bluuebunny/crossref_metadata_2025 huggingface dataset:
A mathematical model of distal nephron acidification: diuretic effects
Authors: Weinstein Alan M.
Published: August 2008

Through their action on the distal nephron (DN), diuretics may produce systemic acid-base disturbances: metabolic alkalosis with thiazides or loop diuretics and metabolic acidosis with amiloride. Enhanced acid excretion may be due to a local effect on the diuretic target cell (a shift of Na+ reabsorption from NaCl transport to Na+/H+ exchange), or an effect at a distance: namely, increases in luminal fluid flow or luminal Na+ concentration may enhance more distal proton secretion. Both local and distance effects are supported by micropuncture data. In the present work, mathematical models of the distal convoluted tubule (DCT)/connecting tubule (CNT) (Weinstein AM, Am J Physiol Renal Physiol 289: F721–F741, 2005), and cortical and medullary collecting ducts (CD) (Weinstein AM, Am J Physiol Renal Physiol 283: F1237–F1251, 2002) have been concatenated to yield a model of rat DN. Among the segments of this DN, the DCT-CNT is responsible for the major portion of distal acidification. Predictions from the model calculations include the following. 1) With increasing distal Na+ delivery, there is little change in net acid excretion, but a shift in acidification locus from shared DCT and CNT contributions, to DCT prominence. 2) Urinary acidification by thiazides is primarily local (in the DCT) via the shift in Na+ reabsorption from NaCl cotransport to entry via NHE2. Increased NaCl delivery to the CNT increases β-cell HCO3− secretion, and thus blunts urine acidification. 3) In contrast to conclusions drawn from the isolated CD model, inclusion of the CNT now reproduces the observed distal acidification defect found with ENaC block, so that this action of amiloride appears to be sufficient to produce “voltage-dependent” distal renal tubular acidosis. 4) The effect of furosemide to enhance distal urinary acidification is not reproduced by the model without major upregulation of CNT α-cell transport, perhaps as a result of increased luminal flow.
Evidence for increased postprandial distal nephron calcium delivery in hypercalciuric stone-forming patients
Authors: Worcester Elaine M. , Coe Fredric L. , Evan Andrew P. , Bergsland Kristin J. , Parks Joan H. , Willis Lynn R. , Clark Daniel L. , Gillen Daniel L.
Published: August 2008

A main mechanism of idiopathic hypercalciuria (IH) in calcium stone-forming patients (IHSF) is postprandial reduction of renal tubule calcium reabsorption that cannot be explained by selective reduction of serum parathyroid hormone levels; the nephron site(s) responsible are not as yet defined. Using fourteen 1-h measurements of the clearances of sodium, calcium, and endogenous lithium during a three-meal day in the University of Chicago General Clinical Research Center, we found reduced postprandial proximal tubule reabsorption of sodium and calcium in IHSF vs. normal subjects. The increased distal sodium delivery is matched by increased distal reabsorption so that urine sodium excretions do not differ, but distal calcium reabsorption does not increase enough to match increased calcium delivery, so hypercalciuria results. In fact, urine calcium excretion and overall renal fractional calcium reabsorption both are high in IHSF vs. normal when adjusted for distal calcium delivery, strongly suggesting a distal as well as proximal reduction of calcium reabsorption. The combination of reduced proximal tubule and distal nephron calcium reabsorption in IHSF is a new finding and indicates that IH involves a complex, presumably genetic, variation of nephron function. The increased calcium delivery into the later nephron may play a role in stone formation via deposition of papillary interstitial apatite plaque.
Predicting diffusive alveolar oxygen transfer from carbon monoxide-diffusing capacity in exercising foxhounds
Authors: Hsia Connie C. W. , Wagner Peter D. , Dane D. Merrill , Wagner Harrieth E. , Johnson Robert L.
Published: August 2008

Although lung diffusing capacity for carbon monoxide (DlCO) is a widely used test of diffusive O2 transfer, few studies have directly related DlCO to O2-diffusing capacity (DlO2); none has used the components of DlCO, i.e., conductance of alveolar membrane and capillary blood, to predict DlO2 from rest to exercise. To understand the relationship between DlCO and DlO2 at matched levels of cardiac output, we analyzed cumulative data from rest to heavy exercise in 43 adult dogs, with normal lungs or reduced lung capacity following lung resection, that were studied by two techniques. 1) A rebreathing (RB) technique was used to measure DlCO and pulmonary blood flow at two O2 tensions, independent of O2 exchange. DlCO was partitioned into CO-diffusing capacity of alveolar membrane and pulmonary capillary blood volume using the Roughton-Forster equation and converted into an equivalent DlO2, [DlO2(RB)]. 2) A multiple inert-gas elimination technique (MIGET) was used to measure ventilation-perfusion distributions, O2 and CO2 exchange under hypoxia, to derive DlO2 [DlO2(MIGET)] by the Lilienthal-Riley technique and Bohr integration. For direct comparisons, DlO2(RB) was interpolated to the cardiac output measured by the Fick principle corresponding to DlO2(MIGET). The DlO2-to-DlCO ratio averaged 1.61. Correlation between DlO2(RB) and DlO2(MIGET) was similar in normal and post-resection groups. Overall, DlO2(MIGET) = 0.975 DlO2(RB); mean difference between the two techniques was under 5% for both animal groups. We conclude that, despite various uncertainties inherent in these two disparate methods, the Roughton-Forster equation adequately predicts diffusive O2 transfer from rest to heavy exercise in canines with normal, as well as reduced, lung capacities.
Synaptic Homeostasis in a Zebrafish Glial Glycine Transporter Mutant
Authors: Mongeon Rebecca , Gleason Michelle R. , Masino Mark A. , Fetcho Joseph R. , Mandel Gail , Brehm Paul , Dallman Julia E.
Published: August 2008

