Symmetric Fiber Research Articles

Celsr3 drives development and connectivity of the acoustic startle hindbrain circuit.

In the developing brain, groups of neurons organize into functional circuits that direct diverse behaviors. One such behavior is the evolutionarily conserved acoustic startle response, which in zebrafish is mediated by a well-defined hindbrain circuit. While numerous molecular pathways that guide neurons to their synaptic partners have been identified, it is unclear if and to what extent distinct neuron populations in the startle circuit utilize shared molecular pathways to ensure coordinated development. Here, we show that the planar cell polarity (PCP)-associated atypical cadherins Celsr3 and Celsr2, as well as the Celsr binding partner Frizzled 3a/Fzd3a, are critical for axon guidance of two neuron types that form synapses with each other: the command-like neuron Mauthner cells that drive the acoustic startle escape response, and spiral fiber neurons which provide excitatory input to Mauthner cells. We find that Mauthner axon growth towards synaptic targets is vital for Mauthner survival. We also demonstrate that symmetric spiral fiber input to Mauthner cells is critical for escape direction, which is necessary to respond to directional threats. Moreover, we identify distinct roles for Celsr3 and Celsr2, as Celsr3 is required for startle circuit development while Celsr2 is dispensable, though Celsr2 can partially compensate for loss of Celsr3 in Mauthner cells. This contrasts with facial branchiomotor neuron migration in the hindbrain, which requires Celsr2 while we find that Celsr3 is dispensable. Combined, our data uncover critical and distinct roles for individual PCP components during assembly of the acoustic startle hindbrain circuit.

Comparison of intraepidermal nerve fiber density and confocal corneal microscopy for neuropathy.

Compare the diagnostic characteristics of intraepidermal nerve fiber density (IENFD) and confocal corneal microscopy (CCM) for distal symmetric polyneuropathy (DSP) and small fiber neuropathy (SFN). Participants with obesity were recruited from bariatric surgery clinics and testing was performed prior to surgery. DSP and SFN were determined using the Toronto consensus definitions of probable neuropathy. IENFD was assessed from 3 mm punch biopsies of the distal leg and proximal thigh. CCM was performed on both eyes with manual and automated counting. The Michigan Neuropathy Screening Instrument questionnaire (MNSIq) was also completed. Diagnostic capability was determined using areas under the receiver operating characteristics curve (AUC) from logistic regression. We enrolled 140 participants (mean [standard deviation [SD]] age: 50.3 years [7.1], 77.1% female, BMI: 44.4 kg/m2 [6.7]). In this population, 22.9% had DSP and 14.3% had SFN. Distal leg IENFD had the largest AUC (95% confidence interval) for DSP (0.78, 0.68-0.89) and SFN (0.85, 0.75-0.96). Proximal thigh IENFD (DSP: AUC: 0.59, 0.48-0.69, SFN: AUC: 0.59, 0.46-0.73) and CCM metrics (DSP: AUC range: 0.55-0.60, SFN: AUC range: 0.45-0.62) had poorer diagnostic capability than distal leg IENFD for DSP/SFN (P < 0.05). MNSIq had similar diagnostic capability to distal leg IENFD for both DSP/SFN (DSP: AUC: 0.76, 0.68-0.85, SFN: AUC: 0.81, 0.73-0.88). More participants (52%) preferred skin biopsies to CCM. Distal leg IENFD was the best quantitative measure of DSP/SFN. CCM had poor diagnostic characteristics and fewer patients preferred this test to IENFD. The MNSIq had similar diagnostic characteristics to distal leg IENFD, indicating its value as a diagnostic tool in the clinical setting. clinicaltrials.gov: NCT03617185.

