Comparative odontometry of the permanent post-canine dentition of American Whites and Negroes

The permanent post-canine teeth of American Whites and American Negroes of the New York City area were studied odontometrically. The mesio-distal and bucco-lingual dimensions of the crowns were measured, as was the total tooth height and crown height. The individual root lengths of these teeth were also measured, in several ways, as was root width. The mean total root volumes of these teeth was measured by a unique mercury displacement method. In another aspect of this study the mean angular divergence of the roots from a mid-coronal vertical plane was determined, while the robustness of these roots was described as a ratio between root width and length. Finally, an extensive comparison was made between our data and those in the literature on a number of African Negro populations. American Negro tooth crown and root dimensions and volumes were significantly different from those of American Whites only sporadically, although the Negro teeth usually tended to be larger. Our comparative data gave some indication that the size of both the maxillary and mandibular American negro teeth, as well as the shape of the mandibular (but not the maxillary) American Negro teeth are roughly intermediate between those of American Whites and South African Negroes. This suggestion that a “hybrid” population may possess intermediate values of crown index and of crown module is supported by our analysis of Hottentot-South African Negro hybrids with their presumptive parental stocks.     

Anterior femoral curvature: Its probable basis and utility as a criterion of racial assessment

Stewart ('62) and Walensky ('65) indicated that while the metrical expression of anterior femoral curvature alone will not always differentiate between Whites, American Negroes, and North American Indians, it was very useful as a racial criterion in combination with observed traits such as torsion, pilastry, and cross-sectional shape. Seven additional North American Indian groups reported here, representing both pre-Columbian and post-contact times, upheld the observation that anterior femoral curvature is a useful feature of racial assessment for Negroes, Whites and North American Indians. However, two South American groups studied (Ecuador and Peru) were only slightly more curved than American Negroes, and were less curved than Whites and North American Indians. The metrical expression of anterior femoral curvature therefore is not a useful feature of racial assessment for separating these two South American Indian groups from Whites and American Negroes. Femora of American Negro and White individuals with low ponderal indices were found to be less bowed than the norms for their race; individuals with high ponderal indices were more bowed than the norm for their race. The assumed genetic basis for expression of anterior femoral curvature suggested by Stewart ('62) and Walensky ('65) seems to be a feature of human plastic response to body weight rather than to temporal, clinal, postural or equestrian influences.     

Race and Ethnic Differences in Religious Involvement: African Americans, Caribbean Blacks and Non-Hispanic Whites

This study examined differences in religious participation and spirituality among African Americans, Caribbean Blacks (Black Caribbeans) and non-Hispanic Whites. Data are taken from the National Survey of American Life, a nationally representative study of African Americans, Black Caribbeans and non-Hispanic Whites. Selected measures of organizational, nonorganizational and subjective religious participation were examined. African American and Caribbean Blacks were largely similar in their reports of religious involvement; both groups generally indicated higher levels of religious participation than non-Hispanic Whites. African Americans were more likely than Black Caribbeans to be official members of their places of worship, engage in activities (choirs, church clubs) at their place of worship and request prayer from others. Black Caribbeans reported reading religious materials more frequently than African Americans. The discussion notes the importance of examining ethnic differences within the black American population of the United States.     

Optimal designs for a multiresponse Emax model and efficient parameter estimation

The aim of dose finding studies is sometimes to estimate parameters in a fitted model. The precision of the parameter estimates should be as high as possible. This can be obtained by increasing the number of subjects in the study, N, choosing a good and efficient estimation approach, and by designing the dose finding study in an optimal way. Increasing the number of subjects is not always feasible because of increasing cost, time limitations, etc. In this paper, we assume fixed N and consider estimation approaches and study designs for multiresponse dose finding studies. We work with diabetes dose–response data and compare a system estimation approach that fits a multiresponse Emax model to the data to equation‐by‐equation estimation that fits uniresponse Emax models to the data. We then derive some optimal designs for estimating the parameters in the multi‐ and uniresponse Emax model and study the efficiency of these designs.     

Testing assumptions of the Gilbert and Gill method for assessing ancestry using the femur subtrochanteric shape

In 1990, Gilbert and Gill proposed a simple metric technique using femoral subtrochanteric anteroposterior and mediolateral diaphyseal diameters for discriminating between Native American and American Black and White femora in medicolegal and bioarchaeological contexts. However, there are several inherent assumptions in the method that may affect its validity. The assumptions include minimal sexual dimorphism, temporal and geographical homogeneity within populations, and that differences between populations in femoral subtrochanteric size and shape are primarily due to genetic variation. In this study, these assumptions are tested using femora from seven populations (African, American Black, American White, Australian, Native American, Hispanic, and Polynesian). The results indicate that sexual dimorphism and geographical and temporal heterogeneity in proximal femur diaphyseal shape within Native Americans are not great enough to significantly affect the validity of the Gilbert and Gill method (GGM). Variation between populations is most likely due to combined genetic and environmental factors, but differences in proximal femur shape between Native Americans and American Blacks/Whites are sufficient to allow accurate discrimination between these groups. Caution, however, must be taken during investigations where populations other than Native Americans or American Blacks/Whites are present, and therefore, the GGM may have limited forensic anthropological application in many parts of the world.     

