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Aphasia

In aphasia (sometimes called dysphasia), a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine but aphasia due to stroke is estimated to be 0.1–0.4% in the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases (such as dementias).

To be diagnosed with aphasia, a person's language must be significantly impaired in one (or more) of the four aspects of communication. Alternatively, in the case of progressive aphasia, it must have significantly declined over a short period of time. The four aspects of communication are spoken language production and comprehension and written language production and comprehension; impairments in any of these aspects can impact on functional communication.

The difficulties of people with aphasia can range from occasional trouble finding words, to losing the ability to speak, read, or write; intelligence, however, is unaffected. Expressive language and receptive language can both be affected as well. Aphasia also affects visual language such as sign language. In contrast, the use of formulaic expressions in everyday communication is often preserved. For example, while a person with aphasia, particularly expressive aphasia (Broca's aphasia), may not be able to ask a loved one when their birthday is, they may still be able to sing "Happy Birthday". One prevalent deficit in all aphasias is anomia, which is a difficulty in finding the correct word.

With aphasia, one or more modes of communication in the brain have been damaged and are therefore functioning incorrectly. Aphasia is not caused by damage to the brain resulting in motor or sensory deficits, thus producing abnormal speech – that is, aphasia is not related to the mechanics of speech, but rather the individual's language cognition. However, it is possible for a person can have both problems, e.g. in the case of a hemorrhage damaging a large area of the brain. An individual's language abilities incorporate the socially shared set of rules, as well as the thought processes that go behind communication (as it affects both verbal and nonverbal language). Aphasia is not a result of other peripheral motor or sensory difficulty, such as paralysis affecting the speech muscles, or a general hearing impairment.

Neurodevelopmental forms of auditory processing disorder are differentiable from aphasia in that aphasia is by definition caused by acquired brain injury, but acquired epileptic aphasia has been viewed as a form of APD.

Signs and symptoms
People with aphasia may experience any of the following behaviors due to an acquired brain injury, although some of these symptoms may be due to related or concomitant problems, such as dysarthria or apraxia, and not primarily due to aphasia. Aphasia symptoms can vary based on the location of damage in the brain. Signs and symptoms may or may not be present in individuals with aphasia and may vary in severity and level of disruption to communication. Often those with aphasia may have a difficulty with naming objects, so they might use words such as thing or point at the objects. When asked to name a pencil they may say it is a "thing used to write".

 * Inability to comprehend language
 * Inability to pronounce, not due to muscle paralysis or weakness
 * Inability to form words
 * Inability to recall words (anomia)
 * Poor enunciation
 * Excessive creation and use of personal neologisms
 * Inability to repeat a phrase
 * Persistent repetition of one syllable, word, or phrase (stereotypies, recurrent/recurring utterances/speech automatism) also known as perseveration.
 * Paraphasia (substituting letters, syllables or words)
 * Agrammatism (inability to speak in a grammatically correct fashion)
 * speaking in incomplete sentences
 * Inability to read
 * Inability to write
 * Limited verbal output
 * Difficulty in naming
 * Speech disorder
 * Speaking gibberish
 * Inability to follow or understand simple requests

Related behaviors
Given the previously stated signs and symptoms, the following behaviors are often seen in people with aphasia as a result of attempted compensation for incurred speech and language deficits:
 * Self-repairs: Further disruptions in fluent speech as a result of mis-attempts to repair erred speech production.
 * Struggle in non-fluent aphasias: A severe increase in expelled effort to speak after a life where talking and communicating was an ability that came so easily can cause visible frustration.
 * Preserved and automatic language: A behavior in which some language or language sequences that were used so frequently prior to onset are still produced with more ease than other language post onset.

Subcortical

 * Subcortical aphasia's characteristics and symptoms depend upon the site and size of subcortical lesion. Possible sites of lesions include the thalamus, internal capsule, and basal ganglia.

Cognitive deficits
While aphasia has traditionally been described in terms of language deficits, there is increasing evidence that many people with aphasia commonly experience co-occurring non-linguistic cognitive deficits in areas such as attention, memory, executive functions and learning. By some accounts, cognitive deficits, such as attention and working memory constitute the underlying cause of language impairment in people with aphasia. Others suggest that cognitive deficits often co-occur but are comparable to cognitive deficits in stroke patients without aphasia and reflect general brain dysfunction following injury. Whilst it has been shown that cognitive neural networks support language reorganisation after stroke, The degree to which deficits in attention and other cognitive domains underlie language deficits in aphasia is still unclear.

In particular, people with aphasia often demonstrate short-term and working memory deficits. These deficits can occur in both the verbal domain as well as the visuospatial domain. Furthermore, these deficits are often associated with performance on language specific tasks such as naming, lexical processing, and sentence comprehension, and discourse production. Other studies have found that most, but not all people with aphasia demonstrate performance deficits on tasks of attention, and their performance on these tasks correlate with language performance and cognitive ability in other domains. Even patients with mild aphasia, who score near the ceiling on tests of language often demonstrate slower response times and interference effects in non-verbal attention abilities.

In addition to deficits in short-term memory, working memory, and attention, people with aphasia can also demonstrate deficits in executive function. For instance, people with aphasia may demonstrate deficits in initiation, planning, self-monitoring, and cognitive flexibility. Other studies have found that people with aphasia demonstrate reduced speed and efficiency during completion executive function assessments.

Regardless of their role in the underlying nature of aphasia, cognitive deficits have a clear role in the study and rehabilitation of aphasia. For instance, the severity of cognitive deficits in people with aphasia has been associated with lower quality of life, even more so than the severity of language deficits. Furthermore, cognitive deficits may influence the learning process of rehabilitation and language treatment outcomes in aphasia. Non-linguistic cognitive deficits have also been the target of interventions directed at improving language ability, though outcomes are not definitive. While some studies have demonstrated language improvement secondary to cognitively-focused treatment, others have found little evidence that the treatment of cognitive deficits in people with aphasia has an influence on language outcomes.

One important caveat in the measurement and treatment of cognitive deficits in people with aphasia is the degree to which assessments of cognition rely on language abilities for successful performance. Most studies have attempted to circumvent this challenge by utilizing non-verbal cognitive assessments to evaluate cognitive ability in people with aphasia. However, the degree to which these tasks are truly "non-verbal" and not mediated by language is unclear. For instance, Wall et al. found that language and non-linguistic performance was related, except when non-linguistic performance was measured by "real life" cognitive tasks.

Causes
Aphasia is most often caused by stroke, where about a quarter of patients who experience an acute stroke develop aphasia. However, any disease or damage to the parts of the brain that control language can cause aphasia. Some of these can include brain tumors, traumatic brain injury, epilepsy and progressive neurological disorders. In rare cases, aphasia may also result from herpesviral encephalitis. The herpes simplex virus affects the frontal and temporal lobes, subcortical structures, and the hippocampal tissue, which can trigger aphasia. In acute disorders, such as head injury or stroke, aphasia usually develops quickly. When caused by brain tumor, infection, or dementia, it develops more slowly.

Substantial damage to tissue anywhere within the region shown in blue (on the figure in the infobox above) can potentially result in aphasia. Aphasia can also sometimes be caused by damage to subcortical structures deep within the left hemisphere, including the thalamus, the internal and external capsules, and the caudate nucleus of the basal ganglia. The area and extent of brain damage or atrophy will determine the type of aphasia and its symptoms. A very small number of people can experience aphasia after damage to the right hemisphere only. It has been suggested that these individuals may have had an unusual brain organization prior to their illness or injury, with perhaps greater overall reliance on the right hemisphere for language skills than in the general population.

Primary progressive aphasia (PPA), while its name can be misleading, is actually a form of dementia that has some symptoms closely related to several forms of aphasia. It is characterized by a gradual loss in language functioning while other cognitive domains are mostly preserved, such as memory and personality. PPA usually initiates with sudden word-finding difficulties in an individual and progresses to a reduced ability to formulate grammatically correct sentences (syntax) and impaired comprehension. The etiology of PPA is not due to a stroke, traumatic brain injury (TBI), or infectious disease; it is still uncertain what initiates the onset of PPA in those affected by it.

Epilepsy can also include transient aphasia as a prodromal or episodic symptom. However, the repeated seizure activity within language regions may also lead to chronic, and progressive aphasia. Aphasia is also listed as a rare side-effect of the fentanyl patch, an opioid used to control chronic pain.

