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  • Springer  (55)
  • 1995-1999  (50)
  • 1960-1964  (5)
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    The chemical educator 3 (1998), S. 1-13 
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Because the conceptual basis of the curriculum is that the majority of the students are not chemists, participants in this session examined which aspects of organic chemistry are really necessary for a nonchemical (mostly biological) audience. Participants learned about Juniata’s solution to this curriculum problem and considered whether any of the ideas are useful in other settings. An important consideration is whether the curriculum is indivisible or whether certain parts can be adopted without others. Particular examples from the Juniata curriculum were described.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 106 (1996), S. 192-198 
    ISSN: 1432-1939
    Keywords: Pollination limitation ; Selection potential ; Seed dispersal ; Microsite limitation ; Fruit production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Will increased fruit and seed production in a severely pollination-limited orchid stimulate population growth? We tested whether safe sites for germination and seedling establishment are limiting for the twig epiphyte, Tolumnia variegata, by manipulating fruit set and monitoring subsequent seedling establishment for two seasons (1991–1992, 1992–1993). In the Cambalache Forest Reserve of Puerto Rico, we established 36 plots along a transect. Each plot consisted of nine trees. A center tree was designated as the site for attaching Tolumnia and manipulating fruit set. The other eight potential host trees were 1–3 and 3–5 m from the center tree in each of the cardinal directions. A 1-m length of stem 1 m from the ground was monitored for recruits on each of the nine trees of 24 fruit-enhanced plots and 12 controls (23 and 13, respectively for the 1992–1993 season). Fruit enhancement plots were divided among two treatments: one-fruit and five-fruit additions for the 1st year and one to five and more than five fruits for the 2nd year. Availability of suitable host species was not limiting. T. variegata showed little specificity for host tree species, good host trees and shrubs were common, and there was no evidence that the orchid had a preference for small branches, despite possessing the entire suite of characteristics thought to respresent “obligate” twig epiphytes. Fruit enhancement increased seed rain and seedling establishment consistently in only the high-fruit treatment plots. Most recruitment occurred near fruiting plants. Over the 2-year period, mortality was 18% for adults and 85.5% for the 1991–1992 cohort of recruits. Net recruitment was positive for both the treatment (average = 1.74) and control plots (average = 0.67). Seedling establishment at our study site was not microsite-limited. If selection for increased pollinator attraction occurs, then an increase in seed output should result in population growth.
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  • 13
    ISSN: 1432-1939
    Keywords: Eelgrass ; Grazing ; Productivity ; Limpets ; Trophic interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unusual appearance of a commensal eelgrass limpet [Tectura depicta (Berry)] from southern California at high density (up to 10 shoot−1) has coincided with the catastrophic decline of a subtidal Zostera marina L. meadow in Monterey Bay, California. Some commensal limpets graze the chloroplast-rich epidermis of eelgrass leaves, but were not known to affect seagrass growth or productivity. We evaluated the effect on eelgrass productivity of grazing by limpets maintained at natural densities (8±2 shoot−1) in a natural light mesocosm for 45 days. Growth rates, carbon reserves, root proliferation and net photosynthesis of grazed plants were 50–80% below those of ungrazed plants, but biomass-specific respiration was unaffected. The daily period of irradiance-saturated photosynthesis (H sat) needed to maintain positive carbon balance in grazed plants approached 13.5 h, compared with 5–6 h for ungrazed plants. The amount of carbon allocated to roots of ungrazed plants was 800% higher than for grazed plants. By grazing the chlorophyll-rich epidermis, T. depicta induced carbon limitation in eelgrass growing in an other-wise light-replete environment. Continued northward movement of T. depicta, may have significant impacts on eelgrass production and population dynamics in the northeast Pacific, even thought this limpet consumes very little plant biomass. This interaction is a dramatic example of top-down control (grazing/predation) of eelgrass productivity and survival operating via a bottom-up mechanism (photosynthesis limitation).
