Probing Quantum Optical Excitations with Fast Electrons

Probing optical excitations with nanometer resolution is important for understanding their dynamics and interactions down to the atomic scale. Electron microscopes currently offer the unparalleled ability of rendering spatially-resolved electron spectra with combined meV and sub-nm resolution, while the use of ultrafast optical pulses enables fs temporal resolution and exposure of the electrons to ultraintense confined optical fields. Here, we theoretically investigate fundamental aspects of the interaction of fast electrons with localized optical modes that are made possible by these advances. We use a quantum-optics description of the optical field to predict that the resulting electron spectra strongly depend on the statistics of the sample excitations (bosonic or fermionic) and their population (Fock, coherent, or thermal), whose autocorrelation functions are directly retrieved from the ratios of electron gain intensities. We further explore feasible experimental scenarios to probe the quantum characteristics of the sampled excitations and their populations.Comment: 13 pages, 6 figures, 56 reference

Quantum erasure of decoherence

We consider the classical algebra of observables that are diagonal in a given orthonormal basis, and define a complete decoherence process as a completely positive map that asymptotically converts any quantum observable into a diagonal one, while preserving the elements of the classical algebra. For quantum systems in dimension two and three any decoherence process can be undone by collecting classical information from the environment and using such an information to restore the initial system state. As a relevant example, we illustrate the quantum eraser of Scully et al. [Nature 351, 111 (1991)] as an example of environment-assisted correction. Moreover, we present the generalization of the eraser setup for d-dimensional systems, showing that any von Neumann measurement on a system can be undone by a complementary measurement on the environment.Comment: 10 pages, 1 figur

Endoscopic scores for inflammatory bowel disease in the era of 'mucosal healing'. old problem, new perspectives

The importance of the endoscopic evaluation in inflammatory bowel disease (IBD) management has been recognized for many years. However, the modalities for reporting endoscopic activity represent an ongoing challenge. To address this, several endoscopic scores have been proposed. Very few have been properly validated, and the use of such tools remains sub-optimal and is mainly restricted to clinical trials. In recent years, a growing emphasis of the concept of 'mucosal healing' as a prognostic marker and therapeutic goal has increased the need for a more accurate definition of endoscopic activity in both ulcerative colitis (UC) and Crohn's Disease (CD). In the present review, the evolution of the challenges related to endoscopic scores in IBD has been analyzed, with particular attention paid to the renewed relevance of endoscopic activity in recent years. Currently, despite the growing relevance of endoscopic activity, evaluating this activity in IBD is still a challenge. The implementation of efficacious endoscopic scores and a better definition of the absence of activity (mucosal healing) are needed.The importance of the endoscopic evaluation in inflammatory bowel disease (IBD) management has been recognized for many years. However, the modalities for reporting endoscopic activity represent an ongoing challenge. To address this, several endoscopic scores have been proposed. Very few have been properly validated, and the use of such tools remains sub-optimal and is mainly restricted to clinical trials. In recent years, a growing emphasis of the concept of 'mucosal healing' as a prognostic marker and therapeutic goal has increased the need for a more accurate definition of endoscopic activity in both ulcerative colitis (UC) and Crohn's Disease (CD). In the present review, the evolution of the challenges related to endoscopic scores in IBD has been analyzed, with particular attention paid to the renewed relevance of endoscopic activity in recent years. Currently, despite the growing relevance of endoscopic activity, evaluating this activity in IBD is still a challenge. The implementation of efficacious endoscopic scores and a better definition of the absence of activity (mucosal healing) are needed

Pistil transcriptome analysis to disclose genes and gene products related to aposporous apomixis in Hypericum perforatum L.

Unlike sexual reproduction, apomixis encompasses a number of reproductive strategies,which permit maternal genome inheritance without genetic recombination and syngamy. The key biological features of apomixis are the circumvention of meiosis (i.e., apomeiosis),the differentiation of unreduced embryo sacs and egg cells, and their autonomous development in functional embryos through parthenogenesis, and the formation of viable endosperm either via fertilization-independent means or following fertilization with a sperm cell. Despite the importance of apomixis for breeding of crop plants and although much research has been conducted to study this process, the genetic control of apomixis is still not well understood. Hypericum perforatum is becoming an attractive model system for the study of aposporous apomixis. Here we report results from a global gene expression analysis of H. perforatum pistils collected from sexual and aposporous plant accessions for the purpose of identifying genes, biological processes and molecular functions associated with the aposporous apomixis pathway. Across two developmental stages corresponding to the expression of aposporous apomeiosis and parthenogenesis in ovules, a total of 224 and 973 unigenes were found to be significantly up- and down-regulated with a fold change >= 2 in at least one comparison, respectively.Differentially expressed genes were enriched for multiple gene ontology (GO) terms,including cell cycle, DNA metabolic process, and single-organism cellular process. For molecular functions, the highest scores were recorded for GO terms associated withDNA binding, DNA (cytosine-5-)-methyltransferase activity and heterocyclic compound binding. As deregulation of single components of the sexual developmental pathway is believed to be a trigger of the apomictic reproductive program, all genes involved in sporogenesis, gametogenesis and response to hormonal stimuli were analyzed in great detail. Overall, our data suggest that phenotypic expression of apospory is concomitant with the modulation of key genes involved in the sexual reproductive pathway. Furthermore, based on gene annotation and co-expression, we underline a putative role of hormones and key actors playing in the RNA-directed DNA methylation pathway in regulating the developmental changes occurring during aposporous apomixis in H. perforatum

