Variable screening in predicting clinical outcome with high-dimensional microarrays

Statistical modeling is an important area of biomarker research of important genes for new drug targets, drug candidate validation, disease diagnoses, personalized treatment, and prediction of clinical outcome of a treatment. A widely adopted technology is the use of microarray data that are typically very high dimensional. After screening chromosomes for relative genes using methods such as quantitative trait locus mapping, there may still be a few thousands of genes related to the clinical outcome of interest. On the other hand, the sample size (the number of subjects) in a clinical study is typically much smaller. Under the assumption that only a few important genes are actually related to the clinical outcome, we propose a variable screening procedure to eliminate genes having negligible effects on the clinical outcome. Once the dimension of microarray data is reduced to a manageable number relative to the sample size, one can select a final set of genes via a well-known variable selection method such as the cross-validation. We establish the asymptotic consistency of the proposed variable screening procedure. Some simulation results are also presented.     

The use of fuzzy sets for resource allocation in an advance request vehicle brokerage system—a case study

Community transport vehicle brokerage operators match the needs of groups without minibuses with the spare capacity of groups which own minibuses. They take bookings in advance, and allocate vehicles without knowing what the total demand will be for travel at a certain time. An approach has been developed which ranks vehicles according to a sequence number which indicates how ‘difficult to book’ they are, and presents the most difficult to book to the broker first, with the intention of maintaining the maximum flexibility in the system. The concept difficult to book is not easy to define exactly. Fuzzy set theory provides a mechanism for dealing with imprecise concepts, and through fuzzy logic for reasoning about such concepts. Fuzzy inferencing systems consist of linguistic variables, fuzzy sets, rules, and methods to combine the sets and produce a final result. Fuzzy logic has been used to provide a means of automating the allocation of sequence numbers to vehicles. Three different approaches to developing the rules for this system have been tested, by simulating bookings, and the one which produced the best results was based on a knowledge acquisition process involving booking staff. This approach resulted in the allocation of the highest number of trips and in leaving the least hours of travel unallocated.     

An unexpected Diels-Alder type cycloaddition of cyclic enone ethylene ketals

The ethylene ketal of 2-cyelopentenone and 2-cyelohexenone in acetonitrile in thepresence of a trace of an acid rapidly undergoes the Diels-Alder type dimerization,Theproducts are regiospecific but not stereoselective and are hydrolysed sequentially to affordketo-ketals and diketones whose structures are determined by extensive applications of NMRspectroscopy.     

Microscopic modelling of bulk and quantum-well GaAs-based semiconductor lasers

The dynamical behaviour of Fabry-Perot type semiconductor lasers is modelled, including the relevant many-body Coulomb effects of the excited carriers. Conditions are given under which a parametrization of the full model is possible, allowing simple analytic relations for local gain, refractive index and linewidth enhancement factor. The parameters of the simplified model are uniquely determined by the microscopic theory and have to be optimized for the respective operating conditions. The theory is evaluated for bulk and quantum-well GaAs active material and a variety of laser structures, including strongly and weakly index-guided structures, as well as purely guided single-and twin-stripe lasers.     

Possibility of using laser-fibre optics as a fire detection system

Optical fibres together with a helium-neon laser is proposed to be used as a new fire detection system. This has been Investigated experimentally and reported in this paper. Results on the coupling loss, bending loss, extinction loss of the fibres due to smoke and refraction loss through hot air shimmer are described. Comparison with the performance of common optical and ionization detectors is made. Experimental results indicate that the optical signal would be significantly changed when there is smoke. Hence it is highly probable that a new fire detection system can be designed using laser-fibre optics.     

Electronic structure and dynamics of muonium in semiconductors

In this paper, a selection of recent results on muonium in semiconductors is presented. These are primarily taken from Si and GaAs and encompass the electronic structure of the diamagnetic centers, charge state cycling, spin‐exchange scattering and interconversion between muonium states. These experiments illustrate the power of μSR for investigating the behavior of muonium and, by analogy, the technologically relevant isolated hydrogen centers in semiconductors. This revised version was published online in August 2006 with corrections to the Cover Date.     

A versatile reagent to synthesize diverse ionic liquids ranging from small molecules and dendrimers to functionalized proteins

An ionic liquid "reagent" bearing a succinimidyl activated ester is reported that can be used to synthesize a variety of small molecule and macromolecular ionic liquids. In addition, the ionic liquid reagent was used to modify lysozyme, and the protein retained its structure and function after modification. This study describes a facile and reliable route to new ionic liquid compositions.     

Cyclometalated platinum(II) complexes as topoisomerase IIα poisons

A platinum(II)-based major groove binder [Pt(II)(C^N)(C≡NR)(2)](+) (HC^N = 2-phenylpyridine (phpy), R = 2-naphthyl) was identified as a potent human topoisomerase IIα poison. It stabilizes the covalent TopoIIα-DNA cleavage complex and induces cancer cell death with potency significantly higher than the widely clinically used TopoIIα poison Vp-16.