Linear Array Research Articles

The WAVE complex forms linear arrays at negative membrane curvature to instruct lamellipodia formation.

Cells generate a wide range of actin-based membrane protrusions for various cell behaviors. These protrusions are organized by different actin nucleation promoting factors. For example, N-WASP controls finger-like filopodia, whereas the WAVE complex controls sheet-like lamellipodia. These different membrane morphologies likely reflect different patterns of nucleator self-organization. N-WASP phase separation has been successfully studied through biochemical reconstitutions, but how the WAVE complex self-organizes to instruct lamellipodia is unknown. Because WAVE complex self-organization has proven refractory to cell-free studies, we leverage in vivo biochemical approaches to investigate WAVE complex organization within its native cellular context. With single molecule tracking and molecular counting, we show that the WAVE complex forms highly regular multilayered linear arrays at the plasma membrane that are reminiscent of a microtubule-like organization. Similar to the organization of microtubule protofilaments in a curved array, membrane curvature is both necessary and sufficient for formation of these WAVE complex linear arrays, though actin polymerization is not. This dependency on negative membrane curvature could explain both the templating of lamellipodia and their emergent behaviors, including barrier avoidance. Our data uncover the key biophysical properties of mesoscale WAVE complex patterning and highlight an integral relationship between NPF self-organization and cell morphogenesis.

Linear Photodiode Arrays For Time-Domain FLEET Velocimetry In Hypersonic Flows

Linear photodiode arrays are applied to Femtosecond Laser Electronic Excitation Tagging (FLEET) to determine the stream-wise velocity of flow at Mach 8 in the Sandia Hypersonic Wind Tunnel (HWT). Incident light emitted by nitrogen gas upon FLEET excitation is collected by intensifying optics that amplify and transmit the light to the photodiode elements as the gas advects downstream. Two photodiode array configurations are considered: one aligned with the flow direction and one that is perpendicular to it. Conventional FLEET using a CMOS image sensor is also performed for quantitative comparison. The configurations are tested for purely free-stream cases as well as the wake of a seven-degree half-angle cone model at various Reynolds number. The influence of the bi-exponential decay of the FLEET line and the transfer function imposed by the intensifying optics are identified as key considerations on the time-domain method accuracy. Overcoming these effects leads to promising application spaces due to the compact nature of photodiodes and low data overhead.

Clustered protocadherin cis-interactions are required for combinatorial cell–cell recognition underlying neuronal self-avoidance

In the developing human brain, only 53 stochastically expressed clustered protocadherin (cPcdh) isoforms enable neurites from individual neurons to recognize and self-avoid while simultaneously maintaining contact with neurites from other neurons. Cell assays have demonstrated that self-recognition occurs only when all cPcdh isoforms perfectly match across the cell boundary, with a single mismatch in the cPcdh expression profile interfering with recognition. It remains unclear, however, how a single mismatched isoform between neighboring cells is sufficient to block erroneous recognitions. Using systematic cell aggregation experiments, we show that abolishing cPcdh interactions on the same membrane (cis) results in a complete loss of specific combinatorial binding between cells (trans). Our computer simulations demonstrate that the organization of cPcdh in linear array oligomers, composed of cis and trans interactions, enhances self-recognition by increasing the concentration and stability of cPcdh trans complexes between the homotypic membranes. Importantly, we show that the presence of mismatched isoforms between cells drastically diminishes the concentration and stability of the trans complexes. Overall, we provide an explanation for the role of the cPcdh assembly arrangements in neuronal self/non-self-discrimination underlying neuronal self-avoidance.

Connections between two classes of generalized Fibonacci numbers squared and permanents of (0,1) Toeplitz matrices

By considering the tiling of an N-board (a linear array of N square cells of unit width) with new types of tile that we refer to as combs, we give a combinatorial interpretation of the product of two consecutive generalized Fibonacci numbers s n (where s n = ∑ i = 1 q v i s n − m i , s 0 = 1 , s n < 0 = 0 , where v i and m i are positive integers and m 1 < ⋯ < m q ) each raised to an arbitrary non-negative integer power. A ( w , g ; m ) -comb is a tile composed of m rectangular sub-tiles of dimensions w × 1 separated by gaps of width g. The interpretation is used to give combinatorial proof of new convolution-type identities relating s n 2 for the cases q = 2, v i = 1 , m 1 = M , m 2 = m + 1 for M = 0, m to the permanent of a (0,1) Toeplitz matrix with 3 nonzero diagonals which are − 2 , M−1, and m above the leading diagonal. When m = 1, these identities reduce to ones connecting the Padovan and Narayana's cows numbers.

