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Step Change (step + change)
Selected AbstractsThe effects of low summer flow on wild salmon (Salmo salar), trout (Salmo trutta) and grayling (Thymallus thymallus) in a small streamFRESHWATER BIOLOGY, Issue 12 2009W. D. RILEY Summary 1.,The effects of an experimentally imposed low summer flow on habitat use, displacement and survival of wild populations of juvenile salmon (Salmo salar), trout (Salmo trutta) and grayling (Thymallus thymallus) were investigated in a chalk stream. The habitat use and mobility of the fish in response to reduced flow was determined using passive integrated transponder-tag detector systems. 2.,Habitat use was compared to that available under different flow regimes. These consisted of an initial control phase of normal summer flow, an abrupt step change to 21 days of low flow, followed by a second control phase when normal summer flow was reinstated. First year (0+) salmon showed little change in their preferred substratum during low flow, whilst 1+ salmon increased their use of gravel and reduced that of mud during the day. Both 0+ and 1+ salmon were found in relatively deep water by day under low flow, whilst 1+ salmon preferred relatively shallow water at night. First year trout increased their use of gravel and reduced their use of mud and submerged tree roots under low flow, using relatively deep and fast flowing water by day. Older trout increased their use of gravel and occupied relatively deep, slow flowing water by day and relatively fast and shallow water at night. Grayling showed little change in their preferred substratum, but occupied relatively shallow water following the introduction of low flow. 3.,The range of movement of juvenile salmon increased at night under low flow, and was greater by day under normal flow. There was also an initial increase in the range of movement of 0+ trout following the introduction of low flow. Older trout initially moved less under low flow. With reduced flow, the range of movement by grayling increased significantly during the day. 4.,There was no net downstream displacement of any species with reduced flow, but the mortality rate in 0+ salmon, trout and grayling increased. This may be related to their small size and increased vulnerability to predation under low flow, and due to the reduction in depth and loss of the stream margins that are normally the preferred habitat of 0+ trout and grayling. 5.,The findings of this field study have implications for the management of braided, and highly regulated, chalk stream systems. In particular, they underline the importance of the stream margins as juvenile salmonid habitat, and suggest that a flow management strategy is required to mitigate for drought conditions. Such a strategy might include pre-emptive controls on abstraction and the maintenance of river flow via a prioritised route, predetermined using fish or habitat surveys, to minimise the effects of drought conditions on the more vulnerable or valued fish groups. [source] An In Situ Device to Measure Oxygen in the Vadose Zone and in Ground Water: Laboratory Testing and Field EvaluationGROUND WATER MONITORING & REMEDIATION, Issue 2 2008Bradley M Patterson Oxygen probes developed to measure in situ oxygen concentrations in gaseous and aqueous environments were evaluated in laboratory tests and during long-term field evaluation trials at contaminated sites. The oxygen probes were shown to have a linear calibration and to be accurate compared to conventional dissolved oxygen electrodes and gas chromatography, both of which require labor-intensive sample collection and processing. The probes, once calibrated, required no maintenance or recalibration for up to a period of 7 years in low-oxygen environments, demonstrating long-term stability. Times to achieve 90% of the stabilized concentration (t90) after a step change in aqueous oxygen concentration were 100,120 min in laboratory experiments and up to 180 min in field experiments, which is adequate for monitoring subsurface changes. Field application data demonstrated that the oxygen probes could monitor oxygen concentrations in hydrocarbon-contaminated ground water to a depth of 20 m below the water table or in pyritic vadose zones over extended periods. During bioremediation field trials, oxygen monitoring enabled estimation of oxygen utilization rates by microorganisms and hydrocarbon biodegradation rates. Also, probes were able to monitor the development of ground water desaturation during air sparging trials, enabling the automated assessment of the distribution of injected air. [source] Chartered Insurance Institute: influencing the course of industry changeJOURNAL OF PUBLIC AFFAIRS, Issue 3 2009Daniel Pedley The Chartered Insurance Institute's campaign to raise professionalism in financial advice is shaping the future of the industry. Our aim is to protect the public and ensure better levels of service by driving a step change in behaviour and professional standards. Success factors have included clear aims and objectives (concentrating on a single issue), the ability to build momentum for our proposals and sustaining interest, and developing an industry consensus in support of our proposals. The campaign has influenced the thinking of the regulator with them adopting our proposals around raising professionalism. Copyright © 2009 John Wiley & Sons, Ltd. [source] Evidence for Changing Flood Risk in New England Since the Late 20th Century,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2009Mathias J. Collins Abstract:, Long-term flow records