While the breakdown of the perturbation expansion for the many-electron problem has several formal consequences, here we unveil its physical effect: flipping the sign of the effective electronic ...interaction in specific scattering channels. By decomposing local and uniform susceptibilities of the Hubbard model via their spectral representations, we prove how entering the nonperturbative regime causes an enhancement of the charge response, ultimately responsible for the phase-separation instabilities close to the Mott metal-insulator transition. Our analysis opens a new route for understanding phase transitions in the nonperturbative regime and clarifies why attractive effects emerging from a strong repulsion can induce phase separations but not s -wave pairing or charge-density wave instabilities.
Abstract
A large repulsion between particles in a quantum system can lead to their localization, an effect responsible for the Mott insulator phases in strongly correlated materials. In a system with ...multiple orbitals, an orbital-selective Mott insulator can form, where electrons in some orbitals are predicted to localize while others remain itinerant. Here we demonstrate a more general version of this phenomenon by observing flavour-selective localization in an atom-based quantum simulator. Our experiment realizes Fermi–Hubbard models with an SU(3) symmetry that can be broken using a tunable coupling between flavours. We observe an enhancement of the localization associated with a selective Mott transition and the emergence of flavour-dependent correlations. Our realization of flavour-selective Mott physics demonstrates the potential of cold atoms to simulate interacting multicomponent materials such as superconductors and topological insulators.
This brief addresses the model-based control of the air path of diesel engines in terms of an optimal control problem with input constraints which can be solved using model predictive algorithms. A ...multilinear model identified from data and a switched controller design are used to cope with the nonlinearity of the engine. Experimental results on a production engine confirm that the proposed control method strongly improves the dynamics of the air path and enormously reduces the parameterization work if compared with the conventional approach. To obtain improvements in emissions as well, the new controller approach cannot simply be plugged in at the site of the conventional one, but new set points must be determined. After such a redesign, improvements of 50% in terms of nitrogen oxides and of 10% in terms of particulate matter have been recorded without a net consumption increase, the main price being the increased activity of the turbocharger vane and especially of the exhaust gas recirculation valve
This paper addresses the modeling and control of the air path system of diesel engines. The underlying issues are critical for the control of the transient exhaust gas fraction pumped into the ...cylinders, which is known to be a dominant factor to reduce the nitrogen oxides (NO x ) emissions. In this paper, we propose a new approach, based on a data-based grey-box linear parameter varying (LPV) model as well as on the gain scheduled H infin technique for the controller design. The modeling step is shown to lead naturally to a so-called quasi-LPV structure, which also delivers the scheduling variables to be accounted for. Using this information, gain scheduled H infin techniques allow to design a controller which enforces a much better tracking performance than the standard production electronic control unit, while not requiring any calibration work. The performance of the proposed approach is demonstrated by experimental results
Microscopic simulations may bring a better understanding of the response of gaseous detectors. Such simulations are computationally demanding, due to the modelling of the low energy processes and to ...the high segmentation required for the 2D/3D field maps. In MPGD such maps can be much more complex than those of traditional multiwire chambers, due to the heterogeneous materials and more involute geometries, which break the simplifying symmetries featured in the latter. In order to investigate the performance of the triple GEM 2-dimensional tracking chambers being developed for high luminosity experiments with the Super BigBite Spectrometer at Jefferson Laboratory, we have set up a flexible and rather effcient multistep simulation processor based on either ANSYS or GMSH+ELMER for 3D CAD and electrostatic field modelling and then combined to Garfield++. Potential systematic effects from the 3D CAD modellers, the mesh generators and the electrostatic field solvers have been estimated with dedicated simulations; once these effects have been assessed, the results of the multistep approach have been compared to a simplified whole GEM chamber model.
Purpose
This narrative review intends to summarize the most important and relevant data on diagnosis and treatment of pediatric forearm fractures and to describe the characteristics and advantage of ...each therapeutic option.
Methods
We conducted a literature research considering peer-reviewed papers (mainly clinical trials or scientific reviews) using the string “forearm fracture AND epidemiology” or “forearm fracture AND diagnosis or “ forearm fracture AND treatment” or “forearm fracture AND casting” or “forearm fracture AND surgery”. Studies were identified by searching electronic databases (MEDLINE and PubMed) till April 2020 and reference lists of retrieved articles. Only English-language articles were included in the review.
