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"\n\n\n \n\n\n\n\n'''Autism''' is a neurodevelopmental disorder characterized by impaired social interaction, impaired verbal and non-verbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child's life. These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress. The diagnostic criteria require that symptoms become apparent in early childhood, typically before age three.\n\n\nAutism is caused by a combination of genetic and environmental factors. Some cases are strongly associated with certain infections during pregnancy including rubella and use of alcohol or cocaine. Controversies surround other proposed environmental causes; for example the vaccine hypotheses, which have been disproven. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood. In the DSM V, autism is included within the autism spectrum (ASDs), as is Asperger syndrome, which lacks delays in cognitive development and language, and pervasive developmental disorder, not otherwise specified (commonly abbreviated as PDD-NOS), which was diagnosed when the full set of criteria for autism or Asperger syndrome were not met.\n\n\nEarly speech or behavioral interventions can help children with autism gain self-care, social, and communication skills. Although there is no known cure, there have been reported cases of children who recovered. Not many children with autism live independently after reaching adulthood, though some become successful. An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.\n\n\nGlobally, autism is estimated to affect 24.8 million people as of 2015. As of 2010, the number of people affected is estimated at about 1–2 per 1,000 worldwide. It occurs four to five times more often in boys than girls. About 1.5% of children in the United States (one in 68) are diagnosed with ASD , a 30% increase from one in 88 in 2012. The rate of autism among adults aged 18 years and over in the United Kingdom is 1.1%. The number of people diagnosed has been increasing dramatically since the 1980s, partly due to changes in diagnostic practice; the question of whether actual rates have increased is unresolved.\n",
"Autism spectrum disorder video\nAutism is a highly variable neurodevelopmental disorder that first appears during infancy or childhood, and generally follows a steady course without remission. People with autism may be severely impaired in some respects but normal, or even superior, in others. Overt symptoms gradually begin after the age of six months, become established by age two or three years, and tend to continue through adulthood, although often in more muted form. It is distinguished not by a single symptom, but by a characteristic triad of symptoms: impairments in social interaction; impairments in communication; and restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis. Autism's individual symptoms occur in the general population and appear not to associate highly, without a sharp line separating pathologically severe from common traits.\n\n===Social development===\nSocial deficits distinguish autism and the related autism spectrum disorders (ASD; see Classification) from other developmental disorders. People with autism have social impairments and often lack the intuition about others that many people take for granted. Noted autistic Temple Grandin described her inability to understand the social communication of neurotypicals, or people with normal neural development, as leaving her feeling \"like an anthropologist on Mars\".\n\nUnusual social development becomes apparent early in childhood. Autistic infants show less attention to social stimuli, smile and look at others less often, and respond less to their own name. Autistic toddlers differ more strikingly from social norms; for example, they have less eye contact and turn-taking, and do not have the ability to use simple movements to express themselves, such as pointing at things. Three- to five-year-old children with autism are less likely to exhibit social understanding, approach others spontaneously, imitate and respond to emotions, communicate nonverbally, and take turns with others. However, they do form attachments to their primary caregivers. Most children with autism display moderately less attachment security than neurotypical children, although this difference disappears in children with higher mental development or less severe ASD. Older children and adults with ASD perform worse on tests of face and emotion recognition although this may be partly due to a lower ability to define a person's own emotions.\n\nChildren with high-functioning autism suffer from more intense and frequent loneliness compared to non-autistic peers, despite the common belief that children with autism prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they feel. Functional friendships, such as those resulting in invitations to parties, may affect the quality of life more deeply.\n\nThere are many anecdotal reports, but few systematic studies, of aggression and violence in individuals with ASD. The limited data suggest that, in children with intellectual disability, autism is associated with aggression, destruction of property, and tantrums.\n\n===Communication===\nAbout a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs. Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and vocal patterns that are not synchronized with the caregiver. In the second and third years, children with autism have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Children with autism are less likely to make requests or share experiences, and are more likely to simply repeat others' words (echolalia) or reverse pronouns. Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD: for example, they may look at a pointing hand instead of the pointed-at object, and they consistently fail to point at objects in order to comment on or share an experience. Children with autism may have difficulty with imaginative play and with developing symbols into language.\n\nIn a pair of studies, high-functioning children with autism aged 8–15 performed equally well as, and adults better than, individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative language, comprehension and inference. As people are often sized up initially from their basic language skills, these studies suggest that people speaking to autistic individuals are more likely to overestimate what their audience comprehends.\n\n===Repetitive behavior===\nA young boy with autism who has arranged his toys in a row\nAutistic individuals can display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows.\n\n* Stereotyped behaviors: Repetitive movements, such as hand flapping, head rolling, or body rocking.\n* Compulsive behaviors: Time-consuming behaviors intended to reduce anxiety that an individual feels compelled to perform repeatedly or according to rigid rules, such as placing objects in a specific order, checking things, or hand washing.\n* Sameness: Resistance to change; for example, insisting that the furniture not be moved or refusing to be interrupted.\n* Ritualistic behavior: Unvarying pattern of daily activities, such as an unchanging menu or a dressing ritual. This is closely associated with sameness and an independent validation has suggested combining the two factors.\n* Restricted interests: Interests or fixations that are abnormal in theme or intensity of focus, such as preoccupation with a single television program, toy, or game.\n* Self-injury: Behaviors such as eye-poking, skin-picking, hand-biting and head-banging.\n\nNo single repetitive or self-injurious behavior seems to be specific to autism, but autism appears to have an elevated pattern of occurrence and severity of these behaviors.\n\n===Other symptoms===\nAutistic individuals may have symptoms that are independent of the diagnosis, but that can affect the individual or the family.\nAn estimated 0.5% to 10% of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious autistic savants. Many individuals with ASD show superior skills in perception and attention, relative to the general population. Sensory abnormalities are found in over 90% of those with autism, and are considered core features by some, although there is no good evidence that sensory symptoms differentiate autism from other developmental disorders. Differences are greater for under-responsivity (for example, walking into things) than for over-responsivity (for example, distress from loud noises) or for sensation seeking (for example, rhythmic movements). An estimated 60%–80% of autistic people have motor signs that include poor muscle tone, poor motor planning, and toe walking; deficits in motor coordination are pervasive across ASD and are greater in autism proper.\n\nUnusual eating behavior occurs in about three-quarters of children with ASD, to the extent that it was formerly a diagnostic indicator. Selectivity is the most common problem, although eating rituals and food refusal also occur; this does not appear to result in malnutrition. Although some children with autism also have gastrointestinal symptoms, there is a lack of published rigorous data to support the theory that children with autism have more or different gastrointestinal symptoms than usual; studies report conflicting results, and the relationship between gastrointestinal problems and ASD is unclear.\n\nParents of children with ASD have higher levels of stress. Siblings of children with ASD report greater admiration of and less conflict with the affected sibling than siblings of unaffected children and were similar to siblings of children with Down syndrome in these aspects of the sibling relationship. However, they reported lower levels of closeness and intimacy than siblings of children with Down syndrome; siblings of individuals with ASD have greater risk of negative well-being and poorer sibling relationships as adults.\n",
"\n\nIt has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism's characteristic triad of symptoms. However, there is increasing suspicion that autism is instead a complex disorder whose core aspects have distinct causes that often co-occur.\n\nDeletion (1), duplication (2) and inversion (3) are all chromosome abnormalities that have been implicated in autism.\nAutism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations with major effects, or by rare multigene interactions of common genetic variants. Complexity arises due to interactions among multiple genes, the environment, and epigenetic factors which do not change DNA sequencing but are heritable and influence gene expression. Many genes have been associated with autism through sequencing the genomes of affected individuals and their parents.\n\nStudies of twins suggest that heritability is 0.7 for autism and as high as 0.9 for ASD, and siblings of those with autism are about 25 times more likely to be autistic than the general population. However, most of the mutations that increase autism risk have not been identified. Typically, autism cannot be traced to a Mendelian (single-gene) mutation or to a single chromosome abnormality, and none of the genetic syndromes associated with ASDs have been shown to selectively cause ASD. Numerous candidate genes have been located, with only small effects attributable to any particular gene. Most loci individually explain less than 1% of cases of autism. The large number of autistic individuals with unaffected family members may result from spontaneous structural variation — such as deletions, duplications or inversions in genetic material during meiosis. Hence, a substantial fraction of autism cases may be traceable to genetic causes that are highly heritable but not inherited: that is, the mutation that causes the autism is not present in the parental genome.\n\nSeveral lines of evidence point to synaptic dysfunction as a cause of autism. Some rare mutations may lead to autism by disrupting some synaptic pathways, such as those involved with cell adhesion. Gene replacement studies in mice suggest that autistic symptoms are closely related to later developmental steps that depend on activity in synapses and on activity-dependent changes. All known teratogens (agents that cause birth defects) related to the risk of autism appear to act during the first eight weeks from conception, and though this does not exclude the possibility that autism can be initiated or affected later, there is strong evidence that autism arises very early in development.\n\nExposure to air pollution during pregnancy, especially heavy metals and particulates, may increase the risk of autism. Environmental factors that have been claimed without evidence to contribute to or exacerbate autism include certain foods, infectious diseases, solvents, diesel exhaust, PCBs, phthalates and phenols used in plastic products, pesticides, brominated flame retardants, alcohol, smoking, illicit drugs, vaccines, and prenatal stress. No evidence has been found for these claims, and some such as the MMR vaccine have been completely disproven.\n\nParents may first become aware of autistic symptoms in their child around the time of a routine vaccination. This has led to unsupported theories blaming vaccine \"overload\", a vaccine preservative, or the MMR vaccine for causing autism. The latter theory was supported by a litigation-funded study that has since been shown to have been \"an elaborate fraud\". Although these theories lack convincing scientific evidence and are biologically implausible, parental concern about a potential vaccine link with autism has led to lower rates of childhood immunizations, outbreaks of previously controlled childhood diseases in some countries, and the preventable deaths of several children.\n",
