optic flow

Overly dense microvascular networks are treated by selective reduction of vascular elements. Inappropriate manipulation of microvessels could result in loss of host tissue function or a worsening of the clinical problem. Here, experimental, and computational models were developed to induce blood flow changes via selective artery and vein laser ablation and study the compensatory collateral flow redistribution and vessel diameter remodeling. The microvasculature was imaged non-invasively by bright-field and multi-photon laser microscopy, and optical coherence tomography pre-ablation and up to 30 days post-ablation...

Optical and acoustic tweezers, despite operating on different physical principles, offer non-contact manipulation of microscopic and mesoscopic objects, making them essential in fields like cell biology, medicine, and nanotechnology. The advantages and limitations of optical and acoustic manipulation complement each other, particularly in terms of trapping size, force intensity, and flexibility. We use photoacoustic effects to generate localized Lamb wave fields capable of mapping arbitrary laser pattern shapes...

Relying on the strong optical absorption of hemoglobin to pulsed laser energy, photoacoustic microscopy provides morphological and functional information on microvasculature label-freely. Here, we propose speckle variance photoacoustic microscopy (SV-PAM), which harnesses intrinsic imaging contrast from temporal-varied photoacoustic signals of moving red blood cells in blood vessels, for recovering three-dimension hemodynamic images down to capillary-level resolution within the microcirculatory tissue beds in vivo ...

PURPOSE: To assess ocular blood flow (OBF) changes in patients with neovascular age-related macular degeneration (nAMD) treated with intravitreal injections of ranibizumab biosimilar (IVRbs) or brolucizumab (IVBr). METHODS: This retrospective longitudinal study included 43 eyes of 43 patients (74.5 ± 9.8 years old, male to female ratio 31:12) with nAMD treated with IVBr (29 eyes) or IVRbs (14 eyes). OBF in the optic nerve head (ONH) and choroid (Ch) was measured with laser speckle flowgraphy (Softcare Co...

Boron carbonitride (BCN) films containing hybridized bonds involving B, C, and N over wide compositional ranges enable an abundant variety of new materials, properties, and applications; however, their electronic performance is still limited by the presence of structural and electronic defects, yielding sluggish mobility and electrical conductivity. This work reports on mechanically stable BCN films and their corresponding optical and electronic properties. The ternary BCN films consisting of hybridized B-C-N bonds have been achieved by varying N2 flow by the radio frequency magnetron sputtering method...

BACKGROUND: To investigate the associations between retinal/choroidal microvasculature and carotid plaque in patients with CAD assessed by optical coherence tomography angiography (OCTA). METHODS: This study included 127 CAD patients with and 79 without carotid plaque. Each patient had both OCTA taken and digitized to determine retinal/choroidal thickness, vessel density and flow area and carotid ultrasound for carotid plaque size and stability measurement. The superficial capillary plexus (SCP), deep capillary plexus (DCP), out retina and choriocapillaris vessel density, out retina and choriocapillaris flow area, and full retina thickness were analyzed in the fovea centered 6 × 6 mm area...

Hybrid fs/ps coherent anti-Stokes Raman scattering (CARS) thermometry often utilizes ps probe pulses derived from pulse shaping or spectrally filtering the primary laser source or by synchronization with a low repetition rate external laser. This results in limited energy, spectral resolution, and/or repetition rate of the ps probe. In this work, a master-oscillator power-amplifier (MOPA) laser was synchronized to the oscillator of a Ti:sapphire regenerative amplifier to achieve high-energy (600 µJ), narrowband (58 ps) probe pulses at kHz repetition rates...

Focused laser differential interferometry (FLDI) is an important diagnostic for measuring density fluctuations in high-speed flows. Currently, however, high dynamic range FLDI is limited to photodiode measurements. In order to spatially resolve multiple locations within complex flows, we present a novel, to the best of our knowledge, refractive-optic imaging FLDI concept that not only produces two-dimensional images without scanning but also reduces the measurement noise floor of those images. To demonstrate this concept, a 33 × 33 grid of FLDI points is first generated using a microlens array...

Two-dimensional materials possess a large number of interesting and important properties. Various methods have been developed to assemble two-dimensional aggregates. Assembly of colloidal particles can be achieved with laser-heating-induced thermal convective flow. In this paper, an opto-hydrodynamic binding method is proposed to assemble colloidal particles dispersed in a solution into multilayer structures. First, we use polystyrene (PS) microspheres to study the feasibility and characteristics of the assembly method...

Nonlinear optical microscopy enables non-invasive imaging in scattering samples with cellular resolution. The spinal cord connects the brain with the periphery and governs fundamental behaviors such as locomotion and somatosensation. Because of dense myelination on the dorsal surface, imaging to the spinal grey matter is challenging, even with two-photon microscopy. Here we show that three-photon excited fluorescence (3PEF) microscopy enables multicolor imaging at depths of up to ~550 μm into the mouse spinal cord, in vivo ...

