1,442 research outputs found
U(1)_R mediation from the flux compactification in six dimensions
We consider a supersymmetric completion of codimension-two branes with
nonzero tension in a 6D gauged supergravity. As a consequence, we obtain the
football solution with 4D Minkowski space as a new supersymmetric background
that preserves 4D N=1 SUSY. In the presence of brane multiplets, we derive the
4D effective supergravity action for the football background and show that the
remaining modulus can be stabilized by a bulk non-perturbative correction with
brane uplifting potentials at a zero vacuum energy. We find that the U(1)_R
mediation can be a dominant source of SUSY breaking for a brane scalar with
nonzero R charge.Comment: 3 pages, no figures, to appear in the proceedings of the 16th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions (SUSY-2008), Seoul, Korea, 16-21 June, 200
Instanton effects on electromagnetic transitions of charmonia
We investigate the mass spectrum and electromagnetic transitions of
charmonia, emphasizing the instanton effects on them. The heavy-quark potential
consists of the Coulomb-like potential from one-gluon exchange and the linear
confining potential. We introduce the nonperturbative heavy-quark potential
derived from the instanton vacuum. We also consider the screened confining
potential, which better describes the electromagnetic decays of higher excited
states. Using this improved heavy-quark potential, we compute the mass spectrum
and electromagnetic decays of the charmonia. Focusing on the instanton effects,
we discuss the results compared with the experimental data and those from other
works. The instanton effects are marginal on the electromagnetic decays of
charmonia.Comment: 10 pages and 4 figures. The final version to be published in Progress
of Theoretical and Experimental Physic
Two-dimensional charge distributions of the baryon: Interpolation between the nonrelativistic and ultrarelativistic limit
We investigate how the charge distributions of both the unpolarized and
transversely polarized baryon change as the longitudinal
momentum~() of the baryon increases from to
in a Wigner phase-space perspective. When the baryon is
longitudinally polarized, its two-dimensional charge distribution is kept to be
spherically symmetric with varied, whereas when the baryon is
transversely polarized along the -axis, the quadrupole contribution emerges
at the rest frame (). When grows, the electric dipole and
octupole moments are induced. The induced dipole moment dominates over other
higher multipole contributions and governs the deformation of the charge
distribution of the baryon.Comment: 22 pages, 12 figure
The Mechanism of Copperâ Catalyzed Trifunctionalization of Terminal Allenes
A highly selective copperâ catalyzed trifunctionalization of allenes has been established based on diborylation/cyanation with bis(pinacolato)diboron (B2pin2) and Nâ cyanoâ Nâ phenylâ pâ toluenesulfonamide (NCTS). The Cuâ catalyzed trifunctionalization of terminal allenes is composed of three catalytic reactions (first borocupration, electrophilic cyanation, and second borocupration) that provide a densely functionalized product with regioâ , chemoâ and diastereoselectivity. Allene substrates have multiple reactionâ sites, and the selectivities are determined by the suitable interactions (e.g., electronic and steric demands) between the catalyst and substrates. We employed DFT calculations to understand the cascade copperâ catalyzed trifunctionalization of terminal allenes, providing denselyâ functionalized organic molecules with outstanding regioâ , chemoâ and diastereoselectivity in high yields. The selectivity challenges presented by cumulated à â systems are addressed by systematic computational studies; these give insight to the catalytic multipleâ functionalization strategies and explain the high selectivities that we see for these reactions.Cuâ catalyzed trifunctionalization of terminal allenes, through three catalytic reactions (borocupration, electrophilic cyanation, followed by a second borocupration), provides a densely functionalized product with regioâ , chemoâ and diastereoselectivity (see figure). Density functional theory calculations help to understand the cascade catalytic mechanism.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/1/chem201900673.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/2/chem201900673-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/3/chem201900673_am.pd
The Mechanism of Copperâ Catalyzed Trifunctionalization of Terminal Allenes
