984 research outputs found
Periodic orbits of period 3 in the disc
Let f be an orientation preserving homeomorphism of the disc D2 which
possesses a periodic point of period 3. Then either f is isotopic, relative the
periodic orbit, to a homeomorphism g which is conjugate to a rotation by 2 pi
/3 or 4 pi /3, or f has a periodic point of least period n for each n in N*.Comment: 7 page
The 2003 eclipse of EE Cep is coming. A review of past eclipses
EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse
will occur soon, in May-June 2003, and all available past eclipses were
collected and briefly analysed. EE Cep shows very large changes of the shape
and the depth of minima during different eclipses, however it is possible to
single out some persistent features. The analysis suggests that the eclipsing
body should be a long object surrounded by an extended semi-transparent
envelope. As an explanation, a model of a precessing optically thick disc,
inclined to the plane of the binary orbit, is invoked. The changes of its
spatial orientation, which is defined by the inclination of the disc and the
tilt, induced most probably by precession of the disc spin axis with a period
of about 50 years, produce strange photometric behaviour of this star. The
H_alpha emission, and possibly the NaI absorptions, show significant changes
during several months outside of the eclipse phase.Comment: 7 pages, 7 figures, LaTeX2e, accepted by A&
Photoluminescence studies of selected styrylquinolinium thin films made using thermal evaporation deposition technique
In this paper we present a photoluminescence (PL) study of new styrylquinolinium dyes. We made a comparative study of the luminescent properties of thin films grown on quartz substrates using thermal evaporation deposition method. Investigated films show PL emission from the violet to near-IR region at room temperature
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Scaling Algebraic Multigrid Solvers: On the Road to Exascale
Algebraic Multigrid (AMG) solvers are an essential component of many large-scale scientific simulation codes. Their continued numerical scalability and efficient implementation is critical for preparing these codes for exascale. Our experiences on modern multi-core machines show that significant challenges must be addressed for AMG to perform well on such machines. We discuss our experiences and describe the techniques we have used to overcome scalability challenges for AMG on hybrid architectures in preparation for exascale
The geometry of a vorticity model equation
We provide rigorous evidence of the fact that the modified
Constantin-Lax-Majda equation modeling vortex and quasi-geostrophic dynamics
describes the geodesic flow on the subgroup of orientation-preserving
diffeomorphisms fixing one point, with respect to right-invariant metric
induced by the homogeneous Sobolev norm and show the local existence
of the geodesics in the extended group of diffeomorphisms of Sobolev class
with .Comment: 24 page
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FAK activity sustains intrinsic and acquired ovarian cancer resistance to platinum chemotherapy.
Gene copy number alterations, tumor cell stemness, and the development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stem phenotypes involving Wnt-β-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous gains in Kras, Myc and FAK (KMF) genes in a new aggressive murine model of ovarian cancer. Adhesion-independent FAK signaling sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neo-adjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance and triggered cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 targets, elevated in HGSOC, that were regulated by FAK activity and β-catenin including Myc, pluripotency and DNA repair genes. These studies reveal an oncogenic FAK signaling role supporting chemoresistance
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