Sfrp3 modulates stromal-epithelial crosstalk during mammary gland development by regulating Wnt levels

Mammary stroma is essential for epithelial morphogenesis and development. Indeed, postnatal mammary gland (MG) development is controlled locally by the repetitive and bi-directional cross-talk between the epithelial and the stromal compartment. However, the signalling pathways involved in stromal–epithelial communication are not entirely understood. Here, we identify Sfrp3 as a mediator of the stromal–epithelial communication that is required for normal mouse MG development. Using Drosophila wing imaginal disc, we demonstrate that Sfrp3 functions as an extracellular transporter of Wnts that facilitates their diffusion, and thus, their levels in the boundaries of different compartments. Indeed, loss of Sfrp3 in mice leads to an increase of ductal invasion and branching mirroring an early pregnancy state. Finally, we observe that loss of Sfrp3 predisposes for invasive breast cancer. Altogether, our study shows that Sfrp3 controls MG morphogenesis by modulating the stromal-epithelial cross-talk during pubertal development

Built-in test for circuits with scan based on reseeding of multiple-polynomial linear feedback shift registers

In this paper, we propose a new scheme for Built-In Test (BIT) that uses Multiple-polynomial Linear Feedback Shift Registers (MP-LFSR's). The same MP-LFSR that generates random patterns to cover easy to test faults is loaded with seeds to generate deterministic vectors for difficult to test faults. The seeds are obtained by solving systems of linear equations involving the seed variables for the positions where the test cubes have specified values. We demonstrate that MP-LFSR's produce sequences with significantly reduced probability of linear dependence compared to single polynomial LFSR's. We present a general method to determine the probability of encoding as a function of the number of specified bits in the test cube, the length of the LFSR and the number of polynomials. Theoretical analysis and experiments show that the probability of encoding a test cube with s specified bits in an s-stage LFSR with 16 polynomials is 1–10^{-6}. We then present the new BIT scheme that allows for an efficient encoding of the entire test set. Here the seeds are grouped according to the polynomial they use and an implicit polynomial identification reduces the number of extra bits per seed to one bit. The paper also shows methods of processing the entire test set consisting of test cubes with varied number of specified bits. Experimental results show the tradeoffs between test data storage and test application time while maintaining complete fault coverage.Index Terms—Built-In Test, hardware test pattern generators, input test data compression and decompression, multiple-polynomial LFSR, reseeding, scan design

Generation of vector patterns through reseeding of multiple-polynomial linear feedback shift registers

A comparative analysis of the encoding efficiency of built-in-self-test (BIST) schemes based on reseeding of single polynomial linear fedback shift registers (LFSRs) as well as LFSRs with fully programmable polynomials is performed. Full programmability gives much better encoding efficiency. For a testcube with s carebits only s + 4 bits are required, in contrast to s + 19 bits for reseeding of single polynomials. A new BIST scheme is proposed in which the generator can operate according to a number of primitive polynomials. The testcubes are encoded as the polynomial identifier and a seed. Models of the encoding efficiency of this scheme are presented, and it is demonstrated, both theoretically and through extensive simulations, that such a scheme with 16 polynomials approaches the efficiency of the scheme based on full polynomial programmability, essentially preserving the computational simplicity of single reseeding