Implicit Coordination in Two-Agent Team Problems; Application to Distributed Power Allocation

The central result of this paper is the analysis of an optimization problem which allows one to assess the limiting performance of a team of two agents who coordinate their actions. One agent is fully informed about the past and future realizations of a random state which affects the common payoff of the agents whereas the other agent has no knowledge about the state. The informed agent can exchange his knowledge with the other agent only through his actions. This result is applied to the problem of distributed power allocation in a two-transmitter $M-$band interference channel, $M\geq 1$, in which the transmitters (who are the agents) want to maximize the sum-rate under the single-user decoding assumption at the two receivers; in such a new setting, the random state is given by the global channel state and the sequence of power vectors used by the informed transmitter is a code which conveys information about the channel to the other transmitter.Comment: 6 pages, appears as WNC3 2014: International Workshop on Wireless Networks: Communication, Cooperation and Competition - International Workshop on Resource Allocation, Cooperation and Competition in Wireless Network

Radiation Survivability of Micro-SD Cards in a Simulated Exposure to Prolonged Low Earth Orbit Space Environments

The harsh space environment can cause detrimental effects on high-density electronics such as micro-SD memory cards. High-energy electrons and ionizing radiation can induce common critical failure modes for satellites, particularly for small satellites with low shielding that often use less radiation-hardened Commercial-Off-The-Shelf (COTS) components. The objective of this research is to observe the impact of radiation on three different types of micro-SD cards in simulated Low Earth Orbit (LEO) space conditions. Radiation survivability was tested in the Space Survivability Test (SST) chamber at Utah State University that uses a ~90 mCi Sr90 source emitting broadband 0.2 to 2.5 MeV penetrating β radiation. Tests were conducted on about a dozen of micro-SD cards at a dose rate of ~2.5 Gy/hr for a period of up to ~400 hr for a cumulative Total Ionizing Dose (TID) of ~1000 Gy or ~50 times a typical annual dose (~20 Gy/yr) received for a typical CubeSat in LEO. The memory capacities of the micro-SD cards ranged from 4 GB to 32 GB with, low- and high-grade commercial multi-level cell (MLC) flash memory and industrial grade single-level cell (SLC) flash memory. Preliminary radiation tests at this facility reported memory failures occurrence at \u3c 340 Gy for the low-grade SD cards. Pre-radiation tests were performed on all micro-SD cards that included- (1) formatting with a FAT32 file system by SD Memory Card Formatter 5.0.1, (2) performing Quick Size Test (to check and report the true capacity of SD cards) and Empty Space Test (to write test files to any remaining free space on the SD cards) using FakeFlash Test 1.1.1, and (3) measuring Sequential and Random Read/Write speeds with Crystal Disk Mark software. At the end of full TID exposure, recovery tests were also performed on the damaged SD cards to check if the recovery was possible. Presentation Time: Thursday, 9-10 a.m

Simultaneous Simulation of Microgravity and Ionizing Radiation in a Laboratory Environment

A novel system was developed to simulate the combined effects of reduced gravity and ionizing radiation present during spaceflight on biological and particulate samples. The miniature rotary cell culture system (mRCCS) was designed to synchronously rotate up to five independent vessels containing particulate samples suspended in fluid media, constructed using radiation tolerant, biocompatible, and vacuum compatible materials. Reduced gravity conditions were achieved when suspended particles (e.g., 200 μm polystyrene microcarrier beads with or without adhered cell clusters) were suspended inside the vessels moving near terminal velocity in viscous neutral-buoyant fluid media with densities matched to the suspended particles to achieve neutral buoyancy. Variations in centripetal acceleration from slow rotation of the vessels limited reduced gravity environments from ~1·10-5 to ~2·10-2 g, comparable to similar commercially available systems. The effective gravitational acceleration applied to particles was calibrated through particle tracking of suspended particles within the mRCCS systems vessels. The entire mRCCS apparatus can be used in a standalone configuration for independent reduced gravity simulations or can be introduced into the Utah State University’s Space Survivability Test (SST) chamber for radiation exposure or simultaneous radiation exposure under reduced gravity. The SST chamber has a ~90 mCi 90Sr source that emits 0.2 to 2.5 MeV β radiation. The combined mRCCS and SST chamber system can provide average effective dose rates for the suspended particles, controlled over a broad range (900X) from ~3.7 mGy/day to 3.4 Gy/day by varying the source-to-sample distance and using varying slit width graphite shields. This system can provide stable, simultaneous space-like radiation and reduced gravity environments for experiments conducted on timescales of minutes to months.Initial experiments have focused on understanding cellular damage due to the effects of radiation and reduced gravity on cardio and neurological cell clusters, with a long-term goal of studying damage mitigation of biological reagents

