12,278 research outputs found
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 10Â 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 10Â 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 â—¦C and 22 â—¦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 â—¦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
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