471 research outputs found
Identification of the novel localization of tenascinX in the monkey choroid plexus and comparison with the mouse
Tenascin-X (Tn-X) belongs to the tenascin family of glycoproteins and has been reported to be significantly associated with schizophrenia in a single nucleotide polymorphism analysis in humans. This finding indicates an important role of Tn-X in the central nervous system (CNS). However, details of Tn-X localization are not clear in the primate CNS. Using immunohistochemical techniques, we found novel localizations of Tn-X in the interstitial connective tissue and around blood vessels in the choroid plexus (CP) in macaque monkeys. To verify the reliability of Tn-X localization, we compared the Tn-X localization with the tenascin-C (Tn-C) localization in corresponding regions using neighbouring sections. Localization of Tn-C was not observed in CP. This result indicated consistently restricted localization of Tn-X in CP. Comparative investigations using mouse tissues showed equivalent results. Our observations provide possible insight into specific roles of Tn-X in CP for mammalian CNS function
Magnetoresistance in Disordered Graphene: The Role of Pseudospin and Dimensionality Effects Unraveled
We report a theoretical low-field magnetotransport study unveiling the effect
of pseudospin in realistic models of weakly disordered graphene-based
materials. Using an efficient Kubo computational method, and simulating the
effect of charges trapped in the oxide, different magnetoconductance
fingerprints are numerically obtained in system sizes as large as 0.3
micronmeter squared, containing tens of millions of carbon atoms. In
two-dimensional graphene, a strong valley mixing is found to irreparably yield
a positive magnetoconductance (weak localization), whereas crossovers from
positive to a negative magnetoconductance (weak antilocalization) are obtained
by reducing disorder strength down to the ballistic limit. In sharp contrast,
graphene nanoribbons with lateral size as large as 10nm show no sign of weak
antilocalization, even for very small disorder strength. Our results
rationalize the emergence of a complex phase diagram of magnetoconductance
fingerprints, shedding some new light on the microscopical origin of pseudospin
effects.Comment: 8 pages, 5 figure
Full counting statistics for transport through a molecular quantum dot magnet
Full counting statistics (FCS) for the transport through a molecular quantum
dot magnet is studied theoretically in the incoherent tunneling regime. We
consider a model describing a single-level quantum dot, magnetically coupled to
an additional local spin, the latter representing the total molecular spin s.
We also assume that the system is in the strong Coulomb blockade regime, i.e.,
double occupancy on the dot is forbidden. The master equation approach to FCS
introduced in Ref. [12] is applied to derive a generating function yielding the
FCS of charge and current. In the master equation approach, Clebsch-Gordan
coefficients appear in the transition probabilities, whereas the derivation of
generating function reduces to solving the eigenvalue problem of a modified
master equation with counting fields. To be more specific, one needs only the
eigenstate which collapses smoothly to the zero-eigenvalue stationary state in
the limit of vanishing counting fields. We discovered that in our problem with
arbitrary spin s, some quartic relations among Clebsch-Gordan coefficients
allow us to identify the desired eigenspace without solving the whole problem.
Thus we find analytically the FCS generating function in the following two
cases: i) both spin sectors lying in the bias window, ii) only one of such spin
sectors lying in the bias window. Based on the obtained analytic expressions,
we also developed a numerical analysis in order to perform a similar
contour-plot of the joint charge-current distribution function, which have
recently been introduced in Ref. [13], here in the case of molecular quantum
dot magnet problem.Comment: 17 pages, 5 figure
Anomalous tunneling conductances of a spin singlet \nu=2/3 edge states: Interplay of Zeeman splitting and Long Range Coulomb Interaction
The point contact tunneling conductance between edges of the spin singlet
quantum Hall states is studied both in the
quasiparticle tunneling picture and in the electron tunneling picture. Due to
the interplay of Zeeman splitting and the long range Coulomb interaction
between edges of opposite chirality novel spin excitations emerge, and their
effect is characterized by anomalous exponents of the charge and spin tunneling
conductances in various temperature ranges. Depending on the kinds of
scatterings at the point contact and the tunneling mechanism the anomalous
interaction in spin sector may enhance or suppress the tunneling conductances.
The effects of novel spin excitation are also relevant to the recent NMR
experiments on quantum Hall edges.Comment: Revtex File, 7 pages: To be published in Physical Reviews
Theory of suppressed shot-noise at
We study the edge states of fractional quantum Hall liquid at bulk filling
factor with being an even integer and . We
describe the transition from a conductance plateau to
another plateau in terms of chiral Tomonaga-Luttinger liquid
theory. It is found that the fractional charge which appears in the
classical shot-noise formula is on the
conductance plateau at whereas on the plateau at
it is given by . For and an alternative hierarchy
constructions is also discussed to explain the suppressed shot-noise experiment
at bulk filling factor .Comment: Typos in Eqs. (5-7) correcte
Strong quasi-particle tunneling study in the paired quantum Hall states
The quasi-particle tunneling phenomena in the paired fractional quantum Hall
states are studied. A single point-contact system is first considered. Because
of relevancy of the quasi-particle tunneling term, the strong tunneling regime
should be investigated.
Using the instanton method it is shown that the strong quasi-particle
tunneling regime is described as the weak electron tunneling regime
effectively.
Expanding to the network model the paired quantum Hall liquid to insulator
transition is discussed
Palaeolimnological reconstruction of Holocene climate variability in Lützow Holm Bay, East Antarctica
Theory of non-equilibrium noise in general multi-terminal superconducting hydrid devices: application to multiple Cooper pair resonances
We consider the out-of-equilibrium behavior of a general class of mesoscopic
devices composed of several superconducting or/and normal metal leads separated
by quantum dots. Starting from a microscopic Hamiltonian description, we
provide a non-perturbative approach to quantum electronic transport in the
tunneling amplitudes between dots and leads: using the equivalent of a path
integral formulation, the lead degrees of freedom are integrated out in order
to compute both the current and the current correlations (noise) in this class
of systems, in terms of the dressed Green's function matrix of the quantum
dots. In order to illustrate the efficiency of this formalism, we apply our
results to the "all superconducting Cooper pair beam splitter", a device
composed of three superconducting leads connected via two quantum dots, where
crossed Andreev reflection operates Cooper pair splitting. Commensurate voltage
differences between the three leads allow to obtain expressions for the current
and noise as a function of the Keldysh Nambu Floquet dressed Green's function
of the dot system. This voltage configuration allows the occurrence of
non-local processes involving multiple Cooper pairs which ultimately lead to
the presence of non-zero DC currents in an out-of-equilibrium situation. We
investigate in details the results for the noise obtained numerically in the
specific case of opposite voltages, where the transport properties are
dominated by the so called "quartet processes", involving the coherent exchange
of two Cooper pairs among all three superconducting terminals. We show that
these processes are noiseless in the non-resonant case, and that this property
is also observed for other voltage configurations. When the dots are in a
resonant regime, the noise characteristics change qualitatively, with the
appearance of giant Fano factors.Comment: 18 pages, 12 figure
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