8,758 research outputs found
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Petrology and geochemistry of nakhlite MIL 03346: A new Martian meteorite from Antarctica
MIL 03346 is the first nakhlite in the US Antarctic collection. We have performed detailed mineralogical and bulk-geochemical investigations to compare petrogenesis of this Martian meteorite with other nakhlites
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Mineralogy and petrology of a lunar highland breccia meteorite, MIL 07006
Quantifying selection in immune receptor repertoires
The efficient recognition of pathogens by the adaptive immune system relies
on the diversity of receptors displayed at the surface of immune cells. T-cell
receptor diversity results from an initial random DNA editing process, called
VDJ recombination, followed by functional selection of cells according to the
interaction of their surface receptors with self and foreign antigenic
peptides. To quantify the effect of selection on the highly variable elements
of the receptor, we apply a probabilistic maximum likelihood approach to the
analysis of high-throughput sequence data from the -chain of human
T-cell receptors. We quantify selection factors for V and J gene choice, and
for the length and amino-acid composition of the variable region. Our approach
is necessary to disentangle the effects of selection from biases inherent in
the recombination process. Inferred selection factors differ little between
donors, or between naive and memory repertoires. The number of sequences shared
between donors is well-predicted by the model, indicating a purely stochastic
origin of such "public" sequences. We find a significant correlation between
biases induced by VDJ recombination and our inferred selection factors,
together with a reduction of diversity during selection. Both effects suggest
that natural selection acting on the recombination process has anticipated the
selection pressures experienced during somatic evolution
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The Apollo Virtual Microscope Collection: Lunar Mineralogy and Petrology of Apollo 11, 12, 14, 15 and 16 Rocks
We report on the new Virtual Microscopes on Apollo 16 lunar samples in our Apollo Virtual Microscope collection
Effect of Muons on the Phase Transition in Magnetised Proto-Neutron Star Matter
We study the effect of inclusion of muons and the muon neutrinos on the phase
transition from nuclear to quark matter in a magnetised proto-neutron star and
compare our results with those obtained by us without the muons. We find that
the inclusion of muons changes slightly the nuclear density at which transition
occurs.However the dependence of this transition density on various chemical
potentials, temperature and the magnetic field remains quantitatively the same.Comment: LaTex2e file with four postscript figure
Oscillation dynamics of embolic microspheres in flows with red blood cell suspensions
Dynamic nature of particle motion in blood flow is an important determinant of embolization based cancer therapy. Yet, the manner in which the presence of high volume fraction of red blood cells influences the particle dynamics remains unknown. Here, by investigating the motions of embolic microspheres in pressure-driven flows of red blood cell suspensions through capillaries, we illustrate unique oscillatory trends in particle trajectories, which are not observable in Newtonian fluid flows. Our investigation reveals that such oscillatory behavior essentially manifests when three simultaneous conditions, namely, the Reynolds number beyond a threshold limit, degree of confinement beyond a critical limit, and high hematocrit level, are fulfilled simultaneously. Given that these conditions are extremely relevant to fluid dynamics of blood or polymer flow, the observations reported here bear significant implications on embolization based cancer treatment as well as for complex multiphase fluidics involving particle
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