10163897
Accelerating approximate subsequence search on large protein sequence databases
In this paper, we study the problem on how to build a persistent index structure for protein sequences to support approximate match. The suffix tree has been proposed as a solution to index sequence database and has been deployed on organizing DNA sequences (Hunt et al. (2001)). Unfortunately, it suffers from the problem of "memory bottleneck" that prevents it from being applied efficiently to a large database. The performance even degrades further for protein database due to a larger fanout at each node. Here, we employ an indexing structure, called BASS-tree, to support approximate match in sublinear time on a large protein database. We call this indexing method the sequence approximate match index method. The search of approximate matches can be properly directed to the portion in the database with a high potential of matching quickly. It is demonstrated in our experiments that the potential performance improvement is in an order of magnitude over alternative methods such as the BLAST algorithm and the suffix tree.
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.
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.
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.
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.
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.
8299246
HyLog: A High Performance Approach to Managing Disk Layout
Our objective is to improve disk I/O performance in multi-disk systems supporting multiple concurrent users, such as file servers, database servers, and email servers. In such systems, many disk reads are absorbed by large in-memory buffers, and so disk writes comprise a large portion of the disk I/O traffic. LFS (Log-structured File System) has the potential to achieve superior write performance by accumulating small writes into large blocks and writing them to new places, rather than overwriting on top of their old copies (called Overwrite). Although it is commonly believed that the high segment cleaning overhead of LFS makes it a poor choice for workloads with random updates, in this paper we find that because of the fast improvement of disk technologies, LFS significantly outperforms Overwrite in a wide range of system configurations and workloads (including the random update workload) under modern and future disks. 
 
LFS performs worse than Overwrite, however, when the disk space utilization is very high due to the high cleaning cost. In this paper, we propose a new approach, the Hybrid Log-structured (Hy-Log) disk layout, to overcome this problem. Hy-Log uses a log-structured approach for hot pages to achieve high write performance, and Overwrite for cold pages to reduce the cleaning cost. We compare the performance of HyLog to that of Overwrite, LFS and WOLF (the latest improvement on LFS) under various system configurations and workloads. Our results show that, in most cases, Hylog performs comparably to the best of the other three approaches.
6853966
Total chromatic number of planar graphs with maximum degree ten
42677463
Heterogeneous software reliability modeling
A number of Markov-based software reliability models have been developed for measuring software reliability. However, the application of these models is strictly limited to software that satisfies the Markov properties. The objective of our work is to expand the application domain of the Markov-based models, so that most software can be modeled and software reliability can be measured at the architecture level. To overcome the limitations of Markov properties, our model takes execution history into account and addresses both deterministic and probabilistic software behaviors. Each state represents the executions of one or more components depending on the architectural styles. In addition, the executions of one component are depicted by using distinctive states, when such executions are influenced by past states. Furthermore, we construct loops to eliminate the likelihood of unlimited state expansion and utilize a binomial tree structure to account for all the different execution paths. We show that Markov models are applicable even to software that does not fully satisfy the Markov properties. Therefore, we significantly improve the state of the art in architecture-based software reliability modeling.
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.
9810371
The edge-face choosability of plane graphs
A plane graph G is said to be k-edge-face choosable if, for every list L of colors satisfying |L(x)|=k for every edge and face x, there exists a coloring which assigns to each edge and each face a color from its list so that any adjacent or incident elements receive different colors. We prove that every plane graph G with maximum degree Δ(G) is (Δ(G)+3)-edge-face choosable.