Separation Of Walls Research Articles

Spontaneous Coronary Artery Dissection with Cardiogenic Shock in the United States.

Spontaneous coronary artery dissection (SCAD) is defined as a non-traumatic separation of the epicardial coronary artery walls that creates a false lumen. SCAD poses a difficult challenge in management, as decisions regarding revascularization and medical management seem to be tailored to the individual patient. We evaluated and compared outcomes based on cardiogenic shock in patients with SCAD utilizing Nationwide Readmissions Database (NRD) between January 1, 2016, to December 30, 2020. We utilized the NRD 2016-2019 to carry out this study. We evaluated demographics (e.g., age, gender), conventional risk factors, comorbidities present on the index admission, and in-hospital outcomes using their specific ICD-10-CM codes. The primary outcomes were In-hospital mortality and 30-day readmission, and the secondary outcome was to compare the complications in SCAD patient with cardiogenic shock (CS) compared to those without CS. We analyzed 2473 individuals with SCAD, 2199 of these individuals did not have cardiogenic shock whereas 274 of these individuals did have cardiogenic shock. When comparing SCAD with cardiogenic shock to SCAD without cardiogenic shock, there was a statistically significant increased odds ratio (OR) for death (propensity matched OR 24.93 (7.49-83.05), use of mechanical circulatory support (propensity matched OR 15.30 (6.87-34.04), ventricular tachycardia (propensity matched OR 4.45 (1.92-10.34), utilization of blood transfusions (propensity matched OR 3.82 (1.86-7.87), acute kidney injury (propensity matched OR 4.02 (1.45-11.13), need for mechanical ventilation (propensity matched OR 8.87 (3.53-22.31), and respiratory failure (propensity matched OR 4.95 (1.83-13.41)))))))). There was no statistically significant difference in 30-day readmission rates between the two groups. SCAD is a unique condition that can lead to many complications. In our analysis, we showed that SCAD associated with cardiogenic shock compared to SCAD not associated with cardiogenic shock results in greater odds of complications including death, use of mechanical circulatory support, need for blood transfusions, ventricular tachycardia, acute kidney injury, use of mechanical ventilation, and respiratory failure. SCAD with cardiogenic shock represents a significantly critical clinical scenario that requires a multi-disciplinary approach to prevent the many potential complications associated with this disease process.

Flows past cylinders confined within ducts. Effects of the duct width

We present direct numerical simulations (DNS) of the flow past a circular cylinder confined in a rectangular duct at a Reynolds number of Re=630, based on the bulk velocity and the cylinder diameter. The blockage ratio, defined as the ratio of the cylinder diameter to the duct height, is set at β=0.6. We find the topology of the wake is highly sensitive to the duct width, and suggest that care needs to be taken comparing results with experimental data sets. This is unlike the flow past an unconfined or lowly confined cylinder where the general topology remains relatively similar with duct width. Ducts of width 4.44, 10, and 20 times the cylinder diameter have been considered along with an infinite channel. For the smallest duct of 4.44 cylinder diameters, the effects of the side walls of the duct, or the end walls from the perspective of the cylinder, extend into the core region, where there are strong interactions between the influence from opposing sides. The wake formed is much more chaotic, with Kelvin–Helmholtz vortices observed to form in the shear layers off the cylinder. Hence leading to a shorter wake. With increases in the duct width to 10 cylinder diameters, the separation of the side walls lessens the interactions within the centre of the duct. The shear layers off the cylinder are less destabilised as a result, leading to the formation of a more classical Kármán vortex street. The wake was also found to be longer as a result. However, the blockage effect was still evident at such a duct width. It was only for widths of 20 cylinder diameters or greater, a flow structurally similar to that in an infinite channel could be obtained, with asymmetric structures modulated along the span. Furthermore, the increases in the duct width beyond 10 cylinder diameters lead to decreases in the wake length.

A Case of Spontaneous Coronary Artery Dissection in the Setting of Exogenous Testosterone.

Spontaneous coronary artery dissection (SCAD) is a rare cause of acute coronary syndrome, occurring when there is separation of the coronary artery walls by intramural hemorrhage creating a false lumen. This compresses the arterial lumen, compromising the ability of the coronary artery to perfuse the myocardial tissue. Spontaneous coronary artery dissection is usually fatal, with risk factors including pregnancy, young age, and female sex, birth control, and other hormonal therapies.In this case report, we describe the case of a 31-year-old biological female transitioning to male with exogenous testosterone who experienced a SCAD. Given the known risk factors for SCAD, such as pregnancy and exogenous hormone therapy, this case raises additional considerations regarding rare unintended consequences of testosterone therapy.