Truncated escape responses characteristic of the zebrafish shocked mutant result from a defective glial glycine transporter (GlyT1). In homozygous GlyT1 mutants, irrigating brain ventricles with glycine-free solution rescues normal swimming. Conversely, elevating brain glycine levels restores motility defects. These experiments are consistent with previous studies that demonstrate regulation of global glycine levels in the CNS as a primary function of GlyT1. As GlyT1 mutants mature, their ability to mount an escape response naturally recovers. To understand the basis of this recovery, we assay synaptic transmission in primary spinal motor neurons by measuring stimulus-evoked postsynaptic potentials. At the peak of the motility defect, inhibitory synaptic potentials are both significantly larger and more prolonged indicating a prominent role for GlyT1 in shaping fast synaptic transmission. However, as GlyT1 mutants naturally regain their ability to swim, the amplitude of inhibitory potentials decreases to below wild-type levels. In parallel with diminishing synaptic potentials, the glycine concentration required to evoke the mutant motility defect increases 61-fold during behavioral recovery. Behavioral recovery is also mirrored by a reduction in the levels of both glycine receptor protein and transcript. These results suggest that increased CNS glycine tolerance and reduced glycine receptor expression in GlyT1 mutants reflect compensatory mechanisms for functional recovery from excess nervous system inhibition.
Dendrite Elongation and Dendritic Branching Are Affected Separately by Different Forms of Intrinsic Motoneuron Excitability
Authors: Duch Carsten , Vonhoff Fernando , Ryglewski Stefanie
Published: August 2008

Dendrites are the fundamental determinant of neuronal wiring. Consequently dendritic defects are associated with numerous neurological diseases and mental retardation. Neuronal activity can have profound effects on dendritic structure, but the mechanisms controlling distinct aspects of dendritic architecture are not fully understood. We use the Drosophila genetic model system to test the effects of altered intrinsic excitability on postembryonic dendritic architecture development. Targeted dominant negative knock-downs of potassium channel subunits allow for selectively increasing the intrinsic excitability of a selected subset of motoneurons, whereas targeted expression of a genetically modified noninactivating potassium channel decrease intrinsic excitability in vivo. Both manipulations cause significant dendritic overgrowth, but by different mechanisms. Increased excitability causes increased dendritic branch formation, whereas decreased excitability causes increased dendritic branch elongation. Therefore dendritic branching and branch elongation are controlled by separate mechanisms that can be addressed selectively in vivo by different manipulations of neuronal intrinsic excitability.
Peroxisome Proliferator‐Activated Receptors in the Modulation of the Immune/Inflammatory Response in Atherosclerosis
Authors: Fernandez Ana Z.
Published: August 2008

Inflammation has been recognized as an important hallmark of atherosclerosis. The pharmacological activation of
PPAR‐γ by the thiazolidinediones in diabetes, and of PPAR‐α by the fibrates in hyperlipidemia has been shown to help to reduce inflammatory markers in preclinical and clinical studies. PPARs are known to modulate immune pathways through at least three different mechanisms: by direct binding to PPRE of anti‐inflammatory cytokines genes; by transrepression of transcription factors like NF‐κB and AP‐1; or by corepression. The regulation of the inflammatory pathways by PPARs can be achieved on each one of the cells involved in the atherosclerotic process, that is, monocytes, macrophages, T cells, endothelial cells, and smooth muscle cells. Moreover, as each of these cellular components is interconnected with each other, PPAR activation in one cell type could affect the other ones. As activation of PPARs has clear ant‐inflammatory benefits, PPARs ligands should be considered as a new therapeutical approach to ameliorate the exacerbated immune response in atherosclerotic diseases.
MaizeGDB: The Maize Model Organism Database for Basic, Translational, and Applied Research
Authors: Lawrence Carolyn J. , Harper Lisa C. , Schaeffer Mary L. , Sen Taner Z. , Seigfried Trent E. , Campbell Darwin A.
Published: August 2008

