THENATIONALPolar ExplorationsGREATGEOGRAPHIC"Taughtby Various InstructorsCOURSESLECTURETITLESAPassionforthePoles1.2Seasons at the PolesOOConnectionsbetweenthePoles4TheSagaofArcticExploration5.The lcyHeart of PolarSeas70%5Geology of the Arctic Circle27.Science and Spirits2offGREATY28of theArcticSkyCOURSESORDERBYMA8IndigenousPeoplesof theArcticPolar Explorations9Greenlandand Arctic IslandsPolarNATIONA10.Terrestrial Mammals inGEOCRAPHICthe Changing ArcticExplorations11.Seabirds of the Arcticand Antarctic12.MarineMammalsfromahEndiaWhalestoWalruses13.TheRacefortheSouthPole14.Geological FeaturesofAntarctica15.Antarctica'sWindowon the Universe16.Diving under Polar Ice17.ResourceDevelopmentinPolarSeas18.SouthGeorgiaandMacquarie19.Living amongthe Penguins20.Antarctica:AContinentforScience21.BasicsofPolarPhotography22.Photographing PolarLandscapesPolarExplorationsExploretheWonderandCourse no.3502122 lectures (30 minutes/lecture)Beauty of the Polar RegionsSAVE$190Enchanting and otherworldly in their beauty, the polar regions are someof the most isolated and least understood places on Earth. And yet, theseextreme environments are endlessly fascinating, and eminently worthy ofDVD$269.95NOW$79.95experiencing firsthand, especially if you are prepared to understand whatStoShiginnBroceenandLifehimCotfinnGuarantyou are seeing.PriorityCode:108554Created in collaboration with National Geographic, Polar Explorationsdelivers an unprecedented 360-degree view of the Arctic and AntarcticFor25years.TheGreatCourseshasregions, featuring spectacular National Geographic footage shot onbroughttheworld'sforemosteducatorslocation. Led by a multidisciplinary team of renowned instructors, it'stomillionswhowanttogodeepea travelogue, science class, and history lesson all rolled into one visuallyintothesubjectsthatmattermost.Nostunning, comprehensive course.exams.Nohomework.Justa worldofknowledgeavailableanytime,anywhereOfferexpires05/28/15DownloadorstreamtoyourlaptopoPC,oruseourfreemobileapps foriPad,THEGREATCOURSES.COM/5NGiPhone.orAndroid.Over500courses1-800-832-2412availableatwww.TheGreatCourses.com
For 25 years, The Great Courses has brought the world’s foremost educators to millions who want to go deeper into the subjects that matter most. No exams. No homework. Just a world of knowledge available anytime, anywhere. Download or stream to your laptop or PC, or use our free mobile apps for iPad, iPhone, or Android. Over 500 courses available at www.TheGreatCourses.com. Polar Explorations Taught by Various Instructors LECTURE TITLES 1. A Passion for the Poles 2. Seasons at the Poles 3. Connections between the Poles 4. The Saga of Arctic Exploration 5. The Icy Heart of Polar Seas 6. Geology of the Arctic Circle 7. Science and Spirits of the Arctic Sky 8. Indigenous Peoples of the Arctic 9. Greenland and Arctic Islands 10. Terrestrial Mammals in the Changing Arctic 11. Seabirds of the Arctic and Antarctic 12. Marine Mammals, from Whales to Walruses 13. The Race for the South Pole 14. Geological Features of Antarctica 15. Antarctica’s Window on the Universe 16. Diving under Polar Ice 17. Resource Development in Polar Seas 18. South Georgia and Macquarie 19. Living among the Penguins 20. Antarctica: A Continent for Science 21. Basics of Polar Photography 22. Photographing Polar Landscapes SAVE $190 Polar Explorations Explore the Wonder and Course no. 3502 | 22 lectures (30 minutes/lecture) Beauty of the Polar Regions Enchanting and otherworldly in their beauty, the polar regions are some of the most isolated and least understood places on Earth. And yet, these extreme environments are endlessly fascinating, and eminently worthy of experiencing firsthand, especially if you are prepared to understand what you are seeing. Created in collaboration with National Geographic, Polar Explorations delivers an unprecedented 360-degree view of the Arctic and Antarctic regions, featuring spectacular National Geographic footage shot on location. Led by a multidisciplinary team of renowned instructors, it’s a travelogue, science class, and history lesson all rolled into one visually stunning, comprehensive course. Off er expires 05/28/15 THEGREATCOURSES.COM/5NG 1-800-832-2412 DVD NOW $79.95 +$10 Shipping, Processing, and Lifetime Satisfaction Guarantee Priority Code: 108554 LIMITED TIME OFFER ORDER BY MAY 28 70% off
