Metrological traceability chain for pH measurement results

The extent to which technical barriers to international trade caused by non-acceptance of chemical measurement results can be removed, largely depends on the success in building up national and international traceability structures also in metrology in chemistry. Achieving metrological comparability of measurement results requires the definition of metrological calibration hierarchies providing metrological traceability chains which enable the establishment of metrological traceability of measured quantity values to a common metrological reference [1]. For pH, over the last decade, work has been carried out in a number of countries to build up meteorological calibration hierarchies within a national framework. An overview on the metrological traceability chain for pH is given with focus on the primary measurement procedure of pH.     

Generic Hubbard Hamiltonian for 1D Large-Spin Ultracold Fermionic Chains

Journal of Superconductivity and Novel Magnetism - A new version of the generalized Hubbard Hamiltonian is introduced here for high-spin ultracold fermions, which was used to study a spin-5/2...     

Experimental 1-V flexible-IF CMOS analoguebaseband chain for IEEE 802.11a/b/g WLAN receivers

A low-voltage low-power analogue-baseband chain designed for IEEE 802.11a/b/g wireless local-area network (WLAN) receivers is described. It features architecturally a 'two-step channel selection' to complement the radio front-end, and a flexible intermediate frequency (IF) reception capability to alleviate the cancellation of frequency and DC-offset. In circuit implementation, a double-quadrature downconverter based on a 'series-switching' mixer- quad realises a wideband-accurate I/Q demodulation. A 'switched-current-resistor' programmable-gain amplifier (PGA) minimises the bandwidth variation and transient in gain tuning by stabilising, concurrently, the PGA's feedback factor and quiescent-operating point. An 'inside-OpAmp' DC-offset canceller creates area-efficiently a very low cut-off frequency high-pass pole at DC while providing a fast settling of DC-offset transients. Fabricated in a 0.35 mum complementary metal-oxide semiconductor (CMOS) process without resorting to any specialised device, the prototype consumes 14 mW per channel at 1 V. The transient time in a 52-dB gain step is < 1 mus and the stopband rejection ratio at 20/40 MHz is 32/90 dB. The error vector magnitudes are -27 and -17 dB for 802.11a/g and b modes, respectively.     

Eliashberg equations with momentum-dependent Kernels for the two-dimensional Hubbard model

We discuss the impact of the strong electron-phonon interactions on the physical properties of correlated electrons in the two-dimensional Hubbard model. An easy access to the physical properties of the superconducting state is obtained by solving the Eliashberg equations with explicit momentum-dependent kernels. In order to facilitate the numerical procedure to solve these equations, correlations are treated within the Gutzwiller approximation (i.e., mean-field-slave boson approximation). Our results strongly support the view thatd-wave symmetry is the most important feature of the superconducting state in the copper oxides. A possible extension beyond the mean field approximation is also presented.Supported by the State Committee for Scientific Research, Grant No. 283021805.     

Asymptotic failure rate of a continuously monitored system

This paper deals with a perfectly continuously monitored system which gradually and stochastically deteriorates. The system is renewed by a delayed maintenance operation, which is triggered when the measured deterioration level exceeds an alarm threshold. A mathematical model is developed to study the asymptotic behavior of the reliability function. A procedure is proposed which allows us to identify the asymptotic failure rate of the maintained system. Numerical experiments illustrate the efficiency of the proposed procedure and emphasize the relevance of the asymptotic failure rate as an interesting indicator for the evaluation of the control-limit preventive replacement policy.     

Asymptotic analysis for a rarefied gas with molecular interactions of infinite range

The limit of small rarefaction is considered for linearized plane Couette flow of a rarefied gas with molecular interactions of infinite range. The governing equation is the linearized Boltzmann equation and the kernel of this integrodifferential equation is strongly singular. The zeroth and first order approximations to the distribution function or the defining equations for the approximations are systematically derived by the method of matched inner and outer asymptotic expansions along with suitable error estimates. The mean velocity and other relevant moments of the distribution function are given up to the order corresponding to the first order inner and outer approximations to the distribution function. The order of the leading term for the mean velocity is verified to be of order α^β where α is the degree of rarefaction, β = (a + 1)/(s ? 1) and s is the exponent in the intermolecular force law. The first order corrections are derived and are found to be of order α In α and α.     

