Optimum Allocation in Two-Stage Stratified Randomized Response Model

In the present paper a two-stage stratified Warner’s randomized response model is used to determine the optimum allocation in the presence of non-response. The problem is formulated as a Nonlinear Programming Problem. A complete method of solution of the formulated problem is proposed. Two numerical examples are worked out to illustrate the computational details of the proposed method.     

Photocatalytic decolorization of Brilliant Golden Yellow in TiO2 and ZnO suspensions

Photocatalytic decolorization of BGY, an anionic dye, has been investigated in TiO₂ and ZnO aqueous dispersions under UV-light irradiation. Spectrum of the dye has been found unaffected in the pH range 4.21–11.30. Adsorption is a prerequisite for the metal oxide-mediated photodegradation/photodecolorization and the extent of decolorization has been discussed in terms of the Langmuir–Hinshelwood model. Complete decolorization was achieved in case of UV irradiation whereas degradation of BGY was found to be about ca.75%. ZnO-mediated decolorization has appeared to be better and faster. The effects of various parameters, such as catalyst loading, pH and initial concentration of the dye on decolorization have been investigated.     

Minimum Cost Compromise Mixed Allocation

When more than one (say p) characteristics in multivariate stratified population are defined on each unit of the population, the individual optimum allocations may differ widely and can not be used practically. Moreover, there may be a situation such that no standard allocation is advisable to all the strata, for one reason or another. In such a situation, Clark and Steel (J R Stat Soc, Ser D Stat 49(2):197–207, 2000) suggested that different allocations may be used for different groups of strata having some common characteristics for double sampling in stratification. Later on, Ahsan et al. (Aligarh J Stat 25:87–97, 2005) used the same concept in univariate stratified sampling. They minimized the variance of the stratified sample mean for a fixed cost to obtain an allocation and called this allocation “mixed allocation”. In the present paper, a “compromise mixed allocation” is worked out for the fixed precisions of the estimates of the p-population means of a multivariate stratified population. A numerical example is also presented.     

Search for pair production of scalar bottom quarks in pp collisions at square root of s = 1.96 TeV

A search for direct production of scalar bottom quarks (b) is performed with 310 pb(-1) of data collected by the D0 experiment in pp collisions at square root s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (chi(1)0), with chi(1)0 assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m(b), m(chi(1)0)) mass plane, improving significantly upon the results from run I of the Tevatron.     

Direct limits on the oscillation frequency

We report results of a study of the B(s)(0) oscillation frequency using a large sample of B(s)(0) semileptonic decays corresponding to approximately 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2006. The amplitude method gives a lower limit on the B(s)(0) oscillation frequency at 14.8 ps(-1) at the 95% C.L. At delta m(s) = 19 ps(-1), the amplitude deviates from the hypothesis A= 0(1) by 2.5 (1.6) standard deviations, corresponding to a two-sided C.L. of 1% (10%). A likelihood scan over the oscillation frequency, delta m(s), gives a most probable value of 19 ps(-1) and a range of 17 < delta m(s) < 21 ps(-1)at the 90% C.L., assuming Gaussian uncertainties. This is the first direct two-sided bound measured by a single experiment. If delta m(s) lies above 22 ps(-1), then the probability that it would produce a likelihood minimum similar to the one observed in the interval 16-22 ps(-1) is (5.0 +/- 0.3)%.     

Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying W Bosons

This Letter presents a search for pair production of heavy down-type quarks decaying via b^{'}→Wt in the lepton+jets channel, as b^{'}b[over ˉ]^{'}→W^{-}tW^{+}t[over ˉ]→bb[over ˉ]W^{+}W^{-}W^{+}W^{-}→l^{±}νbb[over ˉ]qq[over ˉ]qq[over ˉ]qq[over ˉ]. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04 fb^{-1} from pp collisions at sqrt[s]=7 TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480?GeV can be excluded at the 95% confidence level.     

A class of algebraically special null Einstein-Maxwell fields in Newman-Penrose formalism

An algebraically special null Einstein-Maxwell space-time has been obtained. It contains shear-free, geodetic and hypersurface orthogonal congruences and more over the space-time is twist-free.     

