399 research outputs found

    Thermal Conductivity and Specific Heat of the Spin-Ice Compound Dy2_2Ti2_2O7_7: Experimental Evidence for Monopole Heat Transport

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    Elementary excitations in the spin-ice compound Dy2_2Ti2_2O7_7 can be described as magnetic monopoles propagating independently within the pyrochlore lattice formed by magnetic Dy ions. We studied the magnetic-field dependence of the thermal conductivity {\kappa}(B) for B || [001] and observe clear evidence for magnetic heat transport originating from the monopole excitations. The magnetic contribution {\kappa}_{mag} is strongly field-dependent and correlates with the magnetization M(B). The diffusion coefficient obtained from the ratio of {\kappa}_{mag} and the magnetic specific heat is strongly enhanced below 1 K indicating a high mobility of the monopole excitations in the spin-ice state.Comment: 5 pages, 4 figure

    Importance of maintained atrio-ventricular synchrony in patients with pacemarkers

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    The effect of atrial contraction on cardiac function is reviewed in patients with dual chamber and rate-responsive ventricular pacemakers. The question posed was is there any haemodynamic, clinical or prognostic advantage of AV synchrony in dual chamber pacemakers in comparison to rate-responsive ventricular pacemakers? Optimal A V delay in dual chamber pacing favours cardiac performance at rest, while during exercise the increase in heart rate rather than A V synchrony influences cardiac performance and working capacity. However, there is little information on the benefit of maintained A V synchrony in patients' daily activities. Patients with pacemakers which maintain AV synchrony seem to have less morbidity and mortality than patients with ventricular stimulation alone, and there are comparable rates of complication in carriers of single and dual chamber pacemakers, the former showing problems with the pacemaker syndrome and the latter with atrial sensing and pacemaker-induced tachycardias. The disadvantage of dual chamber pacemakers are higher costs and time-consuming control

    Transitional criminal justice after German Unification and its international impact

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    Magister Legum - LLMSouth Afric

    “Machiavelli of Peace”: Dag Hammarskjöld and the political role of the Secretary-General of the United Nations

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    The thesis analyses Dag Hammarskjöld’s political role as UN Secretary-General and the efforts he made to justify such a role. It is the first attempt to give a comprehensive account of the political role Hammarskjöld played from “both sides”, based on the now available sources from both national and UN archives. The thesis also deals with the problems of a political role for the UN Secretary-General. The conventional picture of Hammarskjöld as a “neutral and impartial” international civil servant is challenged and the figure that emerges is the one of an astute politician – a ”Machiavelli of Peace”. As a civil servant in Sweden, Hammarskjöld played a political role although he viewed himself as an expert and civil servant and not a politician. He argued that he could play a political role based on ”neutrality and impartiality” and he transferred this concept to the international arena as Secretary-General. Hammarskjöld managed to play an important political role because he offered a solution to the American dilemma of how to deal with the Cold War in the ThirdWorld without choosing between their Western European allies and the newly independent countries. This at the precise time when the Americans were losing control of the General Assembly due to the influx of newly independent countries that put decolonisation on the agenda. In the Congo Crisis the political role of the Secretary-General reached its zenith during the initial period where Hammarskjöld played an interventionist role. Hammarskjöld’s policies were based on clearly defined Cold War objectives – shared by the Western permanent members of the Security Council – and on a wish to enlarge the political role of the Secretary-General. The weak base for Hammarskjöld’s political role forced him to radically change his policies in the Congo to shore up his position when he was criticised for his interventionist policies

    Influence of coronary artery bypass grafting on ventricular late potentials as a predictive factor for ventricular arrhythmias during short- and long-term follow-up

