First-Passage Time and Large-Deviation Analysis for Erasure Channels with Memory

This article considers the performance of digital communication systems transmitting messages over finite-state erasure channels with memory. Information bits are protected from channel erasures using error-correcting codes; successful receptions of codewords are acknowledged at the source through instantaneous feedback. The primary focus of this research is on delay-sensitive applications, codes with finite block lengths and, necessarily, non-vanishing probabilities of decoding failure. The contribution of this article is twofold. A methodology to compute the distribution of the time required to empty a buffer is introduced. Based on this distribution, the mean hitting time to an empty queue and delay-violation probabilities for specific thresholds can be computed explicitly. The proposed techniques apply to situations where the transmit buffer contains a predetermined number of information bits at the onset of the data transfer. Furthermore, as additional performance criteria, large deviation principles are obtained for the empirical mean service time and the average packet-transmission time associated with the communication process. This rigorous framework yields a pragmatic methodology to select code rate and block length for the communication unit as functions of the service requirements. Examples motivated by practical systems are provided to further illustrate the applicability of these techniques.Comment: To appear in IEEE Transactions on Information Theor

Wire tomography in the H-1NF heliac for investigation of fine structure of magnetic islands

Electron beam wire tomography in the H-1NF heliac enables high resolution mapping of vacuum flux surfaces with minimal disruption of the plasma operations schedule. Recent experimental results have proven this technique to be a highly accurate and high resolution method for mapping vacuum magnetic islands. Islands of width as small as delta approximately 8 mm have been measured, providing estimates of the internal rotational transform of the island. Point-to-point comparison of the mapping results with computer tracing, in conjunction with an image warping technique, enables systematic exploration of magnetic islands and surfaces of interest. Recent development of a fast mapping technique significantly reduced the mapping time and made this technique suitable for mapping at higher magnetic fields. This article presents recent experimental results and associated techniques.with support from the Australian Research Council Grant No. DP0344361

Optical Interferometric Properties of Iridescent Nanoporous Anodic Alumina

AbstractHighly ordered nanoporous anodic alumina (NAA) membranes with varying pore properties were fabricated using two step electrochemical oxidation of aluminum. A study on optical reflective interferometric properties of NAA was conducted. The influence of pore properties including pore diameters, interpore distance and pore lengths on the reflection spectra was explored. Variation of reflection intensities with different angles of incidence showed the iridescence of NAA membranes. Such NAA nanostructures are promising for the use as substrates for various biomedical sensing applications

Observations on the Aging Environment Dependent NO Oxidation Activity of Model Pt/Al2O3 Diesel Oxidation Catalyst

The influence of aging environment of model diesel oxidation catalyst Pt/Al2O3 on the NO oxidation activity is studied. The fresh catalyst Pt/Al/F (calcined in air at 500°C) is aged with or without phosphorus (P) poisoning (7.5wt%) at 800°C either in air (P/Pt/Al/O or Pt/Al/O) or in simulated diesel exhaust (P/Pt/Al/R or Pt/Al/R). Catalyst aged under diesel exhaust environment (Pt/Al/R) surprisingly presents the best NO oxidation activity under excess of O2 followed by the fresh (Pt/Al/F) and thermally aged (Pt/Al/O) catalysts. The activity difference between the catalysts is quite large, especially between Pt/Al/R and Pt/Al/O that are aged at the same temperatures but under different environments suggesting the importance of the aging environment for the catalytic activity. The NO oxidation activity of P poisoned catalysts P/Pt/Al/R and P/Pt/Al/O is minute as compared to their P free counter parts indicating that chemical aging is more detrimental for catalytic efficiency than thermal agin

Role of isoflavones and its derivatives on the growth of Pseudomonas putida and Escherichia coli

Two naturally occurring isoflavones genistine and biochanin - A, and their dihydro derivatives (isoflavones) as well as nine perhydroginated isoflavones (isoflavanes) were tested for their effects on mycelial growth of two soil bacteria viz., Pseudomonas putida and Escherichia coli. All the isoflavonenoids of the biochanin - A series showed the genistine isoflavane and the other isoflavanes with two hydroxyl groups and one methoxy groups are toxic, while isoflavones with two and one methoxy group were almost inactive. Genistein, a radio protective soy isoflavone and protein kinase inhibitor, blocks the invasion of pathogenic bacteria in mammalian epithelial cells. The purpose of this study was to evaluate the direct effect of genistein on the survival and growth of the probiotic Lactobacillus reuteri and selected opportunistic bacteria in vitro as a prelude to in vivo use for managing post irradiation sepsis. The opportunistic bacterial enteropathogens viz., Escherichia coli, Shigella sonnei, and Staphylococcus aureus as well as Klebsiella pneumoniae and the non-pathogenic organism, Bacillus anthracis (Sterne) were evaluated. The latter two bacteria are found in the environment and may be of concern in irradiated individuals. A standard in vitro test was employed to evaluate the direct effect of genistein on the bacteria

Effect of different levels and sources of calcium on post harvest physiology of hybrid tomatoes (Solanum lycopersicum)

Due to high respiration and ethylene production, tomato (Solanum lycopersicum) is highly perishable horticulture produce that deteriorates faster during the post-harvest storage period. Calcium nutrition is important to overcome these losses as it helps in retarding ripening process during storage and improve the post-harvest quality tomatoes. Hence a field experiment was conducted with different calcium sources and levels viz., Calcium sulphate, Calcium Nitrate, Calcium silicate, Poultry manure and Pressmud applied at 0, 20, 40, 60 and 80 kg Ca ha-1. A storage study was conducted in a factorial completely randomized block design (FCRD) to ensure the effective role of calcium in post-harvest quality of hybrid tomato. Tomatoes were analyzed for pH of fruit juice, firmness, titratable acidity, total soluble solids, moisture content and physiological loss at five days intervals upto 15 days. The results revealed thatCalcium sources and levels had highly significant impacts on the quality of tomato fruits. The tomatoes harvested from the plot applied with poultry manure at 80 kg Ca ha-1 retained the highest fruit firmness(3.76 N m-1), moisture content (88.2%) and the lowest weight loss (8.82%) in fruit, highertitratable acidity (0.41%), lesser pH (3.61)andtotal soluble solids (4.23 ˚Brix). Hence the application of poultry manure at 80 kg Ca ha-1was beneficial in improving the quality and extending the storage life of hybrid tomatoes