Complete Ring Research Articles

Clinical features of midzonal iris pigment epithelial cysts: surprising findings revealed by ultrasound biomicroscopy.

Midzonal iris pigment epithelial (IPE) cysts are typically asymptomatic but can pose a differential diagnostic challenge by mimicking ciliary body melanoma. We conducted a case series study of the clinical characteristics of these iris cysts, particularly their shapes and sizes and associated lesions revealed by ultrasound biomicroscopy (UBM). Charts of patients with midzonal IPE cysts encountered by one or more of the authors were reviewed retrospectively. Pertinent demographic information and clinical data about these patients and their cysts were abstracted. 69 patients were identified. At initial diagnosis, patients ranged in age from 14.8 to 89.5years (median: 66.0years). Only one patient was < 30years old at diagnosis. 38 patients (55.1%) were female. 74 eyes (39 right, 35 left) contained one or more clinically identified midzonal IPE cysts. The cysts involved the right eye alone in 34 (49.3%), the left eye alone in 30 (43.5%), and both eyes in 5 (7.2%) patients. The midzonal IPE cysts were located most often inferotemporally (51.4%) and second most often temporally (23.0%). UBM imaging had been performed on 44 of the 74 affected eyes. The median largest basal diameter of the midzonal IPE cysts evaluated by UBM was 4.5mm (extremes: 1.5 to 13mm), and the median height of these cysts was 1.5mm (extremes: 0.6 to 6mm). The largest lesion was a complete ring cyst. All 3 UBM-evaluated eyes that appeared by slit lamp biomicroscopy to have two or more distinct midzonal IPE cysts were shown by UBM to have a single sausage or kidney-bean shaped partial ring cyst with radial folds between the lobules and not separate multiple cysts. UBM imaging also identified peripheral IPE cysts in 32 of 44 evaluated eyes (72.7%). Our case series confirmed previously reported findings regarding age at diagnosis and most common locations of midzonal IPE cysts. However, our UBM images revealed that at least some IPE cysts identified by slit lamp biomicroscopy as multifocal are partial ring cysts with radial folds in the cyst wall between lobules and not true independent multiple cysts. What is known Midzonal IPE cysts occur most often unilaterally and inferotemporally. Midzonal IPE cysts are frequently associated with peripheral IPE cysts. What is new UBM imaging of eyes with two-clinically detected IPE cysts showed that they were confluent as opposed to separate cysts. The median largest basal diameter of midzonal IPE cysts evaluated by UBM was 4.5 mm (extremes: 1.5 and 13 mm). The median height of midzonal IPE cysts evaluated by UBM was 1.5 mm (extremes: 0.6 and 6 mm).

Congenital Tracheal Stenosis: Two Case Reports and Literature Review

Background: Congenital tracheal stenosis is defined as the narrowing of the airway lumen due to the abnormal formation of complete tracheal cartilage rings. It may present with different clinical pictures, depending on the range and extent of stenosis. We present two cases of congenital tracheal stenosis, with a different range of severity and, consequently, different treatment approaches. Case Presentation: We describe the case of a 3-month-old infant with breathing noise that worsened particularly when crying and after nutrition. He presented a congenital funnel-shaped tracheal stenosis with an associated tracheal bronchus, which was treated endoscopically with an endobronchial stent. The second presented case is of a newborn who presented severe respiratory distress and inspiratory stridor in the first hours of life. A congenital cylindrical tracheal stenosis was diagnosed and it was treated surgically through slide tracheoplasty. Discussion: These two cases showed us that congenital tracheal stenosis can present with a very variable clinical picture. Thus, according to clinical presentation, different treatments can be considered. Conclusion: We underline the importance of considering congenital tracheal stenosis in the differential diagnosis of prolonged wheezing and recurrent airway infections.

Krull–Gabriel dimension of Cohen–Macaulay modules over hypersurfaces of countable Cohen-Macaulay representation type

We calculate the Krull–Gabriel dimension of the functor category of the (stable) category of maximal Cohen–Macaulay modules over complete Cohen-Macaulay local rings of countable Cohen-Macaulay representation type. We show that the Krull–Gabriel dimension is 0 if and only if the ring is of finite Cohen–Macaulay representation type and that is 2 if the ring is a hypersurface of countable but not finite Cohen–Macaulay representation type.

