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Hydrogen bonds are ubiquitous in nature and of fundamental importance to the chemical and physical properties of molecular systems in the condensed phase. Nevertheless, our understanding of the structural and dynamical properties of hydrogen-bonded complexes in particular in electronic excited states remains very incomplete. Here, by using formic acid (FA) dimer as a prototype of DNA base pair, we investigate the ultrafast decay process initiated by removal of an electron from the inner-valence shell of the molecule upon electron-beam irradiation. Through fragment-ion and electron coincident momentum measurements and

The advent of laser-driven high-intensity γ-photon beams has opened up new opportunities for designing advanced photon-photon colliders. Such colliders have the potential to produce a large yield of linear Breit-Wheeler (LBW) pairs in a single shot, which offers a unique platform for studying the polarized LBW process. In our recent work [Q. Zhao et al., Signatures of linear Breit-Wheeler pair production in polarized γγ collisions, Phys. Rev. D 105, L071902 (2022)], we investigated the polarization characteristics of LBW pair production in circularly-polarized (CP) γ-photon collisions. To fully clarify the polarization effects involving both CP and linearly-polarized γ-photons, here we further investigate the LBW process using the polarized cross section with explicit azimuthal-angle dependence due to the base rotation of photon-polarization vectors. We accomplished this by defining a new spin basis for positrons and electrons, which enables us to decouple the transverse and longitudinal spin components of e±. By means of analytical calculations and Monte Carlo simulations, we find that the linear polarization of photon can induce the highly angle-dependent pair yield and polarization distributions. The comprehensive knowledge of the polarized LBW process will also open up avenues for investigating the higher-order photon-photon scattering, the laser-driven quantum electrodynamic plasmas and the high-energy astrophysics.

Circularly polarized (CP) γ-ray sources are versatile for broad applications in nuclear physics, high-energy physics, and astrophysics. The laser-plasma based particle accelerators provide accessibility for much higher flux γ-ray sources than conventional approaches, in which, however, the circular polarization properties of the emitted γ-photons are usually neglected. In this Letter, we show that brilliant CP γ-ray beams can be generated via the combination of laser plasma wakefield acceleration and plasma mirror techniques. In a weakly nonlinear Compton scattering scheme with moderate laser intensities, the helicity of the driving laser can be transferred to the emitted γ-photons, and their average polarization degree can reach ∼61% (20%) with a peak brilliance of ≳ 10 21 photons/(s · mm2 · mrad2 · 0.1% BW) around 1 MeV (100 MeV). Moreover, our proposed method is easily feasible and robust with respect to the laser and plasma parameters.

The polarization characteristics of the linear Breit-Wheeler (LBW) pair-production process in polarized γγ colliders have been investigated via our developed spin-resolved binary collision simulation method. We find that the polarization of γ-photons modifies the kinematics of scattering particles and induces the correlated energy-angle shift of LBW pairs, and the latter’s polarization characteristic depends on the helicity configures of scattering particles. We confirm that the polarized γγ collider with an asymmetric setup can be performed with currently achievable laser-driven high-density x rays and high-brilliance γ-photon beams to produce abundant polarized LBW pairs, fulfilling the detection power of polarimetries. Our method and results on the polarized LBW process have plenty of significant applications in strong-field physics, high-energy physics and astrophysics, such as calibrating and monitoring the polarized γγ collider and challenging the current understanding of astrophysical objects through enhancing the opacity of γ-photons to exacerbate the inconsistency between some observations and standard models.

Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser-plasma-based ion-acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to postcompress a highly accelerated proton beam and convert it to a dense quasimonoenergetic one. We find that when the relativistic plasma produced by radiation-pressure acceleration collides head on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation reaction and the ponderomotive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved quantum electrodynamics (QED) particle-in-cell simulations show that hollow-structure proton beams with a peak energy approximately GeV, relative energy spread of few percents, and number Np ∼1010 (or Np ∼109 with a 1% energy spread) can be produced in near-future laser facilities, which may fulfill the requirements of alternative applications, such as, for radiography of ultrathick dense materials, or as injectors of hadron colliders.