Contribution of intrusive and symplastic growths in wood fibre tip development

Key messageAt initial stages of fibre development, radial enlargement of growing fibre tip is achieved, on average, in 37.8% intrusively and in 62.2% symplastically, whereas tip tangential enlargement is purely intrusive.In this study, we have investigated the mode of growth of black locust wood fibre tips at initial stages of their development using detailed measurements. Growth of fibre tips may be considered in three directions: axial, tangential, and radial. An axial elongation of a fibre tip was described as intrusive and related to the separation of walls of neighbouring cells. However, determination of the contribution of intrusive vs. symplastic component of growth in tangential and radial directions was missing. Semi-thin transverse sections of the vascular cambium and adjacent tissues were obtained by ultramicrotome and stained with PAS and toluidine blue. An anatomical analysis of contribution of intrusive and symplastic growths in fibre tip radial and tangential enlargement was performed. Our study showed that during its development an average wood fibre tip grows only intrusively in tangential direction and shows intrusive-symplastic growth in radial direction. On average, at initial stages of its development, a fibre tip radial enlargement is achieved in 37.8% by intrusive growth and in 62.2% by coordinated (symplastic) growth.

Depolymerization behaviors of naked oat stem during autohydrolysis in mild subcritical water Ⅱ: Correlative changes in tissue structure, cell morphology, and chemical composition.

Green, efficient depolymerization of lignocellulose is a prerequisite and the key in high-value utilization of its components. Understanding of the changes in morphological chemistry of the cell wall, related to the biomass recalcitrance, is critical for optimizing the processing conditions of cell wall deconstruction. Thus, herein, based on our previous studies, subcritical water autohydrolysis of naked oat stems was conducted at 190 °C and 1.18 MPa for 0–60 min. The depolymerization behaviors of tissues and cell walls were monitored dynamically at 10 min intervals. The micro-and ultrastructural changes of autohydrolyzed residue sections were analyzed. Parenchyma tissue commenced dissociation after 10 min at 190 ℃, whereas mechanical tissue dissociation occurred after 40 min at 190 ℃, along with interlayer separation of the secondary walls of sclerenchyma fibers. The autofluorescence changes of lignin showed that the order of regional lignin removal in tissues was from sieve tubes and companion cells to parenchyma cells, and finally to sclerenchyma fibers and vessel elements. The turning point of tissue and cell wall structural depolymerization of naked oat stems under subcritical water autohydrolysis conditions occurred after 40 min at 190 ℃ and 1.18 MPa. Under this condition, the degree of tissue dissociation was as high as 80%, while the fiber cell morphology remained intact. Dynamic changes in the tissue and cell wall structures and cell morphologies of naked oat stems maintained at 190 ℃ for various durations were captured by differentiating the use of the optical microscope, fluorescence microscope, and scanning electron microscope. The extensive, detailed assay data yield novel insights into the dynamic depolymerization mechanism of lignocellulosic composite cell walls under subcritical water autohydrolysis conditions.

Separation of domain walls with nonlocal interaction and their renormalised energy by Γ-convergence in thin ferromagnetic films

We analyse two variants of a nonconvex variational model from micromagnetics with a nonlocal energy functional, depending on a small parameter ϵ>0. The model gives rise to transition layers, called Néel walls, and we study their behaviour in the limit ϵ→0. The analysis has some similarity to the theory of Ginzburg-Landau vortices. In particular, it gives rise to a renormalised energy that determines the interaction (attraction or repulsion) between Néel walls to leading order. But while Ginzburg-Landau vortices show attraction for degrees of the same sign and repulsion for degrees of opposite signs, the pattern is reversed in this model.In a previous paper, we determined the renormalised energy for one of the models studied here under the assumption that the Néel walls stay separated from each other. In this paper, we present a deeper analysis that in particular removes this assumption. The theory gives rise to an effective variational problem for the positions of the walls, encapsulated in a Γ-convergence result. In the second part of the paper, we turn our attention to another, more physical model, including an anisotropy term. We show that it permits a similar theory, but the anisotropy changes the renormalised energy in unexpected ways and requires different methods to find it.

