Shear-Flow Driven Current Filamentation: Two-Dimensional Magnetohydrodynamic Simulations

The process of current filamentation in permanently externally driven, initially globally ideal plasmas is investigated by means of two-dimensional Magnetohydrodynamic (MHD)-simulations. This situation is typical for astrophysical systems like jets, the interstellar and intergalactic medium where the dynamics is dominated by external forces. Two different cases are studied. In one case, the system is ideal permanently and dissipative processes are excluded. In the second case, a system with a current density dependent resistivity is considered. This resistivity is switched on self-consistently in current filaments and allows for local dissipation due to magnetic reconnection. Thus one finds tearing of current filaments and, besides, merging of filaments due to coalescence instabilities. Energy input and dissipation finally balance each other and the system reaches a state of constant magnetic energy in time.Comment: 32 Pages, 13 Figures. accepted, to appear in Physics of Plasmas (049012

Large-bore Vascular Closure: New Devices and Techniques

Endovascular aneurysm repair, transcatheter aortic valve implantation and percutaneous mechanical circulatory support systems have become valuable alternatives to conventional surgery and even preferred strategies for a wide array of clinical entities. Their adoption in everyday practice is growing. These procedures require large-bore access into the femoral artery. Their use is thus associated with clinically significant vascular bleeding complications. Meticulous access site management is crucial for safe implementation of large-bore technologies and includes accurate puncture technique and reliable percutaneous closure devices. This article reviews different strategies for obtaining femoral access and contemporary percutaneous closure technologies

The critical velocity effect as a cause for the H\alpha emission from the Magellanic stream

Observations show significant H\alpha-emissions in the Galactic halo near the edges of cold gas clouds of the Magellanic Stream. The source for the ionization of the cold gas is still a widely open question. In our paper we discuss the critical velocity effect as a possible explanation for the observed H\alpha-emission. The critical velocity effect can yield a fast ionization of cold gas if this neutral gas passes through a magnetized plasma under suitable conditions. We show that for parameters that are typical for the Magellanic Stream the critical velocity effect has to be considered as a possible ionization source of high relevance.Comment: 9 pages, 2 figures. accepted, to appear in The Astrophysical Journa

Insights in a restricted temporary pacemaker strategy in a lean transcatheter aortic valve implantation program

OBJECTIVES: To study the safety and feasibility of a restrictive temporary‐RV‐pacemaker use and to evaluate the need for temporary pacemaker insertion for failed left ventricular (LV) pacing ability (no ventricular capture) or occurrence of high‐degree AV‐blocks mandating continuous pacing. BACKGROUND: Ventricular pacing remains an essential part of contemporary transcatheter aortic valve implantation (TAVI). A temporary‐right‐ventricle (RV)‐pacemaker lead is the standard approach for transient pacing during TAVI but requires central venous access. METHODS: An observational registry including 672 patients who underwent TAVI between June 2018 and December 2020. Patients received pacing on the wire when necessary, unless there was a high‐anticipated risk for conduction disturbances post‐TAVI, based on the baseline‐ECG. The follow‐up period was 30 days. RESULTS: A temporary‐RV‐pacemaker lead (RVP‐cohort) was inserted in 45 patients, pacing on the wire (LVP‐cohort) in 488 patients, and no pacing (NoP‐cohort) in 139 patients. A bailout temporary pacemaker was implanted in 14 patients (10.1%) in the NoP‐cohort and in 24 patients (4.9%) in the LVP‐cohort. One patient in the LVP‐cohort needed an RV‐pacemaker for incomplete ventricular capture. Procedure time was significantly longer in the RVP‐cohort (68 min [IQR 52–88.] vs. 55 min [IQR 44–72] in NoP‐cohort and 55 min [IQR 43–71] in the LVP‐cohort [p < 0.005]). Procedural high‐degree AV‐block occurred most often in the RVP‐cohort (45% vs. 14% in the LVP and 16% in the NoP‐cohort [p ≤ 0.001]). Need for new PPI occurred in 47% in the RVP‐cohort, versus 20% in the NoP‐cohort and 11% in the LVP‐cohort (p ≤ 0.001). CONCLUSION: A restricted RV‐pacemaker strategy is safe and shortens procedure time. The majority of TAVI‐procedures do not require a temporary‐RV‐pacemaker

A new variational approach to the stability of gravitational systems

We consider the three dimensional gravitational Vlasov Poisson system which describes the mechanical state of a stellar system subject to its own gravity. A well-known conjecture in astrophysics is that the steady state solutions which are nonincreasing functions of their microscopic energy are nonlinearly stable by the flow. This was proved at the linear level by several authors based on the pioneering work by Antonov in 1961. Since then, standard variational techniques based on concentration compactness methods as introduced by P.-L. Lions in 1983 have led to the nonlinear stability of subclasses of stationary solutions of ground state type. In this paper, inspired by pioneering works from the physics litterature (Lynden-Bell 94, Wiechen-Ziegler-Schindler MNRAS 88, Aly MNRAS 89), we use the monotonicity of the Hamiltonian under generalized symmetric rearrangement transformations to prove that non increasing steady solutions are local minimizer of the Hamiltonian under equimeasurable constraints, and extract compactness from suitable minimizing sequences. This implies the nonlinear stability of nonincreasing anisotropic steady states under radially symmetric perturbations

