bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct measurement of human sympathetic nerve conduction velocity
Authors: Kondo Masahide , Iwase Satoshi , Mano Tadaaki , Kuzuhara Shigeki
Published: December 2003

We evaluated a method for direct measurement of conduction velocity (CV) in sympathetic nerves in humans using a double‐recording method of skin sympathetic nerve activity (SSNA) by microneurography. SSNA in the tibial nerve was recorded simultaneously at proximal and distal sites in the popliteal fossa (short‐distance study) or at the popliteal fossa and ankle (long‐distance study). In both studies, CVs were determined by dividing the interelectrode distance on the skin by the difference in conduction time between the rising‐phases (rising‐phase analysis) or peaks of the integrated bursts (peak‐to‐peak analysis). The measurement using long distance and peak‐to‐peak analysis had the highest accuracy; it is an orthodromic conduction measurement, is unrelated to eliciting stimulus, has high temporal resolution, and is not affected by the effector organ conditions. The average CV of resting SSNA was 0.93 ± 0.09 m/s. Muscle Nerve 29: 128–133, 2004
Threshold electrotonus in chronic inflammatory demyelinating polyneuropathy: Correlation with clinical profiles
Authors: Sung Jia‐Ying , Kuwabara Satoshi , Kaji Ryuji , Ogawara Kazue , Mori Masahiro , Kanai Kazuaki , Nodera Hiroyuki , Hattori Takamichi , Bostock Hugh
Published: December 2003

Chronic inflammatory demyelinating polyneuropathy (CIDP) is characterized by multifocal demyelination along the course of the nerves, and involvement of the intermediate segments may correlate with more severe demyelination associated with breakdown of the blood–nerve barrier. Threshold electrotonus was used to study whether altered membrane properties of the median nerve at the wrist (intermediate segment) are associated with clinical profiles in 21 CIDP patients. In response to hyperpolarizing conditioning stimuli, the threshold changes were significantly greater for CIDP patients than for normal controls (n = 49). The pattern was similar to that of 11 patients with Charcot‐Marie‐Tooth disease type 1a, who exhibited abnormally high thresholds to hyperpolarizing currents. The abnormal threshold electrotonus was present in 48% of the CIDP patients and was associated with longer disease duration, more severe disability, poorer response to immune treatments, and slower nerve conduction velocities. Threshold electrotonus can be used to detect demyelination at the tested sites and may provide new information about pathophysiology and distribution patterns of demyelination in CIDP. Muscle Nerve 29: 28–37, 2004
Effect of load during electrical stimulation training in spinal cord injury
Authors: Crameri Regina M. , Cooper Philip , Sinclair Peter J. , Bryant Grace , Weston Adele
Published: December 2003

Electrical stimulation training is known to alter skeletal muscle characteristics after a spinal cord injury, but the effect of load on optimizing the training protocol has not been fully investigated. This study investigated two electrical‐stimulation training regimes with different loads on intramuscular parameters of the paralyzed lower limbs. Six paraplegic individuals with a spinal cord injury underwent electrical stimulation training (45 min daily for 3 days per week for 10 weeks). One leg was trained statically with load, and the contralateral leg was trained dynamically with minimal load. Isometric force assessed with 35‐HZ stimuli increased significantly in both legs from baseline, with the static‐trained leg also being significantly higher than the dynamic‐trained leg. The vastus lateralis muscle of the statically trained leg showed a significant increase in type I fibers, fiber cross‐sectional area, capillary‐to‐fiber ratio, and citrate synthase activity when compared to both baseline and the dynamically trained leg. Relative oxygenation of the vastus lateralis muscle as determined by near infrared spectroscopy was also significantly greater after static training. This study indicates that the load that is applied to paralyzed muscle during an electrical stimulation training program is an important factor in determining the amount of muscle adaptation that can be achieved. Muscle Nerve 29: 104–111, 2004
Clinical efficacy of tolterodine with or without a simplified pelvic floor exercise regimen
Authors: Millard R.J.
Published: December 2003

Objectives

To investigate whether the combination of tolterodine plus (Tp) a simple pelvic floor muscle exercise (PFME) program would provide improved treatment benefits compared with tolterodine alone (Ta) in patients with symptoms of overactive bladder (OAB).

Methods

After a 1–2 week run‐in period, 480 patients with symptoms of urinary frequency (≥8 micturitions/24 hr), urgency, and urge incontinence (≥1 episode/24 hr), were randomized to receive tolterodine 2 mg bid with or without a simple PFME program for 24 weeks in this multinational study. Treatment efficacy was assessed by comparing the change from baseline in 3‐day micturition diary recordings.

Results

After 24 weeks' treatment, in the Ta group the urgency episodes reduced from mean of 4.1 to 1.5 (83% reduction) while in the Tp group the urgency episodes reduced from 4.2 to 2.1 (78.7% reduction). Mean incontinence episodes per day decreased from 3.21 (standard deviation (SD) 3.4) to 0.95 (SD 1.9) in Ta group and from 3.44 (SD 3.4) to 1.25 (SD 2.7) in the Tp group. Similarly, the number of micturition/24 hr were significantly reduced, from 12.78 to 9.20 (27.3% reduction) in the Ta group and from 11.87 to 9.29 (23% reduction) in the Tp group. There was an improvement in the patients' perception of urinary symptoms in 85.9% of patients on Ta and 81.7% patients on Tp PFME. There were no statistically significant differences between the groups with regard to any of the outcome parameters.