"Autism's symptoms result from maturation-related changes in various systems of the brain. How autism occurs is not well understood. Its mechanism can be divided into two areas: the pathophysiology of brain structures and processes associated with autism, and the neuropsychological linkages between brain structures and behaviors. The behaviors appear to have multiple pathophysiologies.\n\n===Pathophysiology===\nAutism affects the amygdala, cerebellum, and many other parts of the brain.\nUnlike many other brain disorders, such as Parkinson's, autism does not have a clear unifying mechanism at either the molecular, cellular, or systems level; it is not known whether autism is a few disorders caused by mutations converging on a few common molecular pathways, or is (like intellectual disability) a large set of disorders with diverse mechanisms. Autism appears to result from developmental factors that affect many or all functional brain systems, and to disturb the timing of brain development more than the final product. Neuroanatomical studies and the associations with teratogens strongly suggest that autism's mechanism includes alteration of brain development soon after conception. This anomaly appears to start a cascade of pathological events in the brain that are significantly influenced by environmental factors. Just after birth, the brains of children with autism tend to grow faster than usual, followed by normal or relatively slower growth in childhood. It is not known whether early overgrowth occurs in all children with autism. It seems to be most prominent in brain areas underlying the development of higher cognitive specialization. Hypotheses for the cellular and molecular bases of pathological early overgrowth include the following:\n* An excess of neurons that causes local overconnectivity in key brain regions.\n* Disturbed neuronal migration during early gestation.\n* Unbalanced excitatory–inhibitory networks.\n* Abnormal formation of synapses and dendritic spines, for example, by modulation of the neurexin–neuroligin cell-adhesion system, or by poorly regulated synthesis of synaptic proteins. Disrupted synaptic development may also contribute to epilepsy, which may explain why the two conditions are associated.\n\nThe immune system is thought to play an important role in autism. Children with autism have been found by researchers to have inflammation of both the peripheral and central immune systems as indicated by increased levels of pro-inflammatory cytokines and significant activation of microglia. Biomarkers of abnormal immune function have also been associated with increased impairments in behaviors that are characteristic of the core features of autism such as deficits in social interactions and communication. Interactions between the immune system and the nervous system begin early during the embryonic stage of life, and successful neurodevelopment depends on a balanced immune response. It is thought that activation of a pregnant mother's immune system such as from environmental toxicants or infection can contribute to causing autism through causing a disruption of brain development. This is supported by recent studies that have found that infection during pregnancy is associated with an increased risk of autism.\n\nThe relationship of neurochemicals to autism is not well understood; several have been investigated, with the most evidence for the role of serotonin and of genetic differences in its transport. The role of group I metabotropic glutamate receptors (mGluR) in the pathogenesis of fragile X syndrome, the most common identified genetic cause of autism, has led to interest in the possible implications for future autism research into this pathway. Some data suggests neuronal overgrowth potentially related to an increase in several growth hormones or to impaired regulation of growth factor receptors. Also, some inborn errors of metabolism are associated with autism, but probably account for less than 5% of cases.\n\nThe mirror neuron system (MNS) theory of autism hypothesizes that distortion in the development of the MNS interferes with imitation and leads to autism's core features of social impairment and communication difficulties. The MNS operates when an animal performs an action or observes another animal perform the same action. The MNS may contribute to an individual's understanding of other people by enabling the modeling of their behavior via embodied simulation of their actions, intentions, and emotions. Several studies have tested this hypothesis by demonstrating structural abnormalities in MNS regions of individuals with ASD, delay in the activation in the core circuit for imitation in individuals with Asperger syndrome, and a correlation between reduced MNS activity and severity of the syndrome in children with ASD. However, individuals with autism also have abnormal brain activation in many circuits outside the MNS and the MNS theory does not explain the normal performance of children with autism on imitation tasks that involve a goal or object.\n\nAutistic individuals tend to use different areas of the brain (yellow) for a movement task compared to a control group (blue).\nASD-related patterns of low function and aberrant activation in the brain differ depending on whether the brain is doing social or nonsocial tasks.\nIn autism there is evidence for reduced functional connectivity of the default network, a large-scale brain network involved in social and emotional processing, with intact connectivity of the task-positive network, used in sustained attention and goal-directed thinking. In people with autism the two networks are not negatively correlated in time, suggesting an imbalance in toggling between the two networks, possibly reflecting a disturbance of self-referential thought.\n\nThe underconnectivity theory of autism hypothesizes that autism is marked by underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes. Evidence for this theory has been found in functional neuroimaging studies on autistic individuals and by a brainwave study that suggested that adults with ASD have local overconnectivity in the cortex and weak functional connections between the frontal lobe and the rest of the cortex. Other evidence suggests the underconnectivity is mainly within each hemisphere of the cortex and that autism is a disorder of the association cortex.\n\nFrom studies based on event-related potentials, transient changes to the brain's electrical activity in response to stimuli, there is considerable evidence for differences in autistic individuals with respect to attention, orientation to auditory and visual stimuli, novelty detection, language and face processing, and information storage; several studies have found a preference for nonsocial stimuli. For example, magnetoencephalography studies have found evidence in children with autism of delayed responses in the brain's processing of auditory signals.\n\nIn the genetic area, relations have been found between autism and schizophrenia based on duplications and deletions of chromosomes; research showed that schizophrenia and autism are significantly more common in combination with 1q21.1 deletion syndrome. Research on autism/schizophrenia relations for chromosome 15 (15q13.3), chromosome 16 (16p13.1) and chromosome 17 (17p12) are inconclusive.\n\nFunctional connectivity studies have found both hypo- and hyper-connectivity in brains of people with autism. Hypo-connectivity seems to dominate, especially for interhemispheric and cortico-cortical functional connectivity.\n\n===Neuropsychology===\nTwo major categories of cognitive theories have been proposed about the links between autistic brains and behavior.\n\nThe first category focuses on deficits in social cognition. Simon Baron-Cohen's empathizing–systemizing theory postulates that autistic individuals can systemize—that is, they can develop internal rules of operation to handle events inside the brain—but are less effective at empathizing by handling events generated by other agents. An extension, the extreme male brain theory, hypothesizes that autism is an extreme case of the male brain, defined psychometrically as individuals in whom systemizing is better than empathizing. These theories are somewhat related to Baron-Cohen's earlier theory of mind approach, which hypothesizes that autistic behavior arises from an inability to ascribe mental states to oneself and others. The theory of mind hypothesis is supported by the atypical responses of children with autism to the Sally–Anne test for reasoning about others' motivations, and the mirror neuron system theory of autism described in ''Pathophysiology'' maps well to the hypothesis. However, most studies have found no evidence of impairment in autistic individuals' ability to understand other people's basic intentions or goals; instead, data suggests that impairments are found in understanding more complex social emotions or in considering others' viewpoints.\n\nThe second category focuses on nonsocial or general processing: the executive functions such as working memory, planning, inhibition. In his review, Kenworthy states that \"the claim of executive dysfunction as a causal factor in autism is controversial\", however, \"it is clear that executive dysfunction plays a role in the social and cognitive deficits observed in individuals with autism\". Tests of core executive processes such as eye movement tasks indicate improvement from late childhood to adolescence, but performance never reaches typical adult levels. A strength of the theory is predicting stereotyped behavior and narrow interests; two weaknesses are that executive function is hard to measure and that executive function deficits have not been found in young children with autism.\n\nWeak central coherence theory hypothesizes that a limited ability to see the big picture underlies the central disturbance in autism. One strength of this theory is predicting special talents and peaks in performance in autistic people. A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and perceptual operations in autistic individuals. These theories map well from the underconnectivity theory of autism.\n\nNeither category is satisfactory on its own; social cognition theories poorly address autism's rigid and repetitive behaviors, while the nonsocial theories have difficulty explaining social impairment and communication difficulties. A combined theory based on multiple deficits may prove to be more useful.\n",
"Diagnosis is based on behavior, not cause or mechanism. Under the DSM-5, autism is characterized by persistent deficits in social communication and interaction across multiple contexts, as well as restricted, repetitive patterns of behavior, interests, or activities. These deficits are present in early childhood, typically before age three, and lead to clinically significant functional impairment. Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with unusual objects. The disturbance must not be better accounted for by Rett syndrome, intellectual disability or global developmental delay. ICD-10 uses essentially the same definition.\n\nSeveral diagnostic instruments are available. Two are commonly used in autism research: the Autism Diagnostic Interview-Revised (ADI-R) is a semistructured parent interview, and the Autism Diagnostic Observation Schedule (ADOS) uses observation and interaction with the child. The Childhood Autism Rating Scale (CARS) is used widely in clinical environments to assess severity of autism based on observation of children. The Diagnostic interview for social and communication disorders (DISCO) may also be used.\n\nA pediatrician commonly performs a preliminary investigation by taking developmental history and physically examining the child. If warranted, diagnosis and evaluations are conducted with help from ASD specialists, observing and assessing cognitive, communication, family, and other factors using standardized tools, and taking into account any associated medical conditions. A pediatric neuropsychologist is often asked to assess behavior and cognitive skills, both to aid diagnosis and to help recommend educational interventions. A differential diagnosis for ASD at this stage might also consider intellectual disability, hearing impairment, and a specific language impairment such as Landau–Kleffner syndrome. The presence of autism can make it harder to diagnose coexisting psychiatric disorders such as depression.\n\nClinical genetics evaluations are often done once ASD is diagnosed, particularly when other symptoms already suggest a genetic cause. Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes, consensus guidelines in the US and UK are limited to high-resolution chromosome and fragile X testing. A genotype-first model of diagnosis has been proposed, which would routinely assess the genome's copy number variations. As new genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of autism's genetics. Metabolic and neuroimaging tests are sometimes helpful, but are not routine.\n\nASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life: for example, a one-year-old who meets diagnostic criteria for ASD is less likely than a three-year-old to continue to do so a few years later. In the UK the National Autism Plan for Children recommends at most 30 weeks from first concern to completed diagnosis and assessment, though few cases are handled that quickly in practice. Although the symptoms of autism and ASD begin early in childhood, they are sometimes missed; years later, adults may seek diagnoses to help them or their friends and family understand themselves, to help their employers make adjustments, or in some locations to claim disability living allowances or other benefits.\n\nUnderdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported ASD cases is likely due to changes in diagnostic practices. The increasing popularity of drug treatment options and the expansion of benefits has given providers incentives to diagnose ASD, resulting in some overdiagnosis of children with uncertain symptoms. Conversely, the cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis. It is particularly hard to diagnose autism among the visually impaired, partly because some of its diagnostic criteria depend on vision, and partly because autistic symptoms overlap with those of common blindness syndromes or blindisms.\n\n===Classification===\nAutism is one of the five pervasive developmental disorders (PDD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior. These symptoms do not imply sickness, fragility, or emotional disturbance.\n\nOf the five PDD forms, Asperger syndrome is closest to autism in signs and likely causes; Rett syndrome and childhood disintegrative disorder share several signs with autism, but may have unrelated causes; PDD not otherwise specified (PDD-NOS; also called ''atypical autism'') is diagnosed when the criteria are not met for a more specific disorder. Unlike with autism, people with Asperger syndrome have no substantial delay in language development. The terminology of autism can be bewildering, with autism, Asperger syndrome and PDD-NOS often called the ''autism spectrum disorders'' (ASD) or sometimes the ''autistic disorders'', whereas autism itself is often called ''autistic disorder'', ''childhood autism'', or ''infantile autism''. In this article, ''autism'' refers to the classic autistic disorder; in clinical practice, though, ''autism'', ''ASD'', and ''PDD'' are often used interchangeably. ASD, in turn, is a subset of the broader autism phenotype, which describes individuals who may not have ASD but do have autistic-like traits, such as avoiding eye contact.\n\nThe manifestations of autism cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, developmentally disabled, and locked into hand flapping and rocking—to high functioning individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication. Because the behavior spectrum is continuous, boundaries between diagnostic categories are necessarily somewhat arbitrary. Sometimes the syndrome is divided into low-, medium- or high-functioning autism (LFA, MFA, and HFA), based on IQ thresholds, or on how much support the individual requires in daily life; these subdivisions are not standardized and are controversial. Autism can also be divided into syndromal and non-syndromal autism; the syndromal autism is associated with severe or profound intellectual disability or a congenital syndrome with physical symptoms, such as tuberous sclerosis. Although individuals with Asperger syndrome tend to perform better cognitively than those with autism, the extent of the overlap between Asperger syndrome, HFA, and non-syndromal autism is unclear.\n\nSome studies have reported diagnoses of autism in children due to a loss of language or social skills, as opposed to a failure to make progress, typically from 15 to 30 months of age. The validity of this distinction remains controversial; it is possible that regressive autism is a specific subtype, or that there is a continuum of behaviors between autism with and without regression.\n\nResearch into causes has been hampered by the inability to identify biologically meaningful subgroups within the autistic population and by the traditional boundaries between the disciplines of psychiatry, psychology, neurology and pediatrics. Newer technologies such as fMRI and diffusion tensor imaging can help identify biologically relevant phenotypes (observable traits) that can be viewed on brain scans, to help further neurogenetic studies of autism; one example is lowered activity in the fusiform face area of the brain, which is associated with impaired perception of people versus objects. It has been proposed to classify autism using genetics as well as behavior.\n",
