Weakening of the stratospheric polar vortex by Arctic sea-ice loss

Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.open11167174Ysciescopu

A Preliminary Risk Assessment on the Development of a Small-Scaled Floating Power Plant

This paper introduces a preliminary risk assessment method carried out on a newly developed floating power plant. The small-scale floating power plant has been developed to provide electric power for areas on demand, and this is a kind of a new concept system which is not clearly classified in the maritime industry. To grant the feasibility for this novel system design, a set of risk assessment activities is essentially required, and in this context, a hazard identification (HAZID) study is conducted at the very early stage of the plant design. The aims of this HAZID study are to verify the inherent safety of the initial plant design and to provide any recommendations on the next design stages. For this purpose, the potential hazards are identified in view of personnel, structural, and asset effects in association with the operation of the power plant and all the identified hazards and relevant risks are assessed with the defined criteria using a simple risk matrix. As a result, the risk or safety level of the conceptual plant design is estimated, and some design changes are suggested to give a better balance between the safety and the cost of the plant system. Overall, this paper shows how the primitive risk assessment techniques are utilized as a practical engineering tool in the development of the marine system

Factors Related to Clinical Competence among Graduating Nursing Students during the COVID-19 Pandemic: A Cross-Sectional Study.

PURPOSE: This study investigated clinical competency, COVID-19-related anxiety, coping strategies, self-efficacy, and perceived stress among graduating nursing students during the COVID-19 pandemic. METHODS: We conducted a cross-sectional survey. Participants were recruited from universities located in four major cities in South Korea. General demographic information, clinical competency, self-efficacy, perceived stress, COVID-19-related anxiety, and coping strategies were assessed using reliable questionnaires. Descriptive statistics, correlations, and multiple regression tests were used to analyze the data. RESULTS: The mean clinical competency, self-efficacy, perceived stress, adaptive coping, and maladaptive coping were 138.16 ± 18.34, 83.85 ±14.02, 21.37 ± 5.79, 53.15 ± 4.64, and 30.98 ± 6.73, respectively. COVID-19-related anxiety was reported by 4.3% of participants. Clinical competency was significantly positively correlated with self-efficacy (r = .44, p < .001) and adaptive coping (r = .20, p = .035) and was significantly negatively correlated with maladaptive coping (r = .20, p = .035). The predictors of clinical competency were self-efficacy (β = .434, p < .001) and adaptive coping (β = .173, p < .039), which explained 23% of the variance in clinical competency. CONCLUSION: Self-efficacy and adaptive coping strategies are significant predictors of clinical competence during the pandemic. Planning and implementing various curricular and non-curricular activities to increase senior students' self-efficacy and adaptive coping strategies will help prepare competent nursing graduates for the pandemic when they enter the nursing workforce

An interface-proximity model for switchable interfacial uncompensated antiferromagnetic spins and their role in exchange bias

We propose an interface-proximity model that allows us to solve a longstanding puzzle regarding large discrepancies between the experimentally observed and theoretically estimated values of exchange-bias field Heb in coupled ferromagneticantiferromagnetic (FAF) metallic films. In this proposed model, switchable uncompensated (UC) AF spins in contact with an F layer are taken into account as an additionally inserting layer that is chemically or magnetically distinguishable from each of the nominal AF and F layers. Reductions in Heb, enhancements in coercivity, and other exchange-bias behaviors typically observed in experiments are very well reproduced from this model. The switchable interfacial UC region with a sizable thickness, heretofore ignored, plays a crucial role in the exchange bias phenomenon.open6

Atomic-scale depth selectivity of soft x-ray resonant Kerr effect

A study was performed to demonstrate that soft x-ray Kerr rotation, ??K, versus incident grazing angle, ??, and energy, hv, measurements provide an extremely large depth selectivity on the atomic scales even in an ultrathin single layer, simply by choosing appropriate ?? and hv around the resonant regions. Both the experimental and simulation results of ?? vs ??K measurements were considered for depth-varying magnetization reversals in a 3.5-nm-thick Co layer of NiFe/FeMn/Co/Pd films.open161

Soft x-ray resonant magneto-optical Kerr effect as a depth-sensitive probe of magnetic heterogeneity: Its application to resolve helical spin structures using linear p polarization

We have calculated the soft x-ray resonant Kerr intensities as a function of the incident grazing angle of linearly p-polarized waves from the model spin structures, where the chirality (handedness) of the spin spirals (twist in depth) in a magnetic layer and the periodicity of a unit spiral are designed to vary. Variations in the chirality and the periodicity lead to noticeable changes in the Kerr intensity versus the grazing angle, which is due not only to a large sensitivity of the Kerr intensity of the linear p polarization to both the magnitude and direction of the transverse components of magnetizations, but also to a large dependence of the depth sensitivity on the grazing angle at the resonance regions. The measurement and analysis of the specular Kerr intensity are relatively straightforward in determining the inhomogeneous spin structures in depth, compared to those of the Kerr rotation and ellipticity. This is proven to be a convenient and useful probe to determine the handedness of spin spiral structures, as well as to resolve the detailed magnetic heterostructures in depth in ultrathin-layered films.open4

Intracluster photodimerization of thymine: Size-dependent modes of cluster ion fragmentation

A mechanistic investigation of the processes following ultraviolet (UV) irradiation was carried out. A set of distinct and remarkably size-dependent modes of cluster fragmentation were discovered. These modes were also identified as the main culprit for the striking mass distribution that was experimentally observed. Multiple absorption of photons played a key role in such intracluster photodimerization.open8

Radiation of spin waves from magnetic vortex cores by their dynamic motion and annihilation processes

We report on micromagnetic simulation results of radiation of strong spin waves from the cores of magnetic vortices driven by their dynamics motion or the annihilation of a vortex-antivortex pair in a rectangular shaped magnetic thin film. Such strong spin-waves are distinguished from spin wave modes typically excited in patterned magnetic elements. The spin wave excitation with relatively low frequencies of 0-22 GHz are associated with the shape of an element, a magnetization configuration, and an applied magnetic field, while dominating spin waves in the higher frequencies of 22-96 GHz are driven by either the motion or annihilation of vortex cores present in the confined element. The latter case yields much higher amplitudes than the former does. It is found that large torques applied at the local area of the vortex cores, driven by the large exchange fields in the core region during their dynamic motion and collapse, induce a rapid energy dissipation into the surrounding areas through the spin-wave excitation and subsequent propagation. In addition, it is found that the strong spin waves radiated by the dynamic evolution processes of the vortex cores propagate well into a long stripe-shaped magnetic wire. Such traveling spin waves can be applicable for a new generation of magnetic logic devices.open403