Production And Studies Of Photocathodes For High Intensity Electron Beams

For short, high-intensity electron bunches, alkali-tellurides have proved to be a reliable photo-cathode material. Measurements of lifetimes in an RF gun of the CLIC Test Facility II at field strengths greater than 100 MV/m are presented. Before and after using them in this gun, the spectral response of the Cs-Te and Rb-Te cathodes were determined with the help of an optical parametric oscillator. The behaviour of both materials can be described by Spicer's 3-step model. Whereas during the use the threshold for photo-emission in Cs-Te was shifted to higher photon energies, that of Rb-Te did not change. Our latest investigations on the stoichiometric ratio of the components are shown. The preparation of the photo-cathodes was monitored with 320 nm wavelength light, with the aim of improving the measurement sensitivity. The latest results on the protection of Cs-Te cathode surfaces with CsBr against pollution are summarized. New investigations on high mean current production are presented.Comment: Submission to LINAC2000 conference, Paper number MOB08, 3 pages, 6 figure

Functional preservation of vascular smooth muscle tissue

The ionic and cellular feedback relationships operating to effect the vascular decompensatory modifications were examined to reveal procedures for implementing protective measures guarding against vascular collapse when returning from a weightless environment to that of the earth's gravity. The surgical procedures for preparing the rat cremaster, and the fixation methods are described. Abstracts of publications resulting from this research are included

Modularised process-based modelling of phosphorus loss at farm and catchment scale

In recent years, a co-ordinated programme of data collection has resulted in the collation of sub-hourly time-series of hydrological, sediment and phosphorus loss data, together with soil analysis, cropping and management information for two small (< 200 ha) headwater agricultural catchments in the UK Midlands (Rosemaund, Herefordshire and Cliftonthorpe, Leicestershire). These data sets have allowed the dynamics of phosphorus loss to be characterised and the importance of both storm runoff and drainflow to be identified, together with incidental losses following manure and fertiliser additions in contributing to total annual loss. A modularised process-based model has been developed to represent current understanding of the dynamics of phosphorus loss. Modules describing runoff and sediment generation and associated phosphorus adsorption/desorption dynamics are described and tested. In the model, the effect of a growing crop on sediment detachment processes is represented and the stability of topsoil is considered so that, overall, the model is responsive to farm management factors. Importantly, using data sets available from national-scale survey programmes to estimate model parameters, a transferable approach is presented, requiring only sub-hourly rainfall data and field-specific landcover information for application of the model to new sites. Results from application of the model to the hydrological year 1998–99 are presented. Assessment of performance, which suggests that the timing of simulated responses is acceptable, has focused attention on quantifying landscape and in-stream retention and remobilisation processes.</b></p> <p style='line-height: 20px;'><b>Keywords: </b>phosphorus, erosion, process-based modelling, agricultur

Tracking advanced persistent threats in critical infrastructures through opinion dynamics

Advanced persistent threats pose a serious issue for modern industrial environments, due to their targeted and complex attack vectors that are difficult to detect. This is especially severe in critical infrastructures that are accelerating the integration of IT technologies. It is then essential to further develop effective monitoring and response systems that ensure the continuity of business to face the arising set of cyber-security threats. In this paper, we study the practical applicability of a novel technique based on opinion dynamics, that permits to trace the attack throughout all its stages along the network by correlating different anomalies measured over time, thereby taking the persistence of threats and the criticality of resources into consideration. The resulting information is of essential importance to monitor the overall health of the control system and cor- respondingly deploy accurate response procedures. Advanced Persistent Threat Detection Traceability Opinion Dynamics.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Generation of Impulses from Single Frequency Inputs Using Non-linear Propagation in Spherical Chains

This paper investigates the use of chains of spheres to produce impulses. An ultrasonic horn is used to generate high amplitude sinusoidal signals. These are then input into chains of spheres, held together using a minimal force. The result is a non-linear, dispersive system, within which solitary waves can exist. The authors have discovered that resonances can be created, caused by the multiple reflection of solitary waves within the chain. The multiply-reflecting impulses can have a wide bandwidth, due to the inherent nonlinearity of the contact between spheres. It is found that the effect only occurs for certain numbers of spheres in the chain for a given input frequency, a result of the creation of a nonlinear normal mode of resonance. The resulting impulses have many applications, potentially creating high amplitude impulses with adjustable properties, depending on both the nature and number of spheres in the chain, and the frequency and amplitude of excitatio

Corporate social responsibility: A unifying discourse for the Mining Industry?

The public perception of mining as an economic activity that generates harmful environmental impacts has generated both a corporate discourse of social responsibility (CSR) to legitimise mining activities and also anti-mining discourses. Both discourses use science to support their claims, yet they rarely agree on a scientific solution. The concept of discourse community may help us to understand the disconnect between mining companies and stakeholders. It is unclear whether the discourse of corporate social responsibility will improve understanding among stakeholders and lead to mutually acceptable resolutions to conflict

Using a magnetite/thermoplastic composite in 3D printing of direct replacements for commercially available flow sensors

Flow sensing is an essential technique required for a wide range of application environments ranging from liquid dispensing to utility monitoring. A number of different methodologies and deployment strategies have been devised to cover the diverse range of potential application areas. The ability to easily create new bespoke sensors for new applications is therefore of natural interest. Fused deposition modelling is a 3D printing technology based upon the fabrication of 3D structures in a layer-by-layer fashion using extruded strands of molten thermoplastic. The technology was developed in the late 1980s but has only recently come to more wide-scale attention outside of specialist applications and rapid prototyping due to the advent of low-cost 3D printing platforms such as the RepRap. Due to the relatively low-cost of the printers and feedstock materials, these printers are ideal candidates for wide-scale installation as localized manufacturing platforms to quickly produce replacement parts when components fail. One of the current limitations with the technology is the availability of functional printing materials to facilitate production of complex functional 3D objects and devices beyond mere concept prototypes. This paper presents the formulation of a simple magnetite nanoparticle-loaded thermoplastic composite and its incorporation into a 3D printed flow-sensor in order to mimic the function of a commercially available flow-sensing device. Using the multi-material printing capability of the 3D printer allows a much smaller amount of functional material to be used in comparison to the commercial flow sensor by only placing the material where it is specifically required. Analysis of the printed sensor also revealed a much more linear response to increasing flow rate of water showing that 3D printed devices have the potential to at least perform as well as a conventionally produced sensor

TB133: Experimental Stream Application of B.t.i. for Human Nuisance Black Fly Management in a Recreational Area

Biting and swarming black flies are abundant in Maine and can cause serious discomfort to humans, especially in recreational areas where their presence may substantially decrease satisfaction in outdoor activities. In 1985, 1986 and 1987 a series of experimental applications of B.t.i. was made on property owned by the Sugarloaf Mountain Corporation. The 198 5 study determined the persistenc e o f B.t.i. in stream and river water and the concentration necessary to achieve \u3e90% mortality in black fly larvae. It also indicated that B.t.i. had no detectable impact on non-target organisms. In 1986 and 1987 the objective was to determine if controlling the black fly larvae in streams within the Sugarloaf property would result in decreasing adult human nuisance flies to an acceptable level.https://digitalcommons.library.umaine.edu/aes_techbulletin/1069/thumbnail.jp