Using ordinary multiplication to do relativistic velocity addition

Relativistic addition of velocities in one dimension, though a mainstay of introductory physics, contributes much less physical insight than it could. For such calculations, we propose the use of velocity factors (two-way doppler factors). Velocities can easily, often by inspection, be turned into velocity factors, and vice versa. Velocity factors compose by ordinary multiplication. This simple device considerably extends the kinds of questions that can be asked and answered in an introductory course.Comment: 6 page

Provisions for oil and gas decommissioning costs: compliance with disclosure requirements by oil and gas companies listed in the UK

Due to their complications in terms of uncertainty and calculations provisions for oil and gas decommissioning costs are not easy to be understood and interpret by users of no accounting and finance background. Furthermore, due to their significant sizes, cash outflow effect and importance for decision making disclosing more detailed information seem to be ideal requirement to simplify these complications. This study raises, almost for the first time, queries about compliance, sufficiency, uniformity and fairness of oil and gas companies' disclosure practices with regard to provisions for decommissioning costs. In order to provide answers to the research quires, annual reports of 69 oil and gas companies listed in the UK were analysed and thirteen interviews with different professionals were conducted. Our results reveal that whilst there is sufficient standards to regulate accounting for provisions for decommissioning costs there seems to be lack of compliance with requirements of international accounting standards in terms of disclosing information on provisions for decommissioning costs. In many cases, and probably due to their sensitive nature, we found that oil and gas companies tend to disclose a minimum amount of information about provisions for decommissioning costs

Altered Cerebellar Short-Term Plasticity but No Change in Postsynaptic AMPA-Type Glutamate Receptors in a Mouse Model of Juvenile Batten Disease

Juvenile Batten disease is the most common progressive neurodegenerative disorder of childhood. It is associated with mutations in the CLN3 gene, causing loss of function of CLN3 protein and degeneration of cerebellar and retinal neurons. It has been proposed that changes in granule cell AMPA-type glutamate receptors (AMPARs) contribute to the cerebellar dysfunction. In this study we compared AMPAR properties and synaptic transmission in cerebellar granule cells from wild-type and Cln3 knockout mice. In Cln3Δex1–6 cells the amplitude of AMPA-evoked whole-cell currents was unchanged. Similarly, we found no change in the amplitude, kinetics, or rectification of synaptic currents evoked by individual quanta, or in their underlying single-channel conductance. We found no change in cerebellar expression of GluA2 or GluA4 protein. By contrast, we observed a reduced number of quantal events following mossy-fiber stimulation in Sr2+, altered short-term plasticity in conditions of reduced extracellular Ca2+, and reduced mossy fiber vesicle number. Thus, while our results suggest early presynaptic changes in the Cln3Δex1–6 mouse model of juvenile Batten disease, they reveal no evidence for altered postsynaptic AMPARs

Attacking Group Protocols by Refuting Incorrect Inductive Conjectures

Automated tools for finding attacks on flawed security protocols often fail to deal adequately with group protocols. This is because the abstractions made to improve performance on fixed 2 or 3 party protocols either preclude the modelling of group protocols all together, or permit modelling only in a fixed scenario, which can prevent attacks from being discovered. This paper describes Coral, a tool for finding counterexamples to incorrect inductive conjectures, which we have used to model protocols for both group key agreement and group key management, without any restrictions on the scenario. We will show how we used Coral to discover 6 previously unknown attacks on 3 group protocols

Controlling Legionella pneumophila in water systems at reduced hot water temperatures with copper and silver ionization

Background: Hospital-acquired Legionnaires’ disease is associated with the presence of Legionella pneumophila in hospital water systems. In the United Kingdom, the Department of Health recommends maintaining hot water temperatures >55°C and cold water temperatures <20°C at the point of delivery to prevent proliferation of L pneumophila in water systems. In this study, we evaluated the efficacy of copper and silver ionization to control L pneumophila at deliberately reduced hot water temperatures (43°C) within a newly installed water system in a new building linked to a large health care facility in the United Kingdom. / Methods: One thousand, five hundred ninety-eight water samples were collected between September 2011 and June 2017. Samples were tested using accredited methods for L pneumophila, copper and silver ion levels, and total viable counts. Energy consumption and water usage data were also collected to permit carbon emission calculations. / Results: The results of 1,598 routine samples from September 2011 to June 2017, and the recordings of temperatures at outlets in this facility, demonstrated effective (100%) L pneumophila control throughout the study period with an average hot water temperature of 42°C. The energy savings and reduction of carbon emissions were calculated to amount to 33% and 24%, respectively, compared to an equivalent temperature-controlled system. Water system management interventions were required to achieve consistently adequate levels of copper and silver across outlets. / Conclusions: This study demonstrated that it is possible to control L pneumophila independent of temperature when copper and silver ionization is introduced into a new building in conjunction with an appropriately managed water system

Artemis Curation: Preparing for Sample Return from the Lunar South Pole

Space Policy Directive-1 mandates that the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations. In addition, the Vice President stated that It is the stated policy of this administration and the United States of America to return American astronauts to the Moon within the next five years, that is, by 2024. These efforts, under the umbrella of the recently formed Artemis Program, include such historic goals as the flight of the first woman to the Moon and the exploration of the lunar south-polar region. Among the top priorities of the Artemis Program is the return of a suite of geologic samples, providing new and significant opportunities for progressing lunar science and human exploration. In particular, successful sample return is necessary for understanding the history of volatiles in the Solar System and the evolution of the Earth-Moon system, fully constraining the hazards of the lunar polar environment for astronauts, and providing the necessary data for constraining the abundance and distribution of resources for in-situ resource utilization (ISRU). Here we summarize the ef-forts of the Astromaterials Acquisition and Curation Office (hereafter referred to as the Curation Office) to ensure the success of Artemis sample return (per NASA Policy Directive (NPD) 7100.10E)