Analyze the sentiment expressed in the tweet. Is it positive, negative, or neutral? Explain the sentiment in relation to the stock mentioned.
TWEET: "@harpercollins  Lisa Sharkey USA speaking at #Quantum17 with @facebook Erin Murray https://t.co/XCO1hl1HB3  tix still available, fab line up
" STOCK: Facebook DATE: 28/02/2017
Sentiment: (Provide sentiment here)
Explanation: The tweet sentiment is related to the stock mentioned, and it's important to interpret the context. The LSTM polarity score is 1 and the TextBlob polarity score is 0.4.