37,096 research outputs found
Titanium isotopic evidence for felsic crust and plate tectonics 3.5 billion years ago
No full textThe composition of continental crust far back in Earth's history gives us insight into when plate tectonics ramped up and has influenced ocean chemistry. Greber et al. looked at titanium isotopes in shales, which form from eroded continental crustal sediments, to estimate the composition 3.5 billion years ago, closer to the origins of Earth. They found a silica-rich composition, which indicates that plate tectonics was happening deep in our distant past. Other changes in crustal composition might be linked to changing ocean chemistry and major events such as the oxygenation of our atmosphere
Data to: Molybdenum and titanium isotopic signatures of arc-derived cumulates
No full textWe investigated Mo and Ti isotopic signatures of upper crustal magmatic cumulates comprising hornblendites and gabbros from the Alpine orogen, the Sierra Nevada batholith, the Sanandaj-Sirjan zone and the Kos volcano-plutonic system. Along with the isotope data, also bulk rock major and trace elements as well as in-situ microprobe data of individual minerals were measured.The cumulates and mafic enclaves exhibit Ti isotopic compositions ranging from that of arc-basalts/andesites to significantly lighter values (δ49Ti between −0.15 and + 0.08‰), which is in agreement with a Rayleigh distillation model. The δ49Ti correlates negatively with the abundance of Fe-Ti oxides, suggesting that in samples which have δ49Ti signatures similar to those of arc-basalts, most of the Ti is hosted in pyroxene and amphibole. This indicates that the degree to which Ti isotopes are fractionated in a melt is controlled by the fraction of Ti incorporated into silicate phases versus that incorporated into Fe-Ti oxides.In contrast, the corresponding Mo isotopic compositions of the upper crustal magmatic cumulates and mafic enclaves are more dispersed (δ98MoNIST = −0.02 ± 0.22‰, 2 s.d.) and similar to average arc-basalts. However, Mo concentrations throughout several cumulate and mafic enclave bulk rocks measured are too enriched to be explained by pure fractional crystallization as they do not match modelled melt-cumulate fractionation trends. We distinguish between purely magmatic and predominantly fluid mediated processes leading to Mo enrichment in cumulates, and show that both can play an important role in the generation of high Mo cumulates.Further information can be found in the open access publication, which should be cited when using the data: Storck, J. C., Greber, N. D., Duarte, J. F. V., Lanari, P., Tiepolo, M., & Pettke, T. (2023). Molybdenum and titanium isotopic signatures of arc-derived cumulates. Chemical Geology, 617, 121260.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Data to: Titanium isotopic compositions of bulk rocks and mineral separates from the Kos magmatic suite: Insights into fractional crystallization and magma mixing processes
No full textWe measured the Ti isotopic compositions of mineral separates and bulk rocks from the calc-alkaline Kos volcano-plutonic system, Aegean arc, Greece. Bulk rock Ti isotopic compositions (δ49Ti) increase with differentiation of the magmatic system, from δ49Ti of +0.042 ± 0.033‰ in basalt to +0.654 ± 0.034‰ in rhyolite. We document two different Ti isotope trends produced by (i) fractional crystallization, and (ii) mixing between a basaltic melt and an evolved (rhyolitic) magma. Trend (i) can be explained by a melt-cumulate Ti isotopic fraction factor α of 0.9998 (i.e., the bulk cumulate is on average 0.20‰ lighter than the melt). The mineral separates reveal variable δ49Ti values, with magnetite having the lightest 49Ti/47Ti isotopic composition, biotite being intermediate and neso- and tectosilicates (i.e., olivine, plagioclase and quartz) heaviest. Comparing the TiO2 concentrations of the low-Ti minerals olivine, plagioclase and quartz determined with LA-ICP-MS and isotope dilution shows that the δ49Ti values measured in these minerals reflect their isotopic compositions, and contamination by inclusions is minimal. The difference in δ49Ti between different minerals is smallest in a basalt (Δ49Tiolivine-magnetite = +0.426) and largest in two rhyolites (Δ49Tiquartz-magnetite = +1.083; both ± 0.046‰). Our data agree with theoretical predictions that Fe–Ti oxides have a light δ49Ti signature, and neso/tectosilicate minerals are heavy. Furthermore, the measured difference in δ49Ti between magnetite-olivine, magnetite-plagioclase and magnetite-quartz agree to first order with theoretically predicted inter-mineral Ti isotopic fractionation factors, thus suggesting that the measured inter-mineral Ti isotopic variations are equilibrium in nature.Further information can be found in the open access publication, which should be cited when using the data: Greber, N. D., Pettke, T., Vilela, N., Lanari, P., & Dauphas, N. (2021). Titanium isotopic compositions of bulk rocks and mineral separates from the Kos magmatic suite: Insights into fractional crystallization and magma mixing processes. Chemical Geology, 578, 120303.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
