Proposal of a New Parameter for the Weathering Characterization of Carbonate Flysch-Like Rock Masses: The Potential Degradation Index (PDI)

The susceptibility of clay bearing rocks to weathering (erosion and/or differential degradation) is known to influence the stability of heterogeneous slopes. However, not all of these rocks show the same behaviour, as there are considerable differences in the speed and type of weathering observed. As such, it is very important to establish relationships between behaviour quantified in a laboratory environment with that observed in the field. The slake durability test is the laboratory test most commonly used to evaluate the relationship between slaking behaviour and rock durability. However, it has a number of disadvantages; it does not account for changes in shape and size in fragments retained in the 2 mm sieve, nor does its most commonly used index (Id2) accurately reflect weathering behaviour observed in the field. The main aim of this paper is to propose a simple methodology for characterizing the weathering behaviour of carbonate lithologies that outcrop in heterogeneous rock masses (such as Flysch slopes), for use by practitioners. To this end, the Potential Degradation Index (PDI) is proposed. This is calculated using the fragment size distribution curves taken from material retained in the drum after each cycle of the slake durability test. The number of slaking cycles has also been increased to five. Through laboratory testing of 117 samples of carbonate rocks, extracted from strata in selected slopes, 6 different rock types were established based on their slaking behaviour, and corresponding to the different weathering behaviours observed in the field.

The Penetration of Financial Instability in Agricultural Credit and Leveraging. Factor Markets Working Paper No. 2, September 2011

This paper describes the aggregate rural capital markets of the EU and the main differences between the markets of its member countries. The results of our study suggest that the agricultural credit markets are still quite segmented and the segments are country- rather than currency- or region specific. Financial instability in Europe is also penetrating the agricultural sector and the variation of interest rates for agricultural credit is increasing across countries. Perhaps the most dramatic signal of growing financial instability is that the financial leverage (gearing rate) of European farms rose in 2008 by almost 4 percentage points, from 14 to 18%. The 4 percentage-point annual rise was twice the 2 percentage-point rise observed during the economic recession in the late 1980s and early 1990s. The distribution of the financial leverage of agriculture across countries does not, however, reflect the distribution of country-specific risk premiums in the manner that they are observed in government bond yields. Therefore, in those countries that have the weakest financial situation in the public sector and in which the bond markets are encumbered with high country-specific risk premiums, the agricultural sector is not directly exposed to a very large risk of increasing interest rates, since it is not so highly leveraged. For example in Greek and Spanish agriculture, the financial leverage (gearing) rate is only 0.6% and 2.2% respectively, while the highest gearing rates are found elsewhere (in Denmark), reaching 50%.

Kazakhstan: the regional success story; Tajikistan: a trial period; Uzbekistan: the major source of instability in Central Asia? OSW Study 15/2004

Kazakhstan: Kazakhstan can boast economic development like no other country in Central Asia. In contrast to other countries of the region, which have rich natural resources, Kazakhstan has managed to use its economic potential in a way that yields concrete benefits now and, at the same time, creates prospects for further sustainable economic growth. Tajikistan: Tajikistan in its present state has been built on the civil war experiences and provisions of the peace accords signed in 1997. These have had a great impact on the present form of the state, its political scene and power mechanisms. President Emomali Rakhmonov is the central figure in the state. The political system, which he has cocreated, is based on - unique in this region - political pluralism (the existence of the Islamic party), decentralisation (far-going independence of the regions and relatively limited potential of the central structures) and compromise as the basic way of resolving conflicts. Such a system has so far guaranteed stabilisation and normalisation of the country. Uzbekistan: With its geographic location, potential, ambitions and political priorities, Uzbekistan could play a leading role in Central Asia. The international community has perceived the country as the pillar of stability in the region. This perception was further reinforced after 11th September 2001 and was certainly among the factors that inspired the United States to start closer political and military cooperation with Tashkent. The administration in Washington had expected that closer contacts might galvanise political, economic and social change in Uzbekistan, thus reinforcing positive trends in other countries of the region as well. But the relations between Washington and Tashkent are in crisis (which the United States will certainly try to overcome), and we have seen rapprochement between Uzbekistan and Russia and China.

