Full counting statistics of renormalized dynamics in open quantum transport system

The internal dynamics of a double quantum dot system is renormalized due to coupling respectively with transport electrodes and a dissipative heat bath. Their essential differences are identified unambiguously in the context of full counting statistics. The electrode coupling caused level detuning renormalization gives rise to a fast-to-slow transport mechanism, which is not resolved at all in the average current, but revealed uniquely by pronounced super-Poissonian shot noise and skewness. The heat bath coupling introduces an interdot coupling renormalization, which results in asymmetric Fano factor and an intriguing change of line shape in the skewness.     

Numerical experiments of fluorescence quenching studied by the Smoluchowski–Collins–Kimball model

The paper reports on the recovery of the Smoluchowski–Collins–Kimball (SCK) parameters from simulated fluorescence quenching decays for a donor of a subnanosecond lifetime. The accuracies are established to which the reaction distance (R), the sum of diffusion coefficients of donor and quencher (D) and the specific rate constant of the quenching process (κ) can be recovered. It has been shown that taking into regard the character of the correlation between κ and R, the determination of κ is possible to a much higher accuracy than hitherto achieved. As it is impossible to determine correctly the SCK parameters on the basis of a single fluorescence decay, a minimum number of experiments needed to get a good agreement between the recovered SCK parameters and the values of these parameters used in the simulations has been specified. Our results indicate that not only the full width at half maximum of the instrument response function (IRF) but also the shape of the rising slope of IRF have important effect on the accuracy of the recovered R, D, κ parameters.     

A Bound on the Overlap of Same-Sized Subsets

We prove a new lower bound on the number of shared elements of any pair of same-sized subsets drawn from a given set. Received April 28, 2006     

Radiochemical Analysis of 35SO2 Adsorbed on Pbo2

Abstract

The concentration of ³⁵SO₂ in air can be measured by reacting with Pbo₂ to form Pb³⁵SO₄. A method was developed which is suitable for rapid, high-protection radioassaying of ³⁵SO₄ ^2- on the surface of Pbo₂. The surface ³⁵SO₄ ^2- was extracted with a quaternary alkylammonium hydroxide in toluene and counted in an organic liquid scintillator solution with an efficiency of approximately 94%, which was constant for 30 days when corrected for natural decay. More than 99.5% of the surface sulfate was extracted in less than 5 minutes for quaternary alkylammonium concentrations 600 times in excess. This technique was shown superior to gas-flow proportional counting of the PbO₂ surface.     

Linearity of the instrumental intensity scale in TOF‐SIMS—a VAMAS interlaboratory study

A VAMAS interlaboratory study involving 21 time‐of‐flight SIMS instruments from nine countries has been conducted to evaluate the linearity of the instrumental intensity scale and procedures for intensity correction. Analysts were supplied, by National Physical Laboratory (NPL), with a protocol for analysis (closely aligned with ISO 23830) together with a reference material of polytetrafluoroethylene (PTFE) tape. The primary ion beam current is varied to provide secondary ion intensities that span the linear to nonlinear regime. The natural carbon isotope ratios ¹²C_xF_y⁺/¹³C¹²C_x?1F_y⁺ for five peaks are used to evaluate the linearity, without a need to measure the ion beam current. A method is given for determining the linearity as a function of secondary ion intensity, with and without dead time correction. It is found that single ion counting statistics is closely obeyed, and the linearity achievable is generally excellent with careful application of dead time correction. Three quarters of instruments in the study achieved better than 95% linearity at a count rate of 0.8 measured counts per pulse, equivalent to 1.6 secondary ions impinging the detector per primary ion pulse. We discuss factors affecting linearity and the precise application of dead time correction and give guidance for practical analysis. This includes suboptimal detector efficiency, inhomogeneous intensities across the rastered area, inadequate charge compensation, and the choice of peak integration limits. The interlaboratory study shows that the method to determine linearity is generally applicable, robust and provides an excellent basis for the development of an ISO standard. © Crown copyright 2011. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Assessing the quantitative reliability of solid-state 13C NMR spectra of kerogens across a gradient of thermal maturity

