Invited commentary on Stewart and Davis " 'Big data' in mental health research-current status and emerging possibilities"

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Ontological theory for ontological engineering: Biomedical systems information integration

Software application ontologies have the potential to become the keystone in state-of-the-art information management techniques. It is expected that these ontologies will support the sort of reasoning power required to navigate large and complex terminologies correctly and efficiently. Yet, there is one problem in particular that continues to stand in our way. As these terminological structures increase in size and complexity, and the drive to integrate them inevitably swells, it is clear that the level of consistency required for such navigation will become correspondingly difficult to maintain. While descriptive semantic representations are certainly a necessary component to any adequate ontology-based system, so long as ontology engineers rely solely on semantic information, without a sound ontological theory informing their modeling decisions, this goal will surely remain out of reach. In this paper we describe how Language and Computing nv (L&C), along with The Institute for Formal Ontology and Medical Information Sciences (IFOMIS), are working towards developing and implementing just such a theory, combining the open software architecture of L&C’s LinkSuiteTM with the philosophical rigor of IFOMIS’s Basic Formal Ontology. In this way we aim to move beyond the more or less simple controlled vocabularies that have dominated the industry to date

Short Note: Report of mummified leopard seal carcass in the southern Dry Valleys, McMurdo Sound, Antarctica.

The wide spread occurrence of mummified seal and penguin carcasses tens of kilometres from the open ocean is an interesting phenomenon occurring in the Antarctic Dry Valleys. Mummified seal carcasses were first reported by Scott’s expedition in 1903 (Scott 1969), and live seals and seal carcasses have since been reported many kilometres from the nearest ice-free ocean. Seal carcasses found in the McMurdo Dry Valleys are predominantly crabeater seals (Lobodon carcinophaga (Hombron & Jacquinot)) with a smaller number of Weddell seals, (Leptonychotes weddellii (Lesson)), also reported. Here we present only the second published report of a leopard seal carcass from the McMurdo Dry Valleys

A Survey of Software Fault Tolerance Techniques

This report examines the state of the field of software fault tolerance. Terminology, techniques for building reliable systems, and fault tolerance are discussed. While a scientific consensus on the measurement of software reliability has not been reached, software systems are sufficiently pervasive that “software“ components of larger systems must be reliable, since dependence is placed on them. Fault tolerant systems utilize redundant components to mitigate the effects of component failures, and thus create a system which is more reliable than a single component. This idea can be applied to software systems as well. Several techniques for designing fault tolerant software systems are discussed and assessed qualitatively, where "software fault" refers to what is more commonly known as a bug. The assumptions, relative merits, available experimental results, and implementation experience are discussed for each technique. This leads us to some conclusions about the state of the field

Performance Analysis and Improvement in UNIX File System Tree Traversal

A utility program has been developed to aid UNIX system administrators in obtaining information about mounted file systems. The program gathers the information by a traversal of the accessible nodes in the file hierarchy; without kernel-recorded path names, this is the only way to dynamically determine mount-point names. The program has had three significant versions, the second and third of which were driven by performance requirements rather than functional requirements. The original version showed a factor of 7 improvements over the performance of a naive tree traversal. The second iteration showed a factor of 10 improvements over the previous version by using extra information about the structure of the file system tree to prune unnecessary branches from the traversal. The third iteration showed another factor of 3 improvements by changing the search strategy. The performance improvements depend on an analysis described in this report. Since the program's main task is traversal of a UNIX file system tree, our experience can be generalized to other such searches

Rapid location of mount points

"Mount points" allow more storage to be grafted into tree-structured hierarchical file systems. Administrative tasks use their locations, which are tabulated in a file. In our System V UNIX environment, this file was occasionally removed. Getmnt was written to recover the information. Getmnt has had three significant versions. The original version (getmntl) was a highly optimized naive tree traversal. Getmnt2 improved the real time performance by a mean factor of 7 by pruning unnecessary branches from the transversal. Getmnt3 doubled getmnt2' s speed, with a change from depth-first to breadth-first search. On our development system, getmnt1 required 647.6 seconds to run, while getmnt3 required 42.53 seconds

A Practical Course in Software Design

In practical disciplines, "Those who can, do. Those who can‘t, teach." and you "Learn by doing". Our presentation of an undergraduate semester course in Software Design, "Software Design Laboratory", has the spirit of the second adage and attempts to refute the first. In our description of the course, we focus on the relationship between the different programming assignments, and the role of these assignments in developing the student's capabilities, rather than on management, group structure, or formal techniques. We argue that a laboratory course is as essential to Computer Science as it is lo Physics or Chemistry

A Survey of Process Migration Mechanisms

We define process migration as the transfer of a sufficient amount of a process's state from one machine to another for the process to execute on the target machine. This paper surveys proposed and implemented mechanisms for process migration. We pay particular attention to the designer's goals, such as performance, load-balancing, and reliability. The effect of operating system design upon the ease of implementation is discussed in some detail; we conclude that message-passing systems simplify designs for migration

Automorphisms of quartic del Pezzo surfaces in characteristic zero

For each field $k$ of characteristic zero, we classify which groups act by automorphisms on a quartic del Pezzo surface over $k$. We also determine which groups act on $k$-rational, stably $k$-rational, or $k$-unirational quartic del Pezzo surfaces. For each group $G$ that is realized over $k$, we exhibit explicit equations for a quartic del Pezzo surface $X$ in $\mathbb{P}^4_k$ such that $G$ acts by automorphisms on $X$.Comment: 22 page