A semi-parametric approach for mixture models: Application to local false discovery rate estimation

A procedure to estimate a two-component mixture model where one component is known is proposed. The unknown part is estimated with a weighted kernel function. The weights are defined in an adaptive way. The convergence to a unique solution of our estimation procedure is proven. The procedure is compared with two classical approaches using simulation. In addition, the results obtained are applied to multiple testing procedure in order to estimate the posterior population probabilities and the local false discovery rate.     

Role of adrenocorticotropic hormone in the development and maintenance of the adrenal cortical vasculature

The adrenal cortex is a highly vascularized endocrine tissue. A dense network of blood capillaries centripetally irrigates the adrenal gland, allowing every endocrine cell to be in contact with an endothelial cell. The pituitary hormone ACTH controls the coordinated development of the vasculature and the endocrine tissue mass. This suggests that paracrine secretions between steroidogenic adrenocytes and capillary endothelial cells participate in the control of adrenocortical homeostasis. Besides its effect on the vascular tone of arteries, ACTH induces the expression of the angiogenic cytokine VEGF-A (vascular endothelial growth factor-A) in primary cultures of adrenocortical cells. This growth factor is a specific mitogen for endothelial cells and is likely to mediate the hormonal control of adrenocortical vascularization through a paracrine mechanism. The newly discovered angiogenic factor EG-VEGF (endocrine-gland-derived vascular endothelial growth factor), the expression of which is restricted to endocrine glands and which is preferentially mitogenic for endocrine tissue-derived endothelial cells, is another candidate mediator of great potential interest.     

Spatial coherence in strongly scattering media

We study the spatial coherence of an optical beam in a strongly scattering medium confined in a slab geometry. Using the radiative transfer equation, we study numerically the behavior of the transverse spatial coherence length in the different transport regimes. Transitions from the ballistic to the diffusive regimes are clearly identified.     

Widely tunable continuous-wave mid-infrared radiation (5.5-11 microm) by difference-frequency generation in LiInS2 crystal

The first demonstration, to the best of our knowledge, of continuous-wave (cw) difference-frequency generation (DFG) in LiInS2 crystal is reported. Wide spectral coverage (5.5-11.3 microm) has been obtained with angle and wavelength tuning for type II (eoe) critically phase-matched parametric interaction. The phase-matching conditions in cw DFG have been investigated, which allowed us to improve the Sellmeier parameters by use of a two-pole dispersion equation. An effective nonlinear coefficient deff = 6.9 +/- 0.8 pm/V has been determined at approximately 7 microm relative to the well-known nonlinear coefficient d36 of AgGaS2, which yields a power-conversion efficiency of approximately 12.4 microW/(W2 cm). We evaluated the high-resolution spectral characteristics of the DFG source by recording C2H2 and SO2 spectra.     

Highly stable DNA triplexes formed with cationic phosphoramidate pyrimidine alpha-oligonucleotides

The ability of cationic phosphoramidate pyrimidine alpha-oligonucleotides (ONs) to form triplexes with DNA duplexes was investigated by UV melting experiments, circular dichroism spectroscopy and gel mobility shift experiments. Replacement of the phosphodiester linkages in alpha-ONs with positively charged phosphoramidate linkages results in more efficient triplex formation, the triplex stability increasing with the number of positive charges. At a neutral pH and in the absence of magnesium ions, it was found that a fully cationic phosphoramidate alpha-TFO (triplex-forming oligonucleotide) forms a highly stable triplex that melts at a higher temperature than the duplex target. No hysteresis between the annealing and melting curves was noticed; this indicates fast association. Moreover, the recognition of a DNA duplex with a cationic alpha-TFO through Hoogsteen base pairing is highly sequence-specific. To the best of our knowledge, this is the first report of stable triplexes in the pyrimidine motif formed by cationic alpha-oligonucleotides and duplex targets.     

Thermal expansion stress in a metallic matrix composite:in situ TEM observations

A metallic matrix composite material (2024-type aluminium alloy reinforced with 25 vol % SiC whiskers) wasin situ thermally cycled in a transmission electron microscope. Dislocation movements were observed between 180 and 400 °C. The local shear stress due to the difference between the thermal expansion coefficient of matrix and fibres is estimated from the radius of curvature of mobile dislocations. The experimental values of the internal stress are discussed.     

Low earth orbit satellite systems for communications

It may be that we are now entering the era of LEO constellation satellite communications after thirty years of domination by the GEO systems. This paper heralds the coming of the new era with a tutorial approach to the system design and trade-offs of LEO constellation system design. It discusses orbital configurations, network topologies and routeing considerations, multiple access schemes and link performance design. In so doing it brings out the major design parameters and how they interact with each other. Also considered are the service applications for the LEO constellation systems, and the important difference between real-time and delayed communication systems is highlighted. Examples of single and multi-beam (cellular) coverage system link designs are presented for L-K_a frequency bands. Future papers will consider aspects of the LEO spacecraft and launchers.     

comportement cathodique d'olefines activees reduction monoelectronique des (furyl-2)-3 propene nitriles

The electrochemical reduction of substituted 3-(2-furyl)-propenonitriles, in hydroorganic medium and on mercury pool, gives, with a yield of about 80%, a mixture of the dl-hydrodimer and the enamine (cis configuration). The latter results of the spontaneous in situ cyclisation of the meso-hydrodimer. The dl-hydrodimer is cyclised in a trans-enamine by the Thorpe—Ziegler reaction. A reactional scheme is proposed to expain this electrochemical stereoselection reaction.     

Propriétés diélectriques en basse fréquence de structures Al⧸Al2O3⧸Au en couches minces

The dielectric properties of thin film Al/Al₂O₃/Au structures were investigated in the frequency range 10^-2–10⁵ Hz and in the temperature range 393–505 K; the thicknesses of the Al₂O₃ films were between 23 and 100 nm. It was found that the d.c. and a.c. activation energies are approximately equal (0.76 eV).The results of the measurements suggest the superposition of two loss mechanisms, each obeying the empirical relation χ′(ω) ∝ χ″(ω) ∝ ω^n?1 in consistency with the Kramers-Kronig relations with n ? 0.14 in the low frequency range and n ? 0.88 at higher frequencies. At very low frequencies, χ′ tends towards a limit for the thinnest samples; this limit can be explained by the existence of a more insulating barrier region.     

Nature of contact between polymer and mold in injection molding. Part I: Influence of a non‐perfect thermal contact

In injection molding, the pressure in the cavity usually reaches the atmospheric pressure before the ejection, therefore the thermal contact between polymer and mold is modified. This paper aims to evaluate the nature of the thermal contact between the polymer and the mold during the holding and cooling phase. An experimental plate mold has been designed to study this phenomenon. Thermal sensors facing each other and pressure sensors have been set in the mold. An inverse method is used to determine the heat flux density crossing the polymer mold interface, and the mold surface temperature. Then, a second inverse algorithm allows to determine the temperature profile at the end of the filling and the time evolution of the thermal contact resistance (TCR). Finally, the polymer temperature distribution in the thickness is determined between the thermal sensors. The results of this study show that the TCR between the polymer and the mold is not negligible and not constant with time. The polymer temperature at the surface can be 20°C higher than the mold surface temperature. Moreover, asymmetric air gaps have been observed when cavity pressure becomes equal to atmospheric pressure, therefore asymmetric temperature profile in the thickness are generated.