Mechanistic studies of the tellurium(II)/tellurium(IV) redox cycle in thiol peroxidase-like reactions of diorganotellurides in methanol

Di-n-hexyl telluride (2), di-p-methoxyphenyl telluride (3), and (S)-2-(1-N,N-dimethylaminoethyl)phenyl phenyl telluride (4) catalyzed the oxidation of PhSH to PhSSPh with H(2)O(2) in MeOH. Telluride 2 displayed greater rate acceleration than the diaryltellurides 3 and 4 as determined by the initial velocities, v(0), for the rate of appearance of PhSSPh determined at 305 nm by stopped-flow spectroscopy. Rate constants for the oxidation of tellurides 2-4 (k(ox)), rate constants for the introduction of PhSH as a ligand to the Te(IV) center (k(PhSH)) of oxidized tellurides 5-7, and thiol-independent (k(1)) and thiol-dependent (k(2)) rate constants for reductive elimination at Te(IV) in oxidized tellurides 5-7 were determined using stopped-flow spectroscopy. Oxidation of the Te atom of the electron-rich dialkyl telluride 2 was more rapid than oxidation of diaryl tellurides 3 and 4. The dimethylaminoethyl substituent of 4, which acts as a chelating ligand to Te(IV), did not affect k(ox). Values of k(PhSH) for the introduction of PhSH to oxidized dialkyl tellurane 5 and oxidized diaryl tellurane 6 were comparable in magnitude, while the chelating dimethylaminoethyl ligand of oxidized telluride 7 diminished k(PhSH) by a fator of 10(3). Reductive elimination by both first-order, thiol-independent (k(1)) and second-order, thiol-dependent (k(2)) pathways was slower from dialkyl Te(IV) species derived from 2 than from diaryl Te(IV) species derived from 3. The chelating dimethylaminoethyl ligand of Te(IV) species derived from 4 diminished k(1) by a factor of 50 and k(2) by a factor of 3 (relative to the 3-derived species).     

Bonding mechanisms of laser‐fabricated titanium/polyimide and titanium coated glass/polyimide microjoints

In this study, two bimaterial joining systems, namely, titanium coated glass/polyimide (TiGPI) and titanium/polyimide (TiPI) are considered. The joints were prepared by employing transmission type laser‐joining procedure. Both the TiGPI and TiPI bimaterial systems were subjected to tensile loading using a microtester, and failure loads per unit bond length were documented. The average failure strengths of the TiPI and TiGPI samples were found to be 5.1 and 7.3 N/mm, respectively. It is thus clear from the failure data that the TiGPI joints are stronger (1.4 times) than the TiPI joints although same chemical bonds between titanium and polyimide (PI) exist for both the systems. It is thus believed that material surface morphology has contributed to such variation in the microjoint strengths. Later, atomic force microscopy (AFM) of titanium surfaces of both titanium coated glass and titanium foil was performed, and was observed that they had root mean squared (RMS) surface roughnesses of 220 and 55 nm, respectively. The surface roughness provides improved surface contact area, number of chemical bonds, and mechanical interlocking that may have resulted in higher bond strength for the TiGPI system. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and Crystal Structures of Bromo(1,10-phenanthroline- N , N ′)tris(2-cyanoethyl)phosphinocopper(I) and Bromo(2,2′-bipyridine- N , N ′)tris(2-cyanoethyl)phosphinocopper(I)

The two new complexes bromo(1,10-phenanthroline-N,N′)tris(2-cyanoethyl)phosphinocopper(I) and bromo(2,2′-bipyridine-N,N′)tris(2-cyanoethyl)phosphinocopper(I) were synthesized and their X-ray crystal structures were determined. The first complex crystallizes in the triclinic space group P-1 with the crystal cell parameters a = 7.7596(7) ?, b = 11.470(1) ?, c = 12.803(1) ?, α = 78.884(1)^°, β = 79.759(1)^°, γ = 86.867(1)^°, V = 1100.0(2) ?³ and Z = 2. The second complex crystallizes in the orthorhombic space group Pbca with the crystal cell parameters a = 10.614(1) ?, b = 12.345(1) ?, c = 31.903(3) ?, V = 4180.3(7) ?³ and Z = 8. In both compounds, the copper(I) ion is four-coordinate with a distorted tetrahedral geometry. In the 1,10-phenanthroline complex, an intermolecular dipole–dipole interaction between two cyano groups stabilizes an unfavorable synclinal conformation of one cyanoethyl group of the phosphine ligand.