Distributed Learning Policies for Power Allocation in Multiple Access Channels

We analyze the problem of distributed power allocation for orthogonal multiple access channels by considering a continuous non-cooperative game whose strategy space represents the users' distribution of transmission power over the network's channels. When the channels are static, we find that this game admits an exact potential function and this allows us to show that it has a unique equilibrium almost surely. Furthermore, using the game's potential property, we derive a modified version of the replicator dynamics of evolutionary game theory which applies to this continuous game, and we show that if the network's users employ a distributed learning scheme based on these dynamics, then they converge to equilibrium exponentially quickly. On the other hand, a major challenge occurs if the channels do not remain static but fluctuate stochastically over time, following a stationary ergodic process. In that case, the associated ergodic game still admits a unique equilibrium, but the learning analysis becomes much more complicated because the replicator dynamics are no longer deterministic. Nonetheless, by employing results from the theory of stochastic approximation, we show that users still converge to the game's unique equilibrium. Our analysis hinges on a game-theoretical result which is of independent interest: in finite player games which admit a (possibly nonlinear) convex potential function, the replicator dynamics (suitably modified to account for nonlinear payoffs) converge to an eps-neighborhood of an equilibrium at time of order O(log(1/eps)).Comment: 11 pages, 8 figures. Revised manuscript structure and added more material and figures for the case of stochastically fluctuating channels. This version will appear in the IEEE Journal on Selected Areas in Communication, Special Issue on Game Theory in Wireless Communication

Dynamic Power Allocation Games in Parallel Multiple Access Channels

We analyze the distributed power allocation problem in parallel multiple access channels (MAC) by studying an associated non-cooperative game which admits an exact potential. Even though games of this type have been the subject of considerable study in the literature, we find that the sufficient conditions which ensure uniqueness of Nash equilibrium points typically do not hold in this context. Nonetheless, we show that the parallel MAC game admits a unique equilibrium almost surely, thus establishing an important class of counterexamples where these sufficient conditions are not necessary. Furthermore, if the network's users employ a distributed learning scheme based on the replicator dynamics, we show that they converge to equilibrium from almost any initial condition, even though users only have local information at their disposal.Comment: 18 pages, 4 figures, submitted to Valuetools '1

Closed-Form Density of States and Localization Length for a Non-Hermitian Disordered System

We calculate the Lyapunov exponent for the non-Hermitian Zakharov-Shabat eigenvalue problem corresponding to the attractive non-linear Schroedinger equation with a Gaussian random pulse as initial value function. Using an extension of the Thouless formula to non-Hermitian random operators, we calculate the corresponding average density of states. We analyze two cases, one with circularly symmetric complex Gaussian pulses and the other with real Gaussian pulses. We discuss the implications in the context of the information transmission through non-linear optical fibers.Comment: 5 pages, 1 figur

Cas9 interrogates DNA in discrete steps modulated by mismatches and supercoiling.

The CRISPR-Cas9 nuclease has been widely repurposed as a molecular and cell biology tool for its ability to programmably target and cleave DNA. Cas9 recognizes its target site by unwinding the DNA double helix and hybridizing a 20-nucleotide section of its associated guide RNA to one DNA strand, forming an R-loop structure. A dynamic and mechanical description of R-loop formation is needed to understand the biophysics of target searching and develop rational approaches for mitigating off-target activity while accounting for the influence of torsional strain in the genome. Here we investigate the dynamics of Cas9 R-loop formation and collapse using rotor bead tracking (RBT), a single-molecule technique that can simultaneously monitor DNA unwinding with base-pair resolution and binding of fluorescently labeled macromolecules in real time. By measuring changes in torque upon unwinding of the double helix, we find that R-loop formation and collapse proceed via a transient discrete intermediate, consistent with DNA:RNA hybridization within an initial seed region. Using systematic measurements of target and off-target sequences under controlled mechanical perturbations, we characterize position-dependent effects of sequence mismatches and show how DNA supercoiling modulates the energy landscape of R-loop formation and dictates access to states competent for stable binding and cleavage. Consistent with this energy landscape model, in bulk experiments we observe promiscuous cleavage under physiological negative supercoiling. The detailed description of DNA interrogation presented here suggests strategies for improving the specificity and kinetics of Cas9 as a genome engineering tool and may inspire expanded applications that exploit sensitivity to DNA supercoiling

