127 research outputs found
Wall Solution with Weak Gravity Limit in Five Dimensional Supergravity
In five-dimensional supergravity, an exact solution of BPS wall is found for
a gravitational deformation of the massive Eguchi-Hanson nonlinear sigma model.
The warp factor decreases for both infinities of the extra dimension. Thin wall
limit gives the Randall-Sundrum model without fine-tuning of input parameters.
We also obtain wall solutions with warp factors which are flat or increasing in
one side, by varying a deformation parameter of the potential.Comment: Typo corrected, reference added, 13pages, 5 figure
Deformed Prepotential, Quantum Integrable System and Liouville Field Theory
We study the dual descriptions recently discovered for the Seiberg-Witten
theory in the presence of surface operators. The Nekrasov partition function
for a four-dimensional N=2 gauge theory with a surface operator is believed
equal to the wave-function of the corresponding integrable system, or the
Hitchin system, and is identified with the conformal block with a degenerate
field via the AGT relation. We verify the conjecture by showing that the null
state condition leads to the Schrodinger equations of the integrable systems.
Furthermore, we show that the deformed prepotential emerging from the period
integrals of the principal function corresponds to monodromy operation of the
conformal block. We also give the instanton partition functions for the
asymptotically free SU(2) gauge theories in the presence of the surface
operator via the AGT relation. We find that these partition functions involve
the counting of two- and four-dimensional instantons.Comment: 47 pages; v2: references added, typos corrected; v3: a version to
appear in Nuclear Physics
Wild-Type Monomeric α-Synuclein Can Impair Vesicle Endocytosis and Synaptic Fidelity via Tubulin Polymerization at the Calyx of Held
α-Synuclein is a presynaptic protein the function of which has yet to be identified, but its neuronal content increases in patients of synucleinopathies including Parkinson\u27s disease. Chronic overexpression of α-synuclein reportedly expresses various phenotypes of synaptic dysfunction, but the primary target of its toxicity has not been determined. To investigate this, we acutely loaded human recombinant α-synuclein or its pathological mutants in their monomeric forms into the calyces of Held presynaptic terminals in slices from auditorily mature and immature rats of either sex. Membrane capacitance measurements revealed significant and specific inhibitory effects of WT monomeric α-synuclein on vesicle endocytosis throughout development. However, the α-synuclein A53T mutant affected vesicle endocytosis only at immature calyces, whereas the A30P mutant had no effect throughout. The endocytic impairment by WT α-synuclein was rescued by intraterminal coloading of the microtubule (MT) polymerization blocker nocodazole. Furthermore, it was reversibly rescued by presynaptically loaded photostatin-1, a photoswitcheable inhibitor of MT polymerization, in a light-wavelength-dependent manner. In contrast, endocytic inhibition by the A53T mutant at immature calyces was not rescued by nocodazole. Functionally, presynaptically loaded WT α-synuclein had no effect on basal synaptic transmission evoked at a low frequency, but significantly attenuated exocytosis and impaired the fidelity of neurotransmission during prolonged high-frequency stimulation. We conclude that monomeric WT α-synuclein primarily inhibits vesicle endocytosis via MT overassembly, thereby impairing high-frequency neurotransmission.SIGNIFICANCE STATEMENT Abnormal α-synuclein abundance is associated with synucleinopathies including Parkinson\u27s disease, but neither the primary target of α-synuclein toxicity nor its mechanism is identified. Here, we loaded monomeric α-synuclein directly into mammalian glutamatergic nerve terminals and found that it primarily inhibits vesicle endocytosis and subsequently impairs exocytosis and neurotransmission fidelity during prolonged high-frequency stimulation. Such α-synuclein toxicity could be rescued by blocking microtubule polymerization, suggesting that microtubule overassembly underlies the toxicity of acutely elevated α-synuclein in the nerve terminal
Refined Topological Vertex and Instanton Counting
It has been proposed recently that topological A-model string amplitudes for
toric Calabi-Yau 3-folds in non self-dual graviphoton background can be
caluculated by a diagrammatic method that is called the ``refined topological
vertex''. We compute the extended A-model amplitudes for SU(N)-geometries using
the proposed vertex. If the refined topological vertex is valid, these
computations should give rise to the Nekrasov's partition functions of N=2
SU(N) gauge theories via the geometric engineering. In this article, we verify
the proposal by confirming the equivalence between the refined A-model
amplitude and the K-theoretic version of the Nekrasov's partition function by
explicit computation.Comment: 22 pages, 6 figures, minor correction
Difference between carbohydrate antigen 19-9 and fluorine-18 fluorodeoxyglucose positron emission tomography in evaluating the treatment efficacy of neoadjuvant treatment in patients with resectable and borderline resectable pancreatic ductal adenocarcinoma: Results of a dual-center study
kita, H, Takahashi, H, Eguchi, H, et al. Difference between carbohydrate antigen 19‐9 and fluorine‐18 fluorodeoxyglucose positron emission tomography in evaluating the treatment efficacy of neoadjuvant treatment in patients with resectable and borderline resectable pancreatic ductal adenocarcinoma: Results of a dual‐center study. Ann Gastroenterol Surg. 2020; 00: 1– 9. https://doi.org/10.1002/ags3.12418
Massive Nonlinear Sigma Models and BPS Domain Walls in Harmonic Superspace
Four-dimensional massive N=2 nonlinear sigma models and BPS wall solutions
are studied in the off-shell harmonic superspace approach in which N=2
supersymmetry is manifest. The general nonlinear sigma model can be described
by an analytic harmonic potential which is the hyper-Kahler analog of the
Kahler potential in N=1 theory. We examine the massive nonlinear sigma model
with multi-center four-dimensional target hyper-Kahler metrics and derive the
corresponding BPS equation. We study in some detail two particular cases with
the Taub-NUT and double Taub-NUT metrics. The latter embodies, as its two
separate limits, both Taub-NUT and Eguchi-Hanson metrics. We find that domain
wall solutions exist only in the double Taub-NUT case including its
Eguchi-Hanson limit.Comment: 35 pages, 4 figures, minor corrections and references added, to
appear in NP
Surface Operator, Bubbling Calabi-Yau and AGT Relation
Surface operators in N=2 four-dimensional gauge theories are interesting
half-BPS objects. These operators inherit the connection of gauge theory with
the Liouville conformal field theory, which was discovered by Alday, Gaiotto
and Tachikawa. Moreover it has been proposed that toric branes in the A-model
topological strings lead to surface operators via the geometric engineering. We
analyze the surface operators by making good use of topological string theory.
Starting from this point of view, we propose that the wave-function behavior of
the topological open string amplitudes geometrically engineers the surface
operator partition functions and the Gaiotto curves of corresponding gauge
theories. We then study a peculiar feature that the surface operator
corresponds to the insertion of the degenerate fields in the conformal field
theory side. We show that this aspect can be realized as the geometric
transition in topological string theory, and the insertion of a surface
operator leads to the bubbling of the toric Calabi-Yau geometry.Comment: 36 pages, 14 figures. v2: minor changes and typos correcte
Hyper-Kahler Sigma Models on (Co)tangent Bundles with SO(n) isometry
We construct N=2 supersymmetric nonlinear sigma models whose target spaces
are tangent as well as cotangent bundles over the quadric surface Q^{n-2} =
SO(n)/[SO(n-2)\times U(1)]. We use the projective superspace framework, which
is an off-shell formalism of N=2 supersymmetry.Comment: 33 pages, 1 figure, typos corrected, to appear in Nucl. Phys.
- …