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Aims.The aim of this study was to identify the risk correlates for coexisting common mental disorders (CMDs) in the chronic care population in South Africa, with the view to identifying particularly vulnerable patient populations.Methods.The sample comprised 2549 chronic care patients enrolled in the baseline and endline rounds of a facility detection survey conducted by the Programme for Improving Mental Health Care in three large facilities in the Dr Kenneth Kaunda district in the North West province of South Africa. Participants were screened for depression using the Patient Health Questionnaire (PHQ9) and for alcohol misuse using the Alcohol Use Disorders Identification Test (AUDIT). Data were analysed according to the number of morbidities, disorder type (physical or mental) and demographic variables. Multimorbidity was defined as the presence of two or more disorders (physical and/or mental).Results.Just over one-third of the sample reported two or more physical conditions. Women were more at risk of being depressed than were men, with men more at risk of alcohol misuse. Those who were employed were at lower risk of having coexisting CMDs, while being younger, HIV positive, and food deprived were all found to be associated with higher risk for having coexisting CMDs.Conclusion.In the face of the large treatment gap for CMDs in South Africa, and the role that coexisting CMDs can play in exacerbating the burden of chronic physical diseases, mental health screening and treatment interventions should target HIV-positive, younger patients living in circumstances where there is household food insecurity.

For 3 years, a digital demolition derby pitted teams of cryptographers against each other in a fierce battle of different schemes for protecting information from prying eyes. Now, there is [...]

AimsSuicidal behaviour is an under-reported and hidden cause of death in most low- and middle-income countries (LMIC) due to lack of national systematic reporting for cause-specific mortality, high levels of stigma and religious or cultural sanctions. The lack of information on non-fatal suicidal behaviour (ideation, plans and attempts) in LMIC is a major barrier to design and implementation of prevention strategies. This study aims to determine the prevalence of non-fatal suicidal behaviour within community- and health facility-based populations in LMIC.MethodsTwelve-month prevalence of suicidal ideation, plans and attempts were established through community samples (n= 6689) and primary care attendees (n= 6470) from districts in Ethiopia, Uganda, South Africa, India and Nepal using the Composite International Diagnostic Interview suicidality module. Participants were also screened for depression and alcohol use disorder.ResultsWe found that one out of ten persons (10.3%) presenting at primary care facilities reported suicidal ideation within the past year, and 1 out of 45 (2.2%) reported attempting suicide in the same period. The range of suicidal ideation was 3.5–11.1% in community samples and 5.0–14.8% in health facility samples. A higher proportion of facility attendees reported suicidal ideation than community residents (10.3 and 8.1%, respectively). Adults in the South African facilities were most likely to endorse suicidal ideation (14.8%), planning (9.5%) and attempts (7.4%). Risk profiles associated with suicidal behaviour (i.e. being female, younger age, current mental disorders and lower educational and economic status) were highly consistent across countries.ConclusionThe high prevalence of suicidal ideation in primary care points towards important opportunities to implement suicide risk reduction initiatives. Evidence-supported strategies including screening and treatment of depression in primary care can be implemented through the World Health Organization's mental health Global Action Programme suicide prevention and depression treatment guidelines. Suicidal ideation and behaviours in the community sample will require detection strategies to identify at risks persons not presenting to health facilities.

Efforts to support the scale-up of integrated mental health care in low- and middle-income countries (LMICs) need to focus on building human resource capacity in health system strengthening, as well as in the direct provision of mental health care. In a companion editorial, we describe a range of capacity-building activities that are being implemented by a multi-country research consortium (Emerald: Emerging mental health systems in low- and middle-income countries) for (1) service users and caregivers, (2) service planners and policy-makers and (3) researchers in six LMICs (Ethiopia, India, Nepal, Nigeria, South Africa and Uganda). In this paper, we focus on the methodology being used to evaluate the impact of capacity-building in these three target groups. We first review the evidence base for approaches to evaluation of capacity-building, highlighting the gaps in this area. We then describe the adaptation of best practice for the Emerald capacity-building evaluation. The resulting mixed method evaluation framework was tailored to each target group and to each country context. We identified a need to expand the evidence base on indicators of successful capacity-building across the different target groups. To address this, we developed an evaluation plan to measure the adequacy and usefulness of quantitative capacity-building indicators when compared with qualitative evaluation. We argue that evaluation needs to be an integral part of capacity-building activities and that expertise needs to be built in methods of evaluation. The Emerald evaluation provides a potential model for capacity-building evaluation across key stakeholder groups and promises to extend understanding of useful indicators of success.