Small RNAs: Big Roles in White Mold Infecting Crop Plants

In eukaryotes, small RNAs (sRNAs) are key regulators of RNA silencing which is also known as RNA interference (RNAi). RNAi is an essential mechanism known in plants, animals and fungi that regulates various biological activities, including defense against foreign nucleic acids and viruses. Fungal pathogens, such as Sclerotinia sclerotiorum, severely limit crop production in all parts of the world. Sclerotinia sclerotiorum cause white mold infection, affecting all dicotyledonous plants including many economically important field crops, vegetables, and floriculture. There does not exist known host resistance, and only limited chemical control can be achieved. Given the growing cost and environmental impacts of using fungicides to control these pathogens, an alternative method that exploits RNA silencing in fungi is warranted. The objectives of my research were: (i) to understand RNA-editing mechanism in virus derived small interferring RNAs (VsiRNAs), (ii) to discover mycoviruses from metatranscriptomic study of arbuscular mycorrhizal fungus Rhizophagus spp., and (iii) to characterize the antiviral roles of RNAi genes in S. sclerotiorum. This dissertation includes three chapters from my PhD research. In chapter 1, I have demonstrated that RNA editing mechanism is common in fungi, including S. sclerotiorum, Botrytis cinerea, and Fusarium graminearum, as well as in higher metazoans. My analysis showed that the virus-infected wild-type and RNAi mutant strains of S. sclerotiorum accumulate virusderived small RNAs with distinct patterns of internal and terminal modifications. Chapter 2 deals with the discovery of mycoviruses infecting arbuscular mycorrhizal fungus and their evolution with respect to their counterparts infecting pathogenic fungi. Finally, chapter 3 focuses on the characterization of RNAi genes in S. sclerotiorum. While RNA silencing in fungi is primarily involved in antiviral defense against foreign nucleic acids, pathogenic fungi also utilize RNA silencing mechanism to silence host defense genes in plants through the delivery of small RNA molecules as virulence effectors. Beginning with the discovery of RNA editing events, this study investigates the roles of RNAi genes in fungal pathogen S. sclerotiorum using various approaches in bioinformatics. The present study dissects the RNA silencing pathway in S. sclerotiorum by disrupting its key silencing genes using the split-marker recombination method in order to probe the contributions of these genes, specifically argonautes, to fungal virulence and viral defense mechanisms. Following gene disruption, mutants were studied for changes in phenotype, pathogenicity, viral susceptibility, and small RNA processing compared to the wild-type strain, DK3. Among the argonaute mutants, the Δagl-2 mutant had significantly slower growth and virulence prior to and following virus infection. Additional analyses indicated that the virus-infected wild-type strain accumulated virusderived small RNAS (vsiRNAs) with distinct patterns of internal and terminal nucleotide mismatches. Δdcl-1 mutant produced less vsiRNA compared to Δdcl-2 mutant and the wild type strain, suggesting the two dicers are not in the state of complete redundancy. An emerging area of interest is the use of external dsRNA-based pest control which will require detailed characterization of the RNA silencing pathways in S. sclerotiorum. In an attempt to investigate the utility of dsRNA-based pest control strategy for white mold, we studied the roles of argonaute enzymes, agl-2 and agl-4, in small RNA metabolism in S. sclerotiorum. Our study has shown that RNA silencing deficient S. sclerotiorum show increased susceptibility to virus infection. Additionally, we also profiled different classes of small RNAs, including vsiRNAs, from different gene mutants to study viral susceptibility, internal modification, stability, and small RNA processing compared to wild-type strain, DK3, of S. sclerotiorum. Results from this study show that fungal pathogen S. sclerotiorum host robust RNA silencing mechanisms to defend against foreign nucleic acid and viruses and to facilitate fungal infection of host plants through trans-kingdom RNAi. These findings expand our overall understanding of S. sclerotiorum and has important implications for any current or future uses of dsRNA and mycoviruses as disease control agents

Opiate addiction - current trends and treatment options

Opioids are widely used drugs for treatment of pain and related disorders. Opiate addiction is a major public health concern in the United States causing significant increase in healthcare expenditure.  They produce euphoria and sense of well-being which makes them addictive to some people. Used in higher doses they can lead to cardiac or respiratory compromise. They also impair cognition leading to impaired decision making. Opioids exert their effects by acting on three different types of receptors mu, delta, and kappa located on neuronal cell membranes causing inhibition of neurotransmitter release. Prolonged use of these drugs can lead to physical dependence causing withdrawal symptoms if a person stops using them. Commonly used medications to treat opiate addiction are methadone, LAAM (longer acting derivative of methadone), buprenorphine, and naltrexone