Entanglement production by quantum error correction in the presence of correlated environment

We analyze the effect of a quantum error correcting code on the entanglement of encoded logical qubits in the presence of a dephasing interaction with a correlated environment. Such correlated reservoir introduces entanglement between physical qubits. We show that for short times the quantum error correction interprets such entanglement as errors and suppresses it. However for longer time, although quantum error correction is no longer able to correct errors, it enhances the rate of entanglement production due to the interaction with the environment.Comment: 7 pages, 3 figures, published versio

An efficient flamelet progress-variable method for modeling non-premixed flames in weak electric fields

Combustion stabilization and enhancement of the flammability limits are mandatory objectives to improve nowadays combustion chambers. At this purpose, the use of an electric field in the flame region provides a solution which is, at the same time, easy to implement and effective to modify the flame structure. The present work describes an efficient flamelet progress-variable approach developed to model the fluid dynamics of flames immersed in an electric field. The main feature of this model is that it can use complex ionization mechanisms without increasing the computational cost of the simulation. The model is based on the assumption that the combustion process is not directly influenced by the electric field and has been tested using two chemi-ionization mechanisms of different complexity in order to examine its behavior with and without the presence of heavy anions in the mixture. Using a one- and two-dimensional numerical test cases, the present approach has been able to reproduce all the major aspects encountered when a flame is subject to an imposed electric field and the main effects of the different chemical mechanisms. Moreover, the proposed model is shown to produce a large reduction in the computational cost, being able to shorten the time needed to perform a simulation up to 40 times.Comment: 26 pages, 13 figures, paper accepted for publication on Computers and Fluid

Entanglement detection in hybrid optomechanical systems

We study a device formed by a Bose Einstein condensate (BEC) coupled to the field of a cavity with a moving end-mirror and find a working point such that the mirror-light entanglement is reproduced by the BEC-light quantum correlations. This provides an experimentally viable tool for inferring mirror-light entanglement with only a limited set of assumptions. We prove the existence of tripartite entanglement in the hybrid device, persisting up to temperatures of a few milli-Kelvin, and discuss a scheme to detect it.Comment: 6 pages, 7 figures, published versio

Berry phase for a spin 1/2 in a classical fluctuating field

The effect of fluctuations in the classical control parameters on the Berry phase of a spin 1/2 interacting with a adiabatically cyclically varying magnetic field is analyzed. It is explicitly shown that in the adiabatic limit dephasing is due to fluctuations of the dynamical phase.Comment: 4 pages, 1 figure, published versio

HOW FLEXIBLE CLASSROOM CAN IMPROVE SEAMLESS LEARNING

This paper will describe the way flexible classroom, started at primary school, can effectively promote seamless learning in adulthood. From this point of view, a flexible classroom experience for children can become a toolbox to use in their future to face seamless learning and smart working. This work shows that flexibility and adaptation to change are propaedeutic to improve the scheduling and the selection process of learning spaces and times. To support this research, a questionnaire was filled in by one hundred eighty-three students of the University of Sannio in Benevento, Italy

Should sleeve gastrectomy be considered only as a first step in super obese patients? 5-year results from a single center

Purpose: Sleeve gastrectomy (SG) has been originally conceived as a first step procedure for super obese (SO) patients, but it is currently considered a stand-alone intervention. Medium-term to long-term studies have shown weight regain and risk of de novo gastroesophageal reflux (GERD). The aim of this study was to evaluate outcomes of SG in SO subjects. Materials and Methods: A retrospective analysis of a prospectively maintained database was carried out to find all SO patients who had undergone SG with a minimum follow-up of 5 years. Inclusion criteria were preoperative endoscopy negative for esophagitis and/or hiatal hernia, and no GERD or acid reduction medication before SG. Reflux symptoms were evaluated using a validated questionnaire and endoscopy. Remission rates from comorbidities and percentage of excess body mass index (BMI) loss were recorded. Results: A total of 66 (45 male/21 female) patients were included in our study. Mean preoperative BMI and age were 57.4±5.8 kg/m2 and 32.7±11.2 years, respectively. After 5 years, mean percentage of excess BMI loss was 56.42±27.8, and remission rates from hypertension, diabetes, and dyslipidemia were 33.3%, 5.3%, and 20%, respectively. After 5 years, new-onset GERD occurred in 66.7% of patients and 33.3% were taking acid reduction medication. Endoscopy revealed 12 (18.2%) cases of esophagitis ≥grade A. Conclusions: After 5 years, weight loss in SO patients is satisfactory, but the vast majority of patients is still in class II obesity, and resolution of comorbidities is disappointing. High rates of de novo GERD and esophagitis may occur

