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Sample records for atrioventricular nodal conduction

  1. Atrial activation during atrioventricular nodal reentrant tachycardia: studies on retrograde fast pathway conduction

    NARCIS (Netherlands)

    Katritsis, Demosthenes G.; Ellenbogen, Kenneth A.; Becker, Anton E.

    2006-01-01

    Detailed right and left septal mapping of retrograde atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) has not been undertaken and may provide insight into the complex physiology of AVNRT, especially the anatomic localization of the fast and slow pathways. The

  2. Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplantation.

    Science.gov (United States)

    Flyer, Jonathan N; Zuckerman, Warren A; Richmond, Marc E; Anderson, Brett R; Mendelsberg, Tamar G; McAllister, Jennie M; Liberman, Leonardo; Addonizio, Linda J; Silver, Eric S

    2017-06-20

    Supraventricular tachycardia is common after heart transplantation. Adenosine, the standard therapy for treating supraventricular tachycardia in children and adults without transplantation, is relatively contraindicated after transplantation because of a presumed risk of prolonged atrioventricular block in denervated hearts. This study tested whether adenosine caused prolonged asystole after transplantation and if it was effective in blocking atrioventricular nodal conduction in these patients. This was a single-center prospective clinical study including healthy heart transplant recipients 6 months to 25 years of age presenting for routine cardiac catheterization during 2015 to 2016. After catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose-escalation protocol until atrioventricular block was achieved. The incidence of clinically significant asystole (≥12 seconds after adenosine) was quantified. The effects of patient characteristics on adenosine dose required to produce atrioventricular block and duration of effect were also measured. Eighty patients completed adenosine testing. No patient (0%; 95% confidence interval, 0-3) required rescue ventricular pacing. Atrioventricular block was observed in 77 patients (96%; 95% confidence interval, 89-99). The median longest atrioventricular block was 1.9 seconds (interquartile range, 1.4-3.2 seconds), with a mean duration of adenosine effect of 4.3±2.0 seconds. No patient characteristic significantly predicted the adenosine dose to produce atrioventricular block or duration of effect. Results were similar across patient weight categories. Adenosine induces atrioventricular block in healthy pediatric and young adult heart transplant recipients with minimal risk when low initial doses are used (25 μg/kg; 1.5 mg if ≥60 kg) and therapy is gradually escalated. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02462941. © 2017 American Heart Association, Inc.

  3. Does the atrioventricular node conduct?

    NARCIS (Netherlands)

    Meijler, F.L.; Fisch, C.

    1989-01-01

    It is difficult to be certain wh en the term "conduction" was first applied to the transfer of atrial activation to the ventricles .' In 1894, Engelmann used the word "Leitung", which can be translated as "connection" or as "conduction" .2 In 1906, Tawara described the atrioventricular node,

  4. Dual Atrioventricular Nodal Pathways Physiology: A Review of Relevant Anatomy, Electrophysiology, and Electrocardiographic Manifestations

    Directory of Open Access Journals (Sweden)

    Bhalaghuru Chokkalingam Mani, MD

    2014-01-01

    Full Text Available More than half a century has passed since the concept of dual atrioventricular (AV nodal pathways physiology was conceived. Dual AV nodal pathways have been shown to be responsible for many clinical arrhythmia syndromes, most notably AV nodal reentrant tachycardia. Although there has been a considerable amount of research on this topic, the subject of dual AV nodal pathways physiology remains heavily debated and discussed. Despite advances in understanding arrhythmia mechanisms and the widespread use of invasive electrophysiologic studies, there is still disagreement on the anatomy and physiology of the AV node that is the basis of discontinuous antegrade AV conduction. The purpose of this paper is to review the concept of dual AV nodal pathways physiology and its varied electrocardiographic manifestations.

  5. Mechanism of polyuria and natriuresis in atrioventricular nodal tachycardia.

    Science.gov (United States)

    Canepa-Anson, R; Williams, M; Marshall, J; Mitsuoka, T; Lightman, S; Sutton, R

    1984-01-01

    A woman with tachycardia associated with polyuria was investigated. Electrophysiological analysis showed that the tachycardia was an atrioventricular nodal re-entrant tachycardia. Programmed stimulation was then used to provoke and sustain the tachycardia for 40 minutes. Polyuria, with an appreciable increase in free water clearance, was observed. This was associated with reduction in plasma and urinary arginine vasopressin concentrations. Appreciable natriuresis also developed. These results support the hypothesis that the polyuria with increased free water clearance and the natriuresis occurring during sustained tachycardia in man are due to inhibition of secretion of vasopressin and the release of natriuretic factor. PMID:6434116

  6. Modification of atrioventricular nodal electrophysiology by selective radiofrequency delivery on the anterior or posterior approaches.

    Science.gov (United States)

    Chorro, F J; Sanchis, J; Such, L; Artal, L; Llavador, J J; Llavador, E; Monmeneu, J V; López-Merino, V

    1997-05-01

    An analysis was made in 14 isolated and perfused rabbit hearts of the electrophysiological effects of selective radiofrequency (RF) delivery in the anterior (group I, n = 7) or posterior zone (group II, n = 7) of the Koch triangle, with the aim of modifying atrioventricular nodal (AVN) conduction without suppressing 1:1 transmission. After opening the right atrium, RF was delivered (0.5 W) with a 1-mm diameter unipolar electrode positioned in the selected zone until a prolongation of no less than 15% was obtained in the Wenckebach cycle length (WCL). Before and after (30 min) RF, anterograde and retrograde AVN refractoriness and conduction were evaluated, stimulating from the crista terminalis (CT), the interatrial septum (IAS), and from the RV epicardium. After RF, the following percentage increments were observed in group I: AH(CT) = 36% +/- 9%, AH(IAS) = 38% +/- 11%, WCL(CT) = 28% +/- 8%, WCL(IAS) = 22% +/- 6%, functional refractory period (FRP) of the AVN(CT) = 13% +/- 11%, FRP-AVN(IAS) = 13% +/- 8%, retrograde WCL = 20% +/- 19%, and retrograde FRPVA = 13% +/- 16%. The increments observed in group II and the significances of the differences with respect to group I were: AH(CT) = 11% +/- 14% (P IAS) = 19% +/- 32% (NS), WCL(CT) = 42% +/- 14% (P IAS) = 42% +/- 16% (P < 0.01), FRP-AVN(CT) = 28% +/- 28% (NS), FRP-AVN(LAS) = 21% +/- 19% (NS), retrograde WCL = 35% +/- 24% (NS), and retrograde FRP = 16% +/- 13% (NS). In both groups, the AH interval variations were not correlated with those of the rest of the parameters analyzed. Truncated nodal function curves suggestive of a dual AV nodal pathway were obtained in three experiments, though in only one of them was this observed under basal conditions. In the other two experiments, with dual AV nodal physiology only after RF (one from each group), AV nodal reentrant tachycardias were triggered with atrial extrastimulus at coupling intervals equal to or shorter than at those that cause a sudden lengthening of the AH

  7. [Parahisian atrial tachycardia or atrioventricular nodal reentrant tachycardia with tendon of Todaro breakthrough?].

    Science.gov (United States)

    Orczykowski, Michał; Jaworska-Wilczyńska, Maria; Urbanek, Piotr; Bodalski, Robert; Derejko, Paweł; Gajek, Jacek; Hryniewiecki, Tomasz; Szumowski, Lukasz; Walczak, Franciszek

    2010-08-01

    We present a case of a 61 year-old woman with tachycardia originating close to the His bundle where radiofrequency (RF) ablation may bear potential risk of atrioventricular (AV) block. In this case report we discuss the possibility of a AV nodal reciprocating tachycardia with tendon of Todaro breakthrough. Patient was safely and effectively treated with RF catheter ablation.

  8. Electrophysiological markers predicting impeding AV-block during ablation of atrioventricular nodal reentry tachycardia.

    Science.gov (United States)

    Fragakis, Nikolaos; Krexi, Lydia; Kyriakou, Panagiota; Sotiriadou, Melani; Lazaridis, Charalambos; Karamanolis, Athanasios; Dalampyras, Panagiotis; Tsakiroglou, Stelios; Skeberis, Vassilios; Tsalikakis, Dimitrios; Vassilikos, Vassilios

    2018-01-01

    Radiofrequency (RF) ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is occasionally complicated with atrioventricular block (AVB) often predicted by junctional beats (JB) with loss of ventriculo-atrial (VA) conduction. We analyzed retrospectively 153 patients undergoing ablation of SP for typical AVNRT. Patients were divided into two age groups: 127 ≤ 70 years and 26 > 70 years. We analyzed the interval between the atrial electrogram in the His-bundle position and the distal ablation catheter [A(H)-A(RFd)] and between the distal ablation catheter and the proximal coronary sinus catheter [A(RFd)-A(CS)] before RF applications with and without JB. We evaluated if these intervals can be used as predictors of JB incidence and also of JB with loss of VA conduction. We also assessed if age influences the risk of loss of VA conduction. The A(H)-A(RFd) and A(RFd)-A(CS) intervals were significantly shorter in RF applications causing JB than those without JB (33 ± 11 ms vs 39 ± 9 ms, P JB with VA block than those with VA conduction (29 ± 11 ms vs 35 ± 11 ms, P  70 years had shorter intervals (36 ± 11 ms vs 29 ± 8 ms, P  =  0.012, 17 ± 8 ms vs 13 ± 7 ms, P  =  0.027, respectively), while VA block was more common in this age group. The A(H)-A(RFd) and A(RFd)-A(CS) intervals can be used as markers for predicting JB occurrence as well as impending AVB. JB with loss of VA conduction occur more often in older patients possibly due to a higher position of SP. © 2017 Wiley Periodicals, Inc.

  9. Radiofrequency Catheter Ablation of Coexistent Idiopathic Left Ventricular Tachycardia and Atrioventricular Nodal Reentrant Tachycardia

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    Ken-Pen Weng

    2005-10-01

    Full Text Available A healthy 15-year-old male patient presented with a 6-month history of recurrent attacks of palpitations. On multiple emergency room visits, a sustained wide QRS complex tachycardia with a right bundle branch block and northwest axis deviation was documented. The tachycardia was not terminated by intravenous adenosine, but was suppressed with intravenous verapamil. There was no evidence of structural heart disease, myocarditis, long QT syndrome, or electrolyte imbalance after a series of standard examinations. Idiopathic left ventricular tachycardia (ILVT was suspected. Electrophysiologic studies revealed 2 inducible tachycardias, which were shown to represent atrioventricular nodal reentrant tachycardia (AVNRT and ILVT. Transformation from AVNRT to ILVT occurred spontaneously following atrial pacing. Successful ablation of ILVT and the slow atrioventricular nodal pathway resulted in cure of the double tachycardia.

  10. Effect of atrioventricular conduction on heart rate variability

    KAUST Repository

    Ahmad, Talha Jamal; Ali, Hussnain; Majeed, S. M Imran; Khan, Shoab A.

    2011-01-01

    This paper discusses the effect of atrioventricular conduction time (AVCT) on the short-term Heart Rate Variability (HRV) by computing HRV parameters using intervals between the onsets of successive P waves (PP time series) for three groups: normal

  11. Familial atrioventricular nodal re-entrant tachycardia: A case seriers and a systematic review

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    Muthiah Subramanian

    2017-11-01

    Full Text Available Multiple reports of familial clustering suggest that genetic factors may contribute in the pathogenesis of atrioventricular nodal re-entrant tachycardia (AVNRT. We report three cases of AVNRT in a father and his two sons along with a review of literature of other similar cases. Electrophysiological studies induced typical AVNRT, which was successfully eliminated by radiofrequency ablation in all of them. Of the 22 reported cases, 96% had typical (slow-fast variant of AVNRT. The predominant pattern of inheritance appears to be autosomal dominant, though other patterns may exist. Further research is needed to understand the genetic influence of AVNRT and its pathophysiology. Keywords: Familial, AVNRT, Tachycardia

  12. Atrioventricular conduction after alcohol septal ablation for obstructive hypertrophic cardiomyopathy

    DEFF Research Database (Denmark)

    Axelsson, Anna; Weibring, Kristina; Havndrup, Ole

    2014-01-01

    .1-9.4) after ASA. Patients with high-grade atrioventricular block at follow-up had longer PR intervals at baseline [205 ms (200-230)] than the rest of the cohort [180 ms (140-200), P = 0.004] and a higher incidence of acute complete heart block (63 vs. 15%; P = 0.007) during ASA. A PR interval of at least 200...... ms at baseline was associated with higher prevalence of high-grade atrioventricular block at follow-up (30 vs. 2%; P = 0.0013). The incidence of late-onset complete heart block was 1.5% per year after ASA. CONCLUSION: We found normalized atrioventricular conduction at long-term follow-up, suggesting...... recovery in 6 of 14 patients with a pacemaker implanted in relation to ASA. Permanent atrioventricular conduction abnormalities were associated with baseline PR intervals of at least 200 ms and acute persistent complete heart block during ASA....

  13. A case of typical atrioventricular nodal (AVN) reentrant tachycardia confined to the compact AV node, showing a variety of rare electrophysiological findings, including eccentric AVN echoes

    OpenAIRE

    Tanaka, Kazushi; Shiotani, Shinji; Fukuda, Keisuke; Fujihara, Masahiko; Higashimori, Akihiro; Morioka, Nobuyuki; Yokoi, Yoshiaki; Fujimura, Osamu

    2014-01-01

    Herein, we report the case of a 49-year-old woman with typical atrioventricular nodal (AVN) reentrant tachycardia, confined to the compact atrioventricular node, showing numerous rare electrophysiological findings such as unique AVN reentrant echoes, double ventricular responses, latent retrograde dual AVN pathways, antegrade triple AVN pathways, and longitudinal dissociation within the lower final common pathway.

  14. A case of typical atrioventricular nodal (AVN reentrant tachycardia confined to the compact AV node, showing a variety of rare electrophysiological findings, including eccentric AVN echoes

    Directory of Open Access Journals (Sweden)

    Kazushi Tanaka, M.D., Ph.D.

    2014-12-01

    Full Text Available Herein, we report the case of a 49-year-old woman with typical atrioventricular nodal (AVN reentrant tachycardia, confined to the compact atrioventricular node, showing numerous rare electrophysiological findings such as unique AVN reentrant echoes, double ventricular responses, latent retrograde dual AVN pathways, antegrade triple AVN pathways, and longitudinal dissociation within the lower final common pathway.

  15. Atrioventricular conduction abnormality and hyperchloremic metabolic acidosis in toluene sniffing

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    Jian-Hsiung Tsao

    2011-10-01

    Full Text Available Toluene is an aromatic hydrocarbon with widespread industrial use as an organic solvent. As a result of the euphoric effect and availability of these substances, inhalation of toluene-based products is popular among young adults and children. Chronic or acute exposure is known to cause acid–base and electrolyte disorders, and to be toxic to the nervous and hematopoietic systems. We report a 38-year-old man who suffered from general muscular weakness of all extremities after toluene sniffing, which was complicated with hypokalemic paralysis, atrioventricular conduction abnormality, and normal anion gap hyperchloremic metabolic acidosis. Renal function, serum potassium and acid–base status normalized within 3 days after aggressive potassium chloride and intravenous fluid replacement. Electrocardiography showed regression of first-degree atrioventricular block. Exposure to toluene can lead to cardiac arrhythmias and sudden sniffing death syndrome. Tachyarrhythmia is the classical manifestation of toluene cardiotoxicity. Atrioventricular conduction abnormalities have been rarely mentioned in the literature. Knowledge of the toxicology and medical complications associated with toluene sniffing is essential for clinical management of these patients.

  16. Successful radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in a patient with dextrocardia due to unilateral pulmonary agenesis: a case report

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    Aksu T

    2015-02-01

    Full Text Available Tolga Aksu, Tumer Erdem Guler, Ebru Golcuk, Ismail Erden, Kazim Serhan Ozcan Department of Cardiology, Kocaeli Derince Education and Research Hospital, Derince, Kocaeli, Turkey Abstract: Radiofrequency catheter ablation of the slow pathway is considered to be the treatment of choice for patients with atrioventricular nodal reentrant tachycardia. We report a 34-year-old female with mirror image dextrocardia due to unilateral pulmonary agenesis who underwent successful slow pathway ablation for typical atrioventricular nodal reentrant tachycardia. Using contrast injection, cardiac anatomy was identified in a short time and successfully ablated. Keywords: dextrocardia, AVNRT, ablation, pulmonary agenesis

  17. Effect of atrioventricular conduction on heart rate variability

    KAUST Repository

    Ahmad, Talha Jamal

    2011-08-01

    This paper discusses the effect of atrioventricular conduction time (AVCT) on the short-term Heart Rate Variability (HRV) by computing HRV parameters using intervals between the onsets of successive P waves (PP time series) for three groups: normal, arrhythmia and sudden cardiac death (SCD) patients. A very precise wavelet transform based ECG delineator was developed to detect PP, PR and RR time series. Mean PR variation in arrhythmia and SCD group was found to be significantly high as compared to the normal group. It was observed that when PR variations in arrhythmia and SCD cases crossed a certain threshold, RR variability no longer provided a very accurate estimate of HRV. In such cases, PP variability was able to provide a better assessment of HRV. © 2011 IEEE.

  18. Acidosis slows electrical conduction through the atrio-ventricular node.

    Science.gov (United States)

    Nisbet, Ashley M; Burton, Francis L; Walker, Nicola L; Craig, Margaret A; Cheng, Hongwei; Hancox, Jules C; Orchard, Clive H; Smith, Godfrey L

    2014-01-01

    Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

  19. Acidosis slows electrical conduction through the atrio-ventricular node

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    Ashley Muir Nisbet

    2014-06-01

    Full Text Available Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN. In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode’s solution (20% CO2, pH 6.7 increased the time of earliest activation (Tact from 100.5+7.9 to 166.1+7.2ms (n=8 at a pacing cycle length (PCL of 300ms (37oC. Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150ms PCL, Tact was prolonged from 131.0+5.2 to 174.9+16.3ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode’s solutions at pH 7.4 (control, 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH interval, the effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

  20. O efeito da morfina na inibição vagal do coração: demonstração da dupla via do nodo atrioventricular - DOI: 10.4025/actascihealthsci.v28i2.1102 The effect of morphine on vagal inhibition of the heart: demonstration of dual atrioventricular nodal pathways - DOI: 10.4025/actascihealthsci.v28i2.1102

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    José Geraldo Pereira da Cruz

    2006-03-01

    Full Text Available A estimulação elétrica do nervo vago diminui a freqüência cardíaca e aumenta o intervalo PQ no eletrocardiograma, podendo ativar a via anterógrada do nodo atrioventricular. Neste experimento é investigada a interação da morfina sobre o controle nervoso parassimpático cardíaco em relação à dupla condução do nodo atrioventricular. A estimulação do nervo vago induz uma significativa bradicardia e um bloqueio atrioventricular de terceiro grau, com a onda P aparecendo negativa na derivação II. Devido aos efeitos moduladores da anestesia sobre o coração, administração de injeções de morfina induz o aparecimento de onda P positiva através de uma ação inibitória sobre a reentrância do nodo atrioventricular. Tudo sugere a presença de duas vias atrioventriculares, anatômica e funcionalmente distintasThat electrical stimulation of the vagus decreased heart rate and increased the PQ interval in electrocardiogram, consistent with anterograde dual atriventricular conduction. The present experiments were investigating the interaction of the morphine with cardiac parasympathetic nervous control in dual atrioventricular node. Electrical stimulation of the vagus nerve induced significant bradycardia and of third degree atrioventricular block and the P wave appearance was negative in leads II. Because background anesthesia modulates the heart, administered morphine injection the P waves appearance was positive through one inhibitory action on atrioventricular nodal reentry. All suggest the presence of two functionally and anatomically distinct atrioventricular pathways

  1. Outcome of slow pathway modulation for atrioventricular nodal reentrant tachycardia with 50 versus 30 watts-more power, more effect?

    Science.gov (United States)

    Dechering, Dirk G; Schleberger, Ruben; Greiser, Eva; Dickow, Jannis; Koebe, Julia; Frommeyer, Gerrit; Willems, Stephan; Eckardt, Lars; Hoffmann, Boris A; Wasmer, Kristina

    2018-03-19

    Slow pathway modulation is the treatment of choice in patients with atrioventricular nodal reentrant tachycardia (AVNRT). No comparative data on ablation strategies exist. Therefore, we sought to compare two common ablation approaches. We analyzed prospective ablation databases of two high-volume tertiary centers (> 1000 ablations/year) using either 30 or 50 W for slow pathway modulation from 2012 to 2013. We analyzed procedural characteristics as well as short- and long-term outcomes. Mean follow-up was 36 ± 9 months. Six hundred thirty-four patients (50 W center: n = 342, 30 W center: n = 292) were ablated. Slow pathway modulation was successful in 99% in both groups (p = ns). Periprocedural AV block occurred in nine patients (2.6%) in the 50 W and five patients (1.7%) in the 30 W group (p = 0.59), respectively. We documented no permanent higher-degree AV block. The number of RF lesions and seconds of RF delivery was significantly less in the 50 W group (p = 0.04 for number of lesions; p modulation are highly effective and safe. Significantly, fewer RF duration was necessary to modulate the slow pathway with higher power output (50 W). Our subgroup analysis suggests that males and females might benefit most from different modulation approaches.

  2. The anatomy and histology of the atrioventricular conducting system in the hedgehog (Hemiechinus auritus) heart

    OpenAIRE

    NABIPOUR, Abolghasem

    2014-01-01

    This study examined the atrioventricular conducting system in 4 adult male hedgehogs (Hemiechinus auritus). The histological structure of these components was studied using routine histological methods. The AVN was located at the lower and anterior part of the interatrial septum, near the root of the aorta. It was almost oval and consisted of twisted cells. Internodal pathways in the hedgehog heart were not observed, but there were numerous purkinje-like fibers within the myocardium of the at...

  3. Effects of calcium, calcium entry blockers and calmodulin inhibitors on atrioventricular conduction disturbances induced by hypoxia.

    OpenAIRE

    Anno, T.; Kodama, I.; Shibata, S.; Toyama, J.; Yamada, K.

    1986-01-01

    Effects of hypoxia on atrioventricular conduction were investigated in the Langendorff-perfused isolated heart of the rabbit with various extracellular calcium concentrations ([Ca2+]) as well as in the presence of verapamil, nifedipine, N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) and chlorpromazine. The prolongation of the atrio-His (AH) interval by hypoxia for 7 min was greater with increasing [Ca2+]o ranging from 1.2 to 5.2 mM. At [Ca2+]o of over 3.2 mM under hypoxic condition...

  4. Origem das artérias dos nós sinoatrial e atrioventricular em população do sul da Índia: um estudo angiográfico Origen de las arterias de los nódulos sinusal y atrioventricular en población del Sur de la India: un estudio angiográfico Origin of the sinoatrial and atrioventricular nodal arteries in South Indians: an angiographic study

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    Lakshmi Ramanathan

    2009-05-01

    masculino; edad promedio, 55 años, habitantes de la región costera al Sur de la India, sometidos a cineangiocoronariografía debido a síntomas como dolor en el pecho, angina pectoris o test ergométrico positivo. Las angiografías incluyeron ambas arterias coronarias (derecha e izquierda en posición oblicua anterior derecha e izquierda. El origen de la AnSA y AnAV a partir de las arterias coronarias se observó y se correlacionó con la dominancia arterial. RESULTADOS: El nódulo SA (sinusal recibió suministro por la arteria coronaria derecha (ACD en el 53% de los casos, por la rama circunfleja (Cx de la arteria coronaria izquierda (ACI en el 42,66% de los casos, y en el 4,33% de los casos este nódulo fue irrigado por ambas arterias coronarias. El nódulo AV (atrioventricular también recibió suministro sanguíneo con más frecuencia de la ACD (72,33% de los casos que la rama Cx de la ACI (27,66%. Sorprendentemente, en ningún caso este nódulo recibió suministro de ambas arterias coronarias. CONCLUSIÓN: Los resultados del presente estudio pueden auxiliar a los cirujanos cardíacos, sobre todo en cirugías relacionadas a valvulopatías, debido a la franca proximidad entre las ramas nodales y el complejo valvular.BACKGROUND: To study the arterial supply of the conducting system and its correlation with the dominance of the coronary arteries in the South Indian population. OBJECTIVE: To determine angiographically the origins of the sinoatrial nodal artery (SAna and atrioventricular nodal artery (AVna in Indians. METHODS: The study included 300 consecutive patients (114 females, 186 males; mean age, 55 years living in the southern coastal region of India, who underwent coronary angiography either for the symptoms of chest pain, angina pectoris or positive Treadmill Test. The angiograms contained both coronary arteries (right and left in the right and left anterior oblique position. The origin of SAna and AVna from the coronary arteries was observed and correlated with

  5. Surgical anatomy of the atrioventricular conduction bundle in anomalous muscle bundle of the right ventricle with subarterial ventricular septal defect

    NARCIS (Netherlands)

    Kurosawa, H.; Becker, A. E.

    1985-01-01

    A stillborn baby girl was found to have an anomalous muscle bundle of the right ventricle, associated with a doubly committed subarterial ventricular septal defect. The latter was separated from the area of the atrioventricular conduction bundle by muscle. Serial histologic sectioning of the

  6. Zero-fluoroscopy cryothermal ablation of atrioventricular nodal re-entry tachycardia guided by endovascular and endocardial catheter visualization using intracardiac echocardiography (Ice&ICE Trial).

    Science.gov (United States)

    Luani, Blerim; Zrenner, Bernhard; Basho, Maksim; Genz, Conrad; Rauwolf, Thomas; Tanev, Ivan; Schmeisser, Alexander; Braun-Dullaeus, Rüdiger C

    2018-01-01

    Stochastic damage of the ionizing radiation to both patients and medical staff is a drawback of fluoroscopic guidance during catheter ablation of cardiac arrhythmias. Therefore, emerging zero-fluoroscopy catheter-guidance techniques are of great interest. We investigated, in a prospective pilot study, the feasibility and safety of the cryothermal (CA) slow-pathway ablation in patients with symptomatic atrioventricular-nodal-re-entry-tachycardia (AVNRT) using solely intracardiac echocardiography (ICE) for endovascular and endocardial catheter visualization. Twenty-five consecutive patients (mean age 55.6 ± 12.0 years, 17 female) with ECG-documentation or symptoms suggesting AVNRT underwent an electrophysiology study (EPS) in our laboratory utilizing ICE for catheter navigation. Supraventricular tachycardia was inducible in 23 (92%) patients; AVNRT was confirmed by appropriate stimulation maneuvers in 20 (80%) patients. All EPS in the AVNRT subgroup could be accomplished without need for fluoroscopy, relying solely on ICE-guidance. CA guided by anatomical location and slow-pathway potentials was successful in all patients, median cryo-mappings = 6 (IQR:3-10), median cryo-ablations = 2 (IQR:1-3). Fluoroscopy was used to facilitate the trans-septal puncture and localization of the ablation substrate in the remaining 3 patients (one focal atrial tachycardia and two atrioventricular-re-entry-tachycardias). Mean EPS duration in the AVNRT subgroup was 99.8 ± 39.6 minutes, ICE guided catheter placement 11.9 ± 5.8 minutes, time needed for diagnostic evaluation 27.1 ± 10.8 minutes, and cryo-application duration 26.3 ± 30.8 minutes. ICE-guided zero-fluoroscopy CA in AVNRT patients is feasible and safe. Real-time visualization of the true endovascular borders and cardiac structures allow for safe catheter navigation during the ICE-guided EPS and might be an alternative to visualization technologies using geometry reconstructions. © 2017 Wiley Periodicals, Inc.

  7. Evolution and scaling of atrioventricular conduction time in mammals. [Pt. 1

    NARCIS (Netherlands)

    Meijler, F.L.; Strackee, J.

    2006-01-01

    Scaling can be defined as the adjustment of a structure, a function, or an organ to the size of the mammalian body. An example is the size of the heart in relation to the size of the body. The duration of the PR interval on the electrocardiogram (atrioventricular delay) in relation to the size of

  8. Letter by Gourdie and Sedmera regarding article, "Abnormal conduction and morphology in the atrioventricular node of mice with atrioventricular canal-targeted deletion of Alk3/Bmpr1a receptor"

    Czech Academy of Sciences Publication Activity Database

    Gourdie, R. G.; Sedmera, David

    2008-01-01

    Roč. 118, - (2008), e106-e106 ISSN 0009-7322 Institutional research plan: CEZ:AV0Z50450515 Keywords : conduction system * heart development * atrioventricular canal Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 14.595, year: 2008

  9. Optical conductivity of three and two dimensional topological nodal-line semimetals

    Science.gov (United States)

    Barati, Shahin; Abedinpour, Saeed H.

    2017-10-01

    The peculiar shape of the Fermi surface of topological nodal-line semimetals at low carrier concentrations results in their unusual optical and transport properties. We analytically investigate the linear optical responses of three- and two-dimensional nodal-line semimetals using the Kubo formula. The optical conductivity of a three-dimensional nodal-line semimetal is anisotropic. Along the axial direction (i.e., the direction perpendicular to the nodal-ring plane), the Drude weight has a linear dependence on the chemical potential at both low and high carrier dopings. For the radial direction (i.e., the direction parallel to the nodal-ring plane), this dependence changes from linear into quadratic in the transition from low into high carrier concentration. The interband contribution into optical conductivity is also anisotropic. In particular, at large frequencies, it saturates to a constant value for the axial direction and linearly increases with frequency along the radial direction. In two-dimensional nodal-line semimetals, no interband optical transition could be induced and the only contribution to the optical conductivity arises from the intraband excitations. The corresponding Drude weight is independent of the carrier density at low carrier concentrations and linearly increases with chemical potential at high carrier doping.

  10. Transcription factor Tbx3 is required for the specification of the atrioventricular conduction system

    NARCIS (Netherlands)

    Bakker, Martijn L.; Boukens, Bastiaan J.; Mommersteeg, Mathilda T. M.; Brons, Janynke F.; Wakker, Vincent; Moorman, Antoon F. M.; Christoffels, Vincent M.

    2008-01-01

    The cardiac conduction system consists of distinctive heart muscle cells that initiate and propagate the electric impulse required for coordinated contraction. The conduction system expresses the transcriptional repressor Tbx3, which is required for vertebrate development and controls the formation

  11. Multicenter, randomized comparison between magnetically navigated and manually guided radiofrequency ablation of atrioventricular nodal reentrant tachycardia (the MagMa-AVNRT-trial).

    Science.gov (United States)

    Reents, Tilko; Jilek, Clemens; Schuster, Peter; Nölker, Georg; Koch-Büttner, Katharina; Ammar-Busch, Sonia; Semmler, Verena; Bourier, Felix; Kottmaier, Marc; Kornmayer, Marie; Brooks, Stephanie; Fichtner, Stephanie; Kolb, Christof; Deisenhofer, Isabel; Hessling, Gabriele

    2017-12-01

    Remote magnetic navigation (RMN) is attributed to diminish radiation exposure for both patient and operator performing catheter ablation for different arrhythmia substrates. The purpose of this prospective, randomized study was to compare RMN with manually guided catheter ablation for AV nodal reentrant tachycardia (AVNRT) regarding fluoroscopy time/dosage, acute and long-term efficacy as well as safety. A total of 218 patients with AVNRT undergoing catheter ablation at three centers (male 34%, mean age 50 ± 17 years) were randomized to a manual approach (n = 113) or RMN (n = 105) using the Niobe ® magnetic navigation system. The primary study endpoint was total fluoroscopy time/dosage for patient and operator at the end of the procedure. Secondary endpoints included acute success, procedure duration, complications and success rate after 6 months. Fluoroscopy time and dosage for the patient were significantly reduced in the RMN group compared to the manual group (6 ± 6 vs. 11 ± 10 min; p < 0.001 and 425 ± 558 vs. 751 ± 900 cGycm 2 , p = 0.002). A reduction in fluoroscopy time/dose also applied to the operator (3 ± 5 vs. 7 ± 9 min 209 ± 444 vs. 482 ± 689 cGycm 2 , p < 0.001). Procedure duration was significantly longer in the RMN group (88 ± 29 vs. 79 ± 29 min; p = 0.03) and crossover from the RMN group to manual ablation occurred in 7.6% of patients (7.6 vs. 0.1%; p = 0.02). Acute success was achieved in 100% of patients in both groups. Midterm success after 6 months was 97 vs. 98% (p = 0.67). No complications occurred in both groups. The use of RMN for catheter ablation of AVNRT compared to a manual approach results in a reduction of fluoroscopy time and dosage of about 50% for both patients and physicians. Acute and midterm success and safety are comparable. RMN is a good alternative to a manual approach for AVNRT ablation.

  12. Reversible chronic acquired complete atrioventricular block.

    Science.gov (United States)

    Rakovec, P; Milcinski, G; Voga, G; Korsic, L

    1982-01-01

    The return of atrioventricular conduction is reported in a case after nearly four years of complete acquired heart block. After recovery from atrioventricular block, right bundle branch block persisted, but P-R interval and H-V interval were normal. Three months later a relapse of second degree infranodal atrioventricular block was noted. A short review of similar cases from the literature is given.

  13. Catheter ablation as a treatment of atrioventricular block.

    Science.gov (United States)

    Tuohy, Stephen; Saliba, Walid; Pai, Manjunath; Tchou, Patrick

    2018-01-01

    Symptomatic second-degree atrioventricular (AV) block is typically treated by implantation of a pacemaker. An otherwise healthy AV conduction system can nevertheless develop AV block due to interference from junctional extrasystoles. When present with a high burden, these can produce debilitating symptoms from AV block despite an underlying normal AV node and His-Purkinje system properties. The purpose of this study was to describe a catheter ablation approach for alleviating symptomatic AV block due to a ventricular nodal pathway interfering with AV conduction. Common clinical monitoring techniques such as Holter and event recorders were used. Standard electrophysiological study techniques using multipolar recording and ablation catheters were utilized during procedures. A 55-year-old woman presented with highly symptomatic, high-burden second-degree AV block due to concealed and manifest junctional premature beats. Electrophysiological characteristics indicated interference of AV conduction due to a concealed ventricular nodal pathway as the cause of the AV block. The patient's AV nodal and His-Purkinje system conduction characteristics were otherwise normal. Radiofrequency catheter ablation of the pathway was successful in restoring normal AV conduction and eliminating her clinical symptoms. Pathways inserting into the AV junction can interfere with AV conduction. When present at a high burden, this type of AV block can be highly symptomatic. Catheter ablation techniques can be used to alleviate this type of AV block and restore normal AV conduction. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  14. Anatomy of the human atrioventricular junctions revisited

    NARCIS (Netherlands)

    Anderson, R. H.; Ho, S. Y.; Becker, A. E.

    2000-01-01

    There have been suggestions made recently that our understanding of the atrioventricular junctions of the heart is less than adequate, with claims for several new findings concerning the arrangement of the ordinary working myocardium and the specialised pathways for atrioventricular conduction. In

  15. Analysis of Onset Mechanisms of a Sphingosine 1-Phosphate Receptor Modulator Fingolimod-Induced Atrioventricular Conduction Block and QT-Interval Prolongation

    International Nuclear Information System (INIS)

    Yagi, Yukihiro; Nakamura, Yuji; Kitahara, Ken; Harada, Takuma; Kato, Kazuhiko; Ninomiya, Tomohisa; Cao, Xin; Ohara, Hiroshi; Izumi-Nakaseko, Hiroko; Suzuki, Kokichi; Ando, Kentaro

    2014-01-01

    Fingolimod, a sphingosine 1-phosphate (S1P) receptor subtype 1, 3, 4 and 5 modulator, has been used for the treatment of patients with relapsing forms of multiple sclerosis, but atrioventricular conduction block and/or QT-interval prolongation have been reported in some patients after the first dose. In this study, we directly compared the electropharmacological profiles of fingolimod with those of siponimod, a modulator of sphingosine 1-phosphate receptor subtype 1 and 5, using in vivo guinea-pig model and in vitro human ether-a-go-go-related gene (hERG) assay to better understand the onset mechanisms of the clinically observed adverse events. Fingolimod (0.01 and 0.1 mg/kg) or siponimod (0.001 and 0.01 mg/kg) was intravenously infused over 10 min to the halothane-anaesthetized guinea pigs (n = 4), whereas the effects of fingolimod (1 μmol/L) and siponimod (1 μmol/L) on hERG current were examined (n = 3). The high doses of fingolimod and siponimod induced atrioventricular conduction block, whereas the low dose of siponimod prolonged PR interval, which was not observed by that of fingolimod. The high dose of fingolimod prolonged QT interval, which was not observed by either dose of siponimod. Meanwhile, fingolimod significantly inhibited hERG current, which was not observed by siponimod. These results suggest that S1P receptor subtype 1 in the heart could be one of the candidates for fingolimod- and siponimod-induced atrioventricular conduction block since S1P receptor subtype 5 is localized at the brain, and that direct I Kr inhibition may play a key role in fingolimod-induced QT-interval prolongation. - Highlights: • Fingolimod and siponimod are S1P 1,3,4,5 and S1P 1,5 receptor modulators, respectively. • Fingolimod and siponimod induced AV block in the halothane-anesthetized guinea pigs. • S1P 1 in the hearts may be the target of fingolimod- and siponimod-induced AV block. • Fingolimod directly inhibited hERG current, which was not observed by

  16. Analysis of Onset Mechanisms of a Sphingosine 1-Phosphate Receptor Modulator Fingolimod-Induced Atrioventricular Conduction Block and QT-Interval Prolongation

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Yukihiro [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Pharmaceutical Research Center, Meiji Seika Pharma Co., Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama, Kanagawa 222–8567 (Japan); Nakamura, Yuji [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Kitahara, Ken [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Division of Cardiovascular Medicine, Department of Internal Medicine, Faculty of Medicine, Toho University, 6-11-1 Omori-nishi, Ota-ku, Tokyo 143–8541 (Japan); Harada, Takuma [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Kato, Kazuhiko; Ninomiya, Tomohisa [Pharmaceutical Research Center, Meiji Seika Pharma Co., Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama, Kanagawa 222–8567 (Japan); Cao, Xin [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Ohara, Hiroshi [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Division of Cardiovascular Medicine, Department of Internal Medicine, Faculty of Medicine, Toho University, 6-11-1 Omori-nishi, Ota-ku, Tokyo 143–8541 (Japan); Izumi-Nakaseko, Hiroko [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); Suzuki, Kokichi [Pharmaceutical Research Center, Meiji Seika Pharma Co., Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama, Kanagawa 222–8567 (Japan); Ando, Kentaro [Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143–8540 (Japan); and others

    2014-11-15

    Fingolimod, a sphingosine 1-phosphate (S1P) receptor subtype 1, 3, 4 and 5 modulator, has been used for the treatment of patients with relapsing forms of multiple sclerosis, but atrioventricular conduction block and/or QT-interval prolongation have been reported in some patients after the first dose. In this study, we directly compared the electropharmacological profiles of fingolimod with those of siponimod, a modulator of sphingosine 1-phosphate receptor subtype 1 and 5, using in vivo guinea-pig model and in vitro human ether-a-go-go-related gene (hERG) assay to better understand the onset mechanisms of the clinically observed adverse events. Fingolimod (0.01 and 0.1 mg/kg) or siponimod (0.001 and 0.01 mg/kg) was intravenously infused over 10 min to the halothane-anaesthetized guinea pigs (n = 4), whereas the effects of fingolimod (1 μmol/L) and siponimod (1 μmol/L) on hERG current were examined (n = 3). The high doses of fingolimod and siponimod induced atrioventricular conduction block, whereas the low dose of siponimod prolonged PR interval, which was not observed by that of fingolimod. The high dose of fingolimod prolonged QT interval, which was not observed by either dose of siponimod. Meanwhile, fingolimod significantly inhibited hERG current, which was not observed by siponimod. These results suggest that S1P receptor subtype 1 in the heart could be one of the candidates for fingolimod- and siponimod-induced atrioventricular conduction block since S1P receptor subtype 5 is localized at the brain, and that direct I{sub Kr} inhibition may play a key role in fingolimod-induced QT-interval prolongation. - Highlights: • Fingolimod and siponimod are S1P{sub 1,3,4,5} and S1P{sub 1,5} receptor modulators, respectively. • Fingolimod and siponimod induced AV block in the halothane-anesthetized guinea pigs. • S1P{sub 1} in the hearts may be the target of fingolimod- and siponimod-induced AV block. • Fingolimod directly inhibited hERG current, which was not

  17. Solving two-dimensions heat conduction problem for fuel elements in reactor by nodal green's function method

    International Nuclear Information System (INIS)

    Tang Jian; Peng Muzhang; Cao Dongxing

    1989-01-01

    A new numerical method-nodal green's function method is used for solving heat conduction function. A heat conduction problem in cylindrical geometry with axial conduction is solved in this paper. The Kirchhoff transformation is used to deal with the problem with temperature dependent conductivity. Therefor, the calculation for the function is simplified. On the basis of the formulas developed, the code named NGMEFC is programmed. A sample problem which has been calculated by the code COBRA-IV is chosen as checking. A good agreement between both codes is achieved. The calculation shows that the calculation efficiency of the nodel green's function method is much higher than that of finite difference method

  18. Worsening atrioventricular conduction after hospital discharge in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: the HORIZONS-AMI trial.

    Science.gov (United States)

    Kosmidou, Ioanna; Redfors, Björn; McAndrew, Thomas; Embacher, Monica; Mehran, Roxana; Dizon, José M; Ben-Yehuda, Ori; Mintz, Gary S; Stone, Gregg W

    2017-11-01

    The chronic effects of ST-segment elevation myocardial infarction (STEMI) on the atrioventricular conduction (AVC) system have not been elucidated. This study aimed to evaluate the incidence, predictors, and outcomes of worsened AVC post-STEMI in patients treated with a primary percutaneous coronary intervention (PCI). The current analysis included patients from the HORIZONS-AMI trial who underwent primary PCI and had available ECGs. Patients with high-grade atrioventricular block or pacemaker implant at baseline were excluded. Analysis of ECGs excluding the acute hospitalization period indicated worsened AVC in 131 patients (worsened AVC group) and stable AVC in 2833 patients (stable AVC group). Patients with worsened AVC were older, had a higher frequency of hypertension, diabetes, renal insufficiency, previous coronary artery bypass grafting, and predominant left anterior descending culprit lesions. Predictors of worsened AVC included age, hypertension, and previous history of coronary artery disease. Worsened AVC was associated with an increased rate of all-cause death and major adverse cardiac events (death, myocardial infarction, ischemic target vessel revascularization, and stroke) as well as death or reinfarction at 3 years. On multivariable analysis, worsened AVC remained an independent predictor of all-cause death (hazard ratio: 2.005, confidence interval: 1.051-3.827, P=0.0348) and major adverse cardiac events (hazard ratio 1.542, confidence interval: 1.059-2.244, P=0.0238). Progression of AVC system disease in patients with STEMI treated with primary PCI is uncommon, occurs primarily in the setting of anterior myocardial infarction, and portends a high risk for death and major adverse cardiac events.

  19. Atrial flutter with spontaneous 1:1 atrioventricular conduction in adults: an uncommon but frequently missed cause for syncope/presyncope.

    Science.gov (United States)

    Turitto, Gioia; Akhrass, Philippe; Leonardi, Marino; Saponieri, Cesare; Sette, Antonella; El-Sherif, Nabil

    2009-01-01

    To compare patients with atrial flutter (AFl) and 1:1 atrioventricular conduction (AVC) with patients with AFl and higher AVC. The characteristics of 19 patients with AFl and 1:1 AVC (group A) were compared with those of 116 consecutive patients with AFl and 2:1 AVC or higher degree AV block (group B). Age, gender, and left ventricular function were similar in the two groups. In group A versus group B, more patients had no structural heart disease (42% vs 17%, P AVC or vice versa was associated with small but definite changes in AFl CL, which showed larger variations in response to sympathetic stimulation. In group A patients who were studied off drugs, the atrial-His interval was not different from group B, but maximal atrial pacing rate with 1:1 AVC was faster. In group A, five patients were misdiagnosed as ventricular tachyarrhythmias, and three with a defibrillator received inappropriate shocks. Four patients had ablation of AVC and six had ablation of AFl circuit. The main difference between groups A and B may be an inherent capacity of the AV node for faster conduction, especially in response to increased sympathetic tone. The latter affects not only AVC but also the AFl CL. One should be aware of the different presentations of AFl with 1:1 AVC to avoid misdiagnosis/mismanagement and to consider the diagnosis in patients with narrow or wide QRS tachycardia and rates above 220/min.

  20. Atrioventricular Pacemaker Lead Reversal

    Directory of Open Access Journals (Sweden)

    Mehmet K Aktas, MD

    2007-01-01

    Full Text Available During cardiac surgery temporary epicardial atrial and ventricular leads are placed in case cardiac pacing is required postoperatively. We present the first reported series of patients with reversal of atrioventricular electrodes in the temporary pacemaker without any consequent deleterious hemodynamic effect. We review the electrocardiographic findings and discuss the findings that lead to the discovery of atrioventricular lead reversal.

  1. Morfologia da junção atrioventricular em Iguana iguana (Reptilia-Iguanidae

    Directory of Open Access Journals (Sweden)

    Sonia Regina Jurado

    2006-06-01

    Full Text Available The atrioventricular junctional area (AVJA, including atrioventricular (AV node and bundle was investigated in seven hearts of common or green iguana (Iguana iguana using the light microscopy. Adult animals, both sexes, were captured in the Pantanal, Brazil. All hearts were fixed in buffered formaldehyde 10% (pH 7.2 for 24 hours, embedded in paraplast according to routine methods, and serially cut at 5 µm thickness. In the Iguana iguana, the AVJA consists of a mass of the fibers intermingled with variable amount of connective tissue and blood vessels surrounded by adjacent myocardium and the attachment of the right atrioventricular valve in the fibrous skeleton. By light microscopy, conducting cells of the AV node and bundle can be distinguished from working cells by their much smaller size, paler staining reaction and the presence of a sheath of connective tissue. The AV node and bundle and its branches were found to constitute a continuous tract. Histochemically, we found elastic fibers between cells of the conduction, mainly in the AV node. The PAS method reveals absence of glycogen in specialized cells. The fibrous skeleton, mainly the right trigone, showed a well-developed chondroid tissue, made by hyaline like cartilage (binucleated condrocytes included in the big lacunas and extracellular matrix with fibrillar collagen. In conclusion, the nodal and Purkinje cells in heart iguana presented poorly morphological differentiation comparing mammals and birds, however the skeleton fibrous has a different cartilage kind.

  2. Congenital Complete Atrioventricular Block : Clinical and Experimental Studies

    NARCIS (Netherlands)

    Blank, A.C.

    2014-01-01

    Complete atrioventricular block (CAVB) is a cardiac conduction defect wherein the trans¬mission of the normal electrical impulse from the atria to the ventricle is interrupted due to structural or functional impairment of the atrioventricular (AV) conduction system. If CAVB is diagnosed in utero or

  3. Prolongation of atrio-ventricular node conduction in a rabbit model of ischaemic cardiomyopathy: Role of fibrosis and connexin remodelling.

    Science.gov (United States)

    Nisbet, Ashley M; Camelliti, Patrizia; Walker, Nicola L; Burton, Francis L; Cobbe, Stuart M; Kohl, Peter; Smith, Godfrey L

    2016-05-01

    Conduction abnormalities are frequently associated with cardiac disease, though the mechanisms underlying the commonly associated increases in PQ interval are not known. This study uses a chronic left ventricular (LV) apex myocardial infarction (MI) model in the rabbit to create significant left ventricular dysfunction (LVD) 8weeks post-MI. In vivo studies established that the PQ interval increases by approximately 7ms (10%) with no significant change in average heart rate. Optical mapping of isolated Langendorff perfused rabbit hearts recapitulated this result: time to earliest activation of the LV was increased by 14ms (16%) in the LVD group. Intra-atrial and LV transmural conduction times were not altered in the LVD group. Isolated AVN preparations from the LVD group demonstrated a significantly longer conduction time (by approximately 20ms) between atrial and His electrograms than sham controls across a range of pacing cycle lengths. This difference was accompanied by increased effective refractory period and Wenckebach cycle length, suggesting significantly altered AVN electrophysiology post-MI. The AVN origin of abnormality was further highlighted by optical mapping of the isolated AVN. Immunohistochemistry of AVN preparations revealed increased fibrosis and gap junction protein (connexin43 and 40) remodelling in the AVN of LVD animals compared to sham. A significant increase in myocyte-non-myocyte connexin co-localization was also observed after LVD. These changes may increase the electrotonic load experienced by AVN muscle cells and contribute to slowed conduction velocity within the AVN. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Correlation between the sudden jump-like increases of the atrio-Hisian interval induced during burst atrial pacing and during programmed atrial stimulation in patients with atrioventricular nodal reentrant tachycardia.

    Science.gov (United States)

    Bayraktarova, Iskra H; Stoyanov, Milko K; Kunev, Boyan T; Shalganov, Tchavdar N

    To study the correlation between the sudden prolongations of the atrio-Hisian (AH) interval with ≥50 ms during burst and programmed atrial stimulation, and to define whether the AH jump during burst atrial pacing is a reliable diagnostic criterion for dual AV nodal physiology. Retrospective data on 304 patients with preliminary ECG diagnosis of AV nodal reentrant tachycardia (AVNRT), confirmed during electrophysiological study, was analyzed for the presence of AH jump during burst and programmed atrial stimulation, and for correlation between the pacing modes for inducing the jump. Wilcoxon signed-ranks test and Spearman's bivariate correlation coefficient were applied, significant was P-value jump occurred during burst atrial pacing in 81% of the patients, and during programmed stimulation - in 78%, P = 0.366. In 63.2% AH jump was induced by both pacing modes; in 17.8% - only by burst pacing; in 14.8% - only by programmed pacing; in 4.2% there was no inducible jump. There was negative correlation between both pacing modes, ρ = -0.204, Р<0.001. Burst and programmed atrial stimulation separately prove the presence of dual AV nodal physiology in 81 and 78% of the patients with AVNRT, respectively. There is negative correlation between the two pacing modes, allowing the combination of the two methods to prove diagnostic in 95.8% of the patients. Copyright © 2017 Indian Heart Rhythm Society. Production and hosting by Elsevier B.V. All rights reserved.

  5. Persistence of functional atrioventricular accessory pathways in postseptated embryonic avian hearts: implications for morphogenesis and functional maturation of the cardiac conduction system

    NARCIS (Netherlands)

    Kolditz, Denise P.; Wijffels, Maurits C. E. F.; Blom, Nico A.; van der Laarse, Arnoud; Markwald, Roger R.; Schalij, Martin J.; Gittenberger-de Groot, Adriana C.

    2007-01-01

    BACKGROUND: During heart development, the ventricular activation sequence changes from a base-to-apex to an apex-to-base pattern. We investigated the possibility of impulse propagation through remnants of atrioventricular (AV) connections in quail hearts. METHODS AND RESULTS: In 86 hearts (group A,

  6. Complete atrioventricular canal.

    Science.gov (United States)

    Calabrò, Raffaele; Limongelli, Giuseppe

    2006-04-05

    Complete atrioventricular canal (CAVC), also referred to as complete atrioventricular septal defect, is characterised by an ostium primum atrial septal defect, a common atrioventricular valve and a variable deficiency of the ventricular septum inflow. CAVC is an uncommon congenital heart disease, accounting for about 3% of cardiac malformations. Atrioventricular canal occurs in two out of every 10,000 live births. Both sexes are equally affected and a striking association with Down syndrome was found. Depending on the morphology of the superior leaflet of the common atrioventricular valve, 3 types of CAVC have been delineated (type A, B and C, according to Rastelli's classification). CAVC results in a significant interatrial and interventricular systemic-to-pulmonary shunt, thus inducing right ventricular pressure and volume overload and pulmonary hypertension. It becomes symptomatic in infancy due to congestive heart failure and failure to thrive. Diagnosis of CAVC might be suspected from electrocardiographic and chest X-ray findings. Echocardiography confirms it and gives anatomical details. Over time, pulmonary hypertension becomes irreversible, thus precluding the surgical therapy. This is the reason why cardiac catheterisation is not mandatory in infants (less than 6 months) but is indicated in older patients if irreversible pulmonary hypertension is suspected. Medical treatment (digitalis, diuretics, vasodilators) plays a role only as a bridge toward surgery, usually performed between the 3rd and 6th month of life.

  7. Complete atrioventricular canal

    Directory of Open Access Journals (Sweden)

    Limongelli Giuseppe

    2006-04-01

    Full Text Available Abstract Complete atrioventricular canal (CAVC, also referred to as complete atrioventricular septal defect, is characterised by an ostium primum atrial septal defect, a common atrioventricular valve and a variable deficiency of the ventricular septum inflow. CAVC is an uncommon congenital heart disease, accounting for about 3% of cardiac malformations. Atrioventricular canal occurs in two out of every 10,000 live births. Both sexes are equally affected and a striking association with Down syndrome was found. Depending on the morphology of the superior leaflet of the common atrioventricular valve, 3 types of CAVC have been delineated (type A, B and C, according to Rastelli's classification. CAVC results in a significant interatrial and interventricular systemic-to-pulmonary shunt, thus inducing right ventricular pressure and volume overload and pulmonary hypertension. It becomes symptomatic in infancy due to congestive heart failure and failure to thrive. Diagnosis of CAVC might be suspected from electrocardiographic and chest X-ray findings. Echocardiography confirms it and gives anatomical details. Over time, pulmonary hypertension becomes irreversible, thus precluding the surgical therapy. This is the reason why cardiac catheterisation is not mandatory in infants (less than 6 months but is indicated in older patients if irreversible pulmonary hypertension is suspected. Medical treatment (digitalis, diuretics, vasodilators plays a role only as a bridge toward surgery, usually performed between the 3rd and 6th month of life.

  8. Atrioventricular block, ECG tracing (image)

    Science.gov (United States)

    ... an abnormal rhythm (arrhythmia) called an atrioventricular (AV) block. P waves show that the top of the ... wave (and heart contraction), there is an atrioventricular block, and a very slow pulse (bradycardia).

  9. Paroxysmal atrioventricular block: Electrophysiological mechanism of phase 4 conduction block in the His-Purkinje system: A comparison with phase 3 block.

    Science.gov (United States)

    Shenasa, Mohammad; Josephson, Mark E; Wit, Andrew L

    2017-11-01

    Paroxysmal atrioventricular (A-V) block is relatively rare, and due to its transient nature, it is often under recognized. It is often triggered by atrial, junctional, or ventricular premature beats, and occurs in the presence of a diseased His-Purkinje system (HPS). Here, we present a 45-year-old white male who was admitted for observation due to recurrent syncope and near-syncope, who had paroxysmal A-V block. The likely cellular electrophysiological mechanisms(s) of paroxysmal A-V block and its differential diagnosis and management are discussed. Continuous electrocardiographic monitoring was done while the patient was in the cardiac unit. Multiple episodes of paroxysmal A-V block were documented in this case. All episodes were initiated and terminated with atrial/junctional premature beats. The patient underwent permanent pacemaker implantation and has remained asymptomatic since then. Paroxysmal A-V block is rare and often causes syncope or near-syncope. Permanent pacemaker implantation is indicated according to the current guidelines. Paroxysmal A-V block occurs in the setting of diseased HPS and is bradycardia-dependent. The detailed electrophysiological mechanisms, which involve phase 4 diastolic depolarization, and differential diagnosis are discussed. © 2017 Wiley Periodicals, Inc.

  10. Complete atrioventricular block following radiation therapy for malignant thymoma

    International Nuclear Information System (INIS)

    Nakao, Takeshi; Kanaya, Honin; Namura, Masanobu; Ohsato, Kazuo; Araki, Tsutomu; Ohka, Takio; Sugihara, Norihiko; Takeda, Ryoyu.

    1990-01-01

    Complete atrioventricular block following radiation is very rare. We present a case which developed after radiation therapy for malignant thymoma. The etiology of conduction disturbances due to radiation is unknown. In our case, serial electrocardiograms showed stepwise progression of the conduction disturbance, and his bundle electrocardiograms revealed new prolongation of the H-V interval. Endomyocardial biopsy specimens demonstrated occlusion in small arteries and diffuse degenerative changes in the myocardium. We therefore attributed the complete atrioventricular block in our patient to secondary damage to the conduction system, caused by radiation-induced occlusive changes in the small arteries supplying the conduction system. (author)

  11. Atrioventricular Dissociation following Blunt Chest Trauma

    Directory of Open Access Journals (Sweden)

    Salim Surani

    2014-01-01

    Full Text Available Blunt chest trauma (BCT is a common clinical presentation seen in emergency departments. Few cases of cardiac conduction abnormalities due to BCT have been reported in the medical literature. This dysrhythmias may present as permanent conduction defects requiring permanent pacemaker or may have temporary conduction abnormalities requiring temporary pacemaker or supportive care. We present the case of a young woman who suffered from BCT after being kicked by a horse with the development of a significant substernal hematoma. She developed temporary atrioventricular block, which was completely resolved with the decrease in the size of the substernal hematoma suffered.

  12. Nodal-chain metals.

    Science.gov (United States)

    Bzdušek, Tomáš; Wu, QuanSheng; Rüegg, Andreas; Sigrist, Manfred; Soluyanov, Alexey A

    2016-10-06

    The band theory of solids is arguably the most successful theory of condensed-matter physics, providing a description of the electronic energy levels in various materials. Electronic wavefunctions obtained from the band theory enable a topological characterization of metals for which the electronic spectrum may host robust, topologically protected, fermionic quasiparticles. Many of these quasiparticles are analogues of the elementary particles of the Standard Model, but others do not have a counterpart in relativistic high-energy theories. A complete list of possible quasiparticles in solids is lacking, even in the non-interacting case. Here we describe the possible existence of a hitherto unrecognized type of fermionic excitation in metals. This excitation forms a nodal chain-a chain of connected loops in momentum space-along which conduction and valence bands touch. We prove that the nodal chain is topologically distinct from previously reported excitations. We discuss the symmetry requirements for the appearance of this excitation and predict that it is realized in an existing material, iridium tetrafluoride (IrF 4 ), as well as in other compounds of this class of materials. Using IrF 4 as an example, we provide a discussion of the topological surface states associated with the nodal chain. We argue that the presence of the nodal-chain fermions will result in anomalous magnetotransport properties, distinct from those of materials exhibiting previously known excitations.

  13. Atrioventricular Dissociation after Electroconvulsive Therapy

    Directory of Open Access Journals (Sweden)

    Siegfried William Yu

    2011-01-01

    Full Text Available Electroconvulsive therapy (ECT is increasingly used as a treatment for psychiatric disorders. Cardiac effects are the principal cause of medical complications in these patients. We report a case of atrioventricular (AV dissociation that occurred after ECT that was treated with pacemaker implantation. The mechanisms contributing to the onset of AV dissociation in this patient, and the management and rationale for device therapy, in light of the most recent guidelines, are reviewed.

  14. Atrial Fibrillation, Atrioventricular Blocks and Bundle Branch Blocks in Hemodialysis Patients

    OpenAIRE

    Mandic, Ante; Tomic, Monika; Petrov, Bozo; Romic, Zeljko

    2012-01-01

    Atrial fibrillation is one of the most frequent arrhythmias diagnosed in clinical practice and it is also relatively common in dialysis patients. Atrioventricular and intraventricular conduction disturbances are less investigated in hemodialysis patients and data about their prevalence are insufficient. The objective of this study was to determine the prevalence of atrial fibrillation, atrioventricular blocks and bundle branch blocks in hemodialysis patients and to analyze different clinical ...

  15. KEK NODAL user's guide

    International Nuclear Information System (INIS)

    Akiyama, Atsuyoshi; Katoh, Tadahiko; Kikutani, Eiji; Koiso, Haruyo; Kurokawa, Shin-ichi; Oide, Katsunobu.

    1984-06-01

    NODAL is an interpreter language for accelerator control developed at CERN SPS and has been used successfully since 1974. At present NODAL or NODAL-like languages are used at DESY PETRA and CERN CPS. At KEK, we have also adopted NODAL for the control of TRISTAN, a 30 GeV x 30 GeV electron-positron colliding beam facility. The KEK version of NODAL has the following improvements on the SPS NODAL: (1) the fast execution speed due to the compiler-interpreter scheme, and (2) the full-screen editing facility. This manual explains how to use the KEK NODAL. It is based on the manual of the SPS NODAL, THE NODAL SYSTEM FOR THE SPS, by M.C. Crowley-Milling and G.C. Shering, CERN 78-07. We have made some additions and modifications to make the manual more appropriate for the KEK NODAL system, paying attention to retaining the good features of the original SPS NODAL manual. We acknowledge Professor M.C. Crowley-Milling, Dr G.C. Shering and CERN for their kind permission for this modification. (author)

  16. KEK NODAL system

    International Nuclear Information System (INIS)

    Kurokawa, S.; Abe, K.; Akiyama, A.; Katoh, T.; Kikutani, E.; Koiso, H.; Kurihara, N.; Oide, K.; Shinomoto, M.

    1985-01-01

    The KEK NODAL system, which is based on the NODAL devised at the CERN SPS, works on an optical-fiber token ring network of twenty-four minicomputers (Hitachi HIDIC 80's) to control the TRISTAN accelerator complex, now being constructed at KEK. KEK NODAL retains main features of the original NODAL: the interpreting scheme, the multi-computer programming facility, and the data-module concept. In addition, it has the following characteristics: fast execution due to the compiler-interpreter method, a multicomputer file system, a full-screen editing facility, and a dynamic linkage scheme of data modules and NODAL functions. The structure of the KEK NODAL system under PMS, a real-time multitasking operating system of HIDIC 80, is described; the NODAL file system is also explained

  17. Next-generation sequencing of AV nodal reentrant tachycardia patients identifies broad spectrum of variants in ion channel genes

    DEFF Research Database (Denmark)

    Andreasen, Laura; Ahlberg, Gustav; Tang, Chuyi

    2018-01-01

    Atrioventricular nodal reentry tachycardia (AVNRT) is the most common form of regular paroxysmal supraventricular tachycardia. This arrhythmia affects women twice as frequently as men, and is often diagnosed in patients <40 years of age. Familial clustering, early onset of symptoms and lack of st...

  18. Lyme Carditis: A Case Involving the Conduction System and Mitral Valve.

    Science.gov (United States)

    Patel, Lakir D; Schachne, Jay S

    2017-02-01

    Lyme disease is the most common tick-borne infection in the Northern hemisphere. Cardiac manifestations of Lyme disease typically include variable atrioventricular nodal block and rarely structural heart pathology. The incidence of Lyme carditis may be underestimated based on current reporting practices of confirmed cases. This case of a 59-year-old man with Lyme carditis demonstrates the unique presentation of widespread conduction system disease, mitral regurgitation, and suspected ischemic disease. Through clinical data, electrocardiograms, and cardiac imaging, we show the progression, and resolution, of a variety of cardiac symptoms attributable to infection with Lyme. [Full article available at http://rimed.org/rimedicaljournal-2017-02.asp].

  19. Ischemic stroke associated with radio frequency ablation for nodal reentry

    International Nuclear Information System (INIS)

    Diaz M, Juan C; Duran R, Carlos E; Perafan B, Pablo; Pava M, Luis F

    2010-01-01

    Atrioventricular nodal reentry tachycardia is the most common type of paroxysmal supraventricular tachycardia. In those patients in whom drug therapy is not effective or not desired, radio frequency ablation is an excellent therapeutic method. Although overall these procedures are fast and safe, several complications among which ischemic stroke stands out, have been reported. We present the case of a 41 year old female patient with repetitive episodes of tachycardia due to nodal reentry who was treated with radiofrequency ablation. Immediately after the procedure she presented focal neurologic deficit consistent with ischemic stroke in the right medial cerebral artery territory. Angiography with angioplastia and abxicimab was performed and then tissue plasminogen activator (rtPA) was locally infused, with appropriate clinical and angiographic outcome.

  20. [Reversible first-degree atrioventricular block due to hyperthyroidism].

    Science.gov (United States)

    Çelebi, Aksüyek Savaş; Amasyalı, Basri

    2017-04-01

    Hyperthyroidism often causes tachyarrhythmia. Reversible atrioventricular block caused by hyperthyroidism is rare occurrence. Presently described is a case of atrioventricular block due to hyperthyroidism and recovery after antithyroid treatment.

  1. Occult etiologies of complete atrioventricular block: Report of two cases

    Directory of Open Access Journals (Sweden)

    Neeta Bachani

    2016-09-01

    Full Text Available In patients presenting with complete atrioventricular (AV block, the common causes are degeneration of the conduction system, acute myocardial infarction, congenital and metabolic disorders (such as azotemia. However, at times, no cause can be ascribed and the label congenital or degenerative is applied depending on the patient's age and the QRS complex width. We present two cases of patients with complete AV block, who were subsequently found to have rare etiologies – sarcoidosis (with isolated feature of AV block and non-Hodgkin's lymphoma.

  2. Factors associated with moderate or severe left atrioventricular valve regurgitation within 30 days of repair of incomplete atrioventricular septal defect

    Directory of Open Access Journals (Sweden)

    Marcelo Felipe Kozak

    2015-04-01

    Full Text Available AbstractIntroduction:Left atrioventricular valve regurgitation is the most concerning residual lesion after surgical correction of atrioventricular septal defect.Objective:To determine factors associated with moderate or greater left atrioventricular valve regurgitation within 30 days of surgical repair of incomplete atrioventricular septal defect.Methods:We assessed the results of 51 consecutive patients 14 years-old and younger presenting with incomplete atrioventricular septal defect that were operated on at our practice between 2002 and 2010. The following variables were considered: age, weight, absence of Down syndrome, grade of preoperative left atrioventricular valve regurgitation, abnormalities on the left atrioventricular valve and the use of annuloplasty. The median age was 4.1 years; the median weight was 13.4 Kg; 37.2% had Down syndrome. At the time of preoperative evaluation, there were 23 cases with moderate or greater left atrioventricular valve regurgitation (45.1%. Abnormalities on the left atrioventricular valve were found in 17.6%; annuloplasty was performed in 21.6%.Results:At the time of postoperative evaluation, there were 12 cases with moderate or greater left atrioventricular valve regurgitation (23.5%. The variation between pre- and postoperative grades of left atrioventricular valve regurgitation of patients with atrioventricular valve malformation did not reach significance (P=0.26, unlike patients without such abnormalities (P=0.016. During univariate analysis, only absence of Down syndrome was statistically significant (P=0.02. However, after a multivariate analysis, none of the factors reached significance.Conclusion:None of the factors studied was determinant of a moderate or greater left atrioventricular valve regurgitation within the first 30 days of repair of incomplete atrioventricular septal defect in the sample. Patients without abnormalities on the left atrioventricular valve benefit more of the operation.

  3. Clinically oriented device programming in bradycardia patients: part 2 (atrioventricular blocks and neurally mediated syncope). Proposals from AIAC (Italian Association of Arrhythmology and Cardiac Pacing).

    Science.gov (United States)

    Palmisano, Pietro; Ziacchi, Matteo; Biffi, Mauro; Ricci, Renato P; Landolina, Maurizio; Zoni-Berisso, Massimo; Occhetta, Eraldo; Maglia, Giampiero; Botto, Gianluca; Padeletti, Luigi; Boriani, Giuseppe

    2018-04-01

    : The purpose of this two-part consensus document is to provide specific suggestions (based on an extensive literature review) on appropriate pacemaker setting in relation to patients' clinical features. In part 2, criteria for pacemaker choice and programming in atrioventricular blocks and neurally mediate syncope are proposed. The atrioventricular blocks can be paroxysmal or persistent, isolated or associated with sinus node disease. Neurally mediated syncope can be related to carotid sinus syndrome or cardioinhibitory vasovagal syncope. In sinus rhythm, with persistent atrioventricular block, we considered appropriate the activation of mode-switch algorithms, and algorithms for auto-adaptive management of the ventricular pacing output. If the atrioventricular block is paroxysmal, in addition to algorithms mentioned above, algorithms to maximize intrinsic atrioventricular conduction should be activated. When sinus node disease is associated with atrioventricular block, the activation of rate-responsive function in patients with chronotropic incompetence is appropriate. In permanent atrial fibrillation with atrioventricular block, algorithms for auto-adaptive management of the ventricular pacing output should be activated. If the atrioventricular block is persistent, the activation of rate-responsive function is appropriate. In carotid sinus syndrome, adequate rate hysteresis should be programmed. In vasovagal syncope, specialized sensing and pacing algorithms designed for reflex syncope prevention should be activated.

  4. Congestive Heart Failure Leads to Prolongation of the PR Interval and Atrioventricular Junction Enlargement and Ion Channel Remodelling in the Rabbit

    Science.gov (United States)

    Nikolaidou, Theodora; Cai, Xue J.; Stephenson, Robert S.; Yanni, Joseph; Lowe, Tristan; Atkinson, Andrew J.; Jones, Caroline B.; Sardar, Rida; Corno, Antonio F.; Dobrzynski, Halina; Withers, Philip J.; Jarvis, Jonathan C.; Hart, George; Boyett, Mark R.

