Why don't zombies like hibiscus tea? A multi-subject approach to photosynthesis through the use of Grätzel cells

Traditionally, photosynthesis has been seen as the domain of biology, with some input from chemistry when dealing with chromatography, while, apart from a passing reference to the colour of leaves, physics has tended to steer clear of the process that provides the lifeblood of human existence. This article outlines how a recent technological advance can be used as a teaching resource in all three branches of science

The doctrine of authority in the theology of P.T. Forsyth

Not availabl

Studies in the doctrine of grace in British theology – James Denny to D.M. Baillie

The thesis aims to consider some aspects of British theology in the first half of the twentieth century through the thinking of five representative figures on the theme of grace. The first two chapters give a broad historical introduction (I) and an outline of theological thinking in Britain during the period (II).James Denney (III) is chosen as a representative of an 'orthodox' Protestant approach. Arguing chiefly from the Pauline epistles he defends a 'substitutionary' view of atonement. In contrast Hastings Rashdall (IV) working largely from a historical survey and trying to present a moral view acceptable to modern man criticised 'substitutionary' thinking and advocated an 'Abelardian' or 'moral influence' view. This chapter concludes with a discussion of the two views so far considered. John Oman (v) criticises traditional ideas of grace as omnipotent power and advances the view of grace as 'fatherly persuasion' which is always available. This rests on his view of the relation between the Natural and the Supernatural. Oliver Quick (VI) is chosen for his more Catholic approach. He understands the work of Christ under the 'sacrificial' model and has a richer view of worship and sacraments underlying this is the idea of a sacramental universe. Finally, Donald Baillie (VII) is seen as a mediating figure. Here the stress is more on the experience of grace, and the use of the 'paradox of g race' as an approach to Christology is considered. The conclusion (VIII) suggests that there have been two traditional approaches to the understanding of grace, the Protestant and the Catholic, but that a third has emerged which begins from creation rather than redemption. As far as British theology is concerned it is chiefly represented by Oman. It is widely influential but its influence is not always recognised

The jet and counterjet of 3C 270 (NGC 4261) viewed in the X-ray with Chandra

The radio source 3C 270, hosted by NGC 4261, is the brightest known example of counterjet X-ray emission from a low-power radio galaxy. We report on the X-ray emission of the jet and counterjet from 130 ks of Chandra data. We argue that the X-ray emission is synchrotron radiation and that the internal properties of the jet and counterjet are remarkably similar. We find a smooth connection in X-ray hardness and X-ray to radio ratio between the jet and one of the X-ray components within the core spectrum. We observe wedge-like depressions in diffuse X-ray surface brightness surrounding the jets, and interpret them as regions where an aged population of electrons provides pressure to balance the interstellar medium of NGC 4261. About 20% of the mass of the interstellar medium has been displaced by the radio source. Treating 3C 270 as a twin-jet system, we find an interesting agreement between the ratio of jet-to-counterjet length in X-rays and that expected if X-rays are observed over the distance that an outflow from the core would have traveled in ~6x10^4 yr. X-ray synchrotron loss times are shorter than this, and we suggest that most particle acceleration arises as a result of turbulence and dissipation in a stratified flow. We speculate that an episode of activity in the central engine beginning ~6x10^4 yr ago has led to an increased velocity shear. This has enhanced the ability of the jet plasma to accelerate electrons to X-ray-synchrotron-emitting energies, forming the X-ray jet and counterjet that we see today.Comment: Accepted for publication in the MNRAS. 12 pages, 10 figs (some in color).Some figures reduced in qualit

Push-and-Twist Drillstring Assemblies

Deep drilling using a rigid drillstring requires the assembly and disassembly of multiple drill pipes. The interfaces between these pipes provide a challenge for automation because they must transmit large drilling forces and movements while, at the same time, minimise the actions and forces that are needed to make or break the interface. A geometry which can address these requirements has been suggested by the authors. This approach would use a push-and-twist bayonet system to engage drill pipes, with torque transmission through the bayonet studs. A variety of L-shaped and T-shaped bayonet paths have been proposed to ensure that separation of specific drill pipes can be achieved through a combination of clockwise and counter-clockwise rotation and single-point clamping. Sustained drills into a variety of media are used to show that percussive impulses are transmitted across the interface, whilst ensuring that the drill interface is able to withstand the shock loading associated with hammer-drilling. These tests are repeated and contrasted to control experiments using a single-piece control drillstring, which allows the performance of the interface and any degradation over time to be quantified. Results suggest that the bayonet-style connection performs well with no significant performances losses encountered or structural degradation noted

Engineering compliance and worker resistance in UK further education: The creation of the Stepford lecturer

