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  • 1
    Electronic Resource
    Electronic Resource
    Spatial and temporal variation of resource limitation in Chesapeake Bay (1999)
    Springer
    Marine biology 133 (1999), S. 763-778 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report nutrient addition bioassays at 18 stations in Chesapeake Bay (USA) to assess resources limiting phytoplankton growth. Data were pooled from several sampling programs conducted from 1989 to 1994. Spatially, light and P limitation declined from low salinity regions to high salinity regions, as N limitation increased. This spatial pattern was driven primarily by freshwater inflows with high N/P and seawater inflows with low N/P. Seasonally, there was a marked progression of winter light limitation, spring P limitation, and summer N limitation at mesohaline and polyhaline stations. The seasonal pattern appeared to be caused by temperature, mixing, river discharge, and sediment P fluxes. At high salinity stations, we also observed winter N limitation (caused by DIN depletion prior to spring nitrate delivery), and at lower salinity stations there was fall P limitation (caused by reaeration of bottom sediments). At tidal fresh stations, turbidity and nutrient concentrations resulted in continuous light limitation, except at some stations in summer. Interannual decreases in light limitation and increases in N and P limitation appear to represent improvements in water quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050518
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  • 2
    Electronic Resource
    Electronic Resource
    A large open reading frame (orf1995 ) in the chloroplast DNA of Chlamydomonas reinhardtii encodes an essential protein (1997)
    Springer
    Molecular genetics and genomics 253 (1997), S. 649-653 
    Details
    ISSN: 1617-4623
    Keywords: Key words Green algae ; Chlamydomonas reinhardtii ; Chloroplast genome ; Gene inactivation ; Transmembrane protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An open reading frame potentially encoding a protein of 1995 amino acids (orf1995) has been found in the chloroplast genome of the green alga Chlamydomonas reinhardtii. Besides having a short hydrophobic N-terminal domain with five putative transmembrane helices, the predicted orf1995 product is highly basic. orf1995 might be a homologue of the ycf1 gene in land plants, whose function has not yet been determined. Mutants of C. reinhardtii transformed with a disruption of orf1995 remain heteroplasmic for the wild-type and disrupted alleles of this gene, indicating that the orf1995 product is essential for cell survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050368
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  • 3
    Electronic Resource
    Electronic Resource
    Oxydehydrogenation of propane over Mg-V-Sb-oxide catalysts. I. Reaction network (1996)
    Springer
    Catalysis letters 42 (1996), S. 135-137 
    Details
    ISSN: 1572-879X
    Keywords: Oxydehydrogenation ; propane ; propylene ; Mg-V-Sb-oxide catalyst ; reaction network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Magnesium vanadates have been shown by various groups to be active oxydehydrogenation catalysts for the conversion of light paraffins to the corresponding olefins. The olefins produced have significant commercial value in petroleum and petrochemical industry. Recently, we reported that doping of the magnesium vanadates with antimony, antimony-phosphorus, or boron, produces catalysts with significantly better selectivities to olefins than those of the parent undoped catalysts. Among these, the composition Mg4V2SbOx was selected for further study of propane oxydehydrogenation and its reaction network. At 500°C and atmospheric pressure, the selectivity to propylene decreases monotonically from 75% to 5% as propane conversion is increased from 2% to 68%. An analysis of the reaction network reveals, that propylene is the only useful first formed product, that COx is produced largely by sequential oxidation of the in situ formed propylene, but also to a lesser extent direct from propane by a deep oxidation route. The presence of two parallel pathways for COx formation is of interest, as it suggests that partial and deep oxidations may occur at different surface sites or involve different forms of reactive oxygens. Both of these might be amenable to electronic modification by substitution or doping to achieve higher propylene selectivities and yields at higher propane conversions, or their catalytic behavior might be advantageously alterable through site isolation of the paraffin activation centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810678
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  • 4
    Electronic Resource
    Electronic Resource
