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Carbon fusion reactions $$^{12}$$ 12 C($$^{12}$$ 12 C,p)$$^{23}$$ 23 Na and $$^{12}$$ 12 C($$^{12}$$ 12 C,$$\alpha $$ α )$$^{20}$$ 20 Ne play a key role in the evolution of massive stars and in explosive scenarios such as type-Ia supernovae and super-bursts in binary stars. A direct determination of their cross sections is extremely challenging and discrepancies exist between different data sets in the literature. Here we report the results of a direct measurement performed at the CIRCE Tandem Accelerator Laboratory in Caserta (Italy), using $$\varDelta E-E$$ Δ E - E detectors for unambiguous charge identification. Cross sections were measured in the energy range $$E_{\mathrm{c.m.}} =2.51{-}4.36$$ E c . m . = 2.51 - 4.36 MeV with energy steps between 10 and 25 keV in the centre of mass. To our knowledge these represent the finest energy steps to date. Results are presented in the form of partial and summed astrophysical $${\tilde{S}}$$ S ~ -factors for individual proton- and $$\alpha $$ α -particle channels. Branching ratios of individual proton- and $$\alpha $$ α -particle groups were found to vary significantly with energy. Angular distributions, albeit limited to three angles, were also found to be non-isotropic, which could be a potential explanation for the discrepancies observed among different data sets. Further efforts are ongoing to extend measurements to lower energies.

Mesenchymal stromal cells (MSCs) have been shown to reverse radiation damage to marrow stem cells. We have evaluated the capacity of MSC-derived extracellular vesicles (MSC-EVs) to mitigate radiation injury to marrow stem cells at 4 h to 7 days after irradiation. Significant restoration of marrow stem cell engraftment at 4, 24 and 168 h post irradiation by exposure to MSC-EVs was observed at 3 weeks to 9 months after transplant and further confirmed by secondary engraftment. Intravenous injection of MSC-EVs to 500cGy exposed mice led to partial recovery of peripheral blood counts and restoration of the engraftment of marrow. The murine hematopoietic cell line, FDC-P1 exposed to 500cGy, showed reversal of growth inhibition, DNA damage and apoptosis on exposure to murine or human MSC-EVs. Both murine and human MSC-EVs reverse radiation damage to murine marrow cells and stimulate normal murine marrow stem cell/progenitors to proliferate. A preparation with both exosomes and microvesicles was found to be superior to either microvesicles or exosomes alone. Biologic activity was seen in freshly isolated vesicles and in vesicles stored for up to 6 months in 10% dimethyl sulfoxide at -80 °C. These studies indicate that MSC-EVs can reverse radiation damage to bone marrow stem cells.

Marrow stem cell regulation represents a complex and flexible system. It has been assumed that the system was intrinsically hierarchical in nature, but recent data has indicated that at the progenitor/stem cell level the system may represent a continuum with reversible alterations in phenotype occurring as the stem cells transit cell cycle. Short and long-term engraftment, in vivo and in vitro differentiation, gene expression, and progenitor numbers have all been found to vary reversibly with cell cycle. In essence, the stem cells appear to show variable potential, probably based on transcription factor access, as they proceed through cell cycle. Another critical component of the stem cell regulation is the microenvironment, so-called niches. We propose that there are not just several unique niche cells, but a wide variety of niche cells which continually change phenotype to appropriately interact with the continuum of stem cell phenotypes. A third component of the regulatory system is microvesicle transfer of genetic information between cells. We have shown that marrow cells can express the genetic phenotype of pulmonary epithelial cells after microvesicle transfer from lung to marrow cells. Similar transfers of tissue specific mRNA occur between liver, brain, and heart to marrow cells. Thus, there would appear to be a continuous genetic modulation of cells through microvesicle transfer between cells. We propose that there is an interactive triangulated Venn diagram with continuously changing stem cells interacting with continuously changing areas of influence, both being modulated by transfer of genetic information by microvesicles.

