Asymptotically Hyperbolic Metrics on Unit Ball Admitting Multiple Horizons

In this paper, we construct an asymptotically hyperbolic metric with scalar curvature -6 on unit ball $\mathbf{D}^3$, which contains multiple horizons.Comment: 11page

Movement of Cryptosporidium parvum Oocysts through Soils without Preferential Pathways: Exploratory Test

Groundwater contamination by oocysts of the waterborne pathogen Cryptosporidium parvum is a significant cause of animal and human disease worldwide. Although research has been undertaken in the past to determine how specific physical and chemical properties of soils affect the risk of groundwater contamination by C. parvum, there is as yet no clear conclusion concerning the range of mobility of C. parvum that one should expect in field soils. In this context, the key objective of this research was to determine the magnitude of C. parvum transport in a number of soils, under conditions in which fast and preferential transport has been successfully prevented. C. parvum oocysts were applied at the surface of different soils and subjected to artificial rainfall. Apparently for the first time, quantitative PCR was used to detect and enumerate oocysts in the soil columns and in the leachates. The transport of oocysts by infiltrating water, and the considerable retention of oocysts in soil was demonstrated for all soils, although differences in the degree of transport were observed with soils of different types. More oocysts were found in leachates from sandy loam soils than in leachates from loamy sand soils and the retention of oocysts in different soils did not significantly differ. The interaction of various processes of the hydrologic system and biogeochemical mechanisms contributed to the transport of oocysts through the soil matrix. Results suggest that the interplay of clay, organic matter, and Ca2+ facilitates and mediates the transfer of organic matter from mineral surfaces to oocysts surface, resulting in the enhanced breakthrough of oocysts through matrices of sandy loam soils compared to those of loamy sand soils. Although the number of occysts that penetrate the soil matrix account for only a small percentage of initial inputs, they still pose a significant threat to human health, especially in groundwater systems with a water table not too distant from the soil surface. The results of the research demonstrate a critical need for the simultaneous study of the interaction of various processes affecting oocysts transport in the subsurface, and for its expansion into complex systems, in order to obtain a coherent picture of the behavior of C. parvum oocysts in soils

Theoretical Investigations of the Hexagonal Germanium Carbonitride

The structural, mechanical, elastic anisotropic, and electronic properties of hexagonal germanium carbonitride (h-GeCN) are systematically investigated using the first-principle calculations method with the ultrasoft pseudopotential scheme in the frame of generalized gradient approximation in the present work. The h-GeCN are mechanically and dynamically stable, as proved by the elastic constants and phonon spectra, respectively. The h-GeCN is brittle because the ratio B/G and Poisson’s ratio v of the h-GeCN are less than 1.75 and 0.26, respectively. For h-GeCN, from brittleness to ductility, the transformation pressures are 5.56 GPa and 5.63 GPa for B/G and Poisson’s ratio v, respectively. The h-GeCN exhibits the greater elastic anisotropy in Young’s modulus and the sound velocities. In addition, the calculated band structure of h-GeCN reveals that there is no band gap for h-GeCN with the HSE06 hybrid functional, so the h-GeCN is metallic

Study of Comprehensive Utilization of Water Resources of Urban Water Distribution Network

China is a country where the levels of water resources per capita are extremely low. With the rapid development of urbanization, water resource shortages have become a bottleneck existing in more and more cities. This study considers the comprehensive management of urban flood control, water supply, water and the ecological environment, catches the main contradiction between “water deficient” and “water rich” in cities, puts forward a comprehensive utilization pattern for urban water resources by emphasizing the utilization of rain–flood resources. After a simulation study, a better regulation pattern is brought out and achieve multiple benefits based on the river system of Gucheng Lake, which is located in Nanjing, Gaochun district, by optimizing conventional regulation. The results show that two parameters, the low water level (LWL) below which Gucheng Lake stops supplying ecological water, and the high water level (HWL) where Gucheng Lake stops importing water from rivers, are the key parameters to decide the regulation benefits, and the LWL of 9 m and HWL of 12 m is the best combination in river network regulation, the annual potential utilizable of rain–flood resources of Gucheng Lake river system can reach 57 million m3 per year, through the comprehensive utilization of the rain–flood resources, the negative effect of flood is effectively reduced and the disaster is controlled on one hand; and the water demand of urban and rural water supply, 100,000 m3/day, is effectively guaranteed as well as the regional ecological environment is improved on the other hand

