Complex networks have emerged as a simple yet powerful framework to represent and analyze a wide range of complex systems. The problem of ranking the nodes and the edges in complex networks is critical for a broad range of real-world problems because it affects how we access online information and products, how success and talent are evaluated in human activities, and how scarce resources are allocated by companies and policymakers, among others. This calls for a deep understanding of how existing ranking algorithms perform, and which are their possible biases that may impair their effectiveness. Well-established ranking algorithms (such as the popular Google's PageRank) are static in nature and, as a consequence, they exhibit important shortcomings when applied to real networks that rapidly evolve in time. The recent advances in the understanding and modeling of evolving networks have enabled the development of a wide and diverse range of ranking algorithms that take the temporal dimension into account. The aim of this review is to survey the existing ranking algorithms, both static and time-aware, and their applications to evolving networks. We emphasize both the impact of network evolution on well-established static algorithms and the benefits from including the temporal dimension for tasks such as prediction of real network traffic, prediction of future links, and identification of highly-significant nodes.Comment: 54 pages, 16 figure

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The role of sediment-bound organic phosphorus (Po) on lake eutrophication was studied using sequential extraction and enzymatic hydrolysis by collecting sediments from Dianchi Lake, China. Bioavailable Po species including labile monoester P, diester P, and phytate-like P were identified in the sequential extractions by H2O, NaHCO3, and NaOH. For the H2O-Po, 36.7% (average) was labile monoester P, 14.8% was diester P, and 69.9% was phytate-like P. In NaHCO3-Po, 19.9% was labile monoester P, 17.5% was diester P, and 58.8% was phytate-like P. For NaOH-Po, 25.6% was labile monoester P, 7.9% was diester P, and 35.9% was phytate-like P. Labile monoester P was active to support growth of algae to form blooms. Diester P mainly distributed in labile H2O and NaHCO3 fractions was readily available to cyanobacteria. Phytate-like P represents a major portion of the Po in the NaOH fractions, also in the more labile H2O and NaHCO3 fractions. Based on results of sequential extraction of Po and enzymatic hydrolysis, lability and bioavailability was in decreasing order as follows: H2O-Po > NaHCO3-Po > NaOH-Po, and bioavailable Po accounted for only 12.1-27.2% of total Po in sediments. These results suggest that the biogeochemical cycle of bioavailable Po might play an important role in maintaining the eutrophic status of lakes.

We investigated the vertical distributions of 239+240Pu and 137Cs activities and 240Pu/239Pu atom ratios in two lakes in northwestern China. The 240Pu/239Pu atom ratio from the Chinese nuclear test (CNT) site at Lop Nor is too complicated to identify the regional fallout source. However, radionuclides from the test site may be resolved mainly by the vertical distribution of radionuclides because there is no overlap between the global fallout peak and the local fallout peak. We analyzed Pu isotopes and 137Cs in sediments from two lakes (Sugan and Shuangta) located in northwestern China, near the CNT, and Lake Sihailongwan located in northeastern China to date recent lacustrine sediments and resolve global/local fallout sources. The apparently low 240Pu/239Pu atom ratio of 0.103 +/- 0.010 at Lake Sugan was likely representative of the fallout from the Lop Nor site. Our results also demonstrated that the 239+240Pu activity was more useful for recent chronology of lacustrine sediments, compared to 137Cs. Sediment accumulation rates of 0.651, 0.058-0.061, and 0.015 g x cm(-2) x a(-1) for sediment cores of Lake Shuangta, Lake Sugan and Lake Sihailongwan, respectively, were obtained by using the 239+240Pu fallout peak as a discrete time marker for 1964. The respective contributions of 137Cs and 239+240Pu from the CNT were estimated to be about 40 and 27% for Lake Sugan and 36 and 20% for Lake Shuangta. Plutonium isotopes in lacustrine sediments were proven to be useful for quantifying sediment accumulation rates and for source identification of the radioactive contamination.