Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite.

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Morphogenesis of the epidural space in humans during the embryonic and early fetal periods.

The development of the epidural space was studied on 51 series of sections from embryos and early fetuses aged from four to 13 weeks using histological and embryological methods for plastic and graphic reconstruction. We found that three stages can be discriminated in the development of the epidural space: I) the primary epidural space (embryos of 16-31 mm crown-rump length (CRL); II) reduction of the primary epidural space (embryos of 35-55 mm CRL); and III) the secondary epidural space (embryos of 60-70 mm CRL and fetuses of 80-90 mm CRL). The morphogenesis of the primary epidural space is determined by the formative influence of the spinal cord and its dura mater, while that of the secondary epidural space is determined by the walls of the vertebral canal. In the spinal cord-dura mater of the spinal cord-vertebral canal correlation system, the latter two components, subjected to the inducing influence of the first, determine the morphogenesis of the epidural space via a system of morphogenetic correlations. The correlational relationships are apparent as time-linked connections between the rudiment of the dura mater of the spinal cord and the vertebral canal, resulting in the stage-by-stage formation of the epidural space in the ventrodorsal and craniocaudal directions. These same morphogenetic correlations also determine the staging of the development of the epidural space.