Entanglement negativity in quantum field theory

We develop a systematic method to extract the negativity in the ground state of a 1+1 dimensional relativistic quantum field theory, using a path integral formalism to construct the partial transpose rho_A^{T_2} of the reduced density matrix of a subsystem A=A1 U A2, and introducing a replica approach to obtain its trace norm which gives the logarithmic negativity E=ln||\rho_A^{T_2}||. This is shown to reproduce standard results for a pure state. We then apply this method to conformal field theories, deriving the result E\sim(c/4) ln(L1 L2/(L1+L2)) for the case of two adjacent intervals of lengths L1, L2 in an infinite system, where c is the central charge. For two disjoint intervals it depends only on the harmonic ratio of the four end points and so is manifestly scale invariant. We check our findings against exact numerical results in the harmonic chain.Comment: 4 pages, 5 figure

Entanglement entropy and quantum field theory: a non-technical introduction

In these proceedings we give a pedagogical and non-technical introduction to the Quantum Field Theory approach to entanglement entropy. Particular attention is devoted to the one space dimensional case, with a linear dispersion relation, that, at a quantum critical point, can be effectively described by a two-dimensional Conformal Field Theory.Comment: 10 Pages, 2 figures. Talk given at the conference "Entanglement in Physical and information sciences", Centro Ennio de Giorgi, Pisa, December 200

Planning the Integrated Management of Organic Waste Flows and Agricultural Residues for a Circular Economy

In the recent years, the production, management and disposal of both organic waste and agricultural residues has become significantly difficult in Italy, due to the lack of suitable facilities. Very often, indeed, within the different regions, there are no treatment plants for the organic fraction of municipal solid waste or agricultural residues treatment centres, so as to give them a second life in the perspective of a circular economy. The lack of proximity treatment centres, forces local administrations to send these flows to plants outside their territorial area, with a consequent increase for transport and treatment costs. This paper, with reference to the study area of the Matera municipality (Basilicata region - Southern Italy), taking into consideration the organic waste flows of non-domestic users from separate collection and agricultural residues - especially those coming from the wine production chain - provides a state-of-the-art analysis of the problems related to their collection, management and disposal. Subsequently, an alternative model feasibility study - called "proximity composting", aimed at a more sustainable management of these flows based on their “zero-kilometers treatment” – has been implemented. The results obtained have demonstrated that the proposed scenario is much more sustainable when compared to the current situation, both from an economic and environmental point of view. Indeed, thanks to the use of calculation tools, the economic (€/year) and environmental (Kg CO2 avoided/year) advantages, due to the save of transport and disposal of flows outside the region, have been quantified, with consequent reduction of waste tax for citizens (€/year). In addition, the implementation of maps using a Geographical Information System (GIS) has demonstrated a better optimization of the system. Finally, it was highlighted the social utility of the proposed model, because citizens become an active part in the process and self-produce soil fertilisers

Radiative Inflation and Dark Energy

We propose a model based on radiative symmetry breaking that combines inflation with Dark Energy and is consistent with the WMAP 7-year regions. The radiative inflationary potential leads to the prediction of a spectral index 0.955 \lesssim n_S \lesssim 0.967 and a tensor to scalar ratio 0.142 \lesssim r \lesssim 0.186, both consistent with current data but testable by the Planck experiment. The radiative symmetry breaking close to the Planck scale gives rise to a pseudo Nambu-Goldstone boson with a gravitationally suppressed mass which can naturally play the role of a quintessence field responsible for Dark Energy. Finally, we present a possible extra dimensional scenario in which our model could be realised.Comment: 15 pages, 4 figures; v2: references added, appendix added, Section 5 slightly modified; content matches published versio

Experimental analysis on concrete blocks reinforced with Arundo donax fibres

Over the last decades, there has been growing attention in research and development on non-conventional building materials, such as vegetable fibres (e.g., flax, hemp, jute, etc.), to be used as eco-friendly materials in a wide range of applications in civil construction. The main reasons for this interest are related to the specific properties, price, and sustainability of natural fibres, which can be considered ‘green’ building materials. In this article, the tensile strength of a new type of fibre extracted from the stem of the Giant Reed Arundo donax L. has been investigated. First, these fibres, which widely grow in Mediterranean areas but are diffused worldwide as well have been extracted from the outer part of the plant stem. Then, in order to have an initial idea of their influence on the mechanical properties of concrete, some experimental bricks have been prepared, with the addition of different weight percentages of this vegetal fibre. Compression and tensile tests on the whole block have been performed to assess the mechanical properties of these bricks. Hence, the differences between concrete bricks without fibre and those reinforced with different weight percentages of natural fibre have been analysed, assessing their potential applications in bio-architecture

Experimental analysis on concrete blocks reinforced with Arundo Donax fibers.

