1166455
Comparing Graph Representations of Protein Structure for Mining Family-Specific Residue-Based Packing Motifs
We find recurring amino-acid residue packing patterns, or spatial motifs, that are characteristic of protein structural families, by applying a novel frequent subgraph mining algorithm to graph representations of protein three-dimensional structure. Graph nodes represent amino acids, and edges are chosen in one of three ways: first, using a threshold for contact distance between residues; second, using Delaunay tessellation; and third, using the recently developed almost-Delaunay edges. For a set of graphs representing a protein family from the Structural Classification of Proteins (SCOP) database, subgraph mining typically identifies several hundred common subgraphs corresponding to spatial motifs that are frequently found in proteins in the family but rarely found outside of it. We find that some of the large motifs map onto known functional regions in two protein families explored in this study, i.e., serine proteases and kinases. We find that graphs based on almost-Delaunay edges significantly reduce the number of edges in the graph representation and hence present computational advantage, yet the patterns extracted from such graphs have a biological interpretation approximately equivalent to that of those extracted from distance based graphs.
62615149
Mining Asynchronous Periodic Patterns in Time Series Data
Periodicy detection in time series data is a challenging problem of great importance in many applications. Most previous work focused on mining synchronous periodic patterns and did not recognize the misaligned presence of a pattern due to the intervention of random noise. In this paper, we propose a more flexible model of asynchronous periodic pattern that may be present only within a subsequence and whose occurrences may be shifted due to disturbance. Two parameters min/spl I.bar/rep and max/spl I.bar/dis are employed to specify the minimum number of repetitions that is required within each segment of nondisrupted pattern occurrences and the maximum allowed disturbance between any two successive valid segments. Upon satisfying these two requirements, the longest valid subsequence of a pattern is returned. A two-phase algorithm is devised to first generate potential periods by distance-based pruning followed by an iterative procedure to derive and validate candidate patterns and locate the longest valid subsequence. We also show that this algorithm cannot only provide linear time complexity with respect to the length of the sequence but also achieve space efficiency.
14969897
Dynamic adaptive file management in a local area network
In light of advances in processor and networking technology, especially the emergence of network attached disks, the traditional client-server architecture of file systems has become suboptimal for many computation/data intensive applications. We introduce a revised architecture for file management employing network attached storage: the dynamic file server environment (Dynamo). Dynamo introduces two main architectural innovations: to provide high scalability, the file management functions are mainly performed cooperatively by the clients in the system. Furthermore, data is transferred directly to the client's cache from network-attached disks, thus avoiding copies from a disk to the server buffer and then over the network to the client. Secondly, Dynamo uses a cooperative cache management which employs a decentralized lottery-based page replacement strategy. We show via performance benchmarks run on the Dynamo system and simulation results how this architecture increases the system's adaptability, scalability and cost performance.
28890
Extension of Lower Probabilities and Coherence of Belief Measures
Coherence is an important concept which is introduced and discussed in a new mathematics branch, Imprecise Probability Theory. By using the Choquet integral, belief measures can be extended to be coherent lower previsions on the linear space consisting of all bounded functions. As a special case, we establish that all belief measures are coherent imprecise probabilities.
19868872
Management Assistance for Work First via a Dynamic Website
The purpose of the Work First project is to assist the state Dept. of Health and Human Services (DHHS) staff and each county Dept. of Social Services (DSS) across the state in the management of welfare reform initiatives. Work First is the cash assistance program in NC. One important objective is to encourage and support program managers to use data on outcomes to assess their performance. This is accomplished by providing them with easy to use and easy to understand comprehensive information on the experiences of families and individuals that have received assistance through their agency over time.
11841640
Accelerating Profile Queries in Elevation Maps
Elevation maps are a widely used spatial data representation in geographical information systems (GIS). Paths on elevation maps can be characterized by profiles, which describe relative elevation as a function of distance. In this research, we address the inverse of this mapping - given a profile, how to efficiently find paths that could have generated it. This is called the profile query problem. Profiles have a wide variety of uses that include registering tracking information, or even other maps, to a given map. We describe a probabilistic model to characterize the maximal likelihood that a point lying on a path matches the query profile. Propagation of such probabilities to neighboring points can effectively prune the search space. This model enables us to efficiently answer queries of arbitrary profiles with user-specified error tolerances. When compared to existing spatial index methods, our approach supports more flexible queries with orders of magnitude speedup.