Conclusions

Tolterodine therapy for 24 weeks results in significant improvement in urgency, frequency, and incontinence, however, no additional benefit was demonstrated for a simple PFME program. Neurourol. Urodynam. 23:48–53, 2004. © 2003 Wiley‐Liss, Inc.
Morphological description, biometry and phylogenetic position of the skull of Ngawi 1 (east Java, Indonesia)
Authors: Widianto H. , Zeitoun V.
Published: December 2003

The skull of Ngawi 1 was discovered fortuitously in August 1987 on the left bank of the river Solo near the village of Selopuro (east Java, Indonesia). It is a complete, well preserved and strongly mineralized calvaria. The present article provides a complete description of this specimen. Its general morphological pattern is first considered; then, each anatomical complex is considered individually, allowing us a comparison with other Asian Pleistocene fossils. A broad biometric framework and a morphological database are both used to perform a cladistic analysis aiming at a more accurate determination of the phylogenetic position of this skull among ‘Homo erectus’. This work confirms that Ngawi 1 is closer to the Ngandong‐Sambungmachan series than to the Trinil‐Sangiran series. Following the hypothesis of a young age (40,000 years) for the former series, the question is whether this skull belongs to a subspecies of Homo sapiens, as suggested by early authors, or to a separate species, Homo soloensis. An evolutionary process is suggested here, where Ngawi 1 belongs to a particular human group that is geographically and chronologically restricted. This Indonesian human group may have evolved at the same time as the Neandertals in Europe, an area which represented the westernmost end of Eurasia when Indonesia was its easternmost end. The question is raised as to whether insularity, that isolated this taxon, is comparable to the cool climate which isolated the Neandertals for thousands of years. If so, the Ngawi‐Ngandong‐Sambungmachan series might have evolved from an older, local Homo erectus population. On the other hand, due to local, drastic volcano‐tectonic events that occurred 71,000 years ago, and catastrophic events 780,000 years ago, the first inhabitants of Java may have disappeared. According to this alternative hypothesis, Ngawi 1 could be one of the new invaders from continental Asia. Copyright © 2003 John Wiley & Sons, Ltd.
Personality, cognition, and university students' examination performance
Authors: Phillips Pru , Abraham Charles , Bond Rod
Published: December 2003

A prospective study explored the relationship between personality traits (as defined by the five factor model), type of motivation (as defined by self‐determination theory), and goal‐specific cognitions (including those specified by the theory of planned behaviour) as antecedents of degree performance amongst undergraduate students. A sample of 125 students completed a questionnaire two to three months before their final examinations. Structural equation modelling was used to explore relationships. Intention and perceived behavioural control explained 32% of the variance in final degree marks, with intention being the strongest predictor. Controlling for theory of planned behaviour variables, anticipated regret, good‐student identity, controlled extrinsic motivation, Conscientiousness, and Openness had direct significant effects on intention. In total, 65% of the variance in intention was explained. The resultant model illustrates how personality traits may affect examination performance by means of mediators such as intention, anticipated regret, student identity, and autonomous intrinsic motivation. Copyright © 2003 John Wiley & Sons, Ltd.
Can intensive three‐day programmes improve nurses' communication skills in cancer care?
Authors: Wilkinson S. M. , Leliopoulou C. , Gambles M. , Roberts A.
Published: December 2003

Effective communication is widely regarded as a crucial component of patient care that can determine patient satisfaction, compliance and recovery. The plethora of communication skills training programmes available to health professionals is also a testament to the importance of this element of care. However a review of studies evaluating the effectiveness of such training programmes concluded that little behavioural change in health professionals' communication skills was evident. This paper reports the findings of a programme offered to cancer/palliative care nurses (n=108) via eight condensed three‐day workshops at various UK venues. Behavioural change was assessed through evaluation of audiotaped nursing assessments made pre‐ and six weeks post‐course, scored along nine previously identified key communication areas. Mean overall scores rose by 6 points ( p<0.001) to 20 (out of 27) with statistically significant improvements on eight of the nine individual areas. Improvements in subjective levels of confidence in the areas of communication found difficult pre‐course were observed immediately post‐course ( p<0.001) and were still evident six weeks later. Similar improvements immediately post‐course for teaching communication skills to colleagues ( p<0.001) were further improved six weeks post‐course for seven of the eight areas assessed. These results suggest that three‐day training courses can lead to clinically relevant behavioural change and improvements in perceived confidence in communication and dissemination of skills. Copyright © 2003 John Wiley & Sons, Ltd.
A three‐year study of chaplains' professional activities at Memorial Sloan‐Kettering Cancer Center in New York city
Authors: Flannelly Kevin J. , Weaver Andrew J. , Handzo George F.
Published: December 2003

