Provably Efficient Learning of Phases of Matter via Dissipative Evolutions

The combination of quantum many-body and machine learning techniques has recently proved to be a fertile ground for new developments in quantum computing. Several works have shown that it is possible to classically efficiently predict the expectation values of local observables on all states within a phase of matter using a machine learning algorithm after learning from data obtained from other states in the same phase. However, existing results are restricted to phases of matter such as ground states of gapped Hamiltonians and Gibbs states that exhibit exponential decay of correlations. In this work, we drop this requirement and show how it is possible to learn local expectation values for all states in a phase, where we adopt the Lindbladian phase definition by Coser \& P\'erez-Garc\'ia [Coser \& P\'erez-Garc\'ia, Quantum 3, 174 (2019)], which defines states to be in the same phase if we can drive one to other rapidly with a local Lindbladian. This definition encompasses the better-known Hamiltonian definition of phase of matter for gapped ground state phases, and further applies to any family of states connected by short unitary circuits, as well as non-equilibrium phases of matter, and those stable under external dissipative interactions. Under this definition, we show that $N = O(\log(n/\delta)2^{polylog(1/\epsilon)})$ samples suffice to learn local expectation values within a phase for a system with $n$ qubits, to error $\epsilon$ with failure probability $\delta$. This sample complexity is comparable to previous results on learning gapped and thermal phases, and it encompasses previous results of this nature in a unified way. Furthermore, we also show that we can learn families of states which go beyond the Lindbladian definition of phase, and we derive bounds on the sample complexity which are dependent on the mixing time between states under a Lindbladian evolution.Comment: 19 pages, 3 figures, 21 page appendi

Exercise respiratory cycle time components in patients with emphysema

Background: We have recently demonstrated that in patients with COPD the severity of emphysema (E) measured by high resolution computed tomography (HRCT) correlated with: ratio VTpeak/FEV1; VE/VCO2 slope and PETCO2 values at peak exercise. The aim of this study was to further investigate if exercise respiratory cycle time components correlated with % of E measured by HRCT. Method: Twelve patients (age = 65±8 yrs; FEV1 = 55±17%pred) with moderate to severe E (quantified by lung HRCT as % voxels < −910 HU) were evaluated with incremental cardiopulmonary exercise testing (CPET). Mean inspiratory time (TiM), mean total respiratory cycle time (TtotM), mean expiratory time during exercise (TeM) and mean expiratory time during the last third of exercise (TeM-end), has been calculated. Results: Both TeM and TeM-end had a good linear correlation with % of E (r = 0,61; p = 0,004 and r = 0,63; p = 0,003). Moreover, by dividing the patients in two groups based on the % of E (>50% and <50%), we observed that patients with higher % of E had longer TeM (TeM: 1,72±0,26sec vs 1,34±0,27sec, p = 0,005) and TeM-end. A good linear correlation has been observed also between TeM and PETCO2 and VE/VCO2 (r = 0,64; p = 0,002 and r = 0,7; p = 0,0005). TeM did not correlated with resting lung function values or inspiratory capacity (IC). Conclusion: The data confirm that distinct physiologic response pattern can be detected at CPET in these patients

Distal Reoperations after Repair of Acute Type A Aortic Dissection—Incidence, Causes and Outcomes

