14,595 research outputs found
Activation of Ras-ERK pathway by Fgf8 and its downregulation by Sprouty2 for the isthmus organizing activity
In the previous studies, we showed that strong Fgf8 signaling activates the Ras-ERK pathway to induce cerebellum. Here, we show importance of negative regulation of this pathway. 'Prolonged' activation of ERK by misexpression of _Fgf8b_ and dominant-negative _Sprouty2_ (_dnSprouty2_) did not change the fate of the mesencephalic alar plate. Downregulation of ERK activity using a MEK inhibitor, U0126, or by tetracycline dependent Tet-off system after co-expression of _Fgf8b_ and _dnSprouty2_, forced the mesencephalic alar plate to differentiate into cerebellum. We then paid attention to Mkp3. After misexpression of _dnMkp3_ and _Fgf8b_, slight downregulation of ERK activity occurred, which may be due to Sprouty2, and the mesencephalon transformed to the isthmus-like structure. The results indicate that ERK must be once upregulated and then be downregulated for cerebellar differentiation, and that differential ERK activity level established by negative regulators receiving Fgf8 signal may determine regional specificity of mesencephalon and metencephalon
Window effect in the power spectrum analysis of a galaxy redshift survey
We investigate the effect of the window function on the multipole power
spectrum in two different ways. First, we consider the convolved power spectrum
including the window effect, which is obtained by following the familiar (FKP)
method developed by Feldman, Kaiser and Peacock. We show how the convolved
multipole power spectrum is related to the original power spectrum, using the
multipole moments of the window function. Second, we investigate the
deconvolved power spectrum, which is obtained by using the Fourier
deconvolution theorem. In the second approach, we measure the multipole power
spectrum deconvolved from the window effect. We demonstrate how to deal with
the window effect in these two approaches, applying them to the Sloan Digital
Sky Survey (SDSS) luminous red galaxy (LRG) sample.Comment: 22 pages, 11 figures, references adde
Neutrino Induced 4He Break-up Reaction -- Application of the Maximum Entropy Method in Calculating Nuclear Strength Function
The maximum entropy method is examined as a new tool for solving the
ill-posed inversion problem involved in the Lorentz integral transformation
(LIT) method. As an example, we apply the method to the spin-dipole strength
function of 4He. We show that the method can be successfully used for inversion
of LIT, provided the LIT function is available with a sufficient accuracy.Comment: 5 pages, 2 figures. Poster presented by TM at the International
Workshop on Neutrino-Nucleus Interaction in the Few-GeV Region (NuInt15),
Novenber 16-21 2015, Osaka, Japa
Toda Lattice and Tomimatsu-Sato Solutions
We discuss an analytic proof of a conjecture (Nakamura) that solutions of
Toda molecule equation give those of Ernst equation giving Tomimatsu-Sato
solutions of Einstein equation. Using Pfaffian identities it is shown for Weyl
solutions completely and for generic cases partially.Comment: LaTeX 8 page
Constraint on Heavy Element Production in Inhomogeneous Big-Bang Nucleosynthesis from The Light-Element Observations
We investigate the observational constraints on the inhomogeneous big-bang
nucleosynthesis that Matsuura et al. suggested the possibility of the heavy
element production beyond Li in the early universe. From the
observational constraints on light elements of He and D, possible regions
are found on the plane of the volume fraction of the high density region
against the ratio between high-and low-density regions. In these allowed
regions, we have confirmed that the heavy elements beyond Ni can be produced
appreciably, where - and/or -process elements are produced well
simultaneously.Comment: 11 pages, 7 figures, 4 Tables., accepted in Journal of Astrophysics.
arXiv admin note: substantial text overlap with arXiv:1007.046
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