Rolling ferrofluid drop on the surface of a liquid

We report on the controlled transport of drops of magnetic liquid, which are swimming on top of a non-magnetic liquid layer. A magnetic field which is rotating in a vertical plane creates a torque on the drop. Due to surface stresses within the immiscible liquid beneath, the drop is propelled forward. We measure the drop speed for different field amplitudes, field frequencies and drop volumes. Simplifying theoretical models describe the drop either as a solid sphere with a Navier slip boundary condition, or as a liquid half-sphere. An analytical expression for the drop speed is obtained which is free of any fitting parameters and is well in accordance with the experimental measurements. Possible microfluidic applications of the rolling drop are also discussed

La réception de la postérité et de l’autorité de Jean Gerson (1363-1429) au début des temps modernes (XVIème siècle)

Le projet consiste à retracer la postérité du grand théologien du Moyen Âge tardif, Jean Gerson (1363-1429) aussi bien dans le milieu protestant que chez les penseurs catholiques du XVIème siècle. Homme d’église, éducateur, poète, penseur du premier ordre et acteur majeur dans l’histoire politique et religieuse de la France, il n’a pas reçu toute l’attention qu’il mérite. Le premier objectif de la thèse consiste ainsi à sortir le nom de Gerson de l’ombre en mettant en évidence son influence au-delà du XVème siècle, ce qui n’a pas été fait auparavant. Visant à surmonter les clivages religieux et nationaux, cette étude présente les traits majeurs de son influence à travers la multiplicité des usages et des interprétations de sa pensée dont les diverses composantes s’articulent différemment au fil du temps. L’approche intégrale de la thèse cherche à combler un manque historiographique puisque la postérité de Gerson, parfois considérée dans ses diverses régions, n’a pas encore fait objet d’étude dans sa globalité. Comme l’attitude envers l’autorité de Gerson fut largement tributaire des conflits religieux qui agitèrent l’Europe, sa présence posthume dépendit surtout des objectifs polémiques et des prises de positions idéologiques de ceux qui trouvaient en lui une source d’inspiration. En conséquence, la thèse est organisée chronologiquement, confessionnellement, ainsi que géographiquement. Afin de fournir au lecteur l’arrière-plan historique précédant immédiatement la Réforme, l’étude commence après le Concile de Constance. D’un point de vue dénominationnel, la thèse est divisée, de façon relativement égale, entre les réceptions protestante et catholique, à l’exception de la postérité de Gerson en Angleterre et en Écosse qui constitue un chapitre à part. L’étude révèle des tendances dans sa réception touchant à l’humanisme, aux théologies systématique et pastorale, au mysticisme dévotionnel, le droit et l’historiographie, laissant de côté sa pensée conciliariste.The project consists in tracing the legacy of the great late medieval theologian Jean Gerson (1363-1429) both in Protestant circles and among Catholic thinkers of the 16th century. A churchman, educator, poet, humanist, preacher and a first-class thinker, he has not received the attention he deserves. The dissertation hopes to achieve precisely this primary goal: to take Gerson’s name out of shadow and bring him into spotlight, by showing his influence beyond 15th century, which hasn’t been done before. Although the attitude towards Gerson’s authority was largely conditioned by religious conflicts that had agitated Europe during the Reformation, and his posthumous presence depended above all on the polemical objectives and ideological positions of those who found in him a source of inspiration, the dissertation seeks to overcome religious and national divisions and partisan scholarship. The contents of the dissertation are organized chronologically, denominationally, as well as geographically. In order to provide the reader with historical background immediately preceding the Reformation, chronologically it begins after the closure of the Council of Constance. Denominationally, the study is divided, relatively equally, between Protestant and Catholic receptions. Aside from Gerson’s legacy in England and Scotland, which constitutes a separate chapter, his reception in different regions is represented by geographical subdivisions within chapters. By presenting major features of his influence through the massive appropriation of his thought and work, the study reveals discernable tendencies in Gerson’s reception relevant to humanism, systematic theology, devotional mysticism, pastoral care, jurisprudence and early modern historiography, while leaving conciliarist aspect aside

The past and the future of vascular access surgery: Creation of percutaneous arteriovenous fistula using Ellipsys vascular access system in a patient with previous ipsilateral Scribner-shunt

Background: Sixty years after the first description of Scribner-shunt, and 54 years after publication of the first radio-cephalic arterio-venous fistula (AVF), endovascular percutaneous AVF (pAVF) was introduced. We report a successful case of Ellipsys-pAVF creation and use for hemodialysis in a patient with a previous ipsilateral Scribner-shunt. Case: A 72-year old female patient with chronic kidney disease (CKD), previous right-sided Scribner-shunt and kidney transplant, underwent a successful creation of right-sided Ellipsys-pAVF. The procedure time was 12 min with intraoperative brachial artery volume flow of 720 ml/min. At 39 days, an ultrasound-guided balloon-angioplasty of the outflow cephalic vein stenosis was performed. Cannulations were started 41 days after the creation of pAVF. No additional interventions were required during the follow-up of 258 days with last follow-up volume flow of 1400 ml/min. Conclusions: This is the first report of the creation of pAVF in a patient with previous “traumatic” ipsilateral placement of a Scribner-shunt. It allows the creation of a small anastomosis in very short time, which can be successfully used for hemodialysis treatment on the same day, if necessary, and reduces the expected risk of high-flow AVF with associated peripheral steal and cardiac outcomes (especially in a patient with cardiomyopathy such this one). </jats:sec

