Convergence of the one-dimensional Cahn-Hilliard equation

We consider the Cahn-Hilliard equation in one space dimension with scaling a small parameter \epsilon and a non-convex potential W. In the limit \espilon \to 0, under the assumption that the initial data are energetically well-prepared, we show the convergence to a Stefan problem. The proof is based on variational methods and exploits the gradient flow structure of the Cahn-Hilliard equation.Comment: 23 page

Effects of the booking.com rating system: bringing hotel class into the picture

The purpose of this study is to continue the discussion initiated by Mellinas et al. (2015, 2016) on the effects of the Booking.com rating system and more widely on the use of the OTA as a data source in academic tourism and hospitality research. We enrich and complement the original work by Mellinas et al. (2015) by empirically investigating the effects of the Booking.com rating system on the distribution of hotel ratings for the overall population of hotels located in London over two years. Based on more than 1.2 million online reviews, we show that the overall distribution of hotel scores is significantly left-skewed. Moreover, we find that the degree of skewness is positively associated with hotel class: lower-class hotels exhibit distributions of ratings that are statistically less skewed than higher-class hotels

Assessing the Structure of Protic Ionic Liquids Based on Triethylammonium and Organic Acid Anions

We present a computational analysis of the short-range structure of three protic ionic liquids based on strong organic acids: trifluoracetate, methanesulfonate, and triflate of triethylammonium. Accurate ab initio computations carried out on the gas-phase dimers show that the protonation of triethylamine is spontaneous. We have identified the anion-cation binding motif that is due to the presence of a strong hydrogen bond and to electrostatic interactions. The strength of the hydrogen bond and the magnitude of the binding energy decrease in the order trifluoroacetate ≳ methanesulfonate > triflate. The corresponding simulations of the bulk phases, obtained using a semiempirical evaluation of the interatomic forces, reveal that on short timescales, the state of the three liquids remains highly ionized and that the gas-phase cation-/anion-binding motif is preserved while no other peculiar structural features seem to emerge

Statistical mechanics of inference in epidemic spreading

We investigate the information-theoretical limits of inference tasks in epidemic spreading on graphs in the thermodynamic limit. The typical inference tasks consist in computing observables of the posterior distribution of the epidemic model given observations taken from a ground-truth (sometimes called planted) random trajectory. We can identify two main sources of quenched disorder: the graph ensemble and the planted trajectory. The epidemic dynamics however induces nontrivial long-range correlations among individuals' states on the latter. This results in nonlocal correlated quenched disorder which unfortunately is typically hard to handle. To overcome this difficulty, we divide the dynamical process into two sets of variables: a set of stochastic independent variables (representing transmission delays), plus a set of correlated variables (the infection times) that depend deterministically on the first. Treating the former as quenched variables and the latter as dynamic ones, computing disorder average becomes feasible by means of the replica-symmetric cavity method. We give theoretical predictions on the posterior probability distribution of the trajectory of each individual, conditioned to observations on the state of individuals at given times, focusing on the susceptible infectious (SI) model. In the Bayes-optimal condition, i.e., when true dynamic parameters are known, the inference task is expected to fall in the replica-symmetric regime. We indeed provide predictions for the information theoretic limits of various inference tasks, in form of phase diagrams. We also identify a region, in the Bayes-optimal setting, with strong hints of replica-symmetry breaking. When true parameters are unknown, we show how a maximum-likelihood procedure is able to recover them with mostly unaffected performance