Over the last decade, there has been a growing attention in research and development on non-conventional building materials and technologies, such as vegetable fibers (e.g., flax; hemp; jute; etc.), to be used as eco-friendly materials in a wide range of applications in civil construction. The main reasons of this interest are related to the specific properties, price and sustainability of natural fibers, which can be considered as “green” building materials. In this article, a new kind of fibers, extracted from stem of the Giant Reed Arundo donax L., has been investigated as a potential reinforcement of construction materials. These fibers, which widely grow in Mediterranean areas, but that are diffused all around the world as well, have been extracted from the outer part of plant stem. Then, some experimental concrete bricks, have been prepared with the addition of different weight percentages of vegetal fiber. To assess the mechanical properties of these bricks, tensile tests on single fiber have been performed, as well as compression tests on the whole block. Hence, the differences between concrete bricks without any fiber and those reinforced with different weight percentages of natural fiber have been analyzed, and their potential applications in bio-architecture have been assessed

Concrete Blocks Reinforced with Arundo donax Natural Fibers with Different Aspect Ratios for Application in Bioarchitecture

In recent decades, the construction industry has advanced in its use of natural green resources, such as vegetable fibers (e.g., flax, hemp, jute, etc.) added in concrete mixtures, to create building materials that are both economically and environmentally sustainable. The pricing, low energy cost, and environmental sustainability of these natural fibers are driving this interest. The quantity of fibers and the ratio of fiber length to its transverse diameter (aspect ratio) are critical characteristics that have a decisive impact on concrete’s mechanical qualities. The influence of the aspect ratio of Arundo donax fibers on the tensile characteristics of concrete blocks was specifically investigated in this study. These fibers were collected from the outer section of the stem of this plant, which grows commonly in Mediterranean locations, but that is also found all over the world. Experiments were carried out on cylindrical concrete blocks with a constant amount of fiber (1 percent by weight) and different aspect ratios: 30, 50, and 70 (mm/mm) respectively, to assess their tensile strength, even when compared with concrete blocks without any fiber addition. Tensile tests on Arundo donax fibers were also conducted, with the aim to contribute to the analysis of their interaction with cementitious matrices, and to assess differences between the various compositions. The results showed a direct impact of the aspect ratio on the final tensile strength of concrete blocks, with higher aspect ratios producing superior tensile properties

GIScience and Historical Cartography for Evaluating Land Use Changes and Resulting Effects on Carbon Balance

Multi-chronological examination of territory using GIScience and historical cartography may reveal a strategic tool for investigating changes in land use and the surrounding landscape structure. In this framework, the soil plays a key role in ecosystem evolution, since it governs all the mechanisms at the basis of vegetal growth, as well as all components of the total environment contributing to the formation of a rural landscape, including the balance of carbon dioxide. The present study was developed using a GIS approach applied to historical maps and aims to assess the environmental impact of land-use change, with particular attention to its effects on agricultural soil and atmospheric carbon dioxide balance. Thanks to a comparison between historical cartographic maps of different periods, this geospatial approach has enabled the assessment of the evolution of the rural land of the study area in the municipality of Ruoti (Basilicata Region—Southern Italy). This area, indeed, has been affected by deep land-use transformations, mainly caused by agricultural activities, with a resulting impact on the atmospheric CO2 balance. These transformations have been analyzed and quantified in order to contribute to the understanding on how the changes in land use for agricultural purposes have led to unforeseen changes in the rural landscape, ecosystems and the environment. The results showed that the greatest changes in land use were caused by the abandonment of large rural areas, resulting in the expansion of urban areas, a decrease in orchard and arable land (about less 25%), and an increase in woodland (more than 30%). These changes have resulted in a doubling in soil carbon fixation value. The final results have therefore confirmed that historical cartography within a GIS approach may decisively offer information useful for more sustainable agricultural activities, so as to reduce their negative contribution to climate change

Junctions of anyonic Luttinger wires

We present an extended study of anyonic Luttinger liquids wires jointing at a single point. The model on the full line is solved with bosonization and the junction of an arbitrary number of wires is treated imposing boundary conditions that preserve exact solvability in the bosonic language. This allows to reach, in the low momentum regime, some of the critical fixed points found with the electronic boundary conditions. The stability of all the fixed points is discussed.Comment: 16 pages, 2 figures, typos corrected, Refs adde

Adaptable Pulse Compression in φ-OTDR With Direct Digital Synthesis of Probe Waveforms and Rigorously Defined Nonlinear Chirping

Recent research in Phase-Sensitive Optical Time Doman Reflectometry (φ-OTDR) has been focused, among others, on performing spatially resolved measurements with various methods including the use of frequency modulated probes. However, conventional schemes either rely on phase-coded sequences, involve inflexible generation of the probe frequency modulation or mostly employ simple linear frequency modulated (LFM) pulses which suffer from elevated sidelobes introducing degradation in range resolution. In this contribution, we propose and experimentally demonstrate a novel φ-OTDR scheme which employs a readily adaptable Direct Digital Synthesis (DDS) of pulses with custom frequency modulation formats and demonstrate advanced optical pulse compression with a nonlinear frequency modulated (NLFM) waveform containing a complex, rigorously defined modulation law optimized for bandwidth-limited synthesis and sidelobe suppression. The proposed method offers high fidelity chirped waveforms, and when employed in resolving a 50-cm event at ∼1.13 km using a 1.2-μs probe pulse, matched filtering with the DDS-generated NLFM waveform results in a significant reduction in range ambiguity owing to autocorrelation sidelobe suppression of ∼20 dB with no averages and windowing functions, for an improvement of ∼16 dB compared to conventional linear chirping. Experimental results also show that the contribution of autocorrelation sidelobes to the power in the compressed backscattering responses around localized events is suppressed by up to ∼18 dB when advanced pulse compression with an optical NLFM pulse is employed