Development of biomass proportions in Norway spruce (Picea abies [L.] Karst.)

This study tests the hypotheses that (1) the above-ground structure of Norway spruce (Picea abies [L] Karst.) is derivable from the functional balance theory, and that (2) crown ratio is a key source of structural variation in trees of different age and social position. Twenty-nine trees were measured in three stands (young, middle-aged, and mature), with three thinning treatments (unthinned, normal, and intensive) in the two older stands. There was a strong linear relationship between the total cross-sectional area of branches and that of stem at crown base. Foliage mass was linearly related with stem basal area at crown base. Also an allometric relationship was found between foliage mass and crown length. The mean length (weighted by basal area) of branches obeyed an exponential function of crown length. The parameters of most of these relationships were independent of slenderness (tree height/breast height diameter) and tree age However, total branch cross-sectional area per stem cross-sectional area in the young trees was greater than in the older trees. The young trees also had slightly shorter branches than predicted by the mean branch length equation. This was probably caused by branch senescence which had not yet started in the young stand. The older trees had a relatively long lower crown segment which was growing slowly and senescing. It was proposed that a segmented crown structure is characteristic of shade tolerant tree species, and that the structural model could be further developed by making the two segments explicit.     

Rate of growth in length of Bangladeshi infants as a function of attained length.

We examine variation in the rate of growth in length of breast-feeding infants from rural Bangladesh. These data were collected between November 1985 and February 1986 from two rural sites. Eighty-eight infants, ranging from birth to 4 months of age at the start of the study and their mothers were measured monthly for 4 months. Length increased linearly with age over this 4-month period (infants' average bias-adjusted R2 = 0.90). The relationship between infant rate of growth in length and attained length was analyzed by two different methods: Oldham's (1962) method of regressing rate of growth on mean length and Blomqvist's (1977) method of regressing rate of growth on estimated initial length. The methods gave similar results. The rate of growth was negatively associated with mean infant length over the 4-month period (p less than 0.001); that is, shorter infants grew at a faster rate than longer infants. For every centimeter shorter the infant was, the rate of growth was 0.1 cm/mo faster on average; the effect was greater among males than among females. The average rate of growth was greater for males than for females and greater in financially solvent households and varied by site. Infant growth rate was slower among older infants than among younger infants, as expected. However, after adjusting for mean infant length, age was no longer significantly associated with infant growth rate, although mean infant length remained highly significant. Forty-one percent of the variation in infant rate of growth in length was explained by mean infant length, sex, sex by length interaction, household financial solvency, and site.     

The rate of early fetal growth in the human subject

Data from 354 embryos and fetuses between 20 and 200 mm crown rump length obtained by therapeutic abortion in 3 different countries were evaluated. All Danich and Hungarian and the majority of American specimens were measured immeditely after delivery in the fresh condition. In the mathematical evaluation linear regressions were calculated by the method of least squares for arbitrarily defined ranges to 20-50 mm and 50-200 mm crown rump lenghts. The material was analyzed statistically so that confidence limits could be drawn for the estimation of gestational age from crown rump length measurements. All data in the 20-50 mm range were combined, but beyond that fetal length the statistics for the Hungarian group were calculated separatley. The equation calculated to fit the data in the 20-50 mm rage is A = 46 + 0.71 L where A is gestational age in days and L is crown rump lenght in mm. The 95% confidence limits of regression are 0.57-0.83 days/mm and the correlation between gestational age and crown rump length is 0.65. Estimates of gestational age from sitting height measurements can be made + or - 15 days with 95% confidence. The equation for the combined Danish and American data in the range 50-200 mm is A = 64 + 0.41 L. The 95% confidence limits for the regression are 0.36-0.46 days mm and the correlation between gestational age and crown rump length is 0.70. Estimates of gestational age from crown rump length can be made + or - 26 days with 95% confidence. The data from the Hungarian study in the 50-200 mm sitting height range differ from those of the combined Danish and American material. The regression of days/mm (0.22) was significantly less at p. 01 level supporting the suspected bias in the Hungarian material, but the correlation between gestational age and crown rump length, 0.62, was not significantly less than that of the combined Danish and American data. Thus, if the difference in the slope was due to a bias, the bias was relatively consistent from patient to patient. Comparison of the results with those of Streeter (1920, 1951) indicates that the considerable discrepancy at the embryonic stages diminishes gradually in the fetal period and eventually becomes quite insignificant.     

