Quantum Hertz entropy increase in a quenched spin chain

The classical Hertz entropy is the logarithm of the volume of phase space bounded by the constant energy surface; its quantum counterpart, the quantum Hertz entropy, is $\hat S = k_B \ln \hat N$, where the quantum operator $\hat N$ specifies the number of states with energy below a given energy eigenstate. It has been recently proved that, when an isolated quantum mechanical system is driven out of equilibrium by an external driving, the change in the expectation of its quantum Hertz entropy cannot be negative, and is null for adiabatic driving. This is in full agreement with the Clausius principle. Here we test the behavior of the expectation of the quantum Hertz entropy in the case when two identical XY spin chains initially at different temperatures are quenched into a single XY chain. We observed no quantum Hertz entropy decrease. This finding further supports the statement that the quantum Hertz entropy is a proper entropy for isolated quantum systems. We further quantify how far the quenched chain is from thermal equilibrium and the temperature of the closest equilibrium.Comment: 9 pages, 5 figure

Fluctuation theorems for continuously monitored quantum fluxes

It is shown that quantum fluctuation theorems remain unaffected if measurements of any kind and number of observables are performed during the action of a force protocol. That is, although the backward and forward probabilities entering the fluctuation theorems are both altered by these measurements, their ratio remains unchanged. This observation allows to describe the measurement of fluxes through interfaces and, in this way, to bridge the gap between the current theory, based on only two measurements performed at the beginning and end of the protocol, and experiments that are based on continuous monitoring.Comment: 4 pages, 1 figure. Accepted in Physical Review Letter

Work statistics, irreversible heat and correlations build-up in joining two spin chains

We investigate the influences of quantum many-body effects, such as criticality and the existence of factorisation fields, in the thermodynamic cost of establishing a bonding link between two independent quantum spin chains. We provide a physical interpretation of the behavior of irreversible work spent in such process by linking the phenomenology of such quantities to the properties of the spectrum of the systemComment: 9 pages, 8 figures. Contribution to the FQMT13 special volum

Investor sentiment and trading behavior

The aim of this paper is to model trading decisions of financial investors based on a sentiment index. For this purpose, we analyse a dynamical model which includes the sentiment index in the agents' trading behavior. We consider the set up of a Discrete Dynamical System, assuming that in financial markets transactions take place between two groups of fundamentalists that differ in their perception of fundamental value. The proportion of fundamentalists in the two groups is assumed to depend on the sentiment index. The sentiment index used is related to the risk asymmetry index (RAX) enabling us to consider both the variance and the asymmetry of the prediction error between the two groups of fundamentalists. We identify the equilibria of the model and conduct a numerical analysis in order to capture stylized facts documented empirically in the financial literature

Fundamentalists heterogeneity and the role of the sentiment indicator

This paper is a contribution to the literature on the role of the sentiment indices in heterogeneous asset pricing models. We propose a new sentiment index in a financial market where we assume that transactions take place between two groups of fundamentalists that differentiate on the perception of the fundamental value. We assume that the fraction of fundamentalists in the two groups depends on the sentiment index. After studying the analytical properties of the deterministic discrete dynamical system we compare the new index with a previous index introduced in financial literature. For this purpose, by adding stochastic components to the fundamentalist' demands, we measure the performance of our model under different sentiment indices and we test its explanatory power to reproduce the stylized facts of financial data relying on the S&P500 index

Geometric magnetism in open quantum systems

An isolated classical chaotic system, when driven by the slow change of several parameters, responds with two reaction forces: geometric friction and geometric magnetism. By using the theory of quantum fluctuation relations we show that this holds true also for open quantum systems, and provide explicit expressions for those forces in this case. This extends the concept of Berry curvature to the realm of open quantum systems. We illustrate our findings by calculating the geometric magnetism of a damped charged quantum harmonic oscillator transported along a path in physical space in presence of a magnetic field and a thermal environment. We find that in this case the geometric magnetism is unaffected by the presence of the heat bath.Comment: 7 pages. Signs corrected. v3 Accepted in Phys. Rev.

Human Papillomavirus (HPV) Detection in Keratotic Variants of Oral Lichen Planus: Negative Results in a Preliminary Open Study

Background During the last few decades, several researches have been identified HPV genomic sequences in Head Neck Squamous Cell Carcinomas (HNSCC) and in Oral Potentially Malignant Disorders (OPMD) hypothesizing a possible viral etiological role. However, the reported prevalence of HPV-DNA (varying from 0% to 100%) in these lesions result still very discordant. Objective Human papillomavirus (HPV) infection in Oral Lichen Planus (OLP) has been largely investigated but not so extensively with respect to its morphological/histopathological features. The possible influence of hyper-keratosis/parakeratosis in HPV detection for keratotic variants of OLP is here proposed and investigated. Materials and methods A total of 45 individuals with keratotic variants of OLP, clinically and histologically confirmed, were consecutively enrolled, before starting any treatment, and underwent oral brushing for HPV investigation. Viral DNA was extracted from oral brushed cells and HPV DNA researched by the combined use of the INNO-LiPA HPV Genotyping system (Innogenetics) and a PCR assay coupled with genome sequencing. Results None of cytological samples collected resulted HPV-positive. Conclusions In this preliminary study, oral HPV infection, investigated by means of a non-invasive oral sampling procedure and a standardized approach for HPV DNA detection, was not showed in any of the investigated cases. The presence of epithelial hyper-keratosis/parakeratosis in some variants of OLP could be a possible cause of impenetrability and/or difficult detection of the virus. Indeed, in case of keratotic variants of OLP, the possible potential false-negative results of HPV investigation by cytological procedure might be possible; on consequence, an alternative approach for viral detection (i.e. by histological sampling) should be considered

Novel non-invasive adjunctive techniques for early oral cancer diagnosis and oral lesions examination

Oral cancer is a potentially fatal disease with an increasing incidence and an unchanged 5-year mortality rate. Unfortunately, oral cancer is often still late diagnosed, which leads to an increase in the likelihood of functional impairment due to treatment and mortality rate. Definitive diagnosis of oral cancer must be confirmed by scalpel biopsy and histological assessment. However despite its benefits, scalpel biopsy is invasive and it is burdened by a potential morbidity. Furthermore, previous studies have suggested a high degree of intraobserver and interobserver variability regarding the histological evaluation of malignancy. As a consequence, in recent years there has been a growing and persisting demand towards developing new non-invasive, practical diagnostic tools that might facilitate the early detection of oral cancer. The most investigated non-invasive adjunctive techniques are vital staining, autofluorescence, chemiluminescence, narrow band imaging, and exfoliative cytology. Aim of the review is to critically describe these adjunctive aids and, after considering the literature data, an expert opinion on the effectiveness and the possible use of each technique will be provided

Taxonomy and conservation in Higher Plants and Bryophytes in the Mediterranean Area

The Mediterranean Region is among the areas of the world richest in wild and cultivated taxa. Extinctions in the Mediterranean area are bound to have occurred in historical times but they are not documented. The probable and documented cases of plant extinction in specific areas within the Mediterranean are equivalent to 0.25% of total species-by-area records. Species with a large range are more prone to local population size fluctuations and eventual extinction than species with a reduced population. Small islands floras are more prone to extinction than those on large islands and on the mainland. Reliability of our data on Mediterranean plant extinctions is poor. New emphasis on floristic research is needed to boost our deficient knowledge of the Mediterranean flora. A closer collaboration between scholars and amateurs can increase floristic knowledge and also help unravel taxonomic problems