Wang Wei

Bio: Wang Wei is an academic researcher from Fudan University. The author has contributed to research in topics: Inference & Relational database. The author has an hindex of 3, co-authored 17 publications receiving 32 citations.

Non-Almost-Derivable Frequent Itemsets Mining

Abstract: The number of frequent itemsets is often too large to handle, so it is very necessary to work out a condensed representation of the collection of all frequent itemsets. In this paper, we propose a new condensed representation called frequent non-almost-derivable itemsets. This representation is a subset of the original collection of frequent itemsets. For any removed itemset X (which is called an frequent almost-derivable itemset), we can derive a lower and an upper bound of its support from this representation, and the lower bound and the upper bound is close enough (can be controlled by a user-defined parameter). We also propose an apriori-like algorithm, which can extract all frequent non-derivable itemsets. Extensive empirical results on real datasets show the compactness and good approximation of this representation

Alleviative effects of exogenous CaCl2 on the inhibition of photosynthesis induced by heat stress in tobacco.

Abstract: 【Objective】 The effects of CaCl2 on photosynthesis and antioxidative enzyme activities in tobacco under high temperature stress were investigated to reveal the mechanism of external Ca2+ enhances the thermotolerance of tobacco plants.【Method】 The K326 tobacco plants were sprayed with different concentrations(0,10,20,30) of CaCl2 for four days,at the fifth day exposed to 43℃ for 2 hours,then returned to normal growth condition for one day recovery.Photosynthetic rate,chlorophyll fluorescence transients(OJIP),MDA content,H2O2 content and the activities of antioxidative enzymes were studied during the process.【Result】 Under heat stress,CaCl2 pretreatment greatly reduced the decrease in net photosynthesis rate(Pn) and maximum photochemical efficiency of PSⅡ(Fv/Fm).Moreover,it alleviated the damage of heat stress to electron transportation of PSII center and oxygen-evolving complex,so that the PSII could maintain high activity.CaCl2 pretreatment also greatly enhanced the activities of SOD,POD,CAT and APX,reduced the accumulation of H2O2,and thus,the active oxygen species were scavenged efficiently;the accumulation of final product of membrane lipid peroxidation(MDA) greatly decreased.The tobacco plants pretreated with 20 mmol·L-1 CaCl2 maintained the highest antioxidant enzymes activities and photosynthetic ability.【Conclusion】 CaCl2 pretreatment alleviated the heat stress damage to PSII center and oxygen evolving complex via enhancing the antioxidant enzymes activities,reducing the accumulation of H2O2 and protecting the membrane from peroxidation.Exogenous CaCl2 application enhanced thermotolerance of tobacco plants under high temperature stress.

Controlling FD and MVD Inferences in MLS

Abstract: In today's information society, privacy protection has become a very important concern. In this paper we research the inference problems due to functional dependencies (FD) and multi-valued dependencies (MVD) in multilevel secure database (MLS) with element classification instances. To deal with the secure problem brought by inference channels we present our FD and MVD based inference control algorithms working on the finest-grained data level which greatly improve the availability of data and minimize the information loss

Designing an Super-Peer Network

Abstract: A super-peer is a node in a peer-to-peer network that operates both as a server to a set of clients, and as an equal in a network of super-peers. Super-peer networks strike a balance between the efficiency of centralized search, and the autonomy, load balancing and robustness to attacks provided by distributed search. Furthermore, they take advantage of the heterogeneity of capabilities (e.g., bandwidth, processing power) across peers, which recent studies have shown to be enormous. Hence, new and old P2P systems like KaZaA and Gnutella are adopting super-peers in their design. Despite their growing popularity, the behavior of super-peer networks is not well understood. For example, what are the potential drawbacks of super-peer networks? How can super-peers be made more reliable? How many clients should a super-peer take on to maximize efficiency? we examine super-peer networks in detail, gaming an understanding of their fundamental characteristics and performance tradeoffs. We also present practical guidelines and a general procedure for the design of an efficient super-peer network.