Neuroimaging methods
Magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) are the most common neuroimaging tools used in identifying aphasia and studying the extent of damage in the loss of language abilities. This is done by doing MRI scans and locating the extent of lesions or damage within brain tissue, particularly within areas of the left frontal and temporal regions- where a lot of language related areas lie. In fMRI studies a language related task is often completed and then the BOLD image is analyzed. If there are lower than normal BOLD responses that indicate a lessening of blood flow to the affected area and can show quantitatively that the cognitive task is not being completed.

There are limitations to the use of fMRI in aphasic patients particularly. Because a high percentage of aphasic patients develop it because of stroke there can be infarct present which is the total loss of blood flow. This can be due to the thinning of blood vessels or the complete blockage of it. This is important in fMRI as it relies on the BOLD response (the oxygen levels of the blood vessels), and this can create a false hyporesponse upon fMRI study. Due to the limitations of fMRI such as a lower spatial resolution, it can show that some areas of the brain are not active during a task when they in reality are. Additionally, with stroke being the cause of many cases of aphasia the extent of damage to brain tissue can be difficult to quantify therefore the effects of stroke brain damage on the functionality of the patient can vary.

Neural substrates of aphasia subtypes

MRI is often used to predict or confirm the subtype of aphasia present. Researchers compared 3 subtypes of aphasia- nonfluent-variant primary progressive aphasia (nfPPA), logopenic-variant primary progressive aphasia (lvPPA), and semantic-variant primary progressive aphasia (svPPA), with primary progressive aphasia (PPA) and Alzheimer's disease. This was done by analyzing the MRIs of patients with each of the subsets of PPA. Images which compare subtypes of aphasia as well as for finding the extent of lesions are generated by overlapping images of different participant's brains (if applicable) and isolating areas of lesions or damage using third-party software such as MRIcron. MRI has also been used to study the relationship between the type of aphasia developed and the age of the person with aphasia. It was found that patients with fluent aphasia are on average older than people with non-fluent aphasia. It was also found that among patients with lesions confined to the anterior portion of the brain an unexpected portion of them presented with fluent aphasia and were remarkably older than those with non-fluent aphasia. This effect was not found when the posterior portion of the brain was studied.

Associated conditions

In a study on the features associated with different disease trajectories in Alzheimer's disease (AD)-related primary progressive aphasia (PPA), it was found that metabolic patterns via PET SPM analysis can help predict progression of total loss of speech and functional autonomy in AD and PPA patients. This was done by comparing an MRI or CT image of the brain and presence of a radioactive biomarker with normal levels in patients without Alzheimer's Disease. Apraxia is another disorder often correlated with aphasia. This is due to a subset of apraxia which affects speech. Specifically, this subset affects the movement of muscles associated with speech production, apraxia and aphasia are often correlated due to the proximity of neural substrates associated with each of the disorders. Researchers concluded that there were 2 areas of lesion overlap between patients with apraxia and aphasia, the anterior temporal lobe and the left inferior parietal lobe.

Treatment and neuroimaging

Evidence for positive treatment outcomes can also be quantified using neuroimaging tools. The use of fMRI and an automatic classifier can help predict language recovery outcomes in stroke patients with 86% accuracy when coupled with age and language test scores. The stimuli tested were sentences both correct and incorrect and the subject had to press a button whenever the sentence was incorrect. The fMRI data collected focused on responses in regions of interest identified by healthy subjects. Recovery from aphasia can also be quantified using diffusion tensor imaging. The accurate fasciculus (AF) connects the right and left superior temporal lobe, premotor regions/posterior inferior frontal gyrus. and the primary motor cortex. In a study which enrolled patients in a speech therapy program, an increase in AF fibers and volume was found in patients after 6-weeks in the program which correlated with long-term improvement in those patients. The results of the experiment are pictured in Figure 2. This implies that DTI can be used to quantify the improvement in patients after speech and language treatment programs are applied.

Classification
Aphasia is best thought of as a collection of different disorders, rather than a single problem. Each individual with aphasia will present with their own particular combination of language strengths and weaknesses. Consequently, it is a major challenge just to document the various difficulties that can occur in different people, let alone decide how they might best be treated. Most classifications of the aphasias tend to divide the various symptoms into broad classes. A common approach is to distinguish between the fluent aphasias (where speech remains fluent, but content may be lacking, and the person may have difficulties understanding others), and the nonfluent aphasias (where speech is very halting and effortful, and may consist of just one or two words at a time).

However, no such broad-based grouping has proven fully adequate, or reliable. There is wide variation among people even within the same broad grouping, and aphasias can be highly selective. For instance, people with naming deficits (anomic aphasia) might show an inability only for naming buildings, or people, or colors. Unfortunately, assessments that characterize aphasia in these groupings have persisted. This is not helpful to people living with aphasia, and provides inaccurate descriptions of an individual pattern of difficulties.

There are typical difficulties with speech and language that come with normal aging as well. As we age, language can become more difficult to process resulting in a slowing of verbal comprehension, reading abilities and more likely word finding difficulties. With each of these, though, unlike some aphasias, functionality within daily life remains intact.

Boston classification

 * Individuals with receptive aphasia (Wernicke's aphasia), also referred to as fluent aphasia, may speak in long sentences that have no meaning, add unnecessary words, and even create new "words" (neologisms). For example, someone with receptive aphasia may say, "delicious taco", meaning "The dog needs to go out so I will take him for a walk". They have poor auditory and reading comprehension, and fluent, but nonsensical, oral and written expression. Individuals with receptive aphasia usually have great difficulty understanding the speech of both themselves and others and are, therefore, often unaware of their mistakes. Receptive language deficits usually arise from lesions in the posterior portion of the left hemisphere at or near Wernicke's area. It is often the result of trauma to the temporal region of the brain, specifically damage to Wernicke's area. Trauma can be the result from an array of problems, however it is most commonly seen as a result of stroke
 * Individuals with expressive aphasia (Broca's aphasia) frequently speak short, meaningful phrases that are produced with great effort. It is thus characterized as a nonfluent aphasia. Affected people often omit small words such as "is", "and", and "the". For example, a person with expressive aphasia may say, "walk dog", which could mean "I will take the dog for a walk", "you take the dog for a walk" or even "the dog walked out of the yard." Individuals with expressive aphasia are able to understand the speech of others to varying degrees. Because of this, they are often aware of their difficulties and can become easily frustrated by their speaking problems. While Broca's aphasia may appear to be solely an issue with language production, evidence suggests that it may be rooted in an inability to process syntactical information. Individuals with expressive aphasia may have a speech automatism (also called recurring or recurrent utterance). These speech automatisms can be repeated lexical speech automatisms; e.g., modalisations ('I can't..., I can't...'), expletives/swearwords, numbers ('one two, one two') or non-lexical utterances made up of repeated, legal but meaningless, consonant-vowel syllables (e.g.., /tan tan/, /bi bi/). In severe cases, the individual may be able to utter only the same speech automatism each time they attempt speech.
 * Individuals with anomic aphasia have difficulty with naming. People with this aphasia may have difficulties naming certain words, linked by their grammatical type (e.g., difficulty naming verbs and not nouns) or by their semantic category (e.g., difficulty naming words relating to photography but nothing else) or a more general naming difficulty. People tend to produce grammatic, yet empty, speech. Auditory comprehension tends to be preserved. Anomic aphasia is the aphasial presentation of tumors in the language zone; it is the aphasial presentation of Alzheimer's disease. Anomic aphasia is the mildest form of aphasia, indicating a likely possibility for better recovery.
 * Individuals with transcortical sensory aphasia, in principle the most general and potentially among the most complex forms of aphasia, may have similar deficits as in receptive aphasia, but their repetition ability may remain intact.
 * Global aphasia is considered a severe impairment in many language aspects since it impacts expressive and receptive language, reading, and writing. Despite these many deficits, there is evidence that has shown individuals benefited from speech language therapy. Even though individuals with global aphasia will not become competent speakers, listeners, writers, or readers, goals can be created to improve the individual's quality of life. Individuals with global aphasia usually respond well to treatment that includes personally relevant information, which is also important to consider for therapy.
 * Individuals with conduction aphasia have deficits in the connections between the speech-comprehension and speech-production areas. This might be caused by damage to the arcuate fasciculus, the structure that transmits information between Wernicke's area and Broca's area. Similar symptoms, however, can be present after damage to the insula or to the auditory cortex. Auditory comprehension is near normal, and oral expression is fluent with occasional paraphasic errors. Paraphasic errors include phonemic/literal or semantic/verbal. Repetition ability is poor. Conduction and transcortical aphasias are caused by damage to the white matter tracts. These aphasias spare the cortex of the language centers but instead create a disconnection between them. Conduction aphasia is caused by damage to the arcuate fasciculus. The arcuate fasciculus is a white matter tract that connects Broca's and Wernicke's areas. People with conduction aphasia typically have good language comprehension, but poor speech repetition and mild difficulty with word retrieval and speech production. People with conduction aphasia are typically aware of their errors. Two forms of conduction aphasia have been described: reproduction conduction aphasia (repetition of a single relatively unfamiliar multisyllabic word) and repetition conduction aphasia (repetition of unconnected short familiar words.
 * Transcortical aphasias include transcortical motor aphasia, transcortical sensory aphasia, and mixed transcortical aphasia. People with transcortical motor aphasia typically have intact comprehension and awareness of their errors, but poor word finding and speech production. People with transcortical sensory and mixed transcortical aphasia have poor comprehension and unawareness of their errors. Despite poor comprehension and more severe deficits in some transcortical aphasias, small studies have indicated that full recovery is possible for all types of transcortical aphasia.

