Lyapunov functions for a non-linear model of the X-ray bursting of the microquasar GRS 1915+105

This paper introduces a biparametric family of Lyapunov functions for a non-linear mathematical model based on the FitzHugh-Nagumo equations able to reproduce some main features of the X-ray bursting behaviour exhibited by the microquasar GRS 1915+105. These functions are useful to investigate the properties of equilibrium points and allow us to demonstrate a theorem on the global stability. The transition between bursting and stable behaviour is also analyzed.Comment: Published on International Journal of Non-Linear Mechanics, vol. 88, pp. 142-14

Investigation of element-specific and bulk magnetism, electronic and crystal structures of La{0.70}Ca{0.30}Mn{1-x}Cr{x}O{3}

The magnetic interactions in La{0.70}Ca{0.30}Mn{1-x}Cr{x}O{3} (x = 0.15, 0.50 and 0.70) are investigated by x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), high-resolution x-ray powder diffraction, and bulk magnetization measurements. XAS in the Mn and Cr L{2,3} edges support stable single valent Cr{3+} ions and a varying Mn valence state with x, while the O K edge XAS spectrum reveals local maxima in the O 2p density of states close to the Fermi level due to mixing with Mn and Cr 3d states. A robust antiferromagnetic state is found for x=0.70 below TN = 258 K. For x=0.15, combined XMCD and bulk magnetization measurements indicate a fully polarized ferrimagnetic state for the Mn and Cr spins below Tc=224 K. For x=0.50, a reduced ferrimagnetic component dominated by Mn spins is present below Tc=154 K. No evidence of lattice anomalies due to cooperative charge and orbital orderings is found by x-ray diffraction for all samples. The magnetic properties of this system are rationalized in terms of a competition of ferromagnetic Mn-Mn double exchange and antiferromagnetic Cr-Cr and Cr-Mn superexchange interactions.Comment: 25 pages, 9 figure

On Cancer Cell Cycle and Universal Apoptosis Parameters Signaling Unravelled In Silico

Here, cell cycle in higher eukaryotes and their molecular networks signals both in G1/S and G2/M transitions are in silico replicated. Systems control theory is employed to design multi-nestled digital layers to simulate protein-toprotein activation and inhibition in the cancer cell cycle dynamics in presence of damaged genome. Sequencing and controlling the digital process of four micro-scale species networks (p53/Mdm2/DNA damage; p21mRNA/cyclin-CDK complex; CDK/CDC25/wee1/SKP2/APC/CKI and apoptosis target genes system) paved the way for unravelling the participants and their by-products having the task to execute (or not) cell death. The results of the proposed cell digital multi-layers give reason to believe in the existence of an universal apoptotic mechanism. We identified and selected cell checkpoints, sizers, timers and specific target genes dynamics both for influencing mitotic process and avoiding cancer proliferation as much as for leading the cancer cell(s) to collapse into a steady stable apoptosis phase

Possibility of repeat surgery for recurrence following two-stage hepatectomy for colorectal liver metastases: impact on patient outcome

No abstract availabl

Spin-Electron-Phonon Excitation in Re-based Half-Metallic Double Perovskites

A remarkable hardening (~ 30 cm-1) of the normal mode of vibration associated with the symmetric stretching of the oxygen octahedra for the Ba2FeReO6 and Sr2CrReO6 double perovskites is observed below the corresponding magnetic ordering temperatures. The very large magnitude of this effect and its absence for the anti-symmetric stretching mode provide evidence against a conventional spin-phonon coupling mechanism. Our observations are consistent with a collective excitation formed by the combination of the vibrational mode with oscillations of local Fe or Cr 3d and Re 5d occupations and spin magnitudes.Comment: 12 pages, 4 figure

Multiphysics analyses of the effect of package on the performances of PMUT transducers

The paper deals with the multiphysics modeling of piezoelectric micromachined ultrasound transducers (PMUT), that can be used in several practical applications. The model accounts for the multiple couplings between the mechanical fields and the electric and acoustic ones. The numerical solution has been sought by means of the finite element method, for the special case of axial symmetry. The model has been validated with reference to experimental data, that have been obtained by the Authors. The numerical procedure has been applied to carry out a parametric analysis of the effect of package, to extract a set of design guidelines

Real-time cell analysis by xCELLigence®: a new method for dynamic, quantitative measurement of adhesion and proliferation of cell lines

Objectives. In this study, we report the use of a real-time cell analysis (RTCA) test system, the xCELLigence® RTCA, as efficient tool for a fast growth kinetics analysis of cell lines. This new dynamic real-time monitoring and impedance-based assay allows for a combined measurement of cell adhesion, spreading and proliferation. Methods. We used four representative human OSCC derived cell lines, PE49, HSC2, HSC3 and PE15 cells. The measured impedance values could be correlated to characteristic cell culture behaviours. In parallel, were evaluated proliferation and cell viability of the cell lines by the 3-[4,5-dimethylthizol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Results. Through the analysis we were able to quantitatively characterize the growth kinetics of the cell lines. The results are in agreement with the analysis MTT and for us will be the basis for future studies with respect to these lines.Conclusions. The advantage of impedance-based measurements is mainly based on these continuous monitoring of cell responses for a broad range of different cells and with different parameters of culture. Therefore, the xCELLigence system can be used as a rapid monitoring tool for cellular viability and used for multiple applications, such as toxicity testing of xenobiotics, biocompatibility of dental materials, tests of invasion and migration using in vitro cell cultures