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Cnversatin1
Narratr
Listen t a cnversatin between a student and a university emplyee.
Student
Hi. I am a little lst. Um, is this the husing maintenance ffice?
Emplyee
Yu fund it. Hw can I help yu?
Student
h, gd. I have a quick questin. Are we allwed t keep electric heaters in ur rms?
Emplyee
Actually, yu are nt. What’s ging n? Yur rm cld?
Student
It’s freezing in my rm. I think the heat went ut r smething.
Emplyee
Are yu sure it’s ut? Maybe it just gt turned ut t far.
Student
h, n. I tried adjusting the, uh, the heat cntrl, but it desn’t make any difference. It’s s cld in my bedrm I can’t sleep at night. I’ve actually been sleeping n the sfa in the frnt rm. The heat still wrks in there. Actually, we get ht air in all the bedrms except urs.
Emplyee
Ww! D yu have a rmmate?
Student
Yeah. But she said she isn’t bthered by the cld. But n the sfa, I am kept up by the nise ut in the hall. The drms can smetimes get pretty nisy. S what can be dne abut it?
Emplyee
Well, K. There’s a cuple f things we can d. I can have a custdian take a lk at it and see if he can d smething.
Student
Actually, I asked the custdian yesterday t take a lk. But he said he culdn’t find anything wrng. He said that sme f the ther rms have lst heat als and that if we’d cme here yu guys wuld fix it.
Emplyee
h, he did? That’s weird, because I wuld have…well, the custdians themselves are usually suppsed t reprt any prblems right away. K. In that case, then what yu need t d is…here, fill ut this frm.
Student
I have t fill ut a frm?
Emplyee
Yeah, but at least that’ll put yur heater prblem in a wrk rder fr the maintenance crew and they’ll get t yu as sn as pssible. Just s yu knw, because it’s nt winter yet and it’s nt as cld as it culd be, it may take a few days fr a maintenance crew t get t yu.
Student
A few days? I can’t even sleep in my wn rm! Can’t we just get an electric heater?
?
Emplyee
I am srry. But students just aren’t allwed. K. I can see that this is a prblem, and nt just with yur rm. S if yu can get the frm back t me this afternn, I’ll try t get a maintenance crew t lk at yur prblem by tmrrw. Hw’s that?
Student
h, that wuld be great. Seriusly. I have t take ff nw. But when I fill this frm ut, I give it t yu, right?
Emplyee
Right. And if I am nt here, just put it in my bx and I’ll get it.
Lecture1 – Archaelgy (The Great Pyramid)
Narratr
Listen t part f a lecture in an archaelgy class.
Prfessr
The Great Pyramid f Giza in Egypt might be the mst famus building in the wrld. We knw exactly when it was built. Cnstructin started in 2547 B.C.E., abut 4500 years ag. We knw wh had it built. That was the pharah Khufu. We knw wh versaw its cnstructin—the pharah’s brther. We knw s many things abut it, but the funny thing is: we still dn’t knw exactly hw it was built.
This picture will give yu an idea f the size f the Pyramid and the size f the blcks it’s made ut f that. Abut tw millin stne blcks were used t build the Great Pyramid and they are incredibly massive. The average weight is tw and a half tns.
The prblem that has puzzled schlars fr centuries is hw were these blcks lifted up the height f this massive structure and then fit int place and withut the benefit f mdern technlgy. f curse, there’ve been a lt f theries ver the centuries.
The ldest recrded ne is by the Greek histrian Herdtus. He visited Egypt arund 450 B.C.E., when the Pyramid was already 2000 years ld. His thery was that cranes were used, much like we use cranes tday t cnstruct tall buildings. And Herdtus may have seen Egyptians using cranes made f wd. But the prblem with this thery has t d with simple mechanics. A crane needs a wide and sturdy base t stand n r it will fall ver. Well, as yu get tward the tp f the Pyramid, there’s really n place fr a crane t stand. The stne blcks are t narrw t prvide a base. Well, s much fr that thery.
