A simulation‐based algorithm for optimal pricing policy under demand uncertainty

We propose a simulation‐based algorithm for computing the optimal pricing policy for a product under uncertain demand dynamics. We consider a parameterized stochastic differential equation (SDE) model for the uncertain demand dynamics of the product over the planning horizon. In particular, we consider a dynamic model that is an extension of the Bass model. The performance of our algorithm is compared to that of a myopic pricing policy and is shown to give better results. Two significant advantages with our algorithm are as follows: (a) it does not require information on the system model parameters if the SDE system state is known via either a simulation device or real data, and (b) as it works efficiently even for high‐dimensional parameters, it uses the efficient smoothed functional gradient estimator.     

Microstructure and electrical characterisations of K-modified PLZT

Potassium-modified PLZT [Pb_0.92(La_{1 – z}K_z)_0.08(Zr_0.60Ti_0.40)_{0.98 + 0.04z}O₃ (z = 0.0, 0.1, 0.3, 0.5, 0.7)] ceramics were synthesised using sol-gel technique. Preliminary structural and microstructural parameters were determined using XRD, SEM and TEM techniques. Detailed studies of dielectric properties at 10 kHz in a wide temperature range suggest that the compounds have diffuse phase transition of second order. Studies of spontaneous polarisation, pyroelectric and piezoelectric properties yielded data for devices.     

Preparation of water-dispersible graphene by facile surface modification of graphite oxide

Water-dispersible graphene was prepared by reacting graphite oxide and 6-amino-4-hydroxy-2-naphthalenesulfonic acid (ANS). X-ray diffraction study showed that the basal reflection (002) peak of graphite oxide was absent in the ANS-functionalized graphene (ANS-G), indicating crystal layer delamination. Ultraviolet-visible spectral data were recorded to assess the solubility of the ANS-G in water. Fourier transform infrared spectral analysis suggested the attachment of ANS molecules to the surface of graphene. Raman and x-ray photoelectron spectroscopy revealed that oxygen functionality in the graphite oxide had been removed during reduction. Atomic force microscopy found that the thickness of ANS-G in water was about 1.8 nm, much higher than that of single layer graphene. Thermal stability measurements also indicated successful removal of oxygen functionality from the graphite oxide and the attachment of thermally unstable ANS to the graphene surfaces. The electrical conductivity of ANS-G, determined by a four-point probe, was 145 S m(-1) at room temperature.     

The effect of probe coherence and atomic coherence on the response of an open lambda-type pump–probe system

The response of a coherently prepared four-level λ-type system, interacting with two electromagnetic fields in a Doppler-free pump–probe configuration is analytically formulated. Under density matrix formalism the probe coherence (field-dependent phase) and atomic coherence (field-independent phase) are introduced through the off-diagonal matrix elements. The coherent effects on probe response is investigated for probe coherence, as well as for the driving contribution (coherence) of the pump field. We show how probe coherence can modify the Rabi splitting and two-photon absorption, through shifting and broadening of spectral lines for on- and off-resonance pumping, respectively. In addition, we report on the enhancement of absorptionless dispersion (i.e. refractive index for on and around probe resonance) and two-photon absorption, via coherent control of the driving contribution of the pump field.     

Like-minded communities: bringing the familiarity and similarity together

Community detection in social networks is a well-studied problem. A community in social network is commonly defined as a group of people whose interactions within the group are more than outside the group. It is believed that people’s behavior can be linked to the behavior of their social neighborhood. While shared characteristics of communities have been used to validate the communities found, to the best of authors’ knowledge, it is not demonstrated in the literature that communities found using social interaction data are like-minded, i.e., they behave similarly in terms of their interest in items (e.g., movie, products). In this paper, we experimentally demonstrate, on a social networking movie rating dataset, that people who are interested in an item are socially better connected than the overall graph. Motivated by this fact, we propose a method for finding communities wherein like-mindedness is an explicit objective. We find small tight groups with many shared interests using a frequent item set mining approach and use these as building blocks for the core of these like-minded communities. We show that these communities have higher similarity in their interests compared to communities found using only the interaction information. We also compare our method against a baseline where the weight of edges are defined based on similarity in interests between nodes and show that our approach achieves far higher level of like-mindedness amongst the communities compared to this baseline as well.     

