When to rebuild or when to adjust scorecards

Data-based scorecards, such as those used in credit scoring, age with time and need to be rebuilt or readjusted. Unlike the huge literature on modelling the replacement and maintenance of equipment there have been hardly any models that deal with this problem for scorecards. This paper identifies an effective way of describing the predictive ability of the scorecard and from this describes a simple model for how its predictive ability will develop. Using a dynamic programming approach one is then able to find when it is optimal to rebuild and when to readjust a scorecard. Failing to readjust or rebuild a scorecard when they aged was one of the defects in credit scoring identified in the investigations into the sub-prime mortgage crisis.     

Thermodynamics of aqueous solutions of poly ethylene glycol di-methyl ethers in the presence or absence of ammonium phosphate salts

Precise measurements of density and sound velocity at different temperatures ranging from 283.15 to 308.15 K for solutions of PEGDME250, PEGDME500 and PEGDME2000 in water and of PEGDME500 in aqueous solutions of 0.500 mol kg⁻¹ ammonium di-hydrogen phosphate ((NH₄)H₂PO₄) and di-ammonium hydrogen phosphate ((NH₄)₂HPO₄), binodal curves at temperature ranges 293.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄, PEGDME500 + (NH₄)₃PO₄, PEGDME2000 + (NH₄)H₂PO₄, PEGDME2000 + (NH₄)₂HPO₄, PEGDME2000 + (NH₄)₃PO₄ and PPG400 + (NH₄)₂HPO₄ two-phase systems, and liquid-liquid equilibrium data at temperature ranges 298.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄ and PEGDME2000 + (NH₄)₂HPO₄ two-phase systems have been taken. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined and the effect of temperature, charge on the anion of electrolytes and molar mass of PEGDME on the volumetric and compressibility properties of the investigated polymer solutions as well as on the salting-out effect of PEGDMEs produced by ammonium phosphate salts has been studied.     

Reversible tunability of the near-infrared valence band plasmon resonance in Cu(2-x)Se nanocrystals

We demonstrate that colloidal Cu(2-x)Se nanocrystals exhibit a well-defined infrared absorption band due to the excitation of positive charge carrier oscillations (i.e., a valence band plasmon mode), which can be tuned reversibly in width and position by varying the copper stoichiometry. The value of x could be incrementally varied from 0 (no plasmon absorption, then a broad peak at 1700 nm) to 0.4 (narrow plasmon band at 1100 nm) by oxidizing Cu(2)Se nanocrystals (upon exposure either to oxygen or to a Ce(IV) complex), and it could be incrementally restored back to zero by the addition of a Cu(I) complex. The experimentally observed plasmonic behavior is in good agreement with calculations based on the electrostatic approximation.     

Tail-labelling of DNA probes using modified deoxynucleotide triphosphates and terminal deoxynucleotidyl transferase. Application in electrochemical DNA hybridization and protein-DNA binding assays

A simple approach to DNA tail-labelling using terminal deoxynucleotidyl transferase and modified deoxynucleoside triphosphates is presented. Amino- and nitrophenyl-modified dNTPs were found to be good substrates for this enzyme giving 3'-end stretches of different lengths depending on the nucleotide and concentration. 3-Nitrophenyl-7-deazaG was selected as the most useful label because its dNTP was efficiently incorporated by the transferase to form long tail-labels at any oligonucleotide. Accumulation of many nitrophenyl tags per oligonucleotide resulted in a considerable enhancement of voltammetric signals due to the nitro group reduction, thus improving the sensitivity of electrochemical detection of the tail-labelled probes. We demonstrate a perfect discrimination between complementary and non-complementary target DNAs sequences by tail-labelled hybridization probes as well as the ability of tumour suppressor p53 protein to recognize a specific binding site within tail-labelled DNA substrates, making the methodology useful in electrochemical DNA hybridization and DNA-protein interaction assays.     

Iron(II) complexes with functionalized amine-pyrazolyl tripodal ligands in the cross-coupling of aryl Grignard with alkyl halides

Structurally distinctive Fe(II) complexes with furan, thiophene and pyridine functionalized amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. The tether substituent at the central amine plays an active role in determining the coordination mode of the ligand and the metal geometry. All complexes are catalytically active towards cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides with β-hydrogen under ambient conditions. ESI-MS spectra analysis revealed the ligand-stabilised Fe(II) and Mg(II) species.     

An application of comonotonicity theory in a stochastic life annuity framework

A life annuity contract is an insurance instrument which pays pre-scheduled living benefits conditional on the survival of the annuitant. In order to manage the risk borne by annuity providers, one needs to take into account all sources of uncertainty that affect the value of future obligations under the contract. In this paper, we define the concept of annuity rate as the conditional expected present value random variable of future payments of the annuity, given the future dynamics of its risk factors. The annuity rate deals with the non-diversifiable systematic risk contained in the life annuity contract, and it involves mortality risk as well as investment risk. While it is plausible to assume that there is no correlation between the two risks, each affects the annuity rate through a combination of dependent random variables. In order to understand the probabilistic profile of the annuity rate, we apply comonotonicity theory to approximate its quantile function. We also derive accurate upper and lower bounds for prediction intervals for annuity rates. We use the Lee-Carter model for mortality risk and the Vasicek model for the term structure of interest rates with an annually renewable fixed-income investment policy. Different investment strategies can be handled using this framework.     

Preparation of ethyl 2-aryl 2,3-alkadienoates via palladium-catalyzed selective cross-coupling reactions

Pd-catalyzed cross-coupling reactions of aryl iodides containing not only an electron-donating group but also an electron-withdrawing group on the aryl ring with organoindium reagents generated in situ from indium and ethyl 4-bromo-2-alkynoates produced selectively ethyl 2-aryl-2,3-alkadienoates in good yield.     

A new tool to assess ceramide bioactivity: 6-bromo-7-hydroxycoumarinyl-caged ceramide

The bioactivity of natural, long-chain ceramides has until now been studied after its delivery to cells in organic solvent mixtures containing dodecane. We have synthesized ceramides conjugated to a (6-bromo-7-hydroxycoumarin-4-yl)methyl group. The photocaged ceramide is efficiently released with 350 nm light in aqueous solution at neutral pH, thus providing a promising new tool to study ceramide's properties.     

Effect of oxygen evolution catalysts on hematite nanorods for solar water oxidation

Photochemical deposition of Co and Ni based oxygen evolution catalysts on hematite nanorods cathodically shifted the onset potential of photocurrent near to the flat band potential of hematite. A 9.5 fold enhancement in the photocurrent density at 0.86 V vs. RHE compared to the parent hematite photoanode was observed with the Ni-Bi/Fe(2)O(3) photoanode.