Glass transition and layering effects in confined water: a computer simulation study

Single particle dynamics of water confined in a nanopore is studied through Computer Molecular Dynamics. The pore is modeled to represent the average properties of a pore of Vycor glass. Dynamics is analyzed at different hydration levels and upon supercooling. At all hydration levels and all temperatures investigated a layering effect is observed due to the strong hydrophilicity of the substrate. The time density correlators show, already at ambient temperature, strong deviations from the Debye and the stretched exponential behavior. Both on decreasing hydration level and upon supercooling we find features that can be related to the cage effect typical of a supercooled liquid undergoing a kinetic glass transition. Nonetheless the behavior predicted by Mode Coupling Theory can be observed only by carrying out a proper shell analysis of the density correlators. Water molecules within the first two layers from the substrate are in a glassy state already at ambient temperature (bound water). The remaining subset of molecules (free water) undergoes a kinetic glass transition; the relaxation of the density correlators agree with the main predictions of the theory. From our data we can predict the temperature of structural arrest of free water.Comment: 14 pages, 15 figures inserted in the text, to be published in J. Chem. Phys. (2000

Cross-lingual Entity Alignment via Joint Attribute-Preserving Embedding

Entity alignment is the task of finding entities in two knowledge bases (KBs) that represent the same real-world object. When facing KBs in different natural languages, conventional cross-lingual entity alignment methods rely on machine translation to eliminate the language barriers. These approaches often suffer from the uneven quality of translations between languages. While recent embedding-based techniques encode entities and relationships in KBs and do not need machine translation for cross-lingual entity alignment, a significant number of attributes remain largely unexplored. In this paper, we propose a joint attribute-preserving embedding model for cross-lingual entity alignment. It jointly embeds the structures of two KBs into a unified vector space and further refines it by leveraging attribute correlations in the KBs. Our experimental results on real-world datasets show that this approach significantly outperforms the state-of-the-art embedding approaches for cross-lingual entity alignment and could be complemented with methods based on machine translation

A reminder of the road not taken: Hans-Dietrich Genscher and the holy grail of a united Europe

The state funeral of Hans-Dietrich Genscher, West Germany’s longest serving foreign minister and vice-chancellor, was held on 17 April. Kristina Spohr writes on Genscher’s career, his role in unifying Germany, and his ultimate aspiration to integrate both NATO and the Warsaw Pact into an all-European security order that incorporated the Soviet Union

Take care! Aber bitte gegen Bezahlung

Rezension zu: Ute Gerhard, Trudie Knijn, Anja Weckwert (Hrsg.) : Erwerbstätige Mütter – Ein europäischer Vergleich ; Verlag Beck, Becksche Reihe 1514, München 2003, ISBN 3-406-49433-1, 256 Seiten, 14,90 Euro

Der neue Menschenrechtsrat und das Hochkommissariat für Menschenrechte der Vereinten Nationen: Entstehung, Entwicklung und Zusammenarbeit

Maximilian Spohr beschäftigt sich mit der Entstehung, Entwicklung und Zusammenarbeit des Menschenrechtsrats und des Hochkommissariats für Menschenrechte der Vereinten Nationen. Anlässlich der Gründung des neuen Menschenrechtsrates im Jahr 2006 geht er der Frage nach, wie sich die Zusammenarbeit zwischen dem zentralen intergouvernementalen Menschenrechtsorgan der Organisation und dem Hochkommissariat verändert hat. Der Autor bewertet die Reform dabei überwiegend kritisch. So sei vor allem im Zuge der institutionellen Aufwertung des neuen Menschenrechtsrates die Unabhängigkeit des Hochkommissariats verstärkt in Frage gestellt worden. Begünstigt durch arbeitsorganisatorische Probleme am Hochkommissariat, sei es in Reaktion hierauf zu einer Abgrenzung des auf dem Mandat des Hochkommissars beruhenden Tätigkeitsbereichs gekommen. Somit sei heute insbesondere der wichtige Bereich der Vorortmissionen des Hochkommissariats kein Gegenstand der Kooperation der beiden Organe

Russia’s war against Ukraine is not only a challenge to territorial borders. It is Putin’s war to change Europe’s order.

Russia’s war against Ukraine is not only a challenge to Europe’s territorial borders, writes Kristina Spohr. It is a war that challenges the character and rules that have governed the international system since 1945

Layer Analysis of the Structure of Water Confined in Vycor Glass

A Molecular Dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A layer analysis of the site-site radial distribution functions evidence the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer layer, close to the substrate, is strongly influenced by the water-substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer layer. The consequences on experimental determinations of the structural properties of water in confinement are discussed.Comment: 6 pages, 8 figures included in the text, one figure added, changes in the tex

After Merkel: Germany from peace to war

In the autumn of 2021, after Angela Merkel retired, her successor, Olaf Scholz, assumed power as head of a new coalition consisting of Social Democrats, Greens, and Free Democrats. Scholz had an ambitious agenda to reform Germany. Yet, within months, Russia launched its brutal military invasion of Ukraine. Overnight Scholz had to adapt to a Europe at war, which raised profound questions about Germany’s international role. Was its post-1945 ‘civilian power status’ still viable? What about its deep-seated ‘culture of restraint’? On 27 February 2022, three days into the war, Scholz addressed the Bundestag, boldly announcing a German Zeitenwende, an ‘epochal turn’ in the Federal Republic’s conduct of foreign and security affairs. This essay evaluates Scholz’s grand rhetorical vision a year on, questioning how much his claims for a major German foreign-policy revolution have yielded in practice. It will reveal that although Chancellor Scholz hoped to be seen as a decisive leader, his actions have so far been those of a beleaguered temporizer, unable to shake the age-old constraints tied to history, geography, and party politics. Crucially, his innate caution (reflected in long bouts of silences), his stubbornness, his unwillingness to lead from the front, as well as the structural limitations that Germany has long faced, have acted as breaks. Although the biggest tests are still to come, 2022 was a year of forced reinvention for both Scholz and Germany, and neither looked comfortable in assuming their new role