3,467 research outputs found
K-Ras and ÎČ-catenin mutations cooperate with Fgfr3 mutations in mice to promote tumorigenesis in the skin and lung, but not in the bladder
The human fibroblast growth factor receptor 3 (FGFR3) gene is frequently mutated in superficial urothelial cell carcinoma (UCC). To test the functional significance of FGFR3 activating mutations as a âdriverâ of UCC, we targeted the expression of mutated Fgfr3 to the murine urothelium using Cre-loxP recombination driven by the uroplakin II promoter. The introduction of the Fgfr3 mutations resulted in no obvious effect on tumorigenesis up to 18 months of age. Furthermore, even when the Fgfr3 mutations were introduced together with K-Ras or ÎČ-catenin (Ctnnb1) activating mutations, no urothelial dysplasia or UCC was observed. Interestingly, however, owing to a sporadic ectopic Cre recombinase expression in the skin and lung of these mice, Fgfr3 mutation caused papilloma and promoted lung tumorigenesis in cooperation with K-Ras and ÎČ-catenin activation, respectively. These results indicate that activation of FGFR3 can cooperate with other mutations to drive tumorigenesis in a context-dependent manner, and support the hypothesis that activation of FGFR3 signaling contributes to human cancer
Pairing in spin polarized two-species fermionic mixtures with mass asymmetry
We discuss on the pairing mechanism of fermions with mismatch in their fermi
momenta due to a mass asymmetry. Using a variational ansatz for the ground
state we also discuss the BCS -BEC crossover of this system. It is shown that
the breached pairing solution with a single fermi surface is stable in the BEC
regime. We also include the temperatures effect on the fermion pairing within
an approximation that is valid for temperatures much below the critical
temperature.Comment: 8 pages and 6 figures, few typos corrected, version to appear in EPJ
Improving the color yield of ink-jet printing on cationized cotton
This study examines the performance of digital ink-jet printing on cationized cotton treated with polyepichlorohydrin-dimethylamine (PECH-amine). The results show that the color yield of ink-jet printing with reactive inks on cationic modified cotton is much greater than that on untreated cotton. The effect on the increase of color yield by cationic modification is greater than that by preparation with alkali, urea, and thickener. The reason for this is that introducing positively charged sites increases dye uptake and dye fixation on cationized cotton. The results also show that cationic modification with PECH-amine decreases the rub fastness but increases the wash fastness of the treated cotton. <br /
Process mapping of laser surface modification of AISI 316L stainless steel for biomedical applications
A 1.5-kW CO2 laser in pulsed mode at 3 kHz was used to investigate the effects of varied laser process parameters and resulting morphology of AISI 316L stainless steel. Irradiance and residence time were varied between 7.9 to 23.6 MW/cm2 and 50 to 167 ”s respectively. A strong correlation between irradiance, residence time, depth of processing and roughness of processed steel was established. The high depth of altered microstructure and increased roughness were linked to higher levels of both irradiance and residence times. Energy fluence and surface temperature models were used to predict levels of melting occurring on the surface through the analysis of roughness and depth of the region processed. Microstructural images captured by the SEM revealed significant grain structure changes at higher irradiances, but due to increased residence times, limited to the laser in use, the hardness values were not improved
Quantum versus Semiclassical Description of Selftrapping: Anharmonic Effects
Selftrapping has been traditionally studied on the assumption that
quasiparticles interact with harmonic phonons and that this interaction is
linear in the displacement of the phonon. To complement recent semiclassical
studies of anharmonicity and nonlinearity in this context, we present below a
fully quantum mechanical analysis of a two-site system, where the oscillator is
described by a tunably anharmonic potential, with a square well with infinite
walls and the harmonic potential as its extreme limits, and wherein the
interaction is nonlinear in the oscillator displacement. We find that even
highly anharmonic polarons behave similar to their harmonic counterparts in
that selftrapping is preserved for long times in the limit of strong coupling,
and that the polaronic tunneling time scale depends exponentially on the
polaron binding energy. Further, in agreement, with earlier results related to
harmonic polarons, the semiclassical approximation agrees with the full quantum
result in the massive oscillator limit of small oscillator frequency and strong
quasiparticle-oscillator coupling.Comment: 10 pages, 6 figures, to appear in Phys. Rev.