    Oxydehydrogenation of propane over Mg-V-Sb-oxide catalysts. II. Reaction kinetics and mechanism (1996)
    Springer
    Catalysis letters 42 (1996), S. 139-148 
    Details
    ISSN: 1572-879X
    Keywords: Oxydehydrogenation ; propane ; propylene ; Mg-V-Sb-oxide catalyst ; reaction kinetics ; mechanism ; site isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recently we reported that Mg4V2Sb2Ox is selective for propane andn-butane Oxydehydrogenation at low hydrocarbon conversion, and that propane is oxidized in parallel reactions to propylene and COx. We report now on the kinetics of propane and propylene oxidations over this catalyst. The partial oxidations of propane and propylene and zero-order in oxygen, whereas deep oxidations of both hydrocarbons are half-order. This difference in reaction order indicates that different forms of reactive oxygen are involved in the partial and deep oxidation reactions. Presumably, nucleophilic lattice oxygen partakes in the partial oxidation, while electrophilic dissociatively adsorbed oxygen is involved in deep oxidation. A single activated surface adsorbed state of the hydrocarbons is thought to be involved in both the partial and deep oxidation reactions. An interpretation of the observed reaction kinetics in context of the Mg4V2Sb2Ox solid state chemistry, and the partial oxidation literature in general, suggests that selective oxydehydrogenation of propane occurs on isolated (Sb-O-V-O-Sb) sites, deep oxidation on multiple vicinal vanadium sites (Sb-O-V-O-V-O-Sb), and partial oxidation of propylene to acrolein on subsurface V-promoted antimony sites (Sb-O-Sb). Therefore, unproved selectivity of desired intermediates (propylene/acrolein) should be achieved by further lowering the vanadium concentration and/or through key solid state positioning of the vanadium in the catalyst lattice. Alternatively, selective doping to electronically decrease the electrophilicity of the waste forming sites and its appended oxygen should also help depress the waste forming reaction channels in favor of the desired partial oxidation channels. Finally it is anticipated that higher useful product yields would be attained with a compositionally optimized Mg-V-Sb-oxide catalyst by opting for a more stable, isolatable intermediate, e.g., acrylonitrile, by reacting propane in the presence of ammonia and oxygen (air) over this catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810679
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  • 5
    Electronic Resource
    Electronic Resource
    Inputs, losses and transformations of nitrogen and phosphorus in the pelagic North Atlantic Ocean (1996)
    Springer
    Biogeochemistry 35 (1996), S. 181-226 
    Details
    ISSN: 1573-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The North Atlantic Ocean receives the largest allochthonous supplies of nitrogen of any ocean basin because of the close proximity of industrialized nations. In this paper, we describe the major standing stocks, fluxes and transformations of nitrogen (N) and phosphorus (P) in the pelagic regions of the North Atlantic, as one part of a larger effort to understand the entire N and P budgets in the North Atlantic Ocean, its watersheds and overlying atmosphere. The primary focus is on nitrogen, however, we consider both nitrogen and phosphorus because of the close inter-relationship between the N and P cycles in the ocean. The oceanic standing stocks of N and P are orders of magnitude larger than the annual amount transported off continents or deposited from the atmosphere. Atmospheric deposition can have an impact on oceanic nitrogen cycling at locations near the coasts where atmospheric sources are large, or in the centers of the highly stratified gyres where little nitrate is supplied to the surface by vertical mixing of the ocean. All of the reactive nitrogen transported to the coasts in rivers is denitrified or buried in the estuaries or on the continental shelves and an oceanic source of nitrate of 0.7–0.95 × 1012 moles NO 3 −1 y−1 is required to supply the remainder of the shelf denitrification (Nixon et al., this volume). The horizontal fluxes of nitrate caused by the ocean circulation are both large and uncertain. Even the sign of the transport across the equator is uncertain and this precludes a conclusion on whether the North Atlantic Ocean as a whole is a net source or sink of nitrate. We identify a source of nitrate of 3.7–6.4 × 1012 moles NO 3 − y−1 within the main thermocline of the Sargasso Sea that we infer is caused by nitrogen fixation. This nitrate source may explain the nitrate divergence observed by Rintoul & Wunsch (1991) in the mid-latitude gyre. The magnitude of nitrogen fixation inferred from this nitrate source would exceed previous estimates of global nitrogen fixation. Nitrogen fixation requires substantial quantities of