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  • LUNAR AND PLANETARY EXPLORATION  (6)
  • *Global Warming  (1)
  • *Periodicity  (1)
  • 1
    Publication Date: 2012-05-25
    Description: Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wolkovich, E M -- Cook, B I -- Allen, J M -- Crimmins, T M -- Betancourt, J L -- Travers, S E -- Pau, S -- Regetz, J -- Davies, T J -- Kraft, N J B -- Ault, T R -- Bolmgren, K -- Mazer, S J -- McCabe, G J -- McGill, B J -- Parmesan, C -- Salamin, N -- Schwartz, M D -- Cleland, E E -- England -- Nature. 2012 May 2;485(7399):494-7. doi: 10.1038/nature11014.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive 0116, La Jolla, California 92093, USA. wolkovich@biodiversity.ubc.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22622576" target="_blank"〉PubMed〈/a〉
    Keywords: Artifacts ; Ecosystem ; Flowers/growth & development/physiology ; *Global Warming ; *Models, Biological ; *Periodicity ; Plant Development ; Plant Leaves/growth & development/physiology ; *Plant Physiological Phenomena ; Plants/classification ; Reproducibility of Results ; Soil/chemistry ; Temperature ; Time Factors ; *Uncertainty
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2019-06-27
    Description: The black inclusion from the Krymka LL3 chondrite previously found to contain 'mysterite' by Lewis et al. (1979) belongs to a hitherto unknown class of carbonaceous chondrites. Its olivine and pyroxene compositions, Fo 97-99 and En 96, respectively, are characteristic of carbonaceous chondrites and its plagioclase composition. An 100 is characteristic of C3's. It contains a peculiar group of Co-, Cr-rich metal grains whose compositions are similar, but not identical, to those in C2 chondrites. Its weight ratios of total Fe/SiO2 and SiO2/MgO are 0.74 and 1.43, respectively, and its atomic ratio of Si/Al is 10.7, exactly the same as in carbonaceous chondrites. Its bulk chemical composition is very close to that of the Murchison C2 chondrite. The association of mysterite with a special type of carbonaceous chondrite material suggests that mysterite formed by low-temperature condensation in a different region of the nebula from other carbonaceous chondrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Feb. 198
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  • 3
    Publication Date: 2019-06-27
    Description: Results of a detailed mineralogical and textural study of the HAL (Hibonite ALlende) inclusion of the Allende meteorite, which has been found to exhibit no Mg-26 excesses despite very high Al-27/Mg-24 ratios and large fractionation effects with small nuclear effects in its Ca, are reported. The inclusion is found to consist of three up to 1-mm diameter hibonite crystals partially surrounded by a black rim resembling a devitrified glass and containing an anisotropic Al-Fe oxide, which is in turn surrounded by a 2-mm thick friable rim sequence consisting of five layers distinguishable by mineral composition. From the available evidence, it is concluded that each of the layers of the friable rim formed by the accretion of an assemblage of condensate grains rather than by the complete reaction of a HAL precursor with a nebular gas, thus explaining its unusual isotopic characteristics and supporting the conclusion that the solar nebular contained isotopically-distinct reservoirs.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; May 1980
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  • 4
    Publication Date: 2019-06-28
    Description: Two forsterite-, fassaite-, spinel-rich inclusions in Allende which share common mineralogy and texture with three previously described inclusions are described. These inclusions were at least partially molten at temperatures over 1400 C, and their crystallization sequence was spinel, olivine, fassaite, and Mg-rich melilite. At least some of them experienced partial volatilization of MgO and SiO2 from their outer margins. At least one of the inclusions is highly enriched in MgO relative to CaO and Al2O3 compared to Allende coarse-grained inclusions, although it is just as strongly enriched in refractory trace elements as the latter, relative to C1 chondrites. Two of the objects are FUN inclusions on the basis of their oxygen, magnesium, and silicon isotopic compositions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 48; 533-548
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  • 5
    Publication Date: 2019-07-13
    Description: Coarse-grained, calcium-rich inclusions in the Allende meteorite are enclosed by sequences of very thin, mineralogically distinct rim layers. A number of questions arise in connection with the presence of rims. The present investigation presents new observations bearing on all these questions and provides a model for the formation of rims. A zoned alteration vein is considered along with a sinuous inclusion, a spinel-perovskite-melilite band (SP), layers overlying the melilite-rich side of SP, a layer overlying the spinel-rich side of SP, and aspects of rim composition and the degree of alteration in coarse-grained inclusions. It is proposed that rims on coarse-grained inclusions formed in a nonequilibrium process involving those reactions between coarse-grained melilite and spinel and a nebular gas phase which also produced the secondary alteration products in the interiors of these inclusions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Science Conference; Mar 16, 1981 - Mar 20, 1981; Houston, TX
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  • 6
    Publication Date: 2019-07-13
    Description: The major and trace elements of separated fragments and a bulk sample from CG-11, a hibonite-bearing inclusion in the Allende meteorite, were analyzed. Major element abundances were used to determine the minerology of separated fragments. The high degree of correlation between Eu/Sm ratios and Lu/Yb ratios for the samples studied indicates that their rare earth element (REE) distributions are governed by two components. One, Lu-, Eu-rich, is probably hibonite; the other, depleted in these elements, seems to be associated with the secondary alteration phases, grossular, nepheline and anorthite. The REE distribution in CG-11 precludes melting events after formation of the secondary alteration phases, but a melting event involving the primary minerals cannot be excluded. The enrichment of Lu with respect to other measured REE in hibonite can be explained by present REE condensation models. Two Hf-bearing components, most likely hibonite and perovskite, are necessary to account for variations in Sc/Hf ratios in the fragments studied. The lithophile volatiles Na, Mn, Fe, Zn, and probably Cr increase in the same order as the amount of secondary alteration minerals; the volatile siderophile elements Co and Au, however, do not.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Science Conference; Mar 13, 1978 - Mar 17, 1978; Houston, TX
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  • 7
    Publication Date: 2019-07-13
    Description: The origin of a Type A, hibonite-rich, coarse-grained inclusion is investigated with the electron microprobe and petrographic and scanning electron microscopes. The primary phases are hibonite, rhonite, Ti-Al-pyroxene, spinel, perovskite and melilite. Evidence for the crystallization of the bulk of the primary phases, hibonite and melilite, from a melt is lacking, suggesting that they may have condensed directly from a solar nebular gas instead. Primary phases were intensely altered during a later condensation event which deposited grossular, anorthite, nepheline and wollastonite in veins and cavities. Four or five condensate rims were deposited as successive layers on the outside of the inclusion. From inside to outside, they consist of perovskite + spinel, nepheline + anorthite, Ti-Al-pyroxene + diopside, hedenbergite + or - wollastonite + or - andradite and, finally, prisms of diopside and hedenbergite with wollastonite and andradite. Reverse zoning in melilite; alteration phases and rim phases, which are not stable condensates from a gas of solar composition; and details of the sequence of rim condensates all suggest that the entire condensation history of this inclusion was interrupted by changes in pressure and/or temperature and/or gas phase composition.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Science Conference; Mar 13, 1978 - Mar 17, 1978; Houston, TX
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