was found in Lombardy in early 2020, and the first wave was mainly centered in Lombardy. The other three waves, in Autumn 2020, March 2021 and Summer 2021 are also characterized by a high number of cases in absolute terms. A generalized linear mixed model is introduced to model weekly mortality from 2011 to 2019, taking into account seasonal patterns and year-specific trends. Based on the 2019 year-specific conditional best linear unbiased predictions, a significant excess of mortality is estima…

Consumer preferences for food products

2018

Though it started as a niche market, today organic products make up a substantial share of food consumption. In Italy, in terms of production, areas and businesses dedicated to organic farming are on the increase. On the demand side, there is a positive trend in the organic market, especially in the North. The numbers show it: the South produces and the North consumes. Once again, Italy is divided between North and South. Is it an eternal mix, a synthesis of cultural/educational differences that translate into different food styles, or are the other variables that affect it? The South’s underground economy and the absence of an adequate network of distribution channels play an important rol…

From a multivariate spatio-temporal array to a multipollutant - multisite Air Quality Index

2010

AQIs are computed on air pollution data that are usually collected according to time, space and type of pollutant: in a given town/region, data consisting of hourly levels of K pollutants recorded in S monitoring sites, are usually organized in a three-mode array. A first aggregation step usually concerns time, and allows to pass from hourly data to a daily synthesis: in this paper data will be aggregated by time according to the guidelines provided by the national agencies producing the three mode array X. Here we will propose a new approach to get a Multipollutant-Multisite Air Quality Index time series from a multivariate spatio-temporal array. This implies a two step aggregation, accord…

Robustness of air quality indicators: a study of PM10 levels in Scotland

2008

Air quality assessment via functional principal component analysis

2009

The knowledge of the global urban air quality situation represents the first step to face air pollution issues. For the last decades many urban areas can rely on a monitoring network, recording hourly data for the main pollutants. Such data need to be aggregated according to different dimensions, such as time, space and type of pollutant, in order to provide a synthetic air quality index which takes into account interactions among pollutants and correlation among monitoring sites.This paper focuses on Functional Principal Component techniques for the statistical analysis of a set of environmental data x(spt), where s stands for the monitoring site, p for the pollutant and t for time, usuall…

Urban PM10 air quality indicator sensitivity

2008

Aggregate air pollution indices: a new proposal

2009

A new aggregate Air Quality Index (I2) to represent the global air pollution situation for a given city/region is proposed. Accounting for simultaneous exposure to common pollutants and their effects on human health, this index overcomes existing AQIs. Its goodness and utility is shown by a simulation plan and by an application to a real dataset on main pollutants.

The origin of strong ties: the role of weak ties in the evolution of alliance networks

2017

Studies on the structure of alliance networks have explained how the formation, maintenance, and decay of local within cluster ties and shortcuts with semi-distant and distant organizations drive the emergence and evolution of small world architecture in such networks. Interorganizational ties are distinguished into strong and weak on the basis of their strength. Nonetheless, by focusing mainly on strong alliances ties, previous research has fallen short to explain the role of weak ties among organizations for the evolution of alliance networks. With the aim of scrutinizing the role of weak ties in the establishment, maintaining, and transforming of alliance ties, we develop a conceptual fr…