1ST MEASUREMENT OF GAMMA(D(S)(+)-]MU+NU)/GAMMA(D(S)(+)-]PHI-PI+)
No full textComplete Author List:
ACOSTA D, ATHANAS M, MASEK G, PAAR H, BEAN A, GRONBERG J, KUTSCHKE R, MENARY S, MORRISON RJ, NAKANISHI S, NELSON HN, NELSON TK, RICHMAN JD, RYD A, TAJIMA H, SCHMIDT D, SPERKA D, WITHERELL MS, PROCARIO M, YANG S, BALEST R, CHO K, DAOUDI M, FORD WT, JOHNSON DR, LINGEL K, LOHNER M, RANKIN P, SMITH JG, ALEXANDER JP, BEBEK C, BERKELMAN K, BESSON D, BROWDER TE, CASSEL DG, CHO HA, COFFMAN DM, DRELL PS, EHRLICH R, GALIK RS, GARCIASCIVERES M, GEISER B, GITTELMAN B, GRAY SW, HARTILL DL, HELTSLEY BK, JONES CD, JONES SL, KANDASWAMY J, KATAYAMA N, KIM PC, KREINICK DL, LUDWIG GS, MASUI J, MEVISSEN J, MISTRY NB, NG CR, NORDBERG E, OGG M, PATTERSON JR, PETERSON D, RILEY D, SALMAN S, SAPPER M, WORDEN H, WURTHWEIN F, AVERY P, FREYBERGER A, RODRIGUEZ J, STEPHENS R, YELTON J, CINABRO D, HENDERSON S, KINOSHITA K, LIU T, SAULNIER M, SHEN F, WILSON R, YAMAMOTO H, ONG B, SELEN M, SADOFF AJ, AMMAR R, BALL S, BARINGER P, COPPAGE D, COPTY N, DAVIS R, HANCOCK N, KELLY M, KWAK N, LAM H, KUBOTA Y, LATTERY M, NELSON JK, PATTON S, PERTICONE D, POLING R, SAVINOV V, SCHRENK S, WANG R, ALAM MS, KIM IJ, NEMATI B, ONEILL JJ, SEVERINI H, SUN CR, ZOELLER MM, CRAWFORD G, DAUBENMIER CM, FULTON R, FUJINO D, GAN KK, HONSCHEID K, KAGAN H, KASS R, LEE J, MALCHOW R, MORROW F, SKOVPEN Y, SUNG M, WHITE C, WHITMORE J, WILSON P, BUTLER F, FU X, KALBFLEISCH G, LAMBRECHT M, ROSS WR, SKUBIC P, SNOW J, WANG PL, WOOD M, BORTOLETTO D, BROWN DN, FAST J, MCILWAIN RL, MIAO T, MILLER DH, MODESITT M, SCHAFFNER SF, SHIBATA EI, SHIPSEY IPJ, WANG PN, BATTLE M, ERNST J, KROHA H, ROBERTS S, SPARKS K, THORNDIKE EH, WANG CH, DOMINICK J, SANGHERA S, SHELKOV V, SKWARNICKI T, STROYNOWSKI R, VOLOBOUEV I, ZADOROZHNY P, ARTUSO M, HE D, GOLDBERG M, HORWITZ N, KENNETT R, MONETI GC, MUHEIM F, MUKHIN Y, PLAYFER S, ROZEN Y, STONE S, THULASIDAS M, VASSEUR G, ZHU G, BARTELT J, CSORNA SE, EGYED Z, JAIN V, SHELDON P, AKERIB DS, BARISH B, CHADHA M, CHAN S, COWEN DF, EIGEN G, MILLER JS, OGRADY C, URHEIM J, WEINSTEIN A
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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Identifying idiolect in forensic authorship attribution: an n-gram textbite approach
No full textForensic authorship attribution is concerned with identifying authors of disputed or anonymous documents, which are potentially evidential in legal cases, through the analysis of linguistic clues left behind by writers. The forensic linguist “approaches this problem of questioned authorship from the theoretical position that every native speaker has their own distinct and individual version of the language [. . . ], their own idiolect” (Coulthard, 2004: 31). However, given the diXculty in empirically substantiating a theory of idiolect, there is growing concern in the Veld that it remains too abstract to be of practical use (Kredens, 2002; Grant, 2010; Turell, 2010). Stylistic, corpus, and computational approaches to text, however, are able to identify repeated collocational patterns, or n-grams, two to six word chunks of language, similar to the popular notion of soundbites: small segments of no more than a few seconds of speech that journalists are able to recognise as having news value and which characterise the important moments of talk. The soundbite oUers an intriguing parallel for authorship attribution studies, with the following question arising: looking at any set of texts by any author, is it possible to identify ‘n-gram textbites’, small textual segments that characterise that author’s writing, providing DNA-like chunks of identifying material
Gaps in intervals of N-expansions
No full textFor N ∈ N≥2 and α ∈ R such that 0 < α ≤ N − 1, the continued fraction map Tα: [α, α+1] → [α, α+1) is defined as Tα (x):= N/x−d(x), where d: [α, α+1] → N is defined by d(x):= ⌊N/x − α⌋. A maximal open interval (a, b) ⊂ Iα is called a gap of Iα if for almost every x ∈ Iα there is an n0 (x) ∈ N such that xn /∈ (a, b) for all n ≥ n0 . In this paper, all conditions are given in which Iα is gapless. For α =√N − 1 it is shown that the number of gaps is a finite, monotonically non-decreasing and unbounded function of N.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Applied Probabilit
Challenge in R&D Management : Tata Steel A Case Study
No full textThe purpose of R&D management is to promote innovation as
well as wealth creation. The paper traces the history of R&D managementhow it has changed from the first generation when only innovation was the main objective to the fifth generation where IT plays an important role. It is now necessary to understand the needs of market for conducting worthwhile research. The author shares his experience of R&D management at Tata Steel. The experience shows that by adopting judicious R&D strategy it is possible to face the challenges of reconciling innovation with wealth
creation is possible by a judicious R&D strategy
The complete structure of the 55S mammalian mitochondrial ribosome
No full textISSN:0036-8075ISSN:1095-9203ISSN:1095-920
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
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