Attachment theory, originating in the work of John Bowlby, is a psychological, evolutionary and ethological theory that provides a descriptive and explanatory framework for understanding interpersonal relationships between human beings.

In order to formulate a comprehensive theory of the nature of early attachments, Bowlby explored a range of fields including evolution by natural selection, object relations theory (psychoanalysis), control systems theory, evolutionary biology and the fields of ethology and cognitive psychology. There were some preliminary papers from 1958 onwards but the full theory is published in the trilogy Attachment and Loss, 1969- 82. Although in the early days Bowlby was criticised by academic psychologists and ostracised by the psychoanalytic community, attachment theory has become the dominant approach to understanding early social development and given rise to a great surge of empirical research into the formation of children's close relationships.

Brief description of theory
In infants, behavior associated with attachment is primarily a process of proximity seeking to an identified attachment figure in situations of perceived distress or alarm, for the purpose of survival. Infants become attached to adults who are sensitive and responsive in social interactions with the infant, and who remain as consistent caregivers for some months during the period from about six months to two years of age. During the later part of this period, children begin to use attachment figures (familiar people) as a secure base to explore from and return to. Parental responses lead to the development of patterns of attachment which in turn lead to 'internal working models' which will guide the individual's feelings, thoughts, and expectations in later relationships. Separation anxiety or grief following serious loss are normal and natural responses in an attached infant.

The human infant is considered by attachment theorists to have a need for a secure relationship with adult caregivers, without which normal social and emotional development will not occur. However, different relationship experiences can lead to different developmental outcomes. Mary Ainsworth developed a theory of a number of attachment patterns or "styles" in infants in which distinct characteristics were identified; these were secure attachment, avoidant attachment, anxious attachment and, later, disorganized attachment. In addition to care-seeking by children, peer relationships of all ages, romantic and sexual attraction, and responses to the care needs of infants or sick or elderly adults may be construed as including some components of attachment behavior.

Earlier theories
A theory of attachment is a framework of ideas that attempt to explain attachment, the almost universal human tendency to prefer certain familiar companions over other people, especially when ill, injured, or distressed. Historically, certain social preferences, like those of parents for their children, were explained by reference to instinct, or the moral worth of the individual.  The concept of infants' emotional attachment to caregivers has been known anecdotally for hundreds of years. Most early observers focused on the anxiety displayed by infants and toddlers when threatened with separation from a familiar caregiver. Psychological theories about attachment were suggested from the late nineteenth century onward. Freudian theory attempted a systematic consideration of infant attachment and attributed the infant's attempts to stay near the familiar person to motivation learned through feeding experiences and gratification of libidinal drives. In the 1930s, the British developmentalist Ian Suttie put forward the suggestion that the child's need for affection was a primary one, not based on hunger or other physical gratifications. A third theory prevalent at the time of Bowlby's development of attachment theory was "dependency". This approach posited that infants were dependent on adult caregivers but that dependency was, or should be outgrown as the individual matured. Such an approach perceived attachment behaviour in older children as regressive whereas within attachment theory older children and adults remain attached and indeed a secure attachment is associated with independent exploratory behaviour rather than dependence. William Blatz, a Canadian psychologist and teacher of Bowlby's colleague Mary Ainsworth, was among the first to stress the need for security as a normal part of personality at all ages, as well as normality of the use of others as a secure base and the importance of social relationships for other aspects of development.

Current attachment theory focuses on social experiences in early childhood as the source of attachment in childhood and in later life. Attachment theory was developed by Bowlby as a consequence of his dissatisfaction with existing theories of early relationships.

Early developments

Bowlby was influenced by the beginnings of the object relations school of psychoanalysis and in particular, Melanie Klein, although he profoundly disagreed with the psychoanalytic belief then prevalent that saw infants' responses as relating to their internal fantasy life rather than to real life events. As Bowlby began to formulate his concept of attachment, he was influenced by case studies by Levy, Powdermaker, Lowrey, Bender and Goldfarb. An example is the one by David Levy that associated an adopted child's lack of social emotion to her early emotional deprivation. Bowlby himself was interested in the role played in delinquency by poor early relationships, and explored this in a study of young thieves. Bowlby's contemporary René Spitz proposed that "psychotoxic" results were brought about by inappropriate experiences of early care. A strong influence was the work of James and Joyce Robertson who filmed the effects of separation on children in hospital. They and Bowlby collaborated in making the 1952 documentary film A Two-Year Old Goes to the Hospital illustrating the impact of loss and suffering experienced by young children separated from their primary caretakers. This film was instrumental in a campaign to alter hospital restrictions on visiting by parents.

In his 1951 monograph for the World Health Organization, Maternal Care and Mental Health, Bowlby put forward the hypothesis that "the infant and young child should experience a warm, intimate, and continuous relationship with his mother (or permanent mother substitute) in which both find satisfaction and enjoyment" and that not to do so may have significant and irreversible mental health consequences. This proposition was both influential in terms of the effect on the institutional care of children, and highly controversial. There was limited empirical data at the time and no comprehensive theory to account for such a conclusion.

Attachment theory

Following the publication of Maternal Care and Mental Health, Bowlby sought new understanding from such fields as evolutionary biology, ethology, developmental psychology, cognitive science and control systems theory and drew upon them to formulate the innovative proposition that the mechanisms underlying an infants tie emerged as a result of evolutionary pressure. He realised that he had to develop a new theory of motivation and behaviour control, built on up-to-date science rather than the outdated psychic energy model espoused by Freud. Bowlby expressed himself as having made good the "deficiencies of the data and the lack of theory to link alleged cause and effect" in "Maternal Care and Mental Health" in his later work "Attachment and Loss" published between 1969 and 1980.

Bowlby's first official representations were carried out for the relationship theory in three very controversial lectures in 1957 by the British Psychoanalytical Society in London. The formal origin of attachment theory can be traced to the publication of two 1958 papers, one being Bowlby's The Nature of the Child's Tie to his Mother, in which the precursory concepts of "attachment" were introduced, and Harry Harlow's The Nature of Love, based on the results of experiments which showed, approximately, that infant rhesus monkeys spent more time with soft mother-like dummies that offered no food than they did with dummies that provided a food source but were less pleasant to the touch. Bowlby followed this up with two more papers, Separation Anxiety (1960a), and Grief and Mourning in Infancy and Early Childhood (1960b). At about the same time, Bowlby's former colleague, Mary Ainsworth was completing extensive observational studies on the nature of infant attachments in Uganda with Bowlby's ethological theories in mind. Mary Ainsworth's innovative methodology and comprehensive observational studies informed much of the theory, expanded its concepts and enabled some of its tenets to be empirically tested. Attachment theory was finally presented in 1969 in Attachment the first volume of the Attachment and Loss trilogy. The second and third volumes, Separation: Anxiety and Anger and Loss: Sadness and Depression followed in 1972 and 1980 respectively. Attachment was revised in 1982 to incorporate more recent research.

Ethology
Bowlby's attention was first drawn to ethology when he read Lorenz's 1952 publication in draft form although Lorenz had published much earlier work. Soon after this he encountered the work of Tinbergen, and began to collaborate with Robert Hinde. In 1953 he stated "the time is ripe for a unification of psychoanalytic concepts with those of ethology, and to pursue the rich vein of research which this union suggests".

Konrad Lorenz had examined the phenomenon of "imprinting" and felt that it might have some parallels to human attachment. Imprinting, a behavior characteristic of some birds and a very few mammals, involves rapid learning of recognition by a young bird or animal exposed to a conspecific or an object or organism that behaves suitably. The learning is possible only within a limited age period, known as a critical period. This rapid learning and development of familiarity with an animate or inanimate object is accompanied by a tendency to stay close to the object and to follow when it moves; the young creature is said to have been imprinted on the object when this occurs. As the imprinted bird or animal reaches reproductive maturity, its courtship behavior is directed toward objects that resemble the imprinting object. Bowlby's attachment concepts later included the ideas that attachment involves learning from experience during a limited age period, and that the learning that occurs during that time influences adult behavior. However, he did not apply the imprinting concept in its entirety to human attachment, nor assume that human development was as simple as that of birds. He did, however, consider that attachment behavior was best explained as instinctive in nature, an approach that does not rule out the effect of experience, but that stresses the readiness the young child brings to social interactions. Some of Lorenz's work had been done years before Bowlby formulated his ideas, and indeed some ideas characteristic of ethology were already discussed among psychoanalysts some time before the presentation of attachment theory.

Psychoanalysis
Bowlby's view of attachment was also influenced by psychoanalytical concepts and the earlier work of psychoanalysts. In particular he was influenced by observations of young children separated from familiar caregivers, as provided during World War II by Anna Freud and her colleague Dorothy Burlingham.  Observations of separated children's grief by René Spitz were another important factor in the development of attachment theory. However, Bowlby rejected psychoanalytical explanations for early infant bonds. He rejected both Freudian "drive-theory", which he called the Cupboard Love theory of relationships, and early object-relations theory as both in his view failed to see the attachment as a psychological bond in its own right rather than an instinct derived from feeding or sexuality. Thinking in terms of primary attachment and neo-darwinism, Bowlby identified as what he saw as fundamental flaws in psychoanalysis, namely the overemphasis of internal dangers at the expense of external threat, and the picture of the development of personality via linear "phases" with "regression" to fixed points accounting for psychological illness. Instead he posited that several lines of development were possible, the outcome of which depended on the interaction between the organism and the environment. In attachment this would mean that although a developing child has a propensity to form attachments, the nature of those attachments depends on the environment to which the child is exposed.

Internal working model
The important concept of the internal working model of social relationships was adopted by Bowlby from the work of the philosopher Kenneth Craik, who had noted the adaptiveness of the ability of thought to predict events, and stressed the survival value of and natural selection for this ability. According to Craik, prediction occurs when a "small-scale model" consisting of brain events is used to represent not only the external environment, but the individual's own possible actions. This model allows a person to mentally try out alternatives and to use knowledge of the past in responding to the present and future. At about the same time that Bowlby was applying Craik's ideas to the study of attachment, other psychologists were using these concepts in discussion of adult perception and cognition.

