Browsing by Subject "Correlation analysis"

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Embargo
Assessing software evolution with the stickiness score: evaluating code persistence across files, folders, and developers
(2025-04) Uysal, Selen
Software evolution involves continuous code changes, making it essential to under-stand factors that influence code stability and persistence. This study introduces a metric called the “Stickiness Score,” measuring the longevity of lines of code (LOC) within a project. It reflects how much of the LOC written by developers or belonging to a specific file or folder has persisted over time. The goal is to examine its correlation with various software metrics: contributor count, developer Stickiness Scores (average, commit-weighted average, and LOC-weighted average), cyclomatic complexity, bug-fix count, and static code analysis metrics, including bug and code smell counts. Stickiness Scores for developers, files, and folders are calculated using the tool developed for this study, Devotion, across five open-source projects. Spearman correlation tests were used to analyze the relationship between file Stickiness Scores and the specified software metrics. Contributor count exhibited a strong negative correlation with file Stickiness Scores. Commit- and LOC-weighted developer Stickiness Scores showed positive correlations, while unweighted averages produced mixed results. Cyclomatic complexity, bug-fix count, and code smell count showed inconsistent correlations. The bug counts in files showed no significant correlation. In conclusion, files with more contributors or frequent bug-related changes tend to be less sticky. In contrast, files modified by high-commit or high-volume contributions from developers with higher stickiness tend to persist longer. The Stickiness Score provides valuable in-sight into how contributor activity, code complexity, bugginess, and smells relate to code longevity.
Open Access
Dynamic correlation effects on the plasmon dispersion in a two-dimensional electron gas
(The American Physical Society, 2003) Yurtsever, A.; Moldoveanu, V.; Tanatar, Bilal
The charge-density oscillations (plasmons) of a low-density two-dimensional uniform electron gas are studied within the framework of finite temperature and frequency dependent (dynamic) version of Singwi, Tosi, Land, and Sjölander theory and compared with the recent experimental results. The use of the Hartree-Fock approximation for the static structure factor leads to a finite temperature dynamical counterpart of the static Hubbard approximation. We observe important differences between dynamic and static local-field factors as well as between the corresponding plasmon dispersion laws. Our calculated plasmon energies that include dynamic correlations are in very-good agreement with the recent experimental results.
Open Access
Effect of six weeks aerobic training upon blood trace metals levels
(2006) Savaş, S.; Şenel, Ö.; Çelikkan, H.; Uǧraş, A.; Aksu, M. L.
This study was carried out to investigate the effects of 6-week aerobic exercise program upon blood Zn and Cu levels. There were 12 male university students with an average age of 21.67+/-0.89 years and no regular training habits participated in the study. The participants were subjected three days a week 1 hour a day continuous running program on treadmill with an intensity of 60-70% for a period of six weeks. They were fed with zinc and copper free diet throughout the study and it was made sure that they were not using copper or zinc containing vitamin tablets. The difference between the pre and post study period were found to be statistically significant as regards to both resting and maximal loading conditions (p<0.01). The pre and post training maxVO2 values were also found to be positively correlated with the copper and zinc levels in blood. Both the copper and zinc blood levels were found decreased after the training period p<0.05.
Open Access
Expression of IFITM1 in chronic myeloid leukemia patients
(Elsevier, 2005) Akyerli, C. B.; Beksac, M.; Holko, M.; Frevel, M.; Dalva, K.; Özbek, U.; Soydan, E.; Özcan, M.; Özet, G.; İlhan, O.; Gürman, G.; Akan, H.; Williams, B. R. G.; Özçelik, T.
We investigated the peripheral blood gene expression profile of interferon induced transmembrane protein 1 (IFITM1) in sixty chronic myeloid leukemia (CML) patients classified according to new prognostic score (NPS). IFITM1 is a component of a multimeric complex involved in the trunsduction of antiproliferative and cell adhesion signals. Expression level of IFITM1 was found significantly different between the high- and low-risk groups (P = 9.7976 × 10-11) by real-time reverse transcription polymerase chain reaction (RT-PCR). Higher IFITM1 expression correlated with improved survival (P = 0.01). These results indicate that IFITM1 expression profiling could be used for molecular classification of CML, which may also predict survival.
Open Access
MicroRNA-519a is a novel oncomir conferring tamoxifen resistance by targeting a network of tumour-suppressor genes in ER+ breast cancer
(John Wiley and Sons Ltd, 2014) Ward, A.; Shukla, K.; Balwierz, A.; Soons, Z.; König, R.; Sahin, O.; Wiemann, S.
Tamoxifen is an endocrine therapy which is administered to up to 70% of all breast cancer patients with oestrogen receptor alpha (ERα) expression. Despite the initial response, most patients eventually acquire resistance to the drug. MicroRNAs (miRNAs) are a class of small non-coding RNAs which have the ability to post-transcriptionally regulate genes. Although the role of a few miRNAs has been described in tamoxifen resistance at the single gene/target level, little is known about how concerted actions of miRNAs targeting biological networks contribute to resistance. Here we identified the miRNA cluster, C19MC, which harbours around 50 mature miRNAs, to be up-regulated in resistant cells, with miRNA-519a being the most highly up-regulated. We could demonstrate that miRNA-519a regulates tamoxifen resistance using gain- and loss-of-function testing. By combining functional enrichment analysis and prediction algorithms, we identified three central tumour-suppressor genes (TSGs) in PI3K signalling and the cell cycle network as direct target genes of miR-519a. Combined expression of these target genes correlated with disease-specific survival in a cohort of tamoxifen-treated patients. We identified miRNA-519a as a novel oncomir in ER+ breast cancer cells as it increased cell viability and cell cycle progression as well as resistance to tamoxifen-induced apoptosis. Finally, we could show that elevated miRNA-519a levels were inversely correlated with the target genes' expression and that higher expression of this miRNA correlated with poorer survival in ER+ breast cancer patients. Hence we have identified miRNA-519a as a novel oncomir, co-regulating a network of TSGs in breast cancer and conferring resistance to tamoxifen. Using inhibitors of such miRNAs may serve as a novel therapeutic approach to combat resistance to therapy as well as proliferation and evasion of apoptosis in breast cancer.