Lifting elementary Abelian covers of curves

Given a Galois cover of curves f over a field of characteristic p, the lifting problem asks whether there exists a Galois cover over a complete mixed characteristic discrete valuation ring whose reduction is f. In this paper, we consider the case where the Galois groups are elementary abelian p-groups. We prove a combinatorial criterion for lifting an elementary abelian p-cover, dependent on the branch loci of lifts of its p-cyclic subcovers. We also study how branch points of a lift coalesce on the special fiber. Finally, for p=2, we analyze lifts for several families of (Z/2)3-covers of various conductor types, both with equidistant branch locus geometry and non-equidistant branch locus geometry.

On local divisor class groups of complete intersections

Samuel conjectured in 1961 that a (Noetherian) local complete intersection ring that is a UFD in codimension at most three is itself a UFD. It is said that Grothendieck invented local cohomology to prove this fact. Following the philosophy that a UFD is nothing else than a Krull domain (that is, a normal domain, in the Noetherian case) with trivial divisor class group, we take a closer look at the Samuel–Grothendieck Theorem and prove the following generalization: Let A be a local Cohen–Macaulay ring.(1)A is a normal domain if and only if A is a normal domain in codimension at most 1.(2)Suppose that A is a normal domain and a complete intersection. Then the divisor class group of A is a subgroup of the projective limit of the divisor class groups of the localizations Ap, where p runs through all prime ideals of height at most 3 in A. We use this fact to describe for an integral Noetherian locally complete intersection scheme X the gap between the groups of Weil and Cartier divisors, generalizing in this case the classical result that these two concepts coincide if X is locally a UFD.

On the coherency of completed group algebras

We investigate coherency properties of certain completed integral group rings.

Durability of annuloplasty in patients with atrial functional mitral regurgitation associated with atrial fibrillation

ObjectiveTo determine the durability of mitral valve repair (MVr) with complete ring or flexible band annuloplasty in patients with atrial functional mitral regurgitation (AFMR) due to atrial fibrillation (AF) and identify risk factors associated with postoperative recurrence of mitral regurgitation. MethodsBetween January 1, 2000, and January 1, 2023, 194 adults with a history of AF underwent MVr with annuloplasty alone for moderate/severe AFMR. Exclusion criteria were prior cardiac surgery, additional repair techniques, ejection fraction <45%, ischemic heart disease, aortic valve disease, mitral annular calcification, and concomitant procedures other than surgical ablation or tricuspid repair/replacement. The durability of annuloplasty was assessed using longitudinal analysis of postoperative echocardiographic data. ResultsComplete ring annuloplasty was performed in 126 of 194 patients (65%); partial ring (posterior band) in the other 68 (35%). Concomitantly, 124 of the 194 patients underwent tricuspid valve surgery, and 173 (89%) had a procedure for AF, including biatrial Cox-Maze III/IV lesion set in 152 (88%) and pulmonary vein isolation in 21 (12%). All patients were discharged with no/trace MR. Freedom from moderate/severe MR after repair with annuloplasty alone was 89% at 10 years, and no significant differences were noted between complete and partial ring annuloplasty (early, P = .41; late, P = .92). Forty-eight percent of patients developed AF at 3 months or longer after surgery, and the presence of postoperative AF was not associated with a greater likelihood of recurrence of MR (P = .15). Freedom from mitral reintervention was 96% at 10 years. ConclusionsIn appropriate patients with AFMR, the long-term durability of annuloplasty is excellent with complete ring and posterior band annuloplasty techniques.

Successful case report of congenital long-segment complex tracheal stenosis treated with sliding tracheoplasty associated with pulmonary artery vascular ring

BackgroundCongenital tracheal stenosis is a rare structural obstructive disorder affecting a segment of the trachea. It is often caused by complete or nearly complete cartilaginous rings narrowing the airway. Approximately 50% of cases are associated with abnormal left pulmonary artery rings.Case presentationWe present the case of a 4-month-old female infant with complex congenital tracheal stenosis associated with a left pulmonary artery vascular ring and congenital heart disease. The patient underwent successful surgical intervention involving repair of the congenital heart defect and reimplantation of the pulmonary artery, followed by sliding tracheoplasty in one surgery procedure. Postoperative outcomes were favorable, with successful extubating and resolution of respiratory symptoms.ConclusionsSliding tracheoplasty proved an effective treatment option in this complex case, highlighting its reproducibility and favorable outcomes in managing congenital tracheal stenosis.

