Response of soil viral and microbial functional diversity to long-term agricultural management in Jackson, West Tennessee

Soil microbial communities are a critical component for ecosystem stability and function. Viruses, as an important biotic controller, have the potential to regulate the abundance and diversity of bacterial communities through infection. Soil is known to harbor abundant and diverse viral assemblages but their ecological role and influence on microbial processes has not been fully elucidated. Microbes can be influenced by viruses not only from infection but though biogeochemical feedbacks of the “microbial (bacterium–phage–DOC) loop” or “viral shunt”. However, we know relatively little about the microbial community and function under the regulation of viruses in soil and how they respond to agricultural management under climate change. The objectives in this dissertation were (1) to estimate variability of soil viral and bacterial communities under a long-term conventional tillage, cover cropping and inorganic N fertilization management practices, and (2) to access the effect of seasonal change on soil bacteria community diversity and structure, and (3) identify the correlation between viruses and their host, and (4) reveal the response of microbial functional genes (C-degradation and N-cycling genes) on cover cropping and fertilization, and the potential roles of viruses on C-degradation. Soil treatments including two nitrogen rates (0, 67 kg N/ha -1), three levels of cover crop (no-cover, hairy vetch and winter wheat), and two tillage managements (conventional tillage and no tillage) from West Tennessee Agriculture Research and Education Center in Jackson were used. The soil bacterial diversity, functional gene and viral diversity was evaluated by 16S rRNA amplicon sequencing, RAPD-PCR, and bulk soil metagenomic sequencing. My findings highlight the importance of microbial on N fertilization and cover cropping in maintaining long-term C pool stability and N concentractions in agricultural soil, and the impact of viruses on C metabolism through regulating microbial metabolism using auxiliary metabolic genes. This study improves our understanding the ecological roles of soil viruses in influencing soil functions under long-term conservation agricultural management

Application of Variational Iteration Method for Dropping Damage Evaluation of the Suspension Spring Packaging System

The dropping damage evaluation for packaging system is essential for safe transportation and storage. A dynamic model of nonlinear cubic-quintic Duffing oscillator for the suspension spring packaging system was proposed. Then, a first-order approximate solution was obtained by applying He’s variable iteration method. Based on the results, a damage evaluation equation was derived, which reveals the main controlling physical parameters for damage potential of drop to packaged products concretely. Finally, the dropping damage boundary curves and surfaces for the system were discussed. It was found that decreasing the suspension angle can improve the safe region of the system

Global dynamics of a fourth-order parabolic equation describing crystal surface growth

In this paper, we study the global dynamics for the solution semiflow of a fourth-order parabolic equation describing crystal surface growth. We show that the equation has a global attractor in H4per(Ω) when the initial value belongs to H1per(Ω)

Optimal control for a higher-order nonlinear parabolic equation describing crystal surface growth

In this paper, we shall study the optimal control of the initial-boundary value problem of a higher-order nonlinear parabolic equation describing crystal surface growth. The existence and uniqueness of weak solutions to the problem are given. According to the variational method, optimal control theories and distributed parameter system control theories, we can deduce that the norm of the solution is related to the control item and initial value in the special Hilbert space. The optimal control of the problem is given, the existence of optimal solution is proved and the optimality system is established

Dynamics of the sub-Ohmic spin-boson model: a time-dependent variational study

The Dirac-Frenkel time-dependent variation is employed to probe the dynamics of the zero temperature sub-Ohmic spin-boson model with strong friction utilizing the Davydov D1 ansatz. It is shown that initial conditions of the phonon bath have considerable influence on the dynamics. Counterintuitively, even in the very strong coupling regime, quantum coherence features still manage to survive under the polarized bath initial condition, while such features are absent under the factorized bath initial condition. In addition, a coherent-incoherent transition is found at a critical coupling strength alpha ~ 0.1 for s=0.25 under the factorized bath initial condition. We quantify how faithfully our ansatz follows the Schr\"{o}dinger equation, finding that the time-dependent variational approach is robust for strong dissipation and deep sub-Ohmic baths (s<<1).Comment: 8 pages, 6 figure

Global dynamics of solutions for a sixth-order parabolic equation describing continuum evolution of film-free surface

This paper is concerned with a sixth-order diffusion equation, which describes continuum evolution of film-free surface. By using the regularity estimates for the semigroups, iteration technique and the classical existence theorem of global attractors we verified the existence of global attractor for this surface diffusion equation in the spaces H3(Ω) and fractional-order spaces Hk(Ω), where 0 ≤ k &lt; ∞

Pullback Attractor for a Non-Autonomous Generalized Cahn-Hilliard Equation with Biological Applications

In this paper, we consider a non-autonomous generalized Cahn-Hilliard equation with biological applications. It is shown that a pullback attractor of the equation exists when the external force has exponential growth

Time-periodic solution for a fourth-order parabolic equation describing crystal surface growth

In this paper, by using the Galerkin method, the existence and uniqueness of time-periodic generalized solutions to a fourth-order parabolic equation describing crystal surface growth are proved