On Favorable Thermal Fields for Detached Bridgman Growth

The thermal fields of two Bridgman-like configurations, representative of real systems used in prior experiments for the detached growth of CdTe and Ge crystals, are studied. These detailed heat transfer computations are performed using the CrysMAS code and expand upon our previous analyses [14] that posited a new mechanism involving the thermal field and meniscus position to explain stable conditions for dewetted Bridgman growth. Computational results indicate that heat transfer conditions that led to successful detached growth in both of these systems are in accordance with our prior assertion, namely that the prevention of crystal reattachment to the crucible wall requires the avoidance of any undercooling of the melt meniscus during the growth run. Significantly, relatively simple process modifications that promote favorable thermal conditions for detached growth may overcome detrimental factors associated with meniscus shape and crucible wetting. Thus, these ideas may be important to advance the practice of detached growth for many materials

Strongly correlated photons on a chip

Optical non-linearities at the single-photon level are key ingredients for future photonic quantum technologies. Prime candidates for the realization of strong photon-photon interactions necessary for implementing quantum information processing tasks as well as for studying strongly correlated photons in an integrated photonic device setting are quantum dots embedded in photonic crystal nanocavities. Here, we report strong quantum correlations between photons on picosecond timescales. We observe (a) photon antibunching upon resonant excitation of the lowest-energy polariton state, proving that the first cavity photon blocks the subsequent injection events, and (b) photon bunching when the laser field is in two-photon resonance with the polariton eigenstates of the second Jaynes-Cummings manifold, demonstrating that two photons at this color are more likely to be injected into the cavity jointly, than they would otherwise. Together,these results demonstrate unprecedented strong single-photon non-linearities, paving the way for realizing a single-photon transistor or a quantum optical Josephson interferometer

Higher-order mean-field theory of chiral waveguide QED

Waveguide QED with cold atoms provides a potent platform for the study of non-equilibrium, many-body, and open-system quantum dynamics. Even with weak coupling and strong photon loss, the collective enhancement of light-atom interactions leads to strong correlations of photons arising in transmission, as shown in recent experiments. Here we apply an improved mean-field theory based on higher-order cumulant expansions to describe the experimentally relevant, but theoretically elusive, regime of weak coupling and strong driving of large ensembles. We determine the transmitted power, squeezing spectra and the degree of second-order coherence, and systematically check the convergence of the results by comparing expansions that truncate cumulants of few-particle correlations at increasing order. This reveals the important role of many-body and long-range correlations between atoms in steady state. Our approach allows to quantify the trade-off between anti-bunching and output power in previously inaccessible parameter regimes. Calculated squeezing spectra show good agreement with measured data, as we present here.Comment: 16+9 pages, 9+2 figure

Functional improvement following direct interventional leaflet repair of severe tricuspid regurgitation

AIMS: Several new percutaneous tricuspid repair systems have recently been introduced as new treatment options for severe tricuspid regurgitation (TR). Clinical improvement following percutaneous tricuspid valve leaflet repair has been demonstrated by recent studies. A possible impact on exercise capacity has not yet been reported. METHODS AND RESULTS: Eleven patients with at least severe TR and successful tricuspid leaflet repair using the PASCAL Ace implant at our cardiology department were included in this analysis. All patients suffered from symptomatic right‐sided heart failure with compromised exercise capacity. Cardiopulmonary exercise testing (CPET), clinical, laboratory, and echocardiographic parameters were assessed at baseline and 3 months follow‐up. The primary endpoint was the change in maximal oxygen consumption [VO(2) max (mL/(min*kg))] at 3 months follow‐up. Secondary endpoints included improvement in TR, cardiac biomarkers, and other clinical outcomes. TR severity at 3 months follow‐up post‐PASCAL Ace implantation was significantly lower than at baseline (P = 0.004). Cardiac biomarkers including high‐sensitivity troponin T and N‐terminal pro‐brain natriuretic peptide as well as right ventricular diameter improved slightly without reaching statistical significance (P = 0.89, P = 0.32, and P = 0.06, respectively). PASCAL Ace implantation resulted in a significant improvement in cardiopulmonary exercise capacity at 3 months follow‐up compared with baseline. Mean VO(2) max improved from 9.5 ± 2.8 to 11.4 ± 3.4 mL/(min*kg) (P = 0.006), VO(2) max per cent predicted from 42 ± 12% to 50 ± 15% (P = 0.004), peak oxygen uptake from 703 ± 175 to 826 ± 198 mL/min (P = 0.004), and O(2) pulse per cent predicted from 67 ± 21% to 81 ± 25% (P = 0.011). Other CPET‐related outcomes did not show any significant change over time. CONCLUSIONS: In this single‐centre retrospective analysis, direct tricuspid valve leaflet repair using the transcatheter PASCAL Ace implant system was associated with a reduced TR severity and improved cardiopulmonary exercise capacity

