普特.docx

普特.docx

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普特

830OldFashionedIceCreamMakers

Haveyoueverseenanold-fashionedicecreammaker?

Nestledinsidethewoodenbucket,there’sametalcanisterwithahandcrankontop.Crankingthehandlescrapesthesweet,creamymixturefromthesidesofthemetalcanister,whichsitsinabathoficewaterandsalt.Butwhatdoessalthavetodowithfreezing?

Whynotjustuseplainicewater?

Thebathofsaltyicewaterfreezesicecreamfasterthanplainicewatercould.Andspeedyfreezingdoesmorethanminimizethecrankingtimeonahotsummer’sday.Afastfreezingprocessalsoyieldssmallcrystals,insuringasilkytexture.Slowerfreezingcouldmakebigcrystalswithanunpleasantcrunch,kindoflikeicecreamthat’sgrittywithfreezer-burn.Thecoldestthatsaltlessicewatercangetis32degreesFahrenheit,wherethere’sabalancebetweentheratesofmeltingandfreezing.Addsalttothemixandtheenergybalancetips,allowingthetemperaturetodropbelow32withoutfreezing.

SaltyLet’ssayyoutossahandfulofsaltintoicewater,andthetemperaturedropsto20degrees.Atthislowertemperature,saltyicewatercanabsorbmoreheatfromthemixtureinsidethecanister,freezingitfasterthansaltlessicewatercould.Thismeansyoucanquitcrankingsooner,kickbackontheporchandenjoysomegood-old-fashionedicecream.

827TheFutureOfMales

Haveyoueverheardpredictionsthatonedaywomenwillbeabletohavebabieswithoutmen?

ItturnsoutthatsomespeciesoftheWhiptaillizardhavefiguredouthowtodothisandcompletelyeliminatedthemalesex.

FemalesCloningThemselves

Thefemaleshavetheabilitytolayeggsthathatchandgrowintohealthylizardswithoutneedingtobefertilizedbyamale.Theoffspringareexactandcompletegeneticduplicatesofthemothers.

Essentiallythefemalesareclonnigthemselves.

RolePlayingIfthatweren’tenough,thefemalelizardstaketurnsrole-playing.Theyperformamatingritualinwhichonelizardactslikethemale,andthesecondlizardactslikethefemale.Theritualcausesthelizardactingasthefemaletoovulateandlayhereggs.Then,afewweekslater,thetwolizardsswitchrolesandrepeatthisprocesssothatthesecondfemalewillbeabletoovulateandlayhereggs.

GeneticVariationItraisesalotofinterestingquestions.Forexample,it’snotclearhowwellanallfemalespeciescanevolveandadapttoenvironmentalchanges.Aspecies’survivaldependsinpartonvariationamongitsmembers.Ifallthemembersofaspeciesareidentical,chancesaregreaterthatsomethinglikeachangeintheclimateoradiseasewillwipethemallout.

823StoppingSmokingCanLeadToWeightGain

Oneofthereallyinterestingthingsaboutthenicotineincigarettesisthatitworksintwoways.

AllAboutNicotine

Whenyoutakealongdrag,itactsasatranquilizer,butwhenyouinhaleinshortpuffs,itactsasastimulant.Andoneoftheside-effectsofstimulantsisthattheysuppresstheappetite.

Oneofthemostsuccessfuladcampaignsforcigarettesencouragedwomentosmokeinsteadofeat.Andthefactisthatcigarettesmokersdoweighlessonaveragethannonsmokers.Researchshowsthatquittingsmokingcanmakeyougainbetweenfiveandtwelvepounds.

StopSmoking!

Physiciansrecommendmoderateexerciselikewalkingforthirtyminutes,threetimesaweek.Notonlydoesexercisehelpcontrolweightgain,italsohelpseasethestressfulfeelingsassociatedwithquitting.Youcanalsotrytolimitalcoholandcutdownonfoodshighinfat,butkeepinmindthatmostexpertsthinkthatitisn’tagoodideatogoonastrictdietandtrytoquitsmokingatthesametime.Youshouldfocusononehealthchallengeatatime.

821WhyBeASportsFan?

Evernoticehowsportsfansinsistontalkingasifthey’reoneoftheplayerswhenallyoudoiswatchthegamesonTV?

Itcouldbethatcheeringaparticularteamgivesthemanidentityandsenseofbelonging.Theyaredefiningthemselvesaspartofagroup.Eveniftheteamloses,thefanswatcheverygamewithjustasmuchenthusiasmasthelast.

Thepsychologicalbenefitofbeingpartofagroupismoreimportantthanwhetherateamwins.Therealfansarethosewhokeeprootingfortheirteamsevenwhentheylose.Afterall,anotherfunctionofagroupistosticktogetherandprotectitsmembersinthefaceofadversity.Rootingforalosingteamincreasesyoursenseofallegiancetothegroup.

819Ow!

WhyHotFeelsCold

Kidsdon’ttrythisathome!

Haveyoueverdippedyourtoeintoaveryhotbathandfeltaflashoficycoldjustbeforeyourealizethatitsreallyburning?

Afteryoupullyourtoeout,youmightwonderwhatcausesveryhotwatertofeelcold.