"About half of parents of children with ASD notice their child's unusual behaviors by age 18 months, and about four-fifths notice by age 24 months. According to an article failure to meet any of the following milestones \"is an absolute indication to proceed with further evaluations. Delay in referral for such testing may delay early diagnosis and treatment and affect the long-term outcome\".\n* No babbling by 12 months.\n* No gesturing (pointing, waving, etc.) by 12 months.\n* No single words by 16 months.\n* No two-word (spontaneous, not just echolalic) phrases by 24 months.\n* Any loss of any language or social skills, at any age.\n\nThe United States Preventive Services Task Force in 2016 found it was unclear if screening was beneficial or harmful among children in whom there is no concerns. The Japanese practice is to screen all children for ASD at 18 and 24 months, using autism-specific formal screening tests. In contrast, in the UK, children whose families or doctors recognize possible signs of autism are screened. It is not known which approach is more effective. Screening tools include the Modified Checklist for Autism in Toddlers (M-CHAT), the Early Screening of Autistic Traits Questionnaire, and the First Year Inventory; initial data on M-CHAT and its predecessor, the Checklist for Autism in Toddlers (CHAT), on children aged 18–30 months suggests that it is best used in a clinical setting and that it has low sensitivity (many false-negatives) but good specificity (few false-positives). It may be more accurate to precede these tests with a broadband screener that does not distinguish ASD from other developmental disorders. Screening tools designed for one culture's norms for behaviors like eye contact may be inappropriate for a different culture. Although genetic screening for autism is generally still impractical, it can be considered in some cases, such as children with neurological symptoms and dysmorphic features.\n",
"Infection with rubella during pregnancy causes fewer than 1% of cases of autism; vaccination against rubella can prevent many of those cases.\n",
"\nA three-year-old with autism points to fish in an aquarium, as part of an experiment on the effect of intensive shared-attention training on language development.\nThe main goals when treating children with autism are to lessen associated deficits and family distress, and to increase quality of life and functional independence. In general, higher IQs are correlated with greater responsiveness to treatment and improved treatment outcomes. No single treatment is best and treatment is typically tailored to the child's needs. Families and the educational system are the main resources for treatment. Studies of interventions have methodological problems that prevent definitive conclusions about efficacy, however the development of evidence-based interventions has advanced in recent years. Although many psychosocial interventions have some positive evidence, suggesting that some form of treatment is preferable to no treatment, the methodological quality of systematic reviews of these studies has generally been poor, their clinical results are mostly tentative, and there is little evidence for the relative effectiveness of treatment options. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills, and often improve functioning and decrease symptom severity and maladaptive behaviors; claims that intervention by around age three years is crucial are not substantiated. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy. Among these approaches, interventions either treat autistic features comprehensively, or focalize treatment on a specific area of deficit. There is some evidence that early intensive behavioral intervention (EIBI), an early intervention model based on ABA for 20 to 40 hours a week for multiple years, is an effective treatment for some children with ASD. Two theoretical frameworks outlined for early childhood intervention include applied behavioral analysis (ABA) and developmental social pragmatic models (DSP). One interventional strategy utilizes a parent training model, which teaches parents how to implement various ABA and DSP techniques, allowing for parents to disseminate interventions themselves. Various DSP programs have been developed to explicitly deliver intervention systems through at-home parent implementation. Despite the recent development of parent training models, these interventions have demonstrated effectiveness in numerous studies, being evaluated as a probable efficacious mode of treatment.\n\n===Education===\nEducational interventions can be effective to varying degrees in most children: intensive ABA treatment has demonstrated effectiveness in enhancing global functioning in preschool children and is well-established for improving intellectual performance of young children. Similarly, teacher-implemented intervention that utilizes an ABA combined with a developmental social pragmatic approach has been found to be a well-established treatment in improving social-communication skills in young children, although there is less evidence in its treatment of global symptoms. Neuropsychological reports are often poorly communicated to educators, resulting in a gap between what a report recommends and what education is provided. It is not known whether treatment programs for children lead to significant improvements after the children grow up, and the limited research on the effectiveness of adult residential programs shows mixed results. The appropriateness of including children with varying severity of autism spectrum disorders in the general education population is a subject of current debate among educators and researchers.\n\n===Medication===\nMany medications are used to treat ASD symptoms that interfere with integrating a child into home or school when behavioral treatment fails. More than half of US children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, and antipsychotics. Antipsychotics, such as risperidone and aripiprazole, have been found to be useful for treating irritability, repetitive behavior, and sleeplessness that often occurs with autism, however their side effects must be weighed against their potential benefits, and people with autism may respond atypically. There is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD. No known medication relieves autism's core symptoms of social and communication impairments. Experiments in mice have reversed or reduced some symptoms related to autism by replacing or modulating gene function, suggesting the possibility of targeting therapies to specific rare mutations known to cause autism.\n\n===Alternative medicine===\nAlthough many alternative therapies and interventions are available, few are supported by scientific studies. Treatment approaches have little empirical support in quality-of-life contexts, and many programs focus on success measures that lack predictive validity and real-world relevance. Scientific evidence appears to matter less to service providers than program marketing, training availability, and parent requests. Some alternative treatments may place the child at risk. A 2008 study found that compared to their peers, autistic boys have significantly thinner bones if on casein-free diets; in 2005, botched chelation therapy killed a five-year-old child with autism. There has been early research looking at hyperbaric treatments in children with autism.\n\nAlthough popularly used as an alternative treatment for people with autism, there is no good evidence that a gluten-free diet is of benefit. In the subset of people who have gluten sensitivity there is limited evidence that suggests that a gluten free diet may improve some autistic behaviors.\n\n===Cost===\nTreatment is expensive; indirect costs are more so. For someone born in 2000, a US study estimated an average lifetime cost of $ (net present value in dollars, inflation-adjusted from 2003 estimate), with about 10% medical care, 30% extra education and other care, and 60% lost economic productivity. Publicly supported programs are often inadequate or inappropriate for a given child, and unreimbursed out-of-pocket medical or therapy expenses are associated with likelihood of family financial problems; one 2008 US study found a 14% average loss of annual income in families of children with ASD, and a related study found that ASD is associated with higher probability that child care problems will greatly affect parental employment. US states increasingly require private health insurance to cover autism services, shifting costs from publicly funded education programs to privately funded health insurance. After childhood, key treatment issues include residential care, job training and placement, sexuality, social skills, and estate planning.\n",
"\nThe emergence of the autism rights movement has served as an attempt to encourage people to be more tolerant of those with autism. Through this movement, people hope to cause others to think of autism as a difference instead of a disease. Proponents of this movement wish to seek \"acceptance, not cures.\" There have also been many worldwide events promoting autism awareness such as World Autism Awareness Day, Light It Up Blue, Autism Sunday, Autistic Pride Day, Autreat, and others. There have also been many organizations dedicated to increasing the awareness of autism and the effects that autism has on someone's life. These organizations include Autism Speaks, Autism National Committee, Autism Society of America, and many others. Social-science scholars have had an increased focused on studying those with autism in hopes to learn more about \"autism as a culture, transcultural comparisons... and research on social movements.\" Media has had an influence on how the public perceives those with autism. ''Rain Man'', a film that won 4 Oscars including Best Picture, depicts a character with autism who has incredible talents and abilities. While many autistics don't have these special abilities, there are some autistic individuals who have been successful in their fields.\n",
"There is no known cure. Children recover occasionally, so that they lose their diagnosis of ASD; this occurs sometimes after intensive treatment and sometimes not. It is not known how often recovery happens; reported rates in unselected samples of children with ASD have ranged from 3% to 25%. Most children with autism acquire language by age five or younger, though a few have developed communication skills in later years. Most children with autism lack social support, meaningful relationships, future employment opportunities or self-determination. Although core difficulties tend to persist, symptoms often become less severe with age.\n\nFew high-quality studies address long-term prognosis. Some adults show modest improvement in communication skills, but a few decline; no study has focused on autism after midlife. Acquiring language before age six, having an IQ above 50, and having a marketable skill all predict better outcomes; independent living is unlikely with severe autism. Most people with autism face significant obstacles in transitioning to adulthood.\n",
"\nReports of autism cases per 1,000 children grew dramatically in the US from 1996 to 2007. It is unknown how much, if any, growth came from changes in rates of autism.\n\nMost recent reviews tend to estimate a prevalence of 1–2 per 1,000 for autism and close to 6 per 1,000 for ASD, and 11 per 1,000 children in the United States for ASD as of 2008; because of inadequate data, these numbers may underestimate ASD's true rate. Globally, autism affects an estimated 24.8 million people as of 2015, while Asperger syndrome affects a further 37.2 million. In 2012, the NHS estimated that the overall prevalence of autism among adults aged 18 years and over in the UK was 1.1%. Rates of PDD-NOS's has been estimated at 3.7 per 1,000, Asperger syndrome at roughly 0.6 per 1,000, and childhood disintegrative disorder at 0.02 per 1,000. CDC's most recent estimate is that 1 out of every 68 children, or 14.7 per 1,000, has an ASD as of 2010.\n\nThe number of reported cases of autism increased dramatically in the 1990s and early 2000s. This increase is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness, though unidentified environmental risk factors cannot be ruled out. The available evidence does not rule out the possibility that autism's true prevalence has increased; a real increase would suggest directing more attention and funding toward changing environmental factors instead of continuing to focus on genetics.\n\nBoys are at higher risk for ASD than girls. The sex ratio averages 4.3:1 and is greatly modified by cognitive impairment: it may be close to 2:1 with intellectual disability and more than 5.5:1 without. Several theories about the higher prevalence in males have been investigated, but the cause of the difference is unconfirmed; one theory is that females are underdiagnosed.\n\nAlthough the evidence does not implicate any single pregnancy-related risk factor as a cause of autism, the risk of autism is associated with advanced age in either parent, and with diabetes, bleeding, and use of psychiatric drugs in the mother during pregnancy. The risk is greater with older fathers than with older mothers; two potential explanations are the known increase in mutation burden in older sperm, and the hypothesis that men marry later if they carry genetic liability and show some signs of autism. Most professionals believe that race, ethnicity, and socioeconomic background do not affect the occurrence of autism.\n\nSeveral other conditions are common in children with autism. They include:\n* '''Genetic disorders'''. About 10–15% of autism cases have an identifiable Mendelian (single-gene) condition, chromosome abnormality, or other genetic syndrome, and ASD is associated with several genetic disorders.\n* '''Intellectual disability'''. The percentage of autistic individuals who also meet criteria for intellectual disability has been reported as anywhere from 25% to 70%, a wide variation illustrating the difficulty of assessing autistic intelligence. In comparison, for PDD-NOS the association with intellectual disability is much weaker, and by definition, the diagnosis of Asperger's excludes intellectual disability.\n* '''Anxiety disorders''' are common among children with ASD; there are no firm data, but studies have reported prevalences ranging from 11% to 84%. Many anxiety disorders have symptoms that are better explained by ASD itself, or are hard to distinguish from ASD's symptoms.\n* '''Epilepsy''', with variations in risk of epilepsy due to age, cognitive level, and type of language disorder.\n* Several '''metabolic defects''', such as phenylketonuria, are associated with autistic symptoms.\n* '''Minor physical anomalies''' are significantly increased in the autistic population.\n* '''Preempted diagnoses'''. Although the DSM-IV rules out concurrent diagnosis of many other conditions along with autism, the full criteria for Attention deficit hyperactivity disorder (ADHD), Tourette syndrome, and other of these conditions are often present and these comorbid diagnoses are increasingly accepted.\n* '''Sleep problems''' affect about two-thirds of individuals with ASD at some point in childhood. These most commonly include symptoms of insomnia such as difficulty in falling asleep, frequent nocturnal awakenings, and early morning awakenings. Sleep problems are associated with difficult behaviors and family stress, and are often a focus of clinical attention over and above the primary ASD diagnosis.\n",