Cybernetics
The theory of control systems (cybernetics), developing during the 1930s and '40s, influenced Bowlby's thinking. The young child's need for proximity to the attachment figure was seen as balancing homeostatically with the need for exploration. The actual distance maintained would be greater or less as the balance of needs changed; for example, the approach of a stranger, or an injury, would cause the child to seek proximity when a moment before he had been exploring at a distance.

Behavioural development and attachment
Behaviour analysts have constructed models of attachment. Such models are based on the importance of contingent relationships. Behaviour analytic models have received support from research. and meta-analytic reviews.

Developments
Although research on attachment behaviors continued after Bowlby's death in 1990, there was a period of time when attachment theory was considered to have run its course. Some authors argued that attachment should not be seen as a trait (lasting characteristic of the individual), but instead should be regarded as an organizing principle with varying behaviors resulting from contextual factors. Related later research looked at cross-cultural differences in attachment, and concluded that there should be re-evaluation of the assumption  that attachment is expressed identically in all humans. In a recent study conducted in Sapporo, Behrens, et al., 2007 found attachment distributions consistent with global norms using the six-year Main & Cassidy scoring system for attachment classification.

Interest in attachment theory continued, and the theory was later extended to adult romantic relationships by Cindy Hazan and Phillip Shaver. Peter Fonagy and Mary Target have attempted to bring attachment theory and psychoanalysis into a closer relationship by way of such aspects of cognitive science as mentalization, the ability to estimate what the beliefs or intentions of another person may be. A "natural experiment" has permitted extensive study of attachment issues, as researchers have followed the thousands of Romanian orphans who were adopted into Western families after the end of Nicolae Ceauşescu's regime. The English and Romanian Adoptees Study Team, led by Michael Rutter, has followed some of the children into their teens, attempting to unravel the effects of poor attachment, adoption and new relationships, and the physical and medical problems associated with their early lives. Studies on the Romanian adoptees, whose initial conditions were shocking, have in fact yielded reason for optimism. Many of the children have developed quite well, and the researchers have noted that separation from familiar people is only one of many factors that help to determine the quality of development.

Neuroscientific studies are examining the physiological underpinnings of observable attachment style, such as vagal tone which influences capacities for intimacy, stress response which influences threat reactivity (Lupien, McEwan, Gunnar & Heim, 2009), as well as neuroendocrinology such as oxytocin,. These types of studies underscore the fact that attachment is an embodied capacity not only a cognitive one.

Effects of changing times and approaches
Some authors have noted the connection of attachment theory with Western family and child care patterns characteristic of Bowlby's time. The implication of this connection is that attachment-related experiences (and perhaps attachment itself) may alter as young children's experience of care change historically. For example, changes in attitudes toward female sexuality have greatly increased the numbers of children living with their never-married mothers and being cared for outside the home while the mothers work. This social change, in addition to increasing abortion rates, has also made it more difficult for childless people to adopt infants in their own countries, and has increased the number of older-child adoptions and adoptions from third-world sources. Adoptions and births to same-sex couples have increased in number and even gained some legal protection, compared to their status in Bowlby's time.

One focus of attachment research has been on the difficulties of children whose attachment history was poor, including those with extensive non-parental child care experiences. Concern with the effects of child care was intense during the so-called "day care wars" of the late 20th century, during which the deleterious effects of day care were stressed. As a beneficial result of this controversy, training of child care professionals has come to stress attachment issues and the need for relationship-building through techniques such as assignment of a child to a specific care provider. Although only high-quality child care settings are likely to follow through on these considerations, nevertheless a larger number of infants in child care receive attachment-friendly care than was the case in the past, and emotional development of children in nonparental care may be different today than it was in the 1980s or in Bowlby's time.

Finally, any critique of attachment theory needs to consider how the theory has connected with changes in other psychological theories. Research on attachment issues has begun to include concepts related to behaviour genetics and to the study of temperament (constitutional factors in personality), but it is unusual for popular presentations of attachment theory to include these. Importantly, some researchers and theorists have begun to connect attachment with the study of mentalization or Theory of Mind, the capacity that allows human beings to guess with some accuracy what thoughts, emotions, and intentions lie behind behaviours as subtle as facial expression or eye movement. The connection of theory of mind with the internal working model of social relationships may open a new area of study and lead to alterations in attachment theory.

Reception

1950s to the 1970s
The maternal deprivation hypothesis, attachment theory's precursor, was enormously controversial. Ten years after the publication of the hypothesis, Ainsworth listed nine concerns that she felt were the chief points of controversy. Ainsworth separated the three dimensions of maternal deprivation into lack of maternal care, distortion of maternal care and discontinuity of maternal care. She analysed the dozens of studies undertaken in the field and concluded that the basic assertions of the maternal deprivation hypothesis were sound although the controversy continued. As the formulation of attachment theory progressed, critics commented on empirical support for the theory and for the possible alternative explanations for results of empirical research. Wootton questioned the suggestion that early attachment history (as it would now be called) had a lifelong impact.

In 1957 found the young relationship theory in the DDR (East Germany) by an essay of James Robertson in the Zeitschrift für ärztliche Fortbildung (magazine for a medical further education) and Eva Schmidt-Kolmer carried out some journal extracts from Bowlby's essay Maternal Care and mental Health for WHO. In the following period it came to extensive comparative development psychological in the DDR at the end of the fifties. Examinations between family-bound babies and small children, day and week hayracks-as well as Institution children. The findings could do with regard to the morbidity for the family-bound children, the physical and emotional development as well as adaption disturbances at change of environment. After the construction of the Berlin Wall 1961 it didn't come to any additional publications in the DDR Relationship theory and comparative investigations with family-bound children. The previous ones Research results weren't published further and got like the relationship theory into oblivion in the DDR in the subsequent years.

In the 1970s, problems with the emphasis on attachment as a trait (a stable characteristic of an individual) rather than as a type of behaviour with important organising functions and outcomes, led some authors to consider that "attachment (as implying anything but infant-adult interaction) [may be said to have] outlived its usefulness as a developmental construct..." and that attachment behaviours were best understood in terms of their functions in the child's life. Children may achieve a given function, such as a sense of security, in many different ways and the various but functionally comparable behaviours should be categorized as related to each other. This way of thinking saw the secure base concept (the organisation of exploration of an unfamiliar situation around returns to a familiar person) as "central to the logic and coherence of attachment theory and to its status as an organizational construct." Similarly, Thompson pointed out that "other features of early parent-child relationships that develop concurrently with attachment security, including negotiating conflict and establishing cooperation, also must be considered in understanding the legacy of early attachments."

Specific disciplines

Psychoanalysis
From an early point in the development of attachment theory, there was criticism of the theory's lack of congruence with the various branches of psychoanalysis. Like other members of the British object-relations group, Bowlby rejected Melanie Klein's views that considered the infant to have certain mental capacities at birth and to continue to develop emotionally on the basis of fantasy rather than of real experiences. But Bowlby also withdrew from the object-relations approach (exemplified, for example, by Anna Freud), as he abandoned the "drive theory" assumptions in favor of a set of automatic, instinctual behaviour systems that included attachment. Bowlby's decisions left him open to criticism from well-established thinkers working on problems similar to those he addressed. Bowlby was effectively ostracized from the psychoanalytic community. More recently some psychoanalysts have sought to reconcile the two theories in the form of attachment-based psychotherapy, a therapeutic approach.

Ethology
Ethologists expressed concern about the adequacy of some of the research on which attachment theory was based, particularly the generalisation to humans from animal studies. Schur, discussing Bowlby's use of ethological concepts (pre-1960) commented that these concepts as used in attachment theory had not kept up with changes in ethology itself.

Ethologists and others writing in the 1960s and 1970s questioned the types of behaviour used as indications of attachment, and offered alternative approaches. For example, crying on separation from a familiar person was suggested as an index of attachment. Observational studies of young children in natural settings also provided behaviours that might be considered to indicate attachment; for example, staying within a predictable distance of the mother without effort on her part and picking up small objects and bringing them to the mother, but usually not other adults. Although ethological work tended to be in agreement with Bowlby, work like that just described led to the conclusion that "[w]e appear to disagree with Bowlby and Ainsworth on some of the details of the child's interactions with its mother and other people". Some ethologists pressed for further observational data, arguing that psychologists "are still writing as if there is a real entity which is 'attachment', existing over and above the observable measures."

Robert Hinde expressed concern with the use of the word "attachment" to imply that it was an intervening variable or a hypothesised internal mechanism rather than a data term. He suggested that confusion about the meaning of attachment theory terms "could lead to the 'instinct fallacy' of postulating a mechanism isomorphous with the behaviours, and then using that as an explanation for the behaviour". However, Hinde considered "attachment behaviour system" to be an appropriate term of theory language which did not offer the same problems "because it refers to postulated control systems that determine the relations between different kinds of behaviour."

Cognitive development
Bowlby's reliance on Piaget's theory of cognitive development gave rise to questions about object permanence (the ability to remember an object that is temporarily absent) and its connection to early attachment behaviours, and about the fact that the infant's ability to discriminate strangers and react to the mother's absence seems to occur some months earlier than Piaget suggested would be cognitively possible. More recently, it has been noted that the understanding of mental representation has advanced so much since Bowlby's day that present views can be far more specific than those of Bowlby's time.

Behaviourism
In 1969, Gewirtz discussed how mother and child could provide each other with positive reinforcement experiences through their mutual attention and therefore learn to stay close together; this explanation would make it unnecessary to posit innate human characteristics fostering attachment. Learning theory saw attachment as a remnant of dependency and the quality of attachment as merely a response to the caregivers cues. Behaviourists saw behaviours such as crying as a random activity that meant nothing until reinforced by a caregivers response therefore frequent responses would result in more crying. To attachment theorists, crying is an inborn attachment behaviour to which the caregiver must respond if the infant is to develop emotional security. Conscientious responses produce security which enhances autonomy and results in less crying. Ainsworth's research in Baltimore supported the attachment theorists view. In the last decade, behaviour analysts have constructed models of attachment based on the importance of contingent relationships. These behaviour analytic models have received some support from research and meta-analytic reviews.

Methodology
There has been critical discussion of conclusions drawn from clinical and observational work, and whether or not they actually support tenets of attachment theory. For example, Skuse based criticism of a basic tenet of attachment theory on the work of Anna Freud with children from Theresienstadt, who apparently developed relatively normally in spite of serious deprivation during their early years. This discussion concluded from Freud's case and from some other studies of extreme deprivation that there is an excellent prognosis for children with this background, unless there are biological or genetic risk factors. The psychoanalyst Margaret Mahler interpreted ambivalent or aggressive behaviour of toddlers toward their mothers as a normal part of development, not as evidence of poor attachment history.

