53 research outputs found
Moduli trapping mechanism in modular flavor symmetric models
We discuss how the moduli in modular flavor symmetric models dynamically
select enhanced symmetry points at which the residual modular symmetry renders
extra matter fields massless. The moduli dynamics non-perturbatively produces
the extra matter particles, which gives (time-dependent) effective potential
that traps the moduli to enhanced symmetry points. We show analytic estimates
of particle production rate consistent with numerical results, and the dynamics
of moduli based on the analytic estimates.Comment: 35 pages, 14 figure
Statistics of correlated percolation in a bacterial community
Signal propagation over long distances is a ubiquitous feature of multicellular communities, but cell-to-cell variability can cause propagation to be highly heterogeneous. Simple models of signal propagation in heterogenous media, such as percolation theory, can potentially provide a quantitative understanding of these processes, but it is unclear whether these simple models properly capture the complexities of multicellular systems. We recently discovered that in biofilms of the bacterium Bacillus subtilis, the propagation of an electrical signal is statistically consistent with percolation theory, and yet it is reasonable to suspect that key features of this system go beyond the simple assumptions of basic percolation theory. Indeed, we find here that the probability for a cell to signal is not independent from other cells as assumed in percolation theory, but instead is correlated with its nearby neighbors. We develop a mechanistic model, in which correlated signaling emerges from cell division, phenotypic inheritance, and cell displacement, that reproduces the experimentally observed correlations. We find that the correlations do not significantly affect the spatial statistics, which we rationalize using a renormalization argument. Moreover, the fraction of signaling cells is not constant in space, as assumed in percolation theory, but instead varies within and across biofilms. We find that this feature lowers the fraction of signaling cells at which one observes the characteristic power-law statistics of cluster sizes, consistent with our experimental results. We validate the model using a mutant biofilm whose signaling probability decays along the propagation direction. Our results reveal key statistical features of a correlated signaling process in a multicellular community. More broadly, our results identify extensions to percolation theory that do or do not alter its predictions and may be more appropriate for biological systems.P50 GM085764 - NIGMS NIH HHS; Howard Hughes Medical Institute; R01 GM121888 - NIGMS NIH HHSPublished versio
Quark hierarchical structures in modular symmetric flavor models at level 6
We study modular symmetric quark flavor models without fine-tuning. Mass
matrices are written in terms of modular forms, and modular forms in the
vicinity of the modular fixed points become hierarchical depending on their
residual charges. Thus modular symmetric flavor models in the vicinity of the
modular fixed points have a possibility to describe mass hierarchies without
fine-tuning. Since describing quark hierarchies without fine-tuning requires
residual symmetry with , we focus on modular symmetry
in the vicinity of the cusp where residual symmetry
remains. We use only modular forms belonging to singlet representations of
to make our analysis simple. Consequently, viable quark flavor
models are obtained without fine-tuning.Comment: 29 page
Modular symmetry in magnetized torus and orbifold models
We study the modular symmetry in magnetized torus and orbifold
models. The torus has the modular symmetry
. Magnetic flux background breaks the modular
symmetry to a certain normalizer . We classify remaining modular
symmetries by magnetic flux matrix types. Furthermore, we study the modular
symmetry for wave functions on the magnetized and certain orbifolds.
It is found that wave functions on magnetized as well as its orbifolds
behave as the Siegel modular forms of weight and
, which is the metapletic congruence subgroup of the
double covering group of , . Then, wave
functions transform non-trivially under the quotient group,
, where the
level is related to the determinant of the magnetic flux matrix.
Accordingly, the corresponding four-dimensional (4D) chiral fields also
transform non-trivially under modular flavor
transformation with modular weight . We also study concrete modular
flavor symmetries of wave functions on magnetized orbifolds.Comment: 53 page
Zero-modes in magnetized orbifold models through modular symmetry
We study of fermion zero-modes on magnetized orbifolds. In
particular, we focus on non-factorizable orbifolds, i.e. and
corresponding to and Lie lattices
respectively. The number of degenerated zero-modes corresponds to the
generation number of low energy effective theory in four dimensional
space-time. We find that three-generation models preserving 4D
supersymmetry can be realized by magnetized , but not by
. We use modular transformation for the
analyses.Comment: 37 pages, 2 figure
modular symmetry in flavor structures: quark flavor models and Siegel modular forms for
We study an approach to construct Siegel modular forms from .