    2015-01-01

    Heart failure is a major killer worldwide. Atrioventricular conduction block is common in heart failure; it is associated with worse outcomes and can lead to syncope and bradycardic death. We examine the effect of heart failure on anatomical and ion channel remodelling in the rabbit atrioventricular junction (AVJ). Heart failure was induced in New Zealand rabbits by disruption of the aortic valve and banding of the abdominal aorta resulting in volume and pressure overload. Laser micro-dissection and real-time polymerase chain reaction (RT-PCR) were employed to investigate the effects of heart failure on ion channel remodelling in four regions of the rabbit AVJ and in septal tissues. Investigation of the AVJ anatomy was performed using micro-computed tomography (micro-CT). Heart failure animals developed first degree heart block. Heart failure caused ventricular myocardial volume increase with a 35% elongation of the AVJ. There was downregulation of HCN1 and Cx43 mRNA transcripts across all regions and downregulation of Cav1.3 in the transitional tissue. Cx40 mRNA was significantly downregulated in the atrial septum and AVJ tissues but not in the ventricular septum. mRNA abundance for ANP, CLCN2 and Navβ1 was increased with heart failure; Nav1.1 was increased in the inferior nodal extension/compact node area. Heart failure in the rabbit leads to prolongation of the PR interval and this is accompanied by downregulation of HCN1, Cav1.3, Cx40 and Cx43 mRNAs and anatomical enlargement of the entire heart and AVJ. PMID:26509807

  5. Congestive Heart Failure Leads to Prolongation of the PR Interval and Atrioventricular Junction Enlargement and Ion Channel Remodelling in the Rabbit.

    Directory of Open Access Journals (Sweden)

    Theodora Nikolaidou

    Full Text Available Heart failure is a major killer worldwide. Atrioventricular conduction block is common in heart failure; it is associated with worse outcomes and can lead to syncope and bradycardic death. We examine the effect of heart failure on anatomical and ion channel remodelling in the rabbit atrioventricular junction (AVJ. Heart failure was induced in New Zealand rabbits by disruption of the aortic valve and banding of the abdominal aorta resulting in volume and pressure overload. Laser micro-dissection and real-time polymerase chain reaction (RT-PCR were employed to investigate the effects of heart failure on ion channel remodelling in four regions of the rabbit AVJ and in septal tissues. Investigation of the AVJ anatomy was performed using micro-computed tomography (micro-CT. Heart failure animals developed first degree heart block. Heart failure caused ventricular myocardial volume increase with a 35% elongation of the AVJ. There was downregulation of HCN1 and Cx43 mRNA transcripts across all regions and downregulation of Cav1.3 in the transitional tissue. Cx40 mRNA was significantly downregulated in the atrial septum and AVJ tissues but not in the ventricular septum. mRNA abundance for ANP, CLCN2 and Navβ1 was increased with heart failure; Nav1.1 was increased in the inferior nodal extension/compact node area. Heart failure in the rabbit leads to prolongation of the PR interval and this is accompanied by downregulation of HCN1, Cav1.3, Cx40 and Cx43 mRNAs and anatomical enlargement of the entire heart and AVJ.

  6. Experimental discovery of nodal chains

    Science.gov (United States)

    Yan, Qinghui; Liu, Rongjuan; Yan, Zhongbo; Liu, Boyuan; Chen, Hongsheng; Wang, Zhong; Lu, Ling

    2018-05-01

    Three-dimensional Weyl and Dirac nodal points1 have attracted widespread interest across multiple disciplines and in many platforms but allow for few structural variations. In contrast, nodal lines2-4 can have numerous topological configurations in momentum space, forming nodal rings5-9, nodal chains10-15, nodal links16-20 and nodal knots21,22. However, nodal lines are much less explored because of the lack of an ideal experimental realization23-25. For example, in condensed-matter systems, nodal lines are often fragile to spin-orbit coupling, located away from the Fermi level, coexist with energy-degenerate trivial bands or have a degeneracy line that disperses strongly in energy. Here, overcoming all these difficulties, we theoretically predict and experimentally observe nodal chains in a metallic-mesh photonic crystal having frequency-isolated linear band-touching rings chained across the entire Brillouin zone. These nodal chains are protected by mirror symmetry and have a frequency variation of less than 1%. We use angle-resolved transmission measurements to probe the projected bulk dispersion and perform Fourier-transformed field scans to map out the dispersion of the drumhead surface state. Our results establish an ideal nodal-line material for further study of topological line degeneracies with non-trivial connectivity and consequent wave dynamics that are richer than those in Weyl and Dirac materials.

  7. The use of non-invasive fetal electrocardiography in diagnosing second-degree fetal atrioventricular block.

    Science.gov (United States)

    Lakhno, Igor; Behar, Joachim A; Oster, Julien; Shulgin, Vyacheslav; Ostras, Oleksii; Andreotti, Fernando

    2017-01-01

    Complete atrioventricular block in fetuses is known to be mostly associated with autoimmune disease and can be irreversible if no steroids treatment is provided. Conventional methods used in clinical practice for diagnosing fetal arrhythmia are limited since they do not reflect the primary electrophysiological conduction processes that take place in the myocardium. The non-invasive fetal electrocardiogram has the potential to better support fetal arrhythmias diagnosis through the continuous analysis of the beat to beat variation of the fetal heart rate and morphological analysis of the PQRST complex. We present two retrospective case reports on which atrioventricular block diagnosis could have been supported by the non-invasive fetal electrocardiogram. The two cases comprised a 22-year-old pregnant woman with the gestational age of 31 weeks and a 25-year-old pregnant woman with the gestational age of 41 weeks. Both women were admitted to the Department of Maternal and Fetal Medicine at the Kyiv and Kharkiv municipal perinatal clinics. Patients were observed using standard fetal monitoring methods as well as the non-invasive fetal electrocardiogram. The non-invasive fetal electrocardiographic recordings were analyzed retrospectively, where it is possible to identify the presence of the atrioventricular block. This study demonstrates, for the first time, the feasibility of the non-invasive fetal electrocardiogram as a supplementary method to diagnose of the fetal atrioventricular block. Combined with current fetal monitoring techniques, non-invasive fetal electrocardiography could support clinical decisions.

  8. Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management.

    Science.gov (United States)

    Baruteau, Alban-Elouen; Pass, Robert H; Thambo, Jean-Benoit; Behaghel, Albin; Le Pennec, Solène; Perdreau, Elodie; Combes, Nicolas; Liberman, Leonardo; McLeod, Christopher J

    2016-09-01

    Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities. Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for

  9. INTERMITTENT ANTIARYTHMIC THERAPY OF ARIOVENTICULAR NODAL REENTRY TACHYCARDIA IN CHILDREN

    Directory of Open Access Journals (Sweden)

    Boris Djindjic

    2008-04-01

    Full Text Available Until recent advances in pharmacology and clinical cardiology regarding farmacodynamics of antiarrhythmic drugs and their efficiency in patients with refractory paroxysmal supraventricular tachycardia, chronic prophylactic therapy was the only treatment option for patients refusing catheter ablation. Another treatment option, also known by eponym “pill in pocket” have been shown to be equally useful and efficacious.The aim of our study was prospective examination of children with refractory atrioventricular nodal reentry tachycardia (AVNRT who were withdrawn from chronic antiarrhythmic prophylactic therapy and started with intermittent oral beta blocker treatment (propranolol at dosage 1 mg/kg - max 80 mg.Twelve children (8 boys and 4 girls with AVNRT were included in the study. Four children did not have arrhythmia during first six months after withdrawal and 7 were successfully treated without complication.Intermittent antiarrhythmic therapy in children with AVNRT could be very efficacious and useful treatment option which significantly improves their quality of life.

  10. Avoided intersections of nodal lines

    International Nuclear Information System (INIS)

    Monastra, Alejandro G; Smilansky, Uzy; Gnutzmann, Sven

    2003-01-01

    We consider real eigenfunctions of the Schroedinger operator in 2D. The nodal lines of separable systems form a regular grid, and the number of nodal crossings equals the number of nodal domains. In contrast, for wavefunctions of non-integrable systems nodal intersections are rare, and for random waves, the expected number of intersections in any finite area vanishes. However, nodal lines display characteristic avoided crossings which we study in this work. We define a measure for the avoidance range and compute its distribution for the random wave ensemble. We show that the avoidance range distribution of wavefunctions of chaotic systems follows the expected random wave distributions, whereas for wavefunctions of classically integrable but quantum non-separable systems, the distribution is quite different. Thus, the study of the avoidance distribution provides more support to the conjecture that nodal structures of chaotic systems are reproduced by the predictions of the random wave ensemble

  11. [Complete atrioventricular block in Duchenne muscular dystrophy].

    Science.gov (United States)

    Kuru, Satoshi; Tanahashi, Tamotsu; Matsumoto, Shinjirou; Kitamura, Tetsuya; Konagaya, Masaaki

    2012-01-01

    We report a case of complete atrioventricular (AV) block in a 40-year-old patient with Duchenne muscular dystrophy (DMD). While he was bed-ridden and required mechanical ventilation, his cardiac involvement was mild. He had the deletion of exon 45-52 in the dystrophin gene. He underwent transient complete AV block and came to require pacemaker implantation due to recurrence of complete AV block ten days after the first attack. Electrophysiological study revealed mild prolonged AH and HV interval. Although DMD patients with AV block have been rarely reported so far, attention should be paid to AV block for patients who prolonged their lives.

  12. Unbalanced atrioventricular septal defect: definition and decision making.

    Science.gov (United States)

    Overman, David M; Baffa, Jeanne M; Cohen, Meryl S; Mertens, Luc; Gremmels, David B; Jegatheeswaram, Anusha; McCrindle, Brian W; Blackstone, Eugene H; Morell, Victor O; Caldarone, Christopher; Williams, William G; Pizarro, Christian

    2010-04-01

    Unbalanced atrioventricular septal defect is an uncommon lesion with widely varying anatomic manifestations. When unbalance is severe, diagnosis and treatment is straightforward, directed toward single-ventricle palliation. Milder forms, however, pose a challenge to current diagnostic and therapeutic approaches. The transition from anatomies that are capable of sustaining biventricular physiology to those that cannot is obscure, resulting in uneven application of surgical strategy and excess mortality. Imprecise assessments of ventricular competence have dominated clinical decision making in this regard. Malalignment of the atrioventricular junction and its attendant derangement of inflow physiology is a critical factor in determining the feasibility of biventricular repair in the setting of unbalanced atrioventricular septal defect. The atrioventricular valve index accurately identifies unbalanced atrioventricular septal defect and also brings into focus a zone of transition from anatomies that can support a biventricular end state and those that cannot.

  13. A nodalization study of steam separator in real time simulation

    International Nuclear Information System (INIS)

    Horugshyang, Lein; Luh, R.T.J.; Zen-Yow, Wang

    1999-01-01

    The motive of this paper is to investigate the influence of steam separator nodalization on reactor thermohydraulics in terms of stability and level response. Three different nodalizations of steam separator are studied by using THEATRE and REMARK Code in a BWR simulator. The first nodalization is the traditional one with two nodes for steam separator. In this nodalization, the steam separation is modeled in the outer node, i.e., upper downcomer. Separated steam enters the Steen dome node and the liquid goes to the feedwater node. The second nodalization is similar to the first one with the steam separation modeled in the inner node. There is one additional junction connecting steam dome node and the inner node. The liquid fallback junction connects the inner node and feedwater node. The third nodalization is a combination of the former two with an integrated node for steam separator. Boundary conditions in this study are provided by a simplified feedwater and main steam driver. For comparison purpose, three tests including full power steady state initialisation, recirculation pumps runback and reactor scram are conducted. Major parameters such as reactor pressure, reactor level, void fractions, neutronic power and junction flows are recorded for analysis. Test results clearly show that the first nodalization is stable for steady state initialisation. However it has too responsive level performance in core flow reduction transients. The second nodalization is the closest representation of real plant structure, but not the performance. Test results show that an instability occurs in the separator region for both steady state initialisation and transients. This instability is caused by an unbalanced momentum in the dual loop configuration. The magnitude of the oscillation reduces as the power decreases. No superiority to the other nodalizations is shown in the test results. The third nodalization shows both stability and responsiveness in the tests. (author)

  14. Successful catheter ablation of ventricular premature complexes from the right atrial side of the atrioventricular septum with good contact force.

    Science.gov (United States)

    Arai, Marina; Fukamizu, Seiji; Kawamura, Iwanari; Miyazawa, Satoshi; Hojo, Rintaro; Sakurada, Harumizu; Hiraoka, Masayasu

    2018-04-01

    The acquisition of good contact force for radiofrequency catheter ablation of ventricular premature complexes (VPCs) originating from the basal septum of the left ventricle (LV) is often difficult. We describe a case of VPCs originating from the basal septum of the LV, which were successfully eliminated by applying radiofrequency at the right atrium (RA) side of the atrioventricular septum (AVS) without causing any significant impairment of atrioventricular conduction because the ablation catheter could obtain better contact force through the RA approach. Moreover, intracardiac echocardiography (ICE) and RA angiography effectively demonstrated the AVS.

  15. The SINTRAN III NODAL system

    International Nuclear Information System (INIS)

    Skaali, T.B.

    1980-10-01

    NODAL is a high level programming language based on FOCAL and SNOBOL4, with some influence from BASIC. The language was developed to operate on the computer network controlling the SPS accelerator at CERN. NODAL is an interpretive language designed for interactive use. This is the most important aspect of the language, and is reflected in its structure. The interactive facilities make it possible to write, debug and modify programs much faster than with compiler based languages like FORTRAN and ALGOL. Apart from a few minor modifications, the basic part of the Oslo University NODAL system does not differ from the CERN version. However, the Oslo University implementation has been expanded with new functions which enable the user to execute many of the SINTRAN III monitor calls from the NODAL level. In particular the most important RT monitor calls have been implemented in this way, a property which renders possible the use of NODAL as a RT program administrator. (JIW)

  16. Fatal Lyme carditis and endodermal heterotopia of the atrioventricular node.

    Science.gov (United States)

    Cary, N. R.; Fox, B.; Wright, D. J.; Cutler, S. J.; Shapiro, L. M.; Grace, A. A.

    1990-01-01

    A fatal case of Lyme carditis occurring in a Suffolk farmworker is reported. Post-mortem examination of the heart showed pericarditis, focal myocarditis and prominent endocardial and interstitial fibrosis. The additional finding of endodermal heterotopia ('mesothelioma') of the atrioventricular node raises the possibility that this could also be related to Lyme infection and account for the relatively frequent occurrence of atrioventricular block in this condition. Lyme disease should always be considered in a case of atrioventricular block, particularly in a young patient from a rural area. The heart block tends to improve and therefore only temporary pacing may be required. Images Figure 1 Figure 2 Figure 3 PMID:2349186

  17. Right and left inferior extensions of the atrioventricular node may represent the anatomic substrate of the slow pathway in humans

    NARCIS (Netherlands)

    Katritsis, Demosthenes G.; Becker, Anton E.; Ellenbogen, Kenneth A.; Karabinos, Ilias; Giazitzoglou, Eleftherios; Korovesis, Socrates; Camm, A. John

    2004-01-01

    The purpose of this study was to investigate the electrophysiologic characteristics of the inferior extensions of the human atrioventricular (AV) node and their possible relationship to slow pathway conduction. The human heart contains right and left inferior extensions of the AV node that relate to

  18. Atrioventricular node functional remodeling induced by atrial fibrillation.

    Science.gov (United States)

    Zhang, Youhua; Mazgalev, Todor N

    2012-09-01

    The atrioventricular node (AVN) plays a vital role in determining the ventricular rate during atrial fibrillation (AF). AF results in profound electrophysiological and structural remodeling in the atria as well as the sinus node. However, it is unknown whether AVN undergoes remodeling during AF. To determine whether AVN undergoes functional remodeling during AF. AVN conduction properties were studied in vitro in 9 rabbits with AF and 10 normal controls. A previously validated index of AVN dual-pathway electrophysiology, His-electrogram alternans, was used to monitor fast-pathway or slow-pathway (SP) AVN conduction in these experiments. AVN conduction properties were further studied in vivo in 7 dogs with chronic AF and 8 controls. Compared with the control rabbits, the rabbits with AF had a longer AVN conduction time (83 ± 16 ms vs 68 ± 7 ms; P AVN effective refractory period (141 ± 27 ms vs 100 ± 9 ms; P AVN effective refractory period and a slower ventricular rate during AF compared with the controls. Pronounced AVN functional electrophysiological remodeling occurs after long-term AF, which could lead to a spontaneous slowing of the ventricular rate. Furthermore, the SP dominance during AF underscores the effectiveness of its modification by ablation for ventricular rate control during AF. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  19. Swallow syncope caused by third-degree atrioventricular block

    DEFF Research Database (Denmark)

    Roust Aaberg, Anne Marie; Eriksson, Anna Elin; Madsen, Per Lav

    2015-01-01

    We report a case of a patient with more than 30 years of repeated syncopes, always following food intake. The patient was diagnosed with a swallow-related third-degree atrioventricular block and successfully treated with an artificial pacemaker.......We report a case of a patient with more than 30 years of repeated syncopes, always following food intake. The patient was diagnosed with a swallow-related third-degree atrioventricular block and successfully treated with an artificial pacemaker....

  20. NODAL interpreter for CP/M

    International Nuclear Information System (INIS)

    Oide, Katsunobu.

    1982-11-01

    A NODAL interpreter which works under CP/M operating system is made for microcomputers. This interpreter language named NODAL-80 has a similar structure to the NODAL of SPS, but its commands, variables, and expressions are modified to increase the flexibility of programming. NODAL-80 also uses a simple intermediate code to make the execution speed fast without imposing any restriction on the dynamic feature of NODAL language. (author)

  1. The double switch for atrioventricular discordance.

    Science.gov (United States)

    Brawn, William J

    2005-01-01

    Conventional surgery for atrioventricular discordance usually associated with ventricular arterial discordance leaves the morphologic right ventricle in the systemic circulation. Long-term follow-up results with this approach reveal a high incidence of right ventricular failure. The double switch procedure was introduced to restore the morphologic left ventricle to the systemic circulation. This operation is performed in two main ways: the atrial-arterial switch and the atrial switch plus Rastelli procedure. This double switch approach has been successful at least in the medium term in abolishing morphologic right ventricular failure and its associated tricuspid valve regurgitation. In the atrial-arterial switch group, there is an incidence of morphologic left ventricular dysfunction, sometimes associated with neoaortic valve regurgitation, and the minority of cases need aortic valve replacement. The long-term function of the morphologic left ventricle and the aortic valve need careful surveillance in the future. The atrial-Rastelli group of patients has not in the medium term shown evidence of ventricular dysfunction but will require change on a regular basis of their ventricular to pulmonary artery valved conduits.

  2. Long-term survival in children with atrioventricular septal defect and common atrioventricular valvar orifice in Sweden.

    Science.gov (United States)

    Frid, Christina; Björkhem, Gudrun; Jonzon, Anders; Sunnegårdh, Jan; Annerén, Göran; Lundell, Bo

    2004-02-01

    The survival for patients with atrioventricular septal defect has improved markedly over the last decades and, during the same period, the survival of children with Down's syndrome has also increased. The aim of our study was to investigate long-term survival in patients having atrioventricular septal defect with common valvar orifice, but without associated significant congenital heart defects, in the setting of Down's syndrome, comparing the findings to those in chromosomally normal children with the same malformation. In a population-based retrospective study, we scrutinised the medical records from 801 liveborn children with atrioventricular septal defect born in Sweden during the period 1973 through 1997. Data on gender, presence or absence of Down's syndrome, associated congenital heart defects, date of birth, operation and death were recorded and followed up until 2001. An isolated atrioventricular septal defect with common atrioventricular valvar orifice was present in 502 children, of whom 86% had Down's syndrome. We found a significant reduc tion over time in age at operation, and in postoperative mortality at 30 days, from 28 to 1%. Using a multiple logistic regression model, we found no significant differences in mortality between genders, nor between those with or without Down's syndrome. Early corrective surgery could not be identified as a significant independent factor for survival. The 5-year postoperative survival in patients with Down's syndrome increased from 65% over the period from 1973 through 1977, to about 90% in the period 1993 through 1997, and the same trend was observed in chromosomally normal patients. Survival in uncomplicated atrioventricular septal defect with common atrioventricular valvar orifice has greatly increased, and surgical correction is now equally successful in patients with Down's syndrome and chromosomally normal patients, and for both genders. Death in connection with surgery is no longer the major threat, and focus

  3. Nodal metastasis in thyroid cancer

    International Nuclear Information System (INIS)

    Samuel, A.M.

    1999-01-01

    The biological behavior and hence the prognosis of thyroid cancer (TC) depends among other factors on the extent of spread of the disease outside the thyroid bed. This effect is controversial, especially for nodal metastasis of well differentiated thyroid carcinoma (WDC). Nodal metastasis at the time of initial diagnosis behaves differently depending on the histology, age of the patient, presence of extrathyroidal extension, and the sex of the individual. The type of the surgery, administration of 131 I and thyroxin suppression also to some extent influence the rate of recurrence and mortality. Experience has shown that it is not as innocuous as a small intrathyroidal tumor without any invasion outside the thyroid bed and due consideration should be accorded to the management strategies for handling patients with nodal metastasis

  4. The adjoint variational nodal method

    International Nuclear Information System (INIS)

    Laurin-Kovitz, K.; Lewis, E.E.

    1993-01-01

    The widespread use of nodal methods for reactor core calculations in both diffusion and transport approximations has created a demand for the corresponding adjoint solutions as a prerequisite for performing perturbation calculations. With some computational methods, however, the solution of the adjoint problem presents a difficulty; the physical adjoint obtained by discretizing the adjoint equation is not the same as the mathematical adjoint obtained by taking the transpose of the coefficient matrix, which results from the discretization of the forward equation. This difficulty arises, in particular, when interface current nodal methods based on quasi-one-dimensional solution of the diffusion or transport equation are employed. The mathematical adjoint is needed to perform perturbation calculations. The utilization of existing nodal computational algorithms, however, requires the physical adjoint. As a result, similarity transforms or related techniques must be utilized to relate physical and mathematical adjoints. Thus far, such techniques have been developed only for diffusion theory

  5. Reversible complete atrioventricular block in patient with wegener's granulomatosis - a report on fortunate outcome with long term follow-up.

    Science.gov (United States)

    Steckiewicz, Roman; Rosiak, Marek; Stolarz, Przemysław; Świętoń, Elżbieta B; Grabowski, Marcin; Kosior, Dariusz A

    Reversible complete atrioventricular block in patient with Wegener's granulomatosis - a report on a positive outcome with long term follow-up. Atrioventricular (AV) block is a rare complication of Wegener's granulomatosis (WG), thus there are no standards of management in such cases. We present a case of a patient with a dual-chamber pacemaker (DDD) implanted due to complete AV block in the course of Wegener's granulomatosis (WG). An immunosuppressive therapy resulted in the resolution of non-cardiac and AV conduction disorders. The diagnostic functions of the pacemaker enabled us to evaluate AV conduction over a five-year follow-up period. The resolution of AV conduction disorders, which accompanied WG remission, suggests that careful monitoring with temporary cardiac pacing may be considered in some patients before permanent pacemaker implantation.

  6. Nodal in computerized control systems of accelerators

    International Nuclear Information System (INIS)

    Kagarmanov, A.A.; Koval'tsov, V.I.; Korobov, S.A.

    1994-01-01

    Brief description of the Nodal language programming structure is presented. Its possibilities as high-level programming language for accelerator control systems are considered. The status of the Nodal language in the HEPI is discussed. 3 refs

  7. A variational synthesis nodal discrete ordinates method

    International Nuclear Information System (INIS)

    Favorite, J.A.; Stacey, W.M.

    1999-01-01

    A self-consistent nodal approximation method for computing discrete ordinates neutron flux distributions has been developed from a variational functional for neutron transport theory. The advantage of the new nodal method formulation is that it is self-consistent in its definition of the homogenized nodal parameters, the construction of the global nodal equations, and the reconstruction of the detailed flux distribution. The efficacy of the method is demonstrated by two-dimensional test problems

  8. Nodal line optimization and its application to violin top plate design

    Science.gov (United States)

    Yu, Yonggyun; Jang, In Gwun; Kim, In Kyum; Kwak, Byung Man

    2010-10-01

    In the literature, most problems of structural vibration have been formulated to adjust a specific natural frequency: for example, to maximize the first natural frequency. In musical instruments like a violin; however, mode shapes are equally important because they are related to sound quality in the way that natural frequencies are related to the octave. The shapes of nodal lines, which represent the natural mode shapes, are generally known to have a unique feature for good violins. Among the few studies on mode shape optimization, one typical study addresses the optimization of nodal point location for reducing vibration in a one-dimensional beam structure. However, nodal line optimization, which is required in violin plate design, has not yet been considered. In this paper, the central idea of controlling the shape of the nodal lines is proposed and then applied to violin top plate design. Finite element model for a violin top plate was constructed using shell elements. Then, optimization was performed to minimize the square sum of the displacement of selected nodes located along the target nodal lines by varying the thicknesses of the top plate. We conducted nodal line optimization for the second and the fifth modes together at the same time, and the results showed that the nodal lines obtained match well with the target nodal lines. The information on plate thickness distribution from nodal line optimization would be valuable for tailored trimming of a violin top plate for the given performances.

  9. Canonical wnt signaling regulates atrioventricular junction programming and electrophysiological properties

    NARCIS (Netherlands)

    Gillers, Benjamin S.; Chiplunkar, Aditi; Aly, Haytham; Valenta, Tomas; Basler, Konrad; Christoffels, Vincent M.; Efimov, Igor R.; Boukens, Bastiaan J.; Rentschler, Stacey

    2015-01-01

    Proper patterning of the atrioventricular canal (AVC) is essential for delay of electrical impulses between atria and ventricles, and defects in AVC maturation can result in congenital heart disease. To determine the role of canonical Wnt signaling in the myocardium during AVC development. We used a

  10. NESTLE: A nodal kinetics code

    International Nuclear Information System (INIS)

    Al-Chalabi, R.M.; Turinsky, P.J.; Faure, F.-X.; Sarsour, H.N.; Engrand, P.R.

    1993-01-01

    The NESTLE nodal kinetics code has been developed for utilization as a stand-alone code for steady-state and transient reactor neutronic analysis and for incorporation into system transient codes, such as TRAC and RELAP. The latter is desirable to increase the simulation fidelity over that obtained from currently employed zero- and one-dimensional neutronic models and now feasible due to advances in computer performance and efficiency of nodal methods. As a stand-alone code, requirements are that it operate on a range of computing platforms from memory-limited personal computers (PCs) to supercomputers with vector processors. This paper summarizes the features of NESTLE that reflect the utilization and requirements just noted

  11. Nodal lymphomas of the abdomen

    International Nuclear Information System (INIS)

    Bruneton, J.N.; Caramella, E.; Manzino, J.J.

    1986-01-01

    Modern imaging modalities have greatly contributed to current knowledge about intra-abdominal nodal lymphomas. Since both intra and retroperitoneal node involvement can be demonstrated by computed tomography (CT) and ultrasonography, it seems legitimate to treat these two sites together in the same chapter, particularly since the older separation between intraperitoneal and retroperitoneal nodal disease was based to a large degree on the limitations of lymphography. Hodgkin's disease (HD) has benefited less from recent technological advances. The diversity in the incidence of nodal involvement between HD and NHL, the diagnostic capabilities of modern imaging techniques, and the histopathological features of lymphomatous non-Hodgkin and Hodgkin nodes, justify adoption of an investigatory approach which takes all of these factors into account. Details of this investigative strategy are discussed in this paper following a review of available imaging modalities. In current practice, the four main methods for the exploration of abdominal lymph nodes are lymphography, ultrasonography, CT, and radionuclide studies. The first three techniques are also utilized to guide biopsies for staging purposes and for the evaluation of response to treatment

  12. Defeito completo do septo atrioventricular com cianose Complete repair in total atrioventricular canal defect with cyanosis

    Directory of Open Access Journals (Sweden)

    Carla Tanamati

    2006-09-01

    Full Text Available Os defeitos do septo atrioventricular total (DSAVT representam 4% das mal formações cardíacas e acima de 50% dos defeitos observados na síndrome de Down (SD¹. A apresentação clínica é de insuficiência cardíaca precoce na infância e hipertensão pulmonar por hiperfluxo. Raramente a cianose é observada e sugere hipertensão pulmonar ou associação à tetralogia de Fallot³, dupla via de saída de ventrículo direito², anomalia de Ebstein4, drenagem anômala de cava esquerda persistente em átrio esquerdo (Barbero Marcial, comunicação pessoal. Crianças com SD são particularmente difíceis de avaliação por apresentarem obstrução de vias aéreas superiores, que podem contribuir com o aumento da resistência pulmonar observada no cateterismo cardíaco. A presença de cianose pré-operatória constitui-se um desafio ao tratamento cirúrgico devido ao risco de hipertensão pulmonar irreversível com falência ventricular direita com, a correção dos defeitos intracardíacos.Atrioventricular septal defects account for 4% of congenital cardiac malformations and over 50% of cardiac defects seen in Down syndrome¹. Clinical presentation is marked by congestive heart failure early in infancy. Cyanosis is rarely found in infants and suggests irreversible pulmonary hypertension or associated cardiac defects as tetralogy of Fallot, double outlet right ventricle², Ebstein anomaly³, persistent left superior vena cava draining in the left atrium (Barbero Marcial, personal communication. Children with Down's syndrome is particularly difficult to assess because they often suffer from upper airways obstruction4, which may contribute to the increased pulmonary vascular resistance determined at cardiac catheterization. This association of factors becomes a challenge for operability and, we will report one such case.

  13. Identification of nodal tissue in the living heart using rapid scanning fiber-optics confocal microscopy and extracellular fluorophores.

    Science.gov (United States)

    Huang, Chao; Kaza, Aditya K; Hitchcock, Robert W; Sachse, Frank B

    2013-09-01

    Risks associated with pediatric reconstructive heart surgery include injury of the sinoatrial node (SAN) and atrioventricular node (AVN), requiring cardiac rhythm management using implantable pacemakers. These injuries are the result of difficulties in identifying nodal tissues intraoperatively. Here we describe an approach based on confocal microscopy and extracellular fluorophores to quantify tissue microstructure and identify nodal tissue. Using conventional 3-dimensional confocal microscopy we investigated the microstructural arrangement of SAN, AVN, and atrial working myocardium (AWM) in fixed rat heart. AWM exhibited a regular striated arrangement of the extracellular space. In contrast, SAN and AVN had an irregular, reticulated arrangement. AWM, SAN, and AVN tissues were beneath a thin surface layer of tissue that did not obstruct confocal microscopic imaging. Subsequently, we imaged tissues in living rat hearts with real-time fiber-optics confocal microscopy. Fiber-optics confocal microscopy images resembled images acquired with conventional confocal microscopy. We investigated spatial regularity of tissue microstructure from Fourier analysis and second-order image moments. Fourier analysis of fiber-optics confocal microscopy images showed that the spatial regularity of AWM was greater than that of nodal tissues (37.5 ± 5.0% versus 24.3 ± 3.9% for SAN and 23.8 ± 3.7% for AVN; Pfiber-optics confocal microscopy. Application of the approach in pediatric reconstructive heart surgery may reduce risks of injuring nodal tissues.

  14. Development of nodal interface conditions for a PN approximation nodal model

    International Nuclear Information System (INIS)

    Feiz, M.

    1993-01-01

    A relation was developed for approximating higher order odd-moments from lower order odd-moments at the nodal interfaces of a Legendre polynomial nodal model. Two sample problems were tested using different order P N expansions in adjacent nodes. The developed relation proved to be adequate and matched the nodal interface flux accurately. The development allows the use of different order expansions in adjacent nodes, and will be used in a hybrid diffusion-transport nodal model. (author)

  15. Repair of tetralogy of Fallot associated with atrioventricular septal defect.

    Science.gov (United States)

    Tláskal, T; Hucín, B; Kostelka, M; Chaloupecký, V; Marek, J; Tax, P; Janouàek, J; Kuèera, V; Hruda, J; Reich, O; Skovránek, J

    1998-01-01

    Tetralogy of Fallot, when associated with atrioventricular septal defect permitting shunting at ventricular level, represents a complex cyanotic congenital malformation. Experience with surgical repair is limited, and results vary considerably. Between 1984 and 1996, we repaired 14 consecutive patients with this combination seen in our center. Their ages ranged from 8 months to 21 years (median 7.4 years). Six (42.9%) had Down's syndrome. In eight patients the correct diagnosis was made using echocardiography alone. In the remaining six patients, who had previously-constructed arterial shunts and/or suspected pulmonary arterial stenosis, catheterization and angiocardiography were also performed. The repair consisted of double patch closure of the septal defect, reconstruction of two atrioventricular orifices, and relief of pulmonary stenosis at all levels. In five patients with a hypoplastic pulmonary trunk, a monocusp transannular patch (four patients) or an allograft (one patient) was used for restoration of continuity from the right ventricle to the pulmonary arteries. Patch enlargement of one or both pulmonary arteries was necessary in five patients. One patient (7.1%) died early, and another late. The twelve surviving (85.8%) patients have been followed for 1.2-12.5 years after surgery (median 4.9 years, mean 5.9+/-3.9 years). During the follow-up, reoperation was necessary for repair of residual ventricular septal defect and pulmonary regurgitation in two patients, and closure of an atrial septal defect and alteration to left atrioventricular valvar regurgitation in one patient. Seven patients are in class I of the New York Heart Association, four in class II, and one in class III. Tetralogy of Fallot associated with atrioventricular septal defect can be corrected with low mortality and good long-term results. Residual lesions, however, have a tendency to progress, especially when seen in combination. After surgery, all patients need long-term close follow-up.

  16. Echocardiographic effects of changing atrioventricular delay in cardiac resynchronization therapy based on displacement

    DEFF Research Database (Denmark)

    Valeur, Nana; Fritz-Hansen, Thomas; Risum, Niels

    2010-01-01

    In studies showing benefits of cardiac resynchronization therapy (CRT), individual atrioventricular (AV) delays have been optimized using echocardiography. However, the method for AV delay optimization remains controversial....

  17. The angulation of the septal structures impacts ventricular imbalance in atrioventricular septal defects with a common atrioventricular junction.

    Science.gov (United States)

    Ahmad, Zaheer; Lim, Zek; Roman, Kevin; Haw, Marcus; Anderson, Robert H; Vettukattil, Joseph

    2016-02-01

    Multiplanar re-formatting of full-volume three-dimensional echocardiography data sets offers new insights into the morphology of atrioventricular septal defects. We hypothesised that distortion of the alignment between the atrial and ventricular septums results in imbalanced venous return to the ventricles, with consequent proportional ventricular hypoplasia. A single observer evaluated 31 patients, with a mean age of 52.09 months, standard deviation of 55, and with a range from 2 to 264 months, with atrioventricular septal defects, of whom 17 were boys. Ventricular imbalance, observed in nine patients, was determined by two-dimensional assessment, and confirmed at surgical inspection in selected cases when a univentricular strategy was undertaken. Offline analysis using multiplanar re-formatting was performed. A line was drawn though the length of the ventricular septum and a second line along the plane of the atrial septum, taking the angle between these two lines as the atrioventricular septal angle. We compared the angle between 22 patients with adequately sized ventricles, and those with ventricular imbalance undergoing univentricular repair. In the 22 patients undergoing biventricular repair, the septal angle was 0 in 14 patients; the other eight patients having angles ranging from 1 to 36, with a mean angle of 7.4°, and standard deviation of 11.1°.The mean angle in the nine patients with ventricle imbalance was 28.6°, with a standard deviation of 3.04°, and with a range from 26 to 35°. Of those undergoing univentricular repair, two patients died, with angles of 26 and 30°, respectively. The atrioventricular septal angle derived via multiplanar formatting gives important information regarding the degree of ventricular hypoplasia and imbalance. When this angle is above 25°, patients are likely to have ventricular imbalance requiring univentricular repair.

  18. The Nudo, Rollo, Melon codes and nodal correlations

    International Nuclear Information System (INIS)

    Perlado, J.M.; Aragones, J.M.; Minguez, E.; Pena, J.

    1975-01-01

    Analysis of nodal calculation and checking results by the reference reactor experimental data. Nudo code description, adapting experimental data to nodal calculations. Rollo, Melon codes as improvement in the cycle life calculations of albedos, mixing parameters and nodal correlations. (author)

  19. Heterogeneous treatment in the variational nodal method

    International Nuclear Information System (INIS)

    Fanning, T.H.

    1995-01-01

    The variational nodal transport method is reduced to its diffusion form and generalized for the treatment of heterogeneous nodes while maintaining nodal balances. Adapting variational methods to heterogeneous nodes requires the ability to integrate over a node with discontinuous cross sections. In this work, integrals are evaluated using composite gaussian quadrature rules, which permit accurate integration while minimizing computing time. Allowing structure within a nodal solution scheme avoids some of the necessity of cross section homogenization, and more accurately defines the intra-nodal flux shape. Ideally, any desired heterogeneity can be constructed within the node; but in reality, the finite set of basis functions limits the practical resolution to which fine detail can be defined within the node. Preliminary comparison tests show that the heterogeneous variational nodal method provides satisfactory results even if some improvements are needed for very difficult, configurations

  20. Atrioventricular junction (AVJ) motion tracking: a software tool with ITK/VTK/Qt.

    Science.gov (United States)

    Pengdong Xiao; Shuang Leng; Xiaodan Zhao; Hua Zou; Ru San Tan; Wong, Philip; Liang Zhong

    2016-08-01

    The quantitative measurement of the Atrioventricular Junction (AVJ) motion is an important index for ventricular functions of one cardiac cycle including systole and diastole. In this paper, a software tool that can conduct AVJ motion tracking from cardiovascular magnetic resonance (CMR) images is presented by using Insight Segmentation and Registration Toolkit (ITK), The Visualization Toolkit (VTK) and Qt. The software tool is written in C++ by using Visual Studio Community 2013 integrated development environment (IDE) containing both an editor and a Microsoft complier. The software package has been successfully implemented. From the software engineering practice, it is concluded that ITK, VTK, and Qt are very handy software systems to implement automatic image analysis functions for CMR images such as quantitative measure of motion by visual tracking.

  1. Echocardiographic effects of changing atrioventricular delay in cardiac resynchronization therapy based on displacement

    DEFF Research Database (Denmark)

    Valeur, Nana; Fritz-Hansen, Thomas; Risum, Niels

    2010-01-01

    In studies showing benefits of cardiac resynchronization therapy (CRT), individual atrioventricular (AV) delays have been optimized using echocardiography. However, the method for AV delay optimization remains controversial.......In studies showing benefits of cardiac resynchronization therapy (CRT), individual atrioventricular (AV) delays have been optimized using echocardiography. However, the method for AV delay optimization remains controversial....

  2. Coronary sinus and atrioventricular groove avulsion after motor vehicle crash

    Directory of Open Access Journals (Sweden)

    Bradley M Dennis

    2014-01-01

    Full Text Available Simultaneous cardiac and pericardial rupture from blunt chest trauma is a highly lethal combination with rarely reported survival. We report of a case of young patient with a right atrioventricular groove injury, pericardial rupture and a unique description of a coronary sinus avulsion following blunt chest trauma. Rapid recognition of this injury is crucial to patient survival, but traditional diagnostic adjuncts such as ultrasound, echocardiography and computed tomography are often unhelpful. Successful repair of these injuries requires high suspicion of injury, early cardiac surgery involvement of and possible even placement of the patient on cardiopulmonary bypass.

  3. Fallot's tetralogy in combination with an open common atrioventricular canal

    International Nuclear Information System (INIS)

    Alekyan, B.G.; Dvinyaninova, N.B.; Chiaureli, M.R.; Arzhanukhina, S.Yu.

    1987-01-01

    The methods and clinics of diagnostics of Fallot tetrad (FT) combined with the opened general atrioventricular canal (AVC) of the heart are described on the basis of observation of a 6.5-year old patient and analysis of literary data. On the basis of studying clinical data, electro-, phono-, echocardiography and roentgenography, as well as heart catheterization and angiocardiography the conclusion is made that nowadays the most informative method of diagnostics of FT and AVC combination before angiocardiography is a dimer echocardiography which permits to diagnoze AVC. Angiocardiographic study proves this diagnosis and gives a precise anotomical picture of various components of this combination of heart failure

  4. Mirror Image Gerbode or Partial Atrioventricular Canal Defect?

    Directory of Open Access Journals (Sweden)

    Cem Ariturk

    2015-12-01

    Full Text Available Gebode defect, that can accurately be treated surgical repair, is defined as a true communication between left ventricle and right atrium. A 74-year-old woman with a worsening history of ortophnea and peripheral edema was hospitalised. A communication between right atrium and left ventricle was diagnosed using transeusophageal echocardiography. The defect was repaired and mitral valve was replaced with a biologic valve. It would be beter to tailor surgical strategy for each case with atrioventricular canal defect after preoperative transeusophageal echocardiography and peroperative direct sight.

  5. Nodal pricing in a coupled electricity market

    OpenAIRE

    Bjørndal, Endre; Bjørndal, Mette; Cai, Hong

    2014-01-01

    This paper investigates a pricing model for an electricity market with a hybrid congestion management method, i.e. part of the system applies a nodal pricing scheme and the rest applies a zonal pricing scheme. The model clears the zonal and nodal pricing areas simultaneously. The nodal pricing area is affected by the changes in the zonal pricing area since it is directly connected to the zonal pricing area by commercial trading. The model is tested on a 13-node power system. Within the area t...

  6. Atrioventricular and Interventricular Groove and Septal Extension of Right Sinus of Valsalva Aneurysm: A Rare Cause of Complete Heart Block

    International Nuclear Information System (INIS)

    Khan, J.A.; Hussain, M.; Rizvi, N.H.; Fehmi, N.; Hussain, A.; Sial, J.A.

    2013-01-01

    A 26 years old male presented with vertigo and history of fall. The electrocardiogram revealed 2:1 second-degree heart block and later progression to complete heart block. Transthoracic echocardiography revealed aneurysm at the site of ascending aorta and computed tomographic scan showed an aneurysm of right sinsus of Valsalva extending into right atrioventricular and interventricular groove and causing complete heart block by compression on the conduction system. He also suffered from lymph node tuberculosis. This case report is unique because of rare presentation as complete heart block. (author)

  7. A comparison of two nodal codes : Advanced nodal code (ANC) and analytic function expansion nodal (AFEN) code

    International Nuclear Information System (INIS)

    Chung, S.K.; Hah, C.J.; Lee, H.C.; Kim, Y.H.; Cho, N.Z.

    1996-01-01

    Modern nodal methods usually employs the transverse integration technique in order to reduce a multi-dimensional diffusion equation to one-dimensional diffusion equations. The use of the transverse integration technique requires two major approximations such as a transverse leakage approximation and a one-dimensional flux approximation. Both the transverse leakage and the one-dimensional flux are approximated by polynomials. ANC (Advanced Nodal Code) developed by Westinghouse employs a modern nodal expansion method for the flux calculation, the equivalence theory for the homogenization error reduction and a group theory for pin power recovery. Unlike the conventional modern nodal methods, AFEN (Analytic Function Expansion Nodal) method expands homogeneous flux distributions within a node into non-separable analytic basis functions, which eliminate two major approximations of the modern nodal methods. A comparison study of AFEN with ANC has been performed to see the applicability of AFEN to commercial PWR and different types of reactors such as MOX fueled reactor. The qualification comparison results demonstrate that AFEN methodology is accurate enough to apply for commercial PWR analysis. The results show that AFEN provides very accurate results (core multiplication factor and assembly power distribution) for cores that exhibit strong flux gradients as in a MOX loaded core. (author)

  8. A nodal model for the simulation of a PWR core

    International Nuclear Information System (INIS)

    Souza Pinto, R. de.

    1981-06-01

    A computer program FORTRAN language was developed to simulate the neutronic and thermal-hydraulic transient behaviour of a PWR reactor core. The reator power is calculated using a point kinectics model with six groups of delayed neutron precursors. The fission product decay heat was considered assuming three effective decay heat groups. A nodal model was employed for the treatment of heat transfer in the fuel rod, with integration of the heat equation by the lumped parameter technique. Axial conduction was neglected. A single-channel nodal model was developed for the thermo-hydrodynamic simulation using mass and energy conservation equations for the control volumes. The effect of the axial pressure variation was neglected. The computer program was tested, with good results, through the simulation of the transient behaviour of postulated accidents in a typical PWR. (Author) [pt

  9. Accidente cerebrovascular isquémico asociado con ablación por radiofrecuencia de reentrada nodal Ischemic stroke associated with radio frequency ablation for nodal reentry

    Directory of Open Access Journals (Sweden)

    Juan C Díaz Martínez

    2010-04-01

    Full Text Available La taquicardia por reentrada nodal es la causa más común de taquicardia supraventricular paroxística; en aquellos pacientes en quienes el manejo farmacológico no es efectivo o deseado la ablación por radiofrecuencia es un excelente método terapéutico dada su alta tasa de curación. Aunque en términos generales dichos procedimientos son rápidos y seguros, se han descrito varias complicaciones entre las que sobresale el accidente cerebrovascular isquémico. Se presenta el caso de una paciente de 41 años con episodios de taquicardia por reentrada nodal a repetición, que fue llevada a ablación por radiofrecuencia. En el post-operatorio inmediato se evidenció déficit neurológico focal con isquemia en el territorio de la arteria cerebral media derecha, tras lo cual se realizó angiografía con intento de angioplastia y abxicimab y posteriormente infusión local de activador de plasminógeno tisular (rtPA con adecuado resultado clínico y angiográfico.Atrioventricular nodal reentry tachycardia is the most common type of paroxismal supraventricular tachycardia. In those patients in whom drug therapy is not effective or not desired, radio frequency ablation is an excellent therapeutic method. Although overall these procedures are fast and safe, several complications among which ischemic stroke stands out, have been reported. We present the case of a 41 year old female patient with repetitive episodes of tachycardia due to nodal reentry who was treated with radiofrequency ablation. Immediately after the procedure she presented focal neurologic deficit consistent with ischemic stroke in the right medial cerebral artery territory. Angiography with angioplastia and abxicimab was performed and then tissue plasminogen activator (rtPA was locally infused, with appropriate clinical and angiographic outcome.

  10. Maternal Nodal inversely affects NODAL and STOX1 expression in the fetal placenta

    Directory of Open Access Journals (Sweden)

    Hari Krishna Thulluru

    2013-08-01

    Full Text Available Nodal, a secreted signaling protein from the TGFβ-super family plays a vital role during early embryonic development. Recently, it was found that maternal decidua-specific Nodal knockout mice show intrauterine growth restriction (IUGR and preterm birth. As the chromosomal location of NODAL is in the same linkage area as the susceptibility gene STOX1, associated with the familial form of early-onset, IUGR-complicated pre-eclampsia, their potential maternal-fetal interaction was investigated. Pre-eclamptic mothers with children who carried the STOX1 susceptibility allele themselves all carried the NODAL H165R SNP, which causes a 50% reduced activity. Surprisingly, in decidua Nodal knockout mice the fetal placenta showed up-regulation of STOX1 and NODAL expression. Conditioned media of human first trimester decidua and a human endometrial stromal cell line (T-HESC treated with siRNAs against NODAL or carrying the H165R SNP were also able to induce NODAL and STOX1 expression when added to SGHPL-5 first trimester extravillous trophoblast cells. Finally, a human TGFß-BMP-Signaling-Pathway PCR-Array on decidua and the T-HESC cell line with Nodal knockdown revealed upregulation of Activin-A, which was confirmed in conditioned media by ELISA. We show that maternal decidua Nodal knockdown gives upregulation of NODAL and STOX1 mRNA expression in fetal extravillous trophoblast cells, potentially via upregulation of Activin-A in the maternal decidua. As both Activin-A and Nodal have been implicated in pre-eclampsia, being increased in serum of pre-eclamptic women and upregulated in pre-eclamptic placentas respectively, this interaction at the maternal-fetal interface might play a substantial role in the development of pre-eclampsia.

  11. Quantum oscillations in nodal line systems

    Science.gov (United States)

    Yang, Hui; Moessner, Roderich; Lim, Lih-King

    2018-04-01

    We study signatures of magnetic quantum oscillations in three-dimensional nodal line semimetals at zero temperature. The extended nature of the degenerate bands can result in a Fermi surface geometry with topological genus one, as well as a Fermi surface of electron and hole pockets encapsulating the nodal line. Moreover, the underlying two-band model to describe a nodal line is not unique, in that there are two classes of Hamiltonian with distinct band topology giving rise to the same Fermi-surface geometry. After identifying the extremal cyclotron orbits in various magnetic field directions, we study their concomitant Landau levels and resulting quantum oscillation signatures. By Landau-fan-diagram analyses, we extract the nontrivial π Berry phase signature for extremal orbits linking the nodal line.

  12. Sensitivity of SBLOCA analysis to model nodalization

    International Nuclear Information System (INIS)

    Lee, C.; Ito, T.; Abramson, P.B.

    1983-01-01

    The recent Semiscale test S-UT-8 indicates the possibility for primary liquid to hang up in the steam generators during a SBLOCA, permitting core uncovery prior to loop-seal clearance. In analysis of Small Break Loss of Coolant Accidents with RELAP5, it is found that resultant transient behavior is quite sensitive to the selection of nodalization for the steam generators. Although global parameters such as integrated mass loss, primary inventory and primary pressure are relatively insensitive to the nodalization, it is found that the predicted distribution of inventory around the primary is significantly affected by nodalization. More detailed nodalization predicts that more of the inventory tends to remain in the steam generators, resulting in less inventory in the reactor vessel and therefore causing earlier and more severe core uncovery

  13. Twisted Vector Bundles on Pointed Nodal Curves

    Indian Academy of Sciences (India)

    Abstract. Motivated by the quest for a good compactification of the moduli space of -bundles on a nodal curve we establish a striking relationship between Abramovich's and Vistoli's twisted bundles and Gieseker vector bundles.

  14. Atrioventricular depolarization differences identify coronary artery anomalies in Kawasaki disease.

    Science.gov (United States)

    Cortez, Daniel; Sharma, Nandita; Jone, Pei-Ni

    2017-03-01

    Kawasaki disease (KD) is the leading cause of acquired heart disease in children. Signal average electrocardiogram changes in patients during the acute phase of KD with coronary artery anomalies (CAA) include depolarization changes. We set out to determine if 12-lead-derived atrioventricular depolarization differences can identify CAA in patients with KD. A blinded, retrospective case-control study of patients with KD was performed. Deep Q waves, corrected QT-intervals (QTc), spatial QRS-T angles, T-wave vector magnitudes (RMS-T), and a novel parameter for assessment of atrioventricular depolarization difference (the spatial PR angle) and a two dimensional PR angle were assessed. Comparisons between groups were performed to test for significant differences. One hundred one patients with KD were evaluated, with 68 having CAA (67.3%, mean age 3.6 ± 3.0 years, 82.6% male), and 32 without CAA (31.7%, mean age 2.7 ± 3.2 years, 70.4% male). The spatial PR angle significantly discriminated KD patients with CAA from those without, 59.7° ± 31.1° versus 41.6° ± 11.5° (p differences, measured by the spatial or two dimensional PR angle differentiate KD patients with CAA versus those without. © 2016 Wiley Periodicals, Inc.

  15. The NODAL system for the SPS

    International Nuclear Information System (INIS)

    Crowley-Milling, M.C.; Shering, G.C.

    1978-01-01

    A comprehensive description is given of the NODAL system used for computer control of the CERN Super-Proton Synchrotron. Details are given of NODAL, a high-level programming language based on FOCAL and SNOBOL4, designed for interactive use. It is shown how this interpretive language is used with a network of computers and how it can be extended by adding machine-code modules. The report updates and replaces an earlier one published in 1974. (Auth.)

  16. Nodal coupling by response matrix principles

    International Nuclear Information System (INIS)

    Ancona, A.; Becker, M.; Beg, M.D.; Harris, D.R.; Menezes, A.D.; VerPlanck, D.M.; Pilat, E.

    1977-01-01

    The response matrix approach has been used in viewing a reactor node in isolation and in characterizing the node by reflection and trans-emission factors. These are then used to generate invariant imbedding parameters, which in turn are used in a nodal reactor simulator code to compute core power distributions in two and three dimensions. Various nodal techniques are analyzed and converted into a single invariant imbedding formalism

  17. Magnonic triply-degenerate nodal points

    Science.gov (United States)

    Owerre, S. A.

    2017-12-01

    We generalize the concept of triply-degenerate nodal points to non-collinear antiferromagnets. Here, we introduce this concept to insulating quantum antiferromagnets on the decorated honeycomb lattice, with spin-1 bosonic quasiparticle excitations known as magnons. We demonstrate the existence of magnonic surface states with constant energy contours that form pairs of magnonic arcs connecting the surface projection of the magnonic triple nodal points. The quasiparticle excitations near the triple nodal points represent three-component bosons beyond that of magnonic Dirac, Weyl, and nodal-line cases. They can be regarded as a direct reflection of the intrinsic spin carried by magnons. Furthermore, we show that the magnonic triple nodal points can split into magnonic Weyl points, as the system transits from a non-collinear spin structure to a non-coplanar one with a non-zero scalar spin chirality. Our results not only apply to insulating antiferromagnets, but also provide a platform to seek for triple nodal points in metallic antiferromagnets.

  18. Electrocardiographic characteristics of atrioventricular block induced by tilt testing.

    Science.gov (United States)

    Zyśko, Dorota; Gajek, Jacek; Koźluk, Edward; Mazurek, Walentyna

    2009-02-01

    The electrocardiographic (ECG) characteristics of atrioventricular (AV) block during reflex syncope may be unique due to the presence of hypervagotonia. The aim of the present study was to define the ECG characteristics of the AV block induced by neurocardiogenic reflex provoked by tilt testing (TT). A series of 31 patients with presumed vasovagal syncope and AV block provoked by TT was studied. The duration of PP and PR interval, AV block grade and type, concomitant arrhythmias, and timing of the AV block occurrence were assessed. The AV block occurred at TT termination in 26 patients, in the recovery in 4 patients, and in both periods in 1 patient. Atrioventricular block was preceded by sinus slowing, and sinus rhythm during AV block was slow and instable. Mobitz I, 2:1 second-degree AV block, and advanced second-degree AV block were recognized in 35.5, 48.4, and 67.8% of patients, respectively. Third-degree AV block was diagnosed in 41.9% of patients. Twenty-one patients had at least two AV block forms. The most prevalent concomitant arrhythmia was junctional escape rhythm (61.3%). (i) The occurrence of the AV block during neurocardiogenic reaction induced by TT is always preceded by sinus rhythm slowing and usually by PR interval prolongation. (ii) The AV block provoked by TT usually occurs at TT termination, but may occur even in the recovery period in a supine position. Sometimes the AV block may be present both at TT termination and during the recovery period.

  19. The analytic nodal method in cylindrical geometry

    International Nuclear Information System (INIS)

    Prinsloo, Rian H.; Tomasevic, Djordje I.

    2008-01-01

    Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem

  20. Encapsulation of nodal segments of lobelia chinensis

    Directory of Open Access Journals (Sweden)

    Weng Hing Thong

    2015-04-01

    Full Text Available Lobelia chinensis served as an important herb in traditional chinese medicine. It is rare in the field and infected by some pathogens. Therefore, encapsulation of axillary buds has been developed for in vitro propagation of L. chinensis. Nodal explants of L. chinensis were used as inclusion materials for encapsulation. Various combinations of calcium chloride and sodium alginate were tested. Encapsulation beads produced by mixing 50 mM calcium chloride and 3.5% sodium alginate supported the optimal in vitro conversion potential. The number of multiple shoots formed by encapsulated nodal segments was not significantly different from the average of shoots produced by non-encapsulated nodal segments. The encapsulated nodal segments regenerated in vitro on different medium. The optimal germination and regeneration medium was Murashige-Skoog medium. Plantlets regenerated from the encapsulated nodal segments were hardened, acclimatized and established well in the field, showing similar morphology with parent plants. This encapsulation technology would serve as an alternative in vitro regeneration system for L. chinensis.

  1. Structural and functional alterations in the atrioventricular node and atrioventricular ring tissue in ischaemia-induced heart failure.

    Science.gov (United States)

    Yanni, Joseph; Maczewski, Michal; Mackiewicz, Urszula; Siew, Samuel; Fedorenko, Olga; Atkinson, Andrew; Price, Marcus; Beresewicz, Andrzej; Anderson, Robert H; Boyett, Mark R; Dobrzynski, Halina

    2014-07-01

    Heart failure (HF) causes dysfunction of the atrioventricular node (AVN) - first or second-degree heart block is a risk factor for sudden cardiac death in HF patients. The aim of the study was to determine if HF causes remodelling of the AVN and right atrioventricular ring (RAVR). HF was induced in rats (n=4) by ligation of the proximal left coronary artery, which resulted in a large infarct of the left ventricle. Sham-operated rats (n=4) were used as controls. Eight weeks after surgery, functional experiments were performed and the hearts were frozen. The body weight of HF rats was similar to control rats, but the mean heart weight of HF rats was significantly enlarged. In HF rats compared to controls, the left ventricle was dilated, left ventricular end-diastolic pressure elevated (21.0 ± 0.6 and 5.4 ± 0.2 mm Hg), left ventricular ejection fraction reduced (0.2 ± 0.02 and 0.5 ± 0.02) and left ventricular end-systolic pressure reduced (102 ± 4.2 and 127 ± 3.1 mm Hg). In HF rats, the in vivo and in vitro PR intervals were increased (41% and 20%), as was the Wenckebach cycle length, indicative of AVN dysfunction. The collagen content was significantly increased in the AVN and RAVR indicating fibrosis. Immunolabelling of caveolin3 (cell membrane marker) showed that there was hypertrophy in HF (cell diameter was increased by 63%, 39% in AVN, RAVR). The TUNEL assay showed that the myocytes of the AVN and RAVR in HF undergo apoptotic cell death. Immunolabelling showed that expression of HCN4 was significantly decreased in the AVN and RAVR (43% and 47%) in HF. We conclude that in HF there is remodelling of the AVN and RAVR and this remodelling may explain the AVN dysfunction.

  2. Complex models of nodal nuclear data

    International Nuclear Information System (INIS)

    Dufek, Jan

    2011-01-01

    During the core simulations, nuclear data are required at various nodal thermal-hydraulic and fuel burnup conditions. The nodal data are also partially affected by thermal-hydraulic and fuel burnup conditions in surrounding nodes as these change the neutron energy spectrum in the node. Therefore, the nodal data are functions of many parameters (state variables), and the more state variables are considered by the nodal data models the more accurate and flexible the models get. The existing table and polynomial regression models, however, cannot reflect the data dependences on many state variables. As for the table models, the number of mesh points (and necessary lattice calculations) grows exponentially with the number of variables. As for the polynomial regression models, the number of possible multivariate polynomials exceeds the limits of existing selection algorithms that should identify a few dozens of the most important polynomials. Also, the standard scheme of lattice calculations is not convenient for modelling the data dependences on various burnup conditions since it performs only a single or few burnup calculations at fixed nominal conditions. We suggest a new efficient algorithm for selecting the most important multivariate polynomials for the polynomial regression models so that dependences on many state variables can be considered. We also present a new scheme for lattice calculations where a large number of burnup histories are accomplished at varied nodal conditions. The number of lattice calculations being performed and the number of polynomials being analysed are controlled and minimised while building the nodal data models of a required accuracy. (author)

  3. A rare form of atrioventricular septal defect with severe subaortic stenosis.

    Science.gov (United States)

    Venugopalan, P; Agarwal, A K; Reyes, Z

    2001-06-01

    An unusual form of atrioventricular septal defect associated with severe subaortic obstruction is reported in a neonate who presented with intractable cardiac failure. The baby had a large defect in the atrioventricular septum allowing communication from the left ventricle to the right atrium, without interatrial or interventricular communication, and a cleft anterior mitral leaflet. The baby expired despite palliative surgery performed to bypass the subaortic stenosis.

  4. Nodal Structure of the Electronic Wigner Function

    DEFF Research Database (Denmark)

    Schmider, Hartmut; Dahl, Jens Peder

    1996-01-01

    On the example of several atomic and small molecular systems, the regular behavior of nodal patterns in the electronic one-particle reduced Wigner function is demonstrated. An expression found earlier relates the nodal pattern solely to the dot-product of the position and the momentum vector......, if both arguments are large. An argument analogous to the ``bond-oscillatory principle'' for momentum densities links the nuclear framework in a molecule to an additional oscillatory term in momenta parallel to bonds. It is shown that these are visible in the Wigner function in terms of characteristic...

  5. Complete atrioventricular block in acute coronary syndrome: prevalence, characterisation and implication on outcome.

    Science.gov (United States)

    Aguiar Rosa, Silvia; Timóteo, Ana Teresa; Ferreira, Lurdes; Carvalho, Ramiro; Oliveira, Mario; Cunha, Pedro; Viveiros Monteiro, André; Portugal, Guilherme; Almeida Morais, Luis; Daniel, Pedro; Cruz Ferreira, Rui

    2018-04-01

    The aim was to characterise acute coronary syndrome patients with complete atrioventricular block and to assess the effect on outcome. Patients admitted with acute coronary syndrome were divided according to the presence of complete atrioventricular block: group 1, with complete atrioventricular block; group 2, without complete atrioventricular block. Clinical, electrocardiographic and echocardiographic characteristics and prognosis during one year follow-up were compared between the groups. Among 4799 acute coronary syndrome patients admitted during the study period, 91 (1.9%) presented with complete atrioventricular block. At presentation, group 1 patients presented with lower systolic blood pressure, higher Killip class and incidence of syncope. In group 1, 86.8% presented with ST-segment elevation myocardial infarction (STEMI), and inferior STEMI was verified in 79.1% of patients in group 1 compared with 21.9% in group 2 ( Pblock was observed in 7.3% in contrast to 2.5% in patients submitted to primary percutaneous coronary intervention ( Pblock was an independent predictor of hospital mortality (odds ratio 3.671; P=0.045). There was no significant difference in mortality at one-year follow-up between the study groups. Complete atrioventricular block conferred a worse outcome during hospitalisation, including a higher incidence of cardiogenic shock, ventricular arrhythmias and death.

  6. Isospectral graphs with identical nodal counts

    International Nuclear Information System (INIS)

    Oren, Idan; Band, Ram

    2012-01-01

    According to a recent conjecture, isospectral objects have different nodal count sequences (Gnutzmann et al 2005 J. Phys. A: Math. Gen. 38 8921–33). We study generalized Laplacians on discrete graphs, and use them to construct the first non-trivial counterexamples to this conjecture. In addition, these examples demonstrate a surprising connection between isospectral discrete and quantum graphs. (paper)

  7. Comparison of neutronic transport equation resolution nodal methods

    International Nuclear Information System (INIS)

    Zamonsky, O.M.; Gho, C.J.

    1990-01-01

    In this work, some transport equation resolution nodal methods are comparatively studied: the constant-constant (CC), linear-nodal (LN) and the constant-quadratic (CQ). A nodal scheme equivalent to finite differences has been used for its programming, permitting its inclusion in existing codes. Some bidimensional problems have been solved, showing that linear-nodal (LN) are, in general, obtained with accuracy in CPU shorter times. (Author) [es

  8. [Late arrhythmias in the operated interatrial communication. Analysis of sinus node function and the conduction pathways by His bundle electrocardiography].

    Science.gov (United States)

    Ramírez, A; Gil, M; Martínez Ríos, M A; Cárdenas, M; Pliego, J; Zamora, C; Mata, L A

    1982-01-01

    Four hundred patients with atrial septal defect treated surgically were reviewed. Thirty five (8.7%) developed arrhytmias post-surgery which persisted for over a year. Sinus bradycardia was found in 10 patients, nodal rhythm in 21, and atrial fibrilation and flutter in 4 patients. Thirty five per cent of the patients with late arrhythmias developed related symptomatology. In 14 patients the function of the sinus node was studied with electrical stimulation of the atrium and with His registry. The interatrial conduction time, AV node and His Purkinje were analized employing various stimulation frequencies. All the cases studied had normal intra-atrial conduction; the response of the atrio-ventricular node to increasing frequencies was normal, an the intraventricular conduction remained constant. In 8 patients (52%), alterations of the sinus node were found; these consisted of prolonged post-stimulation pauses, Wenckebach's type sinoatrial block and suppression of sinus automatism employing vagal procedures or through electrical stimulation. A patient with severe bradycardia detected by dynamic electrocardiography had to be treated with a permanent pacemaker. We confirm that these arrhytmias are not produced by lesions of the internodal tracts, and that an alteration of the sinus node is frequent without a concomitant lesion of the intraventricular pathway. The lesion to the nutrient artery could be due to trauma and/or surgically induced. The response to anticholinergic drugs was good. Prolonged observation of these patients could increase the morbility of these arrythmias and raise doubts of the surgical indications in cases with moderate hemodynamic repercussion.

  9. Status on development and verification of reactivity initiated accident analysis code for PWR (NODAL3)

    International Nuclear Information System (INIS)

    Peng Hong Liem; Surian Pinem; Tagor Malem Sembiring; Tran Hoai Nam

    2015-01-01

    A coupled neutronics thermal-hydraulics code NODAL3 has been developed based on the nodal few-group neutron diffusion theory in 3-dimensional Cartesian geometry for a typical pressurized water reactor (PWR) static and transient analyses, especially for reactivity initiated accidents (RIA). The spatial variables are treated by using a polynomial nodal method (PNM) while for the neutron dynamic solver the adiabatic and improved quasi-static methods are adopted. A simple single channel thermal-hydraulics module and its steam table is implemented into the code. Verification works on static and transient benchmarks are being conducting to assess the accuracy of the code. For the static benchmark verification, the IAEA-2D, IAEA-3D, BIBLIS and KOEBERG light water reactor (LWR) benchmark problems were selected, while for the transient benchmark verification, the OECD NEACRP 3-D LWR Core Transient Benchmark and NEA-NSC 3-D/1-D PWR Core Transient Benchmark (Uncontrolled Withdrawal of Control Rods at Zero Power). Excellent agreement of the NODAL3 results with the reference solutions and other validated nodal codes was confirmed. (author)

  10. Sensitivity analysis of MIDAS tests using SPACE code. Effect of nodalization

    International Nuclear Information System (INIS)

    Eom, Shin; Oh, Seung-Jong; Diab, Aya

    2018-01-01

    The nodalization sensitivity analysis for the ECCS (Emergency Core Cooling System) bypass phe�nomena was performed using the SPACE (Safety and Performance Analysis CodE) thermal hydraulic analysis computer code. The results of MIDAS (Multi-�dimensional Investigation in Downcomer Annulus Simulation) test were used. The MIDAS test was conducted by the KAERI (Korea Atomic Energy Research Institute) for the performance evaluation of the ECC (Emergency Core Cooling) bypass phenomenon in the DVI (Direct Vessel Injection) system. The main aim of this study is to examine the sensitivity of the SPACE code results to the number of thermal hydraulic channels used to model the annulus region in the MIDAS experiment. The numerical model involves three nodalization cases (4, 6, and 12 channels) and the result show that the effect of nodalization on the bypass fraction for the high steam flow rate MIDAS tests is minimal. For computational efficiency, a 4 channel representation is recommended for the SPACE code nodalization. For the low steam flow rate tests, the SPACE code over-�predicts the bypass fraction irrespective of the nodalization finesse. The over-�prediction at low steam flow may be attributed to the difficulty to accurately represent the flow regime in the vicinity of the broken cold leg.

  11. Sensitivity analysis of MIDAS tests using SPACE code. Effect of nodalization

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Shin; Oh, Seung-Jong; Diab, Aya [KEPCO International Nuclear Graduate School (KINGS), Ulsan (Korea, Republic of). Dept. of NPP Engineering

    2018-02-15

    The nodalization sensitivity analysis for the ECCS (Emergency Core Cooling System) bypass phe�nomena was performed using the SPACE (Safety and Performance Analysis CodE) thermal hydraulic analysis computer code. The results of MIDAS (Multi-�dimensional Investigation in Downcomer Annulus Simulation) test were used. The MIDAS test was conducted by the KAERI (Korea Atomic Energy Research Institute) for the performance evaluation of the ECC (Emergency Core Cooling) bypass phenomenon in the DVI (Direct Vessel Injection) system. The main aim of this study is to examine the sensitivity of the SPACE code results to the number of thermal hydraulic channels used to model the annulus region in the MIDAS experiment. The numerical model involves three nodalization cases (4, 6, and 12 channels) and the result show that the effect of nodalization on the bypass fraction for the high steam flow rate MIDAS tests is minimal. For computational efficiency, a 4 channel representation is recommended for the SPACE code nodalization. For the low steam flow rate tests, the SPACE code over-�predicts the bypass fraction irrespective of the nodalization finesse. The over-�prediction at low steam flow may be attributed to the difficulty to accurately represent the flow regime in the vicinity of the broken cold leg.

  12. [Estimation of the atrioventricular time interval by pulse Doppler in the normal fetal heart].