Sex differences in height and sitting height in the Belgian population

Sex differences in growth were studied in a longitudinal study of 39 boys and 31 girls for sitting height. Individual growth patterns were determined by means of Preece Baines model 1. The results showed no significant bias in the fits of height and sitting height in boys and girls. Girls fits were significantly better than those of the boys for both height and sitting height. Univariate analysis by means of Mann-Whitney test showed significant sex differences for all function and biological parameters of height and sitting height excepted for s₁ parameter (the rate constant controlling pubertal velocity). Linear discriminant analysis revealed that the strongest sex differences for the timing and size parameters at adolescent. Peak velocity at adolescent was slightly less discriminating between the two sexes and velocity at take-off showed the least sex difference. These trends were similar for height and sitting height. Decomposition of sex differences in adult size showed that the major contributor to adult the sex differences is the effect of the later onset of the adolescent growth spurt in boys than in girls. Sex differences in adult phenotypes of height and sitting height are to a slightly lesser extent due to the greater adolescent gain in boys while prepubertal sex differences are almost negligible.     

Estimation of coefficients in a model of radiation-induced myelopoiesis from mortality data for mice following X-ray exposure

The rate coefficients in the model of cell kinetics and mortality introduced by Jones et al. (Radiat. Res. 128, 258-266 (1991)) are estimated using mortality data from several mouse experiments. The evaluated model fits data from a large variety of prompt, protracted, and fractionated irradiations with 250-k Vp X rays with good fidelity. Although the maximum-likelihood estimates are not unique, all estimates lead to greater cell survival than that observed in in vitro experiments on nonterminally differentiated reproducing cells from the marrow.     

Genetic analysis of the predisposition to audiogenic seizure fits in Krushinsky-Molodkina rat strain

The expression of audiogenic seizure fits has been studied in F1 hybrids between audiogenic seizure-prone Krushinsky-Molodkina rat strain and Wistar rats not prone to audiogenic seizures, as well as in two backcross generations. Only 10% of F1 hybrids exhibit audiogenic seizure fits, whereas the frequency of this character in two generations of their backcrosses with Krushinsky-Molodkina rats is about 50%. A digenic model with incomplete penetrance has been put forward to explain the control of audiogenic seizure fits. This model fits the data obtained: the theoretically expected distributions of the character in offsprings of different crosses do not differ significantly from those observed in experiments. The model explains why the distribution of the character is the same in the first and second backcross offsprings.     

Mechanistic modeling of the loss of protein sieving due to internal and external fouling of microfilters

Fed‐batch and perfusion cell culture processes used to produce therapeutic proteins can use microfilters for product harvest. In this study, new explicit mathematical models of sieving loss due to internal membrane fouling, external membrane fouling, or a combination of the two were generated. The models accounted for membrane and cake structures and hindered solute transport. Internal membrane fouling was assumed to occur due to the accumulation of foulant on either membrane pore walls (pore‐retention model) or membrane fibers (fiber‐retention model). External cake fouling was assumed to occur either by the growth of a single incompressible cake layer (cake‐growth) or by the accumulation of a number of independent cake layers (cake‐series). The pore‐retention model was combined with either the cake‐series or cake‐growth models to obtain models that describe internal and external fouling occurring either simultaneously or sequentially. The models were tested using well‐documented sieving decline data available in the literature. The sequential pore‐retention followed by cake‐growth model provided a good fit of sieving decline data during beer microfiltration. The cake‐series and cake‐growth models provided good fits of sieving decline data during the microfiltration of a perfusion cell culture. The new models provide insights into the mechanisms of fouling that result in the loss of product sieving. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1323–1333, 2017     

Comparative kinetics of embryo development

A model of embryo energetics was fitted to data from the literature for species as different as snails and mammals. The model is based on assumptions about energy uptake, storage and utilization. It describes the animal by two state variables: volume and energy storage. Embryo weight is taken to be proportional to volume, yolk weight to energy storage, and respiration rate to storage utilization rate. The fits were good, with minor deviations occurring only in the early phases of development. For altricial birds, good model fits were obtained, but the parameter values markedly differed from those of other species. We hypothesized that, due to an increase in energy utilization towards hatching, the temperature of the embryo increases. As a result, metabolic processes are accelerated. When this was taken into account, parameter values were obtained that correspond better with those of other animals.     

