160,722 research outputs found
Climate sensitivity to the carbon cycle modulated by past and future changes in ocean chemistry
No full textThe carbon cycle has a central role in climate change. For example, during glacial-interglacial cycles, atmospheric carbon dioxide has altered radiative forcing and amplified temperature changes. However, it is unclear how sensitive the climate system has been to changes in carbon cycling in previous geological periods, or how this sensitivity may evolve in the future, following massive anthropogenic emissions. Here we develop an analytical relationship that links the variation of radiative forcing from changes in carbon dioxide concentrations with changes in air-sea carbon cycling on a millennial timescale. We find that this relationship is affected by the ocean storage of carbon and its chemical partitioning in sea water. Our analysis reveals that the radiative forcing of climate is more sensitive to carbon perturbations now than it has been over much of the preceding 400 million years. This high sensitivity is likely to persist into the future as the oceans become more acidic and the bulk of the fossil-fuels inventory is tansferred to the ocean and atmosphere
Analytical relationships between atmospheric carbon dioxide, carbon emissions, and ocean processes
No full textCarbon perturbations leading to an increase in atmospheric CO2 are partly offset by the carbon uptake by the oceans and the rest of the climate system. Atmospheric CO2 approaches a new equilibrium state, reached after ocean invasion ceases after typically 1000 years, given by P CO2 = P 0exp(dI ? /I B ), where P 0 and P CO2 are the initial and final partial pressures of atmospheric CO2, dI ? is a CO2 perturbation, and I B is the buffered carbon inventory of the air-sea system. The perturbation, dI ? , includes carbon emissions and changes in the terrestrial reservoir, as well as ocean changes in the surface carbon disequilibrium and fallout of organic soft tissue material. Changes in marine calcium carbonate, dI CaCO3, lead to a more complex relationship with atmospheric CO2, where P CO2 is changed by the ratio P CO2 = P 0{I O(A - C)/(I O(A - C) - dI CaCO3)} and then modified by a similar exponential relationship, where I O(A - C) is the difference between the inventories of titration alkalinity and dissolved inorganic carbon. The overall atmospheric P CO2 response to a range of perturbations is sensitive to their nonlinear interactions, depending on the product of the separate amplification factors for each perturbation
Ocean-atmosphere partitioning of anthropogenic carbon dioxide on centennial timescales
No full textA theory for the ocean-atmosphere partitioning of anthropogenic carbon dioxide on centennial timescales is presented. The partial pressure of atmospheric CO2 (PCO2) is related to the external CO2 input (??C) at air-sea equilibrium by: PCO2 = 280 ppm exp(??C/[IA + IO/R]), where IA, IO, and R are the pre-industrial values of the atmospheric CO2 inventory, the oceanic dissolved inorganic carbon inventory, and the Revelle buffer factor of seawater, respectively. This analytical expression is tested with two- and three-box ocean models, as well as for a version of the Massachusetts Institute of Technology general circulation model (MIT GCM) with a constant circulation field, and found to be valid by at least 10% accuracy for emissions lower than 4500 GtC. This relationship provides the stable level that PCO2 reaches for a given emission size, until atmospheric carbon is reduced on weathering timescales. On the basis of the MIT GCM, future carbon emissions must be restricted to a total of 700 GtC to achieve PCO2 stabilization at present-day transient levels
Study of Disaster Probability when Strength Follows Power Function Distribution and Stress Follows Odd Generalised Exponential Gompertz Distribution(OGE-G)
No full textIn this article, the probability of disaster is studied when the strength of the items follows power function distribution and the stress of the manufactured items/devices follows OGE-G distribution. In order to study the probability of disaster, a relationship between the parameters of OGE-G and power function distribution is established through the reliability measure P = Pr(Y \u3e X). Finally, through the relationship among the parameters involved in the model is used to get the optimum cost function when the cost function is linear in terms of parameters
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
The Impact Of The Development Of ICT In Several Hungarian Economic Sectors
No full textAs the author could not find a reassuring mathematical and
statistical method in the literature for studying the effect of
information communication technology on enterprises, the author
suggested a new research and analysis method that he also used to study the Hungarian economic sectors. The question of what
factors have an effect on their net income is vital for enterprises. At first, the author studied some potential indicators related to economic sectors, then those indicators were compared to the net income of the surveyed enterprises. The resulting data showed that the growing penetration of electronic marketplaces contributed to the change of the net income of enterprises to the greatest extent.
Furthermore, among all the potential indicators, it was the only indicator directly influencing the net income of enterprises.
With the help of the compound indicator and the financial data
of the studied economic sectors, the author made an attempt to find a connection between the development level of ICT and
profitability. Profitability and productivity are influenced by a lot of other factors as well. As the effect of the other factors could not be measured, the results – shown in a coordinate system - are not full but informative.
The highest increment of specific Gross Value Added was
produced by the fields of ‘Manufacturing’, ‘Electricity, gas and water supply’, ‘Transport, storage and communication’ and
‘Financial intermediation’. With the exception of ‘Electricity, gas and water supply’, the other economic sectors belong to the group of underdeveloped branches (below 50 percent).
On the other hand, ‘Construction’, ‘Health and social work’ and
‘Hotels and restaurants’ can be seen as laggards, so they got into the lower left part of the coordinate system.
‘Agriculture, hunting and forestry’ can also be classified as a
laggard economic sector, but as the effect of the compound
indicator on the increment of Gross Value Added was less
significant, it can be found in the upper left part of the coordinate system. Drawing a trend line on the points, it can be made clear that it shows a positive gradient, that is, the higher the usage of ICT devices, the higher improvement can be detected in the specific Gross Value Added
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
On the roles of cell size and trophic strategy in North Atlantic diatom and dinoflagellate communities
No full textWe have examined the inter- and intra-group seasonal succession of 113 diatom and dinoflagellate taxa, as
surveyed by the Continuous Plankton Recorder (CPR) in the North Atlantic, by grouping taxa according to two
key functional traits: cell size (mg C cell21) and trophic strategy (photoautotrophy, mixotrophy, or heterotrophy).
Mixotrophic dinoflagellates follow photoautotrophic diatoms but precede their obligate heterotrophic
counterparts in the succession because of the relative advantages afforded by photosynthesizing when light and
nutrients are available in spring. The mean cell size of the sampled diatoms is smallest in the summer, likely
because of the higher specific nutrient affinity of smaller relative to larger cells. Contrastingly, we hypothesize that
mixotrophy diminishes the size selection based on nutrient limitation and accounts for the lack of a seasonal size
shift among surveyed dinoflagellates. Relatively small, heterotrophic dinoflagellates (mg C cell21 , 1023) peak
after other, larger dinoflagellates, in part because of the increased abundance of their small prey during nutrientdeplete
summer months. The largest surveyed diatoms (mg C cell21 . 1022) bloom later than others, and we
hypothesize that this may be because of their relatively slow maximum potential growth rates and high internal
nutrient storage, as well as to the slower predation of these larger cells. The new trait database and analysis
presented here helps translate the taxonomic information of the CPR survey into metrics that can be directly
compared with trait-based models
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
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