Improved throat inserts for ablative thrust chambers

Composite material development and structural design of improved throat inserts for ablative thrust chamber

Novel Method of Measuring Electron Positron Colliding Beam Parameters

Through the simultaneous measurement of the transverse size as a function of longitudinal position, and the longitudinal distribution of luminosity, we are able to measure the $\beta_y^\ast$ (vertical envelope function at the collision point), vertical emittance, and bunch length of colliding beams at the Cornell Electron-positron Storage Ring (CESR). This measurement is possible due to the significant ``hourglass'' effect at CESR and the excellent tracking resolution of the CLEO detector.Comment: 11 pages, 4 figures, submitted to NIM

Assessment and Characterization of Physical Habitat, Water Quality, and Biotic Assemblages of the Tyronza River, Arkansas

Few studies within the last few decades have addressed water quality and biotic assemblages within Arkansas’s large channel-altered deltaic rivers. The Tyronza River is located in northeast Arkansas and its watershed has a heavy agricultural presence that drastically affects habitat quality. Meanwhile, the Tyronza River hosts one of the more recent documented range extensions of the federally endangered fat pocketbook mussel [Potamilus capax (Green, 1832)]. The purpose of this study was to assess physical habitat, water quality, and biotic assemblages of the Tyronza River using the Arkansas Department of Environmental Quality’s (ADEQ) regional biometrics. Water samples were collected at 9 stations across 4 seasonal intervals. Physical habitat, fish, and macroinvertebrates were collected at 9 stations during summer and fall. U.S. EPA Rapid Bioassessment Protocols for habitat indicated that habitat quality was suboptimal. Distinct seasonal differences were observed among all water chemistry parameters; however, seasonality was not as clear among nutrient constituents. Macroinvertebrate assemblages varied drastically among sites: taxa richness ranged from 3 to 14 and the Arkansas Macroinvertebrate Index for Small Watersheds values ranged from 16 to 28 (poor to very good condition). Fish Community Structure Indices were less variable among sites ranging from 6 to 16 (Not Similar to Somewhat Similar). The lack of instream habitat and habitat richness is likely resulting in low taxa richness in the biotic communities. Results from this study will provide managers and scientists with valuable information on seasonal variation of select water quality parameters and into the integrity of aquatic assemblages of the Tyronza River. Keywords: Water quality, rapi

Variability in sonic-boom signatures measured along an 8000-foot linear array

Variability in sonic boom signatures measured along 8000 foot linear microphone arra

Letters between H. N. Henderson and William Kerr\u27s secretary

Letters concerning a position in athletic department at Utah Agricultural College

Quantum quenches of ion Coulomb crystals across structural instabilities

Quenches in an ion chain can create coherent superpositions of motional states across the linear-zigzag structural transition. The procedure has been described in [Phys. Rev. A 84, 063821 (2011)] and makes use of spin-dependent forces, so that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain's internal and external degrees of freedom. The properties of the crystalline state so generated are theoretically studied by means of Ramsey interferometry on one ion of the chain. An analytical expression for the visibility of the interferometric measurement is obtained for a chain of arbitrary number of ions and as a function of the time elapsed after the quench. Sufficiently close to the linear-zigzag instability the visibility decays very fast, but exhibits revivals at the period of oscillation of the mode that drives the structural instability. These revivals have a periodicity that is independent of the crystal size, and they signal the creation of entanglement by the quantum quench.Comment: 14 pages, 8 figures; added a paragraph in the introduction providing more background, added paragraph at the end of Sec. IV discussing experimental parameter

Earth orbital teleoperator systems evaluation

The mechanical extension of the human operator to remote and specialized environments poses a series of complex operational questions. A technical and scientific team was organized to investigate these questions through conducting specific laboratory and analytical studies. The intent of the studies was to determine the human operator requirements for remotely manned systems and to determine the particular effects that various system parameters have on human operator performance. In so doing, certain design criteria based on empirically derived data concerning the ultimate control system, the human operator, were added to the Teleoperator Development Program

Hand hygiene expectations in radiography: a critical evaluation of the opportunities for and barriers to compliance

Introduction: Good hand hygiene practices reduce the risk of transmission of infection in healthcare. In common with other areas of healthcare, infection control knowledge and practice in radiography has potential for improvement. Regular hand hygiene compliance (HHC) monitoring indicated poor compliance in radiology which did not accurately reflect practice in one organisation. Using a quality improvement cycle, the process and context of work undertaken in radiology were examined in order to improve the validity and utility of HHC monitoring data collection process in the department. Methods: Following examination of the evidence base and with agreement from the radiology team, the chest X-ray process was observed and actions notated. This was then scored using the organisation and the World Health Organization five moments of hand hygiene tool. An alternative risk-based scoring system was developed. Results: The HHC score of 22% was obtained using standard measurements. Achievement of 100% compliance would require the radiographer to clean their hands nine times for each X-ray. The sequence of taking a chest X-ray was examined and two points in the process were identified as key points at which hand cleaning should take place to reduce the risk of transmission of infection. Conclusions: Cleaning hands frequently to achieve compliance expectations in this short low-risk process is neither feasible nor beneficial. A pragmatic risk-based approach to hand hygiene expectations in predictable procedures such as taking a chest X-ray reduces ambiguity and potentially increases compliance