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High-brilliance high-polarization γ rays based on Compton scattering are of great significance in broad areas, such as nuclear physics, high-energy physics, astrophysics, etc. However, the transfer mechanism of spin angular momentum in the transition from linear through weakly into strongly nonlinear processes is still unclear, which severely limits the simultaneous control of brilliance and polarization of high-energy γ rays. In this work, we clarify the transfer mechanism in the transition regions and put forward a clear way to efficiently manipulate the polarization of emitted photons. We find that to simultaneously generate high-energy, high-brilliance, and high-polarization γ rays, it is better to increase the laser intensity for the initially spin-polarized electron beam. However, for the case of employing the initially spin-nonpolarized electron beam, in addition to increasing laser intensity, it is also necessary to increase the energy of the electron beam. Because the γ photon polarization emitted through the single-photon absorption channel is mainly attributed to the spin transfer of laser photons, while in multi-photon absorption channels, the electron spin plays a major role. Moreover, we confirm that the signature of γ-ray polarization can be applied to observing the nonlinear effects (multi-photon absorption) of Compton scattering with moderate-intensity laser facilities. [ABSTRACT FROM AUTHOR]

Strong-field quantum electrodynamics (SF-QED) plays a crucial role in ultraintense laser–matter interactions and demands sophisticated techniques to understand the related physics with new degrees of freedom, including spin angular momentum. To investigate the impact of SF-QED processes, we have introduced spin/polarization-resolved nonlinear Compton scattering, nonlinear Breit–Wheeler, and vacuum birefringence processes into our particle-in-cell (PIC) code. In this article, we provide details of the implementation of these SF-QED modules and share known results that demonstrate exact agreement with existing single-particle codes. By coupling normal PIC simulations with spin/polarization-resolved SF-QED processes, we create a new theoretical platform to study strong-field physics in currently running or planned petawatt or multi-petawatt laser facilities. [ABSTRACT FROM AUTHOR]

Competition and transition of the dominated mechanisms for proton acceleration were investigated in experiments by optically tuning the preplasma density profile using an additional femtosecond pre-ablation laser beam. Two groups of proton beams with angular separation were measured along the laser propagation axis and target normal direction from a vacuum-gapped double-foil target. A transition of proton acceleration from a target normal sheath acceleration regime to relativistically induced transparency (RIT) domination was observed when increasing the prepulse intensity. Two-dimensional particle-in-cell simulations qualitatively verify the experimental observations that a proton component along the laser axis is mainly generated by the RIT induced breakout afterburner from the tailored pre-expanded ultrathin front-layer foil with spatial-intensity distribution improvement by the second-layer foil. Our method can be popularized in manipulating the laser-driven proton acceleration and beam spatial quality for wide applications. [ABSTRACT FROM AUTHOR]

The rapid development of ultrafast ultraintense laser technology continues to create opportunities for studying strong-field physics under extreme conditions. However, accurate determination of the spatial and temporal characteristics of a laser pulse is still a great challenge, especially when laser powers higher than hundreds of terawatts are involved. In this paper, by utilizing the radiative spin-flip effect, we find that the spin depolarization of an electron beam can be employed to diagnose characteristics of ultrafast ultraintense lasers with peak intensities around 1020–1022 W/cm2. With three shots, our machine-learning-assisted model can predict, simultaneously, the pulse duration, peak intensity, and focal radius of a focused Gaussian ultrafast ultraintense laser (in principle, the profile can be arbitrary) with relative errors of 0.1%–10%. The underlying physics and an alternative diagnosis method (without the assistance of machine learning) are revealed by the asymptotic approximation of the final spin degree of polarization. Our proposed scheme exhibits robustness and detection accuracy with respect to fluctuations in the electron beam parameters. Accurate measurements of ultrafast ultraintense laser parameters will lead to much higher precision in, for example, laser nuclear physics investigations and laboratory astrophysics studies. Robust machine learning techniques may also find applications in more general strong-field physics scenarios. [ABSTRACT FROM AUTHOR]

