The physical picture behind the oscillating sign of drag in high Landau levels

We consider the oscillating sign of the drag resistivity and its anomalous temperature dependence discovered experimentally in a bi-layer system in the regime of the integer quantum Hall effect. We attribute the oscillating sign to the effect of disorder on the relation between an adiabatic momentum transfer to an electron and the displacement of its position. While in the absence of any Landau level mixing a momentum transfer $\hbar \bf q$ implies a displacement of $ql_H^2$ (with $l_H$ being the magnetic length), Landau level mixing induced by short range disorder adds a potentially large displacement that depends on the electron's energy, with the sign being odd with respect to the distance of that energy from the center of the Landau level. We show how the oscillating sign of drag disappears when the disorder is smooth and when the electronic states are localized

Electronic Cooling in Graphene

Energy transfer to acoustic phonons is the dominant low-temperature cooling channel of electrons in a crystal.For cold neutral graphene we find that the weak cooling power of its acoustical modes relative to the heat capacity of the system leads to a power law decay of the electronic temperature when far from equilibrium. For heavily doped graphene a high electronic temperature is shown to initially decrease linearly with time at a rate proportional to n^(3/2) with n being the electronic density. We discuss the relative importance of optical and acoustic phonons to cooling.Comment: corrected typos and added reference

Exclusion of the Locus for Autosomal Recessive Pseudohypoaldosteronism Type 1 from the Mineralocorticoid Receptor Gene Region on Human Chromosome 4q by Linkage Analysis.

Pseudohypoaldosteronism type 1 (PHA1) is an uncommon inherited disorder characterized by salt-wasting in infancy arising from target organ unresponsiveness to mineralocorticoids. Clinical expression of the disease varies from severely affected infants who may die to apparently asymptomatic individuals. Inheritance is Mendelian and may be either autosomal dominant or autosomal recessive. A defect in the mineralocorticoid receptor has been implicated as a likely cause of PHA1. The gene for human mineralocorticoid receptor (MLR) has been cloned and physically mapped to human chromosome 4q31.1-31.2. The etiological role of MLR in autosomal recessive PHA1 was investigated by performing linkage analysis between PHA1 and three simple sequence length polymorphisms (D4S192, D4S1548, and D4S413) on chromosome 4q in 10 consanguineous families. Linkage analysis was carried out assuming autosomal recessive inheritance with full penetrance and zero phenocopy rate using the MLINK program for two-point analysis and the HOMOZ program for multipoint analysis. Lod scores of less than -2 were obtained over the whole region from D4S192 to D4S413 encompassing MLR. This provdes evidence against MLR as the site of mutations causing PHA1 in the majority of autosomal recessive families

Moire bands in twisted double-layer graphene

A moire pattern is formed when two copies of a periodic pattern are overlaid with a relative twist. We address the electronic structure of a twisted two-layer graphene system, showing that in its continuum Dirac model the moire pattern periodicity leads to moire Bloch bands. The two layers become more strongly coupled and the Dirac velocity crosses zero several times as the twist angle is reduced. For a discrete set of magic angles the velocity vanishes, the lowest moire band flattens, and the Dirac-point density-of-states and the counterflow conductivity are strongly enhanced

d0 Perovskite-Semiconductor Electronic Structure

We address the low-energy effective Hamiltonian of electron doped d0 perovskite semiconductors in cubic and tetragonal phases using the k*p method. The Hamiltonian depends on the spin-orbit interaction strength, on the temperature-dependent tetragonal distortion, and on a set of effective-mass parameters whose number is determined by the symmetry of the crystal. We explain how these parameters can be extracted from angle resolved photo-emission, Raman spectroscopy, and magneto-transport measurements and estimate their values in SrTiO3

Penile Growth in Response to Human Chorionic Gonadotropin (hCG) Treatment in Patients with Idiopathic Hypogonadotrophic Hypogonadism

Penile growth is under androgenic control. Human chorionic gonadotropin (hCG) has a stimulatory effect on testicular steroidogenesis and penile growth. The purpose of this study was to evaluate the effect of hCG treatment on the gonadal response and penile growth in male idiopathic hypogonadotrophic hypogonadism (IHH) presenting with micropenis. A total of 20 IHH patients who met the criteria for micropenis were included in this study. hCG (1,500-2,000 IU) was administrated intramuscularly, 3 times per week, for 8 weeks. Basic laboratory and hormonal indexes (including serum testosterone and LH levels), penis length (flaccid and stretched), and testicular volume were measured before and 24 weeks after hCG treatment. The patients' mean age was 18.9 years (range, 12 to 24 years). The mean serum testosterone level was significantly increased after hCG treatment (baseline, 2, 4, 12, and 24 weeks: 0.90±1.35 ng/ml, 1.77±1.31 ng/ml, 3.74±2.24 ng/ml, 5.49±1.70 ng/ml, and 5.58±1.75 ng/ml, respectively; p<0.05). Mean penile length also increased significantly 24 weeks after treatment (flaccid length: from 3.39±1.03 cm to 5.14±1.39 cm; stretched length: from 5.41±1.43 cm to 7.45±1.70 cm; p<0.001). Mean testicular volumes increased significantly as well (left: from 5.45 cc to 6.83 cc; right: from 5.53 cc to 7.03 cc). There were no remarkable adverse effects of the hCG treatment. The hCG treatment increased the serum testosterone level, penile length, and testicular volume in IHH patients. Our results suggest that hCG treatment has a beneficial effect on gonadal function and penile growth in patients with IHH presenting with micropenis

Room-Temperature Superfluidity in Graphene Bilayers

Because graphene is an atomically two-dimensional gapless semiconductor with nearly identical conduction and valence bands, graphene-based bilayers are attractive candidates for high-temperature electron-hole pair condensation. We present estimates which suggest that the Kosterlitz-Thouless temperatures of these two-dimensional counterflow superfluids can approach room temperature.Comment: 5 pages, 3 figures; updated discussion and references; to appear in PRB Rapid Com

Moire Butterflies

The Hofstadter butterfly spectral patterns of lattice electrons in an external magnetic field yield some of the most beguiling images in physics. Here we explore the magneto-electronic spectra of systems with moire spatial patterns, concentrating on the case of twisted bilayer graphene. Because long-period spatial patterns are accurately formed at small twist angles, fractal butterfly spectra and associated magneto-transport and magneto-mechanical anomalies emerge at accessible magnetic field strengths