Investigation into the deterioration of Castanopsis hystrix buried wood by anatomical, chemical and thermal analysis

Comparative studies of the anatomy and composition had been investigated to learn about the degradation characteristics of Castanopsis hystrix wood. Its chemical degradation was analyzed with wet chemical analysis, Fourier-transform infrared analysis, x-ray diffraction analysis, and thermogravimetric analysis. Its morphology was observed with light microscopes and scanning electron techniques. It was found that the deformation and separation of cell walls have no effect on the identification of C. hystrix wood. The degradation of polysaccharides leads to the mechanical properties of C. hystrix buried wood decreased. The inclusions exist in cells of C. hystrix buried wood increased, and the dark color is related to the inclusions and ferric oxide. Furthermore, the hemicellulose was heavily degraded but there was no obvious degradation of crystalline cellulose. Large amounts of inorganic elements such as Fe and S were detected in the ash of C. hystrix buried wood.

Temperature-activation mechanism of the temperature dependence of the dielectric constant of ferroelectric ceramics PZT

The theoretical possibility of the temperature-activation process of the temperature dependence of the dielectric constant of samples of ferroelectric ceramics lead zirconate titanate (PZT) at temperatures below the Curie point is considered. The model takes into account the 180° motion of the domain wall, which is located in the potential well. The values of activation energies ([Formula: see text] 0.01, 0.1, 1 eV) were obtained from the experimental dependences of the logarithm of the dielectric constant on the reciprocal temperature. This is associated with three processes: initial vibrations of domain walls; separation of domain walls (DWs) from oxygen vacancies; the motion of DWs as a result of the motion of oxygen vacancies.

499 What light through yonder window breaks? Benefits of optical coherence tomography (OCT) in a case of spontaneous coronary artery dissection

Abstract Aims Spontaneous coronary artery dissection (SCAD) is a non-traumatic and non-iatrogenic separation of the coronary arterial walls, creating a false lumen. SCAD is an infrequent and often missed diagnosis especially in women presenting with acute coronary syndrome and in the majority of cases angiography alone could be insufficient for identification. Methods and results A 43-year-old woman presented to the Emergency Department of Fondazione Policlinico Universitario A. Gemelli IRCCS (Rome, Italy) for oppressive acute chest pain radiated to the right jaw, resolved spontaneously within a few minutes. Physical examination, including cardiovascular evaluation, was normal. High-sensitivity troponin was 152 ng/l and 250 ng/l in two serial determination (reference range, 0.0–37 ng/l). EKG showed sinus rhythm with no significant ST-segment alterations. Echocardiography revealed preserved biventricular systolic function with mild hypokinesia of the apical segments of the left ventricle. A diagnosis of NSTEMI was made based on clinical and laboratory parameters. Thus, urgent coronary angiography was performed, which demonstrated a single vessel disease with an eccentric, and angiographically complex stenosis of the proximal left anterior descending (LAD) artery with an image of plus compatible with a plaque ulceration. In order to define the extension of the disease and ostium involvement for a better procedural planning, OCT imaging was performed. Surprisingly, OCT showed a intramural haematoma extending from the ADA ostium to the proximal tract (approximately 22 mm) with ulceration in the body, minimal lumen area (MLA) 2.0 mm2 and evidence of normal trilaminar structure of the vessel both on downstream and upstream of the lesion. The angiographic features were compatible with type 2A SCAD. The therapeutic management was conservative with continuation of the double antiplatelet therapy and remote CT monitoring. Three days later, because of a new onset of chest pain and slight elevation of the ST segment on EKG, was performed a coronarographic control: the angiographic appearance of the lesion was substantially unchanged; OCT showed unmodified longitudinal extension of the lesion (about 22 mm) and relative increase in the endoluminal caliber compared to the previous examination (MLA 4.0 mm2).After 2 weeks, coronary CTA control was carried out, which documented the stability of the intramural hematoma in the proximal LAD, extended for 22 mm and with a maximum thickness of 2 mm, determining lumen narrowing of 40–45% The patient was discharged on medical therapy and no events occurred during the follow-up. Six month later, repeat CTA showed a complete resorption of the intramural haematoma. Conclusions In this case we highlight the utility of intravascular imaging, in particular OCT, in the evaluation of angiographic lesions of non-univocal interpretation and how its use can change the management and prognosis of ACS patients. Furthermore, the spontaneous resolution of the clinical and anatomical scenario through conservative treatment additionally confirms spontaneous healing as the natural history of SCAD and foreground the role of precise diagnosis (and intravascular imaging showed to improve it) for therapy shift and calibration.