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Journal of population economics 12 (1999), S. 391-409 
    ISSN: 1432-1475
    Keywords: JEL classification: I38 ; Key words: Interstate migration ; welfare ; poverty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Sociology , Economics
    Notes: Abstract. This paper examines the extent to which differences in welfare generosity across states leads to interstate migration. Using microdata from the National Longitudinal Survey of Youth (NLSY) between 1979 and 1992, we employ a quasi-experimental design that utilizes the categorical eligibility of the welfare system. The pattern of cross-state moves among poor single women with children, who are likely to be eligible for benefits is compared to the pattern among other poor households. We find little evidence indicating that welfare-induced migration is a widespread phenomenon.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Immunogenetics 44 (1996), S. 485-486 
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 16
    Electronic Resource
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    Springer
    Environmental monitoring and assessment 53 (1998), S. 197-212 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bald eagle (Haliaeetus leucocephalus) numbers in North America have increased since the ban of DDT and other organochlorine compounds in the 1970s. The decrease in the environmental concentrations of p,p′-DDE has lead to the lessening of egg-shell thinning and has been a major reason for the current resurgence of bald eagle populations in temperate North America, however, this recovery has not been uniform. Eagles nesting along the shorelines and islands of the Great Lakes have continued to experience impaired productivity. In order to examine some of the reasons for the current recovery of bald eagles in the Great Lakes Basin and the potential use of eagles as a bioindicator species of Great Lakes water quality, we analyzed trends in reproductive activity, concentrations of PCBs and p,p′-DDE in unhatched eggs, and rates of developmental deformities. Numbers of occupied nests, fledged young, and yearly productivity rates have increased across the basin. No trends have been observed in changes in the concentrations of p,p′-DDE nor Total PCBs in unhatched eggs. An increasing rate in the incidence of developmental deformities in nestlings has been observed in Michigan. The recovery of the bald eagle population along the Great Lakes is most likely due to immigration of relatively uncontaminated adults from Interior regions.
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  • 17
    Electronic Resource
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    Springer
    Potato research 6 (1963), S. 191-200 
    ISSN: 1871-4528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Beim Anbau in Israel kommen bei der SorteUp-to-Date im Frühjahrsanbau (als Hauptfrucht) oft Schalendefekte vor, welche den Grad von Bonitätsfehlern erreichen können. Drei Type dieser Schalendefekte wurden mit den folgenden Worten bezeichnet: “Fishy Skin” (fischhäutig), “Turtle Back” (schildkrötenhaft) und “Skin Cracking” (gesprenkelt) (Abb. 1, 2 und 3). Von demselben Ort stammende “Smooth” (glatte), “Fishy” und “Turtle Back” behaftete Knollen von heimischem Pflanzgut der SorteUp-to-Date wurden im März 1961 ausgepflanzt; ihr Ertrag wurde gewogen und das Vorkommen von Schalendefekten registriert. Bei mehreren anderen Sorten wurden Zählungen vorgenommen, um Näheres über die Schalendefekte zu erfahren. Man kam zu folgenden Schlussfolgerungen: In bezug auf das Vorkommen von Schalendefekten wurde zwischen den Pflanzen, die von heimischem oder von importiertem Pflanzgut der SorteUp-to-Date gezogen waren, kein Unterschied gefunden (Tabelle 2); die in der Hauptsaison (März–Juni) von “Smooth” d.h. glatten, mit “Fishy Skin” oder “Turtle Back” behafteten Pflanzknollen gezogenen Pflanzen zeigten in bezug auf den Ertrag oder das Vorkommen von Schalendefekten keine Unterschiede (Tabelle 1); bei der SorteUp-to-Date kommt “Skin Cracking” selten vor; durch die Pflanzung von nur “Smooth” d.h. glattschaligen Knollen aus importiertem oder heimischem Pflanzgut der SorteUp-to-Date wird das Vorkommen von Schalendefekten in der darauffolgenden Nachkommenschaft nicht ausgeschaltet; verschiedene Sorten zeigen eine verschiedene Neigung zur Entwicklung von Schalendefekten beim Anbau in Israel (Abb. 5 und 6); Schalendefekte kommen auf sämtlichen Bodentypen und an sehr unter-schiedlichen Orten vor (Tabelle 3); es scheint, dass die Schalendefekte hauptsächlich auf die Wirkung der Umweltverhältnisse, insbesondere der Feuchtigkeitsfaktoren zurückzuführen sind.
