Aspects of the confinement mechanism in Coulomb-gauge QCD

Phenomenological consequences of the infrared singular, instantaneous part of the gluon propagator in Coulomb gauge are investigated. The corresponding quark Dyson-Schwinger equation is solved, neglecting retardation and transverse gluons and regulating the resulting infrared singularities. While the quark propagator vanishes as the infrared regulator goes to zero, the frequency integral over the quark propagator stays finite and well-defined. Solutions of the homogeneous Bethe-Salpeter equation for the pseudoscalar and vector mesons as well as for scalar and axial-vector diquarks are obtained. In the limit of a vanishing infrared regulator the diquark masses diverge, while meson properties and diquark radii remain finite and well-defined. These features are interpreted with respect to the resulting aspects of confinement for colored quark-quark correlations.Comment: 4 pages, 6 figure

A profile-driven dynamic risk assessment framework for connected and autonomous vehicles

The Internet of Things has already demonstrated clear benefits when applied in many areas. In connected and autonomous vehicles (CAV), IoT data can help the autonomous systems make better decisions for safer and more secure transportation. For example, different IoT data sources can extend CAV's risk awareness, while the incoming data can update these risks in real-time for faster reactions that may mitigate possible damages. However, the current state of the art CAV research has not addressed this matter well enough. This paper proposes a profile-driven approach to manage IoT data in the context of CAV systems through a dynamic risk management framework. Unlike the current inflexible risk assessment strategies, the framework encourages more flexible investigation of risks through different risk profiles, each representing risk knowledge through a set of risk input considerations, assessment methods and optimal reaction strategies. As the risks change frequently with time and location, there will be no single profile that can cover all the risks that CAVs face on the road. The uses of different risk profiles, therefore can help interested parties to better understand the risks and adapt to various situations appropriately. Our framework includes the effective management of IoT data sources to enable the run-time risk assessment. We also describe a case study of using the proposed framework to manage the risks for the POD being developed in the Innovate UK-funded CAPRI project

Shock statistics in higher-dimensional Burgers turbulence

We conjecture the exact shock statistics in the inviscid decaying Burgers equation in D>1 dimensions, with a special class of correlated initial velocities, which reduce to Brownian for D=1. The prediction is based on a field-theory argument, and receives support from our numerical calculations. We find that, along any given direction, shocks sizes and locations are uncorrelated.Comment: 4 pages, 8 figure

Incorporation of stochastic chemistry on dust grains in the PDR code using moment equations

Unlike gas-phase reactions, chemical reactions taking place on interstellar dust grain surfaces cannot always be modeled by rate equations. Due to the small grain sizes and low flux,these reactions may exhibit large fluctuations and thus require stochastic methods such as the moment equations. We evaluate the formation rates of H2, HD and D2 molecules on dust grain surfaces and their abundances in the gas phase under interstellar conditions. We incorporate the moment equations into the Meudon PDR code and compare the results with those obtained from the rate equations. We find that within the experimental constraints on the energy barriers for diffusion and desorption and for the density of adsorption sites on the grain surface, H2, HD and D2 molecules can be formed efficiently on dust grains. Under a broad range of conditions, the moment equation results coincide with those obtained from the rate equations. However, in a range of relatively high grain temperatures, there are significant deviations. In this range, the rate equations fail while the moment equations provide accurate results. The incorporation of the moment equations into the PDR code can be extended to other reactions taking place on grain surfaces

Remediation of Mud Pumping on a Ballasted Railway Track

AbstractMaintenance of ballasted railway tracks is a major cost for railway infrastructure owners. In many developed countries, much of the railway infrastructure is mature and was built for service requirements long since superseded. The increased demands on historic infrastructure can lead to the development or exacerbation of localised trackbed problems that require disproportionate levels of maintenance. Identifying these and applying cost effective remediation has the potential to reduce maintenance spend in the long term. However, it is not always clear what the most cost effective remediation will be. One type of localised maintenance issue is the development of wet beds or wet spots, which can occur where saturated clayey subgrade soils are overloaded and result in the development of mud pumping as trains pass. This leads to the migration of fines into the ballast bed and a deterioration in local track performance. Over time the track overlying the wet bed settles disproportionately more, sleepers become progressively more voided, and train ride quality deteriorates. Maintenance of the wet bed may involve locally digging out and replacing the ballast; however, unless the underlying cause is addressed the problem is likely to recur, requiring repeated localised maintenance interventions. This is costly, reactive and ultimately an ineffective approach to managing the problem. This paper presents a study of a wet bed in the UK, both prior to and after a full track renewal. Transient track deflections during train passage were monitored using sleeper mounted geophones and high speed filming techniques. Loaded track geometry data were obtained from a track recording vehicle. It is shown that local maintenance interventions were generally ineffective, but that a renewal of the top 200mm of the trackbed including placement of a geotextile filter and geogrid appears to have been successful in remediating the problem, at least in the short term

Brainstem metastases treated with Gamma Knife stereotactic radiosurgery: the Indiana University Health experience

Brainstem metastases offer a unique challenge in cancer treatment, yet stereotactic radiosurgery (SRS) has proven to be an effective modality in treating these tumors. This report discusses the clinical outcomes of patients with brainstem metastases treated at Indiana University with Gamma Knife (GK) radiosurgery from 2008 to 2016. 19 brainstem metastases from 14 patients who had follow-up brain imaging were identified. Median tumor volume was 0.04 cc (range: 0.01-2.0 cc). Median prescribed dose was 17.5 Gy to the 50% isodose line (range: 14-22 Gy). Median survival after GK SRS treatment to brainstem lesion was 17.2 months (range: 2.8-45.6 months). The experience at Indiana University confirms the safety and efficacy of range of GK SRS prescription doses (14-22 Gy) to brainstem metastases

The Effects of Information Literacy Instruction on Business Students’ Job Readiness

The purpose of this study is to examine college student perceptions of information literacy instruction and to what extent library instruction influences students’ attitudes in their business research during their job-readiness training through the Panthers Advanced Career Experience (PACE). The findings suggest that library instruction intervention positively influenced and increased confidence in completing the information research for their client-based consultation project

Pathfinder VI Experimental Payload: Desna

The objective of this project is to design, fabricate and test a fixed wing unmanned aerial vehicle (UAV) that is to be carried in, and deployed from the Pathfinder VI rocket. The UAV, known as Desna, is tasked with being able to carry a Tamarisk 640 75mm thermal imaging camera, and transmit live video footage to a ground station from 8500 feet AGL. Desna must also fit inside Pathfinder VI’s 7.5” diameter, 35” long cargo bay. To accomplish this, Desna’s wing configuration, determined through description matrices and light prototype testing, will consist of a 35” wing that rotates about its center with 11” folding winglets to increase lift and stability. Desna will be constructed from blue high-density foam to allow for cheap, rapid prototyping as well as being light as possible while still being able to survive the G loadings during assent. Desna will fly in Pathfinder VI this June in the Intercollegiate Rocket Engineering Competition as an experimental payload