利用角形几何特征和计算机视觉技术确定岩羊年龄的新方法

确定野生动物活体年龄是动物种群生态学研究的一项重要基础工作,然而,迄今为止,没有一种传统方法能高效精准地完成这项任务。岩羊角形态复杂且终身生长,其角形随年龄增长和观察角度变化极大。野外条件下,高效获取岩羊个体年龄信息的唯一方法就是拍摄其角的清晰照片。本研究旨在提出一种利用角形几何特征和计算机视觉技术确定野生岩羊活体年龄的新方法,其原理和操作如下:首先建立覆盖全部年龄段(1.5～15.5岁)的已知年龄羊角实体标本的3D模型(左、右角各22个);再在R程序控制下使其在3D空间中旋转,每旋转1°输出一张角形图片;最后计算每张角形输出图片与待定年龄角照片的形状相似性,找出相似性最高的角形图片对应的3D模型,该3D模型的年龄即为待定年龄羊角的实际年龄。30张已知年龄羊角照片的实验验证结果表明,上述年龄鉴定方法能高效地获得精准结果(准确率达100%)。     

Age estimation in rhesus macaques (Macaca mulatta) based on mandibular dimensions

A new technique has been developed for estimating age in rhesus macaques (Macaca mulatta) that is based on mandibular measurements and has several advantages over presently available techniques. First, the new technique is relatively quick and inexpensive because a single measurement or radiograph suffices to produce an age estimate. Second, mandibular growth represents a more continuous phenomenon than either epiphyseal union or dental eruption; therefore, age estimates may be made throughout the period of growth without significant gaps in the process. Finally, the new technique may be used on incomplete or even fragmentary skeletal material because it requires that only a portion of the mandible be preserved. The new technique produces age estimates with a prediction error of ±5.08 months in males and ±7.29 months in females. These errors are only slightly higher than those found previously for dental eruption or epiphyseal union data.     

Analysis of the relation of the frequency of new gene mutations for Mendelian diseases to parental age

The effect of parental age on mutation rates of achondroplasia, neurophibromatosis, hereditary gastrointestinal adenomatosis and Duchenne muscular dystrophy loci was studied. A significant parental age effect on the occurrence of new mutations for achondroplasia and neurophybromatosis was shown. The paternal component of this parental age effect was the major factor in the occurrence of such mutations. The risk of the occurrence of new cases of achondroplasia and neurophybromatosis, as compared with their overall frequency, due to new mutations, are increased by a factor of 2 and 3, respectively, up to the paternal age of 50. The possibility of application of the data obtained in genetic counselling is discussed.     

Spontaneous mutation and parental age in humans.

A statistical analysis of parental age and the incidence of new mutation has been performed. Some new data on Apert, Crouzon, and Pfeiffer syndromes is presented and combined with all available data from the literature on parental age and new mutation. Significant heterogeneity among syndromes for the rate of increase in incidence with parental age was found. A parsimonious conclusion is that mutations fall into two groups, one with a high rate of increase with age and the other with a low rate of increase with age. For the high-rate-of-increase group, a linear model relating incidence to age is rejected, while an exponential model is not. In addition, for this group, increased paternal age cannot account for the observed increase in maternal age--that is, increased maternal age also contributes to the incidence of new mutations. For the low-rate-of-increase group, increased paternal age alone can account for the observed increase in maternal ages; also, either a linear or exponential model is acceptable. In addition, there is no evidence for a mixture of parental age-independent cases with parental age-dependent cases for any of the syndromes examined. The curves reflecting incidence of new mutation and paternal age for two syndromes, Apert and neurofibromatosis, have an anomalous shape. In both cases the curve increases up to age 37 and drops at age 42 before increasing again at age 47. The usual explanation for the effect of parental age on new mutations is the mechanism of "copy-error" at mitotic division in male sperone that specifies an increased probability of mutation with time spent by a spermatozoon or ovum in a haploid state, a period of time that may also increase with age of the parent. A firm answer to the question of parental age and new mutation awaits identification of the molecular defect underlying some of these syndromes; we will then be in a position to determine in which parent the mutation occurred and at what age it did so.     

