Lotka-Volterra with randomly fluctuating environments: a full description

In this note, we study the long time behavior of Lotka-Volterra systems whose coefficients vary randomly. Benam and Lobry established that randomly switching between two environments that are both favorable to the same species may lead to four different regimes: almost sure extinction of one of the two species, random extinction of one species or the other and persistence of both species. Our purpose here is to provide a complete description of the model. In particular, we show that any couple of environments may lead to the four different behaviours of the stochastic process depending on the jump rates

Mutational-kinetic Analysis Reveals the Roles of Arginines and Aromatics in the Core of the GABAA Receptor Ligand-binding Pocket

The γ-aminobutyric acid type A (GABA) receptor is a member of the cys-loop family of ligand-gated ion channels that plays a crucial role in normal brain function by transducing the majority of inhibitory neurotransmission in the central nervous system. The studies documented in this dissertation were aimed at validating and refining the current best model for the interaction of GABA with the GABAA receptor via structure-function perturbation analysis. Mutational-kinetic data was used in conjunction with homology modeling knowledge to draw up architectural and functional roles of the arginines and aromatics in GABA-binding pocket. The results provide interesting new insights. Two positively charged arginine residues, which have been implicated in ligand binding, were profiled through serial mutagenesis, to get at the specific side chain properties required for the roles they serve. The structural and functional contribution of four aromatic residues were examined through measuring the influence of their side chain on GABA binding rate with respect to changes caused by point mutations. An interaction between two aromatic residues critical for proper ligand binding was discovered through a screen for functional coupling between them and four neighboring arginines. These results were subsequently employed in an attempt to refine the current ligand-receptor interaction model, proposing specific roles for the amino acid residues studied. In the current best model of the GABAA receptor\u27s ligand-binding pocket, the amino moiety of GABA is coordinated by a cation-π interaction with β2Y97 and the carboxyl moiety coordinated by an interaction with either β2R207 or α1R67 (or possibly both). Here, we incorporate the results of this dissertation to modify and add significant detail to this model. The model proposed here includes the following features: a hydrophobic interaction between β2Y97 and β2F200, an inter-subunit cation-π interaction between β2Y97 and α1R132, a cation-π interaction between the amino group of GABA and β2F200, hydrogen bond(s) between the carboxyl end of GABA and the guanidinium group of α1R67, and an interaction between the side chain of β2R207 and the backbone carbonyl of β2Y97

Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection

In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116

A tight coupling between β\u3csub\u3e2\u3c/sub\u3eY97 and β\u3csub\u3e2\u3c/sub\u3eF200 of the GABA\u3csub\u3eA\u3c/sub\u3e receptor mediates GABA binding

The GABAA receptor is an oligopentameric chloride channel that is activated via conformation changes induced upon the binding of the endogenous ligand, GABA, to the extracellular inter-subunit interfaces. Although dozens of amino acid residues at the α/β interface have been implicated in ligand binding, the structural elements that mediate ligand binding and receptor activation are not yet fully described. In this study, double-mutant cycle analysis was employed to test for possible interactions between several arginines (α1R67, α1R120, α1R132, and β2R207) and two aromatic residues (β2Y97 and β2F200) that are present in the ligand-binding pocket and are known to influence GABA affinity. Our results show that neither α1R67 nor α1R120 is functionally coupled to either of the aromatics, whereas a moderate coupling exists between α1R132 and both aromatic residues. Significant functional coupling between β2R207 and both β2Y97 and β2F200 was found. Furthermore, we identified an even stronger coupling between the two aromatics, β2Y97 and β2F200, and for the first time provided direct evidence for the involvement of β2Y97 and β2F200 in GABA binding. As these residues are tightly linked, and mutation of either has similar, severe effects on GABA binding and receptor kinetics, we believe they form a single functional unit that may directly coordinate GABA

ヒト感染能を有する鳥インフルエンザウイルスポリメラーゼの機能解析

この博士論文は内容の要約のみの公開（または一部非公開）になっています筑波大学 (University of Tsukuba)201

Influence of Ca[Mg3SiN4]Ce3+ phosphor’s concentration on optical properties of the 5600K RP-WLEDs