Spacing mode multi-wavelength erbium doped fiber laser based on a symmetrical long-period fiber grating

We present a multiwavelength erbium-doped fiber laser based on a symmetrical long-period fiber grating (LPFG) with tunable spacing mode between single lasing mode and multiwavelength spectra. The LPFG was manufactured using a thermal expansion technique using an LZM-100 glass processing system equipped with a CO2 laser, and it was used as a wavelength-selective filter (WSF) in the laser ring cavity. The laser can emit single, double, triple, quadruple, quintuple, or sextuple lines in the range from 1546 to 1563 nm, which can be tunable by controlling the radius of curvature of the LPFG in the range 0–0.2662 m −1. A minimal spacing mode of 1.92 nm was observed in the multiwavelength region; meanwhile, the fiber laser offers an average spacing mode of 6.945 nm between the multiwavelength region and the single emission. This laser has a 3 dB linewidth of 0.11 nm and a side mode suppression ratio (SMSR) of 55.56 dB. Finally, according to experimental results, the laser has high wavelength stability at room temperature for 88 min.

Case Report: Quantitative Evaluation of Gait Function Following Treatment Progression in a Patient with Central Pontine Myelinolysis

Introduction: Central pontine myelinolysis (CPM) is a rare neurological disorder marked by symmetric nerve fiber damage, commonly following rapid hyponatremia correction, with no established treatment and a poor prognosis. The condition, often linked to alcoholism, malnutrition, and various diseases, lacks comprehensive studies on its impact on gait. This research aims to quantitatively analyze gait changes in CPM patients receiving both traditional Korean and conventional rehabilitation treatments, addressing a gap in current understanding of CPM management.Case presentation: A 56-year-old male diagnosed with CPM following an initial misdiagnosis underwent combined electoracupuncture and rehabilitative treatment at ○○ university Korean medical center, resulting in significant gait improvements. A treadmill gait analysis system was used to measure changes in key gait parameters at 2-week intervals, and the patient’s progress was documented.Conclusions: The quantitative analysis revealed significant gait improvements. Foot rotation decreased from 8.9° to 6.4° (right) and from 11.1° to 7.2° (left); lateral symmetry improved from -7.8 to 0.8; step length increased from 21 cm to 44 cm (right) and from 19 cm to 44 cm (left); and velocity increased from 1.2 m/s to 2.7 m/s. These findings highlight decreased foot rotation and lateral symmetry, along with increased step length and velocity, suggesting a positive outcome of the treatment regimen. Notably, the patient experienced no adverse effects related to the treatments. Despite limitations, including the singe case focus and lack of prior gait-focused CPM research, this case report provides valuable insights into effective CPM management strategies, paving the way for future research in this domain.

Limits of conical Kähler–Einstein metrics on rank one horosymmetric spaces

AbstractWe consider families of conical Kähler–Einstein metrics on rank one horosymmetric Fano manifolds, with decreasing cone angles along a codimension one orbit. At the limit angle, which is positive, we show that the metrics, restricted to the complement of that orbit, converge to (the pull‐back of) the Kähler–Einstein metric on the basis of the horosymmetric homogeneous space, which is a projective homogeneous space. Then we show that, on the symmetric space fibers, the rescaled metrics converge to Stenzel's Ricci flat Kähler metric.

Ultra low-power multistability in [formula omitted]-symmetric periodic structures with saturable coupling, gain and loss

The present work investigates the switching dynamics of conventional fiber Bragg gratings (FBGs) with saturable coupling and parity-time (PT)-symmetric fiber Bragg gratings (PTFBGs) with saturable coupling (SC) and saturable gain-loss (SGL) in the presence of Kerr nonlinearity (KNL) [model - I] and saturable nonlinearity (SNL) [model - II]. Both system models can generate distinct optical multistability (OM) and bistability (OB) curves, including S-shaped, ramp-like, and mixed OM curves in both unbroken and broken PT-symmetric regimes. The impact of each control parameter on controlling switching intensities, hysteresis width, and the number of stable states is thoroughly examined for both of these system models. The direction of right light incidence enables a significant reduction in the switching intensities to below 100 W/cm2, the lowest critical power ever reported in the literature of PTFBGs, thanks to the concept of both saturable coupling, gain and loss.