GenOrigin: A comprehensive protein-coding gene origination database on the evolutionary timescale of life

The origination of new genes contributes to the biological diversity of life. New genes may quickly build their network, exert important functions, and generate novel phenotypes. Dating gene age and inferring the origination mechanisms of new genes, like primate-specific genes, is the basis for the functional study of the genes. However, no comprehensive resource of gene age estimates across species is available. Here, we systematically date the age of 9,102,113 protein-coding genes from 565 species in the Ensembl and Ensembl Genomes databases, including 82 bacteria, 57 protists, 134 fungi, 58 plants, 56 metazoa, and 178 vertebrates, using a protein-family-based pipeline with Wagner parsimony algorithm. We also collect gene age estimate data from other studies and uniformly distribute the gene age estimates to time ranges in a million years for comparison across studies. All the data are cataloged into GenOrigin (http://genorigin.chenzxlab.cn/), a user-friendly new database of gene age estimates, where users can browse gene age estimates by species, age, and gene ontology. In GenOrigin, the information such as gene age estimates, annotation, gene ontology, ortholog, and paralog, as well as detailed gene presence/absence views for gene age inference based on the species tree with evolutionary timescale, is provided to researchers for exploring gene functions.     

Timing of insemination in terms of age of new reproductive females of a temperate-zone polistine wasp,Polistes snelleni (Hymenoptera: Vespidae)

Summary The present study investigated the age at which insemination takes place in Polistes snelleni, a species in which mating begins while new reproductives are still emerging from the nest. Insemination of new reproductive females began as early as 5 days of age, and most females were inseminated by 10 days of age.     

Increasing stereotypy in adult zebra finch song correlates with a declining rate of adult neurogenesis

Adult neurogenesis is often correlated with learning new tasks, suggesting that a function of incorporating new neurons is to permit new memory formation. However, in the zebra finch, neurons are added to the song motor pathway throughout life, long after the initial song motor pattern is acquired by about 3 months of age. To explore this paradox, we examined the relationship between adult song structure and neuron addition using sensitive measures of song acoustic structure. We report that between 4 and 15 months of age there was an increase in the stereotypy of fine-grained spectral and temporal features of syllable acoustic structure. These results indicate that the zebra finch continues to refine motor output, perhaps by practice, over a protracted period beyond the time when song is first learned. Over the same age range, there was a decrease in the addition of new neurons to HVC, a region necessary for song production, but not to Area X or the hippocampus, regions not essential for singing. We propose that age-related changes in the stereotypy of syllable acoustic structure and HVC neuron addition are functionally related.     

New method for estimation of adult skeletal age at death from the morphology of the auricular surface of the ilium

A new method for estimating skeletal age at death from the morphology of the auricular surface of the ilium is presented. It uses a multiple regression analysis with dummy variables, and is based on the examination of 700 modern Japanese skeletal remains with age records. The observer using this method needs only to check for the presence or absence of nine (for a male) or seven (for a female) features on the auricular surface and to select the parameter estimates of each feature, calculated by multiple regression analysis with dummy variables. The observer can obtain an estimated age from the sum of parameter estimates. It is shown that a fine granular texture of the auricular surface is typical of younger individuals, whereas a heavily porous texture is characteristic of older individuals, and that both of these features are very useful for estimating age. Our method is shown here to be more accurate than other methods, especially in the older age ranges. Since the auricular surface allows more expedient observations than other parts of the skeleton, this new method can be expected to improve the overall accuracy of estimating skeletal age at death.     