In 2001 maize became the number one production crop in the world with the Food and Agriculture Organization of the United Nations reporting over 614 million tonnes produced. Its success is due to the high productivity per acre in tandem with a wide variety of commercial uses. Not only is maize an excellent source of food, feed, and fuel, but also its by-products are used in the production of various commercial products. Maize's unparalleled success in agriculture stems from basic research, the outcomes of which drive breeding and product development. In order for basic, translational, and applied researchers to benefit from others' investigations, newly generated data must be made freely and easily accessible. MaizeGDB is the maize research community's central repository for genetics and genomics information. The overall goals of MaizeGDB are to facilitate access to the outcomes of maize research by integrating new maize data into the database and to support the maize research community by coordinating group activities.
Preparation and Characterization of a Novel Chimeric Protein VEGI‐CTT in Escherichia coli
Authors: Cai Jiping , Wei Ruili , Cheng Jinwei
Published: August 2008

Vascular endothelial cell growth inhibitor (VEGI) is a recently identified antiangiogenic cytokine that belongs to the TNF superfamily, and could effectively inhibit endothelial cell proliferation and angiogenesis. Synthetic peptide CTT (CTTHWGFTLC) has been found to suppress invasion and migration of both tumor and endothelial cells by potent and selective inhibition of MMP‐2 and MMP‐9. To prepare chimeric protein VEGI‐CTT for more potent antitumor therapy, the recombinant expression vector pET‐VEGI‐CTT was constructed. This fusion protein was expressed in inclusion bodies in E. coli BL21 (DE3), and was refolded and purified by immobilized metal affinity chromatography using His‐tag. Purified VEGI‐CTT protein was characterized by proliferation assays of the endothelial cells and casein degradation assay in vitro. The results demonstrated that chimeric protein VEGI‐CTT had a potent activity of antiangiogenesis through inhibiting the proliferation of endothelial cells, and could effectively reduce the activity of MMP‐2 and MMP‐9. The preliminarily in vivo study demonstrated that chimeric protein VEGI‐CTT had more potent antitumor activity than VEGI and/or CTT peptide against CA46 human lymphoma xenografts in nude mice. Thus, these facts that are derived from the present study suggest that the chimeric protein VEGI‐CTT may be used for tumor therapy in the future.
“Brown” World Invertebrates Contradict “Green” World Biodiversity Theory
Authors: Patrick L. Brian , Fraser Lauchlan H. , Kershner Mark W.
Published: August 2008

Biodiversity-productivity theory predicts that ecosystems with increased productivity due to excessive limiting-nutrient loading will have decreased taxonomic diversity. In this 4-year study, we elevated productivity by adding NPK fertilizer to 20 m diameter plots in an old-field grassland to test the effects of anthropogenically mediated nutrient loading on plant and epigeal arthropod communities. While plants responded as predicted by the biodiversity-productivity theory, the epigeal arthropod community had highest species richness within the fertilized high-productivity treatments. We conclude that the contradictory response of the largely detrital-based epigeal community should alter conventional biodiversity-productivity theory and could affect terrestrial biodiversity conservation strategies.
Reliability Measurement without Limits
Authors: Reidsma Dennis , Carletta Jean
Published: August 2008

In computational linguistics, a reliability measurement of 0.8 on some statistic such as κ is widely thought to guarantee that hand-coded data is fit for purpose, with 0.67 to 0.8 tolerable, and lower values suspect. We demonstrate that the main use of such data, machine learning, can tolerate data with low reliability as long as any disagreement among human coders looks like random noise. When the disagreement introduces patterns, however, the machine learner can pick these up just like it picks up the real patterns in the data, making the performance figures look better than they really are. For the range of reliability measures that the field currently accepts, disagreement can appreciably inflate performance figures, and even a measure of 0.8 does not guarantee that what looks like good performance really is. Although this is a commonsense result, it has implications for how we work. At the very least, computational linguists should look for any patterns in the disagreement among coders and assess what impact they will have.
Do Large Sibships Really Lead to Lower Educational Attainment?
Authors: Jæger Mads Meier
Published: August 2008

The Resource Dilution Hypothesis and related theories predict that sibship size has a negative causal effect on educational attainment. However, because sibship size is likely to be endogenous to children's schooling in the sense that parents who have many children also have other socio-economic characteristics that lead to low educational attainment, it is difficult to determine if sibship size actually has a negative effect on educational attainment or whether the effect is spurious. This article deals with the endogeneity problem by using mothers' and fathers' inherited reproductive capacity as a `natural' experiment which affects sibship size but which, arguably, has no direct effect on children's educational attainment. I analyse data from the Wisconsin Longitudinal Study and use information on mothers' and fathers' sibship sizes and age at birth of first child as instruments for sibship size. After correcting for endogeneity, I find that sibship size has a negative causal effect on educational attainment.
A New Tester and Method for Measuring Fabric Stiffness and Drape
Authors: Sun M.N.
Published: August 2008

A new tester which uses a cross-shaped specimen to measure fabric drape and stiffness is proposed. The warp and the weft strips of the specimen are supported at the central part and bend under its own weight. The x and y coordinates of the hanging strips are measured so that the drape angles can be calculated. The way that the warp and the weft strips drape can be determined from one measurement. Using Peirce's formula, the conventional bending length and flexural rigidity can also be found. There is a strong correlation with measurements made using the Shirley stiffness tester and the Fabric Assurance by Simple Testing (FAST)-2 bending meter of FAST system.
Digital algorithms for prediction, differentiation and integration
Authors: Forsythe W.
Published: August 2008

The subject is dealt with in three parts, covered in three consecutive papers. Part I, published in the last issue, presented a method of calculating the coefficients required in digital algorithms for prediction (including interpolation and extrapolation), differentiation and integration, both on and off line. It provides the means of computing rapidly, by hand or with the aid of a small calculator, the coefficients required for algorithms of any order up to eight.

