Polarized QED cascades

By taking the spin and polarization of the electrons, positrons and photons into account in the strong-field QED processes of nonlinear Compton emission and pair production, we find that the growth rate of QED cascades in ultra-intense laser fields can be substantially reduced. While this means that fewer particles are produced, we also found them to be highly polarized. We further find that the high-energy tail of the particle spectra is polarized opposite to that expected from Sokolov-Ternov theory, which cannot be explained by just taking into account spin-asymmetries in the pair production process, but results significantly from 'spin-straggling'. We employ a kinetic equation approach for the electron, positron and photon distributions, each of them spin/polarization-resolved, with the QED effects of photon emission and pair production modelled by a spin/polarization dependent Boltzmann-type collision operator. For photon-seeded cascades, depending on the photon polarization, we find an excess or a shortage of particle production in the early stages of cascade development, which provides a path towards a controlled experiment. Throughout this paper we focus on rotating electric field configuration, which represent an idealized model and allows for a straightforward interpretation of the observed effects

In Vitro Evaluation of Antiviral Activities of Funicone-like Compounds Vermistatin and Penisimplicissin against Canine Coronavirus Infection

Recent studies have demonstrated that 3-O-methylfunicone (OMF), a fungal secondary metabolite from Talaromyces pinophilus belonging to the class of funicone-like compounds, has antiviral activity against canine coronaviruses (CCoV), which causes enteritis in dogs. Herein, we selected two additional funicone-like compounds named vermistatin (VER) and penisimplicissin (PS) and investigated their inhibitory activity towards CCoV infection. Thus, both compounds have been tested for their cytotoxicity and for antiviral activity against CCoV in A72 cells, a fibrosarcoma cell line suitable for investigating CCoV. Our findings showed an increase in cell viability, with an improvement of morphological features in CCoV-infected cells at the non-toxic doses of 1 μM for VER and 0.5 μM for PS. In addition, we observed that these compounds caused a strong inhibition in the expression of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor which is activated during CCoV infection. Our results also showed the alkalinization of lysosomes in the presence of VER or PS, which may be involved in the observed antiviral activities

Electron spin polarization in realistic trajectories around the magnetic node of two counter-propagating, circularly polarized, ultra-intense lasers

It has recently been suggested that two counter-propagating, circularly polarized, ultra-intense lasers can induce a strong electron spin polarization at the magnetic node of the electromagnetic field that they setup (Del Sorbo et al 2017 Phys. Rev. A 96 043407). We confirm these results by considering a more sophisticated description that integrates over realistic trajectories. The electron dynamics is weakly affected by the variation of power radiated due to the spin polarization. The degree of spin polarization differs by approximately 5% if considering electrons initially at rest or already in a circular orbit. The instability of trajectories at the magnetic node induces a spin precession associated with the electron migration that establishes an upper temporal limit to the polarization of the electron population of about one laser period

The Effectiveness of Cyrene as a Solvent in Exfoliating 2D TMDs Nanosheets

The pursuit of environmentally friendly solvents has become an essential research topic in sustainable chemistry and nanomaterial science. With the need to substitute toxic solvents in nanofabrication processes becoming more pressing, the search for alternative solvents has taken on a crucial role in this field. Additionally, the use of toxic, non-economical organic solvents, such as N-methyl-2 pyrrolidone and dimethylformamide, is not suitable for all biomedical applications, even though these solvents are often considered as the best exfoliating agents for nanomaterial fabrication. In this context, the success of producing two-dimensional transition metal dichalcogenides (2D TMDs), such as MoS2 and WS2, with excellent captivating properties is due to the ease of synthesis based on environment-friendly, benign methods with fewer toxic chemicals involved. Herein, we report for the first time on the use of cyrene as an exfoliating agent to fabricate monolayer and few-layered 2D TMDs with a versatile, less time-consuming liquid-phase exfoliation technique. This bio-derived, aprotic, green and eco-friendly solvent produced a stable, surfactant-free, concentrated 2D TMD dispersion with very interesting features, as characterized by UV–visible and Raman spectroscopies. The surface charge and morphology of the fabricated nanoflakes were analyzed using ς-potential and scanning electron microscopy. The study demonstrates that cyrene is a promising green solvent for the exfoliation of 2D TMD nanosheets with potential advantages over traditional organic solvents. The ability to produce smaller-sized—especially in the case of WS2 as compared to MoS2—and mono/few-layered nanostructures with higher negative surface charge values makes cyrene a promising candidate for various biomedical and electronic applications. Overall, the study contributes to the development of sustainable and environmentally friendly methods for the production of 2D nanomaterials for various applications

Prediction of SARS-CoV-2-Related Lung Inflammation Spreading by V:ERITAS (Vanvitelli Early Recognition of Inflamed Thoracic Areas Spreading)