Relaxation process in a regime of quantum chaos

We show that the quantum relaxation process in a classically chaotic open dynamical system is characterized by a quantum relaxation time scale t_q. This scale is much shorter than the Heisenberg time and much larger than the Ehrenfest time: t_q ~ g^alpha where g is the conductance of the system and the exponent alpha is close to 1/2. As a result, quantum and classical decay probabilities remain close up to values P ~ exp(-sqrt(g)) similarly to the case of open disordered systems.Comment: revtex, 5 pages, 4 figures discussion of the relations between time scale t_q and weak localization correction and between dynamical and disordered systems is adde

Kibble-Zurek mechanism and infinitely slow annealing through critical points

We revisit the Kibble-Zurek mechanism by analyzing the dynamics of phase ordering systems during an infinitely slow annealing across a second order phase transition. We elucidate the time and cooling rate dependence of the typical growing length and we use it to predict the number of topological defects left over in the symmetry broken phase as a function of time, both close and far from the critical region. Our results extend the Kibble-Zurek mechanism and reveal its limitations.Comment: 5 pages, 4 fig

Time trend occurrence of duodenal intraepithelial lymphocytosis and celiac disease in an open access endoscopic population

Background: Duodenal intraepithelial lymphocytosis (DIL) is a histological finding characterized by the increase of intraepithelial CD3T-lymphocytes over the normal value without villous atrophy, mostly associated to coeliac disease (CD), Helicobacter pylori (Hp) gastritis and autoimmune diseases. Objective: To assess the occurrence of DIL, CD and Hp gastritis in an endoscopic population over a 13 year period. Methods: From 2003 to 2015 we included adult patients who consecutively underwent oesophago-gastro-duodenoscopy (OGD) with duodenal biopsies assessing the overall and annual occurrence of DIL and CD and the prevalence of Hp gastritis. Results: 160 (2.3%) patients with DIL and 275 (3.9%) with CD were detected among 7001 patients. CD occurrence was higher from 2003 to 2011, while since 2012 DIL occurrence gradually increased significantly compared to CD (p = 0.03). DIL patients were more frequently female (p = 0.0006) and underwent OGD more frequently for dyspepsia (p = 0.002) and for indications not related to gastrointestinal symptoms than CD patients (p = 0.0003). Hp gastritis occurred similarly in CD and DIL patients but the latter had higher frequency of atrophic body gastritis (p = 0.005). Conclusions: DIL is a condition increasing in the general endoscopic population mainly diagnosed by chance. Concomitant gastric histological evaluation is able in one third of DIL patients to identify associated possible causes of DIL, such as Hp and atrophic gastritis

Hepatotoxicity induced by greater celandine (Chelidonium majus L.): a review of the literature

The available literature assessing Chelidonium majus L. (CM) hepatotoxicity potential, and its risk to benefit assessment has been reviewed in this paper. Identification of significant scientific literature was performed via the following research databases: Cochrane Central, Google Scholar, EMBASE, Medline, Science Direct, Scopus, Web of Science, using the following keywords: "Chelidonium majus", "greater celandine", "Hepatotoxicity", "Liver" "Injury", "Toxicity" individually investigated and then again in association. CM named also greater celandine, swallow-wort, or bai-qu-cai (Chinese), has been used for a long time in traditional Chinese medicine and phytotherapy. Its extracts have been claimed to display a wide variety of biological activities: antimicrobial, anti-inflammatory, spasmolytic, antineoplastic, hepatoprotective, and analgesic. Moreover, herbal medicine suggests this plant have numerous additional effects which have not yet been scientifically evaluated, such as antitussive, diuretic, and eye-regenerative. However, despite its claimed hepatoprotective effects, several hepatotoxicity cases have been reported to be probably or highly probably connected with CM exposure, after their evaluation through liver-targeted causality assessment methods. CM hepatotoxicity has been defined as a distinct form of herb-induced liver injury (HILI), due to an idiosyncratic reaction of the metabolic type. This evidence has to be considered in relationship with the absence of considerable benefits of CM therapy. Therefore, the risk to benefit ratio of the use of herbal products containing greater celandine can actually be considered as negative