Some of Bowlby's interpretations of the data reported by James Robertson were eventually rejected by the researcher, who reported data from 13 young children who were cared for in ideal circumstances during separation from their mothers. Robertson noted, "...Bowlby acknowledges that he draws mainly upon James Robertson's institutional data. But in developing his grief and mourning theory, Bowlby, without adducing non-institutional data, has generalized Robertson's concept of protest, despair and denial beyond the context from which it was derived. He asserts that these are the usual responses of young children to separation from the mother regardless of circumstance..."; however, of the 13 separated children who received good care, none showed protest and despair, but "coped with separation from the mother when cared for in conditions from which the adverse factors which complicate institutional studies were absent". In the second volume of the trilogy, Separation, published two years later, Bowlby acknowledged that Robertsons foster study had caused him to modify his views on the traumatic consequences of separation in which insufficient weight was given to the influence of skilled care from a familiar substitute.

Some authors have questioned the idea of attachment patterns, thought to be measured by techniques like the Strange Situation Protocol. Such techniques yield a taxonomy of categories considered to represent qualitative difference in attachment relationships (for example, secure attachment versus avoidant). However, a categorical model is not necessarily the best representation of individual difference in attachment. An examination of data from 1139 15-month-olds showed that variation was continuous rather than falling into natural groupings. This criticism introduces important questions for attachment typologies and the mechanisms behind apparent types, but in fact has relatively little relevance for attachment theory itself, which "neither requires nor predicts discrete patterns of attachment." As was noted above, ethologists have suggested other behavioural measures that may be of greater importance than Strange Situation behaviour.

1980s on
Following the argument made in the 1970s that attachment should not be seen as a trait (lasting characteristic of the individual), but instead should be regarded as an organising principle with varying behaviours resulting from contextual factors, later research looked at cross-cultural differences in attachment, and concluded that there should be re-evaluation of the assumption  that attachment is expressed identically in all humans. Various studies appeared to show cultural differences but a 2007 study conducted in Sapporo in Japan found attachment distributions consistent with global norms using the six-year Main & Cassidy scoring system for attachment classification.

Recent critics such as J. R. Harris, Steven Pinker and Jerome Kagan are generally concerned with the concept of infant determinism (Nature versus nurture) and stress the possible effects of later experience on personality. Building on the earlier work on temperament of Stella Chess, Kagan rejected almost every assumption on which attachment theory etiology was based, arguing that heredity was far more important than the transient effects of early environment, for example a child with an inherent difficult temperament would not illicit sensitive behavioural responses from their care giver. The debate spawned considerable research and analysis of data from the growing number of longitudinal studies. Subsequent research has not bourne out  Kagan's argument and broadly demonstrates that it is the caregivers' behaviours that form the child's attachment style although how this style is expressed may differ with temperament.

Harris and Pinker have put forward the notion that the influence of parents has been much exaggerated and that socialisation takes place primarily in peer groups, although H. Rudolph Schaffer concludes that parents and peers fulfill different functions and have distinctive roles in children's development.
Concern about attachment theory has been raised with regard to the fact that infants often have multiple relationships, within the family as well as in child care settings, and that the dyadic model characteristic of attachment theory cannot address the complexity of real-life social experiences.

See also
Attachment theory
John Bowlby
Behavior analysis of child development

Notes

References
 (page numbers refer to Pelican edition 1971)

External links
 Richard Karen. 'Becoming Attached'. The Atlantic Monthly February, 1990.
 Review of Richard Karen. Becoming Attached: First Relationships and How They Shape Our Capacity to Love.
 Rene Spitz's film "Psychogenic Disease in Infancy" (1957)

Ethology
Evolutionary biology
+
Human development
Interpersonal relationships
Philosophy of love
Psychoanalytic theory

History of attachment theory


Celtic Christianity refers to the early Medieval Christian practice that came about in 4th century Ireland. Before Christianity they practiced a religion as complex as the Romans with many gods. It grew during the 5th and 6th centuries one of the most spiritual churches in the world.

Introduction
Roman Christianity was late arriving in Ireland because the Roman armies never invaded the island. Consequently, Roman culture, and its brand of Roman Christianity, had little influence on early Irish Christianity. Because the educated class of the Celts, the Druids, had a long history of educational excellence and philosophic curiosity, they welcomed the new religion into Ireland as they did all new information.  The ancient Greeks did student exchanges with the Druids, whom they considered the other great philosophers in Europe. Perhaps the most famous Greek scholar to study under the Druids was Pythagoras.

Ireland is the one country that had no martyrs when Christianity came into its territory. This prompted the Irish Christians of later years to develop the "White Martyrdom" of monks who lived austere lives as "living martyrs." Christian worship had reached Ireland around 400 AD. Ireland at this time was still a Celtic nation, which the Roman Church called pagan. Contrary to common myth, the Irish did not abandon their Celtic culture in favor of Christianity. Rather, Christianity was woven into their culture. The Celtic cross reflects this mixture of the two. Celtic culture, unlike the very linear philosophy of Rome and Greece, was built upon a very cyclically minded philosophy, patterning itself after the seasonal cycles and life cycles they observed in their beloved natural world. The Celtic cross includes the cross to represent Christianity and the Circle to represent the Celtic world view.

Successes
Roman Christianity, like Roman culture, was a city-based culture. All of the letters of Saint Paul that made it into the official Roman canon of the New Testament were written to new churches in various Roman cities. The Latin word for Celt was Galli. Paul's letter to the Galatians was written to a Celtic settlement, uncharacteristically urban, in what is now Turkey. For most of its early history, the Roman church paid little attention to the country dwellers they called the "Paganus," which is equivalent to the contemporary "redneck" or "country bumpkin." Consequently, it was not the Roman missionaries who Christianized the vast majority of the European land mass. It was the monks from Ireland who were comfortable with the nature-loving ways of the Paganus. They traveled to mainland Europe and taught the countryfolk Celtic Christianity.

Despite Rome's later philosophic battles against it, like those at the Synod of Whitby in 664 AD, Celtic Christianity remained the dominant form of Christianity in terms of numbers of adherents for the first thousand years of the Christian era. Most modern Christians do not know this because once Rome either converted, suppressed, or killed the adherents of what they saw as a heresy. They removed all reference to Celtic Christianity's legacy from the libraries of Europe - except the Irish libraries, material being translated only since Irish Independence in the early Twentieth Century.

Myths
Legend says that Celtic Christianity in Britain was founded by St. Joseph of Arimathea; legend also says that King Arthur is buried in his ruined abbey. According to legend, Joseph was a tin merchant who was often coming and going to the tin mines of Roman Britain. Legend continues to say that he may have taken his nephew, Jesus, with him on some of these trips. Later Joseph of Arimathea becomes first keeper of the Holy Grail. Perhaps the best known myth about Celtic Christianity is that Saint Patrick brought Christianity to Ireland. Christianity was already established in Ireland by the time Patrick began his ministry.

Sources
 Dillard, John R. "The Celtic Apostolic Church - Brief History" (North Carolina, 2007).
 Cahill, Thomas "How the Irish Saved Civilization"
  Beresford Ellis, Peter CELTIC INHERITANCE, London: Constable, 1992.  (A scholarly study of Celtic Christianity and of its history in each of the Celtic lands of northwestern Europe.)

References

Christianity of the Middle Ages
Irish culture
Christian denominations

Celtic Christianity


A partially observable Markov decision process (POMDP) is a generalization of a Markov decision process (MDP). A POMDP models an agent decision process in which it is assumed that the system dynamics are determined by an MDP, but the agent cannot directly observe the underlying state. Instead, it must maintain a sensor model (the probability distribution of different observations given the underlying state) and the underlying MDP. Unlike the policy function in MDP which maps the underlying states to the actions, POMDP's policy is a mapping from the history of observations (or belief states) to the actions.

The POMDP framework is general enough to model a variety of real-world sequential decision processes. Applications include robot navigation problems, machine maintenance, and planning under uncertainty in general. The general framework of Markov decision processes with imperfect information was described by Karl Johan Åström in 1965 in the case of a discrete state space, and it was further studied in the operations research community where the acronym POMDP was coined. It was later adapted for problems in artificial intelligence and automated planning by Leslie P. Kaelbling and Michael L. Littman.

An exact solution to a POMDP yields the optimal action for each possible belief over the world states. The optimal action maximizes the expected reward (or minimizes the cost) of the agent over a possibly infinite horizon. The sequence of optimal actions is known as the optimal policy of the agent for interacting with its environment.

Definition

Formal definition
A discrete-time POMDP models the relationship between an agent and its environment. Formally, a POMDP is a 7-tuple , where
  is a set of states,
  is a set of actions,
  is a set of conditional transition probabilities between states,
  is the reward function.
  is a set of observations,
  is a set of conditional observation probabilities, and
  is the discount factor.

At each time period, the environment is in some state .  The agent takes an action , which causes the environment to transition to state  with probability . At the same time, the agent receives an observation  which depends on the new state of the environment, , and on the just taken action, , with probability  (or sometimes  depending on the sensor model). Finally, the agent receives a reward  equal to . Then the process repeats. The goal is for the agent to choose actions at each time step that maximize its expected future discounted reward: , where  is the reward earned at time . The discount factor  determines how much immediate rewards are favored over more distant rewards. When  the agent only cares about which action will yield the largest expected immediate reward; when  the agent cares about maximizing the expected sum of future rewards.

Discussion
Because the agent does not directly observe the environment's state, the agent must make decisions under uncertainty of the true environment state. However, by interacting with the environment and receiving observations, the agent may update its belief in the true state by updating the probability distribution of the current state. A consequence of this property is that the optimal behavior may often include (information gathering) actions that are taken purely because they improve the agent's estimate of the current state, thereby allowing it to make better decisions in the future.

It is instructive to compare the above definition with the definition of a Markov decision process. An MDP does not include the observation set, because the agent always knows with certainty the environment's current state. Alternatively, an MDP can be reformulated as a POMDP by setting the observation set to be equal to the set of states and defining the observation conditional probabilities to deterministically select the observation that corresponds to the true state.

