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Common Difference (common + difference)
Selected AbstractsBirds select conventional over organic wheat when given free choiceJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2010Ailsa J McKenzie Abstract BACKGROUND: Global demand for organic produce is increasing by ,4 billion annually. One key reason why consumers buy organic food is because they consider it to be better for human and animal health. Reviews comparing organic and conventional food have stated that organic food is preferred by birds and mammals in choice tests. RESULTS: This study shows the opposite result,that captive birds in the laboratory and wild garden birds both consumed more conventional than organic wheat when given free choice. There was a lag in preference formation during which time birds learnt to distinguish between the two food types, which is likely to explain why the present results differ from those of previous studies. A further experiment confirmed that, of 16 potential causal factors, detection by birds of consistently higher levels of protein in conventional seeds (a common difference between many organic and conventional foodstuffs) is the likely mechanism behind this pattern. CONCLUSION: The results of this study suggest that the current dogma that organic food is preferred to conventional food may not always be true, which is of considerable importance for consumer perceptions of organically grown food. Copyright © 2010 Society of Chemical Industry [source] Lineage relationship between LNCaP and LNCaP-derived prostate cancer cell linesTHE PROSTATE, Issue 2 2004Alvin Y. Liu Abstract BACKGROUND LNCaP and its derivative cell lines, which include C4-2 (and the related C4-2B) and CL1, are used as models of prostate cancer. Unlike LNCaP, the other cell lines show features of progressed disease such as metastatic capability and hormone independence. Analyses were done to determine if C4-2 or CL1 cells were selected from pre-existent subpopulations in LNCaP. METHODS Prostate cancer cells were characterized by cluster designation (CD) phenotyping. Specific cell populations were sorted by flow cytometry. DNA array analysis was used to probe differential gene expression. RESULTS CD phenotyping showed that CL1 and C4-2 (and C4-2B) were very dissimilar, and C4-2 was more similar to LNCaP. One common difference between LNCaP and its derivatives was CD26, in which virtually all C4-2 or CL1 cells were CD26+ but only ,10% of LNCaP cells were CD26+. The CD26+ subpopulation of LNCaP was isolated and cultured in vitro. After culture, a high percentage of the cells (descended from the sorted cells) were CD26+, in contrast to those sorted by CD13 or CD44. The cultured CD13 and CD44 populations did not show a high percentage of CD13+ and CD44+ cells, respectively. CD13 and CD44 are markers, in addition to CD26, for CL1 but not for C4-2. CONCLUSIONS C4-2 arose probably from CD26+ LNCaP cells, while CL1 arose de novo. © 2004 Wiley-Liss, Inc. [source] Actigraph-defined moderate-to-vigorous physical activity cut-off points among children: statistical and biobehavioural relevanceACTA PAEDIATRICA, Issue 4 2009Comlavi B Guinhouya Abstract Aim: To compare Actigraph-defined moderate-to-vigorous physical activity (MVPA) cutpoints among children, combining statistical and biobehavioural analyses. Methods: One hundred and thirteen children aged 10.0 ± 0.8 years wore accelerometer for three days. The time they spent in MVPA was estimated using 10 thresholds ranged from 3000 to 3900 cpm. A statistical construct including 45 Bland and Altman pairwise analyses was used to compare the 10 estimates of MVPA. A regression was performed to develop an equation relating mean differences to the between-cutpoint gaps. Results: Mean differences in the MVPA estimates ranged from 1.6 to 12.8 min as a function of increment. Raw estimates of MVPA decreased according to an arithmetic sequence with a common difference of 200 cpm. This difference translates into a drop of 12% in MVPA and a misclassification of up to 5% of children. Mean differences (Y) could be predicted from increments (X) using: Y= 0.02 X (R2= 0.99, SEE = 0.72, p < 0.0001). Conclusion: When a lack of agreement should be assumed as the between-cutpoint gap exceeds 200 cpm, statistical differences may occur earlier at 90 cpm. Yet, the current equation makes it possible to compare and adjust results from studies/interventions using diverse cutpoints for MVPA among children. [source] Refinement of protein crystal structures using energy restraints derived from linear-scaling quantum mechanicsACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2005Ning Yu A novel method is proposed in which combined restraints derived from linear-scaling semiempirical quantum-mechanical (QM) calculations and X-ray diffraction data are combined to refine crystal structures of proteins. Its performance has been tested on a small protein molecule, bovine pancreatic trypsin inhibitor (BPTI). The refinement involves minimization of the sum of a geometric energy function and an X-ray target function based on either the least-squares residual or the maximum-likelihood formalism. For comparison, similar refinement runs have also been performed using energy restraints derived from the force field available in the Crystallography & NMR System (CNS) program. The QM refinements were carried out with weights that were varied by several orders of magnitude and the optimal weights were identified by observing the trend in the final free R values, QM heats of formation and coordinate root-mean-square deviations (r.m.s.d.s) from the crystal structure. It is found that the QM weights are typically smaller but generally on the same scale as the molecular-mechanics (MM) weights for the respective X-ray target functions. The crystallographic R, free R, real-space R values and correlation coefficients based on the structures refined with the energy restraints derived from our QM calculations and Engh and Huber parameters are comparable, suggesting that the QM restraints are capable of maintaining reasonable stereochemistry to a similar degree as the force-field parameters. A detailed inspection of the structures refined with the QM and MM energy restraints reveals that one of the common differences between them and the crystal structure is that the strained bond angles in the crystal structure are corrected after energetically restrained refinements. Systematic differences in certain bond lengths between the QM-refined structures and the statistical averages of experimental structures have also been observed and discussed. [source] | |||||||||||||