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  • 1
    Electronic Resource
    Electronic Resource
    Computer-controlled, small sample ac calorimetry at low temperatures and in high magnetic fields (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 1743-1745 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a computer based ac calorimetry technique for small samples (m〈100 mg) at low temperatures (T〈2 K) and in high magnetic fields (B≤20 T). We have found this technique suitable for relative calorimetry in noisy environments. Extension of this technique to absolute calorimetry is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139378
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  • 2
    Electronic Resource
    Electronic Resource
    Specific heat of speer carbon resistor thermometers at low temperatures and in magnetic fields (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 837-838 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have measured the specific heat of a Speer carbon resistor in the temperature range 0.32 to 4 K and in 0, 1.2, 6, and 12 T magnetic fields. Our zero field data disagree by an order of magnitude with previously reported results; the specific heat is also field sensitive. Where a piece of Speer resistor forms part of the addenda of a small-mass specific heat platform, lack of proper accounting for its addenda contribution can lead to large errors in the specific heat measurements, particularly in field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142044
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  • 3
    Electronic Resource
    Electronic Resource
    Spin fluctuations and superconductivity in UPt3 (invited) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3049-3053 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Of the three known high effective mass ("heavy fermion'') superconductors, UPt3 has quite different properties from the rather similar CeCu2Si2 and UBe13. In particular, UPt3 has a much different temperature dependence of its resistivity below 300 K, a much lower initial slope of the superconducting critical field, H'c2(Tc), a much greater dependence of the superconducting transition temperature, Tc, on lattice perfection (proportional to resistivity ratio), and a much different temperature dependence of the low temperature normal state specific heat, Cn. This temperature dependence of Cn in fact includes a T3 ln T term for UPt3, compared to approximately a T−2 dependence for UBe13 and CeCu2Si2 at low temperatures. The presence of a T3 ln T term in Cn for UPt3, coupled with the extreme dependence of Tc on lattice perfection, has led to speculation that the pairing of the superconducting electrons in UPt3 may not be between opposite spins, but between parallel spins, i.e., p-wave instead of s-wave pairing. Recently, further experimental and theoretical evidence has been found supporting this speculation that UPt3 may be a p-wave superconductor. The present work surveys the properties of UPt3, including new results on the spin fluctuation behavior in the normal state of UPt3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335211
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  • 4
    Electronic Resource
    Electronic Resource
    The Physiology and Biochemistry of Parasitic Angiosperms (1990)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology and Plant Molecular Biology 41 (1990), S. 127-151 
    Details
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pp.41.060190.001015
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  • 5
    Electronic Resource
    Electronic Resource
    Characteristics of inorganic nitrogen assimilation of plants in fire-prone Mediterranean-type vegetation (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A range of approaches was used to investigate how species within a fire-prone Banksia woodland in South West Australia exploited inorganic soil nitrogen sources and how this changes through the development of the fire chronosequence. Nitrate and ammonium were present in soil solution throughout the chronosequence but nitrate predominated in recently burnt sites. Mean shoot nitrate reductase activities were high for all species in recently burnt sites and showed little increase when nitrate was supplied via the transpiration stream. Nitrate reductase of shoots of most species was low at sites not burnt for several years, but following transpirational induction with nitrate, developed activities similar to those at recently burnt sites. The principal amino compounds transported in the xylem were species specific, including asparagine, glutamine and citrulline-dominated species, and changed little in relative composition across the chronosequence. Species most active in leaf nitrate reduction transported the largest amounts of nitrate in their xylem sap and proportional amounts of nitrate in xylem tended to be greatest in recently burnt sites. Most of the species examined appeared to be shoot rather than root nitrate assimilators, but marked differences were recorded in potential of leafy shoots of different species to reduce nitrate. As a general rule, shallow-rooted herbaceous, non-mycorrhizal or VAM-positive species had the highest capacity to reduce nitrate, whereas woody species with ericoid mycorrhizae or combined vesicular arbuscular/ectomycorrhizal associations exhibited little capacity to reduce nitrate in roots or shoots. It seems likely that this latter group utilize ammonium or even organic forms of nitrogen rather than nitrate. Some putative nitrogen-fixing species were active in reducing and transporting nitrate, others were virtually inactive in these respects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1993.tb00881.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of nitrogen supply and high temperature on the growth and physiology of the chickpea (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chickpeas were grown with or without nitrate nitrogen feeding, or nodulated with Rhizobium leguminosarum. High [40°C day, 25°C night (HT)] and moderate [25°C day, 177°C night (LT)] temperature regimes were employed during growth. Growth rates, photosynthetic capacity and enzymes of carbon and nitrogen metabolism were monitored to assess the acclimatory capacity of the chickpea. Initial growth rates were stimulated by high temperatures, particularly in nitrate-fed and nodulated plants. Older HT plants had fewer laterals, smaller leaves, and fewer flowers were produced than in LT plants. There was some indication of an acclimation of photosynthesis to high temperatures and this was independent of nitrogen supply. Rubisco activity was increased by high growth temperatures. However, HT plants also had higher transpiration rates and lower water use efficiency than LT plants both in respective growth conditions and when compared in a common condition. High temperatures reduced shoot nitrate reductase activity but had little effect on root activity, which was the same if not greater than activity in LT roots. The amino acid, asparagine, was found at high concentrations in all treatments. Concentrations were maintained throughout growth in HT plants but declined with age in LT plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1993.tb00479.x
