Around mid-century, Mendeleev began to develop the table of elements which helped in the discovery of new elements. In the last decade of the century, the discovery of radium by Marie and Pierre Curie, and the electron by Becquerel as well as observation of radioactivity in the laboratory, challenged Dalton's theory.
Medications Used to Treat ADHD. Stimulant medications commonly prescribed for attention deficit disorder include methylphenidate (Ritalin, Concerta, Metadate, Methylin) and certain amphetamines (Dexedrine, Dextrostat, Adderall). Methylphenidate is a short acting drug, and in older forms, had to be taken multiple times a day.
Methylphenidate is approved by the US Food and Drug Administration (FDA) for the treatment of attention deficit hyperactivity disorder. The addition of behavioural modification therapy (e.g. cognitive behavioral therapy (CBT)) can have additional benefits on treatment outcome.