Transverse Structure Research Articles

On‐Demand Subwavelength‐Scale Light Sculpting Using Nanometric Holograms

AbstractSpatially or temporally structured light has attracted considerable attention for its intriguing beam characteristics, which have found extensive applications in classical and quantum optics. Extending structured light from macroscale and microscale to nanometricscale brings more prospects both for fundamental and applied science. However, sculpting light at the subwavelength scale remains a challenge since its transverse structure is fragile in the nanometric scale. Here a novelholography for arbitrary light sculpting at the subwavelength scale is demonstrated. A wave phenomenon of diffractive focusing from an amplitude‐only nanometric (50‐nm‐thick) film is introduced, and use of the induced high‐spatial‐frequency waves as carriers to encode information of an object is considered. Using this technique, nanometric holograms are designed and fabricated for generating the well‐defined eigen modes including the zero‐order Bessel beam, vortex beam, vector beam, Airy beam, as well as an arbitrary light pattern, with feature sizes on the deep‐subwavelength scale. The broadband performance of the hologram is examined, and a white‐light nondiffracting beam at the deep‐subwavelength scale is realized. This demonstration paves a way toward on‐demand light sculpting at the nanometric scale, which may find applications such as optical super‐resolution imaging, nanoparticle manipulation, and precise measurements.

Optical trapping based on microring resonators with a transverse slot structure.

Over the past few decades, optical manipulation has emerged as a highly successful tool in various fields such as biology, micro/nanorobotics, and physics. Among the different techniques, the transverse slot optical waveguide has shown remarkable potential in enhancing the field and significantly improving optical trapping capabilities. Additionally, microring resonators have demonstrated the ability to enhance the field at specific resonance wavelengths, enabling the manipulation and capture of particles. In this study, we investigated the impact of the structure on nanoparticle capture by introducing a 50nm transverse slot in a 5µm microring resonator. Through the integration of a transverse slot in the microring resonator, we observed a substantial increase in the maximum bound optical power for a nanosphere with a refractive index of 1.6 and a diameter of 50nm, reaching 3988.8pN/W. This value is 2292 times higher than the maximum optical force in a straight waveguide and 2.266 times higher than the maximum optical force in a microring resonator. The proposed structure significantly enhances the optical trapping capabilities for nanoscale particles, thus paving the way for the development of advanced micro/nanomanipulation techniques.

Improved room-temperature magnetoelectric coupling properties for multiferroic Z-type hexaferrites

Here we present the results of a systematic investigation of the effect of Ba substitution on the spiral magnetic structure and magnetoelectric effect in polycrystalline BaxSr3−xCo2Fe24O41 (x = 0.0, 0.1, 0.3, 0.5, and 0.7). The magnetoelectric coupling coefficient was improved from 455 ps/m (x = 0.0) to 624 ps/m (x = 0.3). Furthermore, the magnetic field range at which the magnetoelectric signal appears extended from 0-∼0.4 T (x = 0.0) to 0-∼0.9 T (x = 0.5), demonstrating that the transverse conical spin structure was significantly strengthened by Ba substitution. These improvements are attributed to the decrease of Fe-O-Fe bond angle near the L and S blocks boundary, the reduction of cone angle in the transverse conical spin structure, and the change in the distribution of magnetic Co ions caused by the substitution of large Ba ions for small Sr ions. In general, we achieved the improved magnetoelectric coupling strength in polycrystalline Z-type hexaferrite for the first time.

Effects of relative curvature radius on erosion and sedimentation patterns in a 90o bend with and without bendway weirs

Bendway weirs are low-level transverse structures constructed on the outer bank of a channel bend to improve navigation, create aquatic habitat and control bend migration. This experimental study was aimed at investigating the erosion and sedimentation patterns in a 90° bend by varying the relative curvature radius (i.e. normalized to the channel width), in the absence and in the presence of bendway weirs, under different flow conditions. A series of flat weirs with relative heights of 30% and 70% were considered. The results indicate that as the relative curvature increases, the erosion near the weirs decreases while the point-bar at the inner bend wall extends. Regardless of the weir height, the increase in the relative curvature leads to a deeper scour depth at the tip of the weirs. Bendway weirs with submergence ratio of 70% are found to be the most efficient in protecting the outer bank from erosion.

