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The creation of high-energy-density (≳ 10 6 joules per cm3) over-critical plasmas in a large volume has essential applications in the study of warm dense matter, being present in the hot cores of stars and planets. It was recently shown that femtosecond Bessel beams enable creating over-critical plasmas inside sapphire with sub-wavelength radius and several tens of micrometers in length. Here, the dependence of field structure and absorption mechanism on the plasma density transverse profile are investigated by performing self-consistent Particle-In-Cell (PIC) simulations. Two limiting cases are considered: one is a homogeneous step-like profile that can sustain plasmon formation, and the second is an inhomogeneous Gaussian profile, where resonance absorption occurs. Comparing experimental absorption measures to analytical predictions allows determining the plasma parameters used in PIC simulations. The PIC simulation results are in good agreement with experimental diagnostics of total absorption, near-field fluence distribution, and far-field radiation pattern. We show that in each case, an ambipolar field forms at the plasma surface due to the expansion of the hot electrons and that electron sound waves propagate into the over-critical region. [ABSTRACT FROM AUTHOR]

We show that a product of two Laguerre–Gaussian (pLG) beams can be expressed as a finite superposition of conventional LG beams with particular coefficients. Based on such an approach, an explicit relationship is derived for the complex amplitude of pLG beams in the Fresnel diffraction zone. Two identical LG beams of the duet produce a particular case of a "squared" Fourier-invariant LG beam, termed as an (LG)2 beam. For a particular case of pLG beams described by Laguerre polynomials with azimuthal numbers n − m and n + m, an explicit expression for the complex amplitude in a Fourier plane is derived. Similar to conventional LG beams, the pLG beams can be utilized for information transmission, as they are characterized by orthogonal azimuthal numbers and carry an orbital angular momentum equal to their topological charge. [ABSTRACT FROM AUTHOR]

A method to design the metasurface‐based splitter with dual beams which have different power distributions, polarizations, and radiated angles is proposed. The presented metasurface is ultrathin which is only 0.12λ and the whole unit cell is mainly composed of receiving antenna with single‐polarization, power divider, dual‐channel phase shifter with independent control and transmitting antenna with dual‐polarization. According to the functional requirements of the beam splitter, the main components which are power divider and phase shifter can be artificially tailored correspondingly. And the fixed design of receiving and transmitting antennas can receive the incident electromagnetic (EM) wave with single‐polarization and transmit the EM wave with dual‐polarization, respectively. Comparing with conventional cascaded transmitarray and bulk lens, the design logic of proposed whole splitter is very clear that scanning and optimizing massive parameters of unit cells for satisfying the demands of polarization, transmission phase, and power distribution simultaneously is not needed. The good consistent results of experiment and simulation can verify the validity of our design. [ABSTRACT FROM AUTHOR]

For the optimal design and accurate prediction of structural behavior, the nonlinear analysis of large deformation of elastic beams has broad applications in various engineering fields. In this study, the nonlinear equation of flexure of an elastic beam, also known as an elastica, was solved by the Galerkin method for a highly accurate solution. The numerical results showed that the third-order solution of the rotation angle at the free end of the beam is more accurate and efficient in comparison with results of other approximate methods, and is perfectly consistent with the exact solution in elliptic functions. A general procedure with the Galerkin method is demonstrated for efficient solutions of nonlinear differential equations with the potential for adoption and implementation in more applications. [ABSTRACT FROM AUTHOR]

A zeroth-order, non-diffracting Bessel beam, generated by picosecond laser pulses (1064 nm, 10 Hz, 30 ps) through an axicon, was utilized to perform pulse energy-dependent (12 mJ, 16 mJ, 20 mJ, 24 mJ) laser ablation of silver (Ag) substrates in air. The fabrication resulted in finger-like Ag nanostructures (NSs) in the sub-200 nm domain and obtained structures were characterized using the FESEM and AFM techniques. Subsequently, we employed those Ag NSs in surface-enhanced Raman spectroscopy (SERS) studies achieving promising sensing results towards trace-level detection of six different hazardous materials (explosive molecules of picric acid (PA) and ammonium nitrate (AN), a pesticide thiram (TH) and the dye molecules of Methylene Blue (MB), Malachite Green (MG), and Nile Blue (NB)) along with a biomolecule (hen egg white lysozyme (HEWL)). The remarkably superior plasmonic behaviour exhibited by the AgNS corresponding to 16 mJ pulse ablation energy was further explored. To accomplish a real-time application-oriented understanding, time-dependent studies were performed utilizing the AgNS prepared with 16 mJ and TH molecule by collecting the SERS data periodically for up to 120 days. The coated AgNSs were prepared with optimized gold (Au) deposition, accomplishing a much lower trace detection in the case of thiram (~50 pM compared to ~50 nM achieved prior to the coating) as well as superior EF up to ~108 (~106 before Au coating). Additionally, these substrates have demonstrated superior stability compared to those obtained before Au coating. [ABSTRACT FROM AUTHOR]

By contrast, topology-shape optimization only modifies the boundary position of unit structure while keeping the topology shape unchanged during the optimization process, which is more compatible with practical fabrication [[37]]. Keywords: extended depth-of-focus; metalens; topology optimization EN extended depth-of-focus metalens topology optimization 2967 2975 9 05/26/22 20220615 NES 220615 1 Introduction Over the past decades, the longitudinal optical field has attracted considerable attentions due to its extraordinary capability for optical manipulation. 2 Principle of topology-shape optimization 2.1 Variable focal-length phase To obtain an extended DOF while maintaining high efficiency, a variable focal-length phase is adopted as the theoretical phase distribution. [Extracted from the article]

Photoacoustic microscopy (PAM) is an emerging biomedical imaging modality, combining good acoustic resolution in deep tissue and rich functional biomedical information. Spatial resolution and spatial isotropy are two of the most important indexes of a PAM. In this study, we propose a PAM scheme based on an aspheric acoustic mirror group to achieve the subwavelength resolution and enhance the spatial isotropy. The mirror group consists of an ellipsoid acoustic mirror and a parabolic acoustic mirror. The ellipsoid acoustic mirror expands the cone angle of signal collection, and the parabolic acoustic mirror reduces the cone angle of the PA beam. Their combination equivalently expands the numerical aperture of acoustic detection. Phantom experiments demonstrate that the proposed scheme can achieve the subwavelength resolution. Simultaneously, its spatial isotropy is improved from 48.2% to 96.7%. An in vivo mouse brain imaging experiment examines the biomedical practicability of the method. This method may be found wide potential applications in biomedicine. [ABSTRACT FROM AUTHOR]