There is increasing international recognition of the need to build capacity to strengthen mental health systems. This is a fundamental goal of the ‘Emerging mental health systems in low- and middle-income countries’ (Emerald) programme, which is being implemented in six low- and middle-income countries (LMICs) (Ethiopia, India, Nepal, Nigeria, South Africa, Uganda). This paper discusses Emerald's capacity-building approaches and outputs for three target groups in mental health system strengthening: (1) mental health service users and caregivers, (2) service planners and policy-makers, and (3) mental health researchers. When planning the capacity-building activities, the approach taken included a capabilities/skills matrix, needs assessments, a situational analysis, systematic reviews, qualitative interviews and stakeholder meetings, as well as the application of previous theory, evidence and experience. Each of the Emerald LMIC partners was found to have strengths in aspects of mental health system strengthening, which were complementary across the consortium. Furthermore, despite similarities across the countries, capacity-building interventions needed to be tailored to suit the specific needs of individual countries. The capacity-building outputs include three publicly and freely available short courses/workshops in mental health system strengthening for each of the target groups, 27 Masters-level modules (also open access), nine Emerald-linked PhD students, two MSc studentships, mentoring of post-doctoral/mid-level researchers, and ongoing collaboration and dialogue with the three groups. The approach taken by Emerald can provide a potential model for the development of capacity-building activities across the three target groups in LMICs.

Aims.In low-income countries, care for people with severe mental disorders (SMDs) who manage to access treatment is usually emergency-based, intermittent or narrowly biomedical. The aim of this study was to inform development of a scalable district-level mental health care plan to meet the long-term care needs of people with SMD in rural Ethiopia.Methods.The present study was carried out as formative work for the Programme for Improving Mental health CarEwhich seeks to develop, implement and evaluate a district level model of integrating mental health care into primary care. Six focus group discussions and 25 in-depth interviews were conducted with service planners, primary care providers, traditional and religious healers, mental health service users, caregivers and community representatives. Framework analysis was used, with findings mapped onto the domains of the Innovative Care for Chronic Conditions (ICCC) framework.Results.Three main themes were identified. (1) Focused on ‘Restoring the person's life’, including the need for interventions to address basic needs for food, shelter and livelihoods, as well as spiritual recovery and reintegration into society. All respondents considered this to be important, but service users gave particular emphasis to this aspect of care. (2) Engaging with families, addressed the essential role of families, their need for practical and emotional support, and the importance of equipping families to provide a therapeutic environment. (3) Delivering collaborative, long-term care, focused on enhancing accessibility to biomedical mental health care, utilising community-based health workers and volunteers as an untapped resource to support adherence and engagement with services, learning from experience of service models for chronic communicable diseases (HIV and tuberculosis) and integrating the role of traditional and religious healers alongside biomedical care. Biomedical approaches were more strongly endorsed by health workers, with traditional healers, religious leaders and service users more inclined to see medication as but one component of care. The salience of poverty to service planning was cross-cutting.Conclusions.Stakeholders prioritised interventions to meet basic needs for survival and endorsed a multi-faceted approach to promoting recovery from SMD, including social recovery. However, sole reliance on this over-stretched community to mobilise the necessary resources may not be feasible. An adapted form of the ICCC framework appeared highly applicable to planning an acceptable, feasible and sustainable model of care.

