Otolith d18 O and d13 C values have been used extensively to reconstruct thermal and diet histories. Researchers have suggested that individual growth rate and size may have an effect on otolith isotope ratios and subsequently confound otolith-based thermal and diet reconstructions. As few explicit tests of the effect on fish in freshwater environments exist, here we determine experimentally the potential for related growth rate and size effects on otolith d18 O and d13 C values.
Fifty Arctic charr were raised in identical conditions for two years after which their otoliths were removed and analyzed for their d18 O and d13 C values. The potential effects of final length and the Thermal Growth Coefficient (TGC) on otolith isotope ratios were tested using correlation and regression analysis to determine if significant effects were present and to quantify effects when present.
The analyses indicated that TGC and size had significant and similar positive non-linear relationships with d13 C values and explained 35% and 42% of the variability, respectively. Conversely, both TGC and size were found to have no significant correlation with otolith d18 O values. There was no significant correlation between d18 O and d13 C values.
The investigation indicated the presence of linked growth rate and size effects on otolith d13 C values, the nature of which requires further study. Otolith d18 O values were unaffected by individual growth rate and size, confirming the applicability of these values to thermal reconstructions of fish habitat.
Otolith d18 O and d13 C values have been used extensively to reconstruct thermal and diet histories. Researchers have suggested that individual growth rate and size may have an effect on otolith isotope ratios and subsequently confound otolith based thermal and diet reconstructions. As few explicit tests of the effect of fish in freshwater environments exist, here we determine experimentally the potential for related growth rate and size effects on otolith d18 O and d13 C values.
Fifty Arctic charr were raised in identical conditions for two years after which their otoliths were removed and analyzed for their d18 O and d13 C values. The potential effects of final length and the Thermal Growth Coefficient (TGC) on otolith isotope ratios were tested using correlation and regression analysis to determine if significant effects were present and to quantify effects when present.
The analyses indicated that TGC and size had significant and similar positive non-linear relationships with d13 C values and explained 35% and 42% of the variability, respectively. Conversely, both TGC and size were found to have no significant correlation with otolith d18 O values. There was no significant correlation between d18 O and d13 C values.
The investigation indicated the presence of linked growth rate and size effects on otolith d13 C values, the nature of which requires further study. Otolith d18 O values were unaffected by individual growth rate and size, confirming the applicability of applying these values to thermal reconstructions of fish habitat.
Otolith d18 O and d13 C values have been used extensively to reconstruct thermal and diet histories. Researchers have suggested that individual growth rate and size may have an effect on otolith isotope ratios and subsequently confound otolith-based thermal and diet reconstructions. As few explicit tests of the effect on fish in freshwater environments exist, here we determine experimentally the potential for related growth rate and size effects on otolith d18 O and d13 C values.
Fifty Arctic charr were raised in identical conditions for two years after which their otoliths were removed and analyzed for their d18 O and d13 C values. The potential effects of final length and the Thermal Growth Coefficient (TGC) on otolith isotope ratios were tested using correlation and regression analysis to determine if significant effects were present and to quantify effects when present.
The analyses indicated that TGC and size had significant and similar positive non-linear relationships with d13 C values and explained 35% and 42% of the variability, respectively. Conversely, both TGC and size were found to have no significant correlation with otolith d18 O values. There was no significant correlation between d18 O and d13 C values.
The investigation indicated the presence of linked growth rate and size effects on otolith d13 C values, the nature of which requires further study. Otolith d18 O values were unaffected by individual growth rate and size, confirming the applicability of these values to thermal reconstructions of fish habitat.
Data on ten variables and 16 biomarkers were obtained on 119 patients with newly diagnosed pulmonary cancer. The prognostic value of 16 biomarkers (alpha-1-antitrypsin [AAT], adrenocorticotropic hormone [ACTH], alpha-fetoprotein [AFP], carcinoembryonic antigen [CEA], human chorionic gonadotropin [HCG], immune complexes, immunoglobulins, N-terminal peptide of proopiomelanocortin [NTERM], and tumor-associated antibody [TAA]) was tested by adding these to the model of age, gender, stage, morphology, Feinstein's classification of symptoms, Karnofsky scale, leukocyte count, recent weight loss, and liver enzymes. Using Cox's regression method and a forward stepwise procedure, seven biomarkers (ACTH, AAT, AFP, calcitonin, HCG, TAA, and prolactin) entered the model. Elevated levels of cortisol and TAA were associated with longer survival. The selection of biomarkers by stepwise regression needs to be interpreted with caution, especially since the Z scores were found to be dependent on the particular variables included in the model. Furthermore, when dichotomized on maximum of the normal laboratory values, HCG and AFP were infrequently (2%) elevated. The lack of correlation among the biomarkers supports the hypothesis of random derepression of the genome of cancer cells. Further studies in improved modeling and the formulation of a biomarker index could enhance our understanding of the biology of cancer.