In this paper, we propose Ca[Mg3SiN4]Ce3+ Phosphor as a new material solution for improving the optical properties in terms of CRI, CQS. D-CCT, LO of the 5600K remote-packaging white LEDs (RP-WLEDs). In the first stage, we built and investigated the 5600K RP-WLEDs by adding the red phosphor to the phosphor layer. Then, the scattering processes inside the phosphor layer are investigated by Mat Lab software. From the research results, we discovered that the concentration of the adding phosphor significantly improved the optical properties of the5600K RP-WLEDs. All the results are convinced by Light Tools and Mat Lab software

Rateless codes-based secure communication employing transmit antenna selection and harvest-to-jam under joint effect of interference and hardware impairments

In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets to a destination in presence of an eavesdropper. Moreover, a cooperative jammer node harvests energy from radio frequency (RF) signals of the source and the interference sources to generate jamming noises on the eavesdropper. The data transmission terminates as soon as the destination can receive a sufficient number of the encoded packets for decoding the original data of the source. To obtain secure communication, the destination must receive sufficient encoded packets before the eavesdropper. The combination of the TAS and harvest-to-jam techniques obtains the security and efficient energy via reducing the number of the data transmission, increasing the quality of the data channel, decreasing the quality of the eavesdropping channel, and supporting the energy for the jammer. The main contribution of this paper is to derive exact closed-form expressions of outage probability (OP), probability of successful and secure communication (SS), intercept probability (IP) and average number of time slots used by the source over Rayleigh fading channel under the joint impact of co-channel interference and hardware impairments. Then, Monte Carlo simulations are presented to verify the theoretical results.Web of Science217art. no. 70

Red-emitting Ba2Si5N8Eu2+ conversion phosphor: A new selection for enhancing the optical performance of the in-cup packaging MCW-LEDs

In this research, the influence of the red-emitting Ba2Si5N8Eu2+ convention phosphor on the optical performance of the 7,000K and 7,700K in-cup packaging multi-chip white LEDs (MCW-LEDs) is investigated. The effect of the red-emitting Ba2Si5N8Eu2+ convention phosphor is demonstrated based on Mie Theory by Mat Lab and Light Tools software. The research results indicated that the optical performance of MCW-LEDs was crucially affected by the red-emitting Ba2Si5N8Eu2+ phosphor's concentration. This paper provides an essential recommendation for selecting and developing the phosphor materials for MW-LEDs manufacturing.Web of Science51art. no. 148615

Intercept probability analysis in DF time switching full-duplex relaying network with impact of Co-channel interference at the eavesdropper

In this research, we propose and investigate intercept probability analysis in DF time switching relaying full-duplex with impact of Co-channel interference at the eavesdropper. In the beginning stage, we present the DF time switching relaying full-duplex with the Impact of Co-channel interference at the eavesdropper. Furthermore, the closed-form expression of the intercept probability (IP) is analyzed and derived in connection with the primary system parameters. Finally, the Monte Carlo simulation is performed for verifying the correctness of the analytical section. From the research results, a novel solution and some recommendations can be proposed for the communication network in the near future

Sr[Mg3SiN4]Eu2+ phosphor: solution for enhancing the optical properties of the 5600K remote-packaging WLEDs

In the last decade, light-emitting diodes (LEDs), which based on spontaneous light emission in semiconductors can be considered as the main light sources for civil and industrial purposes. In this paper, we presented and investigated the effect of the Sr[Mg3SiN4]Eu2+ concentration on the optical properties of the 5600K remote-packaging WLEDs (RP-WLEDs). We use the Mat Lab and the LightTool software to investigate the effect of the Sr[Mg3SiN4]Eu2+ concentration on the CRI, CQS, D-CCT and LO of the 5600K RP-WLEDs. From the result, we can state that the concentration of the Sr[Mg3SiN4]Eu2+ influenced on the CRI, CQS, D-CCT and LO of the RP-WLEDs. The red Sr[Mg3SiN4]Eu2+ phosphor can be considered as the novel recommendation for LEDs industry