Planar signaling

Planar Signals in the Context of Prospective Neural and Epidermal Interactions... 

The sandwich explants described above consist of the dorsal 90-120° of the embryo, which includes little or none of the prospective epidermal ectoderm. Thus, in these explants, planar signals from the Organizer act on the prospective neural tissue in the absence of any influences from the prospective epidermis. Since there is evidence that epidermal-neural interactions pattern the neural tissue and regulate its morphogenesis (57-61), we have developed several types of explants that allow planar signals from the Organizer to act in the context of also having planar neural-epidermal interactions. 

Sater, A. K., Steinhardt R. A., and Keller R. (1993) Induction of neuronal differentiation by planar signals in Xenopus embryos. Devel. Dynam. 197,268-280. 

Papalopulu, N. and Kintner, C. (1993) Zenopi/s Distal-less related homeobox genes are expressed in the developing forebrain and are induced by planar signals. Development 117,961-975. 

Note Conversely, it is important to emphasize that a lack of phase inversion between the signals of two superimposed echoes along the depth axis is not necessarily an evidence that the defect is volumetric (diffraction effect on a planar defect could miss if the geometry of the tips are not favorable). 

Using Equ. (3.1), we can now compute the optimum frequency for cracks in various depths (see Fig. 3.2). For comparison, the optimum excitation frequency for a planar wave or a sheet inducer (300 x 160 mm) is also displayed. One finds that for a planar excitation source, a much lower excitation frequency is required, which causes a reducfion in the response signal of the crack of up to an order of magnitude in case of a small circular coil. 

As stated above the SQUID amplifier demands a low inductance Eddy current probe in order to be able to amplify signals up to 1 MHz. Low inductance Eddy current probes can be obtained by reducing the number of turns and by loosing the magnetic coupling between the tums. So magnetic cores should be avoided as well as tight wounded tums. For this purpose planar coils are the best... 

The Champ-Sons model is a most effieient tool allowing quantitative predictions of the field radiated by arbitrary transducers and possibly complex interfaces. It allows one to easily define the complete set of transducer characteristics (shape of the piezoelectric element, planar or focused lens, contact or immersion, single or multi-element), the excitation pulse (possibly an experimentally measured signal), to define the characteristics of the testing configuration (geometry of the piece, transducer position relatively to the piece, characteristics of both the coupling medium and the piece), and finally to define the calculation to run (field-points position, acoustical quantity considered). 

Figure 8.3. Wave interactions in planar tensile fracture experiment, (a) Shows the distance-time plot of interacting compression C , rarefaction R , and tension T , waves (b) Shows the corresponding particle-velocity profiles including the initial compressive shock wave (tj, tj), the pull-back signal (tj, tj), and subsequent reflection >h).

Wnt/non-P-catenin signaling is not as well characterized biochemically as the Wnt/p-catenin-dependent pathway this may reflect that it is molecularly more diverse, at least in vertebrates. In Drosophila the best characterized Wnt/non-P-catenin pathway is planar cell polarity (PCP) signaling. Ironically, although it certainly depends on a Fz receptor, it remains... 

The carbonate can also be compared with adsorbed formate species prepared by reacting methanol with the alumina surface at 350 C ( ). The spectrum for adsorbed formate. Figure 4d, shows the asymmetric carboxylate stretches at 1565 and 1440 cm l respectively, the CH stretch at 2832 cm , and the CH bending mode at 1505 cm . The Al-OC stretching mode is seen at 1060 cm", and the out-of-plane deformation at 750 cm . The signal to noise ratio in the low frequency end of the spectrum is insufficient to see the planar deformation, which should occur around 630 cm . It should be noted that the carbonate and formate species are very similar, the main distinction being the vibrations associated with the CH bond. 

NCS-carbon is shifted dowfield in the two first complexes. The amine complex shows a shift of the N—H signal which appears at 2.08 ppm in the free ligand and at 5.17 ppm when it is coordinated. The structure of the thiazole complex was studied by X-ray diffraction, confirming the almost linear coordination about the gold atom and showing that the ligands are almost co-planar. 

---