Classical-localizationist approaches
Localizationist approaches aim to classify the aphasias according to their major presenting characteristics and the regions of the brain that most probably gave rise to them. Inspired by the early work of nineteenth-century neurologists Paul Broca and Carl Wernicke, these approaches identify two major subtypes of aphasia and several more minor subtypes:
 * Expressive aphasia (also known as "motor aphasia" or "Broca's aphasia"), which is characterized by halted, fragmented, effortful speech, but well-preserved comprehension relative to expression. Damage is typically in the anterior portion of the left hemisphere, most notably Broca's area. Individuals with Broca's aphasia often have right-sided weakness or paralysis of the arm and leg, because the left frontal lobe is also important for body movement, particularly on the right side.
 * Receptive aphasia (also known as "sensory aphasia" or "Wernicke's aphasia"), which is characterized by fluent speech, but marked difficulties understanding words and sentences. Although fluent, the speech may lack in key substantive words (nouns, verbs, adjectives), and may contain incorrect words or even nonsense words. This subtype has been associated with damage to the posterior left temporal cortex, most notably Wernicke's area. These individuals usually have no body weakness, because their brain injury is not near the parts of the brain that control movement.
 * Conduction aphasia, where speech remains fluent, and comprehension is preserved, but the person may have disproportionate difficulty repeating words or sentences. Damage typically involves the arcuate fasciculus and the left parietal region.
 * Transcortical motor aphasia and transcortical sensory aphasia, which are similar to Broca's and Wernicke's aphasia respectively, but the ability to repeat words and sentences is disproportionately preserved.

Recent classification schemes adopting this approach, such as the Boston-Neoclassical Model, also group these classical aphasia subtypes into two larger classes: the nonfluent aphasias (which encompasses Broca's aphasia and transcortical motor aphasia) and the fluent aphasias (which encompasses Wernicke's aphasia, conduction aphasia and transcortical sensory aphasia). These schemes also identify several further aphasia subtypes, including: anomic aphasia, which is characterized by a selective difficulty finding the names for things; and global aphasia, where both expression and comprehension of speech are severely compromised.

Many localizationist approaches also recognize the existence of additional, more "pure" forms of language disorder that may affect only a single language skill. For example, in pure alexia, a person may be able to write but not read, and in pure word deafness, they may be able to produce speech and to read, but not understand speech when it is spoken to them.

Cognitive neuropsychological approaches
Although localizationist approaches provide a useful way of classifying the different patterns of language difficulty into broad groups, one problem is that most individuals do not fit neatly into one category or another. Another problem is that the categories, particularly the major ones such as Broca's and Wernicke's aphasia, still remain quite broad and do not meaningfully reflect a person's difficulties. Consequently, even amongst those who meet the criteria for classification into a subtype, there can be enormous variability in the types of difficulties they experience.

Instead of categorizing every individual into a specific subtype, cognitive neuropsychological approaches aim to identify the key language skills or "modules" that are not functioning properly in each individual. A person could potentially have difficulty with just one module, or with a number of modules. This type of approach requires a framework or theory as to what skills/modules are needed to perform different kinds of language tasks. For example, the model of Max Coltheart identifies a module that recognizes phonemes as they are spoken, which is essential for any task involving recognition of words. Similarly, there is a module that stores phonemes that the person is planning to produce in speech, and this module is critical for any task involving the production of long words or long strings of speech. Once a theoretical framework has been established, the functioning of each module can then be assessed using a specific test or set of tests. In the clinical setting, use of this model usually involves conducting a battery of assessments, each of which tests one or a number of these modules. Once a diagnosis is reached as to the skills/modules where the most significant impairment lies, therapy can proceed to treat these skills.

Progressive aphasias
Primary progressive aphasia (PPA) is a neurodegenerative focal dementia that can be associated with progressive illnesses or dementia, such as frontotemporal dementia / Pick Complex Motor neuron disease, Progressive supranuclear palsy, and Alzheimer's disease, which is the gradual process of progressively losing the ability to think. Gradual loss of language function occurs in the context of relatively well-preserved memory, visual processing, and personality until the advanced stages. Symptoms usually begin with word-finding problems (naming) and progress to impaired grammar (syntax) and comprehension (sentence processing and semantics). The loss of language before the loss of memory differentiates PPA from typical dementias. People with PPA may have difficulties comprehending what others are saying. They can also have difficulty trying to find the right words to make a sentence. There are three classifications of Primary Progressive Aphasia : Progressive nonfluent aphasia (PNFA), Semantic Dementia (SD), and Logopenic progressive aphasia (LPA).

Progressive Jargon Aphasia is a fluent or receptive aphasia in which the person's speech is incomprehensible, but appears to make sense to them. Speech is fluent and effortless with intact syntax and grammar, but the person has problems with the selection of nouns. Either they will replace the desired word with another that sounds or looks like the original one or has some other connection or they will replace it with sounds. As such, people with jargon aphasia often use neologisms, and may perseverate if they try to replace the words they cannot find with sounds. Substitutions commonly involve picking another (actual) word starting with the same sound (e.g., clocktower – colander), picking another semantically related to the first (e.g., letter – scroll), or picking one phonetically similar to the intended one (e.g., lane – late).

Deaf aphasia
There have been many instances showing that there is a form of aphasia among deaf individuals. Sign languages are, after all, forms of language that have been shown to use the same areas of the brain as verbal forms of language. Mirror neurons become activated when an animal is acting in a particular way or watching another individual act in the same manner. These mirror neurons are important in giving an individual the ability to mimic movements of hands. Broca's area of speech production has been shown to contain several of these mirror neurons resulting in significant similarities of brain activity between sign language and vocal speech communication. People use facial movements to create, what other people perceive, to be faces of emotions. While combining these facial movements with speech, a more full form of language is created which enables the species to interact with a much more complex and detailed form of communication. Sign language also uses these facial movements and emotions along with the primary hand movement way of communicating. These facial movement forms of communication come from the same areas of the brain. When dealing with damages to certain areas of the brain, vocal forms of communication are in jeopardy of severe forms of aphasia. Since these same areas of the brain are being used for sign language, these same, at least very similar, forms of aphasia can show in the Deaf community. Individuals can show a form of Wernicke's aphasia with sign language and they show deficits in their abilities in being able to produce any form of expressions. Broca's aphasia shows up in some people, as well. These individuals find tremendous difficulty in being able to actually sign the linguistic concepts they are trying to express.

Severity
The severity of the type of aphasia varies depending on the size of the stroke. However, there is much variance between how often one type of severity occurs in certain types of aphasia. For instance, any type of aphasia can range from mild to profound. Regardless of the severity of aphasia, people can make improvements due to spontaneous recovery and treatment in the acute stages of recovery. Additionally, while most studies propose that the greatest outcomes occur in people with severe aphasia when treatment is provided in the acute stages of recovery, Robey (1998) also found that those with severe aphasia are capable of making strong language gains in the chronic stage of recovery as well. This finding implies that persons with aphasia have the potential to have functional outcomes regardless of how severe their aphasia may be. While there is no distinct pattern of the outcomes of aphasia based on severity alone, global aphasia typically makes functional language gains, but may be gradual since global aphasia affects many language areas.

