640 research outputs found
Surface scattering characteristics and the measurement of particulate contamination
Surface scattering measurement techniques can be adopted for use in spacecraft contamination control programs. A witness mirror measurement program was developed and implemented for the NASA Cosmic Background Explorer (COBE) spacecraft. Scattering measurements were obtained before and after a qualification level vibration test for several COBE prototype instruments. The measurements indicate that a significant amount of particle redistribution occurred during the vibration test. The methodology used and the results obtained from this monitoring program are discussed
Simulating Nelsonian Quantum Field Theory
We describe the picture of physical processes suggested by Edward Nelson's
stochastic mechanics when generalized to quantum field theory, after an
introductory review of his theory applied to the hydrogen atom. By performing
numerical simulations of the relevant stochastic processes, we observe that
Nelson's theory provides an intuitive account of how particles can arise from
an underlying field ``beable'' -- to use a phrase of John S. Bell -- in the
case of free field theory, regularized on a lattice. We then argue that this
picture looks qualitatively similar when generalized to interacting scalar
field theory. Lastly, we compare the Nelsonian framework to various other
proposed ontologies for QFT, and remark upon their relative merits in light of
the effective field theory paradigm
The Post-9/11 Security State
A “silent minority” until the end of the 20th century, Arab and Muslim Americans became, literally overnight, a "problem" ethnic group in the US consensus after the terrorist attacks of 9/11, when on the one hand Islamophobia was adopted as the leading trope of national grievance, while on the other a massive surveillance apparatus was put in place in order to ostensibly address the risk of internal radicalization, resulting in visible loss of civil rights for Arab and Muslim minorities in the US. This paper explores the deployment of the US security state against America Arabs and Muslims after 9/11, and sets it within the complex history of Middle Eastern and South Asian immigration to the US in the 20th century
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