Symmetric Wall Research Articles

Manipulation of edge states in non-Hermitian acoustic Su Schrieffer Heeger chains

A distinctive feature of topology is its unique ability to obtain and control robust interface states. Among other elements, it has been shown that non-Hermiticity alone can trigger topological phase transition in physical systems. In this work, we construct acoustic Su Schrieffer Heeger(SSH) chains using different unit cells where only the non Hermitian components differ due to different distributions of onsite losses. Our study focus on exploring the emergence of edge states at the interfaces between two chains composed of different unit cells. Our findings delineate three distinct types of edge modes. The topological, cavity and Parity-Time edge modes originate from the topological phase of the unit cells, the local parity symmetry at the interface and the existence of a Parity Time symmetric domain wall, respectively. We then compare the robustness of these different edge modes against disorder, confirming the robustness of the topological edge modes. Parity Time edge states demonstrate superior robustness compared to classical cavity modes for low level of disorder. However, beyond a certain threshold, their eigenfrequencies importantly diverge.

Modulating solute transport in magnetohydrodynamic pulsatile electroosmotic micro-channel flow: Role of symmetric and asymmetric wall zeta potentials

Modulating solute transport in magnetohydrodynamic pulsatile electroosmotic micro-channel flow: Role of symmetric and asymmetric wall zeta potentials

Double-bar technique for the correction of asymmetric pectus excavatum.

Minimally invasive repair of pectus excavatum (MIRPE) improves clinical outcomes and chest wall morphology. However, asymmetry in patients with pectus excavatum (PE) remains as an important issue, even after surgery. Here, we evaluated the benefit of double-bar technique in achieving a symmetric chest wall. This retrospective study included 79 patients with PE who underwent MIRPE between 2017 and 2021. The patients were divided into the double- or non-double-bar groups. Asymmetric degree (AD) and sternal rotation angle (SRA) were used to assess the severity of asymmetry based on computed tomography (CT) images. The primary outcome was the change in radiologic parameters. Secondary outcomes were clinical results, including hospital stay, pain scores, and complication rates. Subgroup analysis of patients with preoperative asymmetric PE was performed. Patients in the double-bar group (n=23) were younger than those in the non-double-bar group (n=56). Additionally, the double-bar group exhibited lower pain scores and shorter hospital stay. Based on radiological assessments, the double-bar group demonstrated a greater decrease in AD without compromising improvement in the Haller index (HI). The benefit of the double-bar technique was more obvious among patients with asymmetry with a preoperative AD >5%, resulting in a significant reduction in AD. In this subgroup, a better correction of sternal rotation was observed. The double-bar technique may be a promising option for correcting asymmetry in patients with PE. Simplified AD and SRA radiologic assessments can be used to evaluate improvements in chest wall configuration.

Endoscopic Retrograde Cholangiopancreatography-Related Procedures for the Differential Diagnosis of Isolated Immunoglobin G4-Related Sclerosing Cholangitis and Perihilar Cholangiocarcinoma.

Differential diagnosis of isolated immunoglobin (Ig)G4-related sclerosing cholangitis (IgG4-SC) and cholangiocarcinoma is challenging. We aimed to clarify the role of endoscopic retrograde cholangiography (ERCP)-related procedures in the differential diagnosis of isolated IgG4-SC and perihilar cholangiocarcinoma (PHCC). Seven patients with hilar-type isolated IgG4-SC diagnosed at Hiroshima University Hospital and sixty-five patients with surgically resected invasive PHCC were enrolled, and the diagnostic yields of intraductal ultrasonography (IDUS), peroral cholangioscopy (POCS), and pathological examinations were determined. In six of seven (86%) patients with isolated IgG4-SC, the stricture was in the perihilar bile duct. IDUS showed that symmetrical wall thickening (40% vs. 5%, p = 0.04), homogeneous internal echo (80% vs. 5%, p < 0.001), and smooth outer margins (80% vs. 6%, p < 0.001) were more frequent in isolated IgG4-SC than in PHCC. POCS showed a smooth mucosal surface more frequent in isolated IgG4-SC (75% vs. 7%, p = 0.006). Only one patient had two pathological findings characteristic of IgG4-SC. The sensitivity for diagnosing PHCC was 81% using two or more combined sampling methods. Pathological examinations have limitations in the differential diagnosis of isolated-IgG4-SC and PHCC, and a diagnostic strategy that combines multiple ERCP-related procedures, including IDUS and POCS, is recommended.