Statistical Mechanics of Inference in Epidemic Spreading

We study the feasibility of inference tasks in epidemic spreading on graphs in the thermodynamic limit. We identify two main sources of disorder which need to be averaged over: the graph ensemble and the set of epidemic individual's trajectories, from which observations are taken with a fixed protocol. The dynamics on the contact graph induces non-trivial long-range correlations among individuals' states. This results in non-local correlated quenched disorder which unfortunately is typically hard to handle. To overcome this difficulty, we divide the dynamical process into two sets of variables: a set of stochastic independent variables (representing the infection delays), plus a set of correlated variables (the infection times) that depend deterministically on the first. Treating the former as quenched variables and the latter as dynamic ones, the disorder average becomes feasible by means of the Replica Symmetric cavity method. We give theoretical predictions on the posterior probability distribution of the trajectory of each individual, conditioned on (partial and noisy) observations on the state of individuals at given times, focusing on the Susceptible Infected (SI) model. In the Bayes-optimal condition, i.e. when true dynamic parameters are known, the inference task is expected to fall in the Replica Symmetric regime. We indeed provide predictions for the information theoretic limits of various inference tasks, in form of phase diagrams. When true parameters are unknown, we show how a maximum-likelihood procedure is able to recover them with mostly unaffected performance

Sirtuins 1–7 expression in human adipose-derived stem cells from subcutaneous and visceral fat depots: influence of obesity and hypoxia

The sirtuin family comprises seven NAD+-dependent deacetylases which control the overall health of organisms through the regulation of pleiotropic metabolic pathways. Sirtuins are important modulators of adipose tissue metabolism and their expression is higher in lean than obese subjects. At present, the role of sirtuins in adipose-derived stem cells has not been investigated yet. Therefore, in this study, we evaluated the expression of the complete panel of sirtuins in adipose-derived stem cells isolated from both subcutaneous and visceral fat of non-obese and obese subjects. We aimed at investigating the influence of obesity on sirtuins' levels, their role in obesity-associated inflammation, and the relationship with the peroxisome proliferator-activated receptor delta, which also plays functions in adipose tissue metabolism. The mRNA levels in the four types of adipose-derived stem cells were evaluated by quantitative polymerase chain reaction, in untreated cells and also after 8 h of hypoxia exposure. Correlations among sirtuins' expression and clinical and molecular parameters were also analyzed. We found that sirtuin1-6 exhibited significant higher mRNA expression in visceral adipose-derived stem cells compared to subcutaneous adipose-derived stem cells of non-obese subjects. Sirtuin1-6 levels were markedly reduced in visceral adipose-derived stem cells of obese patients. Sirtuins' expression in visceral adipose-derived stem cells correlated negatively with body mass index and C-reactive protein and positively with peroxisome proliferator-activated receptor delta. Finally, only in the visceral adipose-derived stem cells of obese patients hypoxia-induced mRNA expression of all of the sirtuins. Our results highlight that sirtuins' levels in adipose-derived stem cells are consistent with protective effects against visceral obesity and inflammation, and suggest a transcriptional mechanism through which acute hypoxia up-regulates sirtuins in the visceral adipose-derived stem cells of obese patients

Online reviews: differences by submission device

This study examines the role played by submission devices (mobile vs. desktop) in online travel reviewing behaviour. We analyse over 1.2 million online reviews from Booking.com and detect the presence and distinctive features of online reviews submitted by mobile devices. Our findings indicate that 1) the share of online reviews submitted by mobile increased at a very high rate over time (higher than the growth rate of those submitted by desktop); 2) there is a systematic and statistically significant difference between the features and distributions of online reviews submitted through mobile devices vs. online reviews submitted through desktops. We raise awareness of the role played by submission devices in online travel behaviour research and present implications for future research

La patria, la festa, la politica. Il cinquantenario dell'unita' d'Italia, tra celebrazioni nazionali e sguardo della Francia (1909-1911).

- The thesis is about the celebrations for the 50th anniversary of Italy's political unity (1909-1911), top moment between the national festivities of the liberal period. The topic is approached gradually: in a first part, by introducing the recent historical analytic tendencies about nation and celebration; then, by observing it from the Italian internal point of view; finally - in a chapter dedicated to the results of an original research - by following the intertwining of French diplomacy and press readings and the main international dynamics which involved the two neighbouring countries in that period