This manuscript introduces a new Bayesian finite mixture methodology for the joint clustering of row and column stimuli/objects associated with two-mode asymmetric proximity, dominance, or profile data. That is, common clusters are derived which partition both the row and column stimuli/objects simultaneously into the same derived set of clusters. In this manner, interrelationships between both sets of entities (rows and columns) are easily ascertained. We describe the technical details of the proposed two-mode clustering methodology including its Bayesian mixture formulation and a Bayes factor heuristic for model selection. We present a modest Monte Carlo analysis to investigate the performance of the proposed Bayesian two-mode clustering procedure with respect to synthetically created data whose structure and parameters are known. Next, a consumer psychology application is provided examining physician pharmaceutical prescription behavior for various brands of prescription drugs in the neuroscience health market. We conclude by discussing several fertile areas for future research.

A new Bayesian multinomial probit model is proposed for the analysis of panel choice data. Using a parameter expansion technique, we are able to devise a Markov Chain Monte Carlo algorithm to compute our Bayesian estimates efficiently. We also show that the proposed procedure enables the estimation of individual level coefficients for the single-period multinomial probit model even when the available prior information is vague. We apply our new procedure to consumer purchase data and reanalyze a well-known scanner panel dataset that reveals new substantive insights. In addition, we delineate a number of advantageous features of our proposed procedure over several benchmark models. Finally, through a simulation analysis employing a fractional factorial design, we demonstrate that the results from our proposed model are quite robust with respect to differing factors across various conditions.

Lake settlements, particularly crannogs, pose several contradictions—visible yet inaccessible, widespread yet geographically restricted, persistent yet vulnerable. To further our understanding, we developed the integrated use of palaeolimnological (scanning XRF, pollen, spores, diatoms, chironomids, Cladocera, microcharcoal, biogenic silica, SEM-EDS, stable-isotopes) and biomolecular (faecal stanols, bile acids, sedaDNA) analyses of crannog cores in south-west Scotland and Ireland. Both can be effective methods sets for revealing occupation chronologies and identifying on-crannog activities and practices. Strong results from sedaDNA and lipid biomarker analyses demonstrate probable on-site animal slaughter, food storage and possible feasting, suggesting multi-period, elite site associations, and the storage and protection of valuable resources.

Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990–1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.

A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.

Photoreflectance spectroscopy (PR) and spectral ellipsometry (SE) have been used to characterize the doping and structure of heterojunction bipolar transistors (HBT). This information provides a more complete description of the epitaxial HBT structure than is possible by relying solely on electrical characterization of specially processed test structures. Additional benefit is derived from the nondestructive nature of both SE and PR. The measurements are fast enough to be implemented on all production-bound HBT material. We describe our recent results comparing capacitance-voltage measurements with PRderived doping levels in the emitter layer of the HBT. We also describe some work comparing SE fit results with Auger electron spectroscopy depth profiles for InGaAs contact layer composition and thickness.

In this paper, the effect of atomic hydrogen on carbon impurity incorporation during the metalorganic-molecular-beam-epitaxy (MOMBE) growth of GaAs is studied. Atomic hydrogen was introduced into the MOMBE chamber during the growth by cracking molecular hydrogen with a high temperature cracker cell. Atomic hydrogen appears to be effective in reducing the background doping level of MOMBE-grown GaAs, presumably by reacting with hydrocarbon radicals. Background doping levels as low as 4 × 1014 cm−3 and room temperature hole mobilities as high as 430 cm2/V-sec were achieved. This result demonstrates that it is feasible to grow high quality GaAs films in MOMBE without using AsH3 or a high flux of As4by introducing atomic hydrogen into the chamber during the growth.