Visualization of rhythm, time and metre

Developments in the theory of auditory processing of rhythmic signals have enabled the construction of a robust algorithm for recovery of rhythmic grouping structure. This algorithm appears to be effective for both speech and music signals. The theory upon which the algorithm was based was inspired by the theory of edge detection in vision. The output of the algorithm can be visualised in the form of a rhythmogram, examples of which are shown for a variety of speech signals. The relationship between rhythm, time perception and metre is discussed in the light of a recent auditory-motor theory of beat induction.     

An empirical comparison between stochastic and deterministic centroid initialisation for K-means variations

Machine Learning - K-Means is one of the most used algorithms for data clustering and the usual clustering method for benchmarking. Despite its wide application it is well-known that it suffers...     

Methods for handling uncertainty within pharmaceutical funding decisions

This article provides a position statement regarding decision making under uncertainty within the economic evaluation of pharmaceuticals, with a particular focus upon the National Institute for Health and Clinical Excellence context within England and Wales. This area is of importance as funding agencies have a finite budget from which to purchase a selection of competing health care interventions. The objective function generally used is that of maximising societal health with an explicit acknowledgement that there will be opportunity costs associated with purchasing a particular intervention. Three components of uncertainty are discussed within a pharmaceutical funding perspective: methodological uncertainty, parameter uncertainty and structural uncertainty, alongside a discussion of challenges that are particularly pertinent to health economic evaluation. The discipline has focused primarily on handling methodological and parameter uncertainty and a clear reference case has been developed for consistency across evaluations. However, uncertainties still remain. Less attention has been given to methods for handling structural uncertainty. The lack of adequate methods to explicitly incorporate this aspect of model development may result in the true uncertainty surrounding health care investment decisions being underestimated. Research in this area is ongoing as we review.     

信息系统定性与定量研究方法的哲学基础

我国一部分有关信息系统研究的文献还停留在运用实证分析的方法测试国外学者的观点及其建立的理论模型这一层面上。这些植根于欧美发达国家社会环境中的理论和模型,不能够完全适应中国目前高速发展的经济环境和社会文化环境。本文从信息系统研究的哲学基础出发,论证定量和定性这两种方法的不同。针对某些研究者青睐定量研究方法这一现象,提出定量或者定性方法的选择应基于哲学的角度,准确地辨别研究对象的差异,针对不同研究目的、需求和研究环境,选择正确的研究方法和途径,从而充分发挥定量和定性研究方法的优势,建立适合于我国经济发展现状的理论模型。     

Supercritical fluid extraction of coal-tar pitch: Part 2. Extraction of the lower molecular weight species with aliphatic solvents

Extraction of coal-tar pitches has been carried out with a number of aliphatic hydrocarbons at temperatures between 210°C and 300°C and pressure of 10 or 15 MPa resulting in extraction yields of up to 50%. The toluene-insoluble (TI) content, molecular weight and the rate of mesophase formation of the residual (refined) pitches increase as the extraction yield increases. The molecular weight of the extract also increases with extraction yield. The volatiles produced during mesophase formation from a supercritical hexane-extracted pitch were analysed by NMR and mass spectrometry and were similar to the hexane extract.     

Vesicle Fusion as a Target Process for the Action of Sphingosine and Its Derived Drugs

The fusion of membranes is a central part of the physiological processes involving the intracellular transport and maturation of vesicles and the final release of their contents, such as neurotransmitters and hormones, by exocytosis. Traditionally, in this process, proteins, such SNAREs have been considered the essential components of the fusion molecular machinery, while lipids have been seen as merely structural elements. Nevertheless, sphingosine, an intracellular signalling lipid, greatly increases the release of neurotransmitters in neuronal and neuroendocrine cells, affecting the exocytotic fusion mode through the direct interaction with SNAREs. Moreover, recent studies suggest that FTY-720 (Fingolimod), a sphingosine structural analogue used in the treatment of multiple sclerosis, simulates sphingosine in the promotion of exocytosis. Furthermore, this drug also induces the intracellular fusion of organelles such as dense vesicles and mitochondria causing cell death in neuroendocrine cells. Therefore, the effect of sphingosine and synthetic derivatives on the heterologous and homologous fusion of organelles can be considered as a new mechanism of action of sphingolipids influencing important physiological processes, which could underlie therapeutic uses of sphingosine derived lipids in the treatment of neurodegenerative disorders and cancers of neuronal origin such neuroblastoma.     