Adult marrow hematopoiesis has been felt to represent a classical hierarchical system with a primitive stem cell progressively differentiating into hematopoietic cells. Colony-forming unit spleen was the initial stem cell and there followed definition of a wide variety of progenitors with different lineage potentials. Purification studies indicated that the critical stem cells were lineage negative and Sca-1+c-kit+CD150+.1 Our studies over the past decade indicate that the phenotype of the stem cell changes reversibly with cell cycle transit. Characteristics showing such changes include long-term multilineage engraftment into irradiated mice, differentiation, homing to marrow, expression of adherence proteins and global gene expression, progenitor phenotype and uptake of extracellular vesicles. It was demonstrated that most stem cells are discarded during the separation. The final purified stem cell is in fact dormant, but the vast majority of stem cells that are discarded (over 90%) are in active cell cycle.2 In these studies it was shown that cells in S/G2/M accounted for over 50% of long-term engraftment of whole unseparated marrow and that the classical purified lineage-negative Sca-1-c-kit+CD150+ stem cell rapidly progressed through the cell cycle so that after 48 h exposure to in vivo bromodeoxyuridine up to 80% of the ‘dormant' cells incorporated bromodeoxyuridine. These data indicated that most mature marrow stem cells were discarded with the purification and that these cells were virtually all proliferating. Studies on the different fractions of a purification indicated that the vast majority of adult marrow stem cells were present in the lineage-positive and lineage-negative populations and that these cells were cycling. Thus, the true marrow stem cells rapidly transited the cell cycle and were continually changing phenotype; they could not be ‘purified' by assessing a set number of epitopic markers. The bulk of studies on murine marrow stem cells has been carried out on ‘purified stem cells' and thus have been addressing an irrelevant population of cells. These studies need to be readdressed. Further heterogeneity of adult marrow stem cells is introduced by considerations of interactions of these cells with extracellular vesicles.3 Studies on lineage-negative Sca-1+ progenitor/stem cells traversing the cell cycle under cytokine stimulation in liquid culture indicated that vesicle uptake varied with both the cell cycle state of the target cell and the nature of treatment of the originator lung cells (irradiation or no irradiation). Thus the adult marrow stem cell continually alters phenotype with cell cycle transit and this is further impacted upon by interactions with vesicles from a variety of cell types. The cell phenotype induced by vesicle exposure appears to be a stable epigenetic change induced by an RNase-sensitive agent that is not messenger RNA, presumably a non-coding RNA species. These observations suggest unique strategies for determination of cell fate and restoration of damaged cells. These data also suggest that while cell populations may be stable at the tissue or population level they are not stable at the individual cell level.

This study explores the utility of psychological content analysis in studying judicial behavior. Justices' testimony before the Senate Judiciary Committee was scored for power, achievement, and affiliation imagery using content analysis techniques developed by Winter (1982a). The results suggest that motivational content analysis may provide a more direct means of assessing the relationship between judges' psychological disposition and their decision making behavior. Combinations of motive imagery variables and social background variables explained between 64% and 83% of the variation in writing opinions and in casting concurring and dissenting votes among U.S. Supreme Court justices.

The electron screening in the d(d,p)t reaction has been studied for the deuterated metal Pt at a target temperature T = 20 degrees C to 340 degrees C, and for Co at T = 20 degrees C and 200 degrees C. The enhanced electron screening decreases with increasing temperature, where the data agree with the plasma model of Debye applied to the quasi-free metallic electrons. The data represent the first observation of a temperature dependence of a nuclear cross-section. We also measured the screening effect for the deuterated metal Ti (an element of group 4 of the periodic table) at T = -10 degrees C to 200 degrees C: above 50 degrees C the hydrogen solubility dropped to values far below unity and a large screening effect became observable. Similarly, all metals of groups 3 and 4 and the lanthanides showed a solubility of a few percent at T = 200 degrees C (compared to T = 20 degrees C) and a large screening became also observable. Within the Debye model the deduced number of valence electrons per metallic atom agrees with the corresponding number from the Hall coefficient, for all metals investigated. RI Fulop, Zsolt/B-2262-2008; Aliotta, Marialuisa /H-2567-2012

An excitation function of the ground-state gamma (0)-ray capture transition in C-12(alpha, gamma)O-16 at theta (gamma) = 90 degrees was obtained in far geometry using six Ge detectors, where the study of the reaction was initiated in inverse kinematics involving a windowless gas target. The detectors observed predominantly the El capture amplitude. The data at E = 1.32 to 2.99 MeV lead to an extrapolated astrophysical S factor S-E1(E-0) = 90 +/- 15 keV b at E-0 = 0.3 MeV (for the case of constructive interference between the two lowest E1 sources), in good agreement with previous works. However, a novel Monte Carlo approach in the data extrapolation reveals systematic differences between the various data sets such that a combined analysis of all available data sets could produce a biased estimate of the S-E1(E-0) value. As a consequence, the case of destructive interference between the two lowest E1 sources with S-E1(E-0) = 8 +/- 3 keV b cannot be ruled out rigorously.

For improved measurements of the key astrophysical reaction C-12(alpha, gamma)O-16 in inverted kinematics, a recoil separator ERNA is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the O-16 recoils with about 50% efficiency. Calculations of the ion beam optics including all filtering and focusing elements of ERNA are presented. Since the C-12 projectiles and the O-16 recoils have essentially the same momentum, and since the C-12 ion beam emerging from the accelerator passes through a momentum filter (analysing magnet), the C-12 ion beam must be as free as possible from O-16 contamination for ERNA to succeed. In the present work, the O-16 contamination was reduced from a level of 1 x 10(-11) to a level below 2 x 10(-29) by the installation of Wien filters both before and after the analysing magnet. The measurement of these and other beam specifications involved other parts of the final ERNA layout - sequentially a Wien filter, a 60 degrees dipole magnet, another Wien filter, and a Delta E-E telescope. The setup led to a measured suppression factor of 5 x 10(-18) for the C-12 ion beam. The experiments also indicate that an almost free choice of the charge state for the O-16 recoils is possible in the separator.