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1.
Distance and velocity curves for height and weight were analyzed in a mixed longitudinal sample of American White, American Negro and Mexican-American deaf children 6 through 17 years of age. The heights of deaf boys and girls are, on the average, consistently below an accepted pediatric standard from six through ten years of age. Between 11 and 17 years, deaf White and Negro boys approximate the standard, while White and Negro girls are at or slightly below the standard. Deaf Mexican-American children are consistently below the height standard. For body weight, deaf boys are at or slightly below the standard from 6 to 11 years, and are at or slightly above the weight standard from 12 to 17 years of age. White and Negro deaf girls generally approximate the weight standard from eight years of age on. Mexican-American deaf girls are consistently below the standard until 13 years of age, while between 14 and 17 years they are at or above the standard. Height and weight velocity curves for deaf children parallel closely the incremental standards of Falkner ('62). The height velocity curve, however, appears to peak, on the average, about one year earlier in deaf children.  相似文献   

2.
气候条件和栽培管理技术直接影响着高梁的干物质积累状况和最终产量。在栽培技术基本相同条件下,干物质的积累主要受气候条件所制约。因此,通过分析不同产量年型下气候  相似文献   

3.
Tryptophan, copper and zinc levels were determined in the hair of 300 healthy subjects divided by sex, age and hair colour. Sex influences tryptophan content in hair, the levels of this amino acid being higher in males than in females. Tryptophan is also higher in infancy (2-5 years) and in both males and females aging around 80 years and over. Hair colour also influences tryptophan levels, which increase from fair to black hair. Copper levels are similar in hair of both males and females, while those of zinc are higher in women. Age influences the distribution of these two metals in human hair. Copper contents in hair of males are higher at the age 20-40 years. In females, values decrease over the age of 60 years. Instead, zinc levels are higher between 20 and 60 years in males, and between 13 and 19 years in females. As regards hair colour, copper is slightly higher in black hair in males and in fair hair in females, and lower in white hair in both sexes. Zinc values appear to be higher in red and lower in white hair in males. In females they are higher in black hair.  相似文献   

4.
RHODOLITHS: BETWEEN ROCKS AND SOFT PLACES   总被引:1,自引:0,他引:1  
Rhodoliths (maërl) are widely distributed in the worlds' oceans and have an excellent fossil record. Individuals are slow growing, may be long lived (>100 years), and are resilient to a variety of environmental disturbances. Their external morphology and internal growth bands are potential archives of environmental variation at scales of within years to tens of years. At high densities, these free-living non-geniculate coralline algae form rhodolith beds, communities of high diversity that can be severely impacted by resource extraction.  相似文献   

5.
The objectives of this paper are to predict life years lost associated with obesity-related diseases (ORDs) for U.S. non-smoking adults, and to examine the relationship between those ORDs and mortality. Data from the National Health Interview Survey, 1997–2000, were used. We employed mixed proportional hazard models to estimate the association between those ORDs and mortality and used simulations to project life years lost associated with the ORDs. We found that obesity-attributable comorbidities are associated with large decreases in life years and increases in mortality rates. The life years lost associated with ORDs is more marked for younger adults than older adults, for blacks than whites, for males than females, and for the more obese than the less obese. Using U.S. non-smoking adults aged 40 to 49 years as an example to illustrate percentage of the life years lost associated with ORDs, we found that the mean life years lost associated with ORDs for U.S. non-smoking black males aged 40 to 49 years with a body mass index above 40 kg/m2 was 5.43 years, which translates to a 7.5% reduction in total life years. White males of the same age range and same degree of obesity lost 5.23 life years on average – a 6.8% reduction in total life years, followed by black females (5.04 years, a 6.5% reduction in life years), and white females (4.7 years, a 5.8% reduction in life years). Overall, ORDs increased chances of dying and lessened life years by 0.2 to 11.7 years depending on gender, race, BMI classification, and age.  相似文献   

6.
Bloom's syndrome: the German experience.   总被引:1,自引:0,他引:1  
Ten patients with Bloom's syndrome observed in Germany during the last 20 years are described. They were born between 1964 and 1986. Seven are alive at the age of 8 to 27 years. Three have died at the age of 5 years (acute leukemia), 18 years (pulmonary fibrosis and bronchiectasis), and 21 years (Hodgkin lymphoma and subsequently leukemia). All show the characteristic clinical and cellular phenotype. In addition to the known early occurrence of malignancies, certain behavioral patterns, the occurrence of hyper- and hypopigmented areas in the skin, pulmonary manifestations, and exquisite sensitivity to chemotherapy and probably also to radiotherapy are emphasized. The potential usefulness of bone marrow preservation for later use in autologous transplantation has not yet been determined. Several features of Bloom's syndrome can be understood on the basis of a genetically determined high rate of somatic recombination.  相似文献   