LPTF frequency synthesis chain: results and improvement for thenear future

We describe the modified LPTF frequency synthesis chain, which starts from the cesium referenced CO₂/OsO₄ laboratory standard. This chain, with variations, is able to cover the whole visible spectrum. A particular scheme is given in order to measure the 385.3-THz frequency of the two-photon transitions in rubidium. To secure the phase lock, the diode lasers' linewidths have to be reduced. We report a 10-Hz beatnote linewidth obtained with two diode lasers stabilized on the same high-finesse cavity     

Pricing decisions for a supply chain with refurbished products

This paper considers a supply chain consisting of a supplier and a retailer where a fixed portion of new products sold will be returned to the retailer and then be repaired and resold as refurbished products at a lower price. Using the utility model, we formulate how consumers will make their choices when facing both new and refurbished products. Then, using the divide-and-conquer method, we derive the supplier and retailer's equilibrium decisions, including the supplier's wholesale price and the retailer's prices for both the new and refurbished products. The main findings include the following. First, refurbished products will be sold in the market only when the refurbishing cost is small. In this situation, as the refurbishing cost increases, most of the negative impact on the retailer will be transferred to the supplier. Second, in the same condition, as the refurbishing cost increases, the wholesale price and retail price of the new product will change in opposite directions. This result contrasts with the traditional pass-through effect. Third, when the repair cost is moderate, the retailer will eventually not sell refurbished products, but its profit can be significantly improved and the double marginalisation effect can be mitigated.     

Asymptotic solution for a penny-shaped near-surface hydraulic fracture

This paper considers the large time asymptotic behavior of a near-surface hydraulic fracture, that is, when the radius (R) is much larger than the depth (H). The fracture is analyzed as an elastically clamped circular plate and stress intensity factors are determined by matching the outer plate problem to the inner problem of a near-surface semi-infinite crack. In the zero-viscosity limit, we derive two terms of a large R/H asymptotic solution. Comparison shows that the accuracy of some published numerical results deteriorates for R/H > 5. This is corrected using smaller element size to ensure that the crack-tip element is entirely in the region that is well-approximated by a square-root tip asymptote.     

Asymptotic expansions of the Biot-Savart law for a slender vortex with core variation

The Method of Matched Asymptotic Expansion of Singular Integrals (MAESI) is used to expand the Biot-Savart law in terms of different parameters. This method is first used to find, in terms of the small distance r to a line vortex, the first orders of the known expansion of the potential flow induced by this line vortex. This method is also used to easily compare two equations of motion of a slender vortex filament: the one obtained in an ad-hoc way by a cut-off line-integral technique and the other derived from the Navier-Stokes equations by Callegari and Ting. Finally, this method is used to give the inner expansion of the flow induced by a slender vortex in terms of its slenderness . This is the first inner expansion up to order one in terms of of the Biot-Savart law for a slender vortex. An application of this inner expansion is then given to find the induced velocity of a family of non-circular vortex rings with axisymmetric axial-core variation. In order to understand the time-evolution of these initial conditions to the Navier-Stokes equations, a short time scale is introduced. A quasi-hyperbolic system that describes the leading-order dynamics of the axisymmetric axial core variation on a curved slender vortex filament is finally extracted from the Navier-Stokes equations.     

