985 resultados para Behner, Frederick G., 1874-1968
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Democracia y desarrollo / Femando H. Cardoso. -- ¿Es posible crecer con equidad? / Joseph Ramos. -- Estabilidad y estructura: Interacciones en el crecimiento económico / José María Fanelli y Roberto Frenkel. -- Reforma a los sistemas de pensiones en América Latina / Andras Vthoff. -- Tendencias económicas en China: significado para el comercio con América Latina y el Caribe / Mikio Kuwayama. -- El Intercambio económico entre América Latina y las economías dinámicas dé Asia / Ronald Sprout. -- La relación económica entre la América Latina y la Unión Europea / Roberto Smith Perera. -- Nuevas Implicaciones de las reglas de origen / Eduardo Gitli. -- Globalización y reestructuración energética en América Latina / Femando Sánchez Albavera. -- El caleidoscopio de la competitividad / Geraldo Mailer. -- La privatización de los servicios públicos del agua / Miguel Solones. -- ¿Cuánto se puede gastar en educación? / Guillermo Labarca. -- Mujeres y migrantes: desigualdades en el mercado laboral de Santiago de Chile / Ivonne Szasz.
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Democracy and development / Fernando H. Cardoso. -- Can growth and equity go hand in hand? / Joseph Ramos. -- Stability and structure: interactions in economic growth / José Maria Fanelli and Roberto Frenkel. -- Pension system reform in Latin America / Andras Uthoff. -- Recent economic trends in China and their implications for trade with Latin America and the Caribbean / Mikio Kuwayama. -- Economic relations between Latin America and the high-performing Asian developing economies / Ronald Sprout. -- Economic relations between Latin America and the European Union / Roberto Smith Perera. -- Rules of origin: new implications / Eduardo Gitli. -- Globalization and restructuring the energy sector in Latin America / Femando Sánchez Albavera. -- The kaleidoscope of competitiveness / Geraldo Müller. -- The privatization of public water utilities / Miguel Solones. -- How much can we spend on education? / Guillermo Labarca. -- Women and migrants: inequalities in the labour market of Santiago, Chile / Ivonne Szasz.
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Infection with bacteria such as Chlamydia pneumonia, Helicobacter pylori or Porphyromonas gingivalis may be triggering the secretion of inflammatory cytokines that leads to atherogenesis. The mechanisms by which the innate immune recognition of these pathogens could lead to atherosclerosis remain unclear. In this study, using human vascular endothelial cells or HEK-293 cells engineered to express pattern-recognition receptors (PRRs), we set out to determine Toll-like receptors (TLRs) and functionally associated PRRs involved in the innate recognition of and response to lipopolysaccharide (LPS) from H. pylori or P. gingivalis. Using siRNA interference or recombinant expression of cooperating PRRs, we show that H. pylori and P. gingivalis LPS-induced cell activation is mediated through TLR2. Human vascular endothelial cell activation was found to be lipid raft-dependent and to require the formation of heterotypic receptor complexes comprising of TLR2, TLR1, CD36 and CD11b/CD18. In addition, we report that LPS from these bacterial strains are able to antagonize TLR4. This antagonistic activity of H. pylori or P. gingivalis LPS, as well as their TLR2 activation capability may be associated with their ability to contribute to atherosclerosis.
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In the annals of cognitive neuroscience there are examples of fantastic memory abilities (e.g., Luria, 1968) that befuddle the vast majority of us with normal mnemonic skills. Although such feats have yet to be demonstrated in other species, extraordinary memory may not be unique to humans. One possible example comes from a study by Inoue and Matsuzawa (2007), which showed that following extensive training, a chimpanzee, Ayumu, displayed superior working memory than human volunteers. Recently, Humphrey (2012) hypothesized that Ayumu outperformed the human participants because he had synaesthesia, a condition in which a stimulus (an inducer) will involuntarily elicit an atypical ancillary experience (a concurrent) (e.g., graphemes eliciting color photisms) (Ward, 2013). Specifically, Humphrey posits that Ayumu spontaneously developed grapheme-colour synaesthesia through “cross-cortical leakage” (p. 354) between the parietal cortex, which may support the storage of overlearned sequences, and adjacent colour-coding regions, during working memory training. Humphrey speculates that the synaesthetic associations elicited colour after-images during training with numerals, and, in turn, facilitated superior performance. Here we challenge this hypothesis and argue that it makes a number of assumptions that are not supported by current research.
