3,491 research outputs found
Origin of the large thermoelectric power in oxygen-variable RBaCo_{2}O_{5+x} (R=Gd, Nd)
Thermoelectric properties of GdBaCo_{2}O_{5+x} and NdBaCo_{2}O_{5+x} single
crystals have been studied upon continuous doping of CoO_2 planes with either
electrons or holes. The thermoelectric response and the resistivity behavior
reveal a hopping character of the transport in both compounds, providing the
basis for understanding the recently found remarkable divergence of the Seebeck
coefficient at x=0.5. The doping dependence of the thermoelectric power evinces
that the configurational entropy of charge carriers, enhanced by their spin and
orbital degeneracy, plays a key role in the origin of the large thermoelectric
response in these correlated oxides.Comment: 5 pages, 4 figures, accepted for publication in PR
Planting a misdiagnosis of Alzheimer's disease in a person's mind
Objective: There is an extensive corpus of knowledge about how misinformation may distort autobiographical memories. A diagnostic error can be conceptualised as a form of misinformation. Methods: The authors discuss the case of a 58-year-old woman who was given a misdiagnosis of Alzheimer's disease. Results: The patient was deeply convinced that the diagnosis was correct, even when she was confronted with contradictory evidence. Conclusion: A diagnosis is not a neutral piece of information. It profoundly affects the lives of patients. The consequences of a misdiagnosis may be similar to persistent false memories
Low Temperature Magnetic Properties of the Double Exchange Model
We study the {\it ferromagnetic} (FM) Kondo lattice model in the strong
coupling limit (double exchange (DE) model). The DE mechanism proposed by Zener
to explain ferromagnetism has unexpected properties when there is more than one
itinerant electron. We find that, in general, the many-body ground state of the
DE model is {\it not} globally FM ordered (except for special filled-shell
cases). Also, the low energy excitations of this model are distinct from spin
wave excitations in usual Heisenberg ferromagnets, which will result in unusual
dynamic magnetic properties.Comment: 5 pages, RevTeX, 5 Postscript figures include
Discovery of a Quasar with Double-Peaked Broad Balmer Emission Lines
Most massive galaxies contain a supermassive black hole (SMBH) at their
center. When galaxies merge, their SMBHs sink to the center of the new galaxy
where they are thought to eventually merge. During this process an SMBH binary
is formed. The presence of two sets of broad emission lines in the optical
spectrum of an active galactic nucleus (AGN) has been interpreted as evidence
for two broad line regions (BLR), one surrounding each SMBH in a binary. We
modeled the broad Balmer emission lines in SDSS spectra of 373 extreme
variability AGNs using one broad and several narrow Gaussian components. We
report on the discovery of SDSS J021647.53011341.5 (hereafter J0216) as a
double-peaked broad emission line source. Among the 373 AGNs there were five
sources that are known double-peaked emission line sources. Three of these have
been reported as candidate SMBH binaries in previous studies. We present all
six objects and their double-peaked broad Balmer emission lines, and discuss
the implications for a tidal disruption event (TDE) interpretation of the
extreme variability assuming the double-peaked sources are SMBH binaries.Comment: 6 pages, 1 figure, 1 table. Accepted for publication in MNRA
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