RESUMO
Primordial black holes (PBHs) are a viable candidate for dark matter if the PBH masses are in the currently unconstrained "sublunar" mass range. We revisit the possibility that PBHs were produced by nucleation of false vacuum bubbles during inflation. We show that this scenario can produce a population of PBHs that simultaneously accounts for all dark matter, explains the candidate event in the Subaru Hyper Suprime-Cam (HSC) data, and contains both heavy black holes as observed by LIGO and very heavy seeds of supermassive black holes. We demonstrate with numerical studies that future observations of HSC, as well as other optical surveys, such as LSST, will be able to provide a definitive test for this generic PBH formation mechanism if it is the dominant source of dark matter.
RESUMO
In infant CT scans, it is important to minimize radiation exposure without lowering the quality of the diagnosis. Therefore, appropriate parameters for infant CT scan should be considered at each institute. In order to determine parameters for infant body CT, we measured the physical characteristics of our current CT machine and evaluated scan parameters as S.D. below 10 on the basis of literature recommendations, which say that we should adopt S.D. of the liver when treated with a radiation exposure dose in an adult abdominal CT scan. As a result, the ideal parameters were 90 kV tube voltage, ultra fast detail resolution, B kernel, and Eff.mAs value calculated from patient body width. Infant body CT scans with the mentioned parameters resulted in an S.D. below 10, and this is thought to be applicable to further examinations.