There is limited evidence on the acceptability, feasibility and cost-effectiveness of task-sharing interventions to narrow the treatment gap for mental disorders in sub-Saharan Africa. The purpose of this article is to describe the rationale, aims and methods of the Africa Focus on Intervention Research for Mental health (AFFIRM) collaborative research hub. AFFIRM is investigating strategies for narrowing the treatment gap for mental disorders in sub-Saharan Africa in four areas. First, it is assessing the feasibility, acceptability and cost-effectiveness of task-sharing interventions by conducting randomised controlled trials in Ethiopia and South Africa. The AFFIRM Task-sharing for the Care of Severe mental disorders (TaSCS) trial in Ethiopia aims to determine the acceptability, affordability, effectiveness and sustainability of mental health care for people with severe mental disorder delivered by trained and supervised non-specialist, primary health care workers compared with an existing psychiatric nurse-led service. The AFFIRM trial in South Africa aims to determine the cost-effectiveness of a task-sharing counselling intervention for maternal depression, delivered by non-specialist community health workers, and to examine factors influencing the implementation of the intervention and future scale up. Second, AFFIRM is building individual and institutional capacity for intervention research in sub-Saharan Africa by providing fellowship and mentorship programmes for candidates in Ethiopia, Ghana, Malawi, Uganda and Zimbabwe. Each year five Fellowships are awarded (one to each country) to attend the MPhil in Public Mental Health, a joint postgraduate programme at the University of Cape Town and Stellenbosch University. AFFIRM also offers short courses in intervention research, and supports PhD students attached to the trials in Ethiopia and South Africa. Third, AFFIRM is collaborating with other regional National Institute of Mental Health funded hubs in Latin America, sub-Saharan Africa and south Asia, by designing and executing shared research projects related to task-sharing and narrowing the treatment gap. Finally, it is establishing a network of collaboration between researchers, non-governmental organisations and government agencies that facilitates the translation of research knowledge into policy and practice. This article describes the developmental process of this multi-site approach, and provides a narrative of challenges and opportunities that have arisen during the early phases. Crucial to the long-term sustainability of this work is the nurturing and sustaining of partnerships between African mental health researchers, policy makers, practitioners and international collaborators.

This paper reports on a pilot study of the development and evaluation (using outcome and process measures) of a manualised participatory risk reduction programme, aimed at reducing high-risk sexual behaviour amongst tertiary level learners, called 'Sex and Risk' (S&R), at the University of Durban-Westville 1 in South Africa. The programme was grounded in a focused ethnographic study of the risk behaviours and life context of tertiary level learners at this institution, as well as informed by literature on successful behavioural risk reduction programmes on Western and African populations. Significantly, the S&R programme was shown to facilitate greater awareness in males of how social influences inform high-risk sexual behaviour. This greater awareness did not, however, translate into greater self-efficacy in relation to negotiating safer sexual relationships for either males or females and was attributed to the dominant social norms, which promote and sustain gender inequity that places the sexual health of young women and men at risk. Given that the S&R programme operates largely at the level of the individual, although it does address the subjective aspects of social influences on behaviour, these findings highlight the need for proximal situation-centred interventions, which promote more egalitarian social norms in sexual relationships, to accompany such curriculum interventions at tertiary institutions.

Comparative genomic hybridization (CGH) was used to screen 83 lung adenocarcinomas of 60 patients for chromosomal imbalances. The most common alteration was DNA overrepresentation on chromosome 1q, with a peak incidence at 1q22-q23 in 73% of the primary tumours, followed by DNA overrepresentation on chromosomes 8q and 20q, and deletions on chromosomes 3p, 4q, 6q, 9p, 9q, and 13q, in at least 60%. The generation of a difference histogram of metastasizing versus non-metastasizing tumours and a case-by-case histogram for the comparison of 23 paired samples of primary tumours and corresponding metastases suggested that deletions on chromosomes 3p12-p14, 3p22-p24, 4p13-15.1, 4q21-qter, 6q21-qter, 8p, 10q, 14q21, 17p12-p13, 20p12, and 21q, and overrepresentations on chromosomes 1q21-q25, 7q11.2, 9q34, 11q12-q13, 14q11-q13, and 17q25 are associated with the metastatic phenotype. In contrast, losses on chromosome 19 and gains on 3p, 4q, 5p, and 6q were preferentially found in non-metastasizng tumours. The analysis of the paired samples revealed considerable chromosomal instability, but indicated a clonal relationship in each case. The primary tumours often showed additional deletions, suggesting that loss of function mutations are critical in the initial phase of tumour dissemination, whereas the metastases preferentially acquired DNA gains, probably modulating the metastatic phenotype. The primary data from this study (ratio profiles, clinicopathological parameters, histograms) are also available at http://amba.charite.de/cgh. Copyright © 2001 John Wiley & Sons, Ltd.