    Abstract: Résumé Cultivée en Israël, la variétéUp-to-Date présente souvent à la récolte (principale) du printemps une rugosité de la peau si importante qu'elle constitute un défaut de qualité. Trois types de défauts de la peau ont reçu les dénominations suivantes: peau-de-poisson (“Fishy Skin”), dos-de-tortue (“Turtle Back”) et craquelure de la peau (“Skin Cracking”) (Fig. 1, 2 et 3). Des échantillons de tubercules lisses, à peau-de-poisson et dos-de-tortue cultivés à partir de plants locaux de la variétéUp-to-Date et provenant du même endroit furent plantés en mars 1961; la récolte obtenue fut triée selon le poids et l'incidence des défauts de la peau fut notée. La comptage fut effectué sur plusieurs variétés différentes afin d'obtenir plus de données sur les affections de la peau. Les conclusions furent les suivantes: il n'y avait aucune différence quant à l'incidence des défauts de la peau entre les récoltes obtenues de plants locaux d'Up-to-Date et celles de plants d'importation (Tableau 2); les cultures faites à partir de plants lisses, peau-de-poisson et dos-de-tortue pendant la saison principale (mars-juin) ne présentainent aucune différence quant au rendement ni aux défauts de la peau (Tableau 1). La variétéUp-to-Date est rarement sujette à la craquelure de la peau. Le fait de planter exclusivement des tubercules à peau lisse, de production locale ou d'importation, n'élimine pas les défauts de la peau dans la récolte suivante. Différentes variétés, lorsqu'elles sont cultivées en Israël, présentent des susceptibilités variables aux défauts de la peau (Fig. 5 et 6). Les défauts de la peau se manifestent sur les sols de tours types et en des endroits très différents (Tableau 3). Ils semblent ètre principalement dus à l'effet des conditions du milieu, surtout en ce qui concerne l'humidité.
    Notes: Summary Abnormal skin conditions in crops grown in Israel are described. Their incidence could neither be correlated with similar conditions in the seed nor with the use of imported or locally grown seed. Varietal differences in liability to develop such defects were established. The defects are considered to be due to environmental conditions, particularly moisture relations.
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  • 18
    ISSN: 1573-8868
    Keywords: geostatistics ; spatial interpolation ; spatial pattern ; surface-fitting algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A factorial, computational experiment was conducted to compare the spatial interpolation accuracy of ordinary and universal kriging and two types of inverse squared-distance weighting. The experiment considered, in addition to these four interpolation methods, the effects of four data and sampling characteristics: surface type, sampling pattern, noise level, and strength of small-scale spatial correlation. Interpolation accuracy was measured by the natural logarithm of the mean squared interpolation error. Main effects of all five factors, all two-factor interactions, and several three-factor interactions were highly statistically significant. Among numerous findings, the most striking was that the two kriging methods were substantially superior to the inverse distance weighting methods over all levels of surface type, sampling pattern, noise, and correlation.
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  • 19
    ISSN: 1573-8469
    Keywords: PNRSV ; ApMV ; Ilarvirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A complete sequence for the RNA 3 of Prunus necrotic ringspot virus (PNRSV) is described (Genbank Accession U57046). Primers from this sequence were used to amplify both the movement protein and coat protein genes of 3 other isolates of PNRSV originating from different host species and geographic locations. Comparisons of these sequences with those of other published sequences for PNRSV and the closely related apple mosaic virus (ApMV) showed that both the movement proteins and coat proteins of isolates of PNRSV are extensively conserved irrespective of either the original host or the geographic origin. The movement protein and coat protein of ApMV and PNRSV are sufficiently conserved to suggest that these two viruses may have evolved from a common ancestor. The amino acid sequence of the two coat proteins shows areas of similarity and difference that would explain the serological continuum reported to occur among isolates of these two viruses. Nevertheless, the movement protein and coat protein of the two viruses are sufficiently different so that ApMV and PNRSV should be considered to be distinct viruses.
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  • 20
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    Flow, turbulence and combustion 59 (1997), S. 283-298 
    ISSN: 1573-1987
    Keywords: mixing rule ; chemical equilibrium ; layer formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The formation of a stable stratification, rather than a uniformly mixed state, is shown to depend critically on the equation of state (EOS) or mixing rule for the density as a function of the solution constitution. For instance, ideal solutions can form any stable stratification at hydrostatic equilibrium, although molecular diffusion will eventually make the concentration of solute uniform. Several other types of EOS are considered at hydrostatic equilibrium, resulting in two and three layer stratifications. In the presence of convective mixing, however, the EOS serves only as a guide, since the dynamics of, for example, turbulent dispersion, significantly alter the formation of stratifications. The case of recirculating flows, however, can be simply treated and results in two layer stratifications for an EOS which is superjacent to the ideal solution. The example of stratification formation in a Burt separator is given.
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