2,017 research outputs found

    Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions

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    An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium emission has been evidenced and attributed both to entrance channel effects favoured by the cluster nature of reaction partners and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.Comment: 4 pages, 2 figures, Contribution to conference proceedings of the 25th International Nuclear Physics Conference (INPC 2013

    HNF1B polymorphism influences the prognosis of endometrial cancer patients: A cohort study

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    Background: HNF1B (formerly known as TCF2) gene encodes for a transcription factor that regulates gene expression involved in normal mesodermal and endodermal developments. A close association between rs4430796 polymorphism of HNF1B gene and decreased endometrial cancer (EC) risk has been demonstrated. The aim of the current study was to test the hypothesis that rs4430796 polymorphism can influence the prognosis of EC patients. Methods: Retrospective cohort study. Clinical and pathological data were extrapolated and genotypes were assessed on formalin-fixed and paraffin-embedded non-tumour tissues. The influence of patients' genotype on overall survival and progression free survival were our main outcome measures. Results: A total of 191 EC patients were included in the final analysis. Overall survival differed significantly (P = 0.003) among genotypes. At multivariate analysis, a significant (P < 0.05) effect on overall survival was detected for FIGO stage, and rs4430796 polymorphism of HNF1B gene. After grouping EC patients according to adjuvant treatment, rs4430796 polymorphism resulted significantly (P < 0.001) related to overall survival only in subjects who received radiotherapy plus chemotherapy. A significant (P = 0.014) interaction between rs4430796 polymorphism and chemo-radiotherapy was also detected. Finally, only a trend (P = 0.090) towards significance was observed for rs4430796 polymorphism effect on progression free survival. Conclusions: rs4430796 polymorphism of HNF1B gene influences independently the prognosis of EC patients with a potential effect on tumor chemo-sensitivity

    Polymorphisms in cyclooxygenase-2 gene in endometrial cancer patients

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    The enzyme cyclooxygenase 2 is an inducible enzyme expressed at sites of inflammation and in a variety of malignant solid tumors such as endometrial cancer (EC). In EC patients, its over-expression is correlated with progressive disease and poor prognosis. The expression is encoded by a polymorphic gene, called PTGS2. The aim of the current study was to test the hypothesis that rs5275 polymorphism of PTGS2 influence the prognosis of EC patients. This paper is a retrospective cohort study. Clinical and pathological data were extrapolated and genotypes were assessed on formalin-fixed and paraffin-embedded non-tumor tissues. A total of 159 type I EC patients were included in the final analysis. Univariate analysis indicated that patients with rs5275 genotype CC have a lower risk to develop a grade (G) 2–3 endometrial cancer. rs5275 effect on EC grading was confirmed by multivariate analysis also after data adjusting for age, BMI, parity, hypertension, and diabetes. Adjusted odds ratio (OR) confirmed that patients with rs5275 genotype CC have a risk 80 % lower (OR = 0.20, P = 0.009) to develop a G2 and/or G3 EC in comparison with patients with TT or TC genotype. Differentiation of the type 1 EC is significantly and independently influenced by rs5275 polymorphism. rs5275 CC patients have a lower risk to present a G2–G3 EC

    Non-statistical decay and α\alpha-correlations in the 12^{12}C+12^{12}C fusion-evaporation reaction at 95 MeV

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    Multiple alpha coincidence and correlations are studied in the reaction 12^{12}C+12^{12}C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with α\alpha-particles are addressed, which are associated with anomalously high branching ratios with respect the predictions by Hauser-Feshbach calculations. Triple alpha emission appears kinematically compatible with a sequential emission from a highly excited Mg. The phase space distribution of α\alpha-α\alpha coincidences suggests a correlated emission from a Mg compound, leaving an Oxygen residue excited above the threshold for neutron decay. These observations indicate a preferential α\alpha emission of 24^{24}Mg at excitation energies well above the threshold for 6−α6-\alpha decay.Comment: 21 pages, 17 figures, second paper of a series of tw

    From light to heavy nuclear systems, production and decay of fragments studied with powerful arrays

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    Reactions between heavy-ions at various energy regimes produce many nuclear fragments which can be populated in highly excited states. The study of these fragments, detected at the end of their particle decay, is important to investigate nuclear forces and structure effects. In recent years there have been many efforts to extend these studies towards the drip-lines, i.e. to systems far from the ÎČ-stability valley, by using accelerated radioactive beams. The development of such infrastructures is accompanied by the development of more powerful detectors and associated electronics, capable to identify ions with very different sizes and kinetic energies. Here we give two examples which show how advanced arrays can contribute to the studies on nuclear phenomena. The examples come from the European FAZIA collaboration and from recent campaigns with the GARFIELD apparatus, the latter in operation at the INFN Legnaro Laboratory (Italy) where the SPES RIB facility is under construction

    Pre-equilibrium emission and its possible relation to α-clustering in nuclei

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    The study of nuclear states built on clusters bound by valence neutrons in their molecular configurations is a field of large interest. Clustering becomes particularly important at the dripline, where weakly bound systems prevail. For light nuclei, at an excitation energy close to the particle separation value, there are experimental evidences of such structure effects, but this is still not the case for heavier nuclear systems. Several theoretical efforts have been done in the development of pre-formation alpha-clustering models, but there is still a lack of experimental data capable to give a direct feedback. The search of alpha-cluster evidences in medium-mass systems is therefore a new challenge which can give new hints in this field of research

    Search for supersymmetry in events with photons and missing transverse energy in pp collisions at 13 TeV

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    Peer reviewe

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an