    Science.gov (United States)

    Hamela-Olkowska, Anita; Dangel, Joanna

    2009-08-01

    To assess normative values of the fetal atrioventricular (AV) time interval by pulse-wave Doppler methods on 5-chamber view. Fetal echocardiography exams were performed using Acuson Sequoia 512 in 140 singleton fetuses at 18 to 40 weeks of gestation with sinus rhythm and normal cardiac and extracardiac anatomy. Pulsed Doppler derived AV intervals were measured from left ventricular inflow/outflow view using transabdominal convex 3.5-6 MHz probe. The values of AV time interval ranged from 100 to 150 ms (mean 123 +/- 11.2). The AV interval was negatively correlated with the heart rhythm (page of gestation (p=0.007). However, in the same subgroup of the fetal heart rate there was no relation between AV intervals and gestational age. Therefore, the AV intervals showed only the heart rate dependence. The 95th percentiles of AV intervals according to FHR ranged from 135 to 148 ms. 1. The AV interval duration was negatively correlated with the heart rhythm. 2. Measurement of AV time interval is easy to perform and has a good reproducibility. It may be used for the fetal heart block screening in anti-Ro and anti-La positive pregnancies. 3. Normative values established in the study may help obstetricians in assessing fetal abnormalities of the AV conduction.

  13. Características morfológicas y posibles implicaciones clínicas de las arterias nodales Morphological characteristics and potential clinical implications of nodal arteries

    Directory of Open Access Journals (Sweden)

    Luis E Ballesteros

    2010-12-01

    Full Text Available La expresión morfológica de las arterias nodales es relevante en el diagnóstico y manejo de eventos clínicos y en abordajes quirúrgicos del corazón. Se estudiaron 88 arterias nodales de corazones obtenidos como material de autopsia. Las arterias coronarias se inyectaron con resina poliéster pigmentada de color rojo. Se registraron las formas de presentación de las arterias nodales y sus características morfométricas. La arteria del nodo sinoatrial se originó de la coronaria derecha en 52 casos (59,1%, de la circunfleja en 33 corazones (37,35% y de ambas en 3 (3,4%. Su calibre proximal fue de 1,31 mm (± 0,3, correspondiente a las arterias originadas de la coronaria derecha de 1,25 mm (± 0,3 mientras que las que se originaron de la arteria circunfleja obtuvieron un calibre de 1,42 mm (± 0,3, siendo esta diferencia significativa (p= 0,01. Se originó con mayor frecuencia en el tercio anteromedial, tanto de la coronaria derecha como de la circunfleja (54,6% y 61,2% respectivamente. En su segmento final cruzó por delante de la desembocadura de la vena cava superior en la mayoría de los casos (44%, mientras que en 22 corazones (24,5% cursó alrededor de la cava. Se observó arteria en forma de «S» en 14 casos (15,9% del total de la muestra y 42,4% de las originadas de la arteria circunfleja. La arteria del nodo atrioventricular se originó del segmento en «U» invertida de la coronaria derecha, al nivel de la cruz cardiaca, en 81 corazones (92%, y presentó un calibre proximal de 1,06 mm (± 0,22. Con relación al calibre y al origen se evidencian hallazgos que coinciden con estudios previos. Se destaca la alta prevalencia de la arteria en forma de «S» y de la trayectoria de la arteria sinoatrial alrededor de la vena cava superior.The morphological expression of nodal arteries is important in the diagnosis and management of cardiac clinical events and surgical approaches. 88 nodal arteries of hearts obtained from autopsies were

  14. Pathology of nodal marginal zone lymphomas.

    Science.gov (United States)

    Pileri, Stefano; Ponzoni, Maurilio

    Nodal marginal zone B cell lymphomas (NMZLs) are a rare group of lymphoid disorders part of the spectrum of marginal zone B-cell lymphomas, which encompass splenic marginal one B-cell lymphoma (SMZL) and extra nodal marginal zone of B-cell lymphoma (EMZL), often of MALT-type. Two clinicopathological forms of NMZL are recognized: adult-type and pediatric-type, respectively. NMZLs show overlapping features with other types of MZ, but distinctive features as well. In this review, we will focus on the salient distinguishing features of NMZL mostly under morphological/immunophenotypical/molecular perspectives in views of the recent acquisitions and forthcoming updated 2016 WHO classification of lymphoid malignancies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Quantum anomalies in nodal line semimetals

    Science.gov (United States)

    Burkov, A. A.

    2018-04-01

    Topological semimetals are a new class of condensed matter systems with nontrivial electronic structure topology. Their unusual observable properties may often be understood in terms of quantum anomalies. In particular, Weyl and Dirac semimetals, which have point band-touching nodes, are characterized by the chiral anomaly, which leads to the Fermi arc surface states, anomalous Hall effect, negative longitudinal magnetoresistance, and planar Hall effect. In this paper, we explore analogous phenomena in nodal line semimetals. We demonstrate that such semimetals realize a three-dimensional analog of the parity anomaly, which is a known property of two-dimensional Dirac semimetals arising, for example, on the surface of a three-dimensional topological insulator. We relate one of the characteristic properties of nodal line semimetals, namely, the drumhead surface states, to this anomaly, and derive the field theory, which encodes the corresponding anomalous response.

  16. Temporal quadratic expansion nodal Green's function method

    International Nuclear Information System (INIS)

    Liu Cong; Jing Xingqing; Xu Xiaolin

    2000-01-01

    A new approach is presented to efficiently solve the three-dimensional space-time reactor dynamics equation which overcomes the disadvantages of current methods. In the Temporal Quadratic Expansion Nodal Green's Function Method (TQE/NGFM), the Quadratic Expansion Method (QEM) is used for the temporal solution with the Nodal Green's Function Method (NGFM) employed for the spatial solution. Test calculational results using TQE/NGFM show that its time step size can be 5-20 times larger than that of the Fully Implicit Method (FIM) for similar precision. Additionally, the spatial mesh size with NGFM can be nearly 20 times larger than that using the finite difference method. So, TQE/NGFM is proved to be an efficient reactor dynamics analysis method

  17. Acceleration of the FERM nodal program

    International Nuclear Information System (INIS)

    Nakata, H.

    1985-01-01

    It was tested three acceleration methods trying to reduce the number of outer iterations in the FERM nodal program. The results obtained indicated that the Chebychev polynomial acceleration method with variable degree results in a economy of 50% in the computer time. Otherwise, the acceleration method by source asymptotic extrapolation or by zonal rebalance did not result in economy of the global computer time, however some acceleration had been verified in outer iterations. (M.C.K.) [pt

  18. Acceleration of the nodal program FERM

    International Nuclear Information System (INIS)

    Nakata, H.

    1985-01-01

    Acceleration of the nodal FERM was tried by three acceleration schemes. Results of the calculations showed the best acceleration with the Tchebyshev method where the savings in the computing time were of the order of 50%. Acceleration with the Assymptotic Source Extrapoltation Method and with the Coarse-Mesh Rebalancing Method did not result in any improvement on the global computational time, although a reduction in the number of outer iterations was observed. (Author) [pt

  19. Nodal method for fast reactor analysis

    International Nuclear Information System (INIS)

    Shober, R.A.

    1979-01-01

    In this paper, a nodal method applicable to fast reactor diffusion theory analysis has been developed. This method has been shown to be accurate and efficient in comparison to highly optimized finite difference techniques. The use of an analytic solution to the diffusion equation as a means of determining accurate coupling relationships between nodes has been shown to be highly accurate and efficient in specific two-group applications, as well as in the current multigroup method

  20. Nodal methods in numerical reactor calculations

    International Nuclear Information System (INIS)

    Hennart, J.P.; Valle, E. del

    2004-01-01

    The present work describes the antecedents, developments and applications started in 1972 with Prof. Hennart who was invited to be part of the staff of the Nuclear Engineering Department at the School of Physics and Mathematics of the National Polytechnic Institute. Since that time and up to 1981, several master theses based on classical finite element methods were developed with applications in point kinetics and in the steady state as well as the time dependent multigroup diffusion equations. After this period the emphasis moved to nodal finite elements in 1, 2 and 3D cartesian geometries. All the thesis were devoted to the numerical solution of the neutron multigroup diffusion and transport equations, few of them including the time dependence, most of them related with steady state diffusion equations. The main contributions were as follows: high order nodal schemes for the primal and mixed forms of the diffusion equations, block-centered finite-differences methods, post-processing, composite nodal finite elements for hexagons, and weakly and strongly discontinuous schemes for the transport equation. Some of these are now being used by several researchers involved in nuclear fuel management. (Author)

  1. Nodal methods in numerical reactor calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hennart, J P [UNAM, IIMAS, A.P. 20-726, 01000 Mexico D.F. (Mexico); Valle, E del [National Polytechnic Institute, School of Physics and Mathematics, Department of Nuclear Engineering, Mexico, D.F. (Mexico)

    2004-07-01

    The present work describes the antecedents, developments and applications started in 1972 with Prof. Hennart who was invited to be part of the staff of the Nuclear Engineering Department at the School of Physics and Mathematics of the National Polytechnic Institute. Since that time and up to 1981, several master theses based on classical finite element methods were developed with applications in point kinetics and in the steady state as well as the time dependent multigroup diffusion equations. After this period the emphasis moved to nodal finite elements in 1, 2 and 3D cartesian geometries. All the thesis were devoted to the numerical solution of the neutron multigroup diffusion and transport equations, few of them including the time dependence, most of them related with steady state diffusion equations. The main contributions were as follows: high order nodal schemes for the primal and mixed forms of the diffusion equations, block-centered finite-differences methods, post-processing, composite nodal finite elements for hexagons, and weakly and strongly discontinuous schemes for the transport equation. Some of these are now being used by several researchers involved in nuclear fuel management. (Author)

  2. Nitric oxide synthase-3 promotes embryonic development of atrioventricular valves.

    Directory of Open Access Journals (Sweden)

    Yin Liu

    Full Text Available Nitric oxide synthase-3 (NOS3 has recently been shown to promote endothelial-to-mesenchymal transition (EndMT in the developing atrioventricular (AV canal. The present study was aimed to investigate the role of NOS3 in embryonic development of AV valves. We hypothesized that NOS3 promotes embryonic development of AV valves via EndMT. To test this hypothesis, morphological and functional analysis of AV valves were performed in wild-type (WT and NOS3(-/- mice at postnatal day 0. Our data show that the overall size and length of mitral and tricuspid valves were decreased in NOS3(-/- compared with WT mice. Echocardiographic assessment showed significant regurgitation of mitral and tricuspid valves during systole in NOS3(-/- mice. These phenotypes were all rescued by cardiac specific NOS3 overexpression. To assess EndMT, immunostaining of Snail1 was performed in the embryonic heart. Both total mesenchymal and Snail1(+ cells in the AV cushion were decreased in NOS3(-/- compared with WT mice at E10.5 and E12.5, which was completely restored by cardiac specific NOS3 overexpression. In cultured embryonic hearts, NOS3 promoted transforming growth factor (TGFβ, bone morphogenetic protein (BMP2 and Snail1expression through cGMP. Furthermore, mesenchymal cell formation and migration from cultured AV cushion explants were decreased in the NOS3(-/- compared with WT mice. We conclude that NOS3 promotes AV valve formation during embryonic heart development and deficiency in NOS3 results in AV valve insufficiency.

  3. On the non-uniqueness of the nodal mathematical adjoint

    International Nuclear Information System (INIS)

    Müller, Erwin

    2014-01-01

    Highlights: • We evaluate three CMFD schemes for computing the nodal mathematical adjoint. • The nodal mathematical adjoint is not unique and can be non-positive (nonphysical). • Adjoint and forward eigenmodes are compatible if produced by the same CMFD method. • In nodal applications the excited eigenmodes are purely mathematical entities. - Abstract: Computation of the neutron adjoint flux within the framework of modern nodal diffusion methods is often facilitated by reducing the nodal equation system for the forward flux into a simpler coarse-mesh finite-difference form and then transposing the resultant matrix equations. The solution to the transposed problem is known as the nodal mathematical adjoint. Since the coarse-mesh finite-difference reduction of a given nodal formulation can be obtained in a number of ways, different nodal mathematical adjoint solutions can be computed. This non-uniqueness of the nodal mathematical adjoint challenges the credibility of the reduction strategy and demands a verdict as to its suitability in practical applications. This is the matter under consideration in this paper. A selected number of coarse-mesh finite-difference reduction schemes are described and compared. Numerical calculations are utilised to illustrate the differences in the adjoint solutions as well as to appraise the impact on such common applications as the computation of core point kinetics parameters. Recommendations are made for the proper application of the coarse-mesh finite-difference reduction approach to the nodal mathematical adjoint problem

  4. Impacts of Contingency Reserve on Nodal Price and Nodal Reliability Risk in Deregulated Power Systems

    DEFF Research Database (Denmark)

    Zhao, Qian; Wang, Peng; Goel, Lalit

    2013-01-01

    The deregulation of power systems allows customers to participate in power market operation. In deregulated power systems, nodal price and nodal reliability are adopted to represent locational operation cost and reliability performance. Since contingency reserve (CR) plays an important role...... in reliable operation, the CR commitment should be considered in operational reliability analysis. In this paper, a CR model based on customer reliability requirements has been formulated and integrated into power market settlement. A two-step market clearing process has been proposed to determine generation...

  5. Long-Term Effects of Atrial Ganglionated Plexi Ablation on Function and Structure of Sinoatrial and Atrioventricular Node in Canine.

    Science.gov (United States)

    Zhang, Ming; Wang, Ximin; Xie, Xinxing; Wang, Zhongsu; Liu, Xiaoyan; Guan, Juan; Wang, Weizong; Li, Zhan; Wang, Jiangrong; Gao, Mei; Hou, Yinglong

    2015-10-01

    Long-term effects of ganglionated plexi (GP) ablation on sinoatrial node (SAN) and atrioventricular node (AVN) remain unclear. This study is to investigate the long-term effects of ablation of cardiac anterior right GP (ARGP) and inferior right GP (IRGP) on function and structure of SAN and AVN in canine. Thirty-two dogs were randomly divided into an operated group (n = 24) and sham-operated group (n = 8). ARGP and IRGP were ablated in operated group which was randomly divided into three subgroups according to the period of evaluation after operation (1 month, 6 months, 12 months). The functional and histological characteristics of SAN and AVN, as well as the expression of connexin (Cx) 43 and Cx 45 in SAN and AVN, were evaluated before and after ablation. Resting heart rate was increased and AVN effective refractory period was prolonged and sinus node recovery time (SNRT) and corrected SNRT were shortened immediately after ablation. These changes were reverted to preablation level after 1 month. At 1 month, ventricular rate during atrial fibrillation was slowed, atria-His intervals were prolonged, and Cx43 and Cx45 expression in SAN and AVN were downregulated. At 6 months, all changes were reverted to preablation level. The histological characteristics of SAN and AVN did not change. Ablation of ARGP and IRGP has short-term effects on function and structure of SAN and AVN rather than long-term effects, which suggests that ablation of ARGP and IRGP is safe. Atrioventricular conduction dysfunction after ablation may be related to downregulated Cx43 and Cx45 expression in AVN. © 2015 Wiley Periodicals, Inc.

  6. Application of nonlinear nodal diffusion method for a small research reactor

    International Nuclear Information System (INIS)

    Jaradat, Mustafa K.; Alawneh, Luay M.; Park, Chang Je; Lee, Byungchul

    2014-01-01

    Highlights: • We applied nonlinear unified nodal method for 10 MW IAEA MTR benchmark problem. • TRITION–NEWT system was used to obtain two-group burnup dependent cross sections. • The criticality and power distribution compared with reference (IAEA-TECDOC-233). • Comparison between different fuel materials was conducted. • Satisfactory results were provided using UNM for MTR core calculations. - Abstract: Nodal diffusion methods are usually used for LWR calculations and rarely used for research reactor calculations. A unified nodal method with an implementation of the coarse mesh finite difference acceleration was developed for use in plate type research reactor calculations. It was validated for two PWR benchmark problems and then applied for IAEA MTR benchmark problem for static calculations to check the validity and accuracy of the method. This work was conducted to investigate the unified nodal method capability to treat material testing reactor cores. A 10 MW research reactor core is considered with three calculation cases for low enriched uranium fuel depending on the core burnup status of fresh, beginning-of-life, and end-of-life cores. The validation work included criticality calculations, flux distribution, and power distribution; in addition, a comparison between different fuel materials with the same uranium content was conducted. The homogenized two-group cross sections were generated using the TRITON–NEWT system. The results were compared with a reference, which was taken from IAEA-TECDOC-233. The unified nodal method provides satisfactory results for an all-rod out case, and the three-dimensional, two-group diffusion model can be considered accurate enough for MTR core calculations

  7. Role of atrial fibrillation and atrioventricular conduction (including Wolff-Parkinson-White Syndrome) in sudden death

    NARCIS (Netherlands)

    Meijler, F.L.; Tweel, I. van der; Herbschleb, J.N.; Hauer, R.N.W.; Robles de Medina, E.O.

    A short refractory period of the accessory pathway is considered a major threat for sudden death in patients with Wolff-Parkinson-White syndrome and atrial fibrillation. RR interval and QRS signal analysis together with signal analysis of a bipolar high right atrial electrogram were obtained in six

  8. Fourier-Accelerated Nodal Solvers (FANS) for homogenization problems

    Science.gov (United States)

    Leuschner, Matthias; Fritzen, Felix

    2017-11-01

    Fourier-based homogenization schemes are useful to analyze heterogeneous microstructures represented by 2D or 3D image data. These iterative schemes involve discrete periodic convolutions with global ansatz functions (mostly fundamental solutions). The convolutions are efficiently computed using the fast Fourier transform. FANS operates on nodal variables on regular grids and converges to finite element solutions. Compared to established Fourier-based methods, the number of convolutions is reduced by FANS. Additionally, fast iterations are possible by assembling the stiffness matrix. Due to the related memory requirement, the method is best suited for medium-sized problems. A comparative study involving established Fourier-based homogenization schemes is conducted for a thermal benchmark problem with a closed-form solution. Detailed technical and algorithmic descriptions are given for all methods considered in the comparison. Furthermore, many numerical examples focusing on convergence properties for both thermal and mechanical problems, including also plasticity, are presented.

  9. Topological surface states in nodal superconductors.

    Science.gov (United States)

    Schnyder, Andreas P; Brydon, Philip M R

    2015-06-24

    Topological superconductors have become a subject of intense research due to their potential use for technical applications in device fabrication and quantum information. Besides fully gapped superconductors, unconventional superconductors with point or line nodes in their order parameter can also exhibit nontrivial topological characteristics. This article reviews recent progress in the theoretical understanding of nodal topological superconductors, with a focus on Weyl and noncentrosymmetric superconductors and their protected surface states. Using selected examples, we review the bulk topological properties of these systems, study different types of topological surface states, and examine their unusual properties. Furthermore, we survey some candidate materials for topological superconductivity and discuss different experimental signatures of topological surface states.

  10. Twisted vector bundles on pointed nodal curves

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    by identifying the points p1 and p2. If m ≥ 2, let R1,...,Rm−1 be m − 1 copies of the projective line P1 and let xi,yi be two distinct points in Ri. Let R be the nodal curve which arises from the union. R0 ⊔ R1 ⊔···⊔ Rm−1 ⊔ Rm by identifying p1 ∈ R0 and p2 ∈ Rm with x1 ∈ R1 and ym−1 ∈ Rm−1 respectively and by identifying ...

  11. Accessory atrioventricular myocardial connections in the developing human heart: relevance for perinatal supraventricular tachycardias

    NARCIS (Netherlands)

    Hahurij, Nathan D.; Gittenberger-de Groot, Adriana C.; Kolditz, Denise P.; Bökenkamp, Regina; Schalij, Martin J.; Poelmann, Robert E.; Blom, Nico A.

    2008-01-01

    BACKGROUND: Fetal and neonatal atrioventricular (AV) reentrant tachycardias can be life-threatening but resolve in most cases during the first year of life. The transient presence of accessory AV myocardial connections during annulus fibrosus development may explain this phenomenon. METHODS AND

  12. Atrioventricular node reentrant tachycardia (AVNRT) after mitral valvuloplasty during cardiac rehabilitation.

    Science.gov (United States)

    Fallavollita, Luca; Santillo, Elpidio; Marini, Luciano; Balestrini, Fabrizio

    2012-12-01

    We descrive a patient who presents palpitations during cardiac rehabilitation after mitral valvuloplasty. ECG showed regular narrow QRS tachycardia compatible with Atrioventricular Node Reentrant Tachycardia. After slow pathway radiofrequency catheter ablation, the patient completed the rehabilitation program remained tachycardia and palpitations-free.

  13. Wnt signaling regulates atrioventricular canal formation upstream of BMP and Tbx2

    NARCIS (Netherlands)

    Verhoeven, Manon C.; Haase, Christa; Christoffels, Vincent M.; Weidinger, Gilbert; Bakkers, Jeroen

    2011-01-01

    In the developing heart, the atrioventricular canal (AVC) is essential for separation and alignment of the cardiac chambers, for valve formation, and serves to delay the electrical impulse from the atria to the ventricles. Defects in various aspects of its formation are the most common form of

  14. Tbx20 interacts with smads to confine tbx2 expression to the atrioventricular canal

    NARCIS (Netherlands)

    Singh, Reena; Horsthuis, Thomas; Farin, Henner F.; Grieskamp, Thomas; Norden, Julia; Petry, Marianne; Wakker, Vincent; Moorman, Antoon F. M.; Christoffels, Vincent M.; Kispert, Andreas

    2009-01-01

    RATIONALE: T-box transcription factors play critical roles in the coordinated formation of the working chambers and the atrioventricular canal (AVC). Tbx2 patterns embryonic myocardial cells to form the AVC and suppresses their differentiation into chamber myocardium. Tbx20-deficient embryos, which

  15. Deficiency of the vestibular spine in atrioventricular septal defects in human fetuses with down syndrome

    NARCIS (Netherlands)

    Blom, Nico A.; Ottenkamp, Jaap; Wenink, Arnold G. C.; Gittenberger-de Groot, Adriana C.

    2003-01-01

    Data on the morphogenesis of atrioventricular septal defect (AVSD) in Down syndrome are lacking to support molecular studies on Down syndrome heart critical region. Therefore, we studied the development of complete AVSD in human embryos and fetuses with trisomy 21 using 3-dimensional graphic

  16. Increased sarcolemmal Na+/H+ exchange activity in hypertrophied myocytes from dogs with chronic atrioventricular block

    NARCIS (Netherlands)

    van Borren, Marcel M. G. J.; Vos, Marc A.; Houtman, Marien J. C.; Antoons, Gudrun; Ravesloot, Jan H.

    2013-01-01

    Dogs with compensated biventricular hypertrophy due to chronic atrioventricular block (cAVB), are more susceptible to develop drug-induced Torsade-de-Pointes arrhythmias and sudden cardiac death. It has been suggested that the increased Na+ influx in hypertrophied cAVB ventricular myocytes

  17. Complete paroxysmal atrioventricular block in a 2-year-old girl

    DEFF Research Database (Denmark)

    Holst, Line Marie; Dixen, Ulrik; Jeppesen, Dorthe L

    2015-01-01

    We present a case of atypical syncope in a 2-year-old, otherwise healthy girl. The patient presented with three episodes of syncope without any precipitating factors and no family history of sudden unexpected death. Holter monitoring revealed 24 events of complete atrioventricular block lasting up...

  18. Posterior extensions of the human compact atrioventricular node: a neglected anatomic feature of potential clinical significance

    NARCIS (Netherlands)

    Inoue, S.; Becker, A. E.

    1998-01-01

    Catheter ablation procedures have revived interest in the detailed anatomy of the specialized atrioventricular (AV) septal junctional area. The compact AV node usually is considered to have a blunt posterior end. The objective of this study was to reconstruct the human compact AV node in relation to

  19. Congenital intermittent atrio-ventricular dissociation in tetralogy of Fallot (a case report.

    Directory of Open Access Journals (Sweden)

    Karande S

    1991-01-01

    Full Text Available A case of tetralogy of fallot with congenital intermittent atrioventricular dissociation is reported. A review of standard postgraduate books of cardiology fails to describe this condition, thus showing its extreme rarity. The therapeutic dilemma in treating such a case is also discussed.

  20. Robust doubly charged nodal lines and nodal surfaces in centrosymmetric systems

    Science.gov (United States)

    Bzdušek, Tomáš; Sigrist, Manfred

    2017-10-01

    Weyl points in three spatial dimensions are characterized by a Z -valued charge—the Chern number—which makes them stable against a wide range of perturbations. A set of Weyl points can mutually annihilate only if their net charge vanishes, a property we refer to as robustness. While nodal loops are usually not robust in this sense, it has recently been shown using homotopy arguments that in the centrosymmetric extension of the AI symmetry class they nevertheless develop a Z2 charge analogous to the Chern number. Nodal loops carrying a nontrivial value of this Z2 charge are robust, i.e., they can be gapped out only by a pairwise annihilation and not on their own. As this is an additional charge independent of the Berry π -phase flowing along the band degeneracy, such nodal loops are, in fact, doubly charged. In this manuscript, we generalize the homotopy discussion to the centrosymmetric extensions of all Atland-Zirnbauer classes. We develop a tailored mathematical framework dubbed the AZ +I classification and show that in three spatial dimensions such robust and multiply charged nodes appear in four of such centrosymmetric extensions, namely, AZ +I classes CI and AI lead to doubly charged nodal lines, while D and BDI support doubly charged nodal surfaces. We remark that no further crystalline symmetries apart from the spatial inversion are necessary for their stability. We provide a description of the corresponding topological charges, and develop simple tight-binding models of various semimetallic and superconducting phases that exhibit these nodes. We also indicate how the concept of robust and multiply charged nodes generalizes to other spatial dimensions.

  1. Radiotherapy of adult nodal non Hodgkin's lymphoma

    International Nuclear Information System (INIS)

    Gamen, G.; Thirion, P.

    1999-01-01

    The role of radiotherapy in the treatment of nodal non-Hodgkin's lymphoma has been modified by the introduction of efficient chemotherapy and the development of different pathological classifications. The recommended treatment of early-stage aggressive lymphomas is primarily a combination chemotherapy. The interest of adjuvant radiotherapy remains unclear and has to be established through large prospective trials. If radiation therapy has to be delivered, the historical results of exclusive radiation therapy showed that involved-fields and a dose of 35-40 Gy (daily fraction of 1.8 Gy, 5 days a week) are the optimal schedule. The interest of radiotherapy in the treatment of advanced-stage aggressive lymphoma is yet to be proven. Further studies had to stratify localized stages according to the factors of the International Prognostic Index. For easy-stage low-grade lymphoma, radiotherapy remains the standard treatment. However, the appropriate technique to use is controversial. Involved-field irradiation at a dose of 35 Gy seems to be the optimal schedule, providing a 10 year disease-free survival rate of 50 % and no major toxicity. There is no standard indication of radiotherapy in the treatment advanced-stage low-grade lymphoma. For 'new' nodal lymphoma's types, the indication of radiotherapy cannot be established (mantle-zone lymphoma, marginal zone B-cell lymphoma) or must take into account the natural history (Burkitt's lymphoma, peripheral T-cell lymphoma) and the sensibility to others therapeutic methods. (authors)

  2. Error estimation for variational nodal calculations

    International Nuclear Information System (INIS)

    Zhang, H.; Lewis, E.E.

    1998-01-01

    Adaptive grid methods are widely employed in finite element solutions to both solid and fluid mechanics problems. Either the size of the element is reduced (h refinement) or the order of the trial function is increased (p refinement) locally to improve the accuracy of the solution without a commensurate increase in computational effort. Success of these methods requires effective local error estimates to determine those parts of the problem domain where the solution should be refined. Adaptive methods have recently been applied to the spatial variables of the discrete ordinates equations. As a first step in the development of adaptive methods that are compatible with the variational nodal method, the authors examine error estimates for use in conjunction with spatial variables. The variational nodal method lends itself well to p refinement because the space-angle trial functions are hierarchical. Here they examine an error estimator for use with spatial p refinement for the diffusion approximation. Eventually, angular refinement will also be considered using spherical harmonics approximations

  3. Torsionfree Sheaves over a Nodal Curve of Arithmetic Genus One

    Indian Academy of Sciences (India)

    We classify all isomorphism classes of stable torsionfree sheaves on an irreducible nodal curve of arithmetic genus one defined over C C . Let be a nodal curve of arithmetic genus one defined over R R , with exactly one node, such that does not have any real points apart from the node. We classify all isomorphism ...

  4. Topological surface states in nodal superconductors

    International Nuclear Information System (INIS)

    Schnyder, Andreas P; Brydon, Philip M R

    2015-01-01

    Topological superconductors have become a subject of intense research due to their potential use for technical applications in device fabrication and quantum information. Besides fully gapped superconductors, unconventional superconductors with point or line nodes in their order parameter can also exhibit nontrivial topological characteristics. This article reviews recent progress in the theoretical understanding of nodal topological superconductors, with a focus on Weyl and noncentrosymmetric superconductors and their protected surface states. Using selected examples, we review the bulk topological properties of these systems, study different types of topological surface states, and examine their unusual properties. Furthermore, we survey some candidate materials for topological superconductivity and discuss different experimental signatures of topological surface states. (topical review)

  5. Nodal aberration theory applied to freeform surfaces

    Science.gov (United States)

    Fuerschbach, Kyle; Rolland, Jannick P.; Thompson, Kevin P.

    2014-12-01

    When new three-dimensional packages are developed for imaging optical systems, the rotational symmetry of the optical system is often broken, changing its imaging behavior and making the optical performance worse. A method to restore the performance is to use freeform optical surfaces that compensate directly the aberrations introduced from tilting and decentering the optical surfaces. In order to effectively optimize the shape of a freeform surface to restore optical functionality, it is helpful to understand the aberration effect the surface may induce. Using nodal aberration theory the aberration fields induced by a freeform surface in an optical system are explored. These theoretical predications are experimentally validated with the design and implementation of an aberration generating telescope.

  6. Prevalence of cardiac dyssynchrony and correlation with atrio-ventricular block and QRS width in dilated cardiomyopathy

    DEFF Research Database (Denmark)

    Anzouan-Kacou, J B; Ncho-Mottoh, M P; Konin, C

    2012-01-01

    Cardiac dyssynchrony causes disorganised cardiac contraction, delayed wall contraction and reduced pumping efficiency. We aimed to assess the prevalence of different types of dyssynchrony in patients with dilated cardiomyopathy (DCM), and to establish the correlation between atrio-ventricular block...

  7. Predictors of hospitalization for heart failure and of all-cause mortality after atrioventricular nodal ablation and right ventricular pacing for atrial fibrillation

    DEFF Research Database (Denmark)

    Björkenheim, Anna; Brandes, Axel; Andersson, Tommy

    2014-01-01

    in patients who underwent AVJA because of AF and to determine predictors for HF and mortality. METHODS AND RESULTS: We retrospectively enrolled 162 consecutive patients, mean age 67 ± 9 years, 48% women, who underwent AVJA because of symptomatic AF refractory to pharmacological treatment (n = 117...

  8. Complex phenotype linked to a mutation in exon 11 of the lamin A/C gene: Hypertrophic cardiomyopathy, atrioventricular block, severe dyslipidemia and diabetes.

    Science.gov (United States)

    Francisco, Ana Rita G; Santos Gonçalves, Inês; Veiga, Fátima; Mendes Pedro, Mónica; Pinto, Fausto J; Brito, Dulce

    2017-09-01

    The lamin A/C (LMNA) gene encodes lamins A and C, which have an important role in nuclear cohesion and chromatin organization. Mutations in this gene usually lead to the so-called laminopathies, the primary cardiac manifestations of which are dilated cardiomyopathy and intracardiac conduction defects. Some mutations, associated with lipodystrophy but not cardiomyopathy, have been linked to metabolic abnormalities such as diabetes and severe dyslipidemia. Herein we describe a new phenotype associated with a mutation in exon 11 of the LMNA gene: hypertrophic cardiomyopathy, atrioventricular block, severe dyslipidemia and diabetes. A 64-year-old woman with hypertrophic cardiomyopathy and a point mutation in exon 11 of the LMNA gene (c.1718C>T, Ser573Leu) presented with severe symptomatic ventricular hypertrophy and left ventricular outflow tract obstruction. She underwent septal alcohol ablation, followed by Morrow myectomy. The patient was also diagnosed with severe dyslipidemia, diabetes and obesity, and fulfilled diagnostic criteria for metabolic syndrome. No other characteristics of LMNA mutation-related phenotypes were identified. The development of type III atrioventricular block with no apparent cause, and mildly depressed systolic function, prompted referral for cardiac resynchronization therapy. In conclusion, the association between LMNA mutations and different phenotypes is complex and not fully understood, and can present with a broad spectrum of severity. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. A nodal expansion method using conformal mapping for hexagonal geometry

    International Nuclear Information System (INIS)

    Chao, Y.A.; Shatilla, Y.A.

    1993-01-01

    Hexagonal nodal methods adopting the same transverse integration process used for square nodal methods face the subtle theoretical problem that this process leads to highly singular nonphysical terms in the diffusion equation. Lawrence, in developing the DIF3D-N code, tried to approximate the singular terms with relatively simple polynomials. In the HEX-NOD code, Wagner ignored the singularities to simplify the diffusion equation and introduced compensating terms in the nodal equations to restore the nodal balance relation. More recently developed hexagonal nodal codes, such as HEXPE-DITE and the hexagonal version of PANTHER, used methods similar to Wagner's. It will be shown that for light water reactor applications, these two different approximations significantly degraded the accuracy of the respective method as compared to the established square nodal methods. Alternatively, the method of conformal mapping was suggested to map a hexagon to a rectangle, with the unique feature of leaving the diffusion operator invariant, thereby fundamentally resolving the problems associated with transverse integration. This method is now implemented in the Westinghouse hexagonal nodal code ANC-H. In this paper we report on the results of comparing the three methods for a variety of problems via benchmarking against the fine-mesh finite difference code

  10. Benchmarking with high-order nodal diffusion methods

    International Nuclear Information System (INIS)

    Tomasevic, D.; Larsen, E.W.

    1993-01-01

    Significant progress in the solution of multidimensional neutron diffusion problems was made in the late 1970s with the introduction of nodal methods. Modern nodal reactor analysis codes provide significant improvements in both accuracy and computing speed over earlier codes based on fine-mesh finite difference methods. In the past, the performance of advanced nodal methods was determined by comparisons with fine-mesh finite difference codes. More recently, the excellent spatial convergence of nodal methods has permitted their use in establishing reference solutions for some important bench-mark problems. The recent development of the self-consistent high-order nodal diffusion method and its subsequent variational formulation has permitted the calculation of reference solutions with one node per assembly mesh size. In this paper, we compare results for four selected benchmark problems to those obtained by high-order response matrix methods and by two well-known state-of-the-art nodal methods (the open-quotes analyticalclose quotes and open-quotes nodal expansionclose quotes methods)

  11. About the specialized myocardial conducting tissue.

    Science.gov (United States)

    de Micheli Serra, Alfredo; Iturralde Torres, Pedro; Aranda Fraustro, Alberto

    2013-01-01

    The chronological succession of discoveries on the location and structure of the atrio-ventricular conducting system are described. The starting point of this system is located in the sinus atrial node, identified by the English scientists A. Keith and M. W. Flack in 1907. The atrioventricular conducting system was pointed out by the Swiss physician Wilhelm His Jr. in 1893. The atrioventricular node (AV) was first identified by the Japanese pathologist Sumao Tawara and his German professor Ludwig Aschoff in 1906. Likewise the structure and routes of the three internodal bundles are described. These bundles include: Bachmann's bundle (1916) connecting the right with the left atrium and the AV node; the middle Wenckebach's bundle (1910) and the posterior or Thörel's bundle (1910), extending from the region of the sinus atrial node towards the posterior margin of the AV node. Lastly, the ventricular left and right conduction systems are detailed. These include the main trunk and their peripheral subdivisions with respective networks. Regarding the controversial existence of the left middle subdivision, it can exist in animal and human hearts. Nevertheless, an intermediate left septal network of specialized fibers seems to act as a functional equivalent of this subdivision. Copyright © 2012 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

  12. A Hennart nodal method for the diffusion equation

    International Nuclear Information System (INIS)

    Lesaint, P.; Noceir, S.; Verwaerde, D.

    1995-01-01

    A modification of the Hennart nodal method for neutron diffusion problems is presented. The final system of equations obtained by this method is not positive definite. However, a flux elimination technique leads to a simple positive definite system, which can be solved by the traditional iterative methods. Calculations of a two-dimensional International Atomic Energy Agency benchmark problem are performed and compared with results of the original Hennart nodal method and some finite element methods. The high computational efficiency of this modified nodal method is clearly demonstrated

  13. Modifying nodal pricing method considering market participants optimality and reliability

    Directory of Open Access Journals (Sweden)

    A. R. Soofiabadi

    2015-06-01

    Full Text Available This paper develops a method for nodal pricing and market clearing mechanism considering reliability of the system. The effects of components reliability on electricity price, market participants’ profit and system social welfare is considered. This paper considers reliability both for evaluation of market participant’s optimality as well as for fair pricing and market clearing mechanism. To achieve fair pricing, nodal price has been obtained through a two stage optimization problem and to achieve fair market clearing mechanism, comprehensive criteria has been introduced for optimality evaluation of market participant. Social welfare of the system and system efficiency are increased under proposed modified nodal pricing method.

  14. Inhibitory effects of Urtica dioica L. root on electrophysiological properties of isolated rabbit atrioventricular node

    OpenAIRE

    A. Enayati; V. Khori*; M. Azadbakhat; M. Zahedi

    2017-01-01

    Background and objectives: The ideal drug for treatment of a wide range of supraventricular arrhythmia hasn't yet been developed. Previous studies have shown antihypertensive and negative inotropic effects of the Urtica dioica L. (nettle). Therefore, the aim of present study is to determine the rate dependent inhibitory effects of ethanol extract of nettle root and investigate the role of adrenoceptors in the anti-arrhythmic mechanism of nettle on the isolated rabbit atrio-ventricular node. M...

  15. Complete Atrioventricular Block Complicating Mitral Infective Endocarditis Caused by Streptococcus Agalactiae

    OpenAIRE

    Arai, Masaru; Nagashima, Koichi; Kato, Mahoto; Akutsu, Naotaka; Hayase, Misa; Ogura, Kanako; Iwasawa, Yukino; Aizawa, Yoshihiro; Saito, Yuki; Okumura, Yasuo; Nishimaki, Haruna; Masuda, Shinobu; Hirayama, Atsushi

    2016-01-01

    Patient: Male, 74 Final Diagnosis: Infective endocarditis Symptoms: Apetite loss ? fever Medication: ? Clinical Procedure: Transesophageal echocardiography Specialty: Cardiology Objective: Rare co-existance of disease or pathology Background: Infective endocarditis (IE) involving the mitral valve can but rarely lead to complete atrioventricular block (CAVB). Case Report: A 74-year-old man with a history of infective endocarditis caused by Streptococcus gordonii (S. gordonii) presented to our ...

  16. Repair of Tetralogy of Fallot in Infancy via the Atrioventricular Approach

    Directory of Open Access Journals (Sweden)

    Hamid Bigdelian

    2016-02-01

    Full Text Available Background: Tetralogy of Fallot (TOF is a well-recognized congenital heart disease. Despite improvements in the outcomes of surgical repair, the optimal timing of surgery and type of surgical management of patients with TOF remains controversial. The purpose of this study was to assess outcomes following the repair of TOF in infants depending on the surgical procedure used. Methods: This study involved the retrospective review of 120 patients who underwent TOF repair between 2010 and 2013. Patients were divided into three groups depending on the surgical procedure that they underwent. Corrective surgery was done via the transventricular approach (n=40, the transatrial approach (n=40, or a combined atrioventricular approach (n=40. Demographic data and the outcomes of the surgical procedures were compared among the groups. Results: In the atrioventricular group, the incidence of the following complications was found to be significantly lower than in the other groups: complete heart block (p=0.034, right ventricular failure (p=0.027 and mediastinal bleeding (p=0.007. Patients in the atrioventricular group had a better postoperative right ventricular ejection fraction (p=0.001. No statistically significant differences were observed among the three surgical groups in the occurrence of tachycardia, renal failure, and tricuspid incompetence. The one-year survival rates in the three groups were 95%, 90%, and 97.5%, respectively (p=0.395. Conclusion: Combined atrioventricular repair of TOF in infancy can be safely performed, with acceptable surgical risk, a low incidence of reoperation, good ventricular function outcomes, and an excellent survival rate.

  17. Neuroendocrine Merkel cell nodal carcinoma of unknown primary site: management and outcomes of a rare entity.

    Science.gov (United States)

    Kotteas, E A; Pavlidis, N

    2015-04-01

    Merkel cell nodal carcinoma of unknown primary (MCCUP) is a rare neuroendocrine tumour with distinct clinical and biological behaviour. We conducted a review of retrospective data extracted from 90 patients focusing on the management and outcome of this disease. We also compared life expectancy of these patients with the outcome of patients with known Merkel primaries and with neuroendocrine cancers of unidentifiable primary. There is a limited body of data for this type of malignancy, however, patients with Merkel cell nodal carcinoma of unknown primary site, seem to have better survival when treated aggressively than patients with cutaneous Merkel tumours of the same stage and equal survival with patients with low-grade neuroendocrine tumour of unknown origin. The lack of prospective trials, and the inadequate data, hamper the management of these tumours. Establishment of treatment guidelines is urgently needed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Características morfológicas y posibles implicaciones clínicas de las arterias nodales

    Directory of Open Access Journals (Sweden)

    Luis E. Ballesteros, MD., MSc.

    2010-11-01

    Full Text Available La expresión morfológica de las arterias nodales es relevante en el diagnóstico y manejo de eventos clínicos y en abordajes quirúrgicos del corazón. Se estudiaron 88 arterias nodales de corazones obtenidos como material de autopsia. Las arterias coronarias se inyectaron con resina poliéster pigmentada de color rojo. Se registraron las formas de presentación de las arterias nodales y sus características morfométricas. La arteria del nodo sinoatrial se originó de la coronaria derecha en 52 casos (59,1%, de la circunfleja en 33 corazones (37,35% y de ambas en 3 (3,4%. Su calibre proximal fue de 1,31 mm (± 0,3, correspondiente a las arterias originadas de la coronaria derecha de 1,25 mm (± 0,3 mientras que las que se originaron de la arteria circunfleja obtuvieron un calibre de 1,42 mm (± 0,3, siendo esta diferencia significativa (p= 0,01. Se originó con mayor frecuencia en el tercio anteromedial, tanto de la coronaria derecha como de la circunfleja (54,6% y 61,2% respectivamente. En su segmento final cruzó por delante de la desembocadura de la vena cava superior en la mayoría de los casos (44%, mientras que en 22 corazones (24,5% cursó alrededor de la cava. Se observó arteria en forma de «S» en 14 casos (15,9% del total de la muestra y 42,4% de las originadas de la arteria circunfleja. La arteria del nodo atrioventricular se originó del segmento en «U» invertida de la coronaria derecha, al nivel de la cruz cardiaca, en 81 corazones (92%, y presentó un calibre proximal de 1,06 mm (± 0,22. Con relación al calibre y al origen se evidencian hallazgos que coinciden con estudios previos. Se destaca la alta prevalencia de la arteria en forma de «S» y de la trayectoria de la arteria sinoatrial alrededor de la vena cava superior.

  19. CT simulation in nodal positive breast cancer

    International Nuclear Information System (INIS)

    Horst, E.; Schuck, A.; Moustakis, C.; Schaefer, U.; Micke, O.; Kronholz, H.L.; Willich, N.

    2001-01-01

    Background: A variety of solutions are used to match tangential fields and opposed lymph node fields in irradiation of nodal positive breast cancer. The choice is depending on the technical equipment which is available and the clinical situation. The CT simulation of a non-monoisocentric technique was evaluated in terms of accuracy and reproducibility. Patients, Material and Methods: The field match parameters were adjusted virtually at CT simulation and were compared with parameters derived mathematically. The coordinate transfer from the CT simulator to the conventional simulator was analyzed in 25 consecutive patients. Results: The angles adjusted virtually for a geometrically exact coplanar field match corresponded with the angles calculated for each set-up. The mean isocenter displacement was 5.7 mm and the total uncertainty of the coordinate transfer was 6.7 mm (1 SD). Limitations in the patient set-up became obvious because of the steep arm abduction necessary to fit the 70 cm CT gantry aperture. Required modifications of the arm position and coordinate transfer errors led to a significant shift of the marked matchline of >1.0 cm in eight of 25 patients (32%). Conclusion: The virtual CT simulation allows a precise and graphic definition of the field match parameters. However, modifications of the virtual set-up basically due to technical limitations were required in a total of 32% of cases, so that a hybrid technique was adapted at present that combines virtual adjustment of the ideal field alignment parameters with conventional simulation. (orig.) [de

  20. Present Status of GNF New Nodal Simulator

    International Nuclear Information System (INIS)

    Iwamoto, T.; Tamitani, M.; Moore, B.

    2001-01-01

    This paper presents core simulator consolidation work done at Global Nuclear Fuel (GNF). The unified simulator needs to supercede the capabilities of past simulator packages from the original GNF partners: GE, Hitachi, and Toshiba. At the same time, an effort is being made to produce a simulation package that will be a state-of-the-art analysis tool when released, in terms of the physics solution methodology and functionality. The core simulator will be capable and qualified for (a) high-energy cycles in the U.S. markets, (b) mixed-oxide (MOX) introduction in Japan, and (c) high-power density plants in Europe, etc. The unification of the lattice physics code is also in progress based on a transport model with collision probability methods. The AETNA core simulator is built upon the PANAC11 software base. The goal is to essentially replace the 1.5-energy-group model with a higher-order multigroup nonlinear nodal solution capable of the required modeling fidelity, while keeping highly automated library generation as well as functionality. All required interfaces to PANAC11 will be preserved, which minimizes the impact on users and process automation. Preliminary results show statistical accuracy improvement over the 1.5-group model

  1. Bachmann's Bundle Pacing not Only Improves Interatrial Conduction but Also Reduces the Need for Ventricular Pacing.

    Science.gov (United States)

    Sławuta, Agnieszka; Kliś, Magdalena; Skoczyński, Przemysław; Bańkowski, Tomasz; Moszczyńska-Stulin, Joanna; Gajek, Jacek

    2016-01-01

    Patients treated for sick sinus syndrome may have interatrial conduction disorder leading to atrial fibrillation. This study was aimed to assess the influence of the atrial pacing site on interatrial and atrioventricular conduction as well as the percentage of ventricular pacing in patients with sick sinus syndrome implanted with atrioventricular pacemaker. The study population: 96 patients (58 females, 38 males) aged 74.1 ± 11.8 years were divided in two groups: Group 1 (n = 44) with right atrial appendage pacing and group 2 (n = 52) with Bachmann's area pacing. We assessed the differences in atrioventricular conduction in sinus rhythm and atrial 60 and 90 bpm pacing, P-wave duration and percentage of ventricular pacing. No differences in baseline P-wave duration in sinus rhythm between the groups (102.4 ± 17 ms vs. 104.1 ± 26 ms, p = ns.) were noted. Atrial pacing 60 bpm resulted in longer P-wave in group 1 vs. group 2 (138.3 ± 21 vs. 106.1 ± 15 ms, p < 0.01). The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with right atrial appendage vs. Bachmann's pacing (44.1 ± 17 vs. 9.2 ± 7 ms p < 0.01 and 69.2 ± 31 vs. 21.4 ± 12 ms p < 0.05, respectively). The percentage of ventricular pacing was higher in group 1 (21 vs. 4%, p < 0.01). Bachmann's bundle pacing decreases interatrial and atrioventricular conduction delay. Moreover, the frequency-dependent atrioventricular conduction lengthening is much less pronounced during Bachmann's bundle pacing. Right atrial appendage pacing in sick sinus syndrome patients promotes a higher percentage of ventricular pacing.

  2. BEACON: An application of nodal methods for operational support

    International Nuclear Information System (INIS)

    Boyd, W.A.; Nguyen, T.Q.

    1992-01-01

    A practical application of nodal methods is on-line plant operational support. However, to enable plant personnel to take full advantage of a nodal model to support plant operations, (a) a core nodal model must always be up to date with the current core history and conditions, (b) the nodal methods must be fast enough to allow numerous core calculations to be performed in minutes to support engineering decisions, and (c) the system must be easily accessible to engineering personnel at the reactor, their offices, or any other location considered appropriate. A core operational support package developed by Westinghouse called BEACON (best estimate analysis of core operations - nuclear) has been installed at several plants. Results from these plants and numerous in-core flux maps analyzed have demonstrated the accuracy of the model and the effectiveness of the methodology

  3. Aircraft Nodal Data Acquisition System (ANDAS), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of an Aircraft Nodal Data Acquisition System (ANDAS) based upon the short haul Zigbee networking standard is proposed. It employs a very thin (135 um)...

  4. Hybrid nodal loop metal: Unconventional magnetoresponse and material realization

    Science.gov (United States)

    Zhang, Xiaoming; Yu, Zhi-Ming; Lu, Yunhao; Sheng, Xian-Lei; Yang, Hui Ying; Yang, Shengyuan A.

    2018-03-01

    A nodal loop is formed by a band crossing along a one-dimensional closed manifold, with each point on the loop a linear nodal point in the transverse dimensions, and can be classified as type I or type II depending on the band dispersion. Here, we propose a class of nodal loops composed of both type-I and type-II points, which are hence termed as hybrid nodal loops. Based on first-principles calculations, we predict the realization of such loops in the existing electride material Ca2As . For a hybrid loop, the Fermi surface consists of coexisting electron and hole pockets that touch at isolated points for an extended range of Fermi energies, without the need for fine-tuning. This leads to unconventional magnetic responses, including the zero-field magnetic breakdown and the momentum-space Klein tunneling observable in the magnetic quantum oscillations, as well as the peculiar anisotropy in the cyclotron resonance.

  5. A nodal method based on matrix-response method

    International Nuclear Information System (INIS)

    Rocamora Junior, F.D.; Menezes, A.

    1982-01-01

    A nodal method based in the matrix-response method, is presented, and its application to spatial gradient problems, such as those that exist in fast reactors, near the core - blanket interface, is investigated. (E.G.) [pt

  6. Nodal prices determination with wind integration for radial ...

    African Journals Online (AJOL)

    With competitive electricity market operation, open access to the transmission and distribution network is essential ... The results have been obtained for IEEE 33 ...... The value of intermittent wind DG under nodal prices and amp – mile tariffs.

  7. Nodal aberration theory for wild-filed asymmetric optical systems

    Science.gov (United States)

    Chen, Yang; Cheng, Xuemin; Hao, Qun

    2016-10-01

    Nodal Aberration Theory (NAT) was used to calculate the zero field position in Full Field Display (FFD) for the given aberration term. Aiming at wide-filed non-rotational symmetric decentered optical systems, we have presented the nodal geography behavior of the family of third-order and fifth-order aberrations. Meanwhile, we have calculated the wavefront aberration expressions when one optical element in the system is tilted, which was not at the entrance pupil. By using a three-piece-cellphone lens example in optical design software CodeV, the nodal geography is testified under several situations; and the wavefront aberrations are calculated when the optical element is tilted. The properties of the nodal aberrations are analyzed by using Fringe Zernike coefficients, which are directly related with the wavefront aberration terms and usually obtained by real ray trace and wavefront surface fitting.

  8. Extension of the analytic nodal method to four energy groups

    International Nuclear Information System (INIS)

    Parsons, D.K.; Nigg, D.W.

    1985-01-01

    The Analytic Nodal Method is one of several recently-developed coarse mesh numerical methods for efficiently and accurately solving the multidimensional static and transient neutron diffusion equations. This summary describes a mathematically rigorous extension of the Analytic Nodal Method to the frequently more physically realistic four-group case. A few general theoretical considerations are discussed, followed by some calculated results for a typical steady-state two-dimensional PWR quarter core application. 8 refs

  9. Bilinear nodal transport method in weighted diamond difference form

    International Nuclear Information System (INIS)

    Azmy, Y.Y.

    1987-01-01

    Nodal methods have been developed and implemented for the numerical solution of the discrete ordinates neutron transport equation. Numerical testing of these methods and comparison of their results to those obtained by conventional methods have established the high accuracy of nodal methods. Furthermore, it has been suggested that the linear-linear approximation is the most computationally efficient, practical nodal approximation. Indeed, this claim has been substantiated by comparing the accuracy in the solution, and the CPU time required to achieve convergence to that solution by several nodal approximations, as well as the diamond difference scheme. Two types of linear-linear nodal methods have been developed in the literature: analytic linear-linear (NLL) methods, in which the transverse-leakage terms are derived analytically, and approximate linear-linear (PLL) methods, in which these terms are approximated. In spite of their higher accuracy, NLL methods result in very complicated discrete-variable equations that exhibit a high degree of coupling, thus requiring special solution algorithms. On the other hand, the sacrificed accuracy in PLL methods is compensated for by the simple discrete-variable equations and diamond-difference-like solution algorithm. In this paper the authors outline the development of an NLL nodal method, the bilinear method, which can be written in a weighted diamond difference form with one spatial weight per dimension that is analytically derived rather than preassigned in an ad hoc fashion

  10. Id4 functions downstream of Bmp signaling to restrict TCF function in endocardial cells during atrioventricular valve development.

    Science.gov (United States)

    Ahuja, Suchit; Dogra, Deepika; Stainier, Didier Y R; Reischauer, Sven

    2016-04-01

    The atrioventricular canal (AVC) connects the atrial and ventricular chambers of the heart and its formation is critical for the development of the cardiac valves, chamber septation and formation of the cardiac conduction system. Consequently, problems in AVC formation can lead to congenital defects ranging from cardiac arrhythmia to incomplete cardiac septation. While our knowledge about early heart tube formation is relatively comprehensive, much remains to be investigated about the genes that regulate AVC formation. Here we identify a new role for the basic helix-loop-helix factor Id4 in zebrafish AVC valve development and function. id4 is first expressed in the AVC endocardium and later becomes more highly expressed in the atrial chamber. TALEN induced inactivation of id4 causes retrograde blood flow at the AV canal under heat induced stress conditions, indicating defects in AV valve function. At the molecular level, we found that id4 inactivation causes misexpression of several genes important for AVC and AV valve formation including bmp4 and spp1. We further show that id4 appears to control the number of endocardial cells that contribute to the AV valves by regulating Wnt signaling in the developing AVC endocardium. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Influence of the heart rate and atrioventricular delays on vortex evolution and blood transport inside the left ventricle

    Science.gov (United States)

    Hendabadi, Sahar; Martinez-Legazpi, Pablo; Benito, Yolanda; Bermejo, Javier; Del Alamo, Juan Carlos; Shadden, Shawn

    2013-11-01

    Cardiac resynchronization therapy (CRT) is used to help restore coordinated pumping of the ventricles by overcoming delays in electrical conduction due to cardiac disease. This is accomplished by a specialized cardiac pacemaker that is able to adjust the atrioventricular (AV) delay.A major clinical challenge is to adjust the pacing strategy to best coordinate the blood flow mechanics of ventricular filling and ejection. To this end, we have studied the difference in the vortex formation and its evolution inside the left ventricle (LV) for 4 different AV delays in a cohort of patients with implanted pacemakers. A reconstruction algorithm was used to obtain 2D velocity over the apical long-axis view of the LV from color Doppler and B-mode ultrasound data. To study blood transport, we have identified Lagrangian coherent structures to determine moving boundaries of the blood volumes injected to the LV in diastole and ejected to the aorta in systole. In all cases, we have analyzed the differences in filling and ejection patterns and the blood transport during the E-wave and A-wave formation.Finally we have assessed the influence of the AV delay on 2 indices of stasis, direct flow and residence time.The findings shed insight to the optimization of AV delays in patients undergoing CRT. NIH award 5R21HL108268 and grants PIS09/02603 and RD06/0010 from the Plan Nacional de Investigacion Cientifica, Spain.

  12. Uniqueness Theorem for the Inverse Aftereffect Problem and Representation the Nodal Points Form

    Directory of Open Access Journals (Sweden)

    A. Neamaty

    2015-03-01

    Full Text Available In this paper, we consider a boundary value problem with aftereffect on a finite interval. Then, the asymptotic behavior of the solutions, eigenvalues, the nodal points and the associated nodal length are studied. We also calculate the numerical values of the nodal points and the nodal length. Finally, we prove the uniqueness theorem for the inverse aftereffect problem by applying any dense subset of the nodal points.

  13. Uniqueness Theorem for the Inverse Aftereffect Problem and Representation the Nodal Points Form

    OpenAIRE

    A. Neamaty; Sh. Akbarpoor; A. Dabbaghian

    2015-01-01

    In this paper, we consider a boundary value problem with aftereffect on a finite interval. Then, the asymptotic behavior of the solutions, eigenvalues, the nodal points and the associated nodal length are studied. We also calculate the numerical values of the nodal points and the nodal length. Finally, we prove the uniqueness theorem for the inverse aftereffect problem by applying any dense subset of the nodal points.

  14. Investigation on generalized Variational Nodal Methods for heterogeneous nodes

    International Nuclear Information System (INIS)

    Wang, Yongping; Wu, Hongchun; Li, Yunzhao; Cao, Liangzhi; Shen, Wei

    2017-01-01

    Highlights: • We developed two heterogeneous nodal methods based on the Variational Nodal Method. • Four problems were solved to evaluate the two heterogeneous nodal methods. • The function expansion method is good at treating continuous-changing heterogeneity. • The finite sub-element method is good at treating discontinuous-changing heterogeneity. - Abstract: The Variational Nodal Method (VNM) is generalized for heterogeneous nodes and applied to four kinds of problems including Molten Salt Reactor (MSR) core problem with continuous cross section profile, Pressurized Water Reactor (PWR) control rod cusping effect problem, PWR whole-core pin-by-pin problem, and heterogeneous PWR core problem without fuel-coolant homogenization in each pin cell. Two approaches have been investigated for the treatment of the nodal heterogeneity in this paper. To concentrate on spatial heterogeneity, diffusion approximation was adopted for the angular variable in neutron transport equation. To provide demonstrative numerical results, the codes in this paper were developed in slab geometry. The first method, named as function expansion (FE) method, expands nodal flux by orthogonal polynomials and the nodal cross sections are also expressed as spatial depended functions. The second path, named as finite sub-element (FS) method, takes advantage of the finite-element method by dividing each node into numbers of homogeneous sub-elements and expanding nodal flux into the combination of linear sub-element trial functions. Numerical tests have been carried out to evaluate the ability of the two nodal (coarse-mesh) heterogeneous VNMs by comparing with the fine-mesh homogeneous VNM. It has been demonstrated that both heterogeneous approaches can handle heterogeneous nodes. The FE method is good at continuous-changing heterogeneity as in the MSR core problem, while the FS method is good at discontinuous-changing heterogeneity such as the PWR pin-by-pin problem and heterogeneous PWR core

  15. Implications of inaccurate clinical nodal staging in pancreatic adenocarcinoma.

    Science.gov (United States)

    Swords, Douglas S; Firpo, Matthew A; Johnson, Kirsten M; Boucher, Kenneth M; Scaife, Courtney L; Mulvihill, Sean J

    2017-07-01

    Many patients with stage I-II pancreatic adenocarcinoma do not undergo resection. We hypothesized that (1) clinical staging underestimates nodal involvement, causing stage IIB to have a greater percent of resected patients and (2) this stage-shift causes discrepancies in observed survival. The Surveillance, Epidemiology, and End Results (SEER) research database was used to evaluate cause-specific survival in patients with pancreatic adenocarcinoma from 2004-2012. Survival was compared using the log-rank test. Single-center data on 105 patients who underwent resection of pancreatic adenocarcinoma without neoadjuvant treatment were used to compare clinical and pathologic nodal staging. In SEER data, medium-term survival in stage IIB was superior to IB and IIA, with median cause-specific survival of 14, 9, and 11 months, respectively (P < .001). Seventy-two percent of stage IIB patients underwent resection vs 28% in IB and 36% in IIA (P < .001). In our institutional data, 12.4% of patients had clinical evidence of nodal involvement vs 69.5% by pathologic staging (P < .001). Among clinical stage IA-IIA patients, 71.6% had nodal involvement by pathologic staging. Both SEER and institutional data support substantial underestimation of nodal involvement by clinical staging. This finding has implications in decisions regarding neoadjuvant therapy and analysis of outcomes in the absence of pathologic staging. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Nodal methods for problems in fluid mechanics and neutron transport

    International Nuclear Information System (INIS)

    Azmy, Y.Y.

    1985-01-01

    A new high-accuracy, coarse-mesh, nodal integral approach is developed for the efficient numerical solution of linear partial differential equations. It is shown that various special cases of this general nodal integral approach correspond to several high efficiency nodal methods developed recently for the numerical solution of neutron diffusion and neutron transport problems. The new approach is extended to the nonlinear Navier-Stokes equations of fluid mechanics; its extension to these equations leads to a new computational method, the nodal integral method which is implemented for the numerical solution of these equations. Application to several test problems demonstrates the superior computational efficiency of this new method over previously developed methods. The solutions obtained for several driven cavity problems are compared with the available experimental data and are shown to be in very good agreement with experiment. Additional comparisons also show that the coarse-mesh, nodal integral method results agree very well with the results of definitive ultra-fine-mesh, finite-difference calculations for the driven cavity problem up to fairly high Reynolds numbers

  17. Full Atrioventricular Block Secondary to Acute Poisoning Mercury: A Case Report

    Directory of Open Access Journals (Sweden)

    Amelia Geraldine Peregrina-Chávez

    2018-04-01

    Full Text Available Background: The biological behaviour and clinical significance of mercury toxicity vary according to its chemical structure. Mercury differs in its degree of toxicity and in its effects on the nervous, digestive and immune systems as well as on organs such as the lungs, kidneys, skin, eyes and heart. Human exposure occurs mainly through inhalation of elemental mercury vapours during industrial and artisanal processes such as artisanal and small-scale gold mining. Case presentation: A 52-years-old female, housewife, with a body mass index of 25.3 kg/cm2, without smoking or alcohol habits or any important clinical or chronic cardiovascular history, was admitted to the emergency room due to probable accidental poisoning by butane gas. Clinical manifestations with a headache, dizziness, cough, and dyspnoea of medium to small efforts. An initial physical exploration with Glasgow scored at 15, with arrhythmic heart sounds, pulmonary fields with bilateral subcrepitant rales and right basal predominance. Electrocardiographic findings were as follows: a cardiac frequency of 50 beats per minute and atrioventricular dissociation. Laboratory parameters were: white blood cells at 15.8 × 109/L; aspartate aminotransferase at 38 U/L; lactate dehydrogenase at 1288 U/L; creatine-kinase at 115 U/L; CK-MB fraction at 28 U/L; and other biochemical parameters were within the reference values. A radiographic evaluation showed flow cephalization, diffuse bilateral infiltrates with right basal predominance. In addition, the patient presented data of low secondary expenditure to third-degree atrioventricular (AV block for which the placement of a transvenous pacemaker was decided, substantially improving the haemodynamic parameters. Subsequently, after a family interrogation, the diagnosis of mercury inhalation poisoning was established. An initial detection of mercury concentration (Hg(0 was carried out, reporting 243.5 µg/L. In view of this new evidence, mercury

  18. Case report of complete atrioventricular block following therapeutic irradiation for breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, Tadashi; Suzuki, Ichiro; Kobayashi, Jun; Terashima, Masafumi

    1987-12-01

    A 49-year-old woman developed complete atrioventricular (A-V) block 16 years after radiotherapy for breast cancer. The patient had received 60 Gy of cobalt 60 irradiation for left breast cancer arising 3 years after contracting right breast cancer. It took one year before complete A-V block was fixed, during which two-degree A-V block, atrial fibrillation, and sinus rhythm were predominant. She had myocardial insertion of pacemaker electrode. Fibrosis and hyaloid degeneration of the pericardium and thickened sclerosis of the epicardium seemed to be radiation-induced. There was no evidence of recurrence of breast cancer. (Namekawa, K.).

  19. Right ventricular hypoplasia syndrome. Atresia of the right atrioventricular ostium (X-ray examination)

    International Nuclear Information System (INIS)

    Golonzko, R.R.; Chernova, M.P.; Berishvili, I.I.; Bulchinskij, S.A.

    1982-01-01

    Data on routine radiologic examination of 51 patients aged 3 days to 3 years with the right atrio-ventricular ostium atresia were presented. The evidence obtained was compared with angiographic and, in part of cases, with morphometric findings. All patients were divided in two groups, depending on pulmonary circulation functions. Characteristic radiologic features of the valvular defect were revealed: ''quadrangle'' heart configuration; increase of right auricle; ''sheared off'' profile of the right ventricle, absence of increase of leftauricle in children up to 1 year

  20. Masquerading bundle branch block as a presenting manifestation of complete atrioventricular block that caused syncope.

    Science.gov (United States)

    Jiao, Zhenyu; Tian, Ying; Yang, Xinchun; Liu, Xingpeng

    2017-10-01

    A 59-year-old male patient was admitted with the main complaints of stuffiness and shortness of breath. An ECG from precordial leads on admission showed masquerading bundle branch block. Syncope frequently occurred after admission. During syncope episodes, ECG telemetry showed that the syncope was caused by intermittent complete atrioventricular block, with the longest RR interval lasting for 4.36 s. At the gap of syncope, ECG showed complete right bundle branch block accompanied by alternation of left anterior fascicular block and left posterior fascicular block. The patient was implanted with a dual-chamber permanent pacemaker. Follow-up of 9 months showed no reoccurrence of syncope.

  1. Analytic function expansion nodal method for nuclear reactor core design

    International Nuclear Information System (INIS)

    Noh, Hae Man

    1995-02-01

    In most advanced nodal methods the transverse integration is commonly used to reduce the multi-dimensional diffusion equation into equivalent one- dimensional diffusion equations when derving the nodal coupling equations. But the use of the transverse integration results in some limitations. The first limitation is that the transverse leakage term which appears in the transverse integration procedure must be appropriately approximated. The second limitation is that the one-dimensional flux shapes in each spatial direction resulted from the nodal calculation are not accurate enough to be directly used in reconstructing the pinwise flux distributions. Finally the transverse leakage defined for a non-rectangular node such as a hexagonal node or a triangular node is too complicated to be easily handled and may contain non-physical singular terms of step-function and delta-function types. In this thesis, the Analytic Function Expansion Nodal (AFEN) method and its two variations : the Polynomial Expansion Nodal (PEN) method and the hybrid of the AFEN and PEN methods, have been developed to overcome the limitations of the transverse integration procedure. All of the methods solve the multidimensional diffusion equation without the transverse integration. The AFEN method which we believe is the major contribution of this study to the reactor core analysis expands the homogeneous flux distributions within a node in non-separable analytic basis functions satisfying the neutron diffusion equations at any point of the node and expresses the coefficients of the flux expansion in terms of the nodal unknowns which comprise a node-average flux, node-interface fluxes, and corner-point fluxes. Then, the nodal coupling equations composed of the neutron balance equations, the interface current continuity equations, and the corner-point leakage balance equations are solved iteratively to determine all the nodal unknowns. Since the AFEN method does not use the transverse integration in

  2. On the Nodal Lines of Eisenstein Series on Schottky Surfaces

    Science.gov (United States)

    Jakobson, Dmitry; Naud, Frédéric

    2017-04-01

    On convex co-compact hyperbolic surfaces {X=Γ backslash H2}, we investigate the behavior of nodal curves of real valued Eisenstein series {F_λ(z,ξ)}, where {λ} is the spectral parameter, {ξ} the direction at infinity. Eisenstein series are (non-{L^2}) eigenfunctions of the Laplacian {Δ_X} satisfying {Δ_X F_λ=(1/4+λ^2)F_λ}. As {λ} goes to infinity (the high energy limit), we show that, for generic {ξ}, the number of intersections of nodal lines with any compact segment of geodesic grows like {λ}, up to multiplicative constants. Applications to the number of nodal domains inside the convex core of the surface are then derived.

  3. A computational study of nodal-based tetrahedral element behavior.

    Energy Technology Data Exchange (ETDEWEB)

    Gullerud, Arne S.

    2010-09-01

    This report explores the behavior of nodal-based tetrahedral elements on six sample problems, and compares their solution to that of a corresponding hexahedral mesh. The problems demonstrate that while certain aspects of the solution field for the nodal-based tetrahedrons provide good quality results, the pressure field tends to be of poor quality. Results appear to be strongly affected by the connectivity of the tetrahedral elements. Simulations that rely on the pressure field, such as those which use material models that are dependent on the pressure (e.g. equation-of-state models), can generate erroneous results. Remeshing can also be strongly affected by these issues. The nodal-based test elements as they currently stand need to be used with caution to ensure that their numerical deficiencies do not adversely affect critical values of interest.