Belief update

After having taken the action  and observing , an agent needs to update its belief in the state the environment may (or not) be in. Since the state is Markovian (by assumption), maintaining a belief over the states solely requires knowledge of the previous belief state, the action taken, and the current observation. The operation is denoted . Below we describe how this belief update is computed.

After reaching , the agent observes  with probability . Let  be a probability distribution over the state space .  denotes the probability that the environment is in state . Given , then after taking action  and observing ,

where  is a normalizing constant with .

Belief MDP
A Markovian belief state allows a POMDP to be formulated as a Markov decision process where every belief is a state. The resulting belief MDP will thus be defined on a continuous state space (even if the "originating" POMDP has a finite number of states: there are infinite belief states (in ) because there are an infinite number of probability distributions over the states (of )).

Formally, the belief MDP is defined as a tuple  where

  is the set of belief states over the POMDP states,
  is the same finite set of action as for the original POMDP,
  is the belief state transition function,
  is the reward function on belief states,
  is the discount factor equal to the  in the original POMDP.

Of these,  and  need to be derived from the original POMDP.  is

where  is the value derived in the previous section and

The belief MDP reward function () is the expected reward from the POMDP reward function over the belief state distribution:

.

The belief MDP is not partially observable anymore, since at any given time the agent knows its belief, and by extension the state of the belief MDP.

Policy and value function
Unlike the "originating" POMDP (where each action is available from only one state), in the corresponding Belief MDP all belief states allow all actions, since you (almost) always have some probability of believing you are in any (originating) state. As such,  specifies an action  for any belief .

Here it is assumed the objective is to maximize the expected total discounted reward over an infinite horizon. When  defines a cost, the objective becomes the minimization of the expected cost.

The expected reward for policy  starting from belief  is defined as

where  is the discount factor. The optimal policy  is obtained by optimizing the long-term reward.

where  is the initial belief.

The optimal policy, denoted by , yields the highest expected reward value for each belief state, compactly represented by the optimal value function . This value function is solution to the Bellman optimality equation:

For finite-horizon POMDPs, the optimal value function is piecewise-linear and convex. It can be represented as a finite set of vectors. In the infinite-horizon formulation, a finite vector set can approximate  arbitrarily closely, whose shape remains convex. Value iteration applies dynamic programming update to gradually improve on the value until convergence to an -optimal value function, and preserves its piecewise linearity and convexity. By improving the value, the policy is implicitly improved. Another dynamic programming technique called policy iteration explicitly represents and improves the policy instead.

Approximate POMDP solutions
In practice, POMDPs are often computationally intractable to solve exactly, so computer scientists have developed methods that approximate solutions for POMDPs.

Grid-based algorithms comprise one approximate solution technique.  In this approach, the value function is computed for a set of points in the belief space, and interpolation is used to determine the optimal action to take for other belief states that are encountered which are not in the set of grid points. More recent work makes use of sampling techniques, generalization techniques and exploitation of problem structure, and has extended POMDP solving into large domains with millions of states. For example, adaptive grids and point-based methods sample random reachable belief points to constrain the planning to relevant areas in the belief space.
Dimensionality reduction using PCA has also been explored.

Another line of approximate solution techniques for solving POMDPs relies on using (a subset of) the history of previous observations, actions and rewards up to the current time step as a pseudo-state. Usual techniques for solving MDPs based on these pseudo-states can then be used (e.g. Q-learning). Ideally the pseudo-states should contain the most important information from the whole history (to reduce bias) while being as compressed as possible (to reduce overfitting).

POMDP theory
Planning in POMDP is undecidable in general. However, some settings have been identified to be decidable (see Table 2 in, reproduced below). Different objectives have been considered. Büchi objectives are defined by Büchi automata. Reachability is an example of a Büchi condition (for instance, reaching a good state in which all robots are home). coBüchi objectives correspond to traces that do not satisfy a given Büchi condition (for instance, not reaching a bad state in which some robot died). Parity objectives are defined via parity games; they enable to define complex objectives such that reaching a good state every 10 timesteps. The objective can be satisfied:

 almost-surely, that is the probability to satisfy the objective is 1;
 positive, that is the probability to satisfy the objective is strictly greater than 0;
 quantitative, that is the probability to satisfy the objective is greater than a given threshold.

We also consider the finite memory case in which the agent is a finite-state machine, and the general case in which the agent has an infinite memory.

Applications
POMDPs can be used to model many kinds of real-world problems. Notable applications include the use of a POMDP in management of patients with ischemic heart disease, assistive technology for persons with dementia, the conservation of the critically endangered and difficult to detect Sumatran tigers and aircraft collision avoidance.

One application is a teaching case, a crying baby problem, where a parent needs to sequentially decide whether to feed the baby based on the observation of whether the baby is crying or not, which is an imperfect representation of the actual baby's state of hunger.

References

External links

 APPL, a fast point-based POMDP solver
 Finite-state Controllers using Branch-and-Bound An Exact POMDP Solver for Policies of a Bounded Size
 pomdp: Infrastructure for Partially Observable Markov Decision Processes (POMDP) an R package which includes an interface to Tony Cassandra's pomdp-solve program.
 POMDPs.jl, an interface for defining and solving MDPs and POMDPs in Julia and python with a variety of solvers.
 pyPOMDP, a (PO)MDP toolbox (simulator, solver, learner, file reader) for Python by Oliver Stollmann and Bastian Migge
 zmdp, a POMDP solver by Trey Smith

Dynamic programming
Markov processes
Stochastic control

Partially observable Markov decision process


Marc Ferrez (December 7, 1843 – January 12, 1923) was a Brazilian photographer born in Rio de Janeiro.

Ferrez's life was dedicated to the art of photography and he is considered one of the greatest photographers of his time. His production was massive, and his photographs document the consolidation of Brazil as a nation and Rio de Janeiro as a metropolis. His career was energized when he made part of Professor Charles Hartt's Geological Commission which covered the north and south of the country.

In 1865, Ferrez opened his own studio at Rua São José, in the center of Rio de Janeiro. He was made Photographo da Marinha Imperial and his work with images increased through his life. He photographed Brazil from south to north, but paid more attention to his home city, Rio de Janeiro. His masterpieces are the great albums of railway constructions and the great panoramic views of the city of Rio de Janeiro and its quick development.

Ferrez died in 1923 and left thousands of pictures and reproductions of his works.

1843 births
1923 deaths
Brazilian photographers

Marc Ferrez


The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron reactors are the most common type of nuclear reactor, and light-water reactors are the most common type of thermal-neutron reactor.

There are three varieties of light-water reactors: the pressurized water reactor (PWR), the boiling water reactor (BWR), and (most designs of) the supercritical water reactor (SCWR).

History

Early concepts and experiments
After the discoveries of fission, moderation and of the theoretical possibility of a nuclear chain reaction, early experimental results rapidly showed that natural uranium could only undergo a sustained chain reaction using graphite or heavy water as a moderator. While the world's first reactors (CP-1, X10 etc.) were successfully reaching criticality, uranium enrichment began to develop from theoretical concept to practical applications in order to meet the goal of the Manhattan Project, to build a nuclear explosive.

In May 1944, the first grams of enriched uranium ever produced reached criticality in the low power (LOPO) reactor at Los Alamos, which was used to estimate the critical mass of U235 to produce the atomic bomb. LOPO cannot be considered as the first light-water reactor because its fuel was not a solid uranium compound cladded with corrosion-resistant material, but was composed of uranyl sulfate salt dissolved in water. It is however the first aqueous homogeneous reactor and the first reactor using enriched uranium as fuel and ordinary water as a moderator.

By the end of the war, following an idea of Alvin Weinberg, natural uranium fuel elements were arranged in a lattice in ordinary water at the top of the X10 reactor to evaluate the neutron multiplication factor. The purpose of this experiment was to determine the feasibility of a nuclear reactor using light water as a moderator and coolant, and clad solid uranium as fuel. The results showed that, with a lightly enriched uranium, criticality could be reached. This experiment was the first practical step toward the light-water reactor.

After World War II and with the availability of enriched uranium, new reactor concepts became feasible. In 1946, Eugene Wigner and Alvin Weinberg proposed and developed the concept of a reactor using enriched uranium as a fuel, and light water as a moderator and coolant. This concept was proposed for a reactor whose purpose was to test the behavior of materials under neutron flux. This reactor, the Material Testing Reactor (MTR), was built in Idaho at INL and reached criticality on March 31, 1952. For the design of this reactor, experiments were necessary, so a mock-up of the MTR was built at ORNL, to assess the hydraulic performances of the primary circuit and then to test its neutronic characteristics. This MTR mock-up, later called the Low Intensity Test Reactor (LITR), reached criticality on February 4, 1950 and was the world's first light-water reactor.

Pressurized water reactors

Immediately after the end of World War II the United States Navy started a program under the direction of Captain (later Admiral) Hyman Rickover, with the goal of nuclear propulsion for ships. It developed the first pressurized water reactors in the early 1950s, and led to the successful deployment of the first nuclear submarine, the .

The Soviet Union independently developed a version of the PWR in the late 1950s, under the name of VVER. While functionally very similar to the American effort, it also has certain design distinctions from Western PWRs.

Boiling water reactor

Researcher Samuel Untermyer II led the effort to develop the BWR at the US National Reactor Testing Station (now the Idaho National Laboratory) in a series of tests called the BORAX experiments.

PIUS reactor
PIUS, standing for Process Inherent Ultimate Safety, was a Swedish design designed by ASEA-ATOM. It is a  concept for a light-water reactor system. Along with the SECURE reactor, it relied on passive measures, not requiring operator actions or external energy supplies, to provide safe operation. No units were ever built.

OPEN100
In 2020, the Energy Impact Center announced publication of an open-sourced engineering design of a pressurized water reactor capable of producing 300 MWth/100 MWe of energy called OPEN100.

Overview

The family of nuclear reactors known as light-water reactors (LWR), cooled and moderated using ordinary water, tend to be simpler and cheaper to build than other types of nuclear reactors; due to these factors, they make up the vast majority of civil nuclear reactors and naval propulsion reactors in service throughout the world as of 2009. LWRs can be subdivided into three categories – pressurized water reactors (PWRs), boiling water reactors (BWRs), and supercritical water reactors (SCWRs).  The SCWR remains hypothetical as of 2009; it is a Generation IV design that is still a light-water reactor, but it is only partially moderated by light water and exhibits certain characteristics of a fast neutron reactor.

