Feynman's path-integral approach for intense-laser-atom interactions

Atoms interacting with intense laser fields can emit electrons and photons of very high energies. An intuitive and quantitative explanation of these highly nonlinear processes can be found in terms of a generalization of classical Newtonian particle trajectories, the so-called quantum orbits. Very few quantum orbits are necessary to reproduce the experimental results. These orbits are clearly identified, thus opening the way for an efficient control as well as previously unknown applications of these processes.     

DNA synthesis in spinal ganglia of rabbit after Herpes suis infection. Findings obtained by electron microscopy and autoradiography]

The mulitplication of herpes suis virus in neurons, amphicytes, gliocytes, as well as Schwann's and endothelial cells of the spinal ganglion of rabbit was traced by electron microscopy and autoradiography, using tritium-labelled thymidine. Marking of nuclear zone margin, quite common when it comes to ganglion cells, was observed also in the context of mesenchymal cells beyond expectation on the basis of light microscopy, but in the case under review it had no direct relationship with virus synthesis. Repeated markings were recorded from the nucleoli of apparently unchanged ganglion cells which suggested the suitability of the technique for early detection of infectious attack on intact cells. Exogenous 3H-thymidine was supplied three hours and absorbed with specificity by the DNA-forming centres of the nuclei, but the growing virus drew into itself additional cellular or inactive thymidine. The method proved to be highly significant, as in comparison to the nuclear environment there were ten times as many lemnici in the DNA production centres of neurons and Schwann's cells and about six times as many in the amphicytes and gliocytes. Now, there is definite justification in rejecting as unfounded all doubt expressed repeatedly and more recently in the specificity of herpes-dependent intranuclear inclusions.     

Long-term dynamics of leaf and root decomposition and nitrogen release in a grey alder (Alnus incana (L.) Moench) and silver birch (Betula pendula Roth.) stands

The decomposition of the leaf litter, fine roots (d?<?2?mm) and coarser roots (2?≤?d?<?5?mm) of grey alder and silver birch, as well as of α-cellulose sheets using the litterbag method was studied in two experimental stands on Podzoluvisol soils in Southern Estonia. For both tree species, the coarser roots decomposed faster than the fine roots, (p?<?.05), tree species did not affect the decomposition rate of the roots (p?>?.5). The nitrogen (N) input to soil from aboveground litter was multiple times higher than the N flux from roots. The remaining relative ash-free mass of the leaves of grey alder and silver birch after three and a half years was similar. After 11 years the remaining relative ash-free mass of the fine and coarser roots of grey alder still accounted for around 10% of the initial value. For silver birch the remaining value was around 20% after 9 years. The litterbag method to underestimates in fertile soils the decomposition of organic matter and thus did not reflect the actual dynamics of decomposition.     

Genetic engineering of cereal crop plants: a review

Summary Many aspects of basic and applied problems in plant biology can be investigated by transformation techniques. In dicotyledonous species, the ability to generate transgenic plants provides the tools for an understanding of plant gene function and regulation as well as for the directed transfer of genes of agronomic interest.For many dicotyledonous plants Agrobacterium tumefaciens can be routinely used to introduce foreign DNA into their genome. However, cereals seem to be recalcitrant to Agrobacterium-mediated transformation.In cereals, many efforts have been made in recent years to establish reliable transformation techniques. Several transformation techniques have been developed but to date only three methods have been found to be suitable for obtaining transgenic cereals: transformation of totipotent protoplasts, particle bombardment of regenerable tissues and, more recently, tissue electroporation. The current state of transformation methods used for cereals will be reviewed.     

Survival of plant pathogens in static piles of ground green waste

Ground green waste is used as mulch in ornamental landscapes and for tree crops such as avocados. Survival of Armillaria mellea, Phytophthora cinnamomi, Sclerotinia sclerotiorum, and Tylenchulus semipenetrans was assessed for 8 weeks within unturned piles of either recently ground or partially composted green waste. S. sclerotiorum survived at the pile surface and at 10, 30, and 100 cm within the pile for the entire 8 weeks in both fresh green waste (FGW) and aged green waste (AGW). A. mellea and T. semipenetrans did not survive more than 2 days in FGW, while P. cinnamomi persisted for over 21 days in FGW. AGW was less effective in reducing pathogen viability than FGW, most likely because temperatures in AGW peaked at 45 degrees C compared with 70 degrees C in FGW. Survival modeling curves based on pile temperatures indicate the time to inactivate 10 propagules of pathogens was 11, 30, 363, and 50 days for A. mellea, P. cinnamomi, S. sclerotiorum, and T. semipenetrans, respectively. Sclerotia-forming pathogens pose the greatest risk for escape; to ensure eradication of persistent fungi, green waste stockpiles should be turned intermittently to mix pile contents and move pathogen propagules to a location within the pile where they are more likely to be killed by heat, microbial attack, or chemical degradation.     

Die Natürliche Ernährung des Menschen im Verlauf der Evolution

Results of prehistoric research back to the origin of mammalians may lead to the highly plausible conclusion that all ancestors of human beings were omnivorous. According to the only low specialisation of man (in body's characteristics) during the progress of evolution there were no changes observed later on. Hypothese about man's descent from carnivorous ancestors are therefore improbable. However, vegetarianism could not supported in man's history of evolution on the other hand. The expectation of a very long life of modern civilized beings—compared with those in former ages—absolutely requires a nutrition of full value in all respects. Such a nutrition must not only be based on the nature and on a peculiar instinct absent in man but mainly on the experiences of nutritional science. Therefore, Quality Research in food plants on a nutritional scale is of great importance.     

Physiological influences on wood-destroying insects of wood compounds and substances produced by microorganisms

Summary Wood-destroying insects react to and depend regarding their nutrition on compounds contained in wood or produced by microorganisms in wood. This relation is a complex matter in the biology of the insects and the chemistry of wood and of the metabolism of woodinhabiting microorganisms. Results on the reaction of Coleoptera and Isoptera to attractive or repellent compounds in wood species or substances produced by fungi in wood are reviewed with emphasis to differences among various insect species. Nutrition of wood-destroying insects depends on nitrogen compounds of the wood; the content of nitrogen can be increased by the presence of fungi. Existing results on the relation between microorganisms and insects are also summarized including toxicity or parasitic influence of part of the microorganisms on insects. The survey may stimulate further investigations which are necessary for better knowledge of the complex interrelations.Prepared for the Convention of the International Academy of Wood Science at Raleigh (S.-Carol., USA) in March 1971.     

Effect of transpiration on iron uptake and translocation in lowland rice

We evaluated six lowland rice (Oryza sativa L.) genotypes with contrasting responses to increasing Fe²⁺ concentrations under conditions of both low (0.3 kPa) and high (2.4 kPa) vapor pressure deficit. Dry atmospheric conditions generally enhanced transpiration with concomitant increases in Fe uptake and leaf bronzing. Some resistant genotypes were able to limit the water loss by transpiration under higher Fe concentrations thus attenuating negative effects associated with increased Fe²⁺ translocation at high vapor pressure deficit.