927 research outputs found

    Extending the theory of Owicki and Gries with a logic of progress

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    This paper describes a logic of progress for concurrent programs. The logic is based on that of UNITY, molded to fit a sequential programming model. Integration of the two is achieved by using auxiliary variables in a systematic way that incorporates program counters into the program text. The rules for progress in UNITY are then modified to suit this new system. This modification is however subtle enough to allow the theory of Owicki and Gries to be used without change

    Which mathematics for the Information Society?

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    MathIS is a new project that aims to reinvigorate secondary- school mathematics by exploiting insights of the dynamics of algorithmic problem solving. This paper describes the main ideas that underpin the project. In summary, we propose a central role for formal logic, the development of a calculational style of reasoning, the emphasis on the algorithmic nature of mathematics, and the promotion of self-discovery by the students. These ideas are discussed and the case is made, through a number of examples that show the teaching style that we want to introduce, for their relevance in shaping mathematics training for the years to come. In our opinion, the education of software engineers that work effectively with formal methods and mathematical abstractions should start before university and would benefit from the ideas discussed here.Long-term collaboration with J. N. Oliveira on calculational approaches to mathematics is deeply acknowledged. We are also grateful to the anonymous referees for their valuable comments. This research was supported by FCT (the Portuguese Foundation for Science and Technology), in the context of the MATHIS Project under contract PTDC/EIA/73252/2006. The work of Joao F. Ferreira and AlexandraMendeswas further supported by FCT grants SFRH/BD/24269/2005 and SFRH/BD/29553/2006, respectively

    How political are national identities? A comparison of the United States, the United Kingdom, and Germany in the 2010s

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    This is the final version of the article. Available from SAGE Publications via the DOI in this record.Original data supporting this research are available from the UK Data Archive (Study Number 851142): http://dx.doi.org/10.5255/UKDA-SN-851142/Research demonstrates the multi-dimensional nature of American identity arguing that the normative content of American identity relates to political ideologies in the United States, but the sense of belonging to the nation does not. This paper replicates that analysis and extends it to the German and British cases. Exploratory structural equation modeling attests to cross-cultural validity of measures of the sense of belonging and norms of uncritical loyalty and engagement for positive change. In the 2010s, we find partisanship and ideology in all three nations explains levels of belonging and the two content dimensions. Interestingly, those identifying with major parties of the left and right in all three countries have a higher sense of belonging and uncritical loyalty than their moderate counterparts. The relationship between partisanship, ideology, and national identity seems to wax and wane over time, presumably because elite political discourse linking party or ideology to identity varies from one political moment to the next.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Data collection was funded by a grant from the Economic and Social Research Council of the United Kingdom (RES-061-25-0405)

    RÀumliche Modellierung von KohlenstoffvorrÀten in Westgrönland

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    Die obersten 300 cm arktischer Böden beinhalten ca. 50 % des weltweit in Böden gespeicherten organischen Kohlenstoffs (Corg). Aufgrund von Datenmangel und einem lĂŒckenhaften Erkenntnisstand weisen Berechnungen des Kohlenstoffvorrats (Cstock) hohe Unsicherheiten auf. Die Höhe des Cstock ist abhĂ€ngig von zahlreichen bodenbildenden Faktoren, die rĂ€umlich und skalenabhĂ€ngig variieren. In Grönland fĂŒhren regionale Klima- sowie wechselnde Umweltbedingungen zu rĂ€umlich variierenden Cstocks. Schwerpunkt dieser Arbeit ist eine flĂ€chendeckende Modellierung des Corg-Gehalts, basierend auf den Prinzipien der Boden-Landschafts-Modellierung, kombiniert mit Verfahren des Maschinellen Lernens (u.a. Random Forest, RF). Die Ziele sind (i) die Identifikation relevanter Umwelteigenschaften im Hinblick auf die rĂ€umliche Verteilung des Corg, (ii) die Erzeugung hochaufgelöster Bodeneigenschaftskarten sowie (iii) die Berechnung des Cstock fĂŒr zwei Untersuchungsgebiete in Westgrönland. Das erste Gebiet befindet sich nahe Kangerlussuaq am Rande des Inlandeises, das zweite in KĂŒstennĂ€he bei Sisimiut. Beide Untersuchungsgebiete haben eine GrĂ¶ĂŸe von 2 kmÂČ, sind reprĂ€sentativ fĂŒr die jeweilige Region und weisen vergleichbare Umwelteigenschaften auf. Bodenproben (Corg, Lagerungsdichte) wurden in vier Tiefenstufen (0-25, 25-50, 50-100, 100-200 cm) an 40 Standorten pro Untersuchungsgebiet entnommen. Die Datengrundlage fĂŒr die Modellierung umfasst neben Bodendaten zahlreiche Reliefparameter sowie Fernerkundungsdaten. Erste Ergebnisse liegen fĂŒr die Berechnung des Cstocks der obersten 25 cm mit RF (RÂČ/RMSE) fĂŒr beide Untersuchungsgebiete vor. Der mittlere Cstock des Gebiets nahe Kangerlussuaq betrĂ€gt 7,56 kg/mÂČ. Aus dem Model mit RF (0,62/1,22) gehen Exposition und Bodenfeuchte als einflussreichste Umweltfaktoren hervor. Nahe Sisimiut belĂ€uft sich der durchschnittliche Cstock auf 12.12 kg/mÂČ. Nach dem RF Model (0,65/6,24) besteht ein Zusammenhang zwischen GelĂ€ndehöhe, Exposition, Vegetation und Cstock