Benign prostatic hyperplasia (BPH) is highly prevalent among older men, impacting on their quality of life, sexual function, and genitourinary health, and has become an important global burden of disease. Transurethral plasmakinetic resection of prostate (TUPKP) is one of the foremost surgical procedures for the treatment of BPH. It has become well established in clinical practice with good efficacy and safety. In 2018, we issued the guideline "2018 Standard Edition". However much new direct evidence has now emerged and this may change some of previous recommendations. The time is ripe to develop new evidence-based guidelines, so we formed a working group of clinical experts and methodologists. The steering group members posed 31 questions relevant to the management of TUPKP for BPH covering the following areas: questions relevant to the perioperative period (preoperative, intraoperative, and postoperative) of TUPKP in the treatment of BPH, postoperative complications and the level of surgeons' surgical skill. We searched the literature for direct evidence on the management of TUPKP for BPH, and assessed its certainty generated recommendations using the grade criteria by the European Association of Urology. Recommendations were either strong or weak, or in the form of an ungraded consensus-based statement. Finally, we issued 36 statements. Among them, 23 carried strong recommendations, and 13 carried weak recommendations for the stated procedure. They covered questions relevant to the aforementioned three areas. The preoperative period for TUPKP in the treatment of BPH included indications and contraindications for TUPKP, precautions for preoperative preparation in patients with renal impairment and urinary tract infection due to urinary retention, and preoperative prophylactic use of antibiotics. Questions relevant to the intraoperative period incorporated surgical operation techniques and prevention and management of bladder explosion. The application to different populations incorporating the efficacy and safety of TUPKP in the treatment of normal volume ( 80 ml) and large-volume (≥ 80 ml) BPH compared with transurethral urethral resection prostate, transurethral plasmakinetic enucleation of prostate and open prostatectomy; the efficacy and safety of TUPKP in high-risk populations and among people taking anticoagulant (antithrombotic) drugs. Questions relevant to the postoperative period incorporated the time and speed of flushing, the time indwelling catheters are needed, principles of postoperative therapeutic use of antibiotics, follow-up time and follow-up content. Questions related to complications incorporated types of complications and their incidence, postoperative leukocyturia, the treatment measures for the perforation and extravasation of the capsule, transurethral resection syndrome, postoperative bleeding, urinary catheter blockage, bladder spasm, overactive bladder, urinary incontinence, urethral stricture, rectal injury during surgery, postoperative erectile dysfunction and retrograde ejaculation. Final questions were related to surgeons' skills when performing TUPKP for the treatment of BPH. We hope these recommendations can help support healthcare workers caring for patients having TUPKP for the treatment of BPH.

An all-optical method of ultrafast spin rotation is put forward to precisely manipulate the polarization of relativistic charged particle beams of leptons or ions. In particular, laser-driven dense ultrashort beams are manipulated via single-shot interaction with a co-propagating moderate temporally asymmetric (frequency-chirped or subcycle THz) laser pulse. Using semi-classical numerical simulations, we find that in a temporally asymmetrical laser field, the spin rotation of a particle can be determined from the flexibly controllable phase retardation between its spin precession and momentum oscillation. An initial polarization of a proton beam can be rotated to any desired orientation (e.g., from the common transverse to the more useful longitudinal polarization) with extraordinary precision (better than 1\%) in tens of femtoseconds using a feasible frequency-chirped laser pulse. Moreover, the beam qualities, in terms of energy and angular divergence, can be significantly improved in the rotation process. This method has potential applications in various areas involving ultrafast spin manipulation, like laser-plasma, laser-nuclear and high-energy particle physics.

High-energy spin-polarized electron, positron, and $\gamma$-photon beams have many significant applications in the study of material properties, nuclear structure, particle physics, and high-energy astrophysics. Thus,efficient production of such polarized beams attracts a broad spectrum of research interests. This is driven mainly by the rapid advancements in ultrashort and ultraintense laser technology. Currently available laser pulses can achieve peak intensities in the range of $10^{22}-10^{23}$ Wcm$^{-2}$, with pulse durations of tens of femtoseconds. The dynamics of particles in laser fields of the available intensities is dominated by quantum electrodynamics (QED) and the interaction mechanisms have reached regimes spanned by nonlinear multiphoton absorbtion (strong-field QED processes). In strong-field QED processes, the scattering cross sections obviously depend on the spin and polarization of the particles, and the spin-dependent photon emission and the radiation-reaction effects can be utilized to produce the polarized particles. An ultraintense laser-driven polarized particle source possesses the advantages of high-brilliance and compactness, which could open the way for the unexplored aspects in a range of researches. In this work, we briefly review the seminal conclusions from the study of the polarization effects in strong-field QED processes, as well as the progress made by recent proposals for production of the polarized particles by laser-beam or laser-plasma interactions.

