18,957 research outputs found
CAVIAR: Climate variability of the Baltic Sea area and the response of the general circulation of the Baltic Sea to climate variability
The warming trend for the entire globe (1850-2005) is 0.04°C per decade. A specific warming period started around 1980 and continues at least until 2005, with a temperature increase of about 0.17°C per decade. This trend is equally well evident for many areas on the globe, especially on the northern hemisphere in observations and climate simulations. For the Baltic Sea catchment, which lies between maritime temperate and continental sub-Arctic climate zones, an even stronger warming of about 0.4°C per decade appeared since 1980. The annual mean air temperature increased by about 1°C until 2004. A similar warming trend could be observed for the sea surface temperature of the Baltic Sea. Even the annual mean water temperatures averaged spatially and vertically for the deep basins of the
Baltic Sea show similar trends. We provide a detailed analysis of the climate variability and associated
changes in the Baltic Sea catchment area as well as in the Baltic Sea itself for the period 1958-2009, in which the recent acceleration of the climate warming happened. Changes in the atmospheric conditions causes corresponding changes in the Baltic Sea, not only for temperature and salinity but also for currents and circulation. These changes in the physical conditions have strong impact on the
marine ecosystem structure and processes
In situ mineralogical-chemical analysis of Martian materials at landing/roving sites by active and passive remote sensing methods
Remote sensing of the Martian surface from the ground and from orbiting spacecraft has provided some first-order insight into the mineralogical-chemical composition and the weathering state of Martian surface materials. Much more detailed information can be gathered from performing such measurements in situ at the landing sites or from a rover in combination with analogous measurements from orbit. Measurements in the wavelength range of approximately 0.3 to 12.0 micrometers appear to be suitable to characterize much of the physical, mineralogical, petrological, and chemical properties of Martian surface materials and the weathering and other alteration processes that have acted on them. It is of particular importance to carry out measurements at the same time over a broad wavelength range since the reflectance signatures are caused by different effects and hence give different and complementing information. It appears particularly useful to employ a combination of active and passive methods because the use of active laser spectroscopy allows the obtaining of specific information on thermal infrared reflectance of surface materials. It seems to be evident that a spectrometric survey of Martian materials has to be focused on the analysis of altered and fresh mafic materials and rocks, water-bearing silicates, and possibly carbonates
Die eerste sendeling as plaaslike hoofmanne in Hereroland*
Slegs terloops vermeld dr. H. Vedder in sy w erk : „D a s alte Südwest-Afrika” (Berlyn, 1934, bl. 230) die feit d a t die welbekende Rynse sendeling C. Hugo Hahn, wat saam met sy mede-sendeling Johannes Kleinschmidt die eerste sendingstasies in Hereroland gestig het, self deur ’n erkende Hererohoofman, Kahitjene, as hoofman van die plek Barmen, waar hy ’n sendingstasie gestig het, beskou is
The genetical theory of social behaviour.
We survey the population genetic basis of social evolution, using a logically consistent set of arguments to cover a wide range of biological scenarios. We start by reconsidering Hamilton's (Hamilton 1964 J. Theoret. Biol. 7, 1-16 (doi:10.1016/0022-5193(64)90038-4)) results for selection on a social trait under the assumptions of additive gene action, weak selection and constant environment and demography. This yields a prediction for the direction of allele frequency change in terms of phenotypic costs and benefits and genealogical concepts of relatedness, which holds for any frequency of the trait in the population, and provides the foundation for further developments and extensions. We then allow for any type of gene interaction within and between individuals, strong selection and fluctuating environments and demography, which may depend on the evolving trait itself. We reach three conclusions pertaining to selection on social behaviours under broad conditions. (i) Selection can be understood by focusing on a one-generation change in mean allele frequency, a computation which underpins the utility of reproductive value weights; (ii) in large populations under the assumptions of additive gene action and weak selection, this change is of constant sign for any allele frequency and is predicted by a phenotypic selection gradient; (iii) under the assumptions of trait substitution sequences, such phenotypic selection gradients suffice to characterize long-term multi-dimensional stochastic evolution, with almost no knowledge about the genetic details underlying the coevolving traits. Having such simple results about the effect of selection regardless of population structure and type of social interactions can help to delineate the common features of distinct biological processes. Finally, we clarify some persistent divergences within social evolution theory, with respect to exactness, synergies, maximization, dynamic sufficiency and the role of genetic arguments
Coulomb blockade effects in driven electron transport
We study numerically the influence of strong Coulomb repulsion on the current
through molecular wires that are driven by external electromagnetic fields. The
molecule is described by a tight-binding model whose first and last site is
coupled to a respective lead. The leads are eliminated within a perturbation
theory yielding a master equation for the wire. The decomposition into a
Floquet basis enables an efficient treatment of the driving field. For the
electronic excitations in bridged molecular wires, we find that strong Coulomb
repulsion significantly sharpens resonance peaks which broaden again with
increasing temperature. By contrast, Coulomb blockade has only a small
influence on effects like non-adiabatic electron pumping and coherent current
suppression.Comment: 9 pages, 7 figures. Added a plot for temperature dependence of
resonance peaks. Published versio
Letter From the Editor
Welcome to the third issue of The Richmond Journal of Law and Technology\u27s seventh publication term! The 2000-2001 academic year has proved to be one of the most productive and exciting in the Journal\u27s decorated history. Our Editorial Board and staff have done a phenomenal job on the Journal\u27s seventh volume and we are very proud of the issue we have worked to prepare for you today
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