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771.
Last Glacial mammals in South America: a new scenario from the Tarija Basin (Bolivia) 总被引:2,自引:0,他引:2
Coltorti M Abbazzi L Ferretti MP Iacumin P Rios FP Pellegrini M Pieruccini P Rustioni M Tito G Rook L 《Die Naturwissenschaften》2007,94(4):288-299
The chronology, sedimentary history, and paleoecology of the Tarija Basin (Bolivia), one of the richest Pleistocene mammalian
sites in South America, are revised here based on a multidisciplinary study, including stratigraphy, sedimentology, geomorphology,
paleontology, isotope geochemistry, and 14C geochronology. Previous studies have indicated a Middle Pleistocene age for this classic locality. We have been able to
obtain a series of 14C dates encompassing all the fossil-bearing sequences previously studied in the Tarija Basin. The dated layers range in age
from about 44,000 to 21,000 radiocarbon years before present (BP), indicating that the Tarija fauna is much younger than previously
thought. Glacial advances correlated to marine isotopic stages (MIS) 4 and 2 (ca. 62 and 20 ka BP, respectively) are also
documented at the base and at the very top of the Tarija–Padcaya succession, respectively, indicating that the Bolivian Altiplano
was not dry but sustained an ice cap during the Last Glacial Maximum. The results of this multidisciplinary study enable us
to redefine the chronological limits of the Tarija sequence and of its faunal assemblage and to shift this paleontological,
paleoclimatological, and paleoecological framework to the time interval from MIS 4 to MIS 2. 相似文献
772.
A male gift to its partner? Cyanogenic glycosides in the spermatophore of longwing butterflies (<Emphasis Type="Italic">Heliconius</Emphasis>) 总被引:1,自引:0,他引:1
Males of several insect species transfer nuptial gifts to females during mating, typically in the form of a protein-rich spermatophore.
In chemically defended species, males could potentially enhance such a gift with chemicals that help protect the female, her
eggs, or both. This was shown for lepidopteran species that accumulate pyrrolizidine alkaloids. Most Heliconius butterflies are presumably protected from predators by virtue of de novo synthesized and/or sequestered cyanogenic glycosides.
Males of Heliconius species are known to transfer nutritional gifts to the females but whether defensive chemicals could also be transferred
is not known. To ascertain whether transfer of cyanogens occurs, we dissected freshly mated females from nine different Heliconius species and analyzed spermatophores for cyanogenic glycosides. We found cyanogens in the spermatophores of all nine species.
This is the first time cyanogenic glycosides are reported in the spermatophores of arthropods. We discuss the implications
of these findings for Heliconius biology and for other cyanogenic insects as well. We suggest that chemically defended species commonly lace their nuptial
gifts with defensive chemicals to improve gift quality. 相似文献
773.
774.
Dicky Simorangkir 《Mitigation and Adaptation Strategies for Global Change》2007,12(1):147-164
During the last two decades Indonesia has experienced immense forest and land fires. Often these fires are associated with
extended drought and widespread use of fire to clear previously logged forest and other degraded land in preparation for oil
palm, rubber, or pulpwood plantations. There are many reasons for the use of fire in land clearing activities, but probably
the most important one is economics. There is still acceptance that fire is the cheapest, fastest, and most effective land
clearing method with the added benefit of providing nutrients from ash residues.
This paper provides a review of existing information on the financial costs and benefits of using fire for land clearing in
agriculture and forestry plantations as compared with zero-burning techniques. The findings indicate that the economic advantage
of fire use varies widely and depends on many factors, such as soil fertility, vegetation density, labour cost, equipment
and training costs, and the costs of fire management. For large-scale land clearing, the financial analysis of the costs and
benefits of fire versus zero-burning shows that when applied to low-volume vegetation, zero-burning methods are not more expensive
than burning – and may actually be more cost effective in the long term. This is the case for clearing oil palm or rubber
plantations for replanting, low secondary vegetation, and heavily logged-over forest. Under high-volume forest conditions,
burning remains less expensive because it is more difficult, time consuming, and costly to dispose of high volumes of piled
wood mechanically. 相似文献
775.
Stefan Hochrainer Joanne Linnerooth-Bayer Reinhard Mechler 《Mitigation and Adaptation Strategies for Global Change》2010,15(7):797-810
This paper examines the legitimacy, viability and efficiency of the European Union Solidarity Fund by asking whether the Fund
meets its stated purpose of providing solidarity within the EU, whether it is sufficiently capitalized and if it promotes
disaster risk reduction in Europe. In examining these questions, we make use of ADAM models of disaster risks throughout Europe.
We conclude that the Solidarity Fund falls short on all three counts, and we suggest possible alternatives. Most far-reaching,
we explore whether the EUSF could support insurance systems in Europe by, among other possible activities, capitalizing national
public-private insurance programs and providing support for government risk transfer. This would leverage the Fund’s capital
and would overcome barriers to the provision of private and public sector insurance in uncertain catastrophe markets. It would
also make insurance more affordable to Europe’s most vulnerable communities. Finally, it would reduce the disincentives for
risk reduction inherent in post-disaster assistance. 相似文献
776.
Monica A. Sundset Perry S. Barboza Thomas K. Green Lars P. Folkow Arnoldus Schytte Blix Svein D. Mathiesen 《Die Naturwissenschaften》2010,97(3):273-278
Reindeer (Rangifer tarandus) eat and utilize lichens as an important source of energy and nutrients in winter. Lichens synthesize and accumulate a wide
variety of phenolic secondary compounds, such as usnic acid, as a defense against herbivores and to protect against damage
by UV-light in solar radiation. We have examined where and to what extent these phenolic compounds are degraded in the digestive
tract of the reindeer, with particular focus on usnic acid. Three male reindeer were given ad libitum access to a control
diet containing no usnic acid for three weeks and then fed lichens ad libitum (primarily Cladonia stellaris) containing 9.1 mg/g DM usnic acid for 4 weeks. Usnic acid intake in reindeer on the lichen diet was 91–117 mg/kg BM/day.
