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Single Loop (single + loop)
Selected AbstractsEntrainment Mapping of Dual-Loop Macroreentry in Common Atrial Flutter:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2004New Insights into the Atrial Flutter Circuit Introduction: The aim of this study was to determine using entrainment mapping whether the reentrant circuit of common type atrial flutter (AFL) is single loop or dual loop. Methods and Results: In 12 consecutive patients with counterclockwise (CCW) AFL, entrainment mapping was performed with evaluation of atrial electrograms from the tricuspid annulus (TA) and the posterior right atrial (RA) area. We hypothesized that a dual-loop reentry could be surmised from "paradoxical delayed capture" of the proximal part of the circuit having a longer interval from the stimulus to the captured beat compared with the distal part of the circuit. In 6 of 12 patients with CCW AFL, during entrainment from the septal side of the posterior blocking line, the interval from the stimulus to the last captured beat was longer at the RA free wall than at the isthmus position. In these six patients with paradoxical delayed capture, flutter cycle length (FCL) was 227 ± 12 ms and postpacing interval minus FCL was significantly shorter at the posterior blocking line than at the RA free wall (20 ± 11 ms vs 48 ± 33 ms, P < 0.05). In two of these patients, early breakthrough occurred at the lateral TA. A posterior block line was confirmed in all six patients in the sinus venosa area by intracardiac echocardiography. Conclusion: Half of the patients with common type AFL had a dual-loop macroreentrant circuit consisting of an anterior loop (circuit around the TA) and a posterior loop (circuit around the inferior vena cava and the posterior blocking line). (J Cardiovasc Electrophysiol, Vol. 15, pp. 679-685, June 2004) [source] Braun enteroenterostomy is associated with reduced delayed gastric emptying and early resumption of oral feeding following pancreaticoduodenectomyJOURNAL OF SURGICAL ONCOLOGY, Issue 5 2010Steven N. Hochwald MD Abstract Background and Objectives Morbidity rates following pancreaticoduodenectomy (PD) remain high with delayed gastric emptying (DGE) and slow resumption of oral diet contributing to increased postoperative length of stay. A Braun enteroenterostomy has been shown to decrease bile reflux following gastric resection. We hypothesize that addition of Braun enteroenterostomy during PD would reduce the sequelae of DGE. Methods From our PD database, patients were identified that underwent classic PD with partial gastrectomy from 2001 to 2006. All patients with reconstruction utilizing a single loop of jejunum at the University of Florida Shands Hospital were reviewed. Demographics, presenting signs and symptoms, pathologic diagnoses, and postoperative morbidity were compared in those patients undergoing reconstruction with an additional Braun enteroenterostomy (n,=,70) to those not undergoing a Braun enteroenterostomy (n,=,35). Results Patients undergoing a Braun had NG tubes removed earlier (Braun: 2 days, no Braun: 3 days, P,=,0.002) and no significant change in postoperative vomiting (Braun: 27%, no Braun: 37%, P,=,0.37) or NG tube reinsertion rates (Braun: 17%, no Braun: 29%, P,=,0.21). Median postoperative day with tolerance of oral liquids (Braun: 5, no Braun: 6, P,=,0.01) and solid diets (Braun: 7, no Braun: 9, P,=,0.01) were significantly sooner in the Braun group. DGE defined by two criteria including the inability to have oral intake by postoperative day 10 (Braun: 10%, no Braun: 26%, P,<,0.05) and the international grading criteria (grades B and C, Braun: 7% vs. no Braun: 31%, P,=,0.003) were significantly reduced in those undergoing the Braun procedure. In addition, the median length of stay (Braun: 10 days, no Braun: 12 days, P,<,0.05) was significantly reduced in those undergoing the Braun procedure. The rate of pancreatic anastomotic failure was similar in the two groups (Braun: 17% vs. no Braun: 14%, P,=,0.79). Median bile reflux was 0% in those undergoing a Braun. Conclusions The present study suggests that Braun enteroenterostomy can be safely performed in patients undergoing PD and may reduce the indicence of DGE and its sequelae. Further studies of Braun enteroenterostomy in larger randomized trials of patients undergoing PD are warranted. J. Surg. Oncol. 