Non-Markovianity of Gaussian Channels

We introduce a necessary and sufficient criterion for the non-Markovianity of Gaussian quantum dynamical maps based on the violation of divisibility. The criterion is derived by defining a general vectorial representation of the covariance matrix which is then exploited to determine the condition for the complete positivity of partial maps associated to arbitrary time intervals. Such construction does not rely on the Choi-Jamiolkowski representation and does not require optimization over states.Comment: 5 pages, 1 figure. Published versio

Glaucoma and cigarette smoking: a review of narrative reviews

Background: Glaucoma is an optic neuropathy associated with visual field changes for which high intra-ocular pressure is a major risk factor. Emerging research indicates that modifiable factors, among which the cigarette smoke, besides IOP may be associated with the presence of glaucoma. Objective: The objective of the study was to perform a review of narrative reviews to examine on the relationship between cigarette smoking and glaucoma. Methods: The results of all narrative reviews in the scientific literature about glaucoma and tobacco smoking were analyzed. A quality assessment was performed according to an easy and convenient tool for the quality assessment of narrative reviews for systematic reviews (International Narrative Systematic assessment) the INSA tool. Literature searches were performed using PubMed. Results: 20 studies about relation between glaucoma and smoke were collected, no restriction language was applied. 15 of these studies have been excluded. We selected among them 5 reviews. With the INSA tool we measured the quality of the 5 selected narrative reviews. Studies that had a highest score with the INSA tool were two: A. Coleman et al. “Risk Factors for Glaucoma Needing More Attention” and R. Salowe et al. “Primary Open-Angle Glaucoma in Individuals of African Descent: A Review of Risk Factors”. Conclusion: The narrative reviews analyzed underline that there is no definitive association between cigarette smoking

Non-markovian quantum dynamics

2014 - 2015Quantum systems can necessarily be viewed as open systems. As in classical physics, any realistic description of a system must take into account the cou- pling to an environment that strongly in uences the system itself. Since perfect isolation of a quantum system is not feasible and the complete description of the degrees of freedom of the environment is not possible, it is required a description that accounts for these aspects. Furthermore, not all the degrees of freedom are of interest in order to e ectively describe the system. Hence a probabilistic ap- proach to a quantum evolution is most appropriate: the idea is to consider only the degrees of freedom that are useful, thus reducing to a small set the number of variables needed to describe the evolution of the system. In last years the remarkable progress of quantum technologies opened up new perspective in the investigation of the dynamics of open systems; in this sense, particularly relevant are the techniques which allow to control the degrees of freedom of the environment that in uence the system of interest. Till now the attention was focused on the methods to reduce the detrimental e ect on the quantum properties of the system-environment interaction; namely, on the methods allowing to make the system the more isolated as possible. On the other hand, it has been experimentally checked that in situations requiring ef- fective quantum transfer a system-environment coupling can become a resource: an example is provided by e cient quantum-information processing , in which the present thesis is speci cally framed. The question is that a set of approxi- mations usually exploited in describing quantum evolution (collectively known as Markovian approximation) are too strong to carefully manage some quantum phenomena. The aim of this thesis is twofold. On the one hand, the characterization and quanti cation of non-Markovian content for continuous-variable quantum systems; on the other hand, its possible usefulness as a resource in the frame- work of Quantum Information. The attention is focused mainly on the class of Gaussian states and Gaussian channels; this choice is motivated by their exper- imental relevance, and by the advantage to pass from the in nite-dimensional Hilbert space to a nite-dimensional Hilbert space because, in this case, we can exploit the nite-dimensional matrix analysis. However, we consider also some non-Gaussian resources, which are anyway needful for implementing uni- versal quantum computation, an potentially more powerful for all the quantum protocols. [edited by author]XIV n.s

Effects of defects in the XY chain with frustrated boundary conditions

It has been recently proven that new types of bulk, local order can ensue due to frustrated boundary condition, that is, periodic boundary conditions with an odd number of lattice sites and anti-ferromagnetic interactions. For the quantum XY chain in zero external fields, the usual antiferromagnetic order has been found to be replaced either by a mesoscopic ferromagnet or by an incommensurate AFM order. In this work we examine the resilience of these new types of orders against a defect that breaks the translational symmetry of the model. We find that, while a ferromagnetic defect restores the traditional, staggered order, an AFM one stabilizes the incommensurate order. The robustness of the frustrated order to certain kinds of defects paves the way for its experimental observability

