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© 2015 The Author(s).The caps on the ends of chromosomes, called telomeres, keep the ends of chromosomes from appearing as DNA double-strand breaks (DSBs) and prevent chromosome fusion. However, subtelomeric regions are sensitive to DSBs, which in normal c

Telomeres distinguish chromosome ends from double-strand breaks (DSBs) and prevent chromosome fusion. However, telomeres can also interfere with DNA repair, as shown by a deficiency in nonhomologous end joining (NHEJ) and an increase in large deletions at

A study conducted on the effect of the delayed rectifier K+ I(sub Kr) current in the left atrium of the rabbit heart shows that the early phase of the repolarization of the atrial action potentials is controlled by I(sub t) while the late phase is controlled by I(sub Kr). I(sub t) is a large transient K+ current and is not dependent on the presence of Ca2+ and is sensitive to 4-aminopyridine. E-4031 and BaCl2 increase the duration of the action potential in most of the cells but do not affect the resting membrane potential.

We demonstrate a method for fabricating induced two-dimensional hole devices in (311)A GaAs. The method uses a metallic p+-GaAs capping layer as an in situ top gate that pins the Fermi energy close to the valence band, thereby allowing very small gate biases to be used to induce a two-dimensional hole system at a AlGaAs/GaAs interface. We present transport data from devices with different levels of background impurities. Modeling the mobility as a function of hole density gives a quantitative measure of the level of disorder and indicates that these systems can be used for a systematic study of the effects of disorder in strongly interacting low-dimensional systems. [ABSTRACT FROM AUTHOR]

Quantum spin Hall insulators (QSHIs), also known as two-dimensional topological insulators, have emerged as an unconventional class of quantum states with insulating bulk and conducting edges originating from nontrivial inverted band structures and have been proposed as a platform for exploring spintronics applications and exotic quasiparticles related to the spin-helical edge modes. Despite theoretical proposals for various materials, however, experimental demonstrations of QSHIs have so far been limited to two systems--HgTe/CdTe and InAs/GaSb--both of which are lattice-matched semiconductor heterostructures. Here, we report transport measurements in yet another realization of a band-inverted heterostructure as a QSHI candidate--InAs/InxGa1-xSb with lattice mismatch. We show that the compressive strain in the InxGa1-xSb layer enhances the band overlap and energy gap. Consequently, high bulk resistivity, two orders of magnitude higher than for InAs/GaSb, is obtained deep in the band-inverted regime. The strain also enhances bulk Rashba spin-orbit splitting, leading to an unusual situation where the Fermi level crosses only one spin branch for electronlike and holelike bands over a wide density range. These properties make this system a promising platform for robust QSHIs with unique spin properties and demonstrate the strain to be an important ingredient for tuning spin-orbit interaction. [ABSTRACT FROM AUTHOR]

When the motion of electrons is restricted to a plane under a perpendicular magnetic field, a variety of quantum phases emerge at low temperatures, the properties of which are dictated by the Coulomb interaction and its interplay with disorder. At very strong magnetic field, the sequence of fractional quantum Hall liquid phases terminates in an insulating phase, which is widely believed to be due to the solidification of electrons into domains possessing Wigner crystal order. The existence of such Wigner crystal domains is signalled by the emergence of microwave pinning-mode resonances, which reflect the mechanical properties characteristic of a solid. However, the most direct manifestation of the broken translational symmetry accompanying the solidification-the spatial modulation of particles' probability amplitudes-has not been observed yet. Here, we demonstrate that nuclear magnetic resonance provides a direct probe of the density topography of electron solids in the integer and fractional quantum Hall regimes. The data uncover quantum and thermal fluctuations of lattice electrons resolved on the nanometre scale. Our results pave the way to studies of other exotic phases with non-trivial spatial spin/charge order. [ABSTRACT FROM AUTHOR]

The model of interacting fermion systems in one dimension known as a Tomonaga-Luttinger liquid (TLL) provides a simple and exactly solvable theoretical framework that predicts various intriguing physical properties. Evidence of a TLL has been observed as power-law behaviour in electronic transport on various types of one-dimensional conductor. However, these measurements, which rely on d.c. transport involving electron tunneling processes, cannot identify the long-awaited hallmark of charge fractionalization, in which an injection of elementary charge e from a non-interacting lead is divided into the non-trivial effective charge e* and the remainder, e−e* (refs 6, 7, 8). Here, we report time-resolved transport measurements on an artificial TLL composed of coupled integer quantum Hall edge channels, in which we successfully identify single charge fractionalization processes. A wave packet of charge q incident from a non-interacting region breaks up into several fractionalized charge wave packets at the edges of the artificial TLL, from which transport eigenmodes can be evaluated directly. These results are informative for elucidating the nature of TLLs and low-energy excitations in the edge channels. [ABSTRACT FROM AUTHOR]

We report a frequency-conversion technique for edge magnetoplasmons in a quantum Hall device. The nonlinear conductance of a quantum point contact (QPC) results in the generation of high harmonics of an input microwave and the mixing of two input frequencies. We controlled the conversion efficiency by tuning the nonlinear conductance via a gate voltage. The amplitudes of the frequency-converted waves agree well with those expected from the measured dc nonlinear conductance. We demonstrate the technique up to our instrumental limit of 12 GHz and show that formation of charge-density waves does not change the nonlinear characteristics of the QPC. [ABSTRACT FROM AUTHOR]