"\nLeo Kanner introduced the label ''early infantile autism'' in 1943.\nA few examples of autistic symptoms and treatments were described long before autism was named. The ''Table Talk'' of Martin Luther, compiled by his notetaker, Mathesius, contains the story of a 12-year-old boy who may have been severely autistic. Luther reportedly thought the boy was a soulless mass of flesh possessed by the devil, and suggested that he be suffocated, although a later critic has cast doubt on the veracity of this report. The earliest well-documented case of autism is that of Hugh Blair of Borgue, as detailed in a 1747 court case in which his brother successfully petitioned to annul Blair's marriage to gain Blair's inheritance. The Wild Boy of Aveyron, a feral child caught in 1798, showed several signs of autism; the medical student Jean Itard treated him with a behavioral program designed to help him form social attachments and to induce speech via imitation.\n\nThe New Latin word ''autismus'' (English translation ''autism'') was coined by the Swiss psychiatrist Eugen Bleuler in 1910 as he was defining symptoms of schizophrenia. He derived it from the Greek word ''autós'' (αὐτός, meaning \"self\"), and used it to mean morbid self-admiration, referring to \"autistic withdrawal of the patient to his fantasies, against which any influence from outside becomes an intolerable disturbance\".\n\nThe word ''autism'' first took its modern sense in 1938 when Hans Asperger of the Vienna University Hospital adopted Bleuler's terminology ''autistic psychopaths'' in a lecture in German about child psychology. Asperger was investigating an ASD now known as Asperger syndrome, though for various reasons it was not widely recognized as a separate diagnosis until 1981. Leo Kanner of the Johns Hopkins Hospital first used ''autism'' in its modern sense in English when he introduced the label ''early infantile autism'' in a 1943 report of 11 children with striking behavioral similarities. Almost all the characteristics described in Kanner's first paper on the subject, notably \"autistic aloneness\" and \"insistence on sameness\", are still regarded as typical of the autistic spectrum of disorders. It is not known whether Kanner derived the term independently of Asperger.\n\nDonald Triplett was the first person diagnosed with autism. He was diagnosed by Leo Kanner after being first examined in 1938, and was labeled as \"case 1\". Triplett was noted for his savant abilities, particularly being able to name musical notes played on a piano and to mentally multiply numbers. His father, Oliver, described him as socially withdrawn but interested in number patterns, music notes, letters of the alphabet, and U.S. president pictures. By the age of 2, he had the ability to recite the 23rd Psalm and memorized 25 questions and answers from the Presbyterian catechism. He was also interested in creating musical chords.\n\nKanner's reuse of ''autism'' led to decades of confused terminology like ''infantile schizophrenia'', and child psychiatry's focus on maternal deprivation led to misconceptions of autism as an infant's response to \"refrigerator mothers\". Starting in the late 1960s autism was established as a separate syndrome. As late as the mid-1970s there was little evidence of a genetic role in autism; while in 2007 it was believed to be one of the most heritable psychiatric conditions. Although the rise of parent organizations and the destigmatization of childhood ASD have affected how ASD is viewed, parents continue to feel social stigma in situations where their child's autistic behavior is perceived negatively, and many primary care physicians and medical specialists express some beliefs consistent with outdated autism research.\n\nIt took until 1980 for the DSM-III to differentiate autism from childhood schizophrenia. In 1987, the DSM-III-R provided a checklist for diagnosing autism. In May 2013, the DSM-5 was released, updating the classification for pervasive developmental disorders. The grouping of disorders, including PDD-NOS, Autism, Asperger Syndrome, Rett Syndrome, and CDD, has been removed and replaced with the general term of Autism Spectrum Disorders. The two categories that exist are impaired social communication and/or interaction, and restricted and/or repetitive behaviors.\n\nThe Internet has helped autistic individuals bypass nonverbal cues and emotional sharing that they find so hard to deal with, and has given them a way to form online communities and work remotely. Sociological and cultural aspects of autism have developed: some in the community seek a cure, while others believe that autism is simply another way of being.\n",
"* \n",
"\n",
"\n\n\n* \n\n\n\n\n\n\n\n\n\n\n\n\n\n"
] | [
"Introduction",
"Characteristics",
"Causes",
"Mechanism",
"Diagnosis",
"Screening",
"Prevention",
"Management",
"Society and culture",
"Prognosis",
"Epidemiology",
"History",
" See also ",
"References",
"External links"
] | Autism |
[
"\n\nPercentage of diffusely reflected sunlight in relation to various surface conditions\n\n'''Albedo''' () is a measure for reflectance or optical brightness (Latin ''albedo,'' \"whiteness\") of a surface. It is dimensionless and measured on a scale from zero (corresponding to a black body that absorbs all incident radiation) to one (corresponding to a white body that reflects all incident radiation).\n\nSurface albedo is defined as the ratio of irradiance reflected to the irradiance received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location and time (see Position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly or annual averages.\n\nUnless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is often given for the spectrum in which most solar energy reaches the surface (approximately between 0.3 and 3 μm). This spectrum includes visible light (0.39-0.7 μm), which explains why surfaces with a low albedo appear dark (e.g., trees absorb most radiation), whereas surfaces with a high albedo appear bright (e.g., snow reflects most radiation).\n\nAlbedo is an important concept in climatology, astronomy, and environmental management (e.g., as part of the Leadership in Energy and Environmental Design (LEED) program for sustainable rating of buildings). The average albedo of the Earth at the top of the atmosphere, its ''planetary albedo'', is 30 to 35% because of cloud cover, but widely varies locally across the surface because of different geological and environmental features.\n\nThe term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work ''Photometria''.\n",
"{| class=\"wikitable\" style=\"float:right; margin:10px\"\n+ Sample albedos\n\n Surface\n Typicalalbedo\n\n Fresh asphalt \n 0.04\n\nOpen ocean\n0.06\n\n Worn asphalt \n 0.12\n\n Conifer forest(Summer) \n 0.08, 0.09 to 0.15\n\n Deciduous trees \n 0.15 to 0.18\n\n Bare soil \n 0.17\n\n Green grass \n 0.25\n\n Desert sand \n 0.40\n\n New concrete \n 0.55\n\n Ocean ice\n 0.5–0.7\n\n Fresh snow \n 0.80–0.90\n\nAny albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body. When seen from a distance, the ocean surface has a low albedo, as do most forests, whereas desert areas have some of the highest albedos among landforms. Most land areas are in an albedo range of 0.1 to 0.4. The average albedo of Earth is about 0.3. This is far higher than for the ocean primarily because of the contribution of clouds.\n\n2003–2004 mean annual clear-sky and total-sky albedo\nEarth's surface albedo is regularly estimated via Earth observation satellite sensors such as NASA's MODIS instruments on board the Terra and Aqua satellites, and the CERES instrument on the Suomi NPP and JPSS. As the amount of reflected radiation is only measured for a single direction by satellite, not all directions, a mathematical model is used to translate a sample set of satellite reflectance measurements into estimates of directional-hemispherical reflectance and bi-hemispherical reflectance (e.g.,). These calculations are based on the bidirectional reflectance distribution function (BRDF), which describes how the reflectance of a given surface depends on the view angle of the observer and the solar angle. Thereby, the BRDF allows to translate observations of reflectance into albedo.\n\nEarth's average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C. If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 °C. If only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about 0 °C. In contrast, if the entire Earth was covered by water — a so-called aquaplanet — the average temperature on the planet would rise to almost 27 °C.\n\n===White-sky and black-sky albedo===\nFor land surfaces, it has been shown that the albedo at a particular solar zenith angle ''θ''''i'' can be approximated by the proportionate sum of two terms: the directional-hemispherical reflectance at that solar zenith angle, , and the bi-hemispherical reflectance, , with being the proportion of direct radiation from a given solar angle, and being the proportion of diffuse illumination.\n\nHence, the actual albedo (also called blue-sky albedo) can then be given as:\n\n:\n\nDirectional-hemispherical reflectance is sometimes referred to as black-sky albedo and bi-hemispherical reflectance as white-sky albedo. These terms are important because they allow the albedo to be calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface.\n",
"\nThe albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. The study of albedos, their dependence on wavelength, lighting angle (\"phase angle\"), and variation in time comprises a major part of the astronomical field of photometry. For small and far objects that cannot be resolved by telescopes, much of what we know comes from the study of their albedos. For example, the absolute albedo can indicate the surface ice content of outer Solar System objects, the variation of albedo with phase angle gives information about regolith properties, whereas unusually high radar albedo is indicative of high metal content in asteroids.\n\nEnceladus, a moon of Saturn, has one of the highest known albedos of any body in the Solar System, with 99% of EM radiation reflected. Another notable high-albedo body is Eris, with an albedo of 0.96. Many small objects in the outer Solar System and asteroid belt have low albedos down to about 0.05. A typical comet nucleus has an albedo of 0.04. Such a dark surface is thought to be indicative of a primitive and heavily space weathered surface containing some organic compounds.\n\nThe overall albedo of the Moon is measured to be around 0.136, but it is strongly directional and non-Lambertian, displaying also a strong opposition effect. Although such reflectance properties are different from those of any terrestrial terrains, they are typical of the regolith surfaces of airless Solar System bodies.\n\nTwo common albedos that are used in astronomy are the (V-band) geometric albedo (measuring brightness when illumination comes from directly behind the observer) and the Bond albedo (measuring total proportion of electromagnetic energy reflected). Their values can differ significantly, which is a common source of confusion.\n\nIn detailed studies, the directional reflectance properties of astronomical bodies are often expressed in terms of the five Hapke parameters which semi-empirically describe the variation of albedo with phase angle, including a characterization of the opposition effect of regolith surfaces.\n\nThe correlation between astronomical (geometric) albedo, absolute magnitude and diameter is:\n,\n\nwhere is the astronomical albedo, is the diameter in kilometers, and is the absolute magnitude.\n",
"\n===Illumination===\nAlthough the albedo–temperature effect is best known in colder, whiter regions on Earth, the maximum albedo is actually found in the tropics where year-round illumination is greater. The maximum is additionally in the northern hemisphere, varying between three and twelve degrees north. The minima are found in the subtropical regions of the northern and southern hemispheres, beyond which albedo increases without respect to illumination.\n\n===Insolation effects ===\nThe intensity of albedo temperature effects depend on the amount of albedo and the level of local insolation (solar irradiance); high albedo areas in the arctic and antarctic regions are cold due to low insolation, where areas such as the Sahara Desert, which also have a relatively high albedo, will be hotter due to high insolation. Tropical and sub-tropical rainforest areas have low albedo, and are much hotter than their temperate forest counterparts, which have lower insolation. Because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes.\n\nArctic regions notably release more heat back into space than what they absorb, effectively cooling the Earth. This has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being water or ground which is darker color) and reflects less heat back into space. This feedback loop results in a reduced albedo effect.\n\n===Climate and weather===\nAlbedo affects climate by determining how much radiation a planet absorbs. The uneven heating of Earth from albedo variations between land, ice, or ocean surfaces can drive weather.\n\n===Albedo–temperature feedback===\nWhen an area's albedo changes due to snowfall, a snow–temperature feedback results. A layer of snowfall increases local albedo, reflecting away sunlight, leading to local cooling. In principle, if no outside temperature change affects this area (e.g., a warm air mass), the raised albedo and lower temperature would maintain the current snow and invite further snowfall, deepening the snow–temperature feedback. However, because local weather is dynamic due to the change of seasons, eventually warm air masses and a more direct angle of sunlight (higher insolation) cause melting. When the melted area reveals surfaces with lower albedo, such as grass or soil, the effect is reversed: the darkening surface lowers albedo, increasing local temperatures, which induces more melting and thus reducing the albedo further, resulting in still more heating.\n\n===Snow===\nSnow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow. Over Antarctica they average a little more than 0.8. If a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack (the ice–albedo positive feedback). Cryoconite, powdery windblown dust containing soot, sometimes reduces albedo on glaciers and ice sheets.\nHence, small errors in albedo can lead to large errors in energy estimates, which is why it is important to measure the albedo of snow-covered areas through remote sensing techniques rather than applying a single value over broad regions.\n\n===Small-scale effects===\nAlbedo works on a smaller scale, too. In sunlight, dark clothes absorb more heat and light-coloured clothes reflect it better, thus allowing some control over body temperature by exploiting the albedo effect of the colour of external clothing.\n\n=== Solar photovoltaic effects ===\nAlbedo can affect the electrical energy output of solar photovoltaic devices. For example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si)-based compared to traditional spectral-integrated albedo predictions. Research showed impacts of over 10%. More recently, the analysis was extended to the effects of spectral bias due to the specular reflectivity of 22 commonly occurring surface materials (both human-made and natural) and analyzes the albedo effects on the performance of seven photovoltaic materials covering three common photovoltaic system topologies: industrial (solar farms), commercial flat rooftops and residential pitched-roof applications.