Two new glycosides of methyl everninate, rhodomollosides A (1) and B (2), were isolated from the aerial parts of a medicinal plant Rhododendron molle. The structures of 1 and 2 were elucidated on the basis of detailed spectroscopic analyses as well as HPLC analyses for thiazolidine derivatives of their sugar moieties. The sugar moiety of rhodomolloside A (1) was elucidated to be a rare monosaccharide, D-allose, while rhodomolloside B (2) was assigned as a D-glucoside of methyl everninate. Furthermore, they were evaluated for their cytotoxicity against RAW264.7 cells, and for their inhibitory effects with a lipopolysaccharide (LPS)-stimulated murine macrophages RAW 264.7 cells model. [ABSTRACT FROM AUTHOR]

Deep understanding of the impact of photon polarization on pair production is essential for the efficient generation of laser-driven polarized positron beams and demands a complete description of polarization effects in strong-field QED processes. Employing fully polarization-resolved Monte Carlo simulations, we investigate correlated photon and electron (positron) polarization effects in the multiphoton Breit–Wheeler pair production process during the interaction of an ultrarelativistic electron beam with a counterpropagating elliptically polarized laser pulse. We show that the polarization of e−e+ pairs is degraded by 35% when the polarization of the intermediate photon is resolved, accompanied by an ∼13% decrease in the pair yield. Moreover, in this case, the polarization direction of energetic positrons at small deflection angles can even be reversed when high-energy photons with polarization parallel to the laser electric field are involved. [ABSTRACT FROM AUTHOR]

The generation of highly polarized high-energy brilliant γ-rays via laser–plasma interaction is investigated in the quantum radiation-reaction regime. We employ a quantum electrodynamics particle-in-cell code to describe spin-resolved electron dynamics semiclassically and photon emission and polarization quantum mechanically in the local constant field approximation. As an ultrastrong linearly polarized (LP) laser pulse irradiates a near-critical-density (NCD) plasma followed by an ultrathin planar aluminum target, the electrons in the NCD plasma are first accelerated by the driving laser to ultrarelativistic energies and then collide head-on with the laser pulse reflected by the aluminum target, emitting brilliant LP γ-rays via nonlinear Compton scattering with an average polarization of about 70% and energy up to hundreds of MeV. Such γ-rays can be produced with currently achievable laser facilities and will find various applications in high-energy physics and laboratory astrophysics. [ABSTRACT FROM AUTHOR]

Background: Mycoplasma is an opportunistic pathogen causing both urogenital and extragenital infections. The lack of cell wall renders Mycoplasma difficult to culture and identify with ordinary methods. Next-generation sequencing (NGS) is a new technology helping a lot in the diagnosis of infective diseases. In this case, NGS played a key role in the diagnosis of Mycoplasma infection. Case presentation: A mid-aged man suffering from renal cyst underwent cyst incision followed by invasive treatments to eliminate hematoma caused by renal artery hemorrhage. After the cyst incision operation, the patient had a persistent high temperature. The persistent increase of blood neutrophile granulocyte count and C-reaction protein suggested an unresolved infection. The empirically chosen anti-infective agents were meropenem and linezolid since the ordinary bacterial cultures of surgical site drainage and blood yielded a negative result. At postoperation day (POD) 17, NGS result of his drainage clearly indicated the pathogen was Mycoplasma hominis. At POD 24, the drug sensitivity test showed resistance to quinolones, clarithromycin and erythromycin, but intermediate to azithromycin. Since then, the antimicrobial agents were changed into azithromycin and kept unchanged until the patient was fully recovered and discharged at POD 39. Conclusion: When the ordinary laboratory diagnostic methods failed, NGS diagnosis could reduce the hospitalization expenses and shorten the lengths of hospital stay. [ABSTRACT FROM AUTHOR]

In this work, a broadband frequency selective surface (FSS), which is insensitive to incident angle is designed. This FSS is composed of three metallic layers and two identical dielectric layers. The top and bottom layers are two identical metal patches, while the middle layer is a slot structure etched in a metal screen. This FSS achieves a broadband pass‐band response from 9.8 to 20.8 GHz by combining different resonant modes at 12.6, 15.2, and 19.2 GHz, respectively. Meanwhile, this FSS can still function properly at up to 60° oblique incidence for TE polarization, which is attributed to the independence of incident angle of the middle slot layer and miniaturization of the whole structure. In addition, two key parameters (that are of great importance in adjusting flatness of the pass‐band) of the FSS element have been studied. A prototype of the FSS was manufactured and measured. Good agreements between measurements and simulations are observed. [ABSTRACT FROM AUTHOR]