Procjena stanja zidanih građevina i džamija nakon potresa u Sivricu

The evaluation of masonry and mosque type structures after the Sivrice Earthquake is presented in this study. Stone masonry buildings exhibited damage such as vertical cracks and splitting at corners, wedge shaped corner failures, diagonal cracking on walls, out-of-plane splitting of walls, and separation of walls from flooring/roofing systems. On the other hand, the separation of flags and caps of minarets was a common example of damage in mosques. Future earthquake damage can be prevented by following design codes and providing adequate supervision for new structures, while strengthening measures are recommended for the existing buildings.

A new Protophyllocladoxylon stem from the Xishanyao Formation (Middle Jurassic) in the Santanghu Basin, Xinjiang, Northwest China

A new permineralized stem, Protophyllocladoxylon yiwuense Gou et Feng sp. nov., is described from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang Uygur Autonomous Region, Northwest China. The stem is only preserved with secondary xylem, which is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. The tracheids have uniseriate or biseriate, alternately arranged bordered pits on their radial walls, and uniseriate bordered pits on the tangential walls. The rays are uniseriate or partially biseriate, up to 34 cells high. There are one or two large, simple pits in each cross field. A branch trace horizontally passes through the secondary xylem showing anatomical structures identical to the secondary xylem. Analyses of the growth-ring width and mean sensitivity values indicate that P. yiwuense had long growing seasons with readily available water supplies and favorable paleoclimatic conditions. White-rot decay features are commonly recognized in the stem, including pocket-like cavities, complete removal of the middle lamellae, thickened corners and separation of the secondary walls of tracheids, as well as septa-like structures in the tracheid lumens due to the cell's reactions to fungal activity. Our study sheds new light into the plant diversity and paleoenvironmental and paleoecological conditions of the Middle Jurassic.

Assessment and Fragility of Byzantine Unreinforced Masonry Towers

The seismic response of five cultural heritage towers erected between the 10th and 19th century AD are investigated herein. Firstly, their architectural and modal characteristics were studied in the light of seismic events that hit the monuments. There exist several historical reports of strong earthquakes, as well as damaged structures and collapses. The limit analysis is adopted to examine the post-elastic behavior of the towers up to collapse due to out-of-plane failure. Recurrent damage modes were collected from recent earthquakes and a classification of four possible collapse mechanisms in towers and slender masonry structures is here proposed: overturning, separation of perpendicular walls, diagonal cracking, and dislocation of the belfry. A thorough examination of the towers under investigation verified the proposed damage classification. The capacity curves were derived combining the capacity curves of each of the collapse mechanisms. Damage thresholds were defined on these curves in correspondence with damage states. The studied group of structures is representative of a wider typology. A statistical approach was adopted to describe damage with seismic intensity, and vulnerability curves were generated. The results of this study will improve the understanding of the performance and the collapse mechanisms of slender masonry structures under seismic loading and provide a characterization of seismic vulnerability for the studied cultural heritage types of towers.

Paleokrajobrazowe aspekty badań nad podepozycyjnymi procesami destrukcji ceramiki osadowej (przypadek kunicki)

The author presents the results of research on a specific type of destruction of pottery from archaeological excavations on a settlement from Late Bronze Age and Early Iron Age(HaB3–HaD1 dated to the 9th–6th centuries BC) in Kunice, voivodeship Lower Silesia. It is located on one of the few postglacial lakes present till now in Silesia. Analysed were disintegrations in form of separation of pottery walls observed on the coil contacts. Topographic and stratigraphic approach to this phenomenon allowed to show its post-depositional character, recognise the causes, and trace the dynamics of this process. The obtained results indicate that there exists a relationship between the pottery wall separations and the hydrological effects of the impact of climatic factors in the course of the oldest oscillation of the Subatlantic stage, generally humid and cool. They enrich and specify the insight on the scale and impact of hydrological changes on the paleo-landscape. The most important, however, is the appreciation of the cognitive values of the source mass material in studying problems that go beyond the trend present in cultural studies.

Simulation of non-resonant stellarator divertor

An efficient numerical method of studying nonresonant stellarator divertors was introduced in Boozer and Punjabi [Phys. Plasmas 25, 092505 (2018)]. This method is used in this paper to study a different magnetic field model of a nonresonant divertor. The most novel and interesting finding of this study is that diffusive magnetic field lines can be distinguished from lines that exit through the primary and the secondary turnstile, and that below some diffusive velocity, all lines exit through only the primary turnstile. The footprints of each family are stellarator symmetric and have a fixed location on the wall for all velocities. The probability exponent of the primary turnstile is d1 = 9/4 and that of the secondary turnstile is d2 = −3/2. This study also addresses the issues of an inadequate separation of the chamber walls from the outermost confining magnetic surface and a marginal step size of the numerical integrations that could compromise the interpretation of the earlier results [Boozer and Punjabi, Phys. Plasmas 25, 092505 (2018)]. The previous value of d1 = 2 is within the error bar of d1 = 9/4 estimated here.

