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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.

The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little. Past climate changes in Greenland ice were accompanied by large aerosol concentration changes. Here, the authors show that by correcting for transport effects, reliable source changes for biogenic aerosol from North America, sea salt aerosol from the North Atlantic, and dust from East Asian deserts can be derived.

Background: The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are prognostic factors for various types of cancer. In this study, we assessed the association of NLR and PLR with the prognosis of small-cell lung cancer (SCLC) in patients who received the standard treatment. Methods: We retrospectively reviewed patients who were diagnosed with SCLC and treated with platinum-based chemotherapy between July 2006 and October 2013 in Gyeongsang National University Hospital Regional Cancer Center and Changwon Samsung Hospital. Results: In total, 187 patients were evaluated. Compared with low NLR (<4), high NLR (⩾4) at diagnosis was associated with poor performance status, advanced stage, and lower response rate. Median overall survival (OS) and progression-free survival (PFS) were worse in the high-NLR group (high vs low, 11.17 vs 9.20 months, P =0.019 and 6.90 vs 5.49 months, P =0.005, respectively). In contrast, PLR at diagnosis was not associated with OS or PFS ( P =0.467 and P =0.205, respectively). In multivariate analysis, stage, lactate dehydrogenase, and NLR at diagnosis were independent prognostic factors for OS and PFS. Conclusions: NLR is easily measurable and reflects the SCLC prognosis. A future prospective study is warranted to confirm our results.

The Higgs mechanism, i.e., spontaneous symmetry breaking of the quantum vacuum, is a cross-disciplinary principle, universal for understanding dark energy, antimatter and quantum materials, from superconductivity to magnetism. Unlike one-band superconductors (SCs), a conceptually distinct Higgs amplitude mode can arise in multi-band, unconventional superconductors  via strong interband Coulomb interaction, but is yet to be accessed. Here we discover such hybrid Higgs mode and demonstrate its quantum control by light in iron-based high-temperature SCs. Using terahertz (THz) two-pulse coherent spectroscopy, we observe a tunable amplitude mode coherent oscillation of the complex order parameter from coupled lower and upper bands. The nonlinear dependence of the hybrid Higgs mode on the THz driving fields is distinct from any known SC results: we observe a large reversible modulation of resonance strength, yet with a persisting mode frequency. Together with quantum kinetic modeling of a hybrid Higgs mechanism, distinct from charge-density fluctuations and without invoking phonons or disorder, our result provides compelling evidence for a light-controlled coupling between the electron and hole amplitude modes assisted by strong interband quantum entanglement. Such light-control of Higgs hybridization can be extended to probe many-body entanglement and hidden symmetries in other complex systems. A collective excitation called Higgs mode may arise in multi-band superconductors via strong interband interaction, but it is yet to be accessed. Here, the authors observe a tunable coherent amplitude oscillation of the order parameter in Ba(Fe 1− x Co x ) 2 As 2 , suggesting appearance and control of the Higgs mode by light tuning interband interaction.

‘Sudden’ quantum quench and prethermalization have become a cross-cutting theme for discovering emergent states of matter1–4. Yet this remains challenging in electron matter5–9, especially superconductors10–14. The grand question of what is hidden underneath superconductivity (SC)15 appears universal, but poorly understood. Here we reveal a long-lived gapless quantum phase of prethermalized quasiparticles (QPs) after a single-cycle terahertz (THz) quench of a Nb3Sn SC gap. Its conductivity spectra is characterized by a sharp coherent peak and a vanishing scattering rate that decreases almost linearly towards zero frequency, which is most pronounced around the full depletion of the condensate and absent for a high-frequency pump. Above a critical pump threshold, such a QP phase with coherent transport and memory persists as an unusual prethermalization plateau, without relaxation to normal and SC thermal states for an order of magnitude longer than the QP recombination and thermalization times. Switching to this metastable ‘quantum QP fluid’ signals non-thermal quench of coupled SC and charge-density-wave (CDW)-like orders and hints quantum control beneath the SC.

