Long before she was known for her innovative guitar playing and her songs became standards in American folk (1) music, and Elizabeth Cotten was just a left-handed girl from Chapel Hill, North Carolina, with a drive to make music. “[For] everything I play for y'all tonight," she would later tell her (2) audience, thinking back to her beginnings, "I give myself credit."

 (3) Cotten was born in 1893.  Cotten was only eight when she taught herself to play her brother's banjo. Contending with an instrument that was built and strung for a right-handed player, she flipped the banjo upside down and developed her own idiosyncratic way of playing (4) them. Her technique was distinctive not simply because she was a left-handed musician playing a right-handed instrument, but because she (5) adopted the unconventional method of wrapping her right hand around the instrument's neck and playing with both her right thumb and fingers. When she applied this technique to the six-stringed acoustic guitar, (6) even though she was so young, the result was a melodic and technically (7) highfalutin style that would become her signature sound.

This "Cotten style," as it later came to be known, incorporated elements from the African American musical tradition. "FreightTrain," a song Cotten wrote when she was only eleven, blends the sing-along quality of folk music with the quick, jostling rhythms of ragtime. Inspired by the locomotive that would rumble by her window each day, she captured both the (8) sound and speed of its passing as well as the possibility of escape when she sang, "Freight train, freight train, run so fast/ Please don't tell what train I'm on / They won't know what route I'm going." As the granddaughter of freed slaves (9) themselves, Cotten was no doubt attuned to the long history trains have had in blues music as symbols of freedom. 

[l] As it happened the route Cotten was on involved a nearly fifty-year detour away from playing guitar, during which she worked and raised a family. [2] She still remembered the songs from her youth but began writing new ones as well. [3] On one such song, "Shake Sugaree," she collaborated with her grandchildren, letting each grandchild write averse. [4] Later, as the rising popularity of her songs took her across North America, earning her awards and accolades of the highest kind, she would encourage her audiences to sing (10) along with her too. (5) Remembering how she taught herself to play and write her songs, she rightfully gave herself credit; however, seeing how her performances brought people together, Cotten also recognized the communal power of music. (11)

The job of a simultaneous interpreter is to translate (12) speaker's words' into a language that an audience understands at the moment the words (13) were spoken. Lynn Visson performs this important task at the United Nations (UN) headquarters. She is one of about 120 language experts employed by the UN to translate diplomats' remarks into the organization's six official languages: Arabic, Chinese, English, French, Russian, and Spanish.

[1] In the first round of screening, candidates (14) and job seekers demonstrate language fluency by interpreting UN speeches delivered in the candidates' acquired languages [2] A UN interpreter must be able to translate from two acquired languages into the interpreter's "main" or native (15) tongue, all three languages must be among the organization's six official ones. (3) Only 10 percent of candidates make it to the next step, the interview, which tests not only language ability but also knowledge of global current events and cross-cultural sensitivity. [4] Before an interpreter can be hired by the UN's Interpretation Service, the organization screens candidates to ensure that they are both multilingual and impartial. (16)

The interpreters selected via this process must be capable of withstanding the pressures of the job. The work of translation is always difficult, but (17) their cognitive demands are amplified in simultaneous interpretation, when (18) the words and syntax of different languages must be aligned instantaneously. For example, because Russian verbs come later in sentences than English ones do, presenting a Russian speech in English requires an interpreter to listen for the end of a sentence before beginning to translate it into English syntax-all while continuing to follow the original speech. 

The word choices of UN interpreters, (19) moreover, can have far-reaching effects, as was proved in 1995 during a dispute between Greece and the former Yugoslav Republic of Macedonia. The latter wanted to be known simply as Macedonia, (20) but this caused protests from Greece. What Greece said was that it infringed on a territorial claim on a Greek province known by the same name. Negotiations on the issue were nearly derailed when an interpreter, (21) showing little awareness of the sensitivities of the two nations involved, shortened the former Yugoslav nation's name to "Macedonia." This momentary deviation from carefully negotiated language required the Interpretation Service's leader to offer an in-person apology to the Greek delegation. If this incident highlights the perils of diplomatic language interpretation, though, (22) in addition to underscoring the work's abiding importance: without the help of Visson and her fellow interpreters, those representing the many nations of the UN would be unable to unite through language.