The pastoral‐care interventions of chaplains at Memorial Sloan‐Kettering Cancer Center were documented during two‐week periods in each of three years. The study describes the pattern of referrals to and from chaplains and the kinds of interventions performed during the chaplains' contacts with patients and their families and friends. Nearly a fifth of all chaplain interventions were the result of referrals. The vast majority of staff referrals to chaplains came from nurses, with the frequency and proportion of referrals from nurses significantly increasing over time. More than a third of all chaplain contacts were with friends and family without the patient present, and over 40% of referrals to chaplains were for the friends and family of patients. Pastoral visits were significantly shorter when patients were not present. In particular, pastoral‐care interventions were found to differ according to the patient's religion and the circumstances of the chaplain's visit to the patient (i.e. patient status). Visit duration also varied by patient status, with pre‐operative visits being significantly shorter than post‐operative or treatment visits. Copyright © 2003 John Wiley & Sons, Ltd.
Prostate cancer patients' support and psychological care needs: Survey from a non‐surgical oncology clinic
Authors: Lintz Kathleen , Moynihan Clare , Steginga Suzanne , Norman Andy , Eeles Ros , Huddart Robert , Dearnaley David , Watson Maggie
Published: December 2003

While there are numerous uncertainties surrounding prostate cancer's detection and treatment, more research focusing on the psychological needs of prostate patients is required. This study investigated the support and psychological care needs of men with prostate cancer. Patients were approached during urological oncology clinics and asked to complete the: Support Care Needs Survey (SCNS), Support Care Preferences Questionnaire, EORTC QLQ‐C30 (Version 3) Measure plus Prostate Module, and the Hospital Anxiety and Depression Scale (HADS). Of the 249 patients meeting study entry criteria, there was an 89% response rate resulting in a cohort of 210 patients. The data showed that significant unmet need exists across a number of domains in the areas of psychological and health system/information. The more commonly reported needs were ‘fears about cancer spreading (44%),’ ‘concerns about the worries of those close to you (43%),’ and ‘changes in sexual feelings (41%).’ Half of all patients reported some need in the domain of sexuality, especially men younger than 65 years. Needs were being well met in the domain of patient care and support. A significant number of patients reported having used or desiring support services, such as information about their illness, brochures about services and benefits for patients with cancer (55%), a series of talks by staff members about aspects of prostate cancer (44%), and one‐on‐one counselling (48%). Quality of life (QoL) was most negatively impacted in those who: were ⩽65 years old, had been diagnosed within one year, or had metastatic disease. Men ⩽65 had decreased social functioning, greater pain, increased sleep disturbance, and were more likely to be uncomfortable about being sexually intimate. Patients recently diagnosed had increased fatigue, more frequent urination, greater disturbance of sleep, and were more likely to have hot flushes. Those with advanced disease scored lower on 12 out of 15 QoL categories. PSA level had no effect on QoL or anxiety/depression scores. Men with advanced disease had greater levels of depression and those ⩽65 years old were more likely to be anxious. Although most men with prostate cancer seem to function quite well, a substantial minority report areas of unmet need that may be targets for improving care. Copyright © 2003 John Wiley & Sons, Ltd.
Course of distress and quality of life in testicular cancer patients before, during, and after chemotherapy: Results of a pilot study
Authors: Trask Peter C. , Paterson Amber G. , Fardig Judith , Smith David C.
Published: December 2003

Testicular cancer is the most common cancer in white males between the ages of 15 and 45 years. Treatment may include the administration of chemotherapy which has been associated with changes in emotional distress, quality of life, and symptom distress in other cancers. The current study was designed to evaluate the course of these constructs in a sample of testicular cancer patients undergoing chemotherapy. Patients completed measures of emotional distress and quality of life prior to, during, and after chemotherapy, with symptom distress measured during chemotherapy. Thirty percent of patients reported moderate to high levels of distress at pre‐treatment baseline that was associated with worse quality of life. Initial anxiety and distress decreased and stayed low through chemotherapy and post‐treatment follow‐up. There were no significant changes in fatigue, nausea or change in appearance during chemotherapy. The results suggest that some patients evidence pre‐treatment anxiety and distress that appears to be primarily anticipatory, decreases over the course of chemotherapy, and occurs in the context of improved quality of life and reduced symptom severity. Deleterious changes in emotional distress, quality of life, and symptom distress seen in other cancer populations were not apparent in our sample of testicular cancer patients. Copyright © 2003 John Wiley & Sons, Ltd.
Perception of breast cancer risk and surveillance behaviours of women with family history of breast cancer: A brief report on a Spanish cohort
Authors: Gil Francisco , Méndez Ignacio , Sirgo Agustina , Llort Gemma , Blanco Ignacio , Cortés‐Funes Hernán
Published: December 2003

