Studies on automatic parallelization for heterogeneous and homogeneous multicore processors

制度:新 ; 報告番号:甲3537号 ; 学位の種類:博士(工学) ; 授与年月日:2012/2/25 ; 早大学位記番号:新587

Experiments on Ion Cyclotron Heating of Plasma in the Heliotron-B Device

The Heliotron magnetic field for plasma confining has many magnetic slopes suitable to cause a phase mixing of ion cyclotron waves propagating along the magnetic lines of force. Experiments on ion cyclotron heating with this mechanism were carried out by using a plasma generator “Heliotron-B”. A rf coil of Picket Fence type fed rf power into plasma and excited the ion cyclotron waves of 12cm axial wave length. Rf power absorption curves as a function of rf frequency, obtained by using a low power oscillator, showed there are two kinds of rf loading peaks of plasma ; one is due to the excitation of the ion cyclotron waves and another due to the cyclotron resonance of individual ions. The exciting efficiency of the ion cyclotron waves was above 75%. Doppler shifts of particle cyclotron reasonance from the cyclotron frequency were also observed under the Joule heating. This fact suggests that ion beams are flowing in plasma under the Joule heating. The plasma generated by the Joule heating was supplied with rf power of 100kW, and ion cyclotron waves were excited and damped in the Heliotron field. As a results, ion temperature could be raised up to 4XlO⁵°K. Electron temperature was insensible to this heating

Low-frequency Oscillation of a Bounded Plasma in an External Magnetic Field

Low-frequency plasma waves with non-axisymmetric modes are generally analyzed under the existence of an ion beam. A boundary condition, that a cylindrical plasma is coaxially immersed in a cylindrical current sheet with a vacuum clearance, is taken into account. Oscillating electromagnetic field and electron and ion motions associated with the waves are also examined. Natural oscillations with a free boundary and cylindrical plasma waves surrounded by a conducting cylinder are found to exist. Ion cyclotron waves of axisymmetric modes found by Stix can be derived as a special case of these modes

The adenosine A2B receptor is involved in anion secretion in human pancreatic duct Capan-1 epithelial cells

Adenosine modulates a wide variety of biological processes via adenosine receptors. In the exocrine pancreas, adenosine regulates transepithelial anion secretion in duct cells and is considered to play a role in acini-to-duct signaling. To identify the functional adenosine receptors and Cl− channels important for anion secretion, we herein performed experiments on Capan-1, a human pancreatic duct cell line, using open-circuit Ussing chamber and gramicidin-perforated patch-clamp techniques. The luminal addition of adenosine increased the negative transepithelial potential difference (V te) in Capan-1 monolayers with a half-maximal effective concentration value of approximately 10 μM, which corresponded to the value obtained on whole-cell Cl− currents in Capan-1 single cells. The effects of adenosine on V te, an equivalent short-circuit current (I sc), and whole-cell Cl− currents were inhibited by CFTRinh-172, a cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel inhibitor. The adenosine A2B receptor agonist, BAY 60-6583, increased I sc and whole-cell Cl− currents through CFTR Cl− channels, whereas the A2A receptor agonist, CGS 21680, had negligible effects. The A2B receptor antagonist, PSB 603, inhibited the response of I sc to adenosine. Immunohistochemical analysis showed that the A2A and A2B receptors colocalized with Ezrin in the luminal membranes of Capan-1 monolayers and in rat pancreatic ducts. Adenosine elicited the whole-cell Cl− currents in guinea pig duct cells. These results demonstrate that luminal adenosine regulates anion secretion by activating CFTR Cl− channels via adenosine A2B receptors on the luminal membranes of Capan-1 cells. The present study endorses that purinergic signaling is important in the regulation of pancreatic secretion

Involvement of butyrate in electrogenic K+ secretion in rat rectal colon

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are synthesized from dietary carbohydrates by colonic bacterial fermentation. These SCFAs supply energy, suppress cancer, and affect ion transport. However, their roles in ion transport and regulation in the intracellular environment remain unknown. In order to elucidate the roles of SCFAs, we measured short-circuit currents (ISC) and performed RT-PCR and immunohistochemical analyses of ion transporters in rat rectal colon. The application of 30 mM butyrate shifted ISC in a negative direction, but did not attenuate the activity of epithelial Na+ channels (ENaC). The application of bumetanide, a Na+-K+-2Cl− cotransporter inhibitor, to the basolateral side reduced the negative ISC shift induced by butyrate. The application of XE991, a KCNQ-type K+ channel inhibitor, to the apical side decreased the ISC shift induced by butyrate in a dose-dependent manner. The ISC shift was independent of HCO3− and insensitive to ibuprofen, an SMCT1 inhibitor. The mucosa from rat rectal colon expressed mRNAs of H+-coupled monocarboxylate transporters (MCT1, MCT4, and MCT5, also referred to as SLC16A1, SLC16A3, and SLC16A4, respectively). RT-PCR and immunofluorescence analyses demonstrated that KCNQ2 and KCNQ4 localized to the apical membrane of surface cells in rat rectal colon. These results indicate that butyrate, which may be transported by H+-coupled monocarboxylate transporters, activates K+ secretion through KCNQ-type K+ channels on the apical membrane in rat rectal colon. KCNQ-type K+ channels may play a role in intestinal secretion and defense mechanisms in the gastrointestinal tract