The Scar-Hidden Surgery on Gynecomastia: Experiences from a Single-Institutional Large Case Series.

To summarize the experiences on the mastoscopic subcutaneous mastectomy for gynecomastia by "nine-step method" based on the "5S" goal and standardize this operation. Between January 1, 2002, and October 31, 2021, a total of 2035 breasts of 1082 male patients with gynecomastia, of which 129 patients with one side, were underwent mastoscopic subcutaneous mastectomy. The follow-up endpoint was 3months after surgery. All patients were successfully completed the operation, and none of them was transferred to open operation. The operation time for unilateral breast was 12-28min, and the average time was 17.7 ± 6.2min. The amount of bleeding during unilateral operation was very small, about 5-10ml. The total drainage volume was 5-50ml after the operation, and the drainage tube was removed in 3-5days. The epidermal necrosis occurred in 0.3% nipple. 0.2% chest wall had a little ecchymosis in the supero-medial region of the breast. All patients had the normal feeling of nipples and areola, the smoothing and symmetrical chest wall, and the natural contour. There was no recurrence during the follow-up period. The mastoscopic subcutaneous mastectomy for gynecomastia by "nine-step method" based on the "5S" goal has a short operation time, few surgical complications and good esthetics. It achieves the "5S" goals on the complete removal of glandular tissue (sweeping), small and scar-hidden incision are small (scarless), good symmetry of bilateral chest wall (symmetry), normal chest shape (shape), and smoothing chest wall (smoothing). The journal asks authors to assign a level of evidence to each article. For a complete description of Evidence-Based Medicine ratings, see the Table of Contents or the online Instructions for Authors at www.springer.com/00266 .

Integration of Acoustic Metamaterials Made of Plastic to Improve Building Acoustics

According to the Waste Management Policy of the European Union, the recycling and reuse of various wastes is considered the most environmentally friendly and advanced waste disposal technology that has the least impact on the environment. By applying the principles of the Circular Economy, plastic waste will extend its life cycle and will be used as secondary materials to create metamaterial structures with improved sound absorption and insulation properties. Acoustic metamaterial resonators, created from plastic, were measured in an impedance tube according to standards ISO 10534-2 for their sound absorbing and ASTM E2611 for their insulating properties. Two types of plastic, PLA and recycled PET-G, were used in acoustic metamaterial 3D printing process. Sound absorption of both PLA and PET-G metamaterials were peaking at 1600 Hz with 0,93 and 0,89 sound absorption coefficient, respectfully. For sound insulation, combined resonator systems were used to control symmetrical wall sound resonance. The aim of this study was to determine plastic potential for use in acoustic structures. The results showed that combined constructions with plastic metamaterials can be integrated into building structures and used as an alternative for improving building acoustics, reducing indoor noise and reverberation time.

Curvature conservation and conduction modulation for symmetric charged ferroelectric domain walls

Curvature conservation is a common feature for the physical properties with topological constraints, from the macroscopic cosmic string loops to the microscopic quantized vortex rings in the superfluid. Interestingly, ferroelectric domain-wall curvature is important to determine its conduction, which is the key parameter for designing domain-wall nanoelectronic devices. Here, we demonstrate the curvature conservation of the charged domain walls confined in ferroelectric topological structures with specific domain symmetry by combining piezoelectric force microscopy, conducting atomic force microscopy, and phase-field simulations. Significantly, the intrinsic conductivity of the charged domain walls exhibits an inverse functional relationship with the local domain-wall curvature in the ferroelectric BiFeO3 nano-islands, which can also be precisely and continuously modulated by applying an electric field. This work provides us with an insightful understanding of the conduction mechanism of charged domain walls confined in ferroelectric topological structures with a high degree of spatial symmetry, which paves the way for the application of charged domain walls as flexible conducting channels with continuously changing resistance states to be used for ferroelectric domain-wall memristors.

