Multivariate adaptive regression splines for estimating riverine constituent concentrations

Regression-based methods are commonly used for riverine constituent concentration/flux estimation, which is essential for guiding water quality protection practices and environmental decision making. This paper developed a multivariate adaptive regression splines model for estimating riverine constituent concentrations (MARS-EC). The process, interpretability and flexibility of the MARS-EC modelling approach, was demonstrated for total nitrogen in the Patuxent River, a major river input to Chesapeake Bay. Model accuracy and uncertainty of the MARS-EC approach was further analysed using nitrate plus nitrite datasets from eight tributary rivers to Chesapeake Bay. Results showed that the MARS-EC approach integrated the advantages of both parametric and nonparametric regression methods, and model accuracy was demonstrated to be superior to the traditionally used ESTIMATOR model. MARS-EC is flexible and allows consideration of auxiliary variables; the variables and interactions can be selected automatically. MARS-EC does not constrain concentration-predictor curves to be constant but rather is able to identify shifts in these curves from mathematical expressions and visual graphics. The MARS-EC approach provides an effective and complementary tool along with existing approaches for estimating riverine constituent concentrations

Fractal analysis of 2D and 3D mesocracks in recycled aggregate concrete using X-ray computed tomography images

Recycled aggregates can introduce initial defects and damage to prepared concrete. Internal mesocrack formation is a fatal factor influencing the durable and mechanical properties of recycled aggregate concrete. In this study, the internal mesocracks of recycled aggregate concrete (RAC) under uniaxial compressive loading were virtually and quantitatively investigated by using the X-ray computed tomography (CT) technique. Statistical analysis was conducted on the number, length, width, tortuosity and density of mesocracks in RAC under critically damaged conditions. Then, these mesocracks were numerically extracted and restored to 2D images and 3D structures based on the digital matrix method for fractal geometry analysis. Fractal characteristics and multifractal spectra were used to analyse the mesocrack characteristics of RAC with different recycled coarse aggregate (RCA) replacement rates. The results show that the total number, width, tortuosity and density of mesocracks decrease with increasing RCA replacement rate. The mesocracks inside concrete have self-similarity characteristics, and the corresponding region is a multifractal body. It is feasible to quantitatively characterize mesocrack propagation in the fractal dimension. A clear correlation exists between the fractal dimension and RCA replacement rate: the higher the RCA replacement rate is, the lower the fractal dimension, and the less tortuous the mesocracks. The fractal dimension of mesocracks ranged from 1.19 to 1.32 and 2.18 to 2.39 for 2D images and 3D structures, respectively. Compared with ordinary concrete, the introduction of recycled aggregates leads to a maximum 10% reduction in fractal dimension. The multifractal spectrum effectively reflects the characteristics of mesocracks at different levels from the local to the global level. Although statistical results indicate that the mesocrack characteristics from 3D structures supply more accurate information than the description from 2D images, mesocracks obtained from 3D structures have fractal characteristics similar to those of 2D images

Acute cholecystitis associated with infection of Enterobacteriaceae from gut microbiota

AbstractAcute cholecystitis (AC) is one of the most common surgical diseases. Bacterial infection accounts for 50% to 85% of the disease's onset. Since there is a close relationship between the biliary system and the gut, the aims of this study were to characterize and determine the influence of gut microbiota on AC, to detect the pathogenic microorganism in the biliary system, and to explore the relationship between the gut and bile microbiota of patients with AC. A total of 185 713 high-quality sequence reads were generated from the faecal samples of 15 patients and 13 healthy controls by 16S rRNA gene pyrosequencing. Patients' samples were significantly enriched in Akkermansia, Enterobacter and Escherichia/Shigella group. The healthy controls, however, showed significant enrichment of Clostridiales, Coprococcus, Coprobacillaceae, Paraprevotella, Turicibacter and TM7-3 in their faecal samples. Escherichia coli was the main biliary pathogenic microorganism, among others such as Klebsiella spp., Clostridium perfringens, Citrobacter freundii and Enterobacter cloacae in the bile of the patients. Additionally, the amount of bile endotoxin significantly correlated with the number of Enterobacteriaceae, especially E. coli. Our data indicate that Enterobacteriaceae might play essential role in the pathogenesis and/or progress of AC. This was verified in an in vivo model using a pathogenic E. coli isolated from one of the patients in guinea pigs and observed marked gallbladder inflammation and morphologic changes. This study thus provides insight which could be useful for the prevention, diagnosis and treatment of AC and related diseases by controlling the growth of Enterobacteriaceae to alleviate the infection

Anchoring Bias in Online Voting

Voting online with explicit ratings could largely reflect people's preferences and objects' qualities, but ratings are always irrational, because they may be affected by many unpredictable factors like mood, weather, as well as other people's votes. By analyzing two real systems, this paper reveals a systematic bias embedding in the individual decision-making processes, namely people tend to give a low rating after a low rating, as well as a high rating following a high rating. This so-called \emph{anchoring bias} is validated via extensive comparisons with null models, and numerically speaking, the extent of bias decays with interval voting number in a logarithmic form. Our findings could be applied in the design of recommender systems and considered as important complementary materials to previous knowledge about anchoring effects on financial trades, performance judgements, auctions, and so on.Comment: 5 pages, 4 tables, 5 figure

Control the entanglement of two atoms in an optical cavity via white noise

Two two-level atoms within a leaky optical cavity is driven by two independent external optical white noise fields. We investigate how entanglement between two atoms arises in such a situation. The steady state entanglement of two atoms is also investigated. A stochastic-resonance-like behavior of entanglement is revealed. Finally, the Bell violation between atoms is discussed.Comment: 10 pages, 9 figure

Intersection of a domains in the c-domain matrix driven by electric field in tetragonal ferroelectric crystal

Domain structures in a tetragonal ferroelectric crystal were examined by transmission electron microscopy(TEM) before and after application of bipolar cyclic electric fields. Prior to the application of the bipolar field, the crystal was poled to an initial domain structure which consisted of a high volume fraction of c domains. Dispersed in the matrix of the c domains were two orthogonal sets of a-domain strips. These two sets of a-domain strips stayed apart to avoid direct contact. Upon application of bipolar cyclic electric fields, intersections of the a domains were observed in the ⟨001⟩-oriented tetragonal ferroelectric crystal. These intersections were formed as one set of the a domains grew under the influence of the in-plane electric field. As a result of the domain wall intersection, segments of the domain wall between two intersecting a domains carried excess electric charges. In the successive TEM examination, domain wall distortion and microcracks were found at these intersections