A process-oriented language for describing aspects of reading comprehension

Includes bibliographical references (p. 36-38)The research described herein was supported in part by the National Institute of Education under Contract No. MS-NIE-C-400-76-011

Low-energy charge transfer for collisions of Si3+ with atomic hydrogen

Cross sections of charge transfer for Si3+ ions with atomic hydrogen at collision energies of ≈40–2500 eV/u were carried out using a merged-beam technique at the Multicharged Ion Research Facility at Oak Ridge National Laboratory. The data span an energy range in which both molecular orbital close coupling (MOCC) and classical trajectory Monte Carlo (CTMC) calculations are available. The influence of quantum mechanical effects of the ionic core as predicted by MOCC is clearly seen in our results. However, discrepancies between our experiment and MOCC results toward higher collision energies are observed. At energies above 1000 eV/u good agreement is found with CTMC results

Homotopy Theoretic Models of Type Theory

We introduce the notion of a logical model category which is a Quillen model category satisfying some additional conditions. Those conditions provide enough expressive power that one can soundly interpret dependent products and sums in it. On the other hand, those conditions are easy to check and provide a wide class of models some of which are listed in the paper.Comment: Corrected version of the published articl

A laser-driven target of high-density nuclear polarized hydrogen gas

We report the best figure-of-merit achieved for an internal nuclear polarized hydrogen gas target and a Monte Carlo simulation of spin-exchange optical pumping. The dimensions of the apparatus were optimized using the simulation and the experimental results were in good agreement with the simulation. The best result achieved for this target was 50.5% polarization with 58.2% degree of dissociation of the sample beam exiting the storage cell at a hydrogen flow rate of $1.1\times 10^{18}$ atoms/s.Comment: Accepted as a Rapid Communication article in Phys. Rev.

Differential Cross Sections For State-selective Electron Capture In 25100-keV Proton-helium Collisions

Cross sections differential in the scattering angle of the projectile are presented for electron capture summed over all states and to the 2s, 2p, 3s, 3p, 4s, and 4p states of hydrogen in 25-, 50-, and 100-keV proton-helium collisions. The classical-trajectory Monte Carlo (CTMC) technique was employed for these calculations as well as to compute total cross sections as a function of impact energy. The latter are compared with experiment to display the behavior of the integral state-selective cross sections in this energy regime. Detailed comparison is also made between the calculated angular differential cross sections and the experimental measurements of Martin et al. [Phys. Rev. A 23, 285 (1981)] for capture summed over all states and of Seely et al. [Phys. Rev. A 45, R1287 (1992)] for capture to the 2p state. Very good overall agreement is found. Regarding the cross section for capture summed over all states, an improved agreement is demonstrated by using an alternate representation of the initial state in the CTMC method, which improves the electronic radial distribution, but which cannot presently be applied to state-selective determinations. © 1992 The American Physical Society

Digital fabrication in the architectural design process

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2004.Includes bibliographical references (leaves 60-62).Digital fabrication is affecting the architectural design process due to the increasingly important role it has in the fabrication of architectural models. Many design professionals, professors, and students have experienced the benefits and challenges of using digital fabrication in their design processes, but many others in the field are not yet aware of the possibilities and drawbacks afforded by these technologies. The research presented here unveiled key issues on the matter through a series of interviews with twenty-five individuals, focusing on digital fabrication in their practices and schools, and through three experiments utilizing eight digital fabrication methods, such as three-dimensional printing, laser cutting, and desktop milling. The interviews and experiments form a basis for suggesting better ways to utilize current digital fabrication methods in design and for proposing future methods better suited for the architectural design process.by Jennifer CK Seely.S.M

The Jefferson Lab Frozen Spin Target

A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized tagged photons of both longitudinal and circular polarization. Protons in TEMPO-doped butanol were dynamically polarized to approximately 90% outside the spectrometer at 5 T and 200--300 mK. Photoproduction data were acquired with the target inside the spectrometer at a frozen-spin temperature of approximately 30 mK with the polarization maintained by a thin, superconducting coil installed inside the target cryostat. A 0.56 T solenoid was used for longitudinal target polarization and a 0.50 T dipole for transverse polarization. Spin-lattice relaxation times as high as 4000 hours were observed. We also report polarization results for deuterated propanediol doped with the trityl radical OX063.Comment: 11 pages, 12 figures, preprint submitted to Nuclear Instruments and Methods in Physics Research, Section

Low-energy electron capture by Ne2+ ions from H(D)

Using the Oak Ridge National Laboratory (ORNL) ion-atom merged-beams apparatus, the absolute, total single-electron-capture cross section has been measured for collisions of Ne2+ with deuterium (D) at center-of-mass (c.m.) collision energies of 59–949 eV∕u. With the high-velocity ion beams now available at the ORNL Multicharged Ion Research Facility, we have extended our previous merged-beams measurement to lower c.m. collision energies. The data are compared to all four previously published measurements for Ne2++H(D) which differ considerably from one another at energies ≲600 eV∕u. We are unaware of any published theoretical cross-section data for Ne2++H(D) at the energies studied. Early quantal rate coefficient calculations for Ne2++H at eV/u energies suggest a cross section many orders of magnitude below previous measurements of the cross section at 40 eV∕u which is the lowest collision energy for which experimental results have been published. Here we compare our measurements to recent theoretical electron-capture results for He2++H. Both the experimental and theoretical results show a decreasing cross section with decreasing energy