iron as a micro-nutrient and the calculated iron requirement is comparable to the rates supplied by the deposition of iron associated with Saharan dust. Interannual variability in dust inputs is large and could cause comparable signals in the nitrogen fixation rate. The balance of the fluxes across the basin boundaries suggest that the total stocks of nitrate and phosphate in the North Atlantic may be increasing on time-scales of centuries. Some of the imbalance is related to the inferred nitrogen fixation in the gyre and the atmospheric deposition of nitrogen, both of which may be influenced by human activities. However, the fluxes of dissolved organic nutrients are almost completely unknown and they have the potential to alter our perception of the overall mass balance of the North Atlantic Ocean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02179827
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  • 6
    Electronic Resource
    Electronic Resource
    Nitrogen and phosphorus budgets of the North Atlantic Ocean and its watershed (1996)
    Springer
    Biogeochemistry 35 (1996), S. 3-25 
    Details
    ISSN: 1573-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Anthropogenic food and energy production extensively mobilize reactive nitrogen (N) in the watershed of the North Atlantic Ocean (NAO). There is wide spread N distribution by both hydrologic and atmospheric processes within the watershed of the NAO, resulting in reactive N accumulation in terrestrial systems. Net denitrification in most estuaries and continental shelves exceeds the amount of N supplied to the shelves by rivers and requires a supply of nitrate from the open ocean. Thus riverine N is only transported to the open ocean in a few areas with the flow from a few major rivers (e.g., Amazon). Atmospheric N deposition to the open ocean has increased and may increase the productivity of the surface ocean. In addition, as a consequence of increased Fe deposition to the open ocean (due in part to anthropogenic processes), the rate of biological N-fixation may have increased resulting in N accumulation in the ocean. Phosphorus (P) is also mobilized by anthropogenic processes (primarily food production). Relative to N, more of the P is transported across the shelf to the open ocean from both estuaries and major rivers. There are several consequences of the increased availability of N and P that are unique to each element. However, the control on primary productivity in both coastal and open ocean ecosystems is dependent on a complex and poorly understood interaction between N and P mobilization and availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02179823
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of Clearfell Harvesting on Lucanid Beetles (Coleoptera: Lucanidae) in Wet and Dry Sclerophyll Forests in Tasmania (1999)
    Springer
    Journal of insect conservation 3 (1999), S. 85-95 
    Details
    ISSN: 1572-9753
    Keywords: saproxylic ; old growth ; forest management ; decaying wood ; conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract The effects of commercial forestry harvest and regeneration practices (clearfelling and slash-burning) on the lucanid fauna of the wet sclerophyll forests of southern Tasmania and the dry sclerophyll forests of eastern Tasmania were examined using pitfall catches. Lucanids are saproxylic beetles, dependent on dead, moribund and decaying wood. Samples taken from old-growth forest and from a chronosequence of sites regenerating after logging, in each forest type, were used to compare the species richness and abundance of the lucanid assemblages. In both forest types, species richness and abundance was highest in the youngest regeneration sites (1–3 year), reflecting the species richness of the original and adjacent unlogged forest, lowest in the older (20–25 year) sites, and variable in the old-growth sites. TWINSPAN cluster analysis showed no clear distinction between regeneration and old-growth forest. The post-harvest slash and stump residue provided an important refugium and initial habitat, but our research indicates that some species may not maintain populations in the long term. Our results suggest that most species of lucanids will find a continuous supply of suitable habitat only in old-growth forests; and such species may become less common as clearfell harvesting leads to a replacement of heterogeneous old-growth forest with single-aged monospecific stands. Continuity of supply of wood in all decay stages, the maintenance of sufficient source areas, and biological connectivity between old-growth stands to enable dispersal, are all likely to be essential to maintain lucanid beetle community integrity. If similar principles apply to other saproxylic species of invertebrate, then clearfelling and slash-burning may cause a gradual extinction of an important element of the forest biota.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009696130694