Is there an indication left for gastric band? A single center experience on 178 patients with a follow-up of 10 years

Background: Laparoscopic Adjustable Gastric Banding (LAGB) has been widely performed in the past at our university bariatric center. Aim of this study was to retrospectively assess long term outcomes of LAGB at our university hospital, with special regard to non-response (EWL 50), while 38 (21.3%) were non-responders (%EWL < 25), 32 (18%) had an insufficient weight loss (25 < %EWL < 50) and 34 (19.1%) underwent band removal. Among these, 6 (3.4%) were removed for complications and 28 (15.7%) for insufficient weight loss. Weight regain occurred in 38 out of 144 (26.4%) subjects with the band in place at 10 years. Only one case of early vomiting with readmission for medical treatment was recorded. Slippage, erosion/migration and port/tube complications occurred in 4 (2.2%), 2(1.1%) and 9(5%) cases respectively. Conclusion: LAGB is a safe and moderately effective bariatric procedure but it showed disappointing rates of removal, non-response and remission from comorbidities. However, LAGB could still be proposed for selected/motivated patients

Stylish UV-C lamp for disinfecting household objects

In this study, UV-C device proved to be a valuable tool for disinfecting household items and enhancing safety for everyday healt

Wind of change: Better air for microbial environmental control

Background: The COVID19 epidemic highlighted the importance of air in the transmission of pathogens. Air disinfection is one of the key points to reduce the risk of transmission both in the health sector and in public, civil and industrial environments. All bacteria and viruses tested to date can be inactivated by UV-C rays. Laboratory tested UV-C systems are increasingly popular and proposed as effective technologies for air purification; few studies have evaluated their performance in populated indoor environments. The aim of this investigation was to evaluate the effectiveness of a UV-C disinfection system for air in a real working context. Methods: This experimental study was conducted between December 2020 and February 2021 in an office of the Department of Molecular and Developmental Medicine of the University of Siena, Italy. A pre-final version air purifier (Cleaning Air T12), capable of treating 210 m3/h of air, was first tested for its ability to filter particulates and reduce microbial air contamination in the absence of people. Subsequently, the experiments were conducted in the presence of 3–5 subjects who worked for several hours in an office. During the tests, microbiological samples of air were collected in real time, switching the system on and off periodically. Air samples were collected and incubated on Petri dishes at 36 ◦C and 22 ◦C. Statistical analysis was performed with Stata 16 software assuming a significance level of 95%. An interpolating model was identified to describe the dynamics of contamination reduction when the device operates. Results: Preliminary tests showed a significant 62.5% reduction in Colony-Forming Units (CFUs) with 36 ◦C incubation. Reductions in the particulate component were also observed. In the main test, comparison of CFU data, between the device-on phase (90 min) and the subsequent device-off phase (60 min), showed statistically significant increase (p = 0.001) of environmental contamination passing from a mean of 86.6 (65.8–107.4) to 171.1 (143.9–198.3) CFU/m3, that is a rise of about 100%. The interpolating model exhibited a good fit of CFU reduction trend with the device on. Conclusions: The system, which mainly uses UV-C lamps for disinfection, was able to significantly reduce envi- ronmental and human contamination in real time. Experimental tests have shown that as soon as the device is switched off, after at least half an hour of operation, the healthiness of the air decreases drastically within 10 minutes, bringing the airborne microbial contamination (induced by the presence of operators in the environ- ment) to levels even higher than 150% of the last value with the device on. Re-engineering strategies for system improvement were also discusse

Collective decoherence of cold atoms coupled to a Bose-Einstein condensate

We examine the time evolution of cold atoms (impurities) interacting with an environment consisting of a degenerate bosonic quantum gas. The impurity atoms differ from the environment atoms, being of a different species. This allows one to superimpose two independent trapping potentials, each being effective only on one atomic kind, while transparent to the other. When the environment is homogeneous and the impurities are confined in a potential consisting of a set of double wells, the system can be described in terms of an effective spin-boson model, where the occupation of the left or right well of each site represents the two (pseudo)-spin states. The irreversible dynamics of such system is here studied exactly, i.e., not in terms of a Markovian master equation. The dynamics of one and two impurities is remarkably different in respect of the standard decoherence of the spin - boson system. In particular we show: i) the appearance of coherence oscillations, i) the presence of super and sub decoherent states which differ from the standard ones of the spin boson model, and iii) the persistence of coherence in the system at long times. We show that this behaviour is due to the fact that the pseudospins have an internal spatial structure. We argue that collective decoherence also prompts information about the correlation length of the environment. In a one dimensional configuration one can change even stronger the qualitative behaviour of the dephasing just by tuning the interaction of the bath.Comment: 18 pages, 6 figures, two references adde