Background and Aim of the Study: In patients with acute type A aortic dissection (A-AAD) whether initial repair should include also aortic arch replacement is still debated. We aimed to assess if extensive aortic repair prevents from reoperations patients with A-AAD. Methods: Outcomes after distal reoperation following repair of A-AAD (n = 285; 1977 to 2018) were analysed in 22 of 226 who underwent ascending aorta/hemiarch replacement (Group 1R) and 7 of 59 who had ascending aorta/arch replacement (Group 2R). Results: Distal reoperation was more common in Group 1R (n = 22) than in Group 2R (n = 0) (p &lt; 0.001) while thoracic endovascular stenting was more frequent in Group 2R (7 vs 3, p &lt; 0.001). Indications for reoperation were pseudoaneurysm at distal anastomosis (n = 4, 18%) and progression of aortic dissection (n = 18, 82%) in Group 1R. Indication for thoracic endovascular stenting was progressive aortic dissection in 3 patients of Group 1R and in 6 of Group 2R. Second reoperation was required in 2 patients from Group 1R (2%) during a mean follow-up of 5 years. Median follow-up was 4 years in Group 1R and 7 years in Group 2R (p = 0.36). Hospital mortality was 14% in Group 1R and 0% in Group 2R (p = 0.3). Actuarial survival is 68 ± 10%, and 62 ± 11% for Group 1R and 100% for Group 2R at 5 and 10 years (p = 0.076). Conclusions: Distal reoperations after A-AAD repair have an acceptable mortality. An extensive initial repair has lower rate of reoperation and better mid-term survival and should be indicated especially for young patients in experienced centers

FSHD muscular dystrophy Region Gene 1 binds Suv4-20h1 histone methyltransferase and impairs myogenesis

Facioscapulohumeral Muscular Dystrophy (FSHD) is an autosomal dominant myopathy with a strong epigenetic component. It is associated with deletion of a macrosatellite repeat leading to over-expression of the nearby genes. Among them, we focused on FSHD Region Gene 1 (FRG1) since its over-expression in mice, X. laevis and C. elegans leads to muscular dystrophy-like defects, suggesting that FRG1 plays a relevant role in muscle biology. Here we show that, when overexpressed, FRG1 binds and interferes with the activity of the histone methyltransferase Suv4-20h1 both in mammals and Drosophila. Accordingly, FRG1 over-expression or Suv4-20h1 knockdown inhibits myogenesis. Moreover, Suv4-20h KO mice develop muscular dystrophy signs. Finally, we identify the FRG1/Suv4-20h1 target Eid3 as a novel myogenic inhibitor that contributes to the muscle differentiation defects. Our study suggests a novel role of FRG1 as epigenetic regulator of muscle differentiation and indicates that Suv4-20h1 has a gene-specific function in myogenesis

Efficacy of pulsatile flow perfusion in adult cardiac surgery: Hemodynamic energy and vascular reactivity

Background: The role of pulsatile (PP) versus non-pulsatile (NP) flow during a cardiopulmonary bypass (CPB) is still debated. This study’s aim was to analyze hemodynamic effects, endothelial reactivity and erythrocytes response during a CPB with PP or NP. Methods: Fifty-two patients undergoing an aortic valve replacement were prospectively randomized for surgery with either PP or NP flow. Pulsatility was evaluated in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). Systemic (SVRi) and pulmonary (PVRi) vascular resistances, endothelial markers levels and erythrocyte nitric-oxide synthase (eNOS) activity were collected at different perioperative time-points. Results: In the PP group, the resultant EEP was 7.3% higher than the mean arterial pressure (MAP), which corresponded to 5150 ± 2291 ergs/cm3 of SHE. In the NP group, the EEP and MAP were equal; no SHE was produced. The PP group showed lower SVRi during clamp-time (p = 0.06) and lower PVRi after protamine administration and during first postoperative hours (p = 0.02). Lower SVRi required a higher dosage of norepinephrine in the PP group (p = 0.02). Erythrocyte eNOS activity results were higher in the PP patients (p = 0.04). Renal function was better preserved in the PP group (p = 0.001), whereas other perioperative variables were comparable between the groups. Conclusions: A PP flow during a CPB results in significantly lower SVRi, PVRi and increased eNOS production. The clinical impact of increased perioperative vasopressor requirements in the PP group deserves further evaluation

Is it possible to assess the best mitral valve repair in the individual patient? Preliminary results of a finite element study from magnetic resonance imaging data

