Ab initio electron-two-phonon scattering in GaAs from next-to-leading order perturbation theory

Electron-phonon (e–ph) interactions are usually treated in the lowest order of perturbation theory. Here we derive next-to-leading order e–ph interactions, and compute from first principles the associated electron-two-phonon (2ph) scattering rates. The derivations involve Matsubara sums of two-loop Feynman diagrams, and the numerical calculations are challenging as they involve Brillouin zone integrals over two crystal momenta and depend critically on the intermediate state lifetimes. Using Monte Carlo integration together with a self-consistent update of the intermediate state lifetimes, we compute and converge the 2ph scattering rates, and analyze their energy and temperature dependence. We apply our method to GaAs, a weakly polar semiconductor with dominant optical-mode long-range e–ph interactions. We find that the 2ph scattering rates are as large as nearly half the value of the one-phonon rates, and that including the 2ph processes is necessary to accurately predict the electron mobility in GaAs from first principles

Pemurnian Pretrombin-2pH Hasil Ko-Ekspresi Chaperone pada Escherichia coli ER2566 Menggunakan Sistem IMPACT

Pemurnian pretrombin-2 merupakan tahap penting dalam produksi trombin sebagai salah satu komponen lem fibrin untuk mengganti teknik jahitan pascabedah mata. Pemurnian pretrombin-2 melalui sistem IMPACT memanfaatkan aktivitas pemotongan intein yang membawa penanda afinitas chitin-binding domain dan tidak memerlukan enzim protease tambahan. Pemotongan pretrombin-2pH dari CBD-intein dapat dilakukan melalui C-terminal intein dengan induksi perubahan pH dan suhu tanpa memerlukan reagen kimia tambahan. Namun dibutuhkan kondisi pH, suhu dan waktu inkubasi yang sesuai untuk memotong pretrombin-2pH dari C-terminal intein. Penelitian ini bertujuan untuk mendapatkan kondisi pH, suhu dan waktu inkubasi pemotongan yang dibutuhkan dalam pemurnian pretrombin-2pH dengan memanfaatkan aktivitas pemotongan C-terminal intein. Metode yang dilakukan adalah ekspresi gen CBD-intein-pt2pH menggunakan vektor pTWIN1 dalam E. coli ER2566 disertai dengan ko-ekspresi chaperone menggunakan plasmid pG-KJE8, isolasi CBD-intein-PT2pH dengan metode sonikasi, pemurnian pretrombin-2pH menggunakan sistem IMPACT, serta karakterisasi pretrombin-2pH hasil pemurnian dengan metode SDS-PAGE. Hasil penelitian ini menunjukkan bahwa kondisi inkubasi pemotongan yang dibutuhkan untuk mendapatkan pretrombin-2pH murni adalah pada suhu 25oC, selama 48 jam dengan perubahan pH lingkungan kolom dari 8,5 ke 7,0. Namun efisiensi pemotongan yang dihasilkan sangat kecil. Hal ini mungkin disebabkan oleh kondisi suhu dan waktu inkubasi yang belum optimum serta diduga masih terdapat reaksi proteolisis yang mendegradasi pretrombin-2pH murni yang dihasilkan

Sensitivity to multi-phonon excitations in heavy-ion fusion reactions

Measured cross sections for the fusion of {64}Ni with {64}Ni, {74}Ge, and {100}Mo targets are analyzed in a coupled-channels approach. The data for the {64}Ni target above 0.1 mb are reproduced by including couplings to the low-lying 2^+ and 3^- states and the mutual and two-phonon excitations of these states. The calculations become more challenging as the fusing nuclei become softer and heavier, and excitations to multi-phonon states start to play an increasingly important role. Thus it is necessary to include up to four-phonon excitations in order to reproduce the data for the {64}Ni+{74}Ge system. Similar calculations for {64}Ni+{100}Mo, and also for the symmetric {74}Ge+{74}Ge system, show large discrepancies with the data. Possible ways to improve the calculations are discussed.Comment: 24 pages, 7 figures, 4 table

Doves and hawks in economics revisited. An evolutionary quantum game theory-based analysis of financial crises

The last financial and economic crisis demonstrated the dysfunctional long-term effects of aggressive behaviour in financial markets. Yet, evolutionary game theory predicts that under the condition of strategic dependence a certain degree of aggressive behaviour remains within a given population of agents. However, as the consequences of the financial crisis exhibit, it would be desirable to change the 'rules of the game' in a way that prevents the occurrence of any aggressive behaviour and thereby also the danger of market crashes. The paper picks up this aspect. Through the extension of the in literature well-known Hawk-Dove game by a quantum approach, we can show that dependent on entanglement, also evolutionary stable strategies can emerge, which are not predicted by classical evolutionary game theory and where the total economic population uses a non aggressive quantum strategy

Inviscid Large deviation principle and the 2D Navier Stokes equations with a free boundary condition

Using a weak convergence approach, we prove a LPD for the solution of 2D stochastic Navier Stokes equations when the viscosity converges to 0 and the noise intensity is multiplied by the square root of the viscosity. Unlike previous results on LDP for hydrodynamical models, the weak convergence is proven by tightness properties of the distribution of the solution in appropriate functional spaces