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  • 1
    ISSN: 1432-0827
    Keywords: Calcium channels ; Development ; Osteoblastic cells ; Fura-2 ; Patch-clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The present study evaluates differential occurrence of voltage-dependent calcium channels (VDCC) in the membranes of fetal (FROB) and neonatal (NROB) calvarian rat osteoblastic cells in primary culture. The intracellular calcium concentration ([Ca2+]i) was monitored upon depolarization of the cell membrane with the use of high K+ containing extracellular solutions. [Ca2+]i was measured in populations of cells as well as in individual cells using Fura-2, whereas the membrane potential (Em) was recorded in parallel experiments using patch-clamp techniques. Increasing the extracellular K+ concentration resulted in an instantaneous depolarization of Em of both FROB and NROB. This depolarization of Em did not significantly affect [Ca2+]i of populations of FROB and neonatal osteoblast precursors (NpROB). In contrast to FROB and NpROB, NROB populations responded to depolarization with significant transient [Ca2+]i increases that could be blocked by the calcium antagonist verapamil and were absent if extracellular Na+ was replaced for choline instead of K+. In individual cell measurements, response frequencies as well as the magnitude of [Ca2+]i responses upon depolarization of NROB were much higher than those of FROB, suggesting that more NROB than FROB possess VDCC. This phenomenon might point to a development-related expression of VDCC in the membranes of osteoblast-like cells.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 25 (1981), S. 119-125 
    ISSN: 1432-0630
    Keywords: 72.40 ; 85.30 ; 85.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An infinite stack ofp—n junctions with smoothly varying bandgap from ∞ to 0 is considered. AnI —V characteristic is derived, which is more correct than the classical exponential characteristic. It is shown that open-circuit operation is a reversible process and leads to the Carnot efficiency, if one defines the efficiency in the way that is usual in the theory of thermodynamic engines. If instead one uses the definition of efficiency usual in photovoltaics, open-circuit mode gives rise to zero efficiency. Then operation at maximum efficiency equals operation at maximum power and is not reversible.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of wildlife research 39 (1993), S. 224-232 
    ISSN: 1439-0574
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary After the disappearance of rabies after 1985 in the alpine county of Garmisch-Partenkirchen, Bavaria, the number of foxes shot has increased considerably though with local variations. In the heterogenous northern part of the county the greatest number of foxes were shot. Temporal and spatial differences in the fox hunting bag are not only a result of differences in the fox density, but also of the hunting pressure. In the hunting season 1991/1992 the number of foxes shot per km2 reached an all time high (0.86) for the county. However, the hunting pressure decreased this year as could be shown by a decrease in the yearly proportion of juvenile foxes in a sample of dead animals. The main fox hunting season in the county Garmisch-Partenkirchen is during the winter.
    Abstract: Résumé Après la disparition de la Rage silvatique en 1985, les tableaux de chasse du Renard ont fortement augmenté dans le district de Garmisch-Partenkirchen (Haute-Bavière). Ces tableaux (Figure 2) montrent cependant des variations locales (Figure 3). Les tableaux les plus élevés sont constatés dans la partie très structurée du Nord du district. Les différences observées ne résultent pas seulement des différences locales de la densité du Renard mais également de la pression de chasse plus ou moins grande. Au cours de l'année 1991–92, le nombre des renards tirés au km2 enregistre un record (0.86). Sur base de la part annuelle des sujets juvéniles au sein d'un échantillon du tableau, on a pu cependant constater que la pression de chasse s'était relâchée au cours de cette année. Dans ce district, le Renard est essentiellement chassé au cours de l'hiver, la chasse à l'affût étant le mode de chasse le plus communément pratiqué.