In this paper, we show that the same panel of three microsatellite markers is useful for the detection of alterations in the DNA of tumor cells and plasma from patients diagnosed with SCLC and NSCLC. In 31 of the SCLC patients, we detected a microsatellite alteration(s) or LOH in at least one locus. In the group of patients diagnosed with NSCLC, a microsatellite alteration or LOH was detected in at least one locus in 33 of the patients. In all but 2 patients, the identical alteration observed in the DNA from tumor cells was also detected in the DNA isolated from blood plasma. This work confirms the results described by other groups and it extends the diagnostic possibilities of finding tumor cell-specific DNA alterations also in the DNA freely circulating in plasma and serum of patients with cancer.

Abstract:  The uncertainty of the Kjeldahl method for determination of nitrogen in insulin was evaluated according the procedure described in the Guide to the Expression of Uncertainty in Measurement. The relative standard uncertainty of the method was found to be 0.19%, compared to the relative intermediate precision experimentally found to be 0.085%. The uncertainty components were organized in Tables, which allowed an easy overview and evaluation. The largest contribution to the uncertainty came from volumetric equipment. Systematic uncertainty budgets such as the design presented here facilitate the uncertainty evaluation process and makes it easier to compare uncertainty evaluations performed by different analysts.

This paper considers a problem of disturbance attenuation for a pinned–pinned flexible beam. The beam is modelled as a distributed parameter system and a procedure is developed to solve the corresponding disturbance attenuation problem for such a distributed parameter system. A controller is designed in a way that minimizes the effect of disturbances over the entire beam. The controller design approach of this paper is applicable to a large number of active noise and vibration control problems.

The paper presents an output feedback optimal guaranteed cost control result for a new class of uncertain linear systems. The cost function considered is a quadratic cost function defined over a finite time interval. The new uncertainty class introduced in the paper involves structured uncertainties which are required to satisfy a certain averaged integral quadratic constraint. The introduction of this new structured uncertainty description enables us to solve a previously unsolved problem of optimal guaranteed cost control via output feedback for an uncertain system with structured uncertainties. The solution is obtained by solving a pair of parametrized Riccati differential equations of the game type.

Eight men were studied during graded (47, 77 and 100% of maximal oxygen uptake) and prolonged (76%) exhaustive treadmill running. Plasma catecholamine levels increased progressively with intensity and duration of exercise. Serum concentrations of thyroid-stimulating hormone (TSH) increased with increasing work loads and were 107 (58–243)% (P<0.001) above resting values after maximal work. Thyroxine, triiodothyronine and luteinizing hormone in serum never changed significantly. While a small increase in testosterone concentrations (13 [1–24]%) after maximal exercise probably could be explained by changes in plasma volume, a definite increase (31 [14–56]%) occurred after 40 min of prolonged exercise. During continued exercise testosterone concentrations then gradually declined. Testicular stimulation by the increased catecholamine concentrations possibly contributed to the rise in testosterone concentrations, but no evidence was found for a direct catecholamine induced increase in the activity of the thyroid gland. The exercise induced increase in TSH levels possibly explains the increased thyroid hormone secretion rate, which previously has been found in individuals participating in physical training programs.

The snailfish family Liparididae was well represented in bottom trawl hauls (205–370 m) from the Spitsbergen area, with Liparis gibbus being the dominant species. Careproctus reinhardti was less numerous. The present paper is based on 539 specimens of C. gibbus (size range 6–25cm) and 120 specimens of L. reinhardti (size range 5–26 cm). Both species showed a rather similar size and age distribution. The stomach contents reveal that both snailfish species feed both benthically and pelagically. Crustaceans, especially amphipods and decapods, were the most common prey items. With increasing size of the fish, the decapod Pandalus borealis becomes more important, particularly for L. gibbus. Juvenile Liparis (1.3–4.3 cm in length) were found pelagically (35–200 m), and their diet mainly consisted of copepods and young hyperiid amphipods.

