594 research outputs found
E-Cadherin in Pancreatic Ductal Adenocarcinoma: A Multifaceted Actor during EMT
Epithelial-to-mesenchymal transition (EMT) is a step-wise process observed in normal and tumor cells leading to a switch from epithelial to mesenchymal phenotype. In tumors, EMT provides cancer cells with a metastatic phenotype characterized by E-cadherin down-regulation, cytoskeleton reorganization, motile and invasive potential. E-cadherin down-regulation is known as a key event during EMT. However, E-cadherin expression can be influenced by the different experimental settings and environmental stimuli so that the paradigm of EMT based on the loss of E-cadherin determining tumor cell behavior and fate often becomes an open question. In this review, we aimed at focusing on some critical points in order to improve the knowledge of the dynamic role of epithelial cells plasticity in EMT and, specifically, address the role of E-cadherin as a marker for the EMT axis
Optical Conductivity of the Two-Dimensional Hubbard Model
Charge dynamics of the two-dimensional Hubbard model is investigated.
Lanczs-diagonalization results for the optical conductivity and
the Drude weight of this model are presented. Near the Mott transition, large
incoherence below the upper-Hubbard band is obtained together with a remarkably
suppressed Drude weight in two dimensions while the clearly coherent character
is shown in one dimension. The two-dimensional results are consistent with
previous results from quantum Monte Carlo calculations indicating that the Mott
transition in this two-dimensional model belongs to the universality class
characterized by the dynamical exponent of .Comment: 4 pages LaTeX including 2 PS figures, to appear in J. Phys. Soc. Jp
Charge and spin excitations of insulating lamellar copper oxides
A consistent description of low-energy charge and spin responses of the
insulating Sr_2CuO_2Cl_2 lamellar system is found in the framework of a
one-band Hubbard model which besides includes hoppings up to 3^{rd}
nearest-neighbors. By combining mean-field calculations, exact diagonalization
(ED) results, and Quantum Monte Carlo simulations (QMC), we analyze both charge
and spin degrees of freedom responses as observed by optical conductivity,
ARPES, Raman and inelastic neutron scattering experiments. Within this
effective model, long-range hopping processes flatten the quasiparticle band
around . We calculate also the non-resonant A_{1g} and B_{1g} Raman
profiles and show that the latter is composed by two main features, which are
attributed to 2- and 4-magnon scattering.Comment: 6 pages, 3 figures, To be published in PRB (july
Drude Weight of the Two-Dimensional Hubbard Model -- Reexamination of Finite-Size Effect in Exact Diagonalization Study --
The Drude weight of the Hubbard model on the two-dimensional square lattice
is studied by the exact diagonalizations applied to clusters up to 20 sites. We
carefully examine finite-size effects by consideration of the appropriate
shapes of clusters and the appropriate boundary condition beyond the imitation
of employing only the simple periodic boundary condition. We successfully
capture the behavior of the Drude weight that is proportional to the squared
hole doping concentration. Our present result gives a consistent understanding
of the transition between the Mott insulator and doped metals. We also find, in
the frequency dependence of the optical conductivity, that the mid-gap
incoherent part emerges more quickly than the coherent part and rather
insensitive to the doping concentration in accordance with the scaling of the
Drude weight.Comment: 9 pages with 10 figures and 1 table. accepted in J. Phys. Soc. Jp
Direct Calculation of the Spin Stiffness in the -- Heisenberg Antiferromagnet
We calculate the spin stiffness for the frustrated
spin- Heisenberg antiferromagnet on a square lattice by exact
diagonalizations on finite clusters of up to sites followed by
extrapolations to the thermodynamic limit. For the non-frustrated case, we find
that , in excellent agreement with the best
results obtained by other means. Turning on frustration, the extrapolated
stiffness vanishes for . In this
intermediate region, the finite-size scaling works poorly -- an additional sign
that their is neither N\'eel nor collinear magnetic order. Using a hydrodynamic
relation, and previous results for the transverse susceptibility, we also
estimate the spin-wave velocity in the N\'eel-ordered region.Comment: 4 pages, uuencoded compressed ps-file (made with uufiles
Rebamipide Does Not Protect Against Naproxen-induced Gastric Damage: A Randomized Double-blind Controlled Trial
Rebamipide is a gastroprotective agent with promising results against gastric damage induced by non-steroidal anti-inflammatory drugs. The present study evaluated if rebamipide protects against naproxen-induced gastric damage in healthy volunteers. Changes in gastric PGE2 tissue concentration were also evaluated. Methods: After a preliminary endoscopy to rule out previous gastric macroscopic damage, twenty-four healthy volunteers of both sexes were divided into 2 groups. One group received sodium naproxen 550 mg b.i.d. plus placebo for 7 days, while the other group received sodium naproxen 550 mg b.i.d. plus rebamipide 100 mg b.i.d. At the end of treatment, a new endoscopy was performed. Gastric macroscopic damage was evaluated by the Cryer score and by the modified Lanza score. The primary outcome measure of the trial was the macroscopic damage observed in each treatment group at the end of treatment. Biopsies were collected at both endoscopies for PGE2 quantification and histopathological analysis (secondary outcomes). Tissue PGE2 was quantified by ELISA. The randomization sequence was generated using 3 blocks of 8 subjects each. Volunteers and endoscopists were blind to whether they were receiving rebamipide or placebo. Results: All recruited volunteers completed the trial. Sodium naproxen induced gastric damage in both groups. At the end of the study, median Cryer score was 4 in both groups (Difference = 0; 95% CI = -1 to 0; p = 0.728). In the placebo group, the mean tissue PGE2 concentration was 1005 +/- 129 pg/mL before treatment and 241 +/- 41 pg/mL after treatment (p < 0.001). In the rebamipide group, the mean tissue PGE2 concentration was 999 +/- 109 pg/mL before treatment, and 168 +/- 13 pg/mL after treatment (p < 0.001). There was no difference in mean tissue PGE2 between the two groups (difference = 5; 95% CI from -334.870 to 345.650; p = 0.975). No significant change was observed at the histopathological evaluation, despite the evident macroscopic damage induced by naproxen. Conclusion: Rebamipide does not protect against naproxen-induced gastric damage in healthy volunteers.1658Biolab Industria Farmaceutica Ltd
Optical Absorption of CuO antiferromagnetic chains at finite temperatures
We use a high-statistic quantum Monte Carlo and Maximum Entropy
regularization method to compute the dynamical energy correlation function
(DECF) of the one-dimensional (1D) antiferromagnetic Heisenberg model
at finite temperatures. We also present a finite temperature analytical ansatz
for the DECF which is in very good agreement with the numerical data in all the
considered temperature range. From these results, and from a finite temperature
generalisation of the mechanism proposed by Lorenzana and Sawatsky [Phys. Rev.
