37 research outputs found
High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy
Two generations of a novel detector for high-resolution transmission imaging
and spectrometry of fast-neutrons are presented. These devices are based on a
hydrogenous fiber scintillator screen and single- or multiple-gated intensified
camera systems (ICCD). This detector is designed for energy-selective neutron
radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams.
Utilizing the Time-of-Flight (TOF) method, such a detector is capable of
simultaneously capturing several images, each at a different neutron energy
(TOF). In addition, a gamma-ray image can also be simultaneously registered,
allowing combined neutron/gamma inspection of objects. This permits combining
the sensitivity of the fast-neutron resonance method to low-Z elements with
that of gamma radiography to high-Z materials.Comment: Also published in JINST:
http://www.iop.org/EJ/abstract/1748-0221/4/05/P0501
Determination of Omega_b From Big Bang Nucleosynthesis in the Presence of Regions of Antimatter
Production of regions of antimatter in the early universe is predicted in
many baryogenesis models. Small scale antimatter regions would annihilate
during or soon after nucleosynthesis, affecting the abundances of the light
elements. In this paper we study how the acceptable range in Omega_b changes in
the presence of antimatter regions, as compared to the standard big bang
nucleosynthesis. It turns out that it is possible to produce at the same time
both a low 4He value (Y_p < 0.240) and a low D/H value (D/H < 4e-5), but
overproduction of 7Li is unavoidable at large Omega_b.Comment: 9 pages, PRD version, ref. 6 correcte
Yield of Forage Sorghum, \u3ci\u3eSorghum vulgare\u3c/i\u3e, as Influenced by Row Number, Width, and Orientation
The primary objectives of this study were to: (1) obtain an estimate of the degree to which inter-plot competition exists in forage sorghum yield trials; and (2) provide a basis for suggesting corrective measures. The row arrangements required to achieve the primary objective provided an opportunity to study the response of forage sorghum to different row spacings.
The elimination of inter-plot error, boarder effect, is essential to proper interpretation of data from experimental agronomic units or plots. Economics either from the cost of labor aspects often determine plot size. Frequently forage sorghum, Sorghum vulgare (Pers.) yield influence of tall, (T) or short (s) growing varieties on neighboring plots of the opposite height character were examined during 1963, 1964, and 1965 at Lincoln, Nebraska and Manhattan, Kansas. Tests were established to measure the interactions of these height variables with row spacing and orientation and soil moisture conditions.
Advisor: William L. Colville
Changes in Kinematics, Kinetics, and Muscle Activity in Patients with Lumbar Spinal Stenosis During Gait: Systematic Review
BACKGROUND CONTEXT: Lumbar spinal stenosis (LSS) is one of the most common orthopaedic conditions and affects more than half a million people over the age of 65 in the US. Patients with LSS have gait dysfunction and movement deficits due to pain and symptoms caused by compression of the nerve roots within a narrowed spinal canal.
PURPOSE: The purpose of the current systematic review was to summarize existing literature reporting biomechanical changes in gait function that occur with LSS, and identify knowledge gaps that merit future investigation in this important patient population.
STUDY DESIGN/SETTING: This study is a systematic literature review.
OUTCOME MEASURES: The current study included biomechanical variables (e.g., kinematic, kinetic, and muscle activity parameters).
METHODS: Relevant articles were selected through MEDLINE, Scopus, Embase, and Web of Science. Articles were included if they: 1) included participants with LSS or LSS surgery, 2) utilized kinematic, kinetic, or muscle activity variables as the primary outcome measure, 3) evaluated walking or gait tasks, and 4) were written in English.
RESULTS: A total of 11 articles were included in the current systematic review. The patients with LSS exhibited altered gait function as compared to healthy controls. Improvements in some biomechanical variables were found up to one year after surgery, but most gait changes were found within one month after surgery.
CONCLUSIONS: Although numerous studies have investigated gait function in patients with LSS, gait alterations in joint kinetics and muscle activity over time remain largely unknown. In addition, there are limited findings of spinal kinematics in patients with LSS during gait. Thus, future investigations are needed to investigate longer-term gait changes with regard to spinal kinematics, joint kinetics, and muscle activity beyond one month after LSS surgery