Photoproduction of Pion Pairs in Hydrogen

The photoproduction of pion pairs has been observed by detecting, in a magnetic spectrometer, the negative pions which emerged at 60° and at 120° from a hydrogen target in the bremsstrahlung beam of an electron synchrotron. The yields of negative pions "per equivalent quantum" were measured for several values of the pion energy and the bremsstrahlung cutoff energy. From the variations of the yields with bremsstrahlung cutoff energy, the cross section for the emission of negative pions was obtained. The cross section shows no large dependence on the pion angle from 90° to 150° in the c.m. system. The integral of the cross section over the negative pion energy is consistent with a constant value of about 4×10^-30 cm^2/sterad for photon energies between 600 and 1100 Mev. The observed dependence of the cross section on pion energy has been compared to some phenomenological models

Lasers for Satellite Uplinks and Downlinks

The article of record as published may be found at http://dx.doi.org/10.3390/sci2030071The use of Light Amplification by Stimulated Emission of Radiation (i.e., LASERs or lasers) by the U.S. Department of Defense is not new and includes laser weapons guidance, laser-aided measurements, even lasers as weapons (e.g., Airborne Laser). Lasers in support of telecommunications is also not new. The use of laser light in fiber optics shattered thoughts on communications bandwidth and throughput. Even the use of lasers in space is no longer new. Lasers are being used for satellite-to-satellite crosslinking. Laser communication can transmit orders-of-magnitude more data using orders-of-magnitude less power and can do so with minimal risk of exposure to the sending and receiving terminals. What is new is using lasers as the uplink and downlink between the terrestrial segment and the space segment of satellite systems. More so, the use of lasers to transmit and receive data between moving terrestrial segments (e.g., ships at sea, airplanes in flight) and geosynchronous satellites is burgeoning. This manuscript examines the technological maturation of employing lasers as the signal carrier for satellite communications linking terrestrial and space systems. The purpose of the manuscript is to develop key performance parameters (KPPs) to inform U.S. Department of Defense initial capabilities documents (ICDs) for near-future satellite acquisition and development. By appreciating the history and technological challenges of employing lasers rather than traditional radio frequency sources for satellite uplink and downlink signal carrier, this manuscript recommends ways for the U.S. Department of Defense to employ lasers to transmit and receive high bandwidth, large-throughput data from moving platforms that need to retain low probabilities of detection, intercept, and exploitation (e.g., carrier battle group transiting to a hostile area of operations, unmanned aerial vehicle collecting over adversary areas). The manuscript also intends to identify commercial sector early-adopter fields and those fields likely to adapt to laser employment for transmission and receipt.U.S. Air Forc

Injection field criteria for high energy synchrotrons

Quantitative criteria are proposed for distinguishing "high" and "low" injection fields in high-energy accelerators. The distinction depends on the aperture scale as well as the synchrotron energy

UDHR and modern slavery: exploring the challenges of fulfilling the universal promise to end slavery in all its forms

This article reflects on the prohibition of slavery set out in article 4 of the 1948 Universal Declaration of Human Rights, and analyses efforts undertaken in the years since to fulfil this commitment. It first addresses the evolution in the prohibition from historic forms of slavery to contemporary forms of slavery and human trafficking. Second, the article examines the Modern Slavery Act 2015 and the National Referral Mechanism to appreciate the UK’s efforts to implement various international commitments to prohibit slavery, noting that the current focus towards criminalisation and the meagre support offered as victim protection does not constitute a sufficiently comprehensive strategy towards effective prohibition. Third, areas for reform are identified that could reorient government strategy toward more effective victim protection and support, starting with better identification of victims. And finally, the article argues in favour of actions that seek to prevent modern slavery crimes and abuse, including with a more robust regulatory framework that engages private sector actors to recognise the risks of slavery and exclude forced labour from supply chains

Injection field criteria for high energy synchrotrons

Quantitative criteria are proposed for distinguishing "high" and "low" injection fields in high-energy accelerators. The distinction depends on the aperture scale as well as the synchrotron energy

Locating the source of an acoustic wave equation using likelihood estimates from the kalman filter applied to surface readings

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonCardiovascular disease (CVD) was the second-largest cause of death in the United Kingdom in 2014 [1], accounting for 32% of all deaths in 2009 [2]. CVD encompasses many diseases, one of which is coronary artery disease (CAD), otherwise known as atherosclerosis. Atherosclerosis is the build-up of fatty material, called plaque, inside the wall of the artery. Over time, this plaque will grow too large or break o , causing a blockage resulting in a heart attack. Currently, mortality from CAD has decreased by 72% between 1979 and 2013 [3]. However, predictions show that if the increasing trend of Body Mass Index (BMI) continues, then mortality from CAD could start increasing again [4]. There are several di erent methods currently available to the National Health Service (NHS) to diagnose CAD. However, there are long waiting lists and expensive costs associated with current diagnosis methods. Our aim is to look at a non-invasive approach of diagnosing CAD. We have limited our investigation to simple model problems. Therefore, further work would be required to consider more complex cases which align with the real-world application. In this thesis, we consider both 1-dimensional (1D) and 2-dimensional (2D) problems modelled by an acoustic wave equation with a forcing function which attempts to emulate a localised disturbance caused by CAD.We use an explicit nite di erence method (FDM) to approximate the solution in our partial di erential equation (PDE) and discard the disturbance location used. Having added noise to these approximations in an attempt to mimic noise from real readings, we record these approximations at speci c locations on the surface of our domains to imitate data collected from actual sensors. Using this data in the Kalman lter (KF), where guesses for the disturbance location are made, we can estimate the approximation of u throughout our domain. Using data generated by the KF, we compute likelihood estimates for each guess made and obtain the most probable disturbance location used to generate our sensor readings.Engineering and Physical Science Research Counci

Vertical Carbon Nanotube Device in Nanoporous Templates

A modified porous anodic alumina template (PAA) containing a thin CNT catalyst layer directly embedded into the pore walls. CNT synthesis using the template selectively catalyzes SWNTs and DWNTs from the embedded catalyst layer to the top PAA surface, creating a vertical CNT channel within the pores. Subsequent processing allows for easy contact metallization and adaptable functionalization of the CNTs and template for a myriad of applications