Publications by authors named "D W Cassidy"

We have measured the spin polarization of a slow positron beam via state-selective depopulation of 2^{3}S_{1} positronium atoms, generated by passing the beam through a gas cell. Our method employs circularly polarized microwave radiation to drive 2^{3}S_{1}→2^{3}P_{1} transitions, for which either Δm_{J}=+1 or Δm_{J}=-1, and relies on the fact that asymmetries between the two cases yield the underlying positron beam polarization. Using this technique we show that the polarization of a positron beam derived from a solid neon moderator may be increased from 30% to 90% by increasing the moderator thickness, with an associated reduction in beam intensity of 60%.

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Fatty acid oxidation is of uncertain importance in most stem cells. We show by C-palmitate tracing and metabolomic analysis that hematopoietic stem/progenitor cells (HSPCs) engage in long-chain fatty acid oxidation that depends upon carnitine palmitoyltransferase 1a (CPT1a) and hydroxyacyl-CoA dehydrogenase (HADHA) enzymes. CPT1a or HADHA deficiency had little or no effect on HSPCs or hematopoiesis in young adult mice.

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Article Synopsis
  • Ascorbate (vitamin C) decreases the function of hematopoietic stem cells (HSCs) and helps prevent leukemia by enhancing the activity of the Tet2 tumor suppressor.
  • Deleting the Slc23a2 transporter from hematopoietic cells caused a significant drop in ascorbate levels within HSCs and multipotent progenitors (MPPs) but did not affect overall plasma ascorbate levels.
  • This deficiency led to increased reconstitution and self-renewal capabilities of HSCs and MPPs when transplanted into irradiated mice, particularly in their quiescent states, indicating that low ascorbate levels may enhance their long-term potential.
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Fate and transport of per- and polyfluoroalkyl substances (PFAS) in wastewater treatment plant (WWTP) effluent discharged to rapid infiltration basins (RIBs) is investigated using data from 26 WWTPs in Michigan, USA. PFAS were found to accumulate in groundwater downgradient from RIBs with median groundwater-effluent enrichment factors for ten commonly detected, terminal-form perfluoroalkyl acids (PFAAs) ranging from 1.3 to 5.

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Most kidney cancers are metabolically dysfunctional, but how this dysfunction affects cancer progression in humans is unknown. We infused C-labelled nutrients in over 80 patients with kidney cancer during surgical tumour resection. Labelling from [U-C]glucose varies across subtypes, indicating that the kidney environment alone cannot account for all tumour metabolic reprogramming.

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