Opposite Side Research Articles

Decomposition-assisted analysis of transmission in periodic resonator arrays using mode-matching method.

This paper focuses on analysing acoustic structures containing locally reacting resonators, aiming to establish a framework for discussing sound properties related to scattering and transmission in a periodic resonator array. The paper introduces an analytical model for the input surface impedance of non-uniform resonator arrays, which is a challenging task when addressing sound propagation to the opposite side of the array. To address this challenge, a mode-matching method is employed within a one-dimensional periodic structure combined with the decomposition of the initial mirror-symmetric system into symmetric and antisymmetric sub-systems. This procedure leads to simplified analytical solutions of transmission problems about non-uniform resonator arrays, and its accuracy is verified through numerical simulations. The proposed method provides insights into mode shapes and amplitudes, thereby complementing numerical simulations and enabling a comprehensive understanding of sound fields beyond conventional results such as pressure fields and sound absorption coefficients alone. The model of a periodic varying-height resonator array presented herein involves developing mathematical equations or simulations to capture the physical characteristics and interactions of the resonators. This approach empowers researchers to predict and comprehend the non-uniform array's transmission behaviour and performance characteristics, with diverse applications spanning various systems, including electromagnetic devices.

Anomalous droplet transfer by surface acoustic waves through a microgap under a thin barrier

The transfer of droplets through a microgap under a thin barrier in the direction opposite to the motion of the surface acoustic waves (SAWs) acting on them has been discovered. Initially, the droplets are in contact with the barrier on the side opposite the SAW source. Under the SAW action, the transfer of a significant portion of the droplet volume through the microgap to the opposite side of the barrier is observed. This is in contrast to the behavior of droplets not in contact with the barrier. These droplets move in the direction of SAW motion. Experiments were performed to determine the effects of droplet size, SAW source power, and barrier wettability on the intensity of anomalous transfer. In addition, a computer simulation of a system simpler than the original was performed to identify the processes responsible for droplet growth on the side of the barrier facing the SAW source. Based on the analysis of the experimental and computational results, a model is proposed to explain the discovered phenomenon. The model assumes that the initial stage of anomalous transfer is due to atomization–coalescence, and the subsequent, more intense stage is due to the specificity of the streams circulating in the growing droplets. The article also shows that in a system of two parallel barriers, anomalous transfer allows either droplet division or droplet division and mixing.

The Faustini Permanently Shadowed Region on the Moon

Faustini crater (41 km diameter) hosts a large (664 km2) permanently shadowed region (PSR) with a high potential to harbor water-ice deposits. One of the 13 candidate Artemis III landing areas contains a portion of the crater rim and proximal ejecta. The ShadowCam instrument aboard the Korea Pathfinder Lunar Orbiter provides detailed images of the PSR within Faustini. We characterize the terrain and thermal environment within the Faustini PSR from ShadowCam images, Lunar Reconnaissance Orbiter thermal measurements and laser ranging, and thermal modeling. Our mapping revealed three distinct areas of the floor of Faustini based on elevations, slopes, and surface roughness. These units broadly correlate with temperatures; thus, they may be influenced by variations in volatile sublimation. Crater retention and topographic diffusion rates appear to be asymmetric across the floor, likely due to differences in maximum and average temperatures. Several irregular depressions and a pronounced lobate-rim crater are consistent with subsurface ice. However, differences in the thicknesses of deposited materials on the floor may also explain the asymmetry. Additionally, zones of elevated surface roughness across Faustini appear to result from overprinted crater ray segments, possibly from Tycho and Jackson craters. Mass wasting deposits and pitting on opposite sides of the crater wall may have resulted from the low-angle delivery of material ejected by the Shackleton crater impact event, suggesting that the Artemis III candidate landing region named “Faustini Rim A” will contain material from Shackleton.