Women with a family history of breast cancer (FHBC) are at increased risk for developing this disease. In this study, we have investigated the differences between two groups of women; those with family history of breast cancer (N=42) and women at population risk (N=42) in a Spanish cohort. Questionnaires assessed distress, perception of breast cancer risk, screening behaviours, coping skills, personality and quality of life. Neither group received genetic counselling before or after this study. Women with FHBC overestimated their risk of developing breast cancer. They report a subjective risk of developing breast cancer of 50%, with their actual risk, using the risk tables elaborated by Claus et al. (Cancer 1994, 73: 643), being only 15% (p<0.05). Discriminant function analysis revealed the patients' information about breast cancer, worries about breast cancer, perception of risk based on family history, perception of lifetime risk of breast cancer and quality of life were the five variables that distinguished between both groups. Only 34% of women in the FHBC group performed monthly breast self‐examination, 24% (10 subjects) had never attended previously for clinical breast examination and 45% (19 subjects) had never undergone a mammogram. This group of women had a significantly lower level of general satisfaction (p<0.05), an indicator of Quality of Life. The results support the need for developing psychological intervention for women with family history of breast cancer in order to increase adherence to surveillance behaviours, reduce distress, improve quality of life, and assure the earliest detection of breast cancer. Copyright © 2003 John Wiley & Sons, Ltd.
Receiving a screen‐detected diagnosis of cancer: The experience of participants in the UK flexible sigmoidoscopy trial
Authors: Miles Anne , Wardle Jane , Atkin Wendy
Published: December 2003

The experience of receiving a screen‐detected diagnosis of colorectal cancer was explored using open‐ended interviews. Twenty four people who had been diagnosed with cancer at flexible sigmoidoscopy screening were interviewed at their homes over the telephone. Thematic analysis of the transcripts showed that the experience of gaining a diagnosis of cancer through screening was characterised by a lack of prior expectation that cancer would be detected and feelings of shock. This was largely because of the absence of symptoms and current feelings of well‐being. Some interviewees expressed feelings of relief and gratitude at having cancer diagnosed at an early enough stage that ‘something could be done about it’. The experience of receiving a screen‐detected diagnosis could be summarised as one of ‘moderated shock’ whereby the shock of the unexpected diagnosis was often moderated by the news that the cancer had been caught early.

Whilst these screen‐detected cancers were diagnosed relatively rapidly, a significant number of interviewees had a period in which they were effectively ‘symptomatic’ (e.g. knew they had an adenoma but did not know whether it was malignant or benign). However, they did not use this period to prepare themselves for a possible cancer diagnosis. Raising awareness of the adenoma–carcinoma sequence may help reduce the shock of a screen‐detected diagnosis. However, any interventions aimed at reducing the distress of a screen‐detected cancer would need to consider the overall benefit to screening attenders, most of whom will have benign polyps detected. Copyright © 2003 John Wiley & Sons, Ltd.
The CARES‐SF used for prospective assessment of health‐related quality of life after stem cell transplantation
Authors: Hjermstad Marianne J. , Evensen Stein A. , Kvaløy Stein O. , Loge Jon H. , Fayers Peter M. , Kaasa Stein
Published: December 2003

Objective: By employing the Cancer Rehabilitation and Evaluation System short form (CARES‐SF) prospectively we wanted to focus on the rehabilitation needs after high‐dose chemotherapy (HDC) and stem cell transplantation, in order to identify problems that should be addressed by health‐care professionals during the course of disease and treatment.

Methods: The CARES‐SF was administered before and at 2, 6 and 12 months post‐transplant to 130 cancer patients treated with HDC and allogeneic (SCT) or autologous stem cell transplantation (ASCT). Physical function scale scores were compared with the corresponding scale of the EORTC QLQ‐C30.

Results: The SCT group reported significantly better physical function than the ASCT group before transplant on both the CARES‐SF (p<0.0001) and the EORTC QLQ‐C30 (p<0.01). Almost identical mean CARES‐SF scores across groups (SCT: 0.7–1.4, ASCT: 0.8–1.3) were found at the subsequent assessments, consistent with the QLQ‐C30 data. Correlations between CARES‐SF and QLQ‐C30 Physical Function Scales ranged from 0.45 to 0.65.

The SCT group had better psychosocial subscale scores (mean 0.4 and 0.5 versus ASCT: 0.7 and 0.8, p < 0.01) at the 6 and 12‐month assessments, as well as better satisfaction on the marital subscale ( p=0.01) 6 months post‐transplant.

Few patients requested specific help: 19% at baseline with ‘fear of the cancer progressing’ and 9% with ‘reduction in physical energy’ after 6 and 12 months.

Conclusion: The CARES‐SF detected differences across groups of patients as well as within‐patient changes over time. The possibility for patients to express their need for professional assistance renders the CARES‐SF appropriate after SCT/ASCT. The sexual, marital and medical interaction subscales in particular address specific issues of relevance for follow‐up care, compared with more traditional questionnaires assessing health related quality of life (HRQOL). Copyright © 2003 John Wiley & Sons, Ltd.
Terrain analyses and surface velocity measurements of the Hiorthfjellet rock glacier, Svalbard
Authors: Ødegård Rune S. , Isaksen Ketil , Eiken Trond , Ludvig Sollid Johan
Published: December 2003

The morphology and dynamics of the Hiorthfjellet rock glacier, Svalbard, are investigated based on analyses of (1) a digital terrain model and (2) surface velocity measurements during the time period 1994 to 2002. The Hiorthfjellet rock glacier is particularly suited for the interpretation of rock‐glacier dynamics from surface morphology since the surface is smooth with homogenous rock size minimally influenced by debris flows. Surface velocity measurements give good evidence of surface strain rate on the order of 4×10−5 year−1 to 8×10−5 year−1. The upper and frontal zones of the rock glacier have extending flow, the central zone compressive flow. There are small deviations between the gradient of the surface velocity vector and the surface gradient of the rock glacier. Observed surface velocity vectors are within the range of 9.5 cm year−1 to 10.8 cm year−1. The DTM analyses clearly show a small‐scale ridge‐and‐furrow surface, most likely attributed to active‐layer processes. Copyright © 2003 John Wiley & Sons, Ltd.
Snow cover and soil moisture controls on solifluction in an area of seasonal frost, eastern Alps
Authors: Jaesche Philipp , Veit Heinz , Huwe Bernd
Published: December 2003

