INTRODUCTION
Nursing care is provided for people with widely diverse health and sick care needs in multiple contexts worldwide. The knowledge and competence to meet such a wide variety of care needs may be daunting for the student starting a programme of study to become a registered nurse. Nursing programmes are designed to allow knowledge and practice experience to be accumulated and assimilated by the nursing student within the 3 or 4 year course period. However, learning is lifelong, and the journey of learning through a pre-registration nursing programme is only the beginning.
In the United Kingdom (UK), the knowledge and skills necessary to become registered as a nurse are primarily structured so that a student can focus on developing proficiencies to provide care for particular patient/client groups (Nursing and Midwifery Council 2004). Two of the groupings are age related, i.e. you register to deliver nursing care specifically to adults or specifically to children, usually with physical healthcare needs. The other two groupings are health condition related, i.e. nursing care is focused on people (children and adults) with mental health problems or people with learning disabilities. These ‘branches’ of nursing have their basis in the history of the development of nursing in the UK (Dingwall et al., 1988 and Nolan, 1998). Following a 1-year common generic programme, students begin to accumulate knowledge and experience specific to their chosen branch of nursing.
Curricula for nursing courses worldwide are broad ranging and usually include an eclectic mix of the following areas:
• Knowledge about the individual person, i.e. physical, psychological, social, cultural and spiritual in health and in sickness
• Knowledge about the environment of care to include safety, policy and politics in the delivery of health care
• Knowledge on how to provide evidence-based nursing care to promote health and care for the sick
• Knowledge of self as a person, as a learner, and as a future professional nurse.
Nursing, along with all the other professions involved in the delivery of health care, is a practice based profession. This means that completion of a university academic course leading to a degree or diploma is not sufficient for professional registration. All students must also learn to nurse patients/clients in the real world of health care. A substantial part of any nursing course is spent learning to nurse in a wide variety of healthcare contexts (in the UK this is currently 50% of the course programme; Nursing and Midwifery Council 2004). Knowledge gained in practice is unique for every student, as practice placement learning depends on the individual healthcare encounters experienced by each student. Making learning explicit is dependent on the interpretation of experience and events made by the learner alone and/or with their practice mentor/supervisor. Knowledge gained in this way is very personal and often depends on the reflective skills of the student and the reflective and learning facilitation skills of the practice mentor/supervisor.
In this first chapter we are presenting an overview of the generic underpinning knowledge that supports the role of the registered nurse in any branch of nursing or context of care. All other chapters of the book focus on knowledge for decision making in providing care to meet specific patient/client needs. The organization of the content of each chapter follows the same pattern as this first chapter.
OVERVIEW
Subject knowledge
This section outlines definitions of nursing and their implications for the development of the nursing profession in the UK and worldwide. An overview of theories and models of nursing, first developed in the United States of America (USA), is presented along with a brief summary of one particular model widely applied in UK nursing. There is an overview of how the image and role of the nurse is perceived by society. Knowledge of people’s needs in health and illness and the policy and politics around the delivery of health care in the UK is outlined. There is an introduction to the globalization of healthcare delivery and the impact of the international movement of the nursing workforce.
Care delivery knowledge
This section focuses on the need for evidence-based health care. It outlines the processes needed to access quality evidence on which to base clinical decisions in the delivery of care. Methods of organizing nursing and other healthcare professions to deliver patient/client centred care is presented with an emphasis on the need for interprofessional learning and working. An overview of the scope of practice available in each of the four branches of nursing is presented.
Professional and ethical knowledge
Accountability and autonomy are central to any profession. This section explores the professional, legal and ethical underpinnings of nursing with an overview of virtue ethics and the impact of the Human Rights Act.
Personal and reflective knowledge
Learning to be a nurse provides an introduction to how a nursing course might be delivered, with an overview of problem based learning and an account of reflective learning. There is an introduction to keeping a Portfolio of learning. One family case study with questions will help you check and consolidate your learning from the chapter.
SUBJECT KNOWLEDGE
DEFINITIONS, THEORIES AND MODELS
The verb ‘to nurse’ is used in everyday language as meaning ‘to care for’, ‘look after’, ‘tend’, ‘foster’, ‘nurture’; and it can be applied in many different everyday situations. Here we are looking at the definitions applied to professional nursing, that is where a person completes a recognized course of study and is assessed as competent and fit to be registered to practise. Registration is usually regulated by a national Nursing Board and is specific to individual countries of the world. Transferability of registration from one country to another is at the discretion of the host country (see Contexts of Care, below).
