Neurogenesis continues throughout adulthood in discrete regions. Proliferative zones include the subependymal zone, from where progenitors migrate along the rostral migratory pathway to differentiate ...into neurons in the olfactory bulb, and the hippocampal subgranular zone, where they migrate and differentiate into granule neurons. Progenitors isolated from adult subependymal zone exhibit in vitro neurogenesis when stimulated with epidermal or fibroblast growth factor. Cultured adult rat hippocampal progenitors (AHPs) grafted to adult rat hippocampus show site-specific neuronal differentiation. Here we investigate determinants of multipotentiality in the adult central nervous system, by grafting AHPs into homotypic (hippocampus) or heterotypic (the rostral migratory pathway) neurogenic sites or a heterotypic, non-neurogenic site (the cerebellum). We found that grafts into neurogenic, but not nonneurogenic sites, showed neuronal differentiation. Furthermore, AHPs grafted in the rostral migratory pathway migrated into the olfactory bulb, differentiating into tyrosine-hydroxylase-positive neurons, a non-hippocampus phenotype. These results reveal that AHP populations can respond to persistent neuronal differentiation cues in the adult central nervous system.
Abstract The first direct determination of the ground-state-to-ground-state $${\beta ^{-}}$$ β - -decay Q -value of $$^{77}$$ 77 As to $$^{77}$$ 77 Se was performed by measuring their atomic mass ...difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The resulting Q -value is 684.463(70) keV, representing a remarkable 24-fold improvement in precision compared to the value reported in the most recent Atomic Mass Evaluation (AME2020). With the significant reduction of the uncertainty of the ground-state-to-ground-state Q -value and knowledge of the excitation energies in $$^{77}$$ 77 Se from $$\gamma $$ γ -ray spectroscopy, the ground-state-to-excited-state Q -value of the transition $$^{77}$$ 77 As (3/2 $$^{-}$$ - , ground state) $$\rightarrow $$ → $$^{77}$$ 77 Se $$^{*}$$ ∗ (5/2 $$^{+}$$ + , 680.1035(17) keV) was refined to be 4.360(70) keV. We confirm that this potential low Q -value $${\beta ^{-}}$$ β - -decay transition for neutrino mass determination is energetically allowed at a confidence level of about 60 $$\sigma $$ σ . Nuclear shell-model calculations with two well-established effective Hamiltonians were used to estimate the partial half-life for the low Q -value transition. The half-life was found to be of the order of 10 $$^{9}$$ 9 years for this first-forbidden non-unique transition. Since the half-life of $$^{77}$$ 77 As is only $$\approx $$ ≈ 2 days, usage of it as source for rare-event experiments searching for the electron antineutrino mass would be challenging.
Problems in species recognition are thought to affect the evolution of secondary sexual characters mainly through avoidance of maladaptive hybridization. Another, but much less studied avenue for the ...evolution of sexual characters due to species recognition problems is through interspecific aggression. In the damselfly, Calopteryx splendens, males have pigmented wing spots as a sexual character. Large‐spotted males resemble males of another species, Calopteryx virgo, causing potential problems in species recognition. In this study, we investigate whether there is character displacement in wing spot size and whether interspecific aggression could cause this pattern. We found first that wing spot size of C. splendens in populations decreased with increasing relative abundance of C. virgo. Secondly, C. virgo males were more aggressive towards large‐ than small‐spotted C. splendens males. Thirdly, in interspecific contests C. virgo males had better territory holding ability than C. splendens males. These results suggest that interspecific aggression may have caused character displacement in wing spot size of C. splendens, because the intensity of aggression towards large‐spotted males is likely to increase with relative abundance of C. virgo males. Thus, interspecific aggression may be an evolutionarily significant force that is able to cause divergence in secondary sexual characters.