The Mechanosensitive Pkd2 Channel Modulates the Recruitment of Myosin II and Actin to the Cytokinetic Contractile Ring.

Cytokinesis, the last step in cell division, separates daughter cells through mechanical force. This is often through the force produced by an actomyosin contractile ring. In fission yeast cells, the ring helps recruit a mechanosensitive ion channel, Pkd2, to the cleavage furrow, whose activation by membrane tension promotes calcium influx and daughter cell separation. However, it is unclear how the activities of Pkd2 may affect the actomyosin ring. Here, through both microscopic and genetic analyses of a hypomorphic pkd2 mutant, we examined the potential role of this essential gene in assembling the contractile ring. The pkd2-81KD mutation significantly increased the counts of the type II myosin heavy chain Myo2 (+18%), its regulatory light chain Rlc1 (+37%) and actin (+100%) molecules in the ring, compared to the wild type. Consistent with a regulatory role of Pkd2 in the ring assembly, we identified a strong negative genetic interaction between pkd2-81KD and the temperature-sensitive mutant myo2-E1. The pkd2-81KD myo2-E1 cells often failed to assemble a complete contractile ring. We conclude that Pkd2 modulates the recruitment of type II myosin and actin to the contractile ring, suggesting a novel calcium-dependent mechanism regulating the actin cytoskeletal structures during cytokinesis.

Morphological Comparison of Larynx, Syrinx and Trachea of Some Wild Birds

The presence of both the larynx and syrinx in the respiratory system, the trachea consisting of long and complete cartilage rings, and the presence of air sacs are some of the important features that distinguish birds from mammals. There have been many studies on the larynx, trachea and syrinx as they are the distinguishing features of song and bird vocalizations in many avian species. In the present study, the purpose was to demonstrate the morphological structures of the larynx, trachea and syrinx, which is a sound organ, pigeon, sparrowhawk, falcon, eagle, goose, crow and stork. A total of 48 specimens, were used in the study. The materials were stained with methylene blue for better observation and counting of the tracheal rings. The staining procedure was performed by soaking the materials in alcohol, methylene blue solution and alcohol solutions of different concentrations, respectively. It was observed that the tracheal cartilages were a complete ring in all study species, but there were differences in tracheal length, number of cartilages and dorsoventral flattening. Syrinx was found to be tracheal type in storks and tracheobronchial type in others. As a result, the similarities and differences of the data obtained from pigeon, falcon, sparrowhawk, eagle, crow, goose and stork on larynx, trachea and syrinx due to different hunting, singing and vocal characteristics were revealed.

Descent of splendid Rickard equivalences in alternating groups

We show that any block of an alternating group with an abelian defect group over an arbitrary complete discrete valuation ring is splendidly Rickard equivalent to its Brauer correspondent. This provides new evidence for a refined version of Broué's abelian defect group conjecture proposed by Kessar and Linckelmann.

Multifunctional and Electronically Conjugated Triazine Framework for Superior Electro‐Ionic Artificial Muscles

AbstractElectro‐ionic artificial muscles, consisting of a configuration where an electrolyte membrane is flanked by two active electrodes, have emerged as transformative components in the field of soft robotics. Despite this, the current actuation performance falls short for many practical applications, because most existing electrode materials exhibit limitations in terms of their properties. Here, a multifunctional active electrode material is reported for an electro‐ionic artificial muscle, employing a triazine framework that incorporates 6,6′‐Dicyano‐2,2′‐bipyridyl (DCB‐TF). The multifunctional DCB‐TF boasts fully conjugated bonds, facilitating fast electron transfer, high porosity for ion accommodation, a substantial surface area of 1800 m2 g−1 for charge storage, numerous active sites for ion interactions, and complete aromatic rings contributing to stability. The application of DCB‐TF to the active electrodes in the electro‐ionic artificial muscles yields remarkable actuation performance, including a substantial bending displacement of 24 mm at 0.5 V and 0.2 Hz, a rapid response time of 2 s, and outstanding durability sustained over 3.4 million continuous cycles. Consequently, these soft actuators have enabled a dragonfly demonstration as a form of kinetic art.