7.
Several country-specific and global projections of the future obesity prevalence have been conducted. However, these projections are obtained by extrapolating past prevalence of obesity or distributions of body weight. More accurate would be to base estimates on the most recent measures of weight change. Using measures of overweight and obesity incidence from a national, longitudinal study, we estimated the future obesity prevalence in Australian adults. Participants were adults aged ≥25 years in 2000 participating in the Australian Diabetes, Obesity, and Lifestyle (AusDiab) study (baseline 2000, follow-up 2005). In this population, approximately one-fifth of those with normal weight or overweight progressed to a higher weight category within 5 years. Between 2000 and 2025, the adult prevalence of normal weight was estimated to decrease from 40.6 to 28.1% and the prevalence of obesity to increase from 20.5 to 33.9%. By the time, those people aged 25-29 in 2000 reach 60-64 years, 22.1% will be normal weight, and 42.4% will be obese. On average, normal-weight females aged 25-29 years in 2000 will live another 56.2 years: 26.6 years with normal weight, 15.6 years with overweight, and 14.0 years with obesity. Normal-weight males aged 25-29 years in 2000 will live another 51.5 years: 21.6 years with normal weight, 21.1 years with overweight, and 8.8 years with obesity. If the rates of weight gain observed in the first 5 years of this decade are maintained, our findings suggest that normal-weight adults will constitute less than a third of the population by 2025, and the obesity prevalence will have increased by 65%.  相似文献   

8.
Mean annual precipitation accounts for a large proportion of the variation in mean above‐ground net primary production (ANPP) of grasslands worldwide. However, the inter‐annual variation in production in any grassland site is only loosely correlated with precipitation. The longest record of variation in production and precipitation for a site corresponds to a shortgrass steppe in Colorado, USA. A previous study of this record showed that current‐year precipitation accounted for 39% of the inter‐annual variation in ANPP. In this note, we show that ca. one third of the unexplained variation is related to previous‐year ANPP: ANPP per mm of precipitation was higher in years preceded by wet, more productive years than in years preceded by average years; similarly, ANPP per mm of precipitation was lower in years preceded by dry, less productive years than in years preceded by average years. Since previous‐year ANPP was, in turn, associated with precipitation of a year before, current‐year ANPP was also explained by precipitation of two previous years. Our finding not only increases our predictive ability, but it also changes our understanding of how ANPP responds to fluctuations in precipitation. If ANPP is thought to vary according to current‐year precipitation only, it will simply track annual precipitation in time. According to this new result, however, ANPP fluctuations are buffered if wet, more productive years alternate with dry, less productive years, and they are amplified if wet or dry sequences of several years take place.  相似文献   

9.
河北低平原生态条件对棉花产量的影响王有增,陈凤瑞(河北省农科院旱作农业研究所,衡水市053000)EffectsofEcologicalConditionsCottonYieldinHebeiLowPlain.¥WangYouzeng;ChenFen...  相似文献   

10.
Growth of body height and weight and skeletal maturation are discussed, based on 49 male and 61 female Hottentot children aged 3 to 17 years from Warmbad, Namibia (South West Africa) and 124 boys and 113 girls aged 1 to 21 years of related populations, the Rehoboth Basters of Namibia and Cape Coloreds from Cape Town, South Africa. The related populations are taller and heavier than the Hottentots, and have almost the same body height as American blacks and whites at least after the age of 18 years. In the Hottentots and Rehoboth Basters, the mean TW2 skeletal age is always less than the British standard by one or two years in both sexes. In general, the Rehoboth Basters have a skeletal age that is intermediate between Hottentot and British children. In both Hottentots and Rehoboth Basters, the increase in body height shows a linear relation to the skeletal age, and the regression curves are almost parallel in both sexes. The differences in body height and weight between the Hottentots and Rehoboth Basters become greater after the skeletal ages of 15 years for boys and 13 years for girls.  相似文献   

