555 research outputs found
Neutrino mixing in matter
Three-neutrino mixing in matter is studied through a set of evolution
equations which are based on a rephasing invariant parametrization. Making use
of the known properties of measured neutrino parameters, analytic, approximate,
solutions are obtained. Their accuracy is confirmed by comparison with
numerical integration of these equations. The results, when expressed in the
elements squared of the mixing matrix, exhibit striking patterns as the matter
density varies.Comment: Revised, 5 pages, 3 figures, references added
Capturing a c2 daisy chain using the threading-followed-by-swelling approach
We have used the "threading-followed-by-swelling'' approach to fix a daisy chain structure in solution, leading to the isolation of a captured [c2] daisy chain in 77% yield
Using a Threading-Followed-by-Swelling Approach to Synthesize 2 Rotaxanes
We have developed a "threading-followed-by-swelling" protocol to synthesize [2]rotaxanes efficiently and atom economically. Our protocol employs cis-1-[(Z)-alk-1'enyl]-2-vinylcyclopropane units as the termini of the threadlike components; these end groups are converted into more-sizable cycloheptadiene motifs, which function as stopper units, through Cope rearrangements at elevated temperature. We used this approach to synthesize [2]rotaxanes in good yield from [2]pseudorotaxanes featuring either one or two swellable termini to interlock three different types of macrocycle. The chiral centers created by the swelling process were "erased" by hydrogenating the cycloheptadiene termini into the corresponding cycloheptane units, affording achiral molecular [2]rotaxanes as the only final products
Weakly Associated TFPB Anions Are Superior to PF6 Anions When Preparing (Pseudo)Rotaxanes from Crown Ethers and Secondary Dialkylammonium Ions
A 2 rotaxane-based H-1 NMR spectroscopic probe for the simultaneous identification of physiologically important metal ions in solution
We describe a [ 2] rotaxane molecule that exhibits distinct signals in its H-1 NMR spectra upon the complexation of physiologically important Li+, Na+, Mg2+ and Ca2+ ions; thus, the identification of these metal ions in solution is possible from the analysis of a single H-1 NMR spectrum of a single molecular sensor
Hamiltonian Description of Composite Fermions: Magnetoexciton Dispersions
A microscopic Hamiltonian theory of the FQHE, developed by Shankar and myself
based on the fermionic Chern-Simons approach, has recently been quite
successful in calculating gaps in Fractional Quantum Hall states, and in
predicting approximate scaling relations between the gaps of different
fractions. I now apply this formalism towards computing magnetoexciton
dispersions (including spin-flip dispersions) in the , 2/5, and 3/7
gapped fractions, and find approximate agreement with numerical results. I also
analyse the evolution of these dispersions with increasing sample thickness,
modelled by a potential soft at high momenta. New results are obtained for
instabilities as a function of thickness for 2/5 and 3/7, and it is shown that
the spin-polarized 2/5 state, in contrast to the spin-polarized 1/3 state,
cannot be described as a simple quantum ferromagnet.Comment: 18 pages, 18 encapsulated ps figure
Hamiltonian Theory of the FQHE: Conserving Approximation for Incompressible Fractions
A microscopic Hamiltonian theory of the FQHE developed by Shankar and the
present author based on the fermionic Chern-Simons approach has recently been
quite successful in calculating gaps and finite tempertature properties in
Fractional Quantum Hall states. Initially proposed as a small- theory, it
was subsequently extended by Shankar to form an algebraically consistent theory
for all in the lowest Landau level. Such a theory is amenable to a
conserving approximation in which the constraints have vanishing correlators
and decouple from physical response functions. Properties of the incompressible
fractions are explored in this conserving approximation, including the
magnetoexciton dispersions and the evolution of the small- structure factor
as \nu\to\half. Finally, a formalism capable of dealing with a nonuniform
ground state charge density is developed and used to show how the correct
fractional value of the quasiparticle charge emerges from the theory.Comment: 15 pages, 2 eps figure
Serotonin accumulation in transgenic rice by over-expressing tryptophan decarboxlyase results in a dark brown phenotype and stunted growth
A mutant M47286 with a stunted growth, low fertility and dark-brown phenotype was identified from a T-DNA-tagged rice mutant library. This mutant contained a copy of the T-DNA tag inserted at the location where the expression of two putative tryptophan decarboxlyase genes, TDC-1 and TDC-3, were activated. Enzymatic assays of both recombinant proteins showed tryptophan decarboxlyase activities that converted tryptophan to tryptamine, which could be converted to serotonin by a constitutively expressed tryptamine 5' hydroxylase (T5H) in rice plants. Over-expression of TDC-1 and TDC-3 in transgenic rice recapitulated the stunted growth, dark-brown phenotype and resulted in a low fertility similar to M47286. The degree of stunted growth and dark-brown color was proportional to the expression levels of TDC-1 and TDC-3. The levels of tryptamine and serotonin accumulation in these transgenic rice lines were also directly correlated with the expression levels of TDC-1 and TDC-3. A mass spectrometry assay demonstrated that the dark-brown leaves and hulls in the TDC-overexpressing transgenic rice were caused by the accumulation of serotonin dimer and that the stunted growth and low fertility were also caused by the accumulation of serotonin and serotonin dimer, but not tryptamine. These results represent the first evidence that over-expression of TDC results in stunted growth, low fertility and the accumulation of serotonin, which when converted to serotonin dimer, leads to a dark brown plant color
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Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV
The momentum distribution of electrons from semi-leptonic decays of charm and
bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is
measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC)
over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of
electrons from bottom to that from charm is presented. The ratio is determined
using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It
is found that the yield of electrons from bottom becomes significant above 4
GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative
quantum chromodynamics (pQCD) calculation agrees with the data within the
theoretical and experimental uncertainties. The extracted total bottom
production cross section at this energy is \sigma_{b\b^bar}= 3.2
^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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