Parts II and III consider the errors inherent in using the algorithms derived in Part I and draw significant conclusions about the interaction of quantisation level, sampling frequency, order of the algorithm and the effects of these quantities on the accuracy of the results. Part II, which follows, deals with prediction and integration algorithms; Part III will deal with differentiation.
Design regions improve control system design
Authors: Hind E.C.
Published: August 2008

The use of a 'Design Region' instead of a 'Design Curve' is shown to provide the designer with a greater freedom of choice and results in the design of compensators which give faster transients than would be obtained by use of the design curve. For some systems the use of a design region will show that the chosen type of compensator will satisfy design requirements; whereas the use of a design curve would suggest that the chosen type of compensator would fail to satisfy the design requirements.
Calculation of the frequency responses of complex systems directly from the physical parameters
Authors: Goodall R.M.
Published: August 2008

The paper describes a novel technique by which frequency responses can be calculated. It works directly from the most basic physical data of the system, and, as such, even complex systems can be rapidly modelled and analysed. The method and its associated digital computation are inclined towards a control- engineering approach in which systems are represented by block diagram, but it will give the frequency- domain solution for any set of linear simultaneous differential equations. Examples are given for both forms of system representation to illustrate the practical use of the technique.
The transcutaneous measurement of common-carotid- artery blood flow using ultrasound
Authors: Lunt M.J. , Reuben J.R. , du Boulay E.P.G.
Published: August 2008

The noninvasive measurement of blood flow in an artery is important for physiological and pharmacological studies as well as in the diagnosis of disease. This paper describes the development of a noninvasive technique applicable to the carotid arteries in man, the validation of which provides a useful case study illustrating the general problems of calibrating a new noninvasive measurement. Blood flow in the human common carotid artery was calculated by combining measurements of blood velocity and arterial diameter, both of which were obtained from outside the body using ultrasound. Blood velocity was measured by recording the audio output from an ultrasonic Doppler velocimeter on magnetic tape and subsequently replaying through a zero crossing detector. Arterial diameter was measured using an ultrasonic pulse-echo A-scan instrument, modified to give two-dimensional images to aid identification of the artery. The accuracy of the measurements was studied in in-vitro and in-vivo investigations and an error in blood flow of ± 40% (± 2 sd), due mainly to error in diameter, was estimated.
Hammeringcontrol valves-diagnosis and solution of a stability problem
Authors: Gulland W.G. , Scott A.F.
Published: August 2008

Plug-type control valves are often installed in the flow-to-close close-on-air-failure configuration. In this configuration, it is possible for the valve to become unstable even though the actuator can generate sufficient force, in the steady state, to overcome the forces opposing it. For a valve that is not fitted with a positioner, instability will occur if the curve of equilibrium valve actuator pressure against lift is not monotonically increasing. If a positioner is fitted, instability will occur if the curve of equilibrium mass of air in the valve actuator against lift is not monotonically increasing. This paper presents the stability analysis for both cases. It outlines areas where instability may occur and suggests a variety of solutions.
A microprocessor-based automatic polynomial lineariser for constant-temperature anemometry systems
Authors: Marlowe S.
Published: August 2008

The paper describes a microprocessor-based lineariser module which automatically computes the coefficients, offset, and gain settings required for an integral wideband polynomial lineariser. An iterative technique is used whereby the aggregate residual-squared error between the normalised input data and the generated 4th-order polynomial converges to a minimum. Weighting factors are included to give a curve-fitting accuracy approximating to a constant percentage of reading.
Measu rement of reed vibration by means of a capacitance pick-up
Authors: Akay M. , Howgate P.
Published: August 2008

Reed vibration is an established method of analysing the dynamic mechanical properties of polymeric materials. The paper describes how capacitance change techniques can be used to measure reed vibration amplitude over a range of excitation frequencies and temperature and compares the results so obtained with those utilising more conventional methods.
Bounds on suboptimality in multilevel control of large systems
Authors: Permar K.D.
Published: August 2008

Closed-loop multilevel optimisation of large-scale systems, proposed by Siljak and Sundareshan ( 1977) and Sundareshan (1977), results in the suboptimal performance. This paper determines the closeness of such a suboptimal performance index to the optimal one without computing the optimal solution. It shows that the optimal performance index is bounded between the suboptimal performance index and a lower bound computed from the dual suboptimal system, so that the difference between the suboptimal and optimal performance indices will always be less than the difference between the suboptimal index and the lower bound.
Control analysis and desig n to improve instrument performance
Authors: Kaya A. , Verdouw J.H.
Published: August 2008