The next ne has t d with the use f a ramp that wuld allw wrkers t drag a stne blck up the side f the structure. f curse the ramp can’t be t steep. It has t have a lng gentle slpe. And that’s the prblem. If yu build a ramp with a slight slpe up t the tp f a Pyramid that’s ver 130 meters high, it wuld have t be almst tw kilmeters lng. Well, the Pyramid is built n a flat area called the Giza Plateau. The Plateau is simply nt big enugh t accmmdate a tw-kilmeter-lng ramp.
K. S what nw? Well, if yu’ve ever driven n a muntain rad, yu’d knw that it has a lt f twists and turns and bends in it, because that’s hw engineers keep the rad frm having t be t steep. S why nt wrap the ramp arund the Pyramid? Building the ramp arund it as yu g. Sunds like a pretty gd idea. Except it’s gt a serius prblem. See…ne f the mst remarkable things abut the Great Pyramid is hw accurate the prprtins are. The dimensins are almst perfect. T get that perfectin, the engineers must have had t measure it repeatedly during cnstructin. And the way yu’d measure it is frm the fur crners f the base. Well, if yu gt a ramp spiraling up frm the base f the Pyramid, thse crners wuld be buried by that ramp during cnstructin.
Well, wh says the ramp has t be n the utside f the Pyramid? And nw we get t the latest idea. If the ramp were n the inside f the Pyramid, the crners at the base wuld be expsed, s the engineers culd d their measurements while they were building.
Well, an architect named Hudin has spent a few years wrking n making cmputer mdels f the building f the Pyramid. And what Hudin believes is that an exterir straight ramp was used t cnstruct the bttm third f the Pyramid, this ramp wuld have been fairly shrt. It prbably rse less than 50 meters. Then the rest f the Pyramid was cnstructed using an internal ramp that spiraled arund the inside f the Pyramid.
But hw can we test this idea? Well, there are several ways t lk inside the Pyramid.
ne is called micrgravimetry. Micrgravimetry is a technique that’s used t detect vids inside a structure. Yu can then take the data and generate an image that shws any empty spaces in the interir. Well, in 1986, French scientists cmpleted a micrgravimetric survey f the Pyramid. And ne f the images they prduced shwed an empty spiral-shaped space inside it. The shape f that space crrespnds exactly t what Hudin thught the ramp wuld lk like. I think Herdtus wuld be cnvinced. We might very well be at the end f centuries f guessing.
?
Lecture2 – Envirnmental Science (Water Management)
Narratr
Listen t part f a lecture in an envirnmental science class.
Prfessr
I’d like t cntinue with the tpic f managing water resurces, but I want t fcus n a particular case. Uh, um, an example f water management that’s made us recnsider the methds we use when we make these decisins. S let’s lk at what’s happening in the Clrad River basin.
The Clrad River basin is a regin in the Suthwest United States. Seven states rely n the Clrad’s water. And as yu can imagine, as the ppulatins f these states began t grw, it became clear that a system t distribute, uh, t make sure each state gt its fair share f water…sme kind f system had t be created. And in 1922, a water-sharing agreement was made. Elizabeth, yu have a questin?
Student
Well, hw exactly d yu figure ut hw t share a river? I mean, yu can’t…like cut it up int pieces.
Prfessr
Well, let’s start with the first step. And that’s trying t figure ut hw much water n average flws thrugh the river each year. Nw, researchers had started gathering data n water flw back in the late 1890s using instruments they placed in the river. When the 1922 water-sharing agreement was made, there were abut twenty years f data n water flw available. The average annual flw was calculated. And, well, the agreement was based n that calculatin. The same basic agreement is in effect tday.
Student
Wait! That was all the data they had? And they based their decisin n that?
?
Prfessr
Yes. And we’ll why that was a bad decisin in a mment. K. As decades passed, it became clear that measuring river flw was much mre cmplicated than we had thught. See…a river has perids f lw flw and perids f high flw. And this wasn’t taken int cnsideratin when the 1922 agreement was made. In the 1970s, the ppulatin f the area was rising while the amunt f water flwing thrugh the river seemed t be falling. By this time, we had…what? A hundred years f recrded data t lk at? That’s still a pretty shrt time fr an ancient river.
