More than 10 years after a chromosomal anomaly screening programme was set up in France for pregnant women of advanced age, amniocentesis is still a controversial issue. The reasons why eligible women did not utilize the test and whether or not the existence of social welfare coverage determined women's access to prenatal diagnosis were studied. A group of 291 women aged ⩾35 years who recently gave birth to normal liveborns was interviewed by telephone. Among those aged 38 years and over, who automatically qualified for social security coverage, 75 per cent had undergone amniocentesis as opposed to 23 per cent in the 35 to 37-year-old non-covered age group who did not qualify for social security coverage. In both groups, access to amniocentesis was found to depend on the physicians', women's and male partners' attitudes towards prenatal diagnosis and abortion. Among the younger group, the uptake depended mainly on socio-economic factors. Institutional policies should ensure greater equality of access while allowing for individual preferences. 相似文献
Mechanical friction and impacts is still today a main cause of ignition of explosive atmospheres (ATEX) in the industry and this trend seems to be stable in time. This situation certainly results from a significant gap of knowledge in the underlying mechanisms so that the parameters to play on are not precisely identified. In this programme of European dimensions, the process of degradation of the mechanical energy into heat during friction and impacts have been studied.
An extensive experimental programme is presented to this end. The mechanisms of dissipation of the mechanical energy into heat during friction has been studied with rubbing machines in which a slider equipped with temperature sensors rubs against a rotating wheel. For impacts, a new device has been developed using a special “air driven cannon” to propel a projectile accurately up to 50 m/s onto an inclined target. A very significant effort has been reserved to the investigation of the ignition mechanisms, not only for ATEX but also for dust accumulations.
Some “simple” modelling is proposed on purpose of practical applications. For frictional situations, a critical rubbing power is calculated without any limitations about any lower boundary concerning the rubbing velocity. For “impacts”, the relevant parameter for ignition is not the kinetic energy of the projectile but its velocity and the nature of the materials. 相似文献
The influence of different states of oxygen supply on heptadecane mineralization has been investigated in resting cell suspensions of Pseudomonas nautica. The rate of heptadecane biodegraded was constant for oxygen concentrations between 21% and 10% (v/v) (about 100% and 50% of air saturation, 230 and 110 microM, respectively). A decline in biodegradation rates occurred for oxygen concentrations below 10% (about 50% of air saturation, 110 microM) and biodegradation stopped with 0.21% oxygen (2.3 microM). In the presence of 1% (11 microM) of oxygen, no CO2 was produced, showing that complete mineralisation of heptadecane was blocked. 相似文献
Investigation at the scene of a crime begins with the search for clues. In the case of bloodstains, the most frequently used
reagents are luminol and reduced phenolphthalein (or phenolphthalin that is also known as the Kastle–Meyer colour test). The
limitations of these reagents have been studied and are well known. Household cleaning products have evolved with the times,
and new products with active oxygen are currently widely used, as they are considered to be highly efficient at removing all
kinds of stains on a wide range of surfaces. In this study, we investigated the possible effects of these new cleaning products
on latent bloodstains that may be left at a scene of a crime. To do so, various fabrics were stained with blood and then washed
using cleaning agents containing active oxygen. The results of reduced phenolphthalein, luminol and human haemoglobin tests
on the washed fabrics were negative. The conclusion is that these new products alter blood to such an extent that it can no
longer be detected by currently accepted methods employed in criminal investigations. This inability to locate bloodstains
means that highly important evidence (e.g. a DNA profile) may be lost. Consequently, it is important that investigators are
aware of this problem so as to compensate for it.
Current models in evolutionary ecology predict life history alterations in response to habitat suitability to optimize fitness. Only few empirical studies have demonstrated how life history traits that are expected to trade off against each other differ among environments. In Europe, many salt marshes have been recently invaded by the grass Elymus athericus. Previous studies however showed higher densities of the endangered spider Arctosa fulvolineata (Araneae: Lycosidae) in invaded salt marshes compared to natural habitats, which suggests a lower habitat suitability in the latter. The aim of this study was to determine if this emerging habitat (1) affects the amount of resource acquisition and (2) alters the balance between life history traits that are expected to trade off against each other in this stenotopic salt marsh species. As suggested by theoretical studies, an optimization of fitness by increasing egg size at the cost of decreasing fecundity in unsuitable (i.e., natural) habitats was expected. Females presenting cocoon were then collected in close invaded and natural salt marsh areas within the Mont Saint-Michel Bay (France). By considering female mass as covariate, cocoon mass, number of eggs, and egg volume were compared between both habitats. Clutch mass was strongly determined by female mass in both habitats. Clutch mass was however significantly smaller in the natural habitat compared to the invaded habitat, indicating a higher resource acquisition in the latter. When correcting for female size, fecundity was additionally increased in the invaded habitat through a significant decrease in egg size. This phenotypic response can be explained by differences in habitat structure between invaded and natural habitats: the former offers a more complex litter favoring nocturnal wanderers like A. fulvolineata. The existence of such an adaptive reproduction strategy depending on habitat suitability constitutes an original case of an invasion that favors an endangered species. 相似文献
Climate change is one of the main challenges faced by mankind in this century. Although developing countries have little historical responsibility for climate change, they are likely to be most affected by it since they lack resources to cope with or to adapt to its effects. Studies show that the semi-arid northeast region of Brazil – where the country's poorest populations are concentrated – is one of the most vulnerable to climate change and thus likely to suffer its impacts more severely. The present paper addresses these problems by presenting a concrete initiative for strengthening adaptive capacity in the rural community of Pintadas as a first step in the development of a comprehensive methodology to help smallholder farmers in the region adapt to climate change. Based on the project results this paper highlights the integration of development, adaptive capacity and adaptation strategies. Furthermore, the necessity of vulnerability studies and concrete local experiences is highlighted in order to develop adaptation strategies that can alleviate poverty and minimize climate change impacts for the poor. 相似文献
Gorgonian species may contribute to the three-dimensional seascape in soft bottom-gravel areas, but the information on their
biology and ecology is very scarce. The biometry and secondary production of the Mediterranean soft bottom-gravel passive
suspension feeder Leptogorgia sarmentosa (Cnidaria: Octocorallia) was studied using photographic monitoring of the primary branches from May 1998 to September 2000.
