33,402 research outputs found
Evaluation of the utility of interphase cytogenetics to detect residual cells with a malignant genotype in mixed cell populations: a Burkitt lymphoma model
Nucleon-Nucleon Scattering in a Harmonic Potential
The discrete energy-eigenvalues of two nucleons interacting with a
finite-range nuclear force and confined to a harmonic potential are used to
numerically reconstruct the free-space scattering phase shifts. The extracted
phase shifts are compared to those obtained from the exact continuum scattering
solution and agree within the uncertainties of the calculations. Our results
suggest that it might be possible to determine the amplitudes for the
scattering of complex systems, such as n-d, n-t or n-alpha, from the
energy-eigenvalues confined to finite volumes using ab-initio bound-state
techniques.Comment: 19 pages, 13 figure
Rapid assembly of highly-functionalised difluorinated cyclooctenones via ring-closing metathesis
Building block methodology from trifluoroethanol and ringclosing metathesis using a Fürstner modification of Grubbs’ conditions allows the rapid synthesis of novel difluorinated cyclooctenones
Confidence Cycles
We provide a model that rationalizes variations in confidence of rational agents, both in the time-series and the cross-section. Combining horizon-dependent risk aversion (“anxiety”) and selective memory, we show that over- and underconfidence can arise in the Bayesian equilibrium of an intra-personal game. In
the time-series, overconfidence is more prevalent when actual risk levels are high, while underconfidence occurs when risks are low. In the cross-section, more anxious agents are more prone to biased confidence and their beliefs fluctuate more, leading them to buy in booms and sell in crashes. Lastly, fluctuations in confidence can amplify boom-bust cycles
Horizon-Dependent Risk Aversion and the Timing and Pricing of Uncertainty
We address two fundamental critiques of established asset pricing models: that they (1) require a controversial degree of preference for early resolution of uncertainty; and (2) do not match the
term structures of risk premia observed in the data. Inspired by experimental evidence, we construct preferences in which risk aversion decreases with the temporal horizon. The resulting
model implies term structures of risk premia consistent with the evidence, including timevariations and reversals in the slope, without imposing a particular preference for early or late
resolutions of uncertainty or compromising on the ability to match standard moments in the returns distributions
Lens or Binary? Chandra Observations of the Wide Separation Broad Absorption Line Quasar Pair UM425
We have obtained a 110 ksec Chandra ACIS-S exposure of UM425, a pair of QSOs
at z=1.47 separated by 6.5 arcsec, which show remarkably similar emission and
broad absorption line (BAL) profiles in the optical/UV. Our 5000 count X-ray
spectrum of UM425A (the brighter component) is well-fit with a power law
(photon spectral index Gamma=2.0) partially covered by a hydrogen column of
3.8x10^22 cm^-2. The underlying power-law slope for this object and for other
recent samples of BALQSOs is typical of radio-quiet quasars, lending credence
to the hypothesis that BALs exist in every quasar. Assuming the same Gamma for
the much fainter image of UM425B, we detect an obscuring column 5 times larger.
We search for evidence of an appropriately large lensing mass in our Chandra
image and find weak diffuse emission near the quasar pair, with an X-ray flux
typical of a group of galaxies at redshift z ~ 0.6. From our analysis of
archival HST WFPC2 and NICMOS images, we find no evidence for a luminous
lensing galaxy, but note a 3-sigma excess of galaxies in the UM425 field with
plausible magnitudes for a z=0.6 galaxy group. However, the associated X-ray
emission does not imply sufficient mass to produce the observed image
splitting. The lens scenario thus requires a dark (high M/L ratio) lens, or a
fortuitous configuration of masses along the line of sight. UM425 may instead
be a close binary pair of BALQSOs, which would boost arguments that
interactions and mergers increase nuclear activity and outflows.Comment: 13 pages, 9 figures, Accepted for publication in the Astrophysical
Journa
A Sustained Dietary Change Increases Epigenetic Variation in Isogenic Mice
Epigenetic changes can be induced by adverse environmental exposures, such as nutritional imbalance, but little is known about the nature or extent of these changes. Here we have explored the epigenomic effects of a sustained nutritional change, excess dietary methyl donors, by assessing genomic CpG methylation patterns in isogenic mice exposed for one or six generations. We find stochastic variation in methylation levels at many loci; exposure to methyl donors increases the magnitude of this variation and the number of variable loci. Several gene ontology categories are significantly overrepresented in genes proximal to these methylation-variable loci, suggesting that certain pathways are susceptible to environmental influence on their epigenetic states. Long-term exposure to the diet (six generations) results in a larger number of loci exhibiting epigenetic variability, suggesting that some of the induced changes are heritable. This finding presents the possibility that epigenetic variation within populations can be induced by environmental change, providing a vehicle for disease predisposition and possibly a substrate for natural selection.This work was supported by the Australian Research Council (DP0771859) and the National Health and Medical Research Council (#459412, #635510)
Experimental Vapor Pressures of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and Hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX)
In this work experimental vapor pressures of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) were measured with transpiration method. Corresponding enthalpies of sublimation were determined to be (130.9 +/- 2.1) kJ mol(-1)and (108.1 +/- 1.6) kJ mol(-1), respectively. Along with the experimental data fitting equations are reported andp-Tdata extrapolated to 298.15 K to be 0.71 mu Pa for RDX and 823 mu Pa for TNX
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