Economic impact on postnatal ossification

The magnitude of economic impact on postnatal ossification timing in generally lower-income boys and girls of European ancestry was found to be 0.21 standard deviation units or Z-scores for a difference of approximately $2200.00 in per-capita income. Both boys and girls were equally affected.     

Brief communication: Emergence chronology of permanent teeth in Nigerian children

This study measured the mean age, duration, and sequence of the emergence of permanent dentition in Nigerian children and compared the findings with other population groups. The cross‐sectional study involved 1,078 Nigerian children, aged 4–16 years old, from selected primary and secondary schools in the Ife Central local government area in Ile‐Ife, Osun State. In general, compared to boys, girls had an earlier mean age of emergence of all the permanent teeth. Children from high socioeconomic class had an earlier mean age of emergence for the maxillary incisors (6.43 and 7.58 years) and mandibular incisors (5.28 and 6.44 years) compared to children from middle and low socioeconomic classes, although socioeconomic effects were more mixed for premolars and molars. Compared to their counterparts in the USA, Australia, Belgium, and Iran, Nigerian children showed an earlier mean age of emergence of all the permanent teeth studied except for Pakistani boys, who had an earlier mean age of emergence of the maxillary premolars and second molar. Poorer economic status has been associated with delayed dental development; however, when compared to other populations, the Nigerian children in this study have earlier mean emergence ages than children from wealthier countries such as the USA and Australia. Am J Phys Anthropol 153:506–511, 2014. © 2013 Wiley Periodicals, Inc.     

Associations in emergence age among permenent teeth

Associations in the timing of emergence among the permanent teeth of Boston children were obtained from a mixed longitudinal growth study of 414 Caucasian twin pairs examined annually. Correlations were estimated by the method of maximum likelihood for corresponding left-right teeth, upper-lower teeth, and all paired combinations from central incisor to second molar in a jaw quadrant of each sex. Strong positive correlations in emergence timing prevailed throughout the dentition. Principal component analyses on correlation matrices of jaw quadrant relations for boys and girls in the maxilla and mandible showed that three components effectively explained the emergence associations among the seven permanent teeth in each jaw quadrant. Factor analytic techniques further illustrated the nature of the three components and showed the emergence relations to be essentially the same in the maxilla and mandible for both sexes. The first component was a general maturation factor influencing all of an individual's teeth to be simultaneously early or late in emerging. The remaining two components were a molar factor, affecting almost exclusively the emergence timing of the permanent first and second molars, and a duration factor that affected the duration of the emergence process for non-molar teeth, contrasting particularly the incisors and premolars.     

How Phenological Variation Affects Species Spreading Speeds

In this paper, we develop a phenologically explicit reaction–diffusion model to analyze the spatial spread of a univoltine insect species. Our model assumes four explicit life stages: adult, two larval, and pupa, with a fourth, implicit, egg stage modeled as a time delay between oviposition and emergence as a larva. As such, our model is broadly applicable to holometabolous insects. To account for phenology (seasonal biological timing), we introduce four time-dependent phenological functions describing adult emergence, oviposition and larval conversion, respectively. Emergence is defined as the per-capita probability of an adult emerging from the pupal stage at a particular time. Oviposition is defined as the per-capita rate of adult egg deposition at a particular time. Two functions deal with the larva stage 1 to larva stage 2, and larva stage 2 to pupa conversion as per-capita rate of conversion at a particular time. This very general formulation allows us to accommodate a wide variety of alternative insect phenologies and lifestyles. We provide the moment-generating function for the general linearized system in terms of phenological functions and model parameters. We prove that the spreading speed of the linearized system is the same as that for nonlinear system. We then find explicit solutions for the spreading speed of the insect population for the limiting cases where (1) emergence and oviposition are impulsive (i.e., take place over an extremely narrow time window), larval conversion occurs at a constant rate, and larvae are immobile, (2) emergence and oviposition are impulsive (i.e., take place over an extremely narrow time window), larval conversion occurs at a constant rate starting at a delayed time from egg hatch, and larvae are immobile, and (3) emergence, oviposition, and larval conversion are impulsive. To consider other biological scenarios, including cases with emergence and oviposition windows of finite width as well as mobile larvae, we use numerical simulations. Our results provide a framework for understanding how phenology can interact with spatial spread to facilitate (or hinder) species expansion. This is an important area of research within the context of global change, which brings both new invasive species and range shifts for native species, all the while causing perturbations to species phenology that may impact the abilities of native and invasive populations to spread.     