Contribution of the root system of Cyperus papyrus and Pontederia sagittata to microplastic removal in floating treatment Wetlands in two urban ponds

Microplastic pollution represents a global challenge that threatens ecosystems and human health. Because of this, there has been an increased interest in evaluating the use of phytotechnologies as a natural alternative for the removal of microplastics in water bodies. This study assessed the microplastic removal by Floating Treatment Wetlands (FTWs) consisting of linear arrays planted with Cyperus papyrus and Pontederia sagittata, installed in two urban ponds (“Pond 1” and “Pond 4”) located in the center of the city of Xalapa, Veracruz, Mexico. The results indicated that the two linear arrays of FTWs in Pond 1 (FTW1 and FTW2) efficiently removed microplastics in water column and sediments, with total removal rates of 82.4% and 81.1% respectively, despite having a high initial microplastic concentration. On the other hand, the effectiveness of the two FTWs in Pond 4 was mainly attributed to the first line of plants (FTW3), where the highest removal rates were observed, showing 61.6% in water column and 72.6% in sediments. However, the total removal of the two lines was 64.6% in water and 48.8% in sediments. C. papyrus and P. sagittata plants strongly retained microplastics in their roots, with concentrations of 16.4 and 11.9 mg/g respectively for FTW1 and FTW2 in Pond 1, and 2.1 and 6 mg/g for FTW3 and FTW 4 in Pond 4. These results suggest that the main removal microplastic mechanism was root retention, which facilitates microplastic removal from the aquatic environment by periodical root harvesting. Therefore, the crucial role of roots in the stabilization and reduction of these pollutants is highlighted. This study represents the first report in Mexico on the efficiency of FTWs in removing microplastics in urban water bodies.

Extraction of Acoustic Normal Mode Depth Functions Using Range-Difference Method with Vertical Linear Array Data

Extraction of Acoustic Normal Mode Depth Functions Using Range-Difference Method with Vertical Linear Array Data

A High-Resolution Magnetic Field Imaging System Based on the Unpackaged Hall Element Array

We have designed a high-resolution magnetic field imaging system using 256 unpackaged Hall elements. These unpackaged Hall elements are arranged in a Hall linear array, and the distance between adjacent elements reaches 255 µm. The sensitivity of the unpackaged Hall element array can be adjusted using a computer to measure magnetic environments with different magnetic field strengths. High-resolution magnetic field images of 256 × 256 pixels can be generated by moving the array using the X–Y axis motorized rail. This spatial resolution can reach 99.61 pixels per inch (ppi). This rail allows for the spatial resolution of the system to be further increased to 199.22 ppi by using a special movement route. In the experiments, we employ this system to image magnetized metal scissors, and the result displays the structural features of the scissor surface. We also detected the magnetic suction wireless charging coil inside an Apple phone. The image obtained shows the shape of the coil and the gap between the magnets. The high-resolution magnetic imaging system displays the magnetic characteristics of the sample very well and easily obtains information about small-shaped structures and defects on the sample surface. This provides the system with potential in several fields such as quality inspection, security, biomedicine, and detection imaging.

Azimuth correction for passive surface wave dispersion based on polarization analysis

SUMMARY Passive surface wave methods have found extensive application in near-surface investigation due to their benefits of low costs, non-invasiveness and high accuracy. Linear arrays are usually adopted in urban environments for their convenience and efficiency. However, the distribution of noise sources in densely populated urban areas varies rapidly in time and space, making it challenging to estimate accurate dispersion spectra using a linear array. To solve this problem, we propose a polarization analysis-based azimuthal correction method. We first obtain the azimuth of each segment by calculating the correlation coefficient of three-component ambient noise data. The normalized correlation coefficient is then applied for quality control to select reliable segments. For selected segments, the overestimated velocity caused by directional sources are corrected to obtain accurate dispersion spectra. A synthetic test is conducted to demonstrate the feasibility of our method. Compared with the dispersion spectra obtained without any correction, the dispersion spectra obtained following the suggested scheme are more consistent with the theoretical dispersion curves. Two real-world examples at crossroads show the superiority of the proposed technique in obtaining higher resolution dispersion energy and more accurate phase velocities. In addition, our approach can attenuate the artefacts and improve the dispersion measurements.