Deep understanding of photon polarization impact on pair production is essential for the efficient creation of laser driven polarized positron beams, and demands a complete description of polarization effects in strong-field QED processes. We investigate, employing fully polarization resolved Monte Carlo simulations, the correlated photon and electron (positron) polarization effects in multiphoton Breit-Wheeler pair production process during the interaction of an ultrarelativistic electron beam with a counterpropagating elliptically polarized laser pulse. We showed that the polarization of e^-e^+ pairs is degraded by 35\%, when the polarization of the intermediate photon is resolved, accompanied with an approximately 13\% decrease of the pair yield. Moreover, the polarization direction of energetic positrons in small angle region is reversed, which originates from the pair production of hard photons with polarization parallel with electric field.

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.

The hydrodynamic behavior of a cylindrical solid target, heated by the intense heavy-ion beams, was simulated. The target was of the LAboratory PlAnetary Science (LAPLAS)-type geometry, as described by Tahir (LAPLAS). An iron target irradiated by the intense heavy-ion beams, with parameters available from the planned High Intensity Accelerator Facility or Facility for Antiproton and Ion Research, Society for Heavy Ion Research, Darmstadt, Germany, will transform to the warm-dense state, similar to the situation that exists in the planet interior. The dependence of the achievable state of iron on the outer-shell material and beam location was investigated with Medusa-code simulations. The simulation results show that the compression of inner iron is significantly influenced by the density-to-mass ratio of the outer-shell material and the location of the beam heating. Using the LAPLAS geometry, a uranium beam of 800 MeV/u, and 1.5 × 10 11 particles per pulse, our simulations show that the warm-dense-matter regime for iron is obtained. Details depend on the yet unknown equation of state and will be measured when this beam intensity is available in a couple of years.

Generation of arbitrarily spin-polarized lepton (here refer in particular to electron and positron) beams has been investigated in the single-shot interaction of high-energy polarized $\gamma$ photons with an ultraintense asymmetric laser pulse via nonlinear Breit-Wheeler (BW) pair production. We develop a fully spin-resolved semi-classical Monte Carlo method to describe the pair creation and polarization in the local constant field approximation. In nonlinear BW process the polarization of created pairs is simultaneously determined by the polarization of parent $\gamma$ photons, the polarization and asymmetry of scattering laser field, due to the spin angular momentum transfer and the asymmetric spin-dependent pair production probabilities, respectively. In considered all-optical method, dense GeV lepton beams with average polarization degree up to about $80\%$ (adjustable between the transverse and longitudinal components) can be obtained with currently achievable laser facilities, which could be used as injectors of the polarized $e^{+}e^{-}$ collider to search for new physics beyond the Standard Model.

Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser- plasma-based ion-acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to postcompress a highly accelerated proton beam and convert it to a dense quasimonoenergetic one. We find that when the relativistic plasma produced by radiation-pressure acceleration collides head on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation reaction and the pondero- motive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved quantum electrodynamics (QED) particle-in- cell simulations show that hollow-structure proton beams with a peak energy approximately GeV, relative energy spread of few percents, and number Np ∼ 1010 (or Np ∼ 109 with a 1% energy spread) can be pro- duced in near-future laser facilities, which may fulfill the requirements of alternative applications, such as, for radiography of ultrathick dense materials, or as injectors of hadron colliders.