The leaders in national experience with PWRs, offering reactors for export, are the United States (which offers the passively safe AP1000, a Westinghouse design, as well as several smaller, modular, passively safe PWRs, such as the Babcock & Wilcox MPower, and the NuScale MASLWR), the Russian Federation (offering both the VVER-1000 and the VVER-1200 for export), the Republic of France (offering the AREVA EPR for export), and Japan (offering the Mitsubishi Advanced Pressurized Water Reactor for export); in addition, both the People's Republic of China and the Republic of Korea are both noted to be rapidly ascending into the front rank of PWR-constructing nations as well, with the Chinese being engaged in a massive program of nuclear power expansion, and the Koreans currently designing and constructing their second generation of indigenous designs. The leaders in national experience with BWRs, offering reactors for export, are the United States and Japan, with the alliance of General Electric (of the US) and Hitachi (of Japan), offering both the Advanced Boiling Water Reactor (ABWR) and the Economic Simplified Boiling Water Reactor (ESBWR) for construction and export; in addition, Toshiba offers an ABWR variant for construction in Japan, as well. West Germany was also once a major player with BWRs. The other types of nuclear reactor in use for power generation are the heavy water moderated reactor, built by Canada (CANDU) and the Republic of India (AHWR), the advanced gas cooled reactor (AGCR), built by the United Kingdom, the liquid metal cooled reactor (LMFBR), built by the Russian Federation, the Republic of France, and Japan, and the graphite-moderated, water-cooled reactor (RBMK or LWGR), found exclusively within the Russian Federation and former Soviet states.

Though electricity generation capabilities are comparable between all these types of reactor, due to the aforementioned features, and the extensive experience with operations of the LWR, it is favored in the vast majority of new nuclear power plants. In addition, light-water reactors make up the vast majority of reactors that power naval nuclear-powered vessels. Four out of the five great powers with nuclear naval propulsion capacity use light-water reactors exclusively: the British Royal Navy, the Chinese People's Liberation Army Navy, the French Marine nationale, and the United States Navy. Only the Russian Federation's Navy has used a relative handful of liquid-metal cooled reactors in production vessels, specifically the Alfa class submarine, which used lead-bismuth eutectic as a reactor moderator and coolant, but the vast majority of Russian nuclear-powered boats and ships use light-water reactors exclusively. The reason for near exclusive LWR use aboard nuclear naval vessels is the level of inherent safety built into these types of reactors. Since light water is used as both a coolant and a neutron moderator in these reactors, if one of these reactors suffers damage due to military action, leading to a compromise of the reactor core's integrity, the resulting release of the light-water moderator will act to stop the nuclear reaction and shut the reactor down. This capability is known as a negative void coefficient of reactivity.

Currently offered LWRs include the following
 ABWR
 AP1000
 APR-1400
 CPR-1000
 EPR
 VVER

LWR statistics

Data from the International Atomic Energy Agency in 2009:

Reactor design
The light-water reactor produces heat by controlled nuclear fission. The nuclear reactor core is the portion of a nuclear reactor where the nuclear reactions take place. It mainly consists of nuclear fuel and control elements. The pencil-thin nuclear fuel rods, each about 12 feet (3.7 m) long, are grouped by the hundreds in bundles called fuel assemblies. Inside each fuel rod, pellets of uranium, or more commonly uranium oxide, are stacked end to end. The control elements, called control rods, are filled with pellets of substances like hafnium or cadmium that readily capture neutrons. When the control rods are lowered into the core, they absorb neutrons, which thus cannot take part in the chain reaction. On the converse, when the control rods are lifted out of the way, more neutrons strike the fissile uranium-235 or plutonium-239 nuclei in nearby fuel rods, and the chain reaction intensifies. All of this is enclosed in a water-filled steel pressure vessel, called the reactor vessel.

In the boiling water reactor, the heat generated by fission turns the water into steam, which directly drives the power-generating turbines. But in the pressurized water reactor, the heat generated by fission is transferred to a secondary loop via a heat exchanger. Steam is produced in the secondary loop, and the secondary loop drives the power-generating turbines. In either case, after flowing through the turbines, the steam turns back into water in the condenser.

The water required to cool the condenser is taken from a nearby river or ocean. It is then pumped back into the river or ocean, in warmed condition. The heat can also be dissipated via a cooling tower into the atmosphere. The United States uses LWR reactors for electric power production, in comparison to the heavy water reactors used in Canada.

Control

Control rods are usually combined into control rod assemblies — typically 20 rods for a commercial pressurized water reactor assembly — and inserted into guide tubes within a fuel element. A control rod is removed from or inserted into the central core of a nuclear reactor in order to control the number of neutrons which will split further uranium atoms. This in turn affects the thermal power of the reactor, the amount of steam generated, and hence the electricity produced. The control rods are partially removed from the core to allow a chain reaction to occur. The number of control rods inserted and the distance by which they are inserted can be varied to control the reactivity of the reactor.

Usually there are also other means of controlling reactivity. In the PWR design a soluble neutron absorber, usually boric acid, is added to the reactor coolant allowing the complete extraction of the control rods during stationary power operation ensuring an even power and flux distribution over the entire core. Operators of the BWR design use the coolant flow through the core to control reactivity by varying the speed of the reactor recirculation pumps. An increase in the coolant flow through the core improves the removal of steam bubbles, thus increasing the density of the coolant/moderator with the result of increasing power.

Coolant

The light-water reactor also uses ordinary water to keep the reactor cooled. The cooling source, light water, is circulated past the reactor core to absorb the heat that it generates.  The heat is carried away from the reactor and is then used to generate steam.  Most reactor systems employ a cooling system that is physically separate from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized-water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling-water reactor.

Many other reactors are also light-water cooled, notably the RBMK and some military plutonium-production reactors. These are not regarded as LWRs, as they are moderated by graphite, and as a result their nuclear characteristics are very different. Although the coolant flow rate in commercial PWRs is constant, it is not in nuclear reactors used on U.S. Navy ships.

Fuel

The use of ordinary water makes it necessary to do a certain amount of enrichment of the uranium fuel before the necessary criticality of the reactor can be maintained. The light-water reactor uses uranium 235 as a fuel, enriched to approximately 3 percent. Although this is its major fuel, the uranium 238 atoms also contribute to the fission process by converting to plutonium 239; about one-half of which is consumed in the reactor. Light-water reactors are generally refueled every 12 to 18 months, at which time, about 25 percent of the fuel is replaced.

The enriched UF6 is converted into uranium dioxide powder that is then processed into pellet form. The pellets are then fired in a high-temperature, sintering furnace to create hard, ceramic pellets of enriched uranium. The cylindrical pellets then undergo a grinding process to achieve a uniform pellet size. The uranium oxide is dried before inserting into the tubes to try to eliminate moisture in the ceramic fuel that can lead to corrosion and hydrogen embrittlement. The pellets are stacked, according to each nuclear core's design specifications, into tubes of corrosion-resistant metal alloy. The tubes are sealed to contain the fuel pellets: these tubes are called fuel rods.

The finished fuel rods are grouped in special fuel assemblies that are then used to build up the nuclear fuel core of a power reactor. The metal used for the tubes depends on the design of the reactor – stainless steel was used in the past, but most reactors now use a zirconium alloy. For the most common types of reactors the tubes are assembled into bundles with the tubes spaced precise distances apart. These bundles are then given a unique identification number, which enables them to be tracked from manufacture through use and into disposal.

Pressurized water reactor fuel consists of cylindrical rods put into bundles. A uranium oxide ceramic is formed into pellets and inserted into zirconium alloy tubes that are bundled together. The zirconium alloy tubes are about 1 cm in diameter, and the fuel cladding gap is filled with helium gas to improve the conduction of heat from the fuel to the cladding. There are about 179-264 fuel rods per fuel bundle and about 121 to 193 fuel bundles are loaded into a reactor core. Generally, the fuel bundles consist of fuel rods bundled 14x14 to 17x17. PWR fuel bundles are about 4 meters in length. The zirconium alloy tubes are pressurized with helium to try to minimize pellet cladding interaction which can lead to fuel rod failure over long periods.

In boiling water reactors, the fuel is similar to PWR fuel except that the bundles are "canned"; that is, there is a thin tube surrounding each bundle. This is primarily done to prevent local density variations from affecting neutronics and thermal hydraulics of the nuclear core on a global scale. In modern BWR fuel bundles, there are either 91, 92, or 96 fuel rods per assembly depending on the manufacturer. A range between 368 assemblies for the smallest and 800 assemblies for the largest U.S. BWR forms the reactor core. Each BWR fuel rod is back filled with helium to a pressure of about three atmospheres (300 kPa).

Moderator

A neutron moderator is a medium which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235. A good neutron moderator is a material full of atoms with light nuclei which do not easily absorb neutrons. The neutrons strike the nuclei and bounce off. After sufficient impacts, the velocity of the neutron will be comparable to the thermal velocities of the nuclei; this neutron is then called a thermal neutron.

The light-water reactor uses ordinary water, also called light water, as its neutron moderator. The light water absorbs too many neutrons to be used with unenriched natural uranium, and therefore uranium enrichment or nuclear reprocessing becomes necessary to operate such reactors, increasing overall costs. This differentiates it from a heavy water reactor, which uses heavy water as a neutron moderator. While ordinary water has some heavy water molecules in it, it is not enough to be important in most applications. In pressurized water reactors the coolant water is used as a moderator by letting the neutrons undergo multiple collisions with light hydrogen atoms in the water, losing speed in the process. This moderating of neutrons will happen more often when the water is denser, because more collisions will occur.

