Showing papers by "Cranfield University published in 1987"

Aspects of the structure, function, and applications of superoxide dismutase

Abstract: The current status of superoxide dismutase (SOD) is that it is an enzyme with diverse ramifications. This review attempts an understanding of SOD as a structural, functional, and biological entity. Accordingly, the review is in three parts. The first part discusses SOD in terms of protein structure, proceeding from primary to secondary and three-dimensional structure for the three forms of SOD: copper/zinc SOD, manganese SOD, and iron SOD. This is the order of structural knowledge of the enzyme. Iron SOD is an enzyme of prokaryotes and some higher plants. Manganese SOD is an enzyme of prokaryotes and eukaryotes. Copper/zinc SOD is an enzyme of eukaryotes and certain prokaryotes. The evolutionary relationships of the three forms of SOD, the status of the copper/zinc SOD gene in prokaryotes, and the cloning and sequencing of SOD genes are discussed. The second part of the review deals with the catalytic mechanism of SOD in the three forms of the enzyme. Structural and mechanistic conclusions from various spectroscopic studies are critically considered. A detailed picture is given of the active site of copper/zinc SOD. The third part is a review of SOD in the general context of oxygen toxicity. After consideration of the question of superoxide toxicity and superoxide pathology, several areas in which SOD has been investigated or used as a tool in a biochemical, pharmacological, or clinical context are discussed, including population genetics; trisomy 21; development and senescence; the nutritional copper, zinc, and manganese status; hemolysis and anemia; oxygen toxicity in the lung and nervous system; inflammation, autoimmune disease and chromosome breakage, ischemia and degenerative changes; radiation damage; and malignancy. A comprehensive picture is given of measurements of SOD activity in disease states, and the question of superoxide-related disease is considered at several points.

A comparison of numerical flux formulas for the Euler and Navier-Stokes equations

Abstract: Numerical flux formulas for the convection terms in the Euler or Navier-Stokes equations are analyzed with regard to their accuracy in representing steady nonlinear and linear waves (shocks and entropy/shear waves, respectively) Numerical results are obtained for a one-dimensional conical Navier-Stokes flow including both a shock and a boundary layer Analysis and experiments indicate that for an accurate representation of both layers the flux formula must include information about all different waves by which neighboring cells interact, as in Roe's flux-difference splitting In comparison, Van Leer's flux-vector splitting, which ignores the linear waves, badly diffuses the boundary layer The results of MacCormack's scheme, if properly tuned, are significantly better The use of a sufficiently detailed flux formula appears to reduce the number of cells required to resolve a boundary layer by a factor 1/2 to 1/4 and thus pays off

Do Women Entrepreneurs Require Different Training

Abstract: This paper analyzes the characteristics of male and female participants attending pioneering entrepreneurship development programs, which form part of an economic strategy directed at increasing the quality and quantity of new firms. The participants did not need to have a business plan, finance available or formal education, but must have had a “reasonably feasible idea”. The results show significant differences between the characteristics of the male and female entrepreneurs, and the businesses which they form.

The management of the personnel function

Abstract: This article examines the way the personnel role has developed in the United Kingdom, and argues that three main models of personnel management may be discerned. The way these models have been influenced by the recession is discussed and it is suggested that the personnel function, both as a specialized activity and as one aspect of all managerial work has been forced to change, in response to the need for increased competitiveness, to structural and ideological changes, and to industrial reorganization. Looking to the future, the paper anticipates the ‘balkanization’ of the personnel function as new specialisms emerge, and as personnel activity becomes more closely associated with corporate marketing strategies.

Application of tetrathiafulvalenes in bioelectrochemical processes

Abstract: Bioelectrochemical processes use tetrathiafulvalenes (TTF) as a mediator of electron transfer between biological systems and electrodes. Typically it finds use in bio­electrochemical assays, e.g. involving glucose oxidase mediated oxidation of glucose. The TTF may be immobilised on the electrode surface, as may one or more enzymes involved in the process.

