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11.
Abstract

In this article, the author constructs new life tables for the white population of the United States in each decade between 1790 and 1900. Drawing from several recent studies, he suggests best estimates of life expectancy at age 20 for each decade. These estimates are fitted to new standards derived from the 1900–1902 rural and 1900–1902 overall death registration area life tables using a two-parameter logit model with fixed slope. The resulting decennial life tables more accurately represent sex- and age-specific mortality rates while capturing known mortality trends.  相似文献   
12.
As population ageing accelerates in China, the number of elderly widowed individuals are expected to increase. Using 2010 census data we estimate widowhood indices for rural and urban areas, and for men and women in China. The indices show that the probability of elderly widowhood to be higher for females (0.68) than males (0.32)—with no rural and urban difference. An average marriage in China lasts about 47 years. After the death of a spouse, the average duration of widowhood is about 11 years for males and about 15 years for females. Spousal age difference has a significant impact on widowhood indices. Rural populations have the shortest marriage duration and the youngest widowhood age, and longer widowhood duration.  相似文献   
13.
Several errors in the early literature discussing life-table analysis of skeletal populations are potentially misleading to the researcher unacquainted with the mathematical methods of palaeodemography. Additional errors document the hazards of borrowing life-table methods and equations from other applications without fully realizing their context, interpretation, and the potential restrictions on their use. A simple generalization of the life-table equations explicitly to reveal their dependence on the entry age and width of the age intervals used will facilitate the correct computation of life tables and readily accommodate the use of unconventional or otherwise non-standard cohorts. A general procedure for computing a life table for a skeletal population is presented, and a numerical example is included to illustrate the method.  相似文献   
14.
《四库全书总目》作为一部目录学巨著,本身具有学术史的性质;与此同时,《总目》也在总序、小序和提要中渗透了编撰者的学术思想。《总目》所收录的清初《左传》研究著作,就是一部清初百余年间的《左传》研究史;而且,《总目》有关(《左传》研究的学术思想,如重视考据,复古倾向,尊经思想等,对清代中后期的《左传》研究产生了深远的影响。  相似文献   
15.
For decades zooarchaeological studies mainly focused on teeth age profiles to derive central hypotheses concerning human subsistence during the Pleistocene. Behavior was often related to hunting and/or scavenging strategies according to two models: attritional versus catastrophic. However, few studies have estimated basic demographic parameters using standard methods of population ecology, which are necessary for a more confident interpretation of animal paleopopulation structures. Thanks to a remarkably rich fossil bone assemblage from the Upper Pleistocene cave of Geula (Mount Carmel, Israel), in this paper we perform a paleodemographic analysis of Hystrix refossa, Gervais 1852 (Mammalia, Rodentia). We first consider phylogenetic and morphometric dental criteria for the comparison of Pleistocene porcupine species, followed by an examination of taphonomic conditions of the bone assemblage. We focus strongly on the age structure of the fossil population, presenting a new methodological approach that combines life tables and Leslie matrix models – one of the best-known methods in population ecology for assessing population growth and age distribution. We detail demographic parameters derived from cross-sectional life tables and past trends in the porcupine population at Geula Cave using simple matrix projection model. Finally, we were able to perform an elasticity analysis to identify which demographic component was potentially the most critical for influencing growth. We show that the population of H. refossa did not decline or shrink but was stable. Our results permit us to characterize Geula Cave as a natural shelter for porcupines, with limited evidence to scavenging and hunting by either hyenas or humans.  相似文献   
16.
Abstract

The male/female sex ratio (SR) and its age-specific patterns vary considerably across time and place. The SR generally begins male-biased at birth and becomes female-biased later in life, but this relationship should respond to historical trends and events. Temporal trends in SRs remain largely unstudied and formal demographic relationships are not well defined. We (1) define SRs in a life table framework, (2) estimate the age at which the number of males and females achieves parity—the sex ratio crossover (SRX)—using basic life table methods, and (3) explore historical and international patterns in these trends. Using publicly-available data from the Human Mortality Database, we construct SR and SRX measures from period and cohort life tables. Analyses explore temporal patterns for seven countries in different global regions since 1850. Overall temporal trends show the SRX advancing to older ages. The SRX also appears to respond to historical events such as wars and epidemics. The measure is simple to construct from life table data, and provides additional insight into the historical context of gender dynamics.  相似文献   
17.
Substantial databases of elemental and isotopic analyses of ancient glass exist and are used to investigate raw material origin, trade, exchange, and processes such as mixing and recycling. However, the chemistry of archaeological glass may be challenging to the untrained. The paper provides structured information on the origin of chemical elements and their isotopes in ancient glass. It details some of the functions of individual elements in the glass and from which raw material(s) or process(es) they originate.  相似文献   
18.
Timber-framed wall buildings are seen all over Europe, especially in seismic regions, given its adequacy to resist earthquakes. The “Pombalino” buildings, developed after the great 1755 earthquake that destroyed Lisbon, constitute one of the best examples of historic seismic-resistant structures based on timber-framed masonry walls. The research presented in this article aimed at experimentally evaluating the seismic behavior of the “Pombalino” buildings. The experimental program was based on extensive dynamic testing on sub-structures of typical “Frontal” walls (the timber masonry walls), carried out at the LNEC (the Portuguese National Laboratory of Civil Engineering) shaking table. The tests comprised (a) seismic tests, in which the seismic action was applied with increasing amplitude in one direction; and (b) dynamic identification tests, aiming at evaluating the dynamic properties of the sub-structures and their evolution with damage accumulation.  相似文献   
19.
A device prototype, based on the superelastic properties of Shape Memory Alloys (SMAs), is proposed to enhance the thermal and seismic behavior of steel tie-rods. First, the thermal behavior of steel tie-rods with and without SMAs is presented based on the results of extensive experimental tests in thermal room. Next, the seismic performances of the proposed SMA system are discussed based on the results of a series of shaking table tests on a 1:4-scale timber roof truss model. In this article, the functioning principles of the proposed SMA-based device prototype are illustrated and the main aspects related to its implementation in practice are discussed in detail. Finally, a recent example of application of the proposed technology to a historic single-aisle church, realized in the 13th century in Brindisi (southern Italy), and equipped with inadequate and deteriorated steel tied rods, is shown.  相似文献   
20.
ABSTRACT

Despite the high vulnerability of historic structures to earthquakes, the approaches for evaluating seismic demand and capacity still appear inadequate and there is little consensus on the most appropriate assessment methods to use. To develop an improved knowledge on the seismic behavior of masonry structures and the reliability of analysis tools, two real-scale specimens were tested on a shake table, and several experts were invited to foresee failure mechanism and seismic capacity within a blind prediction test. Once unveiled, experimental results were simulated using multi-block dynamics, finite elements, or discrete elements. This article gathers the lessons learned and identifies issues requiring further attention. A combination of engineering judgment and numerical models may help to identify the collapse mechanism, which is as essential as it is challenging for the seismic assessment. To this purpose, discrete modeling approaches may lead to more reliable results than continuous ones. Even when the correct mechanism is identified, estimating the seismic capacity remains difficult, due to the complexity and randomness of the seismic response, and to the sensitivity of numerical tools to input variables. Simplified approaches based on rigid body dynamics, despite the considerable experience and engineering judgment required, provide as good results as do advanced simulations.  相似文献   
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