11,604 research outputs found
Multi-wavelength Signatures of Cosmic Rays in the Milky Way
Cosmic rays (CRs) propagate in the Milky Way and interact with the
interstellar medium and magnetic fields. These interactions produce emissions
that span the electromagnetic spectrum, and are an invaluable tool for
understanding the intensities and spectra of CRs in distant regions, far beyond
those probed by direct CR measurements. We present updates on the study of CR
properties by combining multi-frequency observations of the interstellar
emission and latest CR direct measurements with propagation models.Comment: 8 pages, 4 figures. Proceedings of the 35th International Cosmic Ray
Conference, ICRC201
Memory device for two-dimensional radiant energy array computers
A memory device for two dimensional radiant energy array computers was developed, in which the memory device stores digital information in an input array of radiant energy digital signals that are characterized by ordered rows and columns. The memory device contains a radiant energy logic storing device having a pair of input surface locations for receiving a pair of separate radiant energy digital signal arrays and an output surface location adapted to transmit a radiant energy digital signal array. A regenerative feedback device that couples one of the input surface locations to the output surface location in a manner for causing regenerative feedback is also include
Biochemical processes in sagebrush ecosystems: Interactions with terrain
The objectives of a biogeochemical study of sagebrush ecosystems in Wyoming and their interactions with terrain are as follows: to describe the vegetational pattern on the landscape and elucidate controlling variables, to measure the soil properties and chemical cycling properties associated with the vegetation units, to associate soil properties with vegetation properties as measured on the ground, to develop remote sensing capabilities for vegetation and surface characteristics of the sagebrush landscape, to develop a system of sensing snow cover and indexing seasonal soil to moisture; and to develop relationships between temporal Thematic Mapper (TM) data and vegetation phenological state
Galactic annihilation emission from nucleosynthesis positrons
The Galaxy hosts a widespread population of low-energy positrons revealed by
successive generations of gamma-ray telescopes through a bright annihilation
emission from the bulge region, with a fainter contribution from the inner
disk. The exact origin of these particles remains currently unknown. We
estimate the contribution to the annihilation signal of positrons generated in
the decay of radioactive 26Al, 56Ni and 44Ti. We adapted the GALPROP
propagation code to simulate the transport and annihilation of radioactivity
positrons in a model of our Galaxy. Using plausible source spatial
distributions, we explored several possible propagation scenarios to account
for the large uncertainties on the transport of ~1MeV positrons in the
interstellar medium. We then compared the predicted intensity distributions to
the INTEGRAL/SPI observations. We obtain similar intensity distributions with
small bulge-to-disk ratios, even for extreme large-scale transport
prescriptions. At least half of the positrons annihilate close to their
sources, even when they are allowed to travel far away. In the high-diffusion,
ballistic case, up to 40% of them escape the Galaxy. In proportion, this
affects bulge positrons more than disk positrons because they are injected
further off the plane in a tenuous medium, while disk positrons are mostly
injected in the dense molecular ring. The predicted intensity distributions are
fully consistent with the observed longitudinally-extended disk-like emission,
but the transport scenario cannot be strongly constrained by the current data.
Nucleosynthesis positrons alone cannot account for the observed annihilation
emission in the frame of our model. An additional component is needed to
explain the strong bulge contribution, and the latter is very likely
concentrated in the central regions if positrons have initial energies in the
100keV-1MeV range.Comment: 16 pages, 7 figures, accepted for publication in A&
Mass spectrometry in structural and stereochemical problems. Part 178 - The electron-impact promoted fragmentation of 1,2-cyclohexene oxide
Mass spectra of 1,2-cyclohexane oxide and three deuterium labeled analog
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