Pharmacological activation of endogenous protective pathways against oxidative stress under conditions of sepsis

Funding The study was funded entirely by institutional funds.Peer reviewedPostprin

Stable Umbral Chromospheric Structures

Aims. To understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable structures, and examine their relationship with observables in the H-alpha line. Methods. Filtergrams in the core of the Ca II H and H-alpha lines as observed with the Swedish 1-m Solar Telescope are employed. We utilise a technique that creates composite images and tracks the flash propagation horizontally. Results. We find 0"15 wide horizontal structures, in all of the three target sunspots, for every flash where the seeing was moderate to good. Discrete dark structures are identified that are stable for at least two umbral flashes, as well as systems of structures that live for up to 24 minutes. We find cases of extremely extended structures with similar stability, with one such structure showing an extent of 5". Some of these structures have a correspondence in H-alpha but we were unable to find a one to one correspondence for every occurrence. If the dark streaks are formed at the same heights as umbral flashes then there are systems of structures with strong departures from the vertical for all three analysed sunspots. Conclusions. Long-lived Ca II H filamentary horizontal structures are a common and likely ever-present feature in the umbra of sunspots. If the magnetic field in the chromosphere of the umbra is indeed aligned with the structures, then the present theoretical understanding of the typical umbra needs to be revisited.Comment: Accepted to Astronomy and Astrophysics. Online material (Fig3.mov and Fig4.mov) will be available at A&

Ultrashort PW laser pulse interaction with target and ion acceleration

We present the experimental results on ion acceleration by petawatt femtosecond laser solid interaction and explore strategies to enhance ion energy. The irradiation of micrometer thick (0.2 - 6.0 micron) Al foils with a virtually unexplored intensity regime (8x10^19 W/cm^2 - 1x10^21 W/cm^2) resulting in ion acceleration along the rear and the front surface target normal direction is investigated. The maximum energy of protons and carbon ions, obtained at optimised laser intensity condition (by varying laser energy or focal spot size), exhibit a rapid intensity scaling as I^0.8 along the rear surface target normal direction and I^0.6 along the front surface target normal direction. It was found that proton energy scales much faster with laser energy rather than the laser focal spot size. Additionally, the ratio of maximum ion energy along the both directions is found to be constant for the broad range of target thickness and laser intensities. A proton flux is strongly dominated in the forward direction at relatively low laser intensities. Increasing the laser intensity results in the gradual increase in the backward proton flux and leads to almost equalisation of ion flux in both directions in the entire energy range. These experimental findings may open new perspectives for applications.Comment: 6 pages, 5 figures, 3rd EAAC worksho

Scalable photonic sources using two-dimensional lead halide perovskite superlattices

Miniaturized photonic sources based on semiconducting two-dimensional (2D) materials offer new technological opportunities beyond the modern III-V platforms. For example, the quantum-confined 2D electronic structure aligns the exciton transition dipole moment parallel to the surface plane, thereby outcoupling more light to air which gives rise to high-efficiency quantum optics and electroluminescent devices. It requires scalable materials and processes to create the decoupled multi-quantum-well superlattices, in which individual 2D material layers are isolated by atomically thin quantum barriers. Here, we report decoupled multi-quantum-well superlattices comprised of the colloidal quantum wells of lead halide perovskites, with unprecedentedly ultrathin quantum barriers that screen interlayer interactions within the range of 6.5 Å. Crystallographic and 2D k-space spectroscopic analysis reveals that the transition dipole moment orientation of bright excitons in the superlattices is predominantly in-plane and independent of stacking layer and quantum barrier thickness, confirming interlayer decoupling

Observations and 3D Magnetohydrodynamic Modeling of a Confined Helical Jet Launched by a Filament Eruption

We present a detailed analysis of a confined filament eruption and jet associated with a C1.5 class solar flare. Multiwavelength observations from the Global Oscillations Network Group and Solar Dynamics Observatory reveal the filament forming over several days following the emergence and then partial cancellation of a minority polarity spot within a decaying bipolar active region. The emergence is also associated with the formation of a 3D null point separatrix that surrounds the minority polarity. The filament eruption occurs concurrently with brightenings adjacent to and below the filament, suggestive of breakout and flare reconnection, respectively. The erupting filament material becomes partially transferred into a strong outflow jet (∼60 km s−1 ) along coronal loops, becoming guided back toward the surface. Utilizing high-resolution Hα observations from the Swedish Solar Telescope/CRisp Imaging SpectroPolarimeter, we construct velocity maps of the outflows, demonstrating their highly structured but broadly helical nature. We contrast the observations with a 3D magnetohydrodynamic simulation of a breakout jet in a closed-field background and find close qualitative agreement. We conclude that the suggested model provides an intuitive mechanism for transferring twist/helicity in confined filament eruptions, thus validating the applicability of the breakout model not only to jets and coronal mass ejections but also to confined eruptions and flares