北京地区侧柏人工林密度效应

密度是影响森林尤其是人工林生长的重要因素,林冠层是森林生态系统与其他系统进行能量和物质交换的重要场所,树木及树冠生长对林分密度的响应关系可以看作是生物对环境变化产生的适应性现象。林分密度效应是生态学和森林培育学的重要研究内容之一。以23块8种不同密度梯度的北京山区侧柏人工幼龄林林分为研究对象分析其树木生长及树冠生长对密度的响应关系,其中树冠指标使用了参照了美国林务局(USDA)的树冠调查指标。研究结果表明:(1)林分平均胸径、平均树高和平均冠幅生长均随密度增大而减小,林分密度大于3000株/hm2时各指标减小的趋势变缓,使用异速生长模型可以很好地拟合这种变化关系;(2)随密度增加,树冠水平方向和垂直方向生长均到显著地抑制作用,树冠外形表现出由饱满冠型向狭长冠型变化的适应性现象;(3)使用树冠二维、三维指标与密度进行相关性分析可知树冠长度、树冠率等指标与林分密度呈负相关关系,树冠圆满度及树冠生产效率与密度表现出极显著正相关关系;(4)采用枝解析的方法研究了树枝长度、材积的平均生长量、连年生长量与密度的关系,结果表明幼龄期各生长量差异不大;(5)在建立冠幅模型时考虑了自变量间的多重共线性问题,所建的胸径单自变量二次方模型能够很好地预测侧柏人工幼龄林冠幅生长过程,模型相关系数R2为0.961。     

Altitude and infant growth in Bolivia: A longitudinal study

The growth of 79 healthy, well-nourished lowland (400 M) and highland (3600 M) Bolivian infants was analyzed in a longitudinal study through the first postnatal year. Compared to low altitude infants, the high altitude infants were found, by analysis of covariance controlling for size at the previous exam, to be significantly shorter at birth, 1 and 6 months, while they were significantly lighter only at birth and 1 year. Recumbent length gain was slower in the high altitude infants in the early months of life, while weight gain did not differ between altitudes. The observed lower weights at high altitude throughout the first year appear to be due to a persistence of lower weights seen at birth and not to postnatal growth retardation. Significantly greater triceps and subscapular skin-fold thickness measurements were found in the highland group, despite their smaller length and weight. The possible causes and implications of the greater fat accumulation in the highland infants are discussed.     

Changes of the corpus callosum in children who suffered perinatal injury of the periventricular crossroads of pathways

There is a high incidence of periventricular leukomalacia, caused by hypoxia-ischemia, in preterm infants. These lesions damage the periventricular crossroads of commissural, projection and associative pathways, which are in a close topographical relationship with the lateral ventricles. We explored to what extent abnormalities of echogenicity of the periventricular crossroads correlate with changes in size of the corpus callosum. Our study included nine infants (gestation from 26-41 weeks; birth weight between 938-4450 grams) with perinatal brain injury. Periventricular areas, which topographically correspond to the frontal, main and occipital crossroad, were readily visualized by cranial ultrasound scans, performed during the first two weeks after birth. Corpus callosum mediosagittal area measurements were performed using magnetic resonance images, acquired between the first and sixth postnatal month (postmenstrual age 40-49 weeks). We found a statistically significant correlation between the increased echogenicity in the crossroad areas and the decrease of the corpus callosum midsagittal area (p < 0.05). This supports the hypothesis that callosal fibers can be damaged, during growth through the periventricular crossroads of pathways.     

Models relating stem growth to crown length dynamics: application to loblolly pine and Norway spruce

We derive and analyze a model that relates the growth rate of cross-sectional area (‘csa’) at any height on the central stem of a tree to crown-length dynamics. The derivation is based, in part, on assumptions that (a) active csa on the central stem relates allometrically to the length of crown above the cross section, and (b) inactive csa is proportional to active csa within the crown. We also assume that the deactivation rate of csa beneath the crown is determined, in part, by the rate of crown rise. Integration of the growth-rate model under an additional assumption—that total crown length is constant after stand closure—provides a simple model of annual or periodic growth of total csa that can be fit to standard growth data. Three implications of the assumptions and integration are notable: (1) total csa within the crown scales allometrically with stem length above the cross section; (2) for a special case, total csa beneath the crown scales with stem length above the cross section; more generally, csa scales with a linear combination of the stem and crown lengths; and (3) the stem beneath the crown forms to approximate a frustum of a quadratic paraboloid. Basal area data from a loblolly pine (Pinus taeda L.) spacing trial show good agreement with (1) and (2), and with an empirical model developed from the special case of (2). Data from the plots of a Norway spruce (Picea abies (L.) Karst.) thinning trial, where crown length remained approximately constant, show good agreement with (2) and the empirical model. Prediction (3) is demonstrated by simulation.     

