2,326 research outputs found
Projective measurement in nuclear magnetic resonance
It is demonstrated that nuclear magnetic resonance experiments using
pseudopure spin states can give possible outcomes of projective quantum
measurement and probabilities of such outcomes. The physical system is a
cluster of six dipolar-coupled nuclear spins of benzene in a liquid-crystalline
matrix. For this system with the maximum total spin S=3, the results of
measuring are presented for the cases when the state of the system is one
of the eigenstates of .Comment: 9 pages incluing 3 figure
Coding scheme for 3D vertical flash memory
Recently introduced 3D vertical flash memory is expected to be a disruptive
technology since it overcomes scaling challenges of conventional 2D planar
flash memory by stacking up cells in the vertical direction. However, 3D
vertical flash memory suffers from a new problem known as fast detrapping,
which is a rapid charge loss problem. In this paper, we propose a scheme to
compensate the effect of fast detrapping by intentional inter-cell interference
(ICI). In order to properly control the intentional ICI, our scheme relies on a
coding technique that incorporates the side information of fast detrapping
during the encoding stage. This technique is closely connected to the
well-known problem of coding in a memory with defective cells. Numerical
results show that the proposed scheme can effectively address the problem of
fast detrapping.Comment: 7 pages, 9 figures. accepted to ICC 2015. arXiv admin note: text
overlap with arXiv:1410.177
Domain Dynamics in Piezoresponse Force Microscopy: Quantitative Deconvolution and Hysteresis Loop Fine Structure
Domain dynamics in the Piezoresponse Force Spectroscopy (PFS) experiment is
studied using the combination of local hysteresis loop acquisition with
simultaneous domain imaging. The analytical theory for PFS signal from domain
of arbitrary cross-section is developed and used for the analysis of
experimental data on Pb(Zr,Ti)O3 polycrystalline films. The results suggest
formation of oblate domain at early stage of the domain nucleation and growth,
consistent with efficient screening of depolarization field within the
material. The fine structure of the hysteresis loop is shown to be related to
the observed jumps in the domain geometry during domain wall propagation
(nanoscale Barkhausen jumps), indicative of strong domain-defect interactions.Comment: 17 pages, 3 figures, 2 Appendices, to be submmited to Appl. Phys.
Let
A Multi-dimensional Code for Isothermal Magnetohydrodynamic Flows in Astrophysics
We present a multi-dimensional numerical code to solve isothermal
magnetohydrodynamic (IMHD) equations for use in modeling astrophysical flows.
First, we have built a one-dimensional code which is based on an explicit
finite-difference method on an Eulerian grid, called the total variation
diminishing (TVD) scheme. Recipes for building the one-dimensional IMHD code,
including the normalized right and left eigenvectors of the IMHD Jacobian
matrix, are presented. Then, we have extended the one-dimensional code to a
multi-dimensional IMHD code through a Strang-type dimensional splitting. In the
multi-dimensional code, an explicit cleaning step has been included to
eliminate non-zero at every time step. To estimate the
proformance of the code, one- and two-dimensional IMHD shock tube tests, and
the decay test of a two-dimensional Alfv\'{e}n wave have been done. As an
example of astrophysical applications, we have simulated the nonlinear
evolution of the two-dimensional Parker instability under a uniform gravity.Comment: Accepted for publication in ApJ, using aaspp4.sty, 22 text pages with
10 figure
Mutation Testing as a Safety Net for Test Code Refactoring
Refactoring is an activity that improves the internal structure of the code
without altering its external behavior. When performed on the production code,
the tests can be used to verify that the external behavior of the production
code is preserved. However, when the refactoring is performed on test code,
there is no safety net that assures that the external behavior of the test code
is preserved. In this paper, we propose to adopt mutation testing as a means to
verify if the behavior of the test code is preserved after refactoring.