The large deflections of cantilevered beams and rectangular plates are modeled and discussed. Traditional nonlinear elastic models (e.g., von Karman's) employ elastic restoring forces based on the effect of stretching on bending, and these are less applicable to cantilevers. Recent experimental work indicates that elastic cantilevers are subject to nonlinear inertial and stiffness effects. We review a recently established (quasilinear and nonlocal) cantilevered beam model, and consider some extensions to two spatial dimensions, namely inextensible plates. Our principal configuration is that of a thin, isotropic, homogeneous rectangular plate, clamped on the one edge and free on the remaining three. We proceed through the geometric and elastic modeling to obtain equations of motion via Hamilton's principle for the appropriately specified energies. We then enforce effective inextensibility constraints through Lagrange multipliers. Multiple plate analogs of the established 1D model are obtained, based on assumptions. In total, we present three distinct nonlinear partial differential equation models and, additionally, describe a class of "higher-order" models. Each model has particular advantages and drawbacks for both mathematical and engineering analyses. We conclude with a discussion of the various models, as well as some analytical problems. [ABSTRACT FROM AUTHOR]

Dammann gratings conceived earlier are designed using iterative procedures to produce equal intensity light spots. In this paper, we show a novel method to design a Dammann grating by solving optimization problem. We solve the optimization problem by a grid search method with resolution determined by fabrication capabilities. The grid-search method utilizes a cost function to find the phase transition points in the unit cell of a Dammann grating, thereby maximizing the throughput. Since the goal in previously designed gratings is to produce required intensity pattern, other parameters of light such as phase and polarization were not expected to maintain any structure in the diffraction pattern and were considered as free parameters during design. We observe that the element preserves the topological features of the incident light in each of its diffracted orders. We show that Dammann grating when illuminated by a V-point polarization singularity of different Poincaré–Hopf index values, produces multiple beam-lets each containing same polarization distribution as that of the incident V-point. The experimentally obtained array structures are in concordance with the simulations. [ABSTRACT FROM AUTHOR]

A noniterative approach to generation of binary phase holograms is applied for synthesizing complex optical vortex arrays. This approach does not use inverse Fourier analysis and allows one to obtain arbitrary optical vortex arrays with specified topological charges, which cannot be obtained using conventional fork‐shaped gratings. A topological charge of individual optical vortices generated using binary phase holograms can be specified at a given spatial frequency, so that the equidistant array of optical vortices can be generated via illuminating a hologram by a beam with the zero topological charge. The results of the calculation are consistent with the experimental data, including those of the interferometric measurements. The approach also makes it possible to synthesize superimposed optical vortices, where an optical field represents well‐ordered circular arrays of optical singularities. An unusual behavior of phase dislocations in superimposed structures is found. For two optical vortices of same reciprocal lattice vectors, but different topological charges, spatial distribution of singularities are reconfigured in a such manner that a couple of concentric circular arrays of singularities appear. The proposed binary phase holograms offer new opportunities for synthesizing the complex optical vortex light fields, which can find light–matter interaction‐based applications. [ABSTRACT FROM AUTHOR]

This paper provides an analytic method to study propagation characteristics of a linearly polarized Bessel vortex beam through a homogeneous magnetized plasma slab. The incident Bessel vortex beam, as well as the reflected, transmitted and internal fields are expanded in terms of cylindrical vector wave functions (CVWFs). The effects of plasma thickness, electron density and magnetic induction strength on the contour profiles of the reflected and transmitted beams and orbital angular momentum (OAM) spectra are analyzed and discussed in detail. In particular, the magnetic induction strength has a significant impact on the polarization of the transmitted beam, but not on OAM state distribution. The channel capacity of THz OAM multiplexing decreases with an increase of plasma thickness and electron density. [ABSTRACT FROM AUTHOR]

We present two new models for dynamic beams deduced from three dimensional theory of linear elasticity. The first model is deduced from virtual work considered for small beam sections. For the second model, we suppose a Taylor-Young expansion of the displacement field up to the fourth order in transverse dimensions of the beam. We consider the Fourier series expansion for considering Neumann lateral boundary conditions together with dynamical equations, we obtain a system of fifteen vector equations with the fifteen coefficients vector unknown of the displacement field. For beams with two fold symmetric cross sections commonly used (for example circular, square, rectangular, elliptical...), a unique decomposition of any three-dimensional loads is proposed and the symmetries of these loads is introduced. For these two theories, we show that the initial problem decouples into four subproblems. For an orthotropic material, these four subproblems are completely independent. For a monoclinic material, two subproblems are coupled and independent of the two other coupled subproblems. For the first model, we also give the detailed expression of these four subproblems when we consider the approximation of the displacement field used in the second model. [ABSTRACT FROM AUTHOR]

With its elongated depth of focus, Bessel beams offer rapid and high aspect ratio ablation capability, in contrast to Gaussian beam counterparts. In this study, we summarize our efforts in design and characterization of a half-inch diameter probe comprising a hollow core photonics crystal fiber for ultrafast laser delivery, an aspherical lens to collimate the light exiting fiber output, an axicon to generate the Bessel beam, and a relay lens pair to establish a narrow main lobe for improved laser fluence. We discuss two main challenges in transferring the available laser energy to the target: i) fiber damage and ii) energy wasted at the Bessel side-lobes. Solutions that have been proposed in other bench top literary studies are revisited in terms of their practical and realistic adaptation within a probe for potential clinical use. With further development, the proposed Bessel-beam based probe can be targeted for minimally invasive in-vivo activation of follicles for the treatment of premature ovarian failure, potentially leading to shortened healing duration and improved patient comfort. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the morphologic characteristics of the lingual foramen and lateral lingual foramen using cone-beam CT in elderly Korean. Cone-beam CT images were obtained from 80 Korean older than 50 years (mean age, 65.2 years). The prevalence of the lingual and lateral lingual foramina at the lingual aspect of the mandible was determined. The diameter and height to the upper margin of the foramina from the mandibular inferior margin, and the bone height to the alveolar crest from the mandibular inferior margin were measured. In addition, the location of the lateral lingual foramen, the direction of its canal, and the presence of communication with the mandibular canal were evaluated. All of elderly Korean possessed at least one lingual foramen, with two or three foramina occurring in 77.5 % of Korean. A lateral lingual foramen was observed in 91.3 % of Korean, with the prevalence being highest at the second premolar in dentulous cases (21.6 %; 33/153). The very high frequencies of these foramina were attributable to high frequencies of relatively small-diameter inferior lingual foramen and lateral lingual foramen in the incisor region. The prevalence of a large-diameter (³1 mm) superior lingual foramen was high, at 31.0 %. A large-diameter lateral lingual foramen in the premolar region occurred at a frequency of 17.0 %; communication with the mandibular canal was observed in 70.0 % of these cases. These quantitative data on the lingual and lateral lingual foramina of the mandible provide valuable information that could help to avoid surgical complications during implant placement in elderly Korean. [ABSTRACT FROM AUTHOR]