Diversity of Medicinal and Food Plants as Non-timber Forest Products in Naban River Watershed National Nature Reserve (China): Implications for Livelihood Improvement and Biodiversity Conservation

Diversity of Medicinal and Food Plants as Non-timber Forest Products in Naban River Watershed National Nature Reserve (China): Implications for Livelihood Improvement and Biodiversity Conservation. Non-timber forest products (NTFPs) play an important role in rural livelihoods. People living in and around forests are dependent on a variety of NTFPs for their subsistence and for income generation. This paper gives a general overview on the diversity of NTFPs in the Naban River Watershed National Nature Reserve, with a focus on medicinal and food plants. Data on NTFPs use were gathered through an ethnobotanical inventory with semistructured, free-listing, and household socioeconomic interviews. Interviews were supplemented with voucher collections. Bamboo shoots were analyzed further as proxy NTPF. It was hypothesized that there is no significant difference between collection amounts of bamboo shoots and their contribution to the household income between the villages studied. A rapid vulnerability assessment (RVA) was conducted to identify vulnerable and threatened species. A total of 480 plant species (25% of recorded flora) from 117 families and 334 genera are used as NTFPs by the local people. Results revealed that there is a significant difference in the collection and contribution of bamboo shoots to household income among the villages. However, their contribution to per-capita income is very low, and they are mainly used in households. Vulnerability assessment showed that most of the medicinal species have moderate vulnerable status and that most of the food species have less vulnerable status. Some medicinal plants, such as Paris polyphylla var. yunnanensis, are overexploited and getting scarce. Sustainable harvest and management strategies should be implemented to prevent overexploitation of these species.     

Influence of sex on children's body measurements and indices of biological age (findings from a study of twins of different sexes)

By antropometry and roentgenography methods in 52 twin pairs of different sex, body dimensions, the third metacarpal bone and the phalange of the third right hand finger, as well as the terms of permanent teeth eruption were studied. The investigation revealed no timely coincident periods in growth activity between girls and boys. During the first period (6,5--10 years), predominance of some dimentions is observed in boys, during the second (8,5--14 years)--in girls, and during the third (11--17 years)--in boys again. Somewhat different terms for permanent teeth eruption make it possible to distinguish two periods: 7 years when the boys surpass the girls in the number of permanent teeth (two teeth in average) and 8--14 years when the boys lag behind the girls in the number of permanent teeth.     

Canadian Eskimo permanent tooth emergence timing

To identify the times of emergence of the permanent teeth of Canadian Eskimos (Inuit), 368 children and adolescents were examined. The presence or absence of all permanent teeth except the third molars was recorded and these data subjected to probit analysis. Female emergence times were advanced over males. Generally, the Inuit of both sexes showed statistically significant earlier emergence times than Montreal children, except for the incisors. The present results do not support hypotheses indicating that premature extraction of the deciduous teeth advances the emergence of their succedaneous counterparts. There is some indication the controls of deciduous tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.     

Trends in physical stature across socioeconomic groups of Chilean boys, 1880–1997

This paper studies the trends in height-by-age across socioeconomic groups of Chilean boys aged 5–18 born between 1880 and 1997, by performing a meta-analysis of 38 studies reporting height-by-age published since 1898. We estimate the trends using quantile regressions and by analyzing detailed height data from five selected studies. Both methods yield an average decennial increase in height of 1–1.1 cm, and 0.9 and 1.2–1.3 cm for boys of upper and lower socioeconomic status (SES), respectively. SES differences in heights of 9–11 cm are observed up to the late 1940s. However, boys born after the 1930s exhibit substantial convergence in height between socioeconomic groups, driven by an increase in height of middle and lower SES boys of 1.5 and 1.4–2 cm per decade, respectively. As a result, SES differences in height decreased to 5 cm in 1990s. Since these changes occurred in a context of moderate economic growth and persistent income inequality, we argue that our findings are associated with the emergence and expansion of social policies in Chile since the 1940s, which delivered steady improvements in health, nutrition and living conditions.     

Permanent tooth emergence in Gujjars of Punjab, India.

Patterns of permanent tooth emergence in Gujjars were studied in a cross-sectional sample of 483 children ranging in age from 6 to 13 years. Females were markedly advanced in permanent tooth emergence times over males, but no such sex differences were observed in sequence of emergence. Differences between median emergence times of right and left side antimers were significant for only 4 of 28 instances (14.29%), namely central incisors, mandibular first molars in males and lateral maxillary incisors in females. In general mandibular teeth except premolars tended to emerge earlier than their maxillary counterparts. The quiescent period between first and second tooth emergence stages was longer in males than in females. Mandibular depth and morphological facial length were very significantly correlated (p < 0.01) with the number of permanent teeth present in the oral cavity.     