Protection of Big Data Privacy

Abstract: In recent years, big data have become a hot research topic. The increasing amount of big data also increases the chance of breaching the privacy of individuals. Since big data require high computational power and large storage, distributed systems are used. As multiple parties are involved in these systems, the risk of privacy violation is increased. There have been a number of privacy-preserving mechanisms developed for privacy protection at different stages (e.g., data generation, data storage, and data processing) of a big data life cycle. The goal of this paper is to provide a comprehensive overview of the privacy preservation mechanisms in big data and present the challenges for existing mechanisms. In particular, in this paper, we illustrate the infrastructure of big data and the state-of-the-art privacy-preserving mechanisms in each stage of the big data life cycle. Furthermore, we discuss the challenges and future research directions related to privacy preservation in big data.

Rice Responses and Tolerance to High Temperature

Abstract: Climate change may increase storms, flooding and other harsh weather events and, thus, change geographical crop distribution, growing season and may also shorten the growth period. An approximately, 3–4°C increase in global mean temperature would decrease food productivity by altering various vital functions of plants. A rise in the optimum temperature (28/22°C) by about 1°C may led to a 10% decrease in rice yield. High temperatures (above 30°C) at lower altitudes in tropical regions and low temperatures (below 15°C) in the temperate regions adversely affect rice yield. Rice yield is estimated to shrink by 41% by the end of the 21st century because of heat stress (HS) through spikelet degradation, floral sterility, protein denaturation, loss of membrane integrity, enzyme inactivation, production of toxic compounds and reactive oxygen species. HS may disturb photosynthesis and respiration by altering the movement of water, ions and organic solutes across the cell. It also adversely affects physiological parameters (chlorophyll content, net photosynthetic rate, and RuBP carboxylase activity). High night temperature is comparatively more deleterious than high day temperature for rice. In rice heat tolerance (HT) is majorly comprises of escape or avoidance. Heat shock proteins and other stabilizing features play a vital role in rice HT by improving photosynthesis, partitioning of assimilate, nutrient and water use efficiency and membrane thermal stability. Similarly, the cyclic electron transport may also perform a vital role in rice thermo-tolerance. Based on available literature there is a need for more accurate knowledge and new heat-tolerant cultivars to minimize the adverse effects of climate change on rice quality and productivity.

Approximate weighted frequent pattern mining with/without noisy environments

Abstract: In data mining area, weighted frequent pattern mining has been suggested to find important frequent patterns by considering the weights of patterns. More extensions with weight constraints have been proposed such as mining weighted association rules, weighted sequential patterns, weighted closed patterns, frequent patterns with dynamic weights, weighted graphs, and weighted sub-trees or sub structures. In previous approaches of weighted frequent pattern mining, weighted supports of patterns were exactly matched to prune weighted infrequent patterns. However, in the noisy environment, the small change in weights or supports of items affects the result sets seriously. This may make the weighted frequent patterns less useful in the noisy environment. In this paper, we propose the robust concept of mining approximate weighted frequent patterns. Based on the framework of weight based pattern mining, an approximate factor is defined to relax the requirement for exact equality between weighted supports of patterns and a minimum threshold. After that, we address the concept of mining approximate weighted frequent patterns to find important patterns with/without the noisy data. We analyze characteristics of approximate weighted frequent patterns and run extensive performance tests.

Plant signaling: Understanding the molecular crosstalk

Abstract: Among abiotic factors, salinity and drought stress affect every aspect of plant from physiology to metabolic activities. Understanding of abiotic stress responses and signal transduction to control adaptive pathways is a crucial step in determining the plant resistance exposed to unfavorable environments. Molecular and genomic fi ndings have shown several changes in gene expression profi ling under drought and salt stresses in plants. Numbers of transcription factors which are accountable for inducing stress-responsive genes have been documented. To survive in adverse condition, plants have stress‐specifi c and adaptive responses which provide them necessary protection. Although, there are several signaling pathways and stress-responsive perceptions, some of which are defi nite in function, while others may have cross talk. Expressions of a large number of transcripts and genes are induced by these abiotic stresses in plants which facilitate stress tolerance and stress response. Recently, progress has been made in investigating the complex cascades of gene expression in stress responses. Knowledge about plant stress signaling is essential for the development of transgenic and improving breeding strategies in crops under stress environment. This chapter provides an outline of the common features of stress signaling in plants with some current studies on the functional analysis of signaling machineries under salt and drought stresses.