Intergenerational transmission of fertility in Spain among cohorts born during the first half of twentieth century

It is known that historically fertility is correlated between generations of the same family. These links tend to be explained either in terms of the biogenetic determinants of reproduction or by the transmission of intra-familial values associated with reproduction and family life. Less is known about the micro-determinants of these links or about the extent to which the progressive modernization of reproductive outcomes over the past century has affected behavior. In this paper, we will address these issues for Spain with data from the Socio-Demographic Survey (SDS) carried out in 1991 and including data on cohorts born between 1900 and 1946. These data enable us to explore the micro determinants of fertility at different points of time during this period. Our results point to the existence of a significant correlation between intergenerational reproductive outcomes that persists and strengthens throughout this period of demographic change. Results confirm the importance of birth order in large family groups where firstborn offspring are more likely to have larger families than subsequent siblings. There is also evidence that the strength of these intergenerational ties increases with the onset of more modern demographic behavior characterized by sharply declining fertility. The results presented here promise to condition future debates on the subject.     

Investigation of the early mineralisation on collagen in dentine of rat incisors by quantitative electron spectroscopic diffraction (ESD)

The earliest crystallites in dentine appear as chains of dots in ultra-thin sections viewed by transmission electron microscopy. These dots rapidly coalesce along the longitudinal directions of the collagen microfibrils to form needle-like structures that coalesce preferentially in lateral directions to form ribbon-like or plate-like crystallites. This morphological interpretation is supported by line-scans of the corresponding zero-loss filtered electron spectroscopic diffraction patterns, which demonstrate the crystalline structure of the dentine mineral (apatite). The intensity ratio of the Debye-Scherrer rings of the characteristic Bragg-reflections (002 to 300, together with 1 or 2 unresolved reflections) shows a maximum in the region of early chain-like and needle-like crystallites, decreasing with maturation of the dentine mineral to the ribbon-plate-like crystallites. Detailed investigations using line-scans of the zero-loss filtered electron spectroscopic diffraction patterns through the dentine zone show that the intensity ratio found near the mineralisation front is repeated 3–5 times at distances of about 10–20 m. This may represent a circadian pattern of mineralisation corresponding to light microscopically visible incremental lines in dentine.     

Effect of mulching with cereal straw and row spacing on spread of bean yellow mosaic potyvirus into narrow-leafed lupins (Lupinus angustifolius)

Two field experiments examined the effect of straw spread on the soil surface on the incidence of bean yellow mosaic potyvirus (BYMV) in plots of narrow-leafed lupin (Lupinus angustifolius) sown at narrow (17.5 cm) vs wide (35 cm) row spacing and low (25–30 kg/ha) vs medium (50–60 kg/ha) seeding rates. Virus ingress was by vector aphids flying from adjacent pastures dominated by subterranean clover. In Expt 1, in which BYMV infection was extensive, straw greatly decreased the rate and amount of virus spread regardless of row spacing or plant density, decreasing infection more than 70% by the final assessment date. This effect of straw was attributed to decreased landing rates of incoming vector alates. In the plots without added straw, narrow row spacing decreased BYMV % infection by 38% by the last assessment date. Sowing at the medium seeding rate also decreased infection. The effect of wide row spacing seemed due to delayed canopy closure between rows which is likely to have increased the landing of aphids while the effect of medium seeding rate was attributed partly to the dilution effect of greater plant numbers and partly to the effects of partial canopy development in decreasing landing rates. In Expt 2, in which the incidence of BYMV infection was low, added straw again decreased BYMV spread, but by only 25–27% at final assessment; there were no effects of row spacing or seeding rate. In both experiments, an additional “reference” treatment was included which had a high (90–100 kg/ha) seeding rate, narrow rows and no straw. The dense canopy it developed also decreased BYMV incidence but less than in the plots with added straw in Expt 1. In Expt 1, adding straw and the resulting decrease in plants killed by BYMV, were associated with an overall increase in lupin grain yield of 20%. The greater plant densities resulting from the medium seeding rate also increased grain yield but row spacing did not affect it significantly. These results indicate that retaining stubble on the soil surface at seeding will assist in management of BYMV infection in lupin crops but that wide row spacing in the absence of retained stubble is undesirable.     

民族植物学—社会及文化价值初探

简要介绍民族植物学的性质、研究现况及其在经济、生态、环境和学术上的应用情况。民族植物学的社会价值通过其在增强民族自信心、伦理学和知识产权等方面的作用得以论证。民族植物学的文化价值具体而生动,体现于种种直接的植物文化现象（如植物礼仪文化、食花文化、树叶信、草药文化等）和宗教行为（如植物图腾、树神崇拜、神林崇拜等）。通过对民族植物学的经济、生态价值和社会、文化价值的分析,作者相信,民族植物学对于文化多样性和生物多样性的保护将起到积极的作用。     

Social foraging: individual learning and cultural transmission of innovations

We present two stochastic models of individual and social learningthat count the number of individuals exhibiting a learned, resource-producingtrait in a group of social foragers. The novelty of our modelingresults from incorporating the empirically based assumptionthat rates of both individual and social learning should dependon the frequency of the learned trait within the group. Whenresources occur as clumps shared by group members, a naive individual'sacquisition of the skill required for clump discovery/productionshould involve opposing processes of frequency dependence. Theopportunity to learn via cultural transmission should increasewith the trait's frequency, but the opportunity for learningindividually should decrease as the trait's frequency increases.The results of the model suggest that the evolution of the capacityfor cultural transmission may be promoted in environments wherescrounging at resource clumps inhibits rates of individual learning.     