Suspensory materials for surgery of blepharoptosis: a systematic review of observational studies

Background Frontalis suspension surgery is considered the procedure of choice in cases of blepharoptosis. Among all the materials used in this type of surgery, ophthalmic and plastic surgeons prefer to use autologous Fascia Lata. However, during years, other autogenous and exogenous materials have been introduced. Objectives The aim of this study was therefore that of systematically reviewing the functional results and the rate of complications of different synthetic materials, as compared to autogenous Fascia Lata. The primary objective was to determine the rates of Successful Surgeries (SSs) of these materials. The secondary objective was to assess the onset of complications. The following materials were investigated: Fascia Lata, Mersilene, polytetrafluoroethylene (PTFE) and Silicon. Data Source and Methods Following the Prisma procedure, on January 30th, 2016 we used the following electronic databases to select the studies: MEDLINE and Scopus. Results The search strategy retrieved 48 publications that met the eligibility criteria of the systematic review. All studies were non-comparative. PTFE (n = 5) showed the best rate of SSs among the materials compared (statistically significant). Surgeries performed with autogenous Fascia Lata (n = 19) had a 87% rate of success those performed with Mersilene (n = 12)had 92% and those performed with Silicon (n = 17)88%. PTFE had the best outcome, with 99% success rate. As for complications, surgeries performed with PTFE had a higher rate of suture infections (1.9%) as compared to Fascia Lata, but lower incidence for all other complications. Conclusions Although most studies were good quality cohort studies, the overall quality of this evidence should be regarded as low due to their non-comparative design. Our data suggest that PTFE seems to be the most valid alternative material for frontalis suspension surgery, with low recurrence rates and good cosmetic and functional results

Long-range entanglement and topological excitations

Topological order comes in different forms, and its classification and detection is an important field of modern research. In this work, we show that the Disconnected Entanglement Entropy, a measure originally introduced to identify topological phases, is also able to unveil the long-range entanglement (LRE) carried by a single, fractionalized excitation. We show this by considering a quantum, delocalized domain wall excitation that can be introduced into a system by inducing topological frustration in an antiferromagnetic spin chain. Furthermore, we study the resilience of LRE against a quantum quench and the introduction of disorder, thus establishing the existence of a phase with topological features despite not being a typical topological order or symmetry-protected one.Comment: Comments welcom

Results of case-control studies supportthe association between contact lens useand Acanthamoeba keratitis

Acanthamoeba keratitis (AK) is ever more frequently reported in industrialized countries. The loss of the corneal surface integrity consequent to secondary microtrauma produced by the use of contact lens (CL) favors the penetration of the parasite into the corneal tissue. A scientific review was performed to investigate the association of CL wear as an Acanthamoeba keratitis (AK) risk factor. A computerized screening of 7834 Medline articles (4623 from PubMed; 3211 from Scopus) used a strict selection criteria of case-control studies involving CL wear and/or trauma. The search yielded five case-control studies published from 1995 to 2012. All studies included showed a statistically significant positive association between AK and CL use, with a combined odds ratio (OR) of 10.21 (95%, confidence intervals [CI]; 3.57-27.64). All studies included showed a statistically significant positive association between AK and CL use, though with differing OR values. Though rare, AK should be held in higher consideration when ophthalmologists are faced with CL users exhibiting simplex-like lesions associated with circular stromal infiltrates and disproportionate ocular pain in respect to the objective clinical picture.Abstract BACKGROUND: Acanthamoeba keratitis (AK) is ever more frequently reported in industrialized countries. The loss of the corneal surface integrity consequent to secondary microtrauma produced by the use of contact lens (CL) favors the penetration of the parasite into the corneal tissue. OBJECTIVES: A scientific review was performed to investigate the association of CL wear as an Acanthamoeba keratitis (AK) risk factor. METHODS: A computerized screening of 7834 Medline articles (4623 from PubMed; 3211 from Scopus) used a strict selection criteria of case-control studies involving CL wear and/or trauma. RESULTS: The search yielded five case-control studies published from 1995 to 2012. All studies included showed a statistically significant positive association between AK and CL use, with a combined odds ratio (OR) of 10.21 (95%, confidence intervals [CI]; 3.57-27.64). STATISTICAL ANALYSIS: All studies included showed a statistically significant positive association between AK