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Tissue-type plasminogen activator-primed human iPSC-derived neural progenitor cells promote motor recovery after severe spinal cord injury.
The goal of stem cell therapy for spinal cord injury (SCI) is to restore motor function without exacerbating pain. Induced pluripotent stem cells (iPSC) may be administered by autologous transplantation, avoiding immunologic challenges. Identifying strategies to optimize iPSC-derived neural progenitor cells (hiNPC) for cell transplantation is an important objective. Herein, we report a method that takes advantage of the growth factor-like and anti-inflammatory activities of the fibrinolysis protease, tissue plasminogen activator tPA, without effects on hemostasis. We demonstrate that conditioning hiNPC with enzymatically-inactive tissue-type plasminogen activator (EI-tPA), prior to grafting into a T3 lesion site in a clinically relevant severe SCI model, significantly improves motor outcomes. EI-tPA-primed hiNPC grafted into lesion sites survived, differentiated, acquired markers of motor neuron maturation, and extended βIII-tubulin-positive axons several spinal segments below the lesion. Importantly, only SCI rats that received EI-tPA primed hiNPC demonstrated significantly improved motor function, without exacerbating pain. When hiNPC were treated with EI-tPA in culture, NMDA-R-dependent cell signaling was initiated, expression of genes associated with stemness (Nestin, Sox2) was regulated, and thrombin-induced cell death was prevented. EI-tPA emerges as a novel agent capable of improving the efficacy of stem cell therapy in SCI
Locking Local Oscillator Phase to the Atomic Phase via Weak Measurement
We propose a new method to reduce the frequency noise of a Local Oscillator
(LO) to the level of white phase noise by maintaining (not destroying by
projective measurement) the coherence of the ensemble pseudo-spin of atoms over
many measurement cycles. This scheme uses weak measurement to monitor the phase
in Ramsey method and repeat the cycle without initialization of phase and we
call, "atomic phase lock (APL)" in this paper. APL will achieve white phase
noise as long as the noise accumulated during dead time and the decoherence are
smaller than the measurement noise. A numerical simulation confirms that with
APL, Allan deviation is averaged down at a maximum rate that is proportional to
the inverse of total measurement time, tau^-1. In contrast, the current atomic
clocks that use projection measurement suppress the noise only down to the
level of white frequency, in which case Allan deviation scales as tau^-1/2.
Faraday rotation is one of the possible ways to realize weak measurement for
APL. We evaluate the strength of Faraday rotation with 171Yb+ ions trapped in a
linear rf-trap and discuss the performance of APL. The main source of the
decoherence is a spontaneous emission induced by the probe beam for Faraday
rotation measurement. One can repeat the Faraday rotation measurement until the
decoherence become comparable to the SNR of measurement. We estimate this
number of cycles to be ~100 cycles for a realistic experimental parameter.Comment: 18 pages, 7 figures, submitted to New Journal of Physic
Pyrochlore Antiferromagnet: A Three-Dimensional Quantum Spin Liquid
The quantum pyrochlore antiferromagnet is studied by perturbative expansions
and exact diagonalization of small clusters. We find that the ground state is a
spin-liquid state: The spin-spin correlation functions decay exponentially with
distance and the correlation length never exceeds the interatomic distance. The
calculated magnetic neutron diffraction cross section is in very good agreement
with experiments performed on Y(Sc)Mn2. The low energy excitations are
singlet-singlet ones, with a finite spin gap.Comment: 4 pages, 4 figure
Hubbard chains network on corner-sharing tetrahedra: origin of the heavy fermion state in LiV_2O_4
We investigate the Hubbard chains network model defined on corner-sharing
tetrahedra (the pyrochlore lattice) which is a possible microscopic model for
the heavy fermion state of LiV_2O_4. Based upon this model, we can explain
transport, magnetic, and thermodynamic properties of LiV_2O_4. We calculate the
spin susceptibility, and the specific heat coefficient, exploiting the Bethe
ansatz exact solution of the 1D Hubbard model and bosonization method. The
results are quite consistent with experimental observations. We obtain the
large specific heat coefficient .Comment: 5 pages, 2 figures, a postscript file of Figure 1 is not included, to
appear in Physical Review
Bessel bridges decomposition with varying dimension. Applications to finance
We consider a class of stochastic processes containing the classical and
well-studied class of Squared Bessel processes. Our model, however, allows the
dimension be a function of the time. We first give some classical results in a
larger context where a time-varying drift term can be added. Then in the
non-drifted case we extend many results already proven in the case of classical
Bessel processes to our context. Our deepest result is a decomposition of the
Bridge process associated to this generalized squared Bessel process, much
similar to the much celebrated result of J. Pitman and M. Yor. On a more
practical point of view, we give a methodology to compute the Laplace transform
of additive functionals of our process and the associated bridge. This permits
in particular to get directly access to the joint distribution of the value at
t of the process and its integral. We finally give some financial applications
to illustrate the panel of applications of our results
Anomalous behaviors of the charge and spin degrees of freedom in the CuO double chains of PrBaCuO
The density-matrix renormalization-group method is used to study the
electronic states of a two-chain Hubbard model for CuO double chains of
PrBaCuO. We show that the model at quarter filling has the charge
ordered phases with stripe-type and in-line--type patterns in the parameter
space, and in-between, there appears a wide region of vanishing charge gap; the
latter phase is characteristic of either Tomonaga-Luttinger liquid or a
metallic state with a spin gap. We argue that the low-energy electronic state
of the CuO double chains of PrBaCuO should be in the metallic state
with a possibly small spin gap.Comment: REVTEX 4, 10 pages, 9 figures; submitted to PR
Temperature dependent Eu 3d-4f X-ray Absorption and Resonant Photoemission Study of the Valence Transition in
We study the mixed valence transition ( 80 K) in
EuNi(SiGe) using Eu 3 X-ray absorption
spectroscopy (XAS) and resonant photoemission spectroscopy (RESPES). The
Eu and Eu main peaks show a giant resonance and the spectral
features match very well with atomic multiplet calculations. The spectra show
dramatic temperature ()-dependent changes over large energies (10 eV)
in RESPES and XAS. The observed non-integral mean valencies of 2.35
0.03 ( = 120 K) and 2.70 0.03 ( = 40 K) indicate homogeneous
mixed valence above and below . The redistribution between
Eu+ and Eu+ states is attributed to
a hybridization change coupled to a Kondo-like volume collapse.Comment: 4 pages, 3 figure
Pressure Induced Quantum Critical Point and Non-Fermi-Liquid Behavior in BaVS3
The phase diagram of BaVS3 is studied under pressure using resistivity
measurements. The temperature of the metal to nonmagnetic Mott insulator
transition decreases under pressure, and vanishes at the quantum critical point
p_cr=20kbar. We find two kinds of anomalous conducting states. The
high-pressure metallic phase is a non-Fermi liquid described by Delta rho = T^n
where n=1.2-1.3 at 1K < T < 60K. At p<p_cr, the transition is preceded by a
wide precursor region with critically increasing resistivity which we ascribe
to the opening of a soft Coulomb gap.Comment: 4 pages, 5 eps figures, problem with figure correcte
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