    Synthesis of RuO 2 nanowires from Ru thin films by atmospheric pressure micro-post-discharge

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    International audienceOxidation by a micro-post-discharge at atmospheric pressure of thin films of ruthenium deposited on fused silica by pressure-modulated magnetron sputtering is studied. Single-crystalline RuO 2 nanowires are obtained for the first time with a diffusion process over large areas. Nanowires grow typically at temperatures below 550-600 K, provided the level of stress is high enough to fragment grains in sub-grains with sizes between 30 and 50 nm. Because of the alternation of dense and porous layers forming the coating, inward diffusion of vacancies leads to no patent Kirkendall's effect, pores being distributed over the whole coating thickness and not mainly at the interface with the substrate. The centre of the treatment being heated at temperatures higher than 900 K, gaseous RuO 4 is formed, leading to an evaporated area. At its edge, a ring of microcrystals is formed, likely by a CVD mechanism

    Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar-O 2 Afterglow: Application to Nanoparticles Synthesis

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    International audienceThe interaction of (3-Aminopropyl)triethoxysilane (APTES) with pulsed late Ar-O 2 afterglow is characterized by the synthesis of OH, CO and CO 2 in the gas phase as main by-products. Other minor species like CH, CN and C 2 H are also produced. We suggest that OH radicals are produced in a first step by dehydrogenation of APTES after interaction with oxygen atoms. In a second step, the molecule is oxidized by any O 2 state, to form peroxides that transform into by-products, break thus the precursor CC bonds. If oxidation is limited, i.e. a low duty cycle, fragmentation of the precursor is limited and produced nanoparticles keep the backbone structure of the precursor, but contain amide groups produced from the amine groups initially available in APTES. At high duty cycle, silicon-containing fragments contain some carbon and react together and produce nanoparticles with a non-silica-like structure

    Effect of Intraduodenal Bile and Na-Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Secretin, Pancreatic Polypeptide, and Gastrin in Man

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    The effect of intraduodenally administered cattle bile (CB) and Na-taurodeoxycholate (TDC) on basal pancreatic secretion and plasma levels of secretin, pancreatic polypeptide (PP), and gastrin were investigated on two separate days in 10 fasting volunteers. Doses of 2-6 g CB and 20&600 mg TDC were given intraduodenally at 65-min intervals. Volume, bicarbonate, lipase, trypsin, amylase, and bilirubin were measured in 10-min fractions of duodenal juice, and GI peptides determined by radioimmunoassay. CB and TDC enhanced significantly and dose-dependently volume, bicarbonate and enzyme secretion, and plasma secretin and PP levels. In contrast, plasma gastrin showed only a marginal increase. We conclude that the hydrokinetic effect of intraduodenal CB and TDC is at least partially mediated by secretin. Gastrin could be ruled out as a mediator of the ecbolic effect, whereas other GI peptides, primarily CCK, and/or neural mechanisms must be considered possible mediators. Both pathways may also play a role in the PP release

    A new measure of the ‘democratic peace’: what country feeling thermometer data can teach us about the drivers of American and Western European foreign policy

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    This is the final version. Available on open access from Taylor & Francis via the DOI in this recordReplication data is available on the first authors' Harvard dataverse page.While the existence of a ‘Democratic Peace’ (DP) is widely accepted, the various DP theories that seek to explain why democracies rarely fight one another are highly contested. A ‘commercial/capitalist peace’ counterargument maintains that the relationship between democratic politics and peace is spurious: the actual driver is greater trade among democracies. Meanwhile, Realists counter that it is alliances among democratic states, not their democratic nature, that causes peace among them. This research note utilizes novel country feeling thermometer data to explore the debate’s micro-foundations: the underlying drivers of international amity and enmity among democratic citizens in the US, UK, France, and Germany. Utilizing Freedom House and other quantitative measures of freedom, trade, military strength, and racial and cultural difference, it pits the micro-foundations of the DP against its rivals to explain attitude formation among a group of Western democratic publics. Given the resurgence of authoritarianism around the world today, a better understanding of the role of regime type in shaping public opinion – and subsequently war and peace – is urgently needed
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