Capacitance of a Double-Heterojunction GaAs/AlGaAs Structure Subjected to In-Plane Magnetic Fields: Results of Self-Consistent Calculations

The capacitance of a double-heterojunction structure with a wide GaAs undoped layer embedded between two selectively doped AlGaAs barriers is calculated self-consistently as a function of intensity of the in-plane magnetic field. With increasing field intensity the capacitance initially increases and after reaching a maximum decreases toward a high field limit which is less than its zero field value. This behaviour is attributed to 'breathing', or charge redistribution, of the 2D electron gas at individual heterojunctions due to a combination of the confining potential and the magnetic field.Comment: LaTeX, 9 pages, 7 figs. available on request from [email protected] in 1 PS file (compressed and uuencoded

Purely orbital diamagnetic to paramagnetic fluctuation of quasi two-dimensional carriers under in-plane magnetic field

An external magnetic field, $H$, applied parallel to a quasi two-dimensional system modifies quantitatively and qualitatively the density of states. Using a self-consistent numerical approach, we study how this affects the entropy, $S$, the free energy, $F$, and the magnetization, $M$, for different sheet carrier concentrations, $N_s$. As a prototype system we employ III-V double quantum wells. We find that although $M$ is mainly in the opposite direction of $H$, the system is not linear. Surprisingly $\partial M / \partial H$ swings between negative and positive values, i.e., we predict an entirely orbital diamagnetic to paramagnetic fluctuation. This phenomenon is important compared to the ideal de Haas-van Alphen effect i.e. the corresponding phenomenon under perpendicular magnetic field.Comment: 4 pages, 6 figure

Self-Consistent Electron Subbands of Gaas/Algaas Heterostructure in Magnetic Fields Parallel to the Interface

The effect of strong magnetic fields parallel to GaAs/AlGaAs interface on the subband structure of a 2D electron layer is ivestigated theoretically. The system with two levels occupied in zero magnetic field is considered and the magnetic field induced depletion of the second subband is studied. The confining potential and the electron dispersion relations are calculated self-consistently, the electron- electron interaction is taken into account in the Hartree approximation.Comment: written in LaTeX, 8 pages, 4 figs. available on request from [email protected]

Golgi localized β1-adrenergic receptors stimulate Golgi PI4P hydrolysis by PLCε to regulate cardiac hypertrophy.

Increased adrenergic tone resulting from cardiovascular stress leads to development of heart failure, in part, through chronic stimulation of β1 adrenergic receptors (βARs) on cardiac myocytes. Blocking these receptors is part of the basis for β-blocker therapy for heart failure. Recent data demonstrate that G protein-coupled receptors (GPCRs), including βARs, are activated intracellularly, although the biological significance is unclear. Here we investigated the functional role of Golgi βARs in rat cardiac myocytes and found they activate Golgi localized, prohypertrophic, phosphoinositide hydrolysis, that is not accessed by cell surface βAR stimulation. This pathway is accessed by the physiological neurotransmitter norepinephrine (NE) via an Oct3 organic cation transporter. Blockade of Oct3 or specific blockade of Golgi resident β1ARs prevents NE dependent cardiac myocyte hypertrophy. This clearly defines a pathway activated by internal GPCRs in a biologically relevant cell type and has implications for development of more efficacious β-blocker therapies