纺织品隔声性能的测试研究

本文提出了纺织品隔声性能的测试方法和评价指标,探讨了织物结构参数对隔声性能的影响。织物平方米重对声波衰减率的影响大于覆盖系数和厚度。织物对声波的衰减作用具有频率选择性。     

Closure of Disputes in Assessments of Climate Change in The Netherlands

2 greenhouse gases in assessment studies. For the cases studied, we identify variability in the assessment reports in the Netherlands during the pre-IPCC period. In the Netherlands arena, the assessments in this period can be seen as exponents of two different lines, a Netherlands line and an international line. We seek to identify what factors were decisive in the selection processes that resulted in the closure of visible disputes (visible in or across the assessment reports) for both cases. Our analysis reveals a remarkable difference in the adoption behavior of two Dutch assessment groups despite a large overlap in membership. We provide evidence that it is not the paradigmatic predisposition of the experts in the committee that was decisive for the closure of visible disputes, but it was the context in which the experts operated and the commitments they had made in each setting.     

Cool Ground for Aid Providers: Towards Better Security Management in Aid Agencies

Although full statistics are lacking, there is an impression that aid personnel are increasingly at risk from random, criminal and even at times targeted violence. The argument here is that the current tendency to reduce an agency's vulnerability mainly through the use of protective procedures and devices may be necessary but is insufficient. Better practice in the management of security is an urgent need. Reducing vulnerability to attack is only one approach; deterring the threat of violence by counter-threat, or seeking increased acceptance for the agency's work and presence are two other approaches. Major skill development is required in the areas of conflict analysis and monitoring, threat assessment and incident analysis, since together these form the basis for appropriate security management. Improved analysis can then inform a conscious choice about which mixture of approaches is most appropriate in a specific context. The paper explores in some detail the factors that influence acceptance, but not the methods and basic principles in the use of counter-threat.     

SAFE—A hierarchical framework for assessing the sustainability of agricultural systems

Sustainable development and the definition of indicators to assess progress towards sustainability have become a high priority in scientific research and on policy agendas. In this paper, we propose a consistent and comprehensive framework of principles, criteria and indicators (PC&I) for sustainability assessment of agricultural systems, referred to as the Sustainability Assessment of Farming and the Environment (SAFE) framework. In addition we formulate consistent and objective approaches for indicator identification and selection. The framework is designed for three spatial levels: the parcel level, the farm level and a higher spatial level that can be the landscape, the region or the state. The SAFE framework is hierarchical as it is composed of principles, criteria, indicators and reference values in a structured way. Principles are related to the multiple functions of the agro-ecosystem, which go clearly beyond the production function alone. The multifunctional character of the agro-ecosystem encompasses the three pillars of sustainability: the environmental, economic and social pillars. Indicators and reference values are the end-products of the framework. They are the operational tools that are used for evaluating the sustainability of the agro-ecosystems. The proposed analytical framework is not intended to find a common solution for sustainability in agriculture as a whole, but to serve as an assessment tool for the identification, the development and the evaluation of agricultural production systems, techniques and policies.     

Development of zinc bioavailability and toxicity for the springtail Folsomia candida in an experimentally contaminated field plot

The influence of outdoor exposure conditions and ageing of contamination on the toxicity of zinc was investigated for the springtail Folsomia candida to evaluate the validity of a standardised soil toxicity test. In three successive years, animals were incubated in an experimentally contaminated field plot. During the first months after construction of the test field, total zine concentrations of the soil decreased rapidly due to leaching of excess zinc with rainwater, while increased sorption of the remaining residues resulted in a reduced bioavailability of the metal. Although variation between replicates was substantial, the EC50s for the effect of zinc on reproduction of F. candida determined in the field experiments differed by less than a factor of two from effect concentrations obtained in laboratory tests in which the same soil was used. Expression of the EC50s on the basis of water soluble zinc allowed for a comparison with effect concentrations estimated for other soil types. EC50s were comparable with literature data, which indicates that bioavailability of zinc is the main factor determining toxicity for F. candida. It is concluded that laboratory based toxicity data are suitable to predict effects of zinc for F. candida under outdoor conditions, provided that the bioavailability of zinc is determined accurately using water soluble concentrations.     

Prenatal diagnosis of inherited metabolic disorders by quantitation of characteristic metabolites in amniotic fluid: Facts and future

An attempt is made to summarize as completely as possible what is known about the prenatal diagnosis of amino– and organic acidurias by direct measurement of characteristic metabolites in amniotic fluid, and to indicate which disorders can potentially be diagnosed prenatally by direct quantitation of metabolites. Furthermore, the disorders are mentioned in which the prenatal diagnosis was proven to be unsuccessful by this approach. The prenatal diagnoses of a case of propionic acidemia and a case of tyrosinemia type I in the 11th and 12th week of gestational age, respectively, are reported and the prospects of performing amniocentesis in the first trimester for prenatal diagnosis are discussed.     

Prenatal detection of cystic fibrosis; comparative study of maltase and alkaline phosphatase activities in amniotic fluid

The potential value of microvillar enzymes in the prenatal diagnosis of cystic fibrosis (CF) has previously been demonstrated and is corroborated in the present comparative study. Maltase and alkaline phosphatase (ALP) activities were studied in the amniotic fluids of 57 pregnancies with a 1 in 4 risk for CF or with a known CF outcome and in 489 controls. A simple assay for maltase activity (MU-maltase) with the fluorogenic substate 4-methylumbelliferyl α-glucoside, offers great technical advantages and an at least equal detection rate of CF, when compared to the previously used test with maltose as substrate. Intestinal ALP was estimated either as phenylalanine inhibitable activity (PI-ALP) or as the proportions of residual activity in the presence of the inhibitors phenylalanine or homoarginine. MU-maltase and PI-ALP appeared the most successful methods: both tests were able to detect 14 of the 16 (88 per cent) pregnancies with fetal CF. Each of the two tests alone also allowed a correct prediction in 24 of the 25 pregnancies at risk but with normal outcome; however all 25 cases could be correctly predicted by a combined evaluation. It is suggested that more than one intestinal enzyme activity should be evaluated to allow optimal results in the prenatal monitoring of pregnancies at high risk for CF.