Five type II kerogens, shown by elemental analysis and Rock-Eval pyrolysis to represent a gradient of thermal maturity, were further characterized using a range of solid-state ¹³C NMR spectroscopic techniques. ¹³C cross polarization (CP) NMR spectra of the kerogens confirmed the well-established pattern of increasing aromaticity with increasing thermal maturity. Spin counting showed that CP observability was around 50% for the immature kerogens, and only 14–25% for the mature kerogens. Spin counting also showed that the direct polarization (DP) observabilities were >80% for all but one of the kerogens. Despite the large differences in observability between the two techniques, aromaticities derived from corresponding CP and DP spectra differed by only 1–15%. The RESTORE technique showed that the low CP observability of the immature kerogens was due mostly to rapid T_1ρH relaxation, whereas both rapid T_1ρH relaxation and slow polarization transfer contributed to the low CP observability of the mature kerogens.     

Geometry and Growth Rate of Frobenius Numbers of Additive Semigroups

Linear combinations x ₁ a ₁ ⋯ x _n a _n of n given natural numbers a _s (with nonnegative integral coefficients x _s ) attain all the integral values, starting from some integer N(a), called the Frobenius number of vector a (provided that the integers a _s have no common divisor, greater than 1). The growth rate of N(a) with the large value of σ = ta ₁ ⋯ a _n depends peculiarly from the direction α of the vector a = σα. The article proves the lower bound of order and the upper bound of order σ ². Both orders are reached from some directions α. The averaging of N(a) along all directions, performed for σ = 7, 19, 41 and 97, provides the values, confirming the rate σ ^p for some p between 3/2 and 2 (for n = 3), excluding neither 3/2 nor 2, for the asymptotic behaviour at large σ. One gets check p ≈ 1, 66 for σ between 100 and 200. These unexpected results, based on some strange relations of the Frobenius numbers to the higher-dimensional continued fractions geometry, lead to many facts of this arithmetic trubulence theory, discussed in this article both as theorems and as conjectures. ^★ Partially supported by RFBR grant 05-01-00104.     

Atomic geometry, electronic states and possible hydrogen passivation of the InP(1 1 1)A surface

We present a first-principles theoretical study of the atomic geometry and electronics states of the InP(1 1 1)A surface under In- and P-rich conditions. The In-rich surface, characterised by an In vacancy per unit (2×2) cell, obeys the electron counting rule (ECR) and is semiconducting. Under P-rich conditions we have considered two surface reconstructions: (2×2) with 3/4 monolayer (ML) P coverage and () with 1 ML coverage. In complete agreement with a recent experimental work by Li et al., it is found that the () reconstruction is more stable than the (2×2) reconstruction. However, the () reconstruction has a metallic band structure and thus does not satisfy the ECR. The stability of this reconstruction is explained to arise from a competition between the ECR and a significant elastic deformation in the surface region. We confirm the suggestion by Li et al. that this surface can be passivated both chemically as well as electronically with 1/4 ML coverage of hydrogen.     

A generalization of a result of G. Pólya and its application to a continuous extension of the de la Vallée Poussin means

Variation diminishing properties are established for the periodic kernels . On the real axis, there are related variation diminishing properties of the functions u^msgnu, which are the Green’s functions for the differential operator D^(m+1).     

Polymeric phosphonium salts as a novel class of cationic biocides. IV. Synthesis and antibacterial activity of polymers with phosphonium salts in the main chain

Polymers with phosphonium salts and different alkyl spacers in the main chain were prepared, and their antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method in sterile distilled water. The antibacterial activity of the polymers was found to be higher than that of the corresponding model compounds against each strain, and the effect of the molecular weight on the antibacterial activity was also observed for the compounds with the same spacer length. The antibacterial activity of the polymer samples bonded with different spacer lengths was found to increase with increasing the spacer length against both strains. © 1993 John Wiley & Sons, Inc.