Age and sequence of permanent-tooth emergence among Khasis

The times and emergence of permanent teeth were ascertained by examining 1,263 Khasi children (615 males and 648 females), aged 5 to 15 years. Gingival emergence of the first 28 permanent teeth was recorded and the data were subjected to probit analysis to compute the mean (and standard deviation) emergence time of each individual tooth. Tooth emergence in females was markedly earlier than in males, and canines were most advanced in this respect. Females acquired all their teeth in shorter time span (5.5 years) than males (6.5 years). There were no decisive sex differences in the sequence of tooth emergence. The differences in emergence times between antimeres were statistically nonsignificant. The length of hiatus between two active emergence dental stages was shorter for the maxilla than for the mandible. It occurred between lateral incisor and first premolar in the maxilla of both the sexes, while in case of the mandible, it was spaced between lateral incisor and canine. The Khasis showed early emergence when compared to other populations. The findings support the earlier reports that the controls of deciduous-tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.     

Socioeconomic interactions with physique and fertility

The reproductive histories of 4829 white women who participated in the Ten State Nutrition Survey of 1968-1970 were analyzed in the attempt to study socioeconomic interactions with physique and fertility. Socioeconomic data included per-capita income. The range of per capita incomes in the sample was from $12 per capita for those on public assistance to $30,000 per capita, and distinctly skewed to the lower incomes. Most incomes were clustered between $500 and $5000. Associations between 5 measures of physique and fertility were explained by socioeconomic influences -- the per capita income. The exact relation between social variables and physique, as part of this triangle, did not yield gracefully to delineation. The rich were systematically leanest and for females, at least decreasing socioeconomic status appeared to be associated with increasing fatness. Stature was less predictable, appearing to ascend with social class or income. There was a systematic decrease in number of liveborn children, for mothers of completed reproduction, with increasing income. The lowest 3 income levels were each significantly different from each other and contrasted with all other levels. This socially-determined differential fertility of physique categories appeared to be linear rather than modal in character; income and fertility interacted in a curvilinear manner. The data also suggest the existence of a secular trend for certain physical characteristics, particularly fatness, which are subject to social transmission between generations.     

Age assessment in infant crab-eating monkeys (Macaca fascicularis) based on tooth development

Tooth development was studied in 13 Macaca fascicularis monkeys with known dates of birth. Regular intra-oral examination was carried out and standardized lateral radiographs were collected from 27 until 150 weeks of age under general anaesthesia.
Three stages of tooth development were determined radiographically: onset of crypt formation, onset of mineralization, and crown completion. A fourth stage, the emergence, was determined clinically. Developmental stages were recorded for six mandibular and five maxillary teeth.
The ages of emergence of the permanent teeth and the developmental stages of the third molars showed the largest variation. A significant sex difference with earlier maturation in males was found for the start of crypt formation of the maxillary permanent canines and the maxillary second premolars, and for the start of mineralization of the maxillary permanent canines.
The data provide a tool by which chronological age can be assessed of Macaca fascicularis monkeys between 30 and 80 weeks of age. Owing to an interphase of about one year without significant developmental features in the dentition, age assessment based on tooth development cannot be performed from about 80 to 130 weeks of age. Age assessments are possible for the period between 130 and 150 weeks of age. However, in this period the reliability of the data is lower due to larger time intervals and standard deviations.     

Teeth eruption in children with normal occlusion and malocclusion

The aim of this study was to assess the differences in eruption of permanent teeth (C, P1, P2 and M2) in a group of children with and without malocclusion. A sample of 1758 children (921 boys and 837 girls), aged 8-13 was randomly selected. The subjects were grouped by chronological age (11 groups) and by presence of malocclusion. Statistically significant differences were found for both, upper and lower canines in the age group 11 (p<0.01). Statistically significant difference was found in the age group 8.5 for upper first (p<0.05), upper second premolars (p<0.01) in the age group 10, and the lower second premolars in the age group 11 (p<0.05). Premature loss of deciduous teeth caused early eruption of succedaneus permanent teeth, possibly leading to development of a malocclusion.     