Genetic Analysis of the Predisposition to Audiogenic Seizure Fits in Krushinsky-Molodkina Rat Strain

The expression of audiogenic seizure fits has been studied in F₁ hybrids between audiogenic seizure-prone Krushinsky-Molodkina rat strain and Wistar rats not prone to audiogenic seizures, as well as in two backcross generations. Only 10% of F₁ hybrids exhibit audiogenic seizure fits, whereas the frequency of this character in two generations of their backcrosses with Krushinsky-Molodkina rats is about 50%. A digenic model with incomplete penetrance has been put forward to explain the control of audiogenic seizure fits. This model fits the data obtained: the theoretically expected distributions of the character in offsprings of different crosses do not differ significantly from those observed in experiments. The model explains why the distribution of the character is the same in the first and second backcross offsprings.     

Spherical indentation of soft matter beyond the Hertzian regime: numerical and experimental validation of hyperelastic models

The lack of practicable nonlinear elastic contact models frequently compels the inappropriate use of Hertzian models in analyzing indentation data and likely contributes to inconsistencies associated with the results of biological atomic force microscopy measurements. We derived and validated with the aid of the finite element method force-indentation relations based on a number of hyperelastic strain energy functions. The models were applied to existing data from indentation, using microspheres as indenters, of synthetic rubber-like gels, native mouse cartilage tissue, and engineered cartilage. For the biological tissues, the Fung and single-term Ogden models achieved the best fits of the data while all tested hyperelastic models produced good fits for the synthetic gels. The Hertz model proved to be acceptable for the synthetic gels at small deformations (strain < 0.05 for the samples tested), but not for the biological tissues. Although this finding supports the generally accepted view that many soft materials can be assumed to be linear elastic at small deformations, the nonlinear models facilitate analysis of intrinsically nonlinear tissues and large-strain indentation behavior.     

Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort

Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2–31.6% (p = 5.4x10^-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10^-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke.     

The stay/switch model describes choice among magnitudes of reinforcers

The stay/switch model is an alternative to the generalized matching law for describing choice in concurrent procedures. The purpose of the present experiment was to extend this model to choice among magnitudes of reinforcers. Rats were exposed to conditions in which the magnitude of reinforcers (number of food pellets) varied for staying at alternative 1, switching from alternative 1, staying at alternative 2 and switching from alternative 2. A changeover delay was not used. The results showed that the stay/switch model provided a good account of the data overall, and deviations from fits of the generalized matching law to response allocation data were in the direction predicted by the stay/switch model. In addition, comparisons among specific conditions suggested that varying the ratio of obtained reinforcers, as in the generalized matching law, was not necessary to change the response and time allocations. Other comparisons suggested that varying the ratio of obtained reinforcers was not sufficient to change response allocation. Taken together these results provide additional support for the stay/switch model of concurrent choice.     

Confined and unconfined stress relaxation of cartilage: appropriateness of a transversely isotropic analysis.

Previous studies have shown that stress relaxation behavior of calf ulnar growth plate and chondroepiphysis cartilage can be described by a linear transverse isotropic biphasic model. The model provides a good fit to the observed unconfined compression transients when the out-of-plane Poisson's ratio is set to zero. This assumption is based on the observation that the equilibrium stress in the axial direction (deltaz) is the same in confined and unconfined compression, which implies that the radial stress deltar = 0 in confined compression. In our study, we further investigated the ability of the transversely isotropic model to describe confined and unconfined stress relaxation behavior of calf cartilage. A series of confined and unconfined stress relaxation tests were performed on calf articular cartilage (4.5 mm diameter, approximately 3.3 mm height) in a displacement-controlled compression apparatus capable of measuring delta(z) and delta(r). In equilibrium, delta(r) > 0 and delta(z) in confined compression was greater than in unconfined compression. Transient data at each strain were fitted by the linear transversely isotropic biphasic model and the material parameters were estimated. Although the model could provide good fits to the unconfined transients, the estimated parameters overpredicted the measured delta(r). Conversely, if the model was constrained to match equilibrium delta(r), the fits were poor. These findings suggest that the linear transversely isotropic biphasic model could not simultaneously describe the observed stress relaxation and equilibrium behavior of calf cartilage.     