Multi-angle speed-of-sound imaging with sparse sampling to characterize medical tissue properties

Medical Speed-of-sound (SoS) imaging, which can characterize medical tissue properties better by quantifying their different SoS, is an effective imaging method compared with conventional B-mode ultrasound imaging. As a commonly used diagnostic instrument, a hand-held array probe features convenient and quick inspection. However, artifacts will occur in the single-angle SoS imaging, resulting in indistinguishable tissue boundaries. In order to build a high-quality SoS image, a number of raw data are needed, which will bring difficulties to data storage and processing. Compressed sensing (CS) theory offers theoretical support to the feasibility that a sparse signal can be rebuilt with random but less sampling data. In this study, we proposed an SoS reconstruction method based on CS theory to process signals obtained from a hand-held linear array probe with a passive reflector positioned on the opposite side. The SoS reconstruction method consists of three parts. Firstly, a sparse transform basis is selected appropriately for a sparse representation of the original signal. Then, considering the mathematical principles of SoS imaging, the ray-length matrix is used as a sparse measurement matrix to observe the original signal, which represents the length of the acoustic propagation path. Finally, the orthogonal matching pursuit algorithm is introduced for image reconstruction. The experimental result of the phantom proves that SoS imaging can clearly distinguish tissues that show similar echogenicity in B-mode ultrasound imaging. The simulation and experimental results show that our proposed method holds promising potential for reconstructing precision SoS images with fewer signal samplings, transmission, and storage.

Reconstructing Quadriceps Tendon Disruptions in Post Total Knee Arthroplasty Patients with an Autogenous Peroneal Tendon Graft: A Viable Alternative.

Quadriceps tendon disruption post-total knee arthroplasty (TKA) is rare. Existing reconstruction procedures use allografts or synthetic meshes with varied success. This study evaluates outcomes with autogenous peroneal tendon grafts, a cost-effective alternative, compared to synthetic polypropylene mesh for quadriceps reconstruction. 16 patients who underwent extensor mechanism reconstruction between 2017 and 2021were retrospectively analysed. Parameters evaluated included type of reconstruction, extensor lag, IKDC (International Knee Documentation Committee) Score and AOFAS-Hindfoot-score (American Orthopaedic Foot and Ankle Society). At final follow-up, extensor lag for peroneal autograft group was 6.6° ± 1.5 and for synthetic polypropylene mesh group, 7.2° ± 0.7. Both groups improved in IKDC score (p < 0.01) AOFAS-Hindfoot-score was comparable for peroneal autograft patients with opposite side (p = 0.15). Autogenous peroneal tendon graft for quadriceps reconstruction could be viable, cost-effective alternative to allografts or synthetic meshes, with good clinical outcomes. Graphical abstract depicting the harvesting of the peronei grafts and their passage through the quadriceps tendon. Sonographic image showing the preoperative presence of a gap in the quadriceps tendon which is reconstructed post-operatively. The online version contains supplementary material available at 10.1007/s43465-024-01247-8.

Defining the glenohumeral range of motion required for overhead shoulder mobility: an observational study.

Recovery of overhead mobility after shoulder surgery is time-consuming and important for patient satisfaction. Overhead stretching and mobilization of the scapulothoracic and glenohumeral (GH) joints are common treatment interventions. The isolated GH range of motion (ROM) of flexion, abduction, and external rotation required to move above 120° of global shoulder flexion in the clinical setting remains unclear. This study clarified the GH ROM needed for overhead mobility. The timely development of shoulder ROM in patients after shoulder surgery was analyzed. Passive global shoulder flexion, GH flexion, abduction, and external rotation ROM were measured using goniometry and visually at 2-week intervals starting 6-week postsurgery until the end of treatment. Receiver operating characteristic curves were used to identify the GH ROM cutoff values allowing overhead mobility. A total of 21 patients (mean age 49 years; 76% men) after rotator cuff repair (71%), Latarjet shoulder stabilization (19%), and arthroscopic biceps tenotomy (10%) were included. The ROM cutoff value that accurately allowed overhead mobility was 83° for GH flexion and abduction with the area under the curve (AUC) ranging from 0.90 to 0.93 (p < 0.001). The cutoff value for GH external rotation was 53% of the amount of movement on the opposite side (AUC 0.87, p < 0.001). Global shoulder flexion above 120° needs almost full GH flexion and abduction to be executable. External rotation ROM seems less important as long as it reaches over 53% of the opposite side.

Enthesitis on Chip - A Model for Studying Acute and Chronic Inflammation of the Enthesis and its Pharmacological Treatment.