Crown alterations induced by decline: a study of relationships between growth rate and crown morphology in beech (Fagus sylvatica L.)

One of the first symptoms expressed by declining trees is reduced growth in stem diameter and length increment. The possibility of a relationship between length increment and crown thinning in beech (Fagus sylvatica L.) was investigated by developing a computer model to simulate first order branching patterns of the apical 2 m of monopodially branching beech trees, 70–100 years old, for a range of length increment rates. The model was based on values for branching angle, main axis and branch length increment, number of branches produced per year and branch mortality rates for six healthy and declining trees. Shoot growth rates in the apical 2 m of the sample trees ranged from about 5 cm/year (decline class 3) to 43 cm/ year (healthy). Simulations of branching patterns in the apical 2 m of trees growing at different rates indicated that, when growth rate exceeded about 20 cm/year, total first order branch length and area explored were independent of growth rate. When growth rates fell below this value there was a reduction in total area explored and first order branch length due primarily to the formation of fewer branches. More acute branching angles contributed to a reduction in the area explored. Growth rate-related crown thinning could increase the risk of bark necrosis and secondary pathogen infection during dry and/or hot spells.     

Responses of crown architecture in Betula pendula to competition are dependent on the species of neighbouring trees

We measured the growth responses of individual shoots and branches of Betula pendula when growing next to trees of the same species or Pinus sylvestris, Larix sibirica or Alnus glutinosa. We used the three-dimensionally digitized response variables and the size and distance of trees growing within a 5-m radius of the study trees to establish a relationship between tree performance and the effect of competing neighbouring tree species on crown architecture. B. pendula was able to modify its crown architecture and thus alter its strategy to compete with different neighbours. Trees of B. pendula growing beside species counterparts had the highest growth of new long shoots in relation to the already existing branch length [growth vigour (GV)], while GV was the lowest next to L. sibirica. With B. pendula or P. sylvestris as its main neighbour, B. pendula invested in short shoots by growing them rather densely in short branches with limited numbers, whereas with L. sibirica the number, length and angle of the branches were high. The competitive response was also strongly dependent on tree ontogeny and the shoot and branch characteristics were significantly affected by their location inside the crown. B. pendula was able to respond to the challenges posed by its neighbours, which was also reflected in the GV. The ability to maintain steady growth with alternative crown designs in different neighbourhoods reflects plasticity in the crown responses.     

Longitudinal analysis of length growth in the chimpanzee (Pan troglodytes)

The adolescent growth spurt in linear dimension in humans is considered to be unique among mammals, but few comparative studies have been done, even on chimpanzees. Growth of the summed length of crown to rump, thigh, and leg was studied longitudinally in 12 chimpanzees. We took body weight growth and reproductive maturation into consideration. Reproductive maturation was monitored by the swelling of sexual skin and menarche in females, and by testicular development in males. We applied two relationships found in humans between body length growth and the environment to the chimpanzees. The first relationship was the robustness of the growth spurt, meaning that the spurt is absent only in individuals under the most severe environmental pressure. Subjects maturing in a favorable or even mediocre environment are anticipated to show the growth spurt. The second relationship was catch-up growth, where, when the environment is ameliorated, growth may be accelerated to attain the target size. Catch-up growth at the end of the juvenile period may mimic the adolescent growth spurt. Results showed that subjects living under favorable conditions did not exhibit a growth spurt, and that it was only the subjects who had delayed growth in the juvenile period that showed a spurt in adolescence, the period when reproductive maturation occurred. Although we have concluded that chimpanzees do not have an adolescent growth spurt, except in cases of catch-up growth, this does not mean that they have a different growth pattern from that of humans. The absence of a growth spurt may be associated with adaptations to chimpanzee patrilineal society, where adolescent males are incorporated into the adult hierarchy at a low rank.     