Shallow Microtremor Array Survey Using Miniature and Small Arrays: Strategy for Efficient and Feasible Dense Survey

AbstractWe investigated the applicability of miniature microtremor arrays with a radius of a few meters or less to shallow surveys (up to a few tens of meters). It is shown that the upper limit wavelength normalized by the seismometer separation distance s that is analyzable by a miniature array does not depend on the observation instrument as long as the instrument has a self‐noise level that is sufficiently lower than the microtremor intensities; however, it generally depends on the average S‐wave velocity of the ground. This means that a miniature array is useful at soft‐soil sites but not hard‐soil sites. A statistical study in central Japan showed that the penetration depth by a miniature array with s = 1 m ranges from 6 to 12 m; specifically, the depth exceeds 12 m in one quarter of the cases but remains below 6 m in one quarter of the cases. This large variation is due to the variation in the average S‐wave velocity. A miniature array should thus be used in combination with a larger array with an s value of several meters to 20 m. In urbanized areas with high industrial activity, where the microtremor wavefield is likely isotropic, these arrays can be replaced by a linear array. In environments with extremely low signal‐to‐noise ratios, a less efficient zero‐crossing method should be applied to the larger array. An appropriate observation strategy should be selected for a given geoenvironment. Field examples show that our strategy enables efficient and feasible dense surveys.

A Miniaturized Phase Mode Antenna Based on a Radial SSPPs Structure and Its 1-D Linear Arrays

A Miniaturized Phase Mode Antenna Based on a Radial SSPPs Structure and Its 1-D Linear Arrays

Fine Crust‐Mantle Structure of the Major Tectonic Boundaries Between the North China Craton and Central Asian Orogenic Belt Revealed From Rayleigh Wave Phase Velocities and Receiver Functions

AbstractThe Tanlu Fault Zone (TLFZ) and Chifeng‐Kaiyuan Fault (CKF) serve as tectonic boundaries between the North China Craton (NCC) and the Central Asian Orogenic Belt (CAOB). Clarifying the refined structure of these tectonic boundaries is crucial for understanding the relationships between the tectonic units and the heterogeneity in the destruction of the NCC. In this study, two linear seismic arrays were deployed across these tectonic boundaries. Based on the phase velocity dispersion and receiver functions extracted from the seismic arrays, the Hamiltonian Monte Carlo algorithm was employed for the joint inversion of the S‐wave velocity (Vs) in the crust and uppermost mantle. The Vs model was then used to correct the time differences in common conversion point (CCP) stacking. The CCP stacking results indicate that the boundary faults TLFZ and CKF are both whole‐crustal faults that separate the NCC and CAOB. The Vs structure showed a significant low‐velocity anomaly in the mantle beneath the NCC, with intense seismic activity within the crust. This suggests that the NCC was affected by the subduction of the Western Pacific, leading to crustal and mantle destruction. In contrast, the CAOB exhibited a clear high‐velocity anomaly with relatively stable crustal structures. We believe that the NCC and CAOB have undergone structural modification and destruction due to the closure of the Paleo‐Asian Ocean and the activities of the TLFZ since the Late Mesozoic. During the Cenozoic, the region east of the TLFZ experienced more significant destruction in the NCC than the other adjacent tectonic units.

