Abrupt metal-insulator transition observed in VO2 thin films induced by a switching voltage pulse

An abrupt metal-insulator transition (MIT) was observed in VO2 thin films during the application of a switching voltage pulse to two-terminal devices. Any switching pulse over a threshold voltage for the MIT of 7.1 V enabled the device material to transform efficiently from an insulator to a metal. The characteristics of the transformation were analyzed by considering both the delay time and rise time of the measured current response. The extrapolated switching time of the MIT decreased down to 9 ns as the external load resistance decreased to zero. Observation of the intrinsic switching time of the MIT in the correlated oxide films is impossible because of the inhomogeneity of the material; both the metallic state and an insulating state co-exist in the measurement volume. This indicates that the intrinsic switching time is in the order of less than a nanosecond. The high switching speed might arise from a strong correlation effect (Coulomb repulsion) between the electrons in the material.Comment: 5 pages, 5 figure

A Parallel Routing Algorithm on Circulant Networks Employing the Hamiltonian Circuit Latin Square

Abstract. Double-loop and 2-circulant networks are widely used in the design and implementation of local area networks and parallel processing architectures. In this paper, we investigate the routing of a message on circulant networks, that is a key to the performance of this network. We would like to transmit 2k packets from a source node to a destination node simultaneously along paths on G(n; ±s1,±s2,...,±s k ), where the i th packet will traverse along the i th path (1 ≤ i ≤ 2k). In oder for all packets to arrive at the destination node quickly and securely, the i th path must be node-disjoint from all other paths. For construction of these paths, employing the Hamiltonian Circuit Latin Square(HCLS) we present O(n 2 ) parallel routing algorithm on circulant networks

A New Method for Investigation of the Hair Shaft: Hard X-Ray Microscopy with a 90-nm Spatial Resolution

Various methods have been used to investigate the hair shaft. In the ultrastructural hair field, scanning and transmission electron microscopies are widely used investigative methods, but they have some technical limitations. Recently, X-ray microscopes with sub-micron spatial resolution have emerged as useful instruments because they offer a unique opportunity to observe the interior of an undamaged sample in greater detail. In this report, we examined damaged hair shaft tips using hard X-ray microscopy with a 90 nm spatial resolution. The results of this study suggest that hard X-ray microscopy is an alternative investigative method for hair morphology studies

Observation of First-Order Metal-Insulator Transition without Structural Phase Transition in VO_2

An abrupt first-order metal-insulator transition (MIT) without structural phase transition is first observed by current-voltage measurements and micro-Raman scattering experiments, when a DC electric field is applied to a Mott insulator VO_2 based two-terminal device. An abrupt current jump is measured at a critical electric field. The Raman-shift frequency and the bandwidth of the most predominant Raman-active A_g mode, excited by the electric field, do not change through the abrupt MIT, while, they, excited by temperature, pronouncedly soften and damp (structural MIT), respectively. This structural MIT is found to occur secondarily.Comment: 4 pages, 4 figure

Factors associated with delirium among survivors of acute respiratory distress syndrome: a nationwide cohort study

Background The prevalence of delirium, its associated factors, and its impact on long-term mortality among survivors of acute respiratory distress syndrome (ARDS) is unclear. Methods Since this was a population-based study, data were extracted from the National Health Insurance database in South Korea. All adults who were admitted to intensive care units with a diagnosis of ARDS between January 1, 2010, and December 31, 2019, and who survived for ≥ 60 days were included. The International Statistical Classification of Diseases and Related Health Problems, tenth revision code of delirium (F05) was used to extract delirium cases during hospitalization. Results A total of 6809 ARDS survivors were included in the analysis, and 319 patients (4.7%) were diagnosed with delirium during hospitalization. In the multivariable logistic regression analysis after covariate adjustment, male sex (odds ratio [OR] 1.60, 95% confidence interval [CI] 1.23, 2.08; P < 0.001), longer duration of hospitalization (OR 1.02, 95% CI 1.01, 1.03; P < 0.001), neuromuscular blockade use (OR 1.50, 95% CI 1.12, 2.01; P = 0.006), benzodiazepine (OR 1.55, 95% CI 1.13, 2.13; P = 0.007) and propofol (OR 1.48, 95% CI 1.01, 2.17; P = 0.046) continuous infusion, and concurrent depression (OR 1.31, 95% CI 1.01, 1.71; P = 0.044) were associated with a higher prevalence of delirium among ARDS survivors. In the multivariable Cox regression analysis after adjustment for covariates, the occurrence of delirium was not significantly associated with 1-year all-cause mortality, when compared to the other survivors who did not develop delirium (hazard ratio: 0.85, 95% CI 1.01, 1.71; P = 0.044). Conclusions In South Korea, 4.7% of ARDS survivors were diagnosed with delirium during hospitalization in South Korea. Some factors were potential risk factors for the development of delirium, but the occurrence of delirium might not affect 1-year all-cause mortality among ARDS survivors.This research did not receive any specifc grant from funding agencies in the public, commercial, or not-for-proft sectors