Background: During a course of radiation therapy, anatomical changes such as a decrease in tumour size or weight loss can trigger the need for repeating a computed tomography (CT) simulation scan in order to generate a new treatment plan. This adaptive approach requires a separate appointment for an additional CT scan which generates additional burden, cost, and radiation exposure for patients. Case Presentation: Here, we present a case of a head and neck cancer patient who required palliative radiation for a large neck mass. During treatment, he had a remarkable response which required a replan due to rapid tumour downsizing. In this case, we used a novel technique to avoid repeating the planning CT simulation by using a mid‐treatment high‐quality cone beam CT (CBCT) to deform the secondary image (plan CT) of the original planning CT and generate a new adapted treatment plan. Conclusion: This is the first report to our knowledge using a Halcyon CBCT to deform the original planning CT in order to generate a new radiation treatment plan, and this novel technique represents a new potential method of adaptive replanning for select patients. [ABSTRACT FROM AUTHOR]

Objective: Cone‐beam computed tomography (CBCT) is a promising imaging modality for sinonasal evaluation, with advantages of relatively low radiation dose, low cost, and quick outpatient imaging. Our study aimed to compare the diagnostic performance and image quality of CBCT with those of multi‐detector computed tomography (MDCT) with different slice thickness. Methods: We retrospectively reviewed 60 consecutive patients who had undergone both CBCT and MDCT. MDCT images was reconstructed with 1 and 3 mm slice thickness. The quantitative image quality parameters (image noise, signal‐to‐noise ratio [SNR], and contrast‐to noise ratio [CNR] were calculated and compared between the two imaging modalities. Two observers (ENT surgeon and neuroradiologist) evaluated the presence of seven sinonasal anatomic variations in each patient and interobserver agreements were analyzed. The diagnostic performance of CBCT (0.3 mm) and MDCT (3 mm) was assessed and compared with that of high resolution MDCT (1 mm), which is considered as the gold standard. Results: The image noise was significantly higher and SNR and CNR values were lower in the CBCT (0.3 mm) group than in the MDCT groups (1 and 3 mm). The diagnostic performance of CBCT (0.3 mm) was similar to that of MDCT (1 mm) and superior to that of MDCT (3 mm). The highest interobserver agreement was for high resolution MDCT (1 mm), followed by CBCT (0.3 mm), and MDCT (3 mm). Conclusion: Considering its low radiation dose, low cost, and ease of clinical access, CBCT may be a useful imaging modality for as first line sinonasal evaluation and repeated follow up. Study design: Retrospective study in a tertiary referral university center. Level of evidence: NA. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate dosimetric changes detected using synthetic computed tomography (sCT) derived from online cone‐beam CTs (CBCT) in pediatric patients treated using intensity‐modulated proton therapy (IMPT). Methods: Ten pediatric patients undergoing IMPT and aligned daily using proton gantry‐mounted CBCT were identified for retrospective analysis with treated anatomical sites fully encompassed in the CBCT field of view. Dates were identified when the patient received both a CBCT and a quality assurance CT (qCT) for routine dosimetric evaluation. sCTs were generated based on a deformable registration between the initial plan CT (pCT) and CBCT. The clinical IMPT plans were re‐computed on the same day qCT and sCT, and dosimetric changes due to tissue change or response from the initial plan were computed using each image. Linear regression analysis was performed to determine the correlation between dosimetric changes detected using the qCT and the sCT. Gamma analysis was also used to compare the dose distributions computed on the qCT and sCT. Results: The correlation coefficients (p‐values) between qCTs and sCTs for changes detected in target coverage, overall maximum dose, and organ at risk dose were 0.97 (<.001), 0.84 (.002) and 0.91 (<.001), respectively. Mean ± SD gamma pass rates of the sCT‐based dose compared to the qCT‐based dose at 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria were 96.5%±4.5%, 93.2%±6.3%, and 91.3%±7.8%, respectively. Pass rates tended to be lower for targets near lung. Conclusion: While insufficient for re‐planning, sCTs provide approximate dosimetry without administering additional imaging dose in pediatric patients undergoing IMPT. Dosimetric changes detected using sCTs are correlated with changes detected using clinically‐standard qCTs; however, residual differences in dosimetry remain a limitation. Further improvements in sCT image quality may both improve online dosimetric evaluation and reduce imaging dose for pediatric patients by reducing the need for routine qCTs. [ABSTRACT FROM AUTHOR]

Cracks in structural components may ultimately lead to failure of the structure if not identified sufficiently early. This paper presents a crack-identification method based on time-domain. Captured time-domain data are processed into central difference approximation of displacement of each node (point) in the structure. Abnormally high central difference approximation of displacement of a node relative to those of its neighborhood points indicates a crack at that point. A suite of simulation experiments and numerical calculations was conducted to find out whether the proposed identification method could accurately identify the location of a crack in a cantilever beam under moving load compared to the location found by an exact solution method, and the outcomes indicated that it was as able as the analytical method. The proposed method is an FEA analysis, an approach familiar to virtually every engineer. Therefore, the relative amount of time and effort spent on developing the proposed method for a specific application is much less than those spent on developing an analytical method. The saved time and effort should enable more engineering personnel to perform routine checks on structural elements of their interest more simply and frequently. [ABSTRACT FROM AUTHOR]

Light‐sheet fluorescence microscopy (LSFM) is useful for developmental biology studies, which require a simultaneous visualization of dynamic microstructures over large fields of views (FOVs). A comparative study between multicolor Bessel and Gaussian‐based LSFM systems is presented. Discussing the chromatic implications to achieve colocalized and large FOVs when both optical arrays are implemented under the same excitation objective is the purpose of this work. The light‐sheets FOVs, optical sectioning, and resolution are experimentally characterized and discussed. The advantages of using Bessel beams and the main drawbacks of using Gaussian beams for multicolor imaging are highlighted. Multiple Bessel excitation minimizes the FOV's mismatch's effects due to the beams chromatic defocusing and alleviates the aside object blurring obtained with multiple Gaussian beams. It also offers a fair homogeneous axial resolution and optical sectioning over a larger effective FOV. Imaging over perithecia samples of the fungus Sordaria macrospora demonstrates such advantages. This work complements previous comparative studies that discuss only single wavelengths light‐sheets excitations. [ABSTRACT FROM AUTHOR]

In this paper, we consider a new type of Bessel beams having Fourier-invariance property and, therefore, called Fourier-Bessel beams. In contrast to the known Bessel beams, these beams have weak side lobes. Analytical expressions for the complex amplitude of the proposed field in the initial plane of the source and in the far field region have been obtained. It is shown that the proposed Fourier-Bessel beams have a finite energy, although they do not have a Gaussian envelope. Their complex amplitude is proportional to a fractional-order Bessel function (an odd integer divided by 6) in the initial plane and in the Fraunhofer zone. The Fourier-Bessel modes have a smaller internal dark spot compared to the Laguerre-Gauss modes with a zero radial index. The proposed beams can be generated with a spatial light modulator and may find uses in telecommunications, interferometry, and the capture of metal microparticles.