This work describes how the methods of control system analysis and design can be applied to meet performance requirements of an instrument. The basic methods and steps are: mathematical modelling of the instrument, analysis of performance and stability, design modifications to provide satisfactory performance, simulation by computer to verify the design, implementing the modification into the instrument, and verification of the proposed design by tests.
Adaptive control system for blood glucose regulation
Authors: Sano A. , Kondo K. , Kikuchi M. , Sakurai Y.
Published: August 2008

An adaptive scheme for blood glucose regulation is investigated via model-based approaches. The system has the capability of compensating in an on-line manner individual differences and parameter variations in the blood glucose regulation of diabetic subjects. The adaptive control algorithm consists of two types of controllers: a self-tuning regulator for adaptively performing model-matching to the reference model, and an error feedback controller to minimise the output error between the actual glucose level and the desired decreasing profile specified by physicians. It is shown through numerical simulations and animal experiments that in the presence of large parameter variations and disturbances due to food intake, the control algorithm can work efficiently compared to a conventional control algorithm with fixed parameters.
Comparison of methods for predicting head loss in turbulent pipe flow of non-Newtonian fluids
Authors: Heywood N.I. , Cheng D.C.-H.
Published: August 2008

The flow behaviour of a large variety of industrially important, non-Newtonian fluids can be described well using the Herschel-Bulkley model relating shear stress τ to shear rate γ by τ = τy + Kγn . The three parameters τy, K and n are determined experimentally using viscometers. Depending on the experimental spread of the τ, γ data, estimates of the parameters will have associated confidence intervals at any chosen level (eg 90%), and both estimates and confidence intervals will also depend on the regression method adopted; two methods are compared in this paper.

Th e prediction of head losses for laminar flow of the fluid in a pipeline requires a single equation derived from the Herschel-Bulkley model and presents no difficulty. For turbulent head loss prediction the situation is far more complicated. There are many different methods available, and there exist no guidelines regarding which method should be adopted. This paper demonstrates that predictions from these methods differ very widely, and that the uncertainty is compounded by that arising from estimating the τy , K and n parameters due to scatter in viscometric data. It is concluded that head-loss predictions should be made using as many prediction methods as possible, so that an engineering judgement may be made about which prediction is most appropriate for a given set of conditions.

Head-loss estimates for turbulent non-Newtonian flow can vary by ±50%. This contrasts starkly with the situation for turbulent Newtonian flow where head-loss estimates vary by no more than ± 4%. A lthough there are a dozen or more methods for Newtonian flow, the Moody equation is used most frequently and is quite adequate.
Parameterestimation in oxidation ditch modelling
Authors: Cook S.C.
Published: August 2008

The oxidation ditch is becoming increasingly popular in the United Kingdom for comparatively low-load domestic waste treatment situations. It has found widespread use for larger-scale waste treatment in Europe, especially in Holland. The original oxidation ditch concept is over 20 years old, and much research work has been carried out on the sludge characteristics and chemical processes. As a result of ever-increasing operational costs and more stringent effluent quality standards, the need has now arisen for a detailed study of the dynamics of the oxidation ditch process.

This paper forms part of an overall model identification study and intends to examine the possibility of on-line parameter estimation using the Extended Kalman Filter. The first part of the paper develops a non- linear, conceptual, dynamic model of dissolved oxygen (DO)/biological oxygen demand (BOD) interaction in the oxidation ditch. The model is employed together with an arbitrary set of parameters, in the synthesis of a series of noise-corrupted process data. The second part of the paper gives the Filter equations and the third part presents the results of the parameter estimation study.
Risk analysis in water quality management
Authors: Jowitt P.W.
Published: August 2008

The general theme of water quality management is to reduce a primary health risk to a residual risk and induced secondary risks. The paper considers UK residual health risks, sources of instability in water resource systems and the control of complex river basins.
An operational dynamic model of the final clarifier
Authors: Stehfest H.
Published: August 2008

The theory behind the dynamics of the final clarifier of the sludge plant is reviewed and the corresponding distributed parameter model is discussed. Since this full model is too complicated for on-line use, a simplified, lumped-parameter model is derived, which has the following three state variables : sludge blanket height and mean sludge concentrations above and below the sludge blanket height. It has been calibrated and validated with routine measurements from a real clarifier. The conclusion is drawn that the simplified model describes well the dynamics of the clarifier and, therefore, may be used for various real-time control purposes. For example, when combined with an adaptive parameter estimation algorithm, the model can be used to monitor the settling characteristics of the sludge without measuring sludge volume index.
Monte Carlo comparisons of estimators for pH non-linearity
Authors: Jacobs O.L.R. , Briggs M.S.
Published: August 2008

