Radiative properties of a linear chain of coupled qubits

We calculate the radiative properties for a linear dipole-coupled chain of qubits. Using the explicit energy eigenstates of the system, we find the radiation patterns for spontaneous transitions from the one-photon eigenstates to the ground state of the system. We show that depending on the excitation of a specific atom, the radiation tends to be focused either along or perpendicular to the chain. We conclude with a derivation of the total decay rate of the one-photon eigenstates, and find the interesting result that for systems where the photon wavenumber is not much larger than the interatomic spacing, up to 94% of the eigenstates are subradiant, that is, they decay significantly slower than a single atom in isolation.Comment: 20 pages, 11 figure

The no-reflow phenomenon: State of the art

SummaryPrimary percutaneous coronary intervention (PCI) is the best available reperfusion strategy for acute ST-segment elevation myocardial infarction (STEMI), with nearly 95% of occluded coronary vessels being reopened in this setting. Despite re-establishing epicardial coronary vessel patency, primary PCI may fail to restore optimal myocardial reperfusion within the myocardial tissue, a failure at the microvascular level known as no-reflow (NR). NR has been reported to occur in up to 60% of STEMI patients with optimal coronary vessel reperfusion. When it does occur, it significantly attenuates the beneficial effect of reperfusion therapy, leading to poor outcomes. The pathophysiology of NR is complex and incompletely understood. Many phenomena are known to contribute to NR, including leukocyte infiltration, vasoconstriction, activation of inflammatory pathways and cellular oedema. Vascular damage and haemorrhage may also play important roles in the establishment of NR. In this review, we describe the pathophysiological mechanisms of NR and the tools available for diagnosing it. We also describe the microvasculature and the endothelial mechanisms involved in NR, which may provide relevant therapeutic targets for reducing NR and improving the prognosis for patients

The characteristic polynomial of the next-nearest-neighbour qubit chain for single excitations

The characteristic polynomial for a chain of dipole-dipole coupled two-level atoms with nearest-neighbour and next-nearest-neighbour interactions is developed for the study of eigenvalues and eigenvectors for single-photon excitations. We find the exact form of the polynomial in terms of the Chebyshev polynomials of the second kind that is valid for an arbitrary number of atoms and coupling strengths. We then propose a technique for expressing the roots of the polynomial as a power series in the coupling constants. The general properties of the solutions are also explored, to shed some light on the general properties that the exact, analytic form of the energy eigenvalues should have. A method for deriving the eigenvectors of the Hamiltonian is also outlined.Comment: 19 pages, 8 figures; minor correction

Collective Light Emission of a Finite Size Atomic Chain

Radiative properties of collective electronic states in a one dimensional atomic chain are investigated. Radiative corrections are included with emphasize put on the effect of the chain size through the dependence on both the number of atoms and the lattice constant. The damping rates of collective states are calculated in considering radiative effects for different values of the lattice constant relative to the atomic transition wave length. Especially the symmetric state damping rate as a function of the number of the atoms is derived. The emission pattern off a finite linear chain is also presented. The results can be adopted for any chain of active material, e.g., a chain of semiconductor quantum dots or organic molecules on a linear matrix.Comment: 10 pages, 20 figure

The Costs and Benefits of Induced Traffic on the Sydney Harbour Tunnel and Gore Hill Freeway

Statistical analyses have been performed on the effect of the opening of the Sydney Harbour Tunnel (SHT) and Gore Hill Freeway (GHF) on public transport patronage and vehicular usage. The effect of toll increases has also been analysed. Statistically significant estimates have been obtained for the induced traffic and the effects of toll increases and these estimates have provided data for a calculation of consumer surplus gained from the provision of the SHT and GHF. The estimate for consumer surplus has been compared with measured gains calculated from actual changes in travel times, traffic volumes and vehicular speeds after the SHT and GHF opened, and the two measures of benefits were found to be consistent with each other. When external costs of the induced traffic are taken into account, it is found that the benefits gained by the SHT and GHF are outweighed by the external costs in combination with the maintenance and capital costs. It is found that the costs of loss of public transport patronage and congestion costs of induced traffic are significant and cannot be neglected in economic evaluations of future roadworks