A NEW SPECIES OF BANDICOOT FROM THE OLIGOCENE OF NORTHERN AUSTRALIA AND IMPLICATIONS OF BANDICOOTS FOR CORRELATING AUSTRALIAN TERTIARY MAMMAL FAUNAS

Abstract:  A new species of primitive bandicoot, Yarala kida sp. nov., is described from Kangaroo Well, a site in the Northern Territory of Australia. This species is possibly ancestral to Yarala burchfieldi , the type species of the Yaraloidea, and supports a late Oligocene age for the Kangaroo Well Local Fauna. The yaraloid bandicoots are likely to become important biochronological tools for Australian faunas of late Oligocene to early Miocene age, as they are widespread and diverse. Developing morphoclines for this group is therefore essential, as is publication of the mostly undescribed bandicoot material known from other sites of similar age.     

A new nonlinear model of age-dependent population growth

A new nonlinear age-structured population model is presented. Within its framework the occurence of time-persistent age distributions is possible, even if the population sizes are nonstationary. The age distribution as well as the moments of the generation index can be determined analytically. The proposed model is a nonlinear generalization of Lotka's theory of stable populations.     

Towards mapping the late Quaternary vegetation change of Europe

The number of well-dated pollen diagrams in Europe has increased considerably over the last 30 years and many of them have been submitted to the European Pollen Database (EPD). This allows for the construction of increasingly precise maps of Holocene vegetation change across the continent. Chronological information in the EPD has been expressed in uncalibrated radiocarbon years, and most chronologies to date are based on this time scale. Here we present new chronologies for most of the datasets stored in the EPD based on calibrated radiocarbon years. Age information associated with pollen diagrams is often derived from the pollen stratigraphy itself or from other sedimentological information. We reviewed these chronological tie points and assigned uncertainties to them. The steps taken to generate the new chronologies are described and the rationale for a new classification system for age uncertainties is introduced. The resulting chronologies are fit for most continental-scale questions. They may not provide the best age model for particular sites, but may be viewed as general purpose chronologies. Taxonomic particularities of the data stored in the EPD are explained. An example is given of how the database can be queried to select samples with appropriate age control as well as the suitable taxonomic level to answer a specific research question.     

Evolutionary consequences of dating the Yixian Formation

The Yixian Formation of northeastern China has yielded important new fossils that are fuelling debates on the origin of angiosperms, on the early radiation of birds and of mammals, and on the origin of feathers. Although these fossils provide a wealth of detailed anatomical information, knowledge of the absolute age of the Yixian Formation is crucial if we are to understand their true evolutionary significance. The age of the Yixian Formation has been disputed, but recent evidence provides strong support for an Early Cretaceous rather than a Late Jurassic age.     

The structure of optimal time- and age-dependent harvesting in the Lotka-McKendrik population model

The paper analyzes optimal harvesting of age-structured populations described by the Lotka-McKendrik model. It is shown that the optimal time- and age-dependent harvesting control involves only one age at natural conditions. This result leads to a new optimization problem with the time-dependent harvesting age as an unknown control. The integral Lotka model is employed to explicitly describe the time-varying age of harvesting. It is proven that in the case of the exponential discounting and infinite horizon the optimal strategy is a stationary solution with a constant harvesting age. A numeric example on optimal forest management illustrates the theoretical findings. Discussion and interpretation of the results are provided.     

A fossil osteoglossoid fish from Tanzania (E. Africa)

A new genus and species ( Singida jacksonoides ) and a new family (Singididae) of osteoglossoid fishes are described from the lacustrine deposits in Tanzania which have already yielded the primitive clupeomorph Palaeodenticeps. Singida differs from all Osteoglossomorpha in being toothless. Although it shows some affinity with the living Asiatic genus Scleropages , it also exhibits certain characters, particularly in the caudal skeleton, which are usually associated with the recent and fossil Hiodontoidei of North America. Singida shows little affinity with either of the living African genera of Osteoglossoidei. The age of the Singida deposits is unknown, but the fish fauna suggests a Palaeogene (? Oligocene) age.     

