Charged-phonon theory and Fano effect in the optical spectroscopy of bilayer graphene

Since their discovery, graphene-based systems represent an exceptional playground to explore the emergence of peculiar quantum effects. The present paper focuses on the anomalous appearence of strong infrared phonon resonances in the optical spectroscopy of bilayer graphene and on their pronounced Fano-like asymmetry, both tunable in gated devices. By developing a full microscopic many-body approach for the optical phonon response we explain how both effects can be quantitatively accounted for by the quantum interference of electronic and phononic excitations. We show that the phonon modes borrow a large dipole intensity from the electronic background, the so-called charged-phonon effect, and at the same time interfer with it, leading to a typical Fano response. Our approach allows one to disentangle the correct selection rules that control the relative importance of the two (symmetric and antisymmetric) relevant phonon modes for different values of the doping and/or of the gap in bilayer graphene. Finally, we discuss the extension of the same theoretical scheme to the Raman spectroscopy, to explain the lack of the same features on the Raman phononic spectra. Besides its remarkable success in explaining the existing experimental data in graphene-based systems, the present theoretical approach offers a general scheme for the microscopic understanding of Fano-like features in a wide variety of other systems.Comment: 16 pages, 11 eps figures, PR

Infrared phonon activity in pristine graphite

We study experimentally and theoretically the Fano-shaped phonon peak at 1590 cm$^{-1}$ (0.2 eV) in the in-plane optical conductivity of pristine graphite. We show that the anomalously large spectral weight and the Fano asymmetry of the peak can be qualitatively accounted for by a charged-phonon theory. A crucial role in this context is played by the particle-hole asymmetry of the electronic $\pi$-bands.Comment: 5 pages, 4 figures, 1 tabl

Exploring the direction on the environmental and business performance relationship at the firm level. Lessons from a literature review

The interest of scientists and companies in understanding the business implications of environmental investment is timely; however, a dilemma remains at the firm level: is the environment a “strategic competitive factor”, as in the “Porter point of view”, or is it a “luxury good”, as in the “Wagner point of view”? Our research contributes to this debate through a review of the papers published in scientific journals between 2000 and 2015 that discussed the direction of the relationship between the environmental and business performances of enterprises. The objectives of the research are: (a) to verify if there is an agreement in the scientific literature of the last 15 years about the “Porter–Wagner dilemma” when focusing at the firm level; (b) to underline the prevalent cause and effect directions of the relationship between environmental and business performance; and (c) to investigate the reasons for any disagreements in this topic among the scientists. The results show that the main agreement regards the positive bi-directional relationship, as a virtuous cyclic approach with mutual effects between business and environmental performance; nevertheless, more complex hypotheses emerge, such as nonlinear and/or conditional relationship, that need to be further explored. On the other hand, the Porter–Wagner dilemma remains, and the main reason for the non-agreement among scientists can be due to the several non-homogeneous variables considered in the analyses. Thereafter, as lesson for scientists, the priority is to share univocal methods to measure firms’ environmental and business performances

Effect of Low Birth Weight and Gender on the Need for Adult Psychiatric Hospitalization

Background: Low birth weight is associated with increased rates of psychiatric symptomology in childhood but less is known about the risk of adult psychiatric hospitalization. The primary objective of this study is to examine the relationship between low birth weight (Method: Subjects were born at the Copenhagen University Hospital between 1959 and 1961 (N=9,125). A comprehensive series of measures were obtained for each of the 8,109 surviving and eligible infants at the time of birth. Lifetime psychiatric outcomes were defined as any ICD 10 group F diagnosis (Mental and Behavioral Disorders) or an equivalent ICD 8 diagnosis found in the Danish Central Psychiatric Register by 2007. Bivariate analyses stratified by gender are used to compare the prevalence of psychiatric diagnoses among low birth weight infants. Logistic regression models examine the relationship between low birth weight and alcoholism while adjusting for comorbid psychiatric illness. Results: For males and not for females, low birth weight is associated with an overall increased rate of lifetime psychiatric hospitalization and the specific risk of the development of alcoholism, anxiety, and personality disorders. The association between low birth weight and male alcoholism is retained after sequential logistic regression modeling with low birth weight adjusted for social class and other comorbid psychiatric illness. Conclusions: The results support our previous findings that low birth weight is associated with the increased prevalence of adult psychiatric illness. Selective gender effects suggest the greater likelihood of psychopathology among low birth weight males than females, especially for alcoholism.

