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  • transfer functions  (2)
  • Crystal structure  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Monatshefte für Chemie 116 (1985), S. 569-580 
    ISSN: 1434-4475
    Schlagwort(e): Ternary alkaline earth and rare earth metal palladium arsenides, antimonides, and bismuthides ; Crystal structure ; Band structure ; Intermediate valency of Eu compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Fifteen compounds of compositionMPd2 Pn 2 (M = alkaline earth or rare earth metal,Pn = As, Sb, Bi) were prepared. TheirGuinier powder patterns show that the arsenides crystallize with the ThCr2Si2 type structure, the bismuthides with the closely related CaBe2Ge2 type structure. The antimonides most likely also have the CaBe2Ge2 structure as is demonstrated by a structure refinement of EuPd2Sb2 from single crystal X ray data (R = 0.039 for 366 independent structure factors and 15 variable parameters). The structure of SrPd2As2 (ThCr2Si2 type) was refined to a residual ofR = 0.020 for 182F values and 9 variables. EuPd2Sb2 is paramagnetic and a metallic conductor. A comparison of the cell volumes suggests intermediate valency for Eu in EuPd2As2. Chemical bonding and especially the reasons for the adoption of the ThCr2Si2 or CaBe2Ge2 type structures by these compounds are discussed. It is suggested that in going from the phosphides to the bismuthides the ThCr2Si2 structure is loosing and the CaBe2Ge2 structure is gaining stability due to decreasing Pd-Pd bonding and increasing Pd-pnictogen bonding. This trend is caused by the increasing size of the pnictogen component.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1573-0417
    Schlagwort(e): transfer functions ; weighted-averagingpartial-least-squares ; summer temperatures ; surfacesediments ; modern training-sets ; Switzerland
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data-sets was estimated by a series of canonical correspondence analyses (CCA) and the statistical significance of each model was assessed by Monte Carlo permutation tests. A minimal set of environmental variables was found for each biological data-set by a forward-selection procedure within CCA. The unique, independent explanatory power of each set of environmental variables was estimated by a series of CCAs and partial CCAs. Inference models or transfer functions for mean summer (June, July, August) air temperature were developed for each biological data-set using weighted-averaging partial least squares or partial least squares. The final transfer functions, after data screening, have root mean squared errors of prediction, as assessed by leave-one-out cross-validation, of 1.37 °C (chironomids), 1.60 °C (benthic cladocera), 1.62 °C (diatoms), 1.77 °C (planktonic cladocera), and 2.23 °C (chrysophyte cysts).
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 1573-0417
    Schlagwort(e): transfer functions ; WA-PLS ; total phosphorus ; trophic state ; eutrophication ; surface sediments ; Switzerland ; diatoms ; cladocera ; chironomids ; chrysophytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Surface sediments from 68 small lakes in the Alps and 9 well-dated sediment core samples that cover a gradient of total phosphorus (TP) concentrations of 6 to 520 μg TP l-1 were studied for diatom, chrysophyte cyst, cladocera, and chironomid assemblages. Inference models for mean circulation log10 TP were developed for diatoms, chironomids, and benthic cladocera using weighted-averaging partial least squares. After screening for outliers, the final transfer functions have coefficients of determination (r2, as assessed by cross-validation, of 0.79 (diatoms), 0.68 (chironomids), and 0.49 (benthic cladocera). Planktonic cladocera and chrysophytes show very weak relationships to TP and no TP inference models were developed for these biota. Diatoms showed the best relationship with TP, whereas the other biota all have large secondary gradients, suggesting that variables other than TP have a strong influence on their composition and abundance. Comparison with other diatom – TP inference models shows that our model has high predictive power and a low root mean squared error of prediction, as assessed by cross-validation.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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