Honeycomb gold specimen supports enabling orthogonal focussed ion beam-milling of elongated cells for cryo-ET

Cryo-focussed ion beam (FIB)-milling is a powerful technique that opens up thick, cellular specimens to high-resolution structural analysis by electron cryotomography (cryo-ET). FIB-milled lamellae can be produced from cells on grids, or cut from thicker, high-pressure frozen specimens. However, these approaches can put geometrical constraints on the specimen that may be unhelpful, particularly when imaging structures within the cell that have a very defined orientation. For example, plunge frozen rod-shaped bacteria orient parallel to the plane of the grid, yet the Z-ring, a filamentous structure of the tubulin-like protein FtsZ and the key organiser of bacterial division, runs around the circumference of the cell such that it is perpendicular to the imaging plane. It is therefore difficult or impractical to image many complete rings with current technologies. To circumvent this problem, we have fabricated monolithic gold specimen supports with a regular array of cylindrical wells in a honeycomb geometry, which trap bacteria in a vertical orientation. These supports, which we call “honeycomb gold discs”, replace standard EM grids and when combined with FIB-milling enable the production of lamellae containing cross-sections through cells. The resulting lamellae are more stable and resistant to breakage and charging than conventional lamellae. The design of the honeycomb discs can be modified according to need and so will also enable cryo-ET and cryo-EM imaging of other specimens in otherwise difficult to obtain orientations.

Anomalous circumflex artery encircling the aortic annulus: implications for mitral valve repair

Injury to coronary arteries during mitral surgery is a rare but life-threatening procedural complication, an anomalous origin and course of the left circumflex artery (LCx) increase this risk. Recognizing the anomaly by the characteristic angiographic pattern and identifying its relationship with the surrounding anatomical structure using imaging techniques, mainly transesophageal echocardiography (TOE) or coronary computed tomography angiography (CCTA), is of crucial importance in setting up the best surgical strategy. We report a case of anomalous origin of a circumflex artery (LCx) from the proximal portion of the right coronary artery (RCA) with a pathway running retroaortically through the mitro-aortic space. An integrated diagnostic approach using a multidisciplinary team with a cardiologist and an imaging radiologist allowed us to decide the surgical strategy. We successfully performed a mitral valvular repair using a minimally invasive minithoracotomic approach and implanting a complete semirigid ring.

Simultaneous Tricuspid Valve Repair at the Time of Mitral Valve Surgery: Determinants of Postoperative Pacemaker Implantation

Guidelines recommend tricuspid valve (TV) repair for patients with severe tricuspid valve regurgitation (TR) undergoing surgery for degenerative mitral valve (MV) disease, but management of ≤ moderate TR is controversial. This study examines the incidence and causes of bradyarrhythmias leading to PPM implantation. Review of patients undergoing simultaneous TV repair and MV surgery for degenerative MV disease from 2001 to 2022 (N=404). Primary endpoint was the incidence of postoperative PPM implantation. Secondary endpoints included the incidence of high-degree AV block and overall survival. All patients underwent TV repair at the time of MV surgery; 332 (82%) underwent MV repair and 72 (18%) MV replacement. Tricuspid valve repair techniques included flexible band (n=258, 63.8%), DeVega annuloplasty (n=78, 19.3%), complete flexible ring (n=49, 12.1%), and incomplete rigid ring (n=19, 4.7%). The 30-day mortality was 0.5% (n=2). A total of 35 (8.7%) patients had a PPM implanted postoperatively, 26 (6.4%) for high-degree AV block. On multivariable analysis, only older age was associated with PPM implantation. Patients who received a PPM due to high-degree AV block had reduced overall survival (Figure, p=0.01). Need for permanent pacing following TV repair at the time of MV surgery is not uncommon, but there are few modifiable factors that might reduce this risk. Careful selection of patients with less-than-severe TR and surgical techniques may reduce PPM-related risks and complications.