Prevention
Aphasia is largely caused by unavoidable instances. However, some precautions can be taken to decrease risk for experiencing one of the two major causes of aphasia: stroke and traumatic brain injury (TBI). To decrease the probability of having an ischemic or hemorrhagic stroke, one should take the following precautions:
 * Exercising regularly
 * Eating a healthy diet, avoiding cholesterol in particular
 * Keeping alcohol consumption low and avoiding tobacco use
 * Controlling blood pressure
 * Going to the emergency room immediately if you begin to experience unilateral extremity (especially leg) swelling, warmth, redness, and/or tenderness as these are symptoms of a deep vein thrombosis which can lead to a stroke

To prevent aphasia due to traumatic injury, one should take precautionary measures when engaging in dangerous activities such as: Additionally, one should always seek medical attention after sustaining head trauma due to a fall or accident. The sooner that one receives medical attention for a traumatic brain injury, the less likely one is to experience long-term or severe effects.
 * Wearing a helmet when operating a bicycle, motor cycle, ATV, or any other moving vehicle that could potentially be involved in an accident
 * Wearing a seatbelt when driving or riding in a car
 * Wearing proper protective gear when playing contact sports, especially American football, rugby, and hockey, or refraining from such activities
 * Minimizing anticoagulant use (including aspirin) if at all possible as they increase the risk of hemorrhage after a head injury

Management
Most acute cases of aphasia recover some or most skills by participating in speech and language therapy. Recovery and improvement can continue for years after the stroke. After the onset of aphasia, there is approximately a six-month period of spontaneous recovery; during this time, the brain is attempting to recover and repair the damaged neurons. Improvement varies widely, depending on the aphasia's cause, type, and severity. Recovery also depends on the person's age, health, motivation, handedness, and educational level.

Speech and language therapy that is higher intensity, higher dose or provided over a long duration of time leads to significantly better functional communication but people might be more likely to drop out of high intensity treatment (up to 15 hours per week). A total of 20–50 hours of speech and language therapy is necessary for the best recovery. The most improvement happens when 2–5 hours of therapy is provided each week over 4–5 days. Recovery is further improved when besides the therapy people practice tasks at home. Speech and language therapy is also effective if it is delivered online through video or by a family member who has been trained by a professional therapist.

Recovery with therapy is also dependent on the recency of stroke and the age of the person. Receiving therapy within a month after the stroke leads to the greatest improvements. 3 or 6 months after the stroke more therapy will be needed but symptoms can still be improved. People with aphasia who are younger than 55 years are the most likely to improve but people older than 75 years can still get better with therapy.

There is no one treatment proven to be effective for all types of aphasias. The reason that there is no universal treatment for aphasia is because of the nature of the disorder and the various ways it is presented. Aphasia is rarely exhibited identically, implying that treatment needs to be catered specifically to the individual. Studies have shown that, although there is no consistency on treatment methodology in literature, there is a strong indication that treatment, in general, has positive outcomes. Therapy for aphasia ranges from increasing functional communication to improving speech accuracy, depending on the person's severity, needs and support of family and friends. Group therapy allows individuals to work on their pragmatic and communication skills with other individuals with aphasia, which are skills that may not often be addressed in individual one-on-one therapy sessions. It can also help increase confidence and social skills in a comfortable setting.

Evidence does not support the use of transcranial direct current stimulation (tDCS) for improving aphasia after stroke. Moderate quality evidence does indicate naming performance improvements for nouns but not verbs using tDCS

Specific treatment techniques include the following:
 * Copy and recall therapy (CART) – repetition and recall of targeted words within therapy may strengthen orthographic representations and improve single word reading, writing, and naming
 * Visual communication therapy (VIC) – the use of index cards with symbols to represent various components of speech
 * Visual action therapy (VAT) – typically treats individuals with global aphasia to train the use of hand gestures for specific items
 * Functional communication treatment (FCT) – focuses on improving activities specific to functional tasks, social interaction, and self-expression
 * Promoting aphasic's communicative effectiveness (PACE) – a means of encouraging normal interaction between people with aphasia and clinicians. In this kind of therapy, the focus is on pragmatic communication rather than treatment itself. People are asked to communicate a given message to their therapists by means of drawing, making hand gestures or even pointing to an object
 * Melodic intonation therapy (MIT) – aims to use the intact melodic/prosodic processing skills of the right hemisphere to help cue retrieval of words and expressive language
 * Centeredness Theory Interview (CTI) - Uses client centered goal formation into the nature of current patient interactions as well as future / desired interactions to improve subjective well-being, cognition and communication.
 * Other – i.e. drawing as a way of communicating, trained conversation partners

Semantic feature analysis (SFA) – a type of aphasia treatment that targets word-finding deficits. It is based on the theory that neural connections can be strengthened by using related words and phrases that are similar to the target word, to eventually activate the target word in the brain. SFA can be implemented in multiple forms such as verbally, written, using picture cards, etc. The SLP provides prompting questions to the individual with aphasia in order for the person to name the picture provided. Studies show that SFA is an effective intervention for improving confrontational naming.

Melodic intonation therapy is used to treat non-fluent aphasia and has proved to be effective in some cases. However, there is still no evidence from randomized controlled trials confirming the efficacy of MIT in chronic aphasia. MIT is used to help people with aphasia vocalize themselves through speech song, which is then transferred as a spoken word. Good candidates for this therapy include people who have had left hemisphere strokes, non-fluent aphasias such as Broca's, good auditory comprehension, poor repetition and articulation, and good emotional stability and memory. An alternative explanation is that the efficacy of MIT depends on neural circuits involved in the processing of rhythmicity and formulaic expressions (examples taken from the MIT manual: "I am fine," "how are you?" or "thank you"); while rhythmic features associated with melodic intonation may engage primarily left-hemisphere subcortical areas of the brain, the use of formulaic expressions is known to be supported by right-hemisphere cortical and bilateral subcortical neural networks.

Systematic reviews support the effectiveness and importance of partner training. According to the National Institute on Deafness and Other Communication Disorders (NIDCD), involving family with the treatment of an aphasic loved one is ideal for all involved, because while it will no doubt assist in their recovery, it will also make it easier for members of the family to learn how best to communicate with them.

When a person's speech is insufficient, different kinds of augmentative and alternative communication could be considered such as alphabet boards, pictorial communication books, specialized software for computers or apps for tablets or smartphones.

When addressing Wernicke's aphasia, according to Bakheit et al. (2007), the lack of awareness of the language impairments, a common characteristic of Wernicke's aphasia, may affect the rate and extent of therapy outcomes. Robey (1998) determined that at least 2 hours of treatment per week is recommended for making significant language gains. Spontaneous recovery may cause some language gains, but without speech-language therapy, the outcomes can be half as strong as those with therapy.

When addressing Broca's aphasia, better outcomes occur when the person participates in therapy, and treatment is more effective than no treatment for people in the acute period. Two or more hours of therapy per week in acute and post-acute stages produced the greatest results. High-intensity therapy was most effective, and low-intensity therapy was almost equivalent to no therapy.

People with global aphasia are sometimes referred to as having irreversible aphasic syndrome, often making limited gains in auditory comprehension, and recovering no functional language modality with therapy. With this said, people with global aphasia may retain gestural communication skills that may enable success when communicating with conversational partners within familiar conditions. Process-oriented treatment options are limited, and people may not become competent language users as readers, listeners, writers, or speakers no matter how extensive therapy is. However, people's daily routines and quality of life can be enhanced with reasonable and modest goals. After the first month, there is limited to no healing to language abilities of most people. There is a grim prognosis leaving 83% who were globally aphasic after the first month they will remain globally aphasic at the first year. Some people are so severely impaired that their existing process-oriented treatment approaches offer no signs of progress, and therefore cannot justify the cost of therapy.

Perhaps due to the relative rareness of conduction aphasia, few studies have specifically studied the effectiveness of therapy for people with this type of aphasia. From the studies performed, results showed that therapy can help to improve specific language outcomes. One intervention that has had positive results is auditory repetition training. Kohn et al. (1990) reported that drilled auditory repetition training related to improvements in spontaneous speech, Francis et al. (2003) reported improvements in sentence comprehension, and Kalinyak-Fliszar et al. (2011) reported improvements in auditory-visual short-term memory.

Individualized service delivery
Intensity of treatment should be individualized based on the recency of stroke, therapy goals, and other specific characteristics such as age, size of lesion, overall health status, and motivation. Each individual reacts differently to treatment intensity and is able to tolerate treatment at different times post-stroke. Intensity of treatment after a stroke should be dependent on the person's motivation, stamina, and tolerance for therapy.

Outcomes
If the symptoms of aphasia last longer than two or three months after a stroke, a complete recovery is unlikely. However, it is important to note that some people continue to improve over a period of years and even decades. Improvement is a slow process that usually involves both helping the individual and family understand the nature of aphasia and learning compensatory strategies for communicating.