A Distributed Intelligenge Paradigm for Knowledge Management

In the last ten years, knowledge management (KM) has become a new fashioned managerial practice. Though KM theories seem to benefit from a "contamination" with cognitive and social sciences, which emphasize a subjective, contextual, and distributed approach to knowledge representation and integration, current technologies support what we may call a "god's eye" paradigm, in which knowledge is viewed as an objective resource. In this paper we discuss artificial intelligence theories and technologies that can support a shift to a new paradigm, called the "distributed intelligence" paradigm, in designing KM systems. Using the evolution of KM systems within Arthur Andersen Consulting as a motivating case study, we propose the framework of it MultiContext Systems as a specification language for distributed intelligence KM systems, and sketch an agent-based architecture as an example of a KM system which embodies the assumptions of the distributed intelligence paradigm

Engineering interaction-induced topological insulators in a 3×3\sqrt{3} \times \sqrt{3} substrate-induced honeycomb superlattice

We consider a system of spinless fermions on the honeycomb lattice with substrate-induced modulated electrostatic potentials tripling the unit cell. The resulting non-Abelian SU(2) gauge fields act cooperatively to realize a quadratic band crossing point (QBCP). Using a combination of mean-field theory and renormalization group techniques, we show that in the QBCP regime, arbitrarily weak repulsive electronic interactions drive the system into the quantum anomalous Hall state. This proves that substrate-induced local voltages are an effective knob to induce the spontaneous formation of a topological quantum phase.Comment: 5 pages, 2 figure

Analytical Chemistry in Food Science

Analytical chemistry presents a traditional and important tool in food science. Its development grew out of governmental food control to verify food composition and wholesomeness. In modern food chemistry, analytical methods are applied to study food constituents, additives and contaminants and their interactions and reactions during processing and storage. Research activities of the Food Chemistry group at ETH comprise investigations on carbohydrates and on chiral flavour compounds. Experimental work in food technology relies on simple analytical methods that are suitable for large series of processing trials. Such methods are used by the Food Technology group to optimize lipid stability of heat sterilized meat and hot-air roasted nuts. Analytical chemistry is taught at ETH in lectures and laboratory courses to all food science majors

Simplified direct water footprint model to support urban water management

Water resources conservation corresponding to urban growth is an increasing challenge for European policy makers. Water footprint (WF) is one of the methods to address this challenge. The objective of this study was to develop a simplified model to assess the WF of direct domestic and non-domestic water use within an urban area and to demonstrate its effectiveness in supporting new urban water management strategies and solutions. The new model was tested on three Central European urban areas with different characteristics i.e., Wroclaw (Poland), Innsbruck (Austria), and Vicenza (Italy). Obtained WFs varied from 291 dm3/(day∙capita) in Wroclaw, 551 dm3/(day∙capita) in Vicezna to 714 dm3/(day∙capita) in Innsbruck. In addition, WF obtained with the proposed model for the city of Vicenza was compared with a more complex approach. The results proved the model to be robust in providing reasonable results using a small amount of data

Consequential life cycle assessment of kraft lignin recovery with chemical recycling

: The recovery of kraft lignin from black liquor allows an increasing of the pulp production of a kraft mill (marginal tonnage) and at the same time provide a valuable material that can be used as energy or chemical feedstock. However, because lignin precipitation is an energy- and material-consuming process, the environmental consequences from a life cycle perspective are under discourse. The aim of this study is to investigate, through the application of consequential life cycle assessment, the potential environmental benefits of kraft lignin recovery and its subsequent use as an energy or chemical feedstock. A newly developed chemical recovery strategy was assessed. The results revealed how the use of lignin as energy feedstock is not environmentally advantageous compared to producing energy directly from the pulp mill's recovery boiler. However, the best results were observed when lignin was used as a chemical feedstock in four applications to replace bitumen, carbon black, phenol, and bisphenol-A

