Phase Diagrams for the ν\nu = 1/2 Fractional Quantum Hall Effect in Electron Systems Confined to Symmetric, Wide GaAs Quantum Wells

We report an experimental investigation of fractional quantum Hall effect (FQHE) at the even-denominator Landau level filling factor $\nu$ = 1/2 in very high quality wide GaAs quantum wells, and at very high magnetic fields up to 45 T. The quasi-two-dimensional electron systems we study are confined to GaAs quantum wells with widths $W$ ranging from 41 to 96 nm and have variable densities in the range of $\simeq 4 \times 10^{11}$ to $\simeq 4 \times 10^{10}$ cm$^{-2}$. We present several experimental phase diagrams for the stability of the $\nu=1/2$ FQHE in these quantum wells. In general, for a given $W$, the 1/2 FQHE is stable in a limited range of intermediate densities where it has a bilayer-like charge distribution; it makes a transition to a compressible phase at low densities and to an insulating phase at high densities. The densities at which the $\nu=1/2$ FQHE is stable are larger for narrower quantum wells. Moreover, even a slight charge distribution asymmetry destabilizes the $\nu=1/2$ FQHE and turns the electron system into a compressible state. We also present a plot of the symmetric-to-antisymmetric subband separation ($\Delta_{SAS}$), which characterizes the inter-layer tunneling, vs density for various $W$. This plot reveals that $\Delta_{SAS}$ at the boundary between the compressible and FQHE phases increases \textit{linearly} with density for all the samples. Finally, we summarize the experimental data in a diagram that takes into account the relative strengths of the inter-layer and intra-layer Coulomb interactions and $\Delta_{SAS}$. We conclude that, consistent with the conclusions of some of the previous studies, the $\nu=1/2$ FQHE observed in wide GaAs quantum wells with symmetric charge distribution is stabilized by a delicate balance between the inter-layer and intra-layer interactions, and is very likely described by a two-component ($\Psi_{311}$) state.Comment: Accepted for publication in Phys. Rev.

Multicomponent fractional quantum Hall states with subband and spin degrees of freedom

In wide GaAs quantum wells where two electric subbands are occupied we apply a parallel magnetic field or increase the electron density to cause a crossing of the two $N=0$ Landau levels of these subbands and with opposite spins. Near the crossing, the fractional quantum Hall states in the filling factor range $1<\nu<3$ exhibit a remarkable sequence of pseudospin polarization transitions resulting from the interplay between the spin and subband degrees of freedom. The field positions of the transitions yield a new and quantitative measure of the composite Fermions' discrete energy level separations. Surprisingly, the separations are smaller when the electrons have higher spin-polarization

Radiation-induced bystander effect in non-irradiated glioblastoma spheroid cells

Radiation-induced bystander effects (RIBEs) are detected in cells that are not irradiated but receive signals from treated cells. The present study explored these bystander effects in a U87MG multicellular tumour spheroid model. A medium transfer technique was employed to induce the bystander effect, and colony formation assay was used to evaluate the effect. Relative changes in expression of BAX, BCL2, JNK and ERK genes were analysed using RT-PCR to investigate the RIBE mechanism. A significant decrease in plating efficiency was observed for both bystander and irradiated cells. The survival fraction was calculated for bystander cells to be 69.48 and for irradiated cells to be 34.68. There was no change in pro-apoptotic BAX relative expression, but anti-apoptotic BCL2 showed downregulation in both irradiated and bystander cells. Pro-apoptotic JNK in bystander samples and ERK in irradiated samples were upregulated. The clonogenic survival data suggests that there was a classic RIBE in U87MG spheroids exposed to 4 Gy of X-rays, using a medium transfer technique. Changes in the expression of pro- and anti-apoptotic genes indicate involvement of both intrinsic apoptotic and MAPK pathways in inducing these effects. © 2015 The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology

Cosmology of f(Q)f(Q) gravity in non-flat Universe

We investigate the cosmological implications of $f(Q)$ gravity, which is a modified theory of gravity based on non-metricity, in non-flat geometry. We perform a detailed dynamical-system analysis keeping the $f(Q)$ function completely arbitrary. As we show, the cosmological scenario admits a dark-matter dominated point, as well as a dark-energy dominated de Sitter solution which can attract the Universe at late times. However, the main result of the present work is that there are additional critical points which exist solely due to curvature. In particular, we find that there are curvature-dominated accelerating points which are unstable and thus can describe the inflationary epoch. Additionally, there is a point in which the dark-matter and dark-energy density parameters are both between zero and one, and thus it can alleviate the coincidence problem. Finally, there is a saddle point which is completely dominated by curvature. In order to provide a specific example, we apply our general analysis to the power-law case, showing that we can obtain the thermal history of the Universe, in which the curvature density parameter may exhibit a peak at intermediate times. These features, alongside possible indications that non-zero curvature could alleviate the cosmological tensions, may serve as advantages for $f(Q)$ gravity in non-flat geometry

