Therapeutic level IV.

Passive or unassisted ion permeation through lipid bilayers involves a type of rare events by which cells regulate their salt concentrations and pH. It is important to understand its mechanism in order to develop technologies of, for example, delivering or maintaining small drug-like molecules inside cells. In earlier simulations of passive ion permeations, the commonly used sampling methods usually define the positions of ions relative to the membrane as a measure of permeation, i.e., the collective variable, ignoring the active participations of other particles. Newly defined collective variables involving the movements of ions, lipids, and water molecules allow us to identify the transition paths on the free energy landscape using the 2D umbrella sampling techniques. In this work, this technique was used to study the permeation processes of some well-known ions, sodium, potassium, and chloride. It is found permeations of sodium and potassium are assisted by important lipid bilayer deformations and massive water solvation, while chloride may not. Chloride may have two different possible pathways, in which the energetic favorable one is similar to the solubility-diffusion model. The free energy barriers for the permeation of these ions are in semiquantitative agreement with experiments. Further analyses on the distributions of oxygens and interaction energies suggest the electrostatic interactions between ions and polar headgroups of lipids may greatly influence membrane deformation as well as the water wire and furthermore the free energy barriers of waterwire mediated pathways. For chloride, the nonwaterwire pathway may be energetically favorable.

The Cropping System Model (CMS) simulates growth, development and yield of a crop growing on a uniform area of land under prescribed or simulated management as well as the changes in soil water, carbon, and nitrogen that take place under the cropping system over time. Decision Support System for Agro-technology Transfer DSSAT is one of many cropping system models and has been relatively widely applied. In this paper, the development history, the system structure, and the application field of the model system are summarized, and the principle and mechanism of the model to simulate the soil-water balance in the study of water resources management and the representative study results obtained by the scholars in China are analyzed in detail, so as to provide references for relevant studies and applications.

Community detection as a branch of social network analysis has been a hot topic in the past decade. This paper reviews the research about the community detection these years and focuses on the community detection relevant classical algorithms as well as the classic real network datasets.

In the past 28 years, we find that except for the fiscal revenue of 5,132.1 billion yuan in 2007, which is greater than the fiscal expenditure of 4,978.1 billion yuan, presenting a fiscal surplus, the fiscal expenditure of the rest years is greater than the fiscal revenue, showing the situation of public sector net cash requirement (psncr), especially in 2011, the deficit( the gap between fiscal expenditure and fiscal revenue) is 537.3 billion yuan. Since then, the gap between expenditure and revenue has been increasing with each passing year. In 2015, the fiscal deficit is 2,368 billion yuan. In 2018, the fiscal deficit has been expanded to 3,754.4 billion yuan. In order to avoid the continuous increment of the deficit. This paper discusses the causal relationship between China's fiscal revenue and public expenditure from 1990 to 2018. If fiscal revenue has a positive impact on public expenditure, showing that the government shall reduce fiscal deficit through tax increment. On the contrary, it makes public expenditure continue to expand, leading to the continuous deterioration of fiscal deficit, so as to further decide whether China's future fiscal policy should adopt increasing fiscal revenue or deducting public expenditure policy to reduce the deficit.