Evolutionary events in a mathematical sciences research collaboration network

This study examines long-term trends and shifting behavior in the collaboration network of mathematics literature, using a subset of data from Mathematical Reviews spanning 1985–2009. Rather than modeling the network cumulatively, this study traces the evolution of the “here and now” using fixed-duration sliding windows. The analysis uses a suite of common network diagnostics, including the distributions of degrees, distances, and clustering, to track network structure. Several random models that call these diagnostics as parameters help tease them apart as factors from the values of others. Some behaviors are consistent over the entire interval, but most diagnostics indicate that the network’s structural evolution is dominated by occasional dramatic shifts in otherwise steady trends. These behaviors are not distributed evenly across the network; stark differences in evolution can be observed between two major subnetworks, loosely thought of as “pure” and “applied”, which approximately partition the aggregate. The paper characterizes two major events along the mathematics network trajectory and discusses possible explanatory factors.     

Usability assessment of text-to-speech synthesis for additional detail in an automated telephone banking system

This paper describes a comprehensive usability evaluation of an automated telephone banking system which employs text-to-speech (TTS) synthesis in offering additional detail on customers’ account transactions. The paper describes a series of four experiments in which TTS was employed to offer an extra level of detail to recent transactions listings within an established banking service which otherwise uses recorded speech from a professional recording artist. Results from the experiments show that participants welcome the added value of TTS in being able to provide additional detail on their account transactions, but that TTS should be used minimally in the service.     

Distributed control of multi-robot systems using bifurcating potential fields

The distributed control of multi-robot systems has been shown to have advantages over that of conventional single-robot systems. These include scalability, flexibility and robustness to failures. This paper considers pattern formation and reconfigurability in a multi-robot system using a new control algorithm developed through bifurcating potential fields. It is shown how various patterns can be achieved autonomously through a simple free parameter change, with the stability of the system proven to ensure that desired behaviours always occur.     

Unique and interactive effects of depression, age, socioeconomic advantage, and gender on cognitive performance of normal healthy older people.

A sample of 4,243 residents of Manchester and Newcastle-upon-Tyne, England, aged 50 to 93 yrs, completed the Beck Depression Inventory and a battery of 6 different cognitive tests. Beck scores were low, indicating gradations of dysphoria rather than clinical depression. Beck scores did not vary with age but were significantly higher for women than for men and for disadvantaged than for advantaged socioeconomic groups. Measures of fluid, but not of crystallized, ability declined as age increased. Socioeconomic disadvantage was associated with poorer performance on all cognitive tests. Men scored higher on a test of spatial reasoning, and women scored higher on a test of word definition and on 2 tests of verbal memory and learning. However, after variance associated with these demographic and individual difference variables was considered, and within a range indicative of dysphoria rather than clinical depression, higher Beck scores were associated with significantly poorer performance on both crystallized and fluid measures of cognitive ability. This association was less marked in women than in men, but age, socioeconomic advantage, and estimated lifetime intellectual ability did not act as protective or risk factors for vulnerability of cognitive processes to dysphoria. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiation patterns of paraboloid with log-periodic dipole feed

The effect of axial displacement of phase centre on the secondary performance of a parabolic reflector is described, with particular reference to a log-periodic dipole-array feed. Computed and experimental results are presented.     

Radiation patterns of dielectric loaded rectangular horns

The effect of dielectric loading upon theE-plane radiation patterns of rectangular horns is shown to give higher directivity with raised sidelobes. The main beam and first sidelobe can be predicted accurately in terms of radiation from aTM_{y10}mode.     

Bound for Minkowski metric or quadratic metric applied to VQcodeword search

A bound for a Minkowski metric based on L_p distortion measure is proposed and evaluated as a means to reduce the computation in vector quantisation. This bound provides a better criterion than the absolute error inequality (AEI) elimination rule on the Euclidean distortion measure. For the Minkowski metric of order n, this bound contributes the elimination criterion from the L₁ metric to L _n metric. This bound can also be an extended quadratic metric which can be a hidden Markov model (HMM) with a Gaussian mixture probability density function (PDF). In speech recognition, the HMM with the Gaussian mixture VQ codebook PDF has been shown to be a promising method     

Thermal effects in a coplanar-pumped folded-zigzag slab laser

The properties of a coplanar-pumped folded-slab laser under the influence of thermal lensing have been modeled and measured. It is shown that despite the formation of a strong astigmatic lens within the slab, the results can be used to design resonators capable of good TEM₀₀ performance, suitable for a wide variety of applications. Good agreement is found between modeling and measurement of slab and laser parameters. Using a novel technique, the fraction of absorbed pump power converted to heat has been measured under diode-laser pumping     

NMR study of the transforming growth factor-alpha (TGF-alpha)-epidermal growth factor receptor complex. Visualization of human TGF-alpha binding determinants through nuclear Overhauser enhancement analysis

The study of human transforming growth factor-alpha (TGF-alpha) in complex with the epidermal growth factor (EGF) receptor extracellular domain has been undertaken in order to generate information on the interactions of these molecules. Analysis of 1H NMR transferred nuclear Overhauser enhancement data for titration of the ligand with the receptor has yielded specific data on the residues of the growth factor involved in contact with the larger protein. Significant increases and decreases in nuclear Overhauser enhancement cross-peak intensity occur upon complexation, and interpretation of these changes indicates that residues of the A- and C-loops of TGF-alpha form the major binding interface, while the B-loop provides a structural scaffold for this site. These results corroborate the conclusions from NMR relaxation studies (Hoyt, D. W., Harkins, R. N., Debanne, M. T., O'Connor-McCourt, M., and Sykes, B. D. (1994) Biochemistry 33, 15283-15292), which suggest that the C-terminal residues of the polypeptide are immobilized upon receptor binding, while the N terminus of the molecule retains considerable flexibility, and are consistent with structure-function studies of the TGF-alpha/EGF system indicating a multidomain binding model. These results give a visualization, for the first time, of native TGF-alpha in complex with the EGF receptor and generate a picture of the ligand-binding site based upon the intact molecule. This will undoubtedly be of utility in the structure-based design of TGF-alpha/EGF agonists and/or antagonists.     

Low dose desensitisation does not reduce the toxicity of sulphasalazine in rheumatoid arthritis

To investigate the apoptosis-inducing effect of glucocorticoid on gastric epithelial cell expressing different p53 genes, a human gastric epithelial cell line-GES-1 was transfected with either wild type or mutant p53 cDNA in vitro. The cells were treated with hydrocortisone in a concentration range of 0.2-0.8 g/L. Apoptotic cells were found in those transfectants. The apoptotic response of the wild-type p53-transfected GES-1 cells was much more marked than that of the mutant p53 transfected ones. It can be inferred that the glucocorticoid secreted not only suppress the immunological response during inflammation, but induce gastric epithelial cell apoptosis as well. If the gastric epithelial cell contains mutant p53 genes, the glucocorticoid confer a selective growth advantage which advance the malignant process.