124 research outputs found
成人T細胞白血病におけるエピゲノム異常の包括的解析及びその機能的意義の解明
学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 渡邉 俊樹, 東京大学教授 井上 純一郎, 東京大学教授 古川 洋一, 東京大学教授 松田 浩一, 東京大学准教授 内丸 薫University of Tokyo(東京大学
Twisted Superspace on a Lattice
We propose a new formulation which realizes exact twisted supersymmetry for
all the supercharges on a lattice by twisted superspace formalism. We show
explicit examples of N=2 twisted supersymmetry invariant BF and Wess-Zumino
models in two dimensions. We introduce mild lattice noncommutativity to
preserve Leibniz rule on the lattice. The formulation is based on the twisted
superspace formalism for N=D=2 supersymmetry which was proposed recently. From
the consistency condition of the noncommutativity of superspace, we find an
unexpected three-dimensional lattice structure which may reduce into two
dimensional lattice where the superspace describes semilocally scattered
fermions and bosons within a double size square lattice.Comment: 49 pages, 17 figures; v2: Fig.2 is replace
One-loop vacuum amplitude for D-branes in constant electromagnetic field
Following Polchinski's approach we calculate the one-loop vacuum amplitude
for two parallel D-branes connected by open bosonic (neutral or charged)string
in a constant uniform electromagnetic (EM) field. For neutral string, external
EM field contribution appears as multiplier (Born-Infeld type action) of vacuum
amplitude without external EM field. Hence,it gives the alternative way to see
the inducing of Born-Infeld type action for description of D-branes. For
charged string the situation is more complicated, it may indicate the necessity
to modify the induced D-branes action in this case.Comment: Latex file, 9page
The Standard Model with gravity couplings
In this paper, we examine the coupling of matter fields to gravity within the
framework of the Standard Model of particle physics. The coupling is described
in terms of Weyl fermions of a definite chirality, and employs only
(anti)self-dual or left-handed spin connection fields. It is known from the
work of Ashtekar and others that such fields can furnish a complete description
of gravity without matter. We show that conditions ensuring the cancellation of
perturbative chiral gauge anomalies are not disturbed. We also explore a global
anomaly associated with the theory, and argue that its removal requires that
the number of fundamental fermions in the theory must be multiples of 16. In
addition, we investigate the behavior of the theory under discrete
transformations P, C and T; and discuss possible violations of these discrete
symmetries, including CPT, in the presence of instantons and the
Adler-Bell-Jackiw anomaly.Comment: Extended, and replaced with LaTex file. 25 Page
Heavy Higgs production and decay via and irreducible backgrounds at Next Linear Colliders
The complete matrix element for e^+e^-\ar b\bar bZ^0Z^0 has been computed
at tree--level and applied to --production followed by Z^0\ar b\bar b
and H^0\ar Z^0Z^0, including all the irreducible background, at Next Linear
Colliders. We find that, assuming flavour identification of the --decay
products, this channel, together with e^+e^-\ar b\bar bW^+W^- in which
Z^0H^0\ar (b\bar b)(W^+W^-), can be important for the study of the parameters
of the Standard Model Higgs boson over the heavy mass range 2M_{Z^0}\Ord
M_{H^0}\Ord 2{m_t}.Comment: 24 pages, LaTeX (uses Feynman), 7 figures (.ps files or hardcopies of
figs.2-7 available upon request
Enantiopure distorted ribbon-shaped nanographene combining two-photon absorptionbased upconversion and circularly polarized luminescence
Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of
optical properties in graphene-related materials, namely upconversion based on two-photon absorption
(TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule
of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar
lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This
system is shown to combine two-photon absorption and circularly polarized luminescence and
a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity
while the push–pull geometry and the extended network of sp2 carbons are factors favoring the
nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results.This project has received funding from the European Research
Council (ERC) under the European Union's Horizon 2020
research and innovation program (ERC-2015-STG-677023). We
also thank the Ministerio de Economía y Competitividad
(MINECO, Spain) (CTQ2015-70283-P, CTQ2014-53598-R,
MAT2014-54231-C4-1P, FIS2016-77578-R) and the “Unidad de
Excelencia Química Aplicada a Biomedicina y Medioambiente
(UGR)”. A. G. C., C. S. S. and C. M. C. acknowledge funding from
MINECO (Spain) for RyC-2013-12943, IJCI-2014-19291 and
BES-2016-076371 contracts, respectively. I. R. M. thanks UGR
(Spain) for a postdoctoral scholarship. I. M. and E. M. thank the
Fundação para a Ciência e a Tecnologia for financial support
(IF/00759/2013 and post-doc grant SFRH/BPD/75782/2011). We
thank the CSIRC-Alhambra for supercomputing facilities