The primary branches observed had a high density of polyps (2.2 ± 0.2 SD polyps mm−1) and a high organic matter content (63.2 ± 9.1 SD %). During the two-year sampling period, there was a net negative growth
in 90% of the gorgonian population. The mean loss during the 27-month period was −2.9 ± 0.9 SD cm per branch (5.7 mg C branch−1). However, considering only the initial and final diameters and maximum height in the 27 months elapsed time, the gorgonians
showed positive growth, which meant that photographic sampling of single branches was a more appropriate method for gorgonian
secondary production monitoring. A water mass anomaly detected in 1999 in the north-western Mediterranean Sea may have been
the cause of the net negative growth in L. sarmentosa in the studied area. Partial mortality due to different factors, such as strong currents, predation, disease, etc., could
be a common strategy in sessile colonial benthic populations that would facilitate their maintenance even during very stressful
circumstances. 相似文献
International institutions, understood as sets of rules contained in international agreements, are aimed at orienting national
governments towards specific policy options. Nevertheless, they can determine a change in national policies and practices
only if states are willing and capable of incorporating international obligations into their national legislations and ensuring
their application and enforcement in areas that follow completely under national jurisdiction. The establishment of marine
protected areas promoted by international agreements as a tool for the protection of marine resources represents an interesting
case for revealing the complex interactions between international institutions and national actors. Particularly, the establishment
of these areas in Senegal shows the salience of domestic constellations of actors who may support or undercut national commitments
to international regimes: political elites, bureaucracies, the general public and target groups. By anchoring the empirical
analysis to an actor-centred institutionalist perspective, the article explains how dynamic constellations of actors can distort
the penetration of international objectives in the national policy framework. Different constellations of national actors
can indeed bend international institutions at different moments: during the formulation of a new law in line with international
obligations; in the definition of its implementation framework; and in the enforcement of national policies. 相似文献
Historical records of sand drift and dune-building along the coastline of Western Europe provide insights into the natural
processes of sand dune accretion and both the impacts of, and human responses to, sand incursions. The analysis of documentary
records, instrumental data and proxy records over the last 1,000 years indicates that this period, which included the Little
Ice Age (AD 1570–1900), featured numerous episodes of sand drift and dune development driven by strong winds associated with
Atlantic storms. It is estimated that sand drift affected over a quarter of a million hectares of coastal land in Western
Europe. The widespread use of vegetation to stabilise coastal dune systems and prevent sand drift is documented across Europe
from AD 1100 and by the start of the 20th century all of the larger coastal dune systems in Portugal, France, Britain and
Denmark were comparatively inactive. Given that Atlantic storminess has remained more or less unchanged over the last 200 years,
modern dune management strategies which consider dune devegetation, driven by an increasing focus on ‘naturalness’, may give
rise to a recurrence of sand drift problems. Predictions of increased storm frequencies by the end of the 21st century, coupled
with sea level rise and potential changes in sand supply will present further challenges for the more ‘dynamic’ dune management
strategies. 相似文献
The distribution of urban ecosystem services (UES) is often uneven across socioeconomic groups, leading to environmental justice issues. Understanding the distribution of UES across a landscape can help managers ensure an equitable distribution of services. While many past studies have focused on the distribution of green spaces in relation to socioeconomic variables, this research analyzes the distribution of UES provided by these green spaces. This research quantified air pollution removal, atmospheric carbon reduction, and surface runoff mitigation provided by urban trees in Strasbourg city (France). The provision of these three UES was studied at the census block scale by creating an index of UES delivery, which was contrasted with a constructed social deprivation index. Our results show that there is no significant association between the delivery of UES and social deprivation. Some deprived populations benefit from high UES delivery. Results also suggest that mapping associations between UES delivery and social deprivation should be integrated with future development plans to enhance the equitable distribution of UES. This study provides insights into the French context where studies about the distribution of UES at a small-area level remain lacking. 相似文献