Nearly 13,000 years ago, as Earth was emerging from its last ice age, large parts of the globe were plunged back into cold temperatures in a climatic event called the Younger Dryas. Scientists have long debated the cause of this sudden reversal of the warming (23) trend. A 2015 study published in the journal Nature Geoscience claims that the Younger Dryas cannot be explained by a single cause; only the (24) junction of multiple factors could have created this climatic reversal.

One long-standing explanation for the Younger Dryas is a disruption of ocean currents. Normally, ocean currents flow in a pattern called the Atlantic Meridional Overturning Circulation (AMOC). Wann salt water flows north from the tropics into the North Atlantic Ocean, where some warmth is transferred to the atmosphere. At the end of the ice age, glaciers melted, causing cold freshwater to flow into the Atlantic and (25) disrupted the AMOC. When researchers ran a computer model to estimate the effects of these freshwater flows, however, (26) they realized that the theory of ocean current disruption was entirely wrong: in the model, the freshwater entering the Atlantic did not by itself cause enough cooling (27) in accounting for the Younger Dryas.

Other computer models measured the possible effects of either a complete shutdown of the AMOC or a significant change in negative radiative forcing- the tendency of the atmosphere to reflect rather than absorb energy from the Sun. (28) Next, none of these models provided a good fit with the actual temperature changes recorded from geological findings. But when researchers designed a computer (29) model, that accounted for both freshwater infusions associated with melting glaciers and changes in negative radiative forcing, the results were a good fit for the geological data.

The combined model starts at a baseline state derived from geological data. As the model includes freshwater infusions and stronger negative radiative forcing, after (30) 400 years, the air temperature and maximum strength of the AMOC begin to fall. Both (31) vary wildly over a period of about 1,000 years. Finally, temperature and AMOC strength climb sharply starting at approximately 1,100 years. These results match the geological record (32) well; and are not reflected in any other computer models.

The researchers concluded that more than one factor contributed to the Younger Dryas. Glacial melt played a role, but so did changes in atmospheric conditions. Scientists hope to build on this more complicated model of climate change in the Younger (33) Dryas by: studying the causes of atmospheric change during this period and the relative importance of the different contributing factors.

Among computer scientists who are working to develop artificial intelligence, there is debate over the best way to judge when such intelligence has been achieved. According to some, the most promising approach dates back to the mid-nineteenth century. Ada Lovelace is frequently credited as the world's first computer programmer, but her importance as a theorist of what differentiates human thought from computer programs (34) are less often recognized. In fact, her writing on this distinction provides today's computer scientists with one of the clearest pictures of what true artificial intelligence entails. 

(35) In 1843 Lovelace wrote a commentary on a proposed computing device. In this commentary, Lovelace stated that the device "has no pretensions whatever to originate anything. It can do whatever we know how to order it to perform." Lovelace's contrast between a human mind capable of original thought and a computer that can do only as it has been instructed remains highly relevant. In 2001 her analysis inspired a team of computer scientists to develop what they called the Lovelace test. According to this test, a computer program (36) was judged intelligent only if it is capable of producing some sort of output that its programmer cannot explain.

(37) The math that Lovelace used in her work on computers was an early version of calculus. An earlier and more well-known measure is the Turing test, which holds that artificial intelligence is achieved when a computer program successfully convinces a human conversational partner that he or she is talking with another person. The test (38)was not the sole contribution that Alan Turing made to the field of computer science. For one thing, it cannot ultimately determine whether (39) it is capable of independent thought, merely whether the program is able to persuasively impersonate such thought. For another, its assessment of intelligence is based on (40) users' reactions rather than on programmer’s knowledge.  By (41) emphasizing the programmers, the Lovelace test produces a more definitive measure of intelligence. The programmer knows everything that has been put into the (42) system, he or she is in the best position to judge whether something inexplicably original has been generated.

Some computer scientists argue that (43) products claiming to use artificial intelligence today possess little or no true intelligence, but their objections should not be seen as (44) trashing the value of Lovelace's influence. Rather, the difficulty of passing the Lovelace test reflects just how rigorous the test is and how far away the achievement of true artificial intelligence remains. Should the goal ever be reached, Lovelace's contributions will have helped ensure that the milestone represents the highest possible standard and is truly meaningful.