  4. A theoretical study on a convergence problem of nodal methods

    Energy Technology Data Exchange (ETDEWEB)

    Shaohong, Z.; Ziyong, L. [Shanghai Jiao Tong Univ., 1954 Hua Shan Road, Shanghai, 200030 (China); Chao, Y. A. [Westinghouse Electric Company, P. O. Box 355, Pittsburgh, PA 15230-0355 (United States)

    2006-07-01

    The effectiveness of modern nodal methods is largely due to its use of the information from the analytical flux solution inside a homogeneous node. As a result, the nodal coupling coefficients depend explicitly or implicitly on the evolving Eigen-value of a problem during its solution iteration process. This poses an inherently non-linear matrix Eigen-value iteration problem. This paper points out analytically that, whenever the half wave length of an evolving node interior analytic solution becomes smaller than the size of that node, this non-linear iteration problem can become inherently unstable and theoretically can always be non-convergent or converge to higher order harmonics. This phenomenon is confirmed, demonstrated and analyzed via the simplest 1-D problem solved by the simplest analytic nodal method, the Analytic Coarse Mesh Finite Difference (ACMFD, [1]) method. (authors)

  5. Extra-nodal lymphoma. A survey of Japan lymphoma radiation therapy group

    International Nuclear Information System (INIS)

    Oguchi, Masahiko; Ikeda, Hiroshi; Nakamura, Shigeo

    2002-01-01

    The purpose of this study was to examine, retrospectively, national-wide clinical data of patients with localized extranodal non-Hodgkin's lymphoma (NHL) who were treated by radiation therapy with or without chemotherapy. The survey was carried out at 25 radiation oncology institutions in Japan in 1998. In 1999, according to the Revised European American Lymphoma (REAL) classification, central pathological review conducted at Aichi cancer center was carried out for the data from 7 radiation oncology institutions. The 5-year progression free survival rates (PFS) were calculated to identify prognostic factors. Survey: Data from 1, 141 patients with stage I and II NHL were recruited from 1988 through 1992. Of them, 787 patients, who were treated using definitive radiotherapy with or without chemotherapy for intermediate and high-grade lymphomas in Working Formulation, constituted the core of this study. Primary tumors arose mainly from extra-nodal organs (71%) in the head and neck (Waldeyer's ring: 41%, thyroid gland: 7%, nasal cavities: 5%, oral cavities: 4%, sinus: 3%, orbital structures: 3%, skin: 2% and etc.). The median age of 60 years for patients with extra-nodal NHL was higher than that of 56 years for patients with nodal NHL (p<0.01). Female were dominant in incidence of extra-nodal NHL arising from the thyroid gland, skin and gastrointestinal tract. The percentage of stage I to the extra-nodal NHL from orbit, sino-nasal presentation was higher than that of other NHLs. The percentage of stage II to the extra-nodal NHL from Waldeyer's ring and thyroid gland was higher than that of other NHLs. Central pathological review was carried out for pathological data from 79 patients (Waldeyer's ring: 45, thyroid gland: 19, sinonasal cavities: 15). Of these, diffuse large B cell lymphoma (DLBCL) composed 63% of all patients, mucosa associated lyumphoid tissue lymphoma (MALT-L): 16%, Natural Killer/T cell lymphoma (NK/T-L): 11%, and mantle cell lymphoma: 5% in REAL

  6. Acute desensitization of acetylcholine and endothelin-1 activated inward rectifier K+ current in myocytes from the cardiac atrioventricular node.

    Science.gov (United States)

    Choisy, Stéphanie C M; James, Andrew F; Hancox, Jules C

    2012-07-06

    The atrioventricular node (AVN) is a vital component of the pacemaker-conduction system of the heart, co-ordinating conduction of electrical excitation from cardiac atria to ventricles and acting as a secondary pacemaker. The electrical behaviour of the AVN is modulated by vagal activity via activation of muscarinic potassium current, IKACh. However, it is not yet known if this response exhibits 'fade' or desensitization in the AVN, as established for the heart's primary pacemaker--the sinoatrial node. In this study, acute activation of IKACh in rabbit single AVN cells was investigated using whole-cell patch clamp at 37 °C. 0.1-1 μM acetylcholine (ACh) rapidly activated a robust IKACh in AVN myocytes during a descending voltage-ramp protocol. This response was inhibited by tertiapin-Q (TQ; 300 nM) and by the M2 muscarinic ACh receptor antagonist AFDX-116 (1 μM). During sustained ACh exposure the elicited IKACh exhibited bi-exponential fade (τf of 2.0 s and τs 76.9 s at -120 mV; 1 μM ACh). 10 nM ET-1 elicited a current similar to IKACh, which faded with a mono-exponential time-course (τ of 52.6 s at -120 mV). When ET-1 was applied following ACh, the ET-1 activated response was greatly attenuated, demonstrating that ACh could desensitize the response to ET-1. For neither ACh nor ET-1 was the rate of current fade dependent upon the initial response magnitude, which is inconsistent with K+ flux mediated changes in electrochemical driving force as the underlying mechanism. Collectively, these findings demonstrate that TQ sensitive inwardly rectifying K+ current in cardiac AVN cells, elicited by M2 muscarinic receptor or ET-1 receptor activation, exhibits fade due to rapid desensitization. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Super-nodal methods for space-time kinetics

    Science.gov (United States)

    Mertyurek, Ugur

    The purpose of this research has been to develop an advanced Super-Nodal method to reduce the run time of 3-D core neutronics models, such as in the NESTLE reactor core simulator and FORMOSA nuclear fuel management optimization codes. Computational performance of the neutronics model is increased by reducing the number of spatial nodes used in the core modeling. However, as the number of spatial nodes decreases, the error in the solution increases. The Super-Nodal method reduces the error associated with the use of coarse nodes in the analyses by providing a new set of cross sections and ADFs (Assembly Discontinuity Factors) for the new nodalization. These so called homogenization parameters are obtained by employing consistent collapsing technique. During this research a new type of singularity, namely "fundamental mode singularity", is addressed in the ANM (Analytical Nodal Method) solution. The "Coordinate Shifting" approach is developed as a method to address this singularity. Also, the "Buckling Shifting" approach is developed as an alternative and more accurate method to address the zero buckling singularity, which is a more common and well known singularity problem in the ANM solution. In the course of addressing the treatment of these singularities, an effort was made to provide better and more robust results from the Super-Nodal method by developing several new methods for determining the transverse leakage and collapsed diffusion coefficient, which generally are the two main approximations in the ANM methodology. Unfortunately, the proposed new transverse leakage and diffusion coefficient approximations failed to provide a consistent improvement to the current methodology. However, improvement in the Super-Nodal solution is achieved by updating the homogenization parameters at several time points during a transient. The update is achieved by employing a refinement technique similar to pin-power reconstruction. A simple error analysis based on the relative

  8. A comparison of Nodal methods in neutron diffusion calculations

    Energy Technology Data Exchange (ETDEWEB)

    Tavron, Barak [Israel Electric Company, Haifa (Israel) Nuclear Engineering Dept. Research and Development Div.

    1996-12-01

    The nuclear engineering department at IEC uses in the reactor analysis three neutron diffusion codes based on nodal methods. The codes, GNOMERl, ADMARC2 and NOXER3 solve the neutron diffusion equation to obtain flux and power distributions in the core. The resulting flux distributions are used for the furl cycle analysis and for fuel reload optimization. This work presents a comparison of the various nodal methods employed in the above codes. Nodal methods (also called Coarse-mesh methods) have been designed to solve problems that contain relatively coarse areas of homogeneous composition. In the nodal method parts of the equation that present the state in the homogeneous area are solved analytically while, according to various assumptions and continuity requirements, a general solution is sought out. Thus efficiency of the method for this kind of problems, is very high compared with the finite element and finite difference methods. On the other hand, using this method one can get only approximate information about the node vicinity (or coarse-mesh area, usually a feel assembly of a 20 cm size). These characteristics of the nodal method make it suitable for feel cycle analysis and reload optimization. This analysis requires many subsequent calculations of the flux and power distributions for the feel assemblies while there is no need for detailed distribution within the assembly. For obtaining detailed distribution within the assembly methods of power reconstruction may be applied. However homogenization of feel assembly properties, required for the nodal method, may cause difficulties when applied to fuel assemblies with many absorber rods, due to exciting strong neutron properties heterogeneity within the assembly. (author).

  9. Nodal spectrum method for solving neutron diffusion equation

    International Nuclear Information System (INIS)

    Sanchez, D.; Garcia, C. R.; Barros, R. C. de; Milian, D.E.

    1999-01-01

    Presented here is a new numerical nodal method for solving static multidimensional neutron diffusion equation in rectangular geometry. Our method is based on a spectral analysis of the nodal diffusion equations. These equations are obtained by integrating the diffusion equation in X, Y directions and then considering flat approximations for the current. These flat approximations are the only approximations that are considered in this method, as a result the numerical solutions are completely free from truncation errors. We show numerical results to illustrate the methods accuracy for coarse mesh calculations

  10. Oddness of least energy nodal solutions on radial domains

    Directory of Open Access Journals (Sweden)

    Christopher Grumiau

    2010-07-01

    Full Text Available In this article, we consider the Lane-Emden problem $$displaylines{ Delta u(x + |{u(x}mathclose|^{p-2}u(x=0, quad hbox{for } xinOmega,cr u(x=0, quad hbox{for } xinpartialOmega, }$$ where $2 < p < 2^{*}$ and $Omega$ is a ball or an annulus in $mathbb{R}^{N}$, $Ngeq 2$. We show that, for p close to 2, least energy nodal solutions are odd with respect to an hyperplane -- which is their nodal surface. The proof ingredients are a constrained implicit function theorem and the fact that the second eigenvalue is simple up to rotations.

  11. Development and validation of a nodal code for core calculation

    International Nuclear Information System (INIS)

    Nowakowski, Pedro Mariano

    2004-01-01

    The code RHENO solves the multigroup three-dimensional diffusion equation using a nodal method of polynomial expansion.A comparative study has been made between this code and present internationals nodal diffusion codes, resulting that the RHENO is up to date.The RHENO has been integrated to a calculation line and has been extend to make burnup calculations.Two methods for pin power reconstruction were developed: modulation and imbedded. The modulation method has been implemented in a program, while the implementation of the imbedded method will be concluded shortly.The validation carried out (that includes experimental data of a MPR) show very good results and calculation efficiency

  12. Nodal algorithm derived from a new variational principle

    International Nuclear Information System (INIS)

    Watson, Fernando V.

    1995-01-01

    As a by-product of the research being carried on by the author on methods of recovering pin power distribution of PWR cores, a nodal algorithm based on a modified variational principle for the two group diffusion equations has been obtained. The main feature of the new algorithm is the low dimensionality achieved by the reduction of the original diffusion equations to a system of algebraic Eigen equations involving the average sources only, instead of sources and interface group currents used in conventional nodal methods. The advantage of this procedure is discussed and results generated by the new algorithm and by a finite difference code are compared. (author). 2 refs, 7 tabs

  13. Nodal approximations in space and time for neutron kinetics

    International Nuclear Information System (INIS)

    Grossman, L.M.; Hennart, J.P.

    2005-01-01

    A general formalism is described of the nodal type in time and space for the neutron kinetics equations. In space, several nodal methods are given of the Raviart-Thomas type (RT0 and RT1), of the Brezzi-Douglas-Marini type (BDM0 and BDM1) and of the Brezzi-Douglas-Fortin-Marini type (BDFM 1). In time, polynomial and analytical approximations are derived. In the analytical case, they are based on the inclusion of an exponential term in the basis function. They can be continuous or discontinuous in time, leading in particular to the well-known Crank-Nicolson, Backward Euler and θ schemes

  14. Regional Nodal Irradiation in Early-Stage Breast Cancer.

    Science.gov (United States)

    Whelan, Timothy J; Olivotto, Ivo A; Parulekar, Wendy R; Ackerman, Ida; Chua, Boon H; Nabid, Abdenour; Vallis, Katherine A; White, Julia R; Rousseau, Pierre; Fortin, Andre; Pierce, Lori J; Manchul, Lee; Chafe, Susan; Nolan, Maureen C; Craighead, Peter; Bowen, Julie; McCready, David R; Pritchard, Kathleen I; Gelmon, Karen; Murray, Yvonne; Chapman, Judy-Anne W; Chen, Bingshu E; Levine, Mark N

    2015-07-23

    Most women with breast cancer who undergo breast-conserving surgery receive whole-breast irradiation. We examined whether the addition of regional nodal irradiation to whole-breast irradiation improved outcomes. We randomly assigned women with node-positive or high-risk node-negative breast cancer who were treated with breast-conserving surgery and adjuvant systemic therapy to undergo either whole-breast irradiation plus regional nodal irradiation (including internal mammary, supraclavicular, and axillary lymph nodes) (nodal-irradiation group) or whole-breast irradiation alone (control group). The primary outcome was overall survival. Secondary outcomes were disease-free survival, isolated locoregional disease-free survival, and distant disease-free survival. Between March 2000 and February 2007, a total of 1832 women were assigned to the nodal-irradiation group or the control group (916 women in each group). The median follow-up was 9.5 years. At the 10-year follow-up, there was no significant between-group difference in survival, with a rate of 82.8% in the nodal-irradiation group and 81.8% in the control group (hazard ratio, 0.91; 95% confidence interval [CI], 0.72 to 1.13; P=0.38). The rates of disease-free survival were 82.0% in the nodal-irradiation group and 77.0% in the control group (hazard ratio, 0.76; 95% CI, 0.61 to 0.94; P=0.01). Patients in the nodal-irradiation group had higher rates of grade 2 or greater acute pneumonitis (1.2% vs. 0.2%, P=0.01) and lymphedema (8.4% vs. 4.5%, P=0.001). Among women with node-positive or high-risk node-negative breast cancer, the addition of regional nodal irradiation to whole-breast irradiation did not improve overall survival but reduced the rate of breast-cancer recurrence. (Funded by the Canadian Cancer Society Research Institute and others; MA.20 ClinicalTrials.gov number, NCT00005957.).

  15. Discontinuous nodal schemes applied to the bidimensional neutron transport equation

    International Nuclear Information System (INIS)

    Delfin L, A.; Valle G, E. Del; Hennart B, J.P.

    1996-01-01

    In this paper several strong discontinuous nodal schemes are described, starting from the one that has only two interpolation parameters per cell to the one having ten. Their application to the spatial discretization of the neutron transport equation in X-Y geometry is also described, giving, for each one of the nodal schemes, the approximation for the angular neutron flux that includes the set of interpolation parameters and the corresponding polynomial space. Numerical results were obtained for several test problems presenting here the problem with the highest degree of difficulty and their comparison with published results 1,2 . (Author)

  16. Nodal quasi-particles of the high-Tc superconductors as carriers of heat

    Directory of Open Access Journals (Sweden)

    K. Behnia

    2006-09-01

    Full Text Available   In the quest for understanding correlated electrons, high-temperature superconductivity remains a formidable challenge and a source of insight. This paper briefly recalls the central achievement by the study of heat transport at low temperatures. At very low temperatures, nodal quasi-particles of the d-wave superconducting gap become the main carriers of heat. Their thermal conductivity is unaffected by disorder and reflects the fine structure of the superconducting gap. This finding had led to new openings in the exploration of other unconventional superconductors

  17. Modelling the heart with the atrioventricular plane as a piston unit.

    Science.gov (United States)

    Maksuti, Elira; Bjällmark, Anna; Broomé, Michael

    2015-01-01

    Medical imaging and clinical studies have proven that the heart pumps by means of minor outer volume changes and back-and-forth longitudinal movements in the atrioventricular (AV) region. The magnitude of AV-plane displacement has also shown to be a reliable index for diagnosis of heart failure. Despite this, AV-plane displacement is usually omitted from cardiovascular modelling. We present a lumped-parameter cardiac model in which the heart is described as a displacement pump with the AV plane functioning as a piston unit (AV piston). This unit is constructed of different upper and lower areas analogous with the difference in the atrial and ventricular cross-sections. The model output reproduces normal physiology, with a left ventricular pressure in the range of 8-130 mmHg, an atrial pressure of approximatly 9 mmHg, and an arterial pressure change between 75 mmHg and 130 mmHg. In addition, the model reproduces the direction of the main systolic and diastolic movements of the AV piston with realistic velocity magnitude (∼10 cm/s). Moreover, changes in the simulated systolic ventricular-contraction force influence diastolic filling, emphasizing the coupling between cardiac systolic and diastolic functions. The agreement between the simulation and normal physiology highlights the importance of myocardial longitudinal movements and of atrioventricular interactions in cardiac pumping. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Exclusive double outlet right ventricle with atrioventricular concordance and pulmonary stenosis. Results of reconstructive surgery.

    Science.gov (United States)

    Busquet, J; Fontan, F; Choussat, A; Caianiello, G; Fernandez, G

    1988-01-01

    Double outlet right ventricle associated with atrioventricular concordance, pulmonary stenosis and situs solitus of the atria is a subset of double outlet right ventricle related through the surgical treatment. From 1974 to 1985, 14 patients, 5 males, 9 females (mean age 8.9 years, range 13 months-22 years) were operated upon. All patients had infundibular stenosis and normal or large pulmonary arteries. The apex of the heart was to the right in 2 patients, the right and left ventricles were superior and inferior in 2 patients and 1 patient had both anomalies. The ventricular septal defect was subaortic in 11 patients (aorto-mitral discontinuity in 5) and non-committed in 3 patients. Three patients had 2 ventricular septal defects. The aorta was anterior in 3 patients and to the right of the pulmonary artery in 11 patients. All patients, through a transventricular and transatrial approach, had a reconstructive surgery. In 3 patients, an aortic homograft valved conduit was used. One patient had the ventricular septal defect enlarged. There was one early death (7.1%) from high residual right ventricle pressure and no late death. One patient had a transient atrioventricular block. One patient was reoperated upon for a residual ventricular septal defect. All survivors had a good clinical result. Re-evaluation in 8 patients confirmed excellent haemodynamics: the right ventricle to pulmonary artery pressure gradient decreased from 80 mm Hg (range 60-95) preoperatively to 24 mm Hg (range 3-32) postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Echocardiography-guided Radiofrequency Catheter Ablation of Atrioventricular Node and VVI Pacemaker Implantation

    Directory of Open Access Journals (Sweden)

    T Guo

    2014-05-01

    Full Text Available Objective: This study is to evaluate the feasibility and safety of intracardiac radiofrequency catheter ablation (RFCA of the atrioventricular node (AVN and pacemaker implantation using transthoracic echocardiography. Methods: Eleven patients – six males and five females (mean age 66 years – with persistent or permanent atrial fibrillation/atrial flutter received RFCA of AVN and VVI pacemaker implantation (paces and senses the ventricle and is inhibited if it senses ventricular activity. Under transthoracic echocardiography, the electrode catheters were positioned intracardiac, and target ablation was performed, with the permanent pacemaking catheter in the left subclavian vein and the ablation catheter in the right femoral vein. The multi-view imaging and dynamic observation applied during the stable AV dissociation were successful. Results: Atrioventricular node ablation and permanent pacemaker implantation in 11 patients were completed successfully without X-ray exposure. The operation success rate was 100%. All patients recovered well within the follow-up period. Conclusions: Radiofrequency catheter ablation of AVN and VVI pacemaker implantation under transthoracic echocardiography guidance is a safe, easy and feasible approach. This procedure could be an important supplemental measure to catheter ablation of arrhythmia under routine X-ray fluoroscopy.

  20. Post-operative ventricular flow dynamics following atrioventricular valve surgical and device therapies: A review.

    Science.gov (United States)

    Nguyen, Yen Ngoc; Ismail, Munirah; Kabinejadian, Foad; Tay, Edgar Lik Wui; Leo, Hwa Liang

    2018-04-01

    Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern. In this review, current consensus around the roles of vortex dynamics in cardiac function is discussed. An overview of physiological vortex patterns found in healthy left and right ventricles as well as post-operative ventricular flow phenomenon owing to different atrioventricular valvular procedures are reviewed, followed by the summary of different vortex identification schemes used to characterise intraventricular flow. This paper also emphasises on future research directions towards a comprehensive understanding of intra-cardiac flow and its clinical relevance. The knowledge could encourage more effective pre-operative planning and better outcomes for current clinical practices. Copyright © 2018. Published by Elsevier Ltd.

  1. Extension of the linear nodal method to large concrete building calculations

    International Nuclear Information System (INIS)

    Childs, R.L.; Rhoades, W.A.

    1985-01-01

    The implementation of the linear nodal method in the TORT code is described, and the results of a mesh refinement study to test the effectiveness of the linear nodal and weighted diamond difference methods available in TORT are presented

  2. Effects of halothane on the conduction system of the heart in humans

    NARCIS (Netherlands)

    Scheffer, G. J.; Jonges, R.; Holley, H. S.; Grimbergen, C. A.; Ros, H. H.; Peper, A.; Booij, L. H.

    1989-01-01

    The effects of 2.0 MAC halothane on atrioventricular conduction times in humans were studied. A real-time recording system for the detection of surface His-Purkinje potentials based on signal averaging techniques was used. Recordings were made in 23 patients before and after the administration of

  3. Transmembrane protein 2 (Tmem2) is required to regionally restrict atrioventricular canal boundary and endocardial cushion development

    NARCIS (Netherlands)

    Smith, K.; Lagendijk, A.K.; Courtney, A.D.; Chen, H.; Paterson, S.; Hogan, B.M.; Wicking, C.; Bakkers, J.

    2011-01-01

    The atrioventricular canal (AVC) physically separates the atrial and ventricular chambers of the heart and plays a crucial role in the development of the valves and septa. Defects in AVC development result in aberrant heart morphogenesis and are a significant cause of congenital heart malformations.

  4. Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2

    NARCIS (Netherlands)

    Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M.; Cai, Chen-Leng

    2011-01-01

    During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is

  5. Cardiac complications relating to pregnancy and recurrence of disease in the offspring of women with atrioventricular septal defects

    NARCIS (Netherlands)

    Drenthen, W; Pieper, PG; van der Tuuk, K; Roos-Hesselink, JW; Voors, AA; Mostert, B; Mulder, BJM; Moons, P; Ebels, T; van Veldhuisen, DJ

    2005-01-01

    Aims In most pregnancy reports, atrioventricular septal defects (AVSD) are not differentiated from more simple septal defects, thus underestimating the risks of pregnancy. To investigate the magnitude and determinants of risk during pregnancy in female patients with balanced AVSD. Methods and

  6. Unusual diagnosis of a persistent third-degree atrioventricular block during anesthesia in a "healthy" pediatric patient

    Directory of Open Access Journals (Sweden)

    Yasser Alsayegh

    2012-01-01

    Full Text Available We present an unusual diagnosis of a permanent third-degree atrioventricular block under general anesthesia in an otherwise healthy and asymptomatic child. This diagnosis of unclear causality represented a serious rare finding, requiring judicious management and resulting in the placement of a permanent pacemaker.

  7. The Nodal Location of Metastases in Melanoma Sentinel Lymph Nodes

    DEFF Research Database (Denmark)

    Riber-Hansen, Rikke; Nyengaard, Jens; Hamilton-Dutoit, Stephen

    2009-01-01

    BACKGROUND: The design of melanoma sentinel lymph node (SLN) histologic protocols is based on the premise that most metastases are found in the central parts of the nodes, but the evidence for this belief has never been thoroughly tested. METHODS: The nodal location of melanoma metastases in 149...

  8. Real-time control of power systems using nodal prices

    NARCIS (Netherlands)

    Jokic, A.; Lazar, M.; Bosch, van den P.P.J.

    2009-01-01

    This article presents a novel control scheme for achieving optimal power balancing and congestion management in electrical power systems via nodal prices. We develop a dynamic controller that guarantees economically optimal steady-state operation while respecting all line flow constraints in

  9. Topological transport in Dirac nodal-line semimetals

    Science.gov (United States)

    Rui, W. B.; Zhao, Y. X.; Schnyder, Andreas P.

    2018-04-01

    Topological nodal-line semimetals are characterized by one-dimensional Dirac nodal rings that are protected by the combined symmetry of inversion P and time-reversal T . The stability of these Dirac rings is guaranteed by a quantized ±π Berry phase and their low-energy physics is described by a one-parameter family of (2+1)-dimensional quantum field theories exhibiting the parity anomaly. Here we study the Berry-phase supported topological transport of P T -invariant nodal-line semimetals. We find that small inversion breaking allows for an electric-field-induced anomalous transverse current, whose universal component originates from the parity anomaly. Due to this Hall-like current, carriers at opposite sides of the Dirac nodal ring flow to opposite surfaces when an electric field is applied. To detect the topological currents, we propose a dumbbell device, which uses surface states to filter charges based on their momenta. Suggestions for experiments and device applications are discussed.

  10. Hyoid bone chondrosarcoma with cervical nodal metastasis: A case ...

    African Journals Online (AJOL)

    Background: Hyoid bone chondrosarcoma is a very rare condition. This study presents a case report of low-grade chondrosarcoma of hyoid bone with cervical nodal metastasis. The study also presents preoperative radiological investigations, pathological examination and the follow-up of the case. Case presentation: A 42 ...

  11. Note on the nodal line of the p-Laplacian

    Directory of Open Access Journals (Sweden)

    Abdel R. El Amrouss

    2006-09-01

    Full Text Available In this paper, we prove that the length of the nodal line of the eigenfunctions associated to the second eigenvalue of the problem $$ -Delta_p u = lambda ho (x |u|^{p-2}u quad hbox{in } Omega $$ with the Dirichlet conditions is not bounded uniformly with respect to the weight.

  12. A nodal method based on the response-matrix method

    International Nuclear Information System (INIS)

    Cunha Menezes Filho, A. da; Rocamora Junior, F.D.

    1983-02-01

    A nodal approach based on the Response-Matrix method is presented with the purpose of investigating the possibility of mixing two different allocations in the same problem. It is found that the use of allocation of albedo combined with allocation of direct reflection produces good results for homogeneous fast reactor configurations. (Author) [pt

  13. CRY 1AB trangenic cowpea obtained by nodal electroporation ...

    African Journals Online (AJOL)

    Electroporation-mediated genetic transformation was used to introduce Cry 1 Ab insecticidal gene into cowpea. Nodal buds were electroporated in planta with a plasmid carrying the Cry 1Ab and antibiotic resistance npt II genes driven by a 35S CaMV promoter. T1 seeds derived from electroporated branches were selected ...

  14. 47 CFR 101.503 - Digital Electronic Message Service Nodal Stations.

    Science.gov (United States)

    2010-10-01

    ... Service § 101.503 Digital Electronic Message Service Nodal Stations. 10.6 GHz DEMS Nodal Stations may be... 47 Telecommunication 5 2010-10-01 2010-10-01 false Digital Electronic Message Service Nodal Stations. 101.503 Section 101.503 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY...

  15. Female preponderance in atrioventricular node reentrant tachycardia, but no sex related electrophysiological differences

    Directory of Open Access Journals (Sweden)

    Claes Williamsson

    2014-01-01

    Full Text Available The mechanism behind the female preponderance for atrio-ventricular node reentrant tachycardia (AVNRT is not clear. We compared baseline electrophysiological measurements and clinical data in 141 consecutive patients (96 women who underwent successful AVNRT ablation at their fi rst therapeutic procedure. Women had on average 9% higher resting heart rate than men (p<0.05, but were similar in all measures of AV node function. Isoproterenol infusion was required for AVNRT induction in 69 cases (49%, and the need for isoproterenol was associated with lower resting heart rate and longer anterograde and retrograde AV node refractory periods (p<0.05 for comparisons, but not with sex. We conclude that the spectrum of baseline AV node physiology in AVNRT patients is wide, and is similar in men and women. The female preponderance for AVNRT cannot be explained from comparisons of baseline AV node electrophysiological properties.

  16. Complete Atrioventricular Block Complicating Mitral Infective Endocarditis Caused by Streptococcus Agalactiae.

    Science.gov (United States)

    Arai, Masaru; Nagashima, Koichi; Kato, Mahoto; Akutsu, Naotaka; Hayase, Misa; Ogura, Kanako; Iwasawa, Yukino; Aizawa, Yoshihiro; Saito, Yuki; Okumura, Yasuo; Nishimaki, Haruna; Masuda, Shinobu; Hirayama, Astushi

    2016-09-08

    BACKGROUND Infective endocarditis (IE) involving the mitral valve can but rarely lead to complete atrioventricular block (CAVB). CASE REPORT A 74-year-old man with a history of infective endocarditis caused by Streptococcus gordonii (S. gordonii) presented to our emergency room with fever and loss of appetite, which had lasted for 5 days. On admission, results of serologic tests pointed to severe infection. Electrocardiography showed normal sinus rhythm with first-degree atrioventricular block and incomplete right bundle branch block, and transthoracic echocardiography and transesophageal echocardiography revealed severe mitral regurgitation caused by posterior leaflet perforation and 2 vegetations (5 mm and 6 mm) on the tricuspid valve. The patient was initially treated with ceftriaxone and gentamycin because blood and cutaneous ulcer cultures yielded S. agalactiae. On hospital day 2, however, sudden CAVB requiring transvenous pacing occurred, and the patient's heart failure and infection worsened. Although an emergent surgery is strongly recommended, even in patients with uncontrolled heart failure or infection, surgery was not performed because of the Child-Pugh class B liver cirrhosis. Despite intensive therapy, the patient's condition further deteriorated, and he died on hospital day 16. On postmortem examination, a 2×1-cm vegetation was seen on the perforated posterior mitral leaflet, and the infection had extended to the interventricular septum. Histologic examination revealed extensive necrosis of the AV node. CONCLUSIONS This rare case of CAVB resulting from S. agalactiae IE points to the fact that in monitoring patients with IE involving the mitral valve, clinicians should be aware of the potential for perivalvular extension of the infection, which can lead to fatal heart block.

  17. Inverse Relationship Between Membranous Septal Length and the Risk of Atrioventricular Block in Patients Undergoing Transcatheter Aortic Valve Implantation.

    Science.gov (United States)

    Hamdan, Ashraf; Guetta, Victor; Klempfner, Robert; Konen, Eli; Raanani, Ehud; Glikson, Michael; Goitein, Orly; Segev, Amit; Barbash, Israel; Fefer, Paul; Spiegelstein, Dan; Goldenberg, Ilan; Schwammenthal, Ehud

    2015-08-17

    This study sought to examine whether imaging of the atrioventricular (AV) membranous septum (MS) by computed tomography (CT) can be used to identify patient-specific anatomic risk of high-degree AV block and permanent pacemaker (PPM) implantation before transcatheter aortic valve implantation (TAVI) with self-expandable valves. MS length represents an anatomic surrogate of the distance between the aortic annulus and the bundle of His and may therefore be inversely related to the risk of conduction system abnormalities after TAVI. Seventy-three consecutive patients with severe aortic stenosis underwent contrast-enhanced CT before TAVI. The aortic annulus, aortic valve, and AV junction were assessed, and MS length was measured in the coronal view. In 13 patients (18%), high-degree AV block developed, and 21 patients (29%) received a PPM. Multivariable logistic regression analysis revealed MS length as the most powerful pre-procedural independent predictor of high-degree AV block (odds ratio [OR]: 1.35, 95% confidence interval [CI]: 1.1 to 1.7, p = 0.01) and PPM implantation (OR: 1.43, 95% CI: 1.1 to 1.8, p = 0.002). When taking into account pre- and post-procedural parameters, the difference between MS length and implantation depth emerged as the most powerful independent predictor of high-degree AV block (OR: 1.4, 95% CI: 1.2 to 1.7, p < 0.001), whereas the difference between MS length and implantation depth and calcification in the basal septum were the most powerful independent predictors of PPM implantation (OR: 1.39, 95% CI: 1.2 to 1.7, p < 0.001 and OR: 4.9, 95% CI: 1.2 to 20.5, p = 0.03; respectively). Short MS, insufficient difference between MS length and implantation depth, and the presence of calcification in the basal septum, factors that may all facilitate mechanical compression of the conduction tissue by the implanted valve, predict conduction abnormalities after TAVI with self-expandable valves. CT assessment of membranous septal anatomy provides

  18. Endomiocardiofibrose: resultados do tratamento cirúrgico com conservação das valvas atrioventriculares Endomyocardial fibrosis: results of the surgical treatment with atrioventricular valve preservation

    Directory of Open Access Journals (Sweden)

    Sérgio Almeida de Oliveira

    1991-04-01

    Full Text Available Entre abril de 1988 e janeiro de 1991, foram operados 25 pacientes consecutivos, para correção de endomiocardiofibrose, com técnica conservadora das valvas atrioventriculares. Dezenove pacientes eram do sexo feminino e seis do masculino. As idades variaram de 11 a 59 anos, com média de 40,6 anos. Dezesete pacientes apresentavam acometimento biventricular, seis com comprometimento do ventrículo esquerdo e apenas dois pacientes com lesão isolada do ventrículo direito. Todos estavam em grupos avançados de insuficiência cardíaca, sendo 19 em grupo IV da NYHA e seis no grupo III. No pré-operatório, 24 apresentavam insuficiência da valva tricúspide e 22 apresentavam insuficiência da valva mitral. Todos os pacientes foram operados com o auxílio de circulação extracorpórea e hipotermia sistêmica de 28ºC e pinçamento aórtico intermitente, para melhor exposição das cavidades ventriculares. A fibrose ventricular direita foi sempre ressecada através da valva tricúspide, enquanto que a fibrose do ventrículo esquerdo foi removida através de pequena ventriculotomia esquerda apical. Em todos os pacientes com insuficiência tricúspide, foi feita plástica anular do tipo DeVega. Dos pacientes com insuficiência mitral, sete tiveram correção espontânea após a ressecção da fibrose, e os outros 15 receberam anuloplastia. Houve apenas um (4% óbito no pós-operatório imediato e nenhum óbito tardio. A recuperação funcional foi boa, estando atualmente 16 pacientes em grupo funcional I e 8 em grupo II.Between April 1988 and January 1991 we operated on 25 consecutive patients with endomyocardial fibrosis (EMF with an approach to preserve the atrioventricular valves. Nineteen patients were females and six males. Their ages ranged from 11 to 5 years, with an average of 40.6 years. Seventeen patients had biventricular involvement, six had involvement of the left ventricle and only two patients had an isolated lesion of the right

  19. Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure.

    Science.gov (United States)

    Schnittger, I; Appleton, C P; Hatle, L K; Popp, R L

    1988-01-01

    The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. Eleven patients had third degree AV block and a ventricular-inhibited (VVI) pacemaker, two patients had second degree AV block, seven patients had first degree AV block, one patient had blocked premature atrial complexes and one patient had atrial flutter with 4:1 AV block. Diastolic mitral regurgitation was detected in 20 patients, and diastolic tricuspid regurgitation in 21. A mid-diastolic murmur was detected in all patients except in the three youngest. The murmur occurred before diastolic regurgitation and coincided with peak forward flow through the AV valve after atrial contraction. M-mode mitral valve echocardiograms obtained in nine patients demonstrated near closure of some portions of the mitral valve after atrial contraction. Effective closure of the valve, however, did not occur unless ventricular systole supervened. In conclusion, diastolic mitral and tricuspid regurgitation are almost universally present in patients with AV block and are associated with a diastolic murmur. The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.

  20. Disturbed Intracardiac Flow Organization After Atrioventricular Septal Defect Correction as Assessed With 4D Flow Magnetic Resonance Imaging and Quantitative Particle Tracing

    NARCIS (Netherlands)

    Calkoen, Emmeline E.; de Koning, Patrick J. H.; Blom, Nico A.; Kroft, Lucia J. M.; de Roos, Albert; Wolterbeek, Ron; Roest, Arno A. W.; Westenberg, Jos J. M.

    2015-01-01

    Objectives Four-dimensional (3 spatial directions and time) velocity-encoded flow magnetic resonance imaging with quantitative particle tracing analysis allows assessment of left ventricular (LV) blood flow organization. Corrected atrioventricular septal defect (AVSD) patients have an abnormal left

  1. Defeito do septo atrioventricular forma total associado a tricuspidização da valva atrioventricular esquerda na infância

    Directory of Open Access Journals (Sweden)

    Aleksander DOBRIANSKYJ

    1997-10-01

    Full Text Available Entre maio de 1987 e dezembro de 1996, o reparo do defeito do septo atrioventricular, forma total (DSAVT, com duplo retalho de pericárdio bovino e tricuspidização da valva atrioventricular (VAV esquerda, foi realizado em 34 pacientes consecutivos com mortalidade global de 5 (14,7% pacientes (pac.. Grupo I: abaixo de 6 meses (m com 12 pac. (1 óbito; 8,3%; Grupo II: entre 7m e 12m, com 15 pac. (4 óbitos; 26,6% e Grupo III: entre 1 e 5 anos (a com 7 pac. sem óbitos. Ocorreram 2 óbitos tardios (1 por Insuficiência mitral residual + insuficiência cardíaca congestiva e outro por pneumonia + insuficiência respiratória. Duas crianças receberam implante de marcapasso definitivo (após 45 dias e 4 anos. Nenhum paciente foi reoperado, apesar de mais 2 apresentarem insuficiência da VAV esquerda e 1 VAV direita, controlada clinicamente, e as restantes encontram-se nos graus I e II da New York Heart Association (NYHA. Apesar de 29 pacientes apresentarem peso abaixo de 10 kg, utilizou-se circulação extracorpórea (CEC e hipotermia a 25°C sem parada circulatória total. Iniciou-se o reparo pela zona de "aposição" da VAV única com um ou dois pontos em "x", mantendo tricúspide. Sutura-se o primeiro retalho de pericárdio bovino (PB em forma de "gota", insinuando-o entre as cordas do lado direito do septo; a seguir, sutura-se o segundo retalho, fazendo uma aposição concomitante com a VAV única, septando-se, desta forma, as quatro cavidades. As vantagens desta técnica são: preservação da integridade valvar, maior durabilidade funcional da VAV esquerda, menor possibilidade de reoperação mesmo em pacientes mais jovens e que devem ser preferencialmente operados em torno de 6º mês de vida.Between May 1987 and December 1996, repair of the "Ostium Atrioventricularis Communis" (OAVC, with total shaping by means of a double bovine pericardial patch and tricuspidation of the left atrioventricular valve (AVV was performed on 34 consecutive

  2. New procedure for criticality search using coarse mesh nodal methods

    International Nuclear Information System (INIS)

    Pereira, Wanderson F.; Silva, Fernando C. da; Martinez, Aquilino S.

    2011-01-01

    The coarse mesh nodal methods have as their primary goal to calculate the neutron flux inside the reactor core. Many computer systems use a specific form of calculation, which is called nodal method. In classical computing systems that use the criticality search is made after the complete convergence of the iterative process of calculating the neutron flux. In this paper, we proposed a new method for the calculation of criticality, condition which will be over very iterative process of calculating the neutron flux. Thus, the processing time for calculating the neutron flux was reduced by half compared with the procedure developed by the Nuclear Engineering Program of COPPE/UFRJ (PEN/COPPE/UFRJ). (author)

  3. New procedure for criticality search using coarse mesh nodal methods

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wanderson F.; Silva, Fernando C. da; Martinez, Aquilino S., E-mail: wneto@con.ufrj.b, E-mail: fernando@con.ufrj.b, E-mail: Aquilino@lmp.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2011-07-01

    The coarse mesh nodal methods have as their primary goal to calculate the neutron flux inside the reactor core. Many computer systems use a specific form of calculation, which is called nodal method. In classical computing systems that use the criticality search is made after the complete convergence of the iterative process of calculating the neutron flux. In this paper, we proposed a new method for the calculation of criticality, condition which will be over very iterative process of calculating the neutron flux. Thus, the processing time for calculating the neutron flux was reduced by half compared with the procedure developed by the Nuclear Engineering Program of COPPE/UFRJ (PEN/COPPE/UFRJ). (author)

  4. The variational nodal method: history and recent accomplishments

    International Nuclear Information System (INIS)

    Lewis, E.E.

    2004-01-01

    The variational nodal method combines spherical harmonics expansions in angle with hybrid finite element techniques is space to obtain multigroup transport response matrix algorithms applicable to both deep penetration and reactor core physics problems. This survey briefly recounts the method's history and reviews its capabilities. The variational basis for the approach is presented and two methods for obtaining discretized equations in the form of response matrices are detailed. The first is that contained the widely used VARIANT code, while the second incorporates newly developed integral transport techniques into the variational nodal framework. The two approaches are combined with a finite sub element formulation to treat heterogeneous nodes. Applications are presented for both a deep penetration problem and to an OECD benchmark consisting of LWR MOX fuel assemblies. Ongoing work is discussed. (Author)

  5. Radiological signs of extra nodal abdominal involvements in lymphoma

    International Nuclear Information System (INIS)

    Carro, A.I.; Alegre, N.; Cervera, J.L.; Montero, A.I.

    1998-01-01

    To assess abdominal CT images in lymphoma patients for the study of extra nodal abdominal involvement. Ninety-two patients diagnosed as having lymphoma were studied retrospectively. All the patients underwent abdominopelvic CT with oral and intravenous contrast (except in one patient who was allergic). In every case, the diagnosis was confirmed by biopsy or radiological follow-up after treatment had been completed. Fifty-two patients (56.5%) presented infiltration of extra nodal organs. The organs most frequently involved were liver and spleen, followed by the gastrointestinal tract, the musculoskeletal system and the genitourinary tract. The findings in this study coincide with those reported elsewhere with the exception of the splenic involvement the incidence of which was lower in the present series. (Author) 17 refs

  6. On the nodal structure of atomic and molecular Wigner functions

    International Nuclear Information System (INIS)

    Dahl, J.P.; Schmider, H.

    1996-01-01

    In previous work on the phase-space representation of quantum mechanics, we have presented detailed pictures of the electronic one-particle reduced Wigner function for atoms and small molecules. In this communication, we focus upon the nodal structure of the function. On the basis of the simplest systems, we present an expression which relates the oscillatory decay of the Wigner function solely to the dot product of the position and momentum vector, if both arguments are large. We then demonstrate the regular behavior of nodal patterns for the larger systems. For the molecular systems, an argument analogous to the open-quotes bond-oscillatory principleclose quotes for momentum densities links the nuclear framework to an additional oscillatory term in momenta parallel to bonds. It is shown that these are visible in the Wigner function in terms of characteristic nodes

  7. An alternative solver for the nodal expansion method equations - 106

    International Nuclear Information System (INIS)

    Carvalho da Silva, F.; Carlos Marques Alvim, A.; Senra Martinez, A.

    2010-01-01

    An automated procedure for nuclear reactor core design is accomplished by using a quick and accurate 3D nodal code, aiming at solving the diffusion equation, which describes the spatial neutron distribution in the reactor. This paper deals with an alternative solver for nodal expansion method (NEM), with only two inner iterations (mesh sweeps) per outer iteration, thus having the potential to reduce the time required to calculate the power distribution in nuclear reactors, but with accuracy similar to the ones found in conventional NEM. The proposed solver was implemented into a computational system which, besides solving the diffusion equation, also solves the burnup equations governing the gradual changes in material compositions of the core due to fuel depletion. Results confirm the effectiveness of the method for practical purposes. (authors)

  8. Topological and trivial magnetic oscillations in nodal loop semimetals

    Science.gov (United States)

    Oroszlány, László; Dóra, Balázs; Cserti, József; Cortijo, Alberto

    2018-05-01

    Nodal loop semimetals are close descendants of Weyl semimetals and possess a topologically dressed band structure. We argue by combining the conventional theory of magnetic oscillation with topological arguments that nodal loop semimetals host coexisting topological and trivial magnetic oscillations. These originate from mapping the topological properties of the extremal Fermi surface cross sections onto the physics of two dimensional semi-Dirac systems, stemming from merging two massless Dirac cones. By tuning the chemical potential and the direction of magnetic field, a sharp transition is identified from purely trivial oscillations, arising from the Landau levels of a normal two dimensional (2D) electron gas, to a phase where oscillations of topological and trivial origin coexist, originating from 2D massless Dirac and semi-Dirac points, respectively. These could in principle be directly identified in current experiments.

  9. RELAP 4/MOD 6 boiling water nodalization study

    International Nuclear Information System (INIS)

    Sonneck, G.; Pfau, H.

    1985-09-01

    The risk of nuclear steam supply systems is dominated by the core melt accidents. The first step to a realistic assessment of these sequences is the successful prediction of a loss of coolant event in a test loop. One of the codes for that is RELAP 4/MOD 6 and one of the important options in this code is the nodalization. The base of this work is the test LOCA No. 1 FIX II in Studsvik (Sweden) which also served as the OECD International Standard Problem 15. This report discusses the influence of different nodalizations, of different distributions of pressure, water and structural heat as well as of different bubble rise options, break flow coefficients, and heat transfer time steps. The most important result is that a simple RELAP 4/MOD6 model with less than 10 volumes is able to predict an experiment as LOCA No. 1 in FIX II successfully using only a fraction of the usual computing time. (Author)

  10. The variational nodal method: some history and recent activity

    International Nuclear Information System (INIS)

    Lewis, E.E.; Smith, M.A.; Palmiotti, G.

    2005-01-01

    The variational nodal method combines spherical harmonics expansions in angle with hybrid finite element techniques in space to obtain multigroup transport response matrix algorithms applicable to a wide variety of reactor physics problems. This survey briefly recounts the method's history and reviews its capabilities. Two methods for obtaining discretized equations in the form of response matrices are compared. The first is that contained the widely used VARIANT code, while the second incorporates more recently developed integral transport techniques into the variational nodal framework. The two approaches are combined with a finite sub-element formulation to treat heterogeneous nodes. Results are presented for application to a deep penetration problem and to an OECD benchmark consisting of LWR Mox fuel assemblies. Ongoing work is discussed. (authors)

  11. Hybrid microscopic depletion model in nodal code DYN3D

    International Nuclear Information System (INIS)

    Bilodid, Y.; Kotlyar, D.; Shwageraus, E.; Fridman, E.; Kliem, S.

    2016-01-01

    Highlights: • A new hybrid method of accounting for spectral history effects is proposed. • Local concentrations of over 1000 nuclides are calculated using micro depletion. • The new method is implemented in nodal code DYN3D and verified. - Abstract: The paper presents a general hybrid method that combines the micro-depletion technique with correction of micro- and macro-diffusion parameters to account for the spectral history effects. The fuel in a core is subjected to time- and space-dependent operational conditions (e.g. coolant density), which cannot be predicted in advance. However, lattice codes assume some average conditions to generate cross sections (XS) for nodal diffusion codes such as DYN3D. Deviation of local operational history from average conditions leads to accumulation of errors in XS, which is referred as spectral history effects. Various methods to account for the spectral history effects, such as spectral index, burnup-averaged operational parameters and micro-depletion, were implemented in some nodal codes. Recently, an alternative method, which characterizes fuel depletion state by burnup and 239 Pu concentration (denoted as Pu-correction) was proposed, implemented in nodal code DYN3D and verified for a wide range of history effects. The method is computationally efficient, however, it has applicability limitations. The current study seeks to improve the accuracy and applicability range of Pu-correction method. The proposed hybrid method combines the micro-depletion method with a XS characterization technique similar to the Pu-correction method. The method was implemented in DYN3D and verified on multiple test cases. The results obtained with DYN3D were compared to those obtained with Monte Carlo code Serpent, which was also used to generate the XS. The observed differences are within the statistical uncertainties.

  12. SPANDOM - source projection analytic nodal discrete ordinates method

    International Nuclear Information System (INIS)

    Kim, Tae Hyeong; Cho, Nam Zin

    1994-01-01

    We describe a new discrete ordinates nodal method for the two-dimensional transport equation. We solve the discrete ordinates equation analytically after the source term is projected and represented in polynomials. The method is applied to two fast reactor benchmark problems and compared with the TWOHEX code. The results indicate that the present method accurately predicts not only multiplication factor but also flux distribution

  13. HEXAN - a hexagonal nodal code for solving the diffusion equation

    International Nuclear Information System (INIS)

    Makai, M.

    1982-07-01

    This report describes the theory of and provides a user's manual for the HEXAN program, which is a nodal program for the solution of the few-group diffusion equation in hexagonal geometry. Based upon symmetry considerations, the theory provides an analytical solution in a homogeneous node. WWER and HTGR test problem solutions are presented. The equivalence of the finite-difference scheme and the response matrix method is proven. The properties of a symmetric node's response matrix are investigated. (author)

  14. NOMAD: a nodal microscopic analysis method for nuclear fuel depletion

    International Nuclear Information System (INIS)

    Rajic, H.L.; Ougouag, A.M.

    1987-01-01

    Recently developed assembly homogenization techniques made possible very efficient global burnup calculations based on modern nodal methods. There are two possible ways of modeling the global depletion process: macroscopic and microscopic depletion models. Using a microscopic global depletion approach NOMAD (NOdal Microscopic Analysis Method for Nuclear Fuel Depletion), a multigroup, two- and three-dimensional, multicycle depletion code was devised. The code uses the ILLICO nodal diffusion model. The formalism of the ILLICO methodology is extended to treat changes in the macroscopic cross sections during a depletion cycle without recomputing the coupling coefficients. This results in a computationally very efficient method. The code was tested against a well-known depletion benchmark problem. In this problem a two-dimensional pressurized water reactor is depleted through two cycles. Both cycles were run with 1 x 1 and 2 x 2 nodes per assembly. It is obvious that the one node per assembly solution gives unacceptable results while the 2 x 2 solution gives relative power errors consistently below 2%

  15. Applications of a systematic homogenization theory for nodal diffusion methods

    International Nuclear Information System (INIS)

    Zhang, Hong-bin; Dorning, J.J.

    1992-01-01

    The authors recently have developed a self-consistent and systematic lattice cell and fuel bundle homogenization theory based on a multiple spatial scales asymptotic expansion of the transport equation in the ratio of the mean free path to the reactor characteristics dimension for use with nodal diffusion methods. The mathematical development leads naturally to self-consistent analytical expressions for homogenized diffusion coefficients and cross sections and flux discontinuity factors to be used in nodal diffusion calculations. The expressions for the homogenized nuclear parameters that follow from the systematic homogenization theory (SHT) are different from those for the traditional flux and volume-weighted (FVW) parameters. The calculations summarized here show that the systematic homogenization theory developed recently for nodal diffusion methods yields accurate values for k eff and assembly powers even when compared with the results of a fine mesh transport calculation. Thus, it provides a practical alternative to equivalence theory and GET (Ref. 3) and to simplified equivalence theory, which requires auxiliary fine-mesh calculations for assemblies embedded in a typical environment to determine the discontinuity factors and the equivalent diffusion coefficient for a homogenized assembly

  16. Flow-based market coupling. Stepping stone towards nodal pricing?

    International Nuclear Information System (INIS)

    Van der Welle, A.J.

    2012-07-01

    For achieving one internal energy market for electricity by 2014, market coupling is deployed to integrate national markets into regional markets and ultimately one European electricity market. The extent to which markets can be coupled depends on the available transmission capacities between countries. Since interconnections are congested from time to time, congestion management methods are deployed to divide the scarce available transmission capacities over market participants. For further optimization of the use of available transmission capacities while maintaining current security of supply levels, flow-based market coupling (FBMC) will be implemented in the CWE region by 2013. Although this is an important step forward, important hurdles for efficient congestion management remain. Hence, flow based market coupling is compared to nodal pricing, which is often considered as the most optimal solution from theoretical perspective. In the context of decarbonised power systems it is concluded that advantages of nodal pricing are likely to exceed its disadvantages, warranting further development of FBMC in the direction of nodal pricing.

  17. NODAL3 Sensitivity Analysis for NEACRP 3D LWR Core Transient Benchmark (PWR

    Directory of Open Access Journals (Sweden)

    Surian Pinem

    2016-01-01

    Full Text Available This paper reports the results of sensitivity analysis of the multidimension, multigroup neutron diffusion NODAL3 code for the NEACRP 3D LWR core transient benchmarks (PWR. The code input parameters covered in the sensitivity analysis are the radial and axial node sizes (the number of radial node per fuel assembly and the number of axial layers, heat conduction node size in the fuel pellet and cladding, and the maximum time step. The output parameters considered in this analysis followed the above-mentioned core transient benchmarks, that is, power peak, time of power peak, power, averaged Doppler temperature, maximum fuel centerline temperature, and coolant outlet temperature at the end of simulation (5 s. The sensitivity analysis results showed that the radial node size and maximum time step give a significant effect on the transient parameters, especially the time of power peak, for the HZP and HFP conditions. The number of ring divisions for fuel pellet and cladding gives negligible effect on the transient solutions. For productive work of the PWR transient analysis, based on the present sensitivity analysis results, we recommend NODAL3 users to use 2×2 radial nodes per assembly, 1×18 axial layers per assembly, the maximum time step of 10 ms, and 9 and 1 ring divisions for fuel pellet and cladding, respectively.

  18. Modulation by endothelin-1 of spontaneous activity and membrane currents of atrioventricular node myocytes from the rabbit heart.

    Directory of Open Access Journals (Sweden)

    Stéphanie C Choisy

    Full Text Available The atrioventricular node (AVN is a key component of the cardiac pacemaker-conduction system. Although it is known that receptors for the peptide hormone endothelin-1 (ET-1 are expressed in the AVN, there is very little information available on the modulatory effects of ET-1 on AVN electrophysiology. This study characterises for the first time acute modulatory effects of ET-1 on AVN cellular electrophysiology.Electrophysiological experiments were conducted in which recordings were made from rabbit isolated AVN cells at 35-37°C using the whole-cell patch clamp recording technique.Application of ET-1 (10 nM to spontaneously active AVN cells led rapidly (within ~13 s to membrane potential hyperpolarisation and cessation of spontaneous action potentials (APs. This effect was prevented by pre-application of the ET(A receptor inhibitor BQ-123 (1 µM and was not mimicked by the ET(B receptor agonist IRL-1620 (300 nM. In whole-cell voltage-clamp experiments, ET-1 partially inhibited L-type calcium current (I(Ca,L and rapid delayed rectifier K(+ current (I(Kr, whilst it transiently activated the hyperpolarisation-activated current (I(f at voltages negative to the pacemaking range, and activated an inwardly rectifying current that was inhibited by both tertiapin-Q (300 nM and Ba(2+ ions (2 mM; each of these effects was sensitive to ET(A receptor inhibition. In cells exposed to tertiapin-Q, ET-1 application did not produce membrane potential hyperpolarisation or immediate cessation of spontaneous activity; instead, there was a progressive decline in AP amplitude and depolarisation of maximum diastolic potential.Acutely applied ET-1 exerts a direct modulatory effect on AVN cell electrophysiology. The dominant effect of ET-1 in this study was activation of a tertiapin-Q sensitive inwardly rectifying K(+ current via ET(A receptors, which led rapidly to cell quiescence.

  19. Patterns of practice of regional nodal irradiation in breast cancer: results of the European Organization for Research and Treatment of Cancer (EORTC) NOdal Radiotherapy (NORA) survey

    NARCIS (Netherlands)

    Belkacemi, Y.; Kaidar-Person, O.; Poortmans, P.; Ozsahin, M.; Valli, M.-C.; Russell, N.; Kunkler, I.; Hermans, J.; Kuten, A.; van Tienhoven, G.; Westenberg, H.

    2015-01-01

    Predicting outcome of breast cancer (BC) patients based on sentinel lymph node (SLN) status without axillary lymph node dissection (ALND) is an area of uncertainty. It influences the decision-making for regional nodal irradiation (RNI). The aim of the NORA (NOdal RAdiotherapy) survey was to examine

  20. Echocardiographic definition and surgical decision-making in unbalanced atrioventricular septal defect: a Congenital Heart Surgeons' Society multiinstitutional study.

    Science.gov (United States)

    Jegatheeswaran, Anusha; Pizarro, Christian; Caldarone, Christopher A; Cohen, Meryl S; Baffa, Jeanne M; Gremmels, David B; Mertens, Luc; Morell, Victor O; Williams, William G; Blackstone, Eugene H; McCrindle, Brian W; Overman, David M

    2010-09-14

    Although identification of unbalanced atrioventricular septal defect (AVSD) is obvious when extreme, exact criteria to define the limits of unbalanced are not available. We sought to validate an atrioventricular valve index (AVVI) (left atrioventricular valve area/total atrioventricular valve area, centimeters squared) as a discriminator of balanced and unbalanced forms of complete AVSD and to characterize the association of AVVI with surgical strategies and outcomes. Diagnostic echocardiograms and hospital records of 356 infants with complete AVSD at 4 Congenital Heart Surgeons' Society (CHSS) institutions (2000-2006) were reviewed and AVVI measured (n=315). Patients were classified as unbalanced if AVVI≤0.4 (right dominant) or ≥0.6 (left dominant). Surgical strategy and outcomes were examined across the range of AVVI. Competing risks analysis until the time of commitment to a surgical strategy examined 4 end states: biventricular repair (BVR), univentricular repair (UVR), pulmonary artery banding (PAB), and death before surgery. A prediction nomogram for surgical strategy based on AVVI was developed. The majority of patients had balanced AVSD (0.4

  1. High-degree atrioventricular block complicating ST-segment elevation myocardial infarction in the era of primary percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Gang, Uffe Jakob Ortved; Hvelplund, Anders; Pedersen, Sune

    2012-01-01

    Primary percutaneous coronary intervention (pPCI) has replaced thrombolysis as treatment-of-choice for ST-segment elevation myocardial infarction (STEMI). However, the incidence and prognostic significance of high-degree atrioventricular block (HAVB) in STEMI patients in the pPCI era has been only...... sparsely investigated. The objective of this study was to assess the incidence, predictors and prognostic significance of HAVB in STEMI patients treated with pPCI....

  2. Surface and 3D Quantum Hall Effects from Engineering of Exceptional Points in Nodal-Line Semimetals

    Science.gov (United States)

    Molina, Rafael A.; González, José

    2018-04-01

    We show that, under a strong magnetic field, a 3D nodal-line semimetal is driven into a topological insulating phase in which the electronic transport takes place at the surface of the material. When the magnetic field is perpendicular to the nodal ring, the surface states of the semimetal are transmuted into Landau states which correspond to exceptional points, i.e., branch points in the spectrum of a non-Hermitian Hamiltonian which arise upon the extension to complex values of the momentum. The complex structure of the spectrum then allows us to express the number of zero-energy flat bands in terms of a new topological invariant counting the number of exceptional points. When the magnetic field is parallel to the nodal ring, we find that the bulk states are built from the pairing of surfacelike evanescent waves, giving rise to a 3D quantum Hall effect with a flat level of Landau states residing in parallel 2D slices of the 3D material. The Hall conductance is quantized in either case in units of e2/h , leading in the 3D Hall effect to a number of channels growing linearly with the section of the surface and opening the possibility to observe a macroscopic chiral current at the surface of the material.

  3. Echocardiographic estimation of acute haemodynamic response during optimization of multisite pace-maker using different pacing modalities and atrioventricular delays

    Directory of Open Access Journals (Sweden)

    Šalinger-Martinović Sonja

    2009-01-01

    Full Text Available Background/Aim. Cardiac resynchronization therapy (CRT improves ventricular dyssynchrony and is associated with an improvement in symptoms, quality of life and prognosis in patients with severe heart failure and intraventricular conduction delay. Different pacing modalities produce variable activation patterns and may be a cause of different haemodynamic changes. The aim of our study was to investigate acute haemodynamic changes with different CRT configurations during optimization procedure. Methods. This study included 30 patients with severe left ventricular systolic dysfunction and left bundle branch block with wide QRS (EF 24.33 ± 3.7%, QRS 159 ± 17.3 ms, New York Heart Association III/IV 25/5 with implanted CRT device. The whole group of patients had severe mitral regurgitation in order to measure dP/dt. After implantation and before discharge all the patients underwent optimization procedure guided by Doppler echocardiography. Left and right ventricular pre-ejection intervals (LVPEI and RVPEI, interventricular mechanical delay (IVD and the maximal rate of ventricular pressure rise during early systole (max dP/dt were measured during left and biventricular pacing with three different atrioventricular (AV delays. Results. After CRT device optimization, optimal AV delay and CRT mode were defined. Left ventricular pre-ejection intervals changed from 170.5 ± 24.6 to 145.9 ± 9.5 (p < 0.001, RVPEI from 102.4 ± 15.9 to 119.8 ± 10.9 (p < 0.001, IVD from 68.1 ± 18.3 to 26.5 ± 8.2 (p < 0.001 and dP/dt from 524.2 ± 67 to 678.2 ± 88.5 (p < 0.01. Conclusion. In patients receiving CRT echocardiographic assessment of the acute haemodynamic response to CRT is a useful tool in optimization procedure. The variability of Doppler parameters with different CRT modalities emphasizes the necessity of individualized approach in optimization procedure.

  4. Bloqueio atrioventricular no pós-operatório de cirurgia cardíaca valvar: incidência, fatores de risco e evolução hospitalar Atrioventricular block in the postoperative period of heart valve surgery: incidence, risk factors and hospital evolution

    Directory of Open Access Journals (Sweden)

    Andres Di Leoni Ferrari

    2011-09-01

    Full Text Available INTRODUÇÃO: Distúrbios do sistema de condução cardíaco são complicações potenciais e conhecidas dos procedimentos de cirurgia cardíaca valvar. OBJETIVOS: Investigar a associação entre fatores peri-operatórios com bloqueio atrioventricular (BAV e a necessidade de estimulação cardíaca artificial temporária (ECAT e, se necessário, implante de marcapasso definitivo no pós-operatório de cirurgia cardíaca (POCC valvar. MÉTODOS: Coorte histórica de pacientes submetidos a cirurgia cardíaca valvar, sendo realizada análise de banco de dados por regressão logística. RESULTADOS: No período de janeiro de 1996 a dezembro de 2008, foram realizadas 1102 cirurgias cardíacas valvares: 718 (65,2% na valva aórtica e 407 (36,9% na valva mitral; destas, 190 (17,2% cirurgias de revascularização miocárdica associadas à cirurgia valvar e 23 (2,1% cirurgias valvares combinadas (aórtica+mitral. Cento e oitenta e sete (17% pacientes apresentaram quadro clínico e eletrocardiográfico de BAV durante o POCC valvar, necessitando de ECAT. Quatorze (7,5% pacientes evoluíram para implante de marcapasso definitivo (1,27% do total da amostra. A análise multivariada evidenciou associação significativa de BAV com cirurgia de valva mitral (OR=1,76; IC 95% 1,08-2,37; P=0,002, implante de prótese biológica (OR=1,59; IC 95% 1,02-3,91; P= 0,039, idade maior que 60 anos (OR = 1,99; IC 95% 1,35-2,85; PINTRODUCTION: Disturbances of the cardiac conduction system are potential complications after cardiac valve surgery. OBJECTIVES: This study was designed to investigate the association between perioperative factors and atrio-ventricular block, the need for temporary cardiac artificial pacing and, if necessary, permanent pacemaker implantation after cardiac valve surgery. METHODS: Retrospective analysis of the Cardiac Surgery Database - Hospital São Lucas/PUCRS. The data are collected prospectively and analyzed retrospectively. RESULTS: Between January

  5. Radiotherapy studies and extra-nodal non-Hodgkin lymphomas, progress and challenges

    DEFF Research Database (Denmark)

    Specht, L

    2012-01-01

    Extra-nodal lymphomas may arise in any organ, and different histological subtypes occur in distinct patterns. Prognosis and treatment depend not only on the histological subtype and disease extent, but also on the particular involved extra-nodal organ. The clinical course and response to treatment...... for the more common extra-nodal organs, e.g. stomach, Waldeyer's ring, skin and brain, are fairly well known and show significant variation. A few randomised trials have been carried out testing the role of radiotherapy in these lymphomas. However, for most extra-nodal lymphomas, randomised trials have...... not been carried out, and treatment decisions are made on small patient series and extrapolations from nodal lymphomas. Hopefully, wide international collaboration will make controlled clinical trials possible in the less common extra-nodal lymphomas. Modern highly conformal radiotherapy allows better...

  6. Solution and study of nodal neutron transport equation applying the LTSN-DiagExp method

    International Nuclear Information System (INIS)

    Hauser, Eliete Biasotto; Pazos, Ruben Panta; Vilhena, Marco Tullio de; Barros, Ricardo Carvalho de

    2003-01-01

    In this paper we report advances about the three-dimensional nodal discrete-ordinates approximations of neutron transport equation for Cartesian geometry. We use the combined collocation method of the angular variables and nodal approach for the spatial variables. By nodal approach we mean the iterated transverse integration of the S N equations. This procedure leads to the set of one-dimensional averages angular fluxes in each spatial variable. The resulting system of equations is solved with the LTS N method, first applying the Laplace transform to the set of the nodal S N equations and then obtained the solution by symbolic computation. We include the LTS N method by diagonalization to solve the nodal neutron transport equation and then we outline the convergence of these nodal-LTS N approximations with the help of a norm associated to the quadrature formula used to approximate the integral term of the neutron transport equation. (author)

  7. Five-point form of the nodal diffusion method and comparison with finite-difference

    International Nuclear Information System (INIS)

    Azmy, Y.Y.

    1988-01-01

    Nodal Methods have been derived, implemented and numerically tested for several problems in physics and engineering. In the field of nuclear engineering, many nodal formalisms have been used for the neutron diffusion equation, all yielding results which were far more computationally efficient than conventional Finite Difference (FD) and Finite Element (FE) methods. However, not much effort has been devoted to theoretically comparing nodal and FD methods in order to explain the very high accuracy of the former. In this summary we outline the derivation of a simple five-point form for the lowest order nodal method and compare it to the traditional five-point, edge-centered FD scheme. The effect of the observed differences on the accuracy of the respective methods is established by considering a simple test problem. It must be emphasized that the nodal five-point scheme derived here is mathematically equivalent to previously derived lowest order nodal methods. 7 refs., 1 tab

  8. A Nodal-independent and tissue-intrinsic mechanism controls heart-looping chirality

    Science.gov (United States)

    Noël, Emily S.; Verhoeven, Manon; Lagendijk, Anne Karine; Tessadori, Federico; Smith, Kelly; Choorapoikayil, Suma; den Hertog, Jeroen; Bakkers, Jeroen

    2013-11-01

    Breaking left-right symmetry in bilateria is a major event during embryo development that is required for asymmetric organ position, directional organ looping and lateralized organ function in the adult. Asymmetric expression of Nodal-related genes is hypothesized to be the driving force behind regulation of organ laterality. Here we identify a Nodal-independent mechanism that drives asymmetric heart looping in zebrafish embryos. In a unique mutant defective for the Nodal-related southpaw gene, preferential dextral looping in the heart is maintained, whereas gut and brain asymmetries are randomized. As genetic and pharmacological inhibition of Nodal signalling does not abolish heart asymmetry, a yet undiscovered mechanism controls heart chirality. This mechanism is tissue intrinsic, as explanted hearts maintain ex vivo retain chiral looping behaviour and require actin polymerization and myosin II activity. We find that Nodal signalling regulates actin gene expression, supporting a model in which Nodal signalling amplifies this tissue-intrinsic mechanism of heart looping.

  9. Elsevier Trophoblast Research Award lecture: The multifaceted role of Nodal signaling during mammalian reproduction.

    Science.gov (United States)

    Park, C B; Dufort, D

    2011-03-01

    Nodal, a secreted signaling protein in the transforming growth factor-beta (TGF-β) superfamily, has established roles in vertebrate development. However, components of the Nodal signaling pathway are also expressed at the maternal-fetal interface and have been implicated in many processes of mammalian reproduction. Emerging evidence indicates that Nodal and its extracellular inhibitor Lefty are expressed in the uterus and complex interactions between the two proteins mediate menstruation, decidualization and embryo implantation. Furthermore, several studies have shown that Nodal from both fetal and maternal sources may regulate trophoblast cell fate and facilitate placentation as both embryonic and uterine-specific Nodal knockout mouse strains exhibit disrupted placenta morphology. Here we review the established and prospective roles of Nodal signaling in facilitating successful pregnancy, including recent evidence supporting a potential link to parturition and preterm birth. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Maternal steroid therapy for fetuses with second-degree immune-mediated congenital atrioventricular block: a systematic review and meta-analysis.

    Science.gov (United States)

    Ciardulli, Andrea; D'Antonio, Francesco; Magro-Malosso, Elena R; Manzoli, Lamberto; Anisman, Paul; Saccone, Gabriele; Berghella, Vincenzo

    2018-03-07

    To explore the effect of maternal fluorinated steroid therapy on fetuses affected by second-degree immune-mediated congenital atrioventricular block. Studies reporting the outcome of fetuses with second-degree immune-mediated congenital atrioventricular block diagnosed on prenatal ultrasound and treated with fluorinated steroids compared with those not treated were included. The primary outcome was the overall progression of congenital atrioventricular block to either continuous or intermittent third-degree congenital atrioventricular block at birth. Meta-analyses of proportions using random effect model and meta-analyses using individual data random-effect logistic regression were used. Five studies (71 fetuses) were included. The progression rate to congenital atrioventricular block at birth in fetuses treated with steroids was 52% (95% confidence interval 23-79) and in fetuses not receiving steroid therapy 73% (95% confidence interval 39-94). The overall rate of regression to either first-degree, intermittent first-/second-degree or sinus rhythm in fetuses treated with steroids was 25% (95% confidence interval 12-41) compared with 23% (95% confidence interval 8-44) in those not treated. Stable (constant) second-degree congenital atrioventricular block at birth was present in 11% (95% confidence interval 2-27) of cases in the treated group and in none of the newborns in the untreated group, whereas complete regression to sinus rhythm occurred in 21% (95% confidence interval 6-42) of fetuses receiving steroids vs. 9% (95% confidence interval 0-41) of those untreated. There is still limited evidence as to the benefit of administered fluorinated steroids in terms of affecting outcome of fetuses with second-degree immune-mediated congenital atrioventricular block. © 2018 Nordic Federation of Societies of Obstetrics and Gynecology.

