2-loop Quantum Yang-Mills Condensate as Dark Energy

In seeking a model solving the coincidence problem, the effective Yang-Mills condensate (YMC) is an alternative candidate for dark energy. A study is made for the model up to the 2-loop order of quantum corrections. It is found that, like in the 1-loop model, for generic initial conditions during the radiation era, there is always a desired tracking solution, yielding the current status $\Omega_\Lambda \simeq 0.73$ and $\Omega_m \simeq 0.27$. As the time $t\to \infty$ the dynamics is a stable attractor. Thus the model naturally solves the coincidence problem of dark energy. Moreover, if YMC decays into matter, its equation of state (EoS) crosses -1 and takes $w\sim -1.1$, as indicated by the recent observations.Comment: 9 pages, 4 figures. Phys. Lett. B accepte

Nanoelectromechanics of Piezoresponse Force Microscopy

To achieve quantitative interpretation of Piezoresponse Force Microscopy (PFM), including resolution limits, tip bias- and strain-induced phenomena and spectroscopy, analytical representations for tip-induced electroelastic fields inside the material are derived for the cases of weak and strong indentation. In the weak indentation case, electrostatic field distribution is calculated using image charge model. In the strong indentation case, the solution of the coupled electroelastic problem for piezoelectric indentation is used to obtain the electric field and strain distribution in the ferroelectric material. This establishes a complete continuum mechanics description of the PFM contact mechanics and imaging mechanism. The electroelastic field distribution allows signal generation volume in PFM to be determined. These rigorous solutions are compared with the electrostatic point charge and sphere-plane models, and the applicability limits for asymptotic point charge and point force models are established. The implications of these results for ferroelectric polarization switching processes are analyzed.Comment: 81 pages, 19 figures, to be published in Phys. Rev.

A study on the frequency modulation doppler global velocimetry system

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The principle of the frequency modulation Doppler global velocimetry (FM-DGV) is presented in this paper. A FM-DGV system has been developed, of which a CCD camera was used as the detector to receive scattering light. The system was made up of a narrow band laser, a light-sheet-generating optics, an iodine cell, a frequency monitor unit, and an image acquisition CCD camera. Based on this system, measurements have been carried out on the velocity distributions of a rotating wheel. The results show that the system works well, and the maximum velocity measurement error is less than 2m/s.dc201

Magnetic properties and switching volumes of nanocrystalline SmFeSiC films

Systematic studies of the effects of Si addition on the magnetic and magnetization reversal properties of SmFeSiC films are presented. The magnetic switching volume and other magnetic parameters (e.g., coercivity) are strongly dependent upon the Si content. Correlations between switching volume, coercivity, and the intergrain interactions are discussed

Outcome value and task aversiveness impact task procrastination through separate neural pathways

The temporal decision model of procrastination has proposed that outcome value and task aversiveness are two separate aspects accounting for procrastination. If true, the human brain is likely to implicate separate neural pathways to mediate the effect of outcome value and task aversiveness on procrastination. Outcome value is plausibly constructed via a hippocampus-based pathway because of the hippocampus's unique role in episodic prospection. In contrast, task aversiveness might be represented through an amygdala-involved pathway. In the current study, participants underwent fMRI scanning when viewing both tasks and future outcomes, without any experimental instruction imposed. The results revealed that outcome value increased activations in the caudate, and suppressed procrastination through a hippocampus-caudate pathway. In contrast, task aversiveness increased activations in the anterior insula, and increased procrastination via an amygdala-insula pathway. In sum, this study demonstrates that people can incorporate both outcome value and task aversiveness into task valuation to decide whether to procrastinate or not; and it elucidates the separate neural pathways via which this occurs.Action Contro

SNX27 and SORLA interact to reduce amyloidogenic subcellular distribution and processing of amyloid precursor protein

Proteolytic generation of amyloidogenic amyloid {beta} (A{beta}) fragments from the amyloid precursor protein (APP) significantly contributes to Alzheimer's disease (AD). Although amyloidogenic APP proteolysis can be affected by trafficking through genetically associated AD components such as SORLA, how SORLA functionally interacts with other trafficking components is yet unclear. Here, we report that SNX27, an endosomal trafficking/recycling factor and a negative regulator of the {gamma}-secretase complex, binds to the SORLA cytosolic tail to form a ternary complex with APP. SNX27 enhances cell surface SORLA and APP levels in human cell lines and mouse primary neurons, and depletion of SNX27 or SORLA reduces APP endosome-to-cell surface recycling kinetics. SNX27 overexpression enhances the generation of cell surface APP cleavage products such as soluble alpha-APP C-terminal fragment (CTF{alpha}) in a SORLA-dependent manner. SORLA-mediated A{beta} reduction is attenuated by downregulation of SNX27. This indicates that an SNX27/SORLA complex functionally interacts to limit APP distribution to amyloidogenic compartments, forming a non-amyloidogenic shunt to promote APP recycling to the cell surface