After a traumatic brain injury (TBI) or cerebrovascular accident (CVA), the brain undergoes several healing and re-organization processes, which may result in improved language function. This is referred to as spontaneous recovery. Spontaneous recovery is the natural recovery the brain makes without treatment, and the brain begins to reorganize and change in order to recover. There are several factors that contribute to a person's chance of recovery caused by stroke, including stroke size and location. Age, sex, and education have not been found to be very predictive. There is also research pointing to damage in the left hemisphere healing more effectively than the right.

Specific to aphasia, spontaneous recovery varies among affected people and may not look the same in everyone, making it difficult to predict recovery.

Though some cases of Wernicke's aphasia have shown greater improvements than more mild forms of aphasia, people with Wernicke's aphasia may not reach as high a level of speech abilities as those with mild forms of aphasia.

Prevalence
Aphasia affects about two million people in the U.S. and 250,000 people in Great Britain. Nearly 180,000 people acquire the disorder every year in the U.S., 170,000 due to stroke. Any person of any age can develop aphasia, given that it is often caused by a traumatic injury. However, people who are middle aged and older are the most likely to acquire aphasia, as the other etiologies are more likely at older ages. For example, approximately 75% of all strokes occur in individuals over the age of 65. Strokes account for most documented cases of aphasia: 25% to 40% of people who survive a stroke develop aphasia as a result of damage to the language-processing regions of the brain.

History
The first recorded case of aphasia is from an Egyptian papyrus, the Edwin Smith Papyrus, which details speech problems in a person with a traumatic brain injury to the temporal lobe.

During the second half of the 19th century, aphasia was a major focus for scientists and philosophers who were working in the beginning stages of the field of psychology. In medical research, speechlessness was described as an incorrect prognosis, and there was no assumption that underlying language complications existed. Broca and his colleagues were some of the first to write about aphasia, but Wernicke was the first credited to have written extensively about aphasia being a disorder that contained comprehension difficulties. Despite claims of who reported on aphasia first, it was F.J. Gall that gave the first full description of aphasia after studying wounds to the brain, as well as his observation of speech difficulties resulting from vascular lesions. A recent book on the entire history of aphasia is available (Reference: Tesak, J. & Code, C. (2008) Milestones in the History of Aphasia: Theories and Protagonists. Hove, East Sussex: Psychology Press).

Etymology
Aphasia is from Greek a- ("without", negative prefix) + phásis (φάσις, "speech").

The word aphasia comes from the word ἀφασία aphasia, in Ancient Greek, which means "speechlessness", derived from ἄφατος aphatos, "speechless" from ἀ- a-, "not, un" and φημί phemi, "I speak".

Further research
Research is currently being done using functional magnetic resonance imaging (fMRI) to witness the difference in how language is processed in normal brains vs aphasic brains. This will help researchers to understand exactly what the brain must go through in order to recover from Traumatic Brain Injury (TBI) and how different areas of the brain respond after such an injury.

Another intriguing approach being tested is that of drug therapy. Research is in progress that will hopefully uncover whether or not certain drugs might be used in addition to speech-language therapy in order to facilitate recovery of proper language function. It's possible that the best treatment for Aphasia might involve combining drug treatment with therapy, instead of relying on one over the other.

One other method being researched as a potential therapeutic combination with speech-language therapy is brain stimulation. One particular method, Transcranial Magnetic Stimulation (TMS), alters brain activity in whatever area it happens to stimulate, which has recently led scientists to wonder if this shift in brain function caused by TMS might help people re-learn language. Another type of external brain stimulation is transcranial Direct Current Stimulation (tDCS), but existing research has not shown it to be useful for improving aphasia after a stroke.

title: Aphasia


text:
Aorta

The aorta (: aortas or aortae) is the main and largest artery in the human body, originating from the left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at the aortic bifurcation into two smaller arteries (the common iliac arteries). The aorta distributes oxygenated blood to all parts of the body through the systemic circulation.

Sections
In anatomical sources, the aorta is usually divided into sections.

One way of classifying a part of the aorta is by anatomical compartment, where the thoracic aorta (or thoracic portion of the aorta) runs from the heart to the diaphragm. The aorta then continues downward as the abdominal aorta (or abdominal portion of the aorta) from the diaphragm to the aortic bifurcation.

Another system divides the aorta with respect to its course and the direction of blood flow. In this system, the aorta starts as the ascending aorta, travels superiorly from the heart, and then makes a hairpin turn known as the aortic arch. Following the aortic arch, the aorta then travels inferiorly as the descending aorta. The descending aorta has two parts. The aorta begins to descend in the thoracic cavity and is consequently known as the thoracic aorta. After the aorta passes through the diaphragm, it is known as the abdominal aorta. The aorta ends by dividing into two major blood vessels, the common iliac arteries and a smaller midline vessel, the median sacral artery.

Ascending aorta
The ascending aorta begins at the opening of the aortic valve in the left ventricle of the heart. It runs through a common pericardial sheath with the pulmonary trunk. These two blood vessels twist around each other, causing the aorta to start out posterior to the pulmonary trunk, but end by twisting to its right and anterior side. The transition from ascending aorta to aortic arch is at the pericardial reflection on the aorta.

At the root of the ascending aorta, the lumen has small pockets between the cusps of the aortic valve and the wall of the aorta, which are called the aortic sinuses or the sinuses of Valsalva. The left aortic sinus contains the origin of the left coronary artery and the right aortic sinus likewise gives rise to the right coronary artery. Together, these two arteries supply the heart. The posterior aortic sinus does not give rise to a coronary artery. For this reason the left, right and posterior aortic sinuses are also called left-coronary, right-coronary and non-coronary sinuses.

Aortic arch
The aortic arch loops over the left pulmonary artery and the bifurcation of the pulmonary trunk, to which it remains connected by the ligamentum arteriosum, a remnant of the fetal circulation that is obliterated a few days after birth. In addition to these blood vessels, the aortic arch crosses the left main bronchus. Between the aortic arch and the pulmonary trunk is a network of autonomic nerve fibers, the cardiac plexus or aortic plexus. The left vagus nerve, which passes anterior to the aortic arch, gives off a major branch, the recurrent laryngeal nerve, which loops under the aortic arch just lateral to the ligamentum arteriosum. It then runs back to the neck.

The aortic arch has three major branches: from proximal to distal, they are the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. The brachiocephalic trunk supplies the right side of the head and neck as well as the right arm and chest wall, while the latter two together supply the left side of the same regions.

The aortic arch ends, and the descending aorta begins at the level of the intervertebral disc between the fourth and fifth thoracic vertebrae.

Thoracic aorta
The thoracic aorta gives rise to the intercostal and subcostal arteries, as well as to the superior and inferior left bronchial arteries and variable branches to the esophagus, mediastinum, and pericardium. Its lowest pair of branches are the superior phrenic arteries, which supply the diaphragm, and the subcostal arteries for the twelfth rib.

Abdominal aorta
The abdominal aorta begins at the aortic hiatus of the diaphragm at the level of the twelfth thoracic vertebra. It gives rise to lumbar and musculophrenic arteries, renal and middle suprarenal arteries, and visceral arteries (the celiac trunk, the superior mesenteric artery and the inferior mesenteric artery). It ends in a bifurcation into the left and right common iliac arteries. At the point of the bifurcation, there also springs a smaller branch, the median sacral artery.

Development
The ascending aorta develops from the outflow tract, which initially starts as a single tube connecting the heart with the aortic arches (which will form the great arteries) in early development but is then separated into the aorta and the pulmonary trunk.

The aortic arches start as five pairs of symmetrical arteries connecting the heart with the dorsal aorta, and then undergo a significant remodelling to form the final asymmetrical structure of the great arteries, with the 3rd pair of arteries contributing to the common carotids, the right 4th forming the base and middle part of the right subclavian artery and the left 4th being the central part of the aortic arch. The smooth muscle of the great arteries and the population of cells that form the aorticopulmonary septum that separates the aorta and pulmonary artery is derived from cardiac neural crest. This contribution of the neural crest to the great artery smooth muscle is unusual as most smooth muscle is derived from mesoderm. In fact the smooth muscle within the abdominal aorta is derived from mesoderm, and the coronary arteries, which arise just above the semilunar valves, possess smooth muscle of mesodermal origin. A failure of the aorticopulmonary septum to divide the great vessels results in persistent truncus arteriosus.

