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Transparent TransistorAuthor(s): Alexandra GohoSource: Science News, Vol. 166, No. 22 (Nov. 27, 2004), pp. 339-340Published by: Society for Science & the PublicStable URL: http://www.jstor.org/stable/4015851

Accessed: 28/11/2009 12:57

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UmbilicalBountyCordblood showsvalueagainstleukemiaIn two studies comparing treatments foradults with leukemia, scientists find that atransplant of umbilical cord blood offers aviable option for people who don't have awell-matched bone marrow donor.Leukemia occurs when marrow cells-the stem cells for blood-become cancer-ous. Using drugs and radiation, doctors canwipe out nearly all the malignant marrowcells, clearing the way for an infusion ofdonated marrow that can make new,healthy blood cells. Marrow transplantspreciselymatched to a patient'sblood char-acteristics can be remarkably successful.

Only about 20 percent of leukemiapatients have a sibling donor who's a goodmatch, says hematologist MaryJ. LaughlinofCaseWesternReserveUniversityn Cleve-land. Ofthe otherpatients, ewerthan a thirdfind an acceptablematch, she says.Moreover, even a slightly mismatchedmarrow transplant is fraught with risks.That's because marrow delivers more thanjust nascent blood cells; it carries matureimmune cells that can make trouble byattackinga recipient's issues, causing graft-versus-host disease.On the other hand, umbilical cord bloodcontains predominantly naive cells, whicharen'tyet programmed o attackforeigntis-sue, sayshematologistJuliet N. BarkeroftheUniversityof Minnesota in Minneapolis.That'spart of the reason why, since thefirst cord-blood transplant took place in1988, many scientists have eagerly awaitedhard evidence of the technique's benefits.Cord-blood ransplantsin which the donorand recipientaren'trelated or fullymatchedhave shown success in children, who aresmall and resilient. But their potential inadults has been less clear, because a singleumbilical cord contains only about one-tenth as many blood stem cells as the typ-ical bone marrow transplant does.In a new study from Europe, Eliane

Gluckmanof HospitalSt. Louis n Parisandher colleagues compared the outcomes for98 leukemia patients who received cord-blood transplants from donors who wereunrelated and nearly all mismatched andfor 584 similarpatients who received mar-rowtransplants rom unrelated-but-match-ing donors. After 2 years, 36 percent ofthecord-blood recipients and 42 percentofthemarrow recipients were alive and free ofdisease. Statistical analysis indicates thatthese survivalrates aren'tsignificantlydif-ferent, the authors note.In a U.S. study, Laughlin, Barker, andtheircolleaguesassessed367 matched-mar-row transplants, 150 mismatched cord-bloodtransplants,and 83 mismatchedmar-row transplants. After 3 years, 35 percentof patients getting matching marrow werealive. Statistics indicate that no significantdifference between the 26 percent of themismatched cord blood recipients and the20 percent of the mismatched marrowrecipients who survived. The two studiesappear in the Nov. 25 New England Jour-nal ofMedicine.Both research groups found that cordblood, with its small number of stem cells,was slower than marrow to develop into afull complement of blood cells. That makescord-blood recipients more vulnerable toinfection after the transplant, says ClaudioAnasetti of the Moffitt Cancer Center inTampa,Fla.On the otherhand,both studies showthatmismatched cord-blood ransplantsare essapt to spawn acute attacks of graft-versus-host disease than mismatched marrow is.The pros and cons of mismatched mar-row and cord blood seem to balance out,saysTed A. Gooleyof the Fred HutchinsonCancer Research Centerin Seattle.Laughlinsaysthe findings open the wayfor cord-blood treatments in some adultleukemia patients. "We're ecommending,at this point, that if a patient doesn't havea matched marrow [transplant available]in a timely fashion, then proceedwith cordblood," he says. -N. SEPPA

TransparentTransistorSee-throughcomponentforflexibledisplaysImagine a car windshield that suddenlylights up to reveal a map of the city anddirections to your next destination. Orpic-ture a computer display that you can notonly see through but also roll into a tubeand slip into your coat pocket. Scientists inJapan have taken a major step to fulfillingsuch visions with the creation of a trans-parent transistor deposited on plastic.

Hideo Hosono and his colleagues at theTokyo Institute of Technology developeda transparent semiconductor material outof indium gallium zinc oxide. Althoughother research groups have previouslymade transparent circuitry, "their per-formance was not so good," says Hosono.In contrast, prototype transistors madefrom his team's new material are 10 timesas conductive as the silicon transistorsused in today's liquid-crystal displays.Hosono attributes his material'ssuccessto the greater mobility of electrons when avoltage is applied.

"This is the first time I've seen a trans-parent transistoron a plastic substratewithsuch high performance," says EdzerHuitema of Philips Research Laboratoriesin Eindhoven, he Netherlands. "Thisopensup a range of new applications.'Depositing standardsilicon transistorsonplastic s nearly mpossible since the processrequires much heat. "Thatwould melt theplastic," aysHuitema. However, he indiumgalliumzinc oxidegoes onto plasticat roomtemperature.The researchersdescribe heirnew material n the Nov. 25 Nature."Thispaper s exciting," aysJohn Rogersof the University of Illinois at Urbana-Champaign."Thearea of flexible electron-ics has attracted a great deal of attentionoverthe lastfewyears."For nstance,a num-berofgroups in academiaandindustryhavecreated electronic components out oforganic materials for flexible computer dis-plays (SN: 1/31/04, p. 67). However, noneof these materials is transparent.In addition to providing a host of spe-cialty applications, transparent circuitrycould make existing displays brighter byincreasingthe amount of light reachingtheviewer'seyes, adds Rogers.As in allnewtechnologies,devisingmeth-ods for mass production presents a techni-cal hurdle. The method that the researchersused to deposit the transistors on plasticisn't amenable to large-scale manufactur-

