Effects of di-(2-ethylhexyl) phthalate (DEHP) released from laboratory equipments

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in polyvinyl chloride (PVC) manufacturing and is an endocrine disrupter. DEHP was released from laboratory tubing and resins during solvent extraction of natural plants to isolate skin depigmenting compounds. Contamination of DEHP significantly interfered with the purification of depigmenting compounds, since DEHP showed high depigmenting activity (IC₅₀=24 μM) and did not show cell toxicity up to 20 μM. Release of DEHP depended on the composition of tubing materials and solvents used in the extraction process. This result provides practical information for the proper selection of laboratory materials and solvents especially in the extraction and isolation of skin depigmenting compounds for cosmetic ingredients.     

Efficient anticorrelated variance reduction for stochastic simulation of biochemical reactions

We investigate the computational challenge of improving the accuracy of the stochastic simulation estimation by inducing negative correlation through the anticorrelated variance reduction technique. A direct application of the technique to the stochastic simulation algorithm (SSA), employing the inverse transformation, is not efficient for simulating large networks because its computational cost is similar to the sum of independent simulation runs. We propose in this study a new algorithm that employs the propensity bounds of reactions, introduced recently in their rejection‐based SSA, to correlate and synchronise the trajectories during the simulation. The selection of reaction firings by our approach is exact due to the rejection‐based mechanism. In addition, by applying the anticorrelated variance technique to select reaction firings, our approach can induce substantial correlation between realisations, hence reducing the variance of the estimator. The computational advantage of our rejection‐based approach in comparison with the traditional inverse transformation is that it only needs to maintain a single data structure storing propensity bounds of reactions, which is updated infrequently, hence achieving better performance.Inspec keywords: biochemistry, data structures, biology computing, inverse transforms, stochastic processes, large‐scale systemsOther keywords: stochastic simulation estimation, anticorrelated variance reduction technique, stochastic simulation algorithm, computational cost, independent simulation runs, rejection‐based SSA, reaction firings, rejection‐based mechanism, anticorrelated variance technique, substantial correlation, estimator, rejection‐based approach, single data structure storing propensity, biochemical reactions, anticorrelated variance reduction     

Design problem of the profile or the cascade of profiles and construction of orthogonal networks using the Riemann surfaces for the multiform singularities

The complex potential induced by the source-vortex distribution is a multi-values function. In order to treat the field problem defined by the Dirichlet type boundary condition, it is necessary to get its correct value which has to be taken from an appropriate sheet of the Riemann surface. For the analytical formulations of a homogeneous density distribution over a segment or a cascade of segments, it can be done that the multi-value part is located at one of the end points of each segment. An algorithm is proposed to get the appropriate definition according to the relative positions of the induction element with the reception point. The construction of an orthogonal network inside a domain by solving the Dirichlet problem is shown. The simple layer distributions on the boundaries of the domain are used to generate the field in this example. The turbomachine blading design in connection with the flow field problem is described. The proposed method admits the thickness distribution and the bound vortex distribution as the initial data. In the case of the 2D cascade, we show how to define the boundary conditions in order to obtain a properly posed field problem.     

A meshless solution to two-dimensional convection–diffusion problems

An integral equation domain decomposition method has been implemented in a meshless fashion. The method exploits the advantage of placing the source point always in the centre of circular sub-domains in order to avoid singular or near-singular integrals. Three equations for two-dimensional (2D) or four for three-dimensional (3D) potential problems are required at each node. The first equation is the integral equation arising from the application of the Green's identities and the remaining equations are the derivatives of the first equation in respect to space coordinates. Radial basis function interpolation is applied in order to obtain the values of the field variable and partial derivatives at the boundary of the circular sub-domains, providing this way the boundary conditions for solution of the integral equations at the nodes (centres of circles). Dual reciprocity method (DRM) has been applied to convert the domain integrals into boundary integrals, though the approach is general and can be applied without the DRM. The accuracy and robustness of the method has been tested on a convection–diffusion problem. The results obtained using the current approach have been compared with previously reported results obtained using the finite element method (FEM), and the DRM multi-domain approach (DRM-MD) showing similar level of accuracy.     

Mood, personality, and self-monitoring: Negative affect and emotionality in relation to frontal lobe mechanisms of error monitoring.

A fundamental question in frontal lobe function is how motivational and emotional parameters of behavior apply to executive processes. Recent advances in mood and personality research and the technology and methodology of brain research provide opportunities to address this question empirically. Using event-related-potentials (ERPs) to track error monitoring in real time, the authors demonstrated that variability in the amplitude of the error-related negativity (ERN) is dependent on mood and personality variables. College students who are high on negative affect (NA) and negative emotionality (NEM) displayed larger ERN amplitudes early in the experiment than participants who are low on these dimensions. As the high-NA and -NEM participants disengaged from the task, the amplitude of the ERN decreased. These results reveal that affective distress and associated behavioral patterns are closely related with frontal lobe executive functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the macroscopic elastic moduli of inhomogeneous materials and random orthorhombic polycrystals

Real-world randomly inhomogeneous materials generally do not have unique macroscopic (effective) elastic moduli, but those scattered over some uncertainty intervals. Macroscopic isotropy and homogeneity hypotheses for the materials should be weakened to take into account this fact. We derive the explicit expressions of the best available upper and lower estimates on the uncertainty ranges for the moduli of practical random orthorhombic polycrystals (the shape and crystalline orientations of their grains are uncorrelated), with illustrating numerical results.     

Highly nonlinear solitary waves in chains of hollow spherical particles

We study the dynamic response of one- dimensional granular chains composed of uniform hollow spheres excited by an impulse, and we observe the formation and propagation of highly nonlinear solitary waves. We find that the dynamics of these solitary waves are different from the solitary waves forming in chains composed of uniform solid spheres, because of the changes in the contact interaction between particles. We study the quasi-static contact interaction between two hollows spheres using finite element (FE) simulations, and approximate their response as a power-law type function in the range of forces of interest for this work. The experimental data obtained by testing a chain of particles shows good agreement with theoretical predictions obtained using a long wavelength approximation, and with numerical simulations based on discrete particle and FE models. We also investigate the effect of hollow spheres’ wall thickness on the dynamic response of the chains.     

Creating resilient and sustainable manufacturing businesses – a conceptual fitness model

Over recent years, UK manufacturing industry has experienced turbulence in its business performance. Lower cost products, and responsive and flexible processes, are now essential in order for a company to capture new markets and to become economically resilient. Business resiliency is a term used frequently to describe a company’s ability to adapt and cope with disturbance. This has led to the generation of many frameworks and models aimed at guiding companies towards improved business performance. However, these frameworks are primarily strategic in nature and do not necessarily focus on creating resilience at an operational level in manufacturing companies. The authors employ a mixed research approach initially undertaking a literature review and then a screening survey in to 25 manufacturing companies in order to identify the key business resiliency techniques employed. Following this, a focus group goes on to detail a new manufacturing resiliency model called the fit operational model. The model’s effectiveness is then assessed and adjusted as a result of being implemented in a subject company.     

The use and success of activity-based management practices at different organisational life cycle stages

This study examines the association between organisational life cycle (OLC) stages and the use and success of activity-based management (ABM) practices. The results reveal that maturity and revival stage business units use each level of ABM to a greater extent than those in the birth, growth and decline stages. In addition, while the level of ABM success does not differ across OLC stages, ABM success is dependent upon business units using each ABM practice to the greatest extent. The findings provide managers with an insight into the appropriateness of using ABM practices at different OLC stages.