Quantum Quenches in Isolated Quantum Glasses out of Equilibrium.

In this work, we address the question of how a closed quantum system thermalizes in the presence of a random external potential. By investigating the quench dynamics of the isolated quantum spherical p-spin model, a paradigmatic model of a mean-field glass, we aim to shed new light on this complex problem. Employing a closed-time Schwinger-Keldysh path integral formalism, we first initialize the system in a random, infinite-temperature configuration and allow it to equilibrate in contact with a thermal bath before switching off the bath and performing a quench. We find evidence that increasing the strength of either the interactions or the quantum fluctuations can act to lower the effective temperature of the isolated system and stabilize glassy behavior.

Boundary Time Crystals.

In this work we introduce boundary time crystals. Here continuous time-translation symmetry breaking occurs only in a macroscopic fraction of a many-body quantum system. After introducing their definition and properties, we analyze in detail a solvable model where an accurate scaling analysis can be performed. The existence of the boundary time crystals is intimately connected to the emergence of a time-periodic steady state in the thermodynamic limit of a many-body open quantum system. We also discuss connections to quantum synchronization.

Patellofemoral Joint Arthroplasty: Our Experience in Isolated Patellofemoral and Bicompartmental Arthritic Knees.

INTRODUCTION: Isolated patellofemoral (PF) arthritis is rare, and there is no complete agreement about the best surgical treatment. The operative treatments are total knee arthroplasty and patellofemoral replacement (PFR). The incidence of many early complications of PF arthroplasty has decreased with the introduction of newer designs. Nowadays, the main cause of revision surgery is the progression of tibiofemoral osteoarthritis. In the past, PF arthroplasty was contraindicated in patients with evidence of osteoarthritis or pain in medial or lateral tibiofemoral compartments. The improvement in implant designs and surgical techniques has allowed the addition of a monocompartmental arthroplasty for the medial or lateral tibiofemoral compartment. In this work, we evaluate our first experience with PF arthroplasty and its combination with unicompartmental knee arthroplasty. MATERIALS AND METHODS: From May 2014 to March 2016, we treated 14 patients. An isolated PF arthroplasty was performed in six knees (five patients), and a combined PF and unicompartmental knee arthroplasty was performed in nine cases. We observed a significant improvement in the clinical and functional Knee Society Scores (KSSs) after surgery in our patients. RESULTS: We obtained good results in our cases both for clinical and functional KSSs. Patellar clunk was recorded in one case. DISCUSSION AND CONCLUSION: We are going toward a new attitude in which partial osteoarthritic changes could be treated with partial resurfacing prosthetic solutions such as unicompartmental, bi-unicompartmental or PFR alone, or unicompartmental combined, which respects the cruciates and achieves maximal bone preservation, which is vital, particularly, for young patients.

Exotic Attractors of the Nonequilibrium Rabi-Hubbard Model.

We explore the phase diagram of the dissipative Rabi-Hubbard model, as could be realized by a Raman-pumping scheme applied to a coupled cavity array. There exist various exotic attractors, including ferroelectric, antiferroelectric, and incommensurate fixed points, as well as regions of persistent oscillations. Many of these features can be understood analytically by truncating to the two lowest lying states of the Rabi model on each site. We also show that these features survive beyond mean field, using matrix product operator simulations.

Evaluation of anterior knee pain in a PS total knee arthroplasty: the role of patella-friendly femoral component and patellar size.

BACKGROUND: Total knee arthroplasty gives excellent objective results. Nevertheless, the subjective findings do not match the normal knee perception: Often, it depends on patellar pain onset. In this study, we analyzed clinical and radiological items that can affect resurfaced patellar tracking, and role of a patella-friendly femoral component and patellar size on patellar pain onset. MATERIALS AND METHODS: Thirty consecutive patients were implanted using the same-cemented posterior-stabilized TKA associated with patella resurfacing. Fifteen patients were implanted using a classical femoral component, while another 15 patients were implanted using a patella-friendly femoral component. The statistical analysis was set to detect a significant difference (p < 0.05) in clinical and radiological outcomes related to several surgical parameters. Clinical and functional outcomes were recorded using the Knee Society Scoring System (KSS) and patellar pain with the Burnett questionnaire. RESULTS: Mean follow-up was 25 months. KSS results were excellent in both groups. Group 2 (patella-friendly femoral model) reached a higher percentage of 100 points in the clinical and functional KSS, but there was no statistical difference. Also, no statistical differences for Burnett Questionnaire results were recorded. We had one case of patellar clunk syndrome in the standard femoral component group and one poor result in the second group. Postoperative radiographic measurements evidenced no statistical differences in both groups. In group 1 (classical femoral component), better significant result (p < 0.05) war recorded at clinical evaluation according to the Knee Society Scoring System (KSS) in case of wider patellar component resurfaced. CONCLUSIONS: The present study reveals no statistically significant difference in the incidence of anterior knee pain between classical and "patella-friendly" femoral components. With the particular type of implant design utilized in this study, when the classical femoral component is used, bigger patellar implant sizes (38 and 41 mm) showed superior clinical outcome.

Phase transition of light in cavity QED lattices.

Systems of strongly interacting atoms and photons, which can be realized wiring up individual cavity QED systems into lattices, are perceived as a new platform for quantum simulation. While sharing important properties with other systems of interacting quantum particles, here we argue that the nature of light-matter interaction gives rise to unique features with no analogs in condensed matter or atomic physics setups. By discussing the physics of a lattice model of delocalized photons coupled locally with two-level systems through the elementary light-matter interaction described by the Rabi model, we argue that the inclusion of counterrotating terms, so far neglected, is crucial to stabilize finite-density quantum phases of correlated photons out of the vacuum, with no need for an artificially engineered chemical potential. We show that the competition between photon delocalization and Rabi nonlinearity drives the system across a novel Z(2) parity symmetry-breaking quantum criticality between two gapped phases that share similarities with the Dicke transition of quantum optics and the Ising critical point of quantum magnetism. We discuss the phase diagram as well as the low-energy excitation spectrum and present analytic estimates for critical quantities.