Strain-induced structural instability in FeRh

We perform density functional calculations to investigate the structure of the intermetallic alloy FeRh under epitaxial strain. Bulk FeRh exhibits a metamagnetic transition from a low-temperature antiferromagnetic (AFM) phase to a ferromagnetic phase at 350 K, and its strain dependence is of interest for tuning the transition temperature to the room-temperature operating conditions of typical memory devices. We find an unusually strong dependence of the structural energetics on the choice of exchange-correlation functional, with the usual local density approximation yielding the wrong ground-state structure, and generalized gradient (GGA) extensions being in better agreement with the bulk experimental structure. Using the GGA we show the existence of a metastable face-centered-cubic-like AFM structure that is reached from the ground-state body-centered-cubic-like AFM structure by following the epitaxial Bain path. We show that the behavior is well described using nonlinear elasticity theory, which captures the softening and eventual sign change of the orthorhombic shear modulus under compressive strain, consistent with this structural instability. Finally, we predict the existence of an additional unit-cell-doubling lattice instability, which should be observable at low temperature.

Bulk sediment parameter of surface sediment samples (Table 3)

Comparison of rates of accumulation of organic carbon in surface marine sediments from the central North Pacific, the continental margins off northwest Africa, northwest and southwest America, the Argentine Basin, and the western Baltic Sea with primary production rates suggests that the fraction of primary produced organic carbon preserved in the sediments is universally related to the bulk sedimentation rate. Accordingly, less than 0.01% of the primary production becomes fossilized in slowly accumulating pelagic sediments [(2 to 6 mm (1000 y)**-1] of the Central Pacific, 0.1 to 2% in moderately rapidly accumulating [2 to 13 cm (1000 y)**-1] hemipelagic sediments off northwest Africa, northwest America (Oregon) and southeast America (Argentina), and 11 to 18% in rapidly accumulating [66 to 140 cm (1000 y)**-1] hemipelagic sediments off southwest America (Peru) and in the Baltic Sea. The emiprical expression: %Org-C = (0.0030*R*S**0.30)/(ps(1-Theta)) implies that the sedimentary organic carbon content (% Org-C) doubles with each 10-fold increase in sedimentation rate (S), assuming that other factors remain constant; i.e., primary production (R), porosity and sediment density (ps). This expression also predicts the sedimentary organic carbon content from the primary production rate, sedimentation rate, dry density of solids, and their porosity; it may be used to estimate paleoproductivity as well. Applying this relationship to a sediment core from the continental rise off northwest Africa (Spanish Sahara) suggests that productivity there during interglacial oxygen isotope stages 1 and 5 was about the same as today but was higher by a factor of 2 to 3 during glacial stages 2, 3, and 6.

Statistical grain size parameter of surface samples from Kiel Bay

Geological observations, using "free-diving" techniques (Figure I) were made in September, 1960 and March 1961 along two continuous profiles in the outer Kiel Harbor, Germany and at several other spot locations in the Western Baltic Sea. A distinct terrace, cut in Pleistocene glacial till, was found that was covered with varying amounts and types of recent deposits. Hand samples were taken of the sea-floor sediments and grainsize distribution determined for both the sediment as a whole and for its heavy mineral fraction. From the Laboratory and Field observations it was possible to recognize two distinct types of sand; Type I, Sand resulting from transportation over a long period of time and distance and Type 11, Sand resulting from little transportation and found today near to xvhere it was formed. Several criterea related to the agent of movement could be used to classify the nature of the sediment; (1) undisturbed (the sediment Cover of the Pleistocene Terrace is essentially undisturbed), (2) mixed by organisms, (3) transported by water movements (sediment found with ripple marks, etc., and (4) "Scoured" (the movement of individual particles of sediment from around larger boulders causes a slow downward movement or "Creeping" which is due to both the force of gravity and bottom currents. These observations and laboratory studies are discussed concerning their relationship to the formation of residual sediments, the direction of sand transportation, and the intensive erosion on the outer edge of the wave-cut platform found in this part of the Baltic Sea.