Background Coronavirus disease 2019 (COVID-19) can be complicated by interstitial pneu-monia, possibly leading to severe acute respiratory failure and death. Because of variable evolution ranging from asymptomatic cases to the need for invasive ventilation, COVID-19 outcomes cannot be precisely predicted on admission. The aim of this study was to provide a simple tool able to predict the outcome of COVID-19 pneumonia on admission to a low-intensity ward in order to better plan management strategies for these patients. Methods The clinical records of 123 eligible patients were reviewed. The following variables were analyzed on admission: chest computed tomography severity score (CTSS), PaO2/FiO2 ratio, lactate dehydrogenase (LDH), neutrophil to lymphocyte ratio (NLR), lymphocyte to monocyte ratio, C-reactive protein (CRP), fibrinogen, D-dimer, aspartate aminotransferase (AST), alanine aminotransferase, alkaline phosphatase, and albumin. The main outcome was the intensity of respiratory support (RS). To simplify the statistical analysis, patients were split into two main groups: those requiring no or low/moderate oxygen support (group 1); and those needing subintensive/intensive RS up to mechanical ventilation (group 2). Results The RS intensity was significantly associated with higher CTSS and NLR scores; lower PaO2/FiO2 ratios; and higher serum levels of LDH, CRP, D-dimer, and AST. After multivariate logistic regression and ROC curve analysis, CTSS and LDH were shown to be the best predictors of respiratory function worsening. Conclusions Two easy-to-obtain parameters (CTSS and LDH) were able to reliably predict a worse evolution of COVID-19 pneumonia with values of >7 and >328 U/L, respectively

Spin polarization of electrons by ultraintense lasers

Electrons in plasmas produced by next-generation ultraintense lasers (I>5×1022W/cm2) can be spin polarized to a high degree (10%-70%) by the laser pulses on a femtosecond time scale. This is due to electrons undergoing spin-flip transitions as they radiate γ-ray photons, preferentially spin polarizing in one direction. Spin polarization can modify the radiation reaction force on the electrons, which differs by up to 30% for opposite spin polarizations. Consequently, the polarization of the radiated γ-ray photons is also modified: the relative power radiated in the σ and π components increases and decreases by up to 30%, respectively, potentially reducing the rate of pair production in the plasma by up to 30%

Efficient ion acceleration and dense electron-positron plasma creation in ultra-high intensity laser-solid interactions

The radiation pressure of next generation ultra-high intensity ($>10^{23}$ W/cm$^{2}$) lasers could efficiently accelerate ions to GeV energies. However, nonlinear quantum-electrodynamic effects play an important role in the interaction of these laser pulses with matter. Here we show that these effects may lead to the production of an extremely dense ($\sim10^{24}$ cm$^{-3}$) pair-plasma which absorbs the laser pulse consequently reducing the accelerated ion energy and energy conversion efficiency by up to 30-50\%

Modelling the effects of the radiation reaction force on the interaction of thin foils with ultra-intense laser fields

The effects of the radiation reaction (RR) force on thin foils undergoing radiation pressure acceleration (RPA) are investigated. Using QED-particle-in-cell simulations, the influence of the RR force on the collective electron dynamics within the target can be examined. The magnitude of the RR force is found to be strongly dependent on the target thickness, leading to effects which can be observed on a macroscopic scale, such as changes to the distribution of the emitted radiation and the target dynamics. This suggests that such parameters may be controlled in experiments at multi-PW laser facilities. In addition, the effects of the RR force are characterized in terms of an average radiation emission angle. We present an analytical model which, for the first time, describes the effect of the RR force on the collective electron dynamics within the 'light-sail' regime of RPA. The predictions of this model can be tested in future experiments with ultra-high intensity lasers interacting with solid targets

Accidental Inflation in String Theory

We show that inflation in type IIB string theory driven by the volume modulus can be realized in the context of the racetrack-based Kallosh-Linde model (KL) of moduli stabilization. Inflation here arises through the volume modulus slow-rolling down from a flat hill-top or inflection point of the scalar potential. This situation can be quite generic in the landscape, where by uplifting one of the two adjacent minima one can turn the barrier either to a flat saddle point or to an inflection point supporting eternal inflation. The resulting spectral index is tunable in the range of 0.93 < n_s < 1, and there is only negligible production of primordial gravitational waves r < 10^{-6}. The flatness of the potential in this scenario requires fine-tuning, which may be justified taking into account the exponential reward by volume factors preferring the regions of the universe with the maximal amount of slow-roll inflation. This consideration leads to a tentative prediction of the spectral index $n_s\approx 0.95$ or $n_s \approx 0.93$ depending on whether the potential has a symmetry phi -> - phi or not.Comment: 15 pages, 6 figures, LaTeX, uses RevTex