Observation of Raman G-band splitting in top-doped few-layer graphene

An experimental study of Raman scattering in N-layer graphene as a function of the top layer doping is reported. At high doping level, achieved by a CHF_3 plasma treatment, we observe a splitting of the $G$ band in the spectra of bilayer and 4-layer graphene (N even), whereas the splitting is not visible in case of monolayer and trilayer graphene (N odd). The different behaviors are related to distinct electron-phonon interactions, which are affected by symmetry breaking and Fermi level position in different ways in the various N-layer graphenes. In trilayer graphene, a weakening of the electron-phonon coupling as a function of the Fermi energy induces a hardening of all zone-center in-plane optical phonon modes, like in monolayer graphene. On the other hand, in 4-layer graphene two distinct trends are observed in the G band as a function of doping, suggesting the presence of two different groups of electron-phonon interactions, like in bilayer graphene.Comment: 7 pages, 6 figures, to be published in PR

Biomass energy: new opportunity for agriculture and marginal areas?

As it is well known, energy is essential for human activities. Despite the high level of technological progress, the increase of energy consumption, satisfied mainly by fossil fuels, raises a series of issues linked to the scarcity of oil reserves, and their growing cost, and to a delicate relationship (and dependence) with a restricted number of world regions and nations. A greater diversification of the energy supply is one of the solutions to solve these problems, especially in the field of renewable resources. Despite the fact that biofuels are still more expensive than fossil fuels, they present many advantages: they are not subject to a progressive exhaustion and their impact on the environment is very low, due to their inclusion in natural cycles. Among biofuels a relevant role is played by the biomass, a renewable resource, that is obtained from the fraction of products, waste and residues from agriculture, forestry and related industries, as well as the biodegradable fraction of industrial and municipal waste. This resource allows a relevant control of the greenhouse gas emission, a minor dependence from oil and gas resources and represents a way for the economic valorisation of local resources and a opportune utilisation of agricultural wastes. In this context, the aims of the paper are to highlight the opportunities and the bonds that the biomass utilisation involves, to analyse the main public policies adopted to boost a large-scale production and consumption, to measure the different degree of utilisation at national (Italy) and European levels and to draw future scenarios. Particular attention will be paid to the European policies starting from the 1992 reform process until nowadays, having in mind the shortage of cereals in the world market. Where possible and opportune, the situation of Italy and of the European union will be compared with that of India, mainly, as regards public decisions/programmes. The paper concludes with an analysis of the role that the biofuel production is expected to offer in terms of new opportunities to diversify income and employment in rural and marginal areas.Biomass energy, rural and marginal areas, energy public policies

The EU and Asia: World Trade Liberalisation and the Evolution of Agricultural Product Flows

In the trade policy debate, the complete liberalisation of world trade for agricultural products is one of the most relevant issues. European Union is a free trade area where agricultural products are protected and supported from the world market forces, more than any other good or service. The elimination of trade barriers among the EU member states has achieved European self-sufficiency in food and a strong integration in the European market. To resolve international disputes, Mc Sharry, Agenda 2000 and Mid Term Reforms of the CAP were introduced in the last decade, having in mind the reduction of domestic support, tariff barriers and export subsides. In this context, this paper studies the evolution of these trade flows among EU and some selected Asiatic countries. The aim is, on the one hand, to consider the impact of the progressive liberalisation of world agricultural trade in these areas, on the other hand, to measure the integration degree of these groups of countries. In order to be able to study these topics, this paper analyses the evolution of agricultural trade and of the role played by the different product groups. The paper is divided into three sections, followed by some concluding remarks. The first section studies the main agrarian policies adopted in the EU and some selected Asiatic countries. The second section presents the relationships among them. The third describes the agricultural import and export flows, considering the trade from a general perspective, from the point of view of the political decisions adopted and that of the agreements signed.world trade, agricultural products, Asia and Europe integration

Diffusion of finite-size particles in confined geometries

The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle’s dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined

Territorial cooperation and regional economic development: a case study

Cooperation may be defined as the collaboration between two or more parties which fuels initiatives that have shared, or converging interests and objectives. In the European Union territorial cohesion has recently been included in the draft of the European Constitution and is complementary to the EU drive towards economic and social cohesion. This adds a new dimension to European integration which clearly recognises that considering things from a territorial dimension is a tool for reducing the territorial disparity currently present in the EU. In fact, well before its enlargement, significant disparities in prosperity levels existed both between and within member states: prosperity levels in the ten most dynamic regions of the EU, based on GDP per capita, were nearly three times higher than that of the ten least developed regions and regional differences have widened with enlargement. In this context, the territorial cooperation objective aims to: improve cross-border cooperation through joint, local and regional initiatives; strengthen trans-national cooperation by means of actions conducive to integrated territorial development linked to Community priorities as well as to strengthen interregional cooperation and the exchange of experience at the appropriate territorial level. Three different typologies of territorial cooperation have been identified with the European territory: cross-border cooperation, trans-national cooperation and Interregional cooperation. The paper focuses on the territorial cooperation objective and presents a case study with large and strong economic, social and environmental disparities. It includes EU members and non EU members. More specifically, the IPA (Instrument for Pre-Accession Assistance) Adriatic Cross Border Cooperation (CBC) Program, which includes three EU Member States, one Candidate Country, and three Potential Candidates Countries.cooperation, regional disparities, european external instruments