Biological relationships derived from morphology of permanent teeth: recent evidence from prehistoric India

Morphological variation in permanent teeth of prehistoric populations yields clues to their relationships with other prehistoric and living people. This paper documents variation in fourteen variants of the permanent tooth crown for the late Chalcolithic skeletal series from Inamgaon (1600-700 BC), an early farming settlement in western India. In comparison of the dental morphology profile at Inamgaon with American Indians and American Whites, the people of Inamgaon were found to more closely resemble American Whites. However, specific traits deviated in the direction of Amerindian dental trait frequencies, suggesting gene flow from north and east Asian populations. The dental morphology of the Inamgaon sample is similar to dental patterns characteristic of prehistoric Pakistani samples from Sarai Khola and Timargarha. However, Inamgaon and Timargarha exhibit somewhat more complex crown morphology than the Sarai Khola sample, suggesting a closer relationship between them and greater antiquity of residence in the subcontinent, in contrast to Sarai Khola sample.     

A stochastic carcinogenesis model incorporating multiple types of genomic instability fitted to colon cancer data

A generalization of the two-mutation stochastic carcinogenesis model of Moolgavkar, Venzon and Knudson and certain models constructed by Little [Little, M.P. (1995). Are two mutations sufficient to cause cancer? Some generalizations of the two-mutation model of carcinogenesis of Moolgavkar, Venzon, and Knudson, and of the multistage model of Armitage and Doll. Biometrics 51, 1278-1291] and Little and Wright [Little, M.P., Wright, E.G. (2003). A stochastic carcinogenesis model incorporating genomic instability fitted to colon cancer data. Math. Biosci. 183, 111-134] is developed; the model incorporates multiple types of progressive genomic instability and an arbitrary number of mutational stages. The model is fitted to US Caucasian colon cancer incidence data. On the basis of the comparison of fits to the population-based data, there is little evidence to support the hypothesis that the model with more than one type of genomic instability fits better than models with a single type of genomic instability. Given the good fit of the model to this large dataset, it is unlikely that further information on presence of genomic instability or of types of genomic instability can be extracted from age-incidence data by extensions of this model.     

Modelling large herbivore movement decisions: Beyond food availability as a predictor of ranging patterns

The ability of animals to adapt to their changing environment will depend in part on shifts in their ranging patterns, but when and why individuals choose to move requires detailed understanding of their decision‐making processes. We develop a simple decision‐making model accounting for resource availability in habitually used ranges. We suggest that disparities between model predictions and animal tracking data indicate additional factors influencing movement decisions, which may be identified given detailed system‐specific knowledge. The model was evaluated using movement data from satellite‐tracked elephants (Loxodonta africana) inhabiting the Amboseli basin in Kenya, moving from savannah areas with low quality but constant resource availability, to areas with temporally constrained higher nutrient availability. Overall, the model fits the data well: There was a good correlation between predicted and observed locations for the combined data from all elephants, but variation between individuals in how well the model fits. For those elephants where model predictions were less successful, additional factors likely to affect movement decisions, including reproduction, anthropogenic threats, memory and perception are suggested. This protocol for building and testing decision‐making models should contribute to success in attempts to preserve sufficient space for large herbivores in their increasingly human‐dominated ecosystems.     

Symmetric Bernoulli Distributions and Generalized Binomial Distributions

The generalized binomial distribution is defined as the distribution of a sum of symmetrically distributed Bernoulli random variates. Several two-parameter families of generalized binomial distributions have received attention in the literature, including the Polya urn model, the correlated binomial model and the latent variable model. Some properties and limitations of the three distributions are described. An algorithm for maximum likelihood estimation for two-parameter generalized binomial distributions is proposed. The Polya urn model and the latent variable model were found to provide good fits to sub-binomial data given by Parkes. An extension of the latent variable model to incorporate heterogeneous response probabilities is discussed.     

Coronal breadth of human primary anterior teeth

Original data for mesiodistal diameter of deciduous anterior teeth on 180 White children show: (1) mean size is smallest for the lower central incisor and largest for the upper canine, (2) means from combining widths on the left anterior teeth of each arch are larger in the maxilla than the mandible by 4.0 mm, (3) individual differences for widths of the upper central and lateral incisors extend from one child with these teeth of similar size to another child with the central incisor larger than the lateral by 2.3 mm, and (4) anterior tooth correlations are positive, varying from r = 0.4 for upper canine width with width of lower central incisor, to r = 0.8 for combined widths of left anterior teeth in the maxilla with combined widths of their antagonists. Comparative findings are drawn from investigations on Australian aborigines, South African Bushmen, Liberian Negroes, Tristan da Cunha islanders, Japanese, Japanese-Negro admixtures, Japanese-White admixtures, White groups living in several parts of Europe, and North American Whites. Among these ethnic groups, Australian aborigines have the largest deciduous anterior teeth. Composite means on each sex for North American Whites show boys to have slightly larger anterior deciduous teeth than girls.