Investigation of multi-phase tubular permanent magnet linear generator for wave energy converters

In this article, an investigation into different magnetization topologies for a long stator tubular permanent magnet linear generator is performed through a comparison based on the cogging force disturbance, the power output, and the cost of the raw materials of the machines. The results obtained from finite element analysis simulation are compared with an existing linear generator described in [1]. To ensure accurate results, the generator developed in [1] is built with 3D CAD and simulated using the finite-element method, and the obtained results are verified with the source.The PRIMaRE project

Application of compressed sensing to the simulation of atomic systems

Compressed sensing is a method that allows a significant reduction in the number of samples required for accurate measurements in many applications in experimental sciences and engineering. In this work, we show that compressed sensing can also be used to speed up numerical simulations. We apply compressed sensing to extract information from the real-time simulation of atomic and molecular systems, including electronic and nuclear dynamics. We find that for the calculation of vibrational and optical spectra the total propagation time, and hence the computational cost, can be reduced by approximately a factor of five.Comment: 7 pages, 5 figure

Too Big to Manage: US Megabanks’ Competition by Innovation and the Microfoundations of Financialization

Disagreements over the systemic implications—the future—of financialization can be traced in part to the absence of sustained attention to the role of banking firms in driving this secular shift forward. That is, the financialization literature lacks an adequate microfoundation. Accounting for the drivers of financialization processes solely at the macro level overlooks the problems of how these processes came about and whether they are sustainable. This paper addresses this explanatory gap, arguing that a key independent microeconomic driver of increasing financialization did exist: the incessant efforts by money-centre banks in the USA to break out of Depression-era restrictions on their size, activities, and markets. These banks’ growth strategies in turbulent times led to an institutional (meso) shift—the rise of a megabank-centred shadow banking system—that now shapes global financial architecture even while operating in ways that are unsustainable. In short, too-big-to-manage megabanks are at the heart of the fragility and instability of the economy today

Jump-diffusion unravelling of a non Markovian generalized Lindblad master equation

The "correlated-projection technique" has been successfully applied to derive a large class of highly non Markovian dynamics, the so called non Markovian generalized Lindblad type equations or Lindblad rate equations. In this article, general unravellings are presented for these equations, described in terms of jump-diffusion stochastic differential equations for wave functions. We show also that the proposed unravelling can be interpreted in terms of measurements continuous in time, but with some conceptual restrictions. The main point in the measurement interpretation is that the structure itself of the underlying mathematical theory poses restrictions on what can be considered as observable and what is not; such restrictions can be seen as the effect of some kind of superselection rule. Finally, we develop a concrete example and we discuss possible effects on the heterodyne spectrum of a two-level system due to a structured thermal-like bath with memory.Comment: 23 page

SEX-SPECIFIC RESTORATION OF MK-801-INDUCED SENSORIMOTOR GATING DEFICIT BY ENVIRONMENTAL ENRICHMENT

Despite ample evidence of N-methyl-D-aspartate (NMDA) receptor dysfunction in schizophrenia, no study has addressed the effects of enriched environment (EE) on sensorimotor gating deficits induced by postnatal NMDA receptor blockade. We evaluated the effect of EE on sensorimotor gating (measured by prepulse inhibition, PPI), or on sensorimotor gating deficit induced by the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cy clohepten-5,10-imine maleate (MK-801) in both sexes of Wistar rats. Rats were injected with MK-801 (1 mg/kg) on postnatal days (P) 6–10. EE was provided from birth up to the time of experiments on P28–30 or P58–60. PPI data were collected at three prepulse intensities and then averaged to yield global PPI. MK-801 treatment reduced PPI significantly in both sexes. While EE per se had no significant effect on PPI, it restored MK-801-induced PPI deficit only in male rats. An extended period of EE did not influence PPI deficit in female rats. Our results indicate that postnatal exposure to MK-801 may exert long-lasting effects on neuronal circuits underlying sensorimotor gating. Sex-specific modulation of such effects by EE suggests sexually dimorphic mechanisms are involved. � 2015 IBRO. Published by Elsevier Ltd. All rights reserved