The interaction of an unpolarized electron beam with a counterpropagating ultraintense linearly polarized laser pulse is investigated in the quantum radiation-dominated regime. We employ a semiclassical Monte Carlo method to describe spin-resolved electron dynamics, photon emissions and polarization, and pair production. Abundant high-energy linearly polarized γ photons are generated intermediately during this interaction via nonlinear Compton scattering, with an average polarization degree of more than 50%, further interacting with the laser fields to produce electron-positron pairs due to the nonlinear Breit-Wheeler process. The photon polarization is shown to significantly affect the pair yield by a factor of more than 10%. The considered signature of the photon polarization in the pair's yield can be experimentally identified in a prospective two-stage setup. Moreover, with currently achievable laser facilities the signature can serve also for the polarimetry of high-energy high-flux γ photons.

Generation of circularly polarized (CP) and linearly polarized (LP) $\ensuremath{\gamma}$ rays via the single-shot interaction of an ultraintense laser pulse with a spin-polarized counterpropagating ultrarelativistic electron beam has been investigated in nonlinear Compton scattering in the quantum radiation-dominated regime. For the process simulation, a Monte Carlo method is developed which employs the electron-spin-resolved probabilities for polarized photon emissions. We show efficient ways for the transfer of the electron polarization to the high-energy photon polarization. In particular, multi-GeV CP (LP) $\ensuremath{\gamma}$ rays with polarization of up to about 95% can be generated by a longitudinally (transversely) spin-polarized electron beam, with a photon flux meeting the requirements of recent proposals for the vacuum birefringence measurement in ultrastrong laser fields. Such high-energy, high-brilliance, high-polarization $\ensuremath{\gamma}$ rays are also beneficial for other applications in high-energy physics, and laboratory astrophysics.

With the rapid development of deep learning techniques in computer vision, emotion detection has been an emerging topic for different industries, including healthcare, mobile entertainment, and even securities. These organizations leverage emotion detection and apply it to both real-time cameras and offline videos to provide more interactivity between users and devices. In this study, we provide a lightweight personalized accompanying system for home security using emotion detection and IoT devices. We implement our design and demonstrate a practical scenario using Nvidia Jetson Nano. According to our design, we hope the system can benefit the health monitoring and interactivity for those elderly living alone.

Stochasticity effects in the spin (de)polarization of an ultrarelativistic electron beam during photon emissions in a counterpropoagating ultrastrong focused laser pulse in the quantum radiation reaction regime are investigated. We employ a Monte Carlo method to describe the electron dynamics semiclassically, and photon emissions as well as the electron radiative polarization quantum mechanically. While in the latter the photon emission is inherently stochastic, we were able to identify its imprints in comparison with the new developed semiclassical stochasticity-free method of radiative polarization applicable in the quantum regime. With an initially spin-polarized electron beam, the stochastic spin effects are seen in the dependence of the depolarization degree on the electron scattering angle and the electron final energy (spin stochastic diffusion). With an initially unpolarized electron beam, the spin stochasticity is exhibited in enhancing the known effect of splitting of the electron beam along the propagation direction into two oppositely polarized parts by an elliptically polarized laser pulse. The considered stochasticity effects for the spin are observable with currently achievable laser and electron beam parameters.

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. Keywords: Strong field QED, Polarized positrons, Multiphoton Breit-Wheeler pair production, Nonlinear Compton scattering

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.

For vacuum electron acceleration by a Gaussian beam, the energy gain of the electron is sensitively influenced by the initial parameters of the electron and the laser beam. It is necessary to find a group of optimized initial parameters to achieve the highest energy gain. The relationships between the initial parameters and the energy gains are investigated comprehensively by the global optimization method, and the global maximum as well as the local maxima is obtained. Via employing the global optimization of the initial parameters, more efficient electron acceleration has been achieved. Keywords: Electron acceleration, Gaussian beam, Global optimization

In this paper, an intelligent wireless sensor which is controlled by a single-chip microcomputer (SCM) is designed. This intelligent wireless sensor includes host and slave module. The device has the advantages of low cost, simple fabrication, high readability and accurate measurement, etc.