Anisotropic properties of acoustically induced electric polarization in soft fibrous biological tissues

Acoustically induced electric polarization and its anisotropy in soft fibrous biological tissues were investigated under wet conditions. Assuming that fibrous tissues have polar uniaxial symmetry, stress-induced polarization should occur in the direction of fiber orientation in the non-shear terms of the piezoelectric tensor. Using the acoustically stimulated electromagnetic method, we measured the anisotropic properties of acoustically induced polarization in wet samples of Achilles tendon, skeletal muscle, and aortic wall. In all these tissues, the major non-shear term was confirmed to be d33, with polarization occurring along the fibrous direction. In Achilles tendon, which contains highly oriented collagen fibers, the uniaxially symmetric fiber structure explains the anisotropic polarization well. However, substantial polarization perpendicular to the fiber orientation (the d11 term) was observed in skeletal muscle and aortic wall, suggesting that the presence of fiber crimps and complex extracellular matrix produces polarization that does not occur in the uniaxially symmetric structures.

All-Optical format conversion from PAM4 to QPSK based on non-degenerate Phase-Sensitive amplification and pump assisted nonlinear optical loop mirror

An all-optical format conversion (AOFC) scheme from 4-ary pulse amplitude modulation (PAM4) to quadrature phase shift keying (QPSK) based on the non-degenerate phase-sensitive amplification (PSA) and the pump assisted nonlinear optical loop mirror (PA-NOLM) is proposed and numerically simulated for the first time. The input unipolar PAM4 signal with equal amplitude distance (UPAM4-A) is coupled with two input pump lights and injected into the symmetric interferometric fiber optic parameter amplifier (FOPA) to achieve the separation of the UPAM4-A and the new pump light generated at the signal frequency based on the non-degenerate PSA. When the filtered out UPAM4-A is coherent added with the new generated pump, the UPAM4-A signal to the biplolar PAM4 (BPAM4) signal. When the converted BPAM4 is sent into the PA-NOLM after adjusting its power, the BPAM4 signal could be converted into the QPSK signal. The error vector magnitude (EVM) and bit error ratio (BER) performance of the system are measured before and after AOFC with different input and receiver optical signal to noise ratio (OSNR). For the input UPAM4-A signal with an input OSNR of 27 dB, there is about 8.2 dB BER performance improvement in receiver OSNR for the final converted QPSK signal. Additionally, the proposed non-degenerate PSA configuration can be extended to realize the AOFC from one QPSK to two on–off keying (OOK) signals. The scheme can be applied in the optical gateway connecting the long-haul and the short-reach optical networks with suitable modulation formats.

Asymmetries Caused by Nonparaxiality and Spin–Orbit Interaction during Light Propagation in a Graded-Index Medium

Spin–orbit coupling and nonparaxiality effects during the propagation of vortex vector light beams in a cylindrical graded-index waveguide are investigated by solving the full three-component field Maxwell’s equations. Symmetry-breaking effects for left- and right-handed circularly polarized vortex light beams propagating in a rotationally symmetric graded-index optical fiber are considered. The mode-group delay in a graded-index fiber due to spin–orbit interaction is demonstrated. A scheme for observing the temporal spin Hall effect is proposed. It is shown that the relative delay times between vortex pulses of opposite circular polarizations of the order of 10 ps/km can be observed in graded-index fibers for high-order topological charges.

Symmetrical Dual In-line Sagnac Fiber Sensor based on VMD-GCC for High Precision Localization

Symmetrical Dual In-line Sagnac Fiber Sensor based on VMD-GCC for High Precision Localization

Mechanical Behavior of Large Symmetric Fiber Reinforced Polymer-Reactive Powder Concrete Composite Tanks with Floating Tops

In order to investigate the mechanical behavior of FRP-reactive powder concrete composite tanks with floating tops (FRPCTs) subjected to gravity, twenty-two full-scale FRPCTs were designed with varying parameters for the inner diameter of the storage tank (D) and the thickness of the reactive powder concrete (tc). Based on nonlinear constitutive models and the contact of the materials, and considering tank–liquid coupling, three-dimensional finite element refined models of FRPCTs were established under gravity with ADINA8.5 finite element software, and finite element models of FRPCTs under gravity were verified based on theoretical frequency formulae and existing static tests. Then, the influence of the regularity of different parameters on the equivalent stress, hoop stress, radial stress, and axial stress of the FRPCTs was obtained, and the stress distributions of FRPCTs were clearly described. The results show that the natural frequency of FRPCTs increases gradually with an increase in the height of the tank liquid (Hw); however, the natural frequency of FRPCTs reduces with an increase in D. The equivalent stress, hoop stress, radial stress, and axial stress of the FRP plate and RPC decrease slowly with an increase in tc. The axial stress of the inner RPC increases with an increase in D. The equivalent stress of the inner FRP plate subjected to gravity is distributed in a W shape, the hoop stress, and the axial stress of the FRPCTs are distributed in a U shape, and the radial stress of the inner FRP plate is distributed in an I shape. The maximum displacement occurs in the middle of the FRPCTs, and the bonding between the FRP plate and the concrete is better. Finally, a calculation formula for the variation in the regularity of the tc is developed with different D, and design and construction suggestions for FRPCTs are given, which can provide technical support for the application of the FRPCTs in practical engineering.