Transmesocolic double gastro-enteric fistulas due to ingestion of 28 magnets

Abstract Introduction Accidental ingestion of magnetic foreign bodies has become more common due to increased availability of objects and toys with magnetic elements. The majority of them traverse the gastrointestinal system spontaneously without complication. However, ingestion of multiple magnets may require surgical resolution. Magnet ingestion usually does not cause serious complications, but in case of multiple magnet ingestion or ingestion of magnet and a metal object, it could cause intestinal obstruction, fistula formation or even perforation. Case report We report case of a transmesocolic double gastro-enteric fistula formation following ingestion of 28 small magnets in a 17 months old boy. No history of foreign body ingestion could be obtained from parents therefore the patient was treated conservatively in a pediatric clinic for vomiting, dehydration, upper respiratory tract infection and suspicion of upper digestive tract bleeding. After 48 h he was sent in our clinic for surgical evaluation. Intraoperatively double transmesocolic gastro-enteric fistula was found. After separation of de gastric and enteral walls, resection of gastric wall and intestinal segment containing the two perforations was performed, followed by gastric suture in two layers and entero-enteric anastomosis. A total of 28 magnets were removed from the stomach and small intestine. Conclusion Single magnet ingestion is treated as non-magnetic foreign body. Multiple magnet ingestion should be closely monitored and surgical approach could be the best option to prevent or to cure its complications.

Efficient preparation of Arabidopsis pollen tubes for ultrastructural analysis using chemical and cryo-fixation

BackgroundThe pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana.MethodsHere, we present reliable approaches for ultrastructural studies of Arabidopsis PTs, as well as an efficient technique for immunogold detection of cell wall epitopes. Using different fixation and embedding strategies, we show the amount of PT ultrastructural details that can be obtained by the different methods. ResultsDozens of cross-sections can be obtained simultaneously by the approach, which facilitates and shortens the time for evaluation. In addition to in vitro-grown PTs, our study follows the route of PTs from germination, growth along the pistil, to the penetration of the dense stylar tissue, which requires considerable mechanical forces. To this end, PTs have different strategies from growing between cells but also between the protoplast and the cell wall and even within each other, where they share a partly common cell wall. The separation of PT cell walls in an outer and an inner layer reported for many plant species is less clear in Arabidopsis PTs, where these cell wall substructures are connected by a distinct transition zone.ConclusionsThe major advancement of this method is the effective production of a large number of longitudinal and cross-sections that permits obtaining a detailed and representative picture of pollen tube structures in an unprecedented way. This is particularly important when comparing PTs of wild type and mutants to identify even subtle alterations in cytoarchitecture. Arabidopsis is an excellent plant for genetic manipulation, yet the PTs, several-times smaller compared to tobacco or lily, represent a technical challenge. This study reveals a method to overcome this problem and make Arabidopsis PTs more amenable to a combination of genetic and ultrastructural analyses.