8724139
News Content Highlight via Fast Caption Text Detection on Compressed Video
Captions present in video frames play an important role in understanding video content. This paper presents a fast algorithm to automatically detect captions in MPEG compressed video. It is based on statistics features of caption text's chrominance components. The paper also discusses its principle and speed-up mechanism in detail. We have successfully exploited the technique to automatically construct the pictorial catalogue, a new content representation. Experiment results show the proposed caption detection algorithm has not only the ideal accuracy 96.6% and recall 100%, but also a detection speed of faster than real time.
83220
Defending against wormhole attacks in mobile ad hoc networks
In ad hoc networks, malicious nodes can deploy wormhole attacks to fabricate a false scenario on the proximity relationship among mobile nodes. A classification of the attacks according to the format of the wormholes is proposed. This forms a basis to identify the detection capability of various approaches. An analysis shows that earlier approaches focus on the prevention of wormholes among neighbors that trust each other. As a more generic approach, we present an end-to-end scheme that can detect wormholes on a multi-hop route. Only the trust between the source and the destination is assumed. The mechanism uses geographic information to detect anomalies in neighbor relations and node movements. To reduce the computation and storage overhead, we present a scheme called cell-based open tunnel avoidance (COTA) to manage the information. COTA requires a constant space for every node on the path and the computation overhead increases linearly to the number of detection packets. We prove that the savings do not deteriorate the detection capability. Various schemes to control communication overhead are studied. The simulation and experiments on real devices show that the proposed mechanism can be combined with existent routing protocols to defend against wormhole attacks. Copyright © 2006 John Wiley & Sons, Ltd.
20701407
A General Structure of Feedback Shift Registers for Built-In Self Test
A mixed-type feedback shift register (MFSR) is simi lar to a linear feedback shift register (LFSR) except that the connection between two consecutive flip-flops (F/F's) may be through the Q or output, and an extra inver ter may exist at the input to the first flip-flop (stage) of the register. In this p aper, we exploit the properties of MFSR's and show that by using an MFSR based pseudorandom pattern generator (PRPG) or multiple input signature analyzer (MISA), several good features for built-in self test can be obtained. Specifically w e show that: (1) for any given initial seed, an MFSR always exists that can generate the s ame serial output sequence as can an LFSR with the same characteristic polynomial and any initial seed; (2) for any MFSR, we can always find an initial seed for this M FSR such that it can generate the same serial output sequence as can an LFSR with the same characteristic polynomial and any initial seed; and (3) for any given initial seed and any test response to be compressed, an MFSR based MISA can usually be found that will result in any required final signature. If such an MFSR cannot b e found for a specific initial seed and a specific test response sequence, we show that by simply adding one arbitrary dummy pattern to the test response, one can always find the required MFSR. We also show that if the characteristic polynomial of the MFSR based MISA can be chosen freely, it is almost guaranteed that a feasi ble MFSR can be found without adding any dummy patterns to the test response. Fo r example, for a 16-stage MISA, the probability that a feasible MFSR does not exist is less than 2-32768.
11973783
Answering Approximate Range Aggregate Queries on OLAP Data Cubes with Probabilistic Guarantees
Approximate range aggregate queries are one of the most frequent and useful kinds of queries for Decision Support Systems (DSS). Traditionally, sampling- based techniques have been proposed to tackle this problem. However, its effectiveness will degrade when the underlying data distribution is skewed. Another approach based on the outlier management can limit the effect of data skew but fails to address other requirements of approximate range aggregate queries, such as error guarantees and query processing efficiency. In this paper, we present a technique that provide approximate answers to range aggregate queries on OLAP data cubes efficiently with theoretical error guarantees. Our basic idea is to build different data structures for outliers and the rest of the data. Experimental results verified the effectiveness of our proposed methods.
41898252
Vertex-pancyclicity of edge-face-total graphs
The edge-face-total graph r(G) of a plane graph G is the graph defined on the vertex set E(G)∪F(G) so that two vertices in r(G) are joined by an edge if and only if they were adjacent or incident in G. In this paper we prove that (1) the edge-face-total graph of a 2-connected plane graph is vertex-pancyclic and there exists a connected plane graph G with cut vertices such that r(G) is non-Hamiltonian; (2) the line graph of a 2-connected plane graph with at most one face of degree ⩾4 is pancyclic.