Isomeric states in 128In and 130In have been studied with the JYFLTRAP Penning trap at the IGISOL facility. By employing state-of-the-art ion manipulation techniques, three different beta-decaying ...states in 128In and 130In have been separated and their masses measured. JYFLTRAP was also used to select the ions of interest for identification at a post-trap decay spectroscopy station. A new beta-decaying high-spin isomer feeding the 15− isomer in 128Sn has been discovered in 128In at 1797.6(20) keV. Shell-model calculations employing a CD-Bonn potential re-normalized with the perturbative G-matrix approach suggest this new isomer to be a 16+ spin-trap isomer. In 130In, the lowest-lying (10−) isomeric state at 58.6(82) keV was resolved for the first time using the phase-imaging ion cyclotron resonance technique. The energy difference between the 10− and 1− states in 130In, stemming from parallel/antiparallel coupling of (π0g9/2−1)⊗(ν0h11/2−1), has been found to be around 200 keV lower than predicted by the shell model. Precise information on the energies of the excited states determined in this work is crucial for producing new improved effective interactions for the nuclear shell model description of nuclei near 132Sn.
In this paper we analyze the ground-state-to-ground-state two-neutrino double beta (2νββ) decays and single EC and β− decays for the A=100 (100Mo–100Tc–100Ru), A=116 (116Cd–116In–116Sn) and A=128 ...(128Te–128I–128Xe) triplets of isobars. We use the proton–neutron quasiparticle random-phase approximation (pnQRPA) with realistic G-matrix-derived effective interactions in very large single-particle bases. The purpose is to access the effective value of the axial-vector coupling constant gA in the pnQRPA calculations. We show that the three triplets of isobars represent systems with different characteristics of orbital occupancies and cumulative 2νββ nuclear matrix elements. Our analysis points to a considerably quenched averaged effective value of 〈gA〉≈0.6±0.2 in the pnQRPA calculations.
Neutrinos from supernovae constitute important probes of both the currently unknown supernova mechanisms and of neutrino properties. Reliable information about the nuclear responses to supernova ...neutrinos is therefore crucial. In this work, we compute the cross sections for the charged-current neutrino-nucleus scattering off the even-even molybdenum isotopes. The nuclear responses to supernova neutrinos are subsequently calculated by folding the cross sections with a Fermi-Dirac distribution.
The ACCESS (Array of Cryogenic Calorimeters to Evaluate Spectral Shapes) project aims to establish a novel technique to perform precision measurements of forbidden
β
-decays, which can serve as an ...important benchmark for nuclear physics calculations and represent a significant background in astroparticle physics experiments. ACCESS will operate a pilot array of cryogenic calorimeters based on natural and doped crystals containing
β
-emitting radionuclides. In this way, natural (e.g.
113
Cd and
115
In) and synthetic isotopes (e.g.
99
Tc) will be simultaneously measured with a common experimental technique. The array will also include further crystals optimised to disentangle the different background sources, thus reducing the systematic uncertainty. In this paper, we give an overview of the ACCESS research program, discussing a detector design study and promising results of
115
In.
For neutrino detection and for various applications in astrophysics the knowledge of the nuclear responses to astrophysical neutrinos is crucial. Recent studies of neutrino interactions with the ...100Mo nucleus and the other stable molybdenum isotopes are important for the planned MOON (Mo Observatory of Neutrinos) detector. To this aim, in the present work we perform detailed nuclear structure calculations for the neutral-current neutrino–nucleus scattering off the stable molybdenum isotopes. We focus on the differential and total neutrino–nucleus cross sections as well as on flux averaged cross sections to various supernova neutrino spectra. We also propose a more efficient method for the computations of the corresponding nuclear matrix elements. By employing this method we extend our previous calculations for the odd isotopes (95Mo and 97Mo) where also couplings to high-lying QRPA (quasiparticle random-phase approximation) phonons are included in the quasiparticle-phonon basis. It is established in this work that the inclusion of high-lying QRPA excitations are essential for the description of the neutrino–nucleus scattering off open-shell odd-mass nuclei.
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