text_combined: johvdvutqrpvcaaasalertsorg science online week science alert 319 5866 sponsored harvard business school leadership strategy pharmaceuticals biotech june 16 2008 leading sciencebased enterprises june 1520 2008 consider innovation amplification comes sciencebased businesses true way achieve competitive advantage managing innovation identifying scientific breakthroughs today commercial appeal tomorrow easy feat response challenge harvard business school developed two highly targeted programs help leaders sciencebased businesses advance scientific knowledge capture value please visit wwwexedhbseducategoryscihtml learn current issue previous issue science express science products science journal week science volume 319 issue 5866 dated february 22 2008 available httpwwwsciencemagorgcontentvol319issue5866twisdtl copy week science section appended week science february 22 2008 319 5866 week science carboxysome building blocks carboxysome bacterial microcompartment roughly 100 nanometers diameter sequesters enzymes involved carbon fixation proteinaceous outer shell icosohedral geometry typically involves combination hexameric pentameric building blocks found certain viral capsids four abundant shell proteins two known types carboxysomes known form hexamers tanaka et al p 1083 report structure two carboxysome proteins form pentamers appropriate size shape inserted hexagonally packed layers form vertices icosohedral shell modelbuilding gave two plausible ways pack hexamers pentamers build complete carboxysome shell credit yeates ductility ceramic composites nature found routes take weak brittle starting materials make stronger tougher composites incorporating biopolymers calcium carbonate form nacre although scientists able use better starting materials able achieve level improvement sophistication bonderer et al p 1069 see perspective ortiz boyce fabricate composite submicrometerthick alumina embedded polymer matrix chitosan high tensile strength controlling thickness ceramic films determine mode fracture ensure composites remain ductile photon turnstile highquality optical microresonators influence delay propagation light coupled optical fibers dayan et al p 1062 show coupling atom evanescent field resonator dramatic effect propagating light fiber atom coupled input stream photons regularized output single photons optical turnstile prove useful light source quantum information processing whither weather west recently winter rain less snow fallen western united states previously snow melted earlier year changes increased river flows spring decreased summer barnett et al p 1080 published online 31 january conducted multivariate climate change detection attribution study western united states 1950 1999 found 60 trends river flow winter air temperature snow pack reflect anthropogenic climate change despite high variability throughout records results suggest crisis water supply western united states relies heavily late spring snow melt agriculture may looming little nudge scanning probe microscopes used manipulate individual atoms create structures atomic scale despite widespread use difficult determine forces needed move atom ternes et al p 1066 see perspective custance morita report simultaneous measurements vertical lateral forces exerted adsorbate either co atoms co molecules lateral manipulation using atomic force microscope afm simultaneously detected tunneling current oscillating afm tip sample surface recorded variations tunneling gap conductance force measurements credit ternes et al social quakes earthquakes constantly color earths plate boundaries extent two quakes connected let alone series quakes clear aftershocks cover small number quakes primarily series successively weaker overall question partly statistical partly mechanistic determining one quake affects stress another fault marsan et al p 1076 develop model triggering based two simple assumptions without need fitting large number parameters fault model applied southern california quakes implies small earthquakes disproportionate effect triggering cascading events common tau microtubule motors microtubuleassociated protein tau implicated neurodegenerative diseases including alzheimers disease neither normal pathological role well understood microtubules cells densely coated microtubuleassociated proteins including tau dixit et al p 1086 wanted learn motor proteins navigate coated microtubules authors incorporated several isoforms truncations tau cell free assay build complex system mimicking cell environment encounters individual motor proteins tau microtubules observed directly revealed dramatic differences effects tau motility two microtubulebased motors dynein versus kinesin appears likely tau spatially regulate balance microtubuledependent axonal transport neurons viral culprit cancer discovery virus contributes pathogenesis human cancer provides new options prevention treatment illustrated development hpv human papillomavirus vaccine prevention cervical cancer feng et al p 1096 published online 17 january see perspective viscidi shah provide tantalizing evidence previously uncharacterized human polyomavirus may contributing factor merkel cell carcinoma mcc rare highly aggressive form skin cancer authors initially detected viral dna sequences mcc samples digital transcriptome subtraction methodology reveals rare foreign transcripts sequenced full genome virus termed merkel cell polyomavirus mcv although mcv sequences present small