Relationship of enamel hypoplasia to the pattern of tooth crown growth: A discussion

The defects of enamel hypoplasia can be related to the layered structure of enamel which represents the sequence of development in tooth crowns. From such studies, it is possible to see that furrow-type enamel defects (the most common form of hypoplasia seen with the naked eye) are just the most prominent expression of a continuum which extends ever smaller, down to a microscopic disturbance to a single layer in the crown formation sequence. Furthermore, the progressive decrease in spacing between development layers which occurs down the crown sides, from occlusal to cervical, affects both the prominence and apparent width of the defects. This makes it difficult to use measurements as a means of estimating the duration of the disturbance causing a particular defect. The difficulty is even greater for the less common pitted or exposed-plane-type defects, for which the apparent width bears very little relationship with the duration of the growth disturbance. The defects of enamel hypoplasia can therefore be understood clearly only when examined under the microscope in relation to the structures which mark the development sequence of the tooth crown. Am J Phys Anthropol 104:89–103, 1997. © 1997 Wiley-Liss, Inc.     

Crown development in Norway spruce [<Emphasis Type="Italic"> Picea abies </Emphasis>(L.) Karst.]

This study tests whether crown and stem development in Norway spruce could be described using a modified profile theory. 29 trees from three age-groups (25, 67, 86) with different treatments (unthinned, normally and intensively thinned) were destructively sampled. Crown ratio and crown length varied between age groups and treatments. Crown width was positively correlated with crown length, but branch length along the crown depended on tree age and growing space. Foliage mass density peaked at a relative crown height of 50–70% in middle-aged and mature stands, while young crowns were densest and widest at the base. Foliage mass was predictable from branch and stem cross-sectional area, provided the distance from the top was included. The ratio of foliage mass to branch cross-sectional area increased for 2–4 m down from the tip of the crown, then started to decrease. The relationship between cumulative foliage mass and stem cross-sectional area was non-linear along the stem in the upper crown, but the ratio of cumulative branch to stem cross-sectional area was linear. Trees in the mature and unthinned stands had more cross-sectional area in branches relative to stems than in the young and thinned stands. We conclude that the profile theory needs modification regarding (1) crown shape which varies with age and growing space, and (2) the ratio of foliage mass to branch area which varies along the stem. Both aspects emphasise the need to include impacts of disuse of sapwood pipes in models of crown and stem development.     

Alternative dental measurements: proposals and relationships with other measurements

Most archaeological and fossil teeth are heavily worn, and this greatly limits the usefulness of tooth crown diameter measurements, as they are usually defined at the widest points of the crown. There are alternatives, particularly measurements at the cervix of the tooth, where the crown joints the root, and measurements along a diagonal axis in molars, that are much less affected by wear. These would allow a wider range of specimens to be included, e.g., in the study of dental reduction in Upper Palaeolithic and Mesolithic Homo sapiens. In addition, they would allow the little-worn teeth of children to be compared directly with well-worn teeth in adults. These alternatives, however, have been little used, and as yet there have not been any studies of the repeatability with which they can be measured, or of the extent to which they are related to the more usual crown diameters. The present study is based on a group of unworn teeth, where direct comparisons could be made between the alternative measurements, which are not much affected by wear, with the usual crown diameters, which are very much affected. In an interobserver-error study of this material, cervical and diagonal measurements could be recorded as reliably as the usual crown diameters. The buccolingual cervical measurement was strongly correlated with the normal bucclingual crown diameter in all teeth, whereas the mesiodistal cervical measurement was highly correlated with the normal mesiodistal crown diameter in incisors and canines, but less so in premolars and molars. The molar diagonal measurements showed high correlations with all other measurements. Crown areas (robustness index) calculated from the usual diameters were strongly correlated with crown areas calculated from cervical measurements, and crown areas calculated from molar diagonals were strongly correlated with both other areas. Despite the long usage of the more usual maximum crown diameters, the alternative dental measurements could be measured just as reliably, could record similar information about tooth crown size, and would be better measures for the worn dentitions seen in archaeological and fossil material.     

Early diagnosis and early treatment of growth hormone deficiency

In the past, growth hormone (GH) deficiency has usually been diagnosed too late in dwarfed children, so that substitution therapy was not able to obtain a final height in the normal range for most of them. Complete catch-up of growth in hypopituitary patients needs early diagnosis and early treatment. This requires: (1) that full attention be paid to any insufficiency of length or height increment in infants and young children; (2) that evaluation of GH secretion be performed in spite of the practical difficulties encountered in small patients, and (3) that the interpretation of hormonal measurements be carefully discussed. Though the overall results obtained to date in treating very young GH-deficient children have not been completely satisfactory, it is certain that those whose height was within or near the limits of -2 SD at the onset of treatment maintained a normal height. The relationship of end results with the doses of GH used remains to be investigated. Future results will probably be improved more by earlier diagnosis and by using daily injections than by an increase in the annual dose of GH.     