The use of water as a moderator is an important safety feature of PWRs, as any increase in temperature causes the water to expand and become less dense; thereby reducing the extent to which neutrons are slowed down and hence reducing the reactivity in the reactor. Therefore, if reactivity increases beyond normal, the reduced moderation of neutrons will cause the chain reaction to slow down, producing less heat. This property, known as the negative temperature coefficient of reactivity, makes PWRs very stable. In event of a loss-of-coolant accident, the moderator is also lost and the active fission reaction will stop. Heat is still produced after the chain reaction stops from the radioactive byproducts of fission, at about 5% of rated power. This "decay heat" will continue for 1 to 3 years after shut down, whereupon the reactor finally reaches "full cold shutdown". Decay heat, while dangerous and strong enough to melt the core, is not nearly as intense as an active fission reaction. During the post shutdown period the reactor requires cooling water to be pumped or the reactor will overheat. If the temperature exceeds 2200  °C, cooling water will break down into hydrogen and oxygen, which can form a (chemically) explosive mixture. Decay heat is a major risk factor in LWR safety record.

See also
 Nuclear power
 Heavy water reactor
 List of nuclear reactors
 Light-water reactor sustainability
 Breeder Reactor

References

External links
Light Water Reactor Sustainability (LWRS) Program

Nuclear power reactor types

Light-water reactor


The Second Ecumenical Council of the Vatican, or Vatican II, was the twenty-first Ecumenical Council of the Roman Catholic Church. An Ecumenical Council is a meeting of the bishops of the Church to discuss matters of Church doctrine and practice. Pope John XXIII started Vatican II in 1962 and it lasted until 1965, when Pope Paul VI ended it. Four future popes took part in the council's opening session: Cardinal Giovanni Battista Montini, who on succeeding Pope John XXIII took the name of Paul VI; Bishop Albino Luciani, the future Pope John Paul I; Bishop Karol Wojtyła, who became Pope John Paul II. Father Joseph Ratzinger, who was only 35 at the time, was there as a theological consultant. More than forty years later, he became Pope Benedict XVI.

Different things were discussed. These aimed at modernising the church, and opening a dialogue with other religions. Many people see these meetings as the most important event in the Catholic Church in the 20th century. They let Mass be said in different languages, instead of just Latin.

Other websites
 Documents of the council, at the Website of the Vatican

Vatican 2
Roman Catholicism
1960s

Second Vatican Council


Mount Elbrus (, ) is a peak in the western Caucasus mountains. It is in Kabardino-Balkaria and Karachay-Cherkessia, Russia, near the border of Georgia. It consists of two peaks. The western peak has a height of , the eastern peak is  high.

Mount Elbrus is an inactive volcano, with a glacier on top. The western peak still has a crater with a diameter of about . No eruptions have been recorded, but there are other signs of volcanic activity, namely hot springs in the area. There last eruption happened in the first century.

Mount Elbrus is the highest mountain in the Caucasus range, and the highest one on Russian soil. Mount Elbrus is about  taller than Mont Blanc, which is commonly seen as the highest peak in Europe. The Caucasus range is generally seen as the border between Europe and Asia. People disagree on which mountains of the Caucasus are in Europe, and which ones are in Asia. A common view is to use the watershed as the boundary line. If this definition is used, Mount Elbrus is in Europe, and its highest mountain.

Other websites
Mount Elbrus on TierraWiki.org
"Elbrus, Mount." Encyclopædia Britannica. 2006. Encyclopædia Britannica Online. 14 Nov. 2006 <http://www.britannica.com/eb/article-9032240>.
Computer generated summit panoramas North South index. There are a few discontinuities due to incomplete data. Politically the Caucasus are in Europe but topographically they are in Asia.
 NASA Earth Observatory pages on Mount Elbrus:  ,
 Mount Elbrus live webcam  (view from Mount Cheget) (the web cam is not working)
 Climbing Mount Elbrus information
 Elbrus Photos (Hundreds of large photographs of Mt. Elbrus and the vicinity)
 A trip report

References

Mountains of Russia
Volcanoes of Russia
Caucasus

Mount Elbrus


William R. (Bill) Trotter (July 15, 1943 - February 28, 2018) was an American author and historian.

Writings
Trotter's work covered a variety of genres and markets. His first published work was "Sibelius and the Tides of Taste" for High Fidelity in 1965. Lawyer Rob Newsom III invited him to write Deadly Kin, a true crime book, which was published in 1989.  A research project Trotter started while at Davidson College about the Winter War eventually became the history book A Frozen Hell, published in 1991. It was awarded the Arts and Letters Prize of the Finlandia Foundation. A trilogy of books on the American Civil War in North Carolina was published in 1991 and 1992. Winter Fire, his first novel, was published in 1993. A horror novelette, "Siren of Swanquarter", published in Deathrealm magazine, was nominated for a Bram Stoker Award in 1994. His biography of conductor Dmitri Mitropoulos was published in 1995. He wrote two guides for the Close Combat series of computer games in 1999. A pair of historical novels set in North Carolina during the Civil War, Sands of Pride and Fires of Pride, were published in 2002 and 2003, and his most recent novel, Warrener's Beastie, was published in 2006. He has also written "The Desktop General" column for PC Gamer magazine since 1988. Trotter also has spent time in Filmography as an Assistant Director for Ghost Recon 2 in 2004 and as the musical consultant for one episode of Live from Lincoln Center in 1976.

Trotter was also a classical music expert and collector, owning one of the largest collections of vinyl and CD recordings in the Southeast. He wrote on classical music for the Charlotte Observer, the High Point Enterprise, and the Greensboro News & Record, among others, and served as program annotator for Greensboro's prestigious Eastern Music Festival. He was an acknowledged expert on the works of Jean Sibelius, the subject of his novel Winter Fire, and Leopold Stokowski, whose Trotter-penned biography has gone as yet unpublished but has made the rounds of the Leopold Stokowski Society for many years.

Biography
Trotter was born in Charlotte, North Carolina. At the age of fourteen he wrote his first novel, Glorious October (unpublished) about the Hungarian revolution of 1956.
He married his second wife, pianist Elizabeth Lustig, in 1983. They had one son together and one son each from previous marriages. Trotter and Lustig published The Northstate Reader monthly tabloid from 1981 to 1984. Trotter died on February 28, 2018, in Greensboro, North Carolina, of pancreatic cancer.

Works

Novels
Winter Fire (1993)
Sands of Pride (2002)
Fires of Pride (2003)
Warrener's Beastie (2006)

History
Deadly Kin: A True Story of a Mass Family Murder (1988)
Silk Flags and Cold Steel (1988)
Bushwhackers!: The Mountains (1991)
Ironclads and Columbiads: The Coast (1991)
Frozen Hell: The Russo-Finnish Winter War of 1939/40 (1991)
Republished in 2002 as The Winter War: The Russo-Finnish War of 1939-1940
Priest of Music: The Life of Dimitri Mitropoulos (1995)

Computer guides
Word Processing by Anderson and Trotter (1974)
Ascendancy: The Official Strategy Guide (1995)
Close Combat: Inside Moves (1996)
Close Combat - A Bridge Too Far: Inside Moves (1998)

Novelettes and short stories
"The Running Back from Yuggoth" - Fantasy Book June 1985
"Bagman" - Night Cry Fall 1985
"A Pinch of Snuff" - Deathrealm Fall/Win 1990
"The Boss of the Seventh Level" - Deathrealm Spr 1992
"A Graveside chat with Diedra Cox" - Deathrealm Win 1993
"The Siren of Swanquarter" - Deathrealm Win 1993
"Big Game" - Deathrealm Fall 1996
"The Bleeding of Hauptmann Gehlen" - The Darkest Thirst, Anon, Design Image Group 1998

References

American male novelists
Writers from Charlotte, North Carolina
Writers from Greensboro, North Carolina
1943 births
2018 deaths
American male short story writers
20th-century American novelists
21st-century American novelists
American columnists
Davidson College alumni
20th-century American short story writers
21st-century American short story writers
20th-century American male writers
21st-century American male writers
Novelists from North Carolina
20th-century American non-fiction writers
21st-century American non-fiction writers
American male non-fiction writers

William R. Trotter


The Belousov–Zhabotinsky reaction (often shortened to BZR or BZ) is an example of a chemical oscillator. It is often used to illustrate a chaotic system. The BZR is made of several chemical reactions, that occur in sequence. It shows chemical oscillation, which is unusual for chemical reactions. At first it was thought to be a measurement error, or an artifact. It was thought that according to the Second law of thermodynamics, this should not occur. According to this law, a system that is in an unordered state will not assume an ordered state on its own, that is without the provision of energy. However, this is only applicable in a closed system, and does not apply to the BZ reaction.

The reactions are theoretically important because they show that chemical reactions do not have to be dominated by  equilibrium thermodynamic behavior. These reactions are far from equilibrium and remain so for a significant length of time. In this sense, they provide an interesting chemical model of nonequilibrium biological phenomena. The mathematical models of the BZ reactions themselves are of theoretical interest.

An essential aspect of the BZ reaction is called"excitability": under the influence of stimuli, patterns develop in what would otherwise be a perfectly calm medium. Some clock reactions such as Briggs–Rauscher and BZ using the tris(bipyridine)ruthenium(II) chloride as catalyst can be made to show self-organising activity through the influence of light.

Similar processes were already known in the 19th century. Wilhelm Ostwald gave a detailed account in 1899 and 1900, describing the oscillations of Chrome in Hydrochloric acid and of iron in Nitric acid. Boris Pavlovich Belousov accidentally discovered the Belousov–Zhabotinsky reaction in the 1950s. Ilya Prigogine was awarded the Nobel Prize in Chemistry in 1977. His research focused on systems which were far away from an equilibrium state, the Belousov–Zhabotinsky reaction was included. Beloussow was awarded the Lenin Prize in 1980, after his death. The Lenin prize was the highest distinction for scientific achievement in the Soviet Union.

Chemical reactions
Chemical kinetics

Belousov–Zhabotinsky reaction


In physics, moment of force (often just moment) is a measure of a force's tendency to cause a body to rotate about a specific point or axis.

In this concept the moment arm, the distance from the axis of rotation, plays an important role. The lever, pulley, gear, and most other simple machines create mechanical advantage by changing the moment arm. The SI unit for moment is the newton meter (kgm²/s² or Nm).

Formula for moment:

The Principle of Moment states that when a system is in equilibrium the sum of its CLOCKWISE MOMENTS equals the sum of its ANTICLOCKWISE MOMENTS.

Some examples where moments (turning effect) are applied involve levers, like seesaws, opening and closing doors, nutcrackers, can openers, and crowbars.