T get mre data, we lked at a different surce—a surce that was able t tell us abut hundreds f years f the river’s histry—tree rings. K. Let me explain.
Yu prbably knw that we can determine a tree’s age by cunting the rings n a crss sectin f its trunk. Each ring represents ne year f the tree’s life. S if yu knw the year the tree was cut, yu can cunt inwards and date each ring all the way back t the center. Yu can als tell hw much misture the tree gt during each f thse years by lking at the width f the rings. A wide ring means plenty f water while a narrw ne indicates less.
Frtunately fr us, certain areas f the Clrad River basin are hme t sme very ld trees, sme 800 years ld and lder. Researchers can drill cre samples, uh, basically get a crss sectin f a tree withut having t kill it, lk at the rings and get a picture f what the climate was like in the basin fr each f the tree’s years.
Well, the results tell us smething we wuldn’t have knwn withut this data, that ver the past 500 years r s, the Clrad River basin has experienced severe drughts, sme wrse than any we’ve ever recrded. They als shwed that the early t mid-1900s, when mst f the data that led t the water-sharing agreement was cllected…well, this was the wettest perid in the past 400 years. Well, bviusly, had water management fficials knwn then what we knw nw, the 1922 agreement wuld have been handled differently.
But tday we can use the past t help prepare us fr the future. With the demand fr water in the basin stays increasing and with the real likelihd f lwer flws in the river, if histry is ur teacher, we can develp innvative methds f water cnservatin and reevaluate hw water is distributed. ?
Cnversatin2
Narratr
Listen t a cnversatin between a student and his bilgy prfessr.
Student
Prfessr Landrea.
Prfessr
Hi, Dennis. Yu are right n time. Cme n in and have a seat.
Student
Great! Thanks.
Prfessr
S like I tld yu in class, I just wanted t take a few minutes t meet with everyne t make sure yur class presentatins fr next week are all in rder and cming alng well. And as yu knw, yu are suppsed t reprt n sme area f recent research in genetics, smething…yu knw…riginal.
Student
Well, I think I fund just the thing! It actually ccurred t me a cuple nights ag while I was eating dinner in the cafeteria. Tell me prfessr, d yu like brccli?
Prfessr
Brccli? Yu mean the vegetable brccli?
Student
Yeah.
?
Prfessr
Well, I guess nt really.
Student
Me neither. I have never liked it r mst ther vegetables fr that matter…Brussels spruts, asparagus, cauliflwer…yu name it. They just taste bitter and…well…nasty t me. My mther always called me a picky eater.
Prfessr
K…And?
Student
And s I gt t wndering: I mean, I am bviusly nt the nly persn like this. S is this just because f sme…like trauma frm ur childhds? Sme bad experience we’ve had with sme vegetables? r culd there be sme genetic explanatin fr why sme peple are picky eaters and thers aren’t?
Prfessr
K. I see. Well, I suppse it’s a pssibility.
Student
Actually, it turns ut it’s mre than a pssibility. I started ding sme research in the library that night and I fund ut that a bilgist at the Natinal Institutes f Health has been lking at that very questin recently.
Prfessr
Well, I guess that’s nt t surprising. And this is great stuff actually. S what’s the verdict?
Student
Well, this guy seems t have discvered a particular gene that actually makes it pssible fr peple t taste the bitterness in certain green vegetables. But peple wh have a mutatin in that gene cannt taste the bitterness.
Prfessr
Well…that’s certainly fascinating! But…s this bilgist is basically claiming that peple wh like t eat these vegetables actually have sme srt f sensry deficit? Srt f makes us picky eaters than nrmal nes, desn’t it? I mean, that’s kind f turning things n their head, isn’t it?
Student
Well…then again, it wuldn’t be the first time, wuld it? Think f it this way: humans riginally needed t have a strnger sensitivity t bitter-tasting fds s they culd learn what plants were gd fr them and which nes might be pisnus. But at sme pint, as peple figured ut what they culd safely eat, this need became less crucial and a segment f the ppulatin lst that ability.
Prfessr
K. Well, yu make a cmpelling case. I can’t wait t hear mre abut this when yu deliver yur reprt.
?
