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21.
Dissolved organic carbon (DOC) dynamics were investigated over a two year period in the Upper Rhǒne River to examine the role of side-arms in providing DOC to the main channel in relation to discharge fluctuations, especially floods. Concentrations of DOC are shown to remain low in space and in time (average 1.5 mg ?1) and to be more related to global hydrological events (precipitation) than to any local flushing for backwaters during floods. The results do not support the general assumption that side-arms are the providers of DOC to the main channel. 相似文献
22.
In this paper we will analyze the relationship between the value and duration moments of a cash flow and movements in the yield curve. We will show that for changes in the yield curve which can be related to tn , the 1st order changes in the net present value of a cash flow are linearly dependent on the n + lth duration moments, and that the 2nd order changes are dependent on the sum of duration moments of order 2 n + 1 and 2 n + 2. We will use this relationship to tilt tracking portfolios so as to protect them against specific changes in the yield curve. 相似文献
23.
24.
This paper compares the approximation capabilities of the minflex-Laurents translog and minflex generalized Leontief cost functions with their translog and generalized Leontief counterparts in Monte Carlo experiments. The minflex Laurent specifications generally provided closer approximations to underlying technical and economic parameters. Imposition of nonlinear restrictions on some of the parameters of the minflex Laurent models yielded measurable improvement in estimated elasticities of substitutions, returns to scale, and rates of technical change.The refereeing process of this paper was handled through E. Appelbaum. 相似文献
25.
Intensive fertilizer use has led to nitrate contamination of groundwater in many areas. This article examines the possibility of removing nitrates through the construction of artificial wetlands. A pilot study conducted in Denmark has found that the method is effective and economical, at least for small waterworks, though further treatment is necessary before an acceptable microbiological water quality is attained. 相似文献
26.
27.
David Hoopes 《R&D Management》2001,31(4):381-389
Managers and scholars emphasize the importance of inter‐departmental integration to successful product development and emphasize the importance of product development capabilities to firm performance. Interdepartmental integration can increase shared knowledge; this in turn can reduce the severity and incidence of seemingly unnecessary and costly mistakes leading to more efficient and effective product development. This paper examines the sources of shared knowledge problems across functional and product‐based groups. Using interviews, product development plans, and time‐sheet data, we look at the underlying factors behind two sources of knowledge sharing problems: (1) a serial product development process (i.e. little or no face‐to‐face communications) and (2) ineffective use of integrating mechanisms because of sticky knowledge. For each problem source, we find two key causal factors. We discuss the problems, their factors, and the implications for management and theory. 相似文献
28.
J. L. Bencze 《International Journal of Technology and Design Education》2001,11(3):273-298
The status quo for school science and technology is unacceptable. While the former often is required for admission to university engineering,
as well as to science programmes, the latter is deemed most appropriate for less able, concrete thinkers. This situation persists,
despite the fact school science tends to generate large groups of citizens who are relatively scientifically and technologically
illiterate, largely as a result of its preoccupation with identifying and training potential scientists and engineers. This
practice is tyrannical. It must be abandoned forthwith. A realistic alternative is a combined technology and science programme
– perhaps called 'technoscience' education – that would treat science and technology as equals. Such courses may, as well,
be more democratic in the sense that technological problem solving often is more natural to everyday situations that everyone
may find useful, not just future scientists or engineers. A framework for combined technology and science courses is described
and defended here. Originally developed through collaborative action research amongst practising teachers of science, the
approach appears to be feasible, under certain – perhaps ideal – conditions. A number of changes to science and technology
education may be necessary for broader implementation, not the least of which is a general retrenchment in expectations for
pre-determined learning, along with adjustments to teacher education. Nevertheless, the approach is recommended because of
its emphasis on: personalization, inclusion, problematization, explicitness, apprenticeship, authenticity, contextualization
and freedom.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
29.
The Private Finance Initiative (PFI) was launched by the United Kingdom Government in 1992 in order to encourage the private sector in the UK to become more involved in public sector development projects. A key theme of the initiative was that the public should receive 'value for money'. This article investigates the accounting issue as to whether or not the private or the public sector should record any property related to PFI projects on balance sheet. It argues that although both HM Treasury and the Accounting Standards Board (ASB) might agree on the accounting principles, the practical impact is that in order for related properties to stay off the public sector's balance sheet, substantial risk needs to be transferred to the private sector. As a consequence of this, the objective of providing value for money to the public may not be achieved. 相似文献
30.
Kenneth J. Arrow 《Review of International Economics》2004,12(2):207-212
The paper sets a broad agenda touching several areas of policy. It starts from the least likely policy at this point of time, the use of the tax system for redistribution. It discusses prudent macroeconomic coordination without the strings of the Maastricht Treaty in business troughs. Regulation of financial markets, agricultural policies, and health issues are coming up on a desirable agenda of the United States, but are probably important for all countries, as are social security policy and climate change. 相似文献