11.
12.
The concepts of longevity (longest lived) and life expectancy (typical age at death) are common demographic parameters that provide insight into a population. Defined as the longest lived individual, longevity is easily calculated but is not representative, as only one individual will live to this extreme. Longevity records for North American Asian elephants (Elephas maximus) and African elephants (Loxodonta africana) have not yet been set, as the oldest individuals (77 and 53 years, respectively) are still alive. One Asian elephant lived to 86 years in the Taipei Zoo. This is comparable to the maximum (though not typical) longevity estimated in wild populations. Calculation of life expectancy, however, must use statistics that are appropriate for the data available, the distribution of the data, and the species' biology. Using a simple arithmetic mean to describe the non‐normally distributed age at death for elephant populations underestimates life expectancy. Use of life‐table analysis to estimate median survivorship or survival analysis to estimate average survivorship are more appropriate for the species' biology and the data available, and provide more accurate estimates. Using a life‐table, the median life expectancy for female Asian elephants (Lx=0.50) is 35.9 years in North America and 41.9 years in Europe. Survival analysis estimates of average life expectancy for Asian elephants are 47.6 years in Europe and 44.8 years in North America. Survival analysis estimates for African elephants are less robust due to less data. Currently the African elephant average life expectancy estimate in North America is 33.0 years, but this is likely to increase with more data, as it has over the past 10 years. Zoo Biol 23:365–373, 2004. © 2004 Wiley‐Liss, Inc.  相似文献   

13.
Stature and weight of 418 men (age range 15 to 57.6 years) of Italian ancestry immigrated in Belgium are studied as a function of age, education, and of profession. Taking account of the variation observed for these factors, the results are analyzed in terms of the geographical origin and of the age at migration. Compared to a reference population, no significant differences are observed between migrants and sedentes: no evidence of selective migration could be demonstrated. Rather, the influences of environmental factors are seen in that the mean heights of Italians born in Belgium and of individuals who migrated before five years of age are significantly higher than the means of the individuals who migrated after five years.  相似文献   

14.
Abstract. The phenology of spring leaf replacement was studied in a population of 46 evergreen scrub oaks (Quercus cornelius‐mulleri) at the edge of the Mojave Desert in each of five years over the period 1990–2001. The oaks occupied a site that spanned rocky slopes to sandy bajadas. The site receives variable annual rainfall (estimated 12‐yr average 195 mm; range in study years 67–706 mm). The spatial coordinates of all individuals were recorded, and in April, when leaf replacement was underway, individual replacement phenologies were assessed. Shrub sizes were recorded in three separate years, and in 2001 water potentials were measured. Individuals vary greatly in their timing of leaf replacement within years, and also between years. Many individuals with an early phenology one year are significantly later in the following year, and vice versa. While we detected weak influences on leaf replacement phenology due to shrub size, position within the site, and a genetic component, stronger influences were attributable to the phenology of the shrub in prior years, and to the phenology of neighbours within years. Neighbouring individuals that are close and/or large are significantly disparate in phenology, with one early and the other late. A potential mechanism of local resource depletion associated with costs to an early phenology is discussed.  相似文献   

15.
用显微镜确定骨龄的初步研究   总被引:8,自引:1,他引:7  
朱芳武 《人类学学报》1983,2(2):142-151
作者对在广西地区收集的年龄从5岁至86岁的35副完整骨骼的右股骨中点横断磨片的骨单位数、骨间板数、非哈弗氏管数及外环骨板平均相对厚度进行了观测和计算。这些指标与年龄之间均存在非常显著的相关,并建立了相应的回归方程。这些回归方程的估计年龄与实际年龄的误差在±5岁以内的,达80%左右;在±10岁以内的,达90%左右。与用Kerley法所作的对比检验表明,本文方法较适用于国人材料。  相似文献   

16.
Over the last few decades, marked land use changes have taken place in many Mediterranean ecosystems. For example, many chestnut groves in France are now abandoned and have turned into 'natural' coppice stands while others are now clear-cut every 10 or 15 years for wood. Species composition and life form diversity of the plant communities have changed markedly both in the abandoned groves and in the periodically clear-cut coppice stands. What are the consequences of these changes on biodiversity at local and regional scales, and what are the implications for 'new forestry' management intended to conserve biodiversity at the same time as it optimizes productivity and profitability? To answer these questions we studied plant species diversity in the understorey strata along a successional gradient including cultivated grove; abandoned grove; young (15 years old), medium (40 years), and old (>55 years) coppice stands. The results showed that species richness decreased quickly but not steadily along this gradient, but life-form spectra data highlighted that the high levels of plant species biodiversity in cultivated groves were due primarily to the large number of therophytes (annual plants). At a shorter time scale, we also studied the consequences of experimental clear-cutting on plant species biodiversity. Direct measurements over four years showed that species richness and diversity in the understorey increased in the first two years after clear-cutting, but decreased during the 3rd and 4th years. This decrease corresponded closely with a steady increase in Leaf Area Index of the forest canopy. These results have been used to suggest some possible ways to manage the biodiversity in these ecosystems.  相似文献   

