Fundamental uncertainty in the BAO scale from isocurvature modes

Small fractions of isocurvature perturbations correlated with the dominant adiabatic mode are shown to be a significant primordial systematic for Baryon Acoustic Oscillation (BAO) surveys which must be accounted for in future surveys. Isocurvature modes distort the standard ruler distance by broadening and shifting the peak in the galaxy correlation function. While a single isocurvature mode does not significantly degrade dark energy constraints, the general case with multiple isocurvature modes leads to biases that exceed 7σ on average in the dark energy parameters even for isocurvature amplitudes undetectable by Planck. Accounting for all isocurvature modes corrects for this bias but degrades the dark energy figure of merit by at least 50% in the case of the Boss experiment. However the BAO data in turn provides significantly stronger constraints on the nature of the primordial perturbations. Future large galaxy surveys will thus be powerful probes of exotic physics in the early Universe in addition to helping pin down the nature of dark energy.     

Designing optimal global supply chains at Dow AgroSciences

The design of the underlying supply chain network can have a tremendous impact on the profitability, manageability, and level of risk of a global supply chain. Taxes, duties, and tariffs vary from country to country as well as trading bloc to trading bloc and can consume as much as 10% of the revenues of certain products. In the highly regulated business environment of agricultural chemicals, the country of origin of an active ingredient can determine where the final product can be marketed and the amount of taxes and duties applied to the product, making it necessary to trace all batches of product through many layers of the supply chain to their sources. This article presents a mixed integer linear programming model in use at Dow AgroSciences LLC that simultaneously optimizes the network design underlying global supply chains and the monthly production and shipping schedules for maximum profitability. This work contributes to the supply chain design literature by demonstrating a novel method of tracing products to their source for inventory valuation, taxation, and duty computation in a production environment where the products change into other products as they pass through nodes in the network. It also demonstrates an iterative scheme for determining unit fixed costs for fixed cost allocation for the same purposes. Finally, it provides a case study of a supply chain design initiative in a global enterprise.     

The baddeleyite-type high pressure phase of Ca(OH)2

Abstract

A phase transition from Ca(OH)₂ I (portlandite) to Ca(OH)₂ II at high pressure and temperature has been confirmed, using in situ x-ray diffraction in a multianvil high pressure device (DIA). The structure was determined at 9.5 GPa and room temperature from data collected after heating the sample at 300°C at 7.2 GPa in a diamond anvil cell. Both the Le Bail fit and preliminary Rietveld refinement suggest that the new phase, which reverts to Ca(OH), I during pressure release, has a structure related to that of baddeleyite (ZrO₁); it is monoclinic (P2₁/c) with a= 4.887(2), b= 5.834(2), c = 5.587(2), β = 99.74(2)°. The coordination number of Ca increases from six to seven (5 + 2) across the transition. At 500°C, the phase boundary is bracketed at 5.7 ± 0.4 GPa by reversal experiments performed in the DIA.     

Morphology of a Main Chain Liquid Crystal Polymer Containing Semi-Flexible Coupling Chain

A new procedure for the study of textures or director patterns in liquid crystal polymers is reported. The director patterns of the liquid crystal phase are decorated using a lower temperature crystalline phase, a process which does not disrupt the larger scale molecular organisation representative of the liquid crystal structure. The pattern of the decorating crystal lamellae is revealed using an etching technique; the director pattern lies orthogonal to these “lamellae”. Examples are shown of the texture relating to point and line defects. The potential of a quantitative approach to the director distribution about an inversion wall to provide numerical values of the curvature elastic constants is detailed.     

Functional Polymers. XXII. Ultraviolet Absorbers with 2(2-Hydroxyphenyl)2H-benzotriazole and 2-Hydroxybenzophenone (or Acetophenone) Chromophors in the Same Molecule

Benzotriazolization of 2,4-dihydroxyacetophenone and 2,4-dihydroxybenzophenone has given dibenzotriazolized products: 3,5- [di (2H-benzotriazole-2-yl)]2,4-dihydroxyacetophenone, and 3,5-[di (2H-benzotriazole-2-yl)] 2,4-dihydroxybenzophenone. These compounds are expected to be effective and useful UV absorbers as they both have the 2 (2-hydroxyphenyl)2H-benzotriazole unit and the 2-hydroxybenzophenone (or acetophenone) unit in the molecule. The compounds were characterized by their spectral behavior and particularly by careful study of their UV spectrum.     

Polymer morphology: Pure and applied

Polymer morphology has a unique role in macromolecular science. Because it deals primarily with images of microstructure, revealing actual organization in its inherent complexity rather than as oversimplified models, it provides a special wealth of information from which to draw inferences on molecular and other mechanisms involved in its formation and on the consequences for properties. The essential first step is to image the microstructure to allow the eye-brain combination to use its outstanding ability to interpret complex textural patterns. Not only have continual gains in fundamental understanding stemmed from corresponding advances in our ability to reveal and study morphology but so have insights leading to improved properties. These themes are illustrated with recent results for both pure and applied topics. The origin of spherulitic growth, the principal determinant of texture and thus properties in polymers, is a long-standing, sometimes controversial, issue. Now study of an academic system, monodisperse paraffins, has clearly negated the long-standing hypothesis of the responsibility of “impurities” in the melt. It also strongly supports previous suggestions that the essential cause is divergence of adjacent dominant lamellae from their branch points, due to the pressure of uncrystallized molecular cilia. The value of morphological studies in the development of commercial materials is illustrated, firstly, for advanced polyethylene fibers, both compacted and individual, in which novel longitudinal defects have been discovered, and then by details of impact-related failure in polypropylene copolymers.     

Electron microscopy and spherulitic organization in polymers

The principal purposes of this article are (1) to draw attention to the fact that it has recently become possible to study representative internal lamellar microsmctures of melt-crystallized polyolefines with the transmission electron microscope; (2) to describe the new techniques which have made this possible and consider how they may be used to best advantage; and (3) to discuss how this new capability has affected our knowledge and understanding of the internal organization and formation of polymer spherulites together with its implications for the future.     

The stability of W2 and WRe adatom clusters on (110) tungsten surfaces

Kinetics of formation and dissociation of W₂ and WRe adatom clusters and dissociation reaction equilibria on (110) W were studied by field ion microscopy. Deposits of two adatoms only on the (110) face of a tungsten FIM tip were used and these reached an equilibrium state at 400 K. For the W₂ dissociation reaction $\text{ΔA}{}^{\mathrm{?}}\text{(430}\text{K}\text{) = 30 ± 5}\text{kJ mol}{}^{\mathrm{?1}}$; for WRe dissociation $\text{ΔA}{}^{\mathrm{?}}\text{(400}\text{K}\text{) = 14 ± 2}\text{kJ mol}{}^{\mathrm{?1}}$. The dissociation energies indicated by kinetics were consistent with these values.