A fibre Bragg grating accelerometer with temperature insensitivity for cable force monitoring of FAST

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) currently holds the distinction of being the largest single-aperture telescope worldwide. To ensure its secure functioning, it is crucial to monitor the cable force on its active reflecting surface cable network structure. In this paper, a fibre Bragg grating (FBG) accelerometer is developed to acquire low-frequency vibration signals of the cables. The sensor’s cantilever beam structure enables high sensitivity measurement of low-frequency signals, while the symmetrical double fibre grating structure effectively eliminates the impact of temperature. The sensor’s specific limiting structure ensures its survival during transportation and installation. A series of laboratory tests have been performed, and they demonstrate the excellent measurement performance, temperature insensitivity and practical usefulness of the accelerometer. Ninety FBG accelerometers are successfully installed on the site of the FAST project, where they are precisely measuring and documenting the magnitude of force exerted on the edge cables.

A symmetrical dual-mass block fiber Bragg grating vibration sensor based on a V-shaped flexible hinge

Real-time monitoring of vibration properties in micro-seismic applications, such as petroleum exploration, physical oceanography, and perimeter security, is important for deep exploration and the prediction of geological disasters and other fields. The fiber Bragg grating (FBG) vibration sensor with symmetrical V-shaped flexible hinges and a dual mass block is proposed. Utilizing formula derivation and simulation software, the sensor's structural parameters are optimized and subjected to analysis. These simulations inform the fabrication of the actual sensor, and subsequently, the sensor's performance is empirically tested. The results show an average sensitivity of 73.86 pm/G and a natural frequency of 800 Hz, with a working range of 20–340 Hz. Its exhibits anti-interference in the transverse direction is less than 5 % during vibration measurement. The research outcomes offer a point of guidance for the progress of FBG accelerometer development within applications that involve measuring low- to medium-frequency accelerations.

Development of a low-frequency accelerometer based on symmetric multi-stage triangular beam fiber Bragg grating

In order to meet the needs of accelerometers for low-frequency seismic exploration, a fiber-optic grating accelerometer based on a symmetric multi-stage triangular hinge is proposed. The sensitivity of the accelerometer is improved by the symmetrical multi-stage triangular beam structure, and experimental verification is carried out. The resonant frequency and sensitivity equations of the accelerometer are given based on theoretical analysis, while the finite element analysis software is used to simulate and analyze the characteristics of the accelerometer such as resonant frequency, stress distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the influence of the structural parameters on the sensitivity and resonant frequency of the accelerometer is analyzed. The experimental results show that the accelerometer has a resonant frequency of 140 Hz and a linearity of 99.9 % in the flat region of 1–70 Hz, a sensitivity of 337.325 pm/g, and an interference immunity of 5.39 % in the lateral direction in the working axis direction. This indicates that the accelerometer shows good linearity and lateral interference immunity in the flat interval, which well meets the needs of seismic wave signal monitoring in the field of low-frequency oil and gas exploration.

