820 research outputs found
Metastable ferromagnetic clusters in dissipative many-body systems of polar molecules
We investigate the effect of two-body loss due to chemical reactions on
quantum magnetism of fermionic polar molecules in an optical lattice. We show
that an interplay between dissipation and strong long-range interactions leads
to formation of metastable ferromagnetic clusters. The spin states of clusters
are controlled by interaction parameters and reflect the symmetry of
interactions. The size of clusters strongly depends on the initial
configuration of molecules due to Hilbert-space fragmentation during
dissipative many-body dynamics. We construct an effective model to show the
emergence of metastable states as quasi-dark states. Application to quantum
simulation of the spin- Heisenberg model is discussed.Comment: 12 pages, 7 figure
Pressure-induced quantum critical point in a heavily hydrogen-doped iron-based superconductor LaFeAsO
An iron-based superconductor LaFeAsOH (0 0.6)
undergoes two antiferromagnetic (AF) phases upon H doping. We investigated the
second AF phase (=0.6) using NMR techniques under pressure. At pressures up
to 2 GPa, the ground state is a spin-density-wave state with a large gap;
however, the gap closes at 4.0 GPa, suggesting a pressure-induced quantum
critical point. Interestingly, the gapped excitation coexists with gapless
magnetic fluctuations at pressures between 2 and 4 GPa. This coexistence is
attributable to the lift up of the orbital to the Fermi level, a
Lifshitz transition under pressure
Full MAC System Demonstration of Extended 10G-EPON Uplink with 512 ONU Splits Access Span via Burst-Mode SOA and Enhanced-FEC combined with Burst-Mode 3R
This first Extended 10G-EPON uplink system test achieved the largest access span loss of 37 dB supporting 512 ONU splits over 25 km with an enlarged loss budget of 51.2 dB via burst-mode SOA, E-FEC and burst-mode 3R
APC sets the Wnt tone necessary for cerebral cortical progenitor development
Adenomatous polyposis coli (APC) regulates the activity of β-catenin, an integral component of Wnt signaling. However, the selective role of the APC–β-catenin pathway in cerebral cortical development is unknown. Here we genetically dissected the relative contributions of APC-regulated β-catenin signaling in cortical progenitor development, a necessary early step in cerebral cortical formation. Radial progenitor-specific inactivation of the APC–β-catenin pathway indicates that the maintenance of appropriate β-catenin-mediated Wnt tone is necessary for the orderly differentiation of cortical progenitors and the resultant formation of the cerebral cortex. APC deletion deregulates β-catenin, leads to high Wnt tone, and disrupts Notch1 signaling and primary cilium maintenance necessary for radial progenitor functions. β-Catenin deregulation directly disrupts cilium maintenance and signaling via Tulp3, essential for intraflagellar transport of ciliary signaling receptors. Surprisingly, deletion of β-catenin or inhibition of β-catenin activity in APC-null progenitors rescues the APC-null phenotype. These results reveal that APC-regulated β-catenin activity in cortical progenitors sets the appropriate Wnt tone necessary for normal cerebral cortical development
Infrared and hard X-ray diagnostics of AGN identification from the Swift/BAT and AKARI all-sky surveys
We combine data from two all-sky surveys in order to study the connection
between the infrared and hard X-ray (>10keV) properties for local active
galactic nuclei (AGN). The Swift/Burst Alert Telescope all-sky survey provides
an unbiased, flux-limited selection of hard X-ray detected AGN.
Cross-correlating the 22-month hard X-ray survey with the AKARI all-sky survey,
we studied 158 AGN detected by the AKARI instruments. We find a strong
correlation for most AGN between the infrared (9, 18, and 90 micron) and hard
X-ray (14-195 keV) luminosities, and quantify the correlation for various
subsamples of AGN. Partial correlation analysis confirms the intrinsic
correlation after removing the redshift contribution. The correlation for radio
galaxies has a slope and normalization identical to that for Seyfert 1s,
implying similar hard X-ray/infrared emission processes in both. In contrast,
Compton-thick sources show a large deficit in the hard X-ray band, because high
gas column densities diminish even their hard X-ray luminosities. We propose
two photometric diagnostics for source classification: one is an X-ray
luminosity vs. infrared color diagram, in which type 1 radio-loud AGN are well
isolated from the others in the sample. The other uses the X-ray vs. infrared
color as a useful redshift-independent indicator for identifying Compton-thick
AGN. Importantly, Compton-thick AGN and starburst galaxies in composite systems
can also be differentiated in this plane based upon their hard X-ray fluxes and
dust temperatures. This diagram may be useful as a new indicator to classify
objects in new and upcoming surveys such as WISE and NuSTAR.Comment: 17 pages, 5 figures, 5 tables. Accepted for publication in the
Astrophysical Journa
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