Optimal designs for conjoint experiments.

Design; Model-sensitive; Optimal; Optimal design; Data;

Mode expansion for the density profile of crystal-fluid interfaces: Hard spheres as a test case

We present a technique for analyzing the full three-dimensional density profiles of a planar crystal-fluid interface in terms of density modes. These density modes can also be related to crystallinity order parameter profiles which are used in coarse-grained, phase field type models of the statics and dynamics of crystal-fluid interfaces and are an alternative to crystallinity order parameters extracted from simulations using local crystallinity criteria. We illustrate our results for the hard sphere system using finely-resolved, three-dimensional density profiles from density functional theory of fundamental measure type.Comment: submitted for the special issue of the CODEF III conferenc

A Scanning Electron Microscope and in Vitro Study of Meliola palmicola

The genus Meliola contains about 1,000 species of epiphyllic plant parasitic fungi that produce mycelia with characteristic capitate and mucronate hyphopodia. Growth of these fungi in culture or as artifical inoculations on leaves has never been reported. This paper presents some observations on the morphology of the fungus as seen with the scanning electron microscope (SEM), and some results obtained in culture studies

An efficient algorithm for constructing Bayesian optimal choice designs.

Recently, Kessels et al. (2006) developed a way to produce Bayesian G- and V-optimal designs for the multinomial logitmodel. These designs allow for precise response predictions which is the goal of conjoint choice experiments. The authors showed that the G- and V- optimality criteria outperform the D- and A-optimality criteria for prediction. However, their G- and V-optimal design algorithm is computationally intensive, which is a barrier to its use in practice. In this paper, we present an efficient algorithm for calculating Bayesian optimal designs by means of the different criteria. Particularly, the speed of computation for the V-optimality criterion has improved dramatically.The new algorithm makes it possible to use Bayesian D-, A-, G- and V-optimal designs that are tailored to individual respondents in computerized conjoint choice studies.Adaptive algorithm; Bayesian D-,A-,G- and V-optimality; Cholesky decomposition; Conjoint choice design; Coordinate-exchange; Conjoint choice experiments;

Design criteria to develop choice experiments to measure the WTP accurately.

To measure the willingness-to-pay (WTP) accurately, Vermeulen et al.[2008] apply the c-optimality criterion to generate designs for conjoint choice experiments. This criterion is based on minimizing the sum of the variances of the WTP estimators approximated by the delta method. Designs generated based on this criterion lead to more accurate WTP estimates than the ones obtained by standard designs and reduce considerably the occurrence of extreme WTP estimates, although they do not exclude them. In this paper, other optimality criteria are considered to tackle this problem. We distinguish between criteria in preference space on the one hand and criteria in WTP-space on the other hand. In a simulation study and a numerical example, we compare the accuracy of the WTP and the utility coefficient estimates yielded by the designs based on these new criteria.conjoint choice experiment; Bayesian optimal design; willingness-to-pay; conditional logit model;

DD-optimal saturated designs: a simulation study

In this work we focus on saturated $D$-optimal designs. Using recent results, we identify $D$-optimal designs with the solutions of an optimization problem with linear constraints. We introduce new objective functions based on the geometric structure of the design and we compare them with the classical $D$-efficiency criterion. We perform a simulation study. In all the test cases we observe that designs with high values of $D$-efficiency have also high values of the new objective functions.Comment: 8 pages. Preliminary version submitted to the 7th IWS Proceeding

Density functional theory for hard-sphere mixtures: the White-Bear version Mark II

In the spirit of the White-Bear version of fundamental measure theory we derive a new density functional for hard-sphere mixtures which is based on a recent mixture extension of the Carnahan-Starling equation of state. In addition to the capability to predict inhomogeneous density distributions very accurately, like the original White-Bear version, the new functional improves upon consistency with an exact scaled-particle theory relation in the case of the pure fluid. We examine consistency in detail within the context of morphological thermodynamics. Interestingly, for the pure fluid the degree of consistency of the new version is not only higher than for the original White-Bear version but also higher than for Rosenfeld's original fundamental measure theory.Comment: 16 pages, 3 figures; minor changes; J. Phys.: Condens. Matter, accepte

Optimal two-level conjoint designs with constant attributes in the profile sets

We propose a simple strategy to construct D-, A-, G- and V-optimal two-level designs for rating-based conjoint studies with large numbers of attributes. In order to simplify the rating task, the designs hold one or more attributes at a constant level in each profile set. Our approach combines orthogonal designs and binary incomplete block designs with equal replication. The designs are variance-balanced meaning that they yield an equal amount of information on each of the part-worths

A hard-sphere model on generalized Bethe lattices: Statics

We analyze the phase diagram of a model of hard spheres of chemical radius one, which is defined over a generalized Bethe lattice containing short loops. We find a liquid, two different crystalline, a glassy and an unusual crystalline glassy phase. Special attention is also paid to the close-packing limit in the glassy phase. All analytical results are cross-checked by numerical Monte-Carlo simulations.Comment: 24 pages, revised versio

Efficient Expression of Naked Plasmid DNA in Mucosal Epithelium: Prospective for the Treatment of Skin Lesions

Mucocutaneous gene therapy offers exciting new treatment modalities for skin lesions. Transient expression of naked plasmid DNA could be used as a local treatment of various skin lesions where the corresponding gene product (protein) has therapeutic or immunization potential. We analyzed the time course, magnitude, and histologic expression of the indicator plasmid DNA (pCMV:β-Gal) in mucosal epithelium and papilloma lesions. Upon direct injection of naked plasmid DNA (20 μg) into oral mucosa, expression occurred at high local concentrations, up to 35-fold higher than in comparable injections into the epidermis. Due to the accelerated turnover of mucosal epithelium β-galactosidase positive epithelial cells were detected in the basal and suprabasal layers as early as 3 h after injection, whereas only the most superficial mucosal layers demonstrated β-galactosidase staining at 24 h post-injection. These biologic characteristics need to be taken into consideration when clinical applications of expressing naked plasmid DNA in epithelial tissues are considered