An exact equilibrium reduced density matrix formulation I: The influence of noise, disorder, and temperature on localization in excitonic systems

An exact method to compute the entire equilibrium reduced density matrix for systems characterized by a system-bath Hamiltonian is presented. The approach is based upon a stochastic unraveling of the influence functional that appears in the imaginary time path integral formalism of quantum statistical mechanics. This method is then applied to study the effects of thermal noise, static disorder, and temperature on the coherence length in excitonic systems. As representative examples of biased and unbiased systems, attention is focused on the well-characterized light harvesting complexes of FMO and LH2, respectively. Due to the bias, FMO is completely localized in the site basis at low temperatures, whereas LH2 is completely delocalized. In the latter, the presence of static disorder leads to a plateau in the coherence length at low temperature that becomes increasingly pronounced with increasing strength of the disorder. The introduction of noise, however, precludes this effect. In biased systems, it is shown that the environment may increase the coherence length, but only decrease that of unbiased systems. Finally it is emphasized that for typical values of the environmental parameters in light harvesting systems, the system and bath are entangled at equilibrium in the single excitation manifold. That is, the density matrix cannot be described as a product state as is often assumed, even at room temperature. The reduced density matrix of LH2 is shown to be in precise agreement with the steady state limit of previous exact quantum dynamics calculations.Comment: 37 pages, 12 figures. To appear in Phys. Rev.

Semiclassical instanton formulation of Marcus-Levich-Jortner theory

Marcus-Levich-Jortner (MLJ) theory is one of the most commonly used methods for including nuclear quantum effects into the calculation of electron-transfer rates and for interpreting experimental data. It divides the molecular problem into a subsystem treated quantum-mechanically by Fermi's golden rule and a solvent bath treated by classical Marcus theory. As an extension of this idea, we here present a "reduced" semiclassical instanton theory, which is a multiscale method for simulating quantum tunnelling of the subsystem in molecular detail in the presence of a harmonic bath. We demonstrate that instanton theory is typically significantly more accurate than the cumulant expansion or the semiclassical Franck-Condon sum, which can give orders-of-magnitude errors and in general do not obey detailed balance. As opposed to MLJ theory, which is based on wavefunctions, instanton theory is based on path integrals and thus does not require solutions of the Schr\"odinger equation, nor even global knowledge of the ground- and excited-state potentials within the subsystem. It can thus be efficiently applied to complex, anharmonic multidimensional subsystems without making further approximations. In addition to predicting accurate rates, instanton theory gives a high level of insight into the reaction mechanism by locating the dominant tunnelling pathway as well as providing information on the reactant and product vibrational states involved in the reaction and the activation energy in the bath similarly to what would be found with MLJ theory.Comment: 21 pages, 4 figure

Strategic argument mapping

Includes bibliographical references (p. 38)

Orchestrating Forest Policy in Italy: Mission Impossible?

In the Italian political and economic agenda the forest sector occupies a marginal role. The forest sector in Italy is characterized by a high institutional fragmentation and centralized decision-making processes dominated by Public Forest Administrations. Public participation in forest policy processes has been implemented since the 1990s at national, regional and local levels in several cases. However, today no significant changes have been observed in the overall governance of the forest sector and stakeholders' involvement in Italian forest policy decision-making is still rather limited. The aims of this paper are to describe the state of forest-related participatory processes in Italy at various levels (national, regional and local) and identify which factors and actors hinder or support the establishment and implementation of participatory forest-related processes in the country. The forest-related participatory processes are analyzed adopting a qualitative-based approach and interpreting interactive, complex and non-linear participatory processes through the lens of panarchy theory

Venezuela: The Shifting Organizational Framework for the Police

Recent political polarization in Venezuela has exacerbated longer term tensions over the organization and control of the police. Additionally, there is ongoing and widespread public dissatisfaction with the nature of policing. The patrimonial and authoritarian nature of much policing and the heterogeneity of training programs and resource provision pose considerable challenges to reform. Nevertheless, today’s police officers are right to wonder who they will be working for, what rank they will have, and what kind of work they will be given in 2018