Long-term cereal price changes: how important is the speculative element

The objective of this article is to provide an analysis of the relationship existing between cereal prices and several variables such as population, income, exports, the exchange rate, and speculation, by using a linear regression analysis. Specific emphasis is placed on the speculative dimension. The methodology used helps us explore the forms of relationships between the different variables, and, more specifically, it gives an insight into the extent of speculation during the recent critical time period. Our results show that speculation (defined by the long position of traders) has played a crucial role during the period June 2001 – December 2009. According to our analysis, speculation it is the most relevant independent variable that affects cereal prices. Exports, in some ways connected to the former variable, occupy second place, in term of significance. However, their impact on cereal prices is less relevant than that of biofuel production. Population growth does not have impact in a positive way on cereal prices; it acts in the opposite direction due to the change in diets, implying that population increases would tend to affect primarily other agricultural markets. Excessive volatility in food prices, as that observed in the last years is a dramatic question. From a demand point of view, consumers in developing countries and vulnerable income groups in other countries (farmers) have to be protected. More than one policy on both international markets and domestic markets have to be introduced so as to lessen food/cereal lower price volatility.cereal prices, future markets and speculation, renewable energy, agricultural demand and supply.

Rice price volatility: a dilemma for public policies in Asia and Europe?

In 2008 the world’s attention was focused on the global food crisis and, as consequence, on the global food security. By mid-2009, commodity prices have dropped sensitively, nevertheless most of them still remain at or above past trend levels. Fluctuations in prices are not rare in agricultural markets where volatility is a common characteristic. Among cereals rice has a strategic importance. It is source of nutrition for more than a half of the world population and of income for about two million of farmers. Even if it is produced and consumed everywhere, production and consumption are concentrated in Asia. Because of its strategic importance, rice is and has been subject to a host of policy interventions that have made it feature among the most distorted of all agricultural commodities. Export policies have typically been applied by net exporting countries and one of the most commonly applied policy measures, adopted by net importing countries, is the removal or reduction of import duties and taxes on food commodities. Various forms of producer support measures were introduced, including input subsidies, output price support and an easing of cropland set-aside requirements. Policies to support consumers and vulnerable groups have included: direct consumer subsidies, tax reductions, distribution from public stocks, price subsidies, public-sector salary increases and social safety net programmes. Self-targeting food-for-work programmes have been put in place by some countries. Although the EU rice trade represents only 0.4 per cent of world trade a common organisation market (COM) for rice was set-up. It is a complex system aiming at maintaining European rice production destined for domestic and external markets. This paper aims to expand the above statements. The objective is to review and compare the policies adopted in Asia and in the EU and assess their impact form the point of sustainability (in a broad sense) with the ultimate aim to advance some interpretations and suggestions in the short and long run, having in mind the variables that affect the supply, the demand and the trade. As a background, the paper first outlines the characteristics of the rice market. Through a regression analysis that could help to understand how the rice price changes. It also considers the policies adopted in Asia and in the EU, highlighting their results on prices from an economic and social point of view. This paper concludes with a number of issues to be borne in mind when interpreting the volatility or rice prices (according to the regression analysis results), the expected policy impact and distortions, and, finally, the “relatively” new strategy: move from food security to self-sufficient food security, one of the long terms goals of the Treaty of Rome (to secure availability of supplies).food security, rice market, public policies, regression analysis

Jets in 200 GeV p+p and d+Au collisions from the STAR experiment at RHIC

Full jet reconstruction in heavy-ion collisions is a promising tool for the quantitative study of properties of the dense medium produced at RHIC. Measurements of d+Au collisions are important to disentangle initial state nuclear effects from medium-induced kT broadening and jet quenching. Study of jet production and properties in d+Au in combination with similar studies in p+p is an important baseline measurement needed to better understand heavy-ion results. We present mid-rapidity inclusive jet pT spectra and di-jet correlations (kT) in 200 GeV p+p and d+Au collisions from the 2007-2008 RHIC run. We discuss the methods used to correct the data for detector effects and for background in d+Au collisions.Comment: 4 pages, 5 figures. To appear in Hot Quarks 2010 conference proceeding

Geometric deep learning: going beyond Euclidean data

Many scientific fields study data with an underlying structure that is a non-Euclidean space. Some examples include social networks in computational social sciences, sensor networks in communications, functional networks in brain imaging, regulatory networks in genetics, and meshed surfaces in computer graphics. In many applications, such geometric data are large and complex (in the case of social networks, on the scale of billions), and are natural targets for machine learning techniques. In particular, we would like to use deep neural networks, which have recently proven to be powerful tools for a broad range of problems from computer vision, natural language processing, and audio analysis. However, these tools have been most successful on data with an underlying Euclidean or grid-like structure, and in cases where the invariances of these structures are built into networks used to model them. Geometric deep learning is an umbrella term for emerging techniques attempting to generalize (structured) deep neural models to non-Euclidean domains such as graphs and manifolds. The purpose of this paper is to overview different examples of geometric deep learning problems and present available solutions, key difficulties, applications, and future research directions in this nascent field