  11. An improved in vivo method for atrioventricular node ablation via thoracotomy

    Directory of Open Access Journals (Sweden)

    R.H. MacIver

    2010-02-01

    Full Text Available The atrioventricular (AV node is permanently damaged in approximately 3% of congenital heart surgery operations, requiring implantation of a permanent pacemaker. Improvements in pacemaker design and in alternative treatment modalities require an effective in vivo model of complete heart block (CHB before testing can be performed in humans. Such a model should enable accurate, reliable, and detectable induction of the surgical pathology. Through our laboratory’s efforts in developing a tissue engineering therapy for CHB, we describe here an improved in vivo model for inducing chronic AV block. The method employs a right thoracotomy in the adult rabbit, from which the right atrial appendage may be retracted to expose an access channel for the AV node. A novel injection device was designed, which both physically restricts needle depth and provides electrical information via electrocardiogram interface. This combination of features provides real-time guidance to the researcher for confirming contact with the AV node, and documents its ablation upon formalin injection. While all animals tested could be induced to acute AV block, those with ECG guidance were more likely to maintain chronic heart block >12 h. Our model enables the researcher to reproduce both CHB and the associated peripheral fibrosis that would be present in an open congenital heart surgery, and which would inevitably impact the design and utility of a tissue engineered AV node replacement.

  12. Evaluation of atrial, ventricular and atrioventricular septal defects by cine magnetic resonance imaging

    International Nuclear Information System (INIS)

    Akagi, Teiji; Kato, Hirohisa; Kiyomatsu, Yumi; Saiki, Kuninobu; Suzuki, Kazushige; Eto, Takaharu

    1992-01-01

    Cine magnetic resonance imaging (MRI) was performed on 20 patients (mean age: 5.3±4.4 years) with atrial, ventricular, or atrioventricular septal defects for evaluation of cardiac structure and blood flow. Prior to cine MRI, electrocardiographycally gated MRI using multislice scquisition was performed on all patients to localize optimal slice location. Cine-MRI was obtained with a 30 deg flip angle, 15 msec echo time, and 30 msec pulse repetition time, on a 256 x 256 or 128 x 128 acquisition matrix. Abnormalities of cardiac structure were well defined in all patients by gated cardiac imaging. In 18 of the 20 patients, cine-MRI was able to detect shunt flow, visualized as a low intensity signal in comparison with the surrounding blood flow. Cine-MRI can provide not only accurate anatomy of cardiac structures but functional assessment of the cardiac chamber, wall topology and flow relations. Cine-MRI will become an important noninvasive technique for assessment of anatomy and physiology in congenital heart disease. (author)

  13. HAND2 Target Gene Regulatory Networks Control Atrioventricular Canal and Cardiac Valve Development.

    Science.gov (United States)

    Laurent, Frédéric; Girdziusaite, Ausra; Gamart, Julie; Barozzi, Iros; Osterwalder, Marco; Akiyama, Jennifer A; Lincoln, Joy; Lopez-Rios, Javier; Visel, Axel; Zuniga, Aimée; Zeller, Rolf

    2017-05-23

    The HAND2 transcriptional regulator controls cardiac development, and we uncover additional essential functions in the endothelial to mesenchymal transition (EMT) underlying cardiac cushion development in the atrioventricular canal (AVC). In Hand2-deficient mouse embryos, the EMT underlying AVC cardiac cushion formation is disrupted, and we combined ChIP-seq of embryonic hearts with transcriptome analysis of wild-type and mutants AVCs to identify the functionally relevant HAND2 target genes. The HAND2 target gene regulatory network (GRN) includes most genes with known functions in EMT processes and AVC cardiac cushion formation. One of these is Snai1, an EMT master regulator whose expression is lost from Hand2-deficient AVCs. Re-expression of Snai1 in mutant AVC explants partially restores this EMT and mesenchymal cell migration. Furthermore, the HAND2-interacting enhancers in the Snai1 genomic landscape are active in embryonic hearts and other Snai1-expressing tissues. These results show that HAND2 directly regulates the molecular cascades initiating AVC cardiac valve development. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  14. Atrioventricular and ventricular-to-ventricular programming in patients with cardiac resynchronization therapy: results from ALTITUDE.

    Science.gov (United States)

    Steinberg, Benjamin A; Wehrenberg, Scott; Jackson, Kevin P; Hayes, David L; Varma, Niraj; Powell, Brian D; Day, John D; Frazier-Mills, Camille G; Stein, Kenneth M; Jones, Paul W; Piccini, Jonathan P

    2015-12-01

    Cardiac resynchronization therapy (CRT) improves outcomes in patients with heart failure, yet response rates are variable. We sought to determine whether physician-specified CRT programming was associated with improved outcomes. Using data from the ALTITUDE remote follow-up cohort, we examined sensed atrioventricular (AV) and ventricular-to-ventricular (VV) programming and their associated outcomes in patients with de novo CRT from 2009-2010. Outcomes included arrhythmia burden, left ventricular (LV) pacing, and all-cause mortality at 4 years. We identified 5709 patients with de novo CRT devices; at the time of implant, 34% (n = 1959) had entirely nominal settings programmed, 40% (n = 2294) had only AV timing adjusted, 11% (n = 604) had only VV timing adjusted, and 15% (n = 852) had both AV and VV adjusted from nominal programming. Suboptimal LV pacing (5% was lowest in the AV-only adjusted group (17.9%) and highest in the nominal (27.7%) and VV-only adjusted (28.3%) groups. Adjusted all-cause mortality was significantly higher among patients with non-nominal AV delay >120 vs. 180 vs. ≤180 ms, p = 0.4). Nominal settings for de novo CRT implants are frequently altered, most commonly the AV delay. There is wide variability in reprogramming. Patients with nominal or AV-only adjustments appear to have favorable pacing and arrhythmia outcomes. Sensed AV delays less than 120 ms are associated with improved survival.

  15. Congenital complete atrioventricular block. Report of one case and literature review

    International Nuclear Information System (INIS)

    Diaz D, Alejandro; Serrano G, Ana; Guzman B, Monica; Ruz M, Miguel

    2008-01-01

    Complete congenital atrioventricular block is a rare entity that has a high morbidity and mortality. Its real incidence remains unknown and a high suspicion index is needed for its diagnosis and consequently for its early intervention. It is observed in children of mothers having connective tissue autoimmune diseases, in particular systemic lupus erythematosus, when the condition is congenital. If it is post-natal, congenital cardiopathies are responsible in most cases. It may al so appear in. structurally normal hearts. The characteristic clinical finding is persistent bradycardia manifested since intrauterine life and affecting the circulatory fetal stability, going as far as to produce hydrops fetalis, a serious and lethal condition. After birth, it appears with bradycardia as well, that may or not unbalance the patient hemodynamics. Diagnosis is made upon clinical suspicion with fetal echocardiography and when post-natal, through electrocardiogram and maternal antibody type antiRo and antiLa. Pacemaker implantation is the definitive treatment that contributes to improve patient survival and prognosis. We present the case of a premature female patient with 31 weeks of gestation due to non-immune hydrops in who complete atrioventricuiar block secondary to maternal lupus erythematosus confirmed by frankly positive anti-nuclear antibodies and positive antiRo and antiLa antibodies was diagnosed, and that received inotropic support after pace maker implantation. She improved completely from her heart failure and was sent to other institution for conventional management of premature

  16. Nodal wear model: corrosion in carbon blast furnace hearths

    International Nuclear Information System (INIS)

    Verdeja, L. F.; Gonzalez, R.; Alfonso, A.; Barbes, M. F.

    2003-01-01

    Criteria developed for the Nodal Wear Model (NWM) were applied to estimate the shape of the corrosion profiles that a blast furnace hearth may acquire during its campaign. Taking into account design of the hearth, the boundary conditions, the characteristics of the refractory materials used and the operation conditions of the blast furnace, simulation of wear profiles with central well, mushroom and elephant foot shape were accomplished. The foundations of the NWM are constructed considering that the corrosion of the refractory is a function of the temperature present at each point (node) of the liquid metal-refractory interface and the corresponding physical and chemical characteristics of the corrosive fluid. (Author) 31 refs

  17. Approximate Schur complement preconditioning of the lowest order nodal discretizations

    Energy Technology Data Exchange (ETDEWEB)

    Moulton, J.D.; Ascher, U.M. [Univ. of British Columbia, Vancouver, British Columbia (Canada); Morel, J.E. [Los Alamos National Lab., NM (United States)

    1996-12-31

    Particular classes of nodal methods and mixed hybrid finite element methods lead to equivalent, robust and accurate discretizations of 2nd order elliptic PDEs. However, widespread popularity of these discretizations has been hindered by the awkward linear systems which result. The present work exploits this awkwardness, which provides a natural partitioning of the linear system, by defining two optimal preconditioners based on approximate Schur complements. Central to the optimal performance of these preconditioners is their sparsity structure which is compatible with Dendy`s black box multigrid code.

  18. Evaluation of the use of nodal methods for MTR neutronic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Reitsma, F.; Mueller, E.Z.

    1997-08-01

    Although modern nodal methods are used extensively in the nuclear power industry, their use for research reactor analysis has been very limited. The suitability of nodal methods for material testing reactor analysis is investigated with the emphasis on the modelling of the core region (fuel assemblies). The nodal approach`s performance is compared with that of the traditional finite-difference fine mesh approach. The advantages of using nodal methods coupled with integrated cross section generation systems are highlighted, especially with respect to data preparation, simplicity of use and the possibility of performing a great variety of reactor calculations subject to strict time limitations such as are required for the RERTR program.

  19. Time-dependent patterning of the mesoderm and endoderm by Nodal signals in zebrafish

    Directory of Open Access Journals (Sweden)

    Dougan Scott T

    2007-03-01

    Full Text Available Abstract Background The vertebrate body plan is generated during gastrulation with the formation of the three germ layers. Members of the Nodal-related subclass of the TGF-β superfamily induce and pattern the mesoderm and endoderm in all vertebrates. In zebrafish, two nodal-related genes, called squint and cyclops, are required in a dosage-dependent manner for the formation of all derivatives of the mesoderm and endoderm. These genes are expressed dynamically during the blastula stages and may have different roles at different times. This question has been difficult to address because conditions that alter the timing of nodal-related gene expression also change Nodal levels. We utilized a pharmacological approach to conditionally inactivate the ALK 4, 5 and 7 receptors during the blastula stages without disturbing earlier signaling activity. This permitted us to directly examine when Nodal signals specify cell types independently of dosage effects. Results We show that two drugs, SB-431542 and SB-505124, completely block the response to Nodal signals when added to embryos after the mid-blastula transition. By blocking Nodal receptor activity at later stages, we demonstrate that Nodal signaling is required from the mid-to-late blastula period to specify sequentially, the somites, notochord, blood, Kupffer's vesicle, hatching gland, heart, and endoderm. Blocking Nodal signaling at late times prevents specification of cell types derived from the embryo margin, but not those from more animal regions. This suggests a linkage between cell fate and length of exposure to Nodal signals. Confirming this, cells exposed to a uniform Nodal dose adopt progressively more marginal fates with increasing lengths of exposure. Finally, cell fate specification is delayed in squint mutants and accelerated when Nodal levels are elevated. Conclusion We conclude that (1 Nodal signals are most active during the mid-to-late blastula stages, when nodal-related gene

  20. Bloqueo aurículo-ventricular de primer grado en tirotoxicosis aguda First degree atrio-ventricular block in acute thyrotoxicosis

    Directory of Open Access Journals (Sweden)

    Antonio R. Vilches

    2004-02-01

    Full Text Available El cuadro clínico de la tirotoxicosis incluye síntomas cardiovasculares variados. La taquicardia sinusal es el trastorno electrocardiográfico más frecuente y los trastornos de conducción son extremadamente raros como modo de presentación. Comunicamos un caso de bloqueo aurículo-ventricular de primer grado en una paciente con hipertiroidismo recién diagnosticado y que comenzó días antes de la consulta con un cuadro general inespecífico. Su evaluación ulterior demostró que se trataba de una tirotoxicosis aguda autoinmune, y su tratamiento con metimazol corrigió el trastorno totalmente. Se discuten los mecanismos fisiopatológicos involucrados y las implicancias clínicas desde el punto de vista del internista.Thyrotoxicosis may present with a variety of cardiovascular symptoms. Sinus tachycardia is the most frequently encountered electrocardiographic abnormality and conduction disturbances are extremely uncommon. We present a case of first degree atrio-ventricular block in a patient with newly diagnosed hyperthyroidism and discuss the underlying pathophysiological mechanisms and the clinical implications from the internist’s standpoint.

  1. Exact boundary controllability of nodal profile for quasilinear hyperbolic systems

    CERN Document Server

    Li, Tatsien; Gu, Qilong

    2016-01-01

    This book provides a comprehensive overview of the exact boundary controllability of nodal profile, a new kind of exact boundary controllability stimulated by some practical applications. This kind of controllability is useful in practice as it does not require any precisely given final state to be attained at a suitable time t=T by means of boundary controls, instead it requires the state to exactly fit any given demand (profile) on one or more nodes after a suitable time t=T by means of boundary controls. In this book we present a general discussion of this kind of controllability for general 1-D first order quasilinear hyperbolic systems and for general 1-D quasilinear wave equations on an interval as well as on a tree-like network using a modular-structure construtive method, suggested in LI Tatsien's monograph "Controllability and Observability for Quasilinear Hyperbolic Systems"(2010), and we establish a complete theory on the local exact boundary controllability of nodal profile for 1-D quasilinear hyp...

  2. Nodal Diffusion Burnable Poison Treatment for Prismatic Reactor Cores

    International Nuclear Information System (INIS)

    Ougouag, A.M.; Ferrer, R.M.

    2010-01-01

    The prismatic block version of the High Temperature Reactor (HTR) considered as a candidate Very High Temperature Reactor (VHTR)design may use burnable poison pins in locations at some corners of the fuel blocks (i.e., assembly equivalent structures). The presence of any highly absorbing materials, such as these burnable poisons, within fuel blocks for hexagonal geometry, graphite-moderated High Temperature Reactors (HTRs) causes a local inter-block flux depression that most nodal diffusion-based method have failed to properly model or otherwise represent. The location of these burnable poisons near vertices results in an asymmetry in the morphology of the assemblies (or blocks). Hence the resulting inadequacy of traditional homogenization methods, as these 'spread' the actually local effect of the burnable poisons throughout the assembly. Furthermore, the actual effect of the burnable poison is primarily local with influence in its immediate vicinity, which happens to include a small region within the same assembly as well as similar regions in the adjacent assemblies. Traditional homogenization methods miss this artifact entirely. This paper presents a novel method for treating the local effect of the burnable poison explicitly in the context of a modern nodal method.

  3. Hereditary bone dysplasia with pathological fractures and nodal osteoarthropathy

    International Nuclear Information System (INIS)

    Arendse, Regan; Brink, Paul; Beighton, Peter

    2009-01-01

    A father and daughter both had multiple pathological fractures and nodal osteoarthropathy. The father, aged 50 years, had at least 20 healed fractures of the axial and appendicular skeleton, sustained by minor trauma over his 50-year lifespan, many of which had been surgically fixed prior to his first presentation to us. Fractures of the clavicles, thoracic cage and long bones of the arms and legs, had healed with malalignment and deformity. Healed fractures were complicated by ankylosis of the cervical vertebrae and both elbows. He also had osteoarthritis of the hands, with exuberant osteophytosis, and profound perceptive deafness. His general health was good, his intellect and facies were normal, and his sclerae were white. The daughter, aged 27 years, had sustained at least seven fractures of the axial and appendicular skeleton following trivial injuries, in distribution similar to those of the father. She had also experienced painful swelling of the fingers, which preceded progressive development of nodal osteoarthropathy. Her hearing was normal. In both individuals, biochemical and immunological investigations yielded normal results. It was not possible for molecular studies to be undertaken. Pedigree data were consistent with autosomal dominant transmission, and this disorder appeared to be a previously undocumented heritable skeletal dysplasia. (orig.)

  4. Hereditary bone dysplasia with pathological fractures and nodal osteoarthropathy

    Energy Technology Data Exchange (ETDEWEB)

    Arendse, Regan [University of Stellenbosch, Department of Medicine, Tygerberg Hospital, Stellenbosch (South Africa); University of Cape Town, Division of Rheumatology, Groote Schuur Hospital, Cape Town (South Africa); Brink, Paul [University of Stellenbosch, Department of Medicine, Tygerberg Hospital, Stellenbosch (South Africa); Beighton, Peter [University of Cape Town, Division of Human Genetics, Faculty of Health Sciences, Cape Town (South Africa)

    2009-12-15

    A father and daughter both had multiple pathological fractures and nodal osteoarthropathy. The father, aged 50 years, had at least 20 healed fractures of the axial and appendicular skeleton, sustained by minor trauma over his 50-year lifespan, many of which had been surgically fixed prior to his first presentation to us. Fractures of the clavicles, thoracic cage and long bones of the arms and legs, had healed with malalignment and deformity. Healed fractures were complicated by ankylosis of the cervical vertebrae and both elbows. He also had osteoarthritis of the hands, with exuberant osteophytosis, and profound perceptive deafness. His general health was good, his intellect and facies were normal, and his sclerae were white. The daughter, aged 27 years, had sustained at least seven fractures of the axial and appendicular skeleton following trivial injuries, in distribution similar to those of the father. She had also experienced painful swelling of the fingers, which preceded progressive development of nodal osteoarthropathy. Her hearing was normal. In both individuals, biochemical and immunological investigations yielded normal results. It was not possible for molecular studies to be undertaken. Pedigree data were consistent with autosomal dominant transmission, and this disorder appeared to be a previously undocumented heritable skeletal dysplasia. (orig.)

  5. Dirac Magnon Nodal Loops in Quasi-2D Quantum Magnets.

    Science.gov (United States)

    Owerre, S A

    2017-07-31

    In this report, we propose a new concept of one-dimensional (1D) closed lines of Dirac magnon nodes in two-dimensional (2D) momentum space of quasi-2D quantum magnetic systems. They are termed "2D Dirac magnon nodal-line loops". We utilize the bilayer honeycomb ferromagnets with intralayer coupling J and interlayer coupling J L , which is realizable in the honeycomb chromium compounds CrX 3 (X ≡ Br, Cl, and I). However, our results can also exist in other layered quasi-2D quantum magnetic systems. Here, we show that the magnon bands of the bilayer honeycomb ferromagnets overlap for J L  ≠ 0 and form 1D closed lines of Dirac magnon nodes in 2D momentum space. The 2D Dirac magnon nodal-line loops are topologically protected by inversion and time-reversal symmetry. Furthermore, we show that they are robust against weak Dzyaloshinskii-Moriya interaction Δ DM  magnon edge modes.

  6. Retrospective analysis of outcome differences in preoperative concurrent chemoradiation with or without elective nodal irradiation for esophageal squamous cell carcinoma.

    Science.gov (United States)

    Hsu, Feng-Ming; Lee, Jang-Ming; Huang, Pei-Ming; Lin, Chia-Chi; Hsu, Chih-Hung; Tsai, Yu-Chieh; Lee, Yung-Chie; Chia-Hsien Cheng, Jason

    2011-11-15

    To evaluate the efficacy and patterns of failure of elective nodal irradiation (ENI) in patients with esophageal squamous cell carcinoma (SCC) undergoing preoperative concurrent chemoradiation (CCRT) followed by radical surgery. We retrospectively studied 118 patients with AJCC Stage II to III esophageal SCC undergoing preoperative CCRT (median, 36 Gy), followed by radical esophagectomy. Of them, 73 patients (62%) had ENI and 45 patients (38%) had no ENI. Patients with ENI received radiotherapy to either supraclavicular (n = 54) or celiac (n = 19) lymphatics. Fifty-six patients (57%) received chemotherapy with paclitaxel plus cisplatin. The 3-year progression-free survival, overall survival, and patterns of failure were analyzed. Distant nodal recurrence was classified into M1a and M1b regions. A separate analysis using matched cases was conducted. The median follow-up was 38 months. There were no differences in pathological complete response rate (p = 0.12), perioperative mortality rate (p = 0.48), or delayed Grade 3 or greater cardiopulmonary toxicities (p = 0.44), between the groups. More patients in the non-ENI group had M1a failure than in the ENI group, with 3-year rates of 11% and 3%, respectively (p = 0.05). However, the 3-year isolated distant nodal (M1a + M1b) failure rates were not different (ENI, 10%; non-ENI, 14%; p = 0.29). In multivariate analysis, pathological nodal status was the only independent prognostic factor associated with overall survival (hazard ratio = 1.78, p = 0.045). The 3-year overall survival and progression-free survival were 45% and 45%, respectively, in the ENI group, and 52% and 43%, respectively, in the non-ENI group (p = 0.31 and 0.89, respectively). Matched cases analysis did not show a statistical difference in outcomes between the groups. ENI reduced the M1a failure rate but was not associated with improved outcomes in patients undergoing preoperative CCRT for esophageal SCC. Pathological nodal metastasis predicted poor

  7. Retrospective Analysis of Outcome Differences in Preoperative Concurrent Chemoradiation With or Without Elective Nodal Irradiation for Esophageal Squamous Cell Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Feng-Ming [Department of Oncology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan (China); Cancer Research Center, National Taiwan University College of Medicine, Taipei, Taiwan (China); Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan (China); Lee, Jang-Ming; Huang, Pei-Ming [Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan (China); Lin, Chia-Chi; Hsu, Chih-Hung; Tsai, Yu-Chieh [Department of Oncology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan (China); Cancer Research Center, National Taiwan University College of Medicine, Taipei, Taiwan (China); Lee, Yung-Chie [Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan (China); Chia-Hsien Cheng, Jason, E-mail: jasoncheng@ntu.edu.tw [Department of Oncology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan (China); Cancer Research Center, National Taiwan University College of Medicine, Taipei, Taiwan (China); Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan (China); Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan (China)

    2011-11-15

    Purpose: To evaluate the efficacy and patterns of failure of elective nodal irradiation (ENI) in patients with esophageal squamous cell carcinoma (SCC) undergoing preoperative concurrent chemoradiation (CCRT) followed by radical surgery. Methods and Materials: We retrospectively studied 118 patients with AJCC Stage II to III esophageal SCC undergoing preoperative CCRT (median, 36 Gy), followed by radical esophagectomy. Of them, 73 patients (62%) had ENI and 45 patients (38%) had no ENI. Patients with ENI received radiotherapy to either supraclavicular (n = 54) or celiac (n = 19) lymphatics. Fifty-six patients (57%) received chemotherapy with paclitaxel plus cisplatin. The 3-year progression-free survival, overall survival, and patterns of failure were analyzed. Distant nodal recurrence was classified into M1a and M1b regions. A separate analysis using matched cases was conducted. Results: The median follow-up was 38 months. There were no differences in pathological complete response rate (p = 0.12), perioperative mortality rate (p = 0.48), or delayed Grade 3 or greater cardiopulmonary toxicities (p = 0.44), between the groups. More patients in the non-ENI group had M1a failure than in the ENI group, with 3-year rates of 11% and 3%, respectively (p = 0.05). However, the 3-year isolated distant nodal (M1a + M1b) failure rates were not different (ENI, 10%; non-ENI, 14%; p = 0.29). In multivariate analysis, pathological nodal status was the only independent prognostic factor associated with overall survival (hazard ratio = 1.78, p = 0.045). The 3-year overall survival and progression-free survival were 45% and 45%, respectively, in the ENI group, and 52% and 43%, respectively, in the non-ENI group (p = 0.31 and 0.89, respectively). Matched cases analysis did not show a statistical difference in outcomes between the groups. Conclusions: ENI reduced the M1a failure rate but was not associated with improved outcomes in patients undergoing preoperative CCRT for esophageal

  8. Qualification of a full plant nodalization for the prediction of the core exit temperature through a scaling methodology

    Energy Technology Data Exchange (ETDEWEB)

    Freixa, J., E-mail: jordi.freixa-terradas@upc.edu; Martínez-Quiroga, V., E-mail: victor.martinez.quiroga@upc.edu; Reventós, F., E-mail: francesc.reventos@upc.edu

    2016-11-15

    Highlights: • Core exit temperature is used in PWRs as an indication of core heat up. • Qualification of full scale nuclear reactors by means of a scaling methodology. • Scaling of RELAP5 calculations to full scale power plants. - Abstract: System codes and their necessary power plant nodalizations are an essential step in thermal hydraulic safety analysis. In order to assess the safety of a particular power plant, in addition to the validation and verification of the code, the nodalization of the system needs to be qualified. Since most existing experimental data come from scaled-down facilities, any qualification process must therefore address scale considerations. The Group of Thermal Hydraulic Studies at Technical University of Catalonia has developed a scaling-up methodology (SCUP) for the qualification of full-scale nodalizations through a systematic procedure based on the extrapolation of post-test simulations of Integral Test Facility experiments. In the present work, the SCUP methodology will be employed to qualify the nodalization of the AscóNPP, a Pressurized Water Reactor (PWR), for the reproduction of an important safety phenomenon which is the effectiveness of the Core Exit Temperature (CET) as an Accident Management (AM) indicator. Given the difficulties in placing measurements in the core region, CET measurements are used as a criterion for the initiation of safety operational procedures during accidental conditions in PWR. However, the CET response has some limitation in detecting inadequate core cooling simply because the measurement is not taken in the position where the cladding exposure occurs. In order to apply the SCUP methodology, the OECD/NEA ROSA-2 Test 3, an SBLOCA in the hot leg, has been selected as a starting point. This experiment was conducted at the Large Scale Test Facility (LSTF), a facility operated by the Japanese Atomic Energy Agency (JAEA) and was focused on the assessment of the effectiveness of AM actions triggered by

  9. Arrhythmias and conduction abnormalities in children after repair of tetralogy of Fallot

    Directory of Open Access Journals (Sweden)

    Kuzevska-Maneva Konstandina

    2005-01-01

    Full Text Available Aim. To find out types and frequency of cardiac arrhythmias and conduction abnormalities in the group of children who underwent surgery for tetralogy of Fallot (TOF. Methods. Fortysix pedicatric patients who underwent a complete repair of TOF at the age of 1 to 13 (mean 2.89 ± 2.36 were studied. Thirty-eight (82.60% had total correction and 8 (17.40% had palliative operation first, and total correction afterwards. Twenty-four-hour Holter ECG monitoring was performed in all 46 pediatric patients aged from 1 to 16 yrs (mean 6.48 ± 4.04 after surgery as follows: in 1 patient (2.17% after a year, in 20 patients (43.47% after 2 to 5 years and in 25 patients (54.34% after 5 years. Mean age of patients on Holter monitoring was 9.25 ± 4.39 (range 4−19. Twenty of them (43.47% were girls and 28 (56.53% were boys. All the patients were evaluated by standard methods (clinical signs, clinical findings, ECG before surgery, ECG before Holter monitoring and 2D Doppler echocardiography. Results. Types of heart rhythm found out by Holter monitoring were: sinus nodus dysfunction in 1 child (2.17%, significant premature atrial contraction (PAC in 8 (17.39%, supraventricular paroxysmal tachycardia in 3 (6.53%, transient nodal rhythm in 2 (4.34%, premature ventricular contraction (PVC Lown grade I-III in 9 (19.56% and Lown grade IV in 2 (4.34, atrioventricular (AV block grade I in 2, right bundle branch block (RBBB in all 46 (100% and RBBB + left anterior hemiblock (LAH in 4 (8.96%. There was no presence of atrial flutter, ventricular tachycardia or complete AV block. None of them experienced sudden death. Using cross procedure statistical methods, it was found that all the patients with PVC had right ventricular dilatation. There was no relation of other types of arrhythmia found on Holter monitoring to the other parameters from echocardiography, neither to the other standard methods. Children did not need the pace-maker, but 36.95% of the them required

  10. Inhibitory effects of Urtica dioica L. root on electrophysiological properties of isolated rabbit atrioventricular node

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    A. Enayati

    2017-11-01

    Full Text Available Background and objectives: The ideal drug for treatment of a wide range of supraventricular arrhythmia hasn't yet been developed. Previous studies have shown antihypertensive and negative inotropic effects of the Urtica dioica L. (nettle. Therefore, the aim of present study is to determine the rate dependent inhibitory effects of ethanol extract of nettle root and investigate the role of adrenoceptors in the anti-arrhythmic mechanism of nettle on the isolated rabbit atrio-ventricular node. Methods: Urtica dioica roots were collected from Gorgan (Golestan, Iran. Male New Zealand rabbits (n=7 were used in all of the experiments. Experimental stimulation protocols (WBCL; Recovery, Facilitation, Fatigue were applied to assess electrophysiological properties of Node. All protocols were repeated in the presence and absence (control of different concentration (0.25-0.5 w/v % of nettle and 1 μM nadolol. Data were shown as Mean±SE, difference between groups statistically were assessed by SPSS software. Results: Nettle (0.5 w/v significantly decreased basic and functional properties of node as WBCL, ERP, FRP, AVCT and magnitude of fatigue (∆AH significantly increased but ∆FRP significantly decreased. In the presence of nadolol (1μM as a nonselective β-blocker, nettle (0.3 mg/L could not repeat its effects on electrophysiological properties of AV-node. Conclusion: The results showed the modifying properties of Urtica dioica root extract. It may be considered as a candidate for the treatment of supraventicular arrhythmias.

  11. Functional Capacity of Patients with Pacemaker Due to Isolated Congenital Atrioventricular Block

    Science.gov (United States)

    de Oliveira Júnior, Roberto Márcio; da Silva, Kátia Regina; Kawauchi, Tatiana Satie; Alves, Lucas Bassolli de Oliveira; Crevelari, Elizabeth Sartori; Martinelli, Martino; Costa, Roberto

    2015-01-01

    Background Isolated congenital atrioventricular block (CAVB) is a rare condition with multiple clinical outcomes. Ventricular remodeling can occur in approximately 10% of the patients after pacemaker (PM) implantation. Objectives To assess the functional capacity of children and young adults with isolated CAVB and chronic pacing of the right ventricle (RV) and evaluate its correlation with predictors of ventricular remodeling. Methods This cross-sectional study used a cohort of patients with isolated CAVB and RV pacing for over a year. The subjects underwent clinical and echocardiographic evaluation. Functional capacity was assessed using the six-minute walk test. Chi-square test, Fisher's exact test, and Pearson correlation coefficient were used, considering a significance level of 5%. Results A total of 61 individuals were evaluated between March 2010 and December 2013, of which 67.2% were women, aged between 7 and 41 years, who were using PMs for 13.5 ± 6.3 years. The percentage of ventricular pacing was 97.9 ± 4.1%, and the duration of the paced QRS complex was 153.7 ± 19.1 ms. Majority of the subjects (95.1%) were asymptomatic and did not use any medication. The mean distance walked was 546.9 ± 76.2 meters and was strongly correlated with the predicted distance (r = 0.907, p = 0.001) but not with risk factors for ventricular remodeling. Conclusions The functional capacity of isolated CAVB patients with chronic RV pacing was satisfactory but did not correlate with risk factors for ventricular remodeling. PMID:25387405

  12. Serotonin potentiates transforming growth factor-beta3 induced biomechanical remodeling in avian embryonic atrioventricular valves.

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    Philip R Buskohl

    Full Text Available Embryonic heart valve primordia (cushions maintain unidirectional blood flow during development despite an increasingly demanding mechanical environment. Recent studies demonstrate that atrioventricular (AV cushions stiffen over gestation, but the molecular mechanisms of this process are unknown. Transforming growth factor-beta (TGFβ and serotonin (5-HT signaling modulate tissue biomechanics of postnatal valves, but less is known of their role in the biomechanical remodeling of embryonic valves. In this study, we demonstrate that exogenous TGFβ3 increases AV cushion biomechanical stiffness and residual stress, but paradoxically reduces matrix compaction. We then show that TGFβ3 induces contractile gene expression (RhoA, aSMA and extracellular matrix expression (col1α2 in cushion mesenchyme, while simultaneously stimulating a two-fold increase in proliferation. Local compaction increased due to an elevated contractile phenotype, but global compaction appeared reduced due to proliferation and ECM synthesis. Blockade of TGFβ type I receptors via SB431542 inhibited the TGFβ3 effects. We next showed that exogenous 5-HT does not influence cushion stiffness by itself, but synergistically increases cushion stiffness with TGFβ3 co-treatment. 5-HT increased TGFβ3 gene expression and also potentiated TGFβ3 induced gene expression in a dose-dependent manner. Blockade of the 5HT2b receptor, but not 5-HT2a receptor or serotonin transporter (SERT, resulted in complete cessation of TGFβ3 induced mechanical strengthening. Finally, systemic 5-HT administration in ovo induced cushion remodeling related defects, including thinned/atretic AV valves, ventricular septal defects, and outflow rotation defects. Elevated 5-HT in ovo resulted in elevated remodeling gene expression and increased TGFβ signaling activity, supporting our ex-vivo findings. Collectively, these results highlight TGFβ/5-HT signaling as a potent mechanism for control of biomechanical

  13. Atrioventricular canal defect and associated genetic disorders: new insights into polydactyly syndromes

    Directory of Open Access Journals (Sweden)

    M. Cristina Digilio

    2011-07-01

    Full Text Available Atrioventricular canal defect (AVCD is a common congenital heart defect (CHD, representing 7.4% of all cardiac malformations, considered secondary to an extracellular matrix anomaly. The AVCD is associated with extracardiac defects in about 75% of the cases. In this review we analyzed different syndromic AVCDs, in particular those associated with polydactyly disorders, which show remarkable genotype-phenotype correlations. Chromo - some imbalances more frequently associated with AVCD include Down syndrome, deletion 8p23 and deletion 3p25, while mendelian disorders include Noonan syndrome and related RASopathies, several polydactyly syndromes, CHARGE and 3C (cranio-cerebello-cardiac syndrome. The complete form of AVCD is prevalent in patients with chromosomal imbalances. Additional cardiac defects are found in patients affected by chromosomal imbalances different from Down syndrome. Left-sided obstructive lesions are prevalently found in patients with RASopathies. Patients with deletion 8p23 often display AVCD with tetralogy of Fallot or with pulmonary valve stenosis. Tetralogy of Fallot is the only additional cardiac defect found in patients with Down syndrome and AVCD. On the other hand, the association of AVCD and tetralogy of Fallot is also quite characteristic of CHARGE and 3C syndromes. Heterotaxia defects, including common atrium and anomalous pulmonary venous return, occur in patients with AVCD associated with polydactyly syndromes (Ellis-van Creveld, short rib polydactyly, oral-facial-digital, Bardet-Biedl, and Smith-Lemli-Opitz syndromes. The initial clinical evidence of anatomic similarities between AVCD and heterotaxia in polydactyly syndromes was corroborated and explained by experimental studies in transgenic mice. These investigations have suggested the involvement of the Sonic Hedgehog pathway in syndromes with postaxial polydactyly and heterotaxia, and ciliary dysfunction was detected as pathomechanism for these disorders

  14. Improving left ventricular outflow tract obstruction repair in common atrioventricular canal defects.

    Science.gov (United States)

    Myers, Patrick O; del Nido, Pedro J; Marx, Gerald R; Emani, Sitaram; Mayer, John E; Pigula, Frank A; Baird, Christopher W

    2012-08-01

    Left ventricular outflow tract obstruction (LVOTO) is the second most frequent reason for reoperation after atrioventricular canal (AVC) defect repair. Limited data are available on the mechanisms of LVOTO, their treatment, and outcomes. Between 1998 and 2010, 56 consecutive children with AVC underwent 68 LVOTO procedures. The AVC was partial in 4, transitional in 9, and complete in 43. The LVOTO procedure was required in 21 patients at the primary AVC repair, and the initial LVOTO procedure in 35 patients was a late reoperation after AVC repair. During a mean follow-up of 50±41 months, 5 patients (24%) with LVOTO repair at AVC repair required a reoperation for LVOTO, and 7 patients (20%) whose initial LVOTO repair was a reoperation required a second reoperation for LVOTO repair. Overall freedom from LVOTO reoperation was 98.5% at 1 year, 92.5% at 3 years, 81% at 5 years, 72.2% at 7 years, and 52.5% at 10 and 12 years. The freedom from reoperation was neither significantly different between partial, transitional, and complete AVC (p=0.78) nor between timing of the LVOT procedure (p=0.49). Modified single-patch AVC repair was associated with a higher LVOTO reoperation rate (p=0.04). Neither the mechanisms leading to LVOTO nor the surgical techniques used were independent predictors of reoperation. LVOTO in AVC is a complex and multifactorial disease. Aggressive surgical repair has improved late outcomes; however, risk factors for reoperation and the ideal approach for repair remain to be defined. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  15. Istaroxime, a positive inotropic agent devoid of proarrhythmic properties in sensitive chronic atrioventricular block dogs.

    Science.gov (United States)

    Bossu, Alexandre; Kostense, Amée; Beekman, Henriette D M; Houtman, Marien J C; van der Heyden, Marcel A G; Vos, Marc A

    2018-05-10

    Current inotropic agents in heart failure therapy associate with low benefit and significant adverse effects, including ventricular arrhythmias. Istaroxime, a novel Na + /K + -transporting ATPase inhibitor, also stimulates SERCA2a activity, which would confer improved inotropic and lusitropic properties with less proarrhythmic effects. We investigated hemodynamic, electrophysiological and potential proarrhythmic and antiarrhythmic effects of istaroxime in control and chronic atrioventricular block (CAVB) dogs sensitive to drug-induced Torsades de Pointes arrhythmias (TdP). In isolated normal canine ventricular cardiomyocytes, istaroxime (0.3-10 μM) evoked no afterdepolarizations and significantly shortened action potential duration (APD) at 3 and 10 μM. Istaroxime at 3 μg/kg/min significantly increased left ventricular (LV) contractility (dP/dt + ) and relaxation (dP/dt-) respectively by 81 and 94% in anesthetized control dogs (n = 6) and by 61 and 49% in anesthetized CAVB dogs (n = 7) sensitive to dofetilide-induced TdP. While istaroxime induced no ventricular arrhythmias in control conditions, only single ectopic beats occurred in 2/7 CAVB dogs, which were preceded by increase of short-term variability of repolarization (STV) and T wave alternans in LV unipolar electrograms. Istaroxime pre-treatment (3 μg/kg/min for 60 min) did not alleviate dofetilide-induced increase in repolarization and STV, and mildly reduced incidence of TdP from 6/6 to 4/6 CAVB dogs. In six CAVB dogs with dofetilide-induced TdP, administration of istaroxime (90 μg/kg/5 min) suppressed arrhythmic episodes in two animals. Taken together, inotropic and lusitropic properties of istaroxime in CAVB dogs were devoid of significant proarrhythmic effects in sensitive CAVB dogs, and istaroxime provides a moderate antiarrhythmic efficacy in prevention and suppression of dofetilide-induced TdP. Copyright © 2018. Published by Elsevier Ltd.

  16. Load-dependent extracellular matrix organization in atrioventricular heart valves: differences and similarities.

    Science.gov (United States)

    Alavi, S Hamed; Sinha, Aditi; Steward, Earl; Milliken, Jeffrey C; Kheradvar, Arash

    2015-07-15

    The extracellular matrix of the atrioventricular (AV) valves' leaflets has a key role in the ability of these valves to properly remodel in response to constantly varying physiological loads. While the loading on mitral and tricuspid valves is significantly different, no information is available on how collagen fibers change their orientation in response to these loads. This study delineates the effect of physiological loading on AV valves' leaflets microstructures using Second Harmonic Generation (SHG) microscopy. Fresh natural porcine tricuspid and mitral valves' leaflets (n = 12/valve type) were cut and prepared for the experiments. Histology and immunohistochemistry were performed to compare the microstructural differences between the valves. The specimens were imaged live during the relaxed, loading, and unloading phases using SHG microscopy. The images were analyzed with Fourier decomposition to mathematically seek changes in collagen fiber orientation. Despite the similarities in both AV valves as seen in the histology and immunohistochemistry data, the microstructural arrangement, especially the collagen fiber distribution and orientation in the stress-free condition, were found to be different. Uniaxial loading was dependent on the arrangement of the fibers in their relaxed mode, which led the fibers to reorient in-line with the load throughout the depth of the mitral leaflet but only to reorient in-line with the load in deeper layers of the tricuspid leaflet. Biaxial loading arranged the fibers in between the two principal axes of the stresses independently from their relaxed states. Unlike previous findings, this study concludes that the AV valves' three-dimensional extracellular fiber arrangement is significantly different in their stress-free and uniaxially loaded states; however, fiber rearrangement in response to the biaxial loading remains similar. Copyright © 2015 the American Physiological Society.

  17. Therapeutic effects of selective atrioventricular node vagal stimulation in atrial fibrillation and heart failure.

    Science.gov (United States)

    Zhang, Youhua; Popović, Zoran B; Kusunose, Kenya; Mazgalev, Todor N

    2013-01-01

    Atrial fibrillation (AF) and heart failure (HF) frequently coexist. We have previously demonstrated that selective atrioventricular node (AVN) vagal stimulation (AVN-VS) can be used to control ventricular rate during AF. Due to withdrawal of vagal activity in HF, the therapeutic effects of AVN-VS may be compromised in the combined condition of AF and HF. Accordingly, this study was designed to evaluate the therapeutic effects of AVN-VS to control ventricular rate in AF and HF. A combined model of AF and HF was created by implanting a dual chamber pacemaker in 24 dogs. A newly designed bipolar electrode was inserted into the ganglionic AVN fat pad and connected to a nerve stimulator for delivering AVN-VS. In all dogs, HF was induced by high rate ventricular pacing at 220 bpm for 4 weeks. AF was then induced and maintained by rapid atrial pacing at 600 bpm after discontinuation of ventricular pacing. These HF + AF dogs were randomized into control (n = 9) and AVN-VS (n = 15) groups. In the latter group, vagal stimulation (310 μs, 20 Hz, 3-7 mA) was delivered continuously for 6 months. Compared with the control, AVN-VS had a consistent effect on ventricular rate slowing (by >50 bpm, all P AVN-VS was well tolerated by the treated animals. AVN-VS achieved consistent rate slowing, which was associated with improved ventricular function in a canine AF and HF model. Thus, AVN-VS may be a novel, effective therapeutic option in the combined condition of AF and HF. © 2012 Wiley Periodicals, Inc.

  18. Inhibition of sarcoplasmic reticulum Ca(2+)-ATPase decreases atrioventricular node-paced heart rate in rabbits.

    Science.gov (United States)

    Cheng, Hongwei; Smith, Godfrey L; Orchard, Clive H; Hancox, Jules C; Burton, Francis L

    2012-10-01

    Recent data indicate that Ca(2+) cycling in isolated atrioventricular node (AVN) cells contributes to setting spontaneous rate. The aim of the present study was to extend this observation to the intact AVN in situ, by evaluating the effects of inhibiting sarcoplasmic reticulum Ca(2+) uptake with cyclopiazonic acid (CPA) on intact AVN spontaneous activity and its response to isoprenaline. A model of the AVN-paced heart was produced to investigate intact AVN automaticity, by surgical ablation of the sino-atrial node (SAN) in the rabbit Langendorff-perfused heart. Electrograms were recorded from a site close to the AVN (triangle of Koch), an atrial site above the AVN, the left atrium and right ventricle, enabling AVN pacing of the preparation to be confirmed. Before SAN ablation, the heart rate was 166.8 ± 5.4 beats min(-1). Ablation of the SAN was clearly indicated by a sudden and significant decrease of heart rate to 108.6 ± 9.6 beats min(-1) (P AVN rate to 187.8 ± 12.0 beats min(-1) after 1 min of application (P AVN rate to 81.6 ± 4.8 (n = 9) and 77.4 ± 6.0 beats min(-1) (n = 7), respectively [P AVN rate increase in response to isoprenaline from 78.8 ± 10.0 to 46.8 ± 6.8 and 26.7 ± 5.3%, respectively (P AVN rate and its response to isoprenaline indicate that Ca(2+) cycling is important to the intact AVN spontaneous activity and its acceleration during sympathetic stimulation.

  19. Clinical predictors of challenging atrioventricular node ablation procedure for rate control in patients with atrial fibrillation.

    Science.gov (United States)

    Polin, Baptiste; Behar, Nathalie; Galand, Vincent; Auffret, Vincent; Behaghel, Albin; Pavin, Dominique; Daubert, Jean-Claude; Mabo, Philippe; Leclercq, Christophe; Martins, Raphael P

    2017-10-15

    Atrioventricular node (AVN) ablation is usually a simple procedure but may sometimes be challenging. We aimed at identifying pre-procedural clinical predictors of challenging AVN ablation. Patients referred for AVN ablation from 2009 to 2015 were retrospectively included. Baseline clinical data, procedural variables and outcomes of AVN ablation were collected. A "challenging procedure" was defined 1) total radiofrequency delivery to get persistent AVN block≥400s, 2) need for left-sided arterial approach or 3) failure to obtain AVN ablation. 200 patients were included (71±10years). A total of 37 (18.5%) patients had "challenging" procedures (including 9 failures, 4.5%), while 163 (81.5%) had "non-challenging" ablations. In multivariable analysis, male sex (Odds ratio (OR)=4.66, 95% confidence interval (CI): 1.74-12.46), body mass index (BMI, OR=1.08 per 1kg/m 2 , 95%CI 1.01-1.16), operator experience (OR=0.40, 95%CI 0.17-0.94), and moderate-to-severe tricuspid regurgitation (TR, OR=3.65, 95%CI 1.63-8.15) were significant predictors of "challenging" ablations. The proportion as a function of number of predictors was analyzed (from 0 to 4, including male sex, operator inexperience, a BMI>23.5kg/m 2 and moderate-to-severe TR). There was a gradual increase in the risk of "challenging" procedure with the number of predictors by patient (No predictor: 0%; 1 predictor: 6.3%; 2 predictors: 16.5%; 3 predictors: 32.5%; 4 predictors: 77.8%). Operator experience, male sex, higher BMI and the degree of TR were independent predictors of "challenging" AVN ablation procedure. The risk increases with the number of predictors by patient. Copyright © 2017. Published by Elsevier B.V.

  20. Assessment of Effect on LBLOCA PCT for Change in Upper Head Nodalization

    International Nuclear Information System (INIS)

    Kang, Dong Gu; Huh, Byung Gil; Yoo, Seung Hun; Bang, Youngseok; Seul, Kwangwon; Cho, Daehyung

    2014-01-01

    In this study, the best estimate plus uncertainty (BEPU) analysis of LBLOCA for original and modified nodalizations was performed, and the effect on LBLOCA PCT for change in upper head nodalization was assessed. In this study, the best estimate plus uncertainty (BEPU) analysis of LBLOCA for original and modified nodalizations was performed, and the effect on LBLOCA PCT for change in upper head nodalization was assessed. It is confirmed that modification of upper head nodalization influences PCT behavior, especially in the reflood phase. In conclusions, the modification of nodalization to reflect design characteristic of upper head temperature should be done to predict PCT behavior accurately in LBLOCA analysis. In the best estimate (BE) method with the uncertainty evaluation, the system nodalization is determined by the comparative studies of the experimental data. Up to now, it was assumed that the temperature of the upper dome in OPR-1000 was close to that of the cold leg. However, it was found that the temperature of the upper head/dome might be a little lower than or similar to that of the hot leg through the evaluation of the detailed design data. Since the higher upper head temperature affects blowdown quenching and peak cladding temperature in the reflood phase, the nodalization for upper head should be modified

  1. LOLA SYSTEM: A code block for nodal PWR simulation. Part. I - Simula-3 Code

    Energy Technology Data Exchange (ETDEWEB)

    Aragones, J M; Ahnert, C; Gomez Santamaria, J; Rodriguez Olabarria, I

    1985-07-01

    Description of the theory and users manual of the SIMULA-3 code, which is part of the core calculation system by nodal theory in one group, called LOLA SYSTEM. SIMULA-3 is the main module of the system, it uses a modified nodal theory, with interface leakages equivalent to the diffusion theory. (Author) 4 refs.

  2. Rules for Phase Shifts of Quantum Oscillations in Topological Nodal-Line Semimetals

    Science.gov (United States)

    Li, Cequn; Wang, C. M.; Wan, Bo; Wan, Xiangang; Lu, Hai-Zhou; Xie, X. C.

    2018-04-01

    Nodal-line semimetals are topological semimetals in which band touchings form nodal lines or rings. Around a loop that encloses a nodal line, an electron can accumulate a nontrivial π Berry phase, so the phase shift in the Shubnikov-de Haas (SdH) oscillation may give a transport signature for the nodal-line semimetals. However, different experiments have reported contradictory phase shifts, in particular, in the WHM nodal-line semimetals (W =Zr /Hf , H =Si /Ge , M =S /Se /Te ). For a generic model of nodal-line semimetals, we present a systematic calculation for the SdH oscillation of resistivity under a magnetic field normal to the nodal-line plane. From the analytical result of the resistivity, we extract general rules to determine the phase shifts for arbitrary cases and apply them to ZrSiS and Cu3 PdN systems. Depending on the magnetic field directions, carrier types, and cross sections of the Fermi surface, the phase shift shows rich results, quite different from those for normal electrons and Weyl fermions. Our results may help explore transport signatures of topological nodal-line semimetals and can be generalized to other topological phases of matter.

  3. Nodal integral method for the neutron diffusion equation in cylindrical geometry

    International Nuclear Information System (INIS)

    Azmy, Y.Y.

    1987-01-01

    The nodal methodology is based on retaining a higher a higher degree of analyticity in the process of deriving the discrete-variable equations compared to conventional numerical methods. As a result, extensive numerical testing of nodal methods developed for a wide variety of partial differential equations and comparison of the results to conventional methods have established the superior accuracy of nodal methods on coarse meshes. Moreover, these tests have shown that nodal methods are more computationally efficient than finite difference and finite-element methods in the sense that they require shorter CPU times to achieve comparable accuracy in the solutions. However, nodal formalisms and the final discrete-variable equations they produce are, in general, more complicated than their conventional counterparts. This, together with anticipated difficulties in applying the transverse-averaging procedure in curvilinear coordinates, has limited the applications of nodal methods, so far, to Cartesian geometry, and with additional approximations to hexagonal geometry. In this paper the authors report recent progress in deriving and numerically implementing a nodal integral method (NIM) for solving the neutron diffusion equation in cylindrical r-z geometry. Also, presented are comparisons of numerical solutions to two test problems with those obtained by the Exterminator-2 code, which indicate the superior accuracy of the nodal integral method solutions on much coarser meshes

  4. LOLA SYSTEM: A code block for nodal PWR simulation. Part. I - Simula-3 Code

    International Nuclear Information System (INIS)

    Aragones, J. M.; Ahnert, C.; Gomez Santamaria, J.; Rodriguez Olabarria, I.

    1985-01-01

    Description of the theory and users manual of the SIMULA-3 code, which is part of the core calculation system by nodal theory in one group, called LOLA SYSTEM. SIMULA-3 is the main module of the system, it uses a modified nodal theory, with interface leakages equivalent to the diffusion theory. (Author) 4 refs

  5. A practical implementation of the higher-order transverse-integrated nodal diffusion method

    International Nuclear Information System (INIS)

    Prinsloo, Rian H.; Tomašević, Djordje I.; Moraal, Harm

    2014-01-01

    Highlights: • A practical higher-order nodal method is developed for diffusion calculations. • The method resolves the issue of the transverse leakage approximation. • The method achieves much superior accuracy as compared to standard nodal methods. • The calculational cost is only about 50% greater than standard nodal methods. • The method is packaged in a module for connection to existing nodal codes. - Abstract: Transverse-integrated nodal diffusion methods currently represent the standard in full core neutronic simulation. The primary shortcoming of this approach is the utilization of the quadratic transverse leakage approximation. This approach, although proven to work well for typical LWR problems, is not consistent with the formulation of nodal methods and can cause accuracy and convergence problems. In this work, an improved, consistent quadratic leakage approximation is formulated, which derives from the class of higher-order nodal methods developed some years ago. Further, a number of iteration schemes are developed around this consistent quadratic leakage approximation which yields accurate node average results in much improved calculational times. The most promising of these iteration schemes results from utilizing the consistent leakage approximation as a correction method to the standard quadratic leakage approximation. Numerical results are demonstrated on a set of benchmark problems and further applied to a realistic reactor problem, particularly the SAFARI-1 reactor, operating at Necsa, South Africa. The final optimal solution strategy is packaged into a standalone module which may simply be coupled to existing nodal diffusion codes

  6. Recent advances in managing septal defects: ventricular septal defects and atrioventricular septal defects [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    P Syamasundar Rao

    2018-04-01

    Full Text Available This review discusses the management of ventricular septal defects (VSDs and atrioventricular septal defects (AVSDs. There are several types of VSDs: perimembranous, supracristal, atrioventricular septal, and muscular. The indications for closure are moderate to large VSDs with enlarged left atrium and left ventricle or elevated pulmonary artery pressure (or both and a pulmonary-to-systemic flow ratio greater than 2:1. Surgical closure is recommended for large perimembranous VSDs, supracristal VSDs, and VSDs with aortic valve prolapse. Large muscular VSDs may be closed by percutaneous techniques. A large number of devices have been used in the past for VSD occlusion, but currently Amplatzer Muscular VSD Occluder is the only device approved by the US Food and Drug Administration for clinical use. A hybrid approach may be used for large muscular VSDs in small babies. Timely intervention to prevent pulmonary vascular obstructive disease (PVOD is germane in the management of these babies. There are several types of AVSDs: partial, transitional, intermediate, and complete. Complete AVSDs are also classified as balanced and unbalanced. All intermediate and complete balanced AVSDs require surgical correction, and early repair is needed to prevent the onset of PVOD. Surgical correction with closure of atrial septal defect and VSD, along with repair and reconstruction of atrioventricular valves, is recommended. Palliative pulmonary artery banding may be considered in babies weighing less than 5 kg and those with significant co-morbidities. The management of unbalanced AVSDs is more complex, and staged single-ventricle palliation is the common management strategy. However, recent data suggest that achieving two-ventricle repair may be a better option in patients with suitable anatomy, particularly in patients in whom outcomes of single-ventricle palliation are less than optimal. The majority of treatment modes in the management of VSDs and AVSDs are safe

  7. Opposing nodal and BMP signals regulate left-right asymmetry in the sea urchin larva.

    Directory of Open Access Journals (Sweden)

    Yi-Jyun Luo

    Full Text Available Nodal and BMP signals are important for establishing left-right (LR asymmetry in vertebrates. In sea urchins, Nodal signaling prevents the formation of the rudiment on the right side. However, the opposing pathway to Nodal signaling during LR axis establishment is not clear. Here, we revealed that BMP signaling is activated in the left coelomic pouch, specifically in the veg2 lineage, but not in the small micromeres. By perturbing BMP activities, we demonstrated that BMP signaling is required for activating the expression of the left-sided genes and the formation of the left-sided structures. On the other hand, Nodal signals on the right side inhibit BMP signaling and control LR asymmetric separation and apoptosis of the small micromeres. Our findings show that BMP signaling is the positive signal for left-sided development in sea urchins, suggesting that the opposing roles of Nodal and BMP signals in establishing LR asymmetry are conserved in deuterostomes.

  8. A spectral nodal method for discrete ordinates problems in x,y geometry

    International Nuclear Information System (INIS)

    Barros, R.C. de; Larsen, E.W.

    1991-06-01

    A new nodal method is proposed for the solution of S N problems in x- y-geometry. This method uses the Spectral Green's Function (SGF) scheme for solving the one-dimensional transverse-integrated nodal transport equations with no spatial truncation error. Thus, the only approximations in the x, y-geometry nodal method occur in the transverse leakage terms, as in diffusion theory. We approximate these leakage terms using a flat or constant approximation, and we refer to the resulting method as the SGF-Constant Nodal (SGF-CN) method. We show in numerical calculations that the SGF-CN method is much more accurate than other well-known transport nodal methods for coarse-mesh deep-penetration S N problems, even though the transverse leakage terms are approximated rather simply. (author)

  9. Dissection of a Quantitative Trait Locus for PR Interval Duration Identifies Tnni3k as a Novel Modulator of Cardiac Conduction

    NARCIS (Netherlands)

    Lodder, Elisabeth M.; Scicluna, Brendon P.; Milano, Annalisa; Sun, Albert Y.; Tang, Hao; Remme, Carol Ann; Moerland, Perry D.; Tanck, Michael W. T.; Pitt, Geoffrey S.; Marchuk, Douglas A.; Bezzina, Connie R.

    2012-01-01

    Atrio-ventricular conduction disease is a common feature in Mendelian rhythm disorders associated with sudden cardiac death and is characterized by prolongation of the PR interval on the surface electrocardiogram (ECG). Prolongation of the PR interval is also a strong predictor of atrial

  10. Right heart failure due to loss of right ventricular capture in a patient with atrioventricular junction ablation and biventricular pacing.

    Science.gov (United States)

    Raffa, Santi; Fantoni, Cecilia; Restauri, Luigia; Auricchio, Angelo

    2005-10-01

    We describe the case of a patient with atrioventricular (AV) junction ablation and chronic biventricular pacing in which intermittent dysfunction of the right ventricular (RV) lead resulted in left ventricular (LV) stimulation alone and onset of severe right heart failure. Restoration of biventricular pacing by increasing device output and then performing lead revision resolved the issue. This case provides evidence that LV pacing alone in patients with AV junction ablation may lead to severe right heart failure, most likely as a result of iatrogenic mechanical dyssynchrony within the RV. Thus, probably this pacing mode should be avoided in pacemaker-dependent patients with heart failure.

  11. Transient complete atrioventricular block with Morgagni—Adams—Stokes attacks in a child after aortic valve replacement

    Directory of Open Access Journals (Sweden)

    D. R. Sabirova

    2014-01-01

    Full Text Available The diagnosis and treatment of life-threatening arrhythmias after surgical correction of congenital heart diseases is one the urgent problems in pediatrlc cardiology. The paper describes the clinical picture, diagnosis, and therapy in a patent with transient complete atrioventricular block after open heart surgery. A protracted Morgagni—Adams—Stokes attack is one of the causes of sudden cardiac death. The occurrence of even single syncopes in patients after surgery for congenital heart disease requires that the arrhythmogenic nature of the attack should be ruled out for the timely and adequate therapy including the implantation of antiarrhythmic devices.

  12. Echo determinants of dyssynchrony (atrioventricular and inter- and intraventricular) and predictors of response to cardiac resynchronization therapy.

    Science.gov (United States)

    Kapetanakis, Stamatis; Bhan, Amit; Monaghan, Mark J

    2008-10-01

    Cardiac resynchronization therapy (CRT) has revolutionized not only the treatment of chronic heart failure but also how we assess left ventricular (LV) dysfunction on echo. Increasingly, it has become clear that identifying and quantifying delays in events during the cardiac cycle is an important assessment in LV dysfunction as it has prognostic implications for patients undergoing CRT. The delays in atrioventricular, right-to-left ventricular, and LV segmental contraction have been shown to be important components in cardiac performance, and this review provides an overview of the commonest methods used for these assessments and their implications for selecting patients for biventricular pacing.

  13. An integral nodal variational method for multigroup criticality calculations

    International Nuclear Information System (INIS)

    Lewis, E.E.; Tsoulfanidis, N.

    2003-01-01

    An integral formulation of the variational nodal method is presented and applied to a series of benchmark critically problems. The method combines an integral transport treatment of the even-parity flux within the spatial node with an odd-parity spherical harmonics expansion of the Lagrange multipliers at the node interfaces. The response matrices that result from this formulation are compatible with those in the VARIANT code at Argonne National Laboratory. Either homogeneous or heterogeneous nodes may be employed. In general, for calculations requiring higher-order angular approximations, the integral method yields solutions with comparable accuracy while requiring substantially less CPU time and memory than the standard spherical harmonics expansion using the same spatial approximations. (author)

  14. An Adaptive Approach to Variational Nodal Diffusion Problems

    International Nuclear Information System (INIS)

    Zhang Hui; Lewis, E.E.

    2001-01-01

    An adaptive grid method is presented for the solution of neutron diffusion problems in two dimensions. The primal hybrid finite elements employed in the variational nodal method are used to reduce the diffusion equation to a coupled set of elemental response matrices. An a posteriori error estimator is developed to indicate the magnitude of local errors stemming from the low-order elemental interface approximations. An iterative procedure is implemented in which p refinement is applied locally by increasing the polynomial order of the interface approximations. The automated algorithm utilizes the a posteriori estimator to achieve local error reductions until an acceptable level of accuracy is reached throughout the problem domain. Application to a series of X-Y benchmark problems indicates the reduction of computational effort achievable by replacing uniform with adaptive refinement of the spatial approximations

  15. A nonlinear analytic function expansion nodal method for transient calculations

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Han Gyn; Park, Sang Yoon; Cho, Byung Oh; Zee, Sung Quun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    The nonlinear analytic function expansion nodal (AFEN) method is applied to the solution of the time-dependent neutron diffusion equation. Since the AFEN method requires both the particular solution and the homogeneous solution to the transient fixed source problem, the derivation of the solution method is focused on finding the particular solution efficiently. To avoid complicated particular solutions, the source distribution is approximated by quadratic polynomials and the transient source is constructed such that the error due to the quadratic approximation is minimized, In addition, this paper presents a new two-node solution scheme that is derived by imposing the constraint of current continuity at the interface corner points. The method is verified through a series of application to the NEACRP PWR rod ejection benchmark problems. 6 refs., 2 figs., 1 tab. (Author)

  16. On-line application of the PANTHER advanced nodal code

    International Nuclear Information System (INIS)

    Hutt, P.K.; Knight, M.P.

    1992-01-01

    Over the last few years, Nuclear Electric has developed an integrated core performance code package for both light water reactors (LWRs) and advanced gas-cooled reactors (AGRs) that can perform a comprehensive range of calculations for fuel cycle design, safety analysis, and on-line operational support for such plants. The package consists of the following codes: WIMS for lattice physics, PANTHER whole reactor nodal flux and AGR thermal hydraulics, VIPRE for LWR thermal hydraulics, and ENIGMA for fuel performance. These codes are integrated within a UNIX-based interactive system called the Reactor Physics Workbench (RPW), which provides an interactive graphic user interface and quality assurance records/data management. The RPW can also control calculational sequences and data flows. The package has been designed to run both off-line and on-line accessing plant data through the RPW

  17. Nodal domains on isospectral quantum graphs: the resolution of isospectrality?

    International Nuclear Information System (INIS)

    Band, Ram; Shapira, Talia; Smilansky, Uzy

    2006-01-01

    We present and discuss isospectral quantum graphs which are not isometric. These graphs are the analogues of the isospectral domains in R 2 which were introduced recently in Gordon et al (1992 Bull. Am. Math. Soc. 27 134-8), Chapman (1995 Am. Math. Mon. 102 124), Buser et al (1994 Int. Math. Res. Not. 9 391-400), Okada and Shudo (2001 J. Phys. A: Math. Gen. 34 5911-22), Jakobson et al (2006 J. Comput. Appl. Math. 194 141-55) and Levitin et al (2006 J. Phys. A: Math. Gen. 39 2073-82)) all based on Sunada's construction of isospectral domains (Sunada T 1985 Ann. Math. 121 196-86). After presenting some of the properties of these graphs, we discuss a few examples which support the conjecture that by counting the nodal domains of the corresponding eigenfunctions one can resolve the isospectral ambiguity

  18. CAISO flicks switch on nodal scheme and lights stay on

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-06-15

    In 2000-01, two years after introducing a competitive wholesale power auction in California - with a separate day-ahead zonal market operated by the California Power Exchange and a zonal market for ancillary services and balancing energy operated by the California Independent System Operator (CAISO) - the California market collapsed from exorbitant prices, flagrant gaming, and abuse of market power. Nine years later, CAISO introduced a nodal pricing auction for the wholesale market in April, replacing the zonal scheme, which was among many causes of the original market's demise. With nearly 3,000 nodes on the network, high prices in one region do not affect prices everywhere on the system. After investing some $200 million to upgrade the software, countless delays, and 18 months of market simulation and testing, the new auction was introduced and nothing unusual happened.

  19. Ultrasound beam characteristics of a symmetric nodal origami based array

    Science.gov (United States)

    Bilgunde, Prathamesh N.; Bond, Leonard J.

    2018-04-01

    Origami-the ancient art of paper folding-is being explored in acoustics for effective focusing of sound. In this short communication, we present a numerical investigation of beam characteristics for an origami based ultrasound array. A spatial re-configuration of array elements is performed based upon the symmetric nodal origami. The effect of fold angle on the ultrasound beam is evaluated using frequency domain and transient finite element analysis. It was found that increase in the fold angle reduces near field length by 58% and also doubles the beam intensity as compared to the linear array. Transient analysis also indicated 80% reduction in the -6dB beam width, which can improve the lateral resolution of phased array. Such a spatially re-configurable array could potentially be used in the future to reduce the cost of electronics in the phased array instrumentation.

  20. Space-angle approximations in the variational nodal method

    International Nuclear Information System (INIS)

    Lewis, E. E.; Palmiotti, G.; Taiwo, T.

    1999-01-01

    The variational nodal method is formulated such that the angular and spatial approximations maybe examined separately. Spherical harmonic, simplified spherical harmonic, and discrete ordinate approximations are coupled to the primal hybrid finite element treatment of the spatial variables. Within this framework, two classes of spatial trial functions are presented: (1) orthogonal polynomials for the treatment of homogeneous nodes and (2) bilinear finite subelement trial functions for the treatment of fuel assembly sized nodes in which fuel-pin cell cross sections are represented explicitly. Polynomial and subelement trial functions are applied to benchmark water-reactor problems containing MOX fuel using spherical harmonic and simplified spherical harmonic approximations. The resulting accuracy and computing costs are compared

  1. A nonlinear analytic function expansion nodal method for transient calculations

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Han Gyn; Park, Sang Yoon; Cho, Byung Oh; Zee, Sung Quun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-12-31

    The nonlinear analytic function expansion nodal (AFEN) method is applied to the solution of the time-dependent neutron diffusion equation. Since the AFEN method requires both the particular solution and the homogeneous solution to the transient fixed source problem, the derivation of the solution method is focused on finding the particular solution efficiently. To avoid complicated particular solutions, the source distribution is approximated by quadratic polynomials and the transient source is constructed such that the error due to the quadratic approximation is minimized, In addition, this paper presents a new two-node solution scheme that is derived by imposing the constraint of current continuity at the interface corner points. The method is verified through a series of application to the NEACRP PWR rod ejection benchmark problems. 6 refs., 2 figs., 1 tab. (Author)

  2. ANDREA: Advanced nodal diffusion code for reactor analysis

    International Nuclear Information System (INIS)

    Belac, J.; Josek, R.; Klecka, L.; Stary, V.; Vocka, R.

    2005-01-01

    A new macro code is being developed at NRI which will allow coupling of the advanced thermal-hydraulics model with neutronics calculations as well as efficient use in core loading pattern optimization process. This paper describes the current stage of the macro code development. The core simulator is based on the nodal expansion method, Helios lattice code is used for few group libraries preparation. Standard features such as pin wise power reconstruction and feedback iterations on critical control rod position, boron concentration and reactor power are implemented. A special attention is paid to the system and code modularity in order to enable flexible and easy implementation of new features in future. Precision of the methods used in the macro code has been verified on available benchmarks. Testing against Temelin PWR operational data is under way (Authors)

  3. Comparison of PANTHER nodal solutions in hexagonal-z geometry

    International Nuclear Information System (INIS)

    Knight, M.; Hutt, P.; Lewis, I.

    1995-01-01

    The reactor physics code PANTHER has been extended to hexagonal geometries. Steady-state, depletion, and transient calculations with feedback can all be performed. Two hexagonal nodal flux solutions have been developed. In the first method, transverse integration is performed exactly as in the rectangular case. The resulting transverse integrated equation has singular terms, which are simply ignored. The second approach applies a conformal mapping that transforms the hexagon onto a rectangle. Pin power reconstruction has also been developed with both methods. For a benchmark VVER-1000 reactor depletion problem, both methods give accurate results for standard depletion calculations. In the more extreme situation with all rods inserted, the simpler method breaks down. However, the accuracy of the conformal solution was found to be excellent in all cases studied

  4. Static benchmarking of the NESTLE advanced nodal code

    International Nuclear Information System (INIS)

    Mosteller, R.D.