• An ultra-thin binary ultrasonic lens can convert plane waves into Bessel-like beams. • Varying the incident wave's frequency can adjust the long-axis focusing point. • The beam from the binary ultrasonic lens can create a focused sound field in multi-layered tissues. Bessel beams have already been used in acoustic tweezers, ultrasonic medical imaging, and Doppler velocity estimation due to their non-diffractive and self-healing properties. We proposed a binary ultrasonic lens, with ultra-thin planar periodic structures for efficient conversion of the plane wave into a Bessel-like beam. The effectiveness of long-axis focusing has been demonstrated through simulations and experiments with FWHM of 8.5 mm and 9.5 mm around 10 mm. By varying the operating frequency of the incident wave from 1.9 MHz to 2.2 MHz, the position of the long-axis focusing point can be adjusted experimentally from 23.05 mm to 28.95 mm. Additionally, the beam generated by the binary ultrasonic lens can form a focused sound field when passing through multi-layered tissues and the self-healing capability of the Bessel-like beam has been numerically validated, showing strong robustness. This binary ultrasonic lens for a Bessel-like beam would conform better to ergonomic and miniaturization requirements, and expand versatile applications in clinical diagnosis and therapy. [ABSTRACT FROM AUTHOR]

• The high-fidelity higher-order Bessel beams (HHBBs) are generated experimentally. • The complex amplitude distribution of the HHBB is highly consistent with the theoretical expression of the corresponding higher-order Bessel beam. • The generated HHBBs have enhanced diffraction-free distances compared to the conventionally generated higher-order Bessel beams. It is known that the Bessel beams are the solution to the Helmholtz equation, whose amplitude distributions should be strictly conformed with the Bessel functions of the first kind. In addition, the higher-order Bessel beams have helical phases of the same-order topological charges. However, the common methods can only generate approximate higher-order Bessel beams whose diffraction-free distances are shortened. In this paper, we introduce the concept of the high-fidelity higher-order Bessel beam (HHBB), a generated beam whose complex amplitude distribution is highly consistent with the theoretical expression of the corresponding higher-order Bessel beam. The generated HHBBs have the advantages of more compatible complex amplitude distributions with the corresponding theoretical expressions and enhanced diffraction-free distances which have potential applications in optical manipulation, laser processing, and high-resolution optical imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new strategy for preparing superhydrophobic and anti icing surfaces using Bessel beam & fluorination treatment has been proposed. • We realized the high-quality, high-precision, and large-area consistent manufacturing of 3D micro-nano-structures. • Fs-Superalloy&Fluorination surface exhibits excellent superhydrophobic properties. • Fs-Superalloy&Fluorination surface exhibits excellent static and dynamic anti icing characteristics. This study proposes a simple strategy for overcoming the adverse effects of icing on material surfaces and improving the anti-icing performance of these surfaces. First, a femtosecond Gaussian beam is transformed into a femtosecond Bessel beam through spatial shaping to improve its energy distribution in the propagation direction while avoiding the adverse effects of defocusing during processing, thereby achieving large-area, consistent micro-nano-fabrication. Subsequently, the surface wettability of the considered material is controlled through the preparation of a functionalized three-dimensional micro-nano-structure using fluorination, transforming the material surface from superhydrophilic to superhydrophobic, thereby directly preventing the adhesion of subcooled droplets. Static-droplet condensation tests and dynamic anti-icing tests in simulated freezing-rain environments demonstrated that the proposed strategy can considerably increase the droplet condensation time and reduce the amount of surface icing. Overall, the strategy provides an efficient, high-quality, highly reproducible solution to the problem of surface icing. [ABSTRACT FROM AUTHOR]

• We propose a new deep operator network architecture, Res-DeepONet, for rapidly accelerating the solution of the bioheat transfer equation with parameterized laser heating source terms. • In comparison to DeepONets leveraging traditional feedforward network architectures, Res-DeepONet exhibits a 10 × improvement in predictive accuracy on our test dataset. • Zero-shot performance studies with Bessel beam profiles despite training using Gaussian beam profiles show a 50 × enhancement in extrapolation capabilities, when compared to feedforward network-based DeepONets. • In comparison to classical implicit finite difference solvers, we observed a speedup by two orders of magnitude for our foundational 1D transient case setup. Such an improvement in computation time is expected to be even more significant for higher dimensional problems. • Lastly, our model benchmarking studies show that the Res-DeepONet architecture is capable of accurately predicting the solution of any parabolic partial differential equation beyond the bioheat transfer equation. To numerically characterize optothermal interactions at the laser-tissue interface during tissue imaging or surgery, the bioheat transfer partial differential equation (PDE) needs to be solved with a laser excitation source function. Considering various possible experimental scenarios, the PDEs become parametric and need to be solved for several optical and laser parameters. Classical numerical solvers that are used for performing such simulations are computationally expensive and time consuming. In this work, we use the recent deep operator network (DeepONet) framework for learning the mapping between infinite dimensional function spaces of the parameterized laser source functions and the solutions of the parameterized bioheat transfer PDE. We propose a new neural network architecture, Res-DeepONet, for training a purely physics-informed DeepONet with laser heating functions comprising of Gaussian beam profiles. We also showcase the versatility and robustness of our network architecture within purely data-driven and hybrid training frameworks for applications where labeled ground truth data may be accessible. The proposed neural network architecture exhibits excellent generalization performance on unseen Gaussian source functions with 10 × higher accuracy when compared to traditional feedforward network architectures. Furthermore, zero-shot performance studies highlight the exceptional extrapolation capabilities of our network with 50 × higher accuracy compared to traditional DeepONet architectures at inference times that are two orders of magnitude faster than classical solvers. [ABSTRACT FROM AUTHOR]

Based on the original concept of optical frozen waves—one-dimensional structured threads of light constructed from Bessel beams—an approach to construct longitudinally structured light sheets inside the last layer of a lossless stratified structure is analytically presented. The resulting bi-dimensional beam is able to be structured after suffering multiple transmissions and reflections. A procedure to overcome the natural periodicity of ideal "frozen wave"-type beams inside the stratified structure is also proposed. Examples of field reconstructions are provided for two- and N -layer media which show that the proposed method is capable to recreate surface intensity patterns, in the millimeter domain, with good fidelity and contrast even after the generated beam had crossed an arbitrary number of layers. Applications may include optical trapping and manipulation, volumetric displays, biomedical procedures, and so on. • "Frozen wave"-type light-sheets have been studied exclusively in single media. • The propagation of such waves in stratified media is here studied for the first time. • The formalism employs a transfer-matrix method for beams in inhomogeneous structures. • Simulations of beams resisting multiple transmissions and reflections are given. • The diffraction-resistant beams are also resistant to propagation in stratified media. [ABSTRACT FROM AUTHOR]