According to the Royal College of Nursing (RCN; 2003: 1), most countries have a legal definition of the title ‘nurse’ and some also have a legal definition of ‘nursing’. The legal definition in the UK is policy orientated and focused around distinguishing between what care should be delivered by registered nurses as opposed to unregistered carers (Office of Public Information 2001). A professional definition is necessary to provide a framework for outlining the scope of practice of the registered nurse and to guide codes of ethics and professional conduct (Royal College of Nursing 2003).
Professional definitions are available and have changed over time. In the 20th century, the definitions most often quoted in the literature were those written by Florence Nightingale, 1859 and Henderson, 1960. Both focus on the activities of the nursing role:
Nature alone cures … And what nursing has to do … is to put the patient in the best condition for nature to act upon him.
to assist the individual, sick or well, in the performance of those activities contributing to health or its recovery (or to a peaceful death) that he would perform unaided if he had the necessary strength, will, or knowledge.
The World Health Organization (WHO; 2002) and the International Council of Nurses (International Council of Nurses, 1987 and International Council of Nurses, 2002) have provided more recent definitions. The ICN definition below attempts to include the broad scope of nursing roles within this abridged version of their 1987 definition of nursing:
Nursing encompasses autonomous and collaborative care of individuals of all ages, families, groups and communities, sick or well, and in all settings. Nursing includes the promotion of health, prevention of illness, and the care of ill, disabled and dying people. Advocacy, promotion of a safe environment, research, participation in shaping health policy and in patient and health systems management, and education are also key nursing roles.
In the UK, the Royal College of Nursing’s (2003: 3) document Defining Nursing provides a more comprehensive examination of the nursing role in the 21st century. Alongside a short definition statement it describes nursing as:
the use of clinical judgement in the provision of care to enable people to improve, maintain or recover health, to cope with health problems, and to achieve the best possible quality of life, whatever their disease or disability until death …
It further outlines the defining characteristics of nursing as including:
1 a particular purpose for nursing
2 a particular mode for nursing interventions
3 a particular domain
4 a particular focus
5 a particular value base
6 a commitment to partnership.
These six defining characteristics of nursing provide a succinct overview of the broad scope of the nursing role in the 21st century.
• Reflect on your perceptions of the role of the nurse prior to commencing your course. Who and what influenced your perceptions?
• Ask your friends who are not nurses what they think about the nursing profession.
• Refer to some of the definitions quoted and debate which definition helps you to define your understanding and experience of the role of a registered nurse.
• Debate your thoughts and ideas with your peer group.
Throughout the 20th century, particularly in the USA, nursing theories and models were developed (Fawcett, 2004 and McKenna et al., 2008). Learning about these theories has been part of nursing curricula, despite the relative lack of application of many of them in the practice setting (Wimpenny 2002; see Table 1.1 for list of the main theories and their focus). The most popular nursing model, and one which did become embedded in practice settings in the UK, is that of Roper et al., 1980, Roper et al., 2000 and Holland et al., 2003. This model focuses on the delivery of nursing care through viewing people as having 12 activities of daily living, with care being targeted on promoting and enabling independence in these activities. In spite of its popularity, an increasing focus on collaborative multiprofessional working, with concurrent concerns about cost and quality, means that individual professional models are now being replaced by a ‘care pathways’ approach (http://www.evidence-based-medicine.co.uk/ebmfiles/WhatisanICP.pdf; see Care Delivery Knowledge).