Factors Affecting Regional Per-Capita Carbon Emissions in China Based on an LMDI Factor Decomposition Model

China is considered to be the main carbon producer in the world. The per-capita carbon emissions indicator is an important measure of the regional carbon emissions situation. This study used the LMDI factor decomposition model–panel co-integration test two-step method to analyze the factors that affect per-capita carbon emissions. The main results are as follows. (1) During 1997, Eastern China, Central China, and Western China ranked first, second, and third in the per-capita carbon emissions, while in 2009 the pecking order changed to Eastern China, Western China, and Central China. (2) According to the LMDI decomposition results, the key driver boosting the per-capita carbon emissions in the three economic regions of China between 1997 and 2009 was economic development, and the energy efficiency was much greater than the energy structure after considering their effect on restraining increased per-capita carbon emissions. (3) Based on the decomposition, the factors that affected per-capita carbon emissions in the panel co-integration test showed that Central China had the best energy structure elasticity in its regional per-capita carbon emissions. Thus, Central China was ranked first for energy efficiency elasticity, while Western China was ranked first for economic development elasticity.     

How do cross-migration models arise?

In this paper we present a general method to derive spatio-temporal population models mechanistically. We consider a system of multiple species living in a patchy habitat in which the local population of each species consists of some behavioural groups. We then formulate a continuous-time model where a small positive parameter is present, measuring the time scale of behavioural transitions relative to that of giving birth, death and migration among patches. By the singular perturbation method the model is reduced to a lower dimensional one in which the migration terms are, in general, nonlinear and related to the reaction terms describing the local dynamics. Two examples demonstrating the emergence of cross-migration models, i.e., the models in which the per-capita migration rate of one species depends on the density of some other species, are given.     

Probit and survival analysis of tooth emergence ages in a mixed-longitudinal sample of chimpanzees (Pan troglodytes).

Tooth emergence data from a mixed-longitudinal sample of 58 chimpanzees of known age were analyzed using probit and survival techniques to produce median emergence ages, ranges of variability, and emergence sequences for primary and permanent teeth. Between-group comparisons were made to test for statistically significant differences in emergence ages. No such differences were found between right and left sides, or between maxilla and mandible, for any primary or permanent teeth. Male-female comparisons did demonstrate significant emergence-age differences for some teeth, although they were not always bilaterally symmetrical. More complete data are required to further clarify the nature of sex differences in tooth emergence in chimpanzees. Regression models for age prediction from the number of emerged teeth were generated and indicate that males achieve a given number of emerged teeth at a significantly later age than females. However, when fewer than five teeth have emerged, males are predicted to be younger than females. The sizable root mean square error values for these models suggest that this method of age prediction has limited usefulness owing to the amount of variability in timing of tooth emergence in chimpanzees. The implications of these data for studies on tooth emergence in early hominids are addressed.     

Growth and nutritional status of Khasi boys in Northeast India relating to exogamous marriages and socioeconomic classes

The Khasis are one of the matrilineal tribes of Meghalaya in Northeast India. They belong to the Indo-Mongoloid racial stock, and speak the Monkhmer language of the Austro-Asiatic group. They have their own traditional religion (Niam Khasi), but about 65% of them have converted to Christianity. A few Khasi members have also embraced Islam through matrimonial relationship with immigrant Muslim males. The present study was based on a cross-sectional sample of 1,351 urban Khasi boys aged 3-18 years belonging to these three religious groups, with a view to understanding the effects of socioeconomic factors on growth and nutritional status, using anthropometric variables such as weight and height. The findings showed that about 60%, 29%, and 6% of these boys were below -2 Z-scores of the US National Center for Health Statistics (NCHS) references in respect of weight for age, height for age, and body mass index for age, respectively. The logistic regression coefficient (beta +/- standard error) indicated that the prevalence of low weight for age (below -2 Z-scores of the NCHS references) was positively associated with age (0.088 +/- 0.014, P<0.0001), while it was inversely associated with household income (-1.216 +/- 0.030, P<0.0001). Likewise, low height for age Z-score was negatively associated with household income (-1.056 +/- 0.130, P<0.0001), although such a relationship was not significant in the case of low body mass index for age (-0.169 +/- 0.229, P>0.05). There were also significant differences between religious groups in respect of anthropometric variables. Allowing for household income, the ANCOVA test indicated that Muslim Khasi boys, who were the offspring of intermarriages between Khasi females and immigrant Muslim males, were significantly heavier and taller than Christian and Niam Khasi boys almost across ages. From about 3-10 years of age, Muslim Khasi boys were, on average, comparable to the 5th and 25th percentiles of the NCHS references of height and weight, respectively. Although it looks as though genetic mechanisms like heterosis and/or gene flow might also be associated with the larger body size in Muslim boys, such a conjecture could only be substantiated or refuted by further studies concerning genetic and more socioeconomic data on both immigrant and nonimmigrant populations.     