• A new type of gradually-changing period annular radial grating is designed to measure and characterize nonzero radial-index LG beam. • After the phase correction pattern shaping, the detection spot presents a new style, which is convenient for measurement. • The grating combined with phase correction diagram can improve the maximum measurement order of vortex beam to l = 20 , p = 20. The utilization of the radial index of a vortex beam for information transmission has significant potential for enhancing the communication system capacity and communication rates. In this study, we propose a simple and efficient approach to characterize nonzero radial-index vortex beams using a gradually changing-period annular radial grating, which enables improved detection accuracy by shaping the diffracted spot with a phase-correction diagram. The simulation results demonstrate that the far-field diffraction pattern exhibits a two-dimensional array of spots with l + p + 1 · p + 1 when the beam is diffracted at different positions on the grating. The radial index and topological charge of the incident vortex beam can be obtained by analyzing the distribution rule and orientation of the spot array. Finally, the diffracted spot array is shaped using a phase-corrected diagram, and the vortex beam order up to l = 20 , p = 20 was measured. The feasibility of this method is verified experimentally. This study also provides a valuable exploration of the subsequent development of multi-dimensional orbital angular momentum (OAM)multiplexed communication. [ABSTRACT FROM AUTHOR]

As a powerful supplement to the wireless communication, free space optical (FSO) communication has many advantages, but the high-precision time-frequency transmission based on FSO communication is limited by complex equipment factors, especially under the condition of limited communication bandwidth. In this paper, a high-precision frequency transfer system based on a tunable optical field is established. Theoretical analysis yields the detection probability and intensity distribution of Bessel beams. In experiments, Bessel beams generated through optical field modulation exhibit enhanced laser data communication capabilities, achieving high-precision frequency transfer at 2e-12@1s, 3.3e-14@1000s,. This research introduces a novel approach for designing and optimizing frequency transfer methods between smaller platforms in the future. • A high-precision frequency transfer system based on a tunable optical field is established. • An innovative coding scheme is proposed for frequency standard data fusion transmission to avoid redundant coding. • Theoretical and experimental analysis of time-frequency transmission by light field modulation. • Optical field control is realized under the condition of limited communication bandwidth. [ABSTRACT FROM AUTHOR]

In the present work, we have fabricated a novel plasmonic multi-metal nanoalloy colloid engaging a less-explored and versatile femtosecond (fs) Bessel beam ablation technique. A thorough morphological, elemental characterization has been performed with transmission electron microscope (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy (EDX) measurements. The nanoalloys were engaged in SERS-based sensing studies, efficiently detecting traces of RDX (5 μM) and PA (500 nM), two explosive molecules. The computed enhancement factor (EF) values for RDX and PA were determined to be 1.7 × 104 and 2.4 × 105, respectively. The nanoalloy particles (NAPs) were also probed with fs pulses, revealing a domineering three-photon absorption (3 PA) phenomenon in the open aperture Z-scan measurements. The 3 PA coefficient (γ) value has been extracted to be 1.8 × 10−22 cm3/W2, and the nonlinear refraction (NLR) coefficient n 2 value was 1.1 × 10−15 cm2/W. Further, the 3 PA cross-section (σ 3) was estimated to be 1.9 × 10−75 cm6/s2. Additionally, we have demonstrated the optical limiting capability of these nanoalloys. We also performed fs transient absorption spectroscopy (fs TAS), revealing the time-resolved response of the photoexcited electrons in this nanoalloy system. The photoexcited processes of electron-electron/thermalization (τ e-e = 0.7 ± 0.1 ps), electron-phonon (τ e-ph = 1.2 ± 0.1 ps), and phonon-phonon scattering (τ ph-ph = 47.5 ± 8 ps) were retrieved from the TAS data and fit. Several additional aspects of the nanoalloy system, such as interband-excitation-induced plasmon (EIP), delayed ESA band lifetime, and bleach splitting, were systematically understood through the TAS measurements. The results from this study advocate the advantages of the fs BB-induced ablation technique in fabricating novel, multi-metal plasmonic nanoalloys and establish its potential applications in a wide range of fields, including sensors, photonics, and optical limiting. [Display omitted] • Multi-metal nanoalloy particles' colloid fabricated using femtosecond Bessel beam. • We detected traces of RDX (5 μM) and PA (500 nM), real-time explosive molecules. • The computed EFs' values for RDX and PA were 1.7 × 104 and 2.4 × 105, respectively. • 3 PA coefficient value was extraced to be 1.8 × 10−22 cm3/W2. • Electron-electron (1.5 ps) and electron-phonon scattering (52.5 ps) times were obtained. [ABSTRACT FROM AUTHOR]

We present the fabrication of conductive graphitic microelectrodes in diamond by using pulsed Bessel beams in the burst mode laser writing regime. The graphitic wires are created in the bulk of a 500 μm thick monocrystalline HPHT diamond (with (100) orientation) perpendicular to the sample surface, without beam scanning or sample translation. In particular, the role of different burst features in the resistivity of such electrodes is investigated for two very different sub-pulse durations namely 200 fs and 10 ps, together with the role of thermal annealing. Micro-Raman spectroscopy is implemented to investigate the laser-induced crystalline modification, and the results obtained by using two different laser repetition rates, namely 20 Hz and 200 kHz, are compared. A comparison of the micro-Raman spectra and of the resistivity of the electrodes fabricated respectively with 10 ps single pulses and with bursts (of sub-pulses) of similar total duration has also been made, and we show that the burst mode writing regime allows to fabricate more conductive micro electrodes, thanks to the heat accumulation process leading to stronger graphitization. Moreover, the microfabrication of diamond by means of the longest available bursts (~ 46.7 ps duration) featured by 32 sub-pulses of 200 fs duration, with intra-burst time delay of 1.5 ps (sub-THz bursts), leads to graphitic wires with the lowest resistivity values obtained in this work, especially at low repetition rate such as 20 Hz. Indeed, micro electrodes with resistivity on the order of 0.01 Ω cm can be fabricated by Bessel beams in the burst mode regime even when the bursts are constituted by femtosecond laser sub-pulses, in contrast with the results of the standard writing regime with single fs pulses typically leading to less conductive micro electrodes. [Display omitted] • Bessel beam writing. • Laser bursts with sub-pulses in GHz and sub-THz regime. • Fabrication of in-bulk conductive microelectrodes. • Additional heating mechanism with burst fabrication leading to highest concentration of graphite. • Very low resistivity values (~ 0.02 Ω cm). [ABSTRACT FROM AUTHOR]

The finite depth of focus (DOF) of a focusing lens gives rise to the degradation of lateral resolution at defocused positions. Consequently, the generation of a needle-shaped beam with sub-diffraction size and extended DOF can break through this limitation, but few studies have effectively balanced these two characteristics. In this paper, we propose a method based on the stochastic parallel gradient descent (SPGD) algorithm for designing multi-ring diffractive optical elements (DOEs) to produce the needle-shaped beam, which maintains a super-resolution and uniform spot within a large extended DOF range. Numerical simulations and experimental results have validated that our method can extend the DOF by 14 times longitudinally and reduce the lateral resolution to 73% of Airy spot, while maintaining up to 92% uniformity of the beam diameter. Furthermore, we demonstrate that the DOF of the needle-shaped beam extends with the increase of the number of rings and phase levels within the DOE. Our work provides an effective strategy for the design of DOF-extended DOE and it is anticipated to find potential applications in microscopy and three-dimensional imaging, photolithography, and optical manipulation. • Needle-shaped beam with super-resolution spot and large depth of focus. • Stochastic parallel gradient descent algorithm based optimization for diffractive optics. • Extremely high uniformity of the beam diameter within the extended depth of focus range. • Tunability of the needle-shaped beam through varying parameters within the diffractive optical element. [ABSTRACT FROM AUTHOR]

