Here is a question about this article: A series of experiments performed from the late 1800s to the early 1900s revealed that diabetes is caused by the absence of a substance normally produced by the pancreas. In 1869, Oskar Minkowski and Joseph von Mering found that diabetes could be induced in dogs by surgical removal of the pancreas. In 1921, Canadian professor Frederick Banting and his student Charles Best repeated this study, and found that injections of pancreatic extract reversed the symptoms produced by pancreas removal. Soon, the extract was demonstrated to work in people, but development of insulin therapy as a routine medical procedure was delayed by difficulties in producing the material in sufficient quantity and with reproducible purity. The researchers sought assistance from industrial collaborators at Eli Lilly and Co. based on the company's experience with large scale purification of biological materials. Chemist George Walden of Eli Lilly and Company found that careful adjustment of the pH of the extract allowed a relatively pure grade of insulin to be produced. Under pressure from Toronto University and a potential patent challenge by academic scientists who had independently developed a similar purification method, an agreement was reached for non-exclusive production of insulin by multiple companies. Prior to the discovery and widespread availability of insulin therapy the life expectancy of diabetics was only a few months.
What is the answer to this question: Why was insulin therapy delayed?
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So... difficulties in producing the material in sufficient quantity and with reproducible purity

Here is a question about this article: Jonathan Bellman writes that modern concert performance styleset in the "conservatory" tradition of late 19th- and 20th-century music schools, and suitable for large auditoria or recordingsmilitates against what is known of Chopin's more intimate performance technique. The composer himself said to a pupil that "concerts are never real music, you have to give up the idea of hearing in them all the most beautiful things of art." Contemporary accounts indicate that in performance, Chopin avoided rigid procedures sometimes incorrectly attributed to him, such as "always crescendo to a high note", but that he was concerned with expressive phrasing, rhythmic consistency and sensitive colouring. Berlioz wrote in 1853 that Chopin "has created a kind of chromatic embroidery ... whose effect is so strange and piquant as to be impossible to describe ... virtually nobody but Chopin himself can play this music and give it this unusual turn". Hiller wrote that "What in the hands of others was elegant embellishment, in his hands became a colourful wreath of flowers."
What is the answer to this question: Who wrote that the current large concert style conflicts with Chopin's preference of intimate performances?
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So... Jonathan Bellman

Here is a question about this article: While new characters can be easily coined by writing on paper, they are difficult to represent on a computer they must generally be represented as a picture, rather than as text which presents a significant barrier to their use or widespread adoption. Compare this with the use of symbols as names in 20th century musical albums such as Led Zeppelin IV (1971) and Love Symbol Album (1993); an album cover may potentially contain any graphics, but in writing and other computation these symbols are difficult to use.
What is the answer to this question: What has their been a prominent supply of in the 20th century?
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So...
symbols