Zero-mode wave functions on with magnetic flux background behave Siegel
modular forms at the origin. Then -symmetries partially break depending on
the form of background magnetic flux. We study the background such that three
-symmetries , and as well as the -symmetry
remain.Consequently, we obtain Siegel modular forms with three moduli
parameters , which are multiplets of finite
modular groups. We show several examples. As one of examples, we study Siegel
modular forms for in detail. Then, as a
phenomenological applicantion, we study quark flavor models using Siegel
modular forms for . Around the cusp,
, the Siegel modular forms have hierarchical values depending
on their -charges. We show the deviation of from the cusp can
generate large quark mass hierarchies without fine-tuning. Furthermore CP
violation is induced by deviation of from imaginary axis.Comment: 54 page
Quark mass hierarchies and CP violation in modular symmetric flavor models
We study modular symmetric flavor models to
realize quark mass hierarchies and mixing angles without fine-tuning. Mass
matrices are written in terms of modular forms. At modular fixed points and , is broken to residual symmetry. When the
modulus is deviated from the fixed points, modular forms show
hierarchies depending on their residual charges. Thus, we obtain hierarchical
structures in mass matrices. Since we begin with ,
the residual symmetry is which can generate
sufficient hierarchies to realize quark mass ratios and absolute values of the
CKM matrix without fine-tuning. Furthermore, CP violation
is studied. We present necessary conditions for CP violation caused by the
value of . We also show possibilities to realize observed values of the
Jarlskog invariant , quark mass ratios and CKM matrix
simultaneously, if adjustments in
coefficients of Yukawa couplings are allowed.Comment: 41 pages, 3 figure
Anti-Siglec-15 antibody suppresses bone resorption by inhibiting osteoclast multinucleation without attenuating bone formation
Anti-resorptive drugs are widely used for the treatment of osteoporosis, but excessive inhibition of osteoclastogenesis can suppress bone turnover and cause the deterioration of bone quality. Sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) is a transmembrane protein expressed on osteoclast precursor cells and mature osteoclasts. Siglec-15 regulates proteins containing immunoreceptor tyrosine-based activation motif (ITAM) domains, which then induce nuclear factor of activated T-cells 1 (NFATc1), a master transcription factor of osteoclast differentiation. Anti-Siglec-15 antibody modulates ITAM signaling in osteoclast precursors and inhibits the maturation of osteoclasts in vitro. However, in situ pharmacological effects, particularly during postmenopausal osteoporosis, remain unclear. Here, we demonstrated that anti-Siglec-15 antibody treatment protected against ovariectomy-induced bone loss by specifically inhibiting the generation of multinucleated osteoclasts in vivo. Moreover, treatment with anti-Siglec-15 antibody maintained bone formation to a greater extent than with risedronate, the first-line treatment for osteoporosis. Intravital imaging revealed that anti-Siglec-15 antibody treatment did not cause a reduction in osteoclast motility, whereas osteoclast motility declined following risedronate treatment. We evaluated osteoclast activity using a pH-sensing probe and found that the bone resorptive ability of osteoclasts was lower following anti-Siglec-15 antibody treatment compared to after risedronate treatment. Our findings suggest that anti-Siglec-15 treatment may have potential as an anti-resorptive therapy for osteoporosis, which substantially inhibits the activity of osteoclasts while maintaining physiological bone coupling.Tsukazaki H., Kikuta J., Ao T., et al. Anti-Siglec-15 antibody suppresses bone resorption by inhibiting osteoclast multinucleation without attenuating bone formation. Bone 152, 116095 (2021); https://doi.org/10.1016/j.bone.2021.116095
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