for watersheds with minimal human influence have shown trends in recent decades toward increasing streamflow at regional and national scales, especially for low flow quantiles like the annual minimum and annual median flows. Trends for high flow quantiles are less clear, despite recent research showing increased precipitation in the conterminous United States over the last century that has been brought about primarily by an increased frequency and intensity of events in the upper 10th percentile of the daily precipitation distribution , particularly in the Northeast. This study investigates trends in 28 long-term annual flood series for New England watersheds with dominantly natural streamflow. The flood series are an average of 75 years in length and are continuous through 2006. Twenty-five series show upward trends via the nonparametric Mann-Kendall test, 40% (10) of which are statistically significant (p < 0.1). Moreover, an average standardized departures series for 23 of the study gages indicates that increasing flood magnitudes in New England occurred as a step change around 1970. The timing of this is broadly synchronous with a phase change in the low frequency variability of the North Atlantic Oscillation, a prominent upper atmospheric circulation pattern that is known to effect climate variability along the United States east coast. Identifiable hydroclimatic shifts should be considered when the affected flow records are used for flood frequency analyses. Special treatment of the flood series can improve the analyses and provide better estimates of flood magnitudes and frequencies under the prevailing hydroclimatic condition. [source] Physiological and anatomical changes during the early ontogeny of the heteroblastic bromeliad, Vriesea sanguinolenta, do not concur with the morphological change from atmospheric to tank formPLANT CELL & ENVIRONMENT, Issue 11 2004G. ZOTZ ABSTRACT Two distinct morphological forms characterize the ontogeny of many epiphytic bromeliads. Smaller plants exhibit an atmospheric habit, while larger plants form water-impounding tanks. The study of the functional significance of heteroblasty in epiphytes is severely hampered by considerable size-related variation in morphological, anatomical and physiological parameters. To overcome this problem, plants of varying size of both atmospheric and tank form were included in the present study with Vriesea sanguinolenta. The results show that virtually all morphological, anatomical and physiological characteristics vary during ontogeny, but changes were rarely directly related to the step change in gross morphology. Changes were either: (1) gradual from smallest atmospheric to small tank (e.g. leaf divergence angles, reduction in photosystem II efficiency during drought, speed of recovery after drought); (2) there was no change between atmospheric and small tank, but a gradual or step change within the tank form (stomatal density, relationship of leaf N and specific leaf area); or (3) developmental patterns were more complicated with decreases and increases during ontogeny (photosynthetic capacity, carbon isotope ratios, abscisic acid levels during drought). Although the comparisons between ontogenetic phases were always confounded by size differences, a hypothetical small tank plant is expected to suffer higher water loss than a real atmospheric, whereas a hypothetical, large atmospheric plant would show reduced access to resources, such as nutrients, in comparison with the real tank. The present results are consistent with the notion of heteroblasty as an adaptation of early ontogenetic stages to drought, but highlight that size-related variation greatly modifies any difference directly associated with the step change from atmospheric to tank. [source] Thermal analysis of poly(3-hydroxybutyrate- co -3-hydroxyvalerate) irradiated under vacuumPOLYMER INTERNATIONAL, Issue 11 2004Huili Yang Abstract Poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) was irradiated by 60Co ,-rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one-step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight-loss step change. The onset degradation temperature (To) and the temperature of maximum weight-loss rate (Tp) of control and irradiated PHBV were in line with the heating rate (°C min,1). To and TP of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that 60Co ,-radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (Tm) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry [source] Knowledge management and communities of practice in the private sector: lessons for modernizing the National Health Service in England and WalesPUBLIC ADMINISTRATION, Issue 4 2002S.P. Bate The National Health Service (NHS) in England and Wales has embarked upon a radical and far,reaching programme of change and reform. However, to date the results of organizational quality and service improvement initiatives in the public sector have been mixed, if not to say disappointing, with anticipated gains often failing to materialize or to be sustained in the longer term. This paper draws on the authors' recent extensive research into one of the principal methodologies for bringing about the sought after step change in the quality of health care in England and Wales. It explores how private sector knowledge management (KM) concepts and practices might contribute to the further development of public sector quality improvement initiatives in general and to the reform of the NHS in particular. Our analysis suggests there have been a number of problems and challenges in practice, not least a