Spin-polarization effects of an ultrarelativistic electron beam head-on colliding with an ultraintense two-color laser pulse are investigated comprehensively in the quantum radiation-dominated regime. We employ a Monte Carlo method, derived from the recent work of [Phys. Rev. Lett. {\bf 122}, 154801 (2019)], to calculate the spin-resolved electron dynamics and photon emissions in the local constant field approximation. We find that electron radiation probabilities in adjacent half cycles of a two-color laser field are substantially asymmetric due to the asymmetric field strengths, and consequently, after interaction the electron beam can obtain a total polarization of about 11\% and a partial polarization of up to about 63\% because of radiative spin effects, with currently achievable laser facilities, which may be utilized in high-energy physics and nuclear physics. Moreover, the considered effects are shown to be crucially determined by the relative phase of the two-color laser field and robust with respect to other laser and electron beam parameters., 7 pages, 7 figures

The impact of the carrier-envelope phase (CEP) of a long relativistic tightly focused laser pulse on the dynamics of a counterpropagating electron beam has been investigated theoretically in the, so-called, electron reflection regime. Our semiclassical Monte Carlo simulations show that the electrons are reflected at the rising edge of the laser pulse due to the ponderomotive force of the focused laser beam, and an asymmetric electron-momentum distribution emerges along the laser polarization direction, which sensitively depends on the CEP of the driving laser pulse for weak radiative stochasticity effects. The CEP signatures can be determined in the electron-momentum distribution at laser intensities of the order or larger than ${10}^{19}\phantom{\rule{0.16em}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$ and for the pulse lengths up to 10 cycles. The CEP detection resolution is proportional to the electron beam density and can achieve approximately $0.{1}^{\ensuremath{\circ}}$ at an electron density of about ${10}^{15}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. The method is applicable for currently available ultraintense laser facilities with the laser peak power ranging from tens of terawatt to multipetawatt.

The impact of stochasticity effects (SEs) in photon emissions on the proton energy spectra during laser-plasma interaction is theoretically investigated in the quantum radiation-dominated regime, which may facilitate SEs experimental observation. We calculate the photon emissions quantum mechanically and the plasma dynamics semiclassically via two-dimensional particle-in-cell simulations. An ultrarelativistic plasma generated and driven by an ultraintense laser pulse head-on collides with another strong laser pulse, which decelerates the electrons due to radiation-reaction effect and results in a significant compression of the proton energy spectra because of the charge separation force. In the considered regime the SEs are demonstrated in the shift of the mean energy of the protons up to hundreds of MeV. This effect is robust with respect to the laser and target parameters and measurable in soon available strong laser facilities.

Dynamics of an electron beam head-on colliding with an ultraintense focused ultrashort circularly polarized laser pulse are investigated in the quantum radiation-dominated regime. Generally, the ponderomotive force of the laser fields may deflect the electrons transversely, to form a ring structure in the cross section of the electron beam. However, we find that when the Lorentz factor of the electron $\ensuremath{\gamma}$ is approximately one order of magnitude larger than the invariant laser field parameter $\ensuremath{\xi}$, the stochastic nature of the photon emission leads to electron aggregation abnormally inwards to the propagation axis of the laser pulse. Consequently, the electron angular distribution after the interaction exhibits a peak structure in the beam propagation direction, which is noticeably distinguished from the ``ring'' structure of the distribution in the classical regime and, therefore, can be recognized as a proof of the fundamental quantum stochastic nature of radiation. The stochasticity signature is robust with respect to the laser and electron parameters and observable with current experimental techniques.

The motion of two interactional solitons is investigated in nonlinear media with an exponential nonlocal response. A differential equation describing the motion trajectories of soliton center is proposed. Some numerical simulations are performed to illustrate the characteristics of the motion trajectories. The results show that the trajectories always oscillate periodically. However, if the two solitons are launched with a relative inclined angle which is larger than a critical value, they do not collide any more but diverge from each other. The critical angle is also given.

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.

Generation of high-flux vortex γ -ray pulses is investigated in the interaction of ultraintense Bessel–Bessel laser bullets colliding head-on with ultrarelativistic electron bunches in the quantum radiation-dominated regime. In the simulations, a semiclassical Monte–Carlo method is used, based on the radiation probabilities in the local constant field approximation, to describe the electron motion and emission of radiation. Characteristics of the driving laser pulse (orbital angular momentum and nondiffracting spatial and temporal structures) are transferred to the emitted γ rays by nonlinear Compton scattering.