2010; 101:351,355. © 2010 Wiley-Liss, Inc. [source] Developing organizational learning in the NHSMEDICAL EDUCATION, Issue 1 2001Sandra M Nutley Learning has been identified as a central concern for a modernized NHS. Continuing professional development has an important role to play in improving learning but there is also a need to pay more attention to collective (organizational) learning. Such learning is concerned with the way organizations build and organize knowledge. Recent emphasis within the NHS has been on the codification of individual and collective knowledge , for example, guidelines and National Service Frameworks. This needs to be balanced by more personalized knowledge management strategies, especially when dealing with innovative services that rely on tacit knowledge to solve problems. Having robust systems for storing and communicating knowledge is only one part of the challenge. It is also important to consider how such knowledge gets used, and how routines become established within organizations that structure the way in which knowledge is deployed. In many organizations these routines favour the adaptive use of knowledge, which helps organizations to achieve incremental improvements to existing practices. However, the development of organizational learning in the NHS needs to move beyond adaptive (single loop) learning, to foster skills in generative (double loop) learning and meta-learning. Such learning leads to a redefinition of the organization's goals, norms, policies, procedures or even structures. This paper argues that moving the NHS in this direction will require attention to the cultural values and structural mechanisms that facilitate organizational learning. [source] The dual role of a loop with low loop contact distance in folding and domain swappingPROTEIN SCIENCE, Issue 7 2002Apichart Linhananta Abstract , helices, , strands, and loops are the basic building blocks of protein structure. The folding kinetics of , helices and , strands have been investigated extensively. However, little is known about the formation of loops. Experimental studies show that for some proteins, the formation of a single loop is the rate-determining step for folding, whereas for others, a loop (or turn) can misfold to serve as the hinge loop region for domain-swapped species. Computer simulations of an all-atom model of fragment B of Staphylococcal protein A found that the formation of a single loop initiates the dominant folding pathway. On the other hand, the stability analysis of intermediates suggests that the same loop is a likely candidate to serve as a hinge loop for domain swapping. To interpret the simulation result, we developed a simple structural parameter: the loop contact distance (LCD), or the sequence distance of contacting residues between a loop and the rest of the protein. The parameter is applied to a number of other proteins, including SH3 domains and prion protein. The results suggest that a locally interacting loop (low LCD) can either promote folding or serve as the hinge region for domain swapping. Thus, there is an intimate connection between folding and domain swapping, a possible cause of misfolding and aggregation. [source] Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward,reverse rotating impellerTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Masanori Yoshida Abstract For an unbaffled agitated vessel with an unsteadily forward,reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop,reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward,reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine-type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance. On a étudié l'écoulement liquide par visualisation et mesure en utilisant la vélocimétrie avec poursuite de trajectoire pour une cuve non compartimentée et agitée avec un agitateur rotatif avant-arrière non stable dont la rotation est composée de périodes répétées d'accélération, de ralentissement et d'arrêt-marche arrière. Un agitateur à six pales plates a été utilisé avec quatre réglages de hauteur différents. Le dégagement de l'agitateur et son cycle de rotation avant-arrière caractérisaient l'écoulement liquide dans la région de l'agitateur : l'écoulement radial vers l'extérieur dans le processus de décélération pour le dégagement le plus important par rapport au diamètre de la cuve de 1/3 et l'écoulement axial vers le bas dans le processus d'accélération pour le dégagement le plus petit par rapport au diamètre de la cuve de 1/8. Les modèles d'écoulement intérieurs de la cuve résultant du plus grand et du plus petit dégagements de l'agitateur ont été décrits, respectivement, par des doubles boucles et une simple boucle de circulation, ce qui ressemble au modèle produit par des agitateurs à hélice unidirectionnels. On a révélé que l'écoulement de sortie contenait un niveau comparable de vélocité périodique périphérique, indépendamment du dégagement de l'agitateur. [source] | |||||||||||||