746 research outputs found
The Book of Ezekiel
The book of the prophet Ezekiel : critical edition of the Hebrew text / with notes by C.H. Toy.https://scholar.csl.edu/ebooks/1008/thumbnail.jp
Polystyrene-supported triphenylarsines: Useful ligands in palladium-catalyzed aryl halide homocoupling reactions and a catalyst for alkene epoxidation using hydrogen peroxide
The utility of both soluble (non-cross-linked) and insoluble (cross-linked) polystyrene-supported triphenylarsine reagents were examined. These reagents were prepared by standard radical polymerization methodology and used in palladium-catalyzed homocoupling reactions of aryl halides. The insoluble reagent was also used as a catalyst precursor in heterogeneous alkene epoxidation reactions in which aqueous hydrogen peroxide was the stoichiometric oxidant. For the aryl halide homocoupling reactions, both reagents worked well and afforded similar results. Unhindered aryl iodides afforded the best yields in the shortest reaction times compared to aryl bromides. The epoxidation reactions of unfunctionalized alkenes were not very efficient. This was probably due to the hydrophobicity of the polystyrene matrix, which did not swell in the reaction medium. Thus, since a microporous, gel-type polystyrene matrix was used, the majority of the arsine groups were inaccessible to the reaction components and therefore incapable of participating in catalysis. © 2005 Elsevier Ltd. All rights reserved.postprin
First direct observation of Dirac fermions in graphite
Originating from relativistic quantum field theory, Dirac fermions have been
recently applied to study various peculiar phenomena in condensed matter
physics, including the novel quantum Hall effect in graphene, magnetic field
driven metal-insulator-like transition in graphite, superfluid in 3He, and the
exotic pseudogap phase of high temperature superconductors. Although Dirac
fermions are proposed to play a key role in these systems, so far direct
experimental evidence of Dirac fermions has been limited. Here we report the
first direct observation of massless Dirac fermions with linear dispersion near
the Brillouin zone (BZ) corner H in graphite, coexisting with quasiparticles
with parabolic dispersion near another BZ corner K. In addition, we report a
large electron pocket which we attribute to defect-induced localized states.
Thus, graphite presents a novel system where massless Dirac fermions,
quasiparticles with finite effective mass, and defect states all contribute to
the low energy electronic dynamics.Comment: Nature Physics, in pres
Quantum magneto-optics of graphite family
The optical conductivity of graphene, bilayer graphene, and graphite in
quantizing magnetic fields is studied. Both dynamical conductivities,
longitudinal and Hall's, are analytically evaluated. The conductivity peaks are
explained in terms of electron transitions. We have shown that trigonal warping
can be considered within the perturbation theory for strong magnetic fields
larger than 1 T and in the semiclassical approach for weak fields when the
Fermi energy is much larger than the cyclotron frequency. The main optical
transitions obey the selection rule with \Deltan = 1 for the Landau number n,
however the \Deltan = 2 transitions due to the trigonal warping are also
possible. The Faraday/Kerr rotation and light transmission/reflection in the
quantizing magnetic fields are calculated. Parameters of the
Slonczewski-Weiss-McClure model are used in the fit taking into account the
previous dHvA measurements and correcting some of them for the case of strong
magnetic fields.Comment: 28 pages, 12 figures. arXiv admin note: text overlap with
arXiv:1106.340
Inclusive Dielectron Cross Sections in p+p and p+d Interactions at Beam Energies from 1.04 to 4.88 GeV
Measurements of dielectron production in p+p and p+d collisions with beam
kinetic energies from 1.04 to 4.88 GeV are presented. The differential cross
section is presented as a function of invariant pair mass, transverse momentum,
and rapidity. The shapes of the mass spectra and their evolution with beam
energy provide information about the relative importance of the various
dielectron production mechanisms in this energy regime. The p+d to p+p ratio of
the dielectron yield is also presented as a function of invariant pair mass,
transverse momentum, and rapidity. The shapes of the transverse momentum and
rapidity spectra from the p+d and p+p systems are found to be similar to one
another for each of the beam energies studied. The beam energy dependence of
the integrated cross sections is also presented.Comment: 15 pages and 16 figure
Many private mutations originate from the first few divisions of a human colorectal adenoma.
Intratumoural mutational heterogeneity (ITH) or the presence of different private mutations in different parts of the same tumour is commonly observed in human tumours. The mechanisms generating such ITH are uncertain. Here we find that ITH can be remarkably well structured by measuring point mutations, chromosome copy numbers, and DNA passenger methylation from opposite sides and individual glands of a 6 cm human colorectal adenoma. ITH was present between tumour sides and individual glands, but the private mutations were side-specific and subdivided the adenoma into two major subclones. Furthermore, ITH disappeared within individual glands because the glands were clonal populations composed of cells with identical mutant genotypes. Despite mutation clonality, the glands were relatively old, diverse populations when their individual cells were compared for passenger methylation and by FISH. These observations can be organized into an expanding star-like ancestral tree with co-clonal expansion, where many private mutations and multiple related clones arise during the first few divisions. As a consequence, most detectable mutational ITH in the final tumour originates from the first few divisions. Much of the early history of a tumour, especially the first few divisions, may be embedded within the detectable ITH of tumour genomes
Tamoxifen for prevention of breast cancer: extended long-term follow-up of the IBIS-I breast cancer prevention trial
© Cuzick et al. Open Access article distributed under the terms of CC BY.http://dx.doi.org/10.1016/S1470-2045(14)71171-
Investigation of low 5-year relative survival for breast cancer in a London cancer network
BACKGROUND: Breast cancer 5-year relative survival is low in the North East London Cancer Network (NELCN). METHODS: We compared breast cancer that was diagnosed during 2001-2005 with that in the rest of London. RESULTS: North East London Cancer Network women more often lived in socioeconomic quintile 5 (42 vs 21%) and presented with advanced disease (11 vs 7%). Cox regression analysis showed the survival difference (hazard ratio: 1.27, 95% confidence interval (CI): 1.15-1.41) reduced to 1.00 (95% CI: 0.89-1.11) after adjustment for age, stage, socioeconomic deprivation, ethnicity and treatment. Major drivers were stage and deprivation. Excess mortality was in the first year. CONCLUSION: Late diagnosis occurs in NELCN
Experimental Study of the Shortest Reset Word of Random Automata
In this paper we describe an approach to finding the shortest reset word of a
finite synchronizing automaton by using a SAT solver. We use this approach to
perform an experimental study of the length of the shortest reset word of a
finite synchronizing automaton. The largest automata we considered had 100
states. The results of the experiments allow us to formulate a hypothesis that
the length of the shortest reset word of a random finite automaton with
states and 2 input letters with high probability is sublinear with respect to
and can be estimated as $1.95 n^{0.55}.
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