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41.
The paper summarises the history of human settlement in the Sudetes from the Bronze Age. A more intensive stage was reached
in the Middle Ages when settlers from the west established new villages deep in the mountain valleys. By the beginning of
the 20th century the Sudetes were already overpopulated but after a near-complete ethnic replacement from a German to a Polish
population in 1945–8, population continued to grow until the 1980s. However, the economic system was hardly sustainable by
this time. There were many polluting industries in the region and massive transboundary pollution from adjacent areas of Czechoslovakia
and Germany had a devastating effect on the forests. Moreover, subsidised state agriculture placed heavy pressure on vulnerable
mountain grazings. Since 1989 there has been a process of deindustrialisation in the Sudetes and surrounding areas and, with
the disappearance of the state farms and the reduction in subsidies, agriculture is now better adjusted to the natural potential
and is complemented by a promising start with agrotourism. The population of the region is growing relatively slowly (0.8%
per annum 1956–1999), with the rural areas now in decline. A sustainable future for the region is now a possibility, but while
there is a consensus for continued environmental reconstruction, supported by alternative economies, this will have to be
carefully managed in the years ahead when EU accession may bring heavier development pressures than those evident at the moment.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
42.
Piotr Owczarek Adam Nawrot Krzysztof Migała Ireneusz Malik Bartosz Korabiewski 《Boreas: An International Journal of Quaternary Research》2014,43(2):384-402
Changes in the supply of water and sediment to high‐latitude rivers related to contemporary climate change and glacier fluctuations largely determine the activity of fluvial processes. This study reconstructs fluvial dynamics since the end of the Little Ice Age (LIA) in two small, partially glaciated basins in the southern part of Spitsbergen, Svalbard Archipelago. We use a combination of aerial photograph interpretation, field mapping and dendrochronological analysis. Sequences of abandoned channels and glacifluvial terraces are distinctly visible in middle and lower parts of the Brattegg and Arie basins in this area. The advance of glaciers during the LIA in the upper part of the basins led to the development of a braiding pattern and to channel aggradation corresponding to the highest glacifluvial levels. The decreasing activity of these braidplains occurred at the turn of the 19th and 20th centuries, immediately prior to a significant incision period. A second generation of braided channels developed during the first half of the 20th century. Ice‐marginal lake development, less input of fine‐grained sediment to the river channel, and fast incision began from the second half of the 20th century onward. During the last two decades, the main fluvial response to the climatic warming has been contraction of flow within a narrower channel and the abandonment of braidplains. The increased lateral erosion and rate of downcutting and the formation of the most downstream reaches of the modern valley bottom occurred in the 1980s and 1990s. This process was intensified under flood conditions generated by extreme rainfall events. These micro‐scale (small partially glaciated basins) observations concerning the changes of the activity of fluvial processes since the end of LIA may be helpful for the reconstruction of past fluvial changes over longer time scales. 相似文献
43.
Krzysztof Rochowicz 《Astrophysics and Space Science》1996,238(1):71-74
Ultraviolet spectra of population I WR stars obtained from IUE archive are used to determine fundamental stellar parameters. Terminal velocities for 85 galactic and LMC Wolf-Rayet stars were obtained by means of the empirical relation between spectral quantities easily measured in low resolution and high-resolution terminal velocity measurements. Temperatures and so-called transformed radii were derived based on available contour plots of spectral characteristics for a grid of NLTE models. The effect of the reddening law on stellar far ultraviolet continua is emphasized and the revised extinction curve towards WR stars is used for dereddening. For the sample of stars attributed to open clusters or associations we construct the stellar distance scale and adopt it for the other WR stars. The remaining fundamental parameters are derived and HR diagram for population I WR stars is presented. 相似文献
44.
45.
Krzysztof Stasiewicz 《Planetary and Space Science》1984,32(3):379-389
On the basis of quasi-linear theory of ion-acoustic turbulence it is shown that the angular and energy distribution of the electron spectra observed in quasi-static inverted-V structures are natural products of electron heating and runaway processes occuring in a region of current-driven turbulence located at h ≈ 1 Re. The power law population J ∞ E?γ, with γ ≈ 1 observed in the energy range ~ 25–1000 eV, is interpreted as a quasi-stationary distribution of suprathermal electrons interacting resonantly with the ion sound waves. This spectrum is generated in the turbulent region and convectively transported earthward along the magnetic field lines. Field-aligned intense electron fluxes with collimation angle < 10° are explained as due to particles escaping from the turbulent region through the runaway cone—a characteristic feature of velocity-space in ion-acoustic turbulence. A complete, new interpretation of the observed electron spectra is given on the basis of the proposed physical acceleration mechanism along with many other implications of this theory. 相似文献
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47.
The microphysical model with the bulk water parameterization is applied to simulated both contact and deposition nucleation as well as the imersion freezing for unseeded cases and the cases immediately after seeding performed for the cold continental Cb clouds with small cloud droplets. The injection of agent AgI is performed in temperature region between –8°C and –12°C. The four groups of sensitivity experiments are executed.
With 14 Figures 相似文献
| a. | The Brownian coagulation of rain drops is the most important contact nucleation mechanism for seeded cases with great amount of rain drops. When cloud droplets mainly contribute to the liquid water content for seeded cases, the Brownian coagulation of cloud droplets is the primary nucleation mechanism while the inertial impact is the less effective contact nucleation mechanism; |
| b. | the mutual interdependence of contact and deposition nucleation mechanisms shows that the contact nucleation is more effective for graupel production than the deposition one for the temperature region considered in this model; |
| c. | the imersion freezing is the most important mechanism for all cases with significant amount of rain drops. It is more effective than the contact nucleation mechanism in unseeded cases with insufficient number of rain drops; |
| d. | the nucleation mechanisms are more sensitive to temperature changes than to pressure changes. |
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