32 research outputs found
The ICln interactome
No full textThe many different functional phenotypes described in mammalian cells can only be explained by an intense interaction of the underlying proteins, substantiated by the fact that the number of independently expressed proteins in living cells seems not to exceed 25 K, a number way too small to explain the >250 K different phenotypes on a one-protein-one-function base. Therefore, the study of the interactome of the different proteins is of utmost importance. Here, we describe the present knowledge of the ICln interactome. ICln is a protein, we cloned and whose function was reported to be as divers as (i) ion permeation, (ii) cytoskeletal organization, and (iii) RNA processing. The role of ICln in these different functional modules can be described best as being a 'connector hub' with 'date hub' functio
Localisation of MHD modes in the pedestal of ASDEX upgrade
No full textIn der inter-ELM Phase sogenannter H-Moden Plasmen am ASDEX Upgrade TOKAMAK erscheinen MHD-Moden in der Magnetik. Sie haben einen Frequenzbereich bis zu mehreren hundert kHz und können mittels Induktionsspulen beobachtet werden. Ziel dieser Arbeit ist deren radiale Lokalisierung im Plasma sowie die Bestimmung der Geschwindigkeit der Moden, um sie mit Plasmadriften zu vergleichen.Mögliche Auslöser und Treiber von Moden folgen aus einer Betrachtung der TOKAMAK Stabilität. Ein Überblick verschiedener Typen von Moden wird gezeigt. Die Modenstruktur ist durch zwei Parameter charakterisiert, die poloidale Modenzahl m und die toroidale Modenzahl n. Es wird diskutiert wie die magnetische Topologie, im Speziellen der Sicherheitsfaktor, verantwortlich für die Modenstruktur ist. Diese Beziehung zum Sicherheitsfaktor bietet eine Möglichkeit zur Lokalisierung der Moden. Verwendete Diagnostiken werden vorgestellt und ein Programm zur Bestimmung der Modenzahlen wird erklärt. Dies beinhaltet eine neuartige Subroutine für die poloidale Modenzahlbestimmung. Diamagnetische Driften wurden kürzlich in einer Bachelorarbeit mit einer neuen Fitroutine berechnet, die ebenfalls erklärt wird.Anhand von einigen Beispielen aus dem Typ-I ELM Regime wird die Lokalisierung und Geschwindigkeitsberechnung demonstriert. Bei der Lokalisierung wird wiederholt eine Position nahe der Separatrix erhalten, die Präzision ist durch die Reichweite des Equilibriums limitiert. Eine eindeutige Diskrepanz zwischen der Modengeschwindigkeit und den Plasmadriften wird gezeigt, was auf ein Wellenphänomen mit zusätzlicher Phasengeschwindigkeit hindeutet.In the inter-ELM phase of H-mode plasmas at ASDEX Upgrade, MHD modes appear in the magnetic signature. They exhibit a frequency range up to several hundred kHz and can be observed through pick-up coils. This thesis aims to localize their radial position in the plasma as well as to find the velocity with which they move to compare it to plasma drifts.Possible driving causes for the modes follow from a TOKAMAK stability consideration. An overview of mode types is given. The mode structure is characterized by two parameters, the poloidal mode number m and the toroidal mode number n. It is discussed how the magnetic topology, especially the safety factor, determines the mode structure. This relation to the safety factor presents a possibility to localize the modes. The applied diagnostics are presented and a program to compute the mode numbers is explained. This includes a new subroutine for the determination of the poloidal mode number. Calculation of diamagnetic drift velocities was done in a recent bachelor's thesis through a novel fitting routine, which is also explained.Based on several examples from the type-I ELM regime, the localization and velocity calculation is demonstrated. The localization consistently yields a position close to the separatrix, the precision is ultimately limited by the range of the equilibrium reconstruction. A clear discrepancy in the velocity compared to plasma drifts is shown which hints at the presence of a wave phenomenon adding a phase velocity
Resection of lesions in the upper gastrointestinal tract: Results of one year of endoscopic mucosal resection and endoscopic submucosal dissection in a non-academic centre
No full textEarly onset, non fluctuating spinocerebellar ataxia and a novel missense mutation in CACNA1A gene
