391 research outputs found

    Transport control of dust particles via the Electrical Asymmetry Effect: experiment, simulation, and modeling

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    The control of the spatial distribution of micrometer-sized dust particles in capacitively coupled radio frequency discharges is relevant for research and applications. Typically, dust particles in plasmas form a layer located at the sheath edge adjacent to the bottom electrode. Here, a method of manipulating this distribution by the application of a specific excitation waveform, i.e. two consecutive harmonics, is discussed. Tuning the phase angle \theta between the two harmonics allows to adjust the discharge symmetry via the Electrical Asymmetry Effect (EAE). An adiabatic (continuous) phase shift leaves the dust particles at an equilibrium position close to the lower sheath edge. Their levitation can be correlated with the electric field profile. By applying an abrupt phase shift the dust particles are transported between both sheaths through the plasma bulk and partially reside at an equilibium position close to the upper sheath edge. Hence, the potential profile in the bulk region is probed by the dust particles providing indirect information on plasma properties. The respective motion is understood by an analytical model, showing both the limitations and possible ways of optimizing this sheath-to-sheath transport. A classification of the transport depending on the change in the dc self bias is provided, and the pressure dependence is discussed.Comment: 25 pages, 16 figure

    Kaluza-Klein bubble like structure and celestial sphere in inflationary universe

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    We consider five dimensional deSitter spacetimes with a deficit angle due to the presence of a closed 2-brane and identify one dimension as an extra dimension. From the four dimensional viewpoint we can see that the spacetime has a structure similar to a Kaluza-Klein bubble of nothing, that is, four dimensional spacetime ends at the 2-brane. Since a spatial section of the full deSitter spacetime has the topology of a sphere, the boundary surface surrounds the remaining four dimensional spacetime, and can be considered as the celestial sphere. After the spacetime is created from nothing via an instanton which we describe, some four dimensional observers in it see the celestial sphere falling down, and will be in contact with a 2-brane attached on it.Comment: 5pages, 4figures, to be published in GR

    Stapled intestinal anastomosis is a simple and reliable method for management of intestinal caliber discrepancy in children

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    PURPOSE: Popularity of minimally invasive surgeries has led to the development of stapled intestinal anastomosis for adults. The advanced instruments used in this technique are getting suitable with the small intestinal lumens of neonates and infants. We reviewed and compared the intraoperative and postoperative results of stapled and hand-sewn anastomoses in children. METHODS: The operative data of children who underwent stapled and hand-sewn anastomoses between March 2005 and December 2011 were collected and analyzed retrospectively. Furthermore, we compared patients who underwent anastomoses for colostomy closure of anorectal malformation (4 stapled, 9 hand-sewn) and those who underwent anastomoses for treatment of ileal atresia (3 stapled, 11 hand-sewn). RESULTS: In the 47 patients who underwent stapled anastomosis, no intraoperative complications were observed and postoperative complications included wound infection (n = 3), delayed gastric emptying (n = 1), and ileus (n = 1). No complications suggesting anastomotic dilatation were identified. It was observed that patients who underwent stapled anastomosis for colostomy takedown with caliber discrepancy had significantly shorter surgery time than those who underwent hand-sewn anastomosis. CONCLUSION: Our results suggest that stapled anastomosis is safe and effective for various surgical diseases in neonates, infants, and children

    (1R*,2S*,4S*,5R*)-Cyclo­hexane-1,2:4,5-tetra­carb­oxy­lic dianhydride

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    The title compound, C10H8O6, a promising raw material to obtain colorless polyimides which are applied to microelectronic and optoelectronic devices, adopts a folded conformation in which the dihedral angle between the two anhydro rings is 55.15 (8)°. The central six-membered ring assumes a conformation inter­mediate between boat and twist-boat. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming a layer parallel to the bc plane
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