Hierarchical micro-adaptation of biological structures by mechanical stimuli

Remodeling and other evolving processes such as growth or morphogenesis are key factors in the evolution of biological tissue in response to both external and internal epigenetic stimuli. Based on the description of these processes provided by Taber, 1995 and Humphrey et al., 2002 for three important adaptation processes, remodeling, morphogenesis and growth (positive and negative), we shall consider the latter as the increase/decrease of mass via the increase/decrease of the number or size of cells, leading to a change in the volume of the organ. The work of Rodriguez et al. (1994) used the concept of natural configuration previously introduced by Skalak et al. (1982) to formulate volumetric growth. Later, Humphrey et al. (2002) proposed a constrained-mixture theory where changes in the density and mass of different constituents were taken into account. Many other works about biological growth have been presented in recent years, see e.g. Imatani and Maugin, 2002, Garikipati et al., 2004, Gleason and Humphrey, 2004, Menzel, 2004, Amar et al., 2005, Ganghoffer et al., 2005, Ateshian, 2007, Goriely et al., 2007, Kuhl et al., 2007, Ganghoffer, 2010a, Ganghoffer, 2010b and Goktepe et al., 2010. Morphogenesis is associated to changes in the structure shape (Taber, 1995 and Taber, 2009) while remodeling denotes changes in the tissue microstructure via the reorganization of the existing constituents or the synthesis of new ones with negligible volume change. All these processes involve changes in material properties. Although remodeling and growth can, and usually do, occur simultaneously, there are some cases where these processes develop in a decoupled way. For example, Stopak and Harris (1982) reported some experimental results showing remodeling driven by fibroblasts, with no volume growth. We will assume this scenario in this contribution, focusing exclusively on remodeling processes and on the reorientation of fibered biological structures. It is well known that biological tissue remodels itself when driven by a given stimulus, e.g. mechanical loads such as an increase in blood pressure, or changes in the chemical environment that control the signaling processes and the overall evolution of the tissue. Biological remodeling can occur in any kind of biological tissue. In particular, the study of collagen as the most important substance to be remodeled, in all its types (preferentiallyPeer ReviewedPostprint (author's final draft

Operationalizing the circular city model for naples' city-port: A hybrid development strategy

The city-port context involves a decisive reality for the economic development of territories and nations, capable of significantly influencing the conditions of well-being and quality of life, and of making the Circular City Model (CCM) operational, preserving and enhancing seas and marine resources in a sustainable way. This can be achieved through the construction of appropriate production and consumption models, with attention to relations with the urban and territorial system. This paper presents an adaptive decision-making process for Naples (Italy) commercial port's development strategies, aimed at re-establishing a sustainable city-port relationship and making Circular Economy (CE) principles operative. The approach has aimed at implementing a CCM by operationalizing European recommendations provided within both the Sustainable Development Goals (SDGs) framework-specifically focusing on goals 9, 11 and 12-and the Maritime Spatial Planning European Directive 2014/89, to face conflicts about the overlapping areas of the city-port through multidimensional evaluations' principles and tools. In this perspective, a four-step methodological framework has been structured applying a place-based approach with mixed evaluation methods, eliciting soft and hard knowledge domains, which have been expressed and assessed by a core set of Sustainability Indicators (SI), linked to SDGs. The contribution outcomes have been centred on the assessment of three design alternatives for the East Naples port and the development of a hybrid regeneration scenario consistent with CE and sustainability principles. The structured decision-making process has allowed us to test how an adaptive approach can expand the knowledge base underpinning policy design and decisions to achieve better outcomes and cultivate a broad civic and technical engagement, that can enhance the legitimacy and transparency of policies

INSOLVENCY IN THE CONTEXT OF THE PRESENT FINANCIAL CRISES – A COMPARATIVE ANALYSES

This paper presents the current trends in the view of various national states and their on the application of collective insolvency proceedings, also called bankruptcy procedure in common language, by analysing their main pieces of legal regulation, extremely useful both for specialists as well as for creditors and debtors. The fact is that thanks to this procedure, businesses which are in a state of financial crisis, either actual or upcoming can be placed under court protection from creditors which results in blocking enforcement and increasing interest and penalties, allowing them a new start through a reorganization of their activities. Reorganizaing the activities of insolvent debtors activity may also be in the interest of creditors, if they cannot obtain sufficient repayment through the debtor’s bankruptcy. Thus, requests to open insolvency proceedings by them will appear as a means to preserve their rights and to avoid irreversible deterioration of the situation of the deptor. On the other hand, an aggressive insolvency procedure may be used by creditors as a means of pressure in order to obtain a quick settlement of their receivables from solvent borrowers acting in a state of panic created by the existence of an application to open a bankruptcy procedure. And not least, the paper presents how the situation has seriously deteriorated regarding the criteria allowing businesses to apply for an insolvency procedure and the proper use of the benefits of this procedure.bankruptcy, crises, insolvency, insolvability