We report on the decay to two photons of the χc0(13P0) charmonium resonance formed in p̄p interactions at Fermilab experiment E835. We have measured the product of branching ratios ...BR(χc0→p̄p)×BR(χc0→γγ)=(6.52±1.18(stat)+0.48−0.72(sys))×10−8. Using values from the 2002 PDG, this measurement leads to the partial width Γ(χc0→γγ)=2.9±0.9 keV.
Main text
The key comparison CCQM-K157 for the thickness measurement of HfO
2
films was performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance ...(CCQM). The aim of CCQM-K157 is to establish the measurement traceability and to ensure the equivalency in the measurement capability of national metrology institutes for the thickness measurement of HfO
2
films.
In this key comparison, the thicknesses of six HfO
2
films with the nominal thickness range from 0.7 nm to 6 nm were compared by x-ray photoelectron spectroscopy (XPS), x-ray reflectometry (XRR), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE) and medium energy ion scattering spectrometry (MEIS).
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The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Main text The key comparison CCQM-K157 for the thickness measurement of HfO2 films was performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance ...(CCQM). The aim of CCQM-K157 is to establish the measurement traceability and to ensure the equivalency in the measurement capability of national metrology institutes for the thickness measurement of HfO2 films. In this key comparison, the thicknesses of six HfO2 films with the nominal thickness range from 0.7 nm to 6 nm were compared by x-ray photoelectron spectroscopy (XPS), x-ray reflectometry (XRR), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE) and medium energy ion scattering spectrometry (MEIS). To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Microcephaly is often caused by an impairment of the generation of neurons in the brain, a process referred to as neurogenesis. While most neurogenesis in mammals occurs during brain development, it ...thought to continue to take place through adulthood in selected regions of the mammalian brain, notably the hippocampus. However, the generality of neurogenesis in the adult brain has been controversial. While studies in mice and rats have provided compelling evidence for neurogenesis occurring in the adult rodent hippocampus, the lack of applicability in humans of key methods to demonstrate neurogenesis has led to an intense debate about the existence and, in particular, the magnitude of neurogenesis in the adult human brain. Here, we demonstrate the applicability of a powerful method to address this debate, that is, the in vivo labeling of adult human patients with 15 N-thymidine, a non-hazardous form of thymidine, an approach without any clinical harm or ethical concerns. 15 N-thymidine incorporation into newly synthesized DNA of specific cells was quantified at the single-cell level with subcellular resolution by Multiple-isotype imaging mass spectrometry (MIMS) of brain tissue resected for medical reasons. Two adult human patients, a glioblastoma patient and a patient with drug-refractory right temporal lobe epilepsy, were infused for 24 h with 15 N-thymidine. Detection of 15 N-positive leukocyte nuclei in blood samples from these patients confirmed previous findings by others and demonstrated the appropriateness of this approach to search for the generation of new cells in the adult human brain. 15 N-positive neural cells were easily identified in the glioblastoma tissue sample, and the range of the 15 N signal suggested that cells that underwent S-phase fully or partially during the 24 h in vivo labeling period, as well as cells generated therefrom, were detected. In contrast, within the hippocampus tissue resected from the epilepsy patient, none of the 2,000 dentate gyrus neurons analyzed was positive for 15 N-thymidine uptake, consistent with the notion that the rate of neurogenesis in the adult human hippocampus is rather low. Of note, the likelihood of detecting neurogenesis was reduced because of (i) the low number of cells analyzed, (ii) the fact that hippocampal tissue was explored that may have had reduced neurogenesis due to epilepsy, and (iii) the labeling period of 24 h which may have been too short to capture quiescent neural stem cells. Yet, overall, our approach to enrich NeuN-labeled neuronal nuclei by FACS prior to MIMS analysis provides a promising strategy to quantify even low rates of neurogenesis in the adult human hippocampus after in vivo 15 N-thymidine infusion. From a general point of view and regarding future perspectives, the in vivo labeling of humans with 15 N-thymidine followed by MIMS analysis of brain tissue constitutes a novel approach to study mitotically active cells and their progeny in the brain, and thus allows a broad spectrum of studies of brain physiology and pathology, including microcephaly.
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