Stiffness-Tunable Soft Bellows Actuators by Cross-Fiber Jamming Effect for Robust Grasping

Soft actuators typically exhibit low stiffness and low load-bearing properties due to the intrinsic limitations of soft materials. Stiffness modulation is an effective means to improve the performance of soft actuators. However, most stiffness-tunable mechanisms are nonstretchable, and have difficulty in independently adjusting the tensile stiffness of soft elongation actuators. Here, a universal cross-fiber jamming mechanism with both elongation and bending stiffness-tunable capability is proposed for soft bellows actuators. It is composed of two semicircular symmetrical fiber bundles in an up-and-down crossed arrangement, and can follow the tensile state of the soft bellows actuator through the passive staggered motion of the layered fiber bundles. Furthermore, a soft gripper with wide grasping range and sufficient grasping stability is also developed by applying soft bellows actuators with cross-fiber jamming mechanisms. Experiments are conducted to show the related performance of the proposed cross-fiber jamming mechanism. The results show that it has fast antiimpact damping response, strong shaping ability and adjustable stiffness. Such efficient performance will promote the ability of grasping robots, and is expected to be used in daily life and industry.

Multi-wavelength fiber laser with high-purity LP11 output mode based on a symmetrical fiber mode selective coupler and Sagnac interferometer

In this work, a multi-wavelength fiber laser with a high-purity LP11 output mode was proposed and experimentally demonstrated. More specifically, a novel symmetrical fiber mode selective coupler (MSC) was utilized for mode conversion and a Sagnac interferometer is fabricated as a multi-channel filter for wavelength selection. From the experimental results, it was shown that the laser was able to emit stable single-, dual-, and triple-wavelength outputs both around 1530 nm and 1550 nm, and the purity of the LP11 mode was above 97 % and 98 % at the two bands respectively. In addition, the laser was capable of simultaneous dual-wavelength emission around 1530 nm and 1550 nm, resulting in an overall four-wavelength output with an LP11 mode purity of above 98 %. The proposed high-order mode multi-wavelength fiber laser has potential applications in various fields including optical communications, optical sensing, and materials processing.

A contact model based on the coefficient of restitution for simulations of bio-prosthetic heart valves.

A new general contact model is proposed for preventing inter-leaflet penetration of bio-prosthetic heart valves (BHV) at the end of the systole, which has the advantage of applying kinematic constraints directly and creating smooth free edges. At the end of each time step, the impenetrability constraints and momentum exchange between the impacting bodies are applied separately based on the coefficient of restitution. The contact method is implemented in a rotation-free, large deformation, and thin shell finite-element (FE) framework based on loop's subdivision surfaces. A nonlinear, anisotropic material model for a BHV is employed which uses Fung-elastic constitutive laws for in-plane and bending responses, respectively. The contact model is verified and validated against several benchmark problems. For a BHV-specific validation, the computed strains on different regions of a BHV under constant pressure are compared with experimentally measured data. Finally, dynamic simulations of BHV under physiological pressure waveform are performed for symmetrical and asymmetrical fiber orientations incorporating the new contact model and compared with the penalty contact method. The proposed contact model provides the coaptation area of a functioning BHV during the closing phase for both of the fiber orientations. Our results show that fiber orientation affects the dynamic of leaflets during the opening and closing phases. A swirling motion for the BHV with asymmetrical fiber orientation is observed, similar to experimental data. To include the fluid effects, fluid-structure interaction (FSI) simulation of the BHV is performed and compared to the dynamic results.

Symmetrical dual D-shape fiber for waveguide coupled surface plasmon resonance sensing

A waveguide-coupled surface plasmon resonance (WCSPR) sensor consisting of two D-shape single-mode fibers is designed and analyzed by the finite element method (FEM). The optical field of the surface plasmon polaritons (SPPs) mode is confined in the dielectric cavity between the dual metallic thin films. Therefore, the effective refractive index of the SPP mode depends largely on the refractive index of the analyte and an anomalous dispersion relationship is observed between the SPP mode and x-polarized core-guide mode of the dual D-shape fiber. The excitation mechanism of surface plasmon resonance (SPR) in the coupling region is attributed to phase matching of the two modes. Further analysis shows that the narrow bandwidth peak in the loss spectrum of the core mode is determined by the sensor dimensions contributed jointly by the thicknesses of the silver film, dielectric layer, and titanium dioxide film. Compared to the single-fiber structure, the optimized dual D-shape WCSPR sensor achieves a maximum wavelength sensitivity of 52,200 nm/RIU with a full-width at half-minimum (FWHM) of 9.47 nm and a figure of merit (FOM) of 346.6 RIU−1 in the analyte refractive index range of 1.32–1.42.

