Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
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Question: The Web site for the Anxiety Disorders Association of America (ADAA) receives more than 5 million visits per month and thus represents a unique medium for the study of anxiety disorders. ADAA Web site users from October 2002 to January 2003 were invited to complete a survey oriented toward trauma history and psychiatric sequelae. A diagnostic approximation of posttraumatic stress disorder (PTSD) was based on responses to the Trauma Questionnaire, the Davidson Trauma Scale, and questions about impairment. The Connor-Davidson Resilience Scale was also used. Variables were tested for their association with PTSD. Among 1558 participants, 87% had a history of trauma, and 38% had current PTSD. The population was comprised predominantly of white middle-class women, half of whom were married. More than 90% were first-time users of the site. Factors associated with PTSD included death of, or harm to, a loved one; personal history of incest, rape, or physical abuse; lower age; lower income; unemployment; missed work; increased medical care; dissatisfaction with psychotropic medication; depressive symptoms; and lower resilience. In this selective convenience sample, there were high rates of traumatization and PTSD. The demographics of this group are similar to those seen in previously studied populations that had contacted the ADAA. Furthermore, the factors associated with PTSD were like those in many community surveys. The ADAA Web site has the opportunity to benefit large numbers of highly distressed individuals.

Answer: Symptoms of which disorder are evaluated with the Davidson Trauma Scale?

Question: Tardive dyskinesia (TD) is a movement disorder characterized by abnormal involuntary facial movements induced by chronic therapy with classical antipsychotic medications. Currently, there is no satisfactory pharmacotherapy for TD, which represents a major limitation to therapy with classical antipsychotics. In order to develop or optimize therapies for TD, and to develop new APDs with lower indices of motor side effects, the pathology underlying TD must first be understood. The use of animal models has been used to further this objective. Here, we review different preparations that have been used to model TD and discuss the contribution of neuroimaging studies conducted in these models. Studies in animal models have lead to several hypotheses of TD pathology, although none has yet emerged as the ultimate underlying cause of this syndrome. We discuss alterations in functional indices, neuron and synapse morphology and changes in specific neurotransmitter systems that have been described in animal models of TD, and outline how these findings have contributed to our understanding of antipsychotic-induced dyskinesias. We conclude that several non-mutually exclusive theories of TD are supported by animal studies, including increases in oxidative stress leading to structural and functional changes in specific neurotransmitter systems. Elucidating the mechanisms underlying TD neuropathology partly through the use of animal models will lead to the development of APDs with superior side effect profiles or more effective therapies for TD.

Answer: What is the cause of Tardive dyskinesia?

Question: In the 1950s, a family that owned a farm near Beulah, Michigan kept a bull chained to an elm . The bull paced around the tree, dragging the heavy iron chain, which led to a groove in the bark . The groove deepened over the years. Though for whatever reason, it did not kill the tree. After some years, the family took their bull away. They cut the chain, leaving the loop around the tree and one link hanging down. Then one year, agricultural disaster struck Michigan in the form of Dutch Elm Disease. All of the elms lining the road leading to the farm became infected and died. Everyone thought that the old elm would be the next. The farm owners considered doing the safe thing: pulling it out and cutting it up into firewood before it died. But they simply could not bring themselves to do it. It was as if the old tree had become a family friend. So they decided to let nature take its course. Amazingly, the tree did not die. Nobody could understand why it was the only elm still standing in the county! Plant experts from Michigan State University came out to observe the tree. They observed the scar left by the iron chain, now almost completely covered by bark. The experts decided that it was the chain that saved the elm's life. They reasoned that the tree must have absorbed so much iron from the chain that it became immune to the virus. It's said that what doesn't kill you will make you stronger. Or, as Earnest Hemingway put it, "Life breaks us all, but afterwards, many of us are strongest at the broken places."

Answer:
What actually saved the elm?