• An acoustic planar reflector is designed to enhance vortex focusing intensity. • Passive conversion of a plane wave into vortex-focusing waves is fully analyzed. • Acoustic radiation axial force and torque of vortex-focusing beams are calculated. • Rotating centimeter-size objects at high speed is achieved by utilizing sound. The use of acoustic vortex waves with angular momentum is a promising means of transferring mechanical torque to an object without making any physical contact. However, the existing passive-conversion vortex lenses are unable to produce strong acoustic radiation torque. To address this issue, we propose a flat reflector sculpted by spiral grooves. It reflects and converts incident waves into vortex-focusing waves that generate radiation torque. Compared with a transmission-type lens, a reflection-type vortex focusing plate exhibits superior functionality in converging sound waves and creating a stronger circular intensity flow. In this work, we analyze the vortex-focusing sound by Rayleigh-Sommerfeld integral theory and boundary element simulation, confirmed by experiments. The number, depth and direction of spiral grooves determine the topological charge, focusing intensity and torque direction, respectively. We evaluate the local and total acoustic radiation forces and torques, acting on small and large fixed spherical targets in the vortex-focusing beam. As a result, spinning a centimeter-size origami pinwheel several times larger than the wavelength at 40 kHz is realized without direct contact, by utilizing the enhanced acoustic radiation torque converged by the reflector. This technology enables efficient convergence of acoustic waves and simultaneous contactless transfer of mechanical torque to an object, thereby presenting potential applications in sound energy harvesting and wireless power supplies. [ABSTRACT FROM AUTHOR]

In recent decades, significant progress has been made in the field of laser beam shaping, driven by the growing demands in both scientific research and industrial applications. Notably, a class of beams known as nondiffracting beams, which exhibit such characteristics as self-healing and resistance to diffraction, has found practical utility in communication, imaging, and laser microprocessing. Although Bessel beams have become commonplace for various optical applications, further advances in beam engineering remain a need. One of the key requirements is the ability to control the elongation of the transverse profile of an optical needle, which is highly sought after for specific applications. In this study, we propose to achieve this control by utilizing nondiffracting Airy beams. The elongation of the optical needle's transverse profile is achieved through the implementation of a binary phase mask. We evaluate the performance of this method through both numerical simulations and experimental assessments, employing various metrics, such as the major-to-minor axis ratio, the length of the optical needle, and its stability. We present a specific case where a flat optical element is created using geometrical phase induced by nanogratings inscribed within the element's volume by means of a femtosecond laser. We validate the performance of this geometrical phase element through laser microprocessing of transparent glasses and report the results obtained from these experiments. • Elliptical Airy optical needle using binary phase masks is introduced. • Performance of the optical needle is benchmarked numerically and experimentally. • Binary phase mask is inscribed into a flat element for laser microfabrication. • Directional glass cracking along the elongation at the focus is reported. [ABSTRACT FROM AUTHOR]

• A novel QZS dual harvester-absorber system (DHAS) is proposed. • The QZS DHAS mitigates vibrations and harvests energy at low frequency. • The QZS DHAS achieves a wide anti-resonance bandwidth. • The QZS DHAS is optimized with high output power and low resonance peaks. The single quasi-zero-stiffness harvester-absorber system has shown its effectiveness in harvesting vibration energy and suppressing low-frequency vibrations simultaneously. Nevertheless, drawbacks of narrow frequency range of vibration suppression and low output power are still challenges. In this paper, a novel quasi-zero-stiffness dual harvester-absorber system (QZS DHAS) is proposed for broadband synergistic vibration suppression and energy harvesting at low frequency. The QZS feature is realized by mounting an equal-strength piezoelectric beam and a pair of magnet rings in parallel. Firstly, the restoring force of both the piezoelectric beam and the magnet rings are theoretically derived, respectively, which are verified by finite element simulations. Then, the governing equations of a host oscillator with QZS DHAS are derived based on Newton's law and Kirchhoff's law, which are solved by the harmonic balanced method combined with the pseudo arc-length continuation method. Moreover, the effects of mass ratios, frequency ratios and damping ratios on the performance of the QZS DHAS are investigated in details. Finally, the parameters of the QZS DHAS are optimized to improve the performance of vibration suppression and energy harvesting by using the multi-objectives genetic algorithm in combination with the technique of establishing order preference by similarity to the ideal solution. The results show that the peak response of the host oscillator is reduced by 33.48 % and the peak power is increased by 531.38 % after optimization, which indicates that the dual objectives of broadband vibration absorption and high-efficiency energy harvesting are fulfilled. [Display omitted] [ABSTRACT FROM AUTHOR]

• The Bessel Michelson interferometer is first proposed and realized in our work by spatially separating two beams at a specific distance, resulting in partial overlap of the n-th Bessel ring within the central region. • The advantage of Bessel Michelson interferometer over traditional Michelson interferometer have been confirmed, including properties such as propagation invariance, a smaller interference pattern, and self-healing capabilities. • The Bessel Michelson interferometer has the potential to substitute the traditional Michelson interferometer and would play a more significant role in precision measurement or other related fields. Directly introducing Bessel beams into the Michelson interferometer could not generate effective interference pattern for both constructive case or destructive case. To overcome this difficulty, we separate the two Bessel beams with a special distance, making n -th light ring of two Bessel beams partially overlapped in the center. In Bessel Michelson interferometer, the interference pattern changes between hollow shape and rod shape. Comparison with the traditional Michelson interferometer, the Bessel Michelson interferometer exhibits propagation-invariance, smaller interference pattern, and self-healing properties, thus would be of great potential in various fields. [ABSTRACT FROM AUTHOR]

The beam shaping assembly (BSA) plays a crucial role in the facility of accelerator-based boron neutron capture therapy (AB-BNCT). The quality of the neutron beam utilized for treatment is directly influenced by the design of the BSA. However, conventional step-by-step optimization approaches often encounter challenges in achieving the global optimal solution, as they tend to converge towards local optima. To address this issue, this study proposed an intelligent optimization method that combines neural network and genetic algorithm. The proposed method was applied to optimize a double-layered BSA based on the neutron source resulting from a lithium target bombarding by a 2.8 MeV, 20 mA proton beam. The obtained optimal BSA solution parameters well met the IAEA-TECDOC-1223 report, while also exhibiting significantly higher epithermal neutron flux compared to alternative BSA designs. The performance of the epithermal neutron beam was assessed by calculating the dose distribution and clinical parameters in the Snyder head phantom. The findings suggest that this beam exhibits promising therapeutic potential for treating tumors. [ABSTRACT FROM AUTHOR]