This paper presents multi‐year measurements of solifluction, frost heave and the concurrent thermal and hydrological regimes at two solifluction lobes with seasonal frost in the eastern Alps, Austria. The monitoring system included a new solifluction meter and time‐domain‐reflectometry (TDR) probes to measure the unfrozen water content of the soil. Three phases of ground thermal and hydrological conditions were identified, each with distinct consequences for soil movements. Rapid frost heave occurred during initial ground freezing in early winter. Freezing intensity and maximum frost penetration are strongly influenced by snow drifting in that period. Another period of marked heaving during spring snowmelt is attributed to meltwater infiltration into the frozen ground. Solifluction commenced at high water contents with the beginning of thaw settlement and was enhanced by daily fluctuations of snowmelt and lateral influx of meltwater. Slow movements continued, or even started, after complete thawing of the ground as long as lateral runoff from snow patches upslope elevated soil water contents. Copyright © 2003 John Wiley & Sons, Ltd.
Theoretical Studies on PNMFIW by AM1 and PM3 Methods
Authors: Yukai Wu , Yuxiang Ou , Zhiguo Liu , Boren Chen
Published: December 2003

AM1 and PM3 semi‐empirical methods were used to conduct theoretical studies on possible polymorphs of pentanitromonoformylhexaazaisowurtzitane (PNMFIW), and a close link between PNMFIW and Hexanitrohexaazaisowurtzitane (HNIW), especially in sensitivity, is shown. The optimized geometries of possible polymorphs of PNMFIW are similar to those of HNIW. PNMFIW in ε‐HNIW prepared from tetraacetyldiformylhexaazaisowurtzitane is predicted to have a D‐form. The average NN bond lengths of PNMFIW computed by AM1 and PM3 methods are shorter than those of HNIW. The differences in energy and thermochemistry values between PNMFIW and HNIW are insignificant except molecular energies 255.75 kJ⋅mol−1 for D‐form PNMFIW and 460.36 kJ⋅mol−1 for ε‐HNIW. Based on a Mulliken population analysis of the NN bonds, the impact sensitivities of A‐, B‐, C‐ and D‐forms of PNMFIW are estimated to be lower than those of the corresponding polymorphs of HNIW. Taking into account all NN bond lengths and overall molecule size, the shock sensitivities of all forms PNMFIW are predicted to be almost the same, and lower than those of HNIW.
Combustion Model for Pyrophoric Metal Foils
Authors: Wilharm Caroline K.
Published: December 2003

A model for the combustion of pyrophoric metal foils has been developed. The diffusive mass transport, heat transport, and chemical reactions of porous iron foils have been described. The temperature and radiated energy of these materials has been predicted as a function of the physical characteristics of the material (porosity, pore size, specific surface area) for different atmospheric conditions (temperatures and oxygen concentrations varied with altitude and wind velocity).
Feedback stabilization via designed planar centre manifold
Authors: Dong Yali , Cheng Daizhan , Qin Huashu
Published: December 2003

This paper addresses the problem of local state feedback stabilization of a class of nonlinear systems, which have planar centre manifold. A new technique for designing centre manifold has been developed. Using this approach, a sufficient condition for stabilization of a class of nonlinear system is obtained. The approach has been specified for two particular critical cases: ‘zero centre’ with zero eigenvalue of multiplicity 2 and ‘oscillatory centre’ with a pair of pure imaginary eigenvalues. The control law, which stabilizes the overall system, is also presented. Some examples are presented to indicate how the present theorem may be implemented. Copyright © 2003 John Wiley & Sons, Ltd.
Nonlocal stabilization via delayed relay control rejecting uncertainty in a time delay
Authors: Fridman L. , Strygin V. , Polyakov A.
Published: December 2003

Sufficient conditions for a robust relay delayed non‐local stabilization of linear systems are found, which relate the upper bound of an uncertainty in a time delay and the maximum of the real part of system spectrum. Algorithm of delayed relay control gain adaptation for non‐local stabilization is suggested. The proposed algorithm suppresses bounded uncertainties in the time delay: once this relay delayed control law for the upper bound of uncertainty in the time delay for given system is designed, we ensure non‐local stabilization for all values of the time delay less than the upper bound even in the case of a variable delay. Copyright © 2003 John Wiley & Sons, Ltd.
Time‐steppers and ‘coarse’ control of distributed microscopic processes
Authors: Armaou Antonios , I. Siettos Constantinos , G. Kevrekidis Ioannis
Published: December 2003