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  • 8
    Electronic Resource
    Electronic Resource
    Evaluation of a DNA probe for the quantitative detection of common bacterial blight in common bean and its application in a breeding program (1996)
    Springer
    Euphytica 90 (1996), S. 129-135 
    Details
    ISSN: 1573-5060
    Keywords: common bacterial blight ; densitometry ; DNA probe ; Phaseolus vulgaris ; Xanthomonas campestris pv. phaseoli ; common bean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Breeding of Phaseolus vulgaris L. for resistance to common bacterial blight (CBB) can be done with visual evaluations of symptoms to distinguish broad resistance classes, but a more quantitative measure was needed for genetic studies of resistance. A novel method of evaluation was developed by quantifying Xanthomonas campestris pv. phaseoli (XCP) in bean leaf tissue infected with CBB using a 32P-labeled probe and densitometric analysis of hybridization signals. Quantification of bacterial populations using the probe was highly correlated (r=0.98) with the number of colony forming units (CFU) from plate counts of the same leaf samples. The probe was used to follow XCP population dynamics on susceptible (BAT 41) and resistant (OAC 88-1) bean genotypes. OAC 88-1 supported a maximum XCP population which was approximately tenfold less than BAT 41. The probe was also used to study an F2/F3 population segregating for resistance. Narrow sense heritability estimates were less for resistance measured on the basis of bacterial populations (0.18–0.26) than on visual scores of symptoms (0.29–0.38). The anticipated response to selection for CBB resistance would be less based on bacterial numbers than based on symptom expression in this population. In breeding for resistance to CBB, selection based on visual symptoms combined with measurements of XCP populations using a DNA probe can be used to develop bean genotypes that are both resistant to symptom development and bacterial multiplication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023851
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  • 9
    Electronic Resource
    Electronic Resource
    Innovation in environmental policy: the National Environmental Policy Act of the US and the Resource Management Act of New Zealand (1997)
    Springer
    The environmentalist 17 (1997), S. 181-190 
    Details
    ISSN: 1573-2991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract On enactment, both the National Environmental Policy Act (NEPA), 1970 of the US and the Resource Management Act (RMA), 1991 of New Zealand received accolades for innovativeness. However, is such praise justified when these acts are explored through the literature on policy innovation? This paper suggests that it is. More importantly, recognizing how different attributes of innovation contribute to having a policy adopted suggests what the crafters of future environmental policies might do well to consider. It is critical to attend to the political climate in which a policy is being drafted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018520521124
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of genetic relationships among shape Phaseolus vulgaris populations in a conical cross from RAPD marker analyses (1998)
    Springer
    Molecular breeding 4 (1998), S. 395-406 
    Details
    ISSN: 1572-9788
    Keywords: common bean ; conical cross ; genetic distance ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Random-amplified polymorphic DNA (RAPD) markers were used to determine genetic relationships among Phaseolus vulgaris breeding populations. Genetic distances were calculated from the distribution of 317 RAPD markers among 8 parents, 10 individuals from 8 cycle-one populations, 10 individuals from 6 cycle-two populations and 10 individuals from 2 cycle-three populations of a conical cross. Genetic distances between populations and parents were consistent with their degree of relationship in the crossing scheme indicating that a RAPD analysis is a sensitive and useful method for categorizing breeding materials according to their genetic similarities. Genetic variation among individuals within populations increased from cycle one to cycle three and variation among populations within the cycles decreased from cycle one to cycle three in the conical cross. The results showed that this crossing scheme can be used to collect the genetic diversity in eight parents into a single plant breeding population. Abbreviations: CBB, common bacterial blight; GD, genetic distance; RAPD, random-amplified polymorphic DNA
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009601910980
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