4,725 research outputs found

    GEOS-C radar altimeter characteristics

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    The purpose of the GEOS-C mission and the operating characteristics of its special K-band altimeter are outlined. Special attention was given to the possible use of height measurements and other supporting GEOS-C data to evaluate the feasibility and value of altimetry on a global basis

    Transformation and fate of microphytobenthos carbon in subtropical, intertidal sediments: potential for long-term carbon retention revealed by <sup>13</sup>C-labeling

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    Microphytobenthos (MPB) are ubiquitous in coastal sediments, but the fate of their production (carbon biomass) is poorly defined. The processing and fate of MPB-derived carbon in subtropical intertidal sediments was investigated through in situ labeling with <sup>13</sup>C-bicarbonate. Of the added <sup>13</sup>C, 100% was fixed within ~ 4 h, suggesting that MPB productivity was limited by inorganic carbon availability. Although there was rapid transfer of <sup>13</sup>C to bacteria (within 12 h), a relatively small fraction of <sup>13</sup>C was transferred to heterotrophs (up to 12.5% of total fixed <sup>13</sup>C into bacteria and 0.01% into foraminifera). MPB was the major reservoir for <sup>13</sup>C throughout the study, suggesting that production of extracellular polymeric substances was limited and/or MPB recycled <sup>13</sup>C. This retention of <sup>13</sup>C was reflected in remarkably slow estimated turnover times for the MPB community (66–100 d). Over 31 d, ~ 70% of the <sup>13</sup>C was lost from sediments. This was primarily via resuspension (~ 55%), enhanced by elevated freshwater flow following rainfall. A further ~ 13% was lost via fluxes of dissolved inorganic carbon during inundation. However, <sup>13</sup>C losses via dissolved organic carbon fluxes from inundated sediments (0.5%) and carbon dioxide fluxes from exposed sediments (<0.1%) were minimal. The retention of ~ 30% of the carbon fixed by MPB within one tidal exposure after > 30 d, despite high resuspension, demonstrates the potentially substantial longer term retention of MPB-derived carbon in unvegetated sediments and suggests that MPB may contribute to carbon burial ("blue carbon")

    Computational analysis of stochastic heterogeneity in PCR amplification efficiency revealed by single molecule barcoding

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    The polymerase chain reaction (PCR) is one of the most widely used techniques in molecular biology. In combination with High Throughput Sequencing (HTS), PCR is widely used to quantify transcript abundance for RNA-seq, and in the context of analysis of T and B cell receptor repertoires. In this study, we combine DNA barcoding with HTS to quantify PCR output from individual target molecules. We develop computational tools that simulate both the PCR branching process itself, and the subsequent subsampling which typically occurs during HTS sequencing. We explore the influence of different types of heterogeneity on sequencing output, and compare them to experimental results where the efficiency of amplification is measured by barcodes uniquely identifying each molecule of starting template. Our results demonstrate that the PCR process introduces substantial amplification heterogeneity, independent of primer sequence and bulk experimental conditions. This heterogeneity can be attributed both to inherited differences between different template DNA molecules, and the inherent stochasticity of the PCR process. The results demonstrate that PCR heterogeneity arises even when reaction and substrate conditions are kept as constant as possible, and therefore single molecule barcoding is essential in order to derive reproducible quantitative results from any protocol combining PCR with HTS

    Signal for CP violation in B±PPˉπ±B^{\pm} \to P {\bar P} \pi^{\pm} decays

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    We analyze the partial rate asymmetry in B±PPˉπ±B^{\pm} \to P {\bar P} \pi^{\pm} decays (P=π+,K+,π0,η P = \pi^+, K ^+, \pi^0, \eta) which results from the interference of the nonresonant decay amplitude and the resonant amplitude for B±χc0π±B^{\pm} \to \chi_{c0} \pi^{\pm} followed by the decay χc0PPˉ\chi_{c0} \to P {\bar P} . The CP violating phase γ\gamma can be extracted from the measured asymmetry. We find that the partial rate asymmetry for B±π+ππ±B^\pm \to \pi^+ \pi^- \pi^\pm is 0.33 sinγ0.33~sin \gamma, while for B±K+Kπ±B^\pm \to K^+ K^-\pi^\pm it amounts 0.45 sinγ0.45~ sin \gamma.Comment: 3 pages, latex, no figures, Talk given by S. Fajfer at the Hyperons, Charm and Beauty Hadrons, Genova, Italy, 30 June -3 July 1998, to appear as proceedings in Nucl. Phys.