We demonstrate the formation of a two dimensional Airy beam soliton in a photorefractive crystal. By simply varying the nonlinearity strength we identify several scenarios showing the coexistence between an Airy beam and the emerging soliton. The soliton output profile behaves according to the theoretical soliton existence curve and can be tailored by the nonlinearity strength even without modifying the input Airy beam shape. This last feature makes this Airy soliton distinct from the Gaussian beam generated photorefractive soliton. [ABSTRACT FROM AUTHOR]

An accurate three-dimensional (3D) segmentation of the maxillary sinus is crucial for multiple diagnostic and treatment applications. Yet, it is challenging and time-consuming when manually performed on a cone-beam computed tomography (CBCT) dataset. Recently, convolutional neural networks (CNNs) have proven to provide excellent performance in the field of 3D image analysis. Hence, this study developed and validated a novel automated CNN-based methodology for the segmentation of maxillary sinus using CBCT images. A dataset of 264 sinuses were acquired from 2 CBCT devices and randomly divided into 3 subsets: training, validation, and testing. A 3D U-Net architecture CNN model was developed and compared to semi-automatic segmentation in terms of time, accuracy, and consistency. The average time was significantly reduced (p-value < 2.2e−16) by automatic segmentation (0.4 min) compared to semi-automatic segmentation (60.8 min). The model accurately identified the segmented region with a dice similarity co-efficient (DSC) of 98.4%. The inter-observer reliability for minor refinement of automatic segmentation showed an excellent DSC of 99.6%. The proposed CNN model provided a time-efficient, precise, and consistent automatic segmentation which could allow an accurate generation of 3D models for diagnosis and virtual treatment planning. [ABSTRACT FROM AUTHOR]

This work focuses on the design, modeling, simulation and parametric analysis of fixed-guided two beam (FG2B) and fixed-guided four beam (FG4B) piezoelectric energy harvester for ambient energy harvesting application. In these configurations, two and four rectangular beams are connected to the square-shaped proof mass at the center of the structure. The parametric analysis is carried out for the evaluation of displacement, von Mises stress, electric potential and total electric energy generated under varying load conditions i.e., from 1 to 5 g (g = 9.8 m / s 2) . From the modal and the static analysis, it can be deduced that the two beams of FG2B and the four beams of FG4B arrangements are capable of generating 930 mV and 945.12 mV and 48.84 pJ and 51 pJ of electric potential and total electric energy at 5 g input acceleration with the resonant frequency of 556.29 Hz and 780.36 Hz, respectively. These configurations can also be implemented as an energy harvester for low frequency applications. [ABSTRACT FROM AUTHOR]

A single-layer, dual-band, shared-aperture array with a broad fan beam in the lower band centered at 5 GHz and a narrow pencil beam in the adjacent upper band centered at 5.8 GHz is presented in this article. First, the schematic of a dual-band array with its beamwidth regulation capability is presented. Then, two key components, i.e., a novel dual-band patch antenna element and a compact filtering phase shifter (FPS) are developed. The antenna element has counterintuitive beam patterns with broad azimuthal half-power beamwidth (HPBW) of 183.3° in the lower band but much narrower azimuthal HPBW of 68.5° in the upper band, indicating its excellent ability in beamwidth regulation with a figure of merit (FoM) of 2.31. Meanwhile, the FPS serves as a band-stop filter in the lower band and a phase shifter in the upper band. Furthermore, a two-element series-fed subarray is designed by cascading two properly designed antenna elements through the FPS. Finally, a parallel-series-fed array consisting of four rows of the series-fed subarrays is implemented, and a prototype is fabricated and tested. The measured results, in good agreement with the simulated ones, have demonstrated that the array satisfactorily attains a broad fan beam with azimuthal HPBW of 156° and gain of 11.05 dBi at 5 GHz and a narrow pencil beam with azimuthal HPBW of 30° and gain of 16.23 dBi at 5.8 GHz under a shared aperture of $1.37\lambda _{0} \times 3.53\lambda _{0} \times 0.05\lambda _{0}$ , indicating an enhanced FoM up to 4.48. The FoM and gain could be further improved by simply expanding the array’s dimension based on the developed array topology. [ABSTRACT FROM AUTHOR]

We consider three‐dimensional elastic frames constructed out of Euler–Bernoulli beams and describe a simple process of generating joint conditions out of the geometric description of the frame. The corresponding differential operator is shown to be self‐adjoint. In the special case of planar frames, the operator decomposes into a direct sum of two operators, one coupling out‐of‐plane displacement to angular (torsional) displacement and the other coupling in‐plane displacement with axial displacement (compression). Detailed analysis of two examples is presented. We actively exploit the symmetry present in the examples and decompose the operator by restricting it onto reducing subspaces corresponding to irreducible representations of the symmetry group. These "quotient" operators are shown to capture particular oscillation modes of the frame. [ABSTRACT FROM AUTHOR]

The existing Bessel beam generators generally require bulk optics counterparts and additional spatial laser sources, which adds complexity and bulkiness to the system. In this work, we propose Bessel beam devices with high compactness based on vertical-cavity surface-emitting lasers (VCSELs) and microdielectric axicons made by Si3N4. The transparent microaxicons are fabricated by one-step direct writing of focused ion beam (FIB) on the surface of meticulously designed top-emitting VCSELs. Zero- and first-order Bessel beams are obtained by engineering the lasing modes of the VCSELs through simply adjusting the oxide aperture diameter. Even if the VCSEL device works at multimode, Bessel beams can still be realized. This method provides great compatibility with different VCSEL configurations and emitting wavelengths. Such high-compactness devices may enable advanced research and applications relevant to Bessel beams. [ABSTRACT FROM AUTHOR]

This paper presents a beam theory for analyzing the static response of slightly curved three-layer beams with interlayer slip. Since the beams are supposed to be immovably supported, membrane stresses develop even at moderately large deflections and the response becomes geometrically nonlinear. The theory is based on a layerwise application of the Euler–Bernoulli theory and a linear elastic constitutive law for the interlaminar displacements. In three application examples, the accuracy of this theory is shown by comparing the results of this theory with the outcomes of a more complex finite element analysis assuming a plane stress state. These application examples demonstrate the effect of a small initial deflection on the nonlinear response of the considered layered structural members. [ABSTRACT FROM AUTHOR]