Theory of Planned Behavior on Factors Associated with Safe Sex Behavior among Female Sex Workers in Surakarta, Central Java

Background: Practising safe sex is important in order to ensure health and safety. Safe sex means exactly that "safe" is in terms of having sex without getting a contagious disease from your sex partner(s). Safe sex has the following outcomes: (1) It acts as a contraception to prevent pregnancy; (2) It prevents the transmission of sexually transmitted infections and infestations; and (3) It prevents the transmission of HIV, viral hepatitis, and other blood-borne viruses. This study aimed to analyze factors associated with safe sex behavior among female sex workers in Surakarta, Central Java, using Theory of Planned Behavior. Subjects and Method: This was a cross-sectional study carried out in Surakarta, Central Java, from April to May 2018. A sample of 134 female sex workers was selected by simple random sampling. The dependent variable was safe sex behavior. The independent variables were subjective norm, perceived behavior control, intention, attitude, education, and age. The data were collected by questionnaire and analyzed by path analysis. Results: Safe sex behavior was directly affected by intention (b= 0.96; 95% CI= 0.26 to 1.66; p= 0.007). It was indirectly affected by attitude perceived behavior con¬trol, subjective norm, education, and age. Conclusion: Safe sex behavior is directly affected by intention. It is indirectly affected by attitude perceived behavior control, subjective norm, education, and age. Keywords: safe sex behavior, female sex worker, theory of planned behavio

Influence of the disorder on tracer dispersion in a flow channel

Tracer dispersion is studied experimentally in periodic or disordered arrays of beads in a capillary tube. Dispersion is measured from light absorption variations near the outlet following a steplike injection of dye at the inlet. Visualizations using dye and pure glycerol are also performed in similar geometries. Taylor dispersion is dominant both in an empty tube and for a periodic array of beads: the dispersivity $l\_d$ increases with the P\'eclet number $Pe$ respectively as $Pe$ and $Pe^{0.82}$ and is larger by a factor of 8 in the second case. In a disordered packing of smaller beads (1/3 of the tube diameter) geometrical dispersion associated to the disorder of the flow field is dominant with a constant value of $l\_d$ reached at high P\'eclet numbers. The minimum dispersivity is slightly higher than in homogeneous nonconsolidated packings of small grains, likely due heterogeneities resulting from wall effects. In a disordered packing with the same beads as in the periodic configuration, $l\_d$ is up to 20 times lower than in the latter and varies as $Pe^\alpha$ with $\alpha = 0.5$ or $= 0.69$ (depending on the fluid viscosity). A simple model accounting for this latter result is suggested.Comment: available online at http://www.edpsciences.org/journal/index.cfm?edpsname=epjap&niv1=contents&niv2=archive

Pengaruh Suplementasi Betain terhadap Beberapa Parameter Lipida dan Protein Darah pada Puyuh

The objective of this research was to see the influence of betaine supplementation on some of blood lipid and protein parameters in laying quails. The research used four treatments based on completely randomized design. Each treatment was replicated five times with seventeen quails each. The treatments used 340 quails aged 4 weeks with average weigh 98.31±8.67 grams. The supplementation levels of betaine were 0 (control); 0.07; 0.14 and 0.21%. Twenty quails aged 14 weeks were taken from each replicate to determine blood lipid and protein. Data were analyzed by analysis of variance and if there was an effect of treatment, then it was analyzed by Duncan’s Multiple Range Test. The result showed that betaine supplementation at level 0.14% resulted higher level of low density lipoprotein compared with the other treatments. It could be concluded that betaine supplementation at 0.14% resulted higher concentration of low density lipoprotein than control. Key words: quail, betaine, blood lipid, blood protei