n°28I quarterlyI January 2013 Live from the Labs | 15 w Physics Palaiseau Bio-inspired Computing Memory 02 treatment of a model BYBrettkraaBel themstoreinformation,muchlikeferromagnetsin cancer cell line (hela) magneticharddisks,”explainsBibes.Whenplaced withlImk inhibitor w betweenmetalelectrodes,thepolarizationoftheHow long does it take your brain to recognize Pyr-1 increases stable microtubules content a face? Not long. yetforcomputers,thisisanex- ferroelectric film determines the electrical resis- (green) without tremelychallengingtask.Now,researcherManuel tanceofthememristor.Inthisway,theresistanceof affecting dynamic Bibes1andhiscolleaguesatCNRS,Thales,andthe thedevicedependsonitsvoltagehistory,permitting microtubules (red). universityofCambridgehavemimickednatureby memorystorage. Stable buildingelectroniccomponentscalledmemristors In contrast to conventional memory circuits, microtubules that are inspired by the brain’s computational whichstoreonlytwobits,theresistanceofferroelec- circuitry.2 tricmemristorscanbefinelytuned,allowingthem Inourbrain,neuronsactascomputingunits, tocontainmuchmoreinformation.Thisispossible each of which is connected to a thousand other because the film becomes polarized in nm-sized neuronsbysynapses.Butsynapsesalsoserveas chunks,calleddomains.Byvaryingthevoltageap- memory,whichcontrastsstarklywiththedesignof pliedacrossthefilm,thedensityofpolarizeddo- computers,wherememoryisaseparateentityfrom mainscanbepreciselycontrolled,allowingtheresis- thecomputingunit.Amuchmoreglaringdifference tancetobetunedbetweenaminimumvalueanda isthatneuronscommunicatethroughvoltagepulses maximumvalue300timesgreater. ratherthandirectcurrent(dC)voltages.Theresultis Another advantage of ferroelectrics thatthebrainisfarmorepowerfulandenergy-effi- isthattheyhavebeenstudiedfordecades,sothe cientthananyman-madecomputer. mechanismsofdomainformationandinteraction ANCERRESEARCH Memristorsmimicsynapsesinthattheyactas arewellunderstood.Theteamnowplanstousethis wireswhoseelectricalresistancedependsonthe knowledgetobuilda“neuralnetwork”with10elec- previousvoltagepulsessentthroughthem,giving tronicneuronsand100memristorsynapses. /C RE them memory. The first memristor, produced in 01.unitémixtedephysiqueCNRS/Thales. è AFANECH 2008,wasbasedonthediffusionofionsthrougha 02. Chanthboualaetal.,“Aferroelectricmemristor,”Nature Materials, 2012.11:860-4. thinfilm;aphenomenonpoorlyunderstoodanddif- © ficulttocontrol.Toovercomethisdifficulty,Bibes andhiscollaboratorshavebuiltmemristorsbased contactInformatIon: IBmc,strasbourg. onultrathinferroelectricfilmssandwichedbetween Matteo Negroni > m.negroni@ibmc-cnrs.unistra.fr metalelectrodes. contactInformatIon: Institutalbert Bonniot,grenoble. Ferroelectricfilmsprovideananswerbecause cnrs /thales, Palaiseau. Laurence Lafanechère theyretainanelectricpolarizationafterbeingex- Manuel Bibes >laurence.lafanechere@ujf-grenoble.fr > manuel.bibes@thalesgroup.com posedtoanelectricfield(i.e.,avoltage).“Thislets and more news... Islamic Art q thetuquztimur staying Alertlamp, one of the w sing a non-invasive and mobileraman spectroscopy technique on mamluk objects w Blue light proved as effective asu four ancient lamps, researchers1 have revealed the secrets of Mamluk analyzed byraman coffee to keep drivers alert during long spectroscopy. sultanate enamellers (Egypt andsyria: 1250-1517).2 Lapis lazuli or journeys at night.1 Althoughthepositive cobalt were used for blue, and mixed with Naples yellow to produce effectofbluelightonnighttimealertness green, while tin oxide precipitates or calcium phosphate were used wasknownsince2005forsimpletasks,ithad for white. Comparison with replicas by 19th century master neverbeentestedonhighly-complextasks glassmakers unambiguously shows that very different pigments likedriving.Thestudy,conductedbyteams were used in that later period. This study therefore provides fromFrance2andSweden,couldleadtothe tools to identify recently-restored sections or copies developmentofelectronicanti-sleep from originals. /CNRS systemsbuiltintovehicles. 01.Laboratoirededynamique,interactionsetréactivité(CNRS/uPMC). OLOMBAN 01.J.Taillardetal.,PLoS ONE,2012.7(10):e46750.02.P.Colombanetal.,J. Raman Spectrosc.,2012.43: 1975–84. 02.Sommeil,attentionetneuropsychiatrie(CNRS). C P. ©
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