Partly decoupled tree-ring width and leaf phenology response to 20th century temperature change in Sweden

The recent warming trend, and associated shifts in growing season length, challenge the principle of uniformitarianism, i.e., that current relations are persistent over time, and complicates the uncritical inferences of past climate from tree-ring data. Here we conduct a comparison between tree-ring width chronologies of Pinus sylvestris L. (Scots pine), Picea abies (L.) Karst. (Norway spruce) and Betula pubescens Ehrh. (Downy birch) and phenological observations (budburst and leaf senescence) of Fagus sylvatica L. (European beech), Quercus robur L. (European oak), Betula sp. (Birch), Norway spruce and Scots pine) in Sweden to assess to what extent the tree-ring width–temperature relationship and the timing of phenological phases are affected by increased temperature. Daily meteorological observations confirm a prolongation of the thermal growing season, most consistently observed as an earlier onset of around 1–2 weeks since the beginning of the 20th century. Observations of budburst closely mimic this pattern, with budburst of the deciduous trees occurring 1–2.5 weeks earlier. In contrast to the changes seen in phenology and observational temperature data, the tree-ring width–temperature relationships remain surprisingly stable throughout the 20th century. Norway spruce, Scots pine and Downy birch all show consistently significant correlations with at least one 30 day-long window of temperature starting in late June–early July season. Norway spruce displays the largest degree of stability, with a consistent 60 day-long temperature window with significant correlation starting around Julian calendar day 150. Thus, our results suggest that the principle of uniformitarianism is not violated during the period covered by modern meteorological observations. Further research is needed to determine at what thresholds the temperature sensitivity of these species may alter or deteriorate as a consequence of the ongoing climate change.     

Reproductive pattern among women in 19th century Sweden

Among the married female population in rural areas of 19th century Sweden infertility and subfertility were found in 7.5% and 6.1% respectively with increasing incidence during the latter half of the century. In relation to the age group 20-24, fecundity declined by 42% and 92% in the age groups 35-39 and 40-45 respectively. One-third of married women died before age 50. Re-marriages and step-parents were common. Less than half of the married women brought up the majority of the children in the community.     

Some 20th century fish discoveries

Of the approximately 1.5 million species described to date, about 48 170 (3.2%) are vertebrates. Of these 24 618 (51%) are fishes. Amazingly, 41% of fishes are found in fresh water which makes up a negligible percentage of the water on earth. The sea accounts for 97% of all water on the planet and contains 58% of the fish species, mostly from shallow, warm-coastal areas. The families Cichlidae, Cyprinidae, Characidae, Loricariidae, and Cyprinodontidae constitute about half of all the recently described new freshwater fish species named in the period 1978–1993. The Gobiidae and Serranidae are the marine families with the largest number of recently described new species. The most new freshwater teleost names came from South America (39%), Africa (32%) and Asia (17%). New fish species continue to be described at the rate of roughly 130–160 each year. An estimated 13 775 new fish names have been proposed in this century, representing about 56% of all currently known fish species. Three species are discussed in detail to represent remarkable examples of 20th century fish discoveries: the coelacanth Latimeria chalumnae, the salamanderfish Lepidogalaxias salamandroides of Western Australia, and the megamouth shark Megachasma pelagios. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cutting of lichen trees: a survival strategy used before the 20th century in northern Sweden

Sami reindeer herders in northern Fennoscandia have historically cut trees with high quantities of arboreal lichens to feed their animals during harsh winters. In this study we analysed temporal and spatial patterns of lichen-tree cuttings of Scots pine in a remote forest landscape in northern Sweden. We wanted to test the hypothesis that repeated cutting of such trees may have had long-lasting effects on the forest ecosystem that are still discernable today. Our analyses included an inventory of remaining lichen-tree stumps, and a field survey of forest variables to relate structural variation within the forest to these cuttings. We used dendrochronological methods to date stumps and reconstruct forest structure. Our results show that more than 7,000 trees were cut for this purpose over a period of almost 300 years within an area covering 6 km². Lichen-tree cutting was most intense during the late 18th century when ca. 600–1,000 trees were cut during each decade. We did not detect any significant relationship between past lichen-tree cutting and present small-scale forest heterogeneity, and suggest that this might be due to the small size of the cut trees and the long time elapsed since most of the cuttings. We conclude that vestiges such as stumps from lichen-tree cutting are highly valuable for our understanding of past land use. Furthermore, since they are located in an unlogged and very old forest, this highlights the need to acknowledge the interconnectedness between ecological and cultural values of such forests and the need to identify and protect them.     