Unintentional Recharge of Aquifers from Small Dams and Dykes in Spain: A GIS-Based Approach to Determine a Fractional Volume

Conducting an accurate hydrological water balance at the regional and country-wide scales is paramount to assessing available water resources and adequately allocating them. One of the main components of these balances is the anthropogenic recharge of groundwater either intentionally, through managed aquifer recharge (MAR), or unintentionally, where infiltration from dams and dykes can play a significant role. In Spain, proper management of water resources is critical due to the arid to semiarid conditions prevalent in most of the territory and the relevance of water resources for maintaining a robust agricultural sector. Previous work estimated country-wide recharge from MAR at 150 to 280 Mm3/year. Recently, water authorities pointed out that, according to hydrological water balances, the total unintentional recharge volume from water courses may exceed 500 Mm3/year. The present research aims to present a new inventory of transverse structures (also referred to as small dams and dykes) in Spain and use it to estimate country-wide unintentional recharge. The inventory, compiled by the Spanish Ministry for the Ecological Transition and the Demographic Challenge, has 27,680 structures and includes construction and impoundment characteristics, which allow for estimating the wet perimeter and the infiltration area. To this end, structural data from the inventory were crossed through map algebra in a GIS environment with thematic layers, such as lithology, permeability, the digital elevation model, the transverse structures’ wetted area, the average groundwater levels, and a clogging correction factor. Two analytical formulas to compute infiltration from small dams and dykes were tested. The resulting volume of unintentional recharge from transverse structures ranges between 812.5 and 2716.6 Mm3/year. The comparison against regional and national water balances suggests that the lowest value of the range (i.e., 812.5 Mm3/year) is probably the most realistic. Anthropogenic recharge from MAR and transverse structures is likely in the range of 1012.5–1514.8 Mm3/year. This rough figure can help close the hydrological balance at the national and river basin levels and contribute to calibrating regional models. Furthermore, they provide an order of magnitude for anthropogenic recharge at a national scale, which is difficult to obtain.

Transverse momentum structure of strange and charmed baryons: A light-front Hamiltonian approach

Transverse momentum structure of strange and charmed baryons: A light-front Hamiltonian approach

Lateral vibration suppression of highway bridge by using frequency modulated particle damper in earthquake environment

In order to study the seismic control effect and mechanism of particle damper in the transverse structure of highway’s bridge, a 1:20 scale model of a typical highway bridge is designed and manufactured, and a frequency modulated particle damper is designed and manufactured, which can be used in the test model. The seismic simulation vibration array test is carried out on the model bridge before and after the particle damper is set. By changing the filling rate, particle material, particle size and installation position of the particle damper, the power spectral density at the middle or top of the beam steel column is measured, and the total energy response of the steel column structure is calculated. The influence and law of the particle damper on the vibration amplitude of the steel column are explored. The test results show that: the proposed frequency modulated particle damper does not appear particle accumulation phenomenon in the test; it has better damping effect on the transverse seismic response of the main beam of the scale model bridge, and can reduce the peak displacement response of the main beam. The energy response value is 1.016 kg (m/s2)2/Hz.

Extreme ion acceleration at extragalactic jet termination shocks

Context. Extragalactic plasma jets are some of the few astrophysical environments able to confine ultra-high-energy cosmic rays, but whether they are capable of accelerating these particles is unknown. Aims. In this work, we revisit particle acceleration at relativistic magnetized shocks beyond the local uniform field approximation by considering the global transverse structure of the jet. Methods. Using large two-dimensional particle-in-cell simulations of a relativistic electron-ion plasma jet, we show that the termination shock forming at the interface with the ambient medium accelerates particles up to the confinement limit. Results. The radial structure of the jet magnetic field leads to a relativistic velocity shear that excites a von Kármán vortex street in the downstream medium trailing behind an over-pressured bubble filled with cosmic rays. Particles are efficiently accelerated at each crossing of the shear flow boundary layers. Conclusions. These findings support the idea that extragalactic plasma jets may be capable of producing ultra-high-energy cosmic rays. This extreme particle acceleration mechanism may also apply to microquasar jets.