| Focus of model/s | Name/year/place | Key idea | Practical application |
|---|---|---|---|
| Environment of care | Nightingale (1859) UK | Manipulation of external environment to heal the sick, e.g. ventilation, light, warmth, diet, cleanliness | Infection control in 19th century and applicable today with hospital acquired infections and safe environment issues Public health nursing |
| Dealing with patients’ problems/needs | Patient has 14 basic needs Patient has 12 activities of living | Roper model widely used in nursing the physically ill in UK | |
| Promoting independence/self-care | Orem (1971) USA | Patient able to self-care and/or has self-care deficits | Nurse-led clinics and rehabilitation and elderly care in USA and in UK Used in children’s nursing |
| Nursing as caring | Caring is the core of nursing; is transcultural; is holistic; has 10 caring factors Expertise in caring developed through stages | Dealing with patients with diverse cultural needs; applied in critical care areas in adult and child to promote holistic care Assess clinical knowledge development in nurses in many practice settings (Benner) | |
| Nursing as an interpersonal activity | Peplau (1952) USA | Nursing relationship with patients is therapeutic and nursing actions arise from this relationship | Main application in mental health nursing, psychotherapy |
| Patients as systems adapting to environment | Roy (1976) USA | Nurses help patients to adapt to illness and/or environment in physical, psychological and social ways | Led to development of ‘nursing diagnosis’. Model adopted across an eclectic mix of adult nursing environments. Also used for child health care |
ROLE AND IMAGE OF THE NURSE
Although pre-registration nursing degrees have been available in a small selection of universities in the UK since the early 1960s, nursing has only relatively recently (1989) been accepted as a profession where all members should be educated within universities or higher education institutions (HEIs; United Kingdom Central Council for Nurses Midwives and Health Visitors 1986). Reasons for continuing to keep the apprenticeship work-based learning training model until the 1990s could be ascribed to the perceived public image of the nurse. According to Fealy & McNamara (2007) there is a particular and enduring set of images of the nurse which provide a public argument against the notion of an ‘educated’ nurse. There is a view that mental work and manual work are opposites and that nursing should be a practical and commonsense occupation unworthy of academic study. Despite such views, the nursing profession is slowly becoming more visible within academia and more influential in the practice setting, with an acknowledgement that all nurses should be educated to degree level (European Federation of Nurses 2005; see also Contexts of Care).
Kalisch et al (2007) reported on the results of a study of the image of nursing on the Internet utilizing content analysis methodology. A total of 144 websites were content-analysed in 2001 and 152 in 2004. Approximately 70% of the sites showed nurses as intelligent and educated and 60% as respected, accountable, committed, competent and trustworthy. Nurses were also shown as having specialized knowledge and skills in 70% (2001) and 62% (2004) of the websites. Doctoral-prepared nurses were evident in 19% of the websites in 2001 and this number doubled in 2004.
Kalisch’s recent work (Kalisch et al 2007) is significant in that it does show an improving image from those portrayed in the media during the 20th century (Kalisch & Kalisch 1986). It allows the profession to move on and continue to establish, maintain and consolidate its position as equal to other healthcare professions within the university setting and in the healthcare delivery arena. The scope of practice for professional nurses is expanding and role specialization and role autonomy are increasingly recognized.
Obtain a copy of a UK nursing journal which also includes job advertisements (e.g. Nursing Times, Nursing Standard, Royal College of Nursing Bulletin).
• Map the range and scope of nursing roles contained within the job adverts.
• Review the diversity of job titles and the image they portray.
• How many of the job roles advertised portray the nurse as the key clinical decision maker?
• Reflect on the range of choices available to you in future when you become a registered nurse in any of the branches of nursing.
PEOPLE AS RECIPIENTS OF NURSING CARE
Throughout this textbook, the Subject Knowledge section of each chapter focuses on the knowledge underlying people’s responses to health and illness by including information on physiological, psychosocial, cultural and spiritual needs and changes in health and illness. Your nursing programme will include an exploration of all these subject areas in some form within the curriculum.
Knowledge of the biological basis of practice is relevant in all branches of nursing, though application of that knowledge in practice will vary greatly depending on the care needs of people being nursed. Historically, when nursing was primarily described as taking place in an institution and focused on ‘doing what the doctor ordered’ to cure the patient, knowledge of the physical body in health and disease took priority (Rafferty 1996). With the development of nursing as a unique professional role offered in multiple contexts, the shift has been to re-focus on the knowledge needed for caring as opposed to curing. Although knowledge from the biosciences is still essential for safe nursing practice (Clancy et al., 2000 and Friedel and Treagust, 2005), knowledge of the person’s psychological, social, spiritual and cultural needs now tends to dominate the knowledge base of nursing.
