An optimal single-photon source should deterministically deliver one, and only one, photon at a time, with no trade-off between the source’s efficiency and the photon indistinguishability. However, ...all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering, which reduced the efficiency by 50%, fundamentally limiting the scaling of photonic quantum technologies. Here, we overcome this long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities. We present two examples: narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation–collection scheme is designed to minimize the polarization filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60 ± 0.02 (0.56 ± 0.02), a single-photon purity of 0.975 ± 0.005 (0.991 ± 0.003) and an indistinguishability of 0.975 ± 0.006 (0.951 ± 0.005) for the micropillar (Bragg grating) device. Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.
Isostructural metal-insulator transition in VO2 Lee, D; Chung, B; Shi, Y ...
Science (American Association for the Advancement of Science),
11/2018, Letnik:
362, Številka:
6418
Journal Article
Recenzirano
Odprti dostop
Separating structure and electrons in VO2Above 341 kelvin—not far from room temperature—bulk vanadium dioxide (VO2) is a metal. But as soon as the material is cooled below 341 kelvin, VO2 turns into ...an insulator and, at the same time, changes its crystal structure from rutile to monoclinic. Lee et al. studied the peculiar behavior of a heterostructure consisting of a layer of VO2 placed underneath a layer of the same material that has a bit less oxygen. In the VO2 layer, the structural transition occurred at a higher temperature than the metal-insulator transition. In between those two temperatures, VO2 was a metal with a monoclinic structure—a combination that does not occur in the absence of the adjoining oxygen-poor layer.Science, this issue p. 1037The metal-insulator transition in correlated materials is usually coupled to a symmetry-lowering structural phase transition. This coupling not only complicates the understanding of the basic mechanism of this phenomenon but also limits the speed and endurance of prospective electronic devices. We demonstrate an isostructural, purely electronically driven metal-insulator transition in epitaxial heterostructures of an archetypal correlated material, vanadium dioxide. A combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling reveals that an interface interaction suppresses the electronic correlations without changing the crystal structure in this otherwise correlated insulator. This interaction stabilizes a nonequilibrium metallic phase and leads to an isostructural metal-insulator transition. This discovery will provide insights into phase transitions of correlated materials and may aid the design of device functionalities.
Hepatocellular carcinoma (HCC) is the fifth most common cancer with high mortality, due to late diagnosis and limited treatment options. Blood miRNAs, which circulate in a highly stable, cell-free ...form, show promise as novel potential biomarkers for early detection of HCC. Whole miRNome profiling was performed to identify deregulated miRNAs between HCC and normal healthy (NH) volunteers. These deregulated miRNAs were validated in an independent cohort of HCC, NH and chronic Hepatitis B (CHB) volunteers and finally in a 3
cohort comprising NH, CHB, cirrhotic and HCC volunteers to evaluate miRNA changes during disease progression. The associations between circulating miRNAs and liver-damage markers, clinicopathological characteristics and survival outcomes were analysed to identify prognostic markers. Twelve miRNAs are differentially expressed between HCC and NH individuals in all three cohorts. Five upregulated miRNAs (miR-122-5p, miR-125b-5p, miR-885-5p, miR-100-5p and miR-148a-3p) in CHB, cirrhosis and HCC patients are potential biomarkers for CHB infection, while miR-34a-5p can be a biomarker for cirrhosis. Notably, four miRNAs (miR-1972, miR-193a-5p, miR-214-3p and miR-365a-3p) can distinguish HCC from other non-HCC individuals. Six miRNAs are potential prognostic markers for overall survival.
Background
Several studies published mainly from pioneers and early adopters have documented the evolution of minimally invasive hepatectomy (MIH). However, questions remain if these reported ...experiences are applicable and reproducible today. This study examines the changing trends, safety, and outcomes associated with the adoption of MIH based on a contemporary single-institution experience.
Methods
This is a retrospective review of 400 consecutive patients who underwent MIH between 2006 and 2017 of which 360 cases (90%) were performed since 2012. To determine the evolution of MIH, the study population was stratified into four equal groups of 100 patients. Analyses were also performed of predictive factors and outcomes of open conversion.
