A Set of Successive Job Allocation Models in Distributed Computing Infrastructures

The growing number of scientific computation-intensive applications calls for an efficient utilization of large-scale, potentially interoperable distributed infrastructures. Parameter sweep applications represent a large body of workflows. While the principle of workflows is easy to conceive, their execution is very complex and no universally accepted solution exists. In this paper we focus on the resource allocation challenges of parameter study jobs in distributed computing infrastructures. To cope with this NP-hard problem and the high uncertainty present in these systems, we propose a series of job allocation models that helps refining and simplifying the problem complexity. In this way we present some special cases that are polynomial and show how more complex scenarios can be reduced to these models. It is known from practice that a small number of job sizes improves the result of job allocation, therefore we state a hypothesis relying on this fact in one of our models. Unfortunately, the reduction of the general problem (using K-means clustering) did not help, and thus the hypothesis has proved to be false. In the future, we shall look for clustering techniques which fit this goal better.     

Frequent subgraph mining in outerplanar graphs

In recent years there has been an increased interest in frequent pattern discovery in large databases of graph structured objects. While the frequent connected subgraph mining problem for tree datasets can be solved in incremental polynomial time, it becomes intractable for arbitrary graph databases. Existing approaches have therefore resorted to various heuristic strategies and restrictions of the search space, but have not identified a practically relevant tractable graph class beyond trees. In this paper, we consider the class of outerplanar graphs, a strict generalization of trees, develop a frequent subgraph mining algorithm for outerplanar graphs, and show that it works in incremental polynomial time for the practically relevant subclass of well-behaved outerplanar graphs, i.e., which have only polynomially many simple cycles. We evaluate the algorithm empirically on chemo- and bioinformatics applications.     

The relative role of "A" level chemistry, physics and biology in the medical course

The performance of 209 students in the 2nd MBBS, first clinical year and final MBBS examinations has been compared retrospectively with their grades in chemistry, physics and biology at "A" level. The mean grade has also been determined for students from different social classes and secondary education. Significant differences in marks for biology were found between successful and not so successful students, especially in the pre-clinical part of the course. Significnat differences in marks and significant correlations were also found for physics but not to any great extent for chemistry. The relative role of these three basic sciences in the medical course is discussed. The suggestion is made that there is a need for a re-appraisal of the privleged position of chemistry and an unquestioned science requirement for entry to medical school.     

Investigating the intentional quality risks in public foundation projects: A Hong Kong study

Since foundation projects are one of the most complicated construction activities, many unforeseeable and invisible conditions and uncertainties will be investigated during the construction processes. The importance of examining risk management in foundation projects had pressing harder as short-piling experiences gained from the Hong Kong construction. Various types of quality risk should not be avoided throughout the construction development, including site condition, managerial and contractual factors. This paper identifies the typical factors affecting the three main categories defined in risk management in conducting foundation projects from various construction professionals. Intentional quality risk found to be difficult in handling the real responsibilities. This study will also present alternative solutions for controlling these quality risks and the effectiveness of these solutions has been tested. The findings from the study provide useful references to the construction industries.     

An investigation on the onset of plastic deformation of nanocrystalline solid solution Ti-Al-N films

The nanoscale deformation behavior of the solid solution Ti_0.5Al_0.5N thin film was systematically investigated by nanoindentation measurements. The effect of the tip radius of the indenter on the behavior of elastic-plastic deformation was also evaluated. The Hertzian stress analysis was used to determine the distribution of resolved shear stress at the initiate plastic deformation, and the obtained critical resolved shear stress was compared to the theoretical shear strength to establish correlations and differences. Comparison of the calculated critical shear stress and theoretical shear strength also indicated that new complete dislocation nucleation during nanoindentation was not the prerequisite of the onset of plastic deformation, even at very shallow indentation depth.     

Onset of severe nitrification in mildly nitrifying chloraminated bulk waters and its relation to biostability

Triggers of severe nitrification in distribution systems are still not clearly understood. Recently, the biostability concept was proposed to explain the chloramine residual below which signs of nitrification would be seen. To improve understanding, mildly nitrifying bulk water samples (nitrite less than 0.010mg-N/L) from Sydney Water distribution systems were incubated at constant temperatures and periodically analysed for nitrogenous compounds and total chlorine. Total ammoniacal nitrogen in the sample was between 0.25 and 0.35mg-N/L. Severe nitrification was triggered when chloramine residuals dropped below about 0.4mg/L - the critical threshold residual. In 45 such samples, the critical threshold residual was 0.2-0.65mg/L. The biostability concept was found to be useful in explaining the residual below which net growth of microorganisms begins. However, this alone could not predict the critical threshold residual. Different means of overcoming this problem are discussed. One of these is the use of the microbial decay factor method, since microbiologically assisted chloramine decay in the samples studied was found to be mostly the result of ammonia-oxidising bacterial activity. Nitrite levels in winter were found to be poor indicators of nitrifying status. Overall the results were found to be useful in controlling nitrification and to obtain early warning of severe nitrification.     

Zn2+ complexes of di- and tri-nucleating azacrown ligands as base-moiety-selective cleaving agents of RNA 3',5'-phosphodiester bonds: binding to guanine base

The ability of the dinuclear Zn2+ complex of 1,4-bis[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(1)) to promote the cleavage of the phosphodiester bond of dinucleoside-3',5'-monophosphates that contain a guanine base has been studied over a narrow pH range from pH 5.8 to 7.2 at 90 degrees C. Comparative measurements have been carried out by using the trinuclear Zn2+ complex of 1,3,5-tris[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(2)) as a cleaving agent and guanylyl-3',5'-guanosine (5'-GpG-3') as a substrate. The strength of the interaction between the cleaving agent and the starting material has been elucidated by UV spectrophotometric titrations. The speciation and binding mode have been clarified by potentiometric titrations with hydrolytically stable 2'-O-methylguanylyl-3',5'-guanosine and 1H NMR spectroscopic measurements with guanylyl-3',5'-guanosine. The results show that the guanine base is able to serve as a site for anchoring for the Zn2+-azacrown moieties of the cleaving agents L(1) and L(2), analogously to uracil base. The interaction is, however, weaker than with the uracil base and, hence, only the 5'-GpG-3' site (in addition to 5'-GpU-3' and 5'-UpG-3' sites) is able to markedly modulate the phosphodiester cleavage by the Zn2+ complexes of di- and trinucleating azacrown ligands containing an ether oxygen as a potential H-bond-acceptor site.