ObjectivesFinite element modeling was adopted to quantitatively compare, for the first time and on a patient-specific basis, the biomechanical effects of a broad spectrum of different neochordal implantation techniques for the repair of isolated posterior mitral leaflet prolapse.MethodsCardiac magnetic resonance images were acquired from 4 patients undergoing surgery. A patient-specific 3-dimensional model of the mitral apparatus and the motion of the annulus and papillary muscles were reconstructed. The location and extent of the prolapsing region were confirmed by intraoperative findings, and the mechanical properties of the mitral leaflets, chordae tendineae and expanded polytetrafluoroethylene neochordae were included. Mitral systolic biomechanics was simulated under preoperative conditions and after 5 different neochordal procedures: single neochorda, double neochorda, standard neochordal loop with 3 neochordae of the same length and 2 premeasured loops with 1 common neochordal loop and 3 different branched neochordae arising from it, alternatively one third and two thirds of the entire length.ResultsThe best repair in terms of biomechanics was achieved with a specific neochordal technique in the single patient, according to the location of the prolapsing region. However, all techniques achieved a slight reduction in papillary muscle forces and tension relief in intact native chordae proximal to the prolapsing region. Multiple neochordae implantation improved the repositioning of the prolapsing region below the annular plane and better redistributed mechanical stresses on the leaflet.ConclusionsAlthough applied on a small cohort of patients, systematic biomechanical differences were noticed between neochordal techniques, potentially affecting their short- to long-term clinical outcomes. This study opens the way to patient-specific optimization of neochordal techniques

Zika virus induces FOXG1 nuclear displacement and downregulation in human neural progenitors

Congenital alterations in the levels of the transcription factor Forkhead box g1 (FOXG1) coding gene trigger "FOXG1 syndrome," a spectrum that recapitulates birth defects found in the "congenital Zika syndrome," such as microcephaly and other neurodevelopmental conditions. Here, we report that Zika virus (ZIKV) infection alters FOXG1 nuclear localization and causes its downregulation, thus impairing expression of genes involved in cell replication and apoptosis in several cell models, including human neural progenitor cells. Growth factors, such as EGF and FGF2, and Thr271 residue located in FOXG1 AKT domain, take part in the nuclear displacement and apoptosis protection, respectively. Finally, by progressive deletion of FOXG1 sequence, we identify the C-terminus and the residues 428-481 as critical domains. Collectively, our data suggest a causal mechanism by which ZIKV affects FOXG1, its target genes, cell cycle progression, and survival of human neural progenitors, thus contributing to microcephaly

Surgical management and outcomes in patients with acute type A aortic dissection and cerebral malperfusion

Objective: The study objective was to evaluate the surgical results in patients with acute type A aortic dissection and cerebral malperfusion. Methods: From 2000 to 2019, 234 patients with type A aortic dissection and cerebral malperfusion were stratified into 3 groups: 50 (21%) with syncope (group 1), 152 (65%) with persistent loss of focal neurological function (group 2), and 32 (14%) with coma (group 3). Results were evaluated and compared by univariable and multivariable analyses. Results: Median age was higher in group 1, and incidence of cardiogenic shock was higher in group 3. The femoral artery was the most common cannulation site, whereas the axillary artery was used in 18% of group 1, 30% of group 2, and 25% of group 3 patients (P = .337). Antegrade cerebral perfusion was performed in more than 80% of patients, and ascending aorta/arch replacement was performed in 40% of group 1, 27% of group 2, and 31% of group 3 (P = .21). In-hospital mortality was 18% in group 1, 27% in group 2, and 56% in group 3 (P = .001). Survival at 5 years is 57.0% in group 1, 57.7% in group 2, and 38.7% in group 3 (P = .0005). On multivariable analysis, age, cardiopulmonary bypass time, and group 3 versus group 2 were independent risk factors for mortality, whereas axillary cannulation was a protective factor. Conclusions: Patients with aortic dissection and cerebral malperfusion without preoperative coma showed acceptable mortality, and those with coma had a high in-hospital mortality regardless of the type of brain protection. Overall axillary artery cannulation appeared to be a protective factor