A pricing/ordering model for a dyadic supply chain with buyback guarantee financing and fairness concerns

The paper investigates pricing/ordering issues in a dyadic supply chain, in which a core supplier sells products through a budget-constrained retailer. The retailer faces stochastic demand and is fairness-concerned as well. If needed, the retailer can get financing support from bank by means of buyback guarantee financing (BGF) mode, which is often used in China. By introducing Nash bargaining solution as the fairness reference point, we formulate the retailer’s fairness-concerned utility function and develop a two-echelon pricing/ordering game model. We then study the combined impacts of fairness concerns and BGF on two members’ equilibrium strategies and supply chain performance. We also discuss the corresponding issues under no budget constraint, no financing service and bank financing. Our results show that: (1) two members’ equilibrium strategies are significantly influenced by the retailer’s fairness-concerned behaviour and initial budget; (2) as compared to no budget constraint, BGF can bring the whole supply chain more performance, which means that BGF can yield value-added; (3) When the retailer takes the risk of uncertain market solely, the retailer’s fairness concerns are beneficial for supply chain to improve the performance.     

Axiomatic/Asymptotic Technique Applied to Refined Theories for Piezoelectric Plates

This article is devoted to the evaluation of refined theories for static response analysis of piezoelectric plate. The Carrera Unified Formulation (CUF) is employed to generate the refined plate models. The CUF allows the hierarchical implementation of refined models based on any-order expressions of the unknown variables. Equivalent single layer (ESL) and layerwise (LW) approaches are used to generate the refined models. The governing equations are obtained considering Navier-type, closed-form solutions. The axiomatic/asymptotic technique is employed in order to evaluate the relevance of each model term. This technique computes the relevance of a model term by measuring the error introduced with its deactivation with respect to a reference solution. The axiomatic/asymptotic technique is applied considering the sensor and actuator configurations for piezoelectric plates. Moreover, the analyses are performed taking into account the influence of the length-to-thickness ratio (a/h) and the use of isotropic or orthotropic materials. “Best” models are proposed and the stress/displacement components and electric potential distributions are evaluated by means of these reduced models.     

Two Domains of the Parameter Space of the 2D Hubbard Model for High-Tc Superconductors

High-T _c superconducting cuprates have two types of Fermi surfaces: simple-2D-tight-binding-band type (LSCO type) and the much deformed one (Bi2212 type). The difference is attributed to that of band parameter values, i.e., t′ ∼ −0.1 and t″ ∼ 0 versus t′ ∼ −0.3 and t″ ∼ 0.2 in terms of the second- and third-neighbor transfer energies t′ and t″, respectively (energy unit is the nearest-neighbor transfer energy t). Assuming a moderate value of on-site Coulomb energy U ∼ 6 and performing the variational Monte Carlo computation, we found that the two superconducting parameter domains exist in fact around these parameter sets, respectively, in which superconductivity predominates over spin density wave (SDW) due to the latter being at the brink of vanishing. Stripes were obtained in the first domain but tend to disappear in the second. In the latter domain there seems to exist parameter sets for which superconductivity appears without doping.     

Experimental results for a hydraulic refrigeration system using n-butane

The hydraulic refrigeration system (HRS) is a vapor-compression system that accomplishes the compression and condensation of the refrigerant in a unique manner, by entraining refrigerant vapor in a down-flowing stream of water and utilizing the pressure head of the water to compress and condense the refrigerant. A multi-stage HRS was designed, fabricated, and tested using n-butane as the refrigerant. In general, both the refrigeration rate and the coefficient of performance (COP) increased with a corresponding decrease in the compression fluid temperature of the third and final stage. The refrigeration rate and COP were also found to increase with a corresponding increase in evaporator temperature. The predictions of an enhanced model incorporating two-phase hydraulic losses show excellent agreement with the experimental data with a maximum error of ±20%. The results of the experimental investigation indicate that the HRS offers an attractive and feasible alternative to conventional vapor-compression systems, especially in applications where direct-contact heat exchange in the evaporator is desirable.     