\n\n===Trees===\nBecause forests generally have a low albedo, (the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis), some scientists have suggested that greater heat absorption by trees could offset some of the carbon benefits of afforestation (or offset the negative climate impacts of deforestation). In the case of evergreen forests with seasonal snow cover albedo reduction may be great enough for deforestation to cause a net cooling effect. Trees also impact climate in extremely complicated ways through evapotranspiration. The water vapor causes cooling on the land surface, causes heating where it condenses, acts a strong greenhouse gas, and can increase albedo when it condenses into clouds Scientists generally treat evapotranspiration as a net cooling impact, and the net climate impact of albedo and evapotranspiration changes from deforestation depends greatly on local climate \n\nIn seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. Deciduous trees have an albedo value of about 0.15 to 0.18 whereas coniferous trees have a value of about 0.09 to 0.15.\n\nStudies by the Hadley Centre have investigated the relative (generally warming) effect of albedo change and (cooling) effect of carbon sequestration on planting forests. They found that new forests in tropical and midlatitude areas tended to cool; new forests in high latitudes (e.g., Siberia) were neutral or perhaps warming.\n\n===Water===\nWater reflects light very differently from typical terrestrial materials. The reflectivity of a water surface is calculated using the Fresnel equations (see graph).\nReflectivity of smooth water at 20 °C (refractive index=1.333)\nAt the scale of the wavelength of light even wavy water is always smooth so the light is reflected in a locally specular manner (not diffusely). The glint of light off water is a commonplace effect of this. At small angles of incident light, waviness results in reduced reflectivity because of the steepness of the reflectivity-vs.-incident-angle curve and a locally increased average incident angle.\n\nAlthough the reflectivity of water is very low at low and medium angles of incident light, it becomes very high at high angles of incident light such as those that occur on the illuminated side of Earth near the terminator (early morning, late afternoon, and near the poles). However, as mentioned above, waviness causes an appreciable reduction. Because light specularly reflected from water does not usually reach the viewer, water is usually considered to have a very low albedo in spite of its high reflectivity at high angles of incident light.\n\nNote that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. Fresh 'black' ice exhibits Fresnel reflection.\n\n===Clouds===\nCloud albedo has substantial influence over atmospheric temperatures. Different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. \"On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth.\"\n\nAlbedo and climate in some areas are affected by artificial clouds, such as those created by the contrails of heavy commercial airliner traffic. A study following the burning of the Kuwaiti oil fields during Iraqi occupation showed that temperatures under the burning oil fires were as much as 10 °C colder than temperatures several miles away under clear skies.\n\n===Aerosol effects===\nAerosols (very fine particles/droplets in the atmosphere) have both direct and indirect effects on Earth's radiative balance. The direct (albedo) effect is generally to cool the planet; the indirect effect (the particles act as cloud condensation nuclei and thereby change cloud properties) is less certain. As per the effects are:\n\n\n* ''Aerosol direct effect.'' Aerosols directly scatter and absorb radiation. The scattering of radiation causes atmospheric cooling, whereas absorption can cause atmospheric warming.\n* ''Aerosol indirect effect.'' Aerosols modify the properties of clouds through a subset of the aerosol population called cloud condensation nuclei. Increased nuclei concentrations lead to increased cloud droplet number concentrations, which in turn leads to increased cloud albedo, increased light scattering and radiative cooling (''first indirect effect''), but also leads to reduced precipitation efficiency and increased lifetime of the cloud (''second indirect effect'').\n\n\n===Black carbon===\nAnother albedo-related effect on the climate is from black carbon particles. The size of this effect is difficult to quantify: the Intergovernmental Panel on Climate Change estimates that the global mean radiative forcing for black carbon aerosols from fossil fuels is +0.2 W m−2, with a range +0.1 to +0.4 W m−2. Black carbon is a bigger cause of the melting of the polar ice cap in the Arctic than carbon dioxide due to its effect on the albedo.\n\n===Human activities===\nHuman activities (e.g., deforestation, farming, and urbanization) change the albedo of various areas around the globe. However, quantification of this effect on the global scale is difficult.\n",
"Single-scattering albedo is used to define scattering of electromagnetic waves on small particles. It depends on properties of the material (refractive index); the size of the particle or particles; and the wavelength of the incoming radiation.\n",
"\n\n* Cool roof\n* Daisyworld\n* Emissivity\n* Global dimming\n* Irradiance\n* Kirchhoff's law of thermal radiation\n* Opposition surge\n* Polar see-saw\n* Solar radiation management\n\n\n",
"\n",
"\n* Official Website of Albedo Project\n* Global Albedo Project (Center for Clouds, Chemistry, and Climate)\n* Albedo – Encyclopedia of Earth\n* NASA MODIS BRDF/albedo product site\n* Surface albedo derived from Meteosat observations\n* A discussion of Lunar albedos\n* reflectivity of metals (chart)\n\n\n\n\n\n\n\n\n\n"
] | [
"Introduction",
"Terrestrial albedo",
" Astronomical albedo ",
"Examples of terrestrial albedo effects",
"Other types of albedo",
"See also",
"References",
"External links"
] | Albedo |
[
"\n\n\n\n\n\n\nWriting cursive forms of A\n'''A''' (named , plural ''As'', ''A's'', ''a''s, ''a's'' or ''aes'') is the first letter and the first vowel of the ISO basic Latin alphabet. It is similar to the Ancient Greek letter alpha, from which it derives. The upper-case version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lower-case version can be written in two forms: the double-storey '''a''' and single-storey '''ɑ'''. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type.\n",
"{| class=\"wikitable\"\n\n Egyptian\n Cretan\n Phoenician ''aleph''\n Semitic \n Greek ''Alpha''\n Etruscan A\n Roman/Cyrillic A\n Boeotian 800–700 BC\n Greek Uncial\n Latin 300 AD Uncial\n\n Egyptian hieroglyphic ox head\n Early Crete version of the letter \"A\"\n Phoenician aleph\n Semitic letter \"A\", version 1\n Greek alpha, version 1\n Etruscan A, version 1\n Roman A\n Boeotian\n Greek Classical uncial, version 1\n Latin 300 AD uncial, version 1\n\n\n Crete \"A\"\n Phoenician version of the \"A\"\n Semitic \"A\", version 2\n Greek alpha, version 2\n Etruscan A, version 2\n Latin 4th century BC\n Boeotioan 800 BC\n Greek Classical uncial, version 2\n Latin 300 AD uncial, version 2\n\n\nThe earliest certain ancestor of \"A\" is aleph (also written 'aleph), the first letter of the Phoenician alphabet, which consisted entirely of consonants (for that reason, it is also called an abjad to distinguish it from a true alphabet). In turn, the ancestor of aleph may have been a pictogram of an ox head in proto-Sinaitic script influenced by Egyptian hieroglyphs, styled as a triangular head with two horns extended.\n\nIn 1600 B.C.E., the Phoenician alphabet letter had a linear form that served as the base for some later forms. Its name is thought to have corresponded closely to the Hebrew or Arabic aleph.\n\n\n\nBlackletter ABlackletter A\nUncial AUncial A\nAnother Capital AAnother Blackletter A \n\nModern Roman AModern Roman A\nModern Italic AModern Italic A\nModern Script AModern script A\n\nWhen the ancient Greeks adopted the alphabet, they had no use for a letter to represent the glottal stop—the consonant sound that the letter denoted in Phoenician and other Semitic languages, and that was the first phoneme of the Phoenician pronunciation of the letter—so they used their version of the sign to represent the vowel , and called it by the similar name of alpha. In the earliest Greek inscriptions after the Greek Dark Ages, dating to the 8th century BC, the letter rests upon its side, but in the Greek alphabet of later times it generally resembles the modern capital letter, although many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set.\n\nThe Etruscans brought the Greek alphabet to their civilization in the Italian Peninsula and left the letter unchanged. The Romans later adopted the Etruscan alphabet to write the Latin language, and the resulting letter was preserved in the Latin alphabet that would come to be used to write many languages, including English.\n\n===Typographic variants===\nDifferent glyphs of the lowercase letter A.\nDuring Roman times, there were many variant forms of the letter \"A\". First was the monumental or lapidary style, which was used when inscribing on stone or other \"permanent\" mediums. There was also a cursive style used for everyday or utilitarian writing, which was done on more perishable surfaces. Due to the \"perishable\" nature of these surfaces, there are not as many examples of this style as there are of the monumental, but there are still many surviving examples of different types of cursive, such as majuscule cursive, minuscule cursive, and semicursive minuscule. Variants also existed that were intermediate between the monumental and cursive styles. The known variants include the early semi-uncial, the uncial, and the later semi-uncial.\n\nTypographic variants include a double-storey '''a''' and single-storey '''ɑ'''.At the end of the Roman Empire (5th century AD), several variants of the cursive minuscule developed through Western Europe. Among these were the semicursive minuscule of Italy, the Merovingian script in France, the Visigothic script in Spain, and the Insular or Anglo-Irish semi-uncial or Anglo-Saxon majuscule of Great Britain. By the 9th century, the Caroline script, which was very similar to the present-day form, was the principal form used in book-making, before the advent of the printing press. This form was derived through a combining of prior forms.\n\n15th-century Italy saw the formation of the two main variants that are known today. These variants, the ''Italic'' and ''Roman'' forms, were derived from the Caroline Script version. The Italic form, also called ''script a,'' is used in most current handwriting and consists of a circle and vertical stroke. This slowly developed from the fifth-century form resembling the Greek letter tau in the hands of medieval Irish and English writers. The Roman form is used in most printed material; it consists of a small loop with an arc over it (\"a\"). Both derive from the majuscule (capital) form. In Greek handwriting, it was common to join the left leg and horizontal stroke into a single loop, as demonstrated by the uncial version shown. Many fonts then made the right leg vertical. In some of these, the serif that began the right leg stroke developed into an arc, resulting in the printed form, while in others it was dropped, resulting in the modern handwritten form.\n\nItalic type is commonly used to mark emphasis or more generally to distinguish one part of a text from the rest (set in Roman type). There are some other cases aside from italic type where ''script a'' (\"ɑ\"), also called Latin alpha, is used in contrast with Latin \"a\" (such as in the International Phonetic Alphabet).\n",
"305x305px\n\n===English===\n\nIn modern English orthography, the letter represents at least seven different vowel sounds:\n*the near-open front unrounded vowel as in ''pad'';\n*the open back unrounded vowel as in ''father'', which is closer to its original Latin and Greek sound;\n*the diphthong as in ''ace'' and ''major'' (usually when is followed by one, or occasionally two, consonants and then another vowel letter) – this results from Middle English lengthening followed by the Great Vowel Shift;\n*the modified form of the above sound that occurs before , as in ''square'' and ''Mary'';\n*the rounded vowel of ''water'';\n*the shorter rounded vowel (not present in General American) in ''was'' and ''what'';\n*a schwa, in many unstressed syllables, as in ''about'', ''comma'', ''solar''.\n\nThe double sequence does not occur in native English words, but is found in some words derived from foreign languages such as ''Aaron'' and ''aardvark''. However, occurs in many common digraphs, all with their own sound or sounds, particularly , , , , and .\n\n is the third-most-commonly used letter in English (after and ), and the second most common in Spanish and French. In one study, on average, about 3.68% of letters used in English texts tend to be , while the number is 6.22% in Spanish and 3.95% in French.\n\n===Other languages===\nIn most languages that use the Latin alphabet, denotes an open unrounded vowel, such as , , or . An exception is Saanich, in which (and the glyph Á) stands for a close-mid front unrounded vowel .\n\n===Other systems===\n\nIn phonetic and phonemic notation:\n*in the International Phonetic Alphabet, is used for the open front unrounded vowel, is used for the open central unrounded vowel, and is used for the open back unrounded vowel.\n*in X-SAMPA, is used for the open front unrounded vowel and is used for the open back unrounded vowel.\n",
"\nIn algebra, the letter ''a'' along with other letters at the beginning of the alphabet is used to represent known quantities, whereas the letters at the end of the alphabet (''x'', ''y'', ''z'') are used to denote unknown quantities.\n\nIn geometry, capital A, B, C etc. are used to denote segments, lines, rays, etc. A capital A is also typically used as one of the letters to represent an angle in a triangle, the lowercase a representing the side opposite angle A.\n\n\"A\" is often used to denote something or someone of a better or more prestigious quality or status: A-, A or A+, the best grade that can be assigned by teachers for students' schoolwork; \"A grade\" for clean restaurants; A-list celebrities, etc. Such associations can have a motivating effect, as exposure to the letter A has been found to improve performance, when compared with other letters.\n\nFinally, the letter A is used to denote size, as in a narrow size shoe, or a small cup size in a brassiere.\n",
