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41.
ABSTRACTThis article examines recent evidence from Denmark and abroad regarding climate change projects that aim to reduce global carbon dioxide emissions by converting coal-fired thermal power plants to solid biomass fuel. The article argues that projects appear to be pursued narrow-mindedly with insufficient attention paid to safety and points to evidence of media shifting—that the “resolution” of a problem within the environmental domain creates a new problem in the workplace safety domain. From the perspective of inherent safety the article argues that the conversion is a step in the wrong direction as a low risk fuel is substituted for a less safe one. Because of rapid scale-up and handling of unprecedented quantities, solid biomass qualify as an emerging risk for which proper control strategies have yet to be developed. The article finally argues that the tendency to prioritize environmental benefits over safety concerns seems to run deep and not confined to the realm of only solid biomass. Danish environmental ambitions are very high and the costs to society of introducing solid biomass fuels are breathtaking. In this setting, the general failure to address safety risks appears particularly disheartening. 相似文献
42.
α-Amylase from Aspergillus oryzae was covalently immobilized onto polystyrene pellets with pentaethylenehexamine (PS-PEHA-Ald) and pentaethylene glycol (PS-PG-Ald) carrying a terminal aldehyde group. Optimum immobilization occured at pH 8.0 and 25 °C, and at pH 7.0 and 35 °C for PS-PEHA-Ald and PS-PG-Ald, respectively. PS-PEHA-Ald immobilized enzyme retained approximately 75% of the initial activity over 45 days of storage, 70% of the initial activity after nine runs of recycling and displayed the better resistance to detrimental metal ions. PS-PG-Ald immobilized enzyme retained approximately 50% of the initial activity in 8h at 70 °C. The catalytic efficiencies of PS-PEHA-Ald immobilized and PS-PG-Ald immobilized amylase were 1.42 and 1.29 times higher than that of native enzyme. The activation energy of the reaction mediated by the amylase was reduced by 58.1% and 57.3% when PS-PEHA-Ald and PS-PG-Ald used as support respectively. 相似文献
43.
A life cycle evaluation of wood pellet gasification for district heating in British Columbia 总被引:1,自引:0,他引:1
The replacement of natural gas combustion for district heating by wood waste and wood pellets gasification systems with or without emission control has been investigated by a streamlined LCA. While stack emissions from controlled gasification systems are lower than the applicable regulations, compared to the current base case, 12% and 133% increases are expected in the overall human health impacts for wood pellets and wood waste, respectively. With controlled gasification, external costs and GHG emission can be reduced by 35% and 82% on average, respectively. Between wood pellets and wood waste, wood pellets appear to be the better choice as it requires less primary energy and has a much lower impact on the local air quality. 相似文献
44.
Hoffecker JF 《Evolutionary anthropology》2011,20(1):24-39
Artifacts of Paleolithic age were first recognized in eastern Europe during the 1870s. Archeologists have struggled ever since to integrate them into the better known record of western Europe, where the interpretive framework of Paleolithic archeology was originally developed. The essential elements of both the Middle and Upper Paleolithic were recognized quickly in eastern Europe, and a close connection with a major middle Upper Paleolithic industry of central Europe (Gravettian) was established many years ago. The early Upper Paleolithic (EUP) has remained a major challenge, however; it is represented primarily by a bewildering array of local archeological cultures that exhibit limited similarity to contemporaneous industries of western and central Europe.6-9. 相似文献
45.
