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Sökning: WFRF:(Steer S.)

  • Resultat 1-10 av 93
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  • Romagnoni, A, et al. (författare)
  • Comparative performances of machine learning methods for classifying Crohn Disease patients using genome-wide genotyping data
  • 2019
  • Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 10351-
  • Tidskriftsartikel (refereegranskat)abstract
    • Crohn Disease (CD) is a complex genetic disorder for which more than 140 genes have been identified using genome wide association studies (GWAS). However, the genetic architecture of the trait remains largely unknown. The recent development of machine learning (ML) approaches incited us to apply them to classify healthy and diseased people according to their genomic information. The Immunochip dataset containing 18,227 CD patients and 34,050 healthy controls enrolled and genotyped by the international Inflammatory Bowel Disease genetic consortium (IIBDGC) has been re-analyzed using a set of ML methods: penalized logistic regression (LR), gradient boosted trees (GBT) and artificial neural networks (NN). The main score used to compare the methods was the Area Under the ROC Curve (AUC) statistics. The impact of quality control (QC), imputing and coding methods on LR results showed that QC methods and imputation of missing genotypes may artificially increase the scores. At the opposite, neither the patient/control ratio nor marker preselection or coding strategies significantly affected the results. LR methods, including Lasso, Ridge and ElasticNet provided similar results with a maximum AUC of 0.80. GBT methods like XGBoost, LightGBM and CatBoost, together with dense NN with one or more hidden layers, provided similar AUC values, suggesting limited epistatic effects in the genetic architecture of the trait. ML methods detected near all the genetic variants previously identified by GWAS among the best predictors plus additional predictors with lower effects. The robustness and complementarity of the different methods are also studied. Compared to LR, non-linear models such as GBT or NN may provide robust complementary approaches to identify and classify genetic markers.
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  • Wang, F., et al. (författare)
  • Reinvestigation of the excited states in the proton emitter Lu-151 : Particle-hole excitations across the N = Z=64 subshell
  • 2017
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 96:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The excited states of the proton emitter Lu-151 were reinvestigated in a recoil-decay tagging experiment at the Accelerator Laboratory of the University of Jyvaskyla (JYFL). The level scheme built on the ground state of 151Lu was updated with five new y-ray transitions. Large-scale shell model calculations were carried out in the model space consisting of the neutron and proton orbitals 0g(7/2), Id(5/2), Id(3/2), 2s(1/2), and Oh(1/2) with the optimized monopole interaction in order to interpret the experimental level scheme of Lu-151. It is found that the excitation energies of states above the 27/2(-) and 23/2(+) isomeric levels in Lu-151 can be sensitive to excitations from g(7/2) and d(5/2) to single-particle orbitals above N = Z = 64.
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  • Wang, F., et al. (författare)
  • Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu
  • 2017
  • Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 770, s. 83-87
  • Tidskriftsartikel (refereegranskat)abstract
    • The quenching of the experimental spectroscopic factor for proton emission from the short-lived d3/2 isomeric state in 151mLu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15.4(8) μs, respectively, in agreement with another recent study. These new experimental data can resolve the discrepancy in the spectroscopic factor calculated using the spherical WKB approximation. Using the R-matrix approach it is found that the proton formation probability indicates no significant hindrance for the proton decay of 151mLu.
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  • Lalkovski, S., et al. (författare)
  • Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126
  • 2013
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 034308-
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-rich silver isotopes were populated in the fragmentation of a Xe-136 beam and the relativistic fission of U-238. The fragments were mass analyzed with the GSI Fragment Separator and subsequently implanted into a passive stopper. Isomeric transitions were detected by 105 high-purity germanium detectors. Eight isomeric states were observed in Ag122-126 nuclei. The level schemes of Ag-122,Ag-123,Ag-125 were revised and extended with isomeric transitions being observed for the first time. The excited states in the odd-mass silver isotopes are interpreted as core-coupled states. The isomeric states in the even-mass silver isotopes are discussed in the framework of the proton-neutron split multiplets. The results of shell-model calculations, performed for the most neutron-rich silver nuclei are compared to the experimental data.
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  • Steer, S. J., et al. (författare)
  • Isomeric Decay Studies In Neutron-Rich N Approximate To 126 Nuclei
  • 2009
  • Ingår i: International Journal Of Modern Physics E-Nuclear Physics. - 0218-3013. ; 18:4, s. 1002-1007
  • Konferensbidrag (refereegranskat)abstract
    • Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A= 1 GeV Pb-208 beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed. rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z=73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N=126 closed shell nuclei.
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  • Söderström, Pär-Anders, et al. (författare)
  • Spectroscopy of neutron-rich Dy-168,Dy-170 : Yrast band evolution close to the NpNn valence maximum
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:3, s. 034310-
  • Tidskriftsartikel (refereegranskat)abstract
    • The yrast sequence of the neutron-rich dysprosium isotope Dy-168 has been studied using multinucleon transfer reactions following collisions between a 460-MeV Se-82 beam and an Er-170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2(+) and 4(+) members of the previously measured ground-state rotational band of Dy-168 have been confirmed and the yrast band extended up to 10(+). A tentative candidate for the 4(+) -> 2(+) transition in Dy-170 was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.
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  • Resultat 1-10 av 93

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