No full textMutations in the brain-specific P/Q type Ca2+ channel alpha 1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2), and familial hemiplegic migraine type I (FHM1). SCA6 is associated with small expansions of a CAG repeat at the 3' end of the gene, while point mutations are mostly responsible for its two allelic disorders, FHMI and EA2. From the electrophysiological point of view, while FHMI mutations lead to a gain of function [Tottene A, Fellin T, Pagnutti S, Luvisetto S, Striessnig J, Fletcher C, et al. Familial hemiplegic migraine mutations increase Ca(2+) influx through single human CaV2.1 channels and decrease maximal CaV2.1 current density in neurons. Proc Natl Acad Sci 99 (20) (2002) 13284-13289.], EA2 mutations usually generate a loss of channel function [Guida S, Trettel F, Pagnutti S, Mantuano E, Tottene A, Veneziano L, et al. Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2. Am J Hum Genet 68 (3) (2001) 759-764, Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 277 (9) (2002) 6960-6966]. In the present study, we describe a child affected by permanent non-fluctuating limb and trunk ataxia with a quite early age of onset. Interestingly, the size of the CACNA1A triplet repeat region in the patient is within the normal range while he carries a novel de novo, missense mutation in this gene, p.R1664Q. Although functional data are not available, based on the literature data indicating that severe reductions in P/Q-type channel activity favour episodic and/or progressive ataxic symptoms [Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 2002;277(9):6960-6966.], we hypothesize that the functional consequence of the mutation here identified is a partial loss of the Ca channel function. In conclusion, the clinical and molecular findings reported here suggest the opportunity to screen for point mutation in this gene, even patients with a clinical phenotype for some aspects slightly different from the typical picture more commonly associated to SCA6, EA2 or FHM1 diseases. (c) 2005 Elsevier B.V. All rights reserved
Experimental Insights Into Space Weathering of Phobos : Laboratory Investigation of Sputtering by Atomic and Molecular Planetary Ions
No full textInvestigating the space weathering of the Martian moon Phobos represents an important step toward understanding the development from its origin to its present-day appearance. Depending on Phobos' orbital position, its surface is continuously sputtered by the solar wind and planetary ions that originate in the Martian atmosphere. Based on Mars Atmosphere and Volatile Evolution measurements, it has been proposed that sputtering by planetary O+ and O-2(+) ions dominates in the Martian tail region, where the planet mostly shadows Phobos from the solar wind. In these models, uncertainties for sputtering yield inputs still exist due to the lack of sufficient analog experiments. Therefore, sputtering measurements with O+, O-2(+), C+, and CO2+ ions between 1 and 5 keV were performed using augite samples as Phobos analogs. The experimental results for O+ irradiations show smaller mass changes than predicted by SDTrimSP simulations, which probably can be attributed to O implantation enabled by the Fe content of the target. Sputtering with O-2(+) and CO2+ in the low keV range shows no deviations in the sputtering yields attributable to molecular effects. Therefore, CO2+ ions will most likely be negligible for the sputtering of Phobos according to the current understanding of ion fluxes on the Martian moon. Ultimately, our experiments suggest that the sputtering contribution on Phobos by O ions is about 50% smaller than previously assumed. This does not change the qualitative outcome from previous modeling stating that planetary O ions are by far the dominant sputtering contribution on Phobos in the Martian tail region
Assessment of validity of local neoclassical transport theory for studies of electric-field root-transitions in the W7-X stellarator
No full textThe neoclassical ambipolarity condition governing the radial electric field in stellarators can
have several solutions, and sudden transitions (in radius) between these can then take place. The radial position and structure of such a transition cannot be determined from local transport theory, and instead a non-rigorous model based on a diffusion equation for the electric field is usually employed for this purpose (Turkin et al 2011 Phys. Plasmas 18 022505). We compare global (full plasma volume) drift-kinetic simulations of neoclassical transport in the Wendelstein 7-X stellarator with this model and find significant discrepancies. The position r0 of the transition is not predicted correctly by the diffusion model, but the radial structure of the transition layer is in reasonable agreement if the diffusion coefficient is chosen appropriately. In particular, it should depend on the plasma temperature in the same way as the plateau-regime coefficient of neoclassical transport theory or the gyro-Bohm diffusion coefficient. In the small-gyroradius limit, the prediction of r0 by the diffusion model simplifies to the so-called Maxwell construction (Shaing 1984 Phys. Fluids 27 1567–9; Shaing 1984 Phys. Fluids 27 1924–6). However, this property also emerges from a wide range of other mathematical models in the appropriate limit. The basic assumption underlying these models is that the diffusion, or generalisations thereof, is independent of the radial electric field, which is however unlikely to be the case in practice. Presumably this fact explains the discrepancy between the diffusion model and the drift-kinetic simulations. Finally, it is found that global simulations replicate the phenomenon of spontaneous root transitions driven by variations in the electron-to-ion temperature ratio, as predicted by local theory in the small-gyroradius limit