It is important to note that knowledge disciplines studied in nursing are not unique to nursing. Other health and social care professions share the same knowledge base but will apply it in unique ways to suit their individual roles (Royal College of Nursing 2003). With the increasing complexity of people’s health and social care problems, there is a growing need for all professions to collaborate more effectively in delivering patient/client centred care (Department of Health 2005). Professional teams are becoming more central to health care as evidence emerges that effective teamwork enhances the quality of patient care and healthcare consumers demand that healthcare professionals engage in effective partnerships (Illingworth & Chelvanayagam 2007).
Since 2000, the UK government has been encouraging universities to provide opportunities for students of health and social care courses to learn together (Department of Health 2000). Interprofessional learning is described by Barr (2005) as occurring when members (students) of two or more professions associated with health and/or social care engage in learning from and about each other (http://www.caipe.org.uk/). When completing your course, you may find that your university programme includes modules incorporating interprofessional learning in theory and practice throughout your course. You may also be participating in problem based learning activities that allow you to learn and work with students from other health and social care professions in providing collaborative solutions to patient case studies.
Shared partnership with people as clients and patients is being increasingly emphasized in a consumer led society (see Ch. 19). This requires genuine listening and respect for the contribution people make to their own health and/or recovery (Nursing and Midwifery Council 2008). People may have more choice in when and whom they access for health care and their expectations of the standard of care delivered is high. Patient led organizations and groups provide support at all levels and for a very large range of conditions (Binley’s Handbook of Patient Groups 2008).
Reflect on the range of patients/clients you cared for on your recent placements.
• What subject knowledge gained from your course was the most helpful to you in learning to provide nursing care?
• How did you cope with any deficits in your knowledge?
• List the other health or social care professionals also involved in providing care.
• Describe your perceptions of what knowledge these professionals have that is the same as your knowledge base and what might be different.
• Discuss your thoughts and findings with your peers and debate the advantages and disadvantages of participating in interprofessional learning.
CONTEXTS OF CARE
Throughout the ‘first world’, health care is predominantly purchased by people through contributions to insurance systems that will pay fully or proportionately for medical and hospital care when it is needed. In the developing world, health care is often delivered through voluntary organizations supported by worldwide charities. In the UK, the dominant system is through a state supported national health service. The following sections provide insights into the history and politics of the UK National Health Service (NHS) before introducing the influence of globalization on the workforce and its impact on nursing worldwide.
The National Health Service
In the UK, the majority of nurses are trained by and, at some stage of their career, will work for the National Health Service (NHS). Established in 1948, the success of the NHS is measured by the successful treatment of illnesses and is influenced heavily by the medical model of working. In the beginning of the service, day-to-day NHS care was provided by general practitioners in the community, with more serious illnesses being referred to, and treated by, medical specialists in hospitals, either through the out-patient service or as an in-patient.
Funding for the NHS comes from general taxation and initially all services were non-means tested and free at the point of delivery, although as the service developed some charges were introduced, for example for prescriptions and for dental and optical care. It was at first expected that the cost of the NHS would fall as the medical profession treated the illnesses in the population. This did not happen, however. At its launch, NHS funding took 3.75% of the country’s gross domestic product (GDP) but by 2000 this had risen to around 7% (Appleby 2005). Consequently, the cost and funding of the NHS has been questioned almost continuously since its inception.
The problem with the medical approach is that it is very effective at treating illnesses from which people can recover. Unfortunately, another group of people exist who suffer from long-term or chronic illnesses, and here the medical approach is less successful. The nature of these illnesses means that the sufferers will not recover from them fully and will continue to seek support from the NHS to manage their symptoms. Examples of long-term conditions include hypertension, arthritis, diabetes and obstructive pulmonary disease, some learning disabilities and long-term mental health problems as well as disabilities arising from other major conditions such as strokes. Long-term conditions tend to be more prevalent in older people and the UK has an ageing population, meaning that even greater demand is likely to be made on the NHS in the future. In this demographic context, to continue with the hospital centred NHS structure would be prohibitive on economic grounds so, following the implementation of the National Health Service and Community Care Act 1990, the provision of NHS care began to be transferred away from the hospitals and into the community. This enabled the use of informal (unpaid) carers at home, and in turn reduced the demand on expensive NHS staff and resources, and of course reduced the financial demand on the taxpayer. The role of the NHS consequently changed from being a provider of care to one that enables individuals, with their families, to care for themselves (for more information on this see Ch. 9, ‘Stress, relaxation and rest’).