Captive animal liability: 19th century foundations and 20th century modifications

Two important legal milestones concerning liability for keeping animals in captivity occurred in the years 1879–1881. These were the publication of The Common Law by Oliver Wendell Holmes, and the United States Supreme Court's decision in The Congress and Empire Spring Company v. Ann P. Edgar. Holmes declared that the liability one incurs for maintaining potentially dangerous animals is absolute. The Court's decision noted that wild animals not normally considered ferocious, such as deer, can be considered “domestic” under the law if they are tame, with a corresponding reduction in liability. A brief examination is presented of how the doctrine of captive animal liability was modified in the 20th century to reflect the difference between wild animals kept by a private individual and those maintained by a reputable zoological park. Zoo Biol 22:489–496, 2003. © 2003 Wiley‐Liss, Inc.     

Modeling games from the 20th century

A scientific framework is described in which scientists are cast as problem-solvers, and problems as solved when data are mapped to models. This endeavor is limited by finite attentional capacity which keeps depth of understanding complementary to breadth of vision; and which distinguishes the process of science from its products, scientists from scholars. All four aspects of explanation described by Aristotle trigger, function, substrate, and model are required for comprehension. Various modeling languages are described, ranging from set theory to calculus of variations, along with exemplary applications in behavior analysis.     

The development of biochemistry in the 20th century

Summary This lecture consists of a short appraisal of some of the main features that have characterized the growth of biochemistry during the course of the 20th century. It dwells on the early impacts of vitalism, the emergence and elucidation of the vitamins, the discovery of coenzymes, the concept of active centres of enzymes, the development of experimental techniques (including the use of isotopes), the genetic code, and on the development of molecular biology and closely allied fields of investigation. It concludes with a consideration of the influence of the study of membranes and of neurochemistry on current biochemical thought.Résumé Dans cet exposé, nous examinons brièvement certains des principaux aspects qui ont caractérisé la croissance de la biochimie au cours du 20^e siècle. Nous insistons sur les premiers impacts du vitalisme, l'émer-gence et la mise en lumière des vitamines, la découverte des coenzymes, le concept des centres actifs dans les enzymes, le développement des techniques expérimentales (y compris l'emploi des isotopes), le code genetique et le développement de la biologie moléculaire et des domaines étroitement apparentés de la recherche. En conclusion, nous considérons l'influence de l'étude des membranes et de la neurochimie sur la pensée biochimique actuelle.The substance of this paper was presented in the Rossiter Research Conference Structure and Function of Biological Membranes held October 1–4, 1983, at the Geneva Park Conference Centre, Lake Couchiching, Ont.Professor Emeritus (Neurochemistry) at University of British Columbia.     

Human cystic echinococcosis in Sardinia during the 20th century

At the beginning of the 20th century in Sardinia human Cystic Echinococcosis was considered a highly endemic disease by all the health operators. In the early twenties the number of reported cases was 429, but incidence appeared rising due to increase in availability of data and to improvements in diagnosis. The fall of personal and public hygienic conditions together with the drift from urban to rural areas during the second world war, had in fact facilitated the possibilities of infection, causing a strong growth of surgical cases during the post war years, so that incidence rate remains high and almost unvaried until the end of the eighties. Comparative analysis of young and probably old cysts indicates that this high rate of surgical cases was attributable to treated hepatic cysts in elderly. On the contrary the continuous reduction in the number of young cysts clearly shows a slow but constant decrease of the infection rate.     

Trends and uncertainties in Siberian indicators of 20th century warming

Estimates of past climate and future forest biomass dynamics are constrained by uncertainties in the relationships between growth and climatic variability and uncertainties in the instrumental data themselves. Of particular interest in this regard is the boreal-forest zone, where radial growth has historically been closely connected with temperature variability, but various lines of evidence have indicated a decoupling since about the 1960s. We here address this growth-vs.-temperature divergence by analyzing tree-ring width and density data from across Siberia, and comparing 20th century proxy trends with those derived from instrumental stations. We test the influence of approaches considered in the recent literature on the divergence phenomenon (DP), including effects of tree-ring standardization and calibration period, and explore instrumental uncertainties by employing both adjusted and nonadjusted temperature data to assess growth-climate agreement. Results indicate that common methodological and data usage decisions alter 20th century growth and temperature trends in a way that can easily explain the post-1960 DP. We show that (i) Siberian station temperature adjustments were up to 1.3 °C for decadal means before 1940, (ii) tree-ring detrending effects in the order of 0.6–0.8 °C, and (iii) calibration uncertainties up to about 0.4 °C over the past 110 years. Despite these large uncertainties, instrumental and tree growth estimates for the entire 20th century warming interval match each other, to a degree previously not recognized, when care is taken to preserve long-term trends in the tree-ring data. We further show that careful examination of early temperature data and calibration of proxy timeseries over the full period of overlap with instrumental data are both necessary to properly estimate 20th century long-term changes and to avoid erroneous detection of post-1960 divergence.     

