Browsing by Subject "CME"

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  • Morosan, D. E.; Palmerio, E.; Lynch, B. J.; Kilpua, E. K. J. (2020)
    Context. Coronal mass ejections (CMEs) on the Sun are the largest explosions in the Solar System that can drive powerful plasma shocks. The eruptions, shocks, and other processes associated to CMEs are efficient particle accelerators and the accelerated electrons in particular can produce radio bursts through the plasma emission mechanism. Aims. Coronal mass ejections and associated radio bursts have been well studied in cases where the CME originates close to the solar limb or within the frontside disc. Here, we study the radio emission associated with a CME eruption on the back side of the Sun on 22 July 2012. Methods. Using radio imaging from the Nancay Radioheliograph, spectroscopic data from the Nancay Decametric Array, and extreme-ultraviolet observations from the Solar Dynamics Observatory and Solar Terrestrial Relations Observatory spacecraft, we determine the nature of the observed radio emission as well as the location and propagation of the CME. Results. We show that the observed low-intensity radio emission corresponds to a type II radio burst or a short-duration type IV radio burst associated with a CME eruption due to breakout reconnection on the back side of the Sun, as suggested by the pre-eruptive magnetic field configuration. The radio emission consists of a large, extended structure, initially located ahead of the CME, that corresponds to various electron acceleration locations. Conclusions. The observations presented here are consistent with the breakout model of CME eruptions. The extended radio emission coincides with the location of the current sheet and quasi-separatrix boundary of the CME flux and the overlying helmet streamer and also with that of a large shock expected to form ahead of the CME in this configuration.
  • Rinne, Juha K. A.; Ehrlich, Anu; Ward, Jaana; Väyrynen, Ville; Laine, Mikael; Kellokumpu, Ilmo H.; Kairaluoma, Matti; Hyöty, Marja K.; Kössi, Jyrki A. O. (2021)
    Purpose To compare laparoscopic non-CME colectomy with laparoscopic CME colectomy in two hospitals with similar experience in laparoscopic colorectal surgery. Methods Data was collected retrospectively from Paijat-Hame Central Hospital (PHCH, NCME group) and Central Finland Central Hospital (CFCH, CME group) records. Elective laparoscopic resections performed during 2007-2016 for UICC stage I-III adenocarcinoma were included to assess differences in short-term outcome and survival. Results There were 340 patients in the NCME group and 325 patients in the CME group. CME delivered longer specimens (p <0.001), wider resection margins (p <0.001), and more lymph nodes (p <0.001) but did not result in better 5-year overall or cancer-specific survival (NCME 77.9% vs CME 72.9%, p = 0.528, NCME 93.2% vs CME 88.9%, p = 0.132, respectively). Thirty-day morbidity, mortality, and length of hospital stay were similar between the groups. Conversion to open surgery was associated with decreased survival. Discussion Complete mesocolic excision (CME) is reported to improve survival. Most previous studies have compared open CME with open non-CME (NCME) or open CME with laparoscopic CME. NCME populations have been historical or heterogeneous, potentially causing bias in the interpretation of results. Studies comparing laparoscopic CME with laparoscopic NCME are few and involve only small numbers of patients. In this study, diligently performed laparoscopic non-CME D2 resection delivered disease-free survival results comparable with laparoscopic CME but was not safer.
  • Zeinoddin, Narjes (Helsingin yliopisto, 2020)
    Endocytosis is the process responsible for internalising membrane components and as such plays a key role in the biology of this structure. Mammalian cells have evolved various endocytic strategies, but Clathrin-Mediated Endocytosis (CME) is the most common type. Since the discovery of CME, around 50 years ago, the field has built a remarkable wealth of knowledge on the core CME components. In stark contrast, our understanding on the relationship between CME and the actin cytoskeleton, which is present throughout the process, is still in its infancy. In this thesis, I show the production and characterisation of recombinant, SpyCatcher tagged transferrin (TF), a canonical CME ligand. TF was expressed in E. coli and using an optimised protocol, successfully solubilised and refolded from inclusion bodies. The protein was then labelled with a fluorophore and purified to a high level of purity. Tests in mammalian cells showed that home-made TF has the same endocytic behaviour as TF purified from human plasma. Moreover, I could show that the SpyCatcher moiety attached to our home-made TF is capable to mediate its covalent linkage to its counterpart SpyTag. The successful production, refolding and functional characterization of recombinant TF in this study is an important first step to examine the participation of the actin cytoskeleton during CME.
  • Ramesh, R.; Kathiravan, C.; Kumari, Anshu (2023)
    We report spectral and polarimeter observations of two weak, low-frequency (≈85–60 MHz) solar coronal type II radio bursts that occurred on 2020 May 29 within a time interval ≈2 minutes. The bursts had fine structures, and were due to harmonic plasma emission. Our analysis indicates that the magnetohydrodynamic shocks responsible for the first and second type II bursts were generated by the leading edge (LE) of an extreme-ultraviolet flux rope/coronal mass ejection (CME) and interaction of its flank with a neighboring coronal structure, respectively. The CME deflected from the radial direction by ≈25° during propagation in the near-Sun corona. The estimated power spectral density and magnetic field strength (B) near the location of the first burst at heliocentric distance r ≈ 1.35 Re are ≈2 × 10−3 W2m and ≈1.8 G, respectively. The corresponding values for the second burst at the same r are ≈10−3 W2 m and ≈0.9 G. The significant spatial scales of the coronal turbulence at the location of the two type II bursts are ≈62–1 Mm. Our conclusions from the present work are that the turbulence and magnetic field strength in the coronal region near the CME LE are higher compared to the corresponding values close to its flank. The derived estimates of the two parameters correspond to the same r for both the CME LE and its flank, with a delay of ≈2 minutes for the latter.