Reliability and Hardware Implementation of Rank Modulation Flash Memory

We review a novel data representation scheme for NAND flash memory named rank modulation (RM), and discuss its hardware implementation. We show that under the normal threshold voltage (Vth) variations, RM has intrinsic read reliability advantage over conventional multiple-level cells. Test results demonstrating superior reliability using commercial flash chips are reviewed and discussed. We then present a read method based on relative sensing time, which can obtain the rank of all cells in the group in one read cycle. The improvement in reliability and read speed enable similar program-and-verify time in RM as that of conventional MLC flash

Generalized polar transforms of spacelike isothermic surfaces

In this paper, we generalize the polar transforms of spacelike isothermic surfaces in $Q^4_1$ to n-dimensional pseudo-Riemannian space forms $Q^n_r$. We show that there exist $c-$polar spacelike isothermic surfaces derived from a spacelike isothermic surface in $Q^n_r$, which are into $S^{n+1}_r(c)$, $H^{n+1}_{r-1}(c)$ or $Q^n_r$ depending on $c>0,<0,$ or $=0$. The $c-$polar isothermic surfaces can be characterized as generalized $H-$surfaces with null minimal sections. We also prove that if both the original surface and its $c-$polar surface are closed immersion, then they have the same Willmore functional. As examples, we discuss some product surfaces and compute the $c-$polar transforms of them. In the end, we derive the permutability theorems for $c-$polar transforms and Darboux transform and spectral transform of isothermic surfaces.Comment: 12 pages, to appear in J. Geom. Ph

Reliability and Hardware Implementation of Rank Modulation Flash Memory

We review a novel data representation scheme for NAND flash memory named rank modulation (RM), and discuss its hardware implementation. We show that under the normal threshold voltage (Vth) variations, RM has intrinsic read reliability advantage over conventional multiple-level cells. Test results demonstrating superior reliability using commercial flash chips are reviewed and discussed. We then present a read method based on relative sensing time, which can obtain the rank of all cells in the group in one read cycle. The improvement in reliability and read speed enable similar program-and-verify time in RM as that of conventional MLC flash

(1+3) Covariant Dynamics of Scalar Perturbations in Braneworlds

We discuss the dynamics of linear, scalar perturbations in an almost Friedmann-Robertson-Walker braneworld cosmology of Randall-Sundrum type II using the 1+3 covariant approach. We derive a complete set of frame-independent equations for the total matter variables, and a partial set of equations for the non-local variables which arise from the projection of the Weyl tensor in the bulk. The latter equations are incomplete since there is no propagation equation for the non-local anisotropic stress. We supplement the equations for the total matter variables with equations for the independent constituents in a cold dark matter cosmology, and provide solutions in the high and low-energy radiation-dominated phase under the assumption that the non-local anisotropic stress vanishes. These solutions reveal the existence of new modes arising from the two additional non-local degrees of freedom. Our solutions should prove useful in setting up initial conditions for numerical codes aimed at exploring the effect of braneworld corrections on the cosmic microwave background (CMB) power spectrum. As a first step in this direction, we derive the covariant form of the line of sight solution for the CMB temperature anisotropies in braneworld cosmologies, and discuss possible mechanisms by which braneworld effects may remain in the low-energy universe.Comment: 22 pages replaced with additional references and minor corrections in Revtex4, and accepted for publication in Phys. Rev.

Conductive composites for oligonucleotide detection

© 2017 The Authors A new method for oligonucleotide detection is presented based on oligonucleotide cross-linked polymer composites. Conductive carbon nanoparticles are incorporated into a DNA-functionalised polymer, containing partially complementary oligonucleotide cross-linkers, which is polymerised in situ upon interdigitated electrodes. In the presence of an aqueous solution of a specific analyte oligonucleotide sequence, the cross-linkers are cleaved, leading to increased swelling. As the polymer swells the relative density of the conductive particles decreases, leading to an easily measurable decrease in electrical conductivity. We demonstrate that such are capable of discriminating between analyte and control solutions, with single-base specificity, in under 3 min. The lower detection limit of these composites is of the order of 10 nM. The swelling characteristics of these composites is confirmed by optical imaging and the effects of varying temperature upon such composites are also reported

Cosmological Perturbations in Brane-World Theories: Formalism

We develop a gauge-invariant formalism to describe metric perturbations in five-dimensional brane-world theories. In particular, this formalism applies to models originating from heterotic M-theory. We introduce a generalized longitudinal gauge for scalar perturbations. As an application, we discuss some aspects of the evolution of fluctuations on the brane. Moreover, we show how the five-dimensional formalism can be matched to the known four-dimensional one in the limit where an effective four-dimensional description is appropriate.Comment: 16 pages, no figure, matches version to appear in PR

Small Scale Structure Formation in Chameleon Cosmology

Chameleon fields are scalar fields whose mass depends on the ambient matter density. We investigate the effects of these fields on the growth of density perturbations on sub-galactic scales and the formation of the first dark matter halos. Density perturbations on comoving scales $R < 1 {\rm pc}$ go non--linear and collapse to form structure much earlier than in standard $\Lambda$CDM cosmology. The resulting mini-halos are hence more dense and resilient to disruption. We therefore expect (provided that the density perturbations on these scales have not been erased by damping processes) that the dark matter distribution on small scales would be more clumpy in chameleon cosmology than in the $\Lambda$CDM model.Comment: 13 pages, 4 figure