3,166 research outputs found
Morphological detection of X- and Y-chromosomes in smears and paraffin-embedded tissues using a non-isotopic in situ hybridization technique (NISH)
Pharyngeal smears and paraffin-embedded tissue specimens (skeletal muscle, kidney) obtained from 10 male and 10 female individuals were evaluated using non-isotopic in situ hybridization (NISH) with commercial X- and Y-specific biotinylated probes which recognize the pericentromeric regions DXZ1 and DYZ1/DYZ3 of the X- and Y-chromosome, respectively. The results provide evidence that the morphological sex determination of a single cell can be performed by critical application of this staining method leading to one nuclear signal in ldquomalerdquo cells using the Y-specific probe whereas ldquofemalerdquo cells are negative. In situ hybridization of ldquofemalerdquo tissues with an X-specific probe results regularly in 2 signals whereas ldquomalerdquo cells show only one spot in the nucleus
Superadiabatic transitions in quantum molecular dynamics
We study the dynamics of a molecule’s nuclear wave function near an avoided crossing of two electronic energy levels for one nuclear degree of freedom. We derive the general form of the Schrödinger equation in the nth superadiabatic representation for all n є N. Using these results, we obtain closed formulas for the time development of the component of the wave function in an initially unoccupied energy subspace when a wave packet travels through the transition region. In the optimal superadiabatic representation, which we define, this component builds up monotonically. Finally, we give an explicit formula for the transition wave function away from the avoided crossing, which is in excellent agreement with high-precision numerical calculations
Supercollision cooling in undoped graphene
Carrier mobility in solids is generally limited by electron-impurity or
electron-phonon scattering depending on the most frequently occurring event.
Three body collisions between carriers and both phonons and impurities are
rare; they are denoted supercollisions (SCs). Elusive in electronic transport
they should emerge in relaxation processes as they allow for large energy
transfers. As pointed out in Ref. \onlinecite{Song2012PRL}, this is the case in
undoped graphene where the small Fermi surface drastically restricts the
allowed phonon energy in ordinary collisions. Using electrical heating and
sensitive noise thermometry we report on SC-cooling in diffusive monolayer
graphene. At low carrier density and high phonon temperature the Joule power
obeys a law as a function of electronic temperature .
It overrules the linear law expected for ordinary collisions which has recently
been observed in resistivity measurements. The cubic law is characteristic of
SCs and departs from the dependence recently reported for metallic
graphene below the Bloch-Gr\"{u}neisen temperature. These supercollisions are
important for applications of graphene in bolometry and photo-detection
Sodium Transport in Capillaries Isolated from Rat Brain
Brain capillary endothelial cells form a bloodbrain barrier (BBB) that appears to play a role in fluid and ion homeostasis in brain. One important transport system that may be involved in this regulatory function is the Na + ,K + -ATPase that was previously demonstrated to be present in isolated brain capillaries. The goal of the present study was to identify additional Na + transport systems in brain capillaries that might contribute to BBB function. Microvessels were isolated from rat brains and 22 Na + uptake by and efflux from the cells were studied. Total 22 Na + uptake was increased and the rate of 22 Na + efflux was decreased by ouabain, confirming the presence of Na + ,K + -ATPase in capillary cells. After inhibition of Na + ,K + -ATPase activity, another saturable Na + transport mechanism became apparent. Capillary uptake of 22 Na + was stimulated by an elevated concentration of Na + or H + inside the cells and inhibited by extracellular Na + , H + , Li + , and NH 4 + . Amiloride inhibited 22 Na + uptake with a K i between 10 −5 and 10 −6 M but there was no effect of 1 mM furosemide on 22 Na + uptake by the isolated microvessels. These results indicate the presence in brain capillaries of a transport system capable of mediating Na + / Na + and Na + /H + exchange. As a similar transport system does not appear to be present on the luminal membrane of the brain capillary endothelial cell, it is proposed that Na + /H + exchange occurs primarily across the antiluminal membrane.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66187/1/j.1471-4159.1983.tb09065.x.pd
Hot electron cooling by acoustic phonons in graphene
We have investigated the energy loss of hot electrons in metallic graphene by
means of GHz noise thermometry at liquid helium temperature. We observe the
electronic temperature T / V at low bias in agreement with the heat diffusion
to the leads described by the Wiedemann-Franz law. We report on
behavior at high bias, which corresponds to a T4 dependence
of the cooling power. This is the signature of a 2D acoustic phonon cooling
mechanism. From a heat equation analysis of the two regimes we extract accurate
values of the electron-acoustic phonon coupling constant in monolayer
graphene. Our measurements point to an important effect of lattice disorder in
the reduction of , not yet considered by theory. Moreover, our study
provides a strong and firm support to the rising field of graphene bolometric
detectors.Comment: 5 figure
Sensitivity of Azimuthal Jet Tomography to Early Time Energy-Loss at RHIC and LHC
We compute the jet path-length dependence of energy-loss for higher azimuthal
harmonics of jet-fragments in a generalized model of energy-loss that can
interpolate between pQCD and AdS/CFT limits and compare results with Glauber
and CGC/KLN initial conditions. We find, however, that even the high-pT second
moment is most sensitive to the poorly known early-time evolution during the
first fm/c. Moreover, we demonstrate that quite generally the energy and
density-dependence leads to an overquenching jet fragments relative to the
first LHC -data, once the parameters of the energy-loss model are fixed
from -data at RHIC.Comment: 4 pages, 2 figures, version accepted for publication in J. Phys. G:
Nucl. Part. Phys. as conference proceedings for Quark Matter 2011, May 23 -
May 28, Annecy, Franc
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