Enthesitis, the inflammation of the enthesis, which is the point of attachment of tendons and ligaments to bones, is a common musculoskeletal disease. The inflammation often originates from the fibrocartilage region of the enthesis as a consequence of mechanical overuse or -load and consequently tissue damage. During enthesitis, waves of inflammatory cytokines propagate in(to) the fibrocartilage, resulting in detrimental, heterotopic bone formation. Understanding of human enthesitis and its treatment options is limited, also because of lacking in vitro model systems that can closely mimic the pathophysiology of the enthesis and can be used to develop therapies. In this study, an enthes(it)is-on-chip model is developed. On opposite sides of a porous culture membrane separating the chip's two microfluidic compartments, human mesenchymal stromal cells are selectively differentiated into tenocytes and fibrochondrocytes. By introducing an inflammatory cytokine cocktail into the fibrochondrocyte compartment, key aspects of acute and chronic enthesitis, measured as increased expression of inflammatory markers, can be recapitulated. Upon inducing chronic inflammatory conditions, hydroxyapatite deposition, enhanced osteogenic marker expression and reduced secretion of tissue-related extracellular matrix components are observed. Adding the anti-inflammatory drug celecoxib to the fibrochondrocyte compartment mitigates the inflammatory state, demonstrating the potential of the enthesitis-on-chip model for drug testing.

An analysis of the interaction between surface and basal crevasses in ice shelves

Abstract. The prescription of a simple and robust parameterization for calving is one of the most significant open problems in ice sheet modelling. One common approach to the modelling of crevasse propagation in calving in ice shelves is to view crevasse growth as an example of linear elastic fracture mechanics. Prior work has, however, focused on highly idealized crack geometries, with a single fracture incised into a parallel-sided slab of ice. In this paper, we study how fractures growing from opposite sides of such an ice slab interact with each other, focusing on different simple crack arrangements: we consider either perfectly aligned cracks or periodic arrays of laterally offset cracks. We visualize the dynamics of crack growth using simple tools from dynamical systems theory and find that aligned cracks tend to impede each other's growth due to the torques generated by normal stresses on the crack faces, while periodically offset cracks facilitate simultaneous growth of bottom and top cracks. For periodic cracks, the presence of multiple cracks on one side of the ice slab, however, also generates torques that slow crack growth, with widely spaced cracks favouring calving at lower extensional stresses than closely spaced cracks.

Towards spatially selective efferent neuromodulation: anatomical and functional organization of cardiac fibres in the porcine cervical vagus nerve.

Spatially selective vagus nerve stimulation (sVNS) offers a promising approach for addressing heart disease with enhanced precision. Despite its therapeutic potential, VNS is limited by off-target effects and the need for time-consuming titration. Our research aimed to determine the spatial organization of cardiac afferent and efferent fibres within the vagus nerve of pigs to achieve targeted neuromodulation. Using trial-and-error sVNS in vivo and ex vivo micro-computed tomography fascicle tracing, we found significant spatial separation between cardiac afferent and cardiac efferent fibres at the mid-cervical level and they were localized on average on opposite sides of the nerve cross-section. This was consistent between both in vivo and ex vivo methods. Specifically, cardiac afferent fibres were located near pulmonary fibres, consistent with findings of cardiopulmonary convergent circuits and, notably, cardiac efferent fascicles were exclusive. These cardiac efferent regions were located in close proximity to the recurrent laryngeal regions. This is consistent with the roughly equitable spread across the nerve of the afferent and efferent fibres. Our study demonstrated that targeted neuromodulation via sVNS could achieve scalable heart rate decreases without eliciting cardiac afferent-related reflexes; this is desirable for reducing sympathetic overactivation associated with heart disease. These findings indicate that understanding the spatial organization of cardiac-related fibres within the vagus nerve can lead to more precise and effective VNS therapy, minimizing off-target effects and potentially mitigating the need for titration. KEY POINTS: Spatially selective vagus nerve stimulation (sVNS) presents a promising approach for addressing chronic heart disease with enhanced precision. Our study reveals significant spatial separation between cardiac afferent and efferent fibres in the vagus nerve, particularly at the mid-cervical level. Utilizing trial-and-error sVNS in vivo and micro-computed tomography fascicle tracing, we demonstrate the potential for targeted neuromodulation, achieving therapeutic effects such as scalable heart rate decrease without stimulating cardiac afferent-related reflexes. This spatial understanding opens avenues for more effective VNS therapy, minimizing off-target effects and potentially eliminating the need for titration, thereby expediting therapeutic outcomes in myocardial infarction and related conditions.