Why is sodium cocoyl isethionate (SCI) mild to the skin barrier?–An in vitro investigation based on the relative sizes of the SCI micelles and the skin aqueous pores

Sodium cocoyl isethionate (SCI) is an important surfactant ingredient in mild, syndet (synthetic detergent) cleansing bars. In vitro and in vivo studies have demonstrated that SCI is mild and less damaging to the skin barrier than soaps and surfactants such as sodium dodecyl sulfate (SDS). We have recently shown that SDS forms small micelles in aqueous solutions contacting the skin relative to the aqueous pores in the stratum corneum (SC), and as a result, the SDS micelles can contribute to SDS skin penetration and induce skin barrier perturbation. In this paper, we attempt to explain the well-documented skin mildness of SCI by examining the size of the SCI micelles relative to that of the aqueous pores in the SC. For this purpose, we have conducted in vitro mannitol skin permeability and average skin electrical resistivity measurements upon exposure of the skin to an aqueous SCI contacting solution in the context of a hindered-transport aqueous porous pathway model of the SC. These in vitro studies demonstrate that an SCI micelle of radius 33.5 ± 1 Å (as determined using dynamic light-scattering measurements) experiences significant steric hindrance and cannot penetrate into the SC through aqueous pores that have an average radius of 29 ± 5 Å.We believe that this inability of the SCI micelles to contribute to SCI skin penetration and associated skin barrier perturbation is responsible for the observed skin mildness of SCI. Through in vitro quantitative skin radioactivity assays using ¹⁴C-radiolabeled SCI and pig full-thickness skin (p-FTS), we also show conclusively that SCI skin penetration is dose-independent, an important finding that provides additional evidence that the larger SCI micelles cannot penetrate into the SC through the smaller aqueous pores that exist in the SC, and therefore, cannot induce skin barrier perturbation.     

Evolution of multivariant microstructures with anisotropic misfit: A phase field study

We study, in two dimensions, the effect of misfit anisotropy on microstructural evolution during precipitation of an ordered β phase from a disordered α matrix; these phases have, respectively, 2- and 6-fold rotation symmetries. Thus, precipitation produces three orientational variants of β phase particles, and they have an anisotropic (and crystallographically equivalent) misfit strain with the matrix. The anisotropy in misfit is characterized using a parameter t = ?_yy/?_xx, where ?_xx and ?_yy are the principal components of the misfit strain tensor. Our phase field simulations show that the morphology of β phase particles is significantly influenced by t, the level of misfit anisotropy. Particles are circular in systems with dilatational misfit (t = 1), elongated along the direction of lower principal misfit when 0 < t < 1 and elongated along the invariant direction when ?1 ? t ? 0. In the special case of a pure shear misfit strain (t = ?1), the microstructure exhibits star, wedge and checkerboard patterns; these microstructural features are in agreement with those in Ti–Al–Nb alloys.     

Enhanced properties of lignin-based biodegradable polymer composites using injection moulding process

Composites from polybutylene succinate (PBS) and lignin-based natural material were fabricated using a melt mixing process. The effects of lignin material and polymeric methylene diphenyl diisocyanate (PMDI) compatibilizer on the properties of composites were investigated. Incorporation of 65% lignin material into PBS was achieved with an improvement in the tensile and flexural properties of composites. Incorporation of 1% PMDI in 50% lignin filled composites enhanced the tensile, flexural and impact strength simultaneously. Heat deflection temperature (HDT) of the virgin plastic also increased with lignin and PMDI incorporation. Improved interfacial adhesion was observed from SEM micrographs of the compatibilized composites.