Apolipoprotein-induced conversion of phosphatidylcholine bilayer vesicles into nanodisks
AbstractApolipoprotein mediated formation of nanodisks was studied in detail using apolipophorin III (apoLp-III), thereby providing insight in apolipoproteinâlipid binding interactions. The spontaneous solubilization of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles occured only in a very narrow temperature range at the gelâliquidâcrystalline phase transition temperature, exhibiting a net exothermic interaction based on isothermal titration calorimetry analysis. The resulting nanodisks were protected from proteolysis by trypsin, endoproteinase Glu-C, chymotrypsin and elastase. DMPC solubilization and the simultaneous formation of nanodisks were promoted by increasing the vesicle diameter, protein to lipid ratio and concentration. Inclusion of cholesterol in DMPC dramatically enhanced the rate of nanodisk formation, presumably by stabilization of lattice defects which form the main insertion sites for apolipoprotein α-helices. The presence of fully saturated acyl chains with a length of 13 or 14 carbons in phosphatidylcholine allowed the spontaneous vesicle solubilization upon apolipoprotein addition. Nanodisks with C13:0-phosphatidylcholine were significantly smaller with a diameter of 11.7±3.1nm compared to 18.5±5.6nm for DMPC nanodisks determined by transmission electron microscopy. Nanodisk formation was not observed when the phosphatidylcholine vesicles contained acyl chains of 15 or 16 carbons. However, using very high concentrations of lipid and protein (>10mg/ml), 1,2,-dipalmitoyl-sn-glycero-3-phosphocholine nanodisks could be produced spontaneously although the efficiency remained low
Variable Step Random Walks and Self-Similar Distributions
We study a scenario under which variable step random walks give anomalous
statistics. We begin by analyzing the Martingale Central Limit Theorem to find
a sufficient condition for the limit distribution to be non-Gaussian. We note
that the theorem implies that the scaling index is 1/2. For
corresponding continuous time processes, it is shown that the probability
density function satisfies the Fokker-Planck equation. Possible forms
for the diffusion coefficient are given, and related to . Finally, we
show how a time-series can be used to distinguish between these variable
diffusion processes and L\'evy dynamics.Comment: 13pages, 2 figure
Nanoscale Phenomenology from Visualizing Pair Formation Experiment
Recently, Gomes et al. [1] have visualized the gap formation in nanoscale
regions (NRs) above the critical temperature T_c in the high-T_c superconductor
Bi_2Sr_2CaCu_2O_{8+\delta}. It has been found that, as the temperature lowers,
the NRs expand in the bulk superconducting state consisted of inhomogeneities.
The fact that the size of the inhomogeneity [2] is close to the minimal size of
the NR [1] leads to a conclusion that the superconducting phase is a result of
these overlapped NRs. In the present paper we perform the charge and
percolation regime analysis of NRs and show that at the first critical doping
x_{c1}, when the superconductivity starts on, each NR carries the positive
electric charge one in units of electron charge, thus we attribute the NR to a
single hole boson, and the percolation lines connecting these bosons emerge. At
the second critical doping x_{c2}, when the superconductivity disappears, our
analysis demonstrates that the charge of each NR equals two. The origin of
x_{c2} can be understood by introducing additional normal phase hole fermions
in NRs, whose concentration appearing above x_{c1} increases smoothly with the
doping and breaks the percolation lines of bosons at x_{c2}. The last one
results in disappearing the bulk bosonic property of the pseudogap (PG) region,
which explains the upper bound for existence of vortices in Nernst effect [3].
Since [1] has demonstrated the absence of NRs at the PG boundary one can
conclude that along this boundary, as well as in x_{c2}, all bosons disappear.Comment: 4 pages, 1 figure. Good quality figure one can find in published
journal paper. Added 4 new references. Section of arXiv: 1010.043
- âŠ