EXPLOREWild ThingsFood FightWarships use sonarto detecttargets and jammingtechnol-ogytothwartenemysonar.Mexicanfree-tailedbatscandoboth those things with their vocal cords.Batsuseecholocation,bouncingsoundwavesoffanobject,tonavigateanddrawabeadonprey.AaronCorcoranandWilliamConner,scientistsatWakeForestUniversity,recentlydiscovered thatMexicanfree-tailedbatsalso usethese signals to interfere with one another's hunts.Whenoneofthebatsishominginonan insect,itincreasestherateofitssignalstoarapid"feedingbuzz.ifasecond,nearbybatemitsa jammingsignal,thatmayconfuse thereading Bat 1gets on the insect,giving Bat2anopeningtostealit.Nottobeoutdone,Bat1maysenditsownjammingsignal,startingaback-and-forthbattleCorcoran hopestolearn whether thebehavior isuniquetoMexican free-tailedbats,which-living in coloniesofamillionplus-mustcompeteformeals.-LindsayN.SmithCOMPETITIVEEATERSCorcoranplottedthe interactionsoftwoMexicanfree-tailed batshuntingforthesamemothandemittingcompetingfeedingbuzzesandjammingsignals.EcholocationFeedingbuzzJammingcallcallBat10-0-0-00-0-00DBat2000-00000-DsecondsCHAEUCEnCGRAPHIC:MATTHEWTWOMBLY.NGM STAFRSOURCE:AARONCORCORAN
Warships use sonar to detect targets and jamming technology to thwart enemy sonar. Mexican free-tailed bats can do both those things with their vocal cords. Bats use echolocation, bouncing sound waves off an object, to navigate and draw a bead on prey. Aaron Cor coran and William Conner, scientists at Wake Forest University, recently discovered that Mexican free-tailed bats also use these signals to interfere with one another’s hunts. When one of the bats is homing in on an insect, it increases the rate of its signals to a rapid “feeding buzz.” If a second, nearby bat emits a jamming signal, that may confuse the reading Bat 1 gets on the insect, giving Bat 2 an opening to steal it. Not to be outdone, Bat 1 may send its own jamming signal, starting a back-and-forth battle. Corcoran hopes to learn whether the behavior is unique to Mexican free-tailed bats, which—living in colonies of a million plus—must compete for meals. —Lindsay N. Smith Food Fight PHOTO: MICHAEL NICHOLS, NATIONAL GEOGRAPHIC CREATIVE GRAPHIC: MATTHEW TWOMBLY, NGM STAFF. SOURCE: AARON CORCORAN Wild Things EXPLORE COMPETITIVE EATERS Corcoran plotted the interactions of two Mexican free-tailed bats hunting for the same moth and emitting competing feeding buzzes and jamming signals. Echolocation call Feeding buzz 0 seconds 1 2 3 Jamming call Bat 1 Bat 2
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EXPLORE00Bythe NumbersEven though many farmers struggle to meet their crops' demand for water inThirstyplacessuchasdrought-strickenCalifornia,evryyartheysendbilionsofvirtualgallonstoothercountries-intheformofthefoodandfeedgrownwiththatExportswater.AccordingtoArjenHoekstraoftheNetherlands'UniversityofTwente,theissueofagriculture'swaterfootprint-allthewaterusedtoproduceacommodityand get it to a consumeris contentious, since many farmers use scarce watertoproduce low-value export crops.Water isa public good, hesays, so allocationsystemsoughttosupportits sustainableuse.-Kelsey NowakowskiCHINA'S RISING DAIRY DEMANDChinese consumers drink moremilktodaythan everbefore.Becausethelappetite fordairyproducts (s growingfasterthen Chinesefamers capacity,tofeeddairycattle,thosefarmersnowrelyonalfalfahayimportsfromtheU.sWATER FOOTPRINT OFWHOLEMILKINTHEPEOPLE'SREPUBLICOFCHINATOI11,182GALLONSPRODUCEGALLONTAKESOFWATEROFMILKGRAINSOILMEALSOTHERFEEDGRASSANDHAY51%169%14%18%DRINKINGANDUSEATFARM18ALFALFAISCALIFORNIA'SAlfalfaimprovestheamountandqualityLARGESTAGRICULTURALWATERofmillicproducedbydairycows.USER.CONSUMINGMORETHANFIVEMILLIONACRE-FEET"AYEARRAWMILKPROTEINCONTENTINCHINA2.8%standaru3.0%owsfedhigh-qualityalfaifaU.S.ALFALFAHAYIMPORTEDBYCHINAAfter.dropping.offChinesegoodsinCaliforniaports,mamycontainersare filled withalfalfaforthereturn trip.ll'softenmore cost-effective tosend alfalfta from Los Angeles to Beling than from Californin's ImperlalValieyto lits Central Valley.where-manydiairy fams arelocated?0?2.968125.tons19901998"Virtual water floyh tradeto theconsumingcountryMirtMth**One acre-foot is the amount of water ttetoadepthofonefoot,or325.851gallons