A highly selective copperâ catalyzed trifunctionalization of allenes has been established based on diborylation/cyanation with bis(pinacolato)diboron (B2pin2) and Nâ cyanoâ Nâ phenylâ pâ toluenesulfonamide (NCTS). The Cuâ catalyzed trifunctionalization of terminal allenes is composed of three catalytic reactions (first borocupration, electrophilic cyanation, and second borocupration) that provide a densely functionalized product with regioâ , chemoâ and diastereoselectivity. Allene substrates have multiple reactionâ sites, and the selectivities are determined by the suitable interactions (e.g., electronic and steric demands) between the catalyst and substrates. We employed DFT calculations to understand the cascade copperâ catalyzed trifunctionalization of terminal allenes, providing denselyâ functionalized organic molecules with outstanding regioâ , chemoâ and diastereoselectivity in high yields. The selectivity challenges presented by cumulated à â systems are addressed by systematic computational studies; these give insight to the catalytic multipleâ functionalization strategies and explain the high selectivities that we see for these reactions.Cuâ catalyzed trifunctionalization of terminal allenes, through three catalytic reactions (borocupration, electrophilic cyanation, followed by a second borocupration), provides a densely functionalized product with regioâ , chemoâ and diastereoselectivity (see figure). Density functional theory calculations help to understand the cascade catalytic mechanism.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/1/chem201900673.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/2/chem201900673-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150512/3/chem201900673_am.pd
Electromagnet Weight Reduction in a Magnetic Levitation System for Contactless Delivery Applications
This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of electromagnets is better for lateral performance. This is verified by simulations and experiments. This paper presents a statistically optimized design with a high number of the design variables to reduce the weight of the electromagnet under the constraint of normal force using response surface methodology (RSM) and the kriging interpolation method. 2D and 3D magnetostatic analysis of the electromagnet are performed using ANSYS. The most effective design variables are extracted by a Pareto chart. The most desirable set is determined and the influence of each design variable on the objective function can be obtained. The generalized reduced gradient (GRG) algorithm is adopted in the kriging model. This paperâs procedure is validated by a comparison between experimental and calculation results, which shows that the predicted performance of the electromagnet designed by RSM is in good agreement with the simulation results
Posterior Trans-Dural Repair of Iatrogenic Spinal Cord Herniation after Resection of Ossification of Posterior Longitudinal Ligament
Iatrogenic spinal cord herniation is a rare complication following spinal surgery. We introduce a posterior trans-dural repair technique used in a case of thoracic spinal cord herniation through a ventral dural defect following resection of ossification of the posterior longitudinal ligament (OPLL) in the cervicothoracic spine. A 51-year-old female was suffering from paraplegia after laminectomy alone for cervicothoracic OPLL. Magnetic resonance imaging revealed a severely compressed spinal cord with pseudomeningocele identified postoperatively. Cerebrospinal fluid leak and iatrogenic spinal cord herniation persisted despite several operations with duroplasty and sealing agent. Finally, the problems were treated by repair of the ventral dural defect with posterior trans-dural duroplasty. Several months after surgery, the patient could walk independently. This surgical technique can be applied to treat ventral dural defect and spinal cord herniation
Insight into highly conserved H1 subtype-specific epitopes in influenza virus hemagglutinin
Influenza viruses continuously undergo antigenic changes with gradual accumulation of mutations in hemagglutinin (HA) that is a major determinant in subtype specificity. The identification of conserved epitopes within specific HA subtypes gives an important clue for developing new vaccines and diagnostics. We produced and characterized nine monoclonal antibodies that showed significant neutralizing activities against H1 subtype influenza viruses, and determined the complex structure of HA derived from a 2009 pandemic virus A/Korea/01/2009 (KR01) and the Fab fragment from H1-specific monoclonal antibody GC0587. The overall structure of the complex was essentially identical to the previously determined KR01 HA-Fab0757 complex structure. Both Fab0587 and Fab0757 recognize readily accessible head regions of HA, revealing broadly shared and conserved antigenic determinants among H1 subtypes. The beta-strands constituted by Ser110-Glu115 and Lys169-Lys170 form H1 epitopes with distinct conformations from those of H1 and H3 HA sites. In particular, Glu112, Glu115, Lys169, and Lys171 that are highly conserved among H1 subtype HAs have close contacts with HCDR3 and LCDR3. The differences between Fab0587 and Fab0757 complexes reside mainly in HCDR3 and LCDR3, providing distinct antigenic determinants specific for 1918 pdm influenza strain. Our results demonstrate a potential key neutralizing epitope important for H1 subtype specificity in influenza virus
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