МОРФОФУНКЦІОНАЛЬНІ ОСОБЛИВОСТІ ПЛАЦЕНТИ ПРИ ПЕРЕНОШЕНІЙ ВАГІТНОСТІ

Мета дослідження – вивчити морфофункціональні особливості плаценти у породіль з переношеною вагітністю.Матеріали та методи. Проведено динамічне спостереження за 15-ма вагітними з моменту їх госпіталізації до виписки після пологів. Жінки розподілені на 2 групи: перша група – 10 жінок із переношеною вагітністю 42 тижні; друга група – 5 жінок із фізіологічним перебігом вагітності. Після пологів забирали амніотичну оболонку, пуповину та плаценту. Проводили макроскопічне та мікроскопічне дослідження. Після макроскопічного обстеження плаценти вирізали кусочки амніона, пуповини та плаценти (з біля пуповинної, середньої частини та крайової ділянки). Гістологічний матеріал фіксували у 4 % нейтральному формаліні.Результати дослідження та їх обговорення. Показано, що перебіг пологів при переношеній вагітності характеризується такими ускладненнями, як: передчасне вилиття навколоплодових вод, аномалії пологової діяльності, дистрес плода, травми родових шляхів, збільшення оперативних втручань у пологах, що обумовлює підготовку родових шляхів та своєчасного розв’язання пологів. На основі морфофункціональних досліджень плаценти констатували, що переношена вагітність характеризується більш вираженими патологічними змінами плаценти, у тому числі патологічною незрілістю і значною перевагою дрібних та проміжних ворсинок різної форми, масивними депозитами фібриноїду як навколо ворсинок, так і у міжворсинчастому просторі та агрегацією термінальних ворсин, витонченням синцитіотрофобласта на тлі слабовиражених компенсаторних реакцій.Висновки. Морфофункціональні зміни у плаценті жінок із переношеною вагітністю із зміною структури плацентарного бар’єра можуть бути однією з причин переношування вагітності. Дистрофічні процеси амніона, зниження продукції та резорбції амніотичної рідини, набряк компактного шару амніона та вартонових драглів пуповини, розшарування стінки артерій пуповини – ознака порушення процесів плодово-плацентарного кровопостачання і є фактором ризику негативного впливу на життєдіяльність плода.

AN AUTOMATIC METHOD FOR GEOMETRIC SEGMENTATION OF MASONRY ARCH BRIDGES FOR STRUCTURAL ENGINEERING PURPOSES

Abstract. Despite the tremendous advantages of the laser scanning technology for the geometric characterization of built constructions, there are important limitations preventing more widespread implementation in the structural engineering domain. Even though the technology provides extensive and accurate information to perform structural assessment and health monitoring, many people are resistant to the technology due to the processing times involved. Thus, new methods that can automatically process LiDAR data and subsequently provide an automatic and organized interpretation are required. This paper presents a new method for fully automated point cloud segmentation of masonry arch bridges. The method efficiently creates segmented, spatially related and organized point clouds, which each contain the relevant geometric data for a particular component (pier, arch, spandrel wall, etc.) of the structure. The segmentation procedure comprises a heuristic approach for the separation of different vertical walls, and later image processing tools adapted to voxel structures allows the efficient segmentation of the main structural elements of the bridge. The proposed methodology provides the essential processed data required for structural assessment of masonry arch bridges based on geometric anomalies. The method is validated using a representative sample of masonry arch bridges in Spain.

AN AUTOMATIC METHOD FOR GEOMETRIC SEGMENTATION OF MASONRY ARCH BRIDGES FOR STRUCTURAL ENGINEERING PURPOSES

Despite the tremendous advantages of the laser scanning technology for the geometric characterization of built constructions, there are important limitations preventing more widespread implementation in the structural engineering domain. Even though the technology provides extensive and accurate information to perform structural assessment and health monitoring, many people are resistant to the technology due to the processing times involved. Thus, new methods that can automatically process LiDAR data and subsequently provide an automatic and organized interpretation are required. <br><br> This paper presents a new method for fully automated point cloud segmentation of masonry arch bridges. The method efficiently creates segmented, spatially related and organized point clouds, which each contain the relevant geometric data for a particular component (pier, arch, spandrel wall, etc.) of the structure. The segmentation procedure comprises a heuristic approach for the separation of different vertical walls, and later image processing tools adapted to voxel structures allows the efficient segmentation of the main structural elements of the bridge. The proposed methodology provides the essential processed data required for structural assessment of masonry arch bridges based on geometric anomalies. The method is validated using a representative sample of masonry arch bridges in Spain.

The morphology of free-living stages and immature parasites of Rhabdias paraensis (Nematoda: Rhabdiasidae), a parasite of Rhinella marina (Anura: Bufonidae) in Brazil.

Rhabdias paraensis Santos, Melo, Nascimento, Nascimento, Giese et Furtado, 2011 was described based on fully gravid worms. Further investigations on the free-living stages, immature worms and young individuals were facilitated by cultivation in the laboratory, which allowed us to add new information about the morphology and development of the species. Observations on the free-living development of R. paraensis showed that the life cycle is typical of Rhabdias, with alternation of gonochoristic and hermaphroditic generations and without homogony. Males of the free-living generation were different from those in several species of the genus studied previously. In the original description, the excretory glands and duct were absent in gravid specimens of R. paraensis, while in this study, distinct excretory glands and a duct were observed in immature and young individuals. Additionally, we recognised the separation of the buccal capsule walls into anterior and posterior portions and described the specific shapes of these portions in lateral and apical view. Studies on the morphology and development of free-living stages of Rhabdias spp. from Neotropical regions may provide additional information for species determination.