Magnetism in Semiconducting Molybdenum Dichalcogenides

Transition metal dichalcogenides (TMDs) are interesting for understanding fundamental physics of two-dimensional materials (2D) as well as for many emerging technologies, including spin electronics. Here, we report the discovery of long-range magnetic order below TM = 40 K and 100 K in bulk semiconducting TMDs 2H-MoTe2 and 2H-MoSe2, respectively, by means of muon spin-rotation (muSR), scanning tunneling microscopy (STM), as well as density functional theory (DFT) calculations. The muon spin rotation measurements show the presence of a large and homogeneous internal magnetic fields at low temperatures in both compounds indicative of long-range magnetic order. DFT calculations show that this magnetism is promoted by the presence of defects in the crystal. The STM measurements show that the vast majority of defects in these materials are metal vacancies and chalcogen-metal antisites which are randomly distributed in the lattice at the sub-percent level. DFT indicates that the antisite defects are magnetic with a magnetic moment in the range of 0.9-2.8 mu_B. Further, we find that the magnetic order stabilized in 2H-MoTe2 and 2H-MoSe2 is highly sensitive to hydrostatic pressure. These observations establish 2H-MoTe2 and 2H-MoSe2 as a new class of magnetic semiconductors and opens a path to studying the interplay of 2D physics and magnetism in these interesting semiconductors.Comment: 13 pages, 10 Figure

Ultrashort PW laser pulse interaction with target and ion acceleration

We present the experimental results on ion acceleration by petawatt femtosecond laser solid interaction and explore strategies to enhance ion energy. The irradiation of micrometer thick (0.2-6.0 mu m) Al foils with a virtually unexplored intensity regime (8 x 10(19) W/cm(2) - 1 x 10(21) W/cm(2)) resulting in ion acceleration along the rear and the front surface target normal direction is investigated. The maximum energy of protons and carbon ions, obtained at optimized laser intensity condition (by varying laser energy or focal spot size), exhibit a rapid intensity scaling as I-0.8 along the rear surface target normal direction and I-0.6 along the front surface target normal direction. It was found that proton energy scales much faster with laser energy rather than the laser focal spot size. Additionally, the ratio of maximum ion energy along the both directions is found to be constant for the broad range of target thickness and laser intensities. A proton flux is strongly dominated in the forward direction at relatively low laser intensities. Increasing the laser intensity results in the gradual increase in the backward proton flux and leads to almost equalization of ion flux in both directions in the entire energy range. These experimental findings may open new perspectives for applications

Weathering the Storm: Talent Management in Internationally Oriented Greek Small and Medium-Sized Enterprises

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Purpose – Based on a study of internationally oriented Greek small and medium-sized enterprises (SMEs), and using the lens of institutional theory, this article extends our understanding of the extent to which Greece’s institutional context influences talent management (TM). In so doing, we focused on key TM practices employed by SMEs to enhance and sustain TM: talent acquisition, development and retention. We also explore how these practices are shaped by the Greek institutional context. Design/methodology/approach - Employing a multiple case-study approach, we conducted 18 interviews in six distinctive SMEs operating in north, central and southern Greece. The data was thematically analysed to identify patterns across all SMEs. Findings - We found that unlike multinational corporations (MNCs), internationally oriented Greek SMEs adopt a more inclusive approach to TM practices as well as that the country’s institutional context presented important yet not deterministic hurdles. We also found that SMEs adopt an opportunistic approach to talent acquisition by utilising appropriate available sources to reach out for available talent. We provided evidence that SMEs adopt a hybrid approach to talent development in addressing talent scarcity. Finally, we reported that talent retention is significantly appreciated by SMEs, who offer a range of intrinsic and extrinsic incentives to retain their talented workforce. Originality - In a context of reforms, we report on TM practice in internationally oriented Greek SMEs. We also add to the literature on TM in SMEs by providing evidence on the conceptualisation and management of global talent in this context