The implications for hospital services in this latter period of the NHS’s history were profound. The National Health Service and Community Care Act 1990 also introduced the marketplace philosophy into health and social care. Rather than being the natural provider of services for a community, hospital services now had to tender and compete for contracts for services which were negotiated with purchasers – community based general practitioners (GPs). The Health Act 1999 formalized this process, setting the foundations for the NHS to become a primary care led service. It also introduced National Service Frameworks (NSFs; see http://www.dh.gov.uk/en/Healthcare/NationalServiceFrameworks/index.htm for a complete list), which identify standards for the delivery of services and become targets that have to be achieved by the local health services. These are monitored and supervised by the Healthcare Commission and the Strategic Health Authorities (SHAs) which were introduced in Shifting the Balance of Power Within the NHS (Department of Health 2001). This change of emphasis on care commissioning and delivery – from a hospital based system to a community based system – was finalized in the NHS Improvement Plan (Department of Health 2004a), following which primary care services controlled 80% of NHS funding.
To enable community based services, contemporaneous legislation was introduced that focused on streamlining services and supporting carers. Throughout the history of the NHS there had been poor communication and conflicting working priorities between the NHS services and local authority provided social care services, to the detriment of community services overall. The NHS Plan (Department of Health 2000) and Shifting the Balance of Power within the NHS (Department of Health 2001) attempted to address some of the difficulties by introducing partnership working. In this system, health authorities and local authorities joined together to become one employer. Being a single organization it was hoped that this would lead to better targeting and consequently improved community services.
Because of the increasing demand placed upon informal carers, the government looked at ways to support them more fully. Supporting People with Long Term Conditions: Liberating the Talents of Nurses who care for People with Long Term Conditions (Department of Health 2005) introduced community matrons, whose role was to manage a caseload of people with chronic illnesses, and their carers, to help to prevent a deterioration in their condition, or if they did deteriorate, to help them to manage their problems at home rather than being admitted to hospital. Other legislation focused on supporting carers so that they could continue with their existing responsibilities as well as care for their relative (see Evolve 1.1 for list of legislation and a summary of its impact).
As a consequence of the change in emphasis in the NHS to community led services, many nurses working in hospitals are likely to find themselves concentrating on acute, fast-turnaround care, whereas nurses working in the community will be involved in various supportive schemes to either prevent people being admitted to hospital or to coordinate facilities that will enable their early discharge.
International influences
The delivery of nursing care in contemporary society is complex. Nursing can no longer be totally defined by geographical distance nor by region. Today health care is a global undertaking where there are worldwide influences. This section will briefly explore some key considerations.
The information highway
Today information about nursing is truly global. With the advent of the Internet and electronic library gateways, it is possible to retrieve evidence for care from a wide range of sources across the world. It is also possible to communicate via weblinks with nurses working in other countries and find out first hand about the experience of nursing globally. However, evidence should be considered with care. As well as the usual considerations associated with the evaluation of information and research (Cormack et al., 2006 and Parahoo, 2006), there is a need to think about the application of evidence across cultures and contexts. Will the information from another culture transfer to your setting within the UK? Equally, will your knowledge of nursing from the UK transfer outwards to settings across the world?
The impact of migration, inward and outward
It is important to know more about international nursing today because there has been a massive increase in the movement of people across the globe over the last decade. Even if you decide that travelling or moving across the world is not for you, and do not migrate outwardly from the UK, you will encounter the impact of inward migration as people needing health and social care in the UK increasingly emanate from a diverse range of cultures and countries. Nurses also move to the UK to work, both from overseas countries and from the European Union (Nursing and Midwifery Council 2007).
The recruitment of nurses is not without some difficulties. While it is expected that individual nurses will move across the world for many reasons, including seeking experience or better conditions for themselves and their families or for work if jobs in their own localities are few, it is important to recognize that both in the UK and globally, the number of healthcare workers is insufficient to meet future demand. In fact in some countries the situation is critical, and this is frequently the case in areas where health care is needed most (e.g. sub-Saharan Africa). This has led the World Health Organization (WHO) to address the issue of a global workforce in nursing. WHO has made a number of recommendations, including the consideration of individual countries to develop a healthcare workforce for domestic need, and the recognition that recruitment of healthcare workers from disadvantaged countries by wealthy countries is unethical and leads to greater inequality (WHO 2006).