In spite of this, no trace of usnic acid or conjugates of usnic acid was found either in fresh rumen fluid, urine, or feces.
This suggests that usnic acid is rapidly degraded by rumen microbes, and that it consequently is not absorbed by the animal.
This apparent ability to detoxify lichen phenolic compounds may gain increased importance with future enhanced UV-B radiation
expected to cause increased protective usnic acid/phenol production in lichens. 相似文献
777.
Monalisa Chatterjee 《Mitigation and Adaptation Strategies for Global Change》2010,15(4):337-353
Megacities in developing countries are rapidly transforming places. Under the impetus of global change processes and consequent
transformations at the environmental, social, cultural, political and economical scales; factors causing disasters and losses
are changing every day. These changes are also altering society’s ability to respond to hazard events. This paper examines
the response of slum dwellers who are the most vulnerable and marginal section of urban population and often located in places
with high hazard risk with less or no means to reduce the impact of flood events. Marginal population groups in megacities
suffer the negative consequences of large scale global change processes and do not benefit from the risk mitigation strategies
adopted by city authorities. The paper therefore argues that people living in informal settlements instead have to employ
a combination of structural means and complex networks of assistance to recover from floods. Based on the results deduced
from data collected with the help of household surveys in the slums of Mumbai, the study demonstrates the types of coping
strategies used by slum dwellers and the changing characteristics of these mechanisms under the influence of global change
processes in megacities. Furthermore, results show that capacity to respond is not equally distributed among slum dwellers
due to underlying socio cultural divisions and emerging economic and political constraints. The paper concludes that to address
existing discrepancies in urban societies and within slum settlements, flood mitigation strategies will have to be (1) more
inclusive of marginal population (2) sensitive to the limitations and scope of old and new social structures and (3) incorporate
innovative networks of support to deal with the consequences of global change. 相似文献
778.
Ingeborg L. A. Boxman 《Food and environmental virology》2010,2(3):156-166
Different sources were consulted to obtain information on the occurrence of viruses in bivalve molluscs on the European market.
Twenty-six peer-reviewed articles were identified reporting on the molecular detection of viral RNA in 4,260 samples in total.
The data obtained will be presented geographically on virus types detected, the origin and treatment of the shellfish, and
the detection technique applied. The data demonstrate that viral RNA can be detected in shellfish from polluted areas, in
depurated shellfish as well as those for human consumption. The European Rapid Alert System for Food and Feed (RASFF) database
was consulted as another source. Twenty-eight notifications were identified on the presence of hepatitis A virus or norovirus
in shellfish on the European market. The most recent report of the European laboratory network was referred to, to gain insight
into the laboratory capability at present for the analyses of shellfish on the presence of viruses. Approximately 67% of 27
participating laboratories obtained intended results for all samples, consisting of lenticules loaded with 103 copies norovirus (genogroup I (GGI) and/or genogroup II (GGII)) and/or 1 × 105–8 × 104 copies of hepatitis A virus. From 1993, there has been a continuous development of molecular detection techniques and tools
have been described to ensure quality assurance. End product testing will, however, not be achievable. As depuration has been
shown not to be effective for the complete elimination of viruses, shellfish should not be in contact with faecal contaminated
water in order to minimise the risk of shellfish-transmittable viral diseases. 相似文献
779.
Asbjørn Aaheim Bård Romstad Håkon Sælen 《Mitigation and Adaptation Strategies for Global Change》2010,15(7):763-778
This paper describes how relatively detailed knowledge about probabilities of natural hazards can be used to make decisions
to develop areas and control the risk within hazard zones. The assessment serves two purposes. First, it shows how information
can support decisions. Second, decision criteria put leads on what information is required. This is helpful to identify unavailable
information. We show by an example from a land-slide prone area in Norway how a relatively reliable estimate of the probability
of slides ends up in a rather uncertain estimate of the risk. Uncertainty about the risk represented by natural hazards imply
great challenges to the development of adaptation policies to meet climate change, but they are required. We develop a simplified
criterion for optimal adaptation, and estimate the added social value required to defend development in hazard prone areas
instead of developing a risk-free alternative. The value is estimated between 0 and 0.40 Euros per Euro invested in the case
area, depending on type of slide, category of asset and other costs that occur in the wake of slides. 相似文献
780.
Pigeons were released at two sites of equal distance from the loft, one within a magnetic anomaly, the other in magnetically
quiet terrain, and their tracks were recorded with the help of GPS receivers. A comparison of the beginning of the tracks
revealed striking differences: within the anomaly, the initial phase lasted longer, and the distance flown was longer, with
the pigeons' headings considerably farther from the home direction. During the following departure phase, the birds were well
homeward oriented at the magnetically quiet site, whereas they continued to be disoriented within the anomaly. Comparing the
tracks in the anomaly with the underlying magnetic contours shows considerable differences between individuals, without a
common pattern emerging. The differences in magnetic intensity along the pigeons' path do not differ from a random distribution
of intensity differences around the release site, indicating that the magnetic contours do not directly affect the pigeons'
routes. Within the anomaly, pigeons take longer until their flights are oriented, but 5 km from the release point, the birds,
still within the anomaly, are also significantly oriented in the home direction. These findings support the assumption that
magnetically anomalous conditions initially interfere with the pigeons' navigational processes, with birds showing rather
individual responses in their attempts to overcome these problems. 相似文献