Impurity-doped stable domain walls in spherically symmetric spacetimes

In this work, radially symmetric domain wall solutions in the presence of impurities are investigated for both flat and curved D+1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D+1$$\\end{document} spacetimes, with geometry generated by a rotationally invariant background metric. We have examined the constraints placed upon the model by Derrick’s theorem, and found out the Bogomol’nyi bound and equations of the symmetric restriction to this theory. Impurity-doped versions of a ϕ4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi ^4$$\\end{document} model in two dimensions and a model with logarithmic potential in a Schwarzschild background have been explicitly worked out. The resulting configurations have been compared with those found in the homogeneous version of the theory, so that the effect of impurities in the form of solutions may be better appreciated. We have also generalized to higher dimensions some of the results that had been presented in the recent literature. These results relate to the possibility of BPS-preserving impurities, which we have found to still exist in the spacetimes considered in this work. We also investigate ways in which these results may be extended in a curved background.

Edge states in non-Hermitian composite acoustic Su Schrieffer Heeger chains

Non-Hermiticity alone can trigger topological phase transition in physical systems. Here, we construct different unit cells in an acoustic Su Schrieffer Heeger chain with different distributions of onsite losses. We theoretically and numerically investigate the different edge modes that can occur at the domain walls of different finite chains. Three types of edge modes are identified. The first type comes from the topology of the unit cells. The second type comes from the local Parity symmetry at the interface, which are cavity modes. The third one comes from the Parity-Time symmetric domain wall. The robustness against coupling disorder is then examined, confirming the robustness of the topologically protected modes. The evolution with increasing disorder of the interface modes due to the Parity-Time symmetric domain wall is singular as they appear first as more robust than the cavity modes before diverging. These results show the ability of the onsite losses ingredient to control wavefields.

Integration of Acoustic Metamaterials Made of Plastic to Improve Building Acoustics

Abstract According to the Waste Management Policy of the European Union, the recycling and reuse of various wastes is considered the most environmentally friendly and advanced waste disposal technology that has the least impact on the environment. By applying the principles of the Circular Economy, plastic waste will extend its life cycle and will be used as secondary materials to create metamaterial structures with improved sound absorption and insulation properties. The aim of this study was to determine plastic potential for use in acoustic structures. Acoustic metamaterial resonators, created from plastic, were measured in an impedance tube according to standards ISO 10534-2 for their sound absorbing and ASTM E2611 for their insulating properties. Two types of plastic, PLA and recycled PET-G, were used in acoustic metamaterial 3D printing process. For sound insulation, combined resonator systems were used to control symmetrical wall sound resonance. Sound absorption of both PLA and PET-G metamaterials were peaking at 1600 Hz with 0.93 and 0.89 sound absorption coefficient, respectfully. The results showed that combined constructions with plastic metamaterials can be integrated into building structures and used as an alternative for improving building acoustics, reducing indoor noise and reverberation time.

Buckling of a movable constrained laminated beam with variable-length in hygrothermal environment

The buckling response of a variable-length laminated beam constrained by a pair of symmetrical walls in hygrothermal environment is studied in the paper. The constrained wall is rigid but supported by springs that move upwards as a whole after being subjected to a force. The nonlinearly constrained buckling governing equation of the variable-length laminated beam in hygrothermal environment is established based on the principle of minimum potential energy and the Lagrange multiplier method. The buckling responses of the variable-length laminated beam are derived based on the elliptic integral method. Extensive numerical calculations are performed to illustrate the effects of different constraint clearances, spring stiffness, geometry, temperature, humidity, and composite fiber ply angle on the critical buckling load, buckling response, and buckling path.