Understanding driving forces for dissipative, i.e., out of equilibrium, assembly of nanoparticles from colloidal solution at liquid-solid interfaces provides the ability to design external cues for reconfigurable device response. Here electrohydrodynamic flow (EHD) at an electrode-liquid interface is investigated as a dissipative driving force for tuning optical response. EHD results from an oscillatory electric field in a liquid cell between two electrodes and drives assembly of gold nanoparticles (NP) into two-dimensional clusters on electrode surfaces...

Relative localization (RL) and circumnavigation is a highly challenging problem that is crucial for the safe flight of multi-UAVs (multiple unmanned aerial vehicles). Most methods depend on some external infrastructure for positioning. However, in some complex environments such as forests, it is difficult to set up such infrastructures. In this paper, an approach to infrastructure-free RL estimations of multi-UAVs is investigated for circumnavigating a slowly drifting UGV0 (unmanned ground vehicle 0), where UGV0 serves as the RL and circumnavigation target...

This paper investigates non-invasive techniques for annular two-phase flow analysis, focusing on liquid film characterization to understand the interfacial phenomena that are crucial for heat and mass transfer. Limited methods allow the study of the temporal and spatial evolution of liquid film, such as Planar Laser-Induced Fluorescence (PLIF). However, this method possesses optical challenges, leading to the need for improved techniques to mitigate refraction and reflection, such as Refractive Index Matching (RIM)...

Video super-resolution (VSR) remains challenging for real-world applications due to complex and unknown degradations. Existing methods lack the flexibility to handle video sequences with different degradation levels, thus failing to reflect real-world scenarios. To address this problem, we propose a degradation-adaptive video super-resolution network (DAVSR) based on a bidirectional propagation network. Specifically, we adaptively employ three distinct degradation levels to process input video sequences, aiming to obtain training pairs that reflect a variety of real-world corrupted images...

This paper proposes a new sensor using optical flow to stabilize a quadrotor when a GPS signal is not available. Normally, optical flow varies with the attitude of the aerial vehicle. This produces positive feedback on the attitude control that destabilizes the orientation of the vehicle. To avoid this, we propose a novel sensor using an optical flow camera with a 6DoF IMU (Inertial Measurement Unit) mounted on a two-axis anti-shake stabilizer mobile aerial gimbal. We also propose a robust algorithm based on Sliding Mode Control for stabilizing the optical flow sensor downwards independently of the aerial vehicle attitude...

PURPOSE: To document vascular changes in eyes with post-fever retinitis (PFR) pre and post treatment demonstrated using optical coherence tomography angiography (OCTA). METHODS: This is a retrospective observational case series wherein patients with PFR were retrospectively evaluated for changes in the retinal vasculature during the course of disease using OCTA. RESULTS: At presentation, OCTA revealed flow void areas in superficial and deep capillary plexus (SCP and DCP) corresponding to the areas of retinitis...

Vanadium dioxide (VO2 ) stands out for its versatility in numerous applications, thanks to its unique reversible insulator-to-metal phase transition. This transition can be initiated by various stimuli, leading to significant alterations in the material's characteristics, including its resistivity and optical properties. As the interest in the material is growing year by year, the purpose of this review is to explore the trends and current state of progress on some of the applications proposed for VO2 in the field of sensors and actuators using literature review methods...

The reversal potential refers to the membrane potential at which the net current flow through a channel reverses direction. The reversal potential is determined by transmembrane ion gradients and, in turn, determines how the channel's activity will affect the membrane potential. Traditional investigation into the reversal potential of inhibitory ligand-gated ion channels (EInh ) has relied upon the activation of endogenous receptors, such as the GABA-A receptor (GABAA R). There are, however, challenges associated with activating endogenous receptors, including agonist delivery, isolating channel responses, and the effects of receptor saturation and desensitization...

PURPOSE: To evaluate best corrected visual acuity (BCVA), retina sensitivity (RS) and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of inner and outer retinal layers (DRIL/DROL) and ischemia in OCT/OCT-Angiography(OCT-A) in diabetic retinopathy (DR). DESIGN: Retrospective case-control study. SUBJECTS: Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, active proliferative DR...

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are excellent candidates for high-performance optoelectronics due to their high carrier mobility, air stability and strong optical absorption. However, photodetectors made with monolayer TMDs often exhibit a high dark current, and thus, there is a scope for further improvement. Herein, we developed a 2D bilayer tungsten disulfide (WS2 ) based photodetector (PD) with asymmetric contacts that exhibits an exceptionally low dark current and high specific detectivity...