What Makes Educational Campaings Succeed?

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Joint repair methods for cast iron natural gas distribution mains and the preliminary development of an alternative joint seal.

Approximately 10 percent of the natural gas pumped into distribution systems is unaccounted for. A significant portion of this amount is leakage from joints in 50 to 100 year old cast iron main. Because of the cumulative effects of many small leaks, these leaks must be repaired even though the repair expense is not always justified by the value of the gas conserved.Part One identifies and evaluates leak sealing techniques of the past and present by compiling available test data. A major task was to review all documented test results in journals and technical reports. This study followed-up on published articles by contacting all the individuals and organizations concerned. Recommendations for future development of an alternate sealing system are made.Part Two discusses preliminary criteria for the design of an alternative system to seal main joints from within the main without service interruption. Experiments were performed showing that very soft elastomers pressed against the rough pipe wall could prohibit leakage. Potential cleaning methods were tested. Wire and abrasive wheels, and water-jets were recommended for further development. Based on time-dependent characteristics and resistance to aging and to chemicals found in mains, fluorocarbon was recommended for use as the seal material. Preliminary design of the seal verified its feasibility. Several innovative concepts for the seal are presented. Considerations for the cleaning and sealing device and for the overal'. system are discussed

The Effect of Sill Height on Decay in Air-Seasoning Crossties

The sustainable use of wood for rail ties requires chemical treatment to increase service life and maintain structural integrity. Treatment can only be applied after lengthy air-seasoning to reduce moisture content in wood, but seasoning leaves ties exposed to attack by decay fungi for up to a year. One factor affecting the rate of decay is proximity to soil contact. The height of sills used to raise untreated ties above ground contact while drying is mandated by national standards to be 12 inches, but there is little research examining the effects of deviating from this height on decay risk. This study examined the effects of varying sill height on colonization by decay fungi and flexural properties of black gum and red oak ties. The objective was to relate sill height with populations of decay fungi and to changes in wood strength during air-seasoning. Sampling of blackgum railroad ties from the Koppers plant in Guthrie, Kentucky at three time points during seasoning showed that the incidence of decay fungi increased at an even rate over time with little or no difference attributed to distance of stacks above the ground. Red oak ties sampled three times over 11 months showed that red oak yielded few decay fungi for 6 months followed by a rapid increase in fungal populations. Stacks of red oak and blackgum had completely different fungal populations and colonization rates despite being stored in close proximity. Changes in fungi colonizing ties and their effect on tie properties were not strongly related to height between 6 and 33 inches, and there was no relation to sill heights of 6, 8, or 12 inches. Isolates of decay fungi recovered from ties were evaluated for decay potential and produced a wide range of decay capabilities. Blackgum ties were colonized most by white rot fungi, while red oak ties were colonized by both white rot and brown rot fungi. Many cultures isolated from blackgum had weak decay capabilities. The results indicate that decreasing sill height from 12 to 6 inches had no significant effect on fungal colonization or timber properties of the two species evaluated.Key Words: Railroad ties, crossties, blackgum, red oak, fungal colonization, air-seasoning, decay, decay out of ground-contact

Next-gen sequencing of multi-drug resistant Acinetobacter baumanii at Nashville General Hospital at Meharry

Background Acinetobacter baumannii is a nonfermentative Gram-negative bacillus, which easily acquires antibiotic resistance determinants and causes life-threatening nosocomial infections [1]. Multi-drug resistant (MDR) strains are common therefore, empirical treatment choices are limited. More knowledge is needed regarding genetic diversity patterns and resistance phenotypes in a given clinical setting. Our goal is to identify the resistance genotypes of A. baumanii at Nashville General Hospital and correlate them with MDR phenotypes [1]

“Funny How?” A Serious Look at Humor in Conversational Agents

Conversational agents are rapidly advancing in terms of their capabilities and human likeness - both of which are intended to enhance the user experience and engagement. One human quality that can potentially increase trust and likeability is humor. However, what is considered humorous and what is not depends on many contextual and personal factors that are not only difficult for machines to detect, but even humans are still struggling to understand them. This makes training AI to be humorous highly challenging. But is this due only to the technical limitations? In this provocation paper, we discuss the hindrances to utilizing humor in commercial conversational agents and propose addressing this topic from a social and political perspective

Computations of three-dimensional steady and unsteady viscous incompressible flows

The INS3D family of computational fluid dynamics computer codes is presented. These codes are used to as tools in developing and assessing algorithms for solving the incompressible Navier-Stokes equations for steady-state and unsteady flow problems. This work involves applying the codes to real-world problems involving complex three-dimensional geometries. The algorithms utilized include the method of pseudocompressibility including both central and upwind differencing, several types of artificial dissipation schemes, approximate factorization, and an implicit line-relaxation scheme. These codes have been validated using a wide range of problems including flow over a backward-facing step, driven cavity flow, flow through various types of ducts, and steady and unsteady flow over a circular cylinder. Many diverse flow applications have been solved using these codes including parts of the Space Shuttle Main Engine, problems in naval hydrodynamics, low-speed aerodynamics, and biomedical fluid flows. The presentation details several of these, including the flow through a Space Shuttle Main Engine inducer, vortex shedding behind a circular cylinder, and flow through an artificial heart

Around Pelikan's conjecture on very odd sequences

Very odd sequences were introduced in 1973 by J. Pelikan who conjectured that there were none of length >=5. This conjecture was disproved by MacWilliams and Odlyzko in 1977 who proved there are in fact many very odd sequences. We give connections of these sequences with duadic codes, cyclic difference sets, levels (Stufen) of cyclotomic fields, and derive some new asymptotic results on their lengths and on S(n), which denotes the number of very odd sequences of length n.Comment: 21 pages, two tables. Revised version with improved presentation and correction of some typos and minor errors that will appear in Manuscripta Mathematic

Implementation of the Backlund transformations for the Ablowitz-Ladik hierarchy

The derivation of the Backlund transformations (BTs) is a standard problem of the theory of the integrable systems. Here, I discuss the equations describing the BTs for the Ablowitz-Ladik hierarchy (ALH), which have been already obtained by several authors. The main aim of this work is to solve these equations. This can be done in the framework of the so-called functional representation of the ALH, when an infinite number of the evolutionary equations are replaced, using the Miwa's shifts, with a few equations linking tau-functions with different arguments. It is shown that starting from these equations it is possible to obtain explicit solutions of the BT equations. In other words, the main result of this work is a presentation of the discrete BTs as a superposition of an infinite number of evolutionary flows of the hierarchy. These results are used to derive the superposition formulae for the BTs as well as pure soliton solutions.Comment: 20 page

SelVReflect: A Guided VR Experience Fostering Reflection on Personal Challenges

Reflecting on personal challenges can be difficult. Without encouragement, the reflection process often remains superficial, thus inhibiting deeper understanding and learning from past experiences. To allow people to immerse themselves in and deeply reflect on past challenges, we developed SelVReflect, a VR experience which offers active voice-based guidance and a space to freely express oneself. SelVReflect was developed in an iterative design process (N=5) and evaluated in a user study with N=20 participants. We found that SelVReflect enabled participants to approach their challenge and its (emotional) components from different perspectives and to discover new relationships between these components. By making use of the spatial possibilities in VR, participants developed a better understanding of the situation and of themselves. We contribute empirical evidence of how a guided VR experience can support reflection. We discuss opportunities and design requirements for guided VR experiences that aim to foster deeper reflection