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Search Results: 1 - 10 of 2611 matches for " Akira Iritani "
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Resurrection of a Bull by Cloning from Organs Frozen without Cryoprotectant in a ?80°C Freezer for a Decade
Yoichiro Hoshino, Noboru Hayashi, Shunji Taniguchi, Naohiko Kobayashi, Kenji Sakai, Tsuyoshi Otani, Akira Iritani, Kazuhiro Saeki
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004142
Abstract: Frozen animal tissues without cryoprotectant have been thought to be inappropriate for use as a nuclear donor for somatic cell nuclear transfer (SCNT). We report the cloning of a bull using cells retrieved from testicles that had been taken from a dead animal and frozen without cryoprotectant in a ?80°C freezer for 10 years. We obtained live cells from defrosted pieces of the spermatic cords of frozen testicles. The cells proliferated actively in culture and were apparently normal. We transferred 16 SCNT embryos from these cells into 16 synchronized recipient animals. We obtained five pregnancies and four cloned calves developed to term. Our results indicate that complete genome sets are maintained in mammalian organs even after long-term frozen-storage without cryoprotectant, and that live clones can be produced from the recovered cells.
What Happens in the Brain of Schizophrenia Patients?: An Investigation from the Viewpoint of Neuropathology
Nagoya Journal of Medical Science , 2013,
Abstract: Studies that seek to determine the etiology of schizophrenia through pathological images and morphological abnormalities of the brain have been conducted since the era of E. Kraepelin, and pioneers in neuropathology such as A. Alzheimer have also eagerly pursued such studies. However, there have been no disease-specific findings, and there was a brief era in which it was said that “schizophrenia is the graveyard of neuropathologists.” However, since the 1980s, neuroimaging studies with CT and MRI etc., have been used in many reports of cases of schizophrenia with abnormal brain morphology, thus generating renewed interest in developments within brain tissue and leading to new neuropathological studies. There are now many reports in which, in addition to morphological observations, cell distribution and the like are image-processed and statistically processed through computers. Due to methodological problems in making progress in the field of cerebral pathology, we have not yet been able to observe disease-specific findings, although there are several findings with high certainty. However, the neurodevelopmental hypothesis has been supported as being able to reasonably explain the accumulated findings of previous studies. At the same time, results of recent molecular-biological studies have revealed the risk genes for this disease, and because many of those genes are associated with functions related to nerve differentiation, development, and plasticity, there is growing interest in their correlations with cerebral pathology. We are now on the verge of uncovering the etiology of this disease by integrating cerebral neuroimaging, molecular genetics, and cerebral neuropathology. In that sense, neuropathological studies of this disease from new viewpoints have become essential.
Real and integral structures in quantum cohomology I: toric orbifolds
Hiroshi Iritani
Mathematics , 2007,
Abstract: We study real and integral structures in the space of solutions to the quantum differential equations. First we show that, under mild conditions, any real structure in orbifold quantum cohomology yields a pure and polarized tt^*-geometry near the large radius limit. Secondly, we use mirror symmetry to calculate the "most natural" integral structure in quantum cohomology of toric orbifolds. We show that the integral structure pulled back from the singularity B-model is described only in terms of topological data in the A-model; K-group and a characteristic class. Using integral structures, we give a natural explanation why the quantum parameter should specialize to a root of unity in Ruan's crepant resolution conjecture.
tt*-geometry in quantum cohomology
Hiroshi Iritani
Mathematics , 2009,
Abstract: We study possible real structures in the space of solutions to the quantum differential equation. We show that, under mild conditions, a real structure in orbifold quantum cohomology yields a pure and polarized tt^*-geometry near the large radius limit. We compute an example of P^1 which is pure and polarized over the whole Kaehler moduli space H^2(P^1,C^*).
An integral structure in quantum cohomology and mirror symmetry for toric orbifolds
Hiroshi Iritani
Mathematics , 2009, DOI: 10.1016/j.aim.2009.05.016
Abstract: We introduce an integral structure in orbifold quantum cohomology associated to the K-group and the Gamma-class. In the case of compact toric orbifolds, we show that this integral structure matches with the natural integral structure for the Landau-Ginzburg model under mirror symmetry. By assuming the existence of an integral structure, we give a natural explanation for the specialization to a root of unity in Y. Ruan's crepant resolution conjecture.
Quantum Cohomology and Periods
Hiroshi Iritani
Mathematics , 2011,
Abstract: In a previous paper, the author introduced a Z-structure in quantum cohomology defined by the K-theory and the Gamma class and showed that it is compatible with mirror symmetry for toric orbifolds. Applying the quantum Lefschetz principle to the previous results, we find an explicit relationship between solutions to the quantum differential equation for toric complete intersections and the periods (or oscillatory integrals) of their mirrors. We describe in detail the mirror isomorphism of variations of Z-Hodge structure for a mirror pair of Calabi-Yau hypersurfaces (Batyrev's mirror).
Ruan's conjecture and integral structures in quantum cohomology
Hiroshi Iritani
Mathematics , 2008,
Abstract: This is an expository article on the recent studies of Ruan's crepant resolution/flop conjecture and its possible relations to the K-theory integral structure in quantum cohomology.
Shift operators and toric mirror theorem
Hiroshi Iritani
Mathematics , 2014,
Abstract: We give a new proof of Givental's mirror theorem for toric manifolds using shift operators of equivariant parameters. The proof is almost tautological: it gives an A-model construction of the I-function and the mirror map. It also works for non-compact or non-semipositive toric manifolds.
Convergence of quantum cohomology by quantum Lefschetz
Hiroshi Iritani
Mathematics , 2005, DOI: 10.1515/CRELLE.2007
Abstract: Quantum Lefschetz theorem by Coates and Givental gives a relationship between the genus 0 Gromov-Witten theory of X and the twisted theory by a line bundle L on X. We prove the convergence of the twisted theory under the assumption that the genus 0 theory for original X converges. As a byproduct, we prove the semi-simplicity and the Virasoro conjecture for the Gromov-Witten theories of (not necessarily Fano) projective toric manifolds.
Quantum D-modules and equivariant Floer theory for free loop spaces
Hiroshi Iritani
Mathematics , 2004, DOI: 10.1007/s00209-005-0867-9
Abstract: The objective of this paper is to clarify the relationships between the quantum D-module and equivariant Floer theory. Equivariant Floer theory was introduced by Givental in his paper ``Homological Geometry''. He conjectured that the quantum D-module of a symplectic manifold is isomorphic to the equivariant Floer cohomology for the universal cover of the free loop space. First, motivated by the work of Guest, we formulate the notion of ``abstract quantum D-module''which generalizes the D-module defined by the small quantum cohomology algebra. Second, we define the equivariant Floer cohomology of toric complete intersections rigorously as a D-module, using Givental's model. This is shown to satisfy the axioms of abstract quantum D-module. By Givental's mirror theorem, it follows that equivariant Floer cohomology defined here is isomorphic to the quantum cohomology D-module.
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