Environmentally clean and dirty energy equities during extraordinary global conditions

I examine which extraordinary international events coincide with pronounced changes in the equity markets for some of the world’s largest publicly traded suppliers on opposite sides of the global energy mix — oil and environmentally clean energy companies. First, I adapt an intuitively appealing non-parametric filter to empirically timestamp unexpected and prominent increases and decreases in a wide range of global indicators relevant to the international energy market. Then, I use such extraordinary conditions to characterise the performance of oil and environmentally clean energy equities, and their relationships. My findings suggest that jumps in the global stock market, international crude oil market shocks, and the US dollar real effective exchange rate, are the indicators that define the financial landscape during which considerable gains, losses, and instability across both types of energy markets materialise. In contrast, major elevated uncertainties related to geo-political risk and climate policy reflect relative stability in the equities of both oil and environmentally clean energy companies. Although these results imply that both energy assets are potentially lucrative hedging strategies for investors to exploit during heightened geo-political and climate policy uncertainties, clean energy equities offer market participants the option to combine profit maximising and sustainability objectives while minimising global energy security risks.

The Complex Star Formation History of the Halo of NGC 5128 (Cen A)

NGC 5128 (Cen A) is the nearest giant elliptical galaxy and one of the brightest extragalactic radio sources in the sky, boasting a prominent dust lane and jets emanating from its nuclear supermassive black hole. In this paper, we construct the star formation history (SFH) of two small fields in the halo of NGC 5128: a northeastern field (Field 1) at a projected distance of ∼18.8 kpc from the center, and a southern field (Field 2) ∼9.9 kpc from the center. Our method is based on identifying long-period variable (LPV) stars that trace their sibling stellar population and hence historical star formation due to their high luminosity and strong variability; we identified 395 LPV stars in Field 1 and 671 LPV stars in Field 2. Even though the two fields are ∼28 kpc apart on opposite sides from the center, they show similar SFHs. In Field 1, the star formation rate (SFR) increased significantly around t ∼ 800 Myr and t ∼ 3.8 Gyr and in Field 2, the SFR increased considerably around t ∼ 800 Myr, t ∼ 3.8 Gyr, and t ∼ 6.3 Gyr, where t is the lookback time. The increase in SFR ∼800 Myr ago agrees with previous suggestions that the galaxy experienced a merger around that time. The SFH reconstructed from LPV stars supports a scenario in which multiple episodes of nuclear activity lead to episodic jet-induced star formation. While there is no catalog of LPV stars for the central part of NGC 5128, applying our method to the outer regions (for the first time in a galaxy outside the Local Group) has enabled us to put constraints on the complex evolution of this cornerstone galaxy.

Design Analysis of 4H-SiC MOSFET for High Power Application

Abstract Silicon Carbide has emerged as a promising candidate due to its superior material properties such as high breakdown voltage, wide bandgap, and high thermal conductivity. A new vertical trench-based high power MOSFET (VTMOS) on 4H-SiC is presented. The VTMOS device features two trenches, each containing a poly-Si gate positioned on opposite sides of the P-base region. This configuration results in two parallel channels within the device. The unique design of the VTMOS leverages the RESURF effect and parallel conduction of the drive current, leading to notable performance improvements. The AC and DC characteristics of the VTMOS are analyzed and compared with PRMOS using 2-D simulations. The results demonstrate the superior performance of the VTMOS compared to the PRMOS. Specifically, the VTMOS exhibits 2.35 times higher drive current, an 88% enhancement in gain, 52% higher breakdown voltage, an 11% reduction in threshold potential, a 43% decrease in on-resistance, and 5.55 times higher FOM compared to the PRMOS.&amp;#xD;

Effects of monaural sound stimulation on subjective visual vertical.

Sound stimulation can influence electrophysiological vestibular reflexes. However, the effects of sound stimulation on space perception remain unknown. To know the effects of monaural sound stimulation on subjective visual vertical (SVV). We measured SVV with and without monaural sound stimulation (105 dB, 500 Hz short tone burst presented at 4.7 Hz) in 50 healthy volunteers (aged 20-77 [mean = 42.7] years). The mean SVV was deviated 0.139° to the left by right monaural sound stimulation and 0.123° to the right by left monaural sound stimulation. SVV changes due to right and left ear stimulations were significantly different (p = 0.019). Sound stimulation resulted in a significant change in SVV on the left side (p = 0.014) in participants aged 50 or younger (mean = 35.6 years) (n = 37). This study is the first to show the possibility that the monaural sound input deviates the SVV toward the opposite side and is more pronounced for left-ear input. The vestibular-evoked myogenic potential responses may be involved in the mechanism of the contralateral SVV deviation due to sound input.