Research on the Rationality of Setting the Transverse Ribs of Large Cantilever Segmental Prefabricated Box Girders

This article develops three transverse rib setting schemes for a 20 m wide cantilever segmental box girder of a particular engineering bridge deck, analyzes the stress rules under loads such as dead load, live load, and temperature, and studies the lateral deformation characteristics of the three schemes under symmetrical and eccentric live load arrangements on the bridge deck. Research has shown that setting transverse ribs can significantly improve the transverse stress, crack resistance, and reduce vertical deformation of the cross-section. However, its effect gradually weakens with the increase in the number of transverse ribs. Considering the convenience and simplicity of construction, installing a transverse rib structure for the large cantilever section box girder in this project is recommended.

Weissella koreensis and Pediococcus pentosaceus bacterial ghosts induce inflammatory responses as immunostimulants

In this study, bacterial ghosts (BGs) were generated from Weissella koreensis LKS42 (WKorGs) and Pediococcus pentosacues KA94 (PPGs) by chemically inducing lysis using substances such as hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), acetic acid (CH3COOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), n-butanol, and C6H8O7. HCl-induced WKorGs and PPGs exhibited complete removal of DNA and displayed transverse membrane dissolution tunnel structures under scanning electron microscopy (SEM). Cell viability assays showed high viability of RAW 264.7 cells exposed to HCl-induced WKorGs and PPGs. Additionally, treatment with HCl-induced WKorGs and PPGs elevated mRNA levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, iNOS) and the anti-inflammatory cytokine IL-10 in RAW 264.7 cells. These findings suggest that HCl-induced WKorGs and PPGs have the potential to be used as inactivated bacterial immunostimulants, highlighting their promising applications in immunization and immunotherapy.

Design of acoustic impedance gradient matching layers

This article proposes a new acoustic impedance gradient matching layer based on phononic crystal theory to further expand the bandwidth of piezoelectric ultrasonic transducers and improve their working efficiency. The matching layer is made of a composite of two different materials and its transverse structure can be regarded as a one-dimensional phononic crystal. This structure can effectively reduce the transverse vibration of the transducer and enhance the longitudinal vibration. In addition, the gradient alteration of acoustic impedance in the longitudinal direction of the matching layer improves its acoustic impedance matching performance with the medium. Through theoretical calculations and finite element simulations, we obtained the equivalent acoustic parameters of the gradient matching layer and investigated the suppression of transverse vibration by its structural properties based on the band gap theory. Finally, a sample of the transducer equipped with the gradient matching layer was prepared and its working performance was measured by pulse echo experiments, which is a significant improvement compared to the conventional λ/4 matching layer transducer.

Magnetic properties and magnetoimpedance effect in FINEMET/TiO2/Fe20Ni80 composite ribbons

The impact of TiO2 and Fe20Ni80 coating layer on roughness, magnetic properties, giant magneto-impedence (GMI) effect and dipole interactions of FINEMET/TiO2/Fe20Ni80 composite ribbons were investigated systematically. The TiO2 layer can effectively tune transverse magnetic structure and GMI ratio of composite ribbons. More TiO2 coating layer thickness deteriorates the magnetic properties, and dipole interactions decrease owing to the distance between FINEMET ribbon and Fe20Ni80 layer increases. When the thickness of TiO2 is 100 nm, composite ribbons exhibit small roughness of 8.5 nm, a large GMI ratio of 63% at 0.8 MHz, dipole field of 1.0 Oe, which is superior to other semiconductor composite ribbons. The variation in GMI ratio can be explained as the change of transverse permeability, and the decrease of magnetic dipole interactions can be explained as the change of distance between the FINEMET ribbon and Fe20Ni80 layer. The results show that the combination of semiconductor and magnetic materials can realize the miniaturization of magnetic sensing, and it has a guiding role in the development of GMI effect and magnetic interactions theory of composite materials.

Transversalidad docente para la carrera de Medicina: asignatura de Patología del aparato digestivo, un ejemplo a seguir

At present, university medical training in Spain remains stagnant in a model based on subjects, departments that own areas of knowledge, teacher-centered lectures taught in university classrooms or hospital offices, and in an evaluation system carried out by that same teaching staff in which the final grade is often subjective. This model is not valid to respond to the demands of the new generations, who increasingly have a greater number of sources of knowledge that make them less dependent on conventional teachers. Values typical of Primary Care such as transversality, a greater practical approach to learning where health problems are and multidisciplinary teamwork, etc., should be the new paradigms of university medical teaching.In the Faculty of Medicine of Albacete, since its creation, a problem-based learning method has been used in which the Digestive System Pathology subject is taught with a transversal structure in which Family Doctors, and specialists in the digestive system and digestive surgery participate. That interact together contributing to a very rewarding teaching experience.