We present an equation‐free multiscale computational framework for the design of ‘coarse’ controllers for complex spatially distributed processes described by microscopic/mesoscopic evolution rules. We illustrate this framework by designing discrete‐time, coarse linear controllers for a Lattice–Boltzmann (LB) scheme modelling a reaction–diffusion process (a kinetic‐theory based realization of the FitzHugh–Nagumo equation dynamics in one spatial dimension). Short ‘bursts’ of appropriately initialized simulation of the LB model are used to extract the stationary states (stable and unstable) and to estimate the information required to design the coarse controller (e.g. the action of the coarse slow Jacobian of the process). Copyright © 2004 John Wiley & Sons, Ltd.
Reduction and identification methods for Markovian control systems, with application to thin film deposition
Authors: Gallivan Martha A. , Murray Richard M.
Published: December 2003

Dynamic models of nanometer‐scale phenomena often require an explicit consideration of interactions among a large number of atoms or molecules. The corresponding mathematical representation may thus be high dimensional, nonlinear, and stochastic, incompatible with tools in nonlinear control theory that are designed for low‐dimensional deterministic equations. We consider here a general class of probabilistic systems that are linear in the state, but whose input enters as a function multiplying the state vector. Model reduction is accomplished by grouping probabilities that evolve together, and truncating states that are unlikely to be accessed. An error bound for this reduction is also derived. A system identification approach that exploits the inherent linearity is then developed, which generates all coefficients in either a full or reduced model. These concepts are then extended to extremely high‐dimensional systems, in which kinetic Monte Carlo (KMC) simulations provide the input–output data. This work was motivated by our interest in thin film deposition. We demonstrate the approaches developed in the paper on a KMC simulation of surface evolution during film growth, and use the reduced model to compute optimal temperature profiles that minimize surface roughness. Copyright © 2004 John Wiley & Sons, Ltd.
Distributed nonlinear control of diffusion–reaction processes
Authors: Dubljevic Stevan , Christofides Panagiotis D. , Kevrekidis Ioannis G.
Published: December 2003

In this work, we focus on distributed control of quasi‐linear parabolic partial differential equations (PDEs) and address the problem of enforcing a prespecified spatio‐temporal behaviour in the closed‐loop system using nonlinear feedback control and a sufficiently large number of actuators and sensors. Under the assumption that the desired spatio‐temporal behaviour is described by a ‘target parabolic PDE’, we use a combination of Galerkin's method and nonlinear control techniques to design nonlinear state and static output feedback controllers to address this problem. We use examples of diffusion–reaction processes to demonstrate the formulation of the control problem and the effectiveness of our systematic approach to creating prespecified spatio‐temporal behaviour. Using these illustrative examples, we demonstrate that both (a) a sufficiently large number of actuators/sensors, and (b) nonlinear control laws are needed to achieve this goal. Copyright © 2004 John Wiley & Sons, Ltd.
Dissipative systems: from physics to robust nonlinear control
Authors: A. Alonso Antonio , V. Fernandez Carlos , R. Banga Julio
Published: December 2003

In this paper, we explore connections between the underlying physics of dissipative systems and nonlinear robust control. In particular, we concentrate on the problem of stabilizing stationary solutions of nonlinear dissipative systems with states distributed in space. Dissipative systems are equipped with an entropy function which we employ to relate dissipation with the Hamilton–Jacobi–Bellman equation. This relation allows us to establish formal links between the dynamic properties of dissipative systems, passivity and optimal stabilizing control, as it is understood in systems theory. Robustness issues in controller design, are also discussed in the context of front or pulse spatial pattern stabilization. Copyright © 2004 John Wiley & Sons, Ltd.
Compensation of spatiotemporally varying disturbances in nonlinear transport processes via actuator scheduling
Authors: A. Demetriou Michael , Kazantzis Nikolaos
Published: December 2003

A new systematic framework is developed that allows the integration of a comprehensive actuator scheduling policy and a robust feedback controller synthesis method to be realized for the compensation of spatiotemporally varying disturbances for nonlinear transport processes modelled by parabolic partial differential equations (PDEs). It is assumed that the process of interest has either multiple actuators and the desirable arrangement is to activate only one during a given time‐interval, or there is a single actuator capable of moving ata prioriselected positions within the spatial domain. Local feedback controller synthesis methods based on linear matrix inequality (LMI) techniques are developed and realized through the linearization of a nonlinear finite‐dimensional approximation of the original distributed parameter system obtained via a Galerkin discretization scheme. Furthermore, additional conditions are derived that ensure robustness with respect to a certain class of physically meaningful spatiotemporally varying disturbances. The value of an appropriately selected quadratic performance functional is then explicitly calculated by solving an actuator location‐parameterized family of Lyapunov matrix equations, and subsequently optimized with respect to the set of admissible actuator locations. Finally, in order to illustrate the proposed method a typical nonlinear transport process modelled through Burgers' equation is considered, and its performance is evaluated through simulation studies. Copyright © 2004 John Wiley & Sons, Ltd.
Hybrid predictive control of nonlinear systems: method and applications to chemical processes
Authors: El‐Farra Nael H. , Mhaskar Prashant , Christofides Panagiotis D.
Published: December 2003