Strategic use of immunoprecipitation and LC/MS/MS for trace-level protein quantification: myosin light chain 1, a biomarker of cardiac necrosis

Myosin light chain 1 (Myl3) is a 23-kDa isoform of one of the subunits of myosin, a protein involved in muscle contraction. Myl3 is presently being studied as a biomarker of cardiac necrosis to predict drug-induced cardiotoxicity, and in the work presented here, an LC/MS/MS assay was developed and validated to measure Myl3 in rat serum. The key steps in this approach involved immunoaffinity purification of Myl3 from serum followed by on-bead digestion with trypsin to release a surrogate peptide. This tryptic peptide was quantified using a synthetic peptide standard and a corresponding stable isotope-labeled internal standard, and the results were stoichiometrically converted to Myl3 serum concentrations. Myl3 concentrations were corrected for peptide recovery following immunoprecipitation and digestion (85%) and showed excellent agreement with synthetic peptide standards. Both the synthetic peptide and His-Myl3 protein were used to evaluate assay accuracy (% RE) and precision (% CV), which were measured on each of 3 days. The synthetic peptide was evaluated over the range of 0.073-7.16 nM, while Myl3 protein QC samples prepared in rat serum were evaluated over the range of 0.13-6.62 nM. To prepare control matrix, endogenous Myl3 was immunodepleted from pooled rat serum. Peptide interday accuracy and precision did not exceed 7.6 and 11.1%, and Myl3 interday accuracy and precision did not exceed 12.9 and 13.2%, respectively. Data are presented from the application of this assay to establish a time course in which rats demonstrated a marked increase in Myl3 serum concentrations following administration of isoproterenol, a beta-adrenergic receptor agonist known to induce cardiac injury. This assay is an example of a larger effort in our laboratory to use LC/MS/MS in conjunction with immunoaffinity techniques to evaluate candidate biomarkers of target organ toxicity and to expedite the development of biomarker assays for drug development.     

Cuno posts record results for Q1

Connecticut-based Cuno Inc has reported record results for its first quarter ended 31 January 2004.     

Pricing and effort decisions for a supply chain with uncertain information

This paper analyses the pricing and effort decisions of a supply chain with single manufacturer and single retailer. The manufacturer produces a kind of product and then wholesales the product to the retailer, who in turn retails it to customers over a single selling season. The retailer can influence demand through her sales effort. This research depicts the consumer demand, the manufacturing cost and the sales effort cost as uncertain variables. Considering the demand expansion effectiveness of sales effort, one centralised and three decentralised game models are built on the basis of the expected value criterion, and the equilibrium solutions are obtained. We investigate the effects of the parameters’ uncertainty degrees on the pricing and effort decisions. The results indicate that the manufacturer benefits from improvement in demand and cost uncertainties when he has at least bargaining power in the supply chain. The results also imply that the uncertainty degree of sales effort elasticity has an outstanding influence on the pricing and effort decisions, whereas the uncertainty degree of price elasticity has a modest impact on these decisions. We also study the effects of the parameters’ uncertainty degrees on the supply chain from the consumers’ perspective. The results suggest that with a power retailer, the retail price should always be on the high end. Consequently, consumers do not necessarily benefit from a power retailer. When the manufacturer and the retailer have equal bargaining power, consumers do not necessarily benefit from the supply chain, either.     

Asymptotic analysis for a crack on interface of damaged materials

An asymptotic analysis for a crack lying on the interface of a damaged plastic material and a linear elastic material is presented in this paper. The present results show that the stress distributions along the crack tip are quite similar to those with HRR singularity field and the crack faces open obviously. Material constants n, μ and m0 are varied to examine their effects on the resulting stress distributions and displacement distributions in the damaged plastic region. It is found that the stress components σrr, σθ θ, σr θ and σe are slightly affected by the changes of material constants n, μ and m0, but the damaged plastic region are greatly disturbed by these material parameters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Asymptotic behavior of the Langevin equation for a nonhomogeneous medium

The Langevin equation has gained renewed interest through its role in modeling turbulent, reacting flow, and turbulent dispersion. Such applications often require an understanding of its long term, asymptotic behavior. The asymptotic, Smoluchowsky, equation is derived by constructing a uniformly valid bound on the velocity variance. Extra drift terms arise in the asymptotic equation when the coefficients are not constant.