NEW MODEL TO ACHIEVE THE WATER MANAGEMENT AS A COMPETITIVE TOOL FOR INDUSTRIAL PROCESSES

The issue of freshwater use and related impacts is central to international debate. The reason is that freshwater, even though renewable, is a scarce resource with limited availability in a growing number of regions all over the world. The consequent increasing competitiveness on freshwater resources is recognized to affect companies by exposing them to several environmental and market risks. In this contest, businesses clearly showed interest in freshwater management tool so that, in recent year, the scientific community has been working on the development of suitable models and methods. Even though several experiences can be identified in the literature, most significant researches are taking place within the framework of the Life Cycle Assessment, an internationally accepted methodology to assess potential environmental impacts of products, processes and organizations. When focusing on freshwater related issue it is also known as Water Footprint assessment. Current methods, specifically developed to address this issue, present limits in term of transparency, completeness and comprehensiveness. These limitations prevent companies to understand their water environmental hot-spots and therefore to set effective environmental and market performance improvement strategies. The present research focuses on the development of a new model to achieve the freshwater management as a competitive tool for industrial processes. To do so the specific objective of the research was to develop a set of indicators to overcome identified limits and to test its applicability in real case studies. To define the set of indicators, the methodology of the research took into consideration the Life Cycle Assessment framework adopting the criteria agreed within the UNEP-SETAC (United Nation Environmental Program – Society of Environmental Toxicology and Chemistry) Water Use Life Cycle Initiative; to test and discuss its applicability and effectiveness, the methodology of the multiple case studies was adopted. The case studies were selected considering their significance in term of freshwater scarcity and their capability to represent life cycle processes in different locations and therefore to address the issue of regionalization. The four products studied in this research were: a water collection system, an organic oat beverage, an organic strawberry jam and a tomato sauce. The development of the set of indicators is addressed in the first part of the research. To guarantee transparency and effective life cycle impact assessment analysis, the entire environmental impact chain was modelled in order to separately address consumptive and degradative freshwater use. To guarantee completeness and comprehensiveness and therefore to avoid potential environmental burden shifting, a so called water footprint profile covering accepted freshwater related impact methods, was created. The applicability and effectiveness of the proposed set of indicators is presented in the second part of this work. The four case studies were conducted according to the Life Cycle Assessment stages. Results of the applicability of the proposed set of indicators highlighted the importance of regionalization and comprehensiveness and allowed to understand the importance of considering degradative and consumptive freshwater use separately. It was in fact possible to define environmental impact reduction strategies in each of the case studies presented. The research activities were carried out at the Department of Industrial Engineering (Dipartimento di Ingegneria Industriale-DII) at the University of Padova (Italy) and at the Golisano Institute for Sustainability of the Rochester Institute of Technology (New York State –USA). The results of the research activities are summarized in 5 chapters. Chapter 1 includes an introduction of the issue of freshwater scarcity and presents the evolution of models to address freshwater use and related impacts starting from the virtual water assessment to the most recent development within the Life Cycle Assessment framework. Limits of current models and methods are presented. Objective and structure of the research are also described. Chapter 2 reports on materials and methods used in the present research, from the description of the general framework of Life Cycle Assessment studies to the specific criteria used in the indicators definition. Set of developed indicators is therefore presented by specifying procedures for their application and describing the solutions adopted to conform to internationally accepted requirements (such as ISO 14046). Chapter 3 presents the results of the application of the identified set of indicators in four different case studies. To identify potential strategies for companies and to test the effectiveness of the proposed set of indicators, a sensitivity analysis on results is performed. Chapter 4 presents the discussion on results with reference to published literature, the UNEP-SETAC Water Use Life Cycle Initiative criteria, the ISO 14046 principles and objectives of the research. Chapter 5 reports on the conclusion and perspectives for future research