Ten Years after “Go West”

After thirty years’ reform, China has experienced unprecedented changes and prosperity. As is known to all, China’s Reform and Opening-up Policy was initiated along the coastal region. By the end of the 1990s, the gap between the east and the west has been expanded increasingly. The eastern region had been far ahead of the west, which embedded instability for the whole society. Facing this situation, at the 4th Session of the 15th Communist Party of China Meeting in September 1999, West Development, or Xibu Da Kaifa named in Chinese, was forwarded for the first time

Stab-Forests: Dynamic Data Structures for Efficient Temporal Query Processing

Many sources of data have temporal start and end attributes or are created in a time-ordered manner. Hence, it is only natural to consider joining datasets based on these temporal attributes. To do so efficiently, several internal-memory temporal join algorithms have recently been proposed. Unfortunately, these join algorithms are designed to join entire datasets and cannot efficiently join skewed datasets in which only few events participate in the join result. To support high-performance internal-memory temporal joins of skewed datasets, we propose the skip-join algorithm, which operates on stab-forests. The stab-forest is a novel dynamic data structure for indexing temporal data that allows efficient updates when events are appended in a time-based order. Our stab-forests efficiently support not only traditional temporal stab-queries, but also more general multi-stab-queries. We conducted an experimental evaluation to compare the skip-join algorithm with state-of-the-art techniques using real-world datasets. We observed that the skip-join algorithm outperforms other techniques by an order of magnitude when joining skewed datasets and delivers comparable performance to other techniques on non-skewed datasets

Structural characterizations of the navigational expressiveness of relation algebras on a tree

Given a document D in the form of an unordered node-labeled tree, we study the expressiveness on D of various basic fragments of XPath, the core navigational language on XML documents. Working from the perspective of these languages as fragments of Tarski's relation algebra, we give characterizations, in terms of the structure of D, for when a binary relation on its nodes is definable by an expression in these algebras. Since each pair of nodes in such a relation represents a unique path in D, our results therefore capture the sets of paths in D definable in each of the fragments. We refer to this perspective on language semantics as the "global view." In contrast with this global view, there is also a "local view" where one is interested in the nodes to which one can navigate starting from a particular node in the document. In this view, we characterize when a set of nodes in D can be defined as the result of applying an expression to a given node of D. All these definability results, both in the global and the local view, are obtained by using a robust two-step methodology, which consists of first characterizing when two nodes cannot be distinguished by an expression in the respective fragments of XPath, and then bootstrapping these characterizations to the desired results.Comment: 58 Page

PRELIMINARY STUDIES ON ECOLOGICAL DISTRIBUTION OF MICROORGANISMS IN WEST LAKE, HANGZHOU 2. Microorganisms in sediment

The abundance and distribution of microorganisms in the upper-layer sediment of West Lake were studied. Results showed that aerobic heterotrophic bacteria were 2.01 x 10⁵/g and actinomycetes were 1.83 x 10⁴/g on average. Both were more abundant in L. Yuehu. While the bacteria had negative correlation with the surrounding water temperature, actinomycetes had positive correlation. Aerobic cellulose decomposing bacteria were 1.88 x 10³/g on average, and more abundant in L. Xili and L. Yuehu L., peaking in July and May. Nitrite bacteria, nitrate bacteria, nitrate reducers and denitrifiers were 2.75 x 10⁵/g , 1.81 x 10⁵/g, 1.23 x 10⁵/g and 3.14 x 10³/g on average, respectively. Organic phosphorus decomposing bacteria were 2.38 x 10³/g on average, while calcium phosphate dissolving bacteria were very low. About 50.4% of heterotrophic bacteria were found to be Bacillus and about 23.9% were Enterobacteriaceae. Remain about 25.7% consisted of 11 other minor bacteria genus.Article信州大学理学部附属諏訪臨湖実験所報告 11: 59-66(1999)departmental bulletin pape