Chi-square-based scoring function for categorization of MEDLINE citations

Objectives: Text categorization has been used in biomedical informatics for identifying documents containing relevant topics of interest. We developed a simple method that uses a chi-square-based scoring function to determine the likelihood of MEDLINE citations containing genetic relevant topic. Methods: Our procedure requires construction of a genetic and a nongenetic domain document corpus. We used MeSH descriptors assigned to MEDLINE citations for this categorization task. We compared frequencies of MeSH descriptors between two corpora applying chi-square test. A MeSH descriptor was considered to be a positive indicator if its relative observed frequency in the genetic domain corpus was greater than its relative observed frequency in the nongenetic domain corpus. The output of the proposed method is a list of scores for all the citations, with the highest score given to those citations containing MeSH descriptors typical for the genetic domain. Results: Validation was done on a set of 734 manually annotated MEDLINE citations. It achieved predictive accuracy of 0.87 with 0.69 recall and 0.64 precision. We evaluated the method by comparing it to three machine learning algorithms (support vector machines, decision trees, na\"ive Bayes). Although the differences were not statistically significantly different, results showed that our chi-square scoring performs as good as compared machine learning algorithms. Conclusions: We suggest that the chi-square scoring is an effective solution to help categorize MEDLINE citations. The algorithm is implemented in the BITOLA literature-based discovery support system as a preprocessor for gene symbol disambiguation process.Comment: 34 pages, 2 figure

Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

The viscoelastic behavior of semi-crystalline polyamide 6,6 fiber is exploited in viscoelastically prestressed polymeric matrix composites. To understand better the underlying prestress mechanisms, strain–time performance of the fiber material is investigated in this work, under high creep stress values (330–665 MPa). A latch-based Weibull model enables prediction of the “true” elastic modulus through instantaneous deformation from the creep-recovery data, giving 4.6 ± 0.4 GPa. The fiber shows approximate linear viscoelastic characteristics, so that the time–stress superposition principle (TSSP) can be implemented, with a linear relationship between the stress shift factor and applied stress. The resulting master creep curve enables creep behavior at 330 MPa to be predicted over a large timescale, thus creep at 590 MPa for 24 h would be equivalent to a 330 MPa creep stress for ∼5200 years. Similarly, the TSSP is applied to the resulting recovery data, to obtain a master recovery curve. This is equivalent to load removal in the master creep curve, in which the yarns would have been subjected to 330 MPa creep stress for ∼4.56 × 107 h. Since our work involves high stress values, the findings may be of interest to those involved with long-term load-bearing applications using polyamide materials

An Analysis of the Publishing Activity of Keston Institute in the Context of its Last Three Years of Operation in Oxford (2003-2006)

By way of introduction, the study will give an outline of the history of Keston Institute (KI). It will then identify the period of three years (2003-2006) as the period during which KI attempted to integrate in the academic life of the Oxford University under the new director. The period ended with the effective closing down of the institution in its historical shape and with regard to many of its previous activities. On the surface this decision had to do with increasing financial difficulties, but it is the author\u27s contention that on another level it was an outcome of a clash of two differing views on the philosophy of KI\u27s mandate. The publishing output in the period under investigation will be singled out and analysed according to the temporal and geographical coverage of the contents of the KI publications. The conclusions will be shown to reflect the tensions present within KI in this period with regard to the possible future philosophy of research and the publishing policy of KI. One option which was advocating a wider geographical range and more contemporary topics (i.e. including the bulk of the former Eastern Europe, Europe in general but also North Korea and China) and, to some degree, a more overt use of the sociology of religion. The option eventually prevailed which supported a narrower perspective focusing on the topics dealing with the former Soviet Union, primarily Russia and the Ukraine, from a historical point of view, although also including some contemporary surveys (limited to that area). The study concludes with an outline of the subsequent (post-)history of KI which corroborates the results of the analysis and illustrates the practical outcomes of the decisions taken on the questions of research and publishing the journal between 2003-2005

Law of corresponding states for osmotic swelling of vesicles

As solute molecules permeate into a vesicle due to a concentration difference across its membrane, the vesicle swells through osmosis. The swelling can be divided into two stages: (a) an "ironing" stage, where the volume-to-area ratio of the vesicle increases without a significant change in its area; (b) a stretching stage, where the vesicle grows while remaining essentially spherical, until it ruptures. We show that the crossover between these two stages can be represented as a broadened continuous phase transition. Consequently, the swelling curves for different vesicles and different permeating solutes can be rescaled into a single, theoretically predicted, universal curve. Such a data collapse is demonstrated for giant unilamellar POPC vesicles, osmotically swollen due to the permeation of urea, glycerol, or ethylene glycol. We thereby gain a sensitive measurement of the solutes' membrane permeability coefficients, finding a concentration-independent coefficient for urea, while those of glycerol and ethylene glycol are found to increase with solute concentration. In addition, we use the width of the transition, as extracted from the data collapse, to infer the number of independent bending modes that affect the thermodynamics of the vesicle in the transition region.Comment: 10 page