Re‐do MitraClip in patients with functional mitral valve regurgitation and advanced heart failure

AIM: Percutaneous mitral valve repair (PMVR) via MitraClip implantation is a therapeutic option for severe mitral regurgitation (MR) in advanced stages of heart failure (HF). However, progressive left ventricular dilation in these patients may lead to recurrent MR after PMVR and consequent re‐do MitraClip implantation. Here, we describe the characteristics and outcomes of this clinical scenario. METHODS AND RESULTS: Patients with systolic HF and functional MR undergoing a re‐do MitraClip procedure were retrospectively analysed. Inclusion criteria were age ≥18 years, technical, device and procedural success at first MitraClip procedure, functional MR and systolic HF with an ejection fraction (EF) of <45%. Seventeen out of 684 patients undergoing PMVR with the MitraClip device at our institution between September 2009 and July 2019 were included. All patients displayed advanced HF with an EF of 20% (±9.9) and highly elevated N‐terminal pro‐brain natriuretic peptide. Technical success of the re‐do MitraClip procedure was 100%, whereas procedural and device success were only achieved in 11 patients (65%). Unsuccessful re‐do procedures were related to lower EF and implantation of more than one clip at initial procedure. However, despite reduction in MR grade and no occurrence of significant mitral stenosis after the procedure, the mortality during 12 months follow‐up remained high (8 of 17; 47%). CONCLUSIONS: In a cohort of patients with advanced HF undergoing PMVR, re‐do MitraClip procedure was feasible, but procedural success was unsatisfactory and morbidity and mortality remained high, possibly reflecting the advanced stage of HF in these patients

Abfall von Sauerstoffsättigung und Blutdruck sowie Anstieg des zentralen Venendrucks im Rahmen eines Mitralklappenclippings bei einer 81-Jährigen

BACKGROUND: Atrial septal defects (ASD) following endovascular mitral valve clipping are potentially hemodynamically relevant complications. Immediate closure with an occluder can represent a safe and effective treatment. CASE SUMMARY: An 81-year-old female patient suffering from severe dyspnea due to previously known severe mitral valve regurgitation was scheduled for elective mitral valve clipping. The clip was successfully implanted. Removal of the transseptal cannula resulted in a sudden drop in oxygen saturation and systolic blood pressure as well as an immediate increase in central venous pressure. An iatrogenic left-right shunt was observed at the atrial level with a relevant shunt volume. Immediate closure using an atrial septal occluder successfully restored the oxygen saturation and hemodynamic parameters. CONCLUSION: An increase in central venous pressure, reduction of systolic blood pressure or oxygen saturation after withdrawal of the transseptal cannula during mitral valve clipping should always be further investigated regarding a possible ASD

Implementation of Web-Based Respondent-Driven Sampling among Men who Have Sex with Men in Vietnam

Objective: Lack of representative data about hidden groups, like men who have sex with men (MSM), hinders an evidence-based response to the HIV epidemics. Respondent-driven sampling (RDS) was developed to overcome sampling challenges in studies of populations like MSM for which sampling frames are absent. Internet-based RDS (webRDS) can potentially circumvent limitations of the original RDS method. We aimed to implement and evaluate webRDS among a hidden population. Methods and Design: This cross-sectional study took place 18 February to 12 April, 2011 among MSM in Vietnam. Inclusion criteria were men, aged 18 and above, who had ever had sex with another man and were living in Vietnam. Participants were invited by an MSM friend, logged in, and answered a survey. Participants could recruit up to four MSM friends. We evaluated the system by its success in generating sustained recruitment and the degree to which the sample compositions stabilized with increasing sample size. Results: Twenty starting participants generated 676 participants over 24 recruitment waves. Analyses did not show evidence of bias due to ineligible participation. Estimated mean age was 22 year and 82% came from the two large metropolitan areas. 32 out of 63 provinces were represented. The median number of sexual partners during the last six months was two. The sample composition stabilized well for 16 out of 17 variables. Conclusion: Results indicate that webRDS could be implemented at a low cost among Internet-using MSM in Vietnam. WebRDS may be a promising method for sampling of Internet-using MSM and other hidden groups. Key words: Respondent-driven sampling, Online sampling, Men who have sex with men, Vietnam, Sexual risk behavio