Gamma-ray beams with a large angular momentum may affect astrophysical phenomena, which calls for appropriate earth-based experimental investigations. For this purpose, we investigate the generation of well-collimated γ-ray beams with a very large orbital angular momentum using nonlinear Compton scattering of a strong laser pulse of twisted photons at ultrarelativistic electrons. Angular momentum conservation among absorbed laser photons, quantum radiation, and electrons is numerically demonstrated in the quantum radiation-dominated regime. We point out that the angular momentum of the absorbed laser photons is not solely transferred to the emitted γ photons, but due to radiation reaction shared between the γ photons and interacting electrons. The efficiency of the angular momentum transfer is optimized with respect to the laser and electron beam parameters. The accompanying process of electron-positron pair production is furthermore shown to enhance the orbital angular momentum gained by the γ-ray beam.

Sensory navigation device is an important trend in the field of machine learning and data science. Nowadays, more and more sensory navigation devices are built for blind people. The core of such sensory navigation devices for blind people usually is implemented by an Image Recognition Method. To build an image recognition model, many tools and online machine learning platforms are proposed. However, these tools or platforms are not able to completely satisfy the requirements for sensory navigation device. To build a sensory navigation device with satisfying requirements for blind people, an ability of reducing the cost of model training and a capability of user-centric image recognition are the two main issues. Therefore, to address the above issues, we propose a novel approach, namely, DLSNF (Deep-Learning-based Sensory Navigation Framework). Our proposed DLSNF is built based on the YOLO architecture to deal with the reducing cost of model training and NVIDIA Jetson TX2 to take the user-centric image recognition into account. Based on our proposed DLSNF, the real-time image recognition can be trained well and conduct a sensory navigation to help blind people. At the same time, the train model is embedded in NVIDIA Jetson TX2 which is the fastest, most power-efficient embedded AI computing device. For the experiments, we evaluated our proposed DLSNF with a real-world dataset consisting of 4,570 images collected by part-time workers. The extensive experimental results show that our proposed DLSNF more effectively and efficiently beyond the existing baselines.

Direct laser acceleration of ions by short frequency chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1% can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies in the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e., higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

Signatures of stochastic effects in the radiation of a relativistic electron beam interacting with a counterpropagating superstrong short focused laser pulse are investigated in a quantum regime when the electron’s radiation dominates its dynamics. We consider the electron-laser interaction at near-reflection conditions when pronounced high-energy gamma-ray bursts arise in the backward-emission direction with respect to the initial motion of the electrons. The quantum stochastic nature of the gamma-photon emission is exhibited in the angular distributions of the radiation and explained in an intuitive picture. Although, the visibility of the stochasticity signatures depends on the laser and electron beam parameters, the signatures are of a qualitative nature and robust. The stochasticity, a fundamental quantum property of photon emission, should thus be measurable rather straightforwardly with laser technology available in near future.

We demonstrate the feasibility of generation of bright ultrashort gamma-ray pulses and the signatures of stochastic photon emission via the interaction of a relativistic electron bunch with a counterpropagating tightly-focused superstrong laser beam in the quantum-radiation-dominated regime. We consider the electron-laser interaction at near-reflection conditions when pronounced high-energy gamma-ray bursts arise in the backward-emission direction with respect to the initial motion of the electrons. The Compton scattering spectra of gamma-radiation are investigated using a semiclassical description for the electron dynamics in the laser field and a quantum electrodynamical description for the photon emission. We demonstrate the feasibility of ultrashort gamma-ray bursts of hundreds of attoseconds and of dozens of megaelectronvolt photon energies in the near-backwards direction of the initial electron motion. The tightly focused laser field structure and radiation reaction are shown to be responsible for such short gamma-ray bursts, which are independent of the durations of the electron bunch and of the laser pulse. Moreover, the quantum stochastic nature of the gamma-photon emission is exhibited in the angular distributions of the radiation and explained in an intuitive picture. Although, the visibility of the stochasticity signatures depends on the laser and electron beam parameters, the signatures are of a qualitative nature and robust. The stochasticity, a fundamental quantum property of photon emission, should thus be measurable rather straightforwardly with laser technology available in near future.

