The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Caroline Ovaert - One of the best experts on this subject based on the ideXlab platform.
-
kommerell diverticulum should be removed in children with vascular ring and aberrant left subclavian artery
The Annals of Thoracic Surgery, 2015Co-Authors: Deborah Luciano, Julia Mitchell, Alain Fraisse, Hubert Lepidi, Bernard Kreitmann, Caroline OvaertAbstract:Background Right aortic arch with aberrant left subclavian artery is the most frequent cause of vascular ring. Ligamentum arteriosus division opens the ring but leaves the Kommerell diverticulum in place, with a risk of residual compression, aneurysmal dilation, dissection, or even rupture. A Procedure consisting of translocation of the aberrant left subclavian artery to the left carotid artery with removal of the Kommerell diverticulum and division of the ligamentum is currently advocated. Methods Between September /2009 and August 2011, 12 consecutive patients underwent the Foregoing Procedure. Clinical findings, surgical Procedure, complications, histopathologic findings, and follow-up data were retrospectively analyzed. Results Mean age at the time of operation was 7.7 years (median, 4.3 years, range, 0.9 to 18.9 years), and mean weight was 26 kg (median, 18 kg; range, 8.4 to 59 kg). All patients had symptoms. Computed tomography scan or magnetic resonance imaging, or both, had confirmed the diagnosis in all patients. Postoperative events, all transient, included chylothorax (1 patient), phrenic palsy (1 patient), pneumonia (1 patient), and the need for prolonged chest drainage (3 patients). Mean follow-up reached 19 months (median, 13 months; range, 12 to 41 months). Mild residual respiratory symptoms were noted in 3 patients. Echo-Doppler analysis showed a patent left subclavian–to–carotid artery anastomosis. Histopathologic analysis of the resected diverticulum (n = 6) showed cystic medial necrosis in four diverticula (focal in one). Conclusions Translocation of the aberrant left subclavian artery with diverticulum resection and ligamentum division is an efficient Procedure for symptom relief. Profound wall abnormalities such as medial necrosis in at least 50% of the analyzed diverticula encourage us to maintain this strategy, to reduce the risk of aneurysm formation and dissection.
Afshin Taghvaeipour - One of the best experts on this subject based on the ideXlab platform.
-
An enhanced inverse dynamic and joint force analysis of multibody systems using constraint matrices
Multibody System Dynamics, 2019Co-Authors: Ramin Ghaedrahmati, Ali Raoofian, Ali Kamali e., Afshin TaghvaeipourAbstract:In this paper, a new way of computing the constraint transfer matrix for the inverse dynamic and joint force analysis of multibody systems is developed. The method is based on the Newton–Euler method and the screw theory notations. This method is first developed in (Taghvaeipour et al. in Multibody Syst. Dyn. 29(2):139–168, 2013 ), however, in this study, it is efficiently modified by incorporating a unified constraint transfer matrix for all types of joints. This change makes both the derivation of the equations and the computations less time consuming. Moreover, in the Foregoing Procedure, the constraint wrenches of a system are obtained in one reference frame, namely, the global reference frame. As a case study, the proposed method is carried out on the agile wrist which is a three-legged spherical parallel robot with three degrees of freedom. At the end, the results obtained by the modified method are verified with the ones calculated by the original Procedure and a software package.
Deborah Luciano - One of the best experts on this subject based on the ideXlab platform.
