On the Evolutionary Edge of Altruism: A Game-Theoretic Proof of Hamilton's Rule for a Simple Case of Siblings

We offer a game-theoretic proof of Hamilton's rule for the spread of altruism. For a simple case of siblings, we show that the rule can be derived as the outcome of a one-shot prisoner's dilemma game between siblings.Evolution of altruism, Hamilton's rule, One-shot prisoner's dilemma game

A Theory of Self-Segregation as a Response to Relative Deprivation

We model group formation as a response to relative deprivation. We employ a simple measure of relative deprivation. We show that the process of deprivation-induced self-selection into groups reaches a unique steady state. We study the social welfare implications of the deprivation-induced process of group formation and show that when individuals are left to pursue their betterment the resulting state tends to fall short of the best social outcome. We present several implications of the model including federalism and the demand for secession.

Migration Dynamics

Quite often established migrants offer assistance and support that facilitate the arrival of new migrants. Why would migrants want other migrants to join them - so much so as to be willing to pay for them to come? We suggest a rationale. Our modeling framework is capable of explaining several stylized facts pertaining to transfers by migrants and the structure and dynamics of migration.Migration dynamics, Migrants' transfers, Follow-up migration

Preparation of water-soluble nanographite and its application in water-based cutting fluid

Water-soluble nanographite was prepared by in situ emulsion polymerization using methacrylate as polymeric monomer. The dispersion stability and dispersion state of graphite particles were evaluated by UV-visible spectrophotometry and scanning electron microscopy, respectively. The water-soluble nanographite was then added into the water-based cutting fluid as lubricant additive. The lubrication performance of water-based cutting fluid with the nanographite additive was studied on four-ball friction tester and surface tensiometer. Results indicate that the modification method of in situ emulsion polymerization realizes the uniform and stabilized dispersion of nanographite in aqueous environment. The optimal polymerization condition is 70°C (polymerization temperature) and 5 h (polymerization time). The addition of nanographite decreases the friction coefficient and wear scar diameter by 44% and 49%. Meanwhile, the maximum non-seizure load (P(B)) increases from 784 to 883 N, and the value of surface tension (32.76 × 10(−3) N/m) is at low level. Nanographite additive improves apparently the lubrication performance of water-based cutting fluid

Nitrogen-doped carbon nanotubes with encapsulated Fe nanoparticles as efficient oxygen reduction catalyst for alkaline membrane direct ethanol fuel cells

Exploring low-cost and highly efficient non-precious metal electrocatalysts toward oxygen reduction reaction is crucial for the development of fuel cells. Herein, we report the synthesis of bamboo-like N-doped carbon nanotubes with encapsulated Fe-nanoparticles through high-temperature pyrolysis of multiple nitrogen complex consisting of benzoguanamine, cyanuric acid, and melamine. As-prepared catalyst exhibits high catalytic activity for oxygen reduction with onset potential of 1.10 V and half-wave potential of 0.93 V, as well as low H2O2 yield (<1%) in alkaline medium. The mass activity of the catalyst at 1.0 V (0.58 A g−1) can reach 43% of state-of-the-art commercial Pt/C. This catalyst also exhibits high durability and ethanol tolerance. When it was applied in alkaline membrane direct ethanol fuel cell, the peak power density could reach to 64 mW cm−2, indicating its attractive application prospect in fuel cells

(3R*)-Methyl 3-[(2S*)-4,6-dimethoxy-2-(4-methoxyphenyl)-3-oxo-2,3-dihydro-1-benzofuran-2-yl]-2-methoxycarbonyl-3-phenylpropionate

The title compound, C29H28O9, was isolated from the reaction of 4,6-dimeth­oxy-2-(4-methoxy­phen­yl)-3-benzofuran and α-methoxy­carbonyl­cinnaminate. The two aromatic rings form a dihedral angle of 22.7 (1)°. One methoxy­carbonyl group is disordered between two orientations in a 0.612 (4):0.388 (4) ratio. The crystal structure exhibits no significantly short inter­molecular contacts