Novel external stenting for reconstruction of high flow arteriovenous fistula

Background: High-flow arteriovenous fistulae (HF-AVF) may lead to adverse cardiac remodeling in hemodialysis patients. We have investigated whether a novel external stent is safe and effective in reducing and stabilizing flow rates during a 1-year follow-up after HF-AVF reconstruction. Methods: All patients with HF-AVF (access flow rate ⩾ 1500 ml/min), who underwent HF-AVF reconstruction with external stenting in two centers between June 2018 and May 2020, were included in this retrospective analysis. During HF-AVF reconstruction, the dilated vein segment was resected, underwent volume reduction, and was externally stabilized using a braided cobalt-chromium external stent. AVF flow rates were assessed preoperatively, intraoperatively, and at follow up visits using duplex ultrasound. Results: Forty-three HF-AVFs in 42 patients were reconstructed and supported with an external stent (mean age 49 years, range 20–86 years; 74% men). Fifty-one percent were forearm AVFs, 49% were upper arm. The mean preoperative flow rate was 2622 ± 893 ml/min (range: 1500–6000 ml/min) and was decreased to 710 ± 221 ml/min (range: 300–1300 ml/min) intra-operatively after HF-AVF reconstruction. At 6 and 12-months follow-up, the mean flow rates were 1132 ± 320 ml/min (range: 470–1700 ml/min) and 1453 ± 888 ml/min (range: 300–3800 ml/min), respectively. Recurrence of high flow (&gt;1500 ml/min) occurred in 16% and 25% of the patients at 6 and 12 months and primary patency rates were 86% and 70%, respectively. Conclusions: This early experience with novel external stenting for HF-AVF reconstruction demonstrates that it is a safe and effective method for reducing and stabilizing flow rates up to 1-year post procedure. Additional studies are required to evaluate the durability of this procedure over the longer term and assess its effect on cardiac remodeling. </jats:sec

Gracz fistula is a feasible option after two failed percutaneous arteriovenous fistulae

Two devices for the creation of an endovascular percutaneous (pAVF) endovascular (endoAVF) arteriovenous fistulae (AVF) are available: the Ellipsys and the WavelinQ-4F systems. The main difference is the location of the anastomosis, making it feasible to use both pAVFs and surgical Gracz-type AVF in an algorithm sequence. A 66-year-old male patient with end-stage kidney disease and HIV was referred for a creation of a dialysis access after failed peritoneal dialysis. A radial-radial WavelinQ-pAVF with simultaneous coil embolization of a brachial vein was created but failed within 4 weeks. Therefore, an Ellipsys-pAVF was successfully created between the proximal radial artery and perforating vein on the same arm. After 2 days, however, the Ellipsys-pAVF anastomosis occluded. The ipsilateral Gracz-AVF was created, anastomosing perforating vein with the antecubital brachial artery. Cannulations were started 28 days later. During the follow up of 807 days, the AVF remained patent with last known volume flow of 1500 ml/min and no need for secondary interventions. We report a successful creation of a Gracz-AVF after primary failed pAVFs created with both pAVF-systems in a single patient and in the same arm. Thus, based on that case we recommend creation of pAVF prior to Gracz-AVF as integral part of Vascular Access creation algorithm, based on each patient’s life plan. </jats:p

Patency and functionality of radiocephalic arteriovenous fistulas with an external support device (VasQ™): Real-world single-center experience

Background: The VasQTM device was designed to improve the outcome of arteriovenous fistulae by optimizing the hemodynamics of the flow in the juxta-anastomotic region of the arteriovenous fistulae through tailored external support. The aim of the study was to evaluate the impact of the VasQ on outcome of radiocephalic arteriovenous fistulae in a real-world setting. Methods: This was a single-center, retrospective analysis of patients with either fistula creation before or after dialysis initiation with implantation of the VasQ device during creation of end-to-side radiocephalic arteriovenous fistulae between June 2018 and May 2019. The flow rate and vein diameter were evaluated intraoperatively, at discharge within 48 h postprocedure and at a follow-up of 1, 3, 6, 9, and 12 months. Results: Thirty-three VasQ devices were implanted during 33 radiocephalic arteriovenous fistula procedures. The study population comprised mostly of men, with an average age of 66 years. Mean intraoperative flow was 428 mL/min (range: 130–945). All patients were discharged with patent arteriovenous fistulae and mean fistula flow of 740 mL/min (range: 230–1300 mL/min). The primary patency was 100% and 79% at 3 and 6 months, respectively. Cumulative/secondary patency was 100% and 90% at 3 and 6 months, respectively. Conclusion: Data presented here suggest that the VasQ device has the potential to provide benefit to the functionality of radiocephalic arteriovenous fistulae. </jats:sec