Simple pressure gauge for uranium hexafluoride

A sensitive detector and pressure gauge for uranium hexafluoride in high‐vacuum systems is described. Negative surface ionization of UF_6 occurs on ribbon filaments operated at temperatures too low for electron emission to be significant. The ion current measured on a cylindrical collector surrounding the filament assembly varies regularly with UF_6 pressure below 10^(−3) Torr. Different filament materials are considered, including rhenium, thoriated tungsten, and platinum. Rhenium is found to be the most satisfactory material for operation of diode emitters as a pressure gauge. Gauge constants (in A Torr^(−1)) are derived from comparing negative surface ionization currents with the response of a capacitance manometer and are shown to be independent of temperature within a reasonable operating range. The effects of exposing the rhenium filament to various gases is considered, and it is shown that brief exposure to acetylene substantially improves the operating characteristics of the gauge

Temperature‐dependent transmission extended electron energy‐loss fine structure of aluminum

Inelastic electron scattering experiments in a transmission electron microscope provide a probe of core electron excitations that have binding energies below 2 keV, and that are localized within submicron diameter sample volumes. Extended electron energy‐loss fine‐structure measurements which show the variation with temperature of the mean squared relative displacement of aluminum yield a localized measurement of the Debye temperature which is in excellent agreement with macroscopic measurements

Jumpstart 2000—The Maine Economic Improvement Strategy: A Targeted Investment in Research and Development

In recent years Maine has ranked 50th in per capita spending on university-based research and development in the United States, a distinction that an increasing number of Maine policymakers, citizens, business representatives and researchers find alarming. Citing the positive gains R&D investments have shown in other states, not the least of which is improved economic performance, the authors set forth an argument for investing in Maine’s public R&D infrastructure. Whether and how to make such investments have been the subjects of recent debate in many states

AFM pulling and the folding of donor-acceptor oligorotaxanes: phenomenology and interpretation

The thermodynamic driving force in the self-assembly of the secondary structure of a class of donor-acceptor oligorotaxanes is elucidated by means of molecular dynamics simulations of equilibrium isometric single-molecule force spectroscopy AFM experiments. The oligorotaxanes consist of cyclobis(paraquat-\emph{p}-phenylene) rings threaded onto an oligomer of 1,5-dioxynaphthalenes linked by polyethers. The simulations are performed in a high dielectric medium using MM3 as the force field. The resulting force vs. extension isotherms show a mechanically unstable region in which the molecule unfolds and, for selected extensions, blinks in the force measurements between a high-force and a low-force regime. From the force vs. extension data the molecular potential of mean force is reconstructed using the weighted histogram analysis method and decomposed into energetic and entropic contributions. The simulations indicate that the folding of the oligorotaxanes is energetically favored but entropically penalized, with the energetic contributions overcoming the entropy penalty and effectively driving the self-assembly. In addition, an analogy between the single-molecule folding/unfolding events driven by the AFM tip and the thermodynamic theory of first-order phase transitions is discussed and general conditions, on the molecule and the cantilever, for the emergence of mechanical instabilities and blinks in the force measurements in equilibrium isometric pulling experiments are presented. In particular, it is shown that the mechanical stability properties observed during the extension are intimately related to the fluctuations in the force measurements.Comment: 42 pages, 17 figures, accepted to the Journal of Chemical Physic

Brief Note: Ohio Lamprey, Ichthyomyzon bdellium (Petromyzonidae), in Ohio: A Review and Recent Records

Author Institution: Ohio Department of Natural Resources, Division of Natural Areas and Preserves, and Department of Life Science, Otterbein CollegePrior to 1983 only isolated specimens of Ohio lamprey {Ichthyomyzon bdellium) were collected at a few sites in the Ohio River drainage of Ohio, where it is listed as an endangered species. Seining surveys of the Little Muskingum River in 1983 and 1992 discovered a concentration of unattached adults in a riffle in May, as well as a recently metamorphosed subadult and an ammocoete, indicating that the species probably spawns there. Other Ohio River tributaries may support spawning populations as well

Effects of Training Intensity on Locomotor Performance in Individuals With Chronic Spinal Cord Injury: A Randomized Crossover Study

