928 research outputs found
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
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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 increases with the P\'eclet
number respectively as and 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 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, is up to 20 times lower than in the latter and varies as
with or (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
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