Lecture3 – Bilgy (Nttheniids)
Narratr
Listen t part f a lecture in a bilgy class.
Prfessr
Ways in which animals adapt t their envirnment are ften quite ingenius actually. And as an example f this, let me tell yu abut a fish, a grup f fish knwn as the Nttheniids. There’s ver 90 knwn species f Nttheniids and they inhabit bth shallw and very deep waters, mstly arund Antarctica. Many are fairly small, thugh the largest species can weigh up t 150 kilgrams.
Nttheniids can be identified by their large eyes, which are cvered by a thick insulating layer f clear tissue. This tissue prtects their eyes frm freezing. Remember, the freezing pint f cean water, salt water, is lwer than fr fresh water, negative 1.9 degree Celsius (-1.9°C). S it can get a lt clder fr fish in an cean, say, than in a river r lake. S this means that the cean waters arund Antarctica are cld enugh t freeze mst types f fish, but Nttheniids dn’t freeze. In fact, they thrive. They accunt fr sme 95% f all fish in the suthern cean, the cean that surrunds Antarctica.
S, hw unusual is that? T have a single family f fish dminating an entire cean. I mean, think f…say, trpical r temperate marine envirnments, which have incredibly diverse fish ppulatins. Cral reefs, fr example, supprt ver 4000 types f fish, alng with spnges, crustaceans, and many ther rganisms.
S, exactly when and hw did the Nttheniids cme t dminate the suthern cean?
Well, arund 30 millin years ag, the waters arund Antarctica were a lt warmer than they are tday. Um...at that time, Antarctica was cnnected t Suth America, which means that warm air frm the nrth culd flw suthward and heat up the Antarctica waters. Because the water arund Antarctica then was relatively warm, it supprted many types f fish. And we knw this frm fssil evidence.
But the 90 r s species f Nttheniids that exist tday didn’t exist at all back then. In fact, nly ne ancestral Nttheniid species existed. But smewhere between 5 millin and 14 millin years ag, tw majr changes tk place.
First, what we call a chance mutatin. A tiny genetic change ccurred in that ne Nttheniid species. Its DNA allwed fr the prductin f a special prtein, a prtein that prevents the fish frm freezing. The way this…this anti-freeze prtein wrks is: it binds t any ice crystals that frm inside the fish. This binding actin prevents the ice crystals frm grwing larger. And this is what prevents Nttheniids frm freezing.
Nw, at that time, the waters the Nttheniids inhabited were still nt freezing cld, s the prtein didn’t really make a difference as far as the fish’s survival. But this wuld change, because in the same perid f gelgic time there was a shift in the earth’s cntinental plates. Cntinental drift caused Antarctica t mve apart frm the landmass f Suth America and t drift int the Suthern Plar Regin. This resulted in a pwerful water current encircling Antarctica, which prevented the Antarctic waters frm mixing with warmer water. S the suthern cean, islated frm that warm airflw frm the nrth, cled dwn drastically, t the kinds f sub-freezing temperatures we assciate with it tday.
Nw, mst fish species culdn’t survive in this frigid envirnment and they became extinct. But that ne Nttheniid species, with its unique ability t prduce that anti-freeze prtein, thrived. It had virtually the entire suthern cean t itself!
S? Well, there was little r n cmpetitin fr fd r space. Yu might think f it as…um…as a…a kind f eclgical vacuum. And the Nttheniids explited fully. The species migrated int different habitats thrughut the suthern cean. And its ppulatin increased dramatically, with varius sub-ppulatins migrating int different parts f the cean. ver time these sub-ppulatins in all thse different habitats…well, they develped very different physical traits. They adapted t survive in their particular eclgical niche, their…their psitin within a particular ecsystem.
We call this type f species diversificatin within a species adaptive radiatin. And what adaptive radiatin is is: an evlutinary prcess by which a parent species rapidly underges changes resulting in varius new species in rder t fill multiple eclgical niches. S in the case f the Nttheniids, that single species started clnizing empty habitats t such an extent that it evlved int a brad range f new species, the 90 r s Nttheniid species that we have tday. S let me switch t adaptive radiatin with regard t anther species that’s als been very successful. ?