Monte Carlo methods are used to compare the performance of four non-linear estimators when applied to the logarithmic pH non-linearity. The estimators are: direct inversion of the non-linearity, Bayes'rule, extended Kalman filter, statistical linearisation. It is found that the unbiased optimal estimates of Bayes' rule are in many cases significantly better than the other estimates. It is concluded that the Bayes algorithm could be useful for practical purposes.
Computation of optimal inputs and trajectories in linear regulators with energy constraints by using Warner's a logorithm
Authors: Chung S.C. , Lee C.W.
Published: August 2008

In solving a linear regulator problem subjected to the integral type of energy constraint, the classical method requires that the proper magnitude of Lagrangian multiplier should be determined by a trial-and-error procedure. In this work, the Lagrangian multiplier is introduced as a state variable and a method to solve the isoperimetric problem is formulated by using Warner's algorithm. The new method essentially leads to evaluation of a two-point boundary value problem, requiring a far smaller number of differential equations to be solved than the Newton-Raphson-Kan torovich method and ensuring a faster convergence rate by adopting Warner's algorithm It also features the simultaneous computation of optimal inputs and trajectories. The optimal inputs and trajectories subjected to integral constraint are illustrated using a first-order linear dynamic system as an example.
Particle deflection using air jets
Authors: Neve R.S.
Published: August 2008

This paper is intended to provide a design guide for estimating the deflecting force available when aiming air jets at objects to be sorted or diverted, a fairly common requirement in some branches of engineering. Many results have been brought together to achieve this and, although results scatter is sometimes high because of flow unsteadiness, accuracy of force prediction is considered to be much better than any obvious alternative method.
Computer-aided control-system design with mini- and microcomputers
Authors: van den Bosch P.P.J. , van Geest W.J.M.
Published: August 2008

In this paper we discuss some aspects of the computer-aided design of control systems. We focus our attention on design and synthesis programs intended to run on mini- and microcomputers. In particular, a synthesis program, based on simulation and optimisation, is shown to have many capabilities, enabling the designer to solve real control problems. A designer-oriented hardware environment that allows readily available design facilities is discussed. Moreover, an example of a design program and a synthesis program is described, and our experiences with these programs in the education of students and in the research projects in our laboratory are reported.
A multipurpose microprocessor controller for hydraulic pumps
Authors: McGregor A.J. , Wilson J.N. , Lucas J.
Published: August 2008

Hydraulic pump/motor units have a wide range of commercial applications, each requiring a separate bolt-on hydraulic controller. This paper outlines the results of laboratory feasibility tests, aimed at replacing these hydraulic controllers with an electromechanical valve actuated by a universal microprocessor based controller. Since the majority of controller functions include a pressure override capability, the constant pressure override control (CPOC) function has been investigated in detail. The CPOC controller varies the pump flow rate to ensure that the hydraulic pipeline pressure remains constant despite variations in load. The microprocessor required an accurate measure of average line pressure. Preliminary tests showed that the axial pump superimposed large synchronous pressure ripples onto this average level. The results show that if careful signal conditioning is used to remove this ripple, a microprocessor based control unit can mimic the main control function of existing hydraulic controllers successfully. Design features required for a suitable prototype controller necessary for field trials are discussed.
Stability analysis of thyristor device control systems
Authors: Farahat H.M. , Ismail M.S. , Ashour M.A.
Published: August 2008

In this paper, a new method is presented for the study of the stability of systems controlled by thyristors. A nonlinear continuous data model (Lefevre, Bertrand & Ismail, 1973) is proposed for continuous and discontinuous operations. Generally, the system is represented by its transcendental equations at the consecutive instants tn and tn+1. Solving these equations, a module M is obtained which represents the system stability either locally or globally. A simple software program is presented which simplifies the necessary calculations to a high degree of accuracy.

The proposed method is used to study both first- and second-order syvtems. In particular a separately excited DC motor is considered.
Fuzzy feedforward and composite control
Authors: Stipanicev D. , Bozicevic J.
Published: August 2008

The concept of fuzzy feedforward and composite control of complex, ill-defined, non-deterministic processes is offered. Fuzzy relational model of process suitable for feedforward control is developed and, using this model, the algorithms of the fuzzy feedforward and composite controls are derived. The advantages of proposed control procedures are demonstrated by example of the invariant fuzzy control of an irrigation process.
Methods of quantitative validation for dynamic simulation models
Authors: Butterfield M.H. , Thomas P.J.
Published: August 2008

The paper presents a number of techniques developed at AEE Winfrith for assessing and improving dynamic simulation models. A method for selecting best-fit parameters for control engineering applications is discussed first. Then, in the main body of the report, the concept of model-distortion is developed, whereby a model's validity may be assessed quantitatively by the extent of time-variation or distortion needed in its nominally constant parameters to match a recorded transient perfectly.
CACSD software and man-machine interfaces of modern control environments
Authors: Rimvall M.
Published: August 2008