Effect of wall temperature in streamwise supersonic corner flow

The interaction between corner flow and heat transfer is very common in the internal and external flow of hypersonic vehicle surface, but it is not clear how the wall thermal boundary condition affects the supersonic corner flow boundary layer. In the present study, the Reynolds stress model is used to solve the Reynolds-averaged Navier–Stokes equations. The results show that when the symmetrical wall temperature Tw is less than or equal to the recovery temperature Taw, the mean velocity profile in the corner zone is similar to the plate zone, and the temperature is higher in the corner zone. At heating wall condition of Tw&amp;gt;Taw, both velocity and temperature profile of outer corner boundary layer are different from that in the plate zone. The near-wall temperature distribution increases relatively, and the temperature profile is no longer similar to the law of the wall when Tw rises. Along the spanwise wall, the deviation of the velocity–temperature quadratic curve and the generalized Reynolds analogy (GRA) relation is within 10%. In the supersonic corner flow, the velocity–temperature relation under non-adiabatic wall condition satisfies the GRA relation. The effect of wall temperature on corner boundary layer velocity and temperature is significant. It is necessary to consider wall thermal boundary condition in the supersonic corner flow boundary layer analysis.

Sonographic “Cervix Sign”: A New Ancillary Sign of Gallbladder Neck Malignancy

The differentiation of benign and malignant gallbladder wall thickening is challenging. The purpose of this study is to evaluate a new sonographic sign, "cervix sign" for differentiation of benign and malignant gallbladder neck thickening. This retrospective study comprised consecutive patients with gallbladder neck thickening who underwent sonography between August 2019 and December 2021. The presence of "cervix sign" was assessed by two radiologists independently. Sixty-five patients had gallbladder neck thickening (28 malignant and 37 benign). The sonographic "cervix sign" was present in 18 (64%) patients with malignant thickening and in only one (2.7%) patient with benign thickening (P= 0.0001). The mean wall thickness was greater, and symmetric wall thickening and liver metastases were more common in malignant thickening with "cervix sign" (without reaching statistical significance). There was substantial agreement (kappa=0.78) between the two observers for the cervix sign. Sonographic "cervix sign" is a useful ancillary feature of gallbladder neck cancer.

V-028 HYBRID (LAPAROSCOPIC AND OPEN) REPAIR WITH REVERSE TAR TO TREAT A LATERAL INCISIONAL HERNIA WITH DENERVATION OF THE RIGHT ABDOMINAL MUSCLES

Abstract Aim Lateral incisional hernias with denervation of the muscles of the abdominal wall are a problem difficult to solve. The repair of the defect does not guarantee a functionality of the abdominal muscles if the lack of force of the abdominal wall is not solved. With the technique we present there is a minimally invasive reinforcement of the mid lateral wall affected. Material and Method 54 yo female. Previous surgeries: biliary cystadenoma 2014 by Makuuchi laparotomy (2 surgeries), Ooforectomy 2011, Hysterectomy 2013, Mamoplasty 2001, 3 vertebral surgeries. Six months after the surgery she felt a growing lump in the right side of the incision. Physical exam: right lateral incisional hernia and small umbilical hernia. Asymmetry of the abdominal wall because of flaccidity of the right abdominal muscles. Ultrasound Voluminous incisional hernia in the right flank dependent of the right transverse sub-costal incision with a hernia ring of 20mm and hernia sac 60mm of diameter increasing with Vasalva maneuvers. Surgical technique Hybrid approach laparoscopic and lateral by e-TEP to dissect the retrorectal bilateral space and lateral preperitoneal approach with reverse TAR. A macroporous polipropilene preperitoneal mesh is placed from the right psoas to left semilunar line and from top to bottom of the abdominal wall. Result Discharged 2nd po. day without complications. 5 months after surgery she has a symmetric abdominal wall without recurrence. Conclusion Hybrid technique to repair lateral hernias with denervation allows a wide repair with low morbidity and good tolerance with excellent result in abdominal functionality.

