nature 自然杂志.docx

nature 自然杂志.docx

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nature自然杂志

Reportrebutscancerclaimsandrecommendschangestooversightandmonitoring.

ApaneloftopCanadianscientistshasscrutinizedresearchonthehealthandenvironmentaleffectsofoil-sandsdevelopmentinnorthernAlberta,andfoundexaggeratedclaimsforitsimpactonhealth.Ithasalsoidentifiedweaknessinmonitoringandinadequateevidencetosupportsomeremediationtechnologiesnowinplace.Thepanel,convenedbytheRoyalSocietyofCanada（RSC）,findsfaultwiththemediaandenvironmentalgroupsbutmostofitscriticismfocusesontheindustry-fundedbodyresponsibleformonitoringoil-sandsandtheAlbertaandfederalgovernments.

Thereport,releasedtoday,rebutstheclaimmadebyJohnO'Connor,alocalphysicianandafterwards,byenvironmentalgroupssuchasForestEthics,thattheelevatedcancerratesseeninthenorthernAlbertacommunityofFortChipewyanareduetoexposuretooil-sandscontaminantsfromindustrialactivityfurtheruptheAthabascaRiver.

TheRSCreviewwascommissionedinOctober2009tocastanindependenteyeonsomeofthecontroversialhealthandenvironmentalstatementsmadeabouttheindustry.Thepanelreviewedhundredsofpeer-reviewedpapersandotherstudies.

"Contaminantexposurescannotexplaintheexcesscancerrate,"saysSteveHrudey,anemeritusprofessorinenvironmentalhealthresearchattheUniversityofAlbertainEdmontonandthepanel'schair."Wedon'tquestionthenumbersofcancercasesbuttheair-qualitydataandthewater-qualitymonitoringdatadon'tsupportthat."

Thepanelassessedtheoperationandreclamationoftailingspondsthatholdminingdebris,environmentalregulatoryperformance,andthefeasibilityofreclamation.Theyalsolookedattheimpactsofoil-sandsdevelopmentonregionalwatersupply,waterqualityandground-waterquantity;localairquality;andlevelsofgreenhouse-gasemissions.

EssentialsofGenetics

Whydoesacommercialdairycowproducefourtimesasmuchmilkasmostothermammals?

Whydowelooklikeourcousins?

Whydorosescomeinsomanydifferentcolors?

Theanswerstotheseandotherquestionsaboutthediversityoflivingthingsinvolveprocessesthatoccuratthelevelofgenes.

EssentialsofGeneticsisabriefguidethroughthecoreconceptsofhowgenesarestructuredandhowtheydrivebiologicaldiversity.Thiscoursecanbeusedasaguideforintroductorybiologystudents,asareferenceforadvancedstudents,orasaself-guidedexplorationforgeneralscienceenthusiasts.TopicscoveredincludethenatureofDNAanditsrelationshiptothephysicalcharacteristicsoforganisms;thepassageofDNAfromorganismtoorganism;andthevariationofDNAwithinandacrosspopulationsoforganisms.EssentialsofGeneticsalsoconnectsthesecoreconceptstothescientificprocessbydiscussingthekeytoolsusedtostudyDNAinthelaboratory.Alongsideeachconceptarelinkstobiographiesofscientistswhomademajorcontributionstothefield,aswellastoabroadsetofdetailedreadingsonadvancedtopicsinmoderngenetics.Finally,EssentialsofGeneticscombinesitsdescriptionsofvariouscoreconceptswithhigh-qualityvideoanimationsofmolecularprocessestostimulateanintuitivephysicalunderstandingofgenetics.

Deoxyribonucleicacid,morecommonlyknownasDNA,isacomplexmoleculethatcontainsalloftheinformationnecessarytobuildandmaintainanorganism.AlllivingthingshaveDNAwithintheircells.Infact,nearlyeverycellinamulticellularorganismpossessesthefullsetofDNArequiredforthatorganism.

However,DNAdoesmorethanspecifythestructureandfunctionoflivingthings—italsoservesastheprimaryunitofheredityinorganismsofalltypes.Inotherwords,wheneverorganismsreproduce,aportionoftheirDNAispassedalongtotheiroffspring.Thistransmissionofallorpartofanorganism'sDNAhelpsensureacertainlevelofcontinuityfromonegenerationtothenext,whilestillallowingforslightchangesthatcontributetothediversityoflife.

Butwhat,exactly,isDNA?

Whatsmallerelementsmakeupthiscomplexmolecule,howaretheseelementsarranged,andhowisinformationextractedfromthem?

Thisunitanswerseachofthesequestions,anditalsoprovidesabasicoverviewoftheprocessofDNAdiscovery.

OldestresearchsubAlvinsetforrebirth

FamedoceanographicworkhorsegetsUS$40-millionupgrade.

Sinceitwasfirstlaunchedin1964,thevenerableAlvinsubmersible,ownedbytheUSNavyandoperatedbytheWoodsHoleOceanographicInstitution（WHOI）inMassachusetts,hasenablednumeroushistoricdiscoveries.

OnTuesday,Alvinwaspluckedfromtheseaforthelasttimeinitscurrentform.Withthesub'sfinalmissioncomplete—ithasbeenstudyingthedepthsjustafewkilometresfromthesiteoftheDeepwaterHorizonoilspillintheGulfofMexico—itwillnowundergoaUS$40-millionrebirthasasubmersiblewithdramaticallyimprovedcapabilities.