17.
The ocean quahog Arctica islandica is the longest-lived of all bivalve and molluscan species on earth. Animals close to 400 years are common and reported maximum live span around Iceland is close to 400 years. High and stable antioxidant capacities are a possible strategy to slow senescence and extend lifespan and this study has investigated several antioxidant parameters and a mitochondrial marker enzyme in a lifetime range spanning from 4-200 years in the Iceland quahog. In gill and mantle tissues of 4-192 year old A. islandica, catalase, citrate synthase activity and glutathione concentration declined rapidly within the first 25 years, covering the transitional phase of rapid somatic growth and sexual maturation to the outgrown mature stages (approximately 32 years). Thereafter all three parameters kept rather stable levels for > 150 years. In contrast, superoxide dismutase activities maintained high levels throughout life time. These findings support the 'Free Radical-Rate of Living theory', antioxidant capacities of A. islandica are extraordinarily high and thus may explain the species long life span.  相似文献   

18.
In data from the Sri Lanka Fertility Survey, 1975, the cessation of childbearing is examined among women who have never used contraception. The sample consisted of 6810 currently or previously married women, 57% of whom reported that they had never used contraception. Cessation of childbearing is studied according to age and marriage duration. The variables analyzed are age at last birth, proportions infertile during the last 5 or 7 years, and the infertile open interval. The duration of breastfeeding is taken into account where necessary, and the contraceptive users and nonusers are compared where appropriate. Non-users tend to cease childbearing early, and therefore are infertile for longer periods during their marriages. It is probably age of the 1st child that influences decisions on future fertility. Among women aged 45-49 who married before age 20 and continued in their 1st marriage, mean age at last live birth in non-users, was 34.5 years, about 2 years earlier than in those who had used contraception. Non-users who married at any age below 30 years cease childbearing well below age 40. The proportion not currently pregnant and infertile over the past 5 years increases with marriage duration among the fertile non-users in each age group. When age at last birth and the duration of breastfeeding in the open interval are taken into account and the reference period is increased to 7 years, the period of infertility increases with marriage duration among nonpregnant non-users below age 45. The proportion of women who were currently not pregnant and had remained infertile over the past 7 years is higher among the older non-users whose 1st child was born more than 10 years ago.  相似文献   

19.
Silver products have been used for thousands of years for their beneficial effects, often for hygiene and in more recent years as antimicrobials on wounds from burns, trauma, and diabetic ulcers. Silver sulfadiazine creams (Silvazine and Flamazine) are topical ointments that are marketed globally. In recent years, a range of wound dressings with slow-release Ag compounds have been introduced, including Acticoat, Actisorb Silver, Silverlon, and others. While these are generally accepted as useful for control of bacterial infections (and also against fungi and viruses), key issues remain, including importantly the relative efficacy of different silver products for wound and burn uses and the existence of microbes that are resistant to Ag+. These are beneficial products needing further study, although each has drawbacks. The genes (and proteins) involved in bacterial resistance to Ag have been defined and studied in recent years.  相似文献   

20.
The ocean quahog Arctica islandica is the longest-lived of all bivalve and molluscan species on earth. Animals close to 400 years are common and reported maximum live span around Iceland is close to 400 years. High and stable antioxidant capacities are a possible strategy to slow senescence and extend lifespan and this study has investigated several antioxidant parameters and a mitochondrial marker enzyme in a lifetime range spanning from 4–200 years in the Iceland quahog. In gill and mantle tissues of 4–192 year old A. islandica, catalase, citrate synthase activity and glutathione concentration declined rapidly within the first 25 years, covering the transitional phase of rapid somatic growth and sexual maturation to the outgrown mature stages (~32 years). Thereafter all three parameters kept rather stable levels for > 150 years. In contrast, superoxide dismutase activities maintained high levels throughout life time. These findings support the ‘Free Radical-Rate of Living theory’, antioxidant capacities of A.islandica are extraordinarily high and thus may explain the species long life span.  相似文献   

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