    Notes: Zusammenfassung Nach dem Verschwinden der Tollwut im Jahre 1985 hat im alpinen Landkreis Garmisch-Partenkirchen, Oberbayern, die Fuchsjagdstrecke stark zugenommen. Der Streckenverlauf (Abb. 2) zeigt jedoch lokale Unterschiede (Abb. 3). Die höchste Jagdstrecke wurde im strukturreichen Norden des Landkreises aufgefunden. Die festgestellten Unterschiede in der Jagdstrecke sind nicht nur eine Folge der lokalen Differenzen in der Fuchsdichte, sondern werden auch durch die Intensität der Fuchsbejagung mitbeeinflußt. Im Jagdjahr 1991/92 hat die Zahl der erlegten Füchse pro km2 eine Rekordhöhe (0,86) erreicht. Anhand des jährlichen Anteils von juvenilen Füchsen in einer Stichprobe toter Tiere konnte festgestellt werden, daß die Intensität der Bejagung des Fuchses in diesem Jagdjahr jedoch nachgelassen hat. Die Füchse werden in diesem Landkreis hauptsächlich in den Wintermonaten bejagt, wobei die Ansitzjagd die am meisten angewandte Jagdmethode ist.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of wildlife research 23 (1977), S. 113-126 
    ISSN: 1439-0574
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary The results obtained in this study appear to be useful from two points of view: firstly, to allow for a comparison between a heavily exploited population in West Germany and a lightly exploited population in Iran, and secondly, to obtain data on the ecology of wild boar under conditions little disturbed by man. A comparison between results obtained in German studies and in this study indicates the following: 1. There were far more adult animals in the park population because of a lower hunting pressure; 2. Average weights of both adults and yearlings in the park were higher than in West Germany; 3. Productivity in the park varies greatly from year to year, as in West Germany, and seems to be influenced mainly by the production of mast and winter weather conditions: i.e., a combination of a poor mast crop and heavy snow results in the lowest reproductive rate; 4. As a result of the considerable variation in productivity from year to year, the age structure of the population varies greatly accordingly. An evaluation of the possible effect of high winter concentrations of wild boar on a low reproduction of oak indicated that the cause is not the consumption of the acorns by wild boar, but rather the inadequate shade tolerance of the seedlings, i.e. oak does not reproduce well under its own overstorey.
    Abstract: Résumé Les résultats obtenus dans cette étude sont utiles d'un double point de vue: ils permettent d'une part des comparaisons entre une population ouest-allemande soumise à une forte pression de chasse et une population iranienne faiblement chassée; d'autrepart, ils livrent des données écologiques sur une population de sangliers soumise à des conditions peu influencées par l'homme. Une comparaison des résultats obtenus en Allemagne avec ceux recueillis dans cette étude permet d'avancer ce qui suit: 1. En raison de la faible pression de chasse, le nombre du sujets adultes était beaucoup plus élevé dans la population du parc national (P. N.); 2. le poids moyen des sujets adultes et des yearlings était plus élevé dans la population du P. N. qu'en Allemagne de l'Ouest; 3. la productivité variait fortement d'année en année, à l'instar de ce qui se passe en Allemagne fédérale, et semblait influencée par l'abondance des glandées et faînées de même que par les conditions atmosphériques régnant au cours de l'hiver, la productivité la plus faible résultant de l'action conjuguée d'une glandée et d'une faînée peu abondantes et d'un enneigement constituant une gêne pour les animaux; 4. en liaison avec la variation de productivité constatée d'année en année, l'aetilité de la population subit des fluctuations importantes. Une analyse des influences possibles sur une faible régénération du Chêne (Quercus castaneafolia) fait apparaître que la cause n'en serait pas tant le prélèvement des glands par le Sanglier mais la tolérance insuffisante des semis de glands à l'ombre, le Chêne se régénérant mal sous sa propre cîme.
    Notes: Zusammenfassung und Schlußfolgerung Die in dieser Studie gewonnenen Resultate sind aus zwei Blickrichtungen nützlich, einmal um Vergleiche zwischen einer stark bejagten Schwarzwildpopulation in Westdeutschland mit einer gering bejagten Population im Iran zu gewinnen und zweitens um Daten über die Ökologie des Schwarzwildes unter wenig vom Menschen beeinflußten Bedingungen zu erhalten. Ein Vergleich der in Deutschland gewonnenen Ergebnisse und denen dieser Studie läßt folgende Aussage zu: 1. Wegen des geringeren Jagddruckes waren in der Parkpopulation weit mehr erwachsene Stücke. 2. Das Durchschnittsgewicht von erwachsenen Stücken und Jährlingen lag in der Parkpopulation höher als in Westdeutschland. 3. Die Produktivität variierte in dem Nationalpark von Jahr zu Jahr stark, ähnlich wie in der Bundesrepublik Deutschland, und schien wesentlich von der Mastproduktion und der Winterwitterung beeinflußt zu sein, wobei die geringste Produktionsrate aus dem Zusammenwirken einer armen Mast mit belastenden Schneeverhältnissen resultiert. 4. Als ein Ergebnis der festgestellten Variation in der Produktivität von Jahr zu Jahr schwankt auch die Altersstruktur der Population entsprechend stark. Eine Auswertung des möglichen Einflusses einer hohen Winterkonzentration des Schwarzwildes auf eine geringere Produktion der Eiche (Quercus castanaefolia) läßt erkennen, daß nicht die Aufnahme der Eicheln durch Schwarzwild, sondern die unzureichende Schattenverträglichkeit der Eichensämlinge, d. h. daß die Eiche sich unter dem eigenen geschlossenen Kronendach schlecht regeneriert, als Ursache angenommen werden muß.
