7,122 research outputs found
An application of the multivariate extended Poisson distribution in 2 times 2 contingency tables Final report
Application of multivariate extended Poisson distribution
Validation Methods Research for Fault-Tolerant Avionics and Control Systems Sub-Working Group Meeting. CARE 3 peer review
A computer aided reliability estimation procedure (CARE 3), developed to model the behavior of ultrareliable systems required by flight-critical avionics and control systems, is evaluated. The mathematical models, numerical method, and fault-tolerant architecture modeling requirements are examined, and the testing and characterization procedures are discussed. Recommendations aimed at enhancing CARE 3 are presented; in particular, the need for a better exposition of the method and the user interface is emphasized
Facile preparation of agarose-chitosan hybrid materials and nanocomposite ionogels using an ionic liquid via dissolution, regeneration and sol-gel transition
We report simultaneous dissolution of agarose (AG) and chitosan (CH) in
varying proportions in an ionic liquid (IL), 1-butyl-3-methylimidazolium
chloride [C4mim][Cl]. Composite materials were constructed from AG-CH-IL
solutions using the antisolvent methanol, and IL was recovered from the
solutions. Composite materials could be uniformly decorated with silver oxide
(Ag2O) nanoparticles (Ag NPs) to form nanocomposites in a single step by in
situ synthesis of Ag NPs in AG-CH-IL sols, wherein the biopolymer moiety acted
as both reducing and stabilizing agent. Cooling of Ag NPs-AG-CH-IL sols to room
temperature resulted in high conductivity and high mechanical strength
nanocomposite ionogels. The structure, stability and physiochemical properties
of composite materials and nanocomposites were characterized by several
analytical techniques, such as Fourier transform infrared (FTIR), CD
spectroscopy, differential scanning colorimetric (DSC), thermogravimetric
analysis (TGA), gel permeation chromatography (GPC), and scanning electron
micrography (SEM). The result shows that composite materials have good thermal
and conformational stability, compatibility and strong hydrogen bonding
interactions between AG-CH complexes. Decoration of Ag NPs in composites and
ionogels was confirmed by UV-Vis spectroscopy, SEM, TEM, EDAX and XRD. The
mechanical and conducting properties of composite ionogels have been
characterized by rheology and current-voltage measurements. Since Ag NPs show
good antimicrobial activity, Ag NPs -AG-CH composite materials have the
potential to be used in biotechnology and biomedical applications whereas
nanocomposite ionogels will be suitable as precursors for applications such as
quasi-solid dye sensitized solar cells, actuators, sensors or electrochromic
displays
High Tc Superconductors -- A Variational Theory of the Superconducting State
We use a variational approach to gain insight into the strongly correlated
d-wave superconducting state of the high Tc cuprates at T=0. We show that
strong correlations lead to qualitatively different trends in pairing and phase
coherence: the pairing scale decreases monotonically with hole doping while the
SC order parameter shows a non-monotonic dome. We obtain detailed results for
the doping-dependence of a large number of experimentally observable
quantities, including the chemical potential, coherence length, momentum
distribution, nodal quasiparticle weight and dispersion, incoherent features in
photoemission spectra, optical spectral weight and superfluid density. Most of
our results are in remarkable quantitative agreement with existing data and
some of our predictions, first reported in Phys. Rev. Lett. {\bf 87}, 217002
(2001), have been recently verified.Comment: (Minor revisions, 1 figure added, version to appear in PRB) 23 RevTeX
pages, 11 eps figs, long version of cond-mat/0101121, contains detailed
comparisons with experiments, analytical insights, technical aspects of the
calculation, and comparison with slave boson MF
The Nefarious Nexus of Noncoding RNAs in Cancer
The past decade has witnessed enormous progress, which has seen the noncoding RNAs (ncRNAs) turn from the so called dark matter RNA to critical functional molecules, influencing most physiological processes in development and disease contexts. Many ncRNAs interact with each other and are part of networks that influence the cell transcriptome and proteome and consequently the outcome of biological processes. The regulatory circuits controlled by ncRNAs have become increasingly more relevant in cancer. Further understanding of these complex network interactions and how ncRNAs are regulated, is paving the way for the identification of better therapeutic strategies in cancer
Validation Methods Research for Fault-Tolerant Avionics and Control Systems: Working Group Meeting, 2
The validation process comprises the activities required to insure the agreement of system realization with system specification. A preliminary validation methodology for fault tolerant systems documented. A general framework for a validation methodology is presented along with a set of specific tasks intended for the validation of two specimen system, SIFT and FTMP. Two major areas of research are identified. First, are those activities required to support the ongoing development of the validation process itself, and second, are those activities required to support the design, development, and understanding of fault tolerant systems
Competition between antiferromagnetism and superconductivity, electron-hole doping asymmetry and "Fermi Surface" topology in cuprates
We investigate the asymmetry between electron and hole doping in a 2D Mott
insulator, and the resulting competition between antiferromagnetism (AF) and
d-wave superconductivity (SC), using variational Monte Carlo for projected wave
functions. We find that key features of the T = 0 phase diagram, such as
critical doping for SC-AF coexistence and the maximum value of the SC order
parameter, are determined by a single parameter which characterises the
topology of the "Fermi surface" at half filling defined by the bare
tight-binding parameters. Our results give insight into why AF wins for
electron doping, while SC is dominant on the hole doped side. We also suggest
using band structure engineering to control the parameter for enhancing SC.Comment: 4 pages, 4 figure
Strong-coupling expansion for the momentum distribution of the Bose Hubbard model with benchmarking against exact numerical results
A strong-coupling expansion for the Green's functions, self-energies and
correlation functions of the Bose Hubbard model is developed. We illustrate the
general formalism, which includes all possible inhomogeneous effects in the
formalism, such as disorder, or a trap potential, as well as effects of thermal
excitations. The expansion is then employed to calculate the momentum
distribution of the bosons in the Mott phase for an infinite homogeneous
periodic system at zero temperature through third-order in the hopping. By
using scaling theory for the critical behavior at zero momentum and at the
critical value of the hopping for the Mott insulator to superfluid transition
along with a generalization of the RPA-like form for the momentum distribution,
we are able to extrapolate the series to infinite order and produce very
accurate quantitative results for the momentum distribution in a simple
functional form for one, two, and three dimensions; the accuracy is better in
higher dimensions and is on the order of a few percent relative error
everywhere except close to the critical value of the hopping divided by the
on-site repulsion. In addition, we find simple phenomenological expressions for
the Mott phase lobes in two and three dimensions which are much more accurate
than the truncated strong-coupling expansions and any other analytic
approximation we are aware of. The strong-coupling expansions and scaling
theory results are benchmarked against numerically exact QMC simulations in two
and three dimensions and against DMRG calculations in one dimension. These
analytic expressions will be useful for quick comparison of experimental
results to theory and in many cases can bypass the need for expensive numerical
simulations.Comment: 48 pages 14 figures RevTe
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