"\n\n===Descendants and related characters in the Latin alphabet===\n*Æ æ : Latin ''AE'' ligature\n*A with diacritics: Å å Ǻ ǻ Ḁ ḁ ẚ Ă ă Ặ ặ Ắ ắ Ằ ằ Ẳ ẳ Ẵ ẵ Ȃ ȃ Â â Ậ ậ Ấ ấ Ầ ầ Ẫ ẫ Ẩ ẩ Ả ả Ǎ ǎ Ⱥ ⱥ Ȧ ȧ Ǡ ǡ Ạ ạ Ä ä Ǟ ǟ À à Ȁ ȁ Á á Ā ā Ā̀ ā̀ Ã ã Ą ą Ą́ ą́ Ą̃ ą̃ ᶏ\n\n*Phonetic alphabet symbols related to A (the International Phonetic Alphabet only uses lowercase, but uppercase forms are used in some other writing systems): \n**Ɑ ɑ : Latin letter alpha / script A, which represents an open back unrounded vowel in the IPA\n**ᶐ : Latin small letter alpha with retroflex hook\n**Ɐ ɐ : Turned A, which represents a near-open central vowel in the IPA\n**Λ ʌ : turned V (also called a wedge, a caret, or a hat), which represents an open-mid back unrounded vowel in the IPA\n**Ɒ ɒ : Turned alpha / script A, which represents an open back rounded vowel in the IPA\n**ᶛ : Modifier letter small turned alpha\n**ᴀ : Small capital A, an obsolete or non-standard symbol in the International Phonetic Alphabet used to represent various sounds (mainly open vowels)\n**ᴬ ᵃ ᵄ : Modifier letters are used in the Uralic Phonetic Alphabet (UPA).\n**ₐ : Subscript small a is used in Indo-European studies\n**ꬱ : Small letter a reversed-schwa is used in the Teuthonista phonetic transcription system\n\n===Derived signs, symbols and abbreviations===\n*ª : an ordinal indicator\n*Å : Ångström sign\n*∀ : a turned capital letter A, used in predicate logic to specify universal quantification (\"for all\")\n*@ : At sign\n*₳ : Argentine austral\n\n===Ancestors and siblings in other alphabets===\n\n*𐤀 : Semitic letter Aleph, from which the following symbols originally derive\n**Α α : Greek letter Alpha, from which the following letters derive\n***А а : Cyrillic letter A\n*** : Coptic letter Alpha\n***𐌀 : Old Italic A, which is the ancestor of modern Latin A\n**** : Runic letter ansuz, which probably derives from old Italic A\n*** : Gothic letter aza/asks\n",
"\n: 1 \n",
"\n",
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"* \n* \n* \n* \n* \n* \n* \n* \n* \n",
"\n\n* History of the Alphabet\n* \n\n\n\n"
] | [
"Introduction",
"History",
"Use in writing systems",
"Other uses",
"Related characters",
"Computing codes",
"Other representations",
"Notes",
"Footnotes",
"References",
"External links"
] | A |
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"\n\nAchilles and the Nereid Cymothoe, Attic red-figure kantharos from Volci (Cabinet des Médailles, Bibliothèque nationale, Paris)\nKremaste, Phthia. Reverse: Thetis, wearing and holding the shield of Achilles with his AX monogram.\n\n\nIn Greek mythology, '''Achilles''' (, ; ) was a Greek hero of the Trojan War and the central character and greatest warrior of Homer's ''Iliad''. His mother was the immortal nereid Thetis, and his father, the mortal Peleus, was the king of the Myrmidons.\n\nAchilles' most notable feat during the Trojan War was the slaying of the Trojan hero Hector outside the gates of Troy. Although the death of Achilles is not presented in the ''Iliad'', other sources concur that he was killed near the end of the Trojan War by Paris, who shot him in the heel with an arrow. Later legends (beginning with a poem by Statius in the 1st century AD) state that Achilles was invulnerable in all of his body except for his heel. Alluding to these legends, the term \"Achilles heel\" has come to mean a point of weakness, especially in someone or something with an otherwise strong constitution.\n",
"Linear B tablets attest to the personal name ''Achilleus'' in the forms ''a-ki-re-u'' and ''a-ki-re-we'', the latter being the dative of the former. The name grew more popular, even becoming common soon after the seventh century BC and was also turned into the female form Ἀχιλλεία (''Achilleía''), attested in Attica in the fourth century BC (IG II² 1617) and, in the form ''Achillia'', on a stele in Halicarnassus as the name of a female gladiator fighting an \"Amazon\".\n\nAchilles' name can be analyzed as a combination of ('''') \"distress, pain, sorrow, grief\" and ('''') \"people, soldiers, nation\", resulting in a proto-form ''*Akhí-lāu̯os'' \"he who has the people distressed\" or \"he whose people have distress\". The grief or distress of the people is a theme raised numerous times in the ''Iliad'' (and frequently by Achilles himself). Achilles' role as the hero of grief or distress forms an ironic juxtaposition with the conventional view of him as the hero of '''' (\"glory\", usually in war). Furthermore, ''laós'' has been construed by Gregory Nagy, following Leonard Palmer, to mean \"a corps of soldiers\", a muster. With this derivation, the name obtains a double meaning in the poem: when the hero is functioning rightly, his men bring distress to the enemy, but when wrongly, his men get the grief of war. The poem is in part about the misdirection of anger on the part of leadership.\n\nAnother etymology relates the name to a Proto-Indo-European compound ''*h₂eḱ-pṓds'' \"sharp foot\" which first gave an Illyrian ''*āk̂pediós'', evolving through time into ''*ākhpdeós'' and then ''*akhiddeús''. The shift from ''-dd-'' to ''-ll-'' is then ascribed to the passing of the name into Greek via a Pre-Greek source. The first root part ''*h₂eḱ-'' \"sharp, pointed\" also gave Greek ἀκή (''akḗ'' \"point, silence, healing\"), ἀκμή (''akmḗ'' \"point, edge, zenith\") and ὀξύς (''oxús'' \"sharp, pointed, keen, quick, clever\"), whereas ἄχος stems from the root ''*h₂egʰ-'' \"to be upset, afraid\". The whole expression would be comparable to the Latin ''acupedius'' \"swift of foot\". Compare also the Latin word family of ''aciēs'' \"sharp edge or point, battle line, battle, engagement\", ''acus'' \"needle, pin, bodkin\", and ''acuō'' \"to make pointed, sharpen, whet; to exercise; to arouse\" (whence ''acute''). Some topical epitheta of Achilles in the ''Iliad'' point to this \"swift-footedness\", namely ποδάρκης δῖος Ἀχιλλεὺς (''podárkēs dĩos Achilleús'' \"swift-footed divine Achilles\") or, even more frequently, πόδας ὠκὺς Ἀχιλλεύς (''pódas ōkús Achilleús'' \"quick-footed Achilles\").\n\nSome researchers deem the name a loan word, possibly from a Pre-Greek language. Achilles' descent from the Nereid Thetis and a similarity of his name with those of river deities such as Acheron and Achelous have led to speculations about him being an old water divinity (see below Worship). Robert S. P. Beekes has suggested a Pre-Greek origin of the name, based among other things on the coexistence of ''-λλ-'' and ''-λ-'' in epic language, which may account for a palatalized phoneme /ly/ in the original language.\n",
"Chiron teaching Achilles how to play the lyre, Roman fresco from Herculaneum, 1st century AD\n\nAchilles was the son of the Nereid Thetis and of Peleus, the king of the Myrmidons. Zeus and Poseidon had been rivals for the hand of Thetis until Prometheus, the fore-thinker, warned Zeus of a prophecy (originally uttered by Themis, goddess of divine law) that Thetis would bear a son greater than his father. For this reason, the two gods withdrew their pursuit, and had her wed Peleus.\n\nPeter Paul Rubens: ''Thetis Dipping the Infant Achilles into the River Styx'' (c. 1625; Museum Boijmans Van Beuningen, Rotterdam)\n\nThere is a tale which offers an alternative version of these events: In the ''Argonautica'' (4.760) Zeus' sister and wife Hera alludes to Thetis' chaste resistance to the advances of Zeus, pointing out that Thetis was so loyal to Hera's marriage bond that she coolly rejected the father of gods. Thetis, although a daughter of the sea-god Nereus, was also brought up by Hera, further explaining her resistance to the advances of Zeus. Zeus was furious and decreed that she would never marry an immortal.\n\n\n\nAccording to the ''Achilleid'', written by Statius in the 1st century AD, and to non-surviving previous sources, when Achilles was born Thetis tried to make him immortal, by dipping him in the river Styx. However, he was left vulnerable at the part of the body by which she held him, his left heel (see Achilles' heel, Achilles' tendon). It is not clear if this version of events was known earlier. In another version of this story, Thetis anointed the boy in ambrosia and put him on top of a fire, to burn away the mortal parts of his body. She was interrupted by Peleus and abandoned both father and son in a rage.\n\nHowever, none of the sources before Statius makes any reference to this general invulnerability. To the contrary, in the ''Iliad'' Homer mentions Achilles being wounded: in Book 21 the Paeonian hero Asteropaeus, son of Pelagon, challenged Achilles by the river Scamander. He cast two spears at once, one grazed Achilles' elbow, \"drawing a spurt of blood\".\n\nAlso, in the fragmentary poems of the Epic Cycle in which we can find description of the hero's death (i.e. the ''Cypria'', the ''Little Iliad'' by Lesches of Pyrrha, the ''Aithiopis'' and ''Iliou persis'' by Arctinus of Miletus), there is no trace of any reference to his general invulnerability or his famous weakness at the heel; in the later vase paintings presenting Achilles' death, the arrow (or in many cases, arrows) hit his body. Peleus entrusted Achilles to Chiron the Centaur, on Mount Pelion, to be reared. Thetis foretold that her son's fate was either to gain glory and die young, or to live a long but uneventful life in obscurity. Achilles chose the former, and decided to take part in the Trojan war. According to Homer, Achilles grew up in Phthia together with his companion Patroclus.\n\n=== Hidden on Skyros ===\n\n\nSome post-Homeric sources claim that in order to keep Achilles safe from the war, Thetis (or, in some versions, Peleus) hid the young man at the court of Lycomedes, king of Skyros. There, Achilles is disguised as a girl and lives among Lycomedes' daughters, perhaps under the name \"Pyrrha\" (the red-haired girl). With Lycomedes' daughter Deidamia, whom in the account of Statius he rapes, Achilles there fathers a son, Neoptolemus (also called Pyrrhus, after his father's possible alias). According to this story, Odysseus learns from the prophet Calchas that the Achaeans would be unable to capture Troy without Achilles' aid. Odysseus goes to Skyros in the guise of a peddler selling women's clothes and jewelry and places a shield and spear among his goods. When Achilles instantly takes up the spear, Odysseus sees through his disguise and convinces him to join the Greek campaign. In another version of the story, Odysseus arranges for a trumpet alarm to be sounded while he was with Lycomedes' women; while the women flee in panic, Achilles prepares to defend the court, thus giving his identity away.\n",
"According to the ''Iliad'', Achilles arrived at Troy with 50 ships, each carrying 50 Myrmidons. He appointed five leaders (each leader commanding 500 Myrmidons): Menesthius, Eudorus, Peisander, Phoenix and Alcimedon.\nAchilles and Agamemnon by Gottlieb Schick (1801)\n\n=== Telephus ===\nWhen the Greeks left for the Trojan War, they accidentally stopped in Mysia, ruled by King Telephus. In the resulting battle, Achilles gave Telephus a wound that would not heal; Telephus consulted an oracle, who stated that \"he that wounded shall heal\". Guided by the oracle, he arrived at Argos, where Achilles healed him in order that he might become their guide for the voyage to Troy.\n\nAccording to other reports in Euripides' lost play about Telephus, he went to Aulis pretending to be a beggar and asked Achilles to heal his wound. Achilles refused, claiming to have no medical knowledge. Alternatively, Telephus held Orestes for ransom, the ransom being Achilles' aid in healing the wound. Odysseus reasoned that the spear had inflicted the wound; therefore, the spear must be able to heal it. Pieces of the spear were scraped off onto the wound and Telephus was healed.\n\n=== Troilus ===\nAchilles slaying Troilus, red-figure kylix signed by Euphronios\n\nAccording to the ''Cypria'' (the part of the Epic Cycle that tells the events of the Trojan War before Achilles' wrath), when the Achaeans desired to return home, they were restrained by Achilles, who afterwards attacked the cattle of Aeneas, sacked neighbouring cities (like Pedasus and Lyrnessus, where the Greeks capture the queen Briseis) and killed Tenes, a son of Apollo, as well as Priam's son Troilus in the sanctuary of Apollo Thymbraios. However, the romance between Troilus and Chryseis described in Geoffrey Chaucer's ''Troilus and Criseyde'' and in William Shakespeare's ''Troilus and Cressida'' is a medieval invention.\n\nIn Dares Phrygius' ''Account of the Destruction of Troy'', the Latin summary through which the story of Achilles was transmitted to medieval Europe, as well as in older accounts, Troilus was a young Trojan prince, the youngest of King Priam's and Hecuba's five legitimate sons (or according other sources, another son of Apollo). Despite his youth, he was one of the main Trojan war leaders, a \"horse fighter\" or \"chariot fighter\" according to Homer. Prophecies linked Troilus' fate to that of Troy and so he was ambushed in an attempt to capture him. Yet Achilles, struck by the beauty of both Troilus and his sister Polyxena, and overcome with lust, directed his sexual attentions on the youth – who, refusing to yield, instead found himself decapitated upon an altar-omphalos of Apollo Thymbraios. Later versions of the story suggested Troilus was accidentally killed by Achilles in an over-ardent lovers' embrace. In this version of the myth, Achilles' death therefore came in retribution for this sacrilege. Ancient writers treated Troilus as the epitome of a dead child mourned by his parents. Had Troilus lived to adulthood, the First Vatican Mythographer claimed, Troy would have been invincible.\n\n=== Achilles in the ''Iliad'' ===\n\nAchilles cedes Briseis to Agamemnon, from the House of the Tragic Poet in Pompeii, fresco, 1st century AD (Naples National Archaeological Museum)\n\nHomer's ''Iliad'' is the most famous narrative of Achilles' deeds in the Trojan War. Achilles' wrath (μῆνις Ἀχιλλέως, ''mênis Achilléōs'') is the central theme of the poem. The first two lines of the ''Iliad'' read:\n\nΜῆνιν ἄειδε θεὰ Πηληϊάδεω Ἀχιλῆος\nοὐλομένην, ἣ μυρί' Ἀχαιοῖς ἄλγε' ἔθηκεν, …\n\n:Sing, Goddess, of the rage of Peleus' son Achilles,\n:the accursed rage that brought great suffering to the Achaeans.\n\n\nThe Homeric epic only covers a few weeks of the decade-long war, and does not narrate Achilles' death. It begins with Achilles' withdrawal from battle after being dishonoured by Agamemnon, the commander of the Achaean forces. Agamemnon has taken a woman named Chryseis as his slave. Her father Chryses, a priest of Apollo, begs Agamemnon to return her to him. Agamemnon refuses, and Apollo sends a plague amongst the Greeks. The prophet Calchas correctly determines the source of the troubles but will not speak unless Achilles vows to protect him. Achilles does so, and Calchas declares that Chryseis must be returned to her father. Agamemnon consents, but then commands that Achilles' battle prize Briseis, the daughter of Briseus, be brought to him to replace Chryseis. Angry at the dishonour of having his plunder and glory taken away (and, as he says later, because he loves Briseis), with the urging of his mother Thetis, Achilles refuses to fight or lead his troops alongside the other Greek forces. At the same time, burning with rage over Agamemnon's theft, Achilles prays to Thetis to convince Zeus to help the Trojans gain ground in the war, so that he may regain his honour.\n\nThe embassy to Achilles, Attic red-figure hydria, c. 480 BC (Staatliche Antikensammlungen, Berlin)\nAchilles and Agamemnon, from a fresco of Pompeii, 1st century AD\n\nAs the battle turns against the Greeks, thanks to the influence of Zeus, Nestor declares that the Trojans are winning because Agamemnon has angered Achilles, and urges the king to appease the warrior. Agamemnon agrees and sends Odysseus and two other chieftains, Ajax and Phoenix, to Achilles with the offer of the return of Briseis and other gifts. Achilles rejects all Agamemnon offers him and simply urges the Greeks to sail home as he was planning to do.