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    Ventricular late potentials have been identified as a prognostic factor in the prediction of ventricular arrhythmias in patients after myocardial infarction. In this prospective study the possible impact of late potentials on the prediction of ventricular arrhythmias in the short- and long-term follow-up after coronary artery bypass grafting was evaluated. In 188 patients (165 men, 23 women, age 57 ±8 years) with chronic coronary heart disease 48 (26%) had late potentials before bypass grafting; after the procedure this was reduced to 39 (21%) (ns). In 16 (33%) of the 48 patients with late potentials before bypass grafting, late potentials were no longer present in the short-term follow-up (9 ±6 days). Conversely, seven (5%) of the 140 patients without late potentials before bypass grafting had late potentials in the short-term follow-up after grafting. Nine (19%) of the 48 patients with late potentials before bypass grafting had ventricular arrhythmias in the peri-operative phase, which had to be treated with antiarrhythmic agents. In contrast, only three (2%>) of the 140 patients without late potentials before bypass grafting had to be treated for ventricular arrhythmias (P<0.001). In the long-term follow-up of 29 ± 3 months, there were no events in the group of 149 patients without late potentials after grafting. In the 39 patients with late potentials after grafting, there were two (5%) events (two patients with arrhythmic syncope). Conclusions (1) Patients with late potentials before bypass grafting have a markedly higher risk of developing serious ventricular arrhythmias in the peri-operative period than patients without late potentials. (2) Patients without late potentials have a very low risk of developing serious ventricular arrhythmias in the peri-operative period. (3) During long-term follow-up there was only a low probability of developing symptomatic ventricular arrhythmias in patients with or without late potential

    Site-specific management units in a commercial maize plot delineated using very high resolution remote sensing and soil properties mapping

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    14 Pags. The definitive version, with tabls. and figs., is available at: http://www.sciencedirect.com/science/journal/01681699The joint use of satellite imagery and digital soil maps derived from soil sampling is investigated in the present paper with the goal of proposing site-specific management units (SSMU) within a commercial field plot. Very high resolution Quickbird imagery has been used to derive leaf area index (LAI) maps in maize canopies in two different years. Soil properties maps were obtained from the interpolation of ion concentrations (Na, Mg, Ca, K and P) and texture determined in soil samples and also from automatic readings of electromagnetic induction (EMI) readings taken with a mobile sensor. Links between the image-derived LAI and soil properties were established, making it possible to differentiate units within fields subject to abiotic stress associated with soil sodicity, a small water-holding capacity or flooding constraints. In accordance with the previous findings, the delineation of SSMUs is proposed, describing those field areas susceptible of variable-rate management for agricultural inputs such as water or fertilizing, or soil limitation correctors such as gypsum application in the case of sodicity problems. This demonstrates the suitability of spatial information technologies such as remote sensing and digital soil mapping in the context of precision agriculture.The Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) funded the PhD grant of the first author. This work is a result of the project RTA2005-00230, funded by INIA. The contribution of the project AGL2009-08931/AGR is also recognized.Peer reviewe

    Big Data Analytics für die Produktentwicklung

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    Aus der Einleitung: "Auf der Hannovermesse 2011 wurde zum ersten Mal der Begriff "Industrie 4.0" der Öffentlichkeit bekannt gemacht. Die Akademie der Technikwissenschaften hat in einer Arbeitsgruppe diese Grundidee der vierten Revolution der Industrieproduktion weiterbearbeitet und 2013 in einem Abschlussbericht mit dem Titel „Umsetzungsempfehlungen für das Zukunftsprojekt Industrie 4.0“ veröffentlicht (BmBF, 2013). Die Grundidee besteht darin, wandlungsfähige und effiziente Fabriken unter Nutzung moderner Informationstechnologie zu entwickeln. Basistechnologien für die Umsetzung der intelligenten Fabriken sind: — Cyber-Physical Systems (CPS) — Internet of Things (IoT) und Internet of Services (IoS) — Big Data Analytics and Prediction — Social Media — Mobile Computing Der Abschlussbericht fokussiert den Wertschöpfungsschritt der Produktion, während die Fragen der Produktentwicklung weitgehend unberücksichtigt geblieben sind. Die intelligente Fabrik zur Herstellung intelligenter Produkte setzt aber auch die Weiterentwicklung der Produktentwicklungsmethoden voraus. Auch hier gibt es einen großen Handlungsbedarf, der sehr stark mit den Methoden des „Modellbasierten Systems-Engineering“ einhergeht. ...