    Music in advertising and consumer identity: The search for Heideggerian authenticity

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    This study discusses netnographic findings involving 472 YouTube postings categorized to identify themes regarding consumers’ experience of music in advertisements. Key themes relate to musical taste, musical indexicality, musical repetition and musical authenticity. Postings reveal how music conveys individual taste and is linked to personal memories and Heidegger’s coincidental time where moments of authenticity may be triggered in a melee of emotions, memories and projections. Identity protection is enabled as consumers frequently resist advertisers’ attempts to use musical repetition to impose normative identity. Critiques of repetition in the music produce Heideggerian anxiety leading to critically reflective resistance. Similarly, where advertising devalues the authenticity of iconic pieces of music, consumers often resist such authenticity transgressions as a threat to their own identity. The Heideggerian search for meaning in life emphasizes the significance of philosophically driven ideological authenticity in consumers’ responses to music in advertisements

    Ngrams and Engrams: the use of structural and conceptual features to discriminate between English translations of religious texts

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    In this paper, we present experiments using the Linguistic Inquiry and Word Count (LIWC) program, a ‘closed-class keyword’ (CCK) analysis and a ‘correspondence analysis’ (CA) to examine whether the Scientology texts of L. Ron Hubbard are linguistically and conceptually like those of other religions. A Kruskal–Wallis test comparing the frequencies of LIWC category words in the Scientology texts and the English translations of the texts of five other religions showed that there were eighteen categories for which the Scientology texts differed from the others, and between one and seventeen for the other religions. In the CCK experiment, keywords typical of each religion were found, both by comparing the religious texts with one another and with the Brown corpus of general English. The most typical keywords were looked up in a concordancer and were manually coded with conceptual tags. The set of categories found for the Scientology texts showed little overlap with those found for the others. Our CA experiments produced fairly clear clusters of texts by religion. Scientology texts were seen at one pole on the first factor, with Christian and Islamic texts at the other. It appears that, in several ways, the Scientology texts are dissimilar to the texts of some of the world's major religions

    Multi-wavelength Observations of Dusty Star Formation at Low and High Redshift

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    This paper examines what can be learned about high-redshift star formation from the small fraction of high-redshift galaxies' luminosities that is emitted at accessible wavelengths. We review and quantify empirical correlations between bolometric luminosities produced by star formation and the UV, mid-IR, sub-mm, and radio luminosities of galaxies in the local universe. These correlations suggest that observations of high-redshift galaxies at any of these wavelengths should constrain their star-formation rates to within 0.2--0.3 dex. We assemble the limited evidence that high-redshift galaxies obey these locally calibrated correlations. The characteristic luminosities and dust obscurations of galaxies at z ~ 0, z ~ 1, and z ~ 3 are reviewed. After discussing the relationship between the high-redshift populations selected in surveys at different wavelengths, we calculate the contribution to the 850um background from each. The available data show that a correlation between star-formation rate and dust obscuration L_dust/L_UV exists at low and high redshift. This correlation plays a central role in the major conclusion of this paper: most star formation at high redshift occurred in galaxies with 1 < L_dust/L_UV < 100 similar to those that host the majority of star formation in the local universe and to those that are detected in UV-selected surveys. (abridged)Comment: Scheduled for publication in ApJ v544 Dec 2000. Significant changes to section 4. Characteristic UV and dust luminosities of star-forming galaxies at redshifts z~0, z~1, and z~3 presented. Existence of extremely obscured galaxies more clearly acknowledged. Original conclusions reinforced by the observed correlation between bolometric luminosity and dust obscuration at 0<z<
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