Lecture4 – Art Histry (Renaissance Gardens)
Narratr
Listen t part f a lecture in an art histry class.
Prfessr
K. We have been talking abut the art and architecture f the Italian Renaissance, frm arund A.D. 1400 t arund A.D. 1600. Last class, we had a lk at sme f the magnificent palaces and villas built during this time perid. And just as class was ending, smene asked abut the gardens assciated with these palaces and villas. And s I’d like t say a few things abut them befre we mve n.
Nw, when I say gardens, I dn’t mean vegetable gardens r simple flwer gardens. These were lavishly cnstructed, finely detailed gardens that cvered hundreds f acres, with extic plants and rnamental statues. And they were just as much a symbl f their wners’ scial psitin as their palaces and villas were. Again, what was the inspiratin fr the Renaissance? Rebecca.
Student
Classical art and architecture f the ancient Greeks and Rmans.
Prfessr
That’s right. As we’ve said befre, the main pint f the Renaissance was t revive the genius f the ancient Greeks and Rmans, which is why designers f Renaissance gardens designed them as the ancient Rmans wuld have designed them, r at least as they imagined the ancient Rmans wuld have designed them.
Student
Hw did they knw what ancient Rman gardens lk like?
?
Prfessr
Well, they didn’t have any pictures. But they did have sme very detailed descriptins f ancient Rman villas and their gardens that had been written by famus Rman authrs wh lived during the height f the Rman Empire. And at least three f thse authrs, ne was a schlar, ne was a pet, and ne was lawyer, were very authritative, very reliable surces.
Ah…and interestingly enugh, there was anther surce that didn’t describe classical gardens but still became a great influence n Renaissance gardens. It was als written back during the height f the Rman Empire by a mathematician knwn as Her f Alexandria. Her was a Greek. But he lived in Alexandria, Egypt, which was at the time part f the Rman Empire. Her cmpiled descriptins and sketches f seventy sme clever little mechanical devices, mst f which utilized cmpressed air t cause water, r in sme cases wine, t flw frm ne place t anther, r smetimes t squirt r t make sme kind f nise. Yes? Jhn?
Student
Culd yu give an example?
Prfessr
Well, ne f the devices was a sacrificial vessel that was bviusly designed fr a temple, nt fr a garden. Anyway, if yu drp mney int this vessel, water wuld flw ut f it. Well, creative minds in the Renaissance realized that this little device culd be nicely repurpsed as a nifty little funtain. Designers f Renaissance gardens lved this srt f thing. They lved t incrprate nvelties and tricks, things t amuse and impress guests.
Student
And that was the purpse? T impress peple?
Prfessr
Sure. As a nbleman r wealthy landwner, ne purpse f having a fabulus villa with a fantastic garden was t impress peple. It was a way f prving yur scial psitin.
?
Student
Well…K. Yu als mentined tricks.
Prfessr
Well, fr example, sme gardens had plaster r marble birds that sang when water flwed thrugh them. Sme funtains were designed t squirt peple with water.
Student
And these things were ppular?
Prfessr
Yes. They may have been the mst ppular features f the gardens. I mean, flwers and statues can be nice t lk at, but these things were a lt mre fun. And the mre clever the device is, the mre famus the garden and the greater prestige the landwner enjyed. Yes? Rebecca.
Student
What abut mazes? I read that they were a majr part f the Renaissance gardens.
Prfessr
h, yes. They certainly were! Mazes r labyrinths, as they’re als called, were very cmmn in Renaissance gardens. Hw that came t be thugh is a bit f a mystery. Mazes have a lng histry ging back t the ancient Egyptians, but they started appearing in gardens nly during the Renaissance, r perhaps just a little bit prir t that. Accrding t ne surce, what happened was: in the late 1400s, a highly respected expert published a bk n architecture. And readers smehw mistakenly inferred frm that bk that ancient Rmans had mazes in their gardens. S then designers f Renaissance gardens thinking they were fllwing in the ftsteps f the ancient Rmans…well…guess what they did.