18143878
Compiling Parallel Lisp for a Shared Memory Multiprocessor
There is a commonly held idea that although Lisp is a good language for prototyping and software development, it is often too inefcient to be useful in actual implementation. Advances in compiling Lisp have begun to change this notion. However, the situation is less clear in the case of parallel Lisp dialects. In this paper, we report on our experience in implementing a compiler for a parallel Lisp dialect we called BaLinda Lisp for a shared memory multiprocessor. For a class of problems, our compiler was able to achieve performances on Lisp programs that are near, if not equal to, their imperative (C) equivalents. However, on other problems, the situation is less than ideal. We investigate this phenomenum and outline the future challenges in realizing a production strength parallel Lisp compiler.
19382997
Fast Evaluation of the Elementary Functions in Single Precision
In this paper we introduce a new method for the fast evaluation of the elementary functions in single precision based on the evaluation of truncated Taylor series using a difference method. We assume the availability of large and fast (at least for read purposes) memory. We call this method the ATA (Add-Table lookup-Add) method. As the name implies, the hardware required for the method are adders (both two/ and multi/operand adders) and fast tables. For IEEE single precision numbers our initial estimates indicate that we can calculate the basic elementary functions, namely reciprocal, square root, logarithm, exponential, trigonometric and inverse trigonometric functions, within the latency of two to four floating point multiplies. >
26732405
BaLinda Lisp: Design and Implementation
BaLinda Lisp is a parallel Lisp dialect employing a shared memory model of parallel processing together with a subset of the Linda tuple space operators. Also included in the design is speculative processing. The aim is to have shared memory multiprocessing with the tuple space acting as the main data structure through which synchronization is done. The result is a flexible programming language. In this paper, we shall describe the design philosophy of BaLinda Lisp, discuss its implementation on three multiprocessing platforms, give examples of programs written in BaLinda Lisp and discuss future work on the language.
16853040
Local Orientation Smoothness Prior for Vascular Segmentation of Angiography
We present a new generic method for vascular segmentation of angiography. Angiography is used for the medical diagnosis of arterial diseases. To facilitate an effective and efficient review of the vascular information in the angiograms, segmentation is a first stage for other post-processing routines. The method we propose uses a novel a priori — local orientation smoothness prior — to enforce an adaptive regularization constraint for the vascular segmentation within the Bayes’ framework. It aspires to segment a variety of angiographies and is aimed at improving the quality of segmentation in low blood flow regions. Our algorithm is tested on numerical phantoms and clinical datasets. The experimental results show that our method produces better segmentations than the maximum likelihood estimation and the estimation with a multi-level logistic Markov random field model. Furthermore, the novel algorithm produces aneurysm segmentations comparable to the manual segmentations obtained from an experienced consultant radiologist.
16024151
An adaptable architecture for secure delivery of converged services
We present an approach for secure delivery of multimodal services to end users over heterogeneous converged networks. Our approach leads to an easily adaptable and extensible system architecture, in which system components interact with each other through loosely coupled interfaces based on asynchronous exchange of messages. It also effectively separates service logic from service delivery, through the introduction of a secure broker between the end user devices and the enterprise level application that contains the service logic. This separation also provides additional levels of security at the application level. This paper describes how our approach provides the features mentioned above. We have also validated our approach through the implementation of a prototype system, a description of which is also provided.
18768398
Coverage testing of Java programs and components
Although software testing is a crucial activity in the software development process, only recently have more sound and consistent testing tools become available for testing Java programs and their components. These tools support mostly functional and control-flow based structural criteria. In this paper we explore control-flow and data-flow based coverage criteria to support the testing of Java programs and/or components. We also describe a testing tool, named JaBUTi, which can be used by both the component developer and the component user to test Java-based components and/or systems. To achieve this goal, the tool works at the bytecode level such that no source code is required during the testing activity. We illustrate these ideas and concepts with an example extracted from the literature.
6423442
Rule-based anomaly pattern detection for detecting disease outbreaks
This paper presents an algorithm for performing early detection of disease outbreaks by searching a database of emergency department cases for anomalous patterns. Traditional techniques for anomaly detection are unsatisfactory for this problem because they identify individual data points that are rare due to particular combinations of features. When applied to our scenario, these traditional algorithms discover isolated outliers of particularly strange events, such as someone accidentally shooting their ear, that are not indicative of a new outbreak. Instead, we would like to detect anomalous patterns. These patterns are groups with specific characteristics whose recent pattern of illness is anomalous relative to historical patterns. We propose using a rule-based anomaly detection algorithm that characterizes each anomalous pattern with a rule. The significance of each rule is carefully evaluated using Fisher's Exact Test and a randomization test. Our algorithm is compared against a standard detection algorithm by measuring the number of false positives and the timeliness of detection. Simulated data, produced by a simulator that creates the effects of an epidemic on a city, is used for evaluation. The results indicate that our algorithm has significantly better detection times for common significance thresholds while having a slightly higher false positive rate.
28915962
Reducing the cost of mutation testing: An empirical study
Of the various testing strategies, mutation testing has been empirically found to be effective in detecting faults. However, mutation often imposes unacceptable demands on computing and human resources because of the large number of mutants that need to be compiled and executed on one or more test cases. In addition, the tester needs to examine many mutants and analyze these for possible equivalence with the program under test. For these reasons, mutation is generally regarded as too expensive to use. Because one significant component of the cost of mutation is the execution of mutants against test cases, we believe that this cost can be reduced dramatically by reducing the number of mutants that need to be examined. We report results from a case study designed to investigate two alternatives for reducing the cost of mutation. The alternatives considered are randomly selected x% mutation and constrained abs/ror mutation. We provide experimental data indicating that both alternatives lead to test sets that distinguish a significant number of nonequivalent mutants and provide high all-uses coverage.