C.R. Rao: Linear Statistical Inference its Application. 2. Ed. John Wiley & sons, New York, London, Sydney, Toronto 1973, XX, 625 S.O. J. Dunn, V.A. Clark: Applied Statistics: Analysis of Variance and Regression John Wiley & Sons, Inc., New York, London, Sydney, Toronto 1974, XII, 387 S., $10.25.S.N. Roy, R. Gnanadesikan, J.N. Srivastava: Analysis and Design of Certain Quantitative Multipurpose Experiments (with an appendix on computer algorithms and programs by E.B Fowlkes, II and E.T. Lee Pergamon Press, Oxford-New York-Toronto-Sydney-Braunschweig 1971, VIII, 304 S., $ 3.25; $ 8.50)E. Schindowski, O. schürz: Statistiche Qualitätskontrolle (Kontrollkarten und Stichprobepläne) 5. Auflage, VEB Verlag Technik, Berlin 1972, 636 S., 237 Abb., 83 Tab., 28,- M

The paper presents a new approach to model validation and fault diagnosis problems for a class of uncertain systems in which the uncertainty is described by an integral quadratic constraint. The new approach is developed by applying methods from linear quadratic optimal control theory. This leads to a method for model validation and fault diagnosis which is based around a robust Kalman filter type structure.

We analysed 78 carcinomas of the lung for allelic losses on chromosome 10q. The tumours were of different stage and grade and comprised 22 small-cell lung carcinomas (SCLC), 40 squamous cell carcinomas (SCC), 11 adenocarcinomas, four large-cell carcinomas and one carcinoid. They were investigated by six polymorphic markers located between 10q21 and 10qter. We observed a high incidence of loss of heterozygosity (LOH) in SCLC (91%) and metastatic SCC (56%). Non-metastatic SCC showed deletions in three cases (14%) and no LOH was found in the other types of non-small-cell lung cancer. The statistical analysis indicated that the presence of LOH correlated significantly with advanced tumour stages in the entire collective and in particular within the SCLC and SCC subgroups. For SCC, a positive association was found between LOH and metastases formation, while in SCLC the number of non-metastatic tumours was too small for a final conclusion. Whereas SCLC was frequently characterized by multiple allelic losses, suggesting the deletion of the entire chromosomal arm, SCC showed interstitial imbalances. A high incidence of allelic loss was observed between the markers D10S677 and D10S1223. The analysis of five informative cases suggested the presence of two non-overlapping regions between the loci D10S677/D10S1237 and D10S1213/D10S1223. In SCLC, we did not find mutations in the putative tumour-suppressor gene MXI1. The data indicate that LOH on chromosome 10q is associated with tumour progression in SCC and SCLC. Thus it may become a useful genetic marker in the assessment of the malignant potential of these tumour types.

Comparative genomic hybridization was applied to map DNA gains and losses in 39 invasive ductal breast carcinomas. Frequent abnormalities included gains on chromosomal regions 1q, 8q, 11q12-13, 16p, 19, 20q and X as well as frequent losses on 1p, 5q, 6q, 9p, 11q, 13q and 16q. Furthermore, frequent losses on 4q (20 cases) and 21q (14 cases) were found for the first time in this tumour type. High copy number amplifications were observed at 8q12-24, 11q11-13 and 20q13-ter. Highly differentiated tumours were associated with gains on 1q and 11q12-13 along with losses on 1p21-22, 4q, 13q, 11q21-ter. Undifferentiated breast carcinomas were characterized by additional DNA imbalances, i.e. deletions of 5q13-23, all of chromosome 9, the centromeric part of chromosome 13 including band 13q14 and the overrepresentation of chromosome X. We speculate that these changes are associated with tumour progression of invasive ductal breast cancer.

The genetic mechanisms that define the malignant behaviour of small-cell lung cancer (SCLC) are poorly understood. We performed comparative genomic hybridization (CGH) on 22 autoptic SCLCs to screen the tumour genome for genomic imbalances. DNA loss of chromosome 3p was a basic alteration that occurred in all tumours. Additionally, deletions were observed on chromosome 10q in 94% of tumours and on chromosomes 4q, 5q, 13q and 17p in 86% of tumours. DNA loss was confirmed by loss of heterozygosity (LOH) analysis for chromosomes 3p, 5q and 10q. Simultaneous mutations of these six most abundant genetic changes were found in 12 cases. One single tumour carried at least five deletions. DNA under-representations were observed less frequently on chromosome 15q (55%) and chromosome 16q (45%). The prevalent imbalances were clearly indicated by the superposition of the 22 tumours to a CGH superkaryogram. In our view, the high incidence of chromosomal loss is an indication that SCLC is defined by a pattern of deletions and that the inactivation of multiple growth-inhibitory pathways contributes in particular to the aggressive phenotype of that type of tumour.