Association of Antenatal COVID-19-Related Stress with Postpartum Maternal Mental Health and Negative Affectivity in Infants

IMPORTANCE Antenatal stress is a significant risk factor for poor postpartum mental health. The association of pandemic-related stress with postpartum outcomes among mothers and infants is, however, less well understood. OBJECTIVE To examine the association of antenatal COVID-19-related stress with postpartum maternal mental health and infant outcomes. DESIGN, SETTING, AND PARTICIPANTS This cohort study was conducted among 318 participants in the COVID-19 Risks Across the Lifespan study, which took place in Australia, the UK, and the US. Eligible participants reported being pregnant at the first assessment wave between May 5 and September 30, 2020, and completed a follow-up assessment between October 28, 2021, and April 24, 2022. MAIN OUTCOMES AND MEASURES COVID-19-related stress was assessed with the Pandemic Anxiety Scale (score range, 0-4, with higher scores indicating greater COVID-19-related stress). The 8-item Patient Health Questionnaire (score range, 0-3, with higher scores indicating more frequent symptoms of depression) was used to measure maternal depression at each time point, and the 7-item General Anxiety Disorder scale (score range, 0-3, with higher scores indicating more frequent symptoms of anxiety) was used to measure generalized anxiety at each time point. At follow-up, postpartum distress was assessed with the 10-item Postpartum Distress Measure (score range, 0-3, with higher scores indicating greater postpartum distress), and infant outcomes (negative and positive affectivity and orienting behavior) were captured with the Infant Behavior Questionnaire (score range, 1-7, with higher scores indicating that the infant exhibited that affect/behavior more frequently). RESULTS The study included 318 women (mean [SD] age, 32.0 [4.6] years) from Australia (88 [28%]), the US (94 [30%]), and the UK (136 [43%]). Antenatal COVID-19-related stress was significantly associated with maternal postpartum distress (β = 0.40 [95%CI, 0.28-0.53]), depression (β = 0.32 [95%CI, 0.23-0.41]), and generalized anxiety (β = 0.35 [95%CI, 0.26-0.44]), as well as infant negative affectivity (β = 0.45 [95%CI, 0.14-0.76]). The findings remained consistent across a range of sensitivity analyses. CONCLUSIONS AND RELEVANCE The findings of this cohort study suggest that targeting pandemic-related stressors in the antenatal period may improve maternal and infant outcomes. Pregnant individuals should be classified as a vulnerable group during pandemics and should be considered a public health priority, not only in terms of physical health but also mental health

166 Balloon aortic valvuloplasty in unstable and critically ill patients: analysis of three strategies

AimThanks to improved technology and the advent of transcatheter aortic valve implantation (TAVI), balloon aortic valvuloplasty (BAV) has reappared in the management of high risk patients with severe aortic stenosis in a critical clinical state in three different therapeutic strategies: 1) palliative care [A] 2) bridge to surgery [B] 3) bridge to TAVI [C]. Our main objective was to assess the safety, the effiency and the pertinence of BAV.MethodsThirty six patients with severe aortic stenosis and prohibitive surgical risk (logistic Euroscore>15% or severe commorbidities) underwent 39 BAV: 8 in strategy A, 20 in strategy B, 11 in strategy C. 3 patients underwent a second BAV due to early restenosis.ResultsThere was a significant improvement of the hemodynamic parameters after BAV: the peak to peak transaortic gradient was reduced by 56% (47mmHg vs 30mmHg; p<0.001) and index valve area was increased by 48% (0.35 vs 0.52cm2/m2; p<0.001). There was no severe procedural complication (no death due to procedure, no massive aortic insuffisiency, no tamponade). Two patients (5.1%) needed a pacemaker implantation for postprocedure atrioventricular block and 6 patients (15.4%) had moderate bleeding of the femoral artery site. The mortality and follow up for the three strategies are summarized in the table.ConclusionBAV is a safe and efficient transient therapeutic strategy for patients with severe aortic stenosis with prohibitive surgical risk. BAV appears to be more pertinent in bridge to surgery or brige to TAVI than in palliative care. For patients in critical clinical state, BAV stabilizes the hemodynamic status and allows the assessment of anatomical selection criteria for TAVIStratégy A(n=8)Stratégy B(n=20)Stratégy C(n=11)Age (mean, min-max)80 (61–94)73 (44–85)81 (60–87)Mean logistic Euroscore (%)4822.644.2Death n (%)6 (75)8 (40)5 (45)Cardiovascular death n (%)4 (50)3 (15)2 (18)Time of occurrence (days, min-max)12 (0–47)66 (0–130)155 (10–316)Aortic valve replacement n (%)-14 (70)-TAVI n (%)--2 (18