A lever is a simple machine in which one force called the effort is used to overcome another force called the load.

In physics, a moment is a combination of a physical quantity and a distance.

History of moment

The principle of moments is derived from Archimedes' discovery of the operating principle of the lever. In the lever one applies a force, in his day most often human muscle, to an arm, a beam of some sort. Archimedes noted that the amount of force applied to the object, the moment of force, is defined as M = rF, where F is the applied force, and r is the distance from the applied force to object.

Physical quantity

Moment (physics)


The Roseland Peninsula, or just Roseland, is a district of west Cornwall in the United Kingdom. Roseland is in the south of the county and contains the town of St Mawes and villages such as St Just in Roseland and Gerrans. It is a peninsula, separated from the rest of Cornwall by the River Fal (on the east is the English Channel).

There is some disagreement about where the peninsula  begins and some include the village of Tregony in Roseland and others do not.

Geography of Cornwall
Peninsulas of the United Kingdom

Roseland Peninsula


Clint Eastwood (born Robert Brammer) is a Jamaican reggae deejay, who recorded as a solo artist in the late 1970s and early 1980s before teaming up with UK deejay General Saint as the duo Clint Eastwood & General Saint.

Biography
The younger brother of Trinity, Brammer took the trend of adopting the names of characters from Spaghetti Westerns as stage names a step further by recording and performing under the name of one of the genre's most successful actors, Clint Eastwood. Eastwood recorded three albums in 1978 - African Youth and Step It In a Zion for producer Bunny Lee, and Death In The Arena for Channel One. Further albums followed in 1979 and 1980, including Sex Education for Greensleeves Records, Eastwood one of a group of deejays who led the move from 'cultural' chants to dancehall chat and 'slackness'. 1981 saw the release of a live album recorded with Dillinger and the start of a partnership with General Saint. The duo's first release, "Tribute to General Echo" remembered the recently killed slack deejay, and they would later hit the UK chart with their version of "Stop That Train". Both of the duo's albums made the top 5 of the UK Independent Chart.

Albums
African Youth (1978) Third World/Gorgon
Death In The Arena (1978) Cha Cha
Step It In a Zion (1978) Live & Love
Jah Lights Shining (1979) Jamaica Sound
Love & Happiness (1979) Burning Vibrations
Clint Eastwood (Jamaica Sun) (1980) Amo
Sex Education (1980) Greensleeves
Live at London (1981) Vista (Dillinger & Clint Eastwood)
Two Bad D.J. (1981) Greensleeves (Clint Eastwood & General Saint)
Stop That Train (1983) Greensleeves (Clint Eastwood & General Saint)
BBC Radio 1 In Concert (199?) Windsong (Clint Eastwood & General Saint)
The Best of Clint Eastwood (1984) Culture Press
The Real Clint Eastwood (199?) Culture Press/Lagoon

References

External links
Clint Eastwood at Roots Archives
[ AllMusic biography]

Jamaican reggae musicians
Year of birth missing (living people)
Living people
Cultural depictions of Clint Eastwood
Greensleeves Records artists

Clint Eastwood (musician)


Miguel A. Torres (born 1941) is a Spanish winemaker, author and businessman.  He is President and Managing Director of Bodegas Torres, and is a member of the fourth generation of this family business. He also manages the company's vineyards in Chile and collaborates with his sister Marimar Torres in California.

Early life
In 1957, he started his degree in Chemical Sciences at the University of Barcelona, two years later transferring to the University of Dijon (Bourgogne), where he specialised in oenology and viticulture.

In 1962, he joined the family business, of which he is currently President and Managing Director. Five years after joining the company he married Waltraud Maczassek, a painter and fine arts graduate, who from the very first has collaborated with the company in sales management on the German market.
In 1982-1983 he extended his viticulture and oenology studies at the University of Montpellier (France), having taken a sabbatical year.

Writings on wines
Miguel A. Torres has published various books about the world of wine. His first book, Viñas y Vinos, (Vineyards and Wines) is currently in its fourth edition in Spanish, revised and updated by Plaza y Janes in 1993 and translated into Catalan, French, English, German, Norwegian, Finnish and Japanese. This first effort was followed by Vino español, un incierto futuro (Spanish Wine, an Uncertain Future) (1979); Manual de los vinos de Cataluña (Manual of Catalan Wines) (1982); Los vinos de España (The Wines of Spain) (1983); Guía Folio de los Vinos de España (Guide sheet to Spanish Wines) (1985); and Els Vins del Penedès (Wines of the Penedès) (1987). Likewise he also edited Enciclopedia del Vino (Encyclopaedia of Wine) for the editorial Orbis.

Bibliography
Viñas y vinos (Vineyards and Wines), Plaza & Janés Editores, 1996.
Els vins del Penedès (Wines of the Penedès), Nuevo Arte Thor, 1987.
Los vinos de España (The Wines of Spain), Ediciones Castell, 1983.
Vino español: un incierto futuro (Spanish Wine, an Uncertain Future), Editorial Blume, 1979.
Manual de los vinos de Cataluña (Manual of Catalan Wines) (1982)
Guía Folio de los vinos de España (Guide Sheet to Spanish Wines) (1985)

Awards
In 1996 the government of Chile awarded him the Bernardo O'Higgins Order, Grand Officier, in acknowledgement for services towards the improvement of relations between Chile and Spain, as well as contribution to vinicultural development in Chile.
In 2002 the magazine Decanter selected him as "Decanter Man of the Year 2002".
In 2005 he received the Personality of the Year award by the magazine Wine International.

References

Further reading

Salvat Dictionary of Wine. Mauricio Wiesenthal. Salvat editores, 20001.

External links
Bodegas Torres website (in English, Catalan, Spanish and Swedish)

1941 births
Living people
Spanish businesspeople
Businesspeople from Catalonia
Spanish winemakers

Miguel A. Torres


Chandi (Sanskrit: , ) or Chandika or Ran-Chandi () is the supreme Goddess o Devi Mahatmya (Sanskrit: Devīmāhātmyam, देवीमाहात्म्यम्) kent as Chamunda or Durga an aw as mentioned in Durga Saptashati.

Etymologie
 or  is the name bi which the Supreme Goddess is referred tae in Devi Mahatmya. Accordin tae Coburn, " is "the violent an impetuous ane". In the licht o the primacy o this designation o the goddess, it is strikin that the wird  haes virtually nae earlier history in Sanskrit. Thare are nae instances o its
occurrence in the Vedic leeteratur we hae surveyed. The epics are similarly barren: neither the Ramayana nor the Mahabharata gie evidence o the epithet, awtho in ane o the hymns insertit in the latter  an  are applee'd tae the deity thay praised."

The designation o Chandi or Chandika is used twenty-nine times in the Devi Mahatmya, which is agreed bi mony scholars tae hae haed oreeginatit in Bengal, the primar seat o the Shakta or Goddess tradeetion an tantric sadhana syne auncient times. It is the maist common epithet uised for the Goddess. In Devi Mahatmya, Chandi, Chandika, Ambika an Durga hae been uised synonymously.

Goddess Chandi is associatit wi the 9 lettered Navakshari Mantra. It is cried Navarna Mantra or Navavarna Mantra an aw. It is ane o the principal mantras in Shakti Worship apairt frae the Sri Vidhya Mantras. It customar tae chant this mantra when chantin the Devi Mahatmya.

Legends
The oreegin o the goddess is gien in the seicont chapter o Devi Mahatmya. Thare are various mair stories regardin the incarnation o Devi Chandi  .

She is considered as Kaatyayini (Durga) itsel, who haed killed Mahishasura as well as Shumbha Nishumbha   "The great Goddess wis born frae the energies o the male divinities when the gods became impotent in the lang-drawn-oot battle wi the asuras. Aw the energies o the Gods became unitit an became supernova, throwin oot flames in aw directions. Then that unique licht, pervadin the Three Worlds wi its lustre, combined intae ane, an became a female form."

"The Devi projectit an owerwhelmin omnipotence. The three-eyed goddess wis adorned wi the crescent muin. Her multiple airms held auspicious weapons an emblems, jewels an ornaments, garments an utensils, garlands an rosaries o beads, aw affered bi the gods. Wi her gowden bouk blazin wi the splendour o a thoosan suns, seatit on her lion
vehicle, Chandi is ane o the maist spectacular o aw personifications o Cosmic energy."

In ither scriptures, Chandi is portrayed as "assistin" Kali in her battle wi demon Raktabija. While Kali drank Raktabija's bluid, which creatit new demons frae his awn bluid on fawin on the grund; Chandi wad destroy the airmies o demons creatit frae his bluid an feenally killed Raktabija hissel. In Skanda Purana, this story is retauld an anither story o Chandi killin demons Chanda an Manda is addit.

Accordin tae Markandeya Purana, when Indra an the ither gods war praying tae Goddess Mahasaraswati, tae gie them relief frae the atrocities o Demons Shumbha an Nishumbha, Goddess Parvati (Maha Gauri) happened tae hear thair prayers. Oot o curiosity, She asked them that whom are thay addressing tae in thair prayers. Frae the body o the Goddess, a female came intae existence an that wis Devi Chandika. Chandika wis an aa addressed as Ambika. Her actual name is believed tae be Chandraghanta, ane o the nine forms o Durga i.e. ane o the Navdurgas. She haes a third ee, throu the eyebrows o which, Goddess Chamunda haed manifested tae kill demons Chand an Mund; an later, the great demon Rakthbeej too, wis killed bi Kali. Chandika haed slain demons Dumralochan, Shumbha an Nishumbha.
Accordin tae Matsya Purana an as shawn in ane o the best kent Indian TV serials Om Namah Shivaya, Goddess Parvati haed done penance tae please Lord Brahma. And as a reward for the penance, She requested for the recovery o her fair complexion, as She haed acome dark bi Shiva's magic. Brahma gae the desired boon an the darkness o the Goddess got separated frae her an teuk the form o anither Goddess. That Goddess wis considered as the dochter o Parvati an as she haed taken birth frae the Kaushik (dark cell) o her mither, she wis named Kaushiki . Kaushiki haed incarnated for the killin o the demons Shumbha an Nishumbha, who haed got a boon that thay wad be killed bi anjanmi (unborn) girl. And as Kaushiki haed nae taken ony biological birth frae her mither, She wis the Ajanma girl accordin tae the boon; an an aa she haed supernatural powers, bein the dochter o Goddess Shakti i.e. Parvati. Parvati, bein a concerned mither, teuk pairt in the war against the demons. Henceforth, Parvati incarnated as Chandika, Chamunda an Kalika tae kill the demons Dumralochan, Chanda & Munda an Rakthbeej respectively. Thir demons war sent bi Shumbha an Nishumbha, who war finally killed bi Kaushiki in her divine form.