    1997-01-01

    Results from the NESTLE advanced nodal code are presented for multidimensional numerical benchmarks representing four different types of reactors, and predictions from NESTLE are compared with measured data from pressurized water reactors (PWRs). The numerical benchmarks include cases representative of PWRs, boiling water reactors (BWRs), CANDU heavy water reactors (HWRs), and high-temperature gas-cooled reactors (HTGRs). The measured PWR data include critical soluble boron concentrations and isothermal temperature coefficients of reactivity. The results demonstrate that NESTLE correctly solves the multigroup diffusion equations for both Cartesian and hexagonal geometries, that it reliably calculates k eff and reactivity coefficients for PWRs, and that--subsequent to the incorporation of additional thermal-hydraulic models--it will be able to perform accurate calculations for the corresponding parameters in BWRs, HWRs, and HTGRs as well

  5. Contemporary Management of Recurrent Nodal Disease in Differentiated Thyroid Carcinoma

    Science.gov (United States)

    Na’ara, Shorook; Amit, Moran; Fridman, Eran; Gil, Ziv

    2016-01-01

    Differentiated thyroid carcinoma (DTC) comprises over 90% of thyroid tumors and includes papillary and follicular carcinomas. Patients with DTC have an excellent prognosis, with a 10-year survival rate of over 90%. However, the risk of recurrent tumor ranges between 5% and 30% within 10 years of the initial diagnosis. Cervical lymph node disease accounts for the majority of recurrences and in most cases is detected during follow-up by ultrasound or elevated levels of serum thyroglobulin. Recurrent disease is accompanied by increased morbidity. The mainstay of treatment of nodal recurrence is surgical management. We provide an overview of the literature addressing surgical management of recurrent or persistent lymph node disease in patients with DTC. PMID:26886954

  6. Error Estimation and Accuracy Improvements in Nodal Transport Methods

    International Nuclear Information System (INIS)

    Zamonsky, O.M.

    2000-01-01

    The accuracy of the solutions produced by the Discrete Ordinates neutron transport nodal methods is analyzed.The obtained new numerical methodologies increase the accuracy of the analyzed scheems and give a POSTERIORI error estimators. The accuracy improvement is obtained with new equations that make the numerical procedure free of truncation errors and proposing spatial reconstructions of the angular fluxes that are more accurate than those used until present. An a POSTERIORI error estimator is rigurously obtained for one dimensional systems that, in certain type of problems, allows to quantify the accuracy of the solutions. From comparisons with the one dimensional results, an a POSTERIORI error estimator is also obtained for multidimensional systems. LOCAL indicators, which quantify the spatial distribution of the errors, are obtained by the decomposition of the menctioned estimators. This makes the proposed methodology suitable to perform adaptive calculations. Some numerical examples are presented to validate the theoretical developements and to illustrate the ranges where the proposed approximations are valid

  7. Nodal wear model: corrosion in carbon blast furnace hearths

    Directory of Open Access Journals (Sweden)

    Verdeja, L. F.

    2003-06-01

    Full Text Available Criterions developed for the Nodal Wear Model (NWM were applied to estimate the shape of the corrosion profiles that a blast furnace hearth may acquire during its campaign. Taking into account design of the hearth, the boundary conditions, the characteristics of the refractory materials used and the operation conditions of the blast furnace, simulation of wear profiles with central well, mushroom and elephant foot shape were accomplished. The foundations of the NWM are constructed considering that the corrosion of the refractory is a function of the temperature present at each point (node of the liquid metal-refractory interface and the corresponding physical and chemical characteristics of the corrosive fluid.

    Se aplican los criterios del Modelo de Desgaste Nodal (MDN para la estimación de los perfiles de corrosión que podría ir adquiriendo el crisol de un homo alto durante su campaña. Atendiendo al propio diseño del crisol, a las condiciones límites de contorno, a las características del material refractario utilizado y a las condiciones de operación del horno, se consiguen simular perfiles de desgaste con "pozo central", con "forma de seta" ó de "pie de elefante". Los fundamentos del MDN se apoyan en la idea de considerar que la corrosión del refractario es función de la temperatura que el sistema pueda presentar en cada punto (nodo de la intercara refractario-fundido y de las correspondientes características físico-químicas del fluido corrosivo.

  8. Mapping of nodal disease in locally advanced prostate cancer: Rethinking the clinical target volume for pelvic nodal irradiation based on vascular rather than bony anatomy

    International Nuclear Information System (INIS)

    Shih, Helen A.; Harisinghani, Mukesh; Zietman, Anthony L.; Wolfgang, John A.; Saksena, Mansi; Weissleder, Ralph

    2005-01-01

    Purpose: Toxicity from pelvic irradiation could be reduced if fields were limited to likely areas of nodal involvement rather than using the standard 'four-field box.' We employed a novel magnetic resonance lymphangiographic technique to highlight the likely sites of occult nodal metastasis from prostate cancer. Methods and Materials: Eighteen prostate cancer patients with pathologically confirmed node-positive disease had a total of 69 pathologic nodes identifiable by lymphotropic nanoparticle-enhanced MRI and semiquantitative nodal analysis. Fourteen of these nodes were in the para-aortic region, and 55 were in the pelvis. The position of each of these malignant nodes was mapped to a common template based on its relation to skeletal or vascular anatomy. Results: Relative to skeletal anatomy, nodes covered a diffuse volume from the mid lumbar spine to the superior pubic ramus and along the sacrum and pelvic side walls. In contrast, the nodal metastases mapped much more tightly relative to the large pelvic vessels. A proposed pelvic clinical target volume to encompass the region at greatest risk of containing occult nodal metastases would include a 2.0-cm radial expansion volume around the distal common iliac and proximal external and internal iliac vessels that would encompass 94.5% of the pelvic nodes at risk as defined by our node-positive prostate cancer patient cohort. Conclusions: Nodal metastases from prostate cancer are largely localized along the major pelvic vasculature. Defining nodal radiation treatment portals based on vascular rather than bony anatomy may allow for a significant decrease in normal pelvic tissue irradiation and its associated toxicities

  9. A simple nodal force distribution method in refined finite element meshes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jai Hak [Chungbuk National University, Chungju (Korea, Republic of); Shin, Kyu In [Gentec Co., Daejeon (Korea, Republic of); Lee, Dong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2017-05-15

    In finite element analyses, mesh refinement is frequently performed to obtain accurate stress or strain values or to accurately define the geometry. After mesh refinement, equivalent nodal forces should be calculated at the nodes in the refined mesh. If field variables and material properties are available at the integration points in each element, then the accurate equivalent nodal forces can be calculated using an adequate numerical integration. However, in certain circumstances, equivalent nodal forces cannot be calculated because field variable data are not available. In this study, a very simple nodal force distribution method was proposed. Nodal forces of the original finite element mesh are distributed to the nodes of refined meshes to satisfy the equilibrium conditions. The effect of element size should also be considered in determining the magnitude of the distributing nodal forces. A program was developed based on the proposed method, and several example problems were solved to verify the accuracy and effectiveness of the proposed method. From the results, accurate stress field can be recognized to be obtained from refined meshes using the proposed nodal force distribution method. In example problems, the difference between the obtained maximum stress and target stress value was less than 6 % in models with 8-node hexahedral elements and less than 1 % in models with 20-node hexahedral elements or 10-node tetrahedral elements.

  10. A polygonal nodal SP3 method for whole core Pin-by-Pin neutronics calculation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yunzhao; Wu, Hongchun; Cao, Liangzhi, E-mail: xjtulyz@gmail.com, E-mail: hongchun@mail.xjtu.edu.cn, E-mail: caolz@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi' an Jiaotong University, Shaanxi (China)

    2011-07-01

    In this polygonal nodal-SP3 method, neutron transport equation is transformed by employing an isotropic SP3 method into two coupled equations that are both in the same mathematic form with the diffusion equation, and then a polygonal nodal method is proposed to solve the two coupled equations. In the polygonal nodal method, adjacent nodes are coupled through partial currents, and a nodal response matrix between incoming and outgoing currents is obtained by expanding detailed nodal flux distribution into a sum of exponential functions. This method avoids the transverse integral technique, which is widely used in regular nodal method and can not be used in triangular geometry because of the mathematical singularity. It is demonstrated by the numerical results of the test problems that the k{sub eff} and power distribution agree well with other codes, the triangular nodal-SP3 method appears faster, and that whole core pin-by-pin transport calculation with fine meshes is feasible after parallelization and acceleration. (author)

  11. Nodal price volatility reduction and reliability enhancement of restructured power systems considering demand-price elasticity

    International Nuclear Information System (INIS)

    Goel, L.; Wu, Qiuwei; Wang, Peng

    2008-01-01

    With the development of restructured power systems, the conventional 'same for all customers' electricity price is getting replaced by nodal prices. Electricity prices will fluctuate with time and nodes. In restructured power systems, electricity demands will interact mutually with prices. Customers may shift some of their electricity consumption from time slots of high electricity prices to those of low electricity prices if there is a commensurate price incentive. The demand side load shift will influence nodal prices in return. This interaction between demand and price can be depicted using demand-price elasticity. This paper proposes an evaluation technique incorporating the impact of the demand-price elasticity on nodal prices, system reliability and nodal reliabilities of restructured power systems. In this technique, demand and price correlations are represented using the demand-price elasticity matrix which consists of self/cross-elasticity coefficients. Nodal prices are determined using optimal power flow (OPF). The OPF and customer damage functions (CDFs) are combined in the proposed reliability evaluation technique to assess the reliability enhancement of restructured power systems considering demand-price elasticity. The IEEE reliability test system (RTS) is simulated to illustrate the developed techniques. The simulation results show that demand-price elasticity reduces the nodal price volatility and improves both the system reliability and nodal reliabilities of restructured power systems. Demand-price elasticity can therefore be utilized as a possible efficient tool to reduce price volatility and to enhance the reliability of restructured power systems. (author)

  12. Type-I and type-II topological nodal superconductors with s -wave interaction

    Science.gov (United States)

    Huang, Beibing; Yang, Xiaosen; Xu, Ning; Gong, Ming

    2018-01-01

    Topological nodal superconductors with protected gapless points in momentum space are generally realized based on unconventional pairings. In this work we propose a minimal model to realize these topological nodal phases with only s -wave interaction. In our model the linear and quadratic spin-orbit couplings along the two orthogonal directions introduce anisotropic effective unconventional pairings in momentum space. This model may support different nodal superconducting phases characterized by either an integer winding number in BDI class or a Z2 index in D class at the particle-hole invariant axes. In the vicinity of the nodal points the effective Hamiltonian can be described by either type-I or type-II Dirac equations, and the Lifshitz transition from type-I nodal phases to type-II nodal phases can be driven by external in-plane magnetic fields. We show that these nodal phases are robust against weak impurities, which only slightly renormalizes the momentum-independent parameters in the impurity-averaged Hamiltonian, thus these phases are possible to be realized in experiments with real semi-Dirac materials. The smoking-gun evidences to verify these phases based on scanning tunneling spectroscopy method are also briefly discussed.

  13. Nodal-dependent mesendoderm specification requires the combinatorial activities of FoxH1 and Eomesodermin.

    Directory of Open Access Journals (Sweden)

    Christopher E Slagle

    2011-05-01

    Full Text Available Vertebrate mesendoderm specification requires the Nodal signaling pathway and its transcriptional effector FoxH1. However, loss of FoxH1 in several species does not reliably cause the full range of loss-of-Nodal phenotypes, indicating that Nodal signals through additional transcription factors during early development. We investigated the FoxH1-dependent and -independent roles of Nodal signaling during mesendoderm patterning using a novel recessive zebrafish FoxH1 mutation called midway, which produces a C-terminally truncated FoxH1 protein lacking the Smad-interaction domain but retaining DNA-binding capability. Using a combination of gel shift assays, Nodal overexpression experiments, and genetic epistasis analyses, we demonstrate that midway more accurately represents a complete loss of FoxH1-dependent Nodal signaling than the existing zebrafish FoxH1 mutant schmalspur. Maternal-zygotic midway mutants lack notochords, in agreement with FoxH1 loss in other organisms, but retain near wild-type expression of markers of endoderm and various nonaxial mesoderm fates, including paraxial and intermediate mesoderm and blood precursors. We found that the activity of the T-box transcription factor Eomesodermin accounts for specification of these tissues in midway embryos. Inhibition of Eomesodermin in midway mutants severely reduces the specification of these tissues and effectively phenocopies the defects seen upon complete loss of Nodal signaling. Our results indicate that the specific combinations of transcription factors available for signal transduction play critical and separable roles in determining Nodal pathway output during mesendoderm patterning. Our findings also offer novel insights into the co-evolution of the Nodal signaling pathway, the notochord specification program, and the chordate branch of the deuterostome family of animals.

  14. Face centered cubic SnSe as a Z2 trivial Dirac nodal line material

    OpenAIRE

    Tateishi, Ikuma; Matsuura, Hiroyasu

    2018-01-01

    The presence of Dirac nodal line in the time-reversal and inversion symmetric system is dictated by Z2 index when spin-orbit interaction is absent. With the first principles calculation, we show that the Dirac nodal line can emerge in Z2 trivial material by calculating the band structure of SnSe of face centered cubic lattice as an example and it becomes a topological crystalline insulator when spin-orbit interaction is taken into account. We clarify the origin of the Dirac nodal line by obta...

  15. NUMERICAL SOLUTION OF SINGULAR INVERSE NODAL PROBLEM BY USING CHEBYSHEV POLYNOMIALS

    OpenAIRE

    NEAMATY, ABDOLALI; YILMAZ, EMRAH; AKBARPOOR, SHAHRBANOO; DABBAGHIAN, ABDOLHADI

    2017-01-01

    In this study, we consider Sturm-Liouville problem in two cases: the first case having no singularity and the second case having a singularity at zero. Then, we calculate the eigenvalues and the nodal points and present the uniqueness theorem for the solution of the inverse problem by using a dense subset of the nodal points in two given cases. Also, we use Chebyshev polynomials of the first kind for calculating the approximate solution of the inverse nodal problem in these cases. Finally, we...

  16. Using nodal expansion method in calculation of reactor core with square fuel assemblies

    International Nuclear Information System (INIS)

    Abdollahzadeh, M. Y.; Boroushaki, M.

    2009-01-01

    A polynomial nodal method is developed to solve few-group neutron diffusion equations in cartesian geometry. In this article, the effective multiplication factor, group flux and power distribution based on the nodal polynomial expansion procedure is presented. In addition, by comparison of the results the superiority of nodal expansion method on finite-difference and finite-element are fully demonstrated. The comparison of the results obtained by these method with those of the well known benchmark problems have shown that they are in very good agreement.

  17. [Method for optimal sensor placement in water distribution systems with nodal demand uncertainties].

    Science.gov (United States)

    Liu, Shu-Ming; Wu, Xue; Ouyang, Le-Yan

    2013-08-01

    The notion of identification fitness was proposed for optimizing sensor placement in water distribution systems. Nondominated Sorting Genetic Algorithm II was used to find the Pareto front between minimum overlap of possible detection times of two events and the best probability of detection, taking nodal demand uncertainties into account. This methodology was applied to an example network. The solutions show that the probability of detection and the number of possible locations are not remarkably affected by nodal demand uncertainties, but the sources identification accuracy declines with nodal demand uncertainties.

  18. The application of modern nodal methods to PWR reactor physics analysis

    International Nuclear Information System (INIS)

    Knight, M.P.

    1988-06-01

    The objective of this research is to develop efficient computational procedures for PWR reactor calculations, based on modern nodal methods. The analytic nodal method, which is characterised by the use of exact exponential expansions in transverse-integrated equations, is implemented within an existing finite-difference code. This shows considerable accuracy and efficiency on standard benchmark problems, very much in line with existing experience with nodal methods., Assembly powers can be calculated to within 2.0% with just one mesh per assembly. (author)

  19. A variational nodal diffusion method of high accuracy; Varijaciona nodalna difuziona metoda visoke tachnosti

    Energy Technology Data Exchange (ETDEWEB)

    Tomasevic, Dj; Altiparmarkov, D [Institut za Nuklearne Nauke Boris Kidric, Belgrade (Yugoslavia)

    1988-07-01

    A variational nodal diffusion method with accurate treatment of transverse leakage shape is developed and presented in this paper. Using Legendre expansion in transverse coordinates higher order quasi-one-dimensional nodal equations are formulated. Numerical solution has been carried out using analytical solutions in alternating directions assuming Legendre expansion of the RHS term. The method has been tested against 2D and 3D IAEA benchmark problem, as well as 2D CANDU benchmark problem. The results are highly accurate. The first order approximation yields to the same order of accuracy as the standard nodal methods with quadratic leakage approximation, while the second order reaches reference solution. (author)

  20. Regional nodal relapse in surgically staged Merkel cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Hoeller, Ulrike; Mueller, Thomas; Schubert, Tina; Budach, Volker; Ghadjar, Pirus [Charite Universitaetsmedizin Berlin, Department of Radiation Oncology, Berlin (Germany); Brenner, Winfried [Charite Universitaetsmedizin Berlin, Department of Nuclear Medicine, Berlin (Germany); Kiecker, Felix [Charite Universitaetsmedizin Berlin, Department of Dermatology, Berlin (Germany); Schicke, Bernd [Tumor Center Berlin, Berlin (Germany); Haase, Oliver [Charite Universitaetsmedizin Berlin, Department of Surgery, Berlin (Germany)

    2014-10-08

    The nodal relapse pattern of surgically staged Merkel cell carcinoma (MCC) with/without elective nodal radiotherapy (RT) was studied in a single institution. A total of 51 patients with MCC, 33 % UICC stage I, 14 % II, 53 % III (4 lymph node metastases of unknown primary) were eligible. All patients had surgical staging: 23 patients sentinel node biopsy (SNB), 22 patients SNB followed by lymphadenectomy (LAD) and 6 patients LAD. In all, 94 % of the primary tumors (PT) were completely resected; 57 % of patients received RT, 51 % of known PT sites, 33 % (8/24 patients) regional RT to snN0 nodes and 68 % (17/27 patients) to pN+ nodes, mean reference dose 51.5 and 50 Gy, respectively. Mean follow-up was 6 years (range 2-14 years). A total of 22 % (11/51) patients developed regional relapses (RR); the 5-year RR rate was 27 %. In snN0 sites (stage I/II), relapse occurred in 5 of 14 nonirradiated vs. none of 8 irradiated sites (p = 0.054), resulting in a 5-year RR rate of 33 % versus 0 % (p = 0.16). The crude RR rate was lower in stage I (12 %, 2/17 patients) than for stage II (43 %, 3/7 patients). In stage III (pN+), RR appeared to be less frequent in irradiated sites (18 %, 3/14 patients) compared with nonirradiated sites (33 %, 3/10 patients, p = 0.45) with 5-year RR rates of 23 % vs. 34 %, respectively. Our data suggest that adjuvant nodal RT plays a major role even if the sentinel nodes were negative. Adjuvant RT of the lymph nodes in patients with stage IIa tumors and RT after LAD in stage III tumors is proposed and should be evaluated prospectively. (orig.) [German] Untersucht wurde das regionaere Rezidivmuster des Merkelzell-Karzinoms (MCC) nach chirurgischem Staging und stadienadaptierter Therapie. Eingeschlossen wurden 51 Patienten mit lokalisiertem MCC: 33 % hatten UICC-Stadium-I-, 14 % -II-, 53 % -III-Tumoren (davon 4 Lymphknotenmetastasen eines unbekannten Primaertumors). Alle Patienten erhielten ein chirurgisches Staging: 23 Waechterlymphknotenbiopsien (SNB

  1. Short-term variability of repolarization is superior to other repolarization parameters in the evaluation of diverse antiarrhythmic interventions in the chronic atrioventricular block dog

    NARCIS (Netherlands)

    Bossu, Alexandre; Varkevisser, Rosanne; Beekman, Henriette D.M.; Houtman, Marien J C; Van Der Heyden, Marcel A.G.; Vos, Marc A.

    2017-01-01

    Short-term variability (STV), to quantify beat-to-beat variability of repolarization, is a surrogate parameter that reliably identifies proarrhythmic risk in preclinical models. Examples include not only the use in the chronic atrioventricular block (CAVB) dog model whereby it was developed but also

  2. Expression of the BMP receptor Alk3 in the second heart field is essential for development of the dorsal mesenchymal protrusion and atrioventricular septation

    NARCIS (Netherlands)

    Briggs, Laura E.; Phelps, Aimee L.; Brown, Elizabeth; Kakarla, Jayant; Anderson, Robert H.; van den Hoff, Maurice J. B.; Wessels, Andy

    2013-01-01

    The dorsal mesenchymal protrusion (DMP) is a prong of mesenchyme derived from the second heart field (SHF) located at the venous pole of the developing heart. Recent studies have shown that perturbation of its development is associated with the pathogenesis of atrioventricular (AV) septal defect.

  3. Impact of Tricuspid Regurgitation on the Success of Atrioventricular Node Ablation for Rate Control in Patients With Atrial Fibrillation: The Node Blast Study.

    Science.gov (United States)

    Reddy, Yeruva Madhu; Gunda, Sampath; Vallakati, Ajay; Kanmanthareddy, Arun; Pillarisetti, Jayasree; Atkins, Donita; Bommana, Sudharani; Emert, Martin P; Pimentel, Rhea; Dendi, Raghuveer; Berenbom, Loren D; Lakkireddy, Dhanunjaya

    2015-09-15

    Atrioventricular node (AVN) ablation is an effective treatment for symptomatic patients with atrial arrhythmias who are refractory to rhythm and rate control strategies where optimal ventricular rate control is desired. There are limited data on the predictors of failure of AVN ablation. Our objective was to identify the predictors of failure of AVN ablation. This is an observational single-center study of consecutive patients who underwent AVN ablation in a large academic center. Baseline characteristics, procedural variables, and outcomes of AVN ablation were collected. AVN "ablation failure" was defined as resumption of AVN conduction resulting in recurrence of either rapid ventricular response or suboptimal biventricular pacing. A total of 247 patients drug refractory AF who underwent AVN ablation at our center with a mean age of 71 ± 12 years with 46% being males were included. Ablation failure was seen in 11 (4.5%) patients. There were no statistical differences between patients with "ablation failure" versus "ablation success" in any of the baseline clinical variables. Patients with moderate-to-severe tricuspid regurgitation (TR) were much more likely to have ablation failure than those with ablation success (8 [73%] vs 65 [27%]; p = 0.003). All 11 patients with ablation failure had a successful redo procedure, 9 with right and 2 with the left sided approach. On multivariate analysis, presence of moderate-to-severe TR was found to be the only predictor of failure of AVN ablation (odds ratio 9.1, confidence interval 1.99 to 42.22, p = 0.004). In conclusion, moderate-to-severe TR is a strong and independent predictor of failure of AVN ablation. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Nodal colloid goiter: clinical and morphological criteria of thyroid autonomy and progressive growth

    Directory of Open Access Journals (Sweden)

    S S Antonova

    2006-03-01

    Full Text Available Goal. To work up clinical and morphological criteria of thyroid authonomy and progressive growth in nodal colloid goiter (NCG. Methods. A group of patients with nodal euthyroid goiter (NEG (40 patients and a group of patients with nodular toxic goiter (NTG (40 patients were formed to compare clinical and morphological criteria of NCG growth to/with development of functional autonomy (FA. All patients were conducted research including physical examination, thyroid palpation, ultrasound, blood level of TSH and T4, scintigraphy, aspiration (needle biopsy, immunocytological and immunohistological reactions and statistics. In the study the method of indirect immunoperoxidase reaction with monoclonal rat/mouse antigens to Ki-67, TSH, galectin-3, Apo-test (“Dako Corporation”, “Novocastra Laboratories Ltd.” was used. Results. 1. In NEG expression of cell proliferation marker Ki-67 for certain rises pro rata to increase of proliferation degree, and in NTG grows according to FA development. 2. Apoptosis expression in NEG decreases according to degree of thyrocytes in a nodule, but in NTG falls pro rata to accumulation of thyroid FA. 3. Positive reaction for TSH in NEG tissue was found in 100%, whereas negative reaction for this receptor in NTG tissue was observed in 81% of all cases. 4. Galectin-3 was expressed in focuses of severe dysplasia of thyroid nodes tissue comparable to galectin-3 expression in the tissue of high-grade differentiated adenocarcinomas. Summary/conclusion. 1. Severe and moderate expression of Ki-67 and mild or negative immunomorphological reaction for Apo-test allows to refer such kinds of nodules to fast-growing/rapid-growing ones. 2. Reliable negative expression TSH receptor in the tissue of NCG is evidence of FA development and is an indication for a treatment of radioactive iodine or for an operation. 3. Galectin-3 probably is an early marker of malignant transformation in thyroid tissue. 4. Having conducted complex

  5. Hybrid nodal methods in the solution of the diffusion equations in X Y geometry; Metodos nodales hibridos en la solucion de las ecuaciones de difusion en geometria XY

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez M, N. [CFE, Carretera Cardel-Nautla Km. 43.5, 91680 Veracruz (Mexico); Alonso V, G.; Valle G, E. del [IPN-ESFM, 07738 Mexico D.F. (Mexico)]. e-mail: nhmiranda@mexico.com

    2003-07-01

    In 1979, Hennart and collaborators applied several schemes of classic finite element in the numerical solution of the diffusion equations in X Y geometry and stationary state. Almost two decades then, in 1996, himself and other collaborators carried out a similar work but using nodal schemes type finite element. Continuing in this last direction, in this work a group it is described a set of several Hybrid Nodal schemes denominated (NH) as well as their application to solve the diffusion equations in multigroup in stationary state and X Y geometry. The term hybrid nodal it means that such schemes interpolate not only Legendre moments of face and of cell but also the values of the scalar flow of neutrons in the four corners of each cell or element of the spatial discretization of the domain of interest. All the schemes here considered are polynomials like they were it their predecessors. Particularly, its have developed and applied eight different hybrid nodal schemes that its are very nearby related with those developed by Hennart and collaborators in the past. It is treated of schemes in those that nevertheless that decreases the number of interpolation parameters it is conserved the accurate in relation to the bi-quadratic and bi-cubic schemes. Of these eight, three were described and applied in a previous work. It is the bi-lineal classic scheme as well as the hybrid nodal schemes, bi-quadratic and bi-cubic for that here only are described the other 5 hybrid nodal schemes although they are provided numerical results for several test problems with all them. (Author)

  6. Evolução clínica a longo prazo, correlacionando a presença de bloqueios da condução intraventricular em pacientes chagásicos e não chagásicos assintomáticos Long-term follow up of asymptomatic chagasic individuals with intraventricular conduction disturbances, correlating with non-chagasic patients

    Directory of Open Access Journals (Sweden)

    João Pimenta

    1999-12-01

    Full Text Available Estudo prospectivo para avaliar o potencial evolutivo, a longo prazo, dos transtornos da condução intraventricular em indivíduos chagásicos e não chagásicos assintomáticos. Foram submetidos a estudo eletrofisiológico, por metodologia convencional, 84 indivíduos portadores de bloqueio de ramo direito ou esquerdo, 55 chagásicos e 29 não chagásicos. A idade média foi de 45 anos nos chagásicos e 63 nos não chagásicos (pThis prospective study was designed to evaluate intraventricular conduction disturbances in asymptomatic patients with Chagas' disease, and patients with primary sclerosis of the conducting system of the heart (Lev-Lenègre's disease. Eighty-four asymptomatic individuals with right- or left-bundle branch block were submitted to electrophysiological evaluation and long-term follow-up. Fifty-five had positive serologic blood tests for Chagas' disease and 29 had Lev-Lenègre's disease. Mean-age of 45 years in chagasic and 63 in non-chagasic patients (p< 0.001. There were 54 (98.2% with right-bundle branch block in chagasic and 14 (48.3% among non-chagasic patients (p <0.001. Sinus nodal and atrioventricular nodal functions presented no differences in either group. However, mean HV interval was greater in the NCH than in the CH group (p< 0.01. After a mean follow-up of 121 ± 63.75 months among chagasic and 94.97 ± 67.55 months among non-chagasic patients, total mortality was 20 (36.6% patients in chagasic and 9 (31% among non-chagasic patients (NS. Cardiac death was recorded in 17 (85% individuals among chagasic and 3 (33.3% among non-chagasic patients(p <0.05. Sudden death occurred in 10 (50% among chagasic and was not observed in non-chagasic patients (p <0.01. In conclusion: 1. Asymptomatic chagasic individuals with intraventricular conduction disturbances showed higher cardiac mortality, sudden or non-sudden death in relation to non-chagasic individuals. 2. The evaluated electrophysiological parameters were of no

  7. Molecular pathogenesis of splenic and nodal marginal zone lymphoma.

    Science.gov (United States)

    Spina, Valeria; Rossi, Davide

    Genomic studies have improved our understanding of the biological basis of splenic (SMZL) and nodal (NMZL) marginal zone lymphoma by providing a comprehensive and unbiased view of the genes/pathways that are deregulated in these diseases. Consistent with the physiological involvement of NOTCH, NF-κB, B-cell receptor and toll-like receptor signaling in mature B-cells differentiation into the marginal zone B-cells, many oncogenic mutations of genes involved in these pathways have been identified in SMZL and NMZL. Beside genetic lesions, also epigenetic and post-transcriptional modifications contribute to the deregulation of marginal zone B-cell differentiation pathways in SMZL and NMZL. This review describes the progress in understanding the molecular mechanism underlying SMZL and NMZL, including molecular and post-transcriptional modifications, and discusses how information gained from these efforts has provided new insights on potential targets of diagnostic, prognostic and therapeutic relevance in SMZL and NMZL. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Micropropagation of Calophyllum brasiliense (Cambess.) from nodal segments.

    Science.gov (United States)

    Silveira, S S; Cordeiro-Silva, R; Degenhardt-Goldbach, J; Quoirin, M

    2016-05-03

    Micropropagation of Calophyllum brasiliense Cambess. (Clusiaceae) is a way to overcome difficulties in achieving large-scale plant production, given the recalcitrant nature of the seeds, irregular fructification and absence of natural vegetative propagation of the species. Cultures were established using nodal segments 2 cm in length, obtained from 1-2 year old seedlings, maintained in a greenhouse. Mercury chloride and Plant Preservative Mixture™ were used in the surface sterilizing stage, better results being achieved with Plant Preservative Mixture™ incorporation in culture medium, at any concentration. Polyvinylpyrrolidone, activated charcoal, cysteine, ascorbic acid or citric acid were added to the culture medium to avoid oxidation. After 30 days of culture, polyvinylpirrolidone and ascorbic acid gave better results, eliminating oxidation in most explants. For shoot multiplication, benzylaminopurine was used in concentrations of 4.4 and 8.8 µM in Woody Plant Medium, resulting in an average of 4.43 and 4.68 shoots per explant, respectively, after 90 days. Indole-3-butyric acid and α-naphthalene acetic acid were used to induce root formation, reaching a maximum rooting rate of 24% with 20µM α-naphthalene acetic acid. For acclimatization. the rooted plants were transferred to Plantmax® substrate and cultured in a greenhouse, reaching 79% of survival after 30 days and 60% after one year.

  9. Relevance of regional nodal management in multimodality esophageal cancer treatment

    International Nuclear Information System (INIS)

    Wong, J.; Perez-Tamayo, C.; Takasugi, B.; Orringer, M.B.; Flint, A.; Lichter, A.S.

    1986-01-01

    A prospective study has been undertaken at the University of Michigan Hospital, where patients with distal esophageal carcinoma receive concurrent radiation therapy (3,750 cGy delivered in 15 fractions) and systemic chemotherapy (cisplatin, Velban, 5-FU), followed by blunt esophagectomy with exploration and lymph node sampling. Strict pathologic screening and handling of nodal tissue and esophagectomy specimens were analyzed. Eighteen patients with distal esophageal lesions ranging from 5 to 12 cm (average, 7 cm) detected on the initial barium swallow study have been seen to date. In three of these patients celiac axis involvement has been demonstrated on CT. All primary lesions were confirmed by biopsy. Five were found to be squamous cell carcinoma and thirteen were adenocarcinomas. One of 15 of the presently evaluable patients (5%) had microscopic involvement of a celiac node at surgery. Celiac, lesser curvature, and superior gastric nodes where all encompassed in the radiation therapy portals to the aforementioned dose. CT scan planning was done in all patients. This added volume was well tolerated by the patients without morbidity

  10. Topological Nodal Cooper Pairing in Doped Weyl Metals

    Science.gov (United States)

    Li, Yi; Haldane, F. D. M.

    2018-02-01

    We generalize the concept of Berry connection of the single-electron band structure to that of a two-particle Cooper pairing state between two Fermi surfaces with opposite Chern numbers. Because of underlying Fermi surface topology, the pairing Berry phase acquires nontrivial monopole structure. Consequently, pairing gap functions have topologically protected nodal structure as vortices in the momentum space with the total vorticity solely determined by the pair monopole charge qp. The nodes of gap function behave as the Weyl-Majorana points of the Bogoliubov-de Gennes pairing Hamiltonian. Their relation with the connection patterns of the surface modes from the Weyl band structure and the Majorana surface modes inside the pairing gap is also discussed. Under the approximation of spherical Fermi surfaces, the pairing symmetry are represented by monopole harmonic functions. The lowest possible pairing channel carries angular momentum number j =|qp|, and the corresponding gap functions are holomorphic or antiholomorphic functions on Fermi surfaces. After projected on the Fermi surfaces with nontrivial topology, all the partial-wave channels of pairing interactions acquire the monopole charge qp independent of concrete pairing mechanism.

  11. Application of the SPH method in nodal diffusion analyses of SFR cores

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, Evgeny; Fridman, Emil [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Reactor Safety; Mikityuk, K. [Paul Scherrer Institut, Villigen (Switzerland)

    2016-07-01

    The current study investigated the potential of the SPH method, applied to correct the few-group XS produced by Serpent, to further improve the accuracy of the nodal diffusion solutions. The procedure for the generation of SPH-corrected few-group XS is presented in the paper. The performance of the SPH method was tested on a large oxide SFR core from the OECD/NEA SFR benchmark. The reference SFR core was modeled with the DYN3D and PARCS nodal diffusion codes using the SPH-corrected few-group XS generated by Serpent. The nodal diffusion results obtained with and without SPH correction were compared to the reference full-core Serpent MC solution. It was demonstrated that the application of the SPH method improves the accuracy of the nodal diffusion solutions, particularly for the rodded core state.

  12. A Hybrid Interpolation Method for Geometric Nonlinear Spatial Beam Elements with Explicit Nodal Force

    Directory of Open Access Journals (Sweden)

    Huiqing Fang

    2016-01-01

    Full Text Available Based on geometrically exact beam theory, a hybrid interpolation is proposed for geometric nonlinear spatial Euler-Bernoulli beam elements. First, the Hermitian interpolation of the beam centerline was used for calculating nodal curvatures for two ends. Then, internal curvatures of the beam were interpolated with a second interpolation. At this point, C1 continuity was satisfied and nodal strain measures could be consistently derived from nodal displacement and rotation parameters. The explicit expression of nodal force without integration, as a function of global parameters, was founded by using the hybrid interpolation. Furthermore, the proposed beam element can be degenerated into linear beam element under the condition of small deformation. Objectivity of strain measures and patch tests are also discussed. Finally, four numerical examples are discussed to prove the validity and effectivity of the proposed beam element.

  13. ANOVA-HDMR structure of the higher order nodal diffusion solution

    International Nuclear Information System (INIS)

    Bokov, P. M.; Prinsloo, R. H.; Tomasevic, D. I.

    2013-01-01

    Nodal diffusion methods still represent a standard in global reactor calculations, but employ some ad-hoc approximations (such as the quadratic leakage approximation) which limit their accuracy in cases where reference quality solutions are sought. In this work we solve the nodal diffusion equations utilizing the so-called higher-order nodal methods to generate reference quality solutions and to decompose the obtained solutions via a technique known as High Dimensional Model Representation (HDMR). This representation and associated decomposition of the solution provides a new formulation of the transverse leakage term. The HDMR structure is investigated via the technique of Analysis of Variance (ANOVA), which indicates why the existing class of transversely-integrated nodal methods prove to be so successful. Furthermore, the analysis leads to a potential solution method for generating reference quality solutions at a much reduced calculational cost, by applying the ANOVA technique to the full higher order solution. (authors)

  14. Concomitant occurrence of sinus histiocytosis with massive lymphadenopathy and nodal marginal zone lymphoma.

    Science.gov (United States)

    Pang, Changlee S; Grier, David D; Beaty, Michael W

    2011-03-01

    Sinus histiocytosis with massive lymphadenopathy (SHML), also known as Rosai-Dorfman disease, is a rare self-limiting disorder of histiocytes with unknown etiology. Sinus histiocytosis with massive lymphadenopathy is most common in children and young adults and is characterized by painless lymphadenopathy. Histologically there is a proliferation of sinus histiocytes with lymphophagocytosis or emperipolesis. On rare occasions, SHML has been associated with lymphoma, usually involving different anatomic sites and developing at different times. We report a case of concomitant SHML and nodal marginal zone lymphoma involving the same lymph node without involvement of other nodal or extranodal sites. The presence of concomitant SHML within the lymph node involved by nodal marginal zone lymphoma may represent the responsiveness of SHML histiocytes to B-cell-derived cytokines in lymphoproliferative disorders. To our knowledge, this is the first description of concomitant occurrence of SHML and nodal marginal zone lymphoma.

  15. MicroRNA expression in nodal and extranodal Diffuse Large B-cell Lymphoma

    DEFF Research Database (Denmark)

    Mandrup, Charlotte; Petersen, Anders; Højfeldt, Anne Dirks

    MicroRNA expression in nodal and extranodal Diffuse Large B-cell Lymphoma   C. Mandrup1, A. Petersen1, A. D. Hoejfeldt1, H. F. Thomsen1, J. Madsen1, J. Dahlgaard1, P. Johansen2, A. Bukh1, K. Dybkaer1 and H. E Johnsen1. 1Department of Hematology, 2Pathological Institute, Aalborg Hospital, Aarhus...... University Hospital, Aalborg, Denmark Introduction: The aim of this project was to analyse microRNA (miRNA) expression in nodal and extranodal diffuse large B-cell lymphoma (DLBCL). Manifestation at diagnosis may be nodal and/or extranodal. At present, there are no known determinants for none...... of the manifestations, and no way to predict the potential progression from nodal to extranodal disease. miRNA are small regulatory RNA molecules with core function to repress/cleave sequence complementary mRNA targets. Abnormalities in miRNA genetics and expression are known to affect initiation and development...

  16. Atrioventricular valve repair in patients with functional single-ventricle physiology: impact of ventricular and valve function and morphology on survival and reintervention.

    Science.gov (United States)

    Honjo, Osami; Atlin, Cori R; Mertens, Luc; Al-Radi, Osman O; Redington, Andrew N; Caldarone, Christopher A; Van Arsdell, Glen S

    2011-08-01

    This study was to determine whether atrioventricular valve repair modifies natural history of single-ventricle patients with atrioventricular valve insufficiency and to identify factors predicting survival and reintervention. Fifty-seven (13.5%) of 422 single-ventricle patients underwent atrioventricular valve repair. Valve morphology, regurgitation mechanism, and ventricular morphology and function were analyzed for effect on survival, transplant, and reintervention with multivariate logistic and Cox regression models. Comparative analysis used case-matched controls. Atrioventricular valve was tricuspid in 67% and common in 28%. Ventricular morphology was right in 83%. Regurgitation mechanisms were prolapse (n = 24, 46%), dysplasia (n = 18, 35%), annular dilatation (n = 8, 15%), and restriction or cleft (n = 2, 4%). Postrepair insufficiency was none or trivial in 14 (26%), mild in 33 (61%), and moderate in 7 (13%). Survival in repair group was lower than in matched controls (78.9% vs 92.7% at 1 year, 68.7% vs 90.6% at 3 years, P = .015). Patients with successful repair and normal ventricular function had equivalent survival to matched controls (P = .36). Independent predictors for death or transplant included increased indexed annular size (P = .05), increased cardiopulmonary bypass time (P = .04), and decreased postrepair ventricular function (P = .01). Ventricular dilation was a time-related factor for all events, including failed repair. Survival was lower in single-ventricle patients operated on for atrioventricular valve insufficiency than in case-matched controls. Patients with little postoperative residual regurgitation and preserved ventricular function had equivalent survival to controls. Lower grade ventricular function and ventricular dilation correlated with death and repair failure, suggesting that timing of intervention may affect outcome. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All

  17. Reasons for conversion and adverse intraoperative events in Endoscopic Port Access™ atrioventricular valve surgery and minimally invasive aortic valve surgery.

    Science.gov (United States)

    van der Merwe, Johan; Van Praet, Frank; Stockman, Bernard; Degrieck, Ivan; Vermeulen, Yvette; Casselman, Filip

    2018-02-14

    This study reports the factors that contribute to sternotomy conversions (SCs) and adverse intraoperative events in minimally invasive aortic valve surgery (MI-AVS) and minimally invasive Endoscopic Port Access™ atrioventricular valve surgery (MI-PAS). In total, 3780 consecutive patients with either aortic valve disease or atrioventricular valve disease underwent minimally invasive valve surgery (MIVS) at our institution between 1 February 1997 and 31 March 2016. MI-AVS was performed in 908 patients (mean age 69.2 ± 11.3 years, 45.2% women, 6.2% redo cardiac surgery) and MI-PAS in 2872 patients (mean age 64.1 ± 13.3 years, 46.7% women, 12.2% redo cardiac surgery). A cumulative total of 4415 MIVS procedures (MI-AVS = 908, MI-PAS = 3507) included 1537 valve replacements (MI-AVS = 896, MI-PAS = 641) and 2878 isolated or combined valve repairs (MI-AVS = 12, MI-PAS = 2866). SC was required in 3.0% (n = 114 of 3780) of MIVS patients, which occurred in 3.1% (n = 28 of 908) of MI-AVS patients and 3.0% (n = 86 of 2872) of MI-PAS patients, respectively. Reasons for SC in MI-AVS included inadequate visualization (n = 4, 0.4%) and arterial cannulation difficulty (n = 7, 0.8%). For MI-PAS, SC was required in 54 (2.5%) isolated mitral valve procedures (n = 2183). Factors that contributed to SC in MI-PAS included lung adhesions (n = 35, 1.2%), inadequate visualization (n = 2, 0.1%), ventricular bleeding (n = 3, 0.1%) and atrioventricular dehiscence (n = 5, 0.2%). Neurological deficit occurred in 1 (0.1%) and 3 (3.5%) MI-AVS and MI-PAS conversions, respectively. No operative or 30-day mortalities were observed in MI-AVS conversions (n = 28). The 30-day mortality associated with SC in MI-PAS (n = 86) was 10.5% (n = 9). MIVS is increasingly being recognized as the 'gold-standard' for surgical valve interventions in the context of rapidly expanding catheter-based technology and increasing

  18. Análise dos fatores de risco na correção cirúrgica do defeito septal atrioventricular de forma total Risk factors analysis in the surgical repair of complete atrioventricular septal defect

    Directory of Open Access Journals (Sweden)

    Eduardo Keller Saadi

    1993-06-01

    Full Text Available Pacientes com defeito septal atrioventricular de forma total (DSAVT freqüentemente apresentam insuficiência cardíaca intratável e hipertensão arterial pulmonar nos primeiros meses de vida, e apenas uma minoria sobrevive sem tratamento cirúrgico precoce. Por essa razão, indica-se a correção definitiva para alterar favoravelmente a história natural da doença. Entretanto, vários fatores são responsáveis pela alta mortalidade cirúrgica. O presente trabalho estuda a experiência na correção cirúrgica do DSAVT com o objetivo de identificar alguns fatores de risco estatisticamente significativos para a ocorrência de morte operatória. Analisaram-se, retrospectivamente, 52 pacientes submetidos, entre janeiro de 1974 e dezembro de 1990, a cirurgia definitiva para correção de DSAVT no Royal Brompton and National Heart and Lung Institute, sendo estudadas as seguintes variáveis: idade, peso, sexo, ano da operação, presença de síndrome de Down, grau de regurgitação da valva AV, bandagem prévia do tronco pulmonar, presença de anomalias associadas, pressão sistólica pulmonar, duplo orifício mitral, classificação do defeito segundo Rastelli, emprego de parada circulatória e técnica de correção (1 x 2 retalhos. Todos os fatores foram avaliados isoladamente, mediante a análise univariada. Para determinar quais os fatores que, independentemente da ação de outros, contribuíram significativamente para maior mortalidade cirúrgica, foi utilizada a análise multivariada com regressão logística. A análise multivariada demonstrou que o baixo peso na época da operação e a técnica de correção com um retalho aumentam significativamente a mortalidade cirúrgica.Patients with complete atrioventricular septal defects (CAVSD frequently present with severe heart failure which cannot be controllable medically and pulmonary hypertension in infancy. Just a small number survives without early surgical treatment. For this reason

  19. Exclusion of elective nodal irradiation is associated with minimal elective nodal failure in non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Cox James D

    2009-01-01

    Full Text Available Abstract Background Controversy still exists regarding the long-term outcome of patients whose uninvolved lymph node stations are not prophylactically irradiated for non-small cell lung cancer (NSCLC treated with definitive radiotherapy. To determine the frequency of elective nodal failure (ENF and in-field failure (IFF, we examined a large cohort of patients with NSCLC staged with positron emission tomography (PET/computed tomography (CT and treated with 3-dimensional conformal radiotherapy (3D-CRT that excluded uninvolved lymph node stations. Methods We retrospectively reviewed the records of 115 patients with non-small cell lung cancer treated at our institution with definitive radiation therapy with or without concurrent chemotherapy (CHT. All patients were treated with 3D-CRT, including nodal regions determined by CT or PET to be disease involved. Concurrent platinum-based CHT was administered for locally advanced disease. Patients were analyzed in follow-up for survival, local regional recurrence, and distant metastases (DM. Results The median follow-up time was 18 months (3 to 44 months among all patients and 27 months (6 to 44 months among survivors. The median overall survival, 2-year actuarial overall survival and disease-free survival were 19 months, 38%, and 28%, respectively. The majority of patients died from DM, the overall rate of which was 36%. Of the 31 patients with local regional failure, 26 (22.6% had IFF, 5 (4.3% had ENF and 2 (1.7% had isolated ENF. For 88 patients with stage IIIA/B, the frequencies of IFF, any ENF, isolated ENF, and DM were 23 (26%, 3 (9%, 1 (1.1% and 36 (40.9%, respectively. The comparable rates for the 22 patients with early stage node-negative disease (stage IA/IB were 3 (13.6%, 1(4.5%, 0 (0%, and 5 (22.7%, respectively. Conclusion We observed only a 4.3% recurrence of any ENF and a 1.7% recurrence of isolated ENF in patients with NSCLC treated with definitive 3D-CRT without prophylactic irradiation of

  20. Exclusion of elective nodal irradiation is associated with minimal elective nodal failure in non-small cell lung cancer

    International Nuclear Information System (INIS)

    Sulman, Erik P; Komaki, Ritsuko; Klopp, Ann H; Cox, James D; Chang, Joe Y

    2009-01-01

    Controversy still exists regarding the long-term outcome of patients whose uninvolved lymph node stations are not prophylactically irradiated for non-small cell lung cancer (NSCLC) treated with definitive radiotherapy. To determine the frequency of elective nodal failure (ENF) and in-field failure (IFF), we examined a large cohort of patients with NSCLC staged with positron emission tomography (PET)/computed tomography (CT) and treated with 3-dimensional conformal radiotherapy (3D-CRT) that excluded uninvolved lymph node stations. We retrospectively reviewed the records of 115 patients with non-small cell lung cancer treated at our institution with definitive radiation therapy with or without concurrent chemotherapy (CHT). All patients were treated with 3D-CRT, including nodal regions determined by CT or PET to be disease involved. Concurrent platinum-based CHT was administered for locally advanced disease. Patients were analyzed in follow-up for survival, local regional recurrence, and distant metastases (DM). The median follow-up time was 18 months (3 to 44 months) among all patients and 27 months (6 to 44 months) among survivors. The median overall survival, 2-year actuarial overall survival and disease-free survival were 19 months, 38%, and 28%, respectively. The majority of patients died from DM, the overall rate of which was 36%. Of the 31 patients with local regional failure, 26 (22.6%) had IFF, 5 (4.3%) had ENF and 2 (1.7%) had isolated ENF. For 88 patients with stage IIIA/B, the frequencies of IFF, any ENF, isolated ENF, and DM were 23 (26%), 3 (9%), 1 (1.1%) and 36 (40.9%), respectively. The comparable rates for the 22 patients with early stage node-negative disease (stage IA/IB) were 3 (13.6%), 1(4.5%), 0 (0%), and 5 (22.7%), respectively. We observed only a 4.3% recurrence of any ENF and a 1.7% recurrence of isolated ENF in patients with NSCLC treated with definitive 3D-CRT without prophylactic irradiation of uninvolved lymph node stations. Thus

  1. Intra nodal reconstruction of the numerical solution generated by the spectro nodal constant for Sn problems of eigenvalues in two-dimensional rectangular geometry

    International Nuclear Information System (INIS)

    Menezes, Welton Alves de

    2009-01-01

    In this dissertation the spectral nodal method SD-SGF-CN, cf. spectral diamond - spectral Green's function - constant nodal, is used to determine the angular fluxes averaged along the edges of the homogenized nodes in heterogeneous domains. Using these results, we developed an algorithm for the reconstruction of the node-edge average angular fluxes within the nodes of the spatial grid set up on the domain, since more localized numerical solutions are not generated by coarse-mesh numerical methods. Numerical results are presented to illustrate the accuracy of the algorithm we offer. (author)

  2. Analysis of temperature distribution in a heat conducting fiber with ...

    African Journals Online (AJOL)

    The temperature distribution in a heat conducting fiber is computed using the Galerkin Finite Element Method in the present study. The weak form of the governing differential equation is obtained and nodal temperatures for linear and quadratic interpolation functions for different mesh densities are calculated for Neumann ...

  3. Laboratory tests of three Z‐Land Fairfield Nodal 5‐Hz, three‐component sensors

    Science.gov (United States)

    Ringler, Adam; Anthony, Robert E.; Karplus, M.S; Holland, Austin; Wilson, David

    2018-01-01

    We conduct a number of laboratory tests at the Albuquerque Seismological Laboratory to verify the self‐noise and fidelity in which 3 three‐component Fairfield Nodal Z‐Land, Generation 2, 5‐Hz sensors are able to record seismic signals. In addition to the incoherent self‐noise of the sensors, we estimate the sensitivity of the units in digital volts/m/s, the damping, and the free period. These three parameters allow us to completely characterize the response of the instruments. We find that the responses of all components match a mean‐derived response to within 5% of amplitude and 0.03 radians in phase. This close agreement suggests that for most applications a nominal response is suitable. We also checked the timing of the units as compared to a Quanterra Q330HR and found good agreement up to 200samples/s . Finally, we compared the results of our noise tests on these sensors to a couple of nodal sensors recently deployed at the Community Wavefield Demonstration Experiment in north‐central Oklahoma and found that local site noise and not the sensor self‐noise is a fundamental limiter in the resolution of these deployed sensors at frequencies above ∼0.1Hz .

  4. Characterization of nodal/TGF-lefty signaling pathway gene variants for possible roles in congenital heart diseases.

    Directory of Open Access Journals (Sweden)

    Xia Deng

    Full Text Available BACKGROUND: Nodal/TGF-Lefty signaling pathway has important effects at early stages of differentiation of human embryonic stem cells in directing them to differentiate into different embryonic lineages. LEFTY, one of transforming growth factors in the Nodal/TGF-Lefty signaling pathway, plays an important role in the development of heart. The aim of this work was to find evidence on whether Lefty variations are associated with congenital heart diseases (CHD. METHODS: We sequenced the Lefty gene for 230 Chinese Han CHD patients and evaluated SNPs rs2295418, rs360057 and g.G169A, which are located within the translated regions of the genes. The statistical analyses were conducted using Chi-Square Tests as implemented in SPSS (version 13.0. The Hardy-Weinberg equilibrium test of the population was carried out using online software OEGE, and multiple-sequence alignments of LEFTY proteins were carried out using the Vector NTI software. RESULTS: Two heterozygous variants in Lefty1 gene, g.G169A and g.A1035C, and one heterozygous variant in Lefty2 gene, g.C925A, were identified. Statistical analyses showed that the rs2295418 (g.C925A variant in Lefty2 gene was obviously associated with the risk of CHD (P value = 0.0160.05. CONCLUSIONS: The SNP rs2295418 in the Lefty2 gene is associated with CHD in Chinese Han populations.

  5. A study of the literature on nodal methods in reactor physics calculations

    International Nuclear Information System (INIS)

    Van de Wetering, T.F.H.

    1993-01-01

    During the last few decades several calculation methods have been developed for the three-dimensional analysis of a reactor core. A literature survey was carried out to gain insights in the starting points and method of operation of the advanced nodal methods. These methods are applied in reactor core analyses of large nuclear power reactors, because of their high computing speed. The so-called Nodal-Expansion method is described in detail

  6. Excitation model of pacemaker cardiomyocytes of cardiac conduction system

    Science.gov (United States)

    Grigoriev, M.; Babich, L.

    2015-11-01

    Myocardium includes typical and atypical cardiomyocytes - pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation - heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system.

  7. Cilia are required for asymmetric nodal induction in the sea urchin embryo.

    Science.gov (United States)

    Tisler, Matthias; Wetzel, Franziska; Mantino, Sabrina; Kremnyov, Stanislav; Thumberger, Thomas; Schweickert, Axel; Blum, Martin; Vick, Philipp

    2016-08-23

    Left-right (LR) organ asymmetries are a common feature of metazoan animals. In many cases, laterality is established by a conserved asymmetric Nodal signaling cascade during embryogenesis. In most vertebrates, asymmetric nodal induction results from a cilia-driven leftward fluid flow at the left-right organizer (LRO), a ciliated epithelium present during gastrula/neurula stages. Conservation of LRO and flow beyond the vertebrates has not been reported yet. Here we study sea urchin embryos, which use nodal to establish larval LR asymmetry as well. Cilia were found in the archenteron of embryos undergoing gastrulation. Expression of foxj1 and dnah9 suggested that archenteron cilia were motile. Cilia were polarized to the posterior pole of cells, a prerequisite of directed flow. High-speed videography revealed rotating cilia in the archenteron slightly before asymmetric nodal induction. Removal of cilia through brief high salt treatments resulted in aberrant patterns of nodal expression. Our data demonstrate that cilia - like in vertebrates - are required for asymmetric nodal induction in sea urchin embryos. Based on these results we argue that the anterior archenteron represents a bona fide LRO and propose that cilia-based symmetry breakage is a synapomorphy of the deuterostomes.

  8. Solution and Study of the Two-Dimensional Nodal Neutron Transport Equation

    International Nuclear Information System (INIS)

    Panta Pazos, Ruben; Biasotto Hauser, Eliete; Tullio de Vilhena, Marco

    2002-01-01

    In the last decade Vilhena and coworkers reported an analytical solution to the two-dimensional nodal discrete-ordinates approximations of the neutron transport equation in a convex domain. The key feature of these works was the application of the combined collocation method of the angular variable and nodal approach in the spatial variables. By nodal approach we mean the transverse integration of the SN equations. This procedure leads to a set of one-dimensional S N equations for the average angular fluxes in the variables x and y. These equations were solved by the old version of the LTS N method, which consists in the application of the Laplace transform to the set of nodal S N equations and solution of the resulting linear system by symbolic computation. It is important to recall that this procedure allow us to increase N the order of S N up to 16. To overcome this drawback we step forward performing a spectral painstaking analysis of the nodal S N equations for N up to 16 and we begin the convergence of the S N nodal equations defining an error for the angular flux and estimating the error in terms of the truncation error of the quadrature approximations of the integral term. Furthermore, we compare numerical results of this approach with those of other techniques used to solve the two-dimensional discrete approximations of the neutron transport equation. (authors)

  9. Advances in the solution of three-dimensional nodal neutron transport equation

    International Nuclear Information System (INIS)

    Pazos, Ruben Panta; Hauser, Eliete Biasotto; Vilhena, Marco Tullio de

    2003-01-01

    In this paper we study the three-dimensional nodal discrete-ordinates approximations of neutron transport equation in a convex domain with piecewise smooth boundaries. We use the combined collocation method of the angular variables and nodal approach for the spatial variables. By nodal approach we mean the iterated transverse integration of the S N equations. This procedure leads to the set of one-dimensional averages angular fluxes in each spatial variable. The resulting system of equations is solved with the LTS N method, first applying the Laplace transform to the set of the nodal S N equations and then obtaining the solution by symbolic computation. We include the LTS N method by diagonalization to solve the nodal neutron transport equation and then we outline the convergence of these nodal-LTS N approximations with the help of a norm associated to the quadrature formula used to approximate the integral term of the neutron transport equation. We give numerical results obtained with an algebraic computer system (for N up to 8) and with a code for higher values of N. We compare our results for the geometry of a box with a source in a vertex and a leakage zone in the opposite with others techniques used in this problem. (author)

  10. The implementation of a simplified spherical harmonics semi-analytic nodal method in PANTHER

    International Nuclear Information System (INIS)

    Hall, S.K.; Eaton, M.D.; Knight, M.P.

    2013-01-01

    Highlights: ► An SP N nodal method is proposed. ► Consistent CMFD derived and tested. ► Mark vacuum boundary conditions applied. ► Benchmarked against other diffusions and transport codes. - Abstract: In this paper an SP N nodal method is proposed which can utilise existing multi-group neutron diffusion solvers to obtain the solution. The semi-analytic nodal method is used in conjunction with a coarse mesh finite difference (CMFD) scheme to solve the resulting set of equations. This is compared against various nuclear benchmarks to show that the method is capable of computing an accurate solution for practical cases. A few different CMFD formulations are implemented and their performance compared. It is found that the effective diffusion coefficent (EDC) can provide additional stability and require less power iterations on a coarse mesh. A re-arrangement of the EDC is proposed that allows the iteration matrix to be computed at the beginning of a calculation. Successive nodal updates only modify the source term unlike existing CMFD methods which update the iteration matrix. A set of Mark vacuum boundary conditions are also derived which can be applied to the SP N nodal method extending its validity. This is possible due to a similarity transformation of the angular coupling matrix, which is used when applying the nodal method. It is found that the Marshak vacuum condition can also be derived, but would require the significant modification of existing neutron diffusion codes to implement it

  11. Multiarea Transmission Cost Allocation in Large Power Systems Using the Nodal Pricing Control Approach

    Directory of Open Access Journals (Sweden)

    M. Ghayeni

    2010-12-01

    Full Text Available This paper proposes an algorithm for transmission cost allocation (TCA in a large power system based on nodal pricing approach using the multi-area scheme. The nodal pricing approach is introduced to allocate the transmission costs by the control of nodal prices in a single area network. As the number of equations is dependent on the number of buses and generators, this method will be very time consuming for large power systems. To solve this problem, the present paper proposes a new algorithm based on multi-area approach for regulating the nodal prices, so that the simulation time is greatly reduced and therefore the TCA problem with nodal pricing approach will be applicable for large power systems. In addition, in this method the transmission costs are allocated to users more equitable. Since the higher transmission costs in an area having a higher reliability are paid only by users of that area in contrast with the single area method, in which these costs are allocated to all users regardless of their locations. The proposed method is implemented on the IEEE 118 bus test system which comprises three areas. Results show that with application of multi-area approach, the simulation time is greatly reduced and the transmission costs are also allocated to users with less variation in new nodal prices with respect to the single area approach.

  12. A quasi-static polynomial nodal method for nuclear reactor analysis

    International Nuclear Information System (INIS)

    Gehin, J.C.

    1992-09-01

    Modern nodal methods are currently available which can accurately and efficiently solve the static and transient neutron diffusion equations. Most of the methods, however, are limited to two energy groups for practical application. The objective of this research is the development of a static and transient, multidimensional nodal method which allows more than two energy groups and uses a non-linear iterative method for efficient solution of the nodal equations. For both the static and transient methods, finite-difference equations which are corrected by the use of discontinuity factors are derived. The discontinuity factors are computed from a polynomial nodal method using a non-linear iteration technique. The polynomial nodal method is based upon a quartic approximation and utilizes a quadratic transverse-leakage approximation. The solution of the time-dependent equations is performed by the use of a quasi-static method in which the node-averaged fluxes are factored into shape and amplitude functions. The application of the quasi-static polynomial method to several benchmark problems demonstrates that the accuracy is consistent with that of other nodal methods. The use of the quasi-static method is shown to substantially reduce the computation time over the traditional fully-implicit time-integration method. Problems involving thermal-hydraulic feedback are accurately, and efficiently, solved by performing several reactivity/thermal-hydraulic updates per shape calculation

  13. A quasi-static polynomial nodal method for nuclear reactor analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gehin, Jess C. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1992-09-01

    Modern nodal methods are currently available which can accurately and efficiently solve the static and transient neutron diffusion equations. Most of the methods, however, are limited to two energy groups for practical application. The objective of this research is the development of a static and transient, multidimensional nodal method which allows more than two energy groups and uses a non-linear iterative method for efficient solution of the nodal equations. For both the static and transient methods, finite-difference equations which are corrected by the use of discontinuity factors are derived. The discontinuity factors are computed from a polynomial nodal method using a non-linear iteration technique. The polynomial nodal method is based upon a quartic approximation and utilizes a quadratic transverse-leakage approximation. The solution of the time-dependent equations is performed by the use of a quasi-static method in which the node-averaged fluxes are factored into shape and amplitude functions. The application of the quasi-static polynomial method to several benchmark problems demonstrates that the accuracy is consistent with that of other nodal methods. The use of the quasi-static method is shown to substantially reduce the computation time over the traditional fully-implicit time-integration method. Problems involving thermal-hydraulic feedback are accurately, and efficiently, solved by performing several reactivity/thermal-hydraulic updates per shape calculation.

  14. Topological crystalline superconductivity and second-order topological superconductivity in nodal-loop materials

    Science.gov (United States)

    Shapourian, Hassan; Wang, Yuxuan; Ryu, Shinsei

    2018-03-01

    We study the intrinsic fully gapped odd-parity superconducting order in doped nodal-loop materials with a torus-shaped Fermi surface. We show that the mirror symmetry, which protects the nodal loop in the normal state, also protects the superconducting state as a topological crystalline superconductor. As a result, the surfaces preserving the mirror symmetry host gapless Majorana cones. Moreover, for a Weyl-loop system (twofold degenerate at the nodal loop), the surfaces that break the mirror symmetry (those parallel to the bulk nodal loop) contribute a Chern (winding) number to the quasi-two-dimensional system in a slab geometry, which leads to a quantized thermal Hall effect and a single Majorana zero mode bound at a vortex line penetrating the system. This Chern number can be viewed as a higher-order topological invariant, which supports hinge modes in a cubic sample when mirror symmetry is broken. For a Dirac-loop system (fourfold degenerate at the nodal loop), the fully gapped odd-parity state can be either time-reversal symmetry-breaking or symmetric, similar to the A and B phases of 3He. In a slab geometry, the A phase has a Chern number two, while the B phase carries a nontrivial Z2 invariant. We discuss the experimental relevance of our results to nodal-loop materials such as CaAgAs.

  15. Altered left ventricular vortex ring formation by 4-dimensional flow magnetic resonance imaging after repair of atrioventricular septal defects.

    Science.gov (United States)

    Calkoen, Emmeline E; Elbaz, Mohammed S M; Westenberg, Jos J M; Kroft, Lucia J M; Hazekamp, Mark G; Roest, Arno A W; van der Geest, Rob J

    2015-11-01

    During normal left ventricular (LV) filling, a vortex ring structure is formed distal to the left atrioventricular valve (LAVV). Vortex structures contribute to efficient flow organization. We aimed to investigate whether LAVV abnormality in patients with a corrected atrioventricular septal defect (AVSD) has an impact on vortex ring formation. Whole-heart 4D flow MRI was performed in 32 patients (age: 26 ± 12 years), and 30 healthy subjects (age: 25 ± 14 years). Vortex ring cores were detected at peak early (E-peak) and peak late filling (A-peak). When present, the 3-dimensional position and orientation of the vortex ring was defined, and the circularity index was calculated. Through-plane flow over the LAVV, and the vortex formation time (VFT), were quantified to analyze the relationship of vortex flow with the inflow jet. Absence of a vortex ring during E-peak (healthy subjects 0%, vs patients 19%; P = .015), and A-peak (healthy subjects 10% vs patients 44%; P = .008) was more frequent in patients. In 4 patients, this was accompanied by a high VFT (5.1-7.8 vs 2.4 ± 0.6 in healthy subjects), and in another 2 patients with abnormal valve anatomy. In patients compared with controls, the vortex cores had a more-anterior and apical position, closer to the ventricular wall, with a more-elliptical shape and oblique orientation. The shape of the vortex core closely resembled the valve shape, and its orientation was related to the LV inflow direction. This study quantitatively shows the influence of abnormal LAVV and LV inflow on 3D vortex ring formation during LV inflow in patients with corrected AVSD, compared with healthy subjects. Copyright © 2015. Published by Elsevier Inc.

  16. Modification of the ANC Nodal Code for analysis of PWR assembly bow

    International Nuclear Information System (INIS)

    Franceschini, Fausto; Fetterman, Robert J.; Little, David C.

    2008-01-01

    Refueling operations at certain PWR cores have revealed fuel assemblies with assembly bow that was higher than expected. As the fuel assemblies bow, the gaps between assemblies change from the uniform nominal configuration. This causes a change in the water volume which affects neutron moderation and thereby power distribution, fuel depletion history, rod internal pressure, etc., with non-trivial impacts on the safety analysis. Westinghouse has developed a new methodology for incorporation of assembly bow in its reload safety analysis package. As part of the new process, the standard Westinghouse reactor physics tool for core analysis, the Advanced Nodal Code ANC, has been modified. The modified ANC, ANCGAP, enables explicit treatment of three-dimensional gap distributions in its neutronic calculations; its accuracy is similar to that of the standard ANC, as demonstrated through an extensive benchmark campaign conducted over a variety of fuel compositions and challenging gap configurations. These features make ANCGAP a crucial tool in the Westinghouse assembly bow package. (authors)

  17. Modification of the ANC Nodal Code for analysis of PWR assembly bow

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Fausto; Fetterman, Robert J.; Little, David C. [Westinghouse Electric Company LLC, Pittsburgh PA (United States)

    2008-07-01

    Refueling operations at certain PWR cores have revealed fuel assemblies with assembly bow that was higher than expected. As the fuel assemblies bow, the gaps between assemblies change from the uniform nominal configuration. This causes a change in the water volume which affects neutron moderation and thereby power distribution, fuel depletion history, rod internal pressure, etc., with non-trivial impacts on the safety analysis. Westinghouse has developed a new methodology for incorporation of assembly bow in its reload safety analysis package. As part of the new process, the standard Westinghouse reactor physics tool for core analysis, the Advanced Nodal Code ANC, has been modified. The modified ANC, ANCGAP, enables explicit treatment of three-dimensional gap distributions in its neutronic calculations; its accuracy is similar to that of the standard ANC, as demonstrated through an extensive benchmark campaign conducted over a variety of fuel compositions and challenging gap configurations. These features make ANCGAP a crucial tool in the Westinghouse assembly bow package. (authors)

  18. TGF-β promotes glioma cell growth via activating Nodal expression through Smad and ERK1/2 pathways

    International Nuclear Information System (INIS)

    Sun, Jing; Liu, Su-zhi; Lin, Yan; Cao, Xiao-pan; Liu, Jia-ming

    2014-01-01

    Highlights: •TGF-β promoted Nodal expression in glioma cells. •TGF-β promoted Nodal expression via activating Smad and ERK1/2 pathways. •TGF-β promotes glioma cell growth via activating Nodal expression. -- Abstract: While there were certain studies focusing on the mechanism of TGF-β promoting the growth of glioma cells, the present work revealed another novel mechanism that TGF-β may promote glioma cell growth via enhancing Nodal expression. Our results showed that Nodal expression was significantly upregulated in glioma cells when TGF-β was added, whereas the TGF-β-induced Nodal expression was evidently inhibited by transfection Smad2 or Smad3 siRNAs, and the suppression was especially significant when the Smad3 was downregulated. Another, the attenuation of TGF-β-induced Nodal expression was observed with blockade of the ERK1/2 pathway also. Further detection of the proliferation, apoptosis, and invasion of glioma cells indicated that Nodal overexpression promoted the proliferation and invasion of tumor cells and inhibited their apoptosis, resembling the effect of TGF-β addition. Downregulation of Nodal expression via transfection Nodal-specific siRNA in the presence of TGF-β weakened the promoting effect of the latter on glioma cells growth, and transfecting Nodal siRNA alone in the absence of exogenous TGF-β more profoundly inhibited the growth of glioma cells. These results demonstrated that while both TGF-β and Nodal promoted glioma cells growth, the former might exert such effect by enhancing Nodal expression, which may form a new target for glioma therapy

  19. The orphan receptor ALK7 and the Activin receptor ALK4 mediate signaling by Nodal proteins during vertebrate development

    Science.gov (United States)

    Reissmann, Eva; Jörnvall, Henrik; Blokzijl, Andries; Andersson, Olov; Chang, Chenbei; Minchiotti, Gabriella; Persico, M. Graziella; Ibáñez, Carlos F.; Brivanlou, Ali H.

