The anisotropic quantum antiferromagnet on the Sierpinski gasket: Ground state and thermodynamics

We investigate an antiferromagnetic s=1/2 quantum spin system with anisotropic spin exchange on a fractal lattice, the Sierpinski gasket. We introduce a novel approximative numerical method, the configuration selective diagonalization (CSD) and apply this method to the Sierpinski gasket with N=42. Using this and other methods we calculate ground state energies, spin gap, spin-spin correlations and specific heat data and conclude that the s=1/2 quantum antiferromagnet on the Sierpinski gasket shows a disordered magnetic ground state with a very short correlation length of about 1 and an, albeit very small, spin gap. This conclusion holds for Heisenberg as well a for XY exchange.Comment: LaTeX: 16 pages, 9 figures, 1 tabl

NATO-Russia tensions: Putin orders invasion of Ukraine; with the European security order in shambles, further escalation must be prevented

After military maneuvers near the borders, Moscow started a full-scale invasion of Ukraine on 24 February 2022. Before that, it has denied such an intent. It had been accusing Kiev of escalating the situation in the Donbas and the West of encouraging Ukraine to do so by taking sides in a biased manner. In mid-December 2021, it made clear in two draft treaties what it is after, namely preventing a further expansion of NATO to the east and obtaining binding assurances to this end. In doing so, it is in­voking the NATO-Russia agreements of the 1990s. Moscow voiced fears that Ukraine’s accession to NATO in particular would endanger Russia’s security and the strategic balance with the US. The US and NATO had signaled a willingness to engage in dia­logue on arms control issues, but they were not prepared to revise the principles of the European security order. Obviously, Moscow did not accept this and resorted to the use of force. It ignored the chance to embark on a new dialogue as an opportunity to de-escalate the situation and restore military predictability through arms control without abandoning principles. (author's abstract

Attack on the Open Skies Treaty: president Trump wants to withdraw from the Open Skies Treaty

President Donald Trump has announced that the United States will leave the multilateral Open Skies Treaty (OST). Russia could soon follow. The Trump administration would thus continue the US withdrawal from cooperative security and destroy an­other piece of the arms control architecture. Its continued dismantling, a new arms race, and the return of armed conflict and nuclear warfare scenarios threaten Europe's security and strategic stability. The OST permits cooperative observation flights over the territories of the States Parties. This allows for maintaining a minimum of military transparency and confidence-building, even in times of crisis. Such observation flights cannot be replaced by national satellite reconnaissance, especially since it is only available to a few states. Having the option to conduct independent observations is par­ticularly important for allies in regions of tension. Germany and European partners must make a strong commitment to maintaining the OST. (Autorenreferat

The end of the INF Treaty is looming: a new nuclear arms race can still be prevented

President Trump wants to terminate the Intermediate-Range Nuclear Forces (INF) Treaty signed in 1987. Its aim was to end the nuclear deployment race between the US and the then Soviet Union in Europe. Trump justified his intention by accusing Russia of violating the Treaty. Moscow denies this and also accuses Washington of being in breach of the Treaty. Trump has argued that China’s INF potential is also jeopardising the US's strategic position. However, this unilateral move by Washington contradicts NATO's recent positions. If the US were to withdraw from the INF Treaty, another cornerstone of the European security order and the global nuclear order would col­lapse. Unpredictability and destabilisation would increase. Europe must resolutely oppose the threat of a new nuclear arms race. It should insist on verifying the accu­sations from both sides under transparent and cooperative conditions and, if neces­sary, agree on additional stabilisation measures in order to preserve the Treaty or limit the consequences of a US withdrawal. (author's abstract

Technische Empfehlungen für den künftigen Einsatz von Plattfischsteerten in der Ostsee

Die Grundschleppnetzfischerei in der Ostsee konzentriert sich im wesentlichen auf den Fang von Dorsch- und Plattfisch. Neben der Dorschfischerei gibt es auch beim Fang von Plattfisch gebiets- und zeitweise erhebliche Beifänge an untermaßigen Fischen, die verworfen werden müssen. Für beide in Form und Verhalten sehr unterschiedlichen Fischarten können bis dato die gleichen Steerte eingesetzt werden. Um die durch diese Mix-Fischerei an der südlichen Ostseeküste gegebenen Probleme zu verdeutlichen und auf eine zukünftig differenzierte Behandlung für die technischen Maßnahmen zur Verbesserung der Selektivität hinzuwirken, werden seit 1998 vergleichende Untersuchungen mit Schleppnetzsteerten unterschiedlicher Konstruktion durchgeführt

Neue Universitätsbibliothek für Berlin - Gemeinschaftsprojekt der TU Berlin und der Universität der Künste Berlin

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Die Universitätsbibliothek der Technischen Universität Berlin erhält erstmalig in ihrer über 120-jährigen Geschichte ein ausschließlich für ihre Zwecke errichtetes, funktionsgerechtes Gebäude. Damit wird die Bibliothek für die Anforderungen des digitalen Medienzeitalters gerüstet und in die Lage versetzt, ihren Kundinnen und Kunden sowie den Beschäftigten zeitgemäße Arbeitsbedingungen und ein verbessertes Dienstleistungsspektrum in einer adäquaten räumlichen Umgebung bieten zu können. Dazu musste eine Reihe organisatorischer wie finanzieller Schwierigkeiten überwunden und ein Partner in Gestalt der Universitätsbibliothek der Universität der Künste gefunden werden. In dem fünfgeschossigen Gebäude werden drei Millionen Medien Platz finden. Es verfügt über eine Reihe, zum Teil sehr innovativer technischer Lösungen, die sowohl in der Bibliotheksfach- als auch in der Haustechnik zum Einsatz kommen.For the first time in its history of 120 years the university library of the „Technische Universität Berlin" will receive a new building which will both be functional and purpose built. The library will now be able to serve the needs of the digital age as well as provide up to date working conditions and improved services for its users and staff in new appropriate surroundings. To achieve this aim organisational and financial problems had to be overcome and a partner like the university library of the „Universität der Künste " had to be found. More than three million items will be housed in this five storied building, ft will also possess some very innovative solutions for library and domestic techniques

Traceability of Chemical Measurement Results

Traceability to recognised references, ultimately to the SI units, is an indispensable prerequisite for measurement results to be comparable and trustworthy and hence accepted worldwide. This holds also for chemical measurement results, particularly as these are often used as a basis for important decisions and agreements, for example in health care and environmental protection. The concept of traceability and the special problems associated with its application to chemical analysis as compared to metrology in general are described. Current approaches to establish traceability of chemical measurement results are reported. The most important development in the last two decades was the establishment of the Consultative Committee for Metrology in Chemistry under the Metre Convention, which provided the basis for an international reference framework for chemical measurements. In order to link up laboratory results anywhere in the world with this international reference framework, traceability structures on the national level are required. It is shown, using the demand for traceable chemical measurements in Germany as an example, how such structures can be established and efficiently used