In the European Union (EU) there is a recognition that mobility and trade agreements between countries are beneficial as they enable development of wealth and economic growth. The Treaty of Lisbon (2007) is determining change within the EU towards greater economic collaboration. For nursing, it is the response of the universities to the Treaty of Lisbon which is likely to create the greatest impact. Universities across Europe are committed to the development of a European Higher Education Area by 2010. This is being achieved through the ‘Bologna declaration’ (Bologna Process 1999). There are many components in this complex process but the main ones include comparability of degrees and student experience, and mobility of qualifications. In the future it will mean that qualifications gained in the UK will have similar standards to those elsewhere in Europe and will be acceptable to employers. It should also mean that lifelong learning by individuals can be achieved across different countries. It is important also to recognize that nursing has an agreement from a professional perspective through the EU directive 2005/36/EC (European Union (EU) Parliament and Council 2005). This directive identifies the number of hours and type of experience student nurses must complete in order to register as a nurse responsible for the delivery of general care.
Electives and learning about internationalization
In order to be ready for this changing world, it is important that you take all opportunities to find out about global nursing and nursing in Europe. Universities are responding to this through the development of electives and exchange opportunities such as Erasmus (http://www.erasmus.ac.uk), and also through the development of shared work programmes with schools of nursing in other countries. The advent of video links and web based technology means that it is possible to talk about nursing with nurses from many other countries and even share lessons or conferences together. You can participate in European working through the Students’ Union or through the RCN Association of Nursing Students who are members of the European Nursing Students Association (ENSA).
CARE DELIVERY KNOWLEDGE
The RCN definition of nursing refers to the ‘use of clinical judgement in the provision of care’ (Royal College of Nursing 2003: 3). In this section we will first look at the basis for clinical decision making in evidence-based practice before reviewing the organizational approaches in common use to manage the delivery of care. There is a brief overview of the scope for nursing practice in the different branches of nursing.
CLINICAL DECISION MAKING
In the delivery of nursing care in institutional settings, nurses are in constant contact with their patients over a 24-hour period. Any changes (physical and/or mental) observed in a patient’s condition are first seen by the nurse; therefore clinical decision making is a key application of the nursing role. Nurses very often ‘own’ and manage the environment of care, ensuring that resources for care are available. A number of services are also ‘nurse led’ (e.g. tissue viability, diabetic care, ‘first contact’), giving the nurse greater autonomy in decision making. However, the majority of decisions in day-to-day practice take place in a complex environment, in collaboration with a diverse healthcare team and in partnership with patients/clients who have complex needs (Gurbutt 2006).
Knowledge for decision making is obtained from many sources and has been described as both informative (i.e. acquired through the study of written knowledge) and intuitive/experiential (i.e. developed through experience and learning from that experience through reflective practice) (Schon, 1991, Benner, 2001 and Banning, 2008). The views and rights of patients/clients and the context of care are also key factors in clinical decision making. In the world of practice, all sources of knowledge are constantly interacting to inform day-to-day decisions in healthcare delivery. Registered nurses need to be able to describe how and why they came to particular decisions in the delivery of nursing care. As a learner in the practice setting you should be able to ask the nurse and other members of the healthcare team about their decisions and thus learn from practice experience (Standing 2007).
You are allocated to work with a registered nurse (RN) and a healthcare assistant in providing rehabilitation care to a group of 10 elderly people with complex care needs based on a mixture of mental and physical health problems. The RN managed and directed the care during the shift.
• Describe the RN’s approach to organizing priorities in care giving during the shift.
• Under what influence or on what basis did he/she make decisions (try to obtain this information through reflective discussion at the end of the shift).
• Did you experience any changes in decisions over the period of the shift and what do you think influenced these changes.
• Decide how you could record what you had learned so that you could explain your understanding of the RN’s decision making to another learner/peer group of learners.
There is an increasing emphasis on clinical decision making being more prescriptive as health care has to become more cost-effective and evidence based. Decisions of all healthcare professionals are now strongly influenced by protocols, clinical guidelines, clinical standards and benchmarks for best practice. Computer decision-support systems are used to make expert knowledge more widely available (Gurbutt 2006). Although clinical research evidence has strongly informed medical practice, the evidence-based healthcare movement is now accepted as a legitimate source for clinical decision making by all health professionals (Muir Gray 2001).
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