Results
Conservative management with cast immobilization is a safe and successful treatment option in pediatric forearm fractures. Surgical indication is recommended when an acceptable reduction cannot be obtained with closed reduction and casting. Surgical treatment options are intramedullary nail, plating and hybrid fixation.
Conclusions
There is not a unique consensus about fracture management and treatment. Further studies are necessary to create univocal guidelines about optimal treatment, considering new techniques and available technologies.
The objective of this study was to evaluate the frequency, the intensity and the level of moral distress experienced by nurses working in neonatal intensive care units (NICUs).
We conducted a ...cross-sectional questionnaire survey involving 472 nurses working in 15 level III NICUs. Frequency, intensity and level of moral distress was evaluated using a modified version of Moral Distress Scale Neonatal-Pediatric Version. Socio-demographic data were also collected.
Four hundred six nurses completed the study material indicating a low-to-moderate experience of moral distress. The situations receiving the highest scores for frequency, intensity and level of moral distress related to the initiation of extensive life-saving actions and participation to the care of ventilator-dependent child. No difference in the mean scores of moral distress was found according to the socio-demographic characteristics investigated.
The present study provides further insight into the moral distress experienced by nurses working in Italian NICUs.
Fistula-in-ano is one of the most commonly presenting anorectal diseases. Sphincter sparing treatment options should be considered in patients with complex fistulas. Salvecoll-E gel is a native ...collagen deantigenated and purified, non-cross-linked equine dermal extract, with an amino acid composition identical to human collagen.
The multicentric trial study was a prospective, single-arm observational clinical study with the objective to assess the efficacy of Salvecoll-E gel for anal fistula repair in 70 patients. All patients had undergone preliminary surgical treatment consisting of positioning of a draining loosing seton that was maintained for a period of 4–6 weeks. After seton removal, a gentle debridement and washing of the fistula track was performed. The scar tissue was removed from the internal orifice. Internal opening was covered by a side-to side mucosal suture. Salvecoll-E was injected through the external opening into the fistula track, the external opening it has been opened.
Twelve months after surgery, 55 patients demonstrated a clinically healed fistula (78,5%), 15 patients have a recurrence (21,5%). Most of the recurrences were observed in the first 6 months of treatment (13/15, 86.6%). We don't observe any worsening in CCF score. The results obtained at 1 year certainly seem satisfactory and in line with the best results published in literature using mini-invasive techniques.
Salvecoll-E gel is a promising non-invasive technique for conservative treatment of anal fistulas, it's well tolerated by the patients and, in case of recurrence, reinjection or all other known techniques are feasible.
Despite various opinions and healthy controversy on Ozone Therapy (OT), the practices of this therapy have increased worldwide. Main areas of study with consistent scientific outcomes are the topical ...treatment of both disk herniation and periodontal disease. On the other hand, there is a net dissociation of the scientific resonance concerning systemic oxygen/ozone treatments. It is our intention to discuss in logical terms the numerous papers that commendably reported adverse reactions attributable to OT, focusing our attention mainly to the techniques of administration and not to the simple contact of ozone with biological material. The case reports on OT treatments safety concerns discussed on international journals, make it possible to state that most safety issues are secondary to infections or traumatic reactions due to malpractice. Commonly, the molecule of ozone itself is not responsible of severe reactions at the therapeutic modalities. The millions of patients treated so far from the thousands of physicians correctly practicing OT world widely in the last 40 years demonstrate the safety of this simple and cost-effective regenerative medicine tool. The promising therapeutic implications also for the current COVID-19 emergency are a further stimulus to the standardization of this therapeutic resource with multiple application specificities.
The aim of the multicentre study promoted by Nuova FIO is to evaluate the beneficial effects of the systemic Oxygen-Ozone (O2O3) therapy in patients suffering from SARS COV-2 disease in the early ...phases of the disease, before worsening, up to the need of tracheal intubation. The study is based on the rationale on that the systemic oxygen-ozone treatment could be effective, positively influencing the disease evolution and/or being able to mitigate the onset of the cytokine storm syndrome at least partially.
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