considerable naïvety around the issue of knowledge transfer and ,knowledge into practice' within health care organizations. We suggest four broad areas for possible development which also have important implications for other public sector organizations. [source] A clustering approach to identify the time of a step change in Shewhart control chartsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 7 2008Mehdi Ghazanfari Abstract Control charts are the most popular statistical process control tools used to monitor process changes. When a control chart indicates an out-of-control signal it means that the process has changed. However, control chart signals do not indicate the real time of process changes, which is essential for identifying and removing assignable causes and ultimately improving the process. Identifying the real time of the change is known as the change-point estimation problem. Most of the traditional methods of estimating the process change point are developed based on the assumption that the process follows a normal distribution with known parameters, which is seldom true. In this paper, we propose clustering techniques to estimate Shewhart control chart change points. The proposed approach does not depend on the true values of the parameters and even the distribution of the process variables. Accordingly, it is applicable to both phase-I and phase-II of normal and non-normal processes. At the end, we discuss the performance of the proposed method in comparison with the traditional procedures through extensive simulation studies. Copyright © 2008 John Wiley & Sons, Ltd. [source] Penicillin G splitting in a flow-through electro-membrane reactor with the membrane-bound enzymeASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Pavel Hasal Abstract Penicillin G (PenG) (0.05 mol dm,3 in phosphate buffer, pH = 8) was hydrolyzed in a continuous flow-through electro-membrane reactor (EMR) with the penicillin G acylase (PGA) (EC 3.5.1.11) immobilized in 10% (w/v) polyacrylamide membrane with an area of 900 mm2, thickness of 1 mm and enzyme activity of 100 U cm,3 and 160 U cm,3, respectively. The PenG was continuously fed to the substrate compartment adjacent to one membrane surface. Reaction products were washed from the membrane by a phosphate buffer solution fed to the product compartment adjacent to the other membrane surface. The mean residence time of both streams was varied from 11.3 min to 45 min. An electric field perpendicular to the membrane surface was imposed on the reactor and the electric current density was varied from 0 to 822 A m,2. Substrate conversion was determined as a function of the mean residence time, of the applied electric current density and of the enzyme activity of the membrane. The conversion increased with increasing residence time. The applied electric current increased substrate conversion by 200% at short residence times and at low enzyme activity of the membrane. Oscillatory reaction regime was evoked by step change of the mean residence time of reactant streams in the reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Intensified Process for the Purification of an Enzyme from Inclusion Bodies Using Integrated Expanded Bed Adsorption and RefoldingBIOTECHNOLOGY PROGRESS, Issue 4 2006Matthew H. Hutchinson This work describes the integration of expanded bed adsorption (EBA) and adsorptive protein refolding operations in an intensified process used to recover purified and biologically active proteins from inclusion bodies expressed in E. coli. ,5 -3-Ketosteroid isomerase with a C-terminal hexahistidine tag was expressed as inclusion bodies in the cytoplasm of E. coli. Chemical extraction was used to disrupt the host cells and simultaneously solubilize the inclusion bodies, after which EBA utilizing immobilized metal affinity interactions was used to purify the polyhistidine-tagged protein. Adsorptive refolding was then initiated in the column by changing the denaturant concentration in the feed stream from 8 to 0 M urea. Three strategies were tested for performing the refolding step in the EBA column: (i) the denaturant was removed using a step change in feed-buffer composition, (ii) the denaturant was gradually removed using a gradient change in feed-buffer composition, and (iii) the liquid flow direction through the column was reversed and adsorptive refolding performed in the packed bed. Buoyancy-induced mixing disrupted the operation of the expanded bed when adsorptive refolding was performed using either a step change or a rapid gradient change in feed-buffer composition. A shallow gradient reduction in denaturant concentration of the feed stream over 30 min maintained the stability of the expanded bed during adsorptive refolding. In a separate experiment, buoyancy-induced mixing was completely avoided by performing refolding in a settled bed, which achieved comparable yields to refolding in an expanded bed but required a slightly more complex process. A total of 10% of the available KSI,(His6) was recovered as biologically active and purified protein using the described purification and refolding process, and the yield was further increased to 19% by performing a second iteration of the on-column refolding operation. This process should be applicable for other polyhistidine tagged proteins and is likely to have the greatest benefit for proteins that tend to aggregate when refolded by dilution. [source] Corrective movements in response to displacements in visual feedback are more effective during periods of 13,35 Hz oscillatory synchrony in the human corticospinal systemEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006Alexandros G. Androulidakis Abstract Oscillatory synchronization in the beta (,20 Hz) band is a common feature of human motor control, manifest at cortical and muscular levels during tonic contraction. Here we test the hypothesis that the influence of visual feedback on performance in a positional hold task is increased during bursts of beta-band synchrony in the corticospinal motor system. Healthy subjects were instructed to extend their forefinger while receiving high-gain visual feedback of finger position on a PC screen. Small step displacements of the feedback signal were triggered either by bursts of beta oscillations in scalp electroencephalogram or randomly with respect to cortical beta activity, and the resulting positional corrections expressed as a percentage of the step displacement. Corrective responses to beta and randomly triggered step changes in visual feedback were 41.7 ± 4.9 and 31.5 ± 6.8%, respectively (P < 0.05). A marked increase in the coherence in the beta band was also found between muscle activity and cortical activity during the beta-triggered condition. The results suggest that phasic elevations of beta activity in the corticospinal motor system are associated with an increase in the gain of the motor response to visual feedback during a tonic hold task. Beta activity may index a motor state in which processing relevant to the control of positional hold tasks is promoted, with behavioural consequences. [source] Case studies in Bayesian segmentation applied to CD controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2003A.R. Taylor Identifying step changes in historical process and controller output variables can lead to improved process understanding and fault resolution in control system performance analysis. This paper describes an application of Bayesian methods in the search for statistically significant temporal segmentations in the data collected by a cross directional (CD) control system in an industrial web forming process. CD control systems give rise to vector observations which are often transformed through orthogonal bases for control and performance analysis. In this paper two models which exploit basis function representations of vector times series data are segmented. The first of these is a power spectrum model based on the asymptotic Chi-squared approximation which allows large data sets to be processed. The second approach, more capable of detecting small changes, but as a result is more computationally demanding, is a special case of the multivariate linear model. Given the statistical model of the data, inference regarding the number and location of the change-points is based on numerical Bayesian methods known as Markov chain Monte Carlo (MCMC). The methods are applied to real data and the resulting segmentation relates to real process events. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effects of water storage in the stele on measurements of the hydraulics of young roots of corn and barleyNEW PHYTOLOGIST, Issue 3 2009Ankur Joshi Summary ,,In standard techniques (root pressure probe or high-pressure flowmeter), the hydraulic conductivity of roots is calculated from transients of root pressure using responses following step changes in volume or pressure, which may be affected by a storage of water in the stele. ,,Storage effects were examined using both experimental data of root pressure relaxations and clamps and a physical capacity model. Young roots of corn and barley were treated as a three-compartment system, comprising a serial arrangement of xylem/probe, stele and outside medium/cortex. The hydraulic conductivities of the endodermis and of xylem vessels were derived from experimental data. The lower limit of the storage capacity of stelar tissue was caused by the compressibility of water. This was subsequently increased to account for realistic storage capacities of the stele. ,,When root water storage was varied over up to five orders of magnitude, the results of simulations showed that storage effects could not explain the experimental data, suggesting a major contribution of effects other than water storage. ,,It is concluded that initial water flows may be used to measure root hydraulic conductivity provided that the volumes of water used are much larger than the volumes stored. [source] CIVIL SERVICE REFORM IN THE UK, 1999,2005: REVOLUTIONARY FAILURE OR EVOLUTIONARY SUCCESS?PUBLIC ADMINISTRATION, Issue 2 2007TONY BOVAIRD In December 1999, the UK Civil Service Management Board agreed an internal reform programme, complementing the more externally-oriented ,modernizing government' programme, to bring about major changes in the functioning of the civil service ,,step change' rather than continuous improvement. This paper suggests that the aims of the reform programme were only partially achieved. While some step changes did indeed occur, even such central elements of reform as ,joined-up' working with other public organizations were still only at an initial stage some three years later and others , for example, business planning and performance management systems , have taken 20 years to achieve acceptance within the civil service. It appears that examples of meteoric change are rare in the civil service , the reality of the changes are better characterized as ,evolution' and ,continuous improvement' than ,revolution' and ,step change'. [source] Estimating the Change Point of a Poisson Rate Parameter with a Linear Trend DisturbanceQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 4 2006Marcus