Serum Alkaline Phosphatase and Rickets in Urban Schoolchildren

Among 569 schoolchildren (386 boys and 183 girls) aged 14-17 years, 233 had serum alkaline phosphatase values of 30 K.A. units or greater. There was no significant difference in the results in Asian, white, or West Indian children. The mean values were significantly greater in boys than girls and both showed a fall in mean values with increasing age. Radiological rickets occurred in at least 4% of the survey, and was more common in Asians. Low calcium and high hydroxyproline excretion in most of those investigated and the response to vitamin D therapy suggests that most children with alkaline phosphatase levels above 30 K.A. units have rickets.Since the decline of the widespread supplementation of the diet with vitamin D, the demands of the physiological growth spurt for extra vitamin D in adolescents already on a borderline intake may be responsible for the great increase in “biochemical” rickets. Once the growth spurt is over the condition subsides but the results of impaired growth or permanent pelvic deformity will not necessarily be eradicated.     

Perfectly nested or significantly nested – an important difference for conservation management

The trade off between age and size at emergence, which plays a central role in life history theory, is hypothesized to be more pronounced under stressful conditions, especially when these conditions are combined. Empirical evidence for this is equivocal. We tested the hypothesis by imposing combinations of two types of time stress (pond drying and late hatching date) in larvae of the damselfly Lestes viridis . Larvae from a temporary pond and a permanent pond population were reared in outdoor tubs from egg hatching until emergence. Unexpectedly, larvae did not accelerate their life history in response to simulation of pond drying. Instead, larvae reared in temporary tubs generally had a slower development and growth than larvae reared in permanent tubs. Probably deteriorating growth conditions in temporary tubs associated with higher densities and lower food levels caused this pattern. In agreement with a higher time stress in late hatched larvae, they generally had faster development and growth than larvae that hatched early in the season. Drying regime and hatching date shaped the covariation pattern between age and size at emergence, but the tradeoff was only apparent when time stress was relaxed. The tradeoff between age and size at emergence was only present in early hatched larvae, especially in permanent tubs (lowest time stress). Conversely, in late hatched larvae there was a strongly negative relationship between age and size at emergence, especially in temporary tubs (highest time stress). Our results support an alternative hypothesis that deteriorating growth conditions (i.e. pond drying) may decouple the tradeoff under time stress. The absence of a tradeoff in more time-stressed late hatched larvae can be explained by their higher intrinsic growth rates, independent of deteriorating growth conditions. We hypothesize that the pattern of less clear tradeoffs under the imposed types of time stress may be general.     

Maxillary volume growth in childhood

Nasomaxillary abnormalities in form, position, and development in children are often prominent features of craniosynostosis, and in particular, craniofacial dysostosis. While attempting to quantitatively assess the volumetric maxillary deficiency in these patients, it became apparent that there was no "normal" reference range for maxillary volumes throughout childhood that could be used for comparison. The aim of this study was to generate a model for measuring maxillary volume and subsequent changes throughout childhood. The technique of segmentation was applied to magnetic resonance images obtained in 55 healthy children (30 boys, 25 girls), aged 1 month to 184 months (15.33 years). Maxillary volumes were plotted against age for boys and girls to create a model for normal maxillary growth during the first 15 years of life. Maxillary volumes were larger in boys at all ages. However, the pattern of maxillary growth in boys and girls was similar and could be divided into three periods, each lasting approximately 5 years. During the first 5 years of life, there is a steady increase in maxillary volume, at the end of which the maxilla has reached 53 percent of the volume recorded at 15 years. There is an accelerated rate of growth between 5 and 11 years, which corresponds to the development and eruption of the permanent dentition. Thereafter, until the age of 15 years, the rate of growth of the maxilla plateaus. Maxillary volume in the first 12 months of life is, on average, 29 cm3 in boys and 25 cm3 in girls. By 15 years of age, it has increased to an average of 73.0 cm3 in boys and 59.4 cm3 in girls (an increase by a factor of 2.5 in boys and 2.4 in girls). The difference between the two sexes is statistically significant for the entire series (boys: mean maxillary volume = 56.55 cm3, SD = 24.61; girls: mean maxillary volume = 40.68, SD = 17.69, p = 0.009, one-way analysis of variance).