Small‐Magnitude Seismic Swarms in Central Utah (US): Interactions of Regional Tectonics, Local Structures and Hydrothermal Systems

AbstractSwarms in Central Utah are situated in the complex transition between the Basin and Range (BR) province and the Colorado Plateau. Transecting transverse structures, volcanic deposits, and hydrothermal systems complicate the extensional BR horst and graben structures and provide a multitude of plausible triggering mechanisms. Revisiting the catalog of the University of Utah Seismograph Stations (1981–2022), we analyze spatio‐temporal patterns and characteristic features of seismic sequences. Swarms with alternating seismicity rates, bursts, and longer swarms with persistent moment release exhibit a remarkable diversity in temporal evolution. Swarm durations do not scale with cumulative seismic moment: swarms lasting less than 1 day can have similar cumulative seismic moments as month‐long swarms. We observe stationary swarms re‐occurring for years (e.g., Mineral Mountains), as well as singular swarms in low‐seismicity areas (e.g., activating a local structure in Milford, 2021). The swarms show a pronounced heterogeneity in triggering and driving mechanisms, observed in the detailed analysis of exemplary sequences (detections, relocations, moment tensors, waveform‐based clustering, and repeater analysis). The 2022 Sevier Valley sequence activated a BR‐related normal fault, the first resolved fault plane in the valley since 1983. The 2011 Circleville sequence is interpreted as a swarm triggered by mainshock‐aftershock activity characterized by increasing magnitudes, changing rupture mechanisms, and a concentration of highly similar events in the second part of the sequence. By jointly discussing exemplary sequences and catalog statistics, we draw a comprehensive picture of swarm activity and its relation to geothermal and tectonic activity.

Modelling and optimization analysis of a novel hollow flexible-filler-based bulk thermoelectric generator for human body sensor

Thermoelectric generator (TEG) is a promising technology for self-powered wearable electronics and sensors. Usually, polydimethylsiloxane (PDMS) is selected as bulk thermoelectric gap filler to make the TEG flexible. However, PDMS has much higher thermal conductivity than air causing considerable thermal shortcut and efficiency degradation. In this study, a novel hollow PDMS-filler design is proposed to enhance the TEG performance. A well-validated three-dimensional thermal and electrical coupled model is developed to assess effects of longitudinal and transverse hollow structures on maximum output power and corresponding optimal fill factor of the flexible TEG, and to reveal impact of key geometrical and physical parameters on design optimization of the TEG. Results show that, (1) as height of the hollow structure increases, the output power increases linearly, while the optimal fill factor decreases sharply; (2) the transverse-hollow structure is more effective than the longitudinal-hollow structure to create higher power; (3) the transverse-hollow structure can approximately double the output power while halve the optimal fill factor; (4) the transverse-hollow structure combined with both-sides high-thermal-conductivity layers can increase output power up to 137.34 μWcm−2. Such design of hollow PDMS filler could open a window of opportunity to the next generation efficient yet low-cost flexible TEG.

Collins and Sivers transverse-spin asymmetries in inclusive muoproduction of ρ0 mesons

The production of vector mesons in deep inelastic scattering is an interesting yet scarcely explored channel to study the transverse spin structure of the nucleon and the spin-dependence of fragmentation. The COMPASS collaboration has performed the first measurement of the Collins and Sivers asymmetries for inclusively produced ρ0 mesons. The analysis is based on the data set collected in deep inelastic scattering in 2010 using a 160GeV/cμ+ beam impinging on a transversely polarized NH3 target. The ρ0 mesons are selected from oppositely charged hadron pairs, and the asymmetries are extracted as a function of the Bjorken-x variable, the transverse momentum of the pair and the fraction of the energy z carried by the pair. Indications for positive Collins and Sivers asymmetries are observed.