Recent work on Computer Aided Control Systems Design (CACSD) tools has put an increased emphasis on the design of good man-machine interfaces. This paper will survey the properties of an increasingly popular group of user-interfaces, the so-called matrix (control) environments, with comparisons to other approaches. In the first section, the progress of CACSD is compared to general advancements in computer-science. Thereafter, the unique characteristics of CACSD software as opposed to related application software are defined. In the third section, the use of interactive command languages as found in the matrix (control) environments will be evaluated. Finally, the advantages of integrated, all-encompassing packages versus special-purpose programs are discussed.
Education, training and manpower in metrology
Authors: Foxwell Richard
Published: August 2008

Most instrument manufacturers in the UK seem to know less than their US counterparts about the performance of their products ... There are several reasons. Instrument producing factories often lack standard equipment. Most producers have inadequate or no standards laboratory or environmental facilities ... Workmanship does not meet necessary standards because of poor selection and training of people ...
Transfer-function modelling of the Czochralski crystal growth process
Authors: Ghassempoory M. , Morgan C. , Hurle D.T.J. , Joyce G.C.
Published: August 2008

Control of the Czochralski crystal growth process is presently limited by the absence of an adequate transfer-function model of growth dynamics. Such a model would allow the development of more efficient control algorithms, and would lead to increased production of high-quality crystals. It would also help to give a greater understanding of the mechanisms of the growth process under a variety of ambient conditions. The approach used in this paper is to fit a high-order difference equation to the measured crystal weight signal, while modulating the heater power by a deterministic signal. Low-order modelling techniques are then used to extract the dominant transfer-function terms which represent the dynamic crystal growth characteristics.
Stabilising the controls of a boiler feedwater system
Authors: Thomas P.J. , Harrison T.A. , Hollywell P.D.
Published: August 2008

The paper discusses the methods used to gain a detailed understanding of the reasons for the intermittent oscillations observed on the steam drum levels of the UKAEA Prototype Fast Reactor (PFR). The paper goes on to describe how that knowledge was used to improve the control system design so as to eliminate the limit cycling modes and to give good control system performance over the full range of power operation.
A capacitance-based solids concentration transducer with high immunity to interference from the electrostatic charge generated in solids/air two-component flows
Authors: Huang S.M. , Xie C.G. , Stott A.L. , Green R.G. , Beck M.S.
Published: August 2008

Electrostatic charge generated in solids/air two-component flows can cause significant errors in solids-concentration measurement systems based on capacitance techniques, and, in the worst case, can overload or even damage the measuring circuits. A transformer ratio-arm bridge capacitance transducer, incorporating synchronous demodulation and a noise attenuating input amplifier, has been developed for this type of application. The transducer has been tested on several solids-flow plants. It shows a very high immunity to charge interference and it is capable of withstanding large magnitudes of electrostatic interference without being overloaded.
How SSM deals with complexity
Authors: Davies L.J.
Published: August 2008

Soft Systems Methodology (SSM) has been developed to deal with change made to improve problem situations. This methodological process is investigated in this paper and the investigation is related to the classification of complexity types given by Flood in this issue. The three types - i e, classical complexity, psychological complexity, and metaphysical complexity - are related to the three types of Weltanschauungen found in the process of SSM. The recognition of a complexity syndrome and the need to adopt a methodology as a way of handling that syndrome is noted. The paper concludes by arguing that the doubly systemic nature of SSM needs to be explicitly managed in order to utilise SSM fully as a way of handling complexity in problem situations.
Interpretive structural modelling: a methodology for structuring complex issues
Authors: Janes F.R.
Published: August 2008

This paper discusses the nature of Interpretive Structural Modelling (ISM) as methodology for dealing with complex issues. Aspects of managing complexity relating particularly to the use of ISM with a group of participants are explored. These include the interrelations between the issue, group and methodology, and between content, context, process and product. Languages for modelling structure are briefly examined, and ISM is presented as a computer-assisted modelling approach incorporating words, graphics and mathematics. The steps of using ISM in practice are considered in the context of group work. Each step is elaborated upon and important features discussed. The use of Nominal Group Technique as an idea-generation method which may be used in conjunction with ISM is outlined. An example of an application is given concerning the structuring of a set of objectives to produce an Intent Structure.
LQG adaptive ship autopilot
Authors: Katebi M.R. , Byrne J.C.
Published: August 2008

Existing adaptive autopilots do not usually have an energy saving capability. In addition, the control performance in rough seas often deteriorates so significantly that the autopilot is switched to a conventional PID controller. The first problem often arises from inaccurate approximations in the formulation of the energy cost criterion and the second from poor modelling of the sea wave disturbances. These problems are tackled here by formulating a new dynamic cost function system description and modelling approach. The LQG control strategy is then used to design an optimal controller to perform the course-keeping autopilot task. An advanced PID type controller is used for course-changing, the parameters of which are found from pole placement techniques.

An explicit self-tuning scheme is employed to provide adaptation in varying weather conditions. Simulation results are presented to demonstrate the performance of the proposed autopilot.
A digital approach to the disturbance-accommodation problem
Authors: Brandin B.A.
Published: August 2008

In this paper, the work of Burdess and Metcalfe (1985) on the active control of forced vibrations in mechanical systems is extended to the disturbance-accommodation problem. The topic is treated from the digital systems point of view and an a priori control action is included with an improved disturbance estimator.