NOW YOU SEE IT Transparenttransistorson a sheet of plastic can be seen only atcertain angles. Such circuitrycould find itsway into computer displays in carwindshields and other curved surfaces.

zWWW. SC IENCEN EWS. ORG NOVEMBER 27, 2004 VOL. 166 339

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ing, saysTobinMarksof Northwestern Uni-versity in Evanston, Ill. He notes that itremains to be seen whether the researcherscan find a method for making large quan-tities of high-quality transistors.Hosono says that his group is collabo-rating with an electronics company todevelop the technology. Through this part-nership, he plans to sort out the manufac-turing issues and improve the material'slong-term stability. -A. GOHO

C o n A r t i s tScanning program candiscern true artUntil now, discerning an artist's style hasbeen in the eye of the beholder. However, anew mathematical tool distills style into anarrayof statistics as a potential means tospot forgeries. In a recent study, the tech-nique distinguished eight drawings by the16th-century artist Pieter Brueghel theElder from five imitations attributed to themaster until a decade or so ago.Several digital-imaging researchers,including the study'sauthors, agree that thework is only a first step toward a reliablefraud-detection technique. However, thepreliminary indingsareencouraging,com-ments DavidDonoho, a statistician at Stan-ford University.The technique employs a process calledwaveletdecompositionto break down a dig-ital image into a collection of more-basicimages, called subbands. Just as a musicaltone consists of a low fundamental fre-quencywithhigher-frequencyovertones,animage's low-frequency subbands show thebroad strokes, while higher-frequencysub-bands depict details. Wavelets have beenused in a wide range of image-processingapplications, uch as layeringdetail onto theanimated creatures n the filmA Bug'sLife.Wavelet decomposition is good at ana-lyzing textures. For instance, a smooth,untroubled surface such as a blue skywould show up mostly in the low-fre-quency subbands, while blades of grasswould produce activity primarily inhigher-frequency subbands.Now, in an upcoming Proceedings of theNationalAcademy ofSciences, researchersreport capturing the texture of an artist'sstrokes.

"Amaster might have smooth, consis-tent strokes, say,while an imitator isjerky,"

says study coauthor Hany Farid, a com-puter scientist at Dartmouth College inHanover, N.H.In the new study, the researchers meas-ured 72 statistical features, such as the per-centage of dark portions in a given sub-band. The team found that the genuineBrueghels all had similar statistics, whilethe imitations were significantly differentfrom the Brueghels and from each other.The researchersalsostudied the painting"Virginand Child with Saints,"created inthe studio ofthe Italian artist PietroPerug-ino around the turn of the 16th century.They conclude that it was probablypaintedby at least four artists, in keeping with his-torians'opinion that Perugino painted onlya portion of the work.

While the results are interesting, a studyof only two artists isn't enough to make theart world adopt the method, says NadineOrenstein, a curator at the MetropolitanMuseum of Art in New York."I hink theyneed to study a much larger sample ofmaterial," he says."I think the broad idea is the right one,"says Jitendra Malik of the University ofCalifornia, Berkeley.However, he adds, it's

not clear whether the 72 features the teamexamined are the most effective ones. "Test-ing the approach on many more artistswillprobably enable us to get a handle on whatare the best featuresfor art authentication,"he says. -E. KLARREICH

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MANY HANDS A statistical analysis ofPerugino's "Virgin nd Childwith Saints" (top)suggests that at least four artists contributedto the work. Onlyareas 1, 2, and 3 cluster in arepresentation of six areas (bottom).

N e u r a l F e e lf o r S e e i n gEmotionmay mold earlyvisualactivity n brainWe don't just react emotionally to what wesee. What we see is shaped by what we feel,a new study suggests.When looking at faces displayingfearfulexpressions, people with intact brains orwith brain damage that spares the amyg-dala, an emotion-regulating neural struc-ture, exhibit pronounced activity n certainparts ofthe brain that deal with visual nfor-mation, say neuroscientist Patrik Vuilleu-mier ofthe Universityof Geneva n Switzer-land and his colleagues. People respond toneutral faces with less activity in thesevisual-cortex areas.Moreover,when people with amygdaladamageview fearful aces, they show sparseactivityin these areas, the scientists reportin the NovemberNatureNeuroscience.Peo-ple with the most-extensive tissue loss inthe amygdala displaythe least activity.Taken together, the results indicate thatthe amygdala uses its connections to far-flung areas of the brain to shape the visualperception of fearful objects, according toVuilleumier'sgroup. "Enhanced activationto fearfulstimuli in distant sensory regionsdepends on amygdala function," he scien-tists conclude.Yet, n a separatetrial, people with amyg-dala damage recognized the emotiondepicted in faces displaying any of sixexpressions, including fear.Vuilleumier and his coworkers studied26 people who had brain-damagingepilepsy.Overmany years,the disease hadleft half of them with varying degrees ofamygdala damage;in the rest,neural osseshad spared the amygdala. The team alsostudied13participantswith healthybrains.The scientists used afunctional magneticresonance maging (fMRI)scannerto meas-ure bloodflowthroughoutthe brains of par-ticipants as they viewed a sequence ofimages on a computer screen. Each imagecontainedapairof faces and a pairofhouses,with one pairalignedvertically nd the otherhorizontally. Both faces in a pair showedeither a fearful or a neutralexpression.Participants were told to pay attentiononly to vertically aligned pairs on half thetrials and onlyto horizontally aligned pairson the rest. z

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