沙质海岸灌化黑松对蛀食胁迫的补偿性响应

黑松(Pinus thunbergii)在特定的沙质海岸环境中形成了与之相适应的灌化树形。由蛀食胁迫诱发的黑松补偿性响应是其自我保护和适应不良环境的一种重要机制,目前尚缺乏相关研究。该文通过比较蛀食前后植株补偿性生长特征的变化来阐明补偿性响应的机理及其在灌化过程中的作用。结果表明：(1) 蛀食胁迫后,当年和次年枝的数量明显增加,且对当年枝的影响大于次年枝,可见这种补偿响应具有持续性,但强度有减弱的趋势。同样,叶构件的补偿响应也具有持续性但强度差别不显著。(2) 当年枝和叶构件的补偿性生长与其在1年枝上的位置密切相关,蛀食后近顶端枝和叶长度分别为未蛀枝上同部位的1.75与1.43倍,而近底端补偿性生长不明显。(3) 在密度效应的影响下,蛀食枝的芽死亡率上升5.4倍,营养芽产量上升1.55倍,而生殖芽产量差异不显著,因此蛀食胁迫诱发的补偿性响应更倾向于投资营养生长。(4) 主枝遭蛀食胁迫停止生长后,分枝数增多,枝计盒维数增加25%。树冠计盒维数随枝条受害率的增加呈现“先增后减”的变化趋势。通过非线性回归分析表明,两者呈“后峰型”曲线函数关系。(5) 枝和叶构件的总生物量在两条件下差异不显著,属等量补偿性生长。本研究认为：灌化黑松响应蛀食胁迫的补偿性生长机理可用顶端优势去除理论解释,且具有持续效应,这种枝构型改变方式将最终导致黑松灌化形态的形成;同时,补偿性响应还包括芽命运和计盒维数的变化。因此,可将芽命运和计盒维数作为反映植物补偿性生长的指标。     

Measurement and the newborn infant

Measurement of newborn babies is widely regarded as being too inaccurate to justify its regular practice. It is common for infants to be weighed at birth and for no other measurements to be made. Although such assumptions are superficially correct, it is possible to train people to perform accurate measurements and for improved performance to be sustained. Accurate sequential measurements are possible and provide more information than single measurements. Detailed measurements show that postnatal growth may change rapidly and dramatically, particularly in preterm infants. Postnatal growth impairment is common in such infants and may be sustained. Limited evidence suggests that there may be a significant reduction in final stature. Preliminary data also suggest that many preterm infants may also show evidence of alterations in biochemical and physiological variables consistent with early programming and the potential for altered disease susceptibility in adult life.     

Prenatal ionizing irradiaton and early postnatal growth of Colombian and Bolivian squirrel monkeys (Saimiri sciureus)

Fetal squirrel monkeys of Bolivian and Colombian origin were exposed to 100 rad cobalt-60 radiation in utero and carried to term by the dams. Body weight, head circumference, crown–rump length, and food intake were measured during the first 28 postnatal days. Significant subspecies differences were noted in both mothers and offspring, the Colombian squirrel monkeys being generally larger than the Bolivians. The irradiated offspring weighed significantly less, had significantly smaller crania, and consumed significantly less food than control animals. A statistically nonsignificant decrement was also evident in the crown–rump length of radiation-treated infants.     

现代华南人恒齿测量和齿尖形态观察研究

作者测量和观察了现代华南人1963个恒牙。结果表明,铲形上内侧门齿的出现率为91.8％;卡氏尖在M1中的出现率为23.8％,在M2中的出现率为1.6％。     

Determinants of intrauterine growth retardation: evidence against maternal depletion

This analysis examines the relationship between length of preceding birth interval and risk of intrauterine growth retardation using data on Swedish infants from the 1973 World Health Organization study of perinatal mortality. Results of a multivariate logit analysis demonstrate that the lower than average mean birth weight of infants born after short birth intervals cannot be completely attributed to their shorter mean gestation length. Infants born after birth intervals of 12 months or less are 30% more likely to be small for gestational age (SGA) than infants born 18-59 months after the previous birth, even when the effects of maternal age and parity are controlled. The results obtained here do not support maternal depletion as an explanation for the association between short birth intervals and elevated risk of SGA, since there is no evidence of an attenuation of the risk of SGA with increasing length of interval in the under 18 month birth interval range.