Dark matter interacts with variable vacuum energy

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) scenario with two interacting components, dark matter and variable vacuum energy (VVE) densities, plus two decoupled components, one is a baryon term while the other behaves as a radiation component. We consider a linear interaction in the derivative dark component density. We apply the $\chi^2$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for the model. It turns out that our model fulfills the severe bound of $\Omega_{x}(z\simeq 1100)<0.009$ at $2\sigma$ level, so is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from Planck survey, the future constraints achievable by Euclid and CMBPol experiments, reported for the behavior of the dark energy at early times, and fulfills the stringent bound $\Omega_{x}(z\simeq 10^{10})<0.04$ at $2\sigma$ level in the big-bang nucleosynthesis epoch. We also examine the cosmic age problem at high redshift associated with the old quasar APM 08279+5255 and estimate the age of the universe today.Comment: 8 pages, 12 figures. arXiv admin note: text overlap with arXiv:1310.5335 by other author

Parkin interacts with Ambra1 to induce mitophagy

Mutations in the gene encoding Parkin are a major cause of recessive Parkinson's disease. Recent work has shown that Parkin translocates from the cytosol to depolarized mitochondria and induces their autophagic removal (mitophagy). However, the molecular mechanisms underlying Parkin-mediated mitophagy are poorly understood. Here, we investigated whether Parkin interacts with autophagy-regulating proteins. We purified Parkin and associated proteins from HEK293 cells using tandem affinity purification and identified the Parkin interactors using mass spectrometry. We identified the autophagy-promoting protein Ambra1 (activating molecule in Beclin1-regulated autophagy) as a Parkin interactor. Ambra1 activates autophagy in the CNS by stimulating the activity of the class III phosphatidylinositol 3-kinase (PI3K) complex that is essential for the formation of new phagophores. We found Ambra1, like Parkin, to be widely expressed in adult mouse brain, including midbrain dopaminergic neurons. Endogenous Parkin and Ambra1 coimmunoprecipitated from HEK293 cells, SH-SY5Y cells, and adult mouse brain. We found no evidence for ubiquitination of Ambra1 by Parkin. The interaction of endogenous Parkin and Ambra1 strongly increased during prolonged mitochondrial depolarization. Ambra1 was not required for Parkin translocation to depolarized mitochondria but was critically important for subsequent mitochondrial clearance. In particular, Ambra1 was recruited to perinuclear clusters of depolarized mitochondria and activated class III PI3K in their immediate vicinity. These data identify interaction of Parkin with Ambra1 as a key mechanism for induction of the final clearance step of Parkin-mediated mitophagy

A Reusable Interaction Management Module: Use case for Empathic Robotic Tutoring

We demonstrate the workings of a stochastic Interaction Management and showcase this working as part of a learning environment that includes a robotic tutor who interacts with students, helping them through a pedagogical task

Quadrupole Interaction of Non-diffracting Beams with Two-Level Atoms

Recently it has been shown that the quadrupole interactions can be improved significantly as the atom interacts at near resonance with the Laguerre-Gaussian (LG) mode. In this paper, we illustrate that other kinds of optical vortex can be also led to a considerable enhancement of quadrupole interaction when the atom interacts with optical modes at near resonance. The calculations are performed on an interesting situation with Cs atom, where the process is concerned with dipole-forbidden and quadrupole-allowed transitions with a convenable choice of atomic and optical mode parameters. In this direction, we show that the quadrupole transitions can be significantly enhanced and therefore they can play an interesting role and lead to new features of atom-light interaction, which can have some constructive implications in experiments.Comment: 9 pages, 10 figure

Spin flip probability of electron in a uniform magnetic field

The probability of a spin flip of an electron is calculated. It is assumed that the electron resides in a uniform magnetic field and interacts with an incoming electromagnetic pulse. The scattering matrix is constructed and the time needed to flip the spin is calculated.Comment: 4 pages, 0 figure

FOXP3 interacts with hnRNPF to modulate pre-mRNA alternative splicing

FOXP3 promotes the development and function of regulatory T cells mainly through regulating the transcription of target genes. RNA alternative splicing has been implicated in a wide range of physiological and pathophysiological processes. We report here that FOXP3 associates with heterogeneous nuclear ribonucleoprotein (hnRNP) F through the exon 2-encoded region of FOXP3 and the second quasi-RNA recognition motif (qRRM) of hnRNPF. FOXP3 represses the ability of hnRNPF to bind to its target pre-mRNA and thus modulates RNA alternative splicing. Furthermore, overexpression of mouse hnRNPF in in vitro-differentiated regulatory T cells (Tregs) reduced their suppressive function. Thus, our studies identify a novel mechanism by which FOXP3 regulates mRNA alternative splicing to modulate the function of regulatory T cells