Transmission of male cytoplasm during fertilization in Nicotiana tabacum

Serially sectioned embryo sacs of Nicotiana tabacum were examined during fertilization events using transmission electron microscopy. After pollen tube discharge, the outer membrane of the sperm pair is removed, the two sperm cells are deposited in the degenerate synergid and the sperm cells migrate to the chalazal edge of the synergid where gametic fusion occurs. During fertilization, the male cytoplasm, including heritable organelles, is transmitted into the female reproductive cells as shown by: (1) the cytoplasmic confluence of one sperm and the central cell during cellular fusion, (2) the occurrence of sperm mitochondria (distinguished by ultrastructural differences) in the zygote cytoplasm and adjacent to the sperm nucleus, (3) the presence of darkly stained aggregates which are found exclusively in mature sperm cells within the cytoplasm of both female cells soon after cell fusion, and (4) the absence of any large enucleated cytoplasmic bodies containing recognizable organelles outside the zygote or endosperm cells. The infrequent occurrence of plastids in the sperm and the transmission of sperm cytoplasm into the egg during double fertilization provide the cytological basis for occasional biparental plastid inheritance as reported previously in tobacco. Although sperm mitochondria are transmitted into the egg/zygote, their inheritance has not been detected genetically. In one abnormal embryo sac, a pair of sperm cells was released into the cytoplasm of the presumptive zygote. Although pollen tube discharge usually removes the inner pollen-tube plasma membrane containing the two sperm cells, this did not occur in this case. When sperm cells are deposited in a degenerating synergid or outside of a cell, this outer membrane is removed, as it apparently is for fertilization.     

Price interconnection of fuel and food markets: Evidence from biodiesel in the United States

The food versus fuel issue has attracted considerable attention with the rapid growth of global biofuel production. The previous literature examining the interconnectedness between biofuel, fossil fuel and agricultural markets employed futures and spot prices. However, food security needs to be discussed with non-financial market prices, such as wholesale prices, since retail companies and households usually do not purchase products directly from financial markets, which encompass speculative activities, making them more volatile than non-financial ones. This paper focuses on non-financial markets in the United States to investigate the price-interconnection of biodiesel, highway diesel, crude oil, and soybean, initially applying partial wavelet coherence and the Diebold-Yilmaz connectedness index to price transmission research on biodiesel, highway diesel, crude oil, and soybean. Our main results are as follows: First, significant coherence between biodiesel and soybean, biodiesel and highway diesel, and highway diesel and crude oil is identified in the short and long term. Second, crude oil and biodiesel prices are found to be net transmitters, while soybean and highway diesel prices are net receivers. Finally, the crude oil market is identified as the source of spillovers among the four markets, and strongly influences the highway diesel market.     

Rethinking stone age economics: Some speculations concerning the pre-Columbian Yanoama economy

The introduction of steel tools and new crops radically transformed the Yanoama Indians' pre-Columbian economy. A consideration of the impact of these innovations allows for the reconstruction of that economy which suggests a higher dependence upon foraging, a lower population density, more mobile settlement pattern, and heavier workload, than today. This reconstruction challenges both current speculations about pre-Columbian Amazonian economic systems which apply Sahlins' concept of aboriginal affluence and those concerning the relationship between Amazonian environment and cultural development. This reconstruction, confirmed in part by fragmentary historical sources, explores some of the dramatic changes which must have taken place since contact. The Yanoama's agricultural subsistence base is a recent innovation, made possible since contact by new tools and new crops.This article has benefitted considerably from conversations with Emilio Fuentes to whom I offer my gratitude. I would also like to thank the anonymous reviewer who made detailed comments on a first draft.     

Fasciola hepatica: Migration of newly excysted juveniles in resistant rats

Using transmission and scanning electron microscopy, the early migration of juvenile Fasciola hepatica was examined in naive and resistant rats. In naive rats, the migration of flukes to the peritoneal cavity was uneventful. In resistant rats, flukes were rapidly coated with antibody whilst still in the gut lumen and a proportion of the flukes were unable to penetrate the intestinal wall. Those that did penetrate were unharmed as they crossed the gut wall, but on entering the peritoneal cavity they were coated with antibody and host cells including eosinophils, neutrophils, macrophages, and mast cells. Eosinophils were seen degranulating onto the fluke surface, and this appeared to result in the erosion of the tegumental syncytium.     

A filamentous virus of the honey bee

A common and widespread disease of honey bees, Apis mellifera, is caused by an unoccluded, Feulgen-positive, filamentous nuclear virus. Ovoid viral particles seen in diseased bee hemolymph consisted of a folded nucleocapsid within a viral envelope and were 0.40 by 0.10 μm. Virions with unfolded nucleocapsids were about 3060 by 60 nm. The disease was transmissible to bees both per os and by injection, but efforts to infect oriental cockroaches, Blatta orientalis, and the greater wax moth, Galleria mellonella, failed. The disease is apparently the same as that described as a rickettsial disease of European bees.