Electro-optical sampling of quantum vacuum fluctuations in dispersive dielectrics

Electro-optical sampling has been recently used to perform spectrally-resolved measurements of electromagnetic vacuum fluctuations. In order to understand which information on the ground state of an interacting system can be acquired thanks to this technique, in this paper we will develop the quantum theory of electro-optical sampling in arbitrary dispersive dielectrics. Our theory shows that a measure of the time correlations of the vacuum fluctuations effectively implements an ellipsometry measurement on the quantum vacuum, allowing to access the frequency-dependent dielectric function. We discuss consequences of these results on the possibility to use electro-optical sampling to probe the population of ground-state virtual photons in the ultrastrong light-matter coupling regime

Long-term survival after aortic valve replacement with the Mitroflow bioprosthesis : a comparative study

Background Recent case reports of early structural degeneration of the Mitroflow valve have cast doubts on the suitability of this bioprosthesis, particularly in the smaller sizes, and in younger patients. We studied long-term patient survival, in a comparative study, as a marker of success after aortic valve replacement. Methods Long-term survival in 142 consecutive patients implanted with the Mitroflow valve was compared, using the Kaplan-Meier method, with a control group of 149 patients receiving different bioprostheses. Ninety two percent of patients were over 70 years and the Mitroflow was used preferentially in smaller sizes. Results Long-term survival in patients who received a Mitroflow valve was equivalent to controls. Four documented cases of premature structural valve degeneration (3 Mitroflow, 1 Perimount) required a second intervention. Conclusions The Mitroflow compared favorably with other valves in our practice. Although a few patients required further treatment this had no significant adverse impact on overall survival.peer-reviewe

The impact of dog therapy on nursing students’ heart rates and ability to pay attention in class

In this study we explored if the presence of a therapy dog has an impact on students’ stress and ability to pay attention in class. The students' heart rates were measured when the dog was present and when he was absent. The students were also asked to fill in a questionnaire. results showed no significant difference in the students’ average and maximum heart rates, between the experimental and control group, however the average resting heart rate was lower when the dog was present. The low resting heart rate coupled with written comments from the students in- dicate that the presence of the dog did reduce stress and had a calming effect on the students.peer-reviewe

A hybrid heuristic solving the traveling salesman problem

This paper presents a new hybrid heuristic for solving the Traveling Salesman Problem, The algorithm is designed on the frame of a general optimization procedure which acts upon two steps, iteratively. In first step of the global search, a feasible tour is constructed based on insertion approach. In the second step the feasible tour found at the first step, is improved by a local search optimization procedure. The second part of the paper presents the performances of the proposed heuristic algorithm, on several test instances. The statistical analysis shows the effectiveness of the local search optimization procedure, in the graphical representation.peer-reviewe

Is transfusion in coronary artery surgery a predictor or a cause of reduced long-term survival?

Background Transfusion is common after coronary bypass surgery. Transfused patients present with higher operative risk and an increased hazard ratio for curtailed long-term survival. There is debate as to whether transfusion itself may further exacerbate late mortality. Methods Long-term survival was studied in 2550 survivors following coronary revascularization in this retrospective, observational study. Kaplan-Meier survival curves were constructed to compare all transfused and non-transfused patients, as well as survival in propensity-matched transfused and non-transfused patients. Results Operative mortality was 1.05% (original cohort 2577). Maximum follow-up was 23 years (mean 11.8, median 12.4 years). 34.7% of patients received a transfusion (mean 2 units packed red blood cells). Baseline risk characteristics (age, female gender, small body habitus, risk stratification scoring, diabetes, hypertension and reduced stroke volume) operative parameters (urgency and no internal thoracic graft) as well as post-operative parameters (intensive care, hospital stay and ventilation time) and complications (haemorrhage, intra-aortic balloon, ventricular arrhythmias, prolonged inotropic support, atrial fibrillation, dialysis, doubling of creatinine and resternotomy) were higher in the transfused patients. The long-term survival of these patients was significantly reduced when compared with that of non-transfused patients (log rank test p<0.001). When analyzed as a sole risk factor, transfusion was associated with reduced long-term survival (log rank test p<0.001) but when analyzed collectively with other risk factors, transfusion failed to demonstrate a causative effect (p=0.953). When propensity matched groups were compared (612 transfused versus 1222 non-transfused patients) long-term survival was similar (log rank test p=0.554). Conclusions Transfusion was required in higher risk patients undergoing coronary revascularization. Long-term survival was curtailed in this group but this was due to preoperative risk and not directly to transfusion. Transfusion was a predictor but not a cause of reduced long-term survival.peer-reviewe

The dietary habits of Maltese university students

Objective: The objective of this study was to explore university students’ perceived diet and related health practices and whether these varied by gender, faculty and year of course. It also sought to examine the students’ recommendations on what may help them to engage in a healthier diet. Method: A self-administered questionnaire was completed by a representative sample of 494 undergraduate students stratified by gender and faculty. The questionnaire explored various features of the students’ perceived physical and mental health and lifestyle, including diet, the focus of this paper. Results: Half of the students had only between 1 and 2 servings of fruit and vegetables daily, more than half chose the less healthy food, less than half had a regular healthy breakfast, while one third consumed soft drinks. Female students were consistently more conscious of their diet. The students made various recommendations on how the university may help them to make healthy choices, particularly more availability of healthy food on campus. Conclusions: Despite being a highly educated group, the majority of students did not reach the healthy diet benchmarks explored in the study. Further research is suggested to explain the psychological correlates underlying the dietary habits of Maltese university students.peer-reviewe