Takasaka T Kitamura T Sugimoto C Guo J Zheng HY Yogo Y 《American journal of physical anthropology》2006,129(3):465-472
Both mtDNA and the Y chromosome have been used to investigate how modern humans dispersed within and out of Africa. This issue can also be studied using the JC virus (JCV) genotype, a novel marker with which to trace human migrations. Africa is mainly occupied by two genotypes of JCV, designated Af1 and Af2. Af1 is localized to central/western Africa, while Af2 is spread throughout Africa and in neighboring areas of Asia and Europe. It was recently suggested that Af1 represents the ancestral type of JCV, which agrees with the African origin of modern humans. To better understand the origin of modern Africans, we examined the phylogenetic relationships among Af2 isolates worldwide. A neighbor-joining phylogenetic tree was constructed based on the complete JCV DNA sequences of 51 Af2 isolates from Africa and neighboring areas. According to the resultant tree, Af2 isolates diverged into two major clusters, designated Af2-a and -b, with high bootstrap probabilities. Af2-a contained isolates mainly from South Africa, while Af2-b contained those from the other parts of Africa and neighboring regions of Asia and Europe. These findings suggest that Af2-carrying Africans diverged into two groups, one carrying Af2-a and the other carrying Af2-b; and that the former moved to southern Africa, while the latter dispersed throughout Africa and to neighboring regions of Asia and Europe. The present findings are discussed with reference to relevant findings in genetic and linguistic studies. 相似文献
46.
47.
Ronald P. Ladouceur 《Journal of the history of biology》2008,41(3):435-471
Two influential articles published in the 1970s suggested that pressure from Christian fundamentalists, subsequent to the
Scopes trial of 1925, forced American high school biology textbook authors and publishers to significantly limit discussion
of the topic of evolution. The conclusions reached by these studies have become foundational for historians examining the
interplay between science and religion in the United States in the twentieth century. However, a reexamination of key twentieth
century biology textbooks suggests that the narrative that the treatment of the theory of evolution was held hostage to anti-rational
cultural forces is largely a myth, created first as part of a public relations effort by the Biological Sciences Curriculum
Study (BSCS) to differentiate, defend, and promote its work, and later as part of an attempt by scholars to sound a warning
concerning the rise of the religious right. A focus on this narrative has not only allowed biologists to sidestep uncomfortable
questions regarding the race-biased and class-biased assumptions embedded within the concept of evolutionary progress, it
has also limited reliance on the texts in question as reliable reflections of the cultural assumptions of educators and scientists.
A reexamination of the most popular American biology textbooks from 1907 to 1963, particularly the work of Ella Thea Smith,
provides evidence in support of these contentions. 相似文献
48.
ABBEY K. THOMPSON MICHAEL D. SAMUEL TIMOTHY R. VAN DEELEN 《The Journal of wildlife management》2008,72(2):416-421
ABSTRACT We conducted experimental feeding using 3 feeding methods (pile, spread, trough) and 2 quantities (rationed, ad libitum) of shelled corn to compare deer activity and behavior with control sites and evaluate potential direct and indirect transmission of infectious disease in white-tailed deer (Odocoileus virginianus) in central Wisconsin, USA. Deer use was higher at 2 of the feeding sites than at natural feeding areas (P ≤ 0.02). Deer spent a higher proportion of time (P < 0.01) feeding at pile (49%) and spread (61%) treatments than at natural feeding areas (36%). We found higher deer use for rationed than ad libitum feeding quantities and feeding intensity was greatest at rationed piles and lowest at ad libitum spreads. We also observed closer pairwise distances (≤0.3 m) among deer when corn was provided in a trough relative to spread (P=0.03). Supplemental feeding poses risks for both direct and indirect disease transmission due to higher deer concentration and more intensive use relative to control areas. Concentrated feeding and contact among deer at feeding sites can also increase risk for disease transmission. Our results indicated that restrictions on feeding quantity would not mitigate the potential for disease transmission. None of the feeding strategies we evaluated substantially reduced the potential risk for disease transmission and banning supplemental feeding to reduce transmission is warranted. 相似文献
49.
John F. Hoffecker 《Evolutionary anthropology》2005,14(5):186-198
The technology of modern humans is unique in the animal kingdom with respect to its complexity and capacity for innovation. Evidence of technological complexity and creativity in the archeological record is broadly coincident with and presumably related to traces of creativity in art, music, ritual, and other forms of symbolism. The pattern of modern human technology is part of a larger package of behavior (sometimes referred to as “behavioral modernity”) that emerges with the appearance of industries in Eurasia classified as Upper Paleolithic, but has deeper roots in the African Middle Stone Age. 1 - 5 . 相似文献
50.