A model for a mechanical equation of state under continuously changing conditions of hot deformation

A simple model, which takes into account the combined effects of dislocation climb and glide has been developed. In the extreme case when climb is slower than glide, the model predicts the direct transients observed in pure metals and class II alloys and in the other extreme case, when glide is slower than climb, the inverse transients observed in class I alloys. In the intermediate situation, when the velocity of climb is of the same order of magnitude as the velocity of glide, the model gives very small transients in flow stress even with large changes in strain rate. Under such conditions, the observed occurrence of a mechanical equation of state in two alloys: a ferritic stainless steel and an aluminium 1% magnesium alloy, under continuously changing strain rate conditions can be explained. The model also explains that a practical mechanical equation of state can be followed without the simultaneous existence of a microstructural equation of state, because it predicts that a change in flow stress can occur even without an appreciable change in the microstructure.     

Phase measurements in MAESTRO polarimetric data from the U.K. test sites

Tests using MAESTRO data from the Reedham and Feltwell test sites suggest that the assumptions of a multi-variate complex zero-mean Gaussian distribution for scattering am litudes and a linear distortion model for polarimetric data lead to a viable model for C-band observations, though with some deviations between theory and measurements. P·band observations arc in general not consistent with this data model. When viable, the Gaussian model provides a basis for defining phase information, and has implications for the statistical measures which should be used to do so. The usual mean and standard deviation sta istics arc shown to have undesirable characteristics when applied to phase measurements. The effects of calibration and noise on phase measurements from distributed targets arc discussed, and other system effects on phase arc noted. Analysis of phase data from fields at the Feltwell test site shows that at C band the copolarized phase difference can discriminate between different crop types, but not at P band.     

The Hsp90/Cdc37p chaperone system is a determinant of molybdate resistance in Saccharomyces cerevisiae

Saccharomyces cerevisiae lacks enzymes that contain the molybdopterin co‐factor and therefore any requirement for molybdenum as a trace mineral supplement. Instead, high molybdate levels are inhibitory to its growth. Low cellular levels of heat shock protein 90 (Hsp90), an essential chaperone, were found to enhance this sensitivity to molybdate. Certain Hsp90 point mutations and co‐chaperone protein defects that partially compromise the function of the Hsp90/Cdc37p chaperone system also rendered S. cerevisiae hypersensitive to high molybdate levels. Sensitivity was especially apparent with mutations close to the Hsp90 nucleotide binding site, with the loss of the non‐essential co‐chaperone Sti1p (the equivalent of mammalian Hop), and with the abolition of residue Ser14 phosphorylation on the essential co‐chaperone Cdc37p. While it remains to be proved that these effects reflect direct inhibition of the Hsp90 of the cell by the MoO₄²⁺ oxyanion in vivo; this possibility is suggested by molybdate sensitivity arising with a mutation in the Hsp90 nucleotide binding site that does not generate stress sensitivity or an impaired stress response. Molybdate sensitivity may therefore be a useful phenotype to score when studying mutations in this chaperone system. Copyright © 2009 John Wiley & Sons, Ltd.     

Finite element modelling of steel fin plate connections in fire

Recent structural collapses caused by fire have focused attention on research concerning fire safety in building design. Steel connections are an important component of any structural steel building, as they provide links between the principal structural members. The evaluation of the performance of steel connections at elevated temperatures has been a topic of several research programmes in the last few years. Determining the behaviour, available strength and stiffness of moment connections in fire conditions has been a dominant theme in these research works; however very little information on the behaviour of simple shear connections in fire conditions has been disseminated. Fin plate shear connections are easy to fabricate and install; as a result, they have gained popularity with fabricators because of their economy. In this research, the robustness of simple fin plate beam-to-column connections is being investigated under catenary tension from highly deflected beams in fire. A highly detailed three-dimensional (3-D) finite element (FE) model has been created using the ABAQUS software. This is a complex model accounting for material and geometric non-linearity, large deformation and contact behaviour. Contact is critical to model the shear behaviour of the joint, and contact elements have been used both at the bolt–hole interface and also at the surface between the web of the beam and the fin plate, taking into consideration friction between the surfaces. The connection model has been analysed through the elastic and plastic ranges up to failure. Bolt shear and bending, and plate and web bearing have been observed as failure modes. A comparison between available experimental data at ambient and elevated temperatures and other analytical results shows that the model has a high level of accuracy. When the connection model was extended to include an attached beam, it was found that it eventually experiences large tensile force when exposed to fire.