Chronic lymphocytic leukemia (CLL) is a frequent hematological neoplasm in which underlying epigenetic alterations are only partially understood. Here, we analyze the reference epigenome of seven ...primary CLLs and the regulatory chromatin landscape of 107 primary cases in the context of normal B cell differentiation. We identify that the CLL chromatin landscape is largely influenced by distinct dynamics during normal B cell maturation. Beyond this, we define extensive catalogues of regulatory elements de novo reprogrammed in CLL as a whole and in its major clinico-biological subtypes classified by IGHV somatic hypermutation levels. We uncover that IGHV-unmutated CLLs harbor more active and open chromatin than IGHV-mutated cases. Furthermore, we show that de novo active regions in CLL are enriched for NFAT, FOX and TCF/LEF transcription factor family binding sites. Although most genetic alterations are not associated with consistent epigenetic profiles, CLLs with MYD88 mutations and trisomy 12 show distinct chromatin configurations. Furthermore, we observe that non-coding mutations in IGHV-mutated CLLs are enriched in H3K27ac-associated regulatory elements outside accessible chromatin. Overall, this study provides an integrative portrait of the CLL epigenome, identifies extensive networks of altered regulatory elements and sheds light on the relationship between the genetic and epigenetic architecture of the disease.
AGATA is a modern
γ
-ray spectrometer for in-beam nuclear structure studies, based on
γ
-ray tracking. Since more than a decade, it has been operated performing experimental physics campaigns in ...different international laboratories (LNL, GSI, GANIL). This paper reviews the obtained results concerning the performances of
γ
-ray tracking in AGATA and associated algorithms. We discuss
γ
-ray tracking and algorithms developed for AGATA. Then, we present performance results in terms of efficiency and peak-to-total for AGATA. The importance of the high effective angular resolution of
γ
-ray tracking arrays is emphasised, e.g. with respect to Doppler correction. Finally, we briefly touch upon the subject of
γ
-ray imaging and its connection to
γ
-ray tracking.
Nuclear-structure studies using fusion reactions are reviewed in terms of prospects for advancement using the next generation of
γ
-ray tracking arrays such as AGATA. Properties discussed include ...those of light
N
=
Z
nuclei and rotational behaviour in heavy nuclei at high values of angular momentum and internal excitation energy.
The unprecedented capabilities of state-of-the-art segmented germanium-detector arrays, such as AGATA and GRETA, derive from the possibility of performing pulse-shape analysis. The comparison of the ...net- and transient-charge signals with databases via grid-search methods allows the identification of the
γ
-ray interaction points within the segment volume. Their precise determination is crucial for the subsequent reconstruction of the
γ
-ray paths within the array via tracking algorithms, and hence the performance of the spectrometer. In this paper the position uncertainty of the deduced interaction point is investigated using the bootstrapping technique applied to
60
Co radioactive-source data. General features of the extracted position uncertainty are discussed as well as its dependence on various quantities, e.g. the deposited energy, the number of firing segments and the segment geometry.
GABRIELA (Gamma Alpha Beta Recoil Investigations with the Electromagnetic Analyzer) is a detection system installed at the focal plane of the SHELS (Separator for Heavy Elements Spectroscopy) recoil ...separator for gamma and internal conversion electron spectroscopy of heavy and superheavy nuclei. GABRIELA has recently been upgraded. The characteristics of the new setup are presented using the
Geant4
Monte Carlo simulation toolkit and validated against experimental results. The impact of summing on the gamma-ray and electron detection efficiencies is discussed.
The current work discusses the experimental evaluation technique for the prompt neutron multiplicity distribution (PNMD) emitted is the spontaneous fission (SF). The restoring technique for the ...detector efficiency correction is shown as well as the comparison of two regularization parameter choice methods. The shape of the PNMD helps to achieve the information according the dynamic of the SF. The work also compiles all currently published PNMDs in the transfermium (Z > 100) region and discusses their shapes, providing a physical interpretation of the distortion of these distributions.
Fission hindrances in transfermium nuclei Lopez-Martens, A.; Hauschild, K.; Svirikhin, A.I. ...
