Separating the Effect of Independent Interference Sources with Rayleigh Faded Signal Link: Outage Analysis and Applications

We show that, for independent interfering sources and a signal link with exponentially distributed received power, the total probability of outage can be decomposed as a simple expression of the outages from the individual interfering sources. We give a mathematical proof of this result, and discuss some immediate implications, showing how it results in important simplifications to statistical outage analysis. We also discuss its application to two active topics of study: spectrum sharing, and sum of interference powers (e.g., lognormal) analysis.Comment: Submitted to IEEE Wireless Communications Letter

CARET analysis of multithreaded programs

Dynamic Pushdown Networks (DPNs) are a natural model for multithreaded programs with (recursive) procedure calls and thread creation. On the other hand, CARET is a temporal logic that allows to write linear temporal formulas while taking into account the matching between calls and returns. We consider in this paper the model-checking problem of DPNs against CARET formulas. We show that this problem can be effectively solved by a reduction to the emptiness problem of B\"uchi Dynamic Pushdown Systems. We then show that CARET model checking is also decidable for DPNs communicating with locks. Our results can, in particular, be used for the detection of concurrent malware.Comment: Pre-proceedings paper presented at the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur, Belgium, 10-12 October 2017 (arXiv:1708.07854

ASCORBIC ACID AS A GROWTH ADJUVANT IN ENCAPSULATED PROTOCORM-LIKE-BODIES OF RHYNCHOSTYLIS RETUSA BL. (ORCHIDACEAE)

In the present study, effect of ascorbic acid, a known growth adjuvant on encapsulated protocorm-like-bodies (PLBs) of Rhynchostylis retusa Bl. was investigated. PLBs were encapsulated in calcium alginate (3.5% sodium alginate and 100mM calcium chloride) prepared in Mitra et al. (1976) basal medium and supplemented with different concentration of ascorbic acid (5, 10, 15, 20mM). The encapsulated PLBs were stored at 25°C. Their germination response and germination potential was evaluated after every 4 weeks on basal media. Control set of encapsulated PLBs, failed to germinate after 32 weeks. However, PLBs with 15mM ascorbic acid in the encapsulated matrix showed the best response; nearly 90% germinated even after 32 weeks of storage. The survival and germination frequency was directly proportional to the level of ascorbic acid in the alginate mix upto 15mM level but declined on further increase. Differentiation of PLBs into plantlet was better in synthetic seeds containing lower concentration of ascorbic acid (5mM) as compared to higher levels (15, 20mM) whereas multiplication of secondary PLBs was more pronounced at higher levels. Chlorophyll content was inversely proportional to the level of ascorbic acid in the nutrient mix; lush green PLBs were observed at low concentration of ascorbic acid (5mM). This study highlights the potential of ascorbic acid as an aid to growth and survival of encapsulated PLBs upon storage

Remodeling the Isoprenoid Pathway in Tobacco by Expressing the Cytoplasmic Mevalonate Pathway in Chloroplasts

Metabolic engineering to enhance production of isoprenoid metabolites for industrial and medical purposes is an important goal. The substrate for isoprenoid synthesis in plants is produced by the mevalonate pathway (MEV) in the cytosol and by the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway in plastids. A multi-gene approach was employed to insert the entire cytosolic MEV pathway into the tobacco chloroplast genome. Molecular analysis confirmed the site-specific insertion of seven transgenes and homoplasmy. Functionality was demonstrated by unimpeded growth on fosmidomycin, which specifically inhibits the MEP pathway. Transplastomic plants containing the MEV pathway genes accumulated higher levels of mevalonate, carotenoids, squalene, sterols, and triacyglycerols than control plants. This is the first time an entire eukaryotic pathway with six enzymes has been transplastomically expressed in plants. Thus, we have developed an important tool to redirect metabolic fluxes in the isoprenoid biosynthesis pathway and a viable multigene strategy for engineering metabolism in plants

Symbolic Partial-Order Execution for Testing Multi-Threaded Programs

We describe a technique for systematic testing of multi-threaded programs. We combine Quasi-Optimal Partial-Order Reduction, a state-of-the-art technique that tackles path explosion due to interleaving non-determinism, with symbolic execution to handle data non-determinism. Our technique iteratively and exhaustively finds all executions of the program. It represents program executions using partial orders and finds the next execution using an underlying unfolding semantics. We avoid the exploration of redundant program traces using cutoff events. We implemented our technique as an extension of KLEE and evaluated it on a set of large multi-threaded C programs. Our experiments found several previously undiscovered bugs and undefined behaviors in memcached and GNU sort, showing that the new method is capable of finding bugs in industrial-size benchmarks.Comment: Extended version of a paper presented at CAV'2

Sex Reversal in C57BL/6J XY Mice Caused by Increased Expression of Ovarian Genes and Insufficient Activation of the Testis Determining Pathway

Sex reversal can occur in XY humans with only a single functional WT1 or SF1 allele or a duplication of the chromosome region containing WNT4. In contrast, XY mice with only a single functional Wt1, Sf1, or Wnt4 allele, or mice that over-express Wnt4 from a transgene, reportedly are not sex-reversed. Because genetic background plays a critical role in testis differentiation, particularly in C57BL/6J (B6) mice, we tested the hypothesis that Wt1, Sf1, and Wnt4 are dosage sensitive in B6 XY mice. We found that reduced Wt1 or Sf1 dosage in B6 XYB6 mice impaired testis differentiation, but no ovarian tissue developed. If, however, a YAKR chromosome replaced the YB6 chromosome, these otherwise genetically identical B6 XY mice developed ovarian tissue. In contrast, reduced Wnt4 dosage increased the amount of testicular tissue present in Sf1+/− B6 XYAKR, Wt1+/− B6 XYAKR, B6 XYPOS, and B6 XYAKR fetuses. We propose that Wt1B6 and Sf1B6 are hypomorphic alleles of testis-determining pathway genes and that Wnt4B6 is a hypermorphic allele of an ovary-determining pathway gene. The latter hypothesis is supported by the finding that expression of Wnt4 and four other genes in the ovary-determining pathway are elevated in normal B6 XX E12.5 ovaries. We propose that B6 mice are sensitive to XY sex reversal, at least in part, because they carry Wt1B6 and/or Sf1B6 alleles that compromise testis differentiation and a Wnt4B6 allele that promotes ovary differentiation and thereby antagonizes testis differentiation. Addition of a “weak” Sry allele, such as the one on the YPOS chromosome, to the sensitized B6 background results in inappropriate development of ovarian tissue. We conclude that Wt1, Sf1, and Wnt4 are dosage-sensitive in mice, this dosage-sensitivity is genetic background-dependant, and the mouse strains described here are good models for the investigation of human dosage-sensitive XY sex reversal