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  • 5
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary 1. Forty-nine clones and 25 families of white clover were tested in monoculture and in association with grass. The monoculture was mown only. The mixed cultivation was subdivided in a grazed part and a mown part. 2. Comparison of the families at the end of the second year after sowing showed rather low correlations for the characteristics area and density in monoculture and area in mixture. For height and type in monoculture and area in a mixture with grass correlations were even lower. The finer-leaved types of monoculture often performed better under mixture/grazing, but did not belong to the best. Under this kind of utilization the coarse Ladino types were frequently worse. They indeed often ranked among the worst. There was a very close relation between density and area in pasture. The correlation of area in mixture/mowing for the families of clover with area in monoculture was lower than the correlation between the same characteristic in mixture/grazing and monoculture. For the clones the correlation coefficients were lower than for the families. Among the characteristics themselves differences in correlations were found similar to those of the families. 3. For the best families in monoculture the correlation with growth in mixture is often higher than for the average of the other families. 4. In the second year after sowing the correlation between spread of clover in mixture/mowing and in mixture/grazing was very low. 5. Mass per area and density under monoculture in the year of sowing appeared to be moderately correlated with area under mixture/grazing in the second year after sowing as far as the families are concerned. For the best objects the correlation was higher. In a similar comparison area appeared to have much less significance than density. 6. Under grazing conditions the mother clones of the two best families showed the greatest number of surviving plants, indicating thus a clear inheritance of the competitive ability. 7. If breeding clover for cultivation with grass is intended, one must include clover/grass mixture in the selection scheme. Mixture/mowing and mixture/grazing require a rather great number of replications. Another disadvantage of testing under grazing is the need for cattle. On the other hand testing with a clover/grass association does not require so much weed control, which is a great advantage, ince weed control in a monoculture demands expensive labour.
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  • 6
    Electronic Resource
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    Springer
    Euphytica 24 (1975), S. 181-189 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of allopolyploid families from Lolium multiflorum x Festuca arundinacea were compared with varieties of the two parental species. They were investigated at different stages in a heated and an unheated greenhouse and in the field. Early seedling growth in the hybrid families in most cases, proved to be significantly better than in the two Festuca arundinacea standard varieties. One family of the hybrids performed well for height and yield under all conditions. The data indicate good possibilities for selection.
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  • 7
    Electronic Resource
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    Springer
    Euphytica 24 (1975), S. 743-749 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Meiotic doubling of the chromosome number of Festulolium hybrids was applied. Isolated, male-sterile tetraploid LpFa3 hybrids from the cross diploid Lolium perenne x hexaploid Festuca arundinacea, were open-pollinated by octoploid L2Fa6's. The percentage successful doubling (percentage of flowering tetraploid plants, which gave seedlings) x (percentage of these seedlings with the doubled number of chromosomes) was for 157 clones, in 1972, 45%; for 407 clones in 1974 it was considerably smaller, i.e. 7%. Data of our own experiments and experiments from the literature with meiotic and mitotic doubling of the chromosome number of LFa3 hybrids were compared. The percentage of successful meiotic doubling for three experiments was, on average, 38%. For germinated seeds and tillers mitotic doubling by colchicine treatment yielded, on average, 11% (three experiments) and 3% (four experiments), respectively. In addition to the fact that meiotic doubling, on average, gives better results than mitotic doubling, there are the advantage of an absence of mixoploid plants and the advantage of a perhaps greater heterozygosity. It is likely that application of meiotic doubling facilitates the production of fertile Festulolium hybrids and of other intergeneric or interspecific fertile hybrids in which meiotic doubling is possible.
