True Rings Research Articles

Vascular rings and slings: A challenging diagnostic and therapeutic rare disease entity

BackgroundVascular rings (VRs) are classified as true rings or partial rings. The complete VRs include double aortic arch (DAA) and right aortic arch (RAA) with aberrant left subclavian artery and left ligamentum. The incomplete (VRs) include innominate artery compression and pulmonary artery sling. MethodsWe retrospectively analyzed the data from 90 patients with VRs and pulmonary artery slings diagnosed at Mansoura University Children’s Hospital between 2004 to 2016. The initial diagnostic clue might be a right sided aortic arch on a plain x-ray chest. Lateral views were evaluated for retro tracheal opacity, anterior tracheal bowing, and posterior indentation. In our series, bronchoscopy was used for patients with respiratory tract symptoms. Bronchoscopy was performed in 21 patients (23.3%), with finding of external tracheal wall pulsatile compression. Echocardiography was used initially in most cases as the first diagnostic tool followed by Multislice CT scan (MSCT). ResultsThe age of operation was significantly earlier in patients with complete VRs versus incomplete vascular rings. By far the commonest variant was the DAA which constituted in our series 57.8%. The second common type was RAA with aberrant left subclavian and left ligamentum which constituted 30%. The third most common type was pulmonary artery sling constituting 6.7%. In our series, Echocardiography was done in 78 cases (85.6%). It was useful not only in initially diagnosing VR anomaly but also it detected associated cardiac anomalies in 4 cases. MSCT was an excellent noninvasive diagnostic modality that was used in 75 cases (83.3%). We operated 90 cases; 79 via left thoracotomy, 10 cases via median sternotomy and one case via right thoracotomy. Among the 90 cases that were operated, there was a single mortality, no cases were complicated by recurrent laryngeal nerve injury and five cases had postoperative chylothorax. ConclusionsIn our series, Echocardiography and MSCT were essential for proper diagnosis and planing for surgery. Left thoracotomy or median sternotomy provided good exposure in the operated cases. Surgery was done with low mortality and morbidity.

Automatic detection of circular structures in high‐resolution satellite images of agricultural land

AbstractArchaeological sites are sometimes visible in satellite images as soil or crop marks. At best, the marks are distinct, but they tend to have less contrast with the background than many other patterns in the images. Consequently, reliable automated detection based on pattern recognition is very difficult. Our method detects circle‐shaped soil and crop marks in the panchromatic band of high‐resolution satellite images of agricultural fields. Such circular marks may be caused by burial mounds. In our approach, local contrast enhancement is applied in order to make weak marks more distinct. The image is then convolved with ring templates of varying sizes, giving high absolute values at candidate circular mark locations. Each candidate mark is presented to an operator, who may reject it. We tested our method on Quickbird images from southeast Norway. The number of detected candidate marks could be varied by changing a threshold value. A reasonable compromise between not detecting too many false rings and at the same time detecting as many true rings as possible, might be when the number of false detections is approximately seven times the number of true detections. In this case, 11 out of 15, or 73%, of the strong rings were detected, and 5 out of 10, or 50%, of the fairly strong rings were detected. This is 16 out of 25 of the strong and fairly strong rings, or 64%. Archaeologists state that the software tool we developed will be helpful for locating potential cultural heritage sites. Although it makes many false detections, it will relieve the operators from time‐consuming manual inspection of entire images. Copyright © 2008 John Wiley & Sons, Ltd.

The ring characteristics on bony structures for age determination of fish

It is possible to determine the age of fish by reading the annulus in bony structures (scale, otolith, vertebra, opercle, cross section of spine and fin rays). The suitability of the use of the diffrent bony structures and the tecniques may vary among the species. The causes and the periodicity of ring formation may different from species to species. It is essential that the true rings be distinguished from other types of rings, such as false, double, spawning and check rings to avoid confusion and inaccuracy in age determination. While the true annual rings are running concentrically all around the centre of the bony structures, false rings are discontinuous nature. The regeneration and absorbtion on scale are problem for age determination. In this study, some ring which is problem for age determination with the photograph has been showed.

Structure and Bonding in First‐Row Transition‐Metal Dicarbides: Are They Related to the Stability of Met‐cars?

First-row transition-metal dicarbides MC(2) (M=Sc-Zn) have been investigated by using quantum-mechanical techniques. The competition between cyclic and linear isomers in these systems has been studied and the bonding scheme for these compounds is discussed through topological analysis of electron density. All of the systems have been found to prefer a C(2v)-symmetric arrangement, although for ZnC(2) the energy difference between this and the linear isomer is rather small. In most cases the C(2v)-symmetric structure corresponds to a T-shaped structure, with the exceptions of TiC(2), CoC(2), and NiC(2) which have been shown to be true rings. A detailed analysis of the variation of the energy of the system with geometry has been carried out. An analysis of the bonding, taking into account the main interactions between the valence orbitals of both fragments, the M atom and the C(2) molecule, has allowed the main features of these compounds to be interpreted. A clear correlation between the dissociation energies of the first-row transition-metal dicarbides and the bonding energies of the corresponding met-cars was observed.

Kombinierte Altersbestimmung und Altersentwicklung von Jungbuchen - Fagus sylvatica L. -nach morphologischen und anatomischen Merkmalen

Summary Tree ring analyses from cuttings through the middle of the hypocotyle and the following length increments were done on young beeches of known age with and without “lammas shoots”. It could be pointed out that the accurate age can be certainly determined by analyses of ring formation. Endogenous-proleptic shoots do not cause a false wood ring. During these investigations there could be found false wood rings only in few cases. These false rings (additional rings) are distinguished from true rings by the blurred boundary between the first increment area and the following additional increment. It is also possible to determine morphologically the acurate age of young beech plants by counting the length increments produced regularly along the axis of the primary leaf axil shoots including the hypocotyle. Thus, the number of the length increments is identical with the number of the true rings in the hypocotyle. The different branching patterns of one year old beech seedlings are morphologically described. A field method for testing the accurate age of young beech seedlings is presented.

Age Determination and Longevity in Fishes

It is possible to determine the age of fishes with reasonable accuracy by reading the 'growth rings' (annuli) in hard parts (scale, otolith, opercular bone, vertebra and cross-section of dorsal or pectoral spine and fin rays). Primary growth increments in 'otoliths' can also be used as an alternative method of age determination. The traditional methods could be supplemented with more reliable fluorochrome and microradiographic techniques. The suitability of the use of hard parts and the techniques may vary among the species. It is essential that the 'true rings' be distinguished from other types of rings, such as false rings, larval rings and spawning rings through repeated examination of samples to avoid confusion and inaccuracy in age determination. The causes and the periodicity of ring formation may vary from species to species. The growth history of fishes could be traced by back calculation of length attained at different ages. Among the different types of growth equations, the Von Bertalanffy's model appears to be the most suitable for fishes of both temperate and tropical regions. With slight modification, the same model may also serve to estimate the maximum theoretical calculated age (longevity) of fishes. The longevity of fishes show wide variations. The life-span may be short, intermediate and long. Whereas the lowest range of life-span (1-2 years) is exhibited by some species of lampreys and teleosts, there are species of dogfishes, sturgeons, paddlefishes, rockfishes and eels which have the life-span (70-152 years) in the highest range. A number of factors (size, sex, temperature, diet, reproduction, age at maturity and genetic composition) are believed to influence the longevity of fishes.