Degree correlation effect of bipartite network on personalized recommendation

In this paper, by introducing a new user similarity index base on the diffusion process, we propose a modified collaborative filtering (MCF) algorithm, which has remarkably higher accuracy than the standard collaborative filtering. In the proposed algorithm, the degree correlation between users and objects is taken into account and embedded into the similarity index by a tunable parameter. The numerical simulation on a benchmark data set shows that the algorithmic accuracy of the MCF, measured by the average ranking score, is further improved by 18.19% in the optimal case. In addition, two significant criteria of algorithmic performance, diversity and popularity, are also taken into account. Numerical results show that the presented algorithm can provide more diverse and less popular recommendations, for example, when the recommendation list contains 10 objects, the diversity, measured by the hamming distance, is improved by 21.90%.Comment: 9 pages, 3 figure

Clinical value of preferred endoscopic ultrasound-guided antegrade surgery in the treatment of extrahepatic bile duct malignant obstruction

Objectives: To explore the clinical value of preferred ultrasound endoscopic guided biliary drainage in patients with extrahepatic biliary obstruction with intrahepatic biliary ectasis. Methods: A total of 58 patients with malignant obstruction and intrahepatic bile duct expansion, including 32 males, 26 females and median age 65 (58‒81) were selected. A prospective randomized controlled study was randomized into EUS-AG and ERCP-BD, with 28 patients in EUS-AG and 30 in ERCP-BD. The efficacy of the two treatments, operation success rate, operation time, the incidence of complications, hospitalization days, cost, unimpeded stent duration, and survival time were compared. Results: 1) The surgical success rate in group EUS-AG was 100%, and in group, ERCP-BD was 96.67%. There was no statistical difference in surgical success rate in the two groups (p>0.05). 2) Average operating time in EUS-AG was (23.69±11.57) min, and in ERCP-BD was (36.75±17.69) min. The difference between the two groups has statistical significance (p<0.05). 3) The clinical symptoms of successful patients were significantly relieved. Compared with the preoperative procedure, the differences in group levels had statistical significance (p<0.05); TBIL, ALP, WBC and CRP levels, no statistical significance difference in groups (p>0.05). Conclusion: EUS-AG operation has short time, low incidence of complications, safe, effective, and can be used as the preferred treatment plan for patients with extrahepatic biliary duct malignant obstruction associated with intrahepatic biliary duct expansion; EUS-AG operation has more unique clinical advantages for patients with altered gastrointestinal anatomy or upper gastrointestinal obstruction

Impact Of Urbanization On Spatial And Temporal Variation Of Rainfall In Beijing Over The Last 50 Years

Rainfall is one of the key terms involved in many hydrological processes, and it is particularly important in the field of urban hydrology. It is well known that urbanization can have potential impact on precipitation process due to the changes it causes to the ground roughness, thermal-dynamics and many other factors. In this study, the focus is set on the impact on the precipitation patterns in Beijing in term of spatial and temporal variation, from the urbanization over last 50 years in which time the fast and continuous expansion of the city at dramatic scales, the rapid growth of residents population as well as human activities especially building of ground constructions, collectively and inevitably bring changes to the local climatic characteristics of the urbanized areas. This study looks at the two periods according to the speed of urbanization, namely the slow urbanization period of 1957-1980 and the fast urbanization period of 1981-2010. Rainfall data collected from the representative rain gauges across the region is used to analyze the spatial and temporal variation over these two periods. The results show that precipitation in urban areas exhibits the characteristics of higher intensity, shorter duration, with the rainfall mainly concentrated in 60 min or so. Local short-duration rainstorms tend to occur more frequently. Compared with suburban areas, urbanization has significant effect, especially on short-duration precipitation events evidenced by remarkable difference between the coefficients of variation of urban rainfall and those of the suburbs. In addition, for the fast urbanization period, the spatially localized, highly intensive rainfall events are found to be more frequent. Therefore, urbanization of the city has caused increase of the strong convective weather and pressure of flood control drainage, which should be paid more attentions to in city planning

Single-step separation scheme and high-precision isotopic ratios analysis of Sr–Nd–Hf in silicate materials

Thermal ionization mass spectrometry and multiple-collector inductively coupled plasma mass spectrometry are considered to be “gold standards” for the determination of the isotope ratios of Sr–Nd and Hf in geological samples because of the extremely high precision and accuracy of these methods. However, the sample throughputs are hindered by time-consuming and tedious chemical procedures. Three-step ion exchange resin separation is traditionally employed to purify Sr–Nd–Hf from matrix elements. In this study, a one-step Sr–Nd–Hf separation scheme was developed to process geological samples. The separation scheme is based on the combined use of conventional AG50W-X12 cation-exchange resin and LN Spec extraction chromatographic material without any intervening evaporation step. The protocol not only prevents cross-contamination during operation using multiple-stage ion exchange resins but also significantly improves the efficiency of sample preparation. The stability of our chemical procedure was demonstrated by replicate measurements of 87Sr/86Sr, 143Nd/144Nd, and 176Hf/177Hf ratios in six international reference materials of silicate rocks. The analytical results obtained for these standard rocks compare well with the published data. The external reproducibility (2 SD, n = 10) of a BCR-2 standard sample was ±0.000018 for 87Sr/86Sr, ±0.000010 for 143Nd/144Nd, and ±0.000014 for 176Hf/177Hf