The impact of stochasticity effects (SEs) in photon emissions on the proton energy spectra during laser-plasma interaction is theoretically investigated in the quantum radiation-dominated regime. We calculate the photon emissions quantum mechanically and the plasma dynamics semiclassically via two-dimensional particle-in-cell simulations. An ultrarelativistic plasma generated and driven by an ultraintense laser pulse head-on collides with another strong laser pulse, which decelerates the electrons due to radiation-reaction effect and results in a significant compression of the proton energy spectra because of the charge separation force. In the considered regime the SEs are demonstrated in the shift of the mean energy of the protons up to hundreds of MeV. This effect is robust with respect to the laser and target parameters and measurable in soon available strong laser facilities.

In this study, we sequenced plastid DNA to investigate the interspecific relationships of Stemona species . In total, 34 individuals from 23 populations were studied, covering the geographical range of Stemona in China plus eight individuals from Indonesia. Our results show that seven Stemona species cluster into three major clades; S. parviflora is closest to S. javanica of the species studied; it is reasonable to treat S. shandongensis as a synonym of S. sessilifolia , whereas S. japonica is close to S. sessilifolia ; the geographically widespread species S. tuberosa possesses a high degree of differentiation and contains three subgroups.

The real-time monitoring technologies of smart civil structure based on detecting picometer-scale wavelength shift of fiber Bragg grating (FBG), including the wavelength demodulation technology of FBG, are researched extensively at home and abroad. In the paper, using the technologies of wavelength division multiplex (WDM) and time division multiplex (TDM), fiber Bragg grating (FBG) sensor network was built for monitoring smart structure health condition. Based on SOPC (System on Programmable Chip) technology and fiber comb filter, a high-speed and high-precision wavelength demodulation scheme of FBG sensor network was proposed. The optical system and hardware circuit for demodulation system were designed specifically. To improve the accuracy of demodulation system of FBG, a constant temperature channel of the demodulation system connected with a fiber comb filter, which offered reference points to calibrate the Bragg grating center wavelength. Based on 32-bit soft-core processor NoisⅡ, the embedded system collected and processed the photoelectric signal voltage transformed to rectangular voltage pulse. The upper computer displayed dynamically the FBG wavelength demodulation process and calibrated the Bragg grating center wavelength. The experiments of FBG wavelength demodulation and health monitoring of smart structural embedded fiber Bragg gratings were done. Experimental results show that, the FBG wavelength demodulation method can be used to demodulate the FBG wavelength with high speed and high precision (± 2 pm), which can be used extensively in large-scale multipoint monitor engineering, and the strains of the smart structure can be measured accurately.

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. Keywords: Interaction, Anomalous vortex beam, Nonlocal media

The sequence of aeolian red clay and loess deposited in northern China since late Neogene is an ideal palaeoclimate recorder. A profile consisting of loess, lacustrine deposits and red clay was found at Wuqi County in the northern Chinese Loess Plateau. Preliminary investigations were carried out on the typical Tufosi section in order to provide the age constraints of the lacustrine deposits (namely the Wuqi paleolake). Rock magnetic results demonstrate that the magnetic carriers of the characteristic remanent magnetization of lacustrine deposits are mainly magnetite and hematite. The correlation between the magnetic polarity sequence of the Tufosi section and geomagnetic polarity time scale is very well. The age of the bottom of the section is 4.28 Ma B. P. approximately. The Wuqi paleolake formed at about 3.0 Ma B. P. and died out around 1.2 Ma B. P. The regional environment became colder and drier during this period as implied by the variations of lithology, magnetic susceptibility, grain size and sedimentation rates. The evolution history of the Wuqi paleolake can be divided into three stages: the paleolake was formed during the period of 3.0~2.5 Ma B. P. and the water body was relatively deep; the lake became shallow markedly as the result of paleoclimate change during 2.50~2.05 Ma B. P.; during 2.05~1.20 Ma B. P., reduction of the water body led to the extinction of the lake. Climatic deterioration in this region around 1.2 Ma B. P. was the main reason for the end of the Wuqi paleolake. Besides, the headward erosion of the North Luo River caused by regional tectonism was probably a factor, too.