Molecular design and theoretical investigation of TNI based materials

A series of highly symmetrical 2,4,5-trinitroimidazole (TNI) based energetic materials are designed. Based on the structures that optimized by density functional theory at the B3LYP/6-311G(d,p) level, their spectrum, heats of formation, detonation properties, thermal stability and thermodynamics are investigated. The results show that the −NN- bridge will be the most effective bridge to increase the heats of formation while the effect of –CH2CH2- bridge is on the opposite side. Compound G possesses the highest value of heat of detonation, detonation velocity and detonation pressure which reveals that heat of formation plays an important role in the detonation properties rather than the density. The calculated values of bond dissociation energy show that all the designed compounds (except for compound I) are more stable than those of RDX and HMX. Finally, their electronic structures and non-covalent interaction are simulated which may shine lights on the physicochemical properties of the designed compounds.

Molecular phylogenetic reassessment of eastern Atlantic Callinectes (Brachyura, Portunidae)

Abstract Several species from the genus Callinectes are economically important, yet the number of species and their geographic distributions remain unclear. Recently, one of the American species, Callinectes larvatus, was synonymized with one of the African species, C. marginatus, making C. marginatus the only species of the genus regarded to be amphi-Atlantic in distribution. However, there was no formal taxonomic study to support this taxonomic change, which was in contradiction to earlier studies that had provided morphological characters to support the taxonomic separation of the eastern Atlantic species from those of western Atlantic distribution. Callinectes maracaiboensis has also been questionably resurrected. Here we present a molecular based analysis for all species of Callinectes, using the two common mitochondrial genes 16S and 12S. Our molecular data support the presence of three eastern Atlantic, three eastern Pacific, and nine western Atlantic species. Historically, it appears that the separation of Africa and South America with the opening of the Atlantic basin gave rise to sister species distributed on opposite sides of the Atlantic Ocean. In a second isolation event, the emergence of the Panamanian isthmus resulted in pairs of geminate species distributed in eastern Pacific and western Atlantic waters.

Modeling of an electro-active pseudo-trilayer based on PEDOT, a semi-conductor polymer

Abstract Electroactive polymers are smart materials that can be used as actuators, sensors, or energy harvesters. We focus on a pseudo trilayer based on PEDOT, a semiconductor polymer: the central part consists of two interpenetrating polymers and PEDOT is polymerized on each side; the whole blade is saturated with an ionic liquid. A pseudo trilayer is obtained, the two outer layers acting as electrodes. When an electric field is applied, the cations move towards the negative electrode, making it swell, while the volume decreases on the opposite side; this results in the bending of the strip. Conversely, the film deflection generates an electric potential difference between the electrodes. We model this system and establish its constitutive relations using the thermodynamics of irreversible processes; we obtain a Kelvin–Voigt stress–strain relation and generalized Fourier’s and Darcy’s laws. We validate our model in the static case: we apply the latter to a cantilever blade subject to a continuous potential electric difference at the constant temperature. We draw the profiles of the different quantities and evaluate the tip displacement and the blocking force. Our results agree with the experimental data published in the literature.

Visualization of Tetrahedral Li in the Alkali Layers of Li-Rich Layered Metal Oxides.