Microanatomy
The aorta is an elastic artery, and as such is quite distensible. The aorta consists of a heterogeneous mixture of smooth muscle, nerves, intimal cells, endothelial cells, immune cells, fibroblast-like cells, and a complex extracellular matrix. The vascular wall is subdivided into three layers known as the tunica externa, tunica media, and tunica intima. The aorta is covered by an extensive network of tiny blood vessels called vasa vasorum, which feed the tunica externa and tunica media, the outer layers of the aorta. The aortic arch contains baroreceptors and chemoreceptors that relay information concerning blood pressure and blood pH and carbon dioxide levels to the medulla oblongata of the brain. This information along with information from baroreceptors and chemoreceptors located elsewhere is processed by the brain and the autonomic nervous system mediates appropriate homeostatic responses.

Within the tunica media, smooth muscle and the extracellular matrix are quantitatively the largest components, these are arranged concentrically as musculoelastic layers (the elastic lamella) in mammals. The elastic lamella, which comprise smooth muscle and elastic matrix, can be considered as the fundamental structural unit of the aorta and consist of elastic fibers, collagens (predominately type III), proteoglycans, and glycoaminoglycans. The elastic matrix dominates the biomechanical properties of the aorta. The smooth muscle component, while contractile, does not substantially alter the diameter of the aorta, but rather serves to increase the stiffness and viscoelasticity of the aortic wall when activated.

Variation
Variations may occur in the location of the aorta, and the way in which arteries branch off the aorta. The aorta, normally on the left side of the body, may be found on the right in dextrocardia, in which the heart is found on the right, or situs inversus, in which the location of all organs are flipped.

Variations in the branching of individual arteries may also occur. For example, the left vertebral artery may arise from the aorta, instead of the left common carotid artery.

In patent ductus arteriosus, a congenital disorder, the fetal ductus arteriosus fails to close, leaving an open vessel connecting the pulmonary artery to the proximal descending aorta.

Function
The aorta supplies all of the systemic circulation, which means that the entire body, except for the respiratory zone of the lung, receives its blood from the aorta. Broadly speaking, branches from the ascending aorta supply the heart; branches from the aortic arch supply the head, neck, and arms; branches from the thoracic descending aorta supply the chest (excluding the heart and the respiratory zone of the lung); and branches from the abdominal aorta supply the abdomen. The pelvis and legs get their blood from the common iliac arteries.

Blood flow and velocity
The contraction of the heart during systole is responsible for ejection and creates a (pulse) wave that is propagated down the aorta, into the arterial tree. The wave is reflected at sites of impedance mismatching, such as bifurcations, where reflected waves rebound to return to semilunar valves and the origin of the aorta. These return waves create the dicrotic notch displayed in the aortic pressure curve during the cardiac cycle as these reflected waves push on the aortic semilunar valve. With age, the aorta stiffens such that the pulse wave is propagated faster and reflected waves return to the heart faster before the semilunar valve closes, which raises the blood pressure. The stiffness of the aorta is associated with a number of diseases and pathologies, and noninvasive measures of the pulse wave velocity are an independent indicator of hypertension. Measuring the pulse wave velocity (invasively and non-invasively) is a means of determining arterial stiffness. Maximum aortic velocity may be noted as Vmax or less commonly as AoVmax.

Mean arterial pressure (MAP) is highest in the aorta, and the MAP decreases across the circulation from aorta to arteries to arterioles to capillaries to veins back to atrium. The difference between aortic and right atrial pressure accounts for blood flow in the circulation. When the left ventricle contracts to force blood into the aorta, the aorta expands. This stretching gives the potential energy that will help maintain blood pressure during diastole, as during this time the aorta contracts passively. This Windkessel effect of the great elastic arteries has important biomechanical implications. The elastic recoil helps conserve the energy from the pumping heart and smooth out the pulsatile nature created by the heart. Aortic pressure is highest at the aorta and becomes less pulsatile and lower pressure as blood vessels divide into arteries, arterioles, and capillaries such that flow is slow and smooth for gases and nutrient exchange.

Clinical significance
Central aortic blood pressure has frequently been shown to have greater prognostic value and to show a more accurate response to antihypertensive drugs than has peripheral blood pressure.

 * Aortic aneurysm – mycotic, bacterial (e.g. syphilis), senile, genetic, associated with valvular heart disease
 * Aortic coarctation – pre-ductal, post-ductal
 * Aortic dissection
 * Aortic stenosis
 * Abdominal aortic aneurysm
 * Aortitis, inflammation of the aorta that can be seen in trauma, infections, and autoimmune disease
 * Atherosclerosis
 * Ehlers–Danlos syndrome
 * Marfan syndrome
 * Trauma, such as traumatic aortic rupture, most often thoracic and distal to the left subclavian artery and often quickly fatal
 * Transposition of the great vessels, see also dextro-Transposition of the great arteries and levo-Transposition of the great arteries

Other animals
All amniotes have a broadly similar arrangement to that of humans, albeit with a number of individual variations. In fish, however, there are two separate vessels referred to as aortas. The ventral aorta carries de-oxygenated blood from the heart to the gills; part of this vessel forms the ascending aorta in tetrapods (the remainder forms the pulmonary artery). A second, dorsal aorta carries oxygenated blood from the gills to the rest of the body and is homologous with the descending aorta of tetrapods. The two aortas are connected by a number of vessels, one passing through each of the gills. Amphibians also retain the fifth connecting vessel, so that the aorta has two parallel arches.

History
The word aorta stems from the Late Latin aorta from Classical Greek aortē (ἀορτή), from aeirō, "I lift, raise" (ἀείρω) This term was first applied by Aristotle when describing the aorta and describes accurately how it seems to be "suspended" above the heart.

The function of the aorta is documented in the Talmud, where it is noted as one of three major vessels entering or leaving the heart, and where perforation is linked to death.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Aorta


text:
Abimelech

Abimelech (also spelled Abimelek or Avimelech; ) was the generic name given to all Philistine kings in the Hebrew Bible from the time of Abraham through King David. In the Book of Judges, Abimelech, son of Gideon, of the Tribe of Manasseh, is proclaimed king of Shechem after the death of his father.

Etymology
The name or title Abimelech is formed from Hebrew words for "father" and "king," and may be interpreted in a variety of ways, including "Father-King", "My father is king," or "Father of a king." In the Pentateuch, it is used as a title for kings in the land of Canaan.

Abimelech can be translated in Arabic as well into "My father is king", "My father is owner" or "Father of a king," where Abi (أبي) means father or my father while malek (ملك) means king or mālek (مالك) for owner.

At the time of the Amarna tablets (mid-14th century BC), there was an Egyptian governor of Tyre similarly named Abimilki,

Abimelech of Gerar
Abimelech was most prominently the name of a polytheistic king of Gerar who is mentioned in two of the three wife–sister narratives in the Book of Genesis, in connection with both Abraham and Isaac.

King Abimelech of Gerar also appears in an extra-biblical tradition recounted in texts such as the Arabic Apocalypse of Peter, the Cave of Treasures and the Conflict of Adam and Eve with Satan, as one of twelve regional kings in Abraham's time said to have built the city of Jerusalem for Melchizedek.

Abimelech son of Jerubbaal/Gideon
The Book of Judges mentions Abimelech, son of judge Gideon (also known as Jerubbaal). According to the biblical narrative, Abimelech was an extremely conniving and evil person. He persuaded his mother's brothers to encourage the people of Shechem to back him in a plot to overthrow his family rule and make him sole ruler.

After slaying all but one of his seventy brothers, Abimelech was crowned king. The brother who escaped, Jotham youngest son of Jerrubaal, made a pronouncement against Abimelech and those who had crowned him. The curse was that if they had not dealt righteously with the family of Jerrubaal, then fire would come against Abimelech from the people of Shechem and fire would come out of Abimelech against the people who had backed him in this bloody coup. After Abimelech ruled for three years, the pronouncement came through. The people of Shechem set robbers to lie in wait of any goods or money headed to Abimelech and steal everything. Then Gaal Son of Ebed went to Shechem and drunkenly bragged that he would remove Abimelech from the throne. Zebul, ruler of Shechem, sent word to Abimelech along with a battle strategy. Once Zebul taunted Gaal into fighting Abimelech, he shut Gaal and his brethren out of the city.

Abimelech then slew the field workers that came out of the city of Shechem the next day. When he heard that the people of Shechem had locked themselves in a strong tower, he and his men set fire to it, killing about a thousand men and women.

After this, Abimelech went to Thebez and camped against it. When he went close to the tower in Thebez to set it on fire, a woman dropped an upper millstone on Abimelech's head. He did not want to be known as having been killed by a woman, so he asked his armour bearer to run him through with a sword. His place of death is cited as being Thebez.