[The safety and efficacy of systemic salvage thrombolysis in acute myocardial infarct]. / Sicurezza ed efficacia della trombolisi di salvataggio per via sistemica nell'infarto miocardico acuto.

BACKGROUND: Thrombolysis reduces mortality in patients with acute myocardial infarction hospitalized within 6 hours of the symptom onset. Infarctions involving a small area of the myocardium show a lower mortality in comparison to those involving a large area. The aim of this study was to evaluate the safety and efficacy of rescue thrombolysis in patients with large acute myocardial infarction who had failed standard thrombolysis. METHODS: From January 1995 to December 1997, ninety patients (69 males, 21 females, mean age 56.7 +/- 9 years), hospitalized for suspected acute myocardial infarction within 4 hours of the symptom onset, suitable for thrombolysis (first episode), and who experienced pain and showed persistent ST segment elevation 120 min after starting thrombolysis, were randomized (single blind) into two groups: Group A (n = 45) received an additional thrombolytic treatment (rt-PA 50 mg), 10 mg as a bolus plus 40 mg in 60 min; Group B (n = 45) received conventional therapy. Positive non-invasive markers were defined as follows: resolution of chest pain; > 50% reduction in ST segment elevation; double marker of creatine phosphokinase (CPK) and CK-MB activity 2 hours after the start of thrombolysis; occurrence of reperfusion arrhythmias within the first 120 min of thrombolytic therapy. Blood pressure, heart rate and ECG were continuously monitored. Echocardiogram was carried out at entry and before discharge to control ejection fraction and segmental wall motion. Adverse events such as death, reinfarction, recurrent angina, incidence of major and minor bleeding, and emergency bypass surgery or coronary angioplasty were checked. RESULTS: Thirty-five patients (77.7%) showed reperfusion (10-50 min) after the start of additional rt-PA. In patients who did not receive additional thrombolysis, only 12 (26.6%) showed reperfusion 65-115 min after the end of rt-PA infusion. Group A showed an earlier and lower CK and CK-MB peak than Group B (p = 0.0001, p = 0.009, and p = 0.002, respectively). Mortality (n = 16, 17.7%) was higher in Group B (n = 13) than in Group A (n = 3) (28.8 vs 6.6%, p = 0.041). Seven patients from Group A showed non-fatal reinfarction. Angina was observed in 18 (40%) patients from Group A and 3 (6.6%) from Group B (p = 0.006). Ten of these patients underwent urgent coronary angioplasty (9 from Group A and 1 from Group B) and 3 from Group A urgent bypass surgery. Minor bleeding was higher in Group A than in Group B (44.4 vs 15.5%, p = 0.047). A major bleeding was observed in Group A (non-fatal stroke). At predischarge echocardiogram ejection fraction was higher in Group A than in Group B (46 +/- 8 vs 38 +/- 7%, p = 0.0001). CONCLUSIONS: Our data suggest that an additional dose of a thrombolytic drug in patients with unsuccessful thrombolysis is feasible, and the bleeding increase is an acceptable risk in comparison with the advantages obtained from a reduced infarct extension. Rescue thrombolysis could save time and allow mechanical revascularization to be carried out in patients admitted to a hospital without interventional cardiology laboratory or in those who have to be refereed to other hospitals for urgent bypass surgery.

[Comparison of the echo-dobutamine-atropine test and ergometric test in the diagnosis of coronary disease]. / Confronto tra test eco-dobutamina-atropina e test ergometrico nella diagnosi di malattia coronarica.

BACKGROUND: A prospective study has been done on 46 patients with suspected coronary artery disease (CAD). They had no history of myocardial infarction (MI) and a normal basal kinetic echocardiography. This was done in order to evaluate the overall accuracy of dobutamine-atropine stress echocardiography (DAS) compare to exercise stress test (ET) for the diagnosis of CAD. METHODS: All the patients after suspension of coronary therapy, performed a casual sequence with both maximal or symptom limited exercise testing (treadmill-Bruce protocol) and DAS. The dobutamine has been given while monitoring systemic blood pressure, electrocardiography and echocardiography in steps of 10 mcg/kg/min' per 3 min' up to a maximum of 40 mcg/kg/min'. Atropine has been added (0.25-1 mg) in patients who did not reach the theoretical maximal cardiac frequency. The test is considered positive when kinetic segmental left ventricular dysfunction appeared. CAD was defined as 50% luminal area stenosis in at least 1 coronary artery at coronary angiography. RESULTS: Significant CAD was present in 27/46 patients (59%). Compared with ET, DAS had significantly higher sensitivity (59% vs 92%, p = 0.01). The different sensibility between the two tests was higher on these patients with a 1 vessel disease (40% vs 86%, p = 0.02). There were no significant differences in specificity among the two tests (79% vs 84%, respectively). Differences in overall accuracy between ET and DAS were significant (67% vs 89%, p = 0.02). CONCLUSIONS: The results of our study show that the DAS is a safe and feasible technique with high sensibility (especially in patients with single CAD) and specificity. This is a valid alternative to the traditional ET, especially for these patients unable to exercise or these who are poorly motivated to achieve a work load sufficient to make the test interpretable.