Search results for "versification"

Phylogeny and ecological diversification of South African Sarcocornia (Chenopodiaceae)

2007

When do improved covariance matrix estimators enhance portfolio optimization? An empirical comparative study of nine estimators

2011

The use of improved covariance matrix estimators as an alternative to the sample estimator is considered an important approach for enhancing portfolio optimization. Here we empirically compare the performance of 9 improved covariance estimation procedures by using daily returns of 90 highly capitalized US stocks for the period 1997-2007. We find that the usefulness of covariance matrix estimators strongly depends on the ratio between estimation period T and number of stocks N, on the presence or absence of short selling, and on the performance metric considered. When short selling is allowed, several estimation methods achieve a realized risk that is significantly smaller than the one obtai…

Backbone of credit relationships in the Japanese credit market

2016

We detect the backbone of the weighted bipartite network of the Japanese credit market relationships. The backbone is detected by adapting a general method used in the investigation of weighted networks. With this approach we detect a backbone that is statistically validated against a null hypothesis of uniform diversification of loans for banks and firms. Our investigation is done year by year and it covers more than thirty years during the period from 1980 to 2011. We relate some of our findings with economic events that have characterized the Japanese credit market during the last years. The study of the time evolution of the backbone allows us to detect changes occurred in network size,…

Evolution of correlation structure of industrial indices of U.S. equity markets

2013

We investigate the dynamics of correlations present between pairs of industry indices of US stocks traded in US markets by studying correlation based networks and spectral properties of the correlation matrix. The study is performed by using 49 industry index time series computed by K. French and E. Fama during the time period from July 1969 to December 2011 that is spanning more than 40 years. We show that the correlation between industry indices presents both a fast and a slow dynamics. The slow dynamics has a time scale longer than five years showing that a different degree of diversification of the investment is possible in different periods of time. On top to this slow dynamics, we als…

Attempts at diversification: Mexico and Pacific Asia

2002

This article aims to explain the development of Mexico's relations with Pacific Asia. Based on the historical background of Mexico's relations with Asia and on internal and international transformations, we identify the interests of Mexican political actors in Pacific Asia. We provide an overview of the existing political and economic relations between Mexico and Pacific Asia, demonstrating that the success of diversification has been very limited. By trying to explain the gap between the strategic goals and the existing relations we focus on the domestic politics in Mexico. We conclude that intra-elite conflicts had a negative effect on the diversification attempts, since those conflicts p…

Trends in EU Energy Policy 1995–2007

2011

Today, climate change and a significant increase in energy consumption are considered to be the two greatest global challenges facing the energy world (e.g., Hasselmann et al. 2003: 1923; IPCC 2007; Kara 2007: 5; Karl and Trenberth 2003: 1719). In addition to the scientific community having a common understanding about these two issues relating to each other, the political decision makers also need to acknowledge it and start building a framework around it – with the same longterm targets. On the EU-level, climate change concerns were already manifested in the White Paper on Energy Policy for the European Union in 1995. The development of the EU’s common energy policy is also the result of …

Alternative Vehicle Fuel Management: Impact on Energy Security Indicators

2019

Land transport consumes primarily oil products. Their use effects on climate change. A tendency of crude oil price increasing, uneven allocation, and exhaustibility forces to look for alternatives. Alternative vehicle fuel can to reduce energy dependence and meet ecological requirement. The aim of the study was to reveal the basic principles of the alternative vehicle fuel management and its influence on energy security indicators. The fundamental objectives and principles of alternative fuel management were reviewed. The energy security indicators which are affected by the use of alternative fuels were considered. The primary goal of the alternative vehicle fuel management is profit optimi…

Agriculture in a Sicilian inland area: Strategies and motivations of conversion towards multifunctional activities

2016

The main topic of the paper concerns multifunctional farms, their activities and motivations for starting up, and on the other hand visitor satisfaction. To this purpose, a preliminary sample survey was carried out addressed to 13 farms in 3 Sicilian provinces. The aim was to identify positive and negative aspects of the services offered. The most relevant findings of the survey are the variety of activities and services, a widespread use of internet services, efficient means of communications and a significant growth in labour force. On the other side, long time is generally needed in order to obtain administrative authorizations or to carry out farm plants, as well as excessive pay-back t…

The transformation of agricultural systems into agro-forestry systems as a system of adaptation to climate and economic changes: some Sicilian case s…

2021

Many traditional agricultural systems show different limits both in ecological and economic terms. These limits are exacerbated by the increasingly extreme climatic conditions which in the southern regions are manifested essentially in a concentration of rainfall and in increasingly intense dry periods. As part of the LIFE (Desert Adapt) project, some companies involved in the project are modifying their cultivation systems without changing the land use destination. This appears possible by introducing elements of diversification which make the system more resilient as a whole but which guarantees safer economic resources. In particular, in the case of a "classic" agricultural company Calta…

The transformation of agricultural systems into agro-forestry systems as a mechanism of adaptation to climate and economic changes: some Sicilian cas…

2021

Many traditional agricultural systems show different limits both in ecological and economic terms. These limits are exacerbated by the increasingly extreme climatic conditions which in the southern regions are manifested essentially in a concentration of rainfall and in increasingly intense dry periods. As part of the LIFE (Desert Adapt) project, some companies involved in the project are modifying their cultivation systems without changing the land use destination. This appears possible by introducing elements of diversification which make the system more resilient as a whole but which guarantees safer economic resources. In particular, in the case of a "classic" agricultural company Calta…