Toward Automatic Concurrent Debugging Via Minimal Program Mutant Generation with AspectJ

Debugging is one of the most time-consuming activities in program design. Work on automatic debugging has received a great deal of attention and there are a number of symposiums dedicated to this field. Automatic debugging is usually invoked when a test fails in one situation, but succeeds in another. For example, a test fails in one version of the program (or scheduler), but succeeds in another. Automatic debugging searches for the smallest difference that causes the failure. This is very useful when working to identify and fix the root cause of the bug.A new testing method instruments concurrent programs with schedule-modifying instructions to reveal concurrent bugs. This method is designed to increase the probability of concurrent bugs (such as races, deadlocks) appearing. This paper discusses integrating this new testing technology with automatic debugging. Instead of just showing that a bug exists, we can pinpoint its location by finding the minimal set of instrumentations that reveal the bug.In addition to explaining a methodology for this integration, we show an AspectJ-based implementation. We discuss the implementation in detail as it both demonstrates the advantage of the adaptability of open source tools and how our specific change can be used for other testing tools.     

Weak Convex Decomposition by Lines‐of‐sight

We define the convexity rank of a set of points to be the portion of mutually visible pairs of points out of the total number of pairs. Based on this definition of weak convexity, we introduce a spectral method that decomposes a given shape into weakly convex regions. The decomposition is applied without explicitly measuring the convexity rank. The method merely amounts to a spectral clustering of a matrix representing the all‐pairs line of sight. Our method can be directly applied on an oriented point cloud and does not require any topological information, nor explicit concavity or convexity measures. We demonstrate the efficiency of our algorithm on a large number of examples and compare them qualitatively with competitive approaches.     

The Synthesis,Crystal and Molecular Structure,and Oxidation State of Iron Complex from Pyridoxal Isonicotinoyl Hydrazone and Ferrous Sulphate

The reaction of isonicotinoyl hydrazone of pyridoxal (PIH), a biologically active iron-carrier, with FeSO₄-7H₂0 at pH ∼ 6 generates the delta, lamda species of the N,N-trans-O,O-cis-cis coordination isomer of an iron(III) complex with iron-to-ligand ratio of 1:2. The dark red-brown crystals are monoclinic, space group C2/c, with unit-cell dimensions a = 14.487(2), b = 18.586(2), c = 27.508(4) Å, β = 102.76(3)°, and Z = 8. The coordination around the metal is distorted octahedral and involves the protonated organic ligands, which are chelated through the phenolic oxygen [Fe-O1 1.941(6), Fe-O1′ 1.938(6)], an enolic form of the carbonyl oxygen [Fe-O3 2.017(6), Fe-O3′ 2.018(6)] and the azomethinic nitrogen [Fe-N2 2.133(8), Fe-N2′ 2.133(8)]. Packing is determined by systems of N-H….O and O-H….O hydrogen bonds involving the protonated pyridoxal nitrogens, the pyridoxal hydroxymethyl group, and the [SO₄]²⁻ group. The Mössbauer spectra at different temperatures (300 K, 88 K and 4.1 K) clearly prove that the iron atom in the complex is in a high-spin trivalent state.     

Efficient elections in chordal ring networks

We study the message complexity of the problem of distributively electing a leader in chordal rings. Such networks consist of a basic ring with additional links, the extreme cases being the oriented ring and the complete graph with a full sense of direction. We present a general election algorithm for these networks, and prove its optimality. As a corollary, we show thatO(logn) chords at each processor suffice to obtain an algorithm that uses at mostO(n) messages; this improves and extends a previous work, where an algorithm, also usingO(n) messages, was suggested for the case where alln-1 chords exist (the oriented complete network).     

Determination of oxidizing anions in explosive mixtures by phase transfer

Inorganic oxidizing agents are used in various explosive mixtures that are analysed by analytical chemists. Among them are dynamites, ANFO, black powder, match heads, pyrotechnical devices and home-made bombs. The crucial step in post explosion analysis is the extraction and purification of the explosive residues from the debris. A unique, fast and selective extraction technique for inorganic oxidizing agents is described in this paper. The debris are first extracted with water to yield an aqueous solution of the ions. Oxidizing anions such as nitrate and chlorate, are selectively transfered into the organic phase by the use of lipophilic quarternary ammonium cations. Other anions such as carbonate, sulphate and nitrite are not extracted into the organic phase under these conditions. The extracted anions are then identified by infra-red spectrometry and chemical spot tests.     

A parallel implementation of Flat Concurrent Prolog

Flat Concurrent Prolog is a simple, practical, concurrent programming language which has an efficient uniprocessor implementation. This paper describes an initial parallel implementation of the language; it consists of an interpreter implemented on an Intel iPSC Hypercube. The parallel execution of concurrent logic programming languages involves many nontrivial implementation problems. Some of these problems are well known and have been treated extensively in the literature. The most difficult task is to integrate problem solutions in a coherent and efficient manner. The algorithm presented has been useful in providing insights into the major problems and includes a number of novel ideas to simplify implementation. It does not attempt to solve all the problems involved but rather provides a workable basis for current and future research. The algorithm is under ongoing refinement, simplification and improvement.     

Prevalence of internalisation-associated gene, prtF1, among persisting group-A streptococcus strains isolated from asymptomatic carriers

BACKGROUND: The failure of antibiotic treatment to eradicate group-A streptococci in up to 30% of patients with pharyngotonsillitis is unexplained. Some strains of group-A streptococci can enter respiratory epithelial cells, where they would be inaccessible to antibiotics unable to penetrate the cell membrane, such as penicillins. The fibronectin-binding proteins, F1 and SfbI, are needed for this process. We hypothesised, therefore, that an intracellular reservoir of group-A streptococci could account, at least partly, for failure to eradicate throat carriage, and that the presence of the gene for fibronectin-binding protein (F1) might be linked to the ability of a strain to persist in the throat after therapy. METHODS: We investigated the frequency of prtF1-containing strains among 67 patients with pharyngotonsillitis. All patients were clinically cured, although 13 of them continued to carry group-A streptococci in the throat during or after therapy. To distinguish between persisting and recolonising strains, isolates from the 13 patients were serologically tested and compared by polymorphic DNA-amplification technique. FINDINGS: 12 (92%) of the 13 patients with symptomless carriage had prtF1-containing strains in the throat, compared with 16 (30%) of the 54 patients with successful eradication (p=0.0001). Three of the 13 eradication-failure patients were recolonised with strains that differed from the pretreatment strains. Nine of the ten (90%) persisting strains carried prtF1 (p=0.0009). INTERPRETATION: Our findings suggest that protein-F1-mediated entry to cells is involved in the causative process of the carriage state.