Purpose: Image guidance is used to improve the accuracy of radiation therapy delivery but results in increased dose to patients. This is of particular concern in children who need be treated per Pediatric Image Gently Protocols due to long‐term risks from radiation exposure. The purpose of this study is to design a deep neural network architecture and loss function for improving soft‐tissue contrast and preserving small anatomical features in ultra‐low‐dose cone‐beam CTs (CBCT) of head and neck cancer (HNC) imaging. Methods: A 2D compound U‐Net architecture (modified U‐Net++) with different depths was proposed to enhance the network capability of capturing small‐volume structures. A mask weighted loss function (Mask‐Loss) was applied to enhance soft‐tissue contrast. Fifty‐five paired CBCT and CT images of HNC patients were retrospectively collected for network training and testing. The output enhanced CBCT images from the present study were evaluated with quantitative metrics including mean absolute error (MAE), signal‐to‐noise ratio (SNR), and structural similarity (SSIM), and compared with those from the previously proposed network architectures (U‐Net and wide U‐Net) using MAE loss functions. A visual assessment of ten selected structures in the enhanced CBCT images of each patient was performed to evaluate image quality improvement, blindly scored by an experienced radiation oncologist specialized in HN cancer. Results: All the enhanced CBCT images showed reduced artifactual distortion and image noise. U‐Net++ outperformed the U‐Net and wide U‐Net in terms of MAE, contrast near structure boundaries, and small structures. The proposed Mask‐Loss improved image contrast and accuracy of the soft‐tissue regions. The enhanced CBCT images predicted by U‐Net++ and Mask‐Loss demonstrated improvement compared to the U‐Net in terms of average MAE (52.41 vs 42.85 HU), SNR (14.14 vs 15.07 dB), and SSIM (0.84 vs 0.87), respectively (p<0.01$p < 0.01$, in all paired t‐tests). The visual assessment showed that the proposed U‐Net++ and Mask‐Loss significantly improved original CBCTs (p<0.01$p < 0.01$), compared to the U‐Net and MAE loss. Conclusions: The proposed network architecture and loss function effectively improved image quality in soft‐tissue contrast, organ boundary, and small structure preservation for ultra‐low‐dose CBCT following Image Gently Protocol. This method has potential to provide sufficient anatomical representation on the enhanced CBCT images for accurate treatment delivery and potentially fast online‐adaptive re‐planning for HN cancer patients. [ABSTRACT FROM AUTHOR]

This study investigates the advantages and disadvantages of cone-beam-based navigated standardized posterior lumbar interbody fusion surgery (PLIF), regarding the radiation exposure and perioperative time management, compared to the use of fluoroscopy. Patients treated receiving an elective one- to three-level PLIF were retrospectively enrolled in the study. The surgery time, preparation time, operation room time, and effective dose (mSv) were analyzed for comparison of the radiation exposure and time consumption between cone-beam and fluoroscopy; Results: 214 patients were included (108 cone-beam navigated, and 106 traditional fluoroscopies). Using cone-beam navigation, reductions in the effective dose (2.23 ± 1.96 mSv vs. 3.39 ± 2.32 mSv, p = 0.002) and mean surgery time of 30 min (143.62 ± 43.87 min vs. 171.10 ± 48.91 min, p < 0.001) were demonstrated, which leveled out the extended preparation time of 7–8 min (37.25 ± 9.99 min vs. 29.65 ± 7.69 min, p < 0.001). These effects were fusion length dependent and demonstrated additional benefits in multisegmental surgeries. The cone-beam navigation system led to a reduction in the perioperative time requirements and radiation exposure. Furthermore, the controversially discussed longer preparation time when using cone-beam navigation was amortized by a shortened surgery time, especially in multilevel surgery. [ABSTRACT FROM AUTHOR]

Aim: To compare the diagnostic performance and safety of fluoroscopy computed tomography (FCT)-guided to cone-beam CT (CBCT)-guided percutaneous transthoracic needle biopsy (PTNB) in patients with nodules in the lung base.Materials and Methods: The clinical data of 379 patients (228 in the FCT group and 151 in the CBCT group) with nodules in the lung base who underwent FCT-guided or CBCT-guided PTNB from September 2009 to March 2020 were analysed retrospectively. Study outcomes included patient demographics, nodule characteristics, technical success, pathological diagnosis, complications, and radiation exposure.Results: PTNB technical success rates were 98.2% in the FCT group and 98.7% in the CBCT group (p=0.548). For larger lesions (>2 cm in diameter), PTNBs under FCT had similar diagnostic accuracy (95.5% versus 93.64%), incidence of pneumothorax (31.5% versus 21.3%) and radiation exposure (16.8 ± 6.1 versus 15.2 ± 4 mSv) compared to those under CBCT guidance. For smaller lesions (≤2 cm in diameter), the diagnostic accuracy was similar (92.86% versus 100%), but there was a higher incidence of pneumothorax (66.7% versus 31%, p=0.030) and more radiation exposure (19.9 ± 8.4 versus 15.3 ± 5 mSv, p=0.040) under FCT guidance than CBCT.Conclusion: PTNBs under FCT and CBCT guidance had similar performance for larger lesions in lung base. CBCT guidance performed better for smaller lesions in terms of radiation dose and complications. Radiologists could optimise the technological resources based on equipment availability and lesion characteristics. [ABSTRACT FROM AUTHOR]

Compared with traditional vortex beams, high-order Bessel beams (HoBBs) have the unique characteristics of non-diffraction and self-healing, which makes them more competitive in fields of complex-environment optical manipulation and long-distance optical communication. With the progress of machining technology, the realization of micro-nano-sized optical components becomes possible, and integrated optics becomes the trend of future development. However, up to now, the traditional devices for generating HoBBs have a large volume and high weight, which makes it difficult to achieve optical integration. Here, we have designed an ultra-compact micro-optical element to generate high-quality micro-sized HoBBs. Good morphology of the element prepared via laser direct writing (LDW), and beam characteristics of non-diffraction and self-healing were demonstrated experimentally. [ABSTRACT FROM AUTHOR]

To verify the applicability of wave theory in studying the free vibration characteristics and impact response of the cable-beam structure, and to preliminarily explore the behaviors of elastic wave propagation through the structure under moving load, the dynamic response function was derived from the transverse vibration differential equation of Timoshenko beam and the longitudinal wave equation of cables. The reverberation-ray matrix was used to obtain the waveform solution of the structural response. Based on the idea of discrete Fourier transform (DFT), the series solution of structural transient response was derived to solve the inverse problem of the traditional reverberation-ray matrix (MRRM). The improved MRRM was verified by experiment and finite element method (FEM). The results showed that at the speed of 30 km/h, the deviation between the theoretical maximum strain and FEM results was 5% and that between theoretical and experimental results was 8%. When the vehicle speed was 40 km/h, the deviation between the theoretical maximum strain and FEM results was 4.0%, which was 9.8% between theoretical and experimental results. Taking the beam-cable system as the research object, the maximum deviation between the first five natural frequencies calculated by improved MRRM and FEM was 0.29%, and the deviation between the first two natural frequencies was 0. The wave response characteristics of the cable-stayed beam under moving load were analyzed and the theoretical results were in good agreement with the FEM results. It could be inferred that the improved MRRM had high reliability in calculating the transient wave response of bridge structure under moving load. Based on the analyses of the frequency domain response, it was found that the flexural waves in the Timoshenko beam under moving load were mainly low-frequency responses whose frequencies were lower than 2 times the fundamental frequency of the structure. Furthermore, the reasonable selection criteria of frequency range were explored in the process of finding the wave response, to further improve the calculation efficiency of MRRM. [ABSTRACT FROM AUTHOR]