Understanding how the orbital motion of electrons is coupled to the spin degree of freedom in nanoscale systems is central for applications in spin-based electronics and quantum computation. Here we demonstrate such spin-orbit coupling in a carbon-nanotube quantum dot in the general multielectron regime and in the presence of finite disorder. Also, we find a systematic dependence of the spin-orbit coupling on the electron occupation of the quantum dot. Such a dependence has not been seen in any other system and follows from the curvature-induced spin-orbit-split Dirac spectrum of the underlying graphene lattice. Our findings suggest that the spin-orbit coupling is a general property of carbon-nanotube quantum dots, which should provide a unique platform for the study of spin-orbit effects and their applications. [ABSTRACT FROM AUTHOR]

Background and Purpose: The transient receptor potential melastatin-3 (TRPM3) channel forms calcium-permeable, non-selective, cationic channels that are stimulated by pregnenolone sulphate (PregS). Here, we aimed to define chemical requirements of this acute steroid action and potentially reveal novel stimulators with physiological relevance.Experimental Approach: We used TRPM3 channels over-expressed in HEK 293 cells, with intracellular calcium measurement and whole-cell patch-clamp recording techniques.Key Results: The stimulation of TRPM3 channels was confined to PregS and closely related steroids and not mimicked by other major classes of steroids, including progesterone. Relatively potent stimulation of TRPM3-dependent calcium entry was observed. A sulphate group positioned at ring A was important for strong stimulation but more striking was the requirement for a cis (beta) configuration of the side group, revealing previously unrecognized stereo-selectivity and supporting existence of a specific binding site. A cis-oriented side group on ring A was not the only feature necessary for high activity because loss of the double bond in ring B reduced potency and loss of the acetyl group at ring D reduced efficacy and potency. Weak steroid stimulators of TRPM3 channels inhibited effects of PregS, suggesting partial agonism. In silico screening of chemical libraries for non-steroid modulators of TRPM3 channels revealed the importance of the steroid backbone for stimulatory effects.Conclusions and Implications: Our data defined some of the chemical requirements for acute stimulation of TRPM3 channels by steroids, supporting the existence of a specific and unique steroid binding site. Epipregnanolone sulphate was identified as a novel TRPM3 channel stimulator. [ABSTRACT FROM AUTHOR]

Abstract: Using molecular beam epitaxy, we study self-assembled InAs quantum dots (QDs) grown on GaAs (001) substrates by lowtemperature scanning tunneling microscopy. We compare two different growth processes, the well-known Stranski-Krastanow mode and the more recently studied droplet epitaxy mode. We show that, for the same amount of deposited indium, the shape of the dots shows similar anisotropic tendency, but the InAs coverage dependence of the density shows that the growth mechanisms are different at the initial stage of the QD formation. By scanning tunneling spectroscopy at low temperature, we succeed in mapping the local density of states (LDOS) of a single quantum dot grown by the droplet epitaxy. Maps of LDOS are consistent with those previously reported for the Stranski–Krastanow mode; however, energy spectrum of our QDs shows different peak structures. [Copyright &y& Elsevier]

Two-dimensional (2D) electronic systems can exhibit dramatic drops in resistivity, ρxx, as the temperature T→0, which has renewed debate as to whether 2D systems may have a metallic ground state. The metallic behaviour is only observed in low-disorder systems, where interactions between the carriers are strong. However, the strength of the metallic behaviour is not universal, with decreases in resistivity ranging from a few per cent to an order of magnitude as T→0. Here, we compare the metallic behaviour in 2D systems dominated by long- and short-range disorder. We thereby highlight the pivotal role played by the type of disorder in determining the strength of metallic behaviour in these systems. In doing so, we resolve recent confusion in the literature that has arisen from the application of interaction-based theories of metallic behaviour to 2D systems whose disorder environments are inconsistent with the assumptions made by these theories. [ABSTRACT FROM AUTHOR]

We measured an anisotropic magnetotransport that depends on directions of an in-plane field in a bilayer quantum Hall system. We found that the longitudinal resistance near the bilayer v = 1 quantum Hall state strongly varies when we changed an relative angle between the current and the in-plane field. It is a phenomenon peculiar to the bilayer v = 1 quantum Hail state, because this phenomenon does not appear in a monolayer system. [ABSTRACT FROM AUTHOR]

Local spin density functional theory calculations for double quantum dots are compared with experimental data to explain the evolution of addition energy spectra with the interdot distance. Realistic features such as finite thickness and nonidentical constituent dots are included in the calculation. We can thus evaluate the heteronuclear character of the diatomic artificial quantum molecules due to a small unavoidable mismatch introduced in their fabrication. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 [ABSTRACT FROM AUTHOR]

Abstract Technical advancements in molecular genetics have shown various mitochondrial DNA (mtDNA) abnormalities in patients with mitochondrial myopathies. Recently, it has been revealed that, in these patients, the nuclear DNA carries sequences similar to those of the mtDNA (nuclear pseudogene) and it has several point mutations previously reported to be pathogenic. We verified the existence of the T3250C and T3291C mutations, which we have found in patients with mitochondrial myopathy, I [ABSTRACT FROM AUTHOR]