Synthesis of concentric circular antenna array for reducing the sidelobe level by employing sine cosine optimization algorithm

AbstractThe sine cosine algorithm (SCA), a meta‐heuristic optimization method, is used in this study to provide a precise linear and elliptical antenna array design for synthesizing the ideal far‐field radiation pattern in the fifth‐generation (5G) communication spectrum. The wireless communication system will undergo dramatic changes thanks to the forthcoming 5G technology, which offers exceptionally high data rates, increased capacity, reduced latency, and outstanding service quality. The most important component of 5G communications is an accurate antenna array design for an optimum far‐field radiation pattern synthesis with a suppressed sidelobe level (SLL) value and half power beam width (HPBW). While long‐distance communication necessitates a low HPBW, the entire side lobe area needs a suppressed SLL to prevent interference. The SCA is used in this case to the optimal feeding currents applied to each array member in the design examples of the concentric circular antenna arrays (CCAA) discussed in this article. It shows the litheness and attainment of the propound algorithm named SCA, chosen CCAAs with three rings and varying amounts of components or antenna array sets those are stated as follows: Set I (4, 6, 8 elements), Set II (8, 10, 12 elements), Set III (6, 12, 18 elements), Set IV (8, 14, 20 elements) with and without the center element are amalgamate. Apply the PSO, Jaya, and SCA optimization algorithms for all four Sets of antenna arrays and compare the attained results; the SLL values achieved by the SCA technique are contrasted with those of other current optimization techniques. The outcomes of all examinations reveal that the SCA algorithm achieved a superior SLL reduction over other optimization techniques.

An HF-Band Linear Retrodirective Array With Scale Model RCS Measurements

An HF-Band Linear Retrodirective Array With Scale Model RCS Measurements

Deblurring of Beamformed Images in the Ocean Acoustic Waveguide Using Deep Learning-Based Deconvolution

A horizontal towed linear coherent hydrophone array is often employed to estimate the spatial intensity distribution of incident plane waves scattered from the geological and biological features in an ocean acoustic waveguide using conventional beamforming. However, due to the physical limitations of the array aperture, the spatial resolution after conventional beamforming is often limited by the fat main lobe and the high sidelobes. Here, we propose a method originated from computer vision deblurring based on deep learning to enhance the spatial resolution of beamformed images. The effect of image blurring after conventional beamforming can be considered a convolution of beam pattern, which acts as a point spread function (PSF), and the original spatial intensity distributions of incident plane waves. A modified U-Net-like network is trained on a simulated dataset. The instantaneous acoustic complex amplitude is assumed following circular complex Gaussian random (CCGR) statistics. Both synthetic data and experimental data collected from the South China Sea Experiment in 2021 are used to illustrate the effectiveness of this approach, showing a maximum 700% reduction in a 3 dB width over conventional beamforming. A lower normalized mean square error (NMSE) is provided compared with other deconvolution-based algorithms, such as the Richardson–Lucy algorithm and the approximate likelihood model-based deconvolution algorithm. The method is applicable in various acoustic imaging applications that employ linear coherent hydrophone arrays with one-dimensional conventional beamforming, such as ocean acoustic waveguide remote sensing (OAWRS).

Antenna Selection and Receive Beamforming for Multi-Functional Sparse Linear Array via Consensus ADMM

Antenna Selection and Receive Beamforming for Multi-Functional Sparse Linear Array via Consensus ADMM

Multiscale Feature Fusion Method for Liver Cirrhosis Classification

ABSTRACTLiver cirrhosis is one of the most common liver diseases in the world, posing a threat to people's daily lives. In advanced stages, cirrhosis can lead to severe symptoms and complications, making early detection and treatment crucial. This study aims to address this critical healthcare challenge by improving the accuracy of liver cirrhosis classification using ultrasound imaging, thereby assisting medical professionals in early diagnosis and intervention. This article proposes a new multiscale feature fusion network model (MSFNet), which uses the feature extraction module to capture multiscale features from ultrasound images. This approach enables the neural network to utilize richer information to accurately classify the stage of cirrhosis. In addition, a new loss function is proposed to solve the class imbalance problem in medical datasets, which makes the model pay more attention to the samples that are difficult to classify and improves the performance of the model. The effectiveness of the proposed MSFNet was evaluated using ultrasound images from 61 subjects. Experimental results demonstrate that our method achieves high classification accuracy, with 98.08% on convex array datasets and 97.60% on linear array datasets. Our proposed method can classify early, middle, and late cirrhosis very accurately. It provides valuable insights for the clinical treatment of liver cirrhosis and may be helpful for the rehabilitation of patients.