Summary This population-based matched cohort analysis explored the effects of bisphosphonate treatment on acute myocardial infarction (AMI). We found that patients who received bisphosphonate therapy had a lower risk of AMI during a 2-year follow-up period (hazard ratio (HR) = 0.35). Our data support that bisphosphonates may provide protective effects against cardiovascular events. Introduction Although bisphosphonates have been suggested to have anti-atherosclerotic effects in animal models, evidence in human subjects is still conflicting. Therefore, this study aimed to explore the effects of bisphosphonate treatment on AMI using a population-based cohort study. Methods We identified 1,548 patients who received bisphosphonate therapy for osteoporotic fractures and randomly extracted 4,644 subjects with vertebral or hip fractures as a comparison cohort. Each patient was individually tracked for 2 years to identify those who subsequently suffered an AMI. Stratified Cox proportional hazards regressions were performed to assess the effect of bisphosphonate treatment on the risk of AMI. Results Six (0.4 %) of the patients who received bisphosphonate therapy and 49 (1.1 %) of the comparison subjects suffered an AMI during the 2-year follow-up period. The incidence rate of AMI was 1.94 (95 % CI = 0.79–4.03) per 1,000 person-years in patients who received bisphosphonate therapy and 5.28 (95 % CI = 3.95–6.92) per 1,000 person-years in comparison patients. Regression analysis revealed that patients who received bisphosphonate therapy had a lower hazard of AMI during the 2-year follow-up period than comparison patients (HR = 0.37, 95 % CI = 0.16–0.85, p  = 0.020). After censoring cases that died from non-AMI causes and adjusting for both demographic and risk factors, the HR of AMI for patients who received bisphosphonate therapy was 0.35 (95 % CI = 0.14–0.84, p  = 0.020) than that of comparison patients. Conclusions Patients who received bisphosphonate therapy had a lower risk of AMI during the 2-year follow-up period. Our data support that bisphosphonates may provide protective effects against cardiovascular events.

Background: Head and neck squamous cell carcinomas (HNSCCs) display cellular heterogeneity and contain cancer stem cells (CSCs). Sex-determining region Y [SRY]-box (SOX)2 is an important regulator of embryonic stem cell fate and is aberrantly expressed in several types of human tumours. Nonetheless, the role of SOX2 in HNSCC remains unclear. Methods: We created cells ectopically expressing SOX2 from previously established HNSCC cells and examined the cell proliferation, self-renewal capacity, and chemoresistance of these cells compared with control cells. In addition, we knocked down SOX2 in primary spheres obtained from HNSCC tumour tissue and assessed the attenuation of stemness-associated traits in these cells in vitro and in vivo . Furthermore, we examined the clinical relevance of SOX2 expression in HNSCC patients. Results: SOX2 is aberrantly expressed in primary tissue of HNSCC patients but not in healthy tissue. SOX2 expression correlated with tumour recurrence and poor prognosis of HNSCC patients. Ectopic expression of SOX2 induced cell proliferation via cyclin B1 expression and stemness-associated features, such as self-renewal and chemoresistance. In addition, a knockdown of SOX2 in HNSCC CSCs attenuated their self-renewal capacity, chemoresistance (through ABCG2 suppression), invasion capacity (via snail downregulation), and in vivo tumorigenicity. Conclusions: These results suggest that SOX2 may have important roles in the ‘stemness’ and progression of HNSCC. Targeting SOX2-positive tumour cells (CSCs) could be a new therapeutic strategy in HNSCCs.