    2001-01-01

    Nodal proteins have crucial roles in mesendoderm formation and left–right patterning during vertebrate development. The molecular mechanisms of signal transduction by Nodal and related ligands, however, are not fully understood. In this paper, we present biochemical and functional evidence that the orphan type I serine/threonine kinase receptor ALK7 acts as a receptor for mouse Nodal and Xenopus Nodal-related 1 (Xnr1). Receptor reconstitution experiments indicate that ALK7 collaborates with ActRIIB to confer responsiveness to Xnr1 and Nodal. Both receptors can independently bind Xnr1. In addition, Cripto, an extracellular protein genetically implicated in Nodal signaling, can independently interact with both Xnr1 and ALK7, and its expression greatly enhances the ability of ALK7 and ActRIIB to respond to Nodal ligands. The Activin receptor ALK4 is also able to mediate Nodal signaling but only in the presence of Cripto, with which it can also interact directly. A constitutively activated form of ALK7 mimics the mesendoderm-inducing activity of Xnr1 in Xenopus embryos, whereas a dominant-negative ALK7 specifically blocks the activities of Nodal and Xnr1 but has little effect on other related ligands. In contrast, a dominant-negative ALK4 blocks all mesoderm-inducing ligands tested, including Nodal, Xnr1, Xnr2, Xnr4, and Activin. In agreement with a role in Nodal signaling, ALK7 mRNA is localized to the ectodermal and organizer regions of Xenopus gastrula embryos and is expressed during early stages of mouse embryonic development. Therefore, our results indicate that both ALK4 and ALK7 can mediate signal transduction by Nodal proteins, although ALK7 appears to be a receptor more specifically dedicated to Nodal signaling. PMID:11485994

  20. Results of a Phase 2 Study Examining the Effects of Omitting Elective Neck Irradiation to Nodal Levels IV and V{sub b} in Patients With N{sub 0-1} Nasopharyngeal Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian-zhou [Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong (China); Le, Quynh-Thu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Han, Fei; Lu, Li-Xia; Huang, Shao-Min; Lin, Cheng-Guang; Deng, Xiao-Wu; Cui, Nian-Ji [State Key Laboratory of Oncology in South China, Department of Radiation Oncology, Cancer Center of Sun Yat-Sen University, Guangzhou, Guangdong (China); Zhao, Chong, E-mail: gzzhaochong@hotmail.com [State Key Laboratory of Oncology in South China, Department of Radiation Oncology, Cancer Center of Sun Yat-Sen University, Guangzhou, Guangdong (China)

    2013-03-15

    Purpose: To evaluate the patterns of nodal failure and toxicity in clinically negative necks of N{sub 0-1} nasopharyngeal carcinoma (NPC) patients who were treated with intensity modulated radiation therapy (IMRT) but did not receive elective neck irradiation (ENI) to level IV and V{sub b} nodes. Methods and Materials: We conducted a phase 2 prospective study in N{sub 0-1} NPC patients treated with IMRT. ENI included the retropharyngeal nodes and levels II to V{sub a} but omitted levels IV and V{sub b} in clinically negative necks. Patterns of nodal failure, regional control (RC), and late toxicity were evaluated. Results: Between 2001 and 2008, a total of 212 patients (128 N{sub 0} and 84 N{sub 1}) were enrolled in the study. Seven patients (4 in-field and 3 out-of-field) developed nodal failure. One patient (0.5%) developed nodal failure at level V{sub b}, but no patients developed nodal failure at level IV. The 5-year RC rates of the entire group, N{sub 0} patients and N{sub 1} patients were 95.6%, 98.2%, and 91.3%, respectively. Fifteen patients (7.1%) developed distant metastases. The 5-year distant failure-free survival (DFFS) and overall survival (OS) rates were 91.4% and 89.8%, respectively. The rates of grade 2 or greater skin dystrophy, subcutaneous fibrosis and xerostomia were 6.2%, 16.6%, and 17.9%, respectively. Conclusions: The rate of out-of-field nodal failure when omitting ENI to levels IV and V{sub b} in clinically negative necks of patients with N{sub 0-1} NPC was extremely low; therefore, a further phase 3 study is warranted.

  1. Group-decoupled multi-group pin power reconstruction utilizing nodal solution 1D flux profiles

    International Nuclear Information System (INIS)

    Yu, Lulin; Lu, Dong; Zhang, Shaohong; Wang, Dezhong

    2014-01-01

    Highlights: • A direct fitting multi-group pin power reconstruction method is developed. • The 1D nodal solution flux profiles are used as the condition. • The least square fit problem is analytically solved. • A slowing down source improvement method is applied. • The method shows good accuracy for even challenging problems. - Abstract: A group-decoupled direct fitting method is developed for multi-group pin power reconstruction, which avoids both the complication of obtaining 2D analytic multi-group flux solution and any group-coupled iteration. A unique feature of the method is that in addition to nodal volume and surface average fluxes and corner fluxes, transversely-integrated 1D nodal solution flux profiles are also used as the condition to determine the 2D intra-nodal flux distribution. For each energy group, a two-dimensional expansion with a nine-term polynomial and eight hyperbolic functions is used to perform a constrained least square fit to the 1D intra-nodal flux solution profiles. The constraints are on the conservation of nodal volume and surface average fluxes and corner fluxes. Instead of solving the constrained least square fit problem numerically, we solve it analytically by fully utilizing the symmetry property of the expansion functions. Each of the 17 unknown expansion coefficients is expressed in terms of nodal volume and surface average fluxes, corner fluxes and transversely-integrated flux values. To determine the unknown corner fluxes, a set of linear algebraic equations involving corner fluxes is established via using the current conservation condition on all corners. Moreover, an optional slowing down source improvement method is also developed to further enhance the accuracy of the reconstructed flux distribution if needed. Two test examples are shown with very good results. One is a four-group BWR mini-core problem with all control blades inserted and the other is the seven-group OECD NEA MOX benchmark, C5G7

  2. Churchill regulates cell movement and mesoderm specification by repressing Nodal signaling

    Directory of Open Access Journals (Sweden)

    Mentzer Laura

    2007-11-01

    Full Text Available Abstract Background Cell movements are essential to the determination of cell fates during development. The zinc-finger transcription factor, Churchill (ChCh has been proposed to regulate cell fate by regulating cell movements during gastrulation in the chick. However, the mechanism of action of ChCh is not understood. Results We demonstrate that ChCh acts to repress the response to Nodal-related signals in zebrafish. When ChCh function is abrogated the expression of mesodermal markers is enhanced while ectodermal markers are expressed at decreased levels. In cell transplant assays, we observed that ChCh-deficient cells are more motile than wild-type cells. When placed in wild-type hosts, ChCh-deficient cells often leave the epiblast, migrate to the germ ring and are later found in mesodermal structures. We demonstrate that both movement of ChCh-compromised cells to the germ ring and acquisition of mesodermal character depend on the ability of the donor cells to respond to Nodal signals. Blocking Nodal signaling in the donor cells at the levels of Oep, Alk receptors or Fast1 inhibited migration to the germ ring and mesodermal fate change in the donor cells. We also detect additional unusual movements of transplanted ChCh-deficient cells which suggests that movement and acquisition of mesodermal character can be uncoupled. Finally, we demonstrate that ChCh is required to limit the transcriptional response to Nodal. Conclusion These data establish a broad role for ChCh in regulating both cell movement and Nodal signaling during early zebrafish development. We show that chch is required to limit mesodermal gene expression, inhibit Nodal-dependant movement of presumptive ectodermal cells and repress the transcriptional response to Nodal signaling. These findings reveal a dynamic role for chch in regulating cell movement and fate during early development.

  3. Patterns of failure after the reduced volume approach for elective nodal irradiation in nasopharyngeal carcinoma.

    Science.gov (United States)

    Seol, Ki Ho; Lee, Jeong Eun

    2016-03-01

    To evaluate the patterns of nodal failure after radiotherapy (RT) with the reduced volume approach for elective neck nodal irradiation (ENI) in nasopharyngeal carcinoma (NPC). Fifty-six NPC patients who underwent definitive chemoradiotherapy with the reduced volume approach for ENI were reviewed. The ENI included retropharyngeal and level II lymph nodes, and only encompassed the echelon inferior to the involved level to eliminate the entire neck irradiation. Patients received either moderate hypofractionated intensity-modulated RT for a total of 72.6 Gy (49.5 Gy to elective nodal areas) or a conventional fractionated three-dimensional conformal RT for a total of 68.4-72 Gy (39.6-45 Gy to elective nodal areas). Patterns of failure, locoregional control, and survival were analyzed. The median follow-up was 38 months (range, 3 to 80 months). The out-of-field nodal failure when omitting ENI was none. Three patients developed neck recurrences (one in-field recurrence in the 72.6 Gy irradiated nodal area and two in the elective irradiated region of 39.6 Gy). Overall disease failure at any site developed in 11 patients (19.6%). Among these, there were six local failures (10.7%), three regional failures (5.4%), and five distant metastases (8.9%). The 3-year locoregional control rate was 87.1%, and the distant failure-free rate was 90.4%; disease-free survival and overall survival at 3 years was 80% and 86.8%, respectively. No patient developed nodal failure in the omitted ENI site. Our investigation has demonstrated that the reduced volume approach for ENI appears to be a safe treatment approach in NPC.

  4. Patterns of failure after the reduced volume approach for elective nodal irradiation in nasopharyngeal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Ki Ho; Lee, Jeong Eun [Dept. of Radiation Oncology, Kyungpook National University School of Medicine, Daegu (Korea, Republic of)

    2016-03-15

    To evaluate the patterns of nodal failure after radiotherapy (RT) with the reduced volume approach for elective neck nodal irradiation (ENI) in nasopharyngeal carcinoma (NPC). Fifty-six NPC patients who underwent definitive chemoradiotherapy with the reduced volume approach for ENI were reviewed. The ENI included retropharyngeal and level II lymph nodes, and only encompassed the echelon inferior to the involved level to eliminate the entire neck irradiation. Patients received either moderate hypofractionated intensity-modulated RT for a total of 72.6 Gy (49.5 Gy to elective nodal areas) or a conventional fractionated three-dimensional conformal RT for a total of 68.4-72 Gy (39.6-45 Gy to elective nodal areas). Patterns of failure, locoregional control, and survival were analyzed. The median follow-up was 38 months (range, 3 to 80 months). The out-of-field nodal failure when omitting ENI was none. Three patients developed neck recurrences (one in-field recurrence in the 72.6 Gy irradiated nodal area and two in the elective irradiated region of 39.6 Gy). Overall disease failure at any site developed in 11 patients (19.6%). Among these, there were six local failures (10.7%), three regional failures (5.4%), and five distant metastases (8.9%). The 3-year locoregional control rate was 87.1%, and the distant failure-free rate was 90.4%; disease-free survival and overall survival at 3 years was 80% and 86.8%, respectively. No patient developed nodal failure in the omitted ENI site. Our investigation has demonstrated that the reduced volume approach for ENI appears to be a safe treatment approach in NPC.

  5. Patterns of failure after the reduced volume approach for elective nodal irradiation in nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Seol, Ki Ho; Lee, Jeong Eun

    2016-01-01

    To evaluate the patterns of nodal failure after radiotherapy (RT) with the reduced volume approach for elective neck nodal irradiation (ENI) in nasopharyngeal carcinoma (NPC). Fifty-six NPC patients who underwent definitive chemoradiotherapy with the reduced volume approach for ENI were reviewed. The ENI included retropharyngeal and level II lymph nodes, and only encompassed the echelon inferior to the involved level to eliminate the entire neck irradiation. Patients received either moderate hypofractionated intensity-modulated RT for a total of 72.6 Gy (49.5 Gy to elective nodal areas) or a conventional fractionated three-dimensional conformal RT for a total of 68.4-72 Gy (39.6-45 Gy to elective nodal areas). Patterns of failure, locoregional control, and survival were analyzed. The median follow-up was 38 months (range, 3 to 80 months). The out-of-field nodal failure when omitting ENI was none. Three patients developed neck recurrences (one in-field recurrence in the 72.6 Gy irradiated nodal area and two in the elective irradiated region of 39.6 Gy). Overall disease failure at any site developed in 11 patients (19.6%). Among these, there were six local failures (10.7%), three regional failures (5.4%), and five distant metastases (8.9%). The 3-year locoregional control rate was 87.1%, and the distant failure-free rate was 90.4%; disease-free survival and overall survival at 3 years was 80% and 86.8%, respectively. No patient developed nodal failure in the omitted ENI site. Our investigation has demonstrated that the reduced volume approach for ENI appears to be a safe treatment approach in NPC

  6. Ultrasound-guided core biopsy: an effective method of detecting axillary nodal metastases.

    LENUS (Irish Health Repository)

    Solon, Jacqueline G

    2012-02-01

    BACKGROUND: Axillary nodal status is an important prognostic predictor in patients with breast cancer. This study evaluated the sensitivity and specificity of ultrasound-guided core biopsy (Ax US-CB) at detecting axillary nodal metastases in patients with primary breast cancer, thereby determining how often sentinel lymph node biopsy could be avoided in node positive patients. STUDY DESIGN: Records of patients presenting to a breast unit between January 2007 and June 2010 were reviewed retrospectively. Patients who underwent axillary ultrasonography with or without preoperative core biopsy were identified. Sensitivity, specificity, positive predictive value, and negative predictive value for ultrasonography and percutaneous biopsy were evaluated. RESULTS: Records of 718 patients were reviewed, with 445 fulfilling inclusion criteria. Forty-seven percent (n = 210\\/445) had nodal metastases, with 110 detected by Ax US-CB (sensitivity 52.4%, specificity 100%, positive predictive value 100%, negative predictive value 70.1%). Axillary ultrasonography without biopsy had sensitivity and specificity of 54.3% and 97%, respectively. Lymphovascular invasion was an independent predictor of nodal metastases (sensitivity 60.8%, specificity 80%). Ultrasound-guided core biopsy detected more than half of all nodal metastases, sparing more than one-quarter of all breast cancer patients an unnecessary sentinel lymph node biopsy. CONCLUSIONS: Axillary ultrasonography, when combined with core biopsy, is a valuable component of the management of patients with primary breast cancer. Its ability to definitively identify nodal metastases before surgical intervention can greatly facilitate a patient\\'s preoperative integrated treatment plan. In this regard, we believe our study adds considerably to the increasing data, which indicate the benefit of Ax US-CB in the preoperative detection of nodal metastases.

  7. The effect of nodalization and temperature of reactor upper region: Sensitivity analysis for APR-1400 LBLOCA

    International Nuclear Information System (INIS)

    Kang, Dong Gu

    2017-01-01

    Highlights: • The nodalization of APR-1400 was modified to reflect the characteristic of upper region temperature. • The effect of nodalization and temperature of reactor upper region on LBLOCA consequence was evaluated. • The modification of nodalization is an essential prerequisite in APR-1400 LBLOCA analysis. - Abstract: In best estimate (BE) calculation, the definition of system nodalization is important step influencing the prediction accuracy for specific thermal-hydraulic phenomena. The upper region of reactor is defined as the region of the upper guide structure (UGS) and upper dome. It has been assumed that the temperature of upper region is close to average temperature in most large break loss of coolant accident (LBLOCA) analysis cases. However, it was recently found that the temperature of upper region of APR-1400 reactor might be little lower than or similar to hot leg temperature through the review of detailed design data. In this study, the nodalization of APR-1400 was modified to reflect the characteristic of upper region temperature, and the effect of nodalization and temperature of reactor upper region on LBLOCA consequence was evaluated by sensitivity analysis including best estimate plus uncertainty (BEPU) calculation. In basecase calculation, in case of modified version, the peak cladding temperature (PCT) in blowdown phase became higher and the blowdown quenching (or cooling) was significantly deteriorated as compared to original case, and as a result, the cladding temperature in reflood phase became higher and the final quenching was also delayed. In addition, thermal-hydraulic parameters were compared and analyzed to investigate the effect of change of upper region on cladding temperature. In BEPU analysis, the 95 percentile PCT used in current regulatory practice was increased due to the modification of upper region nodalization, and it occurred in the reflood phase unlike original case.

  8. Extra-nodal extension is a significant prognostic factor in lymph node positive breast cancer.

    Directory of Open Access Journals (Sweden)

    Sura Aziz

    Full Text Available Presence of lymph node (LN metastasis is a strong prognostic factor in breast cancer, whereas the importance of extra-nodal extension and other nodal tumor features have not yet been fully recognized. Here, we examined microscopic features of lymph node metastases and their prognostic value in a population-based cohort of node positive breast cancer (n = 218, as part of the prospective Norwegian Breast Cancer Screening Program NBCSP (1996-2009. Sections were reviewed for the largest metastatic tumor diameter (TD-MET, nodal afferent and efferent vascular invasion (AVI and EVI, extra-nodal extension (ENE, number of ENE foci, as well as circumferential (CD-ENE and perpendicular (PD-ENE diameter of extra-nodal growth. Number of positive lymph nodes, EVI, and PD-ENE were significantly increased with larger primary tumor (PT diameter. Univariate survival analysis showed that several features of nodal metastases were associated with disease-free (DFS or breast cancer specific survival (BCSS. Multivariate analysis demonstrated an independent prognostic value of PD-ENE (with 3 mm as cut-off value in predicting DFS and BCSS, along with number of positive nodes and histologic grade of the primary tumor (for DFS: P = 0.01, P = 0.02, P = 0.01, respectively; for BCSS: P = 0.02, P = 0.008, P = 0.02, respectively. To conclude, the extent of ENE by its perpendicular diameter was independently prognostic and should be considered in line with nodal tumor burden in treatment decisions of node positive breast cancer.

  9. Development of an object oriented nodal code using the refined AFEN derived from the method of component decomposition

    International Nuclear Information System (INIS)

    Noh, J. M.; Yoo, J. W.; Joo, H. K.

    2004-01-01

    In this study, we invented a method of component decomposition to derive the systematic inter-nodal coupled equations of the refined AFEN method and developed an object oriented nodal code to solve the derived coupled equations. The method of component decomposition decomposes the intra-nodal flux expansion of a nodal method into even and odd components in three dimensions to reduce the large coupled linear system equation into several small single equations. This method requires no additional technique to accelerate the iteration process to solve the inter-nodal coupled equations, since the derived equations can automatically act as the coarse mesh re-balance equations. By utilizing the object oriented programming concepts such as abstraction, encapsulation, inheritance and polymorphism, dynamic memory allocation, and operator overloading, we developed an object oriented nodal code that can facilitate the input/output and the dynamic control of the memories, and can make the maintenance easy. (authors)

  10. Recognizing nodal marginal zone lymphoma: recent advances and pitfalls. A systematic review

    Science.gov (United States)

    van den Brand, Michiel; van Krieken, J. Han J.M.

    2013-01-01

    The diagnosis of nodal marginal zone lymphoma is one of the remaining problem areas in hematopathology. Because no established positive markers exist for this lymphoma, it is frequently a diagnosis of exclusion, making distinction from other low-grade B-cell lymphomas difficult or even impossible. This systematic review summarizes and discusses the current knowledge on nodal marginal zone lymphoma, including clinical features, epidemiology and etiology, histology, and cytogenetic and molecular features. In particular, recent advances in diagnostics and pathogenesis are discussed. New immunohistochemical markers have become available that could be used as positive markers for nodal marginal zone lymphoma. These markers could be used to ensure more homogeneous study groups in future research. Also, recent gene expression studies and studies describing specific gene mutations have provided clues to the pathogenesis of nodal marginal zone lymphoma, suggesting deregulation of the nuclear factor kappa B pathway. Nevertheless, nodal marginal zone lymphoma remains an enigmatic entity, requiring further study to define its pathogenesis to allow an accurate diagnosis and tailored treatment. However, recent data indicate that it is not related to splenic or extranodal lymphoma, and that it is also not related to lymphoplasmacytic lymphoma. Thus, even though the diagnosis is not always easy, it is clearly a separate entity. PMID:23813646

  11. A new diffusion nodal method based on analytic basis function expansion

    International Nuclear Information System (INIS)

    Noh, J.M.; Cho, N.Z.

    1993-01-01

    The transverse integration procedure commonly used in most advanced nodal methods results in some limitations. The first is that the transverse leakage term that appears in the transverse integration procedure must be appropriately approximated. In most advanced nodal methods, this term is expanded in a quadratic polynomial. The second arises when reconstructing the pinwise flux distribution within a node. The available one-dimensional flux shapes from nodal calculation in each spatial direction cannot be used directly in the flux reconstruction. Finally, the transverse leakage defined for a hexagonal node becomes so complicated as not to be easily handled and contains nonphysical singular terms. In this paper, a new nodal method called the analytic function expansion nodal (AFEN) method is described for both the rectangular geometry and the hexagonal geometry in order to overcome these limitations. This method does not solve the transverse-integrated one-dimensional diffusion equations but instead solves directly the original multidimensional diffusion equation within a node. This is a accomplished by expanding the solution (or the intranodal homogeneous flux distribution) in terms of nonseparable analytic basis functions satisfying the diffusion equation at any point in the node

  12. Interplay between short-range correlated disorder and Coulomb interaction in nodal-line semimetals

    Science.gov (United States)

    Wang, Yuxuan; Nandkishore, Rahul M.

    2017-09-01

    In nodal-line semimetals, Coulomb interactions and short-range correlated disorder are both marginal perturbations to the clean noninteracting Hamiltonian. We analyze their interplay using a weak-coupling renormalization group approach. In the clean case, the Coulomb interaction has been found to be marginally irrelevant, leading to Fermi liquid behavior. We extend the analysis to incorporate the effects of disorder. The nodal line structure gives rise to kinematical constraints similar to that for a two-dimensional Fermi surface, which plays a crucial role in the one-loop renormalization of the disorder couplings. For a twofold degenerate nodal loop (Weyl loop), we show that disorder flows to strong coupling along a unique fixed trajectory in the space of symmetry inequivalent disorder couplings. Along this fixed trajectory, all symmetry inequivalent disorder strengths become equal. For a fourfold degenerate nodal loop (Dirac loop), disorder also flows to strong coupling, however, the strengths of symmetry inequivalent disorder couplings remain different. We show that feedback from disorder reverses the sign of the beta function for the Coulomb interaction, causing the Coulomb interaction to flow to strong coupling as well. However, the Coulomb interaction flows to strong coupling asymptotically more slowly than disorder. Extrapolating our results to strong coupling, we conjecture that at low energies nodal line semimetals should be described by a noninteracting nonlinear sigma model. We discuss the relation of our results with possible many-body localization at zero temperatures in such materials.

  13. Tumor microvessel density–associated mast cells in canine nodal lymphoma

    Directory of Open Access Journals (Sweden)

    Moges Woldemeskel

    2014-11-01

    Full Text Available Objective: Mast cells are associated in angiogenesis in various human and animal neoplasms. However, association of mast cells with tumor microvessel density in canine lymphoma was not previously documented. The objective of the study is to determine if mast cells are increased in canine nodal lymphomas and to evaluate their correlation with tumor microvessel density and grading of lymphomas. Methods: Nodal lymphomas from 33 dogs were studied and compared with nonneoplastic lymph nodes from 6 dogs as control. Mast cell count was made on Toluidine blue stained sections. Immunohistochemistry using antibody against Factor VIII was employed to visualize and determine microvessel density. Results: The mast cell count in lymphoma (2.95 ± 2.4 was significantly higher (p < 0.05 than that in the control (0.83 ± 0.3 and was positively correlated with tumor microvessel density (r = 0.44, p = 0.009. Significant difference was not observed in mast cell count and tumor microvessel density among different gradings of lymphomas. Conclusions: Mast cells are associated with tumor microvessel density in canine nodal lymphoma with no significant difference among gradings of lymphomas. Mast cells may play an important role in development of canine nodal lymphomas. Further detailed investigation on the role of mast cells as important part of tumor microenvironment in canine nodal lymphomas is recommended.

  14. Nodalization effects on RELAP5 results related to MTR research reactor transient scenarios

    Directory of Open Access Journals (Sweden)

    Khedr Ahmed

    2005-01-01

    Full Text Available The present work deals with the anal y sis of RELAP5 results obtained from the evaluation study of the total loss of flow transient with the deficiency of the heat removal system in a research reactor using two different nodalizations. It focuses on the effect of nodalization on the thermal-hydraulic evaluation of the re search reactor. The analysis of RELAP5 results has shown that nodalization has a big effect on the predicted scenario of the postulated transient. There fore, great care should be taken during the nodalization of the reactor, especially when the avail able experimental or measured data are insufficient for making a complete qualification of the nodalization. Our analysis also shows that the research reactor pool simulation has a great effect on the evaluation of natural circulation flow and on other thermal-hydraulic parameters during the loss of flow transient. For example, the on set time of core boiling changes from less than 2000 s to 15000 s, starting from the beginning of the transient. This occurs if the pool is simulated by two vertical volumes in stead of one vertical volume.

  15. Tumor microvessel density–associated mast cells in canine nodal lymphoma

    Science.gov (United States)

    Mann, Elizabeth; Whittington, Lisa

    2014-01-01

    Objective: Mast cells are associated in angiogenesis in various human and animal neoplasms. However, association of mast cells with tumor microvessel density in canine lymphoma was not previously documented. The objective of the study is to determine if mast cells are increased in canine nodal lymphomas and to evaluate their correlation with tumor microvessel density and grading of lymphomas. Methods: Nodal lymphomas from 33 dogs were studied and compared with nonneoplastic lymph nodes from 6 dogs as control. Mast cell count was made on Toluidine blue stained sections. Immunohistochemistry using antibody against Factor VIII was employed to visualize and determine microvessel density. Results: The mast cell count in lymphoma (2.95 ± 2.4) was significantly higher (p < 0.05) than that in the control (0.83 ± 0.3) and was positively correlated with tumor microvessel density (r = 0.44, p = 0.009). Significant difference was not observed in mast cell count and tumor microvessel density among different gradings of lymphomas. Conclusions: Mast cells are associated with tumor microvessel density in canine nodal lymphoma with no significant difference among gradings of lymphomas. Mast cells may play an important role in development of canine nodal lymphomas. Further detailed investigation on the role of mast cells as important part of tumor microenvironment in canine nodal lymphomas is recommended. PMID:26770752

  16. An extremely rare clinical entity: congenitally corrected transposition with situs ınversus and single coronary artery presented with complete atrioventricular block in a young man.

    Science.gov (United States)

    Cirakoglu, Omer Faruk; Bayraktar, Ali; Sayin, Muhammet Rasit

    2018-05-01

    Congenitally corrected transposition of the great arteries is a rare form of CHD. Situs inversus is a much less common variant of a congenitally corrected transposition of the great arteries. In rare cases, transposition events may be accompanied by various cardiac anomalies. However, situs inversus patients with congenitally corrected transposition, single coronary artery anomaly, and atrioventricular block together have not been reported previously. This combination of abnormalities is presented as a first in the literature.

  17. A simplified presentation of the multigroup analytic nodal method in 2-D Cartesian geometry

    International Nuclear Information System (INIS)

    Hebert, Alain

    2008-01-01

    The nodal diffusion algorithms used in many production reactor simulation codes are originating from a common ancestry developed in the 1970s, the analytic nodal method (ANM) of the QUANDRY code. However, this original presentation of the ANM is complex and makes difficult the calculation of the nodal coupling matrices. Moreover, QUANDRY is limited to two-energy groups and its generalization to more groups appears laborious. We are presenting a simplified implementation of the ANM requiring only limited programming work. This formulation is consistent with the initial QUANDRY implementation and is easily generalizable to arbitrary G-group problems. A Matlab script is provided to highlight the simplicity of our presentation. For the sake of clarity, our implementation is limited to G-group, 2-D Cartesian geometry

  18. Cryopreservation of in vitro grown nodal segments of Rauvolfia serpentina by PVS2 vitrification.

    Science.gov (United States)

    Ray, Avik; Bhattacharya, Sabita

    2008-01-01

    This paper describes the cryopreservation by PVS2 vitrification of Rauvolfia serpentina (L.) Benth ex kurz, an important tropical medicinal plant. The effects of type and size of explants, sucrose preculture (duration and concentration) and vitrification treatment were tested. Preliminary experiments with PVS1, 2 and 3 produced shoot growth only for PVS2. When optimizing the PVS2 vitrification of nodal segments, those of 0.31 - 0.39 cm in size were better than other nodal sizes and or apices. Sucrose preculture had a positive role in survival and subsequent regrowth of the cryopreserved explants. Seven days on 0.5 M sucrose solution significantly improved the viability of nodal segments. PVS2 incubation for 45 minutes combined with a 7-day preculture gave the optimum result of 66 percent. Plantlets derived after cryopreservation resumed growth and regenerated normally.

  19. cmpXLatt: Westinghouse automated testing tool for nodal cross section models

    International Nuclear Information System (INIS)

    Guimaraes, Petri Forslund; Rönnberg, Kristian

    2011-01-01

    The procedure for evaluating the merits of different nodal cross section representation models is normally both cumbersome and time consuming, and includes many manual steps when preparing appropriate benchmark problems. Therefore, a computer tool called cmpXLatt has been developed at Westinghouse in order to facilitate the process of performing comparisons between nodal diffusion theory results and corresponding transport theory results on a single node basis. Due to the large number of state points that can be evaluated by cmpXLatt, a systematic and comprehensive way of performing verification and validation of nodal cross section models is provided. This paper presents the main features of cmpXLatt and demonstrates the benefits of using cmpXLatt in a real life application. (author)

  20. Higher order polynomial expansion nodal method for hexagonal core neutronics analysis

    International Nuclear Information System (INIS)

    Jin, Young Cho; Chang, Hyo Kim

    1998-01-01

    A higher-order polynomial expansion nodal(PEN) method is newly formulated as a means to improve the accuracy of the conventional PEN method solutions to multi-group diffusion equations in hexagonal core geometry. The new method is applied to solving various hexagonal core neutronics benchmark problems. The computational accuracy of the higher order PEN method is then compared with that of the conventional PEN method, the analytic function expansion nodal (AFEN) method, and the ANC-H method. It is demonstrated that the higher order PEN method improves the accuracy of the conventional PEN method and that it compares very well with the other nodal methods like the AFEN and ANC-H methods in accuracy

  1. Isospectral discrete and quantum graphs with the same flip counts and nodal counts

    Science.gov (United States)

    Juul, Jonas S.; Joyner, Christopher H.

    2018-06-01

    The existence of non-isomorphic graphs which share the same Laplace spectrum (to be referred to as isospectral graphs) leads naturally to the following question: what additional information is required in order to resolve isospectral graphs? It was suggested by Band, Shapira and Smilansky that this might be achieved by either counting the number of nodal domains or the number of times the eigenfunctions change sign (the so-called flip count) (Band et al 2006 J. Phys. A: Math. Gen. 39 13999–4014 Band and Smilansky 2007 Eur. Phys. J. Spec. Top. 145 171–9). Recent examples of (discrete) isospectral graphs with the same flip count and nodal count have been constructed by Ammann by utilising Godsil–McKay switching (Ammann private communication). Here, we provide a simple alternative mechanism that produces systematic examples of both discrete and quantum isospectral graphs with the same flip and nodal counts.

  2. SIRIUS - A one-dimensional multigroup analytic nodal diffusion theory code

    Energy Technology Data Exchange (ETDEWEB)

    Forslund, P. [Westinghouse Atom AB, Vaesteraas (Sweden)

    2000-09-01

    In order to evaluate relative merits of some proposed intranodal cross sections models, a computer code called Sirius has been developed. Sirius is a one-dimensional, multigroup analytic nodal diffusion theory code with microscopic depletion capability. Sirius provides the possibility of performing a spatial homogenization and energy collapsing of cross sections. In addition a so called pin power reconstruction method is available for the purpose of reconstructing 'heterogeneous' pin qualities. consequently, Sirius has the capability of performing all the calculations (incl. depletion calculations) which are an integral part of the nodal calculation procedure. In this way, an unambiguous numerical analysis of intranodal cross section models is made possible. In this report, the theory of the nodal models implemented in sirius as well as the verification of the most important features of these models are addressed.

  3. Discrete rod burnup analysis capability in the Westinghouse advanced nodal code

    International Nuclear Information System (INIS)

    Buechel, R.J.; Fetterman, R.J.; Petrunyak, M.A.

    1992-01-01

    Core design analysis in the last several years has evolved toward the adoption of nodal-based methods to replace traditional fine-mesh models as the standard neutronic tool for first core and reload design applications throughout the nuclear industry. The accuracy, speed, and reduction in computation requirements associated with the nodal methods have made three-dimensional modeling the preferred approach to obtain the most realistic core model. These methods incorporate detailed rod power reconstruction as well. Certain design applications such as confirmation of fuel rod design limits and fuel reconstitution considerations, for example, require knowledge of the rodwise burnup distribution to avoid unnecessary conservatism in design analyses. The Westinghouse Advanced Nodal Code (ANC) incorporates the capability to generate the intra-assembly pin burnup distribution using an efficient algorithm

  4. Electrophysiological properties of myocytes isolated from the mouse atrioventricular node: L-type ICa, IKr, If, and Na-Ca exchange.

    Science.gov (United States)

    Choisy, Stéphanie C; Cheng, Hongwei; Orchard, Clive H; James, Andrew F; Hancox, Jules C

    2015-11-01

    The atrioventricular node (AVN) is a key component of the cardiac pacemaker-conduction system. This study investigated the electrophysiology of cells isolated from the AVN region of adult mouse hearts, and compared murine ionic current magnitude with that of cells from the more extensively studied rabbit AVN. Whole-cell patch-clamp recordings of ionic currents, and perforated-patch recordings of action potentials (APs), were made at 35-37°C. Hyperpolarizing voltage commands from -40 mV elicited a Ba(2+)-sensitive inward rectifier current that was small at diastolic potentials. Some cells (Type 1; 33.4 ± 2.2 pF; n = 19) lacked the pacemaker current, If, whilst others (Type 2; 34.2 ± 1.5 pF; n = 21) exhibited a clear If, which was larger than in rabbit AVN cells. On depolarization from -40 mV L-type Ca(2+) current, IC a,L, was elicited with a half maximal activation voltage (V0.5) of -7.6 ± 1.2 mV (n = 24). IC a,L density was smaller than in rabbit AVN cells. Rapid delayed rectifier (IK r) tail currents sensitive to E-4031 (5 μmol/L) were observed on repolarization to -40 mV, with an activation V0.5 of -10.7 ± 4.7 mV (n = 8). The IK r magnitude was similar in mouse and rabbit AVN. Under Na-Ca exchange selective conditions, mouse AVN cells exhibited 5 mmol/L Ni-sensitive exchange current that was inwardly directed negative to the holding potential (-40 mV). Spontaneous APs (5.2 ± 0.5 sec(-1); n = 6) exhibited an upstroke velocity of 37.7 ± 16.2 V/s and ceased following inhibition of sarcoplasmic reticulum Ca(2+) release by 1 μmol/L ryanodine, implicating intracellular Ca(2+) cycling in murine AVN cell electrogenesis. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  5. A transient, Hex-Z nodal code corrected by discontinuity factors

    International Nuclear Information System (INIS)

    Shatilla, Y.A.M.; Henry, A.F.

    1993-01-01

    This document constitutes Volume 1 of the Final Report of a three-year study supported by the special Research Grant Program for Nuclear Energy Research set up by the US Department of Energy. The original motivation for the work was to provide a fast and accurate computer program for the analysis of transients in heavy water or graphite-moderated reactors being considered as candidates for the New Production Reactor. Thus, part of the funding was by way of pass-through money from the Savannah River Laboratory. With this intent in mind, a three-dimensional (Hex-Z), general-energy-group transient, nodal code was created, programmed, and tested. In order to improve accuracy, correction terms, called open-quotes discontinuity factors,close quotes were incorporated into the nodal equations. Ideal values of these factors force the nodal equations to provide node-integrated reaction rates and leakage rates across nodal surfaces that match exactly those edited from a more exact reference calculation. Since the exact reference solution is needed to compute the ideal discontinuity factors, the fact that they result in exact nodal equations would be of little practical interest were it not that approximate discontinuity factors, found at a greatly reduced cost, often yield very accurate results. For example, for light-water reactors, discontinuity factors found from two-dimensional, fine-mesh, multigroup transport solutions for two-dimensional cuts of a fuel assembly provide very accurate predictions of three-dimensional, full-core power distributions. The present document (volume 1) deals primarily with the specification, programming and testing of the three-dimensional, Hex-Z computer program. The program solves both the static (eigenvalue) and transient, general-energy-group, nodal equations corrected by user-supplied discontinuity factors

  6. Fluorine-18-Fluorodeoxyglucose PET in the mediastinal nodal staging of bronchogenic carcinoma.

    Energy Technology Data Exchange (ETDEWEB)

    Berlangieri, S.U.; Scott, A.M.; Knight, S.; Pointon, O.; Thomas, D.L.; O``Keefe, G.; Chan, J.G.; Egen, G.F.; Tochon-Danguy, H.J.; Clarke, C.P.; McKay, W.J. [Austin Hospital, Melbourne, VIC (Australia). Centre for Positron Emission Tomography and the Departments of Nuclear Medicine and Thoracic Surgery

    1998-03-01

    Full text: Non-invasive methods of pre-operative staging of non-small cell bronchogenic carcinoma are inaccurate. To determine the clinical role of positron emission tomography (PET) in the mediastinal staging of lung carcinoma, {sup 18}F-fluorodeoxyglucose (FDG) studies were performed in 25 patients with suspected non-small cell bronchogenic carcinoma and correlated with pathology. The patients comprised 20 men and 5 women (mean age 63; range 43-78 y). All patients had proven non-small cell lung carcinoma, except two, one patient with benign inflammatory disease and the other with small cell carcinoma. The FDG PET studies were acquired on a Siemens 951131R body tomography over 2-3 bed positions to include the thorax and mediastinum. The PET images were interpreted for tumour involvement of mediastinal nodes according to the American Thoracic Society classification and scored for confidence of tumour presence on a 5 point scale. The intensity of glucose metabolism was compared to mediastinal blood pool activity and graded on a 4 point scale. FDG PET correctly excluded ipsilateral mediastinal nodal (N2) disease in 16 of 16 patients. Six of nine patients with N2 disease were correctly identified by FDG PET. Of the three patients with N2 nodal involvement not detected by PET, each had single station nodal disease, and in two patients the primary lesions abutted the involved nodal group. A total of 104 nodal stations were sampled or examined at surgery. FDG PET correctly excluded disease in 83/83 (100% specificity) negative nodal stations. FDG PET is a promising non-invasive functional imaging modality for the mediastinal staging of bronchogenic carcinoma.

  7. Hybrid nodal methods in the solution of the diffusion equations in X Y geometry

    International Nuclear Information System (INIS)

    Hernandez M, N.; Alonso V, G.; Valle G, E. del

    2003-01-01

    In 1979, Hennart and collaborators applied several schemes of classic finite element in the numerical solution of the diffusion equations in X Y geometry and stationary state. Almost two decades then, in 1996, himself and other collaborators carried out a similar work but using nodal schemes type finite element. Continuing in this last direction, in this work a group it is described a set of several Hybrid Nodal schemes denominated (NH) as well as their application to solve the diffusion equations in multigroup in stationary state and X Y geometry. The term hybrid nodal it means that such schemes interpolate not only Legendre moments of face and of cell but also the values of the scalar flow of neutrons in the four corners of each cell or element of the spatial discretization of the domain of interest. All the schemes here considered are polynomials like they were it their predecessors. Particularly, its have developed and applied eight different hybrid nodal schemes that its are very nearby related with those developed by Hennart and collaborators in the past. It is treated of schemes in those that nevertheless that decreases the number of interpolation parameters it is conserved the accurate in relation to the bi-quadratic and bi-cubic schemes. Of these eight, three were described and applied in a previous work. It is the bi-lineal classic scheme as well as the hybrid nodal schemes, bi-quadratic and bi-cubic for that here only are described the other 5 hybrid nodal schemes although they are provided numerical results for several test problems with all them. (Author)

  8. A geometrically exact beam element based on the absolute nodal coordinate formulation

    International Nuclear Information System (INIS)

    Gerstmayr, Johannes; Matikainen, Marko K.; Mikkola, Aki M.

    2008-01-01

    In this study, Reissner's classical nonlinear rod formulation, as implemented by Simo and Vu-Quoc by means of the large rotation vector approach, is implemented into the framework of the absolute nodal coordinate formulation. The implementation is accomplished in the planar case accounting for coupled axial, bending, and shear deformation. By employing the virtual work of elastic forces similarly to Simo and Vu-Quoc in the absolute nodal coordinate formulation, the numerical results of the formulation are identical to those of the large rotation vector formulation. It is noteworthy, however, that the material definition in the absolute nodal coordinate formulation can differ from the material definition used in Reissner's beam formulation. Based on an analytical eigenvalue analysis, it turns out that the high frequencies of cross section deformation modes in the absolute nodal coordinate formulation are only slightly higher than frequencies of common shear modes, which are present in the classical large rotation vector formulation of Simo and Vu-Quoc, as well. Thus, previous claims that the absolute nodal coordinate formulation is inefficient or would lead to ill-conditioned finite element matrices, as compared to classical approaches, could be refuted. In the introduced beam element, locking is prevented by means of reduced integration of certain parts of the elastic forces. Several classical large deformation static and dynamic examples as well as an eigenvalue analysis document the equivalence of classical nonlinear rod theories and the absolute nodal coordinate formulation for the case of appropriate material definitions. The results also agree highly with those computed in commercial finite element codes

  9. On the treatment of nonlinear local feedbacks within advanced nodal generalized perturbation theory

    International Nuclear Information System (INIS)

    Maldonado, G.I.; Turinsky, P.J.; Kropaczek, D.J.

    1993-01-01

    Recent efforts to upgrade the underlying neutronics formulations within the in-core nuclear fuel management optimization code FORMOSA (Ref. 1) have produced two important developments; first, a computationally efficient and second-order-accurate advanced nodal generalized perturbation theory (GPT) model [derived from the nonlinear iterative nodal expansion method (NEM)] for evaluating core attributes (i.e., k eff and power distribution versus cycle burnup), and second, an equally efficient and accurate treatment of local thermal-hydraulic and fission product feedbacks embedded within NEM GPT. The latter development is the focus of this paper

  10. Segregated nodal domains of two-dimensional multispecies Bose-Einstein condensates

    Science.gov (United States)

    Chang, Shu-Ming; Lin, Chang-Shou; Lin, Tai-Chia; Lin, Wen-Wei

    2004-09-01

    In this paper, we study the distribution of m segregated nodal domains of the m-mixture of Bose-Einstein condensates under positive and large repulsive scattering lengths. It is shown that components of positive bound states may repel each other and form segregated nodal domains as the repulsive scattering lengths go to infinity. Efficient numerical schemes are created to confirm our theoretical results and discover a new phenomenon called verticillate multiplying, i.e., the generation of multiple verticillate structures. In addition, our proposed Gauss-Seidel-type iteration method is very effective in that it converges linearly in 10-20 steps.

  11. [Does nodal irradiation (clavicular and internal mammary chains) increase the toxicity of adjuvant breast radiotherapy?].

    Science.gov (United States)

    Riou, O; Bourgier, C; Fenoglietto, P; Azria, D

    2015-06-01

    Treatment volume is a major risk factor of radiation-induced toxicity. As nodal irradiation increases treatment volume, radiation toxicity should be greater. Nevertheless, scientific randomised data do not support this fact. However, a radiation-induced toxicity is possible outside tangential fields in the nodal volumes not related to breast-only treatment. Treatment should not be adapted only to the disease but personalized to the individual risk of toxicity for each patient. Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  12. A self-consistent nodal method in response matrix formalism for the multigroup diffusion equations

    International Nuclear Information System (INIS)

    Malambu, E.M.; Mund, E.H.

    1996-01-01

    We develop a nodal method for the multigroup diffusion equations, based on the transverse integration procedure (TIP). The efficiency of the method rests upon the convergence properties of a high-order multidimensional nodal expansion and upon numerical implementation aspects. The discrete 1D equations are cast in response matrix formalism. The derivation of the transverse leakage moments is self-consistent i.e. does not require additional assumptions. An outstanding feature of the method lies in the linear spatial shape of the local transverse leakage for the first-order scheme. The method is described in the two-dimensional case. The method is validated on some classical benchmark problems. (author)

  13. Nodal signals mediate interactions between the extra-embryonic and embryonic tissues in zebrafish

    OpenAIRE

    Xiang, Fan; Hagos, Engda G.; Xu, Bo; Sias, Christina; Kawakami, Koichi; Burdine, Rebecca D.; Dougan, Scott T.

    2007-01-01

    In many vertebrates, extra-embryonic tissues are important signaling centers that induce and pattern the germ layers. In teleosts, the mechanism by which the extra-embryonic yolk syncytial layer (YSL) patterns the embryo is not understood. Although the Nodal-related protein Squint is expressed in the YSL, its role in this tissue is not known. We generated a series of stable transgenic lines with GFP under the control of squint genomic sequences. In all species, nodal-related genes induce thei...

  14. Spectral nodal method for one-speed X,Y-geometry Eigenvalue diffusion problems

    International Nuclear Information System (INIS)

    Dominguez, Dany S.; Lorenzo, Daniel M.; Hernandez, Carlos G.; Barros, Ricardo C.; Silva, Fernando C. da

    2001-01-01

    Presented here is a new numerical nodal method for steady-state multidimensional neutron diffusion equation in rectangular geometry. Our method is based on a spectral analysis of the transverse-integrated nodal diffusion equations. These equations are obtained by integrating the diffusion equation in X and Y directions, and then considering flat approximations for the transverse leakage terms. These flat approximations are the only approximations that we consider in this method; as a result the numerical solutions are completely free from truncation errors in slab geometry. We show numerical results to illustrate the method's accuracy for coarse mesh calculations in a heterogeneous medium. (author)

  15. One-dimensional nodal neutronics routines for the TRAC-BD1 thermal-hydraulics program

    International Nuclear Information System (INIS)

    Nigg, D.W.

    1983-09-01

    Nuclear reactor core transient neutronic behavior is currently modeled in the TRAC-BD1 code using a point-reactor kinetics formulation. This report describes a set of subroutines based on the Analytic Nodal Method that were written to provide TRAC-BD1 with a one-dimensional space-dependent neutronics capability. Use of the routines is illustrated with several test problems. The results of these problems show that the Analytic Nodal neutronics routines have desirable accuracy and computing time characteristics and should be a useful addition to TRAC-BD1

  16. Incidental Prophylactic Nodal Irradiation and Patterns of Nodal Relapse in Inoperable Early Stage NSCLC Patients Treated With SBRT: A Case-Matched Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lao, Louis [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, Auckland City Hospital, Auckland (New Zealand); Hope, Andrew J. [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Maganti, Manjula [Department of Biostatistics, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Brade, Anthony; Bezjak, Andrea; Saibishkumar, Elantholi P.; Giuliani, Meredith; Sun, Alexander [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Cho, B. C. John, E-mail: john.cho@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada)

    2014-09-01

    Purpose: Reported rates of non-small cell lung cancer (NSCLC) nodal failure following stereotactic body radiation therapy (SBRT) are lower than those reported in the surgical series when matched for stage. We hypothesized that this effect was due to incidental prophylactic nodal irradiation. Methods and Materials: A prospectively collected group of medically inoperable early stage NSCLC patients from 2004 to 2010 was used to identify cases with nodal relapses. Controls were matched to cases, 2:1, controlling for tumor volume (ie, same or greater) and tumor location (ie, same lobe). Reference (normalized to equivalent dose for 2-Gy fractions [EQD2]) point doses at the ipsilateral hilum and carina, demographic data, and clinical outcomes were extracted from the medical records. Univariate conditional logistical regression analyses were performed with variables of interest. Results: Cases and controls were well matched except for size. The controls, as expected, had larger gross tumor volumes (P=.02). The mean ipsilateral hilar doses were 9.6 Gy and 22.4 Gy for cases and controls, respectively (P=.014). The mean carinal doses were 7.0 Gy and 9.2 Gy, respectively (P=.13). Mediastinal nodal relapses, with and without ipsilateral hilar relapse, were associated with mean ipsilateral hilar doses of 3.6 Gy and 19.8 Gy, respectively (P=.01). The conditional density plot appears to demonstrate an inverse dose-effect relationship between ipsilateral hilar normalized total dose and risk of ipsilateral hilar relapse. Conclusions: Incidental hilar dose greater than 20 Gy is significantly associated with fewer ipsilateral hilar relapses in inoperable early stage NSCLC patients treated with SBRT.

  17. Incidental Prophylactic Nodal Irradiation and Patterns of Nodal Relapse in Inoperable Early Stage NSCLC Patients Treated With SBRT: A Case-Matched Analysis

    International Nuclear Information System (INIS)

    Lao, Louis; Hope, Andrew J.; Maganti, Manjula; Brade, Anthony; Bezjak, Andrea; Saibishkumar, Elantholi P.; Giuliani, Meredith; Sun, Alexander; Cho, B. C. John

    2014-01-01

    Purpose: Reported rates of non-small cell lung cancer (NSCLC) nodal failure following stereotactic body radiation therapy (SBRT) are lower than those reported in the surgical series when matched for stage. We hypothesized that this effect was due to incidental prophylactic nodal irradiation. Methods and Materials: A prospectively collected group of medically inoperable early stage NSCLC patients from 2004 to 2010 was used to identify cases with nodal relapses. Controls were matched to cases, 2:1, controlling for tumor volume (ie, same or greater) and tumor location (ie, same lobe). Reference (normalized to equivalent dose for 2-Gy fractions [EQD2]) point doses at the ipsilateral hilum and carina, demographic data, and clinical outcomes were extracted from the medical records. Univariate conditional logistical regression analyses were performed with variables of interest. Results: Cases and controls were well matched except for size. The controls, as expected, had larger gross tumor volumes (P=.02). The mean ipsilateral hilar doses were 9.6 Gy and 22.4 Gy for cases and controls, respectively (P=.014). The mean carinal doses were 7.0 Gy and 9.2 Gy, respectively (P=.13). Mediastinal nodal relapses, with and without ipsilateral hilar relapse, were associated with mean ipsilateral hilar doses of 3.6 Gy and 19.8 Gy, respectively (P=.01). The conditional density plot appears to demonstrate an inverse dose-effect relationship between ipsilateral hilar normalized total dose and risk of ipsilateral hilar relapse. Conclusions: Incidental hilar dose greater than 20 Gy is significantly associated with fewer ipsilateral hilar relapses in inoperable early stage NSCLC patients treated with SBRT

  18. Long-term outcome of concurrent chemoradiotherapy with elective nodal irradiation for inoperable esophageal cancer.

    Science.gov (United States)

    Jing, Zhao; Chen, Tian; Zhang, Xuebang; Wu, Shixiu

    2017-09-01

    Elective nodal irradiation (ENI) might improve overall survival in patients with inoperable esophageal cancer. We conducted a retrospective analysis to assess the long-term survival and toxicity of esophageal cancer patients treated with ENI versus conventional-field irradiation (CFI). All data in the present study were based on our institutional experience from 2000 to 2005 of patients with inoperable esophageal cancer treated with ENI or CFI plus two concurrent cycles of paclitaxel/cisplatin. Based on the inclusion and exclusion criteria, 89 patients were included in the analysis. Of these patients, 51 were treated with ENI, whereas 38 were treated with CFI. For the per-protocol population, the patients in the ENI group significantly improved in terms of their 10-year disease-specific overall survival (43.1% vs 10.5%, P = 0.019), 10-year disease-free survival (36.7% vs 10.2%, P = 0.040) and 10-year local recurrence-free survival (47.2% vs 17.2%, P = 0.018) compared with the CFI group. Aside from radiation esophagitis, the incidence of grade 3 or greater acute toxicities did not differ between the two groups. Multivariate analysis showed that radiation field, tumor length and clinical stage were independent prognostic factors associated with OS. Concurrent chemoradiotherapy with ENI improves both disease-specific overall survival and loco-regional control in patients with inoperable esophageal cancer receiving per-protocol treatment. The regimen has a manageable tolerability profile. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

  19. Amplification and protein overexpression of cyclin D1: Predictor of occult nodal metastasis in early oral cancer.

    Science.gov (United States)

    Noorlag, Rob; Boeve, Koos; Witjes, Max J H; Koole, Ronald; Peeters, Ton L M; Schuuring, Ed; Willems, Stefan M; van Es, Robert J J

    2017-02-01

    Accurate nodal staging is pivotal for treatment planning in early (stage I-II) oral cancer. Unfortunately, current imaging modalities lack sensitivity to detect occult nodal metastases. Chromosomal region 11q13, including genes CCND1, Fas-associated death domain (FADD), and CTTN, is often amplified in oral cancer with nodal metastases. However, evidence in predicting occult nodal metastases is limited. In 158 patients with early tongue and floor of mouth (FOM) squamous cell carcinomas, both CCND1 amplification and cyclin D1, FADD, and cortactin protein expression were correlated with occult nodal metastases. CCND1 amplification and cyclin D1 expression correlated with occult nodal metastases. Cyclin D1 expression was validated in an independent multicenter cohort, confirming the correlation with occult nodal metastases in early FOM cancers. Cyclin D1 is a predictive biomarker for occult nodal metastases in early FOM cancers. Prospective research on biopsy material should confirm these results before implementing its use in routine clinical practice. © 2016 Wiley Periodicals, Inc. Head Neck 39: 326-333, 2017. © 2016 Wiley Periodicals, Inc.

  20. A comparison of two efficient nonlinear heat conduction methodologies using a two-dimensional time-dependent benchmark problem

    International Nuclear Information System (INIS)

    Wilson, G.L.; Rydin, R.A.; Orivuori, S.

    1988-01-01

    Two highly efficient nonlinear time-dependent heat conduction methodologies, the nonlinear time-dependent nodal integral technique (NTDNT) and IVOHEAT are compared using one- and two-dimensional time-dependent benchmark problems. The NTDNT is completely based on newly developed time-dependent nodal integral methods, whereas IVOHEAT is based on finite elements in space and Crank-Nicholson finite differences in time. IVOHEAT contains the geometric flexibility of the finite element approach, whereas the nodal integral method is constrained at present to Cartesian geometry. For test problems where both methods are equally applicable, the nodal integral method is approximately six times more efficient per dimension than IVOHEAT when a comparable overall accuracy is chosen. This translates to a factor of 200 for a three-dimensional problem having relatively homogeneous regions, and to a smaller advantage as the degree of heterogeneity increases

  1. Ventricular fibrillation occurring after atrioventricular node ablation despite minimal difference between pre- and post-ablation heart rates.

    Science.gov (United States)

    Squara, F; Theodore, G; Scarlatti, D; Ferrari, E

    2017-02-01

    We report the case of an 82-year-old man presenting with ventricular fibrillation (VF) occurring acutely after atrioventricular node (AVN) ablation. This patient had severe valvular cardiomyopathy, chronic atrial fibrillation (AF), and underwent prior to the AVN ablation a biventricular implantable cardiac defibrillator positioning. The VF was successfully cardioverted with one external electrical shock. What makes this presentation original is that the pre-ablation spontaneous heart rate in AF was slow (84 bpm), and that VF occurred after ablation despite a minimal heart rate drop of only 14 bpm. VF is the most feared complication of AVN ablation, but it had previously only been described in case of acute heart rate drop after ablation of at least 30 bpm (and more frequently>50 bpm). This case report highlights the fact that VF may occur after AVN ablation regardless of the heart rate drop, rendering temporary fast ventricular pacing mandatory whatever the pre-ablation heart rate. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  2. Manual Intracardiac Electrogram Method Is Accurate Alternative to Echocardiography for Atrioventricular and Interventricular Optimization in Cardiac Resynchronization Therapy.

    Science.gov (United States)

    Pezo Nikolić, Borka; Lovrić, Daniel; Ljubas Maček, Jana; Rešković Lukšić, Vlatka; Matasić, Richard; Šeparović Hanževački, Jadranka

    2017-12-01

    Some manufacturers do not provide automated intracardiac electrogram method (IEGM) systems for atrioventricular (AV) and interventricular (VV) delay optimization in cardiac resynchronization therapy (CRT). We aimed to evaluate the accuracy of manual IEGM method in 48 patients previously implanted with Medtronic Syncra CRT. All patients underwent standard device interrogation followed by CRT optimization by IEGM method and by echocardiography one month after implantation. The patient mean age was 60.7±11.8 years and there were 33 (68.8%) males. After CRT implantation, the left ventricular ejection fraction increased from 28.0±7.9% to 39.1±11.0% (p<0.001). Optimal aortic flow Velocity Time Integral (aVTI) was obtained when VV was set to 20-50 ms left ventricular pre-activation. There was a strong correlation between VV values determined by echocardiography and IEGM (R=0.823, p<0.001). We found no significant difference in AV, VV and aVTI values between echocardiography and IEGM method. However, IEGM was significantly less time-consuming than echocardiography [20 (10-28) vs. 40 (35-60) minutes, p<0.001]. Manual IEGM method may be good alternative to echocardiography and automated IEGM method. It also emphasizes the need for implementation of automated IEGM systems in as many CRT devices as possible.

  3. Evidences of the ultrarapid delayed rectifier potassium current (IKur on pacemaker activity in sinoatrial and atrioventricular nodes of Rat

    Directory of Open Access Journals (Sweden)

    Mohammad reza Nikmaram

    2008-09-01

    Full Text Available Background: Sinoatrial node (SAN is the primary pacemaker of the heart. If the SAN activity fails in any way, then the atrioventricular node (AVN immediately starts to regulate the activities of the heart. The aim of this study was to assess the existence or non existence of ultrarapid delayed rectifier potassium current (Ikur and its role on pacemaker activity of two intact SAN and AVN of rat. Methods: The pacemaker activities of distinct intact SAN and AVN by two separate metal microelectrodes that contact the endothelial surface of nodes were recorded and cycle length (CL of action potential was measured. The recording was done before and during 50µM 4-Aminopyridine (4-AP as an Ikur blocker. Results: Compared to control condition, CL of action potentials of SAN and VAN preparations had increased by 17.60 +/-2.9% and 35.90 +/-2.9%, respectively (P<0.05. Conclusion: It is possible to conclude that the Ikur was present in AVN and SAN and the effect of 4-AP on CL of action potential nodes was significantly different.

  4. Conducting Polymers

    Indian Academy of Sciences (India)

    would exhibit electronic conductivity, their conductivities (of compressed pellets) were indeed measured by others, and were found to be .... Polyaniline. Polyphenylene. Polypheny lene- vinylene. Table 1. G!NeRAl I ARTICl! structure. Maximum conductivity Stem Stability. Processability. ~. 1.5 x 105. Reacts with Film not n air.

  5. Nodal involvement in Hodgkin disease and non-Hodgkin lymphoma assessed by magnetic resonance

    International Nuclear Information System (INIS)

    Tesoro Tess, J.D.; Balzarini, L.; Ceglia, E.; Petrillo, R.; Musumeci, R.

    1990-01-01

    Magnetic Resonance Imaging (MRI) demonstrates a good capability in distinguishing nodal involvement in hodgkin disease and nonhodgkin lymphoma both in the chest and in the retroperitoneal areas the initial presentation of the disease. However CT and lymphangiography demonstrated comparable or superior values of accuracy and sensitivity. (H.W.) 4 refs.; 2 tabs

  6. A nodal Grean's function method of reactor core fuel management code, NGCFM2D

    International Nuclear Information System (INIS)

    Li Dongsheng; Yao Dong.

    1987-01-01

    This paper presents the mathematical model and program structure of the nodal Green's function method of reactor core fuel management code, NGCFM2D. Computing results of some reactor cores by NGCFM2D are analysed and compared with other codes

  7. Unbounded planar domains whose second nodal line does not touch the boundary

    Czech Academy of Sciences Publication Activity Database

    Freitas, P.; Krejčiřík, David

    2007-01-01

    Roč. 14, č. 1 (2007), s. 107-111 ISSN 1073-2780 R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Dirichlet Laplacian * eigenfunctions * nodal line Subject RIV: BA - General Mathematics Impact factor: 0.702, year: 2007

  8. Computation of Steady State Nodal Voltages for Fast Security Assessment in Power Systems

    DEFF Research Database (Denmark)

    Møller, Jakob Glarbo; Jóhannsson, Hjörtur; Østergaard, Jacob

    2014-01-01

    Development of a method for real-time assess-ment of post-contingency nodal voltages is introduced. Linear network theory is applied in an algorithm that utilizes Thevenin equivalent representation of power systems as seen from every voltage-controlled node in a network. The method is evaluated b...

  9. Short-term displacement and reproducibility of the breast and nodal targets under active breathing control

    NARCIS (Netherlands)

    Moran, Jean M.; Balter, James M.; Ben-David, Merav A.; Marsh, Robin B.; van Herk, Marcel; Pierce, Lori J.

    2007-01-01

    PURPOSE: The short-term displacement and reproducibility of the breast or chest wall, and the internal mammary (IM), infraclavicular (ICV), and supraclavicular (SCV) nodal regions have been assessed as a function of breath-hold state using an active breathing control (ABC) device for patients

  10. An error bound estimate and convergence of the Nodal-LTS N solution in a rectangle

    International Nuclear Information System (INIS)

    Hauser, Eliete Biasotto; Pazos, Ruben Panta; Tullio de Vilhena, Marco

    2005-01-01

    In this work, we report the mathematical analysis concerning error bound estimate and convergence of the Nodal-LTS N solution in a rectangle. For such we present an efficient algorithm, called LTS N 2D-Diag solution for Cartesian geometry

  11. Lymphoma no Hodgkin extra nodal in head and neck: value of CT

    International Nuclear Information System (INIS)

    Ramos Aguilar, A.; Romance Garcia, A.; Fuentes Lupianez, J.J.; Sanchez Lafuente, J.; Rodriguez Sanpedro, F.

    1994-01-01

    The head and neck regions is one of the most common sites of extra nodal non-Hodgkin's lymphoma (NHL). We studied 7 cases of NHL of head and neck using CT enhanced with intravenous contrast medium, analyzing the important role it plays in diagnosis, treatment planning and evaluation of the recurrence of these tumors. (Author)

  12. VARIANT: VARIational anisotropic nodal transport for multidimensional Cartesian and hexadgonal geometry calculation

    International Nuclear Information System (INIS)

    Palmiotti, G.; Carrico, C.B.; Lewis, E.E.

    1995-10-01

    The theoretical basis, implementation information and numerical results are presented for VARIANT (VARIational Anisotropic Neutron Transport), a FORTRAN module of the DIF3D code system at Argonne National Laboratory. VARIANT employs the variational nodal method to solve multigroup steady-state neutron diffusion and transport problems. The variational nodal method is a hybrid finite element method that guarantees nodal balance and permits spatial refinement through the use of hierarchical complete polynomial trial functions. Angular variables are expanded with complete or simplified P 1 , P 3 or P 5 5 spherical harmonics approximations with full anisotropic scattering capability. Nodal response matrices are obtained, and the within-group equations are solved by red-black or four-color iteration, accelerated by a partitioned matrix algorithm. Fission source and upscatter iterations strategies follow those of DIF3D. Two- and three-dimensional Cartesian and hexagonal geometries are implemented. Forward and adjoint eigenvalue, fixed source, gamma heating, and criticality (concentration) search problems may be performed

  13. A new communication scheme for the neutron diffusion nodal method in a distributed computing environment

    International Nuclear Information System (INIS)

    Kirk, B.L.; Azmy, Y.

    1994-01-01

    A modified scheme is developed for solving the two-dimensional nodal diffusion equations on distributed memory computers. The scheme is aimed at minimizing the volume of communication among processors while maximizing the tasks in parallel. Results show a significant improvement in parallel efficiency on the Intel iPSC/860 hypercube compared to previous algorithms

  14. Encapsulation of nodal cuttings and shoot tips for storage and exchange of cassava germplasm.

    Science.gov (United States)

    Danso, K E; Ford-Lloyd, B V

    2003-04-01

    We report the encapsulation of in vitro-derived nodal cuttings or shoot tips of cassava in 3% calcium alginate for storage and germplasm exchange purposes. Shoot regrowth was not significantly affected by the concentration of sucrose in the alginate matrix while root formation was. In contrast, increasing the sucrose concentration in the calcium chloride polymerisation medium significantly reduced regrowth from encapsulated nodal cuttings of accession TME 60444. Supplementing the alginate matrix with increased concentrations of 6-benzylaminopurine and alpha-naphthaleneacetic acid enhanced complete plant regrowth within 2 weeks. Furthermore, plant regrowth by encapsulated nodal cuttings and shoot tips was significantly affected by the duration of the storage period as shoot recovery decreased from almost 100% to 73.3% for encapsulated nodal cuttings and 94.4% to 60% for shoot tips after 28 days of storage. The high frequency of plant regrowth from alginate-coated micropropagules coupled with high viability percentage after 28 days of storage is highly encouraging for the exchange of cassava genetic resources. Such encapsulated micropropagules could be used as an alternative to synthetic seeds derived from somatic embryos.

  15. GDF3 is a BMP inhibitor that can activate Nodal signaling only at very high doses

    Science.gov (United States)

    Levine, Ariel J.; Levine, Zachary J.; Brivanlou, Ali H.

    2013-01-01

    Within the TGF-β superfamily, there are approximately forty ligands divided into two major branches: the TGF-β/Activin/Nodal ligands and the BMP/GDF ligands. We studied the ligand GDF3 and found that it inhibits signaling by its co-family members, the BMPs; however, GDF3 has been described by others to have Nodal-like activity. Here, we show that GDF3 can activate Nodal signaling, but only at very high doses and only upon mRNA over-expression. In contrast, GDF3 inhibits BMP signaling upon over-expression of GDF3 mRNA, as recombinant protein, and regardless of its dose. We therefore further characterized the mechanism through which GDF3 protein acts as a specific BMP inhibitor and found that the BMP inhibitory activity of GDF3 resides redundantly in the unprocessed, predominant form and in the mature form of the protein. These results confirm and extend the activity that we described for GDF3 and illuminate the experimental basis for the different observations of others. We suggest that GDF3 is either a bi-functional TGF-β ligand, or, more likely, that it is a BMP inhibitor that can artificially activate Nodal signaling under non-physiological conditions. PMID:18823971

  16. Barrier tunneling of the loop-nodal semimetal in the hyperhoneycomb lattice

    Science.gov (United States)

    Guan, Ji-Huan; Zhang, Yan-Yang; Lu, Wei-Er; Xia, Yang; Li, Shu-Shen

    2018-05-01

    We theoretically investigate the barrier tunneling in the 3D model of the hyperhoneycomb lattice, which is a nodal-line semimetal with a Dirac loop at zero energy. In the presence of a rectangular potential, the scattering amplitudes for different injecting states around the nodal loop are calculated, by using analytical treatments of the effective model, as well as numerical simulations of the tight binding model. In the low energy regime, states with remarkable transmissions are only concentrated in a small range around the loop plane. When the momentum of the injecting electron is coplanar with the nodal loop, nearly perfect transmissions can occur for a large range of injecting azimuthal angles if the potential is not high. For higher potential energies, the transmission shows a resonant oscillation with the potential, but still with peaks being perfect transmissions that do not decay with the potential width. These strikingly robust transports of the loop-nodal semimetal can be approximately explained by a momentum dependent Dirac Hamiltonian.

  17. Error quantification of the axial nodal diffusion kernel of the DeCART code

    International Nuclear Information System (INIS)

    Cho, J. Y.; Kim, K. S.; Lee, C. C.

    2006-01-01

    This paper is to quantify the transport effects involved in the axial nodal diffusion kernel of the DeCART code. The transport effects are itemized into three effects, the homogenization, the diffusion, and the nodal effects. A five pin model consisting of four fuel pins and one non-fuel pin is demonstrated to quantify the transport effects. The transport effects are analyzed for three problems, the single pin (SP), guide tube (GT) and control rod (CR) problems by replacing the non-fuel pin with the fuel pin, a guide-tube and a control rod pins, respectively. The homogenization and diffusion effects are estimated to be about -4 and -50 pcm for the eigenvalue, and less than 2 % for the node power. The nodal effect on the eigenvalue is evaluated to be about -50 pcm in the SP and GT problems, and +350 pcm in the CR problem. Regarding the node power, this effect induces about a 3 % error in the SP and GT problems, and about a 20 % error in the CR problem. The large power error in the CR problem is due to the plane thickness, and it can be decreased by using the adaptive plane size. From the error quantification, it is concluded that the homogenization and the diffusion effects are not controllable if DeCART maintains the diffusion kernel for the axial solution, but the nodal effect is controllable by introducing the adaptive plane size scheme. (authors)

  18. Depletion Calculations for MTR Core Using MCNPX and Multi-Group Nodal Diffusion Methods

    International Nuclear Information System (INIS)

    Jaradata, Mustafa K.; Park, Chang Je; Lee, Byungchul

    2013-01-01

    In order to maintain a self-sustaining steady-state chain reaction, more fuel than is necessary in order to maintain a steady state chain reaction must be loaded. The introduction of this excess fuel increases the net multiplication capability of the system. In this paper MCNPX and multi-group nodal diffusion theory will be used for depletion calculations for MTR core. The eigenvalue and power distribution in the core will be compared for different burnup. Multi-group nodal diffusion theory with combination of NEWT-TRITON system was used to perform depletion calculations for 3Χ3 MTR core. 2G and 6G approximations were used and compared with MCNPX results for 2G approximation the maximum difference from MCNPX was 40 mk and for 6G approximation was 6 mk which is comparable to the MCNPX results. The calculated power using nodal code was almost the same MCNPX results. Finally the results of the multi-group nodal theory were acceptable and comparable to the calculated using MCNPX

  19. A Nodal-independent and tissue-intrinsic mechanism controls heart-looping chirality

    NARCIS (Netherlands)

    Noel, E.S.; Verhoeven, M.; Lagendijk, A.K.; Tessadori, F.; Smith, K.; Choorapoikayil, S.; den Hertog, J.; Bakkers, J.