Moreover, we also show how this approach can be used to identify the part of
the test code which is improperly refactored
Gene alterations by peroxisome proliferator-activated receptor gamma agonists in human colorectal cancer cells
The peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear transcription factor that controls the genes involved in metabolism and carcinogenesis. In the present study, we examined the alteration of gene expression in HCT-116 human colorectal cancer cells by PPARgamma agonists: MCC-555 (5 microM), rosiglitazone (5 microM), and 15-deoxy-Delta12,14-prostaglandin J2 (1 microM). The long-oligo microarray data revealed a list of target genes commonly induced (307 genes) and repressed (32 genes) by tested PPARgamma agonists. These genes were analyzed by Onto-Express software and KEGG pathway analysis and revealed that PPARgamma agonists are involved in cell proliferation, focal adhesion, and several signaling pathways. Eight genes were selected to confirm the microarray data by RT-PCR and real-time PCR, from which CSTA, DAP13, TAF12, RIS1, CDKN3 and MAGOH were up-regulated, and KLHL11 and NCOA2 were down-regulated. This study elucidates the commonly induced genes modulated by tested PPARgamma ligands involved in the different signaling pathways and metabolisms, probably mediated in a PPARgamma-dependent manner in colorectal cancer cells and helps to better understand the pleiotropic actions of PPARgamma ligands
Facial structures for various notions of positivity and applications to the theory of entanglement
In this expository note, we explain facial structures for the convex cones
consisting of positive linear maps, completely positive linear maps,
decomposable positive linear maps between matrix algebras, respectively. These
will be applied to study the notions of entangled edge states with positive
partial transposes and optimality of entanglement witnesses.Comment: An expository note. Section 7 and Section 8 have been enlarge
Controlled spontaneous emission
The problem of spontaneous emission is studied by a direct computer
simulation of the dynamics of a combined system: atom + radiation field. The
parameters of the discrete finite model, including up to 20k field oscillators,
have been optimized by a comparison with the exact solution for the case when
the oscillators have equidistant frequencies and equal coupling constants.
Simulation of the effect of multi-pulse sequence of phase kicks and emission by
a pair of atoms shows that both the frequency and the linewidth of the emitted
spectrum could be controlled.Comment: 25 pages including 11 figure
Dirac fermions on a disclinated flexible surface
A self-consisting gauge-theory approach to describe Dirac fermions on
flexible surfaces with a disclination is formulated. The elastic surfaces are
considered as embeddings into R^3 and a disclination is incorporated through a
topologically nontrivial gauge field of the local SO(3) group which generates
the metric with conical singularity. A smoothing of the conical singularity on
flexible surfaces is naturally accounted for by regarding the upper half of
two-sheet hyperboloid as an elasticity-induced embedding. The availability of
the zero-mode solution to the Dirac equation is analyzed.Comment: 6 page
The complete chloroplast genome sequence of Gossypium hirsutum: organization and phylogenetic relationships to other angiosperms
BACKGROUND: Cotton (Gossypium hirsutum) is the most important fiber crop grown in 90 countries. In 2004–2005, US farmers planted 79% of the 5.7-million hectares of nuclear transgenic cotton. Unfortunately, genetically modified cotton has the potential to hybridize with other cultivated and wild relatives, resulting in geographical restrictions to cultivation. However, chloroplast genetic engineering offers the possibility of containment because of maternal inheritance of transgenes. The complete chloroplast genome of cotton provides essential information required for genetic engineering. In addition, the sequence data were used to assess phylogenetic relationships among the major clades of rosids using cotton and 25 other completely sequenced angiosperm chloroplast genomes. RESULTS: The complete cotton chloroplast genome is 160,301 bp in length, with 112 unique genes and 19 duplicated genes within the IR, containing a total of 131 genes. There are four ribosomal RNAs, 30 distinct tRNA genes and 17 intron-containing genes. The gene order in cotton is identical to that of tobacco but lacks rpl22 and infA. There are 30 direct and 24 inverted repeats 30 bp or longer with a sequence identity ≥ 90%. Most of the direct repeats are within intergenic spacer regions, introns and a 72 bp-long direct repeat is within the psaA and psaB genes. Comparison of protein coding sequences with expressed sequence tags (ESTs) revealed nucleotide substitutions resulting in amino acid changes in ndhC, rpl23, rpl20, rps3 and clpP. Phylogenetic analysis of a data set including 61 protein-coding genes using both maximum likelihood and maximum parsimony were performed for 28 taxa, including cotton and five other angiosperm chloroplast genomes that were not included in any previous phylogenies. CONCLUSION: Cotton chloroplast genome lacks rpl22 and infA and contains a number of dispersed direct and inverted repeats. RNA editing resulted in amino acid changes with significant impact on their hydropathy. Phylogenetic analysis provides strong support for the position of cotton in the Malvales in the eurosids II clade sister to Arabidopsis in the Brassicales. Furthermore, there is strong support for the placement of the Myrtales sister to the eurosid I clade, although expanded taxon sampling is needed to further test this relationship
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