PurposeThe purpose of this paper is to explore control and resistance in the UK further education (FE) sector by examining senior college managers’ attempts to engineer culture change and analysing lecturers’ resistance to such measures.Design/methodology/approachData were derived from interviews with managers and lecturers in two English FE colleges and the analysis of college documents. Interview data were analysed thematically using NVIVO software.FindingsIt was found that college managers sought to build consent to change among lecturers based on values derived from “business‐like” views. Culture change initiatives were framed within the language of empowerment but lecturers’ experiences of change led them to feel disempowered and cynical as managers imposed their view of what lecturers should be doing and how they should behave. This attempt to gain control of the lecturers’ labour process invoked the “Stepford” lecturer metaphor used in the paper. Paradoxically, as managers sought to create lecturers who were less resistant to change, individualised resistance intensified as managers’ attempts to win hearts and minds conspicuously failed.Research limitations/implicationsThe paper draws on data from two case study colleges and this limits the generalisability of its findings.Practical implicationsThe paper provides a critical perspective on the received wisdom of investing in stylised change programmes that promise to win staff over to change but which may alienate those they purport to empower and ultimately lead to degenerative workplace relations.Originality/valueThe paper offers new insights into culture change from the juxtaposed, polarised views of senior managers and lecturers, while highlighting the negative consequences of imposing change initiatives from above.</jats:sec

Inverse Simulation as a Tool for Fault Detection and Isolation in Planetary Rovers

With manned expeditions to planetary bodies beyond our own and the Moon currently intractable, the onus falls upon robotic systems to explore and analyse extraterrestrial environments such as Mars. These systems typically take the form of wheeled rovers, designed to navigate the difficult terrain of other worlds. Rovers have been used in this role since Lunokhod 1 landed on the Moon in 1970. While early rovers were remote controlled, communication latency with bodies beyond the Moon and the desire to improve mission effectiveness have resulted in increasing autonomy in planetary rovers. With an increase in autonomy, however, comes an increase in complexity. This can have a negative impact on the reliability of the rover system. With a fault-free system an unlikely prospect and human assistance millions of miles away, the rover must have a robust fault detection, isolation and recovery (FDIR) system. The need for comprehensive FDIR is demonstrated by the recent Chinese lunar rover, Yutu (or “Jade Rabbit”). Yutu was rendered immobile 42 days after landing and remained so for the duration of its operational life: 31 months. While its lifespan far exceeded its expected value, Yutu's inability to move severely impaired its ability to perform its mission. This clearly highlights the need for robust FDIR. A common approach to FDIR is through the generation and analysis of residuals. Output residuals may be obtained by comparing the outputs of the system with predictions of those outputs, obtained from a mathematical model of the system which is supplied with the system inputs. Output residuals allow simple detection and isolation of faults at the output of the system. Faults in earlier stages of the system, however, propagate through the system dynamics and can disperse amongst several of the outputs. This problem is exemplified by faults at the input, which can potentially excite every system state and thus manifest in every output residual. Methods exist for decoupling and analysing output residuals such that input faults may be isolated, however, these methods are complex and require comprehensive development and testing. A conceptually simpler approach is presented in this paper. Inverse simulation (InvSim) is a numerical method by which the inputs of a system are obtained for a desired output. It does so by using a Newton-Raphson algorithm to solve a non-linear model of the system for the input. When supplied with the outputs of a fault-afflicted system, InvSim produces the input required to drive a fault-free system to this output. The fault therefore manifests itself in this generated input signal. The InvSim-generated input may then be compared to the true system input to generate input residuals. Just as a fault at an output manifests itself in the residual for that output alone, a fault at an input similarly manifests itself only in the residual for that input. InvSim may also be used to generate residuals at other locations in the system, by considering distinct subsystems with their own inputs and outputs. This ability is tested comprehensively in this paper. Faults are applied to a simulated rover at a variety of locations within the system structure and residuals generated using both InvSim and conventional forward simulation. Residuals generated using InvSim are shown to facilitate detection and isolation of faults in several locations using simple analyses. By contrast, forward simulation requires the use of complex analytical methods such as structured residuals or adaptive thresholds

Determining paediatric patient thickness from a single digital radiograph – a proof of principle

Objective: This work presents a proof of principle for a method of estimating the thickness of an attenuator from a single radiograph using the image, the exposure factors with which it was acquired and a priori knowledge of the characteristics of the X-ray unit and detector used for the exposure. It is intended this could be developed into a clinical tool to assist with paediatric patient dose audit, for which a measurement of patient size is required. Methods: The proof of principle used measured pixel value and effective linear attenuation coefficient to estimate the thickness of a Solid Water attenuator. The kerma at the detector was estimated using a measurement of pixel value on the image and measured detector calibrations. The initial kerma was estimated using a lookup table of measured output values. The effective linear attenuation coefficient was measured for Solid Water at varying kVp. 11 test images of known and varying thicknesses of Solid Water were acquired at 60, 70 and 81 kVp. Estimates of attenuator thickness were made using the model and the results compared to the known thickness. Results: Estimates of attenuator thickness made using the model differed from the known thickness by 3.8 mm (3.2%) on average, with a range of 0.5–10.8 mm (0.5–9%). Conclusion: A proof of principle is presented for a method of estimating the thickness of an attenuator using a single radiograph of the attenuator. The method has been shown to be accurate using a Solid Water attenuator, with a maximum difference between estimated and known attenuator thickness of 10.8 mm (9%). The method shows promise as a clinical tool for estimating abdominal paediatric patient thickness for paediatric patient dose audit, and is only contingent on the type of data routinely collected by Medical Physics departments. Advances in knowledge: A computational model has been created that is capable of accurately estimating the thickness of a uniform attenuator using only the radiographic image, the exposure factors with which it was acquired and a priori knowledge of the characteristics of the X-ray unit and detector used for the exposure. </jats:sec