4,856 research outputs found
Cauchy horizon singularity without mass inflation
A perturbed Reissner-Nordstr\"om-de Sitter solution is used to emphasize the
nature of the singularity along the Cauchy horizon of a charged spherically
symmetric black hole. For these solutions, conditions may prevail under which
the mass function is bounded and yet the curvature scalar
diverges.Comment: typeset in RevTex, 13 page
Nuclear Magnetic Resonance and Hyperfine Structure
Contains research objectives and reports on two research projects
Quantum Computation with Quantum Dots
We propose a new implementation of a universal set of one- and two-qubit
gates for quantum computation using the spin states of coupled single-electron
quantum dots. Desired operations are effected by the gating of the tunneling
barrier between neighboring dots. Several measures of the gate quality are
computed within a newly derived spin master equation incorporating decoherence
caused by a prototypical magnetic environment. Dot-array experiments which
would provide an initial demonstration of the desired non-equilibrium spin
dynamics are proposed.Comment: 12 pages, Latex, 2 ps figures. v2: 20 pages (very minor corrections,
substantial expansion), submitted to Phys. Rev.
Correlated charge polarization in a chain of coupled quantum dots
Coherent charge transfer in a linear array of tunnel-coupled quantum dots,
electrostatically coupled to external gates, is investigated using the Bethe
ansatz for a symmetrically biased Hubbard chain. Charge polarization in this
correlated system is shown to proceed via two distinct processes: formation of
bound states in the metallic phase, and charge transfer processes corresponding
to a superposition of antibound states at opposite ends of the chain in the
Mott-insulating phase. The polarizability in the insulating phase of the chain
exhibits a universal scaling behavior, while the polarization charge in the
metallic phase of the model is shown to be quantized in units of .Comment: 9 pages, 3 figures, 1 tabl
Nuclear Magnetic Resonance and Hyeprfine Structure
Contains research objectives and reports on four research projects
Association of single nucleotide polymorphisms in Pre-miR-27a, Pre-miR-196a2, Pre-miR-423, miR-608 and Pre-miR-618 with breast cancer susceptibility in a South American population
Indexación: Web of ScienceBackground
MicroRNAs (miRNAs) are a novel class of endogenous, non-coding, single-stranded RNAs capable of regulating gene expression by suppressing translation or degrading mRNAs. Single nucleotide polymorphisms (SNP) can alter miRNA expression, resulting in diverse functional consequences. Previous studies have examined the association of miRNA SNPs with breast cancer (BC) susceptibility. The contribution of miRNA gene variants to BC susceptibility in South American women had been unexplored. Our study evaluated the association of the SNPs rs895819 in pre-miR27a, rs11614913 in pre-miR-196a2, rs6505162 in pre-miR-423, rs4919510 in miR-608, and rs2682818 in pre-mir-618 with familial BC and early-onset non-familial BC in non-carriers of BRCA1/2 mutations from a South American population.
Results
We evaluated the association of five SNPs with BC risk in 440 cases and 807 controls. Our data do not support an association of rs11614913:C > T and rs4919510:C > G with BC risk. The rs6505162:C > A was significantly associated with increased risk of familial BC in persons with a strong family history of BC (OR = 1.7 [95 % CI 1.0–2.0] p = 0.05). The rs2682818:C > A genotype C/A is associated with an increased BC risk in non-familial early-onset BC. For the rs895819:A > G polymorphism, the genotype G/G is significantly associated with reduced BC risk in families with a moderate history of BC (OR = 0.3 [95 % CI 0.1–0.8] p = 0.01).
Conclusions
The contribution of variant miRNA genes to BC in South American women had been unexplored. Our findings support the following conclusions: a) rs6505162:C > A in pre-miR-423 increases risk of familial BC in families with a strong history of BC; b) the C/A genotype at rs2682818:C > A (pre-miR-618) increases BC risk in non-familial early-onset BC; and c) the G/G genotype at rs895819:A > G (miR-27a) reduces BC risk in families with a moderate history of BC.http://bmcgenet.biomedcentral.com/articles/10.1186/s12863-016-0415-
Magnet Laboratory Research
Contains research objectives and reports on three research projects
Even-odd parity effects in conductance and shot noise of metal-atomic wire-metal(superconducting) junctions
In this paper, we study the conductance and shot noise in transport through a
multi-site system in a two terminal configuration. The dependence of the
transport on the number of atoms in the atomic wire is investigated using a
tight-binding Hamiltonian and the nonequilibrium Green's function method. In
addition to reproducing the even-odd behavior in the transmission probability
at the Fermi energy or the linear response conductance in the normal-atomic
wire-normal metallic(NAN) junctions, we find the following: (i) The shot noise
is larger in the even-numbered atomic wire than in the odd-numbered wire. (ii)
The Andreev conductance displays the same even-odd parity effects in the
normal-atomic wire-superconducting(NAS) junctions. In general, the conductance
is higher in the odd-numbered atomic wire than in the even-numbered wire. When
the number of sites () is odd and the atomic wire is mirror symmetric with
respect to the center of the atomic wire, the conductance does not depend on
the details of the hopping matrices in the atomic wire, but is solely
determined by the coupling strength to the two leads. When is even, the
conductance is sensitive to the values of the hopping matrices.Comment: 12 pages, 9 figure
Spherically symmetric static solution for colliding null dust
The Einstein equations are integrated in the presence of two (incoming and
outgoing) streams of null dust, under the assumptions of spherical symmetry and
staticity. The solution is also written in double null and radiation
coordinates and it is reinterpreted as an anisotropic fluid. Interior matching
with a static fluid and exterior matching with the Vaidya solution along null
hypersurfaces is discussed. The connection with two-dimensional dilaton gravity
is established.Comment: 12 pages, 7 figures, to appear in Phys. Rev.
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