EPJ Web of Conferences,
2023, Letnik:
290
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Very heavy nuclei owe their stability against spontaneous fission to quantum shell effects, which depend on the local density of single-particle states. The height but also the width and the ...structure of the barrier in multi-dimensional deformation space determine the fission half-lives. Other effects come into play, such as the conservation of quantum numbers and superfluidity or stiffness of the system in the fission process. This is why odd nuclei have longer fission partial half-lives with respect to their even neighbours and also why multi-quasi-particle states, such as high-K states, are thought to be more stable against fission than the ground state. We will report here on two different fission studies carried out with the GABRIELA detector array at the focal plane of the recoil separator SHELS. The first study concerns the fission properties of
253
Rf, the most neutron deficient Rf isotope known to date. The second study focusses on a new measurement of the fission hindrance of the known 8
-
isomer in
254
No.
Hematopoietic stem cell transplantation (HSCT) using umbilical cord blood (UCB) progenitors is increasingly being used. One of the problems that may arise after UCB transplantation is an impaired ...engraftment. Either intrabone (IB) injection of hematopoietic progenitors or mesenchymal stem cell (MSC) coadministration has been proposed among the strategies to improve engraftment. In the current study, we have assessed the effects of both approaches. Thus, NOD/SCID recipients were transplanted with human UCB CD34+ cells administered either intravenously (IV) or IB, receiving or not bone marrow (BM)-derived MSCs also IV or IB (in the right femur). Human HSC engraftment was measured 3 and 6 weeks after transplantation. Injected MSCs were tracked weekly by bioluminescence. Also, lodgment within the BM niche was assessed at the latter time point by immunofluorescence. Our study shows regarding HSC engraftment that the number of BM human CD45+ cells detected 3 weeks after transplantation was significantly higher in mice cotransplanted with human MSCs. Moreover, these mice had a higher myeloid (CD13+) engraftment and a faster B-cell (CD19+) chimerism. At the late time point evaluated (6 weeks), human engraftment was higher in the group in which both strategies were employed (IB injection of HSC and MSC coadministration). When assessing human MSC administration route, we were able to track MSCs only in the injected femurs, whereas they lost their signal in the contralateral bones. These human MSCs were mainly located around blood vessels in the subendosteal region. In summary, our study shows that MSC coadministration can enhance HSC engraftment in our xenogenic transplantation model, as well as IB administration of the CD34+ cells does. The combination of both strategies seems to be synergistic. Interestingly, MSCs were detected only where they were IB injected contributing to the vascular niche.
The spectrum of states in very heavy and super heavy nuclei is the result of a delicate balance between the strong Coulomb repulsion between the numerous protons in the nucleus and the properties of ...the strong force acting between the many nucleons in the system. Fine-structure
α
decay combined with
γ
-ray and internal-electron-conversion spectroscopy allows to identify the sequence and energies of low-lying nuclear states. This information can then be used to constrain the parameters that define the nuclear mean-field and thus improve the reliability of predictions in a region controlled critically by small shell effects. Detailed spectroscopy of transfermium nuclei is the prime motivation of the Franco-Russian GABRIELA (Gamma Alpha Beta Recoil Investigation with the ELectromagnetic Analyzer) project, launched more than 15 years ago. The current review aims at presenting the experimental developments that have been carried out over the years and discuss a selection of results that have been obtained.
The structure of the 102254No152 nucleus has been studied for more than 20 years: the last publications on its decay spectroscopy are from LBNL 1, GSI 2, JYFL 3 and ANL 4. Four decay schemes ...featuring two isomers have been published and are interpreted differently in terms of excitation energy and decay scheme of the 2nd isomer and configuration assignments of both K-isomers. These discrepancies have triggered new experiments including this one, performed with the GABRIELA 5, 6 array, at the focal plane of the SHELS 7 separator at the FLNR, Dubna. The first part of this proceeding will present the experimental setup and the analysis techniques used to reveal the electromagnetic decay of the known isomers in 254No. The second part will focus on the new results obtained with more than 1 million 254No nuclei implanted in the focal plane detector. In particular, the internal conversion electron spectrum observed in the decay of the 8− K-isomer has revealed the presence of a strong transition, most likely E0, suggesting low-lying shape coexistence in this nucleus as predicted in 8, 9. The γ-ray spectrum obtained from the decay of the short-lived 170 μs isomer has revealed new γ-ray lines putting in doubt the previous interpretations about this isomer decay.
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