Field-induced axion emission via process e+e−→ae^+ e^- \to a in plasma

The annihilation into axion $e^+ e^- \to a$ is investigated in a plasma and an external magnetic field. This process via a plasmon intermediate state has a resonant character at a particular energy of the emitted axion. The emissivity by $e^+ e^- \to a$ is compared with the axion cyclotron emissivity.Comment: 8 pages, latex, 4 PS figure

FGF-1 and FGF-2 modulate the E-cadherin/catenin system in pancreatic adenocarcinoma cell lines

Fibroblast growth factors (FGFs) and fibroblast growth factor receptors (FGFRs) have been increasingly recognized to play an important role in the pathobiology of pancreatic malignancy. We have investigated the effects of FGF-1 and FGF-2 on the behaviour and adhesion properties of human pancreatic adenocarcinoma cell lines (BxPc3, T3M4 and HPAF) that were previously characterised for the expression of FGFRs. Here we show that exposure to FGF-1 and FGF-2 leads to significant and dose-dependent increase in E-cadherin-dependent cell-cell adhesion, tubular differentiation, and a reduced capacity to invade collagen gels. FGF stimulation produces phosphorylation of E-cadherin and β-catenin on tyrosine residues, as well as increased E-cadherin localisation to the cytoplasmic membrane and association with FGFR1 demonstrable by coimmunoprecipitation. These results demonstrate that FGF-1 and FGF-2 may be involved in the regulation of cell adhesion, differentiation and invasion of pancreatic cancer. © Cancer Research Campaign http://www.bjcancer.co

Optimisation of conditions for detection of activated oncogenes by transfection of NIH 3T3 cells.

Optimisation of conditions for detection of activated oncogenes by transfection of NIH 3T3 cells

Sticky islands in stochastic webs and anomalous chaotic cross-field particle transport by ExB electron drift instability

The ExB electron drift instability, present in many plasma devices, is an important agent in cross-field particle transport. In presence of a resulting low frequency electrostatic wave, the motion of a charged particle becomes chaotic and generates a stochastic web in phase space. We define a scaling exponent to characterise transport in phase space and we show that the transport is anomalous, of super-diffusive type. Given the values of the model parameters, the trajectories stick to different kinds of islands in phase space, and their different sticking time power-law statistics generate successive regimes of the super-diffusive transport.Comment: This manuscript contains 13 Pages and 21 figure

Design Considerations for a Dedicated Gravity Recovery Satellite Mission Consisting of Two Pairs of Satellites

Future satellite missions dedicated to measuring time-variable gravity will need to address the concern of temporal aliasing errors; i.e., errors due to high-frequency mass variations. These errors have been shown to be a limiting error source for future missions with improved sensors. One method of reducing them is to fly multiple satellite pairs, thus increasing the sampling frequency of the mission. While one could imagine a system architecture consisting of dozens of satellite pairs, this paper explores the more economically feasible option of optimizing the orbits of two pairs of satellites. While the search space for this problem is infinite by nature, steps have been made to reduce it via proper assumptions regarding some parameters and a large number of numerical simulations exploring appropriate ranges for other parameters. A search space originally consisting of 15 variables is reduced to two variables with the utmost impact on mission performance: the repeat period of both pairs of satellites (shown to be near-optimal when they are equal to each other), as well as the inclination of one of the satellite pairs (the other pair is assumed to be in a polar orbit). To arrive at this conclusion, we assume circular orbits, repeat groundtracks for both pairs of satellites, a 100-km inter-satellite separation distance, and a minimum allowable operational satellite altitude of 290 km based on a projected 10-year mission lifetime. Given the scientific objectives of determining time-variable hydrology, ice mass variations, and ocean bottom pressure signals with higher spatial resolution, we find that an optimal architecture consists of a polar pair of satellites coupled with a pair inclined at 72deg, both in 13-day repeating orbits. This architecture provides a 67% reduction in error over one pair of satellites, in addition to reducing the longitudinal striping to such a level that minimal post-processing is required, permitting a substantial increase in the spatial resolution of the gravity field products. It should be emphasized that given different sets of scientific objectives for the mission, or a different minimum allowable satellite altitude, different architectures might be selected

Experimental and theoretical study of bumped characteristics obtained with cylindrical Langmuir probe in magnetized Helium plasma

Cylindrical Langmuir probe measurements in a Helium plasma were performed and analysed in the presence of a magnetic field. The plasma is generated in the ALINE device, a cylindrical vessel 1 m long and 30 cm in diameter using a direct coupled RF antenna (ν RF = 25 MHz). The density and temperature are of the order of 10 16 m −3 and 1.5 eV, respectively, for 1.2 Pa Helium pressure and 200 W RF power. The axial magnetic field can be set from 0 up to 0.1 T, and the plasma diagnostic is a RF compensated Langmuir probe, which can be tilted with respect to the magnetic field lines. In the presence of a magnetic field, I(V) characteristics look like asymmetrical double probe ones (tanh-shape), which is due to the trapping of charged particles inside a flux tube connected to the probe on one side and to the wall on the other side. At low tilting angle, high magnetic field amplitude, power magnitude and low He pressure, which are the parameters scanned in our study, a bump can appear on the I(V) in the plasma potential range. We then compare different models for deducing plasma parameters from such unusual bumped curves. Finally, using a fluid model, the bump rising on the characteristics can be explained, assuming a density depletion in the flux tube, and emphasizing the role of the perpendicular transport of ions

Structure and expression of nuclear oncogenes in multi-stage thyroid tumorigenesis.

We have investigated the possibility that structural alterations of the 'nuclear' oncogene family (c-myc, N-myc, L-myc, fos, myb and p53) leading to aberrant expression might, as in several other tumour types, play a role in the multi-stage development of tumorigenesis in the human thyroid follicular cell. Direct analysis of expression by slot and Northern blot RNA hybridisation showed that normal thyroid expresses surprisingly high levels of fos, and to a lesser extent c-myc, c-myc expression was markedly increased in all tumours, both benign and malignant, but no increase was seen in any other nuclear oncogene. fos expression was reduced specifically in one type of malignant tumour-follicular carcinoma-in inverse correlation with differentiation. Southern blot analysis showed no evidence of rearrangement or amplification of c-myc, or of any other 'nuclear' oncogene in any thyroid tumour. We conclude that there is no evidence that a primary abnormality of these genes plays a role in thyroid follicular cell tumorigenesis and suggest that the observed changes in expression can be adequately explained as secondary consequences of the tumour phenotype