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  • 7
    Electronic Resource
    Electronic Resource
    Physiology of the interaction of angiosperm parasites and their higher plant hosts (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Interactions between parasitic angiosperms and their hosts occur at the level of seed germination, haustorial development and resource transfer. Chemicals released from the host function as cues for host recognition, and trigger germination as well as haustorial initiation. Transpiration is a key process regulating solute transfer from host to parasite, and some parasitie plants have unusual stomatal characteristics. Although solute transfer is apoplastic, the haustorium appears to play a role in regulating solute composition. Host responses to infection are reviewed, and it is concluded that competition for water and solutes are unlikely to play a major role in determining reductions in host productivity: metabolic incompatability is suggested to be the major cause of this.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1990.tb01281.x
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  • 8
    Electronic Resource
    Electronic Resource
    15N natural abundance of plant and soil components of a Banksia woodland ecosystem in relation to nitrate utilization, life form, mycorrhizal status and N2-fixing abilities of component species (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Studies of the variation in δ15N values for plants from a fire-prone Banksia woodland in South West Australia showed that pioneer herbaceous, non-mycorrhizal species which were active in nitrate reduction and storage, had the highest values (1.81%c). A detailed study of one such species Ptilotus polystachus demonstrated a close correspondence between the δ15N values of soil nitrate, xylem nitrate and leaf total nitrogen, suggesting an exclusive reliance on nitrate ions as nitrogen source. These pioneer species also showed a preponderance of the chloroplastic isoform of glutamine synthetase while woody species generally had higher activity associated with the cytosolic isoform. The group comprising monocotyledonous hemicryptophytes and geophytes contained species with slightly positive δ15N values and moderately active in nitrate reduction and storage. Nitrogen-fixing species had the lowest δ15N values (–0.36‰), irrespective of their apparent utilisation of nitrate. However, woody resprouter species which had low levels of nitrate reduction and storage had δ15N values which fell within the range of values obtained for the miscellaneous assemblage of N2-fixing species. Consequently, 15N abundance values failed to distinguish N2 fixing from non-fixing woody species, and therefore, could not be used in the ecosystem to determine the dependence of putative nitrogen fixing species on N2 fixation. The study demonstrated complex patterns of nitrogen utilization in the ecosystem in which exploitation of different nitrogen resources related to plant life form and the physiological attributes of nitrogen assimilation by component species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1993.tb00882.x
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  • 9
    Electronic Resource
    Electronic Resource
    Growth and carbon allocation in Pennisetum typhoides infected with the parasitic angiosperm Striga hermonthica (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Growth and gas exchange measurements are used in conjunction with a carbon balance model to describe the millet (Pennisetum typhoides)–witchweed (Striga hermonthica) host—parasite association. Striga hermonthica reduces the growth of millet by 28% and radically alters the architecture of infected plants. Whilst grain yield and stem dry weight are reduced (by 80 and 53%, respectively), leaf and root growth are stimulated (by 41 and 86%, respectively). The difference in production between infected and uninfected millet plants can be accounted for by two processes: first, export of carbon to the parasite (accounting for 16% of the dry weight not gained); and second, parasite-induced reductions in host photosynthesis (accounting for 84% of the dry weight not gained). Striga hermonthica is dependent on carbon exported from the host, since the plant has low rates of photosynthesis coupled with high rates of respiration. The carbon balance model suggests that in mature S. hermonthica plants parasitic on millet, 85% of the carbon is host-derived. Carbon fluxes are also estimated using δ13C measurements, since S. hermonthica is a C3 plant parasitizing a C4 host. In conjunction with gas exchange measurements, these suggest that in root, stem and leaf of S. hermonthica, 87, 70 and 49% of carbon is hostderived, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1990.tb02140.x
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  • 10
    Electronic Resource
    Electronic Resource
    A carbon balance model of the sorghum-Striga hermonthica host-parasite association (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Growth and gas exchange measurements are used to formulate a carbon balance model to describe the sorghum-Striga hermonthica host-Parasite association. S. hermonthica reduces the growth and radically alters the architecture of infected sorghum plants. Grain and stem weight are reduced, whilst leaf and root biomass are maintained. Losses in host productivity result from two processes: export of carbon to the parasite and Parasite-induced reductions in host photosynthesis. The latter occurs before the emergence of the Parasite above ground and accounts for 80% of the Predicted loss in production over the lifecycle of the association. S. hermonthica is dependent on carbon exported from the host, since the plant has low rates of photosynthesis coupled with high rates of respiration. Host-derived carbon accounts for approximately one-third of the total parasite carbon requirement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01921.x
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