5 research outputs found
Trap-integrated fluorescence detection based on silicon photomultipliers in a cryogenic Penning trap
We present a fluorescence-detection system for laser-cooled 9Be+ ions based
on silicon photomultipliers (SiPM) operated at 4 K and integrated into our
cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence
detection in a hermetically-sealed cryogenic Penning-trap chamber with limited
optical access, where state-of-the-art detection using a telescope and
photomultipliers at room temperature would be extremely difficult. We
characterize the properties of the SiPM in a cryocooler at 4 K, where we
measure a dark count rate below 1/s and a detection efficiency of 2.5(3) %. We
further discuss the design of our cryogenic fluorescence-detection trap, and
analyze the performance of our detection system by fluorescence spectroscopy of
9Be+ ion clouds during several runs of our experiment.Comment: 12 pages, 11 figure
Correlation of Transcriptomics and FDG-PET SUVmax Indicates Reciprocal Expression of Stemness-Related Transcription Factor and Neuropeptide Signaling Pathways in Glucose Metabolism of Ewing Sarcoma
Background: In Ewing sarcoma (EwS), long-term treatment effects and poor survival rates for relapsed or metastatic cases require individualization of therapy and the discovery of new treatment methods. Tumor glucose metabolic activity varies significantly between patients, and FDG-PET signals have been proposed as prognostic factors. However, the biological basis for the generally elevated but variable glucose metabolism in EwS is not well understood. Methods: We retrospectively included 19 EwS samples (17 patients). Affymetrix gene expression was correlated with maximal standardized uptake value (SUVmax) using machine learning, linear regression modelling, and gene set enrichment analyses for functional annotation. Results: Expression of five genes correlated (MYBL2, ELOVL2, NETO2) or anticorrelated (FAXDC2, PLSCR4) significantly with SUVmax (adjusted p-value ≤ 0.05). Additionally, we identified 23 genes with large SUVmax effect size, which were significantly enriched for “neuropeptide Y receptor activity (GO:0004983)” (adjusted p-value = 0.0007). The expression of the members of this signaling pathway (NPY, NPY1R, NPY5R) anticorrelated with SUVmax. In contrast, three transcription factors associated with maintaining stemness displayed enrichment of their target genes with higher SUVmax: RNF2, E2F family, and TCF3. Conclusion: Our large-scale analysis examined comprehensively the correlations between transcriptomics and tumor glucose utilization. Based on our findings, we hypothesize that stemness may be associated with increased glucose uptake, whereas neuroectodermal differentiation may anticorrelate with glucose uptake
Constraints on the Coupling between Axionlike Dark Matter and Photons Using an Antiproton Superconducting Tuned Detection Circuit in a Cryogenic Penning Trap
We constrain the coupling between axionlike particles (ALPs) and photons,
measured with the superconducting resonant detection circuit of a cryogenic
Penning trap. By searching the noise spectrum of our fixed-frequency resonant
circuit for peaks caused by dark matter ALPs converting into photons in the
strong magnetic field of the Penning-trap magnet, we are able to constrain the
coupling of ALPs with masses around to
. This is more than one
order of magnitude lower than the best laboratory haloscope and approximately 5
times lower than the CERN axion solar telescope (CAST), setting limits in a
mass and coupling range which is not constrained by astrophysical observations.
Our approach can be extended to many other Penning-trap experiments and has the
potential to provide broad limits in the low ALP mass range.Comment: 7 pages, 3 figure
Superconducting Solenoid System with Adjustable Shielding Factor for Precision Measurements of the Properties of the Antiproton
status: publishe
Superconducting Solenoid System with Adjustable Shielding Factor for Precision Measurements of the Properties of the Antiproton
A superconducting self-shielding three-solenoid system with an adjustable shielding factor is developed, implemented, and characterized using a single antiproton in a Penning trap. With the tuned system, we suppress external magnetic field disturbances by up to a factor of 225 ± 15, allowing antiproton-to-proton charge-to-mass ratio comparisons with fourfold reduced frequency fluctuations and antiproton magnetic moment determinations with tenfold reduced uncertainty