-
kommerell diverticulum should be removed in children with vascular ring and aberrant left subclavian artery
The Annals of Thoracic Surgery, 2015Co-Authors: Deborah Luciano, Julia Mitchell, Alain Fraisse, Hubert Lepidi, Bernard Kreitmann, Caroline OvaertAbstract:Background Right aortic arch with aberrant left subclavian artery is the most frequent cause of vascular ring. Ligamentum arteriosus division opens the ring but leaves the Kommerell diverticulum in place, with a risk of residual compression, aneurysmal dilation, dissection, or even rupture. A Procedure consisting of translocation of the aberrant left subclavian artery to the left carotid artery with removal of the Kommerell diverticulum and division of the ligamentum is currently advocated. Methods Between September /2009 and August 2011, 12 consecutive patients underwent the Foregoing Procedure. Clinical findings, surgical Procedure, complications, histopathologic findings, and follow-up data were retrospectively analyzed. Results Mean age at the time of operation was 7.7 years (median, 4.3 years, range, 0.9 to 18.9 years), and mean weight was 26 kg (median, 18 kg; range, 8.4 to 59 kg). All patients had symptoms. Computed tomography scan or magnetic resonance imaging, or both, had confirmed the diagnosis in all patients. Postoperative events, all transient, included chylothorax (1 patient), phrenic palsy (1 patient), pneumonia (1 patient), and the need for prolonged chest drainage (3 patients). Mean follow-up reached 19 months (median, 13 months; range, 12 to 41 months). Mild residual respiratory symptoms were noted in 3 patients. Echo-Doppler analysis showed a patent left subclavian–to–carotid artery anastomosis. Histopathologic analysis of the resected diverticulum (n = 6) showed cystic medial necrosis in four diverticula (focal in one). Conclusions Translocation of the aberrant left subclavian artery with diverticulum resection and ligamentum division is an efficient Procedure for symptom relief. Profound wall abnormalities such as medial necrosis in at least 50% of the analyzed diverticula encourage us to maintain this strategy, to reduce the risk of aneurysm formation and dissection.
Ramin Ghaedrahmati - One of the best experts on this subject based on the ideXlab platform.
-
An enhanced inverse dynamic and joint force analysis of multibody systems using constraint matrices
Multibody System Dynamics, 2019Co-Authors: Ramin Ghaedrahmati, Ali Raoofian, Ali Kamali e., Afshin TaghvaeipourAbstract:In this paper, a new way of computing the constraint transfer matrix for the inverse dynamic and joint force analysis of multibody systems is developed. The method is based on the Newton–Euler method and the screw theory notations. This method is first developed in (Taghvaeipour et al. in Multibody Syst. Dyn. 29(2):139–168, 2013 ), however, in this study, it is efficiently modified by incorporating a unified constraint transfer matrix for all types of joints. This change makes both the derivation of the equations and the computations less time consuming. Moreover, in the Foregoing Procedure, the constraint wrenches of a system are obtained in one reference frame, namely, the global reference frame. As a case study, the proposed method is carried out on the agile wrist which is a three-legged spherical parallel robot with three degrees of freedom. At the end, the results obtained by the modified method are verified with the ones calculated by the original Procedure and a software package.
Mark James - One of the best experts on this subject based on the ideXlab platform.
-
Algorithm That Synthesizes Other Algorithms for Hashing
2010Co-Authors: Mark JamesAbstract:An algorithm that includes a collection of several subalgorithms has been devised as a means of synthesizing still other algorithms (which could include computer code) that utilize hashing to determine whether an element (typically, a number or other datum) is a member of a set (typically, a list of numbers). Each subalgorithm synthesizes an algorithm (e.g., a block of code) that maps a static set of key hashes to a somewhat linear monotonically increasing sequence of integers. The goal in formulating this mapping is to cause the length of the sequence thus generated to be as close as practicable to the original length of the set and thus to minimize gaps between the elements. The advantage of the approach embodied in this algorithm is that it completely avoids the traditional approach of hash-key look-ups that involve either secondary hash generation and look-up or further searching of a hash table for a desired key in the event of collisions. This algorithm guarantees that it will never be necessary to perform a search or to generate a secondary key in order to determine whether an element is a member of a set. This algorithm further guarantees that any algorithm that it synthesizes can be executed in constant time. To enforce these guarantees, the subalgorithms are formulated to employ a set of techniques, each of which works very effectively covering a certain class of hash-key values. These subalgorithms are of two types, summarized as follows: Given a list of numbers, try to find one or more solutions in which, if each number is shifted to the right by a constant number of bits and then masked with a rotating mask that isolates a set of bits, a unique number is thereby generated. In a variant of the Foregoing Procedure, omit the masking. Try various combinations of shifting, masking, and/or offsets until the solutions are found. From the set of solutions, select the one that provides the greatest compression for the representation and is executable in the minimum amount of time. Given a list of numbers, try to find one or more solutions in which, if each number is compressed by use of the modulo function by some value, then a unique value is generated.