Role of computed tomographic enterography for evaluation of small bowel diseases: A cross-sectional study

Background: Computed tomographic enterography (CTE) is a newer non-invasive modality having distinct advantages over conventional CT and capsule endoscopy. Objectives: This technique allows faster evaluation of small bowel diseases in the endoscopically inaccessible segments. Being an operator-independent procedure, CTE is widely available and allows a better depiction of extra enteric complications. The aim is to evaluate CTE features of various small bowel diseases and the role of 2% mannitol for adequate small bowel distension. Materials and methods: A cross-sectional study comprising 105 patients had presented with small bowel diseases. Patients in the age group of 10 to 85 years with complaints of fever, abdominal pain, nausea, vomiting, altered bowel habits, loss of appetite and loss of weight were included in this study. CTE images were analyzed to compare the diagnosis with the available histopathological and ultrasonography results. Results: Among the study population, the majority had presented CTE features such as symmetrical wall thickening (53.3%), peri-bowel inflammatory changes (61%), mucosal hyperenhancement (39%), and mural stratification, i.e., target sign (33.3%). The majority of diagnoses of CTE were ileocecal tuberculosis (11.5%), small bowel inflammation (7.6%), and Crohn’s disease (6.7%). Other conditions such as small bowel neoplastic masses, diverticula, ischemic bowel disease, bowel strictures, intussusception, and ulcerative colitis. Conclusion: CTE has the vital role of first-line modality in the work-up of suspected small intestinal diseases and helps evaluate disease activity before endoscopy, particularly in inaccessible segments. It allows a better depiction of extra enteric complications of the bowel.

Role of Multidetector Computed Tomography in the Assessment of Malignant Large-Bowel Lesions

Abstract Background and Objective: Intestinal disease can be examined with computed tomography (CT), which also allows for an assessment of extraintestinal pathology. In addition, CT enhances diagnostic specificity (SP) and offers an exceptional evaluation of the perienteric anomalies that typically accompany bowel disorders. The preoperative grading accuracy was found unappealing, varying between 48% and 77%. The bowel wall thickening among individuals with colorectal cancer is classified as benign or malignant depending on the extent of thickening, symmetrical and asymmetrical thickening, focal, segmental, or diffuse involvement, and related perienteric anomalies. The current study used a cohort of patients with colorectal cancers. The study aimed to find out sensitivity (SN) and SP of multidetector CT (MDCT) in detecting malignant pathologies of the large bowel by comparing the MDCT diagnosis with findings of histopathological examination. Materials and Methods: The study was an observational study, done from December 2019 to December 2021 in the Department of Radiodiagnosis, MES Medical College, Perinthalmanna, Kerala. The patients included were clinically and radiologically indicative of bowel lesions, who were referred with clinical suspicion of large-bowel diseases. The 16-slice Philips ACCESS MDCT scanner was used for MDCT. Oral, rectal, and IV contrast were used after plain CT imaging. Results: The study consisted of 63 patients, of which 53 lesions were found to be malignant on MDCT. However, only 51 patients had cancer verified by histology. Histopathology indicated that the two instances, which the MDCT had identified as malignant, were actually inflammatory. Therefore, for the diagnosis of malignant tumors, MDCT had a SN of 98.10%, SP of 81.80%, a positive predictive value of 96.20%, and a negative predictive value of 90.00% in the present study. On histology, a case that was first identified as benign on MDCT turned out to be malignant. Benign abnormalities on CT showed broad intestinal involvement and modest, symmetric wall thickening. The CT characteristics of malignant tumors included localized intestinal involvement and pronounced asymmetric wall thickening. Conclusion: MDCT has shown to be a trustworthy method for the purpose of evaluating and discriminating benign from malignant colon and rectum tumors. In addition to merely identifying a tumor, MDCT also offers additional information on any perienteric anomalies that may be present around the lesion, the presence of lymph node enlargement, invasion of adjacent viscera, the existence of intestinal obstruction, and metastatic tumors.

Non-Hermitian total-loss high-order topological insulator based on 1D Su–Schrieffer–Heeger (SSH)

Non-Hermiticity alters topology with the presence of non-Hermitian factors in topological systems. Most existing non-Hermitian topological systems derive their topological phases from Hermitian components, that is, the gain and loss of the system are considered simultaneously. In this work, we reveal two-dimensional non-Hermitian high-order topological insulator based on one-dimensional SSH chain, the nontrivial topology of which induced by total-loss. By introducing the loss of a specific configuration, we get a bandgap with corner and edge states whose topology is characterized by the gapped wannier band. In addition, we demonstrate the existence of ’real-energy’ edge states in pseudo-PT symmetric domain wall system. These results can be easily implemented in experiments, and promote the research of topological transmission of lossy systems in the real world.