    НАДЕЖНОСТЬ КОНВЕЙРНОГО ТРАНСПОРТА

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    Досліджено питання комплексної надійності функціонування конвеєрних ліній при відкритій розробці корисних копалин. Наведено статистичні закони розподілу для напрацювання на відмову і термінів служби роликових опор для конвеєрних ліній. Побудовано діаграму причин і результатів для системати- зації причин простоїв конвейєрних ліній з переміщення гірської маси в кар'єрах. Исследован вопрос комплексной надежности функционирования конвейерных линий при открытой разра- ботке полезных ископаемых. Приведены статистические законы распределения для наработки на отказ и сроков службы роликовых опор для конвейерных линий. Построена диаграмма причин и результатов для систематизации причин простоев конвейерных линий по перемещению горной массы в карьерах

    Proinflammatory cytokines in acute myocardial infarction with and without cardiogenic shock

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    Background: Inflammatory response is an important feature of acute coronary syndromes and myocardial infarction (MI). The prognostic value of proinflammatory cytokines in patients with acute MI complicated by cardiogenic shock is unknown. Methods and results: In 41 patients admitted with acute MI (age 60 ± 11 years, six females, 19 Killip class IV) serial plasma concentration of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 receptor antagonist (IL-1Ra) were measured. Seven patients with cardiogenic shock (CS) developed a systemic inflammatory response syndrome (SIRS). Patients with CS—particularly those who developed SIRS—showed significantly higher cytokine levels than patients with uncomplicated MI. In patients with CS and SIRS peak levels of IL-1Ra were 223,973 pg/ml, IL-6 252.8 pg/ml and TNF-α 7.0 pg/ml. In CS without SIRS IL-1Ra levels were 19,988 pg/ml, IL-6 109.3 pg/ml and TNF-α 3.8 pg/ml. In uncomplicated MI peak IL-1Ra levels were 1,088 pg/ml, IL-6 34.1 pg/ml and TNF-α 2.6 pg/ml. Conclusions: The inflammation-associated cytokines TNF-α, IL-6 and IL-1Ra are significantly elevated in patients with MI complicated by CS when compared to patients with uncomplicated MI. Among shock-patients IL-1Ra levels are promising diagnostic markers for early identification of patients developing SIRS, heralding a poor outcom

    Multilayered lipid membrane stacks for biocatalysis using membrane enzymes

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    Multilayered or stacked lipid membranes are a common principle in biology and have various functional advantages compared to single lipid membranes, such as their ability to spatially organize processes, compartmentalize molecules and greatly increase surface area and hence membrane protein concentration. Here we report on a supramolecular assembly of a multilayered lipid membrane system in which poly-L-lysine electrostatically links negatively charged lipid membranes. When suitable membrane enzymes are incorporated, either an ubiquinol oxidase (cytochrome bo3 from Escherichia coli) or an oxygen tolerant hydrogenase (the membrane-bound hydrogenase from Ralstonia eutropha), cyclic voltammetry (CV) reveals a linear increase in biocatalytic activity with each additional membrane layer. Electron transfer between the enzymes and the electrode is mediated by the quinone pool that is present in the lipid phase. We deduce by atomic force microscopy, CV and fluorescence microscopy that quinones are able to diffuse between the stacked lipid membrane layers via defect sites where the lipid membranes are interconnected. This assembly is akin to that of interconnected thylakoid membranes or the folded lamella of mitochondria and have significant potential for mimicry in biotechnology applications such as energy production or biosensing
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