Choice of suture technique may mitigate figure-of-8 deformity in slide tracheoplasty

ObjectivesTo demonstrate varying degrees of immediate postoperative figure of 8 deformity following three different methods of tracheal suturing. Study designComparative ex-vivo study. MethodsA fresh, unfixed rabbit trachea was harvested and bisected at its midpoint. The posterior membranous trachea was excised from both segments to mimic the anatomy of complete tracheal rings following longitudinal release. A slide tracheoplasty was performed on the same tracheal segments as an internal control, using three different methods of closure: simple running, running horizontal mattress, and a modified baseball stitch. Endoscopic and external photographs were taken immediately following repair to document the effect of closure technique on external and endoluminal anatomy. ResultsA simple running closure, in which traveling occurs between needle passes, showed the greatest degree of postoperative figure of 8 deformity. A running horizontal mattress suture closure showed less deformity and a modified running closure, in which traveling occurs within needle passes, showed the least deformity. ConclusionsOur study suggests that a minor modification of standard running closure techniques may help limit the common figure-of-8 deformity often noted following slide tracheoplasty. Lay SummaryFigure of-8 deformity is a problem that can occur when repairing a narrow trachea referred to as tracheal stenosis. This deformity may be prevented using particular suture techniques which may decrease the likelihood that the trachea becomes blocked again following repair.

Completed prismatic F-crystals and crystalline Zp-local systems

We introduce the notion of completed $F$-crystals on the absolute prismatic site of a smooth $p$-adic formal scheme. We define a functor from the category of completed prismatic $F$-crystals to that of crystalline étale $\mathbf {Z}_p$-local systems on the generic fiber of the formal scheme and show that it gives an equivalence of categories. This generalizes the work of Bhatt and Scholze, which treats the case of a mixed characteristic complete discrete valuation ring with perfect residue field.

Critical interplay between ruthenium oxide and water for the catalytic conversion of lignin to sustainable aviation fuel

The production of renewable drop-in fuels from lignocellulosic biomass is desirable for achieving net-zero carbon emissions in the transportation sector. However, the high irregularity of lignin and its resistance to complete ring saturation and deoxygenation hinder its conversion to sustainable aviation fuels (SAFs) such as C7–C16 isoparaffins and alkylated cycloalkanes. In this study, we achieve the direct production of SAFs from lignin-derived oil over a nonacidic Ru/C catalyst in water. Hydrogen atoms generated by H2 dissociation combine with neighboring water molecules to produce hydronium ions, which are then transferred via H-shuttling to attack the double bonds and cyclic –OH groups of adsorbed reactants and intermediates. Density functional theory calculations suggest that hydrodeoxygenation in water decreases the activation energy for the direct hydrogenolysis of cyclic –OH groups over oxygen-vacant ruthenium oxide sites. The critical interplay between oxygen-vacant ruthenium oxide and water results in the almost-complete conversion of lignin-derived monomers, dimers, and bio-oils to desirable SAF components.

Effect of Metal Foam’s Volume on the Performance of a Double Pipe heat exchanger

The present numerical study aims to explore the effect of metal foam’s volume on the performance of a double-pipe heat exchanger in comparison with a smooth pipe (HXS). It used water as operating fluid at flow rate 2lpm, the outer stainless steel pipe has outer diameter (Do=60mm) and length (L=609.6mm), and inner copper pipe with outer diameter (do=20mm). The numerical simulation was conducted by ANSYS FLUENT 2020 R2 software and open-cell copper foam (CF) with porosity (0.9) was used. The cases considered in the analysis include a heat exchanger with a complete fill of copper foam (HXF), and a partial fill heat exchanger. The latter was made by inserting a complete rings of copper foam baffles (CFB) to decrease volume of a CF. Then, the baffles volumes was increased by increasing the thickness and their number. Three parameters were varied and their influence on performance evaluate criteria (PEC) were investigated. They are pore density (PPI), thickness of baffles (tc), and number of baffles (nob). Results showed that, heat transfer rate (Qave) and the pressure drop (∆p) increased with increase pore density, and well distribution of a CFB increase thermal performance while the pressure drop did not change with use same volume of CF.

Linkage and F-Regularity of Determinantal Rings

Abstract In this paper, we prove that the generic link of a generic determinantal ring defined by maximal minors is strongly $F$-regular. In the process, we strengthen a result of Chardin and Ulrich in the graded setting. They showed that the generic residual intersections of a complete intersection ring with rational singularities again have rational singularities. We show that if the said complete intersection is defined by homogeneous elements and is $F$-rational, then in fact, its generic residual intersections are strongly $F$-regular in positive prime characteristic. Hochster and Huneke showed that determinantal rings are strongly $F$-regular; however, their proof is quite involved. Our techniques allow us to give a new and simple proof of the strong $F$-regularity of determinantal rings defined by maximal minors.