Clinical consequences of consecutive self-expanding transcatheter heart valve iterations

OBJECTIVE: To compare early clinical outcomes after transcatheter aortic valve implantation (TAVI) with three consecutive generations of self-expanding valves (SEVs). METHODS: Clinical endpoints of consecutive patients who underwent TAVI with CoreValve, Evolut R or Evolut PRO were included in a prospective database. RESULTS: TAVI was performed with CoreValve (n = 116), Evolut R (n = 160) or Evolut PRO (n = 92). Evolut R and Evolut PRO showed a tendency towards lower permanent pacemaker implantation (PPI) rates compared to CoreValve (CoreValve 27% vs Evolut R 16% vs Evolut PRO 18%, p = 0.091). By multivariable regression analysis CoreValve had a significantly higher risk for PPI (odds ratio (OR) 2.79, 95% confidence interval (CI) 1.31–5.94, p = 0.008) compared to Evolut R, while Evolut R and PRO were similar. Severe paravalvular leakage (PVL) occurred only with CoreValve, but no significant difference was observed in moderate PVL (10% vs 8% vs 6%, p = 0.49). CoreValve had a tendency towards a higher risk for more-than-mild PVL as compared with the Evolut platform (R + PRO) (OR 2.46, 95% CI 0.98–6.16, p = 0.055). No significant differences in all-cause mortality (7% vs 4% vs 1%, p = 0.10), stroke (6% vs 3% vs 2%, p = 0.21) or major vascular complications (10% vs 12% vs 4%, p = 0.14) were observed. CONCLUSIONS: TAVI with self-expanding valves was safe, and device iterations may result in a lower need for PPI. More-than-mild PVL seemed to occur less often with repositionable technology. SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s12471-021-01568-5) contains supplementary material, which is available to authorized users

Milestones in the Observations of Cosmic Magnetic Fields

Magnetic fields are observed everywhere in the universe. In this review, we concentrate on the observational aspects of the magnetic fields of Galactic and extragalactic objects. Readers can follow the milestones in the observations of cosmic magnetic fields obtained from the most important tracers of magnetic fields, namely, the star-light polarization, the Zeeman effect, the rotation measures (RMs, hereafter) of extragalactic radio sources, the pulsar RMs, radio polarization observations, as well as the newly implemented sub-mm and mm polarization capabilities. (Another long paragraph is omitted due to the limited space here)Comment: Invited Review (ChJA&A); 32 pages. Sorry if your significant contributions in this area were not mentioned. Published pdf & ps files (with high quality figures) now availble at http://www.chjaa.org/2002_2_4.ht

Caveolin 1 protein expression in renal cell carcinoma predicts survival

<p>Abstract</p> <p>Background</p> <p>Caveolae play a significant role in disease phenotypes such as cancer, diabetes, bladder dysfunction, and muscular dystrophy. The aim of this study was to elucidate the caveolin-1 <it>(</it>CAV1<it>) </it>protein expression in renal cell cancer (RCC) and to determine its potential prognostic relevance.</p> <p>Methods</p> <p>289 clear cell RCC tissue specimens were collected from patients undergoing surgery for renal tumors. Both cytoplasmic and membranous CAV1 expression were determined by immunohistochemistry and correlated with clinical variables. Survival analysis was carried out for 169 evaluable patients with a median follow up of 80.5 months (interquartile range (IQR), 24.5 - 131.7 months).</p> <p>Results</p> <p>A high CAV1 expression in the tumor cell cytoplasm was significantly associated with male sex (p = 0.04), a positive nodal status (p = 0.04), and poor tumor differentiation (p = 0.04). In contrast, a higher than average (i.e. > median) CAV1 expression in tumor cell membranes was only linked to male sex (p = 0.03). Kaplan-Meier analysis disclosed significant differences in 5-year overall (51.4 vs. 75.2%, p = 0.001) and tumor specific survival (55.3 vs. 80.1%, p = 0.001) for patients with higher and lower than average cytoplasmic CAV1 expression levels, respectively. Applying multivariable Cox regression analysis a high CAV1 protein expression level in the tumor cell cytoplasm could be identified as an independent poor prognostic marker of both overall (p = 0.02) and tumor specific survival (p = 0.03) in clear cell RCC patients.</p> <p>Conclusion</p> <p>Over expression of caveolin-1 in the tumour cell cytoplasm predicts a poor prognosis of patients with clear cell RCC. CAV1 is likely to be a useful prognostic marker and may play an important role in tumour progression. Therefore, our data encourage further investigations to enlighten the role of CAV1 and its function as diagnostic and prognostic marker in serum and/or urine of RCC patients.</p