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Carbon isotopically based estimates of CO2 levels have been generated from a record of the photosynthetic fractionation of 13C (epsilon p) in a central equatorial Pacific sediment core that spans the last ~255 ka. Contents of 13C in phytoplanktonic biomass were determined by analysis of C37 alkadienones. These compounds are exclusive products of Prymnesiophyte algae which at present grow most abundantly at depths of 70-90 m in the central equatorial Pacific. A record of the isotopic compostion of dissolved CO2 was constructed from isotopic analyses of the planktonic foraminifera Neogloboquadrina dutertrei, which calcifies at 70-90 m in the same region. Values of epsilon p, derived by comparison of the organic and inorganic delta values, were transformed to yield concentrations of dissolved CO2 (c e) based on a new, site-specific calibration of the relationship between epsilon p and c e. The calibration was based on reassessment of existing epsilon p versus c e data, which support a physiologically based model in which epsilon p is inversely related to c e. Values of PCO2, the partial pressure of CO2 that would be in equilibrium with the estimated concentrations of dissolved CO2, were calculated using Henry's law and the temperature determined from the alkenone-unsaturation index UK 37. Uncertainties in these values arise mainly from uncertainties about the appropriateness (particularly over time) of the site-specific relationship between epsilon p and 1/c e. These are discussed in detail and it is concluded that the observed record of epsilon p most probably reflects significant variations in Delta pCO2, the ocean-atmosphere disequilibrium, which appears to have ranged from ~110 µatm during glacial intervals (ocean > atmosphere) to ~60 µatm during interglacials. Fluxes of CO2 to the atmosphere would thus have been significantly larger during glacial intervals. If this were characteristic of large areas of the equatorial Pacific, then greater glacial sinks for the equatorially evaded CO2 must have existed elsewhere. Statistical analysis of air-sea pCO2 differences and other parameters revealed significant (p < 0.01) inverse correlations of Delta pCO2 with sea surface temperature and with the mass accumulation rate of opal. The former suggests response to the strength of upwelling, the latter may indicate either drawdown of CO2 by siliceous phytoplankton or variation of [CO2]/[Si(OH)4] ratios in upwelling waters.
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Oxidized intervals of five organic-rich Madeira Abyssal Plain (MAP) turbidites deposited during the Miocene, Pliocene, and Pleistocene all displayed comparable major loss of total organic carbon (TOC) (84 ± 3.1%) accompanied by a negative isotopic (d13C) shift ranging from -0.3 to -2.9 per mil. Major but significantly lower loss of total nitrogen (Ntot, 61 ± 7.1%) also occurred, leading to a decrease in TOC relative to Ntot (C/Ntot) and a +1.3 to 2.7 per mil Ntot isotopic (d15N) shift. Compound specific isotopic measurements on plant wax n-alkanes indicate the terrestrial organic component in the unoxidized deposits is 13C-enriched owing to significant C4 contribution. Selective preservation of terrestrial relative to marine organic carbon could account for the d13C behavior of TOC upon oxidation but only if a 13C-depleted component of the bulk terrestrial signal is selectively preserved in the process. Although the C/Ntot decrease and positive d15N shift seems inconsistent with selective terrestrial organic preservation, results from analysis of a Modern eolian dust sample collected in the vicinity indicate these observations are compatible. Regardless of the specific explanation for these isotopic observations, however, our findings provide evidence that paleoreconstruction of properties such as pCO2 using the d13C of TOC is a goal fraught with uncertainty whether or not the marine sedimentary record considered is 'contaminated' with significant terrestrial input. Nonetheless, despite major and selective loss of both marine and terrestrial components as a consequence of postdepositional oxidation, intensive organic geochemical proxies such as the alkenone unsaturation index, UK'37, appear resistant to change and thereby retain their paleoceanographic promise.
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Six samples from Sites 1219 and 1221 ranging in age from early Eocene to early Oligocene were analyzed for freely extractable lipids to determine whether the low organic carbon (Corg) sediments of the Eocene equatorial Pacific (Corg content typically 0.03%) are appropriate for biomarker studies. Only one sample from the Oligocene equatorial Pacific (Sample 199-1219A-13H-3, 50-54 cm) contained any biomarkers of interest to paleoceanography. The only lipids identified in the remaining samples appear to be contaminants from drilling or subsequent handling. Sample 199-1219A-13H-3, 50-54 cm, contained alkenone biomarkers specific to haptophyte algae that are used for estimating past mean annual sea-surface temperature (maSST). If the Holocene calibration of maSST is appropriate for the Oligocene, the estimated equatorial temperature is >=28.3°C, or at least 3°C warmer than modern equatorial maSST at a similar longitude.
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Assessment of changes in surface ocean conditions, in particular, sea-surface temperature (SST), is essential to understand long-term changes in climate especially in regions where continental climate is strongly influenced by oceanographic processes. To evaluate changes in SST in the northeast Pacific, we have analyzed long-chain alkenones of prymnesiophyte origin at 38 depths in a piston and associated trigger core collected beneath the contemporary core of the California Current System at 42°N, ~270 km off the coast of Oregon/California. The samples span 30,000 years of deposition at this location. Unsaturation patterns (UK'37) in the alkenone series display a statistically significant difference (p <<0.001) between interglacial (0.44 ± 0.02, n = 11) and glacial (0.29 ± 0.04, n = 20) intervals of the cores. Detailed examination of other compositional features of the C37, C38, C39 alkenone series and a related C36 alkenoate series measured downcore suggests the published UK'37 - temperature calibration (UK'37 = 0.034 * T + 0.039 ) , defined for cultures of a strain of Emiliania huxleyi isolated from the subarctic Pacific, provides best estimates of winter SST at our study site. This inference is purely statistical and does not imply, however, that the phytoplankton source of these biomarkers is most productive in winter or at the ocean surface. The temperature record for UK'37 implies (1) an ~4°C shift occurred in winter SST from ~7.5 ± 1.1°C at the last glacial maximum to ~11.7 ± 0.7°C in the present interglacial period, and (2) this warming trend was confined to the time frame 14-10 Ka within the glacial to interglacial transition period. These conclusions are corroborated entirely by results from an independent SST transformation of radiolarian species assemblage data obtained from the same core materials.