Ten greatest discoveries of the 20th century in cardiovascular medicine

The Netherlands Society of Cardiology (NVVC) was founded 70 years ago on 28 April 1934. When looking back at the history of our Society on its 70th anniversary, it might be a nice opportunity to mention ten great discoveries in cardiology in the 20th century.     

20世纪生物科学前进的足迹(Ⅰ)

20世纪生物科学发展速度惊人 ,在众多领域都有新的发现和重大突破 ,2 0世纪取得的这些重大成果 ,使生物科学得到空前的发展和完善 ,为 2 1世纪生物科学的腾飞奠定了坚实的基础。现将2 0世纪生物科学的重大成果介绍给广大读者。190 1年△奥地利病理学家卡尔 兰德斯坦纳 (ＫａｒｌＬａｎｄｓｔｅｉｎｅｒ)发现了人的ＡＢＯ血型系统。△奥地利的休斯 (Ｅ .Ｓｕｅｓｓ)出版巨著《地球的面貌》 ,书中首次提出“生物圈”这一重要术语。△德国细菌学家贝林 (ＥｍｉｌｖｏｎＢｅｈｒｉｎｇ)由于对血清疗法特别是抗白喉血清疗法的研究及发现白喉抗毒…     

A century of tree line changes in sub‐Arctic Sweden shows local and regional variability and only a minor influence of 20th century climate warming

Aim Models project that climate warming will cause the tree line to move to higher elevations in alpine areas and more northerly latitudes in Arctic environments. We aimed to document changes or stability of the tree line in a sub‐Arctic model area at different temporal and spatial scales, and particularly to clarify the ambiguity that currently exists about tree line dynamics and their causes. Location The study was conducted in the Torneträsk area in northern Sweden where climate warmed by 2.5 °C between 1913 and 2006. Mountain birch (Betula pubescens ssp. czerepanovii) sets the alpine tree line. Methods We used repeat photography, dendrochronological analysis, field observations along elevational transects and historical documents to study tree line dynamics. Results Since 1912, only four out of eight tree line sites had advanced: on average the tree line had shifted 24 m upslope (+0.2 m year^?1 assuming linear shifts). Maximum tree line advance was +145 m (+1.5 m year^?1 in elevation and +2.7 m year^?1 in actual distance), whereas maximum retreat was 120 m downslope. Counter‐intuitively, tree line advance was most pronounced during the cooler late 1960s and 1970s. Tree establishment and tree line advance were significantly correlated with periods of low reindeer (Rangifer tarandus) population numbers. A decreased anthropozoogenic impact since the early 20th century was found to be the main factor shaping the current tree line ecotone and its dynamics. In addition, episodic disturbances by moth outbreaks and geomorphological processes resulted in descent and long‐term stability of the tree line position, respectively. Main conclusions In contrast to what is generally stated in the literature, this study shows that in a period of climate warming, disturbance may not only determine when tree line advance will occur but if tree line advance will occur at all. In the case of non‐climatic climax tree lines, such as those in our study area, both climate‐driven model projections of future tree line positions and the use of the tree line position for bioclimatic monitoring should be used with caution.     

20th century at a glance: the streptomycin story

The discovery of streptomycin is attributed to a microbiologist, Selman Waksman, Nobel Prize 1952, a paternity that was disputed by his collaborator Albert Schatz, who was the first author of the princeps article. Two pioneering clinical studies involved streptomycin, both of which have been widely used as reference works. The first one was English, under the name of Austin Bradford Hill. It inaugurated a randomization in medicine. The second trial was American, and carried out by the Veteran Administration. It made use for the first time of the "control group". The present article analyses the genesis of clinical trials and illustrates the recurrent difficulties encountered in their implementation.