Taking bare land as the control, this paper studied the effects of different planting modes on the soil permeability of sloping farmlands in purple soil area. For the test six planting modes, the soil permeability was in the order of Eriobotrya japonica > Citrus limon > Vetiveria zizanioides hedgerows+corn>Leucaena leucocephala hedgerows+corn>Hemerocallis fulva>corn>bare land, and decreased with increasing depth. The eigenvalues of soil infiltration were in the order of initial infil- tration rate>average infiltration rate>stable infiltration rate. The soil permeability had significant positive linear correlations with soil total porosity, non-capillary porosity, initial moisture content, water holding capacity, and organic matter content, and significant negative linear correlation with soil bulk density. The common empirical infiltration model could well fit the soil moisture infiltration processes under the six planting modes, while the Kostiakov equation could not. [ABSTRACT FROM AUTHOR]

In this paper, the interactional behaviors of anomalous vortex beams in highly nonlocal media are investigated. An analytical expression describing the interaction is given, and some numerical simulations are carried out to illustrate the interactional characteristics. It is found that two interactional anomalous vortex beams always attract each other, and their evolution is periodical. The influence of different relative phases between two anomalous vortex beams on their interaction is presented in details. [ABSTRACT FROM AUTHOR]

We investigate the beam width evolution of astigmatic hollow Gaussian beams propagating in highly nonlocal nonlinear media. The input-power-induced different evolutions of the beam width are illustrated: (i) the beam widths in two transverse directions are compressed or broadened at the same time; (ii) the beam width in one transverse direction keeps invariant, and the other is compressed or broadened; (iii) furthermore, the beam width in one transverse direction is compressed, whereas it in the other transverse direction is broadened. [ABSTRACT FROM AUTHOR]

In this paper, we focus on the on-axis intensity evolutions of hollow beams in nonlinear media with a high nonlocality. It is found that, the evolutions of on-axis intensity with different beam powers are always periodic during propagation, whereas, depending on different beam powers, the evolution curves of on-axis intensity in each period may exhibit themselves as three different types, namely, a concave, a platform, or a convex shape. The critical power, the extreme values of on-axis intensity and their corresponding positions are all given analytically. [ABSTRACT FROM AUTHOR]

A chiral metasurface is proposed to realize a tri-band polarization angle insensitive cross-polarization converter. The unit cell of the chiral metamaterial is composed by four twisted anisotropic structure pairs in four-fold rotation symmetry. The simulation results show that this device can work at 9.824 GHz, 11.39 GHz, and 13.37 GHz with low loss and a high polarization conversion ratio (PCR) of more than 99%. The proposed design can transmit the co-polarization wave at 14.215 GHz, like a frequency selective surface. The study of the current and electric fields distributions indicates that the cross-polarization transmission is due to electric dipole coupling. [ABSTRACT FROM AUTHOR]

By using experimental results and taking into account the characteristics of shaping in the focal region, we theoretically demonstrate the plasma ellipsoid model and calculate the breakdown threshold and the directivity of the sound filed. It is found that the predictions in our theoretical model well agree with the results of experiments. [ABSTRACT FROM AUTHOR]

Relativistic spin-polarized positron beams are indispensable for future electron-positron colliders to test modern high-energy physics theory with high precision. However, present techniques require very large scale facilities for those experiments. We put forward a novel efficient method for generating ultrarelativistic polarized positron beams employing currently available laser fields. For this purpose, the generation of polarized positrons via multiphoton Breit-Wheeler pair production and the associated spin dynamics in single-shot interaction of an ultraintense laser pulse with an ultrarelativistic electron beam is investigated in the quantum radiation-dominated regime. The pair production spin asymmetry in strong fields, significantly exceeding the asymmetry of the radiative polarization, produces locally highly polarized particles, which are split by a specifically tailored small ellipticity of the laser field into two oppositely polarized beams along the minor axis of laser polarization. In spite of radiative de-polarization, a dense positron beam with up to about 90% polarization can be generated in tens of femtoseconds. The method may eventually usher high-energy physics studies into smaller-scale laser laboratories. [ABSTRACT FROM AUTHOR]