Femoxetine and amitriptyline were compared double-blind in totally 38 patients with endogenous depression. Of these 25 patients completed the six weeks' treatment with 13 in the femoxetine group and 12 in the amitriptyline group. A significant improvement was seen for both drugs and it appears that femoxetine was equally as active as amitriptyline.No correlation was found between the plasma-concentration of femoxetine and the clinical effect.Side effects especially those of an anticholinergic nature appeared with a higher frequency in the amitriptyline group.

The current political changes in South Africa and the realization that there is a need to transform many institutions have resulted in strident calls for changes to mental health policies. However, it is also recognized that these changes must be coherent, and should enjoy the support of all interested constituencies. The authors surveyed members of the mental health professions, namely, Clinical and Counselling Psychologists to elicit their opińions regarding these changes. The aim was to obtain data on their current practice patterns and attitudes to change in mental health policies designed to meet the needs of the majority of South Africans. In this article the authors discuss results of the survey and emphasize some of the issues that need to be addressed if the mental health needs of the population are to be met.Die huidige politieke veranderinge in Suid-Afrika en die besef dat daar 'n behoefte is om instellings te transformeer het gelei tot ernstige beroepe om die geestegesondheidsbeleid ter verander. Nietemin word daar besef dat die veranderinge samehangend moet wees, en moet die ondersteuning van alle belangstellende groepe geniet. Om die nodige standpunte van hierdie verskillende groepe te bekom, was die lede van die Kliniese en Raadgewende Sielkundiges oor hul meinings gevra. Die doel was om data te bekom oor die huidige modelle en houdinge in die uitoefening van die beroep met betrekking tot veranderinge tot geestgesondheidsbeleid wat geruk is op die geestegesondheids behoeftes van die meerheid van Suid-Afrikaners. In hierdie artikel bespreek die outeurs die resultante van hierdie ondersoek en beklemtoon sommige van die vraagstukke waarmee rekening gehou moet word indien aan die geestegesondheidsbeloftes van die meerderheid van die bevolking voldoen moet word.

Jacobsen S, Petersen IS, Danneskiold-Samsøe B. Clinical Features in Patients with Chronic Muscle Pain - with Special Reference to Fibromyalgia. Scand J Rheumatol. 1993; 22: 69-76.Clinical characteristics were studied in patients with chronic muscle pain, divided into three groups according to the characteristics of their pain; "fibromyalgia" (n = 23), "widespread muscle pain" (n = 21), and "regional muscle pain" (n = 28). Typical fibromyalgia features were also seen in the other groups of patients, but not to the same extent. In particular. sleep disturbance, subjective swelling, cold and exercise intolerance and low self-reported physical performance were significantly related to fibromyalgia. The major components of fibromyalgia were not wholly different compared with other European and North American studies, except for sleep disturbance and subjective swelling, which was somewhat more pronounced in this study. The most used medications in fibromyalgia patients at referral were analgesics, anxiolytic drugs and female sex hormones. Medication in fibromyalgia was not excessive and seemed appropriate compared to the other patient groups. Effects of various biases and classification criteria on the results of fibromyalgia studies are discussed. The characteristic features of fibromyalgia, its stability when diagnosed and the promotion of research and patient management ustify the current classification of fibromyalgia at this stage.

Abstract: This paper is concerned with the problem of stabilizing an uncertain linear system using state feedback control. The uncertain systems under consideration are described by state equations containing unknown but bounded uncertain parameters. The uncertain parameters are classified into two types: either constant or time-varying. Indeed, the main feature of this paper is that it allows one to exploit the fact that some of the uncertain parameters are constant. In order to investigate the question of stabilizability, quadratic Lyapunov functions are used. Hence, the paper deals with the notion of quadratic stabilizability. The main result of the paper is a necessary and sufficient condition for the quadratic stabilizability of the uncertain systems under consideration.

This paper applies a recent result on nonlinear H∞-optimal control to give a necessary and sufficient condition for the existence of a state feedback controller which absolutely stabilizes a discrete-time uncertain nonlinear system with structured uncertainty. The class of uncertain systems being considered contain uncertainties which satisfy a certain sum constraint. This sum constraint is a nonlinear discrete-time version of the integral quadratic constraint uncertainty description. The main result is established by using a nonlinear S-procedure result, which enables the robust absolute stabilization problem to be converted into a equivalent nonlinear H∞-optimal control problem.