102,053 research outputs found
Fluxes of nutrients in a three-dimensional meander structure of the Antarctic Polar Front
No full textThe horizontal and vertical advection and the vertical diffusion of two plant nutrients (nitrate and silicate) are estimated at the Antarctic Polar Front (APF) in the Atlantic sector using quasi-synoptic, high-resolution physical and chemical measurements. Our results suggest that the routes of nutrient supply are more complex than indicated by existing large-scale views. The vertical advection associated with mesoscale upwelling events is shown to be between two and three orders of magnitude larger than the diffusion, and to potentially amount to the phytoplankton uptake rate locally. Averaged over the survey area, however, the vertical nutrient transport is downward and concords with the front acting as a barrier to the northward export of surface nutrients by the Ekman drift. This poses significant constraints on the global cycles of nutrients and may have an impact in the sediment record
Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard
No full textPhytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSFW); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes
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
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
Summary Report of The First International Competition on Computational Models of Argumentation
No full textComputational models of argumentation are an active research discipline within Artificial Intelligence that has grown since the beginning of the 1990s (Dung 1995).
While still a young field when compared to areas such as SAT solving and Logic Programming, the argumentation community is very active, with a conference series (COMMA, which began in 2006) and a variety of workshops and special issues of journals. Argumentation has also worked its way into a variety of applications. For example, Williams et al. (2015) described how argumentation techniques are used for recommending cancer treatments, while Toniolo et
al. (2015) detail how argumentation-based techniques can support critical thinking and collaborative scientific inquiry or intelligence analysis.
Many of the problems that argumentation deals with are computationally difficult, and applications utilising argumentation therefore require efficient solvers. To encourage this line of research, we organised the First International
Competition on Computational Models of Argumentation (ICCMA), with the intention of assessing and promoting state of the art solvers for abstract argumentation problems, and to identify families of challenging benchmarks for
such solvers.
The objective of ICCMA’15 is to allow researchers to compare the performance of different solvers systematically on common benchmarks and rules. Moreover, as witnessed by competitions in other AI disciplines such as planning and SAT solving, we see ICCMA as a new pillar of the community which provides information and insights on the current state of the art, and highlights future
challenges and developments.
This article summarises the first ICCMA held in 2015 (ICCMA’15). In this competition, solvers were invited to address standard decision and enumeration problems of abstract argumentation frameworks (Dunne and Wooldridge 2009).
Solvers’ performance is evaluated based on their time taken to provide a correct solution for a problem; incorrect results were discarded. More information about the competition, including complete results and benchmarks, can be found on the ICCMA website
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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
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
Significance of the Polar Frontal Zone for large-sized diatoms and new production during summer in the Atlantic sector of the Southern Ocean
No full textThe chlorophyll a (chl a) biomass and primary production of three phytoplankton size fractions were estimated in the Atlantic sector of the Southern Ocean from 12 December 1995 to 20 January 1996. Elevated concentrations of chl a, primary production, and contribution of microplankton (>20 ?m) coincided with dominance by large or long-chained diatoms (Thalassiothrix spp., Pseudonitzschia lineola, and Chaetoceros spp.) in the Polar Frontal Zone (PFZ, 49.5°S–52°S). Vertically resolved assimilation numbers (i.e. primary production normalized to chl a) and intrinsic growth rates of microplankton were much lower at high-biomass stations of the Northern Polar Frontal Zone (NPFZ) than in adjacent waters. Silicic acid appeared to be the proximal factor limiting the growth and yield of resident diatoms in the NPFZ. A carbon budget showed that, during the sampling period, diatom dominance at high-biomass sites was associated with near-steady-state conditions. This system exhibited a low POC sinking flux relative to total primary production, despite strong dominance by microplankton. South of 52°S, total chl a and primary production were generally low, but increased sharply in a mixed Phaeocystis-diatom bloom that extended from 61°S to 65°S in the Seasonal Ice Zone (SIZ). We estimated that the PFZ contributes from 37% to 67% of the total open-water new production in the Southern Ocean near the Greenwich meridian, depending on whether blooms occur or not in the SIZ.<br/
G-Rank: Unsupervised Continuous Learn-to-Rank for Edge Devices in a P2P Network
No full textRanking algorithms in traditional search engines are powered by enormous training data sets that are meticulously engineered and curated by a centralized entity. Decentralized peer-to-peer (p2p) networks such as torrenting applications and Web3 protocols deliberately eschew centralized databases and computational architectures when designing services and features. As such, robust search-and-rank algorithms designed for such domains must be engineered specifically for decentralized networks, and must be lightweight enough to operate on consumer-grade personal devices such as a smartphone or laptop computer. We introduce G-Rank, an unsupervised ranking algorithm designed exclusively for decentralized networks. We demonstrate that accurate, relevant ranking results can be achieved in fully decentralized networks without any centralized data aggregation, feature engineering, or model training. Furthermore, we show that such results are obtainable with minimal data preprocessing and computational overhead, and can still return highly relevant results even when a user’s device is disconnected from the network. G-Rank is highly modular in design, is not limited to categorical data, and can be implemented in a variety of domains with minimal modification. The results herein show that unsupervised ranking models designed for decentralized p2p networks are not only viable, but worthy of further research.https://github.com/awrgold/G-RankComputer Scienc
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