By the Numbers EXPLORE CHINA’S RISING DAIRY DEMAND RAW MILK PROTEIN CONTENT IN CHINA U.S. ALFALFA HAY IMPORTED BY CHINA 2.8% 3.0% National standard Cows fed high-quality alfalfa DRINKING AND USE AT FARM 1% TO PRODUCE 1 GALLON OF MILK 1,182 GALLONS OF WATER IT TAKES GRAINS 51% GRASS AND HAY 16% OIL MEALS 14% OTHER FEED 18% 1990 1998 2,968 125 tons Even though many farmers struggle to meet their crops’ demand for water in places such as drought-stricken California, every year they send billions of virtual gallons to other countries—in the form of the food and feed grown with that water. According to Arjen Hoekstra of the Netherlands’ University of Twente, the issue of agriculture’s water footprint—all the water used to produce a commodity and get it to a consumer—is contentious, since many farmers use scarce water to produce low-value export crops. Water is a public good, he says, so allocation systems ought to support its sustainable use. —Kelsey Nowakowski Thirsty Exports Chinese consumers drink more milk today than ever before. Because their appetite for dairy products is growing faster than Chinese farmers’ capacity to feed dairy cattle, those farmers now rely on alfalfa hay imports from the U.S. After dropping off Chinese goods in California ports, many containers are filled with alfalfa for the return trip. It’s often more cost-effective to send alfalfa from Los Angeles to Beijing than from California’s Imperial Valley to its Central Valley, where many dairy farms are located. Alfalfa improves the amount and quality of milk produced by dairy cows. WATER FOOTPRINT OF WHOLE MILK IN THE PEOPLE’S REPUBLIC OF CHINA ALFALFA IS CALIFORNIA’S LARGEST AGRICULTURAL WATER USER, CONSUMING MORE THAN FIVE MILLION ACRE-FEET** A YEAR. * Virtual water flow is all water used to produce a commodity, transferred virtually through trade to the consuming country. **One acre-foot is the amount of water that would cover one acre to a depth of one foot, or 325,851 gallons
AVERAGE ANNUAL WATER FOOTPRINTVIRTUAL WATER FLOW*gallons per capita, 1996-2005eNet exportersNet importersPercentage contributedby milk consumption7.3%U.S.[6.8%WORLDAVERAGE↓1.6%CHINA0250,000500,000750.000TONS OFU.S.ALFALFAIMPORTED BY CHINA648,980APPETITEFORMILK310In20yearsannualper.capitamilkconsumptionin China rosemore than fivefold.1991THOUSAND20112011ACRE-FEETOFWATER.areused togrow.theU.S.CHINA'S DAIRY COW IMPORTSalfalfa exportedtoChinaeveryyear.From2008to2011imports.ofAustralian,NewZealandand Uruguayan cows-twice as productiveas Chinesecows-grewalmost6o0.percent.Tofeedthose.cows,haydemandincreaseddramatically..+....+..0..5....+.+800★:THOUSANDAMERICANFAMILIESusethe sameamountofwater annually that's usedGOVERNMENTPUSHtogrowalfalfainCalifornia206,923"havea dream,and mydreamis that each Chinese person,especially the children, canaffordtobuyonejin[18fl.oz.]of milk to drink every day."PREMIERWENJIABAO,2006i21,3212008200620112013GRAPHIC:ALVARO VALINO.SOURCES: ARJEN HOEKSTRA,UNRESEARCH SERVICE;SHEFALISHARMA ANESITYOWEsnDAECOEPOLICY:FAO;MINISTRYOFAGRICULTURE,PEOPLE'SREPUBLICOFCHINAZHANGROU,INSTITUTEFORAGRICULTUREANDTRADE
GRAPHIC: ÁLVARO VALIÑO. SOURCES: ARJEN HOEKSTRA, UNIVERSITY OF TWENTE; USDA ECONOMIC RESEARCH SERVICE; SHEFALI SHARMA AND ZHANG ROU, INSTITUTE FOR AGRICULTURE AND TRADE POLICY; FAO; MINISTRY OF AGRICULTURE, PEOPLE’S REPUBLIC OF CHINA TONS OF U.S. ALFALFA IMPORTED BY CHINA 648,980 1991 2011 Percentage contributed by milk consumption 0 250,000 500,000 750,000 CHINA U.S. WORLD AVERAGE 1.6% 6.8% 7.3% 21,321 206,923 2006 2008 2013 2011 2011 Net exporters Net importers 310 ACRE-FEET OF WATER AMERICAN FAMILIES are used to grow the U.S. alfalfa exported to China every year. use the same amount of water annually that’s used to grow alfalfa in California. In 20 years annual per capita milk consumption in China rose more than fivefold. From 2008 to 2011 imports of Australian, New Zealand, and Uruguayan cows—twice as productive as Chinese cows—grew almost 600 percent. To feed those cows, hay demand increased dramatically. “ I have a dream, and my dream is that each Chinese person, especially the children, can afford to buy one jin [18 fl. oz.] of milk to drink every day.” PREMIER WEN JIABAO, 2006 APPETITE FOR MILK VIRTUAL WATER FLOW* AVERAGE ANNUAL WATER FOOTPRINT gallons per capita, 1996-2005 CHINA’S DAIRY COW IMPORTS GOVERNMENT PUSH 800 THOUSAND THOUSAND