    2013-01-01

    Breaking left-right symmetry in bilateria is a major event during embryo development that is required for asymmetric organ position, directional organ looping and lateralized organ function in the adult. Asymmetric expression of Nodal-related genes is hypothesized to be the driving force behind

  20. On the relationship between some nodal schemes and the finite element method in static diffusion calculations

    International Nuclear Information System (INIS)

    Fedon-Magnaud, C.; Hennart, J.P.; Lautard, J.J.

    1983-03-01

    An unified formulation of non conforming finite elements with quadrature formula and simple nodal scheme is presented. The theoretical convergence is obtained for the previous scheme when the mesh is refined. Numerical tests are provided in order to bear out the theorical results

  1. A nodal method applied to a diffusion problem with generalized coefficients

    International Nuclear Information System (INIS)

    Laazizi, A.; Guessous, N.

    1999-01-01

    In this paper, we consider second order neutrons diffusion problem with coefficients in L ∞ (Ω). Nodal method of the lowest order is applied to approximate the problem's solution. The approximation uses special basis functions in which the coefficients appear. The rate of convergence obtained is O(h 2 ) in L 2 (Ω), with a free rectangular triangulation. (authors)

  2. A difference-equation formalism for the nodal domains of separable billiards

    Energy Technology Data Exchange (ETDEWEB)

    Manjunath, Naren; Samajdar, Rhine [Indian Institute of Science, Bangalore 560012 (India); Jain, Sudhir R., E-mail: srjain@barc.gov.in [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-09-15

    Recently, the nodal domain counts of planar, integrable billiards with Dirichlet boundary conditions were shown to satisfy certain difference equations in Samajdar and Jain (2014). The exact solutions of these equations give the number of domains explicitly. For complete generality, we demonstrate this novel formulation for three additional separable systems and thus extend the statement to all integrable billiards.

  3. The statistics of the points where nodal lines intersect a reference curve

    International Nuclear Information System (INIS)

    Aronovitch, Amit; Smilansky, Uzy

    2007-01-01

    We study the intersection points of a fixed planar curve Γ with the nodal set of a translationally invariant and isotropic Gaussian random field Ψ(r) and the zeros of its normal derivative across the curve. The intersection points form a discrete random process which is the object of this study. The field probability distribution function is completely specified by the correlation G(|r - r'|) = (Ψ(r)Ψ(r')). Given an arbitrary G(|r - r'|), we compute the two-point correlation function of the point process on the line, and derive other statistical measures (repulsion, rigidity) which characterize the short- and long-range correlations of the intersection points. We use these statistical measures to quantitatively characterize the complex patterns displayed by various kinds of nodal networks. We apply these statistics in particular to nodal patterns of random waves and of eigenfunctions of chaotic billiards. Of special interest is the observation that for monochromatic random waves, the number variance of the intersections with long straight segments grows like Lln L, as opposed to the linear growth predicted by the percolation model, which was successfully used to predict other long-range nodal properties of that field

  4. Prognostic value of nodal micrometastases in patients with cancer of the gastro-oesophageal junction

    NARCIS (Netherlands)

    Heeren, PAM; Kelder, W; Blondeel, [No Value; van Westreenen, HL; Hollema, H; Plukker, JT

    Aims. Aim of this study was to examine the presence and the prognostic impact of immunohistochemically identified nodal micrometastases in patients with astro-oesophageal junction (GEJ) carcinomas. Methods. Between January 1988 and December 2000, 148 patients underwent a radical (R0) resection with

  5. Bifurcation from infinity and nodal solutions of quasilinear elliptic differential equations

    Directory of Open Access Journals (Sweden)

    Bian-Xia Yang

    2014-01-01

    Full Text Available In this article, we establish a unilateral global bifurcation theorem from infinity for a class of $N$-dimensional p-Laplacian problems. As an application, we study the global behavior of the components of nodal solutions of the problem $$\\displaylines{ \\operatorname{div}(\\varphi_p(\

  6. Nodalization qualification process of the PSBVVER facility for the Cathare2 thermal-hydraulic code

    International Nuclear Information System (INIS)

    Del Nevo, A.; Araneo, D.; D'Auria, F.; Galassi, G.

    2004-01-01

    The present document deals with the nodalization qualification process of the PSB-VVER test facility for Cathare2 code. PSB-VVER facility is a 1/300 volume scale model of a VVER-1000, reactor installed at Electrogorsk Research and Engineering Centre in 1998. The version V1.5b of the Cathare2 code has been used. In order to evaluate the nodalization performance, the qualifying procedure set up at the DIMNP of Pisa University (UNIPI) has been applied that foresees two qualification levels: a 'steady state' level and an 'on transient' level. After the steady state behavior check of the nodalization, it has been preformed the on transient qualification the PSB-VVER test 2. It is a 11% equivalent break in Upper Plenum with the actuation of one high pressure injection system, connected to the hot leg of the loop 4, and 4 passive systems (ECCS hydro-accumulators), connected to the outlet plenum and to the inlet chamber of the downcomer. The low-pressure injection system is not available in the test. The goal of this paper is to demonstrate that the first step of the nodalization qualification adopted for the PSB test analyses is achieved and the PSB facility input deck is available and ready to use. The quantitative accuracy of the performed calculation has been evaluated by using the FFT-BM tool developed at the University of Pisa.(author)

  7. Clinical implementation of coverage probability planning for nodal boosting in locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Ramlov, Anne; Assenholt, Marianne S; Jensen, Maria F

    2017-01-01

    PURPOSE: To implement coverage probability (CovP) for dose planning of simultaneous integrated boost (SIB) of pathologic lymph nodes in locally advanced cervical cancer (LACC). MATERIAL AND METHODS: CovP constraints for SIB of the pathological nodal target (PTV-N) with a central dose peak...

  8. A new nodal kinetics method for analyzing fast control rod motions in nuclear reactor cores

    International Nuclear Information System (INIS)

    Kaya, S.; Yavuz, H.

    2001-01-01

    A new nodal kinetics approach is developed for analyzing large reactivity accidents in nuclear reactor cores. This method shows promising that it has capability of inspecting promt criticality transients and it gives comparable results with respect to those of other techniques. (orig.)

  9. Analysis of nodal coverage utilizing image guided radiation therapy for primary gynecologic tumor volumes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Faisal [University of Utah School of Medicine, Salt Lake City, UT (United States); Loma Linda University Medical Center, Department of Radiation Oncology, Loma Linda, CA (United States); Sarkar, Vikren; Gaffney, David K.; Salter, Bill [Department of Radiation Oncology, University of Utah, Salt Lake City, UT (United States); Poppe, Matthew M., E-mail: matthew.poppe@hci.utah.edu [Department of Radiation Oncology, University of Utah, Salt Lake City, UT (United States)

    2016-10-01

    Purpose: To evaluate radiation dose delivered to pelvic lymph nodes, if daily Image Guided Radiation Therapy (IGRT) was implemented with treatment shifts based on the primary site (primary clinical target volume [CTV]). Our secondary goal was to compare dosimetric coverage with patient outcomes. Materials and methods: A total of 10 female patients with gynecologic malignancies were evaluated retrospectively after completion of definitive intensity-modulated radiation therapy (IMRT) to their pelvic lymph nodes and primary tumor site. IGRT consisted of daily kilovoltage computed tomography (CT)-on-rails imaging fused with initial planning scans for position verification. The initial plan was created using Varian's Eclipse treatment planning software. Patients were treated with a median radiation dose of 45 Gy (range: 37.5 to 50 Gy) to the primary volume and 45 Gy (range: 45 to 64.8 Gy) to nodal structures. One IGRT scan per week was randomly selected from each patient's treatment course and re-planned on the Eclipse treatment planning station. CTVs were recreated by fusion on the IGRT image series, and the patient's treatment plan was applied to the new image set to calculate delivered dose. We evaluated the minimum, maximum, and 95% dose coverage for primary and nodal structures. Reconstructed primary tumor volumes were recreated within 4.7% of initial planning volume (0.9% to 8.6%), and reconstructed nodal volumes were recreated to within 2.9% of initial planning volume (0.01% to 5.5%). Results: Dosimetric parameters averaged less than 10% (range: 1% to 9%) of the original planned dose (45 Gy) for primary and nodal volumes on all patients (n = 10). For all patients, ≥99.3% of the primary tumor volume received ≥ 95% the prescribed dose (V95%) and the average minimum dose was 96.1% of the prescribed dose. In evaluating nodal CTV coverage, ≥ 99.8% of the volume received ≥ 95% the prescribed dose and the average minimum dose was 93%. In

  10. VALIDATION OF FULL CORE GEOMETRY MODEL OF THE NODAL3 CODE IN THE PWR TRANSIENT BENCHMARK PROBLEMS

    Directory of Open Access Journals (Sweden)

    Tagor Malem Sembiring

    2015-10-01

    Full Text Available ABSTRACT VALIDATION OF FULL CORE GEOMETRY MODEL OF THE NODAL3 CODE IN THE PWR TRANSIENT BENCHMARK PROBLEMS. The coupled neutronic and thermal-hydraulic (T/H code, NODAL3 code, has been validated in some PWR static benchmark and the NEACRP PWR transient benchmark cases. However, the NODAL3 code have not yet validated in the transient benchmark cases of a control rod assembly (CR ejection at peripheral core using a full core geometry model, the C1 and C2 cases.  By this research work, the accuracy of the NODAL3 code for one CR ejection or the unsymmetrical group of CRs ejection case can be validated. The calculations by the NODAL3 code have been carried out by the adiabatic method (AM and the improved quasistatic method (IQS. All calculated transient parameters by the NODAL3 code were compared with the reference results by the PANTHER code. The maximum relative difference of 16% occurs in the calculated time of power maximum parameter by using the IQS method, while the relative difference of the AM method is 4% for C2 case.  All calculation results by the NODAL3 code shows there is no systematic difference, it means the neutronic and T/H modules are adopted in the code are considered correct. Therefore, all calculation results by using the NODAL3 code are very good agreement with the reference results. Keywords: nodal method, coupled neutronic and thermal-hydraulic code, PWR, transient case, control rod ejection.   ABSTRAK VALIDASI MODEL GEOMETRI TERAS PENUH PAKET PROGRAM NODAL3 DALAM PROBLEM BENCHMARK GAYUT WAKTU PWR. Paket program kopel neutronik dan termohidraulika (T/H, NODAL3, telah divalidasi dengan beberapa kasus benchmark statis PWR dan kasus benchmark gayut waktu PWR NEACRP.  Akan tetapi, paket program NODAL3 belum divalidasi dalam kasus benchmark gayut waktu akibat penarikan sebuah perangkat batang kendali (CR di tepi teras menggunakan model geometri teras penuh, yaitu kasus C1 dan C2. Dengan penelitian ini, akurasi paket program

  11. The impact of nodal tumour burden on lymphoscintigraphic imaging in patients with melanomas

    Energy Technology Data Exchange (ETDEWEB)

    Kretschmer, Lutz; Bertsch, Hans Peter; Hellriegel, Simin; Thoms, Kai-Martin; Schoen, Michael Peter [Georg August University of Goettingen, Department of Dermatology, Venereology and Allergology, Goettingen (Germany); Bardzik, Pawel; Meller, Johannes; Sahlmann, Carsten Oliver [Georg-August-University of Goettingen, Department of Nuclear Medicine, Goettingen (Germany)

    2014-10-15

    To retrospectively study the influence of nodal tumour burden on lymphoscintigraphic imaging in 509 consecutive patients with melanomas. Bidirectional lymphatic drainage, the clear depiction of an afferent lymphatic vessel, time to depiction of the first sentinel lymph node (SLN) and number of depicted and excised nodes were recorded. Nodal tumour load was classified as SLN-negative, SLN micrometastases or macrometastases. In the overall population, using multivariate regression analysis, a short SLN depiction time was significantly associated with the depiction of a greater number of radioactive nodes, a short distance between the primary tumour site and the nodal basin, younger age and lower nodal tumour burden. The proportion of patients with clear depiction of an afferent lymphatic vessel depended on the nodal tumour load (46 % in SLN-negative patients, 57 % in SLN positive patients, and 69 % in patients with macrometastases; P = 0.009). Macrometastasis was significantly associated with delayed depiction of the first radioactive node and a greater number of depicted hotspots. In patients with clinically nonsuspicious nodes, i.e. the classical target group for SLN biopsy, clear depiction of an afferent vessel was significantly associated with a higher number of SLNs during dynamic acquisition, SLN micrometastasis and a higher overall number of metastatic lymph nodes after SLN biopsy plus completion lymphadenectomy. The excision of more than two SLNs did not increase the metastasis detection rate. In patients with bidirectional or tridirectional lymphatic drainage, the SLN positivity rates for the first, second and third basin were 25.4 %, 11.7 % and 0.0 %, respectively (P = 0.002). In patients with clinically nonsuspicious lymph nodes, clear depiction of an afferent lymph vessel may be a sign of micrometastasis. Macrometastasis is associated with prominent afferent vessels, delayed depiction of the first radioactive node and a higher number of depicted hotspots

  12. An approach to model reactor core nodalization for deterministic safety analysis

    Science.gov (United States)

    Salim, Mohd Faiz; Samsudin, Mohd Rafie; Mamat @ Ibrahim, Mohd Rizal; Roslan, Ridha; Sadri, Abd Aziz; Farid, Mohd Fairus Abd

    2016-01-01

    Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH1.6, stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D® computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M.

  13. Radiotherapy for esthesioneuroblastoma: is elective nodal irradiation warranted in the multimodality treatment approach?

    Science.gov (United States)

    Noh, O Kyu; Lee, Sang-wook; Yoon, Sang Min; Kim, Sung Bae; Kim, Sang Yoon; Kim, Chang Jin; Jo, Kyung Ja; Choi, Eun Kyung; Song, Si Yeol; Kim, Jong Hoon; Ahn, Seung Do

    2011-02-01

    The role of elective nodal irradiation (ENI) in radiotherapy for esthesioneuroblastoma (ENB) has not been clearly defined. We analyzed treatment outcomes of patients with ENB and the frequency of cervical nodal failure in the absence of ENI. Between August 1996 and December 2007, we consulted with 19 patients with ENB regarding radiotherapy. Initial treatment consisted of surgery alone in 2 patients; surgery and postoperative radiotherapy in 4; surgery and adjuvant chemotherapy in 1; surgery, postoperative radiotherapy, and chemotherapy in 3; and chemotherapy followed by radiotherapy or concurrent chemoradiotherapy in 5. Five patients did not receive planned radiotherapy because of disease progression. Including 2 patients who received salvage radiotherapy, 14 patients were treated with radiotherapy. Elective nodal irradiation was performed in 4 patients with high-risk factors, including 3 with cervical lymph node metastasis at presentation. Fourteen patients were analyzable, with a median follow-up of 27 months (range, 7-64 months). The overall 3-year survival rate was 73.4%. Local failure occurred in 3 patients (21.4%), regional cervical failure in 3 (21.4%), and distant failure in 2 (14.3%). No cervical nodal failure occurred in patients treated with combined systemic chemotherapy regardless of ENI. Three cervical failures occurred in the 4 patients treated with ENI or neck dissection (75%), none of whom received systemic chemotherapy. ENI during radiotherapy for ENB seems to play a limited role in preventing cervical nodal failure. Omitting ENI may be an option if patients are treated with a combination of radiotherapy and chemotherapy. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. An approach to model reactor core nodalization for deterministic safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Mohd Faiz, E-mail: mohdfaizs@tnb.com.my; Samsudin, Mohd Rafie, E-mail: rafies@tnb.com.my [Nuclear Energy Department, Regulatory Economics & Planning Division, Tenaga Nasional Berhad (Malaysia); Mamat Ibrahim, Mohd Rizal, E-mail: m-rizal@nuclearmalaysia.gov.my [Prototypes & Plant Development Center, Malaysian Nuclear Agency (Malaysia); Roslan, Ridha, E-mail: ridha@aelb.gov.my; Sadri, Abd Aziz [Nuclear Installation Divisions, Atomic Energy Licensing Board (Malaysia); Farid, Mohd Fairus Abd [Reactor Technology Center, Malaysian Nuclear Agency (Malaysia)

    2016-01-22

    Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH{sub 1.6}, stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D{sup ®} computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M.

  15. An approach to model reactor core nodalization for deterministic safety analysis

    International Nuclear Information System (INIS)

    Salim, Mohd Faiz; Samsudin, Mohd Rafie; Mamat Ibrahim, Mohd Rizal; Roslan, Ridha; Sadri, Abd Aziz; Farid, Mohd Fairus Abd

    2016-01-01

    Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH 1.6 , stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D ® computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M

  16. Combined-modality therapy for patients with regional nodal metastases from melanoma

    International Nuclear Information System (INIS)

    Ballo, Matthew T.; Ross, Merrick I.; Cormier, Janice N.; Myers, Jeffrey N.; Lee, Jeffrey E.; Gershenwald, Jeffrey E.; Hwu, Patrick; Zagars, Gunar K.

    2006-01-01

    Purpose: To evaluate the outcome and patterns of failure for patients with nodal metastases from melanoma treated with combined-modality therapy. Methods and Materials: Between 1983 and 2003, 466 patients with nodal metastases from melanoma were managed with lymphadenectomy and radiation, with or without systemic therapy. Surgery was a therapeutic procedure for clinically apparent nodal disease in 434 patients (regionally advanced nodal disease). Adjuvant radiation was generally delivered with a hypofractionated regimen. Adjuvant systemic therapy was delivered to 154 patients. Results: With a median follow-up of 4.2 years, 252 patients relapsed and 203 patients died of progressive disease. The actuarial 5-year disease-specific, disease-free, and distant metastasis-free survival rates were 49%, 42%, and 44%, respectively. By multivariate analysis, increasing number of involved lymph nodes and primary ulceration were associated with an inferior 5-year actuarial disease-specific and distant metastasis-free survival. Also, the number of involved lymph nodes was associated with the development of brain metastases, whereas thickness was associated with lung metastases, and primary ulceration was associated with liver metastases. The actuarial 5-year regional (in-basin) control rate for all patients was 89%, and on multivariate analysis there were no patient or disease characteristics associated with inferior regional control. The risk of lymphedema was highest for those patients with groin lymph node metastases. Conclusions: Although regional nodal disease can be satisfactorily controlled with lymphadenectomy and radiation, the risk of distant metastases and melanoma death remains high. A management approach to these patients that accounts for the competing risks of distant metastases, regional failure, and long-term toxicity is needed

  17. Radiotherapy for Esthesioneuroblastoma: Is Elective Nodal Irradiation Warranted in the Multimodality Treatment Approach?

    International Nuclear Information System (INIS)

    Noh, O Kyu; Lee, Sang-wook; Yoon, Sang Min; Kim, Sung Bae; Kim, Sang Yoon; Kim, Chang Jin; Jo, Kyung Ja; Choi, Eun Kyung; Song, Si Yeol; Kim, Jong Hoon; Ahn, Seung Do

    2011-01-01

    Purpose: The role of elective nodal irradiation (ENI) in radiotherapy for esthesioneuroblastoma (ENB) has not been clearly defined. We analyzed treatment outcomes of patients with ENB and the frequency of cervical nodal failure in the absence of ENI. Methods and Materials: Between August 1996 and December 2007, we consulted with 19 patients with ENB regarding radiotherapy. Initial treatment consisted of surgery alone in 2 patients; surgery and postoperative radiotherapy in 4; surgery and adjuvant chemotherapy in 1; surgery, postoperative radiotherapy, and chemotherapy in 3; and chemotherapy followed by radiotherapy or concurrent chemoradiotherapy in 5. Five patients did not receive planned radiotherapy because of disease progression. Including 2 patients who received salvage radiotherapy, 14 patients were treated with radiotherapy. Elective nodal irradiation was performed in 4 patients with high-risk factors, including 3 with cervical lymph node metastasis at presentation. Results: Fourteen patients were analyzable, with a median follow-up of 27 months (range, 7-64 months). The overall 3-year survival rate was 73.4%. Local failure occurred in 3 patients (21.4%), regional cervical failure in 3 (21.4%), and distant failure in 2 (14.3%). No cervical nodal failure occurred in patients treated with combined systemic chemotherapy regardless of ENI. Three cervical failures occurred in the 4 patients treated with ENI or neck dissection (75%), none of whom received systemic chemotherapy. Conclusions: ENI during radiotherapy for ENB seems to play a limited role in preventing cervical nodal failure. Omitting ENI may be an option if patients are treated with a combination of radiotherapy and chemotherapy.

  18. Role of CT/PET in predicting nodal disease in head and neck cancers

    International Nuclear Information System (INIS)

    Singham, S.; Iyer, G.; Clark, J.

    2009-01-01

    Full text:Introduction: Pre-treatment evaluation of the presence of cervical nodal metastases is important in head and neck cancers and has major prognostic implications. In this study, we aim to determine the accuracy of CT/PET as a tool for identifying such metastases. Methods: All patients from Royal Prince Alfred and Liverpool Hospitals, who underwent CT/PET for any cancer arising from the head and neck, and who underwent subsequent surgery (which included a neck dissection) within 8 weeks of the CT/PET were included. Nodal staging was undertaken by utilising imaging-based nodal classification, and comparison with pathologic data from the surgical specimen was made. PET was considered positive if the SUV was greater than 2. Results: We identified 111 patients from the above criteria. 80 of such patients were treated for squamous cell carcinoma (SCC). CT/PET identified unsuspected metastatic disease in 6 patients. Correlation of CT/PET findings and the presence of disease at the primary site: sensitivity: 98%, specificity: 93%, positive predictive value (PPV): 98% and negative predictive value (NPV): 93%. Correlating CT/PET findings with the presence of nodal disease at any level: sensitivity: 95%, specificity: 88%, PPV: 95% and NPV: 88%. CT/PET was anatomically accurate in predicting the site of metastases in 62/74 (84%). Conclusion: PET is accurate in predicting both presence of nodal metastases and the level of involvement. CT/PET should be undertaken as a pre-operative tool to assist in planning the extent of surgery required in head and neck cancers.

  19. An adaptive mesh refinement approach for average current nodal expansion method in 2-D rectangular geometry

    International Nuclear Information System (INIS)

    Poursalehi, N.; Zolfaghari, A.; Minuchehr, A.

    2013-01-01

    Highlights: ► A new adaptive h-refinement approach has been developed for a class of nodal method. ► The resulting system of nodal equations is more amenable to efficient numerical solution. ► The benefit of the approach is reducing computational efforts relative to the uniform fine mesh modeling. ► Spatially adaptive approach greatly enhances the accuracy of the solution. - Abstract: The aim of this work is to develop a spatially adaptive coarse mesh strategy that progressively refines the nodes in appropriate regions of domain to solve the neutron balance equation by zeroth order nodal expansion method. A flux gradient based a posteriori estimation scheme has been utilized for checking the approximate solutions for various nodes. The relative surface net leakage of nodes has been considered as an assessment criterion. In this approach, the core module is called in by adaptive mesh generator to determine gradients of node surfaces flux to explore the possibility of node refinements in appropriate regions and directions of the problem. The benefit of the approach is reducing computational efforts relative to the uniform fine mesh modeling. For this purpose, a computer program ANRNE-2D, Adaptive Node Refinement Nodal Expansion, has been developed to solve neutron diffusion equation using average current nodal expansion method for 2D rectangular geometries. Implementing the adaptive algorithm confirms its superiority in enhancing the accuracy of the solution without using fine nodes throughout the domain and increasing the number of unknown solution. Some well-known benchmarks have been investigated and improvements are reported

  20. Development of an environment-insensitive PWR radial reflector model applicable to modern nodal reactor analysis method

    International Nuclear Information System (INIS)

    Mueller, E.M.

    1989-05-01

    This research is concerned with the development and analysis of methods for generating equivalent nodal diffusion parameters for the radial reflector of a PWR. The requirement that the equivalent reflector data be insensitive to changing core conditions is set as a principle objective. Hence, the environment dependence of the currently most reputable nodal reflector models, almost all of which are based on the nodal equivalence theory homgenization methods of Koebke and Smith, is investigated in detail. For this purpose, a special 1-D nodal equivalence theory reflector model, called the NGET model, is developed and used in 1-D and 2-D numerical experiments. The results demonstrate that these modern radial reflector models exhibit sufficient sensitivity to core conditions to warrant the development of alternative models. A new 1-D nodal reflector model, which is based on a novel combination of the nodal equivalence theory and the response matrix homogenization methods, is developed. Numerical results varify that this homogenized baffle/reflector model, which is called the NGET-RM model, is highly insensitive to changing core conditions. It is also shown that the NGET-RM model is not inferior to any of the existing 1-D nodal reflector models and that it has features which makes it an attractive alternative model for multi-dimensional reactor analysis. 61 refs., 40 figs., 36 tabs

  1. Validation of full core geometry model of the NODAL3 code in the PWR transient Benchmark problems

    International Nuclear Information System (INIS)

    T-M Sembiring; S-Pinem; P-H Liem

    2015-01-01

    The coupled neutronic and thermal-hydraulic (T/H) code, NODAL3 code, has been validated in some PWR static benchmark and the NEACRP PWR transient benchmark cases. However, the NODAL3 code have not yet validated in the transient benchmark cases of a control rod assembly (CR) ejection at peripheral core using a full core geometry model, the C1 and C2 cases. By this research work, the accuracy of the NODAL3 code for one CR ejection or the unsymmetrical group of CRs ejection case can be validated. The calculations by the NODAL3 code have been carried out by the adiabatic method (AM) and the improved quasistatic method (IQS). All calculated transient parameters by the NODAL3 code were compared with the reference results by the PANTHER code. The maximum relative difference of 16 % occurs in the calculated time of power maximum parameter by using the IQS method, while the relative difference of the AM method is 4 % for C2 case. All calculation results by the NODAL3 code shows there is no systematic difference, it means the neutronic and T/H modules are adopted in the code are considered correct. Therefore, all calculation results by using the NODAL3 code are very good agreement with the reference results. (author)

  2. Heat conduction

    International Nuclear Information System (INIS)

    Grigull, U.; Sandner, H.

    1984-01-01

    Included are discussions of rates of heat transfer by conduction, the effects of varying and changing properties, thermal explosions, distributed heat sources, moving heat sources, and non-steady three-dimensional conduction processes. Throughout, the importance of thinking both numerically and symbolically is stressed, as this is essential to the development of the intuitive understanding of numerical values needed for successful designing. Extensive tables of thermophysical properties, including thermal conductivity and diffusivity, are presented. Also included are exact and approximate solutions to many of the problems that arise in practical situations

  3. Supra-Hisian Conduction Block as an Unusual Presenting Feature of Takotsubo Cardiomyopathy.

    Science.gov (United States)

    Prabhu, Mukund Aravind; Pai, Praveen Gopalakrishna; Vupputuri, Anjith; Shekhar, Saritha; Harikrishnan, Madhavankutty Santhakumari; Kumaraswamy, Natarajan Umayammal

    2017-05-01

    Atrioventricular (AV) block is rare in Takotsubo cardiomyopathy (TC). A 66-year-old female presented with fatigue. Her electrocardiogram revealed 3:2 Mobitz Type II AV block, confirmed to be supra-Hisian by electrophysiological study. Echocardiogram and left ventricular angiogram showed moderate left ventricular dysfunction and apical ballooning, whereas coronary angiogram revealed mildly ectatic coronaries. At 2 weeks AV block persisted, needing permanent pacemaker implantation. At 1-month follow-up, she had normal ventricular function and no AV block. Delayed recovery of AV conduction is possible in TC, thus implying to wait for a longer period before implanting a pacemaker. © 2016 Wiley Periodicals, Inc.

  4. [Infections as a preoperative problem in patients with tetralogy of Fallot (TOF) associated with complete atrioventricular canal septal defect (AVC)].

    Science.gov (United States)

    Szydłowski, Lesław; Marek-Szydłowska, Teresa; Rudziński, Andrzej; Pajak, Jacek; Morka, Jacek; Stołtny, Ludwik

    2004-01-01

    Tetralogy of Fallot (TOF) coexisting with atrioventricular canal septal defect (AVC) is a rare combination of anomalies. Additionally, in cases with concomitant Down syndrome, recurrent infections can be a serious problem in patients (pts.) waiting for cardiosurgery treatment. The purpose of the study was an analysis of types of infections and other factors complicating the preoperative period in those patients. The study group consisted of 17 pts. with TOF and AVC aged from 1 day to 9 years (mean 9.4 month). In this group there were 11 pts. with Down syndrome. All of them were subjected to physical examinations, blood analysis, ECG, chest X-ray and echocardiographic study. Additionally, in 8 pts. we performed catheterization. The signs of different types of infection were analyzed and results were compared in two groups: with and without Down syndrome. The differences were observed in the frequency of recurrent or chronic infections (21 v/s 4), time of hospitalization before surgery (17 v/s 9 days), necessity (11 v/s 3) and duration of antibiotic therapy (19 v/s 7 days) in the two studied groups. Elevated body temperature of unknown etiology was noted in 8 cases with Down syndrome, compared to 1 patient without trisomy 21. Also, the children with Down syndrome had to wait 11 days longer (19 v/s 8) for discharge after operation. Infections in children with TOF, AVC and Down syndrome significantly complicate the natural course of this anomaly. Prolonged preoperation time is characteristic of Down syndrome pts. compared to patients without chromosomal abnormalities.

  5. Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2.

    Science.gov (United States)

    Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M; Cai, Chen-Leng

    2011-12-15

    During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Development and qualification of a thermal-hydraulic nodalization for modeling station blackout accident in PSB-VVER test facility

    Energy Technology Data Exchange (ETDEWEB)

    Saghafi, Mahdi [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Ghofrani, Mohammad Bagher, E-mail: ghofrani@sharif.edu [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); D’Auria, Francesco [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, San Piero a Grado, Pisa (Italy)

    2016-07-15

    Highlights: • A thermal-hydraulic nodalization for PSB-VVER test facility has been developed. • Station blackout accident is modeled with the developed nodalization in MELCOR code. • The developed nodalization is qualified at both steady state and transient levels. • MELCOR predictions are qualitatively and quantitatively in acceptable range. • Fast Fourier Transform Base Method is used to quantify accuracy of code predictions. - Abstract: This paper deals with the development of a qualified thermal-hydraulic nodalization for modeling Station Black-Out (SBO) accident in PSB-VVER Integral Test Facility (ITF). This study has been performed in the framework of a research project, aiming to develop an appropriate accident management support tool for Bushehr nuclear power plant. In this regard, a nodalization has been developed for thermal-hydraulic modeling of the PSB-VVER ITF by MELCOR integrated code. The nodalization is qualitatively and quantitatively qualified at both steady-state and transient levels. The accuracy of the MELCOR predictions is quantified in the transient level using the Fast Fourier Transform Base Method (FFTBM). FFTBM provides an integral representation for quantification of the code accuracy in the frequency domain. It was observed that MELCOR predictions are qualitatively and quantitatively in the acceptable range. In addition, the influence of different nodalizations on MELCOR predictions was evaluated and quantified using FFTBM by developing 8 sensitivity cases with different numbers of control volumes and heat structures in the core region and steam generator U-tubes. The most appropriate case, which provided results with minimum deviations from the experimental data, was then considered as the qualified nodalization for analysis of SBO accident in the PSB-VVER ITF. This qualified nodalization can be used for modeling of VVER-1000 nuclear power plants when performing SBO accident analysis by MELCOR code.

  7. Electrical Conductivity.

    Science.gov (United States)

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Conduct Disorder

    Science.gov (United States)

    ... objections runs away from home often truant from school Children who exhibit these behaviors should receive a comprehensive evaluation by an experience mental health professional. Many children with a conduct disorder may ...

  9. Patterns of practice of regional nodal irradiation in breast cancer: results of the European Organization for Research and Treatment of Cancer (EORTC) NOdal Radiotherapy (NORA) survey.

    Science.gov (United States)

    Belkacemi, Y; Kaidar-Person, O; Poortmans, P; Ozsahin, M; Valli, M-C; Russell, N; Kunkler, I; Hermans, J; Kuten, A; van Tienhoven, G; Westenberg, H

    2015-03-01

    Predicting outcome of breast cancer (BC) patients based on sentinel lymph node (SLN) status without axillary lymph node dissection (ALND) is an area of uncertainty. It influences the decision-making for regional nodal irradiation (RNI). The aim of the NORA (NOdal RAdiotherapy) survey was to examine the patterns of RNI. A web-questionnaire, including several clinical scenarios, was distributed to 88 EORTC-affiliated centers. Responses were received between July 2013 and January 2014. A total of 84 responses were analyzed. While three-dimensional (3D) radiotherapy (RT) planning is carried out in 81 (96%) centers, nodal areas are delineated in only 51 (61%) centers. Only 14 (17%) centers routinely link internal mammary chain (IMC) and supraclavicular node (SCN) RT indications. In patients undergoing total mastectomy (TM) with ALND, SCN-RT is recommend by 5 (6%), 53 (63%) and 51 (61%) centers for patients with pN0(i+), pN(mi) and pN1, respectively. Extra-capsular extension (ECE) is the main factor influencing decision-making RNI after breast conserving surgery (BCS) and TM. After primary systemic therapy (PST), 49 (58%) centers take into account nodal fibrotic changes in ypN0 patients for RNI indications. In ypN0 patients with inner/central tumors, 23 (27%) centers indicate SCN-RT and IMC-RT. In ypN1 patients, SCN-RT is delivered by less than half of the centers in patients with ypN(i+) and ypN(mi). Twenty-one (25%) of the centers recommend ALN-RT in patients with ypN(mi) or 1-2N+ after ALND. Seventy-five (90%) centers state that age is not considered a limiting factor for RNI. The NORA survey is unique in evaluating the impact of SLNB/ALND status on adjuvant RNI decision-making and volumes after BCS/TM with or without PST. ALN-RT is often indicated in pN1 patients, particularly in the case of ECE. Besides the ongoing NSABP-B51/RTOG and ALLIANCE trials, NORA could help to design future specific RNI trials in the SLNB era without ALND in patients receiving or not PST.

  10. Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

    Science.gov (United States)

    Chen, Kang; Mao, Ye; Liu, Shao-hua; Wu, Qiong; Luo, Qing-zhi; Pan, Wen-qi; Jin, Qi; Zhang, Ning; Ling, Tian-you; Chen, Ying; Gu, Gang; Shen, Wei-feng; Wu, Li-qun

    2014-06-01

    We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, Pfunction capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

  11. Mapping of selected markets with Nodal pricing or similar systems. Australia, New Zealand and North American power markets

    Energy Technology Data Exchange (ETDEWEB)

    Mathiesen, Vivi (ed.)

    2011-07-01

    This report shows that the principals of nodal pricing can be implemented in different ways. A common denominator for markets with nodal pricing is a central market based nodal dispatch, where prices and flows are determined simultaneously close to real time. This stands apart from the European market design, which is based on a highly simplified version of the grid, and a physical point auction day ahead. Congestion management is handled by the TSO during the operational hour and not through the market as is the case in nodal pricing systems. Nodal pricing yields optimal dispatch and congestion management through the market, and as such an optimal utilisation of energy generation and network. However, whether this short term optimisation delivers the highest overall efficiency for the market in terms of competition in the wholesale and retail market, price discovery, possibilities for hedging, long term price signals etc. is difficult to determine. The markets investigated handle issues such as market power, risk management, investment signals and retail markets in very different ways. New Zealand and PJM are examples of markets with full nodal pricing, i.e. both generators and the demand side are exposed to nodal prices. The PJM market has more 'additional features' than the New Zealand market. Examples of these are separate capacity market to trigger investments in generation and generator price caps to deal with situations of market power. In addition PJM offers liquid and mature markets for risk management, such as aggregates of nodes where market participant can chose to be settled (rather than to be settled directly at the node). A general finding though, seems to be that risk management at peripheral nodes is challenging in nodal markets, particularly for independent retailers. In New Zealand generators and retailers were permitted to 'reintegrate' in order to cope with the nodal prices. The Australian market has central market based

  12. Pattern of Progression after Stereotactic Body Radiotherapy for Oligometastatic Prostate Cancer Nodal Recurrences.

    Science.gov (United States)

    Ost, P; Jereczek-Fossa, B A; Van As, N; Zilli, T; Tree, A; Henderson, D; Orecchia, R; Casamassima, F; Surgo, A; Miralbell, R; De Meerleer, G

    2016-09-01

    To report the relapse pattern of stereotactic body radiotherapy (SBRT) for oligorecurrent nodal prostate cancer (PCa). PCa patients with ≤3 lymph nodes (N1/M1a) at the time of recurrence were treated with SBRT. SBRT was defined as a radiotherapy dose of at least 5 Gy per fraction to a biological effective dose of at least 80 Gy to all metastatic sites. Distant progression-free survival was defined as the time interval between the first day of SBRT and appearance of new metastatic lesions, outside the high-dose region. Relapses after SBRT were recorded and compared with the initially treated site. Secondary end points were local control, time to palliative androgen deprivation therapy and toxicity scored using the Common Terminology Criteria for Adverse Events v4.0. Overall, 89 metastases were treated in 72 patients. The median distant progression-free survival was 21 months (95% confidence interval 16-25 months) with 88% of patients having ≤3 metastases at the time of progression. The median time from first SBRT to the start of palliative androgen deprivation therapy was 44 months (95% confidence interval 17-70 months). Most relapses (68%) occurred in nodal regions. Relapses after pelvic nodal SBRT (n = 36) were located in the pelvis (n = 14), retroperitoneum (n = 1), pelvis and retroperitoneum (n = 8) or in non-nodal regions (n = 13). Relapses after SBRT for extrapelvic nodes (n = 5) were located in the pelvis (n = 1) or the pelvis and retroperitoneum (n = 4). Late grade 1 and 2 toxicity was observed in 17% (n = 12) and 4% of patients (n = 3). SBRT for oligometastatic PCa nodal recurrences is safe. Most subsequent relapses are again nodal and oligometastatic. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  13. Regeneration of three sweet potato (Ipomea batatas (L.)) accessions via meristem, Nodal and callus induction

    International Nuclear Information System (INIS)

    Addae-Frimpomaah, F.

    2012-11-01

    In vitro regeneration of three sweet potato accessions UE007, UK-BNARI and SA-BNARI using meristem, nodal cuttings or callus induction was studied. Meristematic explants cultured on Murashige and Skoog (1962) basal medium supplemented with low concentration of benzylaminopurine (BAP) or kinetin resulted in callus with or without shoot development which delayed shoot emergence. The degree of callus development increased as the concentration of the cytokinin in the culture medium increased. Although, callus development was comparatively lower on kinetin amended medium than BAP amended medium, Murashige and Skoog medium supplemented with 0.25mg/1BAP had the highest shoot induction (80%). For further differentiation of callus or shoots into distinct stem and leaves, the culture were transferred into fresh MS medium supplemented with 0.25mg/1 BAP, 0.1 mg/1 NAA and 0.1 mg/1 Gibberellic acid (GA 3 . To overcome the delay in shoot initiation using meristem culture, nodal cuttings of sweet potato were used as explants and cultured on MS medium amended with 0.3 - 0.9mg/1 BAP. All explants cultured on 0.3 or 0.6mg/1 BAP developed shoots. Furthermore, liquid MS medium amended with 0.25mg/1 BAP, 0.1mg/I NAA, and 0.1mg/1 GA 3 also enhanced early shoot development from nodal cutting explants compared to solid culture. Post flask acclimatisation of meristem or nodal cutting-derived plantlets showed that meristem derived plantlets were better acclimatised than nodal cutting plants due to vigorous root development leading to higher percentage survival in pots and subsequent tuber production. Callusogenesis was achieved when leaf lobe explants were cultured on CLC/ Ipomoea medium supplemented with 1.0 - 4.0mg/1 2,4-D with 4.0mg/1 2,4-D being the optimal concentration. However, the calli were non-embryogenic and therefore could not produce embryos when transferred to 0.1mg/1 BAP amended medium but rather produced either single or multiple shoots. The highest percentage shoot (83

  14. Involved-field radiotherapy (IFRT) versus elective nodal irradiation (ENI) in combination with concurrent chemotherapy for 239 esophageal cancers: a single institutional retrospective study

    International Nuclear Information System (INIS)

    Yamashita, Hideomi; Takenaka, Ryousuke; Omori, Mami; Imae, Toshikazu; Okuma, Kae; Ohtomo, Kuni; Nakagawa, Keiichi

    2015-01-01

    This retrospective study on early and locally advanced esophageal cancer was conducted to evaluate locoregional failure and its impact on survival by comparing involved field radiotherapy (IFRT) with elective nodal irradiation (ENI) in combination with concurrent chemotherapy. We assessed all patients with esophageal cancer of stages I-IV treated with definitive radiotherapy from June 2000 to March 2014. Between 2000 and 2011, ENI was used for all cases excluding high age cases. After Feb 2011, a prospective study about IFRT was started, and therefore IFRT was used since then for all cases. Concurrent chemotherapy regimen was nedaplatin (80 mg/m 2 at D1 and D29) and 5-fluorouracil (800 mg/m 2 at D1-4 and D29-32). Of the 239 consecutive patients assessed (120 ENI vs. 119 IFRT), 59 patients (24.7 %) had stage IV disease and all patients received at least one cycle of chemotherapy. The median follow-up time for survivors was 34.0 months. There were differences in 3-year local control (44.8 % vs. 55.5 %, p = 0.039), distant control (53.8 % vs. 69.9 %, p = 0.021) and overall survival (34.8 % vs. 51.6 %, p = 0.087) rates between ENI vs. IFRT, respectively. Patients treated with IFRT (8 %) demonstrated a significantly lower risk (p = 0.047) of high grade late toxicities than with ENI (16 %). IFRT did not increase the risk of initially uninvolved or isolated nodal failures (27.5 % in ENI and 13.4 % in IFRT). Nodal failure rates in clinically uninvolved nodal stations were not increased with IFRT when compared to ENI. IFRT also resulted in significantly decreased esophageal toxicity, suggesting that IFRT may allow for integration of concurrent systemic chemotherapy in a greater proportion of patients. Both tendencies of improved loco-regional progression-free survival and a significant increased overall survival rate favored the IFRT arm over the ENI arm in this study

  15. Involved-field radiotherapy (IFRT) versus elective nodal irradiation (ENI) in combination with concurrent chemotherapy for 239 esophageal cancers: a single institutional retrospective study.

    Science.gov (United States)

    Yamashita, Hideomi; Takenaka, Ryousuke; Omori, Mami; Imae, Toshikazu; Okuma, Kae; Ohtomo, Kuni; Nakagawa, Keiichi

    2015-08-14

    This retrospective study on early and locally advanced esophageal cancer was conducted to evaluate locoregional failure and its impact on survival by comparing involved field radiotherapy (IFRT) with elective nodal irradiation (ENI) in combination with concurrent chemotherapy. We assessed all patients with esophageal cancer of stages I-IV treated with definitive radiotherapy from June 2000 to March 2014. Between 2000 and 2011, ENI was used for all cases excluding high age cases. After Feb 2011, a prospective study about IFRT was started, and therefore IFRT was used since then for all cases. Concurrent chemotherapy regimen was nedaplatin (80 mg/m(2) at D1 and D29) and 5-fluorouracil (800 mg/m(2) at D1-4 and D29-32). Of the 239 consecutive patients assessed (120 ENI vs. 119 IFRT), 59 patients (24.7%) had stage IV disease and all patients received at least one cycle of chemotherapy. The median follow-up time for survivors was 34.0 months. There were differences in 3-year local control (44.8% vs. 55.5%, p = 0.039), distant control (53.8% vs. 69.9%, p = 0.021) and overall survival (34.8% vs. 51.6%, p = 0.087) rates between ENI vs. IFRT, respectively. Patients treated with IFRT (8 %) demonstrated a significantly lower risk (p = 0.047) of high grade late toxicities than with ENI (16%). IFRT did not increase the risk of initially uninvolved or isolated nodal failures (27.5% in ENI and 13.4% in IFRT). Nodal failure rates in clinically uninvolved nodal stations were not increased with IFRT when compared to ENI. IFRT also resulted in significantly decreased esophageal toxicity, suggesting that IFRT may allow for integration of concurrent systemic chemotherapy in a greater proportion of patients. Both tendencies of improved loco-regional progression-free survival and a significant increased overall survival rate favored the IFRT arm over the ENI arm in this study.

  16. Cardiac Conduction System: Delineation of Anatomic Landmarks With Multidetector CT

    Directory of Open Access Journals (Sweden)

    Farhood Saremi

    2009-11-01

    Full Text Available Major components of the cardiac conduction system including the sinoatrial node (SAN, atrioventricular node (AVN, the His Bundle, and the right and left bundle branches are too small to be directly visualized by multidetector CT (MDCT given the limited spatial resolution of current scanners. However, the related anatomic landmarks and variants of this system a well as the areas with special interest to electrophysiologists can be reliably demonstrated by MDCT. Some of these structures and landmarks include the right SAN artery, right atrial cavotricuspid isthmus, Koch triangle, AVN artery, interatrial muscle bundles, and pulmonary veins. In addition, MDCT has an imperative role in demarcating potential arrhythmogenic structures. The aim of this review will be to assess the extent at which MDCT can outline the described anatomic landmarks and therefore provide crucial information used in clinical practice.

  17. Development and Validation of NODAL-LAMBDA Program for the Calculation of the Sub-criticality of LAMDA MODES By Nodal Methods in BWR reactors

    International Nuclear Information System (INIS)

    Munoz-Cobo, J. L.; Merino, R.; Escriva, A.; Melara, J.; Concejal, A.

    2014-01-01

    We have developed a 3D code with two energy groups and diffusion theory that is capable of calculating eigenvalues lambda of a BWR reactor using nodal methods and boundary conditions that calculates ALBEDO NODAL-LAMBDA from the properties of the reflector code itself. The code calculates the sub-criticality of the first harmonic, which is involved in the stability against oscillations reactor out of phase, and which is needed for calculating the decay rate for data out of phase oscillations. The code is very fast and in a few seconds is able to make a calculation of the first eigenvalues and eigenvectors, discretized solving the problem with different matrix elements zero. The code uses the LAPACK and ARPACK libraries. It was necessary to modify the LAPACK library to perform various operations with five non-diagonal matrices simultaneously in order to reduce the number of calls to bookstores and simplify the procedure for calculating the matrices in compressed format CSR. The code is validated by comparing it with the results for SIMULATE different cases and making 3D BENCHMAR of the IAEA. (Author)

  18. Building the nodal nuclear data dependences in a many-dimensional state-variable space

    International Nuclear Information System (INIS)

    Dufek, Jan

    2011-01-01

    Highlights: → The Abstract and Introduction are revised to reflect reviewers' comments. → Section is revised and simplified. → The third paragraph in Section is revised. → All typos are fixed. - Abstract: We present new methods for building the polynomial-regression based nodal nuclear data models. The data models can reflect dependences on a large number of state variables, and they can consider various history effects. Suitable multivariate polynomials that approximate the nodal data dependences are identified efficiently in an iterative manner. The history effects are analysed using a new sampling scheme for lattice calculations where the traditional base burnup and branch calculations are replaced by a large number of diverse burnup histories. The total number of lattice calculations is controlled so that the data models are built to a required accuracy.

  19. An analytical nodal method for time-dependent one-dimensional discrete ordinates problems

    International Nuclear Information System (INIS)

    Barros, R.C. de

    1992-01-01

    In recent years, relatively little work has been done in developing time-dependent discrete ordinates (S N ) computer codes. Therefore, the topic of time integration methods certainly deserves further attention. In this paper, we describe a new coarse-mesh method for time-dependent monoenergetic S N transport problesm in slab geometry. This numerical method preserves the analytic solution of the transverse-integrated S N nodal equations by constants, so we call our method the analytical constant nodal (ACN) method. For time-independent S N problems in finite slab geometry and for time-dependent infinite-medium S N problems, the ACN method generates numerical solutions that are completely free of truncation errors. Bsed on this positive feature, we expect the ACN method to be more accurate than conventional numerical methods for S N transport calculations on coarse space-time grids

  20. Reconstruction of pin burnup characteristics from nodal calculations in hexagonal geometry

    International Nuclear Information System (INIS)

    Yang, W.S.; Finck, P.J.; Khalil, H.S.

    1990-01-01

    A reconstruction method has been developed for recovering pin burnup characteristics from fuel cycle calculations performed in hexagonal-z geometry using the nodal diffusion option of the DIF3D/REBUS-3 code system. Intra-modal distributions of group fluxes, nuclide densities, power density, burnup, and fluence are efficiently computed using polynomial shapes constrained to satisfy nodal information. The accuracy of the method has been tested by performing several numerical benchmark calculations and by comparing predicted local burnups to values measured for experimental assemblies in EBR-11. The results indicate that the reconstruction methods are quite accurate, yielding maximum errors in power and nuclide densities that are less than 2% for driver assemblies and typically less than 5% for blanket assemblies. 14 refs., 2 figs., 5 tabs

  1. Discrete nodal integral transport-theory method for multidimensional reactor physics and shielding calculations

    International Nuclear Information System (INIS)

    Lawrence, R.D.; Dorning, J.J.

    1980-01-01

    A coarse-mesh discrete nodal integral transport theory method has been developed for the efficient numerical solution of multidimensional transport problems of interest in reactor physics and shielding applications. The method, which is the discrete transport theory analogue and logical extension of the nodal Green's function method previously developed for multidimensional neutron diffusion problems, utilizes the same transverse integration procedure to reduce the multidimensional equations to coupled one-dimensional equations. This is followed by the conversion of the differential equations to local, one-dimensional, in-node integral equations by integrating back along neutron flight paths. One-dimensional and two-dimensional transport theory test problems have been systematically studied to verify the superior computational efficiency of the new method

  2. The General-Use Nodal Network Solver (GUNNS) Modeling Package for Space Vehicle Flow System Simulation

    Science.gov (United States)

    Harvey, Jason; Moore, Michael

    2013-01-01

    The General-Use Nodal Network Solver (GUNNS) is a modeling software package that combines nodal analysis and the hydraulic-electric analogy to simulate fluid, electrical, and thermal flow systems. GUNNS is developed by L-3 Communications under the TS21 (Training Systems for the 21st Century) project for NASA Johnson Space Center (JSC), primarily for use in space vehicle training simulators at JSC. It has sufficient compactness and fidelity to model the fluid, electrical, and thermal aspects of space vehicles in real-time simulations running on commodity workstations, for vehicle crew and flight controller training. It has a reusable and flexible component and system design, and a Graphical User Interface (GUI), providing capability for rapid GUI-based simulator development, ease of maintenance, and associated cost savings. GUNNS is optimized for NASA's Trick simulation environment, but can be run independently of Trick.

  3. Engineering topological phases with a three-dimensional nodal-loop semimetal

    Science.gov (United States)

    Li, Linhu; Yap, Han Hoe; Araújo, Miguel A. N.; Gong, Jiangbin

    2017-12-01

    A three-dimensional (3D) nodal-loop semimetal phase is exploited to engineer a number of intriguing phases featuring different peculiar topological surface states. In particular, by introducing various two-dimensional gap terms to a 3D tight-binding model of a nodal-loop semimetal, we obtain a rich variety of topological phases of great interest to ongoing theoretical and experimental studies, including a chiral insulator, degenerate-surface-loop insulator, and second-order topological insulator, as well as a Weyl semimetal with tunable Fermi arc profiles. The unique concept underlying our approach is to engineer topological surface states that inherit their dispersion relations from a gap term. The results provide one rather unified principle for the creation of novel topological phases and can guide the search for new topological materials. Two-terminal transport studies are also carried out to distinguish the engineered topological phases.

  4. Analysis of the applicability of acceleration methods for a triangular prism geometry nodal diffusion code

    International Nuclear Information System (INIS)

    Fujimura, Toichiro; Okumura, Keisuke

    2002-11-01

    A prototype version of a diffusion code has been developed to analyze the hexagonal core as reduced moderation reactor and the applicability of some acceleration methods have been investigated to accelerate the convergence of the iterative solution method. The hexagonal core is divided into regular triangular prisms in the three-dimensional code MOSRA-Prism and a polynomial expansion nodal method is applied to approximate the neutron flux distribution by a cubic polynomial. The multi-group diffusion equation is solved iteratively with ordinal inner and outer iterations and the effectiveness of acceleration methods is ascertained by applying an adaptive acceleration method and a neutron source extrapolation method, respectively. The formulation of the polynomial expansion nodal method is outlined in the report and the local and global effectiveness of the acceleration methods is discussed with various sample calculations. A new general expression of vacuum boundary condition, derived in the formulation is also described. (author)

  5. Conduct disorders

    NARCIS (Netherlands)

    Buitelaar, J.K.; Smeets, K.C.; Herpers, P.; Scheepers, F.; Glennon, J.; Rommelse, N.N.J.

    2013-01-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic

  6. Two-energy group solution of the diffusion equation by the multidimensional nodal polynomial expansion method

    International Nuclear Information System (INIS)

    Ribeiro, R.D.M.; Vellozo, S.O.; Botelho, D.A.

    1983-01-01

    The EPON computer code based in a Nodal Polynomial Expansion Method, wrote in Fortran IV, for steady-state, square geometry, one-dimensional or two-dimensional geometry and for one or two-energy group is presented. The neutron and power flux distributions for nuclear power plants were calculated, comparing with codes that use similar or different methodologies. The availability, economy and speed of the methodology is demonstrated. (E.G.) [pt

  7. Rapid enhancement of nodal quasiparticle mass with heavily underdoping in Bi2212

    Science.gov (United States)

    Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shin-ichi; Ino, Akihiro

    2018-05-01

    We report substantial advance of our low-energy angle-resolved photoemission study of nodal quasiparticles in Bi2Sr2CaCu2O8+δ. The new data cover the samples from underdoped down to heavily underdoped levels. We also present the nodal Fermi velocities that determined by using an excitation-photon energy of hν = 7.0 eV over a wide doping range. The consistency between the results with hν = 8.1 and 7.0 eV allows us to rule out the effect of photoemission matrix elements. In comparison with the data previously reported, the nodal effective mass increases by a factor of ∼ 1.5 in going from optimally doped to heavily underdoped levels. We find a rapid enhancement of the nodal quasiparticle mass at low doping levels near the superconductor-to-insulator transition. The effective coupling spectrum, λ (ω) , is extracted directly from the energy derivatives of the quasiparticle dispersion and scattering rate, as a causal function of the mass enhancement factor. A steplike increase in Reλ (ω) around ∼ 65 meV is demonstrated clearly by the Kramers-Kronig transform of Imλ (ω) . To extract the low-energy renormalization effect, we calculated a simple model for the electron-boson interaction. This model reveals that the contribution of the renormalization at | ω | ≤ 15 meV to the quasiparticle mass is larger than that around 65 meV in underdoped samples.

  8. The role of elective nodal irradiation for esthesioneuroblastoma patients with clinically negative neck.

    Science.gov (United States)

    Jiang, Wen; Mohamed, Abdallah S R; Fuller, Clifton David; Kim, Betty Y S; Tang, Chad; Gunn, G Brandon; Hanna, Ehab Y; Frank, Steven J; Su, Shirley Y; Diaz, Eduardo; Kupferman, Michael E; Beadle, Beth M; Morrison, William H; Skinner, Heath; Lai, Stephen Y; El-Naggar, Adel K; DeMonte, Franco; Rosenthal, David I; Garden, Adam S; Phan, Jack

    2016-01-01

    Although adjuvant radiation to the tumor bed has been reported to improve the clinic outcomes of esthesioneuroblastoma (ENB) patients, the role of elective neck irradiation (ENI) in clinically node-negative (N0) patients remains controversial. Here, we evaluated the effects of ENI on neck nodal relapse risk in ENB patients treated with radiation therapy as a component of multimodality treatment. Seventy-one N0 ENB patients irradiated at the University of Texas MD Anderson Cancer Center between 1970 and 2013 were identified. ENI was performed on 22 of these patients (31%). Survival analysis was performed with focus on comparative outcomes of those patients who did and did not receive ENI. The median follow-up time for our cohort is 80.8 months (range, 6-350 months). Among N0 patients, 13 (18.3%) developed neck nodal relapses, with a median time to progression of 62.5 months. None of these 13 patients received prophylactic neck irradiation. ENI was associated with significantly improved regional nodal control at 5 years (regional control rate of 100% for ENI vs 82%, P ENI developed isolated neck recurrences. All had further treatment for their neck disease, including neck dissection (n = 10), radiation (n = 10), or chemotherapy (n = 5). Six of these 11 patients (54.5%) demonstrated no evidence of further recurrence with a median follow-up of 55.5 months. ENI significantly reduces the risk of cervical nodal recurrence in ENB patients with clinically N0 neck, but this did not translate to a survival benefit. Multimodality treatment for isolated neck recurrence provides a reasonable salvage rate. The greatest benefit for ENI appeared to be among younger patients who presented with Kadish C disease. Further studies are needed to confirm these findings. Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

  9. The role of elective-nodal irradiation for esthesioneuroblastoma patients with clinically negative neck

    Science.gov (United States)

    Jiang, Wen; Mohamed, Abdallah Sherif; Fuller, Clifton David; Kim, Betty Y.S.; Tang, Chad; Gunn, G. Brandon; Hanna, Ehab Y.; Frank, Steven J.; Su, Shirley Y.; Diaz, Eduardo; Kupferman, Michael E.; Beadle, Beth M.; Morrison, William H.; Skinner, Heath; Lai, Stephen Y.; El-Naggar, Adel K.; DeMonte, Franco; Rosenthal, David I.; Garden, Adam S.; Phan, Jack

    2017-01-01

    Purpose Although adjuvant radiation to the tumor bed has been reported to improve the clinic outcomes of esthesioneuroblastoma (ENB) patients, the role of elective neck irradiation (ENI) in clinically node negative (N0) patients remains controversial. Here, we evaluated the effects of ENI on neck nodal relapse risk in ENB patients treated with radiotherapy as a component of multi-modality treatment. Methods and Materials Seventy-one N0 ENB patients irradiated at XXXXXXXXX between 1970 and 2013 were identified. ENI was performed on 22 of these patients (31%). Survival analysis was performed with focus on comparative outcomes of those patients who did and did not receive ENI. Results The median follow up time for our cohort is 80.8 months (range 6 – 350 month). Among N0 patients, 13 (18.3%) developed neck nodal relapses, with a median time to progression of 62.5 months. None of these 13 patients received prophylactic neck irradiation. ENI was associated with significantly improved regional nodal control at 5-year (regional control rate of 100% for ENI vs 82%, p ENI developed isolated neck recurrences. All had further treatment for their neck disease, including neck dissection (n=10), radiation (n=10), or chemotherapy (n=5). Six of these 11 patients (54.5%) demonstrated no evidence of further recurrence with a median follow up of 55.5 month. Conclusion ENI significantly reduces the risk of cervical nodal recurrence in ENB patients with clinically N0 neck but this did not translate to a survival benefit. Multimodality treatment for isolated neck recurrence provides a reasonable salvage rate. The greatest benefit for ENI appeared to be among younger patients who presented with Kadish C disease. Further studies are needed to confirm these findings. PMID:26979544

  10. Moderator feedback effects in two-dimensional nodal methods for pressurized water reactor analysis

    International Nuclear Information System (INIS)

    Downar, T.J.

    1987-01-01

    A method was developed for incorporating moderator feedback effects in two-dimensional nodal codes used for pressurized water reactor (PWR) neutronic analysis. Equations for the assembly average quality and density are developed in terms of the assembly power calculated in two dimensions. The method is validated with a Westinghouse PWR using the Electric Power Research Institute code SIMULATE-E. Results show a several percent improvement is achieved in the two-dimensional power distribution prediction compared to methods without moderator feedback

  11. Nodal collocation approximation for the multidimensional PL equations applied to transport source problems

    International Nuclear Information System (INIS)

    Verdu, G.; Capilla, M.; Talavera, C. F.; Ginestar, D.

    2012-01-01

    PL equations are classical high order approximations to the transport equations which are based on the expansion of the angular dependence of the angular neutron flux and the nuclear cross sections in terms of spherical harmonics. A nodal collocation method is used to discretize the PL equations associated with a neutron source transport problem. The performance of the method is tested solving two 1D problems with analytical solution for the transport equation and a classical 2D problem. (authors)

  12. Nodal collocation approximation for the multidimensional PL equations applied to transport source problems

    Energy Technology Data Exchange (ETDEWEB)

    Verdu, G. [Departamento de Ingenieria Quimica Y Nuclear, Universitat Politecnica de Valencia, Cami de Vera, 14, 46022. Valencia (Spain); Capilla, M.; Talavera, C. F.; Ginestar, D. [Dept. of Nuclear Engineering, Departamento de Matematica Aplicada, Universitat Politecnica de Valencia, Cami de Vera, 14, 46022. Valencia (Spain)

    2012-07-01

    PL equations are classical high order approximations to the transport equations which are based on the expansion of the angular dependence of the angular neutron flux and the nuclear cross sections in terms of spherical harmonics. A nodal collocation method is used to discretize the PL equations associated with a neutron source transport problem. The performance of the method is tested solving two 1D problems with analytical solution for the transport equation and a classical 2D problem. (authors)

  13. Numerical divergence effects of equivalence theory in the nodal expansion method

    International Nuclear Information System (INIS)

    Zika, M.R.; Downar, T.J.

    1993-01-01

    Accurate solutions of the advanced nodal equations require the use of discontinuity factors (DFs) to account for the homogenization errors that are inherent in all coarse-mesh nodal methods. During the last several years, nodal equivalence theory (NET) has successfully been implemented for the Cartesian geometry and has received widespread acceptance in the light water reactor industry. The extension of NET to other reactor types has had limited success. Recent efforts to implement NET within the framework of the nodal expansion method have successfully been applied to the fast breeder reactor. However, attempts to apply the same methods to thermal reactors such as the Modular High-Temperature Gas Reactor (MHTGR) have led to numerical divergence problems that can be attributed directly to the magnitude of the DFs. In the work performed here, it was found that the numerical problems occur in the inner and upscatter iterations of the solution algorithm. These iterations use a Gauss-Seidel iterative technique that is always convergent for problems with unity DFs. However, for an MHTGR model that requires large DFs, both the inner and upscatter iterations were divergent. Initial investigations into methods for bounding the DFs have proven unsatisfactory as a means of remedying the convergence problems. Although the DFs could be bounded to yield a convergent solution, several cases were encountered where the resulting flux solution was less accurate than the solution without DFs. For the specific case of problems without upscattering, an alternate numerical method for the inner iteration, an LU decomposition, was identified and shown to be feasible

  14. Nodal imaging in the neck: recent advances in US, CT and MR imaging of metastatic nodes

    International Nuclear Information System (INIS)

    Nakamura, Takashi; Sumi, Misa

    2007-01-01

    The presence of lymph node metastasis in the neck in patients with head and neck cancer is an important prognostic determinant in staging cancers and in planning surgery and chemo- and radiotherapy for the cancer patients. Therefore, metastatic nodes should be effectively differentiated from benign lymphadenopathies and nodal lymphomas. Here, we review recent advances in the diagnostic imaging of metastatic nodes in the neck, with emphasis placed on the diagnostic performance of MR imaging, Doppler sonography, and CT. (orig.)

  15. The BWR core simulator COSIMA with 2 group nodal flux expansion and control rod history

    International Nuclear Information System (INIS)

    Hoejerup, C.F.

    1989-08-01

    The boiling water simulator NOTAM has been modified and improved in several aspects: - The ''1 1/2'' energy group TRILUX nodal flux solution method has been exchanged with a 2 group modal expansion method. - Control rod ''history'' has been introduced. - Precalculated instrument factors have been introduced. The paper describes these improvements, which were considered sufficiently large to justify a new name to the programme: COSIMA. (author)

  16. An evaluation of nodalization/decay heat/ volatile fission product release models in ISAAC code

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yong Mann; Park, Soo Yong; Kim, Dong Ha

    2003-03-01

    An ISAAC computer code, which was developed for a Level-2 PSA during 1995, has developed mainly with fundamental models for CANDU-specific severe accident progression and also the accident-analyzing experiences are limited to Level-2 PSA purposes. Hence the system nodalization model, decay model and volatile fission product release model, which are known to affect fission product behavior directly or indirectly, are evaluated to both enhance understanding for basic models and accumulate accident-analyzing experiences. As a research strategy, sensitivity studies of model parameters and sensitivity coefficients are performed. According to the results from core nodalization sensitivity study, an original 3x3 nodalization (per loop) method which groups horizontal fuel channels into 12 representative channels, is evaluated to be sufficient for an optimal scheme because detailed nodalization methods have no large effect on fuel thermal-hydraulic behavior, total accident progression and fission product behavior. As ANSI/ANS standard model for decay heat prediction after reactor trip has no needs for further model evaluation due to both wide application on accident analysis codes and good comparison results with the ORIGEN code, ISAAC calculational results of decay heat are used as they are. In addition, fission product revaporization in a containment which is caused by the embedded decay heat, is demonstrated. The results for the volatile fission product release model are analyzed. In case of early release, the IDCOR model with an in-vessel Te release option shows the most conservative results and for the late release case, NUREG-0772 model shows the most conservative results. Considering both early and late release, the IDCOR model with an in-vessel Te bound option shows mitigated conservative results.

  17. Construction of Nodal Bubbling Solutions for the Weighted Sinh-Poisson Equation

    Directory of Open Access Journals (Sweden)

    Yibin Zhang

    2013-01-01

    Full Text Available We consider the weighted sinh-Poisson equation in , on , where is a small parameter, , and is a unit ball in . By a constructive way, we prove that for any positive integer , there exists a nodal bubbling solution which concentrates at the origin and the other -points , , such that as , , where and is an odd integer with , or is an even integer. The same techniques lead also to a more general result on general domains.

  18. Stage IVN neuroblastoma: MRI diagnosis of left supraclavicular ''Virchow's'' nodal spread

    International Nuclear Information System (INIS)

    Abramson, S.J.; Berdon, W.E.; Stolar, C.; Ruzal-Shapiro, C.; Garvin, J.

    1996-01-01

    Stage IV neuroblastoma is associated with high mortality; an exception are patients whose stage IV status includes distant positive nodes, but no skeletal metastases - stage IVN neuroblastoma. We describe our experience with preoperative MRI in three patients with extensive abdominal neuroblastoma without cortical bony involvement but with unsuspected metastatic involvement to the left supraclavicular (Virchow's) node. We review findings of left supraclavicular nodal spread in five earlier cases of IVN neuroblastoma. (orig.). With 3 figs., 1 tab

  19. A PURE NODAL-ANALYSIS METHOD SUITABLE FOR ANALOG CIRCUITS USING NULLORS

    OpenAIRE

    E. Tlelo-Cuautle; L.A. Sarmiento-Reyes

    2003-01-01

    A novel technique suitable for computer-aided analysis of analog integrated circuits (ICs) is introduced. This technique uses the features of both nodal-analysis (NA) and symbolic analysis, at nullor level. First, the nullor is used to model the ideal behavior of several analog devices, namely: transistors, opamps, OTAs, and current conveyors. From this modeling approach, it is shown how to transform circuits working in voltage-mode to current-mode and vice-versa. Second, it is demonstrated t...

  20. Disrupted Nodal and Hub Organization Account for Brain Network Abnormalities in Parkinson's Disease.

    Science.gov (United States)

    Koshimori, Yuko; Cho, Sang-Soo; Criaud, Marion; Christopher, Leigh; Jacobs, Mark; Ghadery, Christine; Coakeley, Sarah; Harris, Madeleine; Mizrahi, Romina; Hamani, Clement; Lang, Anthony E; Houle, Sylvain; Strafella, Antonio P

    2016-01-01

    The recent application of graph theory to brain networks promises to shed light on complex diseases such as Parkinson's disease (PD). This study aimed to investigate functional changes in sensorimotor and cognitive networks in Parkinsonian patients, with a focus on inter- and intra-connectivity organization in the disease-associated nodal and hub regions using the graph theoretical analyses. Resting-state functional MRI data of a total of 65 participants, including 23 healthy controls (HCs) and 42 patients, were investigated in 120 nodes for local efficiency, betweenness centrality, and degree. Hub regions were identified in the HC and patient groups. We found nodal and hub changes in patients compared with HCs, including the right pre-supplementary motor area (SMA), left anterior insula, bilateral mid-insula, bilateral dorsolateral prefrontal cortex (DLPFC), and right caudate nucleus. In general, nodal regions within the sensorimotor network (i.e., right pre-SMA and right mid-insula) displayed weakened connectivity, with the former node associated with more severe bradykinesia, and impaired integration with default mode network regions. The left mid-insula also lost its hub properties in patients. Within the executive networks, the left anterior insular cortex lost its hub properties in patients, while a new hub region was identified in the right caudate nucleus, paralleled by an increased level of inter- and intra-connectivity in the bilateral DLPFC possibly representing compensatory mechanisms. These findings highlight the diffuse changes in nodal organization and regional hub disruption accounting for the distributed abnormalities across brain networks and the clinical manifestations of PD.