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  • 8
    Electronic Resource
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    Springer
    Euphytica 39 (1988), S. 131-139 
    ISSN: 1573-5060
    Keywords: Phleum pratense L. ; timothy ; breeding ; hydroponics ; persistency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Twenty four populations of timothy (Phleum pratense L.) with varying persistency were grown on a nutrient flow system and in soil. Growth analyses showed that seedlings grew faster on nutrient solution than in soil but this was only temporary. After the fourth cutting, regrowth of plants in soil was faster than on hydroponics, probably because the optimal growth conditions and the relatively high temperatures in the nutrient solution led to a depleted storage carbohydrate pool, necessary for regrowth. Non-destructive growth analyses were carried out by monitoring the amount of acid needed to compensate for carbohydrate extrusion by the roots in exchange for nitrate uptake. It was assumed that regrowth was proportional to the NO3 - incorporated in the plants. The calculated growth efficiency on hydroponics, averaged over all populations, ranged between 4.4 and 5.4 gram dry matter per megajoule photosynthetic radiation absorbed. The populations responded significantly differently to a frequent cutting regime. As a function of harvest number, the competitive ability of some populations decreased compared with the mean of all populations, while that of others increased or remained stable. The coefficients of genetic variation for shoot regrowth ranged between 0.16–0.22 for different harvests. For root regrowth and tillering the coefficients of genetic variation were even higher: 0.21–0.25 for the roots and 0.18–0.35 for the tiller number. Dry matter production was closely correlated with tiller formation (r=0.95). The application of nitrogen to the nutrient solution was controlled by a simple computer model, which was based on the incoming radiation and which calculated momentaneous growth of the plants on a minutes time base. Thus an equilibrium between nitrogen application and the demand of the plants was maintained. During the last regrowth period, the nitrogen supply was limited to 30% of the optimal addition rate. The production of different populations under limited supply (sixth harvest) was closely correlated with that under optimal supply (fifth harvest), (r=0.7).
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  • 9
    Electronic Resource
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    Environmental monitoring and assessment 34 (1995), S. 73-102 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A base line study into the environmental quality of soils in the rural areas of the province of Zeeland, the Netherlands, was performed. The polder-landscape in this area was developed in a complex history of floodings and land-reclamation. Samples from 67 sites, at a density of roughly one per 25 km2, were analyzed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in addition to a physicochemical characterization by pH(KCl), dry solids, organic matter, and clay content. At about 2/3 of the sites samples were taken at more than one depth. Fluoride and pesticides were determined in partly overlapping selections of 30 samples. Four land use classes were distinguished (arable land, grass land, orchards, uncultivated), and samples were labelled by region within the province. Data evaluation was aided by a recursive statistical approach, whereby statistical tests confirm and strengthen geochemical reasoning. Single- and multivariate statistics were used both as exploratory tools and as a measure of significance and relevance of conditions and processes. In general the environmental quality of the soils is satisfactory. Exceedence of the legal standards for natural background values at more than one site occurs for Cd, Cu, Hg and the pesticides DDT/DDE, dieldrin and HCH, at most by a factor of three. High levels of Hg appear related to arable land use; enhanced levels of Cu are found in orchards. High Cd levels primarily seem to follow a regional or geological pattern; yet, a relation with arable land use and clayey soils cannot be excluded. Pesticides are not detected in grass land, incidence is highest in orchards as well as in uncultivated areas. DDT levels appear to be generally inherited from the past. Variation in soil type as described by the macro physico-chemical characteristics is essential in explaining the variation in concentration level of the potential contaminants. Variations with depth also appear largely related to concurrent variation in soil properties. For As redox conditions and hydrological regime seem of importance, in addition to the geologic history. The influence of atmospheric input is inferred for Pb. The available data do not fully resolve the causes for the regional pattern that remains when the influences of soil type, geology, and land use have been taken into account. In addition to current concentration levels, the base line study offers general insight as to what degree variations in potential contaminants are of natural or anthropogenic origin. A succession of similar studies at suitable time intervals, each with a new selection of sampling sites, may constitute an evolving, flexible monitoring system. When putting up a monitoring system, authorities should weigh the advantages and disadvantages of a network composed of fixed sites against this alternative.
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  • 10
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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