Deterministic Constructions for Large Girth Protograph LDPC Codes

The bit-error threshold of the standard ensemble of Low Density Parity Check (LDPC) codes is known to be close to capacity, if there is a non-zero fraction of degree-two bit nodes. However, the degree-two bit nodes preclude the possibility of a block-error threshold. Interestingly, LDPC codes constructed using protographs allow the possibility of having both degree-two bit nodes and a block-error threshold. In this paper, we analyze density evolution for protograph LDPC codes over the binary erasure channel and show that their bit-error probability decreases double exponentially with the number of iterations when the erasure probability is below the bit-error threshold and long chain of degree-two variable nodes are avoided in the protograph. We present deterministic constructions of such protograph LDPC codes with girth logarithmic in blocklength, resulting in an exponential fall in bit-error probability below the threshold. We provide optimized protographs, whose block-error thresholds are better than that of the standard ensemble with minimum bit-node degree three. These protograph LDPC codes are theoretically of great interest, and have applications, for instance, in coding with strong secrecy over wiretap channels.Comment: 5 pages, 2 figures; To appear in ISIT 2013; Minor changes in presentatio

Effect of Haemoglobin and Iron Status of the Antenatal Mothers on their Newborns at Birth: A Cross-sectional Study

Introduction: Iron deficiency (ID) anaemia in pregnant mothers can affect the iron reserves of their newborns and lead to anaemia later. The haematological indices and iron status of pregnant women and its correlation with their neonates is still unclear. Aim: To assess the correlation between maternal and cord blood Hb and iron status. Materials and Methods: The present cross-sectional study included 134 antenatal mothers, at term gestation without any significant antenatal complications. Complete haemogram, serum iron, ferritin, and iron binding capacity were assessed for these mothers before delivery and also from the cord blood samples of their newborns at birth. Statistical difference and correlation were observed using Chi-square test and Pearson’s correlation coefficient. Results: Maternal anaemia Hb <11 gm/dL) was observed in 62 (46.3%). The mean Hb and ferritin of the mothers were 11.06±1.02 gm/dL and 113.3±7.1 μg/L, respectively. The mean Hb and ferritin levels of the cord blood samples were 12.24±0.17 gm/dL and 214.3±20.1 μg/L, respectively. In univariate analysis, maternal Hb showed a significant correlation with cord blood Hb with Odds Ratio (OR) 0.508 and 95% Confidence Interval (CI): 0.428-0.603. The Pearson’s correlation showed a moderate correlation between mother and cord blood Packed Cell Volume (PCV) (r=0.344, p<0.001) and weak correlation between other maternal and cord blood iron indices and serum ferritin (r=0.191, p=0.027 and r=0.203, p=0.019). Conclusion: There is a significant correlation between maternal and cord blood Hb in term neonates. The study indicates that the haematological indices of pregnant women determine the neonatal Hb in term babies

Nanosafety

The nanomaterials resembling nanotubes, nanospheres, nanofertilizer, nanoherbicide, nanoinsecticide, and nanosheets have the physical, chemical, biological, mechanical, electrical and thermal properties. Still, the nanoparticles have very minute dimensions, enormous area and high reactivity they need the potential ability to penetrate in living cells quite rapidly. The petite size nanoparticles contain lofty surface area may cause higher reactivity with nearby particles. It is broadly predictable that there is a critical need for more information and facts about the implications of manufactured nanomaterials on personal fitness and surroundings. Concerns about potential risks to health that may arise during the making, management, use, and discarding of these nanomaterials have been spoken over the past few years. Consequently, strong research action is being undertaken in various institutions, and industries across the world to appraise their toxicity and spread of nanoparticle

Large duodenal GIST with massive liver secondaries melting under Imatinib: a case report

Gastrointestinal stromal tumors(GIST) have become a well established entity and its taxonomy is no more ambiguous. Better understanding of the cell of origin and immunohistochmical markers have made this possible. Their treatment has been revolutionized with the advent of targeted molecular therapy, namely Imatinib mesylate. Herein we report a rare and interesting case of a thirty year old South Indian Lady with an extremely large Duodenal GIST with massive Liver secondaries. The phenomenon of metastatic GIST responding to Imatinib mesylate is not new. What is interesting in this case is the enormous tumor load at the time of presentation as exemplified by the cross sectional images. This kind of tumor response and patient survival deserves documentatio