It is believit that the extremely white skined bonnie goddess Kaushiki came intae existence frae Maha Gauri Parvati an aw. Due tae this, Parvati turned dark. Goddesses Lakshmi an Saraswati appeared thare an bestoued thair pouers tae Parvati. Hence, Parvati got transformit intae Goddess Chandika, who firstly killed the demons that creatit havoc aw ower the yird. Then, She assisted Kaushiki in the war against Shumbh-Nishumbh. Chandika confrontit the demons Chand an Mund sent bi Shumbh an Nisumbh, during which Goddess Chamunda manefisted frae the eyebrous o her third ee, who killed Chand an Mund. Later, Chandika killed Nishumbh an then while battlin the great demon Rakthbeej, Chandika transformit in Mahakali tae kill the demon bi drinkin his bluid. Hence, Chandika is considered as Parvati, Kali an Chamunda an is considered as the mither o Kaushiki an aw.

Chandi Homa (Havan)

Chandi Homa is ane o the maist popular Homas in Hindu releegion. It is performit athort Indie durin various festivals, especially durin the Navaratri. Chandi Homa is performit bi recitin verses frae the Durga Sapthasathi an afferin oblations intae the sacrificial fire. It coud be accompaniet bi the Navakshari Mantra an aw. Kumari Puja, Suvasini Puja form a pairt o the ritual an aw.

Iconografie

The dhyana sloka precedin the Middle episode o Devi Mahatmya the iconographic details are gien. The Goddess is describit as aichteen airmit bearin string o beads, battle axe, mace, arrae, thunnerbolt, lotus, bow, watter-pot, cudgel, lance, swuird, shield, conch, bell, wine-cup, trident, noose an the discus (sudarsana). She haes a complexion o coral an is seatit on a lotus.

In some temples the images o Maha Kali, Maha Lakshmi, an Maha Saraswati are kept separately. The Goddess is portrayed as fower airmit in mony temples.

Temples
Temples devotit tae Chandi are locatit in mony places includin the follaein:

 Gandaki Chandi, Gandaki near Pokhara, Nepal. (Shakti Peethas)
 Mangal Chandika, Ujjaani, Wast Bengal. (Shakti Peethas)
 Saptashrangi Temple, Vani, (Maharashtra). (Ashtadasa Bhuja Mahalakshmi)
 Mahalaxmi Temple, Mumbai (Maharashtra). (Three separate images).
 Hemadpanthi Chandika Devi Mandir, Katol (Maharashtra).
 Vaishno Devi temple, Khatra, Jammu an Kashmir. (Three Pindas (stanes)).
 Katak Chandi Temple, Cuttack, Odisha. (Fower airmit).
 Mangal Chandi temple, Guwahati, Assam.
 Mangal Chandi temple, Chandithala, Kolkata.
 Chandi Devi Temple, Neel Parvat, Haridwar
 Chandi Mandir, Chandigarh. The ceety o Chandigarh (lit. "fort of Chandi") derives its name frae this temple.
 Chandi Mata Mandir Machail, Kishtwar,J&K Sphire glen Paddar
 Chandi Mata Mandir Chinnot, Badherwah,J&K
 Anandavalli Temple, Panchetti, Gummudipoondi, Chennai - The Durga Sapthasathi yantra haes been instawed bi Sage Agastya in this temple.
Hedavde Mahalaxmi Mata, Maharashtra
 Chandika Devi Mandir, Malgund, (Ratnagiri) (Maharashtra) *Short drive fraethe famous Ganpatipule Mandir.
 Maa MangalChandi mandir (sagarbhanga, Durgapur)

In fowklear o Bengal
Chandi is one of the most popular folk deities in Bengal, an a nummer o poems an leeterar componitions in Bengali cried Chandi Mangala Kavyas wur written frae 13t century tae early 19t century. Thir haed the effect o mergin the local fowk an tribal goddesses wi mainstream
Hinduism. The Mangal kavyas aften associate Chandi wi goddess Kali or Kalika. an recognise her as a consort o Shiva an mither o Ganesha an Kartikeya, which are characteristics o goddesses lik Parvati an Durga. The concept of Chandi as the supreme Goddess underwent a change an aw. The worship of the goddess became heterogeneous in nature.

Chandi is associated with good fortune as well as disaster. Her auspicious forms like Mangal Chandi, Sankat Mangal Chandi, Rana Chandi bestow joy, riches, childer, guid huntin an victory in battles while ither forms lik Olai Chandi cur diseases lik cholera, plague an cattle diseases.

Thir are amaist aw village an tribal goddesses wi the name o the veelage or tribe bein addit ontae the name Chandi. The most important o thir goddesses is Mangol Chandi who is worshippit in the entire state an in Assam an aw. Here the wird "Mangol" means auspicious or benign.

Notes

References
Coburn, Thomas B., "Devī Māhātmya, The Crystallization of the Goddess Tradition", South Asia Beuks, 2002. (ISBN 81-208-0557-7)
Manna, Sibendu, Mother Goddess, , Punthi Pustak, Calcutta, Indie, 1993. (ISBN 81-85094-60-8)
Mookerjee, Ajit, Kali, The Feminine Force, Destiny Beuks, Rochester, Vermont, 1988, (ISBN 0-89281-212-5)
Sankaranarayanan, S., Glory o the Divine Mother (Devī Māhātmyam), Nesma Beuks, Indie, 2001. (ISBN 81-87936-00-2)
McDaniel, Juin, Offering Flowers, Feeding Skulls: Popular Goddess Worship in West , Published 2004, Oxford Varsity Press - US, 368 pages, ISBN 0-19-516790-2
McDaniel, Juin, Making Virtuous Daughters and Wives: An Introduction to Women's Brata Rituals in Benegal Folk Religion, Published 2002, SUNY Press, 144 pages, ISBN 0-7914-5565-3
 Wilkins, William Joseph, Hindu Mythology, Vedic and Puranic, Published 2004, Kessinger Publishing, 428 pages, ISBN 0-7661-8881-7 (First edition: Published 1882; Thacker, Spink & co.)

Mither goddesses
Hindu goddesses
Virgin goddesses

Chandi


Coronel () is a Chilean city and commune, located in the Concepción Province of the eighth region of Biobío.

Geography
The city of Coronel is located in a sandy platform that goes from the mouth of the Biobío River to the Arauco Gulf bay, a muddy landscape, full of forests, typical of the region.

This muddy, forested landscape enclosed by high mountains was what the first Spanish conquistadors and settlers found when arriving. Vegetation and forests covered most of the area except very close to the coast. This type of landscape is characteristic of the province.

The total area of the commune is . Aside from its western coast along the Pacific Ocean, the commune is surrounded by other communes of the Concepción Province: San Pedro de la Paz to the north, Hualqui to the north and east, and Lota and Santa Juana to the south.

Santa María Island also forms part of the city, which is represented there by a municipal delegate.

Climate
The climate of Coronel is temperate Mediterranean, common to the Chilean Coast Range, with moderate temperature variations.  As Coronel is situated west of the mountain range, it generally receives winds out of the west and northwest, and increased precipitation due to orographic lift.  Its proximity to the Pacific influences its annual temperature variations. The average temperature in summer is  and  in winter.

History
Like all territory to the south of Biobío River, this area was populated by the Mapuche. Historically, Spaniards called them as Araucaníans (araucanos) and their coastal territory as Araucanía.

This territory is a part of the Kingdom of Araucania and Patagonia, an unrecognised state established on November 19, 1861.

The indigenous population of Coronel Bay was located into a war zone called Butanmapu de la costa.  From the descriptions made by the Spaniards, it is probable that before the Spaniards' colonization, half of the Mapuche population lived in this region. Also, the population density of the tribes was evenly distributed on both east and west sides of the Cordillera de Nahuelbuta

The city of Lota was an early coal mining settlement in the area. The mine was composed of "Chiflones" 1, 2, 3, 4, Pique Santa Maria, and Pique Arenas Blancas. This was the last mine closed, because of a grisu gas explosion where 21 miners died. This mine was the deepest in South America, at .

The World War I naval Battle of Coronel between ships of the United Kingdom and Germany was fought on 1 November 1914 off the coast of Coronel.

The city was the seat of Lautaro Department, later known as the Coronel Department.

In March 2013, an investigation was started after thousands of sea animals washed ashore.

Demographics
According to the 2002 census of the National Statistics Institute, Coronel spans an area of  and has 95,528 inhabitants (46,766 men and 48,762 women). Of these, 91,469 (95.8%) lived in urban areas and 4,059 (4.2%) in rural areas. Between the 1992 and 2002 censuses, the population grew by 14.5% (12,102 persons). The demonym for a man from Coronel is Coronelino and Coronelina for a woman.

Administration
As a commune, Coronel is a third-level administrative division of Chile administered by a communal council, headed by an alcalde who is directly elected every four years. The 2012-2016 alcalde is Leonidas Romero. The communal council has the following members:
 José Suazo Muñoz
 Francisco Merino Olivares
 Edmundo Salas Norambuena
 Francisco Reyes Aguayo
 Daniel Rosales Salgado
 Hugo Monsalves Obreque
 Carmen Madinagoitia Chamorro
 Osvaldo Campos Torres

Within the electoral divisions of Chile, Coronel is represented in the Chamber of Deputies
by Marcelo Chávez (PDC) and Clemira Pacheco (PS) as part of the 45th electoral district, (together with Tomé, Penco, Florida, Hualqui and Santa Juana). The commune is represented in the Senate by Alejandro Navarro Brain (MAS) and Jacqueline Van Rysselberghe Herrera (UDI) as part of the 12th senatorial constituency (Biobío-Cordillera).

References

External links
  Municipality of Coronel

Communes of Chile
Port cities in Chile
Populated places established in 1851
Populated places in Concepción Province
1851 establishments in Chile

Coronel, Chile