多维方法评价全氟辛酸对人结直肠癌细胞的毒性效应

全氟辛酸(PFOA)的暴露与溃疡性结肠炎的发生密切相关,但目前缺少PFOA暴露对人结直肠癌细胞(HCT116)产生毒性效应的相关分子机理研究。本研究从细胞毒性表型、细胞呼吸和代谢相关基因转录水平3个层次评价了PFOA对HCT116的毒性效应。首先,利用水溶性甲臜化合物(MTS)来评价PFOA暴露对HCT116细胞相对活性的影响;随后,利用细胞外流量分析仪对HCT116的线粒体呼吸活性进行测定;最后,用定量即时聚合酶链式反应(qPCR)对HCT116中代谢相关基因的转录水平进行检测。细胞毒性实验结果表明,与对照组相比,经高浓度(300 μmol/L)PFOA暴露48 h后,HCT116的细胞活性受到显著抑制(p<0.01),并在G0/G1细胞周期受到阻滞,而低浓度(30、50 μmol/L)的PFOA反而提高了细胞相对活性;低浓度(50 μmol/L)的PFOA能够促进HCT116的线粒体呼吸活性。利用自主开发的Metabolic Gene and Pathway Query检索软件和比较毒理基因组学数据库,本研究发现代谢相关基因二肽酶1(DPEP1)和鞘甘氨酸-1激酶(SPHK1)与PFOA引起的溃疡性结肠炎相关。qPCR实验结果表明,高浓度(300 μmol/L)PFOA能够显著诱导DPEP1和SPHK1的转录表达上调(约8~10倍),低浓度(50 μmol/L)PFOA未引起DPEP1和SPHK1转录表达水平的变化。本文发现细胞线粒体呼吸活性是评价低浓度PFOA干扰效应的一个敏感指标,DPEP1和SPHK1介导的细胞代谢过程可能是PFOA引起肠道毒性的潜在机制。     

基于Java APplet的Internet地图服务平台设计

;主要论述了网络环境下建立地图服务平台的设计思路与结构设计.在此基础上对矢量地图数据基本流程做了详细的论述,其中主要包括数据获取、数据压缩、数据传输、数据表达与空间查询等.基于Java语言.论文从底层实现了基于socket协议连接的服务器端与客户端地图数据的组织、传输与数据可视化表达,实现了网络地图发布平台.论文主要讨论了Java环境下具体地图服务平台设计.     

Extremal point queries with lines and line segments and related problems

We address a number of extremal point query problems when P is a set of n points in , d3 a constant, including the computation of the farthest point from a query line and the computation of the farthest point from each of the lines spanned by the points in P. In , we give a data structure of size O(n¹⁺), that can be constructed in O(n¹⁺) time and can report the farthest point of P from a query line segment in O(n^2/3+) time, where >0 is an arbitrarily small constant. Applications of our results also include: (1) Sub-cubic time algorithms for fitting a polygonal chain through an indexed set of points in , d3 a constant, and (2) A sub-quadratic time and space algorithm that, given P and an anchor point q, computes the minimum (maximum) area triangle defined by q with P{q}.     

Fraction auctions: The tradeoff between efficiency and running time

This paper studies the sales of a single indivisible object where bidders have continuous valuations. In Grigorieva et al. [14] it was shown that, in this setting, query auctions necessarily allocate inefficiently in equilibrium. In this paper we propose a new sequential auction, called the c-fraction auction. We show the existence of an ex-post equilibrium, called bluff equilibrium, in which bidders behave truthfully except for particular constellations of observed bids at which it is optimal to pretend a slightly higher valuation. We show c-fraction auctions guarantee approximate efficiency at any desired level of accuracy, independent of the number of bidders, when bidders choose to play the bluff equilibrium. We discuss the running time and the efficiency in the bluff equilibrium. We show that by changing the parameter c of the auction we can trade off efficiency against running time.     

From searching text to querying XML streams

XML data is queried with a limited form of regular expressions, in a language called XPath. New XML stream processing applications, such as content-based routing or selective dissemination of information, require thousands or millions of XPath expressions to be evaluated simultaneously on the incoming XML stream at a high, sustained rate. In its simplest approximation, the XPath evaluation problem is analogous to the text search problem, in which one or several regular expressions need to be matched to a given text. At a finer level, it is related to the tree pattern matching problem. However, unlike the traditional setting, the number of regular expressions here is much larger, while the “text” is much shorter, since it corresponds to the depth of the XML stream. In this paper we examine techniques that have been proposed for XML stream processing and describe a few open problems.     

Chromatic nearest neighbor searching: A query sensitive approach

The nearest neighbor problem is that of preprocessing a set P of n data points in so that, given any query point q, the closest point in P to q can be determined efficiently. In the chromatic nearest neighbor problem, each point of P is assigned a color, and the problem is to determine the color of the nearest point to the query point. More generally, given k1, the problem is to determine the color occurring most frequently among the k nearest neighbors. The chromatic version of the nearest neighbor problem is used in many applications in pattern recognition and learning. In this paper we present a simple algorithm for solving the chromatic k nearest neighbor problem. We provide a query sensitive analysis, which shows that if the color classes form spatially well separated clusters (as often happens in practice), then queries can be answered quite efficiently. We also allow the user to specify an error bound 0, and consider the same problem in the context of approximate nearest neighbor searching. We present empirical evidence that for well clustered data sets, this approach leads to significant improvements in efficiency.     

关于量子力学基础的一个质疑

本文对量子力学的基础提出了质疑,以一个常见的例子说明量予力学三个基本假设是不相容的.     

Heyting algebras with Boolean operators for rough sets and information retrieval applications

This paper presents an algebraic formalism for reasoning on finite increasing sequences over Boolean algebras in general and on generalizations of rough set concepts in particular. We argue that these generalizations are suitable for modeling relevance of documents in an information retrieval system.     

ARIES: A Visual Path in the Investigation of Statistical Data

Abstract

The massive flood of numbers in ongoing large-scale periodic economic and social surveys commonly leaves little time for anything but a cursory examination of the quality of the data, and few techniques exist for giving an overview of data activity. At the U.S. Bureau of Labor Statistics, a graphical and query-based solution to these problems has recently been adopted for data review in the Current Employment Statistics survey. Chief among the motivations for creating the new system were: (1) Reduce or eliminate the arduous paper review of thousands of sample reports by review analysts; (2) allow the review analysts a more global view of sample activity and at the same time make outlier detection less of a strain; and (3) present global views of estimates over time and among groups of subestimates. The specific graphics approaches used in the new system were designed to quickly portray both time series and cross-sectional aspects of the data, as these are both critical elements in the review process. The described system allows the data analysts to track down suspicious sample members by first graphically pinpointing questionable estimates, and then pinpointing questionable sample data used to produce those estimates. Query methods are used for cross-checking relationships among different sample data elements. Although designed for outlier detection and estimation, the data-representation methods employed in the system have opened up new possibilities for further statistical and economic uses of the data. The authors were torn between the desire for a completely automatic system of data review and the practical demands of an actual survey operating under imperfect conditions, and thus viewed the new system as an evolutionary advance, not as an ideal final solution. Possibilities opened up by the new system prompted some further thinking on finding an ideal state.