The international decade for natural disaster reduction (IDNDR): A challenge to science

The United Nations proclaimed the 1990s as the International Decade for Natural Disaster Reduction (IDNDR). Based on the ‘Tokyo Declaration’—an action plan for the IDNDR formulated by a commission of highly recognized experts—a program was drafted in March 1991 by the International Scientific and Technical Committee for the IDNDR, whose members were appointed by the Secretary General of the United Nations. Based on this international draft program a framework for national scientific programs should be developed by National Committees. The Decade and its translation into actions are briefly reviewed.     

The effect of biodegradation on steranes and terpanes in crude oils

Steranes and terpanes biodegrade at a slower rate than isoprenoids and survive moderate biodegradation. Heavy biodegradation results in destruction of regular steranes, survival of diasteranes (20R better than 20S) and tricyclic terpanes and transformation of hopanes to Ring A/B demethylated hopanes. These survivors can be used as source fingerprints in biodegraded crudes. The structure of predominant steranes in undegraded to moderately degraded fossil fuels was proven to be 14β, 17β(H) (20R + S) by molecular spectroscopy. These compounds plus the 20S epimers of regular 5α-steranes (20R) were identified as major constituents and their 5β-counterparts as minor components in a cholestane isomerizate (300°C, Pt on C), allowing assessment of relative thermodynamic stabilities. An observed increase of optical activity in heavily degraded crudes from three different basins is interpreted to be the result of bacterial transformation of terpanes and steranes to new optically active species plus enrichment of the latter by n + isoparaffin depletion rather than total bacterial synthesis. Diagnostic ion profiling by GC-MS-C is a convenient tool for surveying the relative abundance of individual diasteranes and regular steranes plus distinguishing epimeric and ring skeletal isomeric series in complex fossil fuel mixtures. A new practical method of determining the absolute quantities of individual steranes by spiking with 5β-cholane and integration of mass chromatograms is described.     

High-frequency radar observations of sea waves travelling in opposition to the wind

High-frequency (HF) radar observations of sea waves apparently travelling against the wind are discussed. In some cases, it appears that the wave angular spectrum does contain components travelling against the wind. Some data taken on the Barbados Island during BOMEX have been analyzed, and they show that such components increase in amplitude with distance from a windward shore. It is shown that the order of magnitude of the observed growth rates can be explained by resonant non-linear interaction within the wave spectrum.     

Einfluss korrelativer Abhängigkeiten auf simulierte Zeitreihen: Empfindlichkeit des Fiering-Modells gegenüber Veränderungen der Korrelationsstruktur

The simulation of time series is based on estimated statistical parameters of the empirical time series. The Fiering Model generating monthly sums of streamflows is used as an example for the simulation in order to account for the error of the model, theoretically and practically, caused by statistically inprecise parameter estimation. The sensitivity of this model, especially to the correlation coefficients, is analyzed by means of systematic variations of the correlation coefficients, since these are most affected by the error of estimation. No significant dependency could be found comparing the empirical and simulated parameters mean, standard deviation, and skewness. From this follows, that the importance of the correlation coefficients in the Fiering Model is generally overestimated. The results are given for monthly sums of streamflows at four stations with different hydrological characteristics.