Russian use
Avimelekh (Авимеле́х) is a Russian male first name derived from Abimelech. It was included into various, often handwritten, church calendars throughout the 17th–19th centuries, but was omitted from the official Synodal Menologium at the end of the 19th century.

Other people with this name
Apart from the king (or kings) of Gerar, the Bible also records this name for: Other literary references include:
 * The father of Abiathar, and high priest in the time of David. In the parallel passage, the name is given as Ahimelech; most authorities consider this the more correct reading.
 * The king of Gath better known as Achish, referred to as Abimelech or Achimelech in the title of Psalm 34.
 * The husband of Naomi, and father of Mahlon and Chilion who leaves Bethlehem and dies in the land of Moab, in the Hebrew, his name is given as Elimelek, which is likely the correct reading.
 * Abimélech, Satrap of Gaza is a character baritone in Camille Saint-Saëns' Samson and Delilah.

title: Abimelech


text:
Andrew Tridgell

Andrew "Tridge" Tridgell (born 28 February 1967) is an Australian computer programmer. He is the author of and a contributor to the Samba file server, and co-inventor of the rsync algorithm.

He has analysed complex proprietary protocols and algorithms, to allow compatible free and open source software implementations.

Projects
Tridgell was a major developer of the Samba software, analyzing the Server Message Block protocol used for workgroup and network file sharing by Microsoft Windows products. He developed the talloc hierarchical memory allocator, originally as part of Samba.

For his PhD dissertation, he co-developed rsync, including the rsync algorithm, a highly efficient file transfer and synchronisation tool. He was also the original author of rzip, which uses a similar algorithm to rsync. He developed spamsum, based on locality-sensitive hashing algorithms.

He is the author of KnightCap, a reinforcement-learning based chess engine.

Tridgell was also a leader in hacking the TiVo to make it work in Australia, which uses the PAL video format.

In April 2005, Tridgell tried to produce free software (now known as SourcePuller) that interoperated with the BitKeeper source code repository. This was cited as the reason that BitMover revoked a license allowing Linux developers free use of their BitKeeper product. Linus Torvalds, the creator of the Linux kernel, and Tridgell were thus involved in a public debate about the events, in which Tridgell stated that, not having bought or owned BitKeeper – and thus having never agreed to its license – he could not violate it, and was analyzing the protocol ethically, as he had done with Samba. Tridgell's involvement in the project resulted in Torvalds accusing him of playing dirty tricks with BitKeeper. Tridgell claimed his analysis started with simply telneting to a BitKeeper server and typing.

In 2011 Tridgell became involved with the software development of ArduPilot Mega, an open source Arduino-based UAV controller board, working on an entry with CanberraUAV for the UAV Challenge Outback Rescue.

Academic achievements
Tridgell completed a PhD at the Computer Sciences Laboratory of the Australian National University. His original doctorate work was in the area of speech recognition but was never completed. His submitted dissertation 'Efficient Algorithms for Sorting and Synchronization' was based on his work on the rsync algorithm.

Awards and honours

 * In October 2003, The Bulletin magazine judged Tridgell to be Australia's smartest Information and Communications Technology person.
 * In July 2008, Tridgell was named "Best Interoperator" at the Google–O'Reilly Open Source Awards, for his work on Samba and rsync.
 * Tridgell (along with Jeremy Allison and Volker Lendecke) has been called a "guru in its traditional Indian meaning" by IT writer, Sam Varghese.
 * On 11 December 2018, Tridgell was awarded the degree of Doctor of Science (Honoris Causa) by the Australian National University, for authoring Samba, co-inventing rsync; and contributions to free and open source software.
 * On 26 January 2020, Tridgell was awarded the Medal (OAM) of the Order of Australia in the General Division for service to Information Technology. The biographical notes for the award noted his contributions to software development and education including his work on rsync, Samba, ArduPilot, MAVProxy as well as teaching at the Australian National University.

title: Andrew Tridgell


text:
Applesoft BASIC

Applesoft BASIC is a dialect of Microsoft BASIC, developed by Marc McDonald and Ric Weiland, supplied with Apple II computers. It supersedes Integer BASIC and is the BASIC in ROM in all Apple II series computers after the original Apple II model. It is also referred to as FP BASIC (from floating point) because of the Apple DOS command  used to invoke it, instead of   for Integer BASIC.

Applesoft BASIC was supplied by Microsoft and its name is derived from the names of both Apple Computer and Microsoft. Apple employees, including Randy Wigginton, adapted Microsoft's interpreter for the Apple II and added several features. The first version of Applesoft was released in 1977 on cassette tape and lacked proper support for high-resolution graphics. Applesoft II, which was made available on cassette and disk and in the ROM of the Apple II Plus and subsequent models, was released in 1978. It is this latter version, which has some syntax differences and support for the Apple II high-resolution graphics modes, that is usually synonymous with the term "Applesoft."

A compiler for Applesoft BASIC, TASC (The Applesoft Compiler), was released by Microsoft in 1981.

History
When Steve Wozniak wrote Integer BASIC for the Apple II, he did not implement support for floating-point arithmetic because he was primarily interested in writing games, a task for which integers alone were sufficient. In 1976, Microsoft had developed Microsoft BASIC for the MOS Technology 6502, but at the time there was no production computer that used it. Upon learning that Apple had a 6502 machine, Microsoft asked if the company were interested in licensing BASIC, but Steve Jobs replied that Apple already had one.

The Apple II was unveiled to the public at the West Coast Computer Faire in April 1977 and became available for sale in June. One of the most common customer complaints about the computer was BASIC's lack of floating-point math. Making things more problematic was that the rival Commodore PET personal computer had a floating point-capable BASIC interpreter from the beginning. As Wozniak—the only person who understood Integer BASIC well enough to add floating point features—was busy with the Disk II drive and controller and with Apple DOS, Apple turned to Microsoft.

Apple reportedly obtained an eight-year license for Applesoft BASIC from Microsoft for a flat fee of $31,000, renewing it in 1985 through an arrangement that gave Microsoft the rights and source code for Apple's Macintosh version of BASIC. Applesoft was designed to be backwards-compatible with Integer BASIC and uses the core of Microsoft's 6502 BASIC implementation, which includes using the GET command for detecting key presses and not requiring any spaces on program lines. While Applesoft BASIC is slower than Integer BASIC, it has many features that the older BASIC lacks:

 * Atomic strings: A string is no longer an array of characters (as in Integer BASIC and C); it is instead a garbage-collected object (as in Scheme and Java). This allows for string arrays; DIM A$(10) creates an array of eleven string variables numbered 0–10.
 * Multidimensional arrays (numbers or strings)
 * Single-precision floating-point variables with an 8-bit exponent and a 31-bit significand and improved math capabilities, including trigonometry and logarithmic functions
 * Commands for high-resolution graphics
 * statements, with  and   commands, for representing numerical and string values in quantity
 * ,, and   functions for converting between string and numeric types (both languages did have the   function)
 * User-defined functions: simple one-line functions written in BASIC, with a single parameter
 * Error-trapping: allowing BASIC programs to handle unexpected errors via subroutine written in BASIC

Conversely, Applesoft lacks the  (remainder) operator from Integer BASIC.

Adapting BASIC for the Apple II was a tedious job as Apple received a source listing for Microsoft 6502 BASIC which proved to be buggy and also required the addition of Integer BASIC commands. Since Apple had no 6502 assembler on hand, the development team was forced to send the source code over the phone lines to Call Computer, an outfit that offered compiler services. This was an extremely tedious, slow process and after Call Computer lost the source code due to an equipment malfunction, one of the programmers, Cliff Huston, used his own IMSAI 8080 computer to cross assemble the BASIC source.

Features
Applesoft is similar to Commodore's BASIC 2.0 aside from features inherited from Integer BASIC. There are a few minor differences such as Applesoft's lack of bitwise operators; otherwise most BASIC programs that do not use hardware-dependent features will run on both BASICs.

The PR# statement redirects output to an expansion card, and IN# redirects input from an expansion card. The slot number of the card is specified after the PR# or IN# within the statement. The computer locks-up if there is no card present in the slot. PR#0 restores output to the 40 column screen and IN#0 to the keyboard.

The PR# statement can be used to redirect output to the printer (e.g. 10 PR#x:PRINT"Hello!") where x is the slot number containing the printer port card. To send a BASIC program listing to the printer, the user types PR#x:LIST.

Using PR# on a slot with a disk drive (usually in slot 6) causes Applesoft to boot the disk drive. Using PR# on a slot with an 80 column card (usually in slot 3) switches to 80 column text mode.