The idea of a modified disturbance observer is proposed to show how an estimate of the excitation can be derived and is used to generate part of the control action. In order to allow a predefined state trajectory to be followed, an a priori control action is proposed. The resulting compensator does not require any knowledge of the disturbance model, the underlying concept consisting of estimating the disturbance instantaneously.

Experimental results are presented to show the performance of the method proposed with different types of dis turbances acting on the system considered.
Sexual Abuse and Its Relationship to Later Sexual Satisfaction, Marital Status, Religion, and Attitudes
Authors: FINKELHOR DAVID , HOTALING GERALD T. , LEWIS I. A. , SMITH CHRISTINE
Published: August 2008

In a large, nationally representative survey of 2,626 adult Americans, men and women who reported a history of childhood sexual abuse involving penetration were also more likely to report a disrupted marriage, dissatisfaction in their sexual relationship, and a tendency to be a religious nonpractitioner. Victims of abuse were also more likely to have read or talked about the problem recently and tended to see it as a more common occurrence than nonvictims. These findings are generally consistent with other studies on the long-term impact of abuse and add to the sense of this as a social problem with important social and psychological ramifications.
Violence Against Lesbian and Gay Male Youths
Authors: HUNTER JOYCE
Published: August 2008

This article documents the incidence of violent assaults toward lesbian and gay male youths and those youths' suicidal behavior. Data were obtained by reviewing charts for the first 500 youths seeking services in 1988 at the Hetrick-Martin Institute, a community-based agency serving lesbian and gay male adolescents in New York City. The adolescents, who ranged in age from 14 to 21 years, were predominantly minority (35% Black, 46% Latino) and typically were referred by peers, media, schools, and emergency shelters. Of the youths, 41% in the sample reported having suffered violence from families, peers, or strangers; 46% of that violence was gay-related. These reports of violence occurred in conjunction with a high rate of suicide attempts: 41% of the girls and 34% of the boys who experienced violent assaults reported having attempted suicide. These alarming rates indicate the need for more systematic monitoring of violence toward and suicidal behavior among lesbian and gay male youths.
Thinking About Hate-Motivated Crimes
Authors: BERK RICHARD A.
Published: August 2008

This article discusses a variety of problems related to the general conceptualization of hate crimes. Beginning with the question of what attributes differentiate a hate-motivated crime from other types of crime, the article discusses problems associated with discerning time trends, the possible role of the AIDS epidemic in hate-motivated crimes, and the import of particular risk factors. The article identifies the symbolic and actuarial status of crime victims as the defining feature of hate crimes, and points out that such crimes may be both expressive and instrumental. A preliminary list of eight variables is proposed that might be related to hate-motivated crimes. In a discussion of how time trends might be identified in hate-motivated crimes, the article briefly describes some procedures by which data might be analyzed. In the discussion of risk factors, the article discusses how minority groups targeted by hate-motivated crimes might be sampled, and how data collected from those groups might be analyzed. In conclusion, a parallel is drawn between current knowledge on hate-motivated crimes and the status of knowledge about family violence 15 years ago.
Child Maltreatment Among Asian and Pacific Islander Refugees and Immigrants
Authors: IMA KENJI , HOHM CHARLES F.
Published: August 2008

The literature that focuses on cultural aspects of child maltreatment among Asian and Pacific Islander (API) immigrant groups is sparse. The literature on child maltreatment among API refugees is virtually nonexistent. This article attempts to address this void and reports the findings of a study on 158 cases of child maltreatment that were reported to and handled by the Union of Pan Asian Communities in San Diego, California. A utilization of both quantitative and qualitative strategies identified five possible parameters that may explain the patterns of reported child maltreatment in an Asian and Pacific Islander population: (a) home country traumas, especially notable among refugees; (b) differences in child-rearing practices; (c) the relative visibility to welfare professionals and other publicly employed professionals; (d) the relative continuity of social support systems brought from country of origin; and (e) the relative ability to cope with cultural conflicts brought on by being newcomers.
Early Onset and Deviant Sexuality in Child Molesters
Authors: MARSHALL W. L. , BARBAREE H. E. , ECCLES A.
Published: August 2008

One hundred twenty-nine outpatient child molesters (91 nonfamilial and 38 father/daughter offenders) were assessed and interviewed regarding various aspects of their deviant sexuality. Of our total sample, 29% reported having deviant fantasies prior to age 20, and this was most pronounced (41.1%) among those who molested the sons of other people. Fourteen percent of the nonfamilial offenders against boys, 11.8% of the nonfamilial offenders against girls, and 7.9% of the incest offenders had one or more paraphilia additional to their index offense; only three of the total sample reported more than two additional paraphilias. These data differ from those reported earlier by Abel and his colleagues (1985) and by Freund (1990). The results are discussed in terms of these discrepancies.