\n\nAchilles sacrificing to Zeus for Patroclus' safe return, from the ''Ambrosian Iliad'', a 5th-century illuminated manuscript\n''The Rage of Achilles'', fresco by Giovanni Battista Tiepolo (1757, Villa Valmarana ai Nani, Vicenza)\nTriumphant Achilles dragging Hector's lifeless body in front of the Gates of Troy, from a panoramic fresco on the upper level of the main hall of the Achilleion\n\nThe Trojans, led by Hector, subsequently push the Greek army back toward the beaches and assault the Greek ships. With the Greek forces on the verge of absolute destruction, Patroclus leads the Myrmidons into battle, wearing Achilles' armour, though Achilles remains at his camp. Patroclus succeeds in pushing the Trojans back from the beaches, but is killed by Hector before he can lead a proper assault on the city of Troy.\n\nAfter receiving the news of the death of Patroclus from Antilochus, the son of Nestor, Achilles grieves over his beloved companion's death. His mother Thetis comes to comfort the distraught Achilles. She persuades Hephaestus to make new armour for him, in place of the armour that Patroclus had been wearing, which was taken by Hector. The new armour includes the Shield of Achilles, described in great detail in the poem.\n\nEnraged over the death of Patroclus, Achilles ends his refusal to fight and takes the field, killing many men in his rage but always seeking out Hector. Achilles even engages in battle with the river god Scamander, who has become angry that Achilles is choking his waters with all the men he has killed. The god tries to drown Achilles but is stopped by Hera and Hephaestus. Zeus himself takes note of Achilles' rage and sends the gods to restrain him so that he will not go on to sack Troy itself before the time allotted for its destruction, seeming to show that the unhindered rage of Achilles can defy fate itself. Finally, Achilles finds his prey. Achilles chases Hector around the wall of Troy three times before Athena, in the form of Hector's favorite and dearest brother, Deiphobus, persuades Hector to stop running and fight Achilles face to face. After Hector realizes the trick, he knows the battle is inevitable. Wanting to go down fighting, he charges at Achilles with his only weapon, his sword, but misses. Accepting his fate, Hector begs Achilles, not to spare his life, but to treat his body with respect after killing him. Achilles tells Hector it is hopeless to expect that of him, declaring that \"my rage, my fury would drive me now to hack your flesh away and eat you raw – such agonies you have caused me\". Achilles then kills Hector and drags his corpse by its heels behind his chariot. After having a dream where Patroclus begs Achilles to hold his funeral, Achilles hosts a series of funeral games in his honour.\n\ntondo of an Attic red-figure kylix, c. 465 BC, from Vulci.\n\nWith the assistance of the god Hermes, Hector's father, Priam, goes to Achilles' tent to plead with Achilles for the return of Hector's body so that he can be buried. Achilles relents and promises a truce for the duration of the funeral. The poem ends with a description of Hector's funeral, with the doom of Troy and Achilles himself still to come.\n\n=== Later epic accounts: Fighting Penthesilea and Memnon ===\nAchilles and Penthesilea fighting, Lucanian red-figure bell-krater, late 5th century BC\nAchilles and Memnon fighting, between Thetis and Eos, Attic black-figure amphora, c. 510 BC, from Vulci.\n\nThe ''Aethiopis'' (7th century BC) and a work named ''Posthomerica'', composed by Quintus of Smyrna in the fourth century AD, relate further events from the Trojan War. When Penthesilea, queen of the Amazons and daughter of Ares, arrives in Troy, Priam hopes that she defeat Achilles. After his temporary truce with Priam, Achilles fights and kills the warrior queen, only to grieve over her death later. At first, he was so distracted by her beauty, he did not fight as intensely as usual. Once he realized that his distraction was endangering his life, he refocused and killed her.\n\nFollowing the death of Patroclus, Nestor's son Antilochus becomes Achilles' closest companion. When Memnon, son of the Dawn Goddess Eos and king of Ethiopia, slays Antilochus, Achilles once more obtains revenge on the battlefield, killing Memnon. Consequently, Eos will not let the sun rise, until Zeus persuades her. The fight between Achilles and Memnon over Antilochus echoes that of Achilles and Hector over Patroclus, except that Memnon (unlike Hector) was also the son of a goddess.\n\nMany Homeric scholars argued that episode inspired many details in the ''Iliad'''s description of the death of Patroclus and Achilles' reaction to it. The episode then formed the basis of the cyclic epic ''Aethiopis'', which was composed after the ''Iliad'', possibly in the 7th century BC. The ''Aethiopis'' is now lost, except for scattered fragments quoted by later authors.\n\n=== Achilles' death ===\n\nAttic black-figure lekythos, c. 510 BC, from Sicily (Staatliche Antikensammlungen, Munich).\n\nThe death of Achilles, as predicted by Hector with his dying breath, was brought about by Paris with an arrow (to the heel according to Statius). In some versions, the god Apollo guided Paris' arrow. Some retellings also state that Achilles was scaling the gates of Troy and was hit with a poisoned arrow. All of these versions deny Paris any sort of valour, owing to the common conception that Paris was a coward and not the man his brother Hector was, and Achilles remained undefeated on the battlefield. His bones were mingled with those of Patroclus, and funeral games were held. He was represented in the ''Aethiopis'' as living after his death in the island of Leuke at the mouth of the river Danube.\n\nAnother version of Achilles' death is that he fell deeply in love with one of the Trojan princesses, Polyxena. Achilles asks Priam for Polyxena's hand in marriage. Priam is willing because it would mean the end of the war and an alliance with the world's greatest warrior. But while Priam is overseeing the private marriage of Polyxena and Achilles, Paris, who would have to give up Helen if Achilles married his sister, hides in the bushes and shoots Achilles with a divine arrow, killing him.\n\nIn the ''Odyssey'', Agamemnon informs Achilles of his pompous burial and the erection of his mound at the Hellespont while they are receiving the dead suitors in Hades. He claims they built a massive burial mound on the beach of Ilion that could be seen by anyone approaching from the Ocean. Achilles was cremated and his ashes buried in the same urn as those of Patroclus. Paris was later killed by Philoctetes using the enormous bow of Heracles.\n\nIn Book 11 of Homer's ''Odyssey'', Odysseus sails to the underworld and converses with the shades. One of these is Achilles, who when greeted as \"blessed in life, blessed in death\", responds that he would rather be a slave to the worst of masters than be king of all the dead. But Achilles then asks Odysseus of his son's exploits in the Trojan war, and when Odysseus tells of Neoptolemus' heroic actions, Achilles is filled with satisfaction. This leaves the reader with an ambiguous understanding of how Achilles felt about the heroic life.\n\nAccording to some accounts, he had married Medea in life, so that after both their deaths they were united in the Elysian Fields of Hades – as Hera promised Thetis in Apollonius' ''Argonautica'' (3rd century BC).\n\nAchilles tending Patroclus wounded by an arrow, Attic red-figure kylix, c. 500 BC (Altes Museum, Berlin)\n\n=== Achilles and Patroclus ===\n\n\nThe exact nature of Achilles' relationship with Patroclus has been a subject of dispute in both the classical period and modern times. In the ''Iliad'', it appears to be the model of a deep and loyal friendship. Homer does not suggest that Achilles and his close friend Patroclus were lovers. Despite there being no direct evidence in the text of the Iliad that Achilles and Patroclus were lovers, this theory was expressed by some later authors. Commentators from classical antiquity to the present have often interpreted the relationship through the lens of their own cultures. In 5th-century BC Athens, the intense bond was often viewed in light of the Greek custom of ''paiderasteia''. In Plato's ''Symposium'', the participants in a dialogue about love assume that Achilles and Patroclus were a couple; Phaedrus argues that Achilles was the younger and more beautiful one so he was the beloved and Patroclus was the lover. But ancient Greek had no words to distinguish heterosexual and homosexual, and it was assumed that a man could both desire handsome young men and have sex with women.\n\n=== The fate of Achilles' armour ===\nAchilles and Ajax playing the board game ''petteia'', black-figure oinochoe, c. 530 BC (Capitoline Museums, Rome)\n\nAchilles' armour was the object of a feud between Odysseus and Telamonian Ajax (Ajax the greater). They competed for it by giving speeches on why they were the bravest after Achilles to their Trojan prisoners, who after considering both men came to a consensus in favor of Odysseus. Furious, Ajax cursed Odysseus, which earned the ire of Athena. Athena temporarily made Ajax so mad with grief and anguish that he began killing sheep, thinking them his comrades. After a while, when Athena lifted his madness and Ajax realized that he had actually been killing sheep, Ajax was left so ashamed that he committed suicide. Odysseus eventually gave the armour to Neoptolemus, the son of Achilles.\n\nA relic claimed to be Achilles' bronze-headed spear was for centuries preserved in the temple of Athena on the acropolis of Phaselis, Lycia, a port on the Pamphylian Gulf. The city was visited in 333 BC by Alexander the Great, who envisioned himself as the new Achilles and carried the ''Iliad'' with him, but his court biographers do not mention the spear. However, it was shown in the time of Pausanias in the 2nd century AD.\n\n=== Achilles, Ajax and a game of ''petteia'' ===\nNumerous paintings on pottery have suggested a tale not mentioned in the literary traditions. At some point in the war, Achilles and Ajax were playing a board game (''petteia''). They were absorbed in the game and oblivious to the surrounding battle. The Trojans attacked and reached the heroes, who were saved only by an intervention of Athena.\n",
"The tomb of Achilles, extant throughout antiquity in Troad, was venerated by Thessalians, but also by Persian expeditionary forces, as well as by Alexander the Great and the Roman emperor Caracalla. Achilles' cult was also to be found at other places, e. g. on the island of Astypalaea in the Sporades, in Sparta which had a sanctuary, in Elis and in Achill's homeland Thessaly, as well as in the Magna Graecia cities of Tarentum, Locri and Croton, accounting for an almost Panhellenic cult to the hero.\n\nThe spread and intensity of the hero's veneration among the Greeks that had settled on the northern coast of the Pontus Euxinus, today's Black Sea, appears to have been remarkable. An archaic cult is attested for the Milesian colony of Olbia as well as for an island in the middle of the Black Sea, today identified with Snake Island (Ukrainian Зміїний, ''Zmiinyi'', near Kiliya, Ukraine). Early dedicatory inscriptions from the Greek colonies on the Black Sea (graffiti and inscribed clay disks, these possibly being votive offerings, from Olbia, the area of Berezan Island and the Tauric Chersonese) attest the existence of a heroic cult of Achilles from the sixth century BC onwards. The cult was still thriving in the third century AD, when dedicatory stelae from Olbia refer to an ''Achilles Pontárchēs'' (Ποντάρχης, roughly \"lord of the Sea,\" or \"of the Pontus Euxinus\"), who was invoked as a protector of the city of Olbia, venerated on par with Olympian gods such as the local Apollo Prostates, Hermes Agoraeus, or Poseidon.\n\nPliny the Elder (23–79 AD) in his ''Natural History'' mentions a \"port of the Achæi\" and an \"island of Achilles\", famous for the tomb of that \"man\" (portus Achaeorum, insula Achillis, tumulo eius viri clara), situated somewhat nearby Olbia and the Dnieper-Bug Estuary; furthermore, at 125 Roman miles from this island, he places a peninsula \"which stretches forth in the shape of a sword\" obliquely, called ''Dromos Achilleos'' (Ἀχιλλέως δρόμος, ''Achilléōs drómos'' \"the Race-course of Achilles\") and considered the place of the hero's exercise or of games instituted by him. This last feature of Pliny's account is considered to be the iconic spit, called today ''Tendra'' (or ''Kosa Tendra'' and ''Kosa Djarilgatch''), situated between the mouth of the Dnieper and Karkinit Bay, but which is hardly 125 Roman miles (c. 185 km) away from the Dnieper-Bug estuary, as Pliny states. (To the \"Race-course\" he gives a length of 80 miles, c. 120 km, whereas the spit measures c. 70 km today.)\n\nThetis and the Nereids mourning Achilles, Corinthian black-figure hydria, c. 555 BC (Louvre, Paris)\nRoman statue of a man with the dead body of a boy, identified as Achilles and Troilus, 2nd century AD (Naples National Archaeological Museum)\n\nIn the following chapter of his book, Pliny refers to the same island as ''Achillea'' and introduces two further names for it: ''Leuce'' or ''Macaron'' (from Greek νῆσος μακαρῶν \"island of the blest\"). The \"present day\" measures, he gives at this point, seem to account for an identification of ''Achillea'' or ''Leuce'' with today's Snake Island. Pliny's contemporary Pomponius Mela (c. 43 AD) tells that Achilles was buried on an island named ''Achillea'', situated between the Borysthenes and the Ister, adding to the geographical confusion. Ruins of a square temple, measuring 30 meters to a side, possibly that dedicated to Achilles, were discovered by Captain Kritzikly in 1823 on Snake Island. A second exploration in 1840 showed that the construction of a lighthouse had destroyed all traces of this temple. A fifth century BC black-glazed lekythos inscription, found on the island in 1840, reads: \"Glaukos, son of Poseidon, dedicated me to Achilles, lord of Leuke.\" In another inscription from the fifth or fourth century BC, a statue is dedicated to Achilles, lord of Leuke, by a citizen of Olbia, while in a further dedication, the city of Olbia confirms its continuous maintenance of the island's cult, again suggesting its quality as a place of a supra-regional hero veneration.\n\nThe heroic cult dedicated to Achilles on ''Leuce'' seems to go back to an account from the lost epic ''Aethiopis'' according to which, after his untimely death, Thetis had snatched her son from the funeral pyre and removed him to a mythical Λεύκη Νῆσος (''Leúkē Nêsos'' \"White Island\"). Already in the fifth century BC, Pindar had mentioned a cult of Achilles on a \"bright island\" (φαεννά νᾶσος, ''phaenná nâsos'') of the Black Sea, while in another of his works, Pindar would retell the story of the immortalized Achilles living on a geographically indefinite Island of the Blest together with other heroes such as his father Peleus and Cadmus. Well known is the connection of these mythological Fortunate Isles (μακαρῶν νῆσοι, ''makárôn nêsoi'') or the Homeric Elysium with the stream Oceanus which according to Greek mythology surrounds the inhabited world, which should have accounted for the identification of the northern strands of the Euxine with it. Guy Hedreen has found further evidence for this connection of Achilles with the northern margin of the inhabited world in a poem by Alcaeus, speaking of \"Achilles lord of Scythia\" and the opposition of North and South, as evoked by Achilles' fight against the Aethiopian prince Memnon, who in his turn would be removed to his homeland by his mother Eos after his death.\n\nThe ''Periplus of the Euxine Sea'' (c. 130 AD) gives the following details:\n\n\n\nThe Greek geographer Dionysius Periegetes, who lived probably during the first century AD, wrote that the island was called ''Leuce'' \"because the wild animals which live there are white. It is said that there, in Leuce island, reside the souls of Achilles and other heroes, and that they wander through the uninhabited valleys of this island; this is how Jove rewarded the men who had distinguished themselves through their virtues, because through virtue they had acquired everlasting honour\". Similarly, others relate the island's name to its white cliffs, snakes or birds dwelling there. Pausanias has been told that the island is \"covered with forests and full of animals, some wild, some tame. In this island there is also Achilles' temple and his statue\". Leuce had also a reputation as a place of healing. Pausanias reports that the Delphic Pythia sent a lord of Croton to be cured of a chest wound. Ammianus Marcellinus attributes the healing to waters (''aquae'') on the island.\n\nA number of important commercial port cities of the Greek waters were dedicated to Achilles. Herodotus, Pliny the Elder and Strabo reported on the existence of a town ''Achílleion'' (Ἀχίλλειον), built by settlers from Mytilene in the sixth century BC, close to the hero's presumed burial mound in the Troad. Later attestations point to an ''Achílleion'' in Messenia (according to Stephanus Byzantinus) and an ''Achílleios'' (Ἀχίλλειος) in Laconia. Nicolae Densuşianu recognized a connection to Achilles in the names of Aquileia and of the northern arm of the Danube delta, called Chilia (presumably from an older ''Achileii''), though his conclusion, that Leuce had sovereign rights over the Black Sea, evokes modern rather than archaic sea-law.\n\nThe kings of Epirus claimed to be descended from Achilles through his son, Neoptolemus. Alexander the Great, son of the Epirote princess Olympias, could therefore also claim this descent, and in many ways strove to be like his great ancestor. He is said to have visited the tomb of Achilles at Achilleion while passing Troy. In AD 216 the Roman Emperor Caracalla, while on his way to war against Parthia, emulated Alexander by holding games around Achilles' tumulus.\n",