Syndecan-1 regulates the biological activities of interleukin-34
IL-34 is a challenging cytokine sharing functional similarities with M-CSF through M-CSFR activation. It also plays a singular role that has recently been explained in the brain, through a binding to the receptor protein tyrosine phosphatase RPTPβ/ζ. The aim of this paper was to look for alternative binding of IL-34 on other cell types. Myeloid cells (HL-60, U-937, THP-1) were used as cells intrinsically expressing M-CSFR, and M-CSFR was expressed in TF-1 and HEK293 cells. IL-34 binding was studied by Scatchard and binding inhibition assays, using 125I-radiolabelled cytokines, and surface plasmon resonance. M-CSFR activation was analysed by Western blot after glycosaminoglycans abrasion, syndecan-1 overexpression or repression and addition of a blocking anti-syndecan antibody. M-CSF and IL-34 induced different patterns of M-CSFR phosphorylations, suggesting the existence of alternative binding for IL-34. Binding experiments and chondroitinase treatment confirmed low affinity binding to chondroitin sulphate chains on cells lacking both M-CSFR and RPTPβ/ζ. Amongst the proteoglycans with chondroitin sulphate chains, syndecan-1 was able to modulate the IL-34-induced M-CSFR signalling pathways. Interestingly, IL-34 induced the migration of syndecan-1 expressing cells. Indeed, IL-34 significantly increased the migration of THP-1 and M2a macrophages that was inhibited by addition of a blocking anti-syndecan-1 antibody. This paper provides evidence of alternative binding of IL-34 to chondroitin sulphates and syndecan-1 at the cell surface that modulates M-CSFR activation. In addition, IL-34-induced myeloid cell migration is a syndecan-1 dependent mechanism
Effects of Large CP violating phases on g_{\m}-2 in MSSM
Effects of CP violation on the supersymmetric electro-weak correction to the
anomalous magnetic moment of the muon are investigated with the most general
allowed set of CP violating phases in MSSM. The analysis includes contributions
from the chargino and the neutralino exchanges to the muon anomaly. The
supersymmetric contributions depend only on specific combinations of CP phases.
The independent set of such phases is classified. We analyse the effects of the
phases under the EDM constraints and show that large CP violating phases can
drastically affect the magnitude of the supersymmetric electro-weak
contribution to and may even affect its overall sign.Comment: 26 pages Latex file including 4 figure
M(atrix) Theory: Matrix Quantum Mechanics as a Fundamental Theory
A self-contained review is given of the matrix model of M-theory. The
introductory part of the review is intended to be accessible to the general
reader. M-theory is an eleven-dimensional quantum theory of gravity which is
believed to underlie all superstring theories. This is the only candidate at
present for a theory of fundamental physics which reconciles gravity and
quantum field theory in a potentially realistic fashion. Evidence for the
existence of M-theory is still only circumstantial---no complete
background-independent formulation of the theory yet exists. Matrix theory was
first developed as a regularized theory of a supersymmetric quantum membrane.
More recently, the theory appeared in a different guise as the discrete
light-cone quantization of M-theory in flat space. These two approaches to
matrix theory are described in detail and compared. It is shown that matrix
theory is a well-defined quantum theory which reduces to a supersymmetric
theory of gravity at low energies. Although the fundamental degrees of freedom
of matrix theory are essentially pointlike, it is shown that higher-dimensional
fluctuating objects (branes) arise through the nonabelian structure of the
matrix degrees of freedom. The problem of formulating matrix theory in a
general space-time background is discussed, and the connections between matrix
theory and other related models are reviewed.Comment: 56 pages, 3 figures, LaTeX, revtex style; v2: references adde
Production of neutral and charged Higgs bosons of the MSSM at the future e-gamma colliders
A complete study for the production of neutral (h^0, H^0, A^0 (= \phi^0_i))
and charged Higgs (H^\pm) bosons at electron-photon colliders is presented in
the context of the minimal supersymmetric standard model.
A particular choice of the non-linear R_\xi gauge is used to evaluate the
amplitudes of the reaction e-gamma --> e \phi^0_i.
The resulting cross section indicates that it will be possible to detect a
signal from the neutral Higgs bosons for most regions of parameter space at the
future linear colliders with \sqrt{s}=500 GeV through the reaction e gamma -->
e \phi^0_i. This reaction also offers the interesting possibility to measure
the Higgs mass through the detection of the outgoing electron.
The production of the charged Higgs boson through the reaction e gamma -->
\nu_e H^\pm$ has in general smaller values for the cross section, which seems
more difficult to observe.Comment: submitted to Phys. Rev.
- …