Advanced paternal age is associated with lower facial attractiveness

In view of disease risk, Kong et al. (2012) demonstrated that most of the new mutations are explained by the age of the father at conception. Accordingly, paternal age effects have been found for a variety of offspring traits, from physical and mental health to intelligence. Here, we investigated whether facial attractiveness is significantly associated with paternal age. We used the Wisconsin Longitudinal Study (n = 4018 male and 4416 female high school graduates) to analyze the association between an individual's father's age at birth and that individual's facial attractiveness (estimated by rating the high school yearbook photographs from 1957), controlling for sex, age as well as mother's age. We find that subject's facial attractiveness decreased with advancing paternal but not maternal age, suggesting that facial attractiveness might be a cue of an individual's new mutation load.     

我国黄羊种群结构及动态趋势的研究

随机抽取1988年12月猎于内蒙古西旗的1026只黄羊,对其种群结构的研究表明:1988年黄羊种群可划分成8个年龄组,当年出生的幼体比重较大,占39.7％;具繁殖能力的雌体数占24.95％;4.5岁以上年龄组个体数占12.7％;是典型的增长型年龄结构。种群全体、2.5、3.5、5.5岁以上年龄组的性比((?)/♀♀)与1:1差异显著(P<0.05),此结果与1979年差异较大。生命表和死亡率曲线表明:种群有3个死亡高峰,分别发生在0.5、3.5和6.5岁以上年龄组。1979年和1988年黄羊种群的净生殖率(R。)分别为1.1335和0.864;1988年雌性开始繁殖的年龄有比1979年提前的趋势。30年来黄羊种群数量明显减少,分布区迅速缩小。由于黄羊的繁殖能力强和增长型的年龄结构,只要加强保护和管理,恢复扩大种群是可能的。     

Health care trends for older people

Research is showing us a radically different view of aging from the one seen by earlier generations. Attitudes, which were based on the myth that physical and mental decline are inevitable with age, are beginning to change as a result of new scientific information. What we are learning is that aging involves both intrinsic and extrinsic factors. The universal phenomena that occur in all of us as we advance in age are intrinsic characteristics of aging, while extrinsic factors are those characteristics that can be prevented or modified, such as lifestyle choices, environmental exposure, and disease.     

Plasticity of hippocampal stem/progenitor cells to enhance neurogenesis in response to kainate-induced injury is lost by middle age

A remarkable up-regulation of neurogenesis through increased proliferation of neural stem/progenitor cells (NSCs) is a well-known plasticity displayed by the young dentate gyrus (DG) following brain injury. To ascertain whether this plasticity is preserved during aging, we quantified DG neurogenesis in the young adult, middle-aged and aged F344 rats after kainic acid induced hippocampal injury. Measurement of new cells that are added to the dentate granule cell layer (GCL) between post-injury days 4 and 15 using 5'-bromodeoxyuridine labeling revealed an increased addition of new cells in the young DG but not in the middle-aged and aged DG. Quantification of newly born neurons using doublecortin immunostaining also demonstrated a similar trend. Furthermore, the extent of ectopic migration of new neurons into the dentate hilus was dramatically increased in the young DG but was unaltered in the middle-aged and aged DG. However, there was no change in neuronal fate-choice decision of newly born cells following injury in all age groups. Similarly, comparable fractions of new cells that are added to the GCL after injury exhibited 5-month survival and expressed the mature neuronal marker NeuN, regardless of age or injury at the time of their birth. Thus, hippocampal injury does not adequately stimulate NSCs in the middle-aged and aged DG, resulting in no changes in neurogenesis after injury. Interestingly, rates of both neuronal fate-choice decision and long-term survival of newly born cells remain stable with injury in all age groups. These results underscore that the ability of the DG to increase neurogenesis after injury is lost as early as middle age.     

Health care trends for older people.

Research is showing us a radically different view of aging from the one seen by earlier generations. Attitudes, which were based on the myth that physical and mental decline are inevitable with age, are beginning to change as a result of new scientific information. What we are learning is that aging involves both intrinsic and extrinsic factors. The universal phenomena that occur in all of us as we advance in age are intrinsic characteristics of aging, while extrinsic factors are those characteristics that can be prevented or modified, such as lifestyle choices, environmental exposure, and disease.