"=== Achilles in Greek tragedy ===\n\n\nThe Greek tragedian Aeschylus wrote a trilogy of plays about Achilles, given the title ''Achilleis'' by modern scholars. The tragedies relate the deeds of Achilles during the Trojan War, including his defeat of Hector and eventual death when an arrow shot by Paris and guided by Apollo punctures his heel. Extant fragments of the ''Achilleis'' and other Aeschylean fragments have been assembled to produce a workable modern play. The first part of the ''Achilleis'' trilogy, ''The Myrmidons'', focused on the relationship between Achilles and chorus, who represent the Achaean army and try to convince Achilles to give up his quarrel with Agamemnon; only a few lines survive today. In Plato's ''Symposium'', Phaedrus points out that Aeschylus portrayed Achilles as the lover and Patroclus as the beloved; Phaedrus argues that this is incorrect because Achilles, being the younger and more beautiful of the two, was the beloved, who loved his lover so much that he chose to die to revenge him.\n\nThe tragedian Sophocles also wrote ''The Lovers of Achilles'', a play with Achilles as the main character. Only a few fragments survive.\n\nTowards the end of the 5th century BC, a more negative view of Achilles emerges in Greek drama; Euripides refers to Achilles in a bitter or ironic tone in ''Hecuba'', ''Electra'', and ''Iphigenia in Aulis''.\n\n=== Achilles in Greek philosophy ===\nThe philosopher Zeno of Elea centered one of his paradoxes on an imaginary footrace between \"swift-footed\" Achilles and a tortoise, by which he attempted to show that Achilles could not catch up to a tortoise with a head start, and therefore that motion and change were impossible. As a student of the monist Parmenides and a member of the Eleatic school, Zeno believed time and motion to be illusions.\n\n=== Achilles in Roman and medieval literature ===\nThe Romans, who traditionally traced their lineage to Troy, took a highly negative view of Achilles. Virgil refers to Achilles as a savage and a merciless butcher of men, while Horace portrays Achilles ruthlessly slaying women and children. Other writers, such as Catullus, Propertius, and Ovid, represent a second strand of disparagement, with an emphasis on Achilles' erotic career. This strand continues in Latin accounts of the Trojan War by writers such as Dictys Cretensis and Dares Phrygius and in Benoît de Sainte-Maure's ''Roman de Troie'' and Guido delle Colonne's ''Historia destructionis Troiae'', which remained the most widely read and retold versions of the Matter of Troy until the 17th century.\n\nAchilles was described by the Byzantine chronicler Leo the Deacon, not as Hellene, but as Scythian, while according to the Byzantine author John Malalas, his army was made up of a tribe previously known as Myrmidons and later as Bulgars.\n",
"\n''Briseis and Achilles'', engraving by Wenceslaus Hollar (1607–1677)\n''The Wrath of Achilles'' (c. 1630–1635), painting by Peter Paul Rubens\n''The death of Hector'', unfinished oil painting by Peter Paul Rubens\nJames Barry (Yale Center for British Art)\n''The Wrath of Achilles'', by François-Léon Benouville (1847; Musée Fabre)\n''The Education of Achilles'', by Eugène Delacroix, pastel on paper, c. 1862 (Getty Center, Los Angeles)\n\n===Literature===\n* Achilles appears in Dante's ''Inferno'' (composed 1308–1320). He is seen in Hell's second Circle of Lust.\n* Achilles is portrayed as a former hero who has become lazy and devoted to the love of Patroclus, in William Shakespeare's ''Troilus and Cressida'' (1602).\n* The French dramatist Thomas Corneille wrote a tragedy ''La Mort d'Achille'' (1673).\n* Achilles is the subject of the poem ''Achilleis'' (1799), a fragment by Johann Wolfgang von Goethe.\n* Achilles is mentioned in Tennyson's poem \"Ulysses\" (published in 1842): \"… we shall touch the happy isles and meet there the great Achilles whom we knew.\"\n* In 1899, the Polish playwright, painter and poet Stanisław Wyspiański published a national drama, based on Polish history, named ''Achilles''.\n* In 1921, Edward Shanks published ''The Island of Youth and Other Poems'', concerned among others with Achilles.\n* The 1983 novel ''Kassandra'' by Christa Wolf also treats the death of Achilles.\n* Achilles (Akhilles) is killed by a poisoned Kentaur arrow shot by Kassandra in Marion Zimmer Bradley's novel ''The Firebrand'' (1987).\n* Achilles is one of various 'narrators' in Colleen McCullough's novel ''The Song of Troy'' (1998).\n* ''The Death of Achilles'' (''Смерть Ахиллеса'', 1998) is an historical detective novel by Russian writer Boris Akunin that alludes to various figures and motifs from the ''Iliad''.\n* The character Achilles in ''Ender's Shadow'' (1999), by Orson Scott Card, shares his namesake's cunning mind and ruthless attitude.\n* Achilles is one of the main characters in Dan Simmons's novels ''Ilium'' (2003) and ''Olympos'' (2005).\n* Achilles is a major supporting character in David Gemmell's ''Troy'' series of books (2005-2007).\n* Achilles is the main character in David Malouf's novel ''Ransom'' (2009).\n* The ghost of Achilles appears in Rick Riordan's ''The Last Olympian'' (2009). He warns Percy Jackson about the Curse of Achilles and its side effects.\n* Achilles is a main character in Terence Hawkins' 2009 novel ''The Rage of Achilles''.\n* Achilles is a major character in Madeline Miller's debut novel, ''The Song of Achilles'' (2011), which won the 2012 Orange Prize for Fiction. The novel explores the relationship between Patroclus and Achilles from boyhood to the fateful events of the ''Iliad''.\n* Achilles appears in the light novel series ''Fate/Apocrypha'' (2012–2014) as the Rider of Red.\n\n=== Visual arts ===\n* ''Achilles with the Daughters of Lycomedes'' is a subject treated in paintings by Anthony van Dyck (before 1618; Museo del Prado, Madrid) and Nicolas Poussin (c. 1652; Museum of Fine Arts, Boston) among others.\n* Peter Paul Rubens has authored a series of works on the life of Achilles, comprising the titles: ''Thetis dipping the infant Achilles into the river Styx'', ''Achilles educated by the centaur Chiron'', ''Achilles recognized among the daughters of Lycomedes'', ''The wrath of Achilles'', ''The death of Hector'', ''Thetis receiving the arms of Achilles from Vulcanus'', ''The death of Achilles'' (Museum Boijmans Van Beuningen, Rotterdam), and ''Briseis restored to Achilles'' (Detroit Institute of Arts; all c. 1630–1635)\n* ''Dying Achilles'' is a sculpture created by Christophe Veyrier (c. 1683; Victoria and Albert Museum, London).\n* ''The Rage of Achilles'' is a fresco by Giovanni Battista Tiepolo (1757, Villa Valmarana ai Nani, Vicenza).\n* Eugène Delacroix painted a version of ''The Education of Achilles'' for the ceiling of the Paris Palais Bourbon (1833–1847), one of the seats of the French Parliament.\n* Arthur Kaan created a statue group ''Achilles and Penthesilea'' (1895; Vienna).\n* ''Achilleus'' (1908) is a lithography by Max Slevogt.\n\n=== Music ===\nAchilles has been frequently the subject of operas, ballets and related genres.\n\n* Operas titled ''Deidamia'' were composed by Francesco Cavalli (1644) and George Frideric Handel (1739).\n* ''Achille et Polyxène'' (Paris 1687) is an opera begun by Jean-Baptiste Lully and finished by Pascal Collasse.\n* ''Achille e Deidamia'' (Naples 1698) is an opera, composed by Alessandro Scarlatti.\n* ''Achilles'' (London 1733) is a ballad opera, written by John Gay, parodied by Thomas Arne as ''Achilles in petticoats'' in 1773.\n* ''Achille in Sciro'' is a libretto by Metastasio, composed by Domenico Sarro for the inauguration of the Teatro di San Carlo (Naples, 4 November 1737). An even earlier composition is from Antonio Caldara (Vienna 1736). Later operas on the same libretto were composed by Leonardo Leo (Turin 1739), Niccolò Jommelli (Vienna 1749 and Rome 1772), Giuseppe Sarti (Copenhagen 1759 and Florence 1779), Johann Adolph Hasse (Naples 1759), Giovanni Paisiello (St. Petersburg 1772), Giuseppe Gazzaniga (Palermo 1781) and many others. It has also been set to music as ''Il Trionfo della gloria''.\n* ''Achille'' (Vienna 1801) is an opera by Ferdinando Paër on a libretto by Giovanni de Gamerra.\n* ''Achille à Scyros'' (Paris 1804) is a ballet by Pierre Gardel, composed by Luigi Cherubini.\n* ''Achilles, oder Das zerstörte Troja'' (\"Achilles, or Troy Destroyed\", Bonn 1885) is an oratorio by the German composer Max Bruch.\n* ''Achilles auf Skyros'' (Stuttgart 1926) is a ballet by the Austrian-British composer and musicologist Egon Wellesz.\n* ''Achilles' Wrath'' is a concert piece by Sean O'Loughlin.\n\n===Architecture===\n''Dying Achilles'' (Achilleas thniskon) in the gardens of the Achilleion \nIn 1890, Elisabeth of Bavaria, Empress of Austria, had a summer palace built in Corfu. The building is named the ''Achilleion'', after Achilles. Its paintings and statuary depict scenes from the Trojan war, with particular focus on Achilles.\n",
"* The name of Achilles has been used for at least nine Royal Navy warships since 1744 - both as HMS ''Achilles'' and with the French spelling HMS ''Achille''. A 60-gun ship of that name served at the Battle of Belleisle in 1761 while a 74-gun ship served at the Battle of Trafalgar. Other battle honours include Walcheren 1809. An armored cruiser of that name served in the Royal Navy during the First World War.\n* HMNZS ''Achilles'' was a ''Leander''-class cruiser which served with the Royal New Zealand Navy in World War II. It became famous for its part in the Battle of the River Plate, alongside and . In addition to earning the battle honour 'River Plate', HMNZS Achilles also served at Guadalcanal 1942–43 and Okinawa in 1945. After returning to the Royal Navy, the ship was sold to the Indian Navy in 1948 but when she was scrapped parts of the ship were saved and preserved in New Zealand.\n* A species of lizard, ''Anolis achilles'', which has widened heel plates, is named for Achilles.\n",
"\n",
"* Homer, ''Iliad''\n* Homer, ''Odyssey'' XI, 467–540\n* Pseudo-Apollodorus, ''Bibliotheca'' III, xiii, 5–8\n* Apollodorus, ''Epitome'' III, 14-V, 7\n* Ovid, ''Metamorphoses'' XI, 217–265; XII, 580-XIII, 398\n* Ovid, ''Heroides'' III\n* Apollonius Rhodius, ''Argonautica'' IV, 783–879\n* Dante Alighieri, ''The Divine Comedy'', Inferno, V.\n",
"* Ileana Chirassi Colombo (1977), \"Heroes Achilleus – Theos Apollon.\" In ''Il Mito Greco'', edd. Bruno Gentili and Giuseppe Paione. Rome: Edizione dell'Ateneo e Bizzarri.\n* Anthony Edwards (1985a), \"Achilles in the Underworld: Iliad, Odyssey, and Æthiopis\". ''Greek, Roman, and Byzantine Studies''. '''26''': pp. 215–227.\n* Anthony Edwards (1985b), \"Achilles in the Odyssey: Ideologies of Heroism in the Homeric Epic\". ''Beiträge zur klassischen Philologie''. '''171'''.\n* Anthony Edwards (1988), \"Kleos Aphthiton and Oral Theory,\" ''Classical Quarterly''. '''38''': pp. 25–30.\n* \n* \n* \n* \n* Hélène Monsacré (1984), ''Les larmes d'Achille. Le héros, la femme et la souffrance dans la poésie d'Homère'', Paris: Albin Michel.\n* Gregory Nagy (1984), ''The Name of Achilles: Questions of Etymology and 'Folk Etymology''', ''Illinois Classical Studies''. '''19'''.\n* Gregory Nagy (1999), ''The Best of The Acheans: Concepts of the Hero in Archaic Greek Poetry''. Johns Hopkins University Press (revised edition, online).\n* \n* Dale S. Sinos (1991), ''The Entry of Achilles into Greek Epic'', Ph. D. thesis, Johns Hopkins University. Ann Arbor, Michigan: University Microfilms International.\n* Jonathan S. Burgess (2009), ''The Death and Afterlife of Achilles''. Baltimore: Johns Hopkins University Press.\n",
"\n\n* Trojan War Resources\n* Gallery of the Ancient Art: Achilles\n* Poem by Florence Earle Coates\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
] | [
"Introduction",
" Etymology ",
" Birth and early years ",
" Achilles in the Trojan War ",
" Worship and heroic cult ",
" Reception during antiquity ",
"Achilles in modern literature and arts ",
" Namesakes ",
" Notes ",
" References ",
" Bibliography ",
" External links "
] | Achilles |
["\n\n\n\n\n\n\n'''Abraham Lincoln''' (; February 12, 1809 – April 15, 1865) was an American poli(...TRUNCATED) | ["Introduction","Family and childhood","Early career and militia service","U.S. House of Representat(...TRUNCATED) | Abraham Lincoln |
["\n\n\n\n\n'''Aristotle''' (; , , ''Aristotélēs''; 384–322 BC) was an ancient Greek philosophe(...TRUNCATED) | ["Introduction"," Life ","Thought","Loss and preservation of his works","Legacy","List of works","Ep(...TRUNCATED) | Aristotle |
["\n\n\n\n'''''An American in Paris''''' is a jazz-influenced orchestral piece by the American compo(...TRUNCATED) | ["Introduction","Background","Composition","Instrumentation","Response","Preservation status","Recor(...TRUNCATED) | An American in Paris |
["\n\n\nThe '''Academy Award for Best Production Design''' recognizes achievement for art direction (...TRUNCATED) | ["Introduction","Superlatives","Best Interior Decoration","Best Art Direction – Set Decoration(...TRUNCATED) | Academy Award for Best Production Design |
["\n\n\n\n\nThe '''Academy Awards''', now known officially as '''The Oscars''', is a set of twenty-f(...TRUNCATED) | ["Introduction","History","Oscar statuette","Nomination","Awards ceremonies","Venues","Awards of Mer(...TRUNCATED) | Academy Awards |
["\n\n\n\n'''''Actresses''''' (Catalan: '''''Actrius''''') is a 1997 Catalan language Spanish drama (...TRUNCATED) | [
"Introduction",
"Synopsis",
"Cast",
"Recognition",
"References",
"External links"
] | Actrius |
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