Eco-Evolutionary Feedback and the Invasion of Cooperation in Prisoner's Dilemma Games

Unveiling the origin and forms of cooperation in nature poses profound challenges in evolutionary ecology. The prisoner's dilemma game is an important metaphor for studying the evolution of cooperation. We here classified potential mechanisms for cooperation evolution into schemes of frequency- and density-dependent selection, and focused on the density-dependent selection in the ecological prisoner's dilemma games. We found that, although assortative encounter is still the necessary condition in ecological games for cooperation evolution, a harsh environment, indicated by a high mortality, can foster the invasion of cooperation. The Hamilton rule provides a fundamental condition for the evolution of cooperation by ensuring an enhanced relatedness between players in low-density populations. Incorporating ecological dynamics into evolutionary games opens up a much wider window for the evolution of cooperation, and exhibits a variety of complex behaviors of dynamics, such as limit and heteroclinic cycles. An alternative evolutionary, or rather succession, sequence was proposed that cooperation first appears in harsh environments, followed by the invasion of defection, which leads to a common catastrophe. The rise of cooperation (and altruism), thus, could be much easier in the density-dependent ecological games than in the classic frequency-dependent evolutionary games

Isolation and Characterization of Organosolv Lignins From Wheat Straw

Delignification of wheat straw with aqueous methanol, ethanol, l-propanol, n-butanol, dioxane, and acetone in the presence of acid catalyst (0.02 N H2SO4) at low temperature (75°C) for 2 h was studied. The effect of ethanol-water ratios on the yield of dissolved lignin is also reported here. There was no significant difference in the organosolv lignin yields among the various organic solvents used, which accounted for 24-28% of the total amount of acidic chlorite lignin present in wheat straw. Increase of ethanol-water volume ratio from 40/60 to 70/30 resulted in raising lignin yields from 25 to 31%, while the reverse yield from 31 to 24% appeared in the increase of volume ratio from 70/30 to 90/10. The isolated organosolv lignin fractions contained low amounts of polysaccharide sugars (4.5-5.3%) and had low average molecular weights (1190-1650 Da), which corresponded with the ball-milling lignin, enzyme lignin, and alkali lignin obtained from wheat straw. The predominant components of the alkali nitrobenzene oxidation products were found to be vanillin and syringaldehyde. The yield of vanillin was slightly higher than that of syringaldehyde in all the nitrobenzene oxidation products of the isolated organosolv lignin preparations

MeCP2 regulates the timing of critical period plasticity that shapes functional connectivity in primary visual cortex

Mutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome, an autism spectrum-associated disorder with a host of neurological and sensory symptoms, but the pathogenic mechanisms remain elusive. Neuronal circuits are shaped by experience during critical periods of heightened plasticity. The maturation of cortical GABA inhibitory circuitry, the parvalbumin+ (PV+) fast-spiking interneurons in particular, is a key component that regulates the initiation and termination of the critical period. Using MeCP2-null mice, we examined experience-dependent development of neural circuits in the primary visual cortex. The functional maturation of parvalbumin interneurons was accelerated upon vision onset, as indicated by elevated GABA synthetic enzymes, vesicular GABA transporter, perineuronal nets, and enhanced GABA transmission among PV interneurons. These changes correlated with a precocious onset and closure of critical period and deficient binocular visual function in mature animals. Reduction of GAD67 expression rescued the precocious opening of the critical period, suggesting its major role in MECP2-mediated regulation of experience-driven circuit development. Our results identify molecular changes in a defined cortical cell type and link aberrant developmental trajectory to functional deficits in a model of neuropsychiatric disorder

Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology

An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 is a good candidate for searching for such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from a best fit model with $M$/$M_{\odot}$ = 0.630 $\pm$ 0.002, $T_{\rm eff}$ = 12400 K $\pm$ 70 K, log($M_{\rm He}/M$) = -2.00 $\pm$ 0.02, log($M_{\rm H}/M$) = -4.50 $\pm$ 0.02 and determining a rotation period of $\approx$ 7 days.Comment: 10 pages, 13 figures, accepted by MNRA

Joint Deployment and Resource Management for VLC-enabled RISs-assisted UAV Networks

In this paper, the problem of the deployment and resource management for visible light communication (VLC)-enabled, reconfigurable intelligent surfaces (RISs)-assisted unmanned aerial vehicle (UAV) networks is investigated. In the considered model, UAVs provide terrestrial users with wireless services and illumination simultaneously. Moreover, RISs are utilized to further improve the channel quality between UAVs and users. This joint placement and resource management problem is constructed aiming at acquiring the optimal UAV deployment, RISs phase shift, user and RIS association that satisfies the users’ needs with minimum consumption of the UAVs’ energy. An iterative algorithm that alternately optimizes continuous and binary variables is proposed to solve this mixed-integer programming problem. Specifically, RISs phase shift optimization is solved by phases alignment method and semidefinite program algorithm. Next, the successive convex approximation algorithm is proposed to settle the UAV deployment problem. The user and RIS association variables are relaxed to the continuous ones before adopting the dual method to find the optimal solution. Moreover, a greedy algorithm is proposed as an alternative to RIS association optimization with low complexity. Simulation results show that the proposed two schemes harvest the superior performance of 34.85% and 32.11% energy consumption reduction over the case without RIS, respectively