Background. Many physical interventions can improve locomotor function in individuals with motor incomplete spinal cord injury (iSCI), although the training parameters that maximize recovery are not clear. Previous studies in individuals with other neurologic injuries suggest the intensity of locomotor training (LT) may positively influence walking outcomes. However, the effects of intensity during training of individuals with iSCI have not been tested. Objective. The purpose of this pilot, blinded-assessor randomized trial was to evaluate the effects of LT intensity on walking outcomes in individuals with iSCI. Methods. Using a crossover design, ambulatory participants with iSCI \u3e1 year duration performed either high- or low-intensity LT for ≤20 sessions over 4 to 6 weeks. Four weeks following completion, the training interventions were alternated. Targeted intensities focused on achieving specific ranges of heart rate (HR) or ratings of perceived exertion (RPE), with intensity manipulated by increasing speeds or applying loads. Results. Significantly greater increases in peak treadmill speeds (0.18 vs 0.02 m/s) and secondary measures of metabolic function and overground speed were observed following high- versus low-intensity training, with no effects of intervention order. Moderate to high correlations were observed between differences in walking speed or distances and differences in HRs or RPEs during high- versus low-intensity training. Conclusion. This pilot study provides the first evidence that the intensity of stepping practice may be an important determinant of LT outcomes in individuals with iSCI. Whether such training is feasible in larger patient populations and contributes to improved locomotor outcomes deserves further consideration

Ariel - Volume 9 Number 5

Executive Editor Seth B. Paul Associate Editor Warren J. Ventriglia Business Manager Fredric Jay Matlin University News John Patrick Welch World News George Robert Coar Editorials Editor Steve Levine Features Mark Rubin Brad Feldstein Sports Editor Eli Saleeby Photo Editor Ken Buckwalter Circulation Victor Onufreiczuk Lee Wugofski Graphics and Art Steve Hulkower Commons Editor Brenda Peterso

Unique selling propositions and destination branding: A longitudinal perspective on the Caribbean tourism in transition

A recurring theme in the tourism literature is how travelers and tourism businesses perceive the concept of diversity and uniqueness of attractions pinned to places called tourism destinations and respond to their perceptions. In this backdrop, the primary focus of this research is a reexamination of the unique selling proposition (USP) based tourism marketing practice that various Caribbean island nations unleased since the early 2000\u27s. The extent of USP adoption in the web-based marketing campaigns of these destinations over a timeline from 2004 to 2014 is studied. Analysis shows that higher level USP use initially rose, reached a peak, and then declined. Also, over the years, destinations high in attraction diversity tended to delimit themselves from using highly targeted USPs while their counterparts with less attraction diversity routinely employed hierarchically superior USP slogans. The exact number of attractions in a destination country did not significantly imply the choice of slogans as much as the attraction type diversity. In order to achieve these objectives, an \u27attraction diversity index\u27 is proposed, which is a measure of the diversity of attraction types in a destination area. The research opens up further questions about the moderating role of product diversity in uniqueness centered marketing programs. It is recommended that marketers leverage the mass customization potential underlying in the contemporary progress in the information and communication technologies and tailor make USPs that reflect individual and small group aspirations about destination offerings

Effects of human and porcine bile on the proteome of Helicobacter hepaticus

<p>Abstract</p> <p>Background</p> <p><it>Helicobacter hepaticus </it>colonizes the intestine and liver of mice causing hepatobiliary disorders such as hepatitis and hepatocellular carcinoma, and has also been associated with inflammatory bowel disease in children. In its habitat, <it>H. hepaticus </it>must encounter bile which has potent antibacterial properties. To elucidate virulence and host-specific adaptation mechanisms of <it>H. hepaticus </it>modulated by human or porcine bile, a proteomic study of its response to the two types of bile was performed employing two-dimensional gel electrophoresis (2-DE) and mass spectrometry.</p> <p>Results</p> <p>The 2-DE and mass spectrometry analyses of the proteome revealed that 46 proteins of <it>H. hepaticus </it>were differentially expressed in human bile, 18 up-regulated and 28 down-regulated. In the case of porcine bile, 32 proteins were differentially expressed of which 19 were up-regulated, and 13 were down-regulated. Functional classifications revealed that identified proteins participated in various biological functions including stress response, energy metabolism, membrane stability, motility, virulence and colonization. Selected genes were analyzed by RT-PCR to provide internal validation for the proteomic data as well as provide insight into specific expressions of motility, colonization and virulence genes of <it>H. hepaticus </it>in response to human or porcine bile.</p> <p>Conclusions</p> <p>Overall, the data suggested that bile is an important factor that determines virulence, host adaptation, localization and colonization of specific niches within host environment.</p