A hybrid control structure that unites bounded control with model predictive control (MPC) is proposed for the constrained stabilization of nonlinear systems. The structure consists of: (1) a finite‐horizon model predictive controller, which can be linear or nonlinear, and with or without stability constraints, (2) a family of bounded nonlinear controllers for which the regions of constrained closed‐loop stability are explicitly characterized and (3) a high‐level supervisor that orchestrates switching between MPC and the bounded controllers. The central idea is to embed the implementation of MPC within the stability regions of the bounded controllers and employ these controllers as fall‐back in the event that MPC is unable to achieve closed‐loop stability (due, for example, to infeasibility of a given initial condition and/or horizon length, or due to computational difficulties in solving the nonlinear optimization). Switching laws, that monitor the closed‐loop state evolution under MPC, are derived to orchestrate the transitions in a way that guarantees asymptotic closed‐loop stability for all initial conditions within the union of the stability regions of the bounded controllers. The proposed hybrid control scheme is shown to provide a paradigm for the safe implementation of predictive control algorithms to nonlinear systems, with guaranteed stability regions. The efficacy of the proposed approach is demonstrated through applications to chemical reactor and crystallization process examples. Copyright © 2004 John Wiley & Sons, Ltd.
Distributed, asynchronous and hybrid simulation of process networks using recording controllers
Authors: Garcia‐Osorio Vianey , Ydstie B. Erik
Published: December 2003

In this paper we propose a novel approach for distributed process simulation which does not need synchronization by a central coordinator, nor does it require an iterative procedure to ensure stability and boundedness of the simulation error. Instead we rely on inherent passivity properties of process networks and recording‐controller (RC) devices to develop a hybrid representation of the underlying continuous dynamics. The RCs are added to the original process system where there are interconnections between different computational agents. RCs accumulate the simulation error between communication intervals, perform error checking, control information flow and update the interconnection variables at discrete intervals so that the errors remain bounded. The distributed simulation framework is used to develop two different simulation strategies: In one case we use distributed simulation with fixed time horizons. In the other case we use update on demand and adapt the time horizons so that the error satisfies pre‐specified tolerances. Copyright © 2004 John Wiley & Sons, Ltd.
Comments on ‘Sufficient conditions for the synthesis of H∞ fixed‐order controllers’
Authors: Feng Zhengping , Allen Robert
Published: December 2003

This note points out that both theorems in Mattei (Int. J. Robust Nonlinear Control 2000; 10: 1237–1248) are incorrect for a general plant model. Additionally, it presents the corrections of them. Copyright © 2004 John Wiley & Sons, Ltd.
Reply to comments on ‘Sufficient conditions for the synthesis of H∞ fixed‐order controllers’
Authors: Mattei Massimiliano
Published: December 2003

In this brief note Theorems 1 and 2 (Int. J. Robust Nonlinear Control 2000; 10:1237–1242) are discussed in the light of the observations raised in Feng and Allen (Int. J. Robust Nonlinear Control). A simple correction to the proof of these theorems allows to keep the hypothesis on the possible rank deficiency of the system matrices B and Cy. Copyright © 2004 John Wiley & Sons, Ltd.
Reliable memory feedback design for a class of non‐linear time‐delay systems
Authors: Yue Dong , Lam James
Published: December 2003

This paper is concerned with the robust controller design of uncertain time‐delay systems with unknown nonlinearity and actuators failures. New methods for designing stabilizing controllers and reliable controllers are proposed. The stability criteria of the closed‐loop system, which are dependent on the magnitudes of the delay and its derivative, are derived in the form of linear matrix inequalities. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed results, as well as the reduction of conservativeness when compared with existing ones. Copyright © 2004 John Wiley & Sons, Ltd.
Absolute stability of nonlinear systems with disc and norm‐bounded perturbations
Authors: Impram Serkan T. , Munro Neil
Published: December 2003

Absolute stability of uncertain nonlinear systems is studied using the celebrated Popov and circle criteria. Uncertainty is assumed to exist in terms of disc and norm‐bounded perturbations in the linear plant. The use of circular arithmetic is proposed as an accurate but computationally more demanding alternative to the already existing approach based on strict positive realness conditions which is easier and faster to implement but gives, in general, conservative results. Numerical examples are given in order to illustrate the salient features of the mathematical developments. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐destructive analysis of ultrathin dielectric films
Authors: Champaneria R. , Mack P. , White R. , Wolstenholme J.
Published: December 2003

Using angle‐resolved x‐ray photoelectron spectroscopy (ARXPS) it is possible to determine thickness, composition and depth distribution information for ultrathin samples in the region of ∼5–10 nm. With ARXPS determining both quantitative elemental information and chemical state information, it provides chemical state profiles from surface and buried layers non‐destructively.

This paper illustrates how ARXPS data can provide measurements of overlayer thickness and interface layer thickness for high‐k dielectric layers on silicon. Elemental and chemical state depth distribution information is also provided in the form of reconstructed concentration profiles. Further examples are provided where ARXPS has been used to study the influence of surface pretreatment of the silicon substrate prior to deposition of hafnium oxide. It will be shown that the pretreatment determines whether a silicon oxide or silicate is formed. Copyright © 2003 John Wiley & Sons, Ltd.
Adsorption behaviour of C2H5SCH3 on Ag(111) and Ag(UFP) surfaces
Authors: Sardar S. A. , Syed J. A. , Yagi S. , Tanaka K.
Published: December 2003