Influence of Anionic Surfactant on Saturated Hydraulic Conductivity of Loamy Sand and Sandy Loam Soils

Surfactants released into the terrestrial environment in large amounts can potentially alter the physical, chemical and biological properties of soils, particularly the saturated hydraulic conductivity (Ks). Unfortunately findings regarding this process are quite limited. In this study, column tests were used to analyze the effects of Aerosol 22, a widely used anionic surfactant, on Ks of loamy sand and sandy loam soils. Solutions were injected into columns from the bottom with controlled pressure heads. Both the overall Ks of columns and the Ks of 6 layers at distances of 0–1 cm, 1–3 cm, 3–5 cm, 5–7 cm, 7–9 cm, and 9–10 cm from the bottom, were continuously monitored before and after the surfactant injections. Results showed that the overall Ks of all columns decreased after 2–4 pore volumes of the surfactant injections. However, stabilization and even increase at the beginning of the surfactant injection was also observed due to the different Ks variations in different layers. Specifically, a surfactant injection of 2–4 pore volumes continuously decreased the Ks of the 0–1 cm layers which yielded a Ks reduction of two orders of magnitude and dominated the Ks variations of the column. In contrast, an increase in the Ks of the 1–3 cm and 3–5 cm layers was more likely, while Ks variation of the 5–10 cm layers was less likely. We hypothetically attributed the Ks variations to the swelling of clay, the collapse of soil aggregates and subsequent particle displacements from surfactant adsorption, which caused pore clogging in the bottom 0–1 cm layer and higher porosities in the layers above. The adsorption of the surfactant aggregates and crystallization were also possibly thought to cause a pore clogging in the bottom layer thus decrease the surfactant concentration from the inlet, the severity of which affects these layers less at greater distances from the inlet. In view of the uncertainty showed by the experimental results, we also suggest to include more replicate columns in future studies, so as to increase the repeatability of the measurements

Tree Species Classification Using Optimized Features Derived from Light Detection and Ranging Point Clouds Based on Fractal Geometry and Quantitative Structure Model

Tree species classification is a ubiquitous task in the forest inventory field. Only directly measured feature vectors have been applied to most existing methods that use LiDAR technology for tree species classification. As a result, it is difficult to obtain a satisfactory tree species classification performance. To solve this challenge, the authors of this paper developed two new kinds of feature vectors, including fractal geometry-based feature vectors and quantitative structural model (QSM)-based feature vectors. In terms of fractal geometry, both two fractal parameters were extracted as feature vectors for reflecting how tree architecture is distributed in three-dimensional space. In terms of QSM, the ratio of length change and the ratio of radius change of different branches were extracted as feature vectors. To reduce the feature vector dimensionality and explore valuable feature vectors, feature vector dimension reduction was conducted using the classification and regression tree (CART). Five hundred and sixty-eight individual trees with five tree species were selected for evaluating the performance of the developed feature vectors. The experimental results indicate that the tree species of Fagus sylvatica achieved the highest overall accuracy, which is 98.06%, while Quercus petraea obtained the lowest overall accuracy, which is 96.65%. Four other classical supervised learning methods were adopted for comparison. The comparison result indicates that the proposed method outperformed the other four supervised learning methods no matter which accuracy indicator was adopted. In comparison with the relevant method, the eight feature vectors developed in this paper also performed much better. This indicates that the fractal geometry-based feature vectors and QSM-based feature vectors developed in this paper can effectively improve the performance of tree species classification