Objectives: To examine the prevalence of sarcopenia and sarcopenic obesity (SO) as defined by different indices, including appendicular skeletal muscle mass (ASM)/height2, skeletal muscle mass index (SMI) and residuals for Korean adults, and to explore the association between SO and metabolic syndrome. Methods: Our study sample included 526 participants (328 women, 198 men) for whom complete data on body composition were collected using available dual X-ray absorptiometry. Modified National Cholesterol Education Program Adult Treatment Panel III criteria were used to identify the individuals with metabolic syndrome. Results: The prevalence of sarcopenia and SO is higher in older adults. Using two s.d. of ASM/height2 below reference values from young, healthy adults as a definition of sarcopenia, the prevalence of sarcopenia and SO was 6.3% and 1.3% in older (60 years) men and 4.1% and 0.8% in older women, respectively. The prevalence of sarcopenia using the residuals method was 15.4% in older men and 22.3% in older women. In addition, using two s.d. of SMI, the prevalence of sarcopenia and SO was 5.1% and 5.1%, respectively, in older men and 14.2% and 12.5%, respectively, in older women. Among women, SO subjects defined by the SMI had three times the risk of metabolic syndrome (odds ratios (OR)=3.24, 95% confidence interval (CI)=1.21-8.66) and non-sarcopenic obese subjects had approximately twice the risk of metabolic syndrome (OR=2.17, 95% CI=1.22-3.88) compared with normal subjects. Similar trends were observed in men. Conclusion: The prevalence and cutoff values of sarcopenia and SO in the Korean population were evaluated using different methods. Among the different indices of sarcopenia and SO, SO only defined using the SMI was associated with the risk of metabolic syndrome. As the Korean population gets older and more obese, the problematics of SO need to be elucidate.

Molecular quantum magnetism involving an isolated spin state is of particular interest due to the characteristic quantum phenomena underlying spin qubits or molecular spintronics for quantum information devices, as demonstrated in magnetic metal–organic molecular systems, the so-called molecular magnets. Here we report the molecular quantum magnetism realized in an inorganic solid Ba 3 Yb 2 Zn 5 O 11 with spin–orbit coupled pseudospin-½ Yb 3+ ions. The magnetization represents the magnetic quantum values of an isolated Yb 4 tetrahedron with a total (pseudo)spin 0, 1 and 2. Inelastic neutron scattering results reveal that a large Dzyaloshinsky–Moriya interaction originating from strong spin–orbit coupling of Yb 4 f is a key ingredient to explain magnetic excitations of the molecular magnet states. The Dzyaloshinsky–Moriya interaction allows a non-adiabatic quantum transition between avoided crossing energy levels, and also results in unexpected magnetic behaviours in conventional molecular magnets. Molecular magnets may provide fundamental building blocks for future spintronic and quantum information technologies. Here, the authors demonstrate how the Yb 4 tetrahedral components of inorganic materials Ba 3 Yb 2 Zn 5 O 11 behave as isolated molecular magnets.

BackgroundPrevious literature has demonstrated equivalent or improved survival post mitral valve (MV) surgery amongst patients with obesity when compared to their normal-weight counterparts. This relationship is poorly understood and the impact of body mass index (BMI) on cardiac remodeling has not been established.MethodsIn this retrospective, single-center study, we sought to identify the impact that BMI may have on long-term outcomes and cardiac remodeling post-MV repair. Outcomes were compared between patients of varying BMI undergoing MV repair between 2004 and 2018. The primary outcome was mortality and secondary outcomes included stroke, myocardial infarction, reoperation of the MV, rehospitalization, and cardiac remodeling.ResultsA total of 32 underweight, 249 normal weight, 249 overweight, 121 obese, and 50 morbidly obese patients were included in this study. Underweight patients had increased mortality at longest follow-up. Patients with morbid obesity were found to have higher rates of readmission for heart failure. Only underweight patients did not demonstrate a significant reduction in LVEF. Patients with normal weight and overweight had a significant reduction in left atrial size, and patients with obesity had a significant reduction in MV area.ConclusionsAn obesity paradox has been identified in cardiac surgery. While patients with obesity have higher rates of comorbidities preoperatively, their rates of mortality are equivalent or even superior to those with lower BMI. The results of our study confirm this finding with patients of high BMI undergoing MV repair demonstrating equivalent rates of morbidity to their normal BMI counterparts. While the obesity paradox has been relatively consistent in the literature, the understanding of its cause and long-term impacts are not well understood. Further focused investigation is necessary to elucidate the cause of this relationship.