Robust adaptive beamforming for cylindrical uniform conformal array

As we all know, conformal arrays can provide smaller radar cross-section (RCS) and greater angle coverage than conventional linear arrays and planar arrays. In this paper, we develop a robust adaptive beamforming (RAB) approach using the cylindrical uniform conformal array. Firstly, we reconstruct the interference-plus-noise covariance matrix (INCM) by estimating the steering vectors (SVs) and powers of all interferences. Specifically, we estimate the interference SVs by exploiting the MUSIC spectrum and corrected by solving a minimization problem based on the orthogonality between the interferences SVs and noise subspace, and the interferences powers are further estimated by utilizing the non-correlation between different signal SVs. With the reconstructed INCM, the SV of the signal-of-interest is estimated by solving a quadratically constrained quadratic programming problem. Numerical results demonstrate that the proposed approach is obviously superior to the existing RAB techniques.

Low sidelobe cosecant-squared pattern time-modulated antenna array with harmonic suppression

In this paper, a pulse shifting approach with phase-only weighting is proposed for a cosecant-squared radiation pattern time-modulated linear array (TMLA) synthesis. The sidelobe level (SLL) of fundamental signal and maximum sideband levels (SBLs) of harmonic signals is simultaneously reduced. This is achieved by controlling both the phase and the periodic switching time sequence of each element of the TMLA. In pulse shifting, the on–off switching sequence of each radiating element is characterized by a switch-on instant and interval within the modulation period which increases the degrees of freedom. A genetic algorithm (GA) is employed to optimize the switch-on and switch-off instants of each time pulse along with the phase weight for each element in the antenna array. The simulation results reveal that the proposed method can achieve the required patterns with very low SLL and SBLs.

Twisted and Disconnected Chains: Flexible Linear Tetracuprous Arrays and a Decanuclear CuI Cluster as Blue- and Green/Yellow-Light Emitters.

Defined arrays of transition metal ions embedded in tailored polydentate ligand scaffolds allow for a systematic design of their physical properties. Such molecular strings of closed-shell transition metal centers are particularly interesting for Group 11 metal ions in the oxidation state +1 if they undergo metallophilic d10···d10 contact interactions since these clusters are oftentimes efficient photoluminescence (PL) emitters. Copper is particularly attractive as a sustainable earth-abundant coinage metal source and because of the ability of several CuI complexes to serve as powerful thermally activated delayed fluorescence (TADF) emitters in molecular/organic light-emitting devices (OLEDs). Our combined synthetic, crystallographic, photophysical, and computational study describes a straight tetracuprous array possessing a centrally disconnected CuI2···CuI2 chain and a continuous helically bent CuI4 complex. This molecular helix undergoes a facile rearrangement in diethyl ether solution, yielding an unprecedented nanosized CuI10 cluster (2.9 × 2.0 nm) upon crystallization. All three clusters show either bright blue phosphorescence, TADF, or green/yellow multiband phosphorescence with quantum yields between 6.5 and 67%, which is persistent under hydrostatic pressure up to 30 kbar. Temperature-dependent PL investigations in combination with time-dependent density-functional theory (TD-DFT) calculations and void space analyses of the crystal packings complement a comprehensive correlation between the molecular structures and photoluminescence properties.

Annealing of bismuth telluride-based thick films by laser irradiation

Interest towards fabrication and post-processing of thermoelectric micro-sized devices has increased in recent years. The coupling of inexpensive deposition technologies and fast laser treatments on “as-deposited” films is an attractive solution for industrial scalability. In this work, we propose an approach never reported before in literature: the utilization of a ns-pulsed active fibre laser to directly densify p-type bismuth telluride-based thick films deposited on silicon. A feasibility study was conducted on the material to determine optimal laser parameters: the treated products were characterized, and it was concluded that a value of laser fluence as low as 4.5 mJ cm−2 is sufficient for densification. The material resulted cracked after the laser treatment, and it was demonstrated by SEM and profilometric analyses that shrinking occurs and sintering necks are formed; further, the arising of second phases after annealing was excluded by means of XRD analysis. Envisioning an industrial large area process with linear diode arrays source, a prediction of the laser power requirements to irradiate 1 mm2 films in selected conditions is presented. More extensive studies will be performed to determine a narrower parameters window and determine a relationship between the film thickness and laser parameters for future applications to as-deposited films.