Lett. {\bf 74}, 1867 (1995)], we compute the line shape for the optical
absorption spectra of multimagnon excitations assisted by phonons for quasi 1D
compounds. The line shape has two contributions analogous to the Stokes and
anti-Stokes process of Raman scattering. Our low temperature data is in good
agreement with optical absorption experiments of CuO chains in
SrCuO. Our finite temperature results provide a non trivial prediction
on the dynamics of the Heisenberg model at finite temperatures that is easy to
verify experimentally.Comment: 7 pages, 5 figure
Computers from plants we never made. Speculations
We discuss possible designs and prototypes of computing systems that could be
based on morphological development of roots, interaction of roots, and analog
electrical computation with plants, and plant-derived electronic components. In
morphological plant processors data are represented by initial configuration of
roots and configurations of sources of attractants and repellents; results of
computation are represented by topology of the roots' network. Computation is
implemented by the roots following gradients of attractants and repellents, as
well as interacting with each other. Problems solvable by plant roots, in
principle, include shortest-path, minimum spanning tree, Voronoi diagram,
-shapes, convex subdivision of concave polygons. Electrical properties
of plants can be modified by loading the plants with functional nanoparticles
or coating parts of plants of conductive polymers. Thus, we are in position to
make living variable resistors, capacitors, operational amplifiers,
multipliers, potentiometers and fixed-function generators. The electrically
modified plants can implement summation, integration with respect to time,
inversion, multiplication, exponentiation, logarithm, division. Mathematical
and engineering problems to be solved can be represented in plant root networks
of resistive or reaction elements. Developments in plant-based computing
architectures will trigger emergence of a unique community of biologists,
electronic engineering and computer scientists working together to produce
living electronic devices which future green computers will be made of.Comment: The chapter will be published in "Inspired by Nature. Computing
inspired by physics, chemistry and biology. Essays presented to Julian Miller
on the occasion of his 60th birthday", Editors: Susan Stepney and Andrew
Adamatzky (Springer, 2017
LACHESIS restricts gametic cell fate in the female gametophyte of Arabidopsis
In flowering plants, the egg and sperm cells form within haploid gametophytes. The female gametophyte of Arabidopsis consists of two gametic cells, the egg cell and the central cell, which are flanked by five accessory cells. Both gametic and accessory cells are vital for fertilization; however, the mechanisms that underlie the formation of accessory versus gametic cell fate are unknown. In a screen for regulators of egg cell fate, we isolated the lachesis (lis) mutant which forms supernumerary egg cells. In lis mutants, accessory cells differentiate gametic cell fate, indicating that LIS is involved in a mechanism that prevents accessory cells from adopting gametic cell fate. The temporal and spatial pattern of LIS expression suggests that this mechanism is generated in gametic cells. LIS is homologous to the yeast splicing factor PRP4, indicating that components of the splice apparatus participate in cell fate decisions
Dynamical Structure Factors of the S=1/2 Bond-Alternating Spin Chain with a Next-Nearest-Neighbor Interaction in Magnetic Fields
The dynamical structure factor of the S=1/2 bond-alternating spin chain with
a next-nearest-neighbor interaction in magnetic field is investigated using the
continued fraction method based on the Lanczos algorithm. When the plateau
exists on the magnetization curve, the longitudinal dynamical structure factor
shows a large intensity with a periodic dispersion relation, while the
transverse one shows a large intensity with an almost dispersionless mode. The
periodicity and the amplitude of the dispersion relation in the longitudinal
dynamical structure factor are sensitive to the coupling constants. The
dynamical structure factor of the S=1/2 two-leg ladder in magnetic field is
also calculated in the strong interchain-coupling regime.
The dynamical structure factor shows gapless or gapful behavior depending on
the wave vector along the rung.Comment: 8 pages, 4 figures, to appear in Journal of the Physical Society of
Japan, vol. 69, no. 10, (2000
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