415,317 research outputs found
Different steady states for spin currents in noncollinear multilayers
We find there are at least two different steady states for transport across
noncollinear magnetic multilayers. In the conventional one there is a
discontinuity in the spin current across the interfaces which has been
identified as the source of current induced magnetic reversal; in the one
advocated herein the spin torque arises from the spin accumulation transverse
to the magnetization of a magnetic layer. These two states have quite different
attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics:
Condensed Matte
Nonsmooth and level-resolved dynamics illustrated with the tight binding model
We point out that in the first order time-dependent perturbation theory, the
transition probability may behave nonsmoothly in time and have kinks
periodically. Moreover, the detailed temporal evolution can be sensitive to the
exact locations of the eigenvalues in the continuum spectrum, in contrast to
coarse-graining ideas. Underlying this nonsmooth and level-resolved dynamics is
a simple equality about the sinc function \sinc x \equiv \sin x / x. These
physical effects appear in many systems with approximately equally spaced
spectra, and is also robust for larger-amplitude coupling beyond the domain of
perturbation theory. We use a one-dimensional periodically driven tight-binding
model to illustrate these effects, both within and outside the perturbative
regime.Comment: Link with the Paley-Wiener theorem and another reference is added;
any comment is welcome and will be greatly appreciated
PPM1D phosphatase, a target of p53 and RBM38 RNA-binding protein, inhibits p53 mRNA translation via dephosphorylation of RBM38.
PPM1D phosphatase, also called wild-type p53-induced phosphatase 1, promotes tumor development by inactivating the p53 tumor suppressor pathway. RBM38 RNA-binding protein, also called RNPC1 and a target of p53, inhibits p53 messenger RNA (mRNA) translation, which can be reversed by GSK3 protein kinase via phosphorylation of RBM38 at serine 195. Here we showed that ectopic expression of RBM38 increases, whereas knockdown of RBM38 inhibits, PPM1D mRNA translation. Consistent with this, we found that RBM38 directly binds to PPM1D 3'-untranslated region (3'-UTR) and promotes expression of a heterologous reporter gene that carries PPM1D 3'-UTR in a dose-dependent manner. Interestingly, we showed that PPM1D directly interacts with and dephosphorylates RBM38 at serine 195. Furthermore, we showed that PPM1D modulates p53 mRNA translation and p53-dependent growth suppression through dephosphorylation of RBM38. These findings provide evidence that the crosstalk between PPM1D and RBM38, both of which are targets and modulators of p53, has a critical role in p53 expression and activity
Witnessing a Poincar\'e recurrence with Mathematica
The often elusive Poincar\'e recurrence can be witnessed in a completely
separable system. For such systems, the problem of recurrence reduces to the
classic mathematical problem of simultaneous Diophantine approximation of
multiple numbers. The latter problem then can be somewhat satisfactorily solved
by using the famous Lenstra-Lenstra-Lov\'{a}sz (LLL) algorithm, which is
implemented in the Mathematica built-in function \verb"LatticeReduce". The
procedure is illustrated with a harmonic chain. The incredibly large recurrence
times are obtained exactly. They follow the expected scaling law very well.Comment: 8 pages, 5 figure
Light scattering detection of quantum phases of ultracold atoms in optical lattices
Ultracold atoms loaded on optical lattices can provide unprecedented
experimental systems for the quantum simulations and manipulations of many
quantum phases. However, so far, how to detect these quantum phases effectively
remains an outstanding challenge. Here, we show that the optical Bragg
scattering of cold atoms loaded on optical lattices can be used to detect many
quantum phases which include not only the conventional superfluid and Mott
insulating phases, but also other important phases such as various kinds of
density waves (CDW), valence bond solids (VBS), CDW supersolids and VBS
supersolids.Comment: 4 pages, 3 colour figures, to appear in Phys. Rev. A, Rapid
Communicatio
Exotic Hill Problem: Hall motions and symmetries
Our previous study of a system of bodies assumed to move along almost
circular orbits around a central mass, approximately described by Hill's
equations, is extended to "exotic" [alias non-commutative] particles. For a
certain critical value of the angular velocity, the only allowed motions follow
the Hall law. Translations and generalized boosts span two independent
Heisenberg algebras with different central parameters. In the critical case,
the symmetry reduces to a single Heisenberg algebra.Comment: RevTeX, 4 pages, 4 figure
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