As with Commodore BASIC, numeric variables are stored as 40-bit floating point; each variable requires five bytes of memory. The programmer may designate variables as integer by following them with a percent sign, in which case they use two bytes and are limited to a range of -32768 to 32767; however BASIC internally converts them back to floating point when performing calculations, while each percent sign also takes an additional byte of program code, so in practice this feature is only useful for reducing the memory usage of large array variables, as it offers no performance benefit.

The RND function generates a pseudorandom fractional number between 0 and 1. RND(0) returns the most recently generated random number. RND with a negative number will jump to a point in the sequence determined by the particular negative number used. RND with any positive value generates the next number in the sequence, not dependent on the actual value given.

Like other implementations of Microsoft BASIC, Applesoft discards spaces (outside of strings and comments) on program lines. adds spaces when displaying code for the sake of readability. Since LIST adds a space before and after every tokenized keyword, it often produces two spaces in a row where one would suffice for readability.

The default prompt for  is a question mark. does not add a leading space in front of numbers.

Limitations
Through several early models of the Apple II, Applesoft BASIC did not support the use of lowercase letters in programs, except in strings. is a valid command but  and   result in a syntax error.

Applesoft lacks several commands and functions common to most of the non-6502 Microsoft BASIC interpreters, such as:
 * (search for a substring in a string)
 * (format numbers in printed output)
 * (check for a keypress without stopping the program; although a PEEK to location $C000 achieves this action)
 * (output to a printer instead of the screen)

Applesoft does not have commands for file or disk handling, other than to save and load programs via cassette tape. The Apple II disk operating system, known simply as DOS, augments the language to provide such abilities.

Only the first two letters of variables names are significant. For example, "LOW" and "LOSS" are treated as the same variable, and attempting to assign a value to "LOSS" overwrites any value assigned to "LOW". A programmer also has to avoid consecutive letters that are Applesoft commands or operations. The name "SCORE" for a variable is interpreted as containing the  Boolean operator, rendered as. "BACKGROUND" contains, the command to invoke the low-resolution graphics mode, and results in a syntax error.

Sound and graphics
The only sound support is the option to  an ASCII bell character to sound the system alert beep, and a   command to click the speaker. The language is not fast enough to produce more than a baritone buzz from repeated clicks. Programs can, however, store a machine-language routine to be called to generate electronic musical tones spanning several octaves.

Applesoft supports drawing in the Apple II's low resolution and high resolution modes. There are commands to plot pixels and draw horizontal and vertical lines in low resolution. High resolution allows arbitrary lines and vector-based shape tables for drawing scaled and rotated objects. The only provision for mixing text and graphics is the four lines of text at the bottom of a graphic display.

Beginning with the Apple IIe, a "double-high resolution" mode became available on machines with 128k of memory. This mode essentially duplicates the resolution of the original high resolution mode, but including all 16 colors of the low resolution palette. Applesoft does not provide direct support for this mode. Apple IIGS-specific modes are likewise not supported.

Extensions
Applesoft BASIC can be extended by two means: the ampersand (&) command and the USR function. These are two features that call low-level machine-language routines stored in memory, which is useful for routines that need to be fast or require direct access to arbitrary functions or data in memory. The USR function takes one argument, and can be programmed to derive and return a calculated function value to be used in a numerical expression. & is effectively a shorthand for CALL, with an address that is predefined. By calling routines in the Applesoft ROM, it is possible for ampersand routines to parse values that follow the ampersand. Numerous third-party commercial packages were available to extend Applesoft using ampersand routines.

Bugs
A deficiency with error-trapping via  means that the system stack is not reset if an error-handling routine does not invoke , potentially leading to a crash. The built-in pseudorandom number generator function  is capable of producing a predictable series of outputs due to the manner in which the generator is seeded when first powering on. This behavior is contrary to how Apple's documentation describes the function.

Performance
Wozniak originally referred to his Integer BASIC as "Game BASIC" (having written it so he could implement a Breakout clone for his new computer). Few action games were written in Applesoft BASIC, in large part because the use of floating-point numbers for all math operations degrades performance.

Applesoft BASIC programs are stored as a linked list of lines; a  or   takes linear time. Some programs have the subroutines at the top to reduce the time for calling them.

Unlike Integer BASIC, Applesoft does not convert literal numbers (like 100) in the source code to binary when a line is entered. Rather, the ASCII string is converted whenever the line is executed. Since variable lookup is often faster than this conversion, it can be faster to store numeric constants used inside loops in variables before the loop is entered.

Sample code
Hello, World! in Applesoft BASIC can be entered as the following: Multiple commands can be included on the same line of code if separated by a colon. The  can be used in Applesoft BASIC (and almost all versions of Microsoft BASIC) as a shortcut for "PRINT", though spelling out the word is not only acceptable but canonical—Applesoft converted "?" in entered programs to the same token as "PRINT" (thus no memory is actually saved by using "?"), thus either appears as "PRINT" when a program is listed. The program above appears in a  command as: When Applesoft II BASIC was initially released in mid-1978, it came on cassette tape and could be loaded into memory via the Apple II's machine language monitor. When the enhanced Apple II+ replaced the original II in 1979, Applesoft was now included in ROM and automatically started on power-up if no bootable floppy disk was present. Conversely, Integer BASIC was now removed from ROM and turned into an executable file on the DOS 3.3 disk.

Early evolution
The original Applesoft, stored in RAM as documented in its Reference Manual of November 1977, has smaller interpreter code than the later Applesoft II, occupying 8½ KB of memory, instead of the 10 KB used by the later Applesoft II. Consequently, it lacks a number of command features developed for the later, mainstream version: as well as several the later version would have, that had already been present in Apple's Integer BASIC: In addition, its low-resolution graphics commands have different names from their Integer BASIC/Applesoft II counterparts. All command names are of the form PLTx such that GR, COLOR=, PLOT, HLIN and VLIN are called PLTG, PLTC, PLTP, PLTH, and PLTV, respectively. The command for returning to text mode, known as TEXT in other versions, is simply TEX, and carries the proviso that it has to be the last statement in a program line.
 * All commands supporting Apple's "high resolution" graphics (9 total)
 * Error-trapping with ONERR...GOTO and RESUME
 * Machine-routine shorthand call "&"
 * Screen-clearing HOME (a call to a system ROM routine)
 * Text-output control NORMAL, INVERSE, FLASH and SPEED=
 * The print-space function SPC is listed among reserved words in the manual, but is not otherwise documented (the TAB print-function is documented)
 * Cassette tape storage of numerical arrays: STORE and RECALL
 * Device response: WAIT
 * Program-line deletion: DEL
 * Machine-routine access: CALL
 * Peripheral device access: IN# and PR# (although IN without "#" is listed among reserved words)
 * Memory range control: HIMEM: and LOMEM:
 * Execution tracking for debugging: TRACE and NOTRACE
 * Screen-positioning: HTAB and VTAB
 * Subroutine aborting POP
 * Functions PDL to read the analog controllers, and SCRN to read the low-resolution graphics screen (both accessing system ROM routines)

Applesoft BASIC 1.x was closer to Microsoft's original 6502 BASIC code than the later Applesoft II; it retained the Memory Size? prompt and displayed a Microsoft copyright notice. To maintain consistency with Integer BASIC, the "Ok" prompt from Microsoft's code was replaced by a ] character. Applesoft 1.x also prompted the user upon loading if he wished to disable the REM statement and the LET keyword in assignment statements in exchange for lores graphics commands.

The USR function is also defined differently, serving as a stand-in for the absent CALL command. Its argument is not for passing a numerical value to the machine-language routine, but is instead the call-address of the routine itself; there is no "hook" to pre-define the address. All of several examples in the manual use the function only to access "system monitor ROM" routines, or short user-routines to manipulate the ROM routines. No mention is made of any code to calculate the value returned by the function itself; the function is always shown being assigned to "dummy" variables, which, without action to set a value by user-code, just receive a meaningless value handed back to them. Even accessed ROM routines that return values (in examples, those that provide the service of PDL and SCRN functions) merely have their values stored, by user-routines, in locations that are separately PEEKed in a subsequent statement.

Unlike in Integer BASIC and Applesoft II, the Boolean operators AND, OR and NOT perform bitwise operations on 16-bit integer values. If they are given values outside that range, an error results.

The terms OUT and PLT (and the aforementioned IN) appear in the list of reserved words, but are not explained anywhere in the manual.

Related BASICs
Coleco claimed that its Adam home computer's SmartBASIC was source-code compatible with Applesoft.

Microsoft licensed a BASIC compatible with Applesoft to VTech for its Laser 128 clone.

title: Applesoft BASIC