New DNA Technology and the DNA Biosensor

Abstract: Recently there has been an increasing demand to produce systems for the detection of specific DNA sequences that are amenable to non-specialised laboratories. This demand has led to many innovative and novel approaches to DNA analysis which may collectively be termed ′new DNA technology′. Here, we review these advances in relation to their applicability for the production of a DNA biosensor. The present state of the art is described and future possibilities are considered.

A multicriteria objective function optimization scheme for laminated composites for use in multilevel structural optimization schemes

Abstract: A multilevel optimization scheme for large laminated composite structures is proposed, and a suitable element/lower-level optimization scheme using a multicriteria objective function is developed. The objective function combines a weight function and a strain energy change function into a utility function which is minimized and in which the relative importance of each part is reflected by weighting coefficients. Minimizing the change in strain energy ensures load path continuity in the overall structure when switching between upper and lower levels of optimization, and so decouples the problems at the two levels. Continuous lamina thickness and ply-angle variation is used to minimize the objective function while satisfying strain, buckling, and gauge constraints. Numerical applications are given to illustrate the effect of the weighting coefficients in the objective function on the final result, and to demonstrate the algorithm's effectiveness as a pure weight minimization routine.

Consumer Boycotts and Consumer Sovereignty

Abstract: Consumer boycotts may be understood as consumer behaviour, and the concept of consumer sovereignty is identified here as the implicit paradigm for the marketing desciple, this is then applied to illustrate and explain the workings of consumer boycotts which are seen to have two dimensions: degree and domain, information is shown to be important in determining the domain of consumer sovereignty and pressure groups may play an important role in providing this. Three case examples of boycotts support the argument.

A Fast Riemann Solver with Constant Covolume Applied to the Random Choice Method

Abstract: The Riemann problem for the unsteady, one dimensional Euler equations together with the constant-covolume equation of state is solved exactly. The solution is then applied to the Random Choice Method to solve the general initialboundary value problem for the Euler equations. The iterative procedure to find p*, the pressure between the acoustic waves, involves a single algebraic (non-linear) equation, all other quantities follow directly throughout the x - t plane, except within rarefaction fans, where an extra iterative procedure is required. Starting in 1946 as the College of Aeronautics, the Cranfield Institute of Technology was granted university status in 1969. In 1993 it changed its name to Cranfield University.

The development of whole cell biosensors for on‐line screening of herbicide pollution of surface waters

Abstract: The use of mediator assisted amperometric whole-cell biosensors, monitoring microbial photosynthetic electron transfer, to screen for herbicides in intake protection by the water industry is described. Cells harvested from axenic cultures are loaded onto bacteriological filters and held against a working carbon electrode polarised against the silver chloride reference. Redox mediators are reduced by the microorganisms and then reoxidised at the working electrode resulting in a flow of current. For on-line applications the sensors are controlled by a programmable electrochemical analyser (Artek) and housed in specially designed perspex flow cells which incorporate light emitting diodes (LEDs) for photosynthetic stimulation. A range of cyanobacteria and algae have been tested, but biosensors incorporating unicellular cyanobacteria have proven the most successful. Results obtained using the cyanobacterium Synechococcus show detection levels of less than 200 ppb with response times of less than ten minutes for selected herbicides. Sensor stability in the absence of pollutant poisoning has been found to be greatly influenced by the choice of mediator. Membrane penetrating mediators such as -benzoquinone reduce sensor life to about 24 hours, while a sensor life of up to six days has been achieved with ferricyanide.

A re‐appraisal of the role of marketing planning

Abstract: Reviews development of marketing planning literature and the success of its prescriptive advice, based on an empirical study of marketing planning practices. The authors call for a change of perspective, from the present state of concentrating almost exclusively on the “medicine” rather than on the “patient”. Stresses the need to recognise that there is a symbiotic relationship between the patient and the cure. The stages of development of a company are outlined, together with the role of “culture carriers”. One of the main results of the actions of culture carriers is that they can determine the level of acceptance of marketing planning—four levels are identified and illustrated.