The adsorption behaviour of ethylmethylsulfide (C2H5SCH3) on Ag(111) and ultrafine particle Ag, Ag(UFP), surfaces has been studied by near‐edge x‐ray absorption fine structure and x‐ray photoelectron spectroscopy techniques. It is found that C2H5SCH3 adsorbs molecularly on the Ag(111) surface but dissociates on Ag(UFP). On the Ag(111) surface the molecule shows polarization dependence. The S–C2H5 and S–CH3 bonds are found to be tilted at angles of 31 ± 5° and 21 ± 5° from the surface, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Fatty acid‐modified microgels: transmission electron microscopy study
Authors: Kraft Mary L. , Robinson Scott J. , Moore Jeffrey S.
Published: December 2003

In order to examine modified microgels with transmission electron microscopy (TEM), we developed a sample preparation protocol that employs colloidal gold to label the sample/resin interface. This approach avoids the introduction of additional components to the prepolymer mixture, possibly altering the material properties of the resulting hydrogel. Examination of thinly sectioned hydrogels embedded in resin by TEM revealed that the gold particles clearly outlined the hydrogel/resin interface, facilitating characterization of a fatty acid coating on the hydrogel. Copyright © 2003 John Wiley & Sons, Ltd.
Increased regulatory activity of the calcineurin/NFAT pathway in human heart failure
Authors: Diedrichs Holger , Chi Mei , Boelck Birgit , Mehlhorm Uwe , Schwinger Robert H.G.
Published: December 2003

Background:

Cardiac hypertrophy may initiate progression to a compromised cardiac function. While the clinical consequences of hypertrophy are well understood, only little is known about the underlying molecular pathways. As reported from animal experiments, the Ca2+‐calmodulin activated phosphatase calcineurin and its downstream transcriptional effector NFAT have been implicated as transducers of the hypertrophic response.

Methods and results:

To study whether the calcineurin pathway is activated in human heart failure, we investigated samples of human left ventricular myocardium from patients with dilated (idiopathic) cardiomyopathy (DCM, NYHA IV, n=8) in comparison with non‐failing controls (NF, n=8). We not only analyzed the pathway by measuring the calcineurin activity, but also by determination of the protein expression of the calcineurin B subunit and additional key markers of the calcineurin signaling cascade (NFAT‐3, GATA‐4). Calcineurin enzymatic activity was increased by 80% in human dilated cardiomyopathy compared with non‐failing human hearts (135.424±11.69 and 83.484±1.81 nmol Pi/min per μl). This was in line with increased protein expression of calcineurin B in DCM (71.18+9.11 vs. 46.41±11.23 densitometric units (DU)/μg protein). In order to verify the activated calcineurin pathway as described in animal models, we compared the protein expression of NFAT‐3 in homogenates within nuclear extracts. In nuclear extracts the protein level of NFAT‐3 was increased in dilated cardiomyopathy compared with non‐failing myocardium (104.01±8.85 vs. 71.47±8.79 DU/μg protein). In contrast, in homogenates the expression of NFAT‐3 was higher in the non‐failing tissue indicating subcellular redistribution (19.56±3.36 vs. 25.84±3.16 DU/μg protein). The protein expression of GATA‐4 was increased in DCM (43.14±2.89 vs. 29.87±2.17 DU/μg protein).

Conclusions:

In human heart failure (DCM) the calcineurin signaling pathway is activated not only by an increased activity of calcineurin and expression of GATA‐4, but also by the shift from dephosphorylated NFAT‐3 to the nucleus indicating subcellular redistribution and regulatory activation.
Effect of tissue harmonic imaging and contrast upon between observer and test–retest reproducibility of left ventricular ejection fraction measurement in patients with heart failure
Authors: Whalley Gillian A. , Gamble Greg D. , Walsh Helen J. , Wright Susan P. , Agewall Stefan , Sharpe Norman , Doughty Robert N.
Published: December 2003

Aims:

To investigate the effects of tissue harmonic imaging (THI) and contrast chamber opacification (LVO) upon measurement variability and reproducibility of echocardiographic left ventricular (LV) volume and ejection fraction (EF) measurements in patients with heart failure (HF).

Background:

Echocardiography is often used in HF patients to determine LV volumes and EF. However, current echo methods are variable and may not be applicable for repeat testing in individual patients. THI and LVO have both been shown to improve endocardial visualisation, but it remains to be determined whether this results in better measurement reproducibility.

Methods:

Thirty‐one HF patients and 30 control subjects underwent echocardiography on two separate days. LV volumes were measured under four different imaging conditions: fundamental, THI, LVO and LVO with ECG–triggered Power Doppler. Chamber opacification, pulmonary transit time (PTT), endocardial enhancement, reproducibility and bias were assessed.

Results:

Chamber opacification was inferior and the PTT longer in the HF patients. PTT was related to LV volumes, EF, jugular venous pressure and mitral filling pattern. THI improved endocardial visualisation, and although LVO improved endocardial visualisation in the controls, it offered no benefit over THI in the HF patients. LV volumes and EF were different for each method and THI was the least variable method for repeat measurements.

Conclusions:

THI improved endocardial visualisation and was the least variable of the techniques. LVO offered no further advantage in patients with HF and thus cannot be routinely advocated and since LV volumes and EF were different for each, these methods are neither comparable nor interchangeable for follow‐up assessments.