Thisoddsensationiscalledparadoxicalcoldandiscausedbythetemperaturereceptorsintheskin.Thereareseparate,specificreceptorsthatrespondtodecreasesorincreasesinskintemperature.Ifskintemperaturedrops,thecoldreceptorsfireandifitincreases,thewarmthreceptorsfire.However,ifastrongstimulus,likeveryhotwater,canstimulatenotonlythewarmthreceptorsbutalsostimulatethepainreceptors.Thesewarnusthatwearedoingourselvesdamage,andshouldtakeactiontopreventit.Thestrongstimuluscanalsocausetheabnormalstimulationofthecoldreceptors.

Over-stimulationcancausetheconfusingsensationofcold,hotandpain,butaslongaswe’reclearaboutpullingthetoeouttosafety,paradoxicalcoldisjustanotherstrangetrickofthesenses.

813ARoseByAnyOtherName

Justsayingtheword“rose”conjuresupimagesofromance,secretadmirers,Valentinesgifts,andbridalbouquets.Romanticsimaginesoft,redpetalsandlong,gracefulstems,butpracticalgardenersknowallaboutpainful,pointythorns.Asthesayinggoes,everyrosehasitsthorn.But,whatwecallthornsareactuallynotthornsatall.

Thorns

Thorns,likethosefoundontheHawthorntree,aremodifiedbranchesthatprojectfromthestemandbranchesofawoodyplant.

Theyareverysharpandquitestrongbecausetheyaremadeofthesamestuffasthestemofthetreeorbush.Thornsaredeeplyembeddedinthewoodystructureoftheplantandcan’tbebrokenoffeasily.Thosenastypointsonthestemoftherosearenottruethorns:

theyarewhatscientistscall“prickles.”

PricklesPricklesaresmallerthanthorns:

theyaresharpoutgrowthsoftheplant’souterlayers,theskin-likeepidermis,andthesub-epidermallayerjustbeneathit.Unlikeathorn,apricklecanbeeasilybrokenofftheplantbecauseitisreallyafeatureoftheouterlayersratherthanpartofthewood,likeathorn.

Bothpricklesandthornsprotecttheplantfrompredators,and,maybe,fromloverslookingforafreebouquet.Butperhapswecalltheroseprickles“thorns”becausesaying“everyrosehasitsprickle”doesn’tseemtodojusticetothepainofunrequitedlove.

812DoesFacebookLeadToLoneliness?

DearAMomentofScience,

I’mnotabigFacebookuser,butIhavefriendswhoare.AndI’venoticedthatsomeofthemareconstantlyupdatingtheirstatus.Wheresomepeoplemightpostamessageonceaday,othersseemtobepostingsomethingeveryfewminutes.Cansciencehelpexplainthisphenomenon?

Interestingquestion.Ofcourse,therearemanyreasonswhypeoplejoinandpoststuffonFacebook.Butresearchershavebeguntostudythephenomenonyoudescribe.AndtheyfoundthatcopiouspostingonFacebookmayhavesomethingtodowithloneliness.

BeingLonely

Specifically,theresearchersfoundthatpeoplewhoupdatetheirstatusmoreoftenreportfeelinglesslonelythanpeoplewhopostlessoften.Now,granted,thestudylookedatonly100undergraduatestudents,aroundhalfofwhomwereinstructedtoupdatetheirstatusmorefrequentlythantheynormallywould.Andthentheyselfreportedontheirlevelsofloneliness,happiness,depression,andsoon.Sothisquestionrequiresmoreindepthresearch.

FeelingHappy

Still,it’sanoteworthyfinding.Interestingly,thestudentswhopostedmoredidnotreportfeelinghappier,orlessormoredepressed.Sostatusupdatesseemtohavesomethingtodospecificallywithfeelinglesslonelyandmoresociallyconnected.WhatIfindevenmoreinterestingisthatitdidnotseemtomatterwhetherthestudentsgotany“Likes”orresponsestotheirposts.Justtheactofupdatingtheirstatuswasenoughtomakethemfeellesslonely.

801WhatCausesAltitudeSickness?

AnyonewhohasvacationedinthehigherelevationsofColorado,suchasVailandEstesPark,willtellyoualtitudesicknesscanbearealproblem.Lossofappetite,nausea,vomiting,weakness,dizziness,anddifficultysleepingcanplaguethosevisitingareasovereightthousandfeet.

HighUp

Altitudesicknessresultsfromthelackofoxygenathighelevations.Atthirteenthousandfeet,everylungfulofairholdsonlysixtypercentofwhatitwouldatsealevel.Despitethatfact,manyindigenouspeopleliveinareasoflowoxygenconcentrationwithfewadverseeffects.Thebigquestionis,howdotheysurvive?

Thebodycanadapttolowoxygenlevelsbymakingmorehemoglobin,anoxygen-carryingmoleculeinredbloodcells.Buttoomuchhemoglobinoveralongperiodoftimecanputapersonatriskofbloodclots,stroke,orchronicmountainsickness.Scientistswonderedhowmountainpeoplecanremainhealthylivingathighaltitudes.Toseeifgenescontribute,scientistsanalyzedthegenomesofthreeethnicgroupslivingataltitudesovertwelvethousandfeet,twofromEthiopia,andTibetans.

Oromo

OneEthiopiangroup,theOromo,copethesamewaylowlandersdo,bymakingmorehemoglobin.TheAmharaandTibetans,ontheotherhand,havehemoglobinlevelstenpercentlowerthantheOromo.Doesgeneticvariationaccountforthis?

ScientistsfoundthatboththeAmharaandTibetanhighlanderspossessedgeneticvariantsassociatedwithlowhemogl