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(B)  The 2009 H1N1 influenza pandemic left a troubling legacy in Europe: More than 1300 people who received a vaccine to prevent the flu developed narcolepsy, an incurable, debilitating condition that causes overpowering daytime sleepiness, sometimes accompanied by a sudden muscle weakness in response to strong emotions such as laughter or anger. The manufacturer, GlaxoSmithKline (GSK), has acknowledged the link, but how the vaccine might have triggered the condition has been unclear.  In a paper in Science Translational Medicine (STM) this week, researchers offer a possible explanation. They show that the vaccine, called Pandemrix, triggers antibodies that can also bind to a receptor in brain cells that help regulate sleepiness. The work strongly suggests that Pandemrix triggered an autoimmune reaction that led to narcolepsy in some people who are genetically at risk.   “They put together quite a convincing picture and provide a plausible explanation for what has happened,” says Pasi Penttinen, who heads the influenza program at the European Centre for Disease Prevention and Control. “It’s really the kind of work we’ve been waiting for 5 years.” But the results still need to be confirmed in a larger study, the authors and other narcolepsy researchers say. A 2013 paper in STM by another group, documenting a different type of vaccine-triggered autoimmune reaction, was retracted after the results proved irreproducible.   Narcolepsy, a mysterious malady that affects roughly one in 3000 people in Europe, most often appears in childhood or adolescence. Patients lose certain brain cells in the hypothalamus, leading to a deficiency of hypo-cretin, a molecule that helps regulate the sleep-wake cycle. Researchers suspect an autoimmune reaction is to blame because many people who develop narcolepsy—and just about everyone with the vaccine-associated form—have a specific variant in a gene in the HLA family, which helps the body distinguish its own proteins from those made by microbial invaders.  When they heard about the rise in narcolepsy in 2010, neuroscientist Lawrence Steinman and rheumatologist Sohail Ahmed began scouring databases for proteins expressed in the brain that might resemble those in the vaccine.   Their search turned up a suspect: a piece of a receptor for hypo-cretin resembles part of the H1N1 influenza nucleoprotein—which binds to the virus genome and plays a key role in its replication .The flu vaccine is designed to trigger antibodies to influenza’s surface proteins, but if it elicits antibodies to the nucleoproteinas well, those might well latch on to the hypocretin receptor, and eventually lead to death of the cells, the researchers thought.  In the new work, the researchers added serum from Finnish narcolepsy patients who had received Pandemrix to cells that were engineered to display human hypo cretin receptor 2 on their surface. Antibodies from the patients bound to these cells in 17 of 20 samples. Serum from Italians who had been vaccinated with a different pandemic vaccine from Novartis, called Focetria, did not have such antibodies. The researchers also showed that Focetria, which has not been linked to narcolepsy, had a much lower concentration of nucleoprotein than Pandemrix did.   The passage answers which of the following questions?

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(A)  Procrastination is a well-known and serious behavioral problem involving both practical and psychological implications. Taxpayers commonly put off submitting their annual returns until the last minute, risking mathematical errors in their frenzy to file. Lawmakers notoriously dawdle and filibuster before enacting sometimes rash and ill-advised legislation at the eleventh hour. And, students burn the midnight oil to get their term papers submitted before the impending deadline, precluding proper polishing and proofreading. For these reasons, we are cautioned not to procrastinate: Don’t put off until tomorrow what you can do today. He who hesitates is lost. Procrastination is the thief of time.  However, the opposite of procrastination can also be a serious problem 一 a tendency we call “pre-crastination.” Pre-crastination is the inclination to complete tasks quickly just for the sake of getting things done sooner rather than later. People answer emails immediately rather than carefully contemplating their replies. People pay bills as soon as they arrive, thus failing to collect interest income. And, people grab items when they first enter the grocery store, carry them to the back of the store, pick up more groceries at the back, and then return to the front of the store to pay and exit, thus toting the items farther than necessary. Familiar adages also warm of the hazards of pre-crastinating: Measure twice, cut once. Marry in haste, repent at leisure. Look before you leap.  We first found striking evidence of pre-crastination in a laboratory study exploring the economics of effort. College students were asked to carry one of a pair of buckets: one on the left side of a walkway and one on the right side of the same walkway. The students were instructed to carry whichever bucket seemed easier to take to the end of the walkway. We expected students to choose the bucket closer to the end because it would have to be carried a shorter distance. Surprisingly, they preferred the bucket closer to the starting point, actually carrying it farther. When asked why they did so, most students said something like, “I wanted to get the task done as soon as possible,” even though this choice did not in fact complete the ask sooner.  Nine experiments involving more than 250 students failed to reveal what might have been so compelling about picking up the nearer bucket. Although some hidden benefit may await discovery, a simple hypothesis is that getting something done, or coming closer to getting it done, is inherently rewarding. No matter how trivial the achievement, even something as inconsequential as picking up a bucket may serve as its own reward.  Is pre-crastinatio — exhibited by college students, bill payers, e-mailers, and shoppers —a symptom of our harried lives? The other study from our laboratories suggests it is not: that experiment was done with pigeons. The birds could earn food by pecking a touchscreen three times: first, into a square in the center of the screen; second, into the same square or into a square that randomly appeared to the left or right of it; and third, into a side square after a star appeared within it. Critically, food was given after the final peck regardless of whether the second peck struck the center square or the side square where the star would be presented. The pigeons directed their second peck to the side square, hence moving to the goal position as soon as they could even though there was no obvious or extra reward for doing so. Thus, the pigeons pre-crastinated.   What does the passage mainly discuss?

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