Myocardial T1-mapping for early detection of left ventricular myocardial fibrosis in systemic sclerosis

International audiencen.

Determination of the myocardial area at risk after reperfused acute myocardial infarction with different imaging techniques: cardiac magnetic resonance imaging, multidetector computed tomography and histopathological validation

International audiencen.

Cardioprotective effects of shock wave therapy: A cardiac magnetic resonance imaging study on acute ischemia-reperfusion injury

IntroductionCardioprotection strategies remain a new frontier in treating acute myocardial infarction (AMI), aiming at further protect the myocardium from the ischemia-reperfusion damage. Therefore, we aimed at investigating the mechano-transduction effects induced by shock waves (SW) therapy at time of the ischemia reperfusion as a non-invasive cardioprotective innovative approach to trigger healing molecular mechanisms.MethodsWe evaluated the SW therapy effects in an open-chest pig ischemia-reperfusion (IR) model, with quantitative cardiac Magnetic Resonance (MR) imaging performed along the experiments at multiple time points (baseline (B), during ischemia (I), at early reperfusion (ER) (∼15 min), and late reperfusion (LR) (3 h)). AMI was obtained by a left anterior artery temporary occlusion (50 min) in 18 pigs (32 ± 1.9 kg) randomized into SW therapy and control groups. In the SW therapy group, treatment was started at the end of the ischemia period and extended during early reperfusion (600 + 1,200 shots @0.09 J/mm2, f = 5 Hz). The MR protocol included at all time points LV global function assessment, regional strain quantification, native T1 and T2 parametric mapping. Then, after contrast injection (gadolinium), we obtained late gadolinium imaging and extra-cellular volume (ECV) mapping. Before animal sacrifice, Evans blue dye was administrated after re-occlusion for area-at-risk sizing.ResultsDuring ischemia, LVEF decreased in both groups (25 ± 4.8% in controls (p = 0.031), 31.6 ± 3.2% in SW (p = 0.02). After reperfusion, left ventricular ejection fraction (LVEF) remained significantly decreased in controls (39.9 ± 4% at LR vs. 60 ± 5% at baseline (p = 0.02). In the SW group, LVEF increased quickly ER (43.7 ± 11.4% vs. 52.4 ± 8.2%), and further improved at LR (49.4 ± 10.1) (ER vs. LR p = 0.05), close to baseline reference (LR vs. B p = 0.92). Furthermore, there was no significant difference in myocardial relaxation time (i.e. edema) after reperfusion in the intervention group compared to the control group: ΔT1 (MI vs. remote) was increased by 23.2±% for SW vs. +25.2% for the controls, while ΔT2 (MI vs. remote) increased by +24.9% for SW vs. +21.7% for the control group.DiscussionIn conclusion, we showed in an ischemia-reperfusion open-chest swine model that SW therapy, when applied near the relief of 50′ LAD occlusion, led to a nearly immediate cardioprotective effect translating to a reduction in the acute ischemia-reperfusion lesion size and to a significant LV function improvement. These new and promising results related to the multi-targeted effects of SW therapy in IR injury need to be confirmed by further in-vivo studies in close chest models with longitudinal follow-up