Effects of neoclassical tearing modes and toroidal field ripple on lost alpha power in the SPARC tokamak

Using the SPIRAL Monte Carlo, full particle-orbit simulation code, we investigate the effects of neoclassical tearing modes (NTMs) and toroidal field (TF) ripple on alpha power losses during steady-state operation of the SPARC primary reference discharge. Model perturbations for TF ripple and the and NTMs with exaggerated widths selected based on an H-mode plasma approaching thermal quench are added to a simulated SPARC magnetic equilibrium through which marker particles are tracked. The 3/2 and 2/1 NTMs are located at and respectively, well positioned to increase alpha particle transport into and within an outer lossy region of the plasma beyond where over 95% of lost alpha particles are born. Total alpha power losses are shown to increase modestly from 1.73% lost at a minimum to 2.34% lost at a maximum, and alpha particle surface power densities form localized hotspots on the first-wall near the low-field side midplane due to NTMs and TF ripple. We establish a conservative upper limit for first-wall alpha surface power densities on a toroidally symmetric wall for typical, flattop operation and motivate the consideration of NTMs in the design of three dimensional limiter surfaces for SPARC.

Numerical Approach on Oblique Wave Scattering by a Wide Rectangular Impediment With a Vent Placed Under a Finite Depth Water Body With Ice-Covered Surface

Abstract In this paper, we investigate the scattering of obliquely incident surface water waves on a hurdle as a form of a thick symmetric wall with a gap immersed in a finite depth water body having a cover of a thin ice sheet. In the context of the linear theory of water waves, this two-dimensional problem is formulated as a first-kind integral equation by splitting the velocity potential into symmetric and antisymmetric parts. The integral equation is tackled by using two numerical methods. The first method is the boundary element method where the range of integration is divided into a finite number of small line elements, and choosing the unknown function of the integral equation as constant in each line interval, we reduce the integral equation into a linear system of an algebraic equation. The second method is the multi-term Galerkin Approximation method where the basis functions are chosen as ultraspherical Gegenbauer polynomials to reduce the integral equation to a system of an algebraic equation. These systems of equations are then solved to obtain the unknown function of the integral equation in both methods. Here, very accurate numerical estimates are obtained for the reflection coefficient by both methods which are depicted graphically against the wave number for different parameters involving this problem. Also, there is a good agreement between the results of the reflection coefficient by the two methods.

Experimental and numerical analysis of a hybrid WEC-breakwater system combining an oscillating water column and an oscillating buoy

Integrating multi-type Wave Energy Converters (WECs) enables wave energy to be extracted from multiple harvesting manners simultaneously, which presents a more competitive energy conversion technology. In this study, an Oscillating Water Column (OWC) and an Oscillating Buoy (OB) are combined to devise a hybrid WEC system that serves as a floating breakwater. The two devices are aligned in line with the incident wave direction, where the OB is deployed upstream from the OWC. A series of physical experiments are conducted to understand the working principle of the hybrid WEC system. After a fully non-linear time-domain model is validated by the measured data, the comparisons of the hybrid system and its respective isolated devicesare emphasised. Then, the hydrodynamic dependence of the hybrid system is comprehensively tested. The results indicated that the hybrid system design provides higher energy conversion as well as better wave attenuation performance compared to the isolated OWC and OB devices. Additionally, the OB outperforms the OWC in terms of wave energy conversion. The OWC-OB gap resonance has a negative impact on wave energy extraction but has a negligible effect on wave attenuation. The OWC with a deeper draft and symmetric wall performs better both in terms of wave energy extraction and wave attenuation in long-period waves. The overall conversion efficiency decreases with the increase of the OB draft, but the transmission coefficient follows an opposite trend. The PTO dampings of the OB and the OWC dominate the overall conversion efficiency and the transmission coefficient, respectively.