Neuroprotective potential of Marsilea quadrifolia Linn against monosodium glutamate-induced excitotoxicity in rats

Background: Excitotoxicity is a condition in which neurons are damaged/injured by the over-activation of glutamate receptors. Excitotoxins play a crucial part in the progression of several neurological diseases. Marsilea quadrifolia Linn (M. quadrifolia) is a very popular aquatic medicinal plant that has been utilised for a variety of therapeutic benefits since ancient times. Its chemical composition is diverse and includes phenolic compounds, tannins, saponins, flavonoids, steroids, terpenoids, alkaloids, carbohydrates and several others that possess antioxidant properties.Objective: The objective of the present study was to investigate the neuroprotective potential of M. quadrifolia against monosodium glutamate (MSG)-induced excitotoxicity in rats.Methods: A high-performance thin-layer chromatography (HPTLC) analysis of chloroform extract of M. quadrifolia (CEMQ) was conducted to identify the major constituents. Further, the in silico docking analysis was carried out on selected ligands. To confirm CEMQ’s neuroprotective effects, the locomotor activity, non-spatial memory, and learning were assessed.Results and discussion: The present study confirmed that CMEQ contains quercetin and its derivatives in large. The in-silico findings indicated that quercetin has a better binding affinity (−7.9 kcal/mol) towards the protein target 5EWJ. Animals treated with MSG had 1) a greater reduction in the locomotor score and impairment in memory and learning 2) a greater increase in the blood levels of calcium and sodium and 3) neuronal disorganization, along with cerebral edema and neuronal degeneration in the brain tissues as compared to normal control animals. The changes were however, significantly improved in animals which received standard drug memantine (20 mg/kg) and CEMQ (200 and 400 mg/kg) as compared to the negative control. It is plausible that the changes seen with CEMQ may be attributed to the N-methyl-D-aspartate (NMDA) antagonistic properties.Conclusion: Overall, this study indicated that M. quadrifolia ameliorated MSG-induced neurotoxicity. Future investigations are required to explore the neuroprotective mechanism of M. quadrifolia and its active constituents, which will provide exciting insights in the therapeutic management of neurological disorders

Coding techniques for information-theoretic strong secrecy on wiretap channels

Traditional solutions to information security in communication systems act in the application layer and are oblivious to the effects in the physical layer. Physical-layer security methods, of which information-theoretic security is a special case, try to extract security from the random effects in the physical layer. In information-theoretic security, there are two asymptotic notions of secrecy---weak and strong secrecy This dissertation investigates the problem of information-theoretic strong secrecy on the binary erasure wiretap channel (BEWC) with a specific focus on designing practical codes. The codes designed in this work are based on analysis and techniques from error-correcting codes. In particular, the dual codes of certain low-density parity-check (LDPC) codes are shown to achieve strong secrecy in a coset coding scheme. First, we analyze the asymptotic block-error rate of short-cycle-free LDPC codes when they are transmitted over a binary erasure channel (BEC) and decoded using the belief propagation (BP) decoder. Under certain conditions, we show that the asymptotic block-error rate falls according to an inverse square law in block length, which is shown to be a sufficient condition for the dual codes to achieve strong secrecy. Next, we construct large-girth LDPC codes using algorithms from graph theory and show that the asymptotic bit-error rate of these codes follow a sub-exponential decay as the block length increases, which is a sufficient condition for strong secrecy. The secrecy rates achieved by the duals of large-girth LDPC codes are shown to be an improvement over that of the duals of short-cycle-free LDPC codes.PhDCommittee Chair: McLaughlin, Steven; Committee Member: Boldyreva, Alexandra; Committee Member: Coyle, Edward; Committee Member: Fekri, Faramarz; Committee Member: Ma, Xiaol