percentage control tissues strongly associated mcc integrated within tumor genome pattern suggests mcv infection preceded clonal expansion tumor cells credit feng et al beyond africa analysis dna sequence variation increased understanding genetic diversity humans revealing example humans migrated africa dispersed across globe displacing hominids process order gain deeper understanding li et al p 1100 studied half million single nucleotide polymorphisms human genome diversity panel representing 51 populations around world broad sweep analysis uncovers finescale population structure example distinguishing orcadian french northern italian populations bergamo tuscan groups supports serial founder model nonafrican populations form sequential chain colonies radiated africa tagging recruitment learning stabilizating longterm memories requires expression new gene products nucleus generate physical changes tags small subset synapses dendrites neuron synthesis ampa receptors increased learning suggestive possible role process matsuo et al p 1104 developed transgenic mice monitor trafficking turnover newly synthesized ampa receptors fearconditioning paradigm coupling expression fluorescent receptors neuronal activity specifically examined pool newly synthesized receptor new receptors delivered spines several hours behavioral training suggests time learning changes occur spines allow capture newly synthesized ampa receptors later time points spike coding retina retinas task transduce visual images neural signals process signals transmit result optic nerve brain general notion sensory systems timevarying visual stimulus produce timevarying firing rates among retinal ganglion cells rates drives processing subsequent visual stations unclear however whether type sensory encoding could support rapid signal detection image processing visual system capable gollisch meister p 1108 show instead single spike per ganglion cell sufficient accurately communicate new visual image meaning spike conveyed precise time occurrence relative spikes ganglion cells several criteria message powerful robust conveyed firing rate importantly transmits image information shortest possible time predicting human behavior well neuronal networks model human interactive decisionmaking recently important role regret human decisionmaking demonstrated marchiori warglien p 1111 see perspective cohen modified neuronal network feedback 21 interactive games take role regret account introducing regret feedback dramatically improved efficacy neuronal networks allowed precise prediction human behavior conventional economic learning theories exploiting nonlinearity molecular junctions use molecules switching elements electronics stems small size possibility molecular junction could exhibit nonlinear responses enable compact realizations logic operations galperin et al p 1056 overview theory electronic transport molecular junctions moves beyond tunneling regime higher voltages 03 volts molecular vibrations scatter electrons provide spectroscopic signatures higher biases strong coupling allows electron reside longer times molecule leads strong polarization charging well nonlinear responses coulomb blockades negative differential resistance dynamical switching tracking interfacial mixing highresolution electron microscopy identify columns atoms crystalline material even identify individual vacancies structure defects grain boundary using fifthordercorrected scanning tunneling transmission electron microscope muller et al p 1073 determined chemical species bonding la07sr03mno3srtio3 multilayer observed asymmetries intermixing interfaces uptake la titanium oxide layers telomere tag telomeresthe ends linear mammalian chromosomesare regulated length protected recognition dna damage repair systems shelterin complex includes proteins telomeric repeat binding factors 1 2 trf1 trf2 two proteins recruit members shelterin complex associated telomere factors negatively regulate telomere length chen et al p 1092 published online 17 january show trf1 trf2 structurally quite similar interact factors distinct ways tin2 binds trf1 nterminal trf homology trfh domain trf2 cterminal domain whereas apollo binds trf2 via trfh domain manner trf1 binds tin2 two loops trfh domain determining distinct binding specificities binding regions tin2 apollo share pentameric sequence may help identify telomere accessory proteins regulating regulon presence galactose yeast saccharomyces cerevisiae transports sugar cytoplasm galactose binds gal3 protein turn sequesters gal80 repressor away transcriptional activator gal4 resulting induction galactose metabolizing enzymes induction rapid suggested another unknown factor must somehow involved galactose regulon kumar et al p 1090 identified factor nicotinamide adenine dinucleotide nad phosphate nadp gal4gal80 complex nad sandwiched two proteins nadp hand inhibits interaction gal4 gal80 mutations potential affect nadbinding site gal80 result even faster induction suggests gal80 sensing balance nad nadp thus metabolic state cell unsubscribe edit subscriptions service httpwwwsciencemagorgcgialertsmain written requests unsubscribe may sent customer service 1454 page mill road palo alto ca 94304 usa magazine news signaling careers multimedia collections help site map rss subscribe feedback privacy legal us advertise us contact us 2008 american association advancement science rights reservedaaas partner 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