Initial Enzymatic Steps In The Degradation Of Alpha-Pinene By Pseudomonas Fluorescens Ncimb 11671

Abstract: The initial steps in the degradation of the bicyclic monoterpene, (–)-alpha-pinene, by a new isolate, Pseudomonas fluorexem NCIMB 11671, are described. Degradation is initiated by an oxygenative attack upon the unsaturated position in the molecule to form the corresponding epoxide, catalysed by a pyridine nucleotide-dependent oxygenase with a narrow substrate specificity. The epoxide undergoes rapid rearrangement and concomitant decyclisation to form a di-unsaturated aldehyde, in which both the cyclobutane and cyclohexane rings of the parent molecule are broken, without the insertion of further oxygen species or the appearance of other intermediate compounds. This represents a new enzymatic mechanism for the disruption of a cyclic ring system.

Thermal Design of Compound Parabolic Concentrating Solar-Energy Collectors

Abstract: Despite the vast attention devoted recently to the design and development of effective collectors for harnessing solar energy at medium and high temperatures (>100°C), there is still a lack of a rigorous mathematical model describing their behaviours and which would provide an adequate basis for their design optimisation. Since its invention in 1974 [1] many advances in the design of the compound parabolic concentrator solar—energy collectors have been made. The analysis of the concentrator’s optical behaviour with respect to incident radiation has been undertaken previously [2,3]. However, insufficient in—depth studies have been reported which relate the solar—energy capture behaviour to the overall thermal performance of the CPC collector. To date the mathematical formulations employed [4,5] are over simplified. The pertinent materials research has been aimed at improving the properties, such as the absorptance, emittance and reflectance [6,7,8], but the resulting materials are frequently excessively expensive. However, for the commercial viability of the CPC collectors, low cost materials must be used.

The Management Factor in Acquisition Performance

Abstract: Theoretical development and empirical investigation into the performance of mergers and acquisitions are reviewed. In parallel, recent research which links the performance of organisations to the presence of an appropriate corporate culture is discussed. From these two theoretical platforms, it is argued that the performance of acquisitions is determined by a match of culture and those organisational expectations which avoid post‐acquisition managerial indigestion. Finally, a programme of research is proposed to measure the performance of acquisitions against the criteria laid down by the acquiring management, and to determine the impact of culture clashes on those acquisitions perceived to have failed.

Nocturnal behaviour of adults of Heliothis armigera (Hübner) (Lepidoptera: Noctuidae) in the Sudan Gezira and pest control implications

Abstract: Field and cage observations were made on Heliothis armigera (Hubner) in the Sudan Gezira to quantify nocturnal patterns of moth emergence, copulation and oviposition and the ages at which copulation and egg-laying occur. The flight activity pattern of males, virgins and inseminated females was assessed for crops with scarce or abundant sources of honeydew or nectar. A pronounced redistribution of moths between crops during the peak flight activity period (18.15-19.30 h) was demonstrated and measured, with the net exchange being approximately balanced. The direction of this movement was dependent upon the attractiveness of crops for feeding or oviposition. Male and female moths developing from larvae reared on groundnuts had significantly shorter lifespans when fed only water and less fat-body at emergence than moths developing from larvae reared on sorghum. When offered sugar solution, lifespans were significantly greater and differences in the lifespan of moths from groundnuts or sorghum were no longer evident. Adult feeding appears to compensate for any deficiencies associated with a larval diet of groundnut. Feeding was important for adult survival; there was a strong attraction of moths to crops with plentiful honeydew or nectar. A descriptive behavioural model is presented for the first half of adult life, until peak oviposition, and the uses of this model for pest management are discussed.

A comparison of supervised maximum likelihood and decision tree classification for crop cover estimation from multitemporal LANDSAT MSS data

Abstract: Supervised maximum likelihood classification was compared with a supervised binary decision tree for crop classification from multitemporal LANDSAT MSS data. Similar levels of classification accuracy were obtained using both algorithms, but the ease of training and computational simplicity of the binary decision tree suggest that this algorithm may be a viable alternative to the maximum likelihood for the analysis of data sets with high dimensionality such as multitemporal LANDSAT MSS data.