Results
Four hundred patients underwent MIH of which 379 (94.8%) were totally laparoscopic/robotic. Eighty-eight (22.0%) patients underwent major hepatectomy and 160 (40.0%) had resection of tumors located in the posterosuperior segments. There were 38 (9.5%) open conversions. Comparison across the four groups demonstrated that patients were older, had higher ASA score, and had increased frequency of previous abdominal surgery and repeat liver resections. There was also an increase in the proportion of patients who underwent totally laparoscopic/robotic surgery, major liver resection, resection of ≥ 3 segments, and multiple resections. Comparison of outcomes demonstrated that there was a significant decrease in open conversion rate, longer operation time, and increased use of Pringles maneuver. The presence of cirrhosis and institution experience (1st 100 cases) were independent predictors of open conversion. Patients who required open conversion had significantly increased operation time, blood loss, blood transfusion rate, morbidity, and mortality.
Conclusion
The case volume of MIH performed increased rapidly at our institution over time. Although the indications of MIH expanded to include higher risk patients and more complex hepatectomies, there was a decrease in open conversion rate and no change in other perioperative outcomes.
Background
This study aims to determine the safety and efficacy of laparoscopic repeat liver resection (LRLR) for recurrent hepatocellular carcinoma (rHCC).
Methods
Twenty patients underwent LRLR for ...rHCC between 2015 and 2017. The control groups consisted of 79 open RLR (ORLR) for rHCC and 185 LLR for primary HCC. We undertook propensity score-adjusted analyses (PSA) and 1:1 propensity score matching (PSM) for the comparison of LRLR versus ORLR. Comparison of LRLR versus LLR was done using multivariable regression models with adjustment for clinically relevant covariates.
Results
Twenty patients underwent LRLR with three open conversions (15%). Both PSA and 1:1-PSM demonstrated that LRLR was significantly associated with a shorter stay, superior disease-free survival (DFS) but longer operation time compared to ORLR. Comparison between LRLR versus LLR demonstrated that patients undergoing LRLR were significantly older, had smaller tumors, longer operation time and decreased frequency of Pringle’s maneuver applied. There was no difference in other key perioperative outcomes.
Conclusion
The results of this study demonstrate that in highly selected patients; LRLR for rHCC is feasible and safe. LRLR was associated with a shorter hospitalization but longer operation time compared to ORLR. Moreover, other than a longer operation time, LRLR was associated with similar perioperative outcomes compared to LLR for primary HCC.
An outstanding goal in quantum optics and scalable photonic quantum technology is to develop a source that each time emits one and only one entangled photon pair with simultaneously high entanglement ...fidelity, extraction efficiency, and photon indistinguishability. By coherent two-photon excitation of a single InGaAs quantum dot coupled to a circular Bragg grating bull's-eye cavity with a broadband high Purcell factor of up to 11.3, we generate entangled photon pairs with a state fidelity of 0.90(1), pair generation rate of 0.59(1), pair extraction efficiency of 0.62(6), and photon indistinguishability of 0.90(1) simultaneously. Our work will open up many applications in high-efficiency multiphoton experiments and solid-state quantum repeaters.
The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to ...leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1α (HIF1α), activation of HIF1αtargets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1α a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel–Lindau syndrome.
Background
This study aims to compare the short‐ and long‐term outcomes of patients undergoing minimally invasive liver resection (MILR) versus open liver resection (OLR) for nonrecurrent ...hepatocellular carcinoma (HCC).
Methods
Review of 204 MILR and 755 OLR without previous LR performed between 2005 and 2018. 1:1 coarsened exact matching (CEM) and 1:1 propensity‐score matching (PSM) were performed.
Results
Overall, 190 MILR were well‐matched with 190 OLR by PSM and 86 MILR with 86 OLR by CEM according to patient baseline characteristics. After PSM and CEM, MILR was associated with a significantly longer operation time 230 min (interquartile range IQR, 145–330) vs. 160 min (IQR, 125–210), p < .001 215 min (IQR, 135–295) vs. 153.5 min (120–180), p < .001, shorter postoperative stay 4 days (IQR, 3–6) vs. 6 days (IQR, 5–8), p = .001) 4 days (IQR, 3–5) vs. 6 days (IQR, 5–7), p = .004 and lower postoperative morbidity 40 (21%) vs. 67 (35.5%), p = .003 16 (18.6%) vs. 27 (31.4%), p = .036 compared to OLR. MILR was also associated with a significantly longer median time to recurrence (70 vs. 40.3 months, p = .014) compared to OLR after PSM but not CEM. There was no significant difference in terms of overall survival and recurrence‐free survival.
Conclusion
MILR is associated with superior short‐term postoperative outcomes and with at least equivalent long‐term oncological outcomes compared to OLR for HCC.
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