B. Perry Abstract Knowing when a process changed would simplify the search and identification of the special cause. In this paper, we compare the maximum likelihood estimator (MLE) of the process change point designed for linear trends to the MLE of the process change point designed for step changes when a linear trend disturbance is present. We conclude that the MLE of the process change point designed for linear trends outperforms the MLE designed for step changes when a linear trend disturbance is present. We also present an approach based on the likelihood function for estimating a confidence set for the process change point. We study the performance of this estimator when it is used with a cumulative sum (CUSUM) control chart and make direct performance comparisons with the estimated confidence sets obtained from the MLE for step changes. The results show that better confidence can be obtained using the MLE for linear trends when a linear trend disturbance is present. Copyright © 2005 John Wiley & Sons, Ltd. [source] A magnitude-robust control chart for monitoring and estimating step changes for normal process meansQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 6 2002Joseph J. Pignatiello Jr Abstract Statistical process control charts are intended to assist operators of a usually stable system in monitoring whether a change has occurred in the process. When a change does occur, the control chart should detect it quickly. If the operator can also be provided information that aids in the search for the special cause, then critical off-line time can be saved. We investigate a process-monitoring tool that not only provides speedy detection regardless of the magnitude of the process shift, but also supplies useful change point statistics. A likelihood ratio approach can be used to develop a control chart for permanent step change shifts of a normal process mean. The average run length performance for this chart is compared to that of several cumulative sum (CUSUM) charts. Our performance comparisons show that this chart performs better than any one CUSUM chart over an entire range of potential shift magnitudes. The likelihood ratio approach also provides point and interval estimates for the time and magnitude of the process shift. These crucial change-point diagnostics can greatly enhance special cause investigation. Copyright © 2002 John Wiley & Sons, Ltd. [source] The effect of predictive display on the control of step changes in effect site sevoflurane levels,ANAESTHESIA, Issue 8 2010R. R. Kennedy Summary Graphical displays of past and future levels of drugs may be a useful adjunct to manual dosing. We have previously found that a display of predicted future values speeds step changes in end-tidal sevoflurane. In this study anaesthetists made step changes of 0.3% in effect site sevoflurane, with and without the display and as increases and decreases. We analysed 91 changes. When the predictive display was present, users made larger vaporiser dial changes of 3.9% vs 3.1% (95% CI for the difference ,1.3% to ,0.01%, p = 0.046) reflected in larger end-tidal changes (95% CI for the difference ,0.009 vol% to ,0.34 vol%, p = 0.06). There was no difference in the speed of change (220 vs 227 s (95% CI for the difference ,51 to 32 s)), or in the accuracy of the change. In this study the predictive display influenced the magnitude of the step changes made by anaesthetists but did not affect the speed or overall accuracy of the change. [source] Novel Process Windows , Gate to Maximizing Process Intensification via Flow ChemistryCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2009V. Hessel Abstract Driven by the economics of scale, the size of reaction vessels as the major processing apparatus of the chemical industry has became bigger and bigger [1, 2]. Consequently, the efforts for ensuring mixing and heat transfer have also increased, as these are scale dependent. This has brought vessel operation to (partly severe) technical limits, especially when controlling harsh conditions, e.g., due to large heat releases. Accordingly, processing at a very large scale has resulted in taming of the chemistry involved in order to slow it down to a technically controllable level. Therefore, reaction paths that already turned out too aggressive at the laboratory scale are automatically excluded for later scale-up, which constitutes a common everyday confinement in exploiting chemical transformations. Organic chemists are barely conscious that even the small-scale laboratory protocols in their textbooks contain many slow, disciplined chemical reactions. Operations such as adding a reactant drop by drop in a large diluted solvent volume have become second nature, but are not intrinsic to the good engineering of chemical reactions. These are intrinsic to the chemical apparatus used in the past. In contrast, today's process intensification [3,12] and the new flow-chemistry reactors on the micro- and milli-scale [13,39] allow such limitations to be overcome, and thus, enable a complete, ab-initio type rethinking of the processes themselves. In this way, space-time yields and the productivity of the reactor can be increased by orders of magnitude and other dramatic performance step changes can be achieved. A hand-in-hand design of the reactors and process re-thinking is required to enable chemistry rather than subduing chemistry around the reactor [40]. This often leads to making use of process conditions far from conventional practice, under harsh environments, a procedure named here as Novel Process Windows. [source] | |||||||||||||||||||