Variable Range Hopping and Electrical Conductivity along the DNA Double Helix

We present a model to describe electrical conductivity along the DNA double helix. In this model, DNA is considered as a one-dimensional disordered system, and electrons are transported via variable range hopping between localized states. Thermal structural fluctuations in DNA further localize electronic wave functions, giving rise to a temperature-dependent localization length. The model quantitatively explains the temperature dependence of the conductivity observed in the lambda phage DNA ( λ-DNA)

Polarizability Fluctuations in Dielectric Materials with Quenched Disorder

We study a model of dielectric response for spatially disordered materials. In this model the local polarizability αr is a quenched random variable. From a one-loop level renormalization-group analysis, we predict that with increasing length scale L, the dimensionless fluctuation strength α¯σ,where 1/α¯ and σ2 are the average and the variance of the distribution for 1/αr, decays as 1/L2universally at large length scales. The interplay of the random polarizability and the long-range dipole-dipole interaction is discussed

Electrical Stimulation to Conductive Scaffold Promotes Axonal Regeneration and Remyelination in a Rat Model of Large Nerve Defect

BACKGROUND: Electrical stimulation (ES) has been shown to promote nerve regeneration when it was applied to the proximal nerve stump. However, the possible beneficial effect of establishing a local electrical environment between a large nerve defect on nerve regeneration has not been reported in previous studies. The present study attempted to establish a local electrical environment between a large nerve defect, and examined its effect on nerve regeneration and functional recovery. METHODOLOGY/FINDINGS: In the present study, a conductive scaffold was constructed and used to bridge a 15 mm sciatic nerve defect in rats, and intermittent ES (3 V, 20 Hz) was applied to the conductive scaffold to establish an electrical environment at the site of nerve defect. Nerve regeneration and functional recovery were examined after nerve injury repair and ES. We found that axonal regeneration and remyelination of the regenerated axons were significantly enhanced by ES which was applied to conductive scaffold. In addition, both motor and sensory functional recovery was significantly improved and muscle atrophy was partially reversed by ES localized at the conductive scaffold. Further investigations showed that the expression of S-100, BDNF (brain-derived neurotrophic factor), P0 and Par-3 was significantly up-regulated by ES at the conductive scaffold. CONCLUSIONS/SIGNIFICANCE: Establishing an electrical environment with ES localized at the conductive scaffold is capable of accelerating nerve regeneration and promoting functional recovery in a 15 mm nerve defect in rats. The findings provide new directions for exploring regenerative approaches to achieve better functional recovery in the treatment of large nerve defect

Variable Range Hopping and Electrical Conductivity along the DNA Double Helix

We present a model to describe electrical conductivity along the DNA double helix. In this model, DNA is considered as a one-dimensional disordered system, and electrons are transported via variable range hopping between localized states. Thermal structural fluctuations in DNA further localize electronic wave functions, giving rise to a temperature-dependent localization length. The model quantitatively explains the temperature dependence of the conductivity observed in the lambda phage DNA ( λ-DNA).This article is from Physical Review Letters 86 (2001): 6018, doi:10.1103/PhysRevLett.86.6018. Posted with permission.</p

Polarizability Fluctuations in Dielectric Materials with Quenched Disorder

We study a model of dielectric response for spatially disordered materials. In this model the local polarizability αr is a quenched random variable. From a one-loop level renormalization-group analysis, we predict that with increasing length scale L, the dimensionless fluctuation strength α¯σ,where 1/α¯ and σ2 are the average and the variance of the distribution for 1/αr, decays as 1/L2universally at large length scales. The interplay of the random polarizability and the long-range dipole-dipole interaction is discussed.This article is from Physical Review E 62 (2000: 4698, doi:10.1103/PhysRevE.62.4698. Posted with permission.</p

Study of some problems on the development and protection of fracture-karst water resources in North China

Water resources are in shortage in China, especially in northern China. As surface water often dries in spring and summer, fracture-karst water becomes an important source for supply. [[Karst in China can be divided into three types: karst in northern China, karst in southern China and karst in western China. Karst in northern China is not a typical karst but a fracture karst. The aquifers are networks of solution fractures, fissures and openings. Some wide solution fractures become strong runoff zones. The aquifer has a large coefficient of transmissibility and small storage capacity. It is strongly heterogeneous and anisotropic. Fracture-karst water flows at a high velocity and so the transport of contaminants is a advection-dominated problem. The amount of fracture-karst water depends on the condition of recharge. As the storage capacity is small, the fluctuation of water level in wells is greater than that in porous aquifer. [[According to the previous data, some authors suggested that the depths of wells in a fracture-karst aquifer should be less than 100∼300 m. In the Zibo area we found that some deep wells (at depths 500∼700 m) had also great pumping rates and the yields reached 3000∼5000 m3/d. It may be related to the palaeokarst in the geologic history. [[Fracture-karst water is vulnerable to contamination and the environment is fragile. Therefore, factories, plants, dumps and landfills should not be placed on the recharge areas of fracture-karst water. When making land planning, considerations should be given to protect cultivated land as well as groundwater resources. Compared with porous water both the velocity and the distance of plume movement in fracture-karst water are much larger. The curves of contaminant concentrations versus time in fracture-karst wells often fluctuate greatly, which are different from those in porous water wells. Pumping is one of the best methods for remediation. If the area of the groundwater basin is not large, we can renew contaminated water by pumping. If it is large o

Study of some problems on the development and protection of fracture-karst water resources in North China

Water resources are in shortage in China, especially in northern China. As surface water often dries in spring and summer, fracture-karst water becomes an important source for supply. [[Karst in China can be divided into three types: karst in northern China, karst in southern China and karst in western China. Karst in northern China is not a typical karst but a fracture karst. The aquifers are networks of solution fractures, fissures and openings. Some wide solution fractures become strong runoff zones. The aquifer has a large coefficient of transmissibility and small storage capacity. It is strongly heterogeneous and anisotropic. Fracture-karst water flows at a high velocity and so the transport of contaminants is a advection-dominated problem. The amount of fracture-karst water depends on the condition of recharge. As the storage capacity is small, the fluctuation of water level in wells is greater than that in porous aquifer. [[According to the previous data, some authors suggested that the depths of wells in a fracture-karst aquifer should be less than 100∼300 m. In the Zibo area we found that some deep wells (at depths 500∼700 m) had also great pumping rates and the yields reached 3000∼5000 m3/d. It may be related to the palaeokarst in the geologic history. [[Fracture-karst water is vulnerable to contamination and the environment is fragile. Therefore, factories, plants, dumps and landfills should not be placed on the recharge areas of fracture-karst water. When making land planning, considerations should be given to protect cultivated land as well as groundwater resources. Compared with porous water both the velocity and the distance of plume movement in fracture-karst water are much larger. The curves of contaminant concentrations versus time in fracture-karst wells often fluctuate greatly, which are different from those in porous water wells. Pumping is one of the best methods for remediation. If the area of the groundwater basin is not large, we can renew contaminated water by pumping. If it is large o

Settlement and pore-water pressure induced in a semi-infinite transversely isotropic saturated by fast moving traffic loading

The theme of the seminar is still the latest research progress in the field of environmental vibration, including urban rail transit, high-speed railway caused by environmental vibration prediction calculation, testing, evaluation, vibration reduction measures and other disciplines, is the environmental vibration of a Event. The conference has received 264 academic papers from experts and scholars from 18 countries and regions, including China, Japan, Belgium, Germany, Australia, Switzerland, Italy, Sweden, UK, USA, Canada, Denmark, Russia, the Netherlands, South Korea, Iran, Hong Kong and Taiwan