AlthoughAlvinhashadcountlessimprovementsandoverhauls,andnooriginalpartsremain,ithasmaintainedlargelythesameformsinceitwasgivenanewtitaniumhullin1974.Withmorethan4,000divesunderitsbelt,thesubmersiblehasbecomeaniconicpartofoceanography."Isuspectthat50or100yearsfromnow,Alvinissomethingpeoplewillrememberandwriteabout,inthatitchangedthenatureofwhatweknowabouttheplanet,"saysBruceStrickrott,theAlvinteam'sexpeditionleader.

Duringitslonglife,Alvinhasbeenattackedbyaswordfish;enabledthediscoveryofdeep-seahydrothermalvents;tookhumanstothewreckageoftheTitanicforthefirsttime;andhelpedtorecoveralosthydrogenbomb.Between1968and1969itevensatontheseafloorfor10monthsafteralaunchaccident.Afteritsrecovery,researchersweresurprisedtofindsandwichesinsidethatwerestillinfairshape.

Alvinwillbeupgradedtohavealargercrewcompartment,betterarmsandanadvancedautopilot.WHOI/Lockheed-Martin

In2008,theWHOIabandonedplanstoentirelyreplaceAlvinafterdecidingitwouldbetooexpensive.Theythensettledonaschemetotransformthecurrentsubintwophaseswhilebalancingcost,engineeringpossibilitiesandresearchpriorities.

Thefirstphase,fundedlargelybytheUSNationalScienceFoundation（NSF）andlikelytostretchinto2012,willessentiallyinvolveremovingandreplacingtheentirefronthalfofthesub.Phasetwo,withdetailsandtimingstilltobefinalized,willtransformthebackhalf.

Extreme-depthmakeover

Themostsubstantialinitialchangewillbealargertitaniumspheretocarrycrew.Itwillberatedfordivesupto6,500metres,althoughthesubwillretainitscurrent4,500-metreratinguntilphasetwoiscomplete.Alvinisoneofonlyahandfulofsubmersiblesontheplanetcapableofdivesdeeperthan1,000metres.

Today'sAlvinhasjustthree15-centimetreportholes,onefacingforwardforthepilotandtwoonthesidesforobservers,robbingscientistsofprimeforwardviews.Thenewspherewillhavethreeforward-facing18-centimetreportholesaswellastwosmallersidewindows.Andwhereasdiverspreviouslysatsprawledagainstthesub'sconfinedwalls,everyonewillnowhaveadjustableseatstoworkfrom.

Alvin'smothership,theresearchvesselAtlantis,atdawnjustbeforethesub'slastdive.MarkSchrope

Othermajorupgradeswillincludefibre-opticcables,newcamerasandlights,manipulatorarmscapableofswingingoutforforwardorsideactivity,replacementofanaloguecontrolswithadigitaltouch-screensystem,andanadvancedautopilotsystem.Phasetwoupgrades,estimatedtocostabout$7million,willfocusonimprovingthesub'sbatteryandballastsystems.

"It'sreallyexciting,ourworkhorseisgettingrevitalizedandcomingbackevenstronger,"saysTimShank,anevolutionarybiologistfromtheWHOIwhoparticipatedintheGulfofMexicoexpeditionandisaveteranof55divesinAlvin.

Oilmission

TheretirementofAlvinwaspostponedtoallowanunscheduledNSF-fundedexpeditiontostudytheeffectsoftheDeepwaterHorizonoilspillonthedeepsea.Film-makerMikedeGruyandexpeditionchiefscientistCharlesFisher,fromPennsylvaniaStateUniversityinUniversityPark,tookthelastdive."Itwasanhonour,"saidFisherofhisprizedslot,justaftersurfacing.FamedmarinebiologistandNationalGeographicexplorer-in-residenceSylviaEarlewasalsopresentaspartoffilmingforadocumentarycalledMissionBlue.

ThediveteamwasreturningtoalargeareaofcoralsapparentlydamagedbyoilfromthespillandfirstdiscoveredinNovemberusingaremotelyoperatedvehicle.UsingAlvin,thistimetheygatheredimages,sedimentandsoilsamples,andpositionedatime-lapsecamerathatwilloperateoverthenexttwomonths.Thiswillcreatearecordofhowthecoralsrepairordeteriorateinresponsetotheirrecentdamage,offeringcluestolong-termimpacts.TheresearchershavebeenworkingwithintheNaturalResourceDamageAssessmentprocess,whichlegallyestablishesthedamagesforwhichBPandothersinvolvedintheDeepwaterHorizonspillcouldbeheldliable.

Fearsmountforforensicresearch

ScientistsexpressconcernasUKgovernmentaxesitsforensicservice.

ForensicresearchfacesagrimfutureinEnglandandWales,warnUKforensicscientists.TheirgloomypredictionfollowedhotontheheelsoftheUKgovernment'sdecisiontowinddowntheForensicScienceService（FSS）.

TheFSSisagovernment-ownedcompanyheadquarteredinBirminghamthatsellsitsservicestocustomersincludingpoliceforcesinEnglandandWales.Thegovernmenthasnowpromisedtoselloffasmuchofitsoperationsaspossibletotheprivatesector.Althoughithadpreviouslybeensuggestedthatthecompanywouldbeprivatized,itiscurrentlylosing£2million