Dual-ring parity-time symmetric brillouin fiber laser with an unbalanced polarization Mach-Zehnder interferometer.

A dual-ring parity-time (PT) symmetric Brillouin fiber laser (BFL) with an unbalanced polarization Mach-Zehnder interferometer (UP-MZI) is proposed and experimentally investigated. An UP-MZI consisting of optical coupler, polarization beam combiner (PBC) and two asymmetric length arms with 10 km and 100 m single-mode fiber, is used to achieve Vernier effect and PT symmetry. Due to the orthogonally polarized lights created in the PBC, the dual-ring PT symmetry BFL with an UP-MZI implements two unbalanced length feedback rings that are connected to one another, one long length ring with a Brillouin gain and the other short length ring with a loss of the same magnitude, to break a PT symmetric and maintain the Vernier effect. By contrast with existing PT symmetry BFL studies, this design does not require same lengths of the gain and loss loops, but can manipulate freely PT symmetry status in accordance with a rational scaling factor between them. Experimental results reveal that the 3-dB linewidth of dual-ring PT symmetry BFL with an UP-MZI is about 4.85 Hz with the threshold input power of 9.5 mW, in accordance with the 97 Hz measured linewidth at the -20 dB power point. Within 60 mins of the stability experiment, the power and frequency stability fluctuation are ±0.02 dB and ±0.137 kHz, respectively. Thanks to the two asymmetric ring lengths, the sidemode suppression ratio (SMSR) is optimized by 54 dB compared to that with the only long ring structure, 26 dB when using only the Vernier effect or 12 dB for existing PT symmetry BFL. This BFL design with single longitudinal mode and high SMSR output can be applied to high coherent communication and Brillouin-based microwave photonics systems with low phase noise.

Early committed polarization of intracellular tension in response to cell shape determines the osteogenic differentiation of mesenchymal stromal cells.

Within the heterogeneous tissue architecture, a comprehensive understanding of how cell shapes regulate cytoskeletal mechanics by adjusting focal adhesions (FAs) signals to correlate with the lineage commitment of mesenchymal stromal cells (MSCs) remains obscure. Here, via engineered extracellular matrices, we observed that the development of mature FAs, coupled with a symmetrical pattern of radial fiber bundles, appeared at the right-angle vertices in cells with square shape. While circular cells aligned the transverse fibers parallel to the cell edge, and moved them centripetally in a counter-clockwise direction, symmetrical bundles of radial fibers at the vertices of square cells disrupted the counter-clockwise swirling and bridged the transverse fibers to move centripetally. In square cells, the contractile force, generated by the myosin IIA-enriched transverse fibers, were concentrated and transmitted outwards along the symmetrical bundles of radial fibers, to the extracellular matrix through FAs, and thereby driving FA organization and maturation. The symmetrical radial fiber bundles concentrated the transverse fibers contractility inward to the linkage between the actin cytoskeleton and the nuclear envelope. The tauter cytoskeletal network adjusted the nuclear-actomyosin force balance to cause nuclear deformability and to increase nuclear translocation of the transcription co-activator YAP, which in turn modulated the switch in MSC commitment. Thus, FAs dynamically respond to geometric cues and remodel actin cytoskeletal network to re-distribute intracelluar tension towards the cell nucleus, and thereby controlling YAP mechanotransduction signaling in regulating MSC fate decision. STATEMENT OF SIGNIFICANCE: We decipher how cellular mechanics is self-organized depending on extracellular geometric features to correlate with mesenchymal stromal cell lineage commitment. In response to geometry constrains on cell morphology, symmetrical radial fiber bundles are assembled and clustered depending on the maturation state of focal adhesions and bridge with the transverse fibers, and thereby establishing the dynamic cytoskeletal network. Contractile force, generated by the myosin-IIA-enriched transverse fibers, is transmitted and dynamically drives the retrograde movement of the actin cytoskeletal network, which appropriately adjusts the nuclear-actomyosin force balance and deforms the cell nucleus for YAP mechano-transduction signaling in regulating mesenchymal stromal cell fate decision.