The propagation speed of optical speckle

That the speed of light in vacuum is constant is a cornerstone of modern physics. However, recent experiments have shown that when the light field is confined in the transverse plane, the observed propagation speed of the light is reduced. This effect is a consequence of the transverse structure which reduces the component of wavevector of the light in the direction of propagation, thereby modifying both the phase and group velocity. Here, we consider the case of optical speckle, which has a random transverse distribution and is ubiquitous with scales ranging from the microscopic to the astronomical. We numerically investigate the plane-to-plane propagation speed of the optical speckle by using the method of angular spectrum analysis. For a general diffuser with Gaussian scattering over an angular range of 5°, we calculate the slowing of the propagation speed of the optical speckle to be on the order of 1% of the free-space speed, resulting in a significantly higher temporal delay compared to the Bessel and Laguerre–Gaussian beams considered previously. Our results have implications for studying optical speckle in both laboratory and astronomical settings.

Interplay between Magnetism and Topology: Large Topological Hall Effect in an Antiferromagnetic Topological Insulator, EuCuAs.

Magnetic interactions in combination with nontrivial band structures can give rise to several exotic physical properties such as a large anomalous Hall effect, the anomalous Nernst effect, and the topological Hall effect (THE). Antiferromagnetic (AFM) materials exhibit the THE due to the presence of nontrivial spin structures. EuCuAs crystallizes in a hexagonal structure with an AFM ground state (Néel temperature ∼ 16 K). In this work, we observe a large topological Hall resistivity of ∼7.4 μΩ-cm at 13 K which is significantly higher than the giant topological Hall effect of Gd2PdSi3 (∼3 μΩ-cm). Neutron diffraction experiments reveal that the spins form a transverse conical structure during the metamagnetic transition, resulting in the large THE. In addition, by controlling the magnetic ordering structure of EuCuAs with an external magnetic field, several fascinating topological states such as Dirac and Weyl semimetals have been revealed. These results suggest the possibility of spintronic devices based on antiferromagnets with tailored noncoplanar spin configurations.

Both Longitudinal and Transverse Extension Controlling Gas Migration Through Submarine Anticlinal Ridges, New Zealand's Southern Hikurangi Margin

AbstractSub‐seabed fluid flow, gas hydrate accumulation and seafloor methane seepage are tightly interwoven processes with implications for marine biodiversity, ocean chemistry and seafloor stability. We combine long‐offset seismic reflection data with high‐resolution seismic data to investigate shallow structural deformation and its relationship to focused gas migration and hydrate accumulation in the southern Hikurangi subduction wedge. Anticlines, effective traps for focusing free gas, are characterized by both normal faults and vertical zones of hydraulic fracturing within the hydrate stability zone. The normal faults form as a result of sediment layer folding and gravitational collapse of ridges during uplift. We document both longitudinal (ridge‐parallel) and transverse (ridge‐perpendicular) extensional structures (normal faults and elongated hydraulic fracture zones) in the sub‐seafloor of anticlinal ridges. Intriguingly, gas flow through ridges close to the deformation front of the wedge exploits longitudinal structures, while ridges further inboard are characterized by gas flow along transverse structures. This highlights pronounced changes in the shallow deformation of ridges in different parts of the wedge, associated with a switching of the least and intermediate principal stress directions. It is critical to understand these shallow stress fields because they control fluid flow patterns and methane seepage out of the seafloor.

Multimode Graded Index Fiber with Random Array of Bragg Gratings and Its Raman Lasing Properties

Light propagation in multimode fibers is known to experience various nonlinear effects, which are being actively studied. One of the interesting effects is the brightness enhancement at the Raman conversion of the multimode beam in graded index (GRIN) fiber due to beam cleanup at Raman amplification and mode selective feedback in the Raman laser cavity based on fiber Bragg gratings (FBGs) with special transverse structure. It is also possible to explore random distributed feedback based on Rayleigh backscattering on natural refractive index fluctuations in GRIN fibers, but it is rather weak, requiring very high power multimode pumping for random lasing. Here, we report on the first realization of femtosecond pulse-inscribed arrays of weak randomly spaced FBGs in GRIN fibers and study Raman lasing at its direct pumping by highly multimode (M2~34) 940-nm laser diodes. The fabricated 1D–3D FBG arrays are used as a complex output mirror, together with the highly reflective input FBG in 1-km fiber. Above threshold pump power (~100 W), random lasing of the Stokes beam at 976 nm is obtained with output power exceeding 28 W at 174 W pumping. The beam quality parameter varies for different arrays, reaching M2~2 at the linewidth narrowing to 0.1–0.2 nm due to the interference effects, with the best characteristics for the 2D array.