Understanding Li+ ion diffusion pathways in Li-rich layered transition metal (TM) oxides is crucial for understanding the sluggish kinetics in anionic O2- redox. Although Li diffusion within the alkali layers undergoes a low-barrier octahedral-tetrahedral-octahedral pathway, it is less clear how Li diffuses in and out of the TM layers, particularly given the complex structural rearrangements that take place during the oxidation of O2-. Here, we develop simultaneous electron ptychography and annular dark field imaging methods to unlock the Li migration pathways in Li1.2Ni0.13Mn0.54Co0.13O2 associated with structural changes in the charge-discharge cycle. At the end of TM oxidation and before the high-voltage O oxidation plateau, we show that the Li migrating out of the TM layers occupies the alkali-layer tetrahedral sites on opposite sides of the TM layers, forming Li-Li dumbbell configurations, consistent with the density functional theory calculations. Also occurring are the TM migration and phase transition from O3 to O1 stacking, leading to unstable tetrahedral Li and the absence of Li contrast in imaging. Upon further Li deintercalation to 4.8 V, most of the tetrahedral Li are removed. After discharging to 2 V, we did not identify the reformation of tetrahedral Li but observed permanently migrated TMs at the alkali-layer sites, disfavoring the Li occupying the tetrahedral sites for diffusion. Our findings suggest a landscape of Li diffusion pathways in Li-rich layered oxides and strategies for minimizing the disruption of Li diffusion.

Hemal sinus basal laminae contact sites: a possible route between gonadal lumen and myoepithelial cells in the gonad of the sea star Patiria pectinifera.

Sea stars are a group of marine invertebrates suitable for studying the hormonal regulation of reproduction and spawning. In spite of substantial progress in understanding how various substances such as 1-methyladenine act in their gonads, there are still many gaps concerning the fine details of their action. One such gap is how the gonadal wall contraction is induced. Recent literature data suggest that, upon 1-methyladenine stimulation, some cells within the gonadal lumen produce non-neuronal acetylcholine that, upon contact with the gonadal wall, induces contraction of myoepithelial cells. Our ultrastructural study of the gonads in the sea star Patiria pectinifera has shown, for the first time, that there are sites where the basal laminae bordering the hemal sinus directly contact one another and appear at this contact site as a single entity. These contact sites are often associated with hemidesmosome-like junctions that anchor male accessory cells or female follicle cells on one side of the site and myoepithelial cells on the opposite. We suggest that contraction-inducing substance is secreted from an accessory or follicle cell, passes through a basal lamina contact site, and on the opposite side of the contact site acts on a myoepithelial cell to induce its contraction.

Rural Landscapes as Cultural Heritage and Identity along a Romanian River

In contemporary narratives, rural landscapes and identities, as judged by the inhabitants’ sense of belonging, continue to be important points that need to be (re)considered when discussing places as instruments for local development. This paper pushes forward these debates and explores the construction of rural and regional identity in Romania with the help of a case study that focuses on perceptions of rural landscapes as cultural heritage in two rural communities situated on opposite sides of the river Mureș. Based on participant and ethnographic observation and making use of a survey and a qualitative analysis, this paper highlights the most significant features of the local cultural identities and their rural landscape heritage expressed by the two sets of people, which often coincide with the most important characteristics attributed to the regions separated by the river Mureș. The results of this study underline the dividing role of the river in the preservation of rural identity and cultural heritage. They also demonstrate that rural landscapes and the construction of identities along the river have generated both development opportunities and various risks.

Scalp Reconstruction With Free Tissue Transfer Using Descending Branch of Lateral Circumflex Femoral Vessels as Interposition Graft.

Despite the rich blood supply to the scalp, postoperative skin necrosis at the surgical site sometimes occurs, and unresolved defects often present a significant challenge for the surgeon. When planning a free flap for scalp reconstruction, distant anastomoses may be necessary if local recipient vessels are unavailable due to previous surgery. This study presents the authors' treatment strategy, which includes extending the pedicle length with arteriovenous bundle interposition grafts. Two patients who experienced surgical wound necrosis after bypass surgery for moyamoya disease underwent reconstruction for skin and soft tissue coverage. To evaluate the altered anatomical structures after the previous surgery, three-dimensional computed tomography angiography was performed, and preoperative photos were taken to accurately measure the expected defect. The surgical strategy was designed to accommodate their unique conditions, utilizing an arteriovenous interposition graft, which included 2 stages of microvascular anastomoses, for pedicle lengthening. The procedure successfully bridged the gap between distant recipient vessels and the extensive defect, and the wounds healed without major complications such as venous congestion or total flap loss. Both patients were satisfied with the surgical outcomes. Arteriovenous bundle interposition grafts can be a useful option for patients with complex scalp